CN114562881B - Method for recycling foundry waste sand based on vertical energy-saving roasting furnace - Google Patents
Method for recycling foundry waste sand based on vertical energy-saving roasting furnace Download PDFInfo
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- CN114562881B CN114562881B CN202210193995.2A CN202210193995A CN114562881B CN 114562881 B CN114562881 B CN 114562881B CN 202210193995 A CN202210193995 A CN 202210193995A CN 114562881 B CN114562881 B CN 114562881B
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- 239000004576 sand Substances 0.000 title claims abstract description 149
- 239000002699 waste material Substances 0.000 title claims abstract description 98
- 238000000034 method Methods 0.000 title claims abstract description 56
- 238000004064 recycling Methods 0.000 title claims abstract description 32
- 239000000463 material Substances 0.000 claims abstract description 177
- 239000007789 gas Substances 0.000 claims abstract description 48
- 230000008569 process Effects 0.000 claims abstract description 20
- 229920005989 resin Polymers 0.000 claims abstract description 9
- 239000011347 resin Substances 0.000 claims abstract description 9
- 238000002485 combustion reaction Methods 0.000 claims description 173
- 238000007599 discharging Methods 0.000 claims description 54
- 238000009835 boiling Methods 0.000 claims description 48
- 238000010438 heat treatment Methods 0.000 claims description 28
- 239000002912 waste gas Substances 0.000 claims description 26
- 230000007246 mechanism Effects 0.000 claims description 22
- 239000003507 refrigerant Substances 0.000 claims description 19
- 238000012216 screening Methods 0.000 claims description 19
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 claims description 18
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 18
- 229910052593 corundum Inorganic materials 0.000 claims description 16
- 239000010431 corundum Substances 0.000 claims description 16
- 238000003756 stirring Methods 0.000 claims description 15
- 239000002253 acid Substances 0.000 claims description 13
- 239000000243 solution Substances 0.000 claims description 13
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 13
- 238000001035 drying Methods 0.000 claims description 10
- 238000007885 magnetic separation Methods 0.000 claims description 10
- 238000002156 mixing Methods 0.000 claims description 10
- 230000007480 spreading Effects 0.000 claims description 10
- 238000003892 spreading Methods 0.000 claims description 10
- 238000001816 cooling Methods 0.000 claims description 9
- 238000005201 scrubbing Methods 0.000 claims description 9
- 238000005507 spraying Methods 0.000 claims description 9
- 239000004927 clay Substances 0.000 claims description 8
- 230000018044 dehydration Effects 0.000 claims description 7
- 238000006297 dehydration reaction Methods 0.000 claims description 7
- 238000005200 wet scrubbing Methods 0.000 claims description 7
- KXGFMDJXCMQABM-UHFFFAOYSA-N 2-methoxy-6-methylphenol Chemical compound [CH]OC1=CC=CC([CH])=C1O KXGFMDJXCMQABM-UHFFFAOYSA-N 0.000 claims description 6
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims description 6
- 239000011230 binding agent Substances 0.000 claims description 6
- 239000011259 mixed solution Substances 0.000 claims description 6
- 239000005011 phenolic resin Substances 0.000 claims description 6
- 229920001568 phenolic resin Polymers 0.000 claims description 6
- 235000019353 potassium silicate Nutrition 0.000 claims description 6
- NTHWMYGWWRZVTN-UHFFFAOYSA-N sodium silicate Chemical compound [Na+].[Na+].[O-][Si]([O-])=O NTHWMYGWWRZVTN-UHFFFAOYSA-N 0.000 claims description 6
- 238000009210 therapy by ultrasound Methods 0.000 claims description 6
- 238000005406 washing Methods 0.000 claims description 5
- 238000001471 micro-filtration Methods 0.000 claims description 4
- 238000003303 reheating Methods 0.000 claims description 3
- 239000003929 acidic solution Substances 0.000 claims description 2
- 239000011229 interlayer Substances 0.000 claims description 2
- 238000011069 regeneration method Methods 0.000 abstract description 24
- 230000000694 effects Effects 0.000 abstract description 22
- 239000012535 impurity Substances 0.000 abstract description 22
- 230000008929 regeneration Effects 0.000 abstract description 22
- 238000000227 grinding Methods 0.000 abstract description 7
- 238000011084 recovery Methods 0.000 abstract description 6
- 239000002918 waste heat Substances 0.000 abstract description 6
- 238000005265 energy consumption Methods 0.000 abstract description 5
- 239000000126 substance Substances 0.000 abstract description 4
- 238000004090 dissolution Methods 0.000 abstract description 3
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 126
- 238000005266 casting Methods 0.000 description 8
- 238000005516 engineering process Methods 0.000 description 4
- 239000000377 silicon dioxide Substances 0.000 description 4
- 238000007664 blowing Methods 0.000 description 3
- 230000007935 neutral effect Effects 0.000 description 3
- 238000007254 oxidation reaction Methods 0.000 description 3
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- 239000003082 abrasive agent Substances 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 239000000440 bentonite Substances 0.000 description 2
- 229910000278 bentonite Inorganic materials 0.000 description 2
- SVPXDRXYRYOSEX-UHFFFAOYSA-N bentoquatam Chemical compound O.O=[Si]=O.O=[Al]O[Al]=O SVPXDRXYRYOSEX-UHFFFAOYSA-N 0.000 description 2
- 239000011449 brick Substances 0.000 description 2
- 238000001354 calcination Methods 0.000 description 2
- 238000011161 development Methods 0.000 description 2
- 230000018109 developmental process Effects 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000009826 distribution Methods 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 239000011490 mineral wool Substances 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000003647 oxidation Effects 0.000 description 2
- 239000002245 particle Substances 0.000 description 2
- 239000000843 powder Substances 0.000 description 2
- 238000007528 sand casting Methods 0.000 description 2
- 229910000831 Steel Inorganic materials 0.000 description 1
- 238000005299 abrasion Methods 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 230000000903 blocking effect Effects 0.000 description 1
- 238000005119 centrifugation Methods 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 229910021652 non-ferrous alloy Inorganic materials 0.000 description 1
- 238000005554 pickling Methods 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 230000001172 regenerating effect Effects 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 239000010865 sewage Substances 0.000 description 1
- 239000007921 spray Substances 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F27—FURNACES; KILNS; OVENS; RETORTS
- F27B—FURNACES, KILNS, OVENS, OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
- F27B15/00—Fluidised-bed furnaces; Other furnaces using or treating finely-divided materials in dispersion
- F27B15/02—Details, accessories, or equipment peculiar to furnaces of these types
- F27B15/10—Arrangements of air or gas supply devices
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22C—FOUNDRY MOULDING
- B22C5/00—Machines or devices specially designed for dressing or handling the mould material so far as specially adapted for that purpose
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22C—FOUNDRY MOULDING
- B22C5/00—Machines or devices specially designed for dressing or handling the mould material so far as specially adapted for that purpose
- B22C5/04—Machines or devices specially designed for dressing or handling the mould material so far as specially adapted for that purpose by grinding, blending, mixing, kneading, or stirring
- B22C5/0409—Blending, mixing, kneading or stirring; Methods therefor
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23L—SUPPLYING AIR OR NON-COMBUSTIBLE LIQUIDS OR GASES TO COMBUSTION APPARATUS IN GENERAL ; VALVES OR DAMPERS SPECIALLY ADAPTED FOR CONTROLLING AIR SUPPLY OR DRAUGHT IN COMBUSTION APPARATUS; INDUCING DRAUGHT IN COMBUSTION APPARATUS; TOPS FOR CHIMNEYS OR VENTILATING SHAFTS; TERMINALS FOR FLUES
- F23L15/00—Heating of air supplied for combustion
- F23L15/04—Arrangements of recuperators
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F27—FURNACES; KILNS; OVENS; RETORTS
- F27B—FURNACES, KILNS, OVENS, OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
- F27B15/00—Fluidised-bed furnaces; Other furnaces using or treating finely-divided materials in dispersion
- F27B15/006—Equipment for treating dispersed material falling under gravity with ascending gases
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F27—FURNACES; KILNS; OVENS; RETORTS
- F27B—FURNACES, KILNS, OVENS, OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
- F27B15/00—Fluidised-bed furnaces; Other furnaces using or treating finely-divided materials in dispersion
- F27B15/02—Details, accessories, or equipment peculiar to furnaces of these types
- F27B15/08—Arrangements of devices for charging
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F27—FURNACES; KILNS; OVENS; RETORTS
- F27B—FURNACES, KILNS, OVENS, OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
- F27B15/00—Fluidised-bed furnaces; Other furnaces using or treating finely-divided materials in dispersion
- F27B15/02—Details, accessories, or equipment peculiar to furnaces of these types
- F27B15/09—Arrangements of devices for discharging
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F27—FURNACES; KILNS; OVENS; RETORTS
- F27B—FURNACES, KILNS, OVENS, OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
- F27B15/00—Fluidised-bed furnaces; Other furnaces using or treating finely-divided materials in dispersion
- F27B15/02—Details, accessories, or equipment peculiar to furnaces of these types
- F27B15/14—Arrangements of heating devices
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F27—FURNACES; KILNS; OVENS; RETORTS
- F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
- F27D17/00—Arrangements for using waste heat; Arrangements for using, or disposing of, waste gases
- F27D17/004—Systems for reclaiming waste heat
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E20/00—Combustion technologies with mitigation potential
- Y02E20/34—Indirect CO2mitigation, i.e. by acting on non CO2directly related matters of the process, e.g. pre-heating or heat recovery
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Dispersion Chemistry (AREA)
- Combustion & Propulsion (AREA)
- Environmental & Geological Engineering (AREA)
- Molds, Cores, And Manufacturing Methods Thereof (AREA)
- Processing Of Solid Wastes (AREA)
Abstract
The invention provides a method for recycling foundry waste sand based on a vertical energy-saving roasting furnace, which combines thermal regeneration and wet mechanical regeneration, and simultaneously adds grinding materials into the waste sand during thermal roasting to play a certain role in grinding, so that the effects of well removing surface resin and inorganic impurities of the mixed foundry waste sand are achieved by combining chemical dissolution, burning and friction, and the recovery rate is high. The invention further optimizes the thermal cycle during roasting, and is energy-saving, environment-friendly and efficient. The invention adopts a novel vertical energy-saving roasting furnace in the roasting process, adopts a unique secondary roasting process to carry out secondary roasting on tail gas and materials, and adopts secondary roasting to efficiently utilize waste heat, so that the energy consumption is low, the quality of the produced reclaimed sand is excellent and uniform, and the waste sand recycling effect is obvious.
Description
Technical Field
The invention belongs to the technical field of foundry sand recovery, and particularly relates to a method for recycling foundry waste sand based on a vertical energy-saving roasting furnace.
Background
About 90% of the castings in the foundry industry are produced using sand casting processes, and steel, iron and most nonferrous alloy castings are obtained using sand casting methods. The basic raw materials for manufacturing sand molds are foundry sand and sand binders, the common sand binders can be divided into organic type (such as phenolic resin, cold box resin and the like) and inorganic type (such as clay, water glass and the like), and the common foundry sand is silica sand (20-140 meshes of particles), 1 ton of foundry waste sand is produced by generally producing 1 ton of foundry, a large amount of silica sand is sourced from the nature, and the scale development of the foundry industry inevitably leads to the mass exploitation of natural silica sand resources and the discarding of a large amount of waste sand containing harmful substances. For sustainable development of the foundry industry, it is necessary to recycle foundry waste sand to protect our earth resources and environment. The currently disclosed method for recycling the foundry waste sand mainly comprises dry mechanical regeneration, thermal regeneration and wet mechanical regeneration: dry mechanical regeneration mainly adopts two methods of centrifugation and grinding to make the material impact friction to remove impurity film on the surface of waste sand so as to attain the goal of regeneration; the thermal regeneration is to bake the waste sand at 700-800 ℃ to burn out impurities on the surface of the silica sand so as to achieve the purpose of demoulding and regeneration; the wet mechanical regeneration is carried out by using water as a medium to infiltrate and scrub the waste sand, thereby removing the impurity film on the surface of the waste sand and achieving the purpose of stripping and regenerating.
Although the existing waste sand regeneration methods are various, the methods have a plurality of problems that the removal rate of an impurity film by dry mechanical regeneration is not more than 80%, the abrasion of sand by the regeneration process is large, a large amount of fine powder can be generated, the particle size of the regenerated sand is continuously reduced, on one hand, the recovery rate (not more than 80%) of the regenerated sand is greatly reduced, cracks can be generated on the surface of the obtained regenerated sand, the acid consumption value of the regenerated sand is high, the technical quality requirement of casting sand cannot be met, on the other hand, a large amount of fine powder is generated, and the technical pressure of secondary treatment and utilization is large; the thermal regeneration mode has good removal effect on organic impurity films with combustibility such as phenolic resin, cold box resin and the like, but has poor removal effect on inorganic impurity films such as clay, water glass and the like; and the tail gas after roasting needs to be purified; the wet mechanical regeneration method has good removal effect on inorganic impurity films with water solubility such as clay, water glass and the like, but has poor removal effect on organic impurity films such as phenolic resin, cold box resin and the like; and the subsequent sand, water and impurities are required to be further separated, and even the sewage generated in the production process is required to be treated by water.
In conclusion, the prior art aims at recycling a single waste sand type, and the research on the regeneration technology of the mixed type casting waste sand is less. The binder of the mixed type casting waste sand comprises an organic type (such as phenolic resin, cold box resin and the like) and an inorganic type (such as clay, water glass and the like), the recycling technology is integrated and optimized by comprehensively considering the characteristics of the binder and the advantages and disadvantages of a recycling method, and the recycling process step is adjusted, so that the mixed type casting waste sand is high in recycling rate and environment-friendly and safe.
Disclosure of Invention
The invention aims to provide a method for recycling foundry waste sand based on a vertical energy-saving roasting furnace, which combines thermal regeneration and wet mechanical regeneration, simultaneously adds grinding materials into the waste sand during thermal roasting to play a role in grinding, achieves the effect of well removing surface resin and inorganic impurities of the mixed foundry waste sand through chemical dissolution, burning and friction, and has high recovery rate; the invention further optimizes the thermal cycle during roasting, and is energy-saving, environment-friendly and efficient.
In order to achieve the above purpose, the invention adopts the following technical scheme:
A method for recycling foundry waste sand based on a vertical energy-saving roasting furnace comprises the following steps:
s1, crushing foundry waste sand, and then carrying out magnetic separation and screening to obtain pretreated waste sand;
S2, fully mixing the pretreated waste sand with an acid solution in a spraying mode, reacting for 10-20min while stirring, washing with water, and airing;
S3, adding brown corundum abrasive into the dried waste sand, and roasting in a roasting furnace at 700-900 ℃ for 5-10min; the addition amount of the brown corundum abrasive is 5-10% of the weight of the waste sand; cooling and screening after roasting to obtain a regenerated sand primary product;
S4, wet scrubbing is carried out on the reclaimed sand primary product, then rinsing, concentrating, dehydrating and drying are carried out.
The foundry waste sand treated by the present invention is a mixed foundry waste sand, wherein the binder includes, but is not limited to, phenolic resin, cold box resin, clay and water glass.
According to the method for recycling the foundry waste sand, a part of organic and inorganic impurities are removed by pickling, so that the subsequent roasting time is shortened; and then roasting friction is carried out, and the roasting temperature and time are adjusted and optimized. In the roasting process, the waste sand and the brown alumina abrasive are continuously rubbed, so that inorganic impurities such as bentonite and the like remained on the surface of the waste sand can be removed, and the burning-out of organic impurities is facilitated. The brown corundum abrasive has edges and corners on the surface, is high temperature resistant, and is a good abrasive choice. And finally, scrubbing the obtained reclaimed sand primary product by a wet method to remove a small part of residual impurities. The whole process can efficiently remove organic and inorganic impurities, the recovery rate of the mixed casting waste sand is high, the roasting time is reduced, and the energy is saved.
A method for recycling foundry waste sand based on a vertical energy-saving roasting furnace comprises the following steps:
s1, crushing foundry waste sand, and then carrying out magnetic separation and screening to obtain pretreated waste sand;
s2, adding brown fused alumina abrasive into the pretreated waste sand, and roasting in a roasting furnace at 700-900 ℃ for 5-10min; the addition amount of the brown corundum abrasive is 5-10% of the weight of the pretreated waste sand; cooling and screening after roasting to obtain a regenerated sand primary product;
S3, fully mixing the reclaimed sand primary product with an acid solution in a spraying mode, reacting for 10-20min while stirring, then scrubbing the reclaimed sand primary product by a wet method, rinsing with clear water, concentrating, dehydrating and drying.
According to the method for recycling the foundry waste sand, magnetic separation screening is performed first, then roasting friction is performed, and roasting temperature and time are adjusted and optimized. In the roasting process, the waste sand and the brown alumina abrasive are continuously rubbed, so that inorganic impurities such as bentonite and the like remained on the surface of the waste sand can be removed, and the burning-out of organic impurities is facilitated. The brown corundum abrasive has edges and corners on the surface, is high temperature resistant, and is a good abrasive choice. And finally, scrubbing the obtained reclaimed sand primary product by a wet method to remove a small part of residual impurities.
In the present invention, preferably, the acidic solution is a mixed solution of hydrofluoric acid and 10% sulfuric acid, and further preferably, the mass ratio of the two is 1-2:1. The mixed solution of hydrofluoric acid and 10% sulfuric acid has better solubility to most organic and inorganic impurities in the casting waste sand, and can remove a part of impurities.
In the present invention, preferably, the reclaimed sand primary product is simultaneously provided with stirring and ultrasonic treatment during wet scrubbing. Stirring and ultrasonic treatment to clean the sand surface.
In the invention, preferably, the dehydration adopts a microfiltration dehydration dryer, the microfiltration dehydration dryer comprises a cylindrical tank body, a feed inlet is arranged at the upper end of the tank body, a discharge outlet is arranged at the lower end of the tank body, an inner cavity is arranged in the tank body, a gap between the inner cavity and the tank body forms an air guide interlayer, an air inlet is arranged on the side wall of the tank body, a plurality of vent holes for communicating the tank body and the inner cavity are arranged on the side wall of the inner cavity, and an exhaust system is arranged in the inner cavity; the air inlet is filled with hot air at 80-100 ℃. The microwave dehydration dryer has the advantages of large contact surface between hot air and materials, small heat loss, full heat energy utilization, low energy consumption and capability of rapidly drying the materials.
In the invention, a novel vertical energy-saving roasting furnace is also designed, the top of the roasting furnace is provided with a feeding mechanism, the inside of the roasting furnace is sequentially provided with a primary combustion chamber, a secondary combustion chamber and a receiving mechanism from top to bottom,
The feeding mechanism comprises a feeding hopper, a screw feeder, a flow guide pipe and a material spreading disc, wherein the feeding hopper is used for containing materials to be roasted, an outlet of the feeding hopper is communicated with the screw feeder, the screw feeder is used for conveying the materials to be roasted into the roasting furnace along the flow guide pipe power, the materials to be roasted are enabled to flow downwards in a waterfall shape through the material spreading disc, and the materials flowing downwards are subjected to heat exchange with first waste gas discharged from the primary combustion chamber to form preheated materials;
A plurality of first burning guns are arranged on the side wall of the middle part of the primary combustion chamber and are used for heating and burning the preheated materials; the lower part of the primary combustion chamber is provided with a plurality of first heat exchange pipes, the upper end of each first heat exchange pipe is provided with a first tuyere, the lower end of each first heat exchange pipe is communicated with a first boiling air chamber, the first boiling air chamber is provided with a first air inlet, and hot air enters the first boiling air chamber through the first air inlet and then is blown into the primary combustion chamber through the first tuyere to heat boiling materials; the bottom of the primary combustion chamber is provided with a discharge device which is communicated with the secondary combustion chamber, and the roasted material is discharged into the secondary combustion chamber through the discharge device;
A pipeline is also communicated between the side wall of the upper part of the first-stage combustion chamber and the second-stage combustion chamber, a plurality of second combustion guns are arranged at the pipeline interface of the first-stage combustion chamber and are used for heating and incinerating volatile organic gas in the process of preheating materials, the organic gas and the first waste gas form mixed hot gas after being incinerated, and the mixed hot gas is conveyed to the second-stage combustion chamber along the pipeline and is used for reheating and combusting materials discharged by the discharging device; the lower part of the secondary combustion chamber is provided with a plurality of second heat exchange pipes, the upper end of each second heat exchange pipe is provided with a second tuyere, the lower end of each second heat exchange pipe is communicated with a second boiling air chamber, the second boiling air chamber is provided with a second air inlet, first cold air sequentially enters the second boiling air chamber and the second heat exchange pipes from the second air inlet, the temperature of the materials after the second heat exchange pipes and the secondary roasting is raised, and the materials are blown into the secondary combustion chamber from the second tuyere to heat the boiling materials;
The bottom of the secondary combustion chamber is communicated with a receiving mechanism, the receiving mechanism comprises a receiving hopper and a plurality of receiving pipes, the feeding end of each receiving pipe is communicated to the secondary combustion chamber, the discharging end extends to the receiving hopper, and the materials after secondary roasting are cooled after heat exchange with the second heat exchange pipe and are conveyed to the receiving hopper through each receiving pipe;
the heat exchanger comprises a refrigerant inlet, a refrigerant outlet, a heating medium inlet and a heating medium outlet, wherein the heating medium inlet is communicated with the secondary combustion chamber, the refrigerant outlet is communicated with the first air inlet, second waste gas discharged from the secondary combustion chamber enters the heat exchanger through the heating medium inlet and exchanges heat with second cold air entering the heat exchanger through the refrigerant inlet, the second waste gas after heat exchange is discharged from the heating medium outlet to form tail gas from the roasting furnace, the second cold air after heat exchange is heated to form hot air, and the hot air enters the first-stage combustion chamber to boil materials through the first boiling air chamber.
Preferably, the discharging device comprises a plurality of discharging pipes, the feeding end of each discharging pipe is communicated with the primary combustion chamber, the discharging end of each discharging pipe extends to the secondary combustion chamber, and the materials after primary roasting are conveyed to the discharging end through the feeding end of each discharging pipe; the material discharging pipes are respectively communicated to an air box, a third air inlet is formed in the air box, third cold air sequentially enters the air box, the guide pipes and the material discharging pipes from the third air inlet, and the materials after primary roasting are blown into the secondary combustion chamber from the material discharging ends of the material discharging pipes;
It is to be noted that, the material in the traditional roasting furnace discharges the in-process and appears blocking phenomenon easily, and is further, communicates respectively to bellows with each row material pipe through the pipe, utilizes the blowing effect of bellows, and from row material pipe inside to row material end direction blowing is favorable to smooth and easy discharge of material, guarantees the continuous operation performance of this novel vertical energy-conserving roasting furnace.
Further preferably, the material discharging pipes are distributed on two sides of the pipeline interface of the secondary combustion chamber in a fan shape, the discharge ends of the material discharging pipes face the pipeline interface of the secondary combustion chamber, and the material discharged by the material discharging pipes and the mixed hot gas conveyed by the pipeline form convection;
It should be noted that the novel vertical energy-saving roasting furnace mainly comprises the steps of placing materials in a first-stage combustion chamber, heating the materials by boiling, rapidly combusting organic matters on the surfaces of the materials, introducing high-temperature residual heat into a second-stage combustion chamber, and roasting the materials which are not completely roasted again, so that the materials which are difficult to combust can also have an efficient roasting treatment effect; further, the arrangement of the material discharging pipes is in fan-shaped distribution on two sides of the pipeline interface of the secondary combustion chamber, so that convection is formed between materials discharged from the primary combustion chamber and high-temperature waste heat, and the materials are subjected to secondary roasting while boiling, so that the surface quality of finally produced regenerated sand is more uniform and excellent, and the waste sand regeneration and reuse effect is obvious.
Preferably, the central axis of the primary combustion chamber coincides with the central axis of the secondary combustion chamber, and the height dimension of the primary combustion chamber is larger than that of the secondary combustion chamber; on the cross section in the vertical direction, the maximum width dimension of the primary combustion chamber is smaller than that of the secondary combustion chamber;
Further preferably, the height dimension of the primary combustion chamber is 2 to 4 times the height dimension of the secondary combustion chamber;
on the cross section in the vertical direction, the maximum width dimension of the primary combustion chamber is 1/4-1/2 of the maximum width dimension of the secondary combustion chamber;
It is to be noted that, this novel vertical energy-saving roasting furnace adopts unique secondary roasting technology, all carries out the secondary roasting to tail gas, material, and further, the first-stage combustion chamber includes the triplex to the calcination of material: on one hand, the height of the primary combustion chamber is 2-4 times of the height of the secondary combustion chamber, so that the stroke of the material to be roasted in the primary combustion chamber in the vertical direction is longer than that of the conventional vertical roasting furnace, and the material to be roasted and the hot waste gas discharged by the primary combustion chamber can be fully subjected to heat exchange, thereby achieving a good preheating effect; on the other hand, the maximum width of the primary combustion chamber is 1/4-1/2 of the maximum width of the secondary combustion chamber, so that the roasting treatment of the material by the combustion gun in the primary combustion chamber is more concentrated, the surface incineration and oxidation treatment of the material is more sufficient, and the roasting treatment efficiency is greatly improved.
Preferably, the side walls of the primary combustion chamber and the secondary combustion chamber are sequentially provided with refractory bricks, heat-insulating rock wool and a shell from inside to outside.
Preferably, the first heat exchange tube and the second heat exchange tube are both spiral heat exchange tubes, the inside of each spiral heat exchange tube is a high-pressure air channel, a long and narrow gap is formed between every two spiral heat exchange tubes, and the roasted material flows from top to bottom through the long and narrow gap and exchanges heat with the high-pressure air inside the spiral heat exchange tube.
Preferably, the pipeline is positioned at one side of the roasting furnace, and vertically extends to the top of the secondary combustion chamber along the outer wall of the primary combustion chamber;
Further preferably, the heat exchanger is positioned on one side of the roasting furnace far away from the pipeline, and the heat medium inlet of the heat exchanger faces downwards and is communicated with the top of the secondary combustion chamber;
It should be noted that, the novel vertical energy-saving roasting furnace adopts a unique secondary roasting process, including carrying out secondary roasting on tail gas and materials, further, in order to reasonably arrange the spatial positions of a pipeline and a heat exchanger, improve the space utilization rate of the roasting furnace, arrange the pipeline on one side of the roasting furnace, and arrange the heat exchanger on one side far away from the pipeline, on one hand, the mixed hot gas guided by the pipeline and the materials after primary roasting form convection, and the boiling materials are further subjected to secondary roasting at the same time of boiling the materials, so that the materials which are difficult to burn are treated, such as foundry sand, clay sand and the like, and also have efficient roasting treatment effects; on the other hand, the organic gas generated by roasting is burnt and oxidized after the secondary roasting treatment by distributing the positions of the pipeline and the heat exchanger, the second waste gas generated by the materials after the secondary roasting can be smoothly discharged out of the roasting furnace along with air convection by the heat exchanger, and the tail gas purification treatment is sufficient, so that the harm of the tail gas emission of the roasting furnace to the environment is effectively avoided.
Further preferably, the heat exchanger is a counter-flow heat exchanger;
In order to more efficiently recycle waste heat in the novel vertical energy-saving roasting furnace, further, through setting up counter-flow heat exchanger in the roasting furnace, the required air quantity of the roasting furnace in the secondary roasting process is smaller, so that the aim of remarkable energy-saving effect is achieved, and compared with the traditional vertical roasting furnace, the energy consumption is low, the regeneration cost is low, and the roasting furnace has excellent large-scale popularization and application prospects.
Compared with the prior art, the invention has the beneficial effects that:
1. According to the method for recycling the foundry waste sand, the thermal regeneration and the wet mechanical regeneration are combined, and meanwhile, the grinding material is added into the waste sand during the thermal roasting, so that a certain grinding effect is achieved, the effect of well removing the surface resin and the inorganic impurities of the mixed foundry waste sand is achieved through chemical dissolution, burning and friction, and the recovery rate is high; the invention further optimizes the thermal cycle during roasting, and is energy-saving, environment-friendly and efficient.
2. The invention adopts a novel vertical energy-saving roasting furnace in the roasting process, adopts a unique secondary roasting process to carry out secondary roasting on tail gas and materials, and adopts secondary roasting to efficiently utilize waste heat, so that the energy consumption is low, the quality of the produced reclaimed sand is excellent and uniform, and the waste sand recycling effect is obvious. The novel vertical energy-saving roasting furnace mainly comprises the steps of placing materials in a first-stage combustion chamber, heating the materials by boiling, rapidly combusting organic matters on the surfaces of the materials, introducing high-temperature residual heat into a second-stage combustion chamber, roasting the materials which are not completely roasted again, and enabling clay sand which is difficult to burn to be treated to have an efficient roasting treatment effect by the further action of abrasive materials; meanwhile, the organic gas generated by roasting is subjected to secondary roasting treatment and then is subjected to incineration and oxidization, so that the tail gas is sufficiently purified, and the harm of tail gas emission of a roasting furnace to the environment is effectively avoided.
Drawings
FIG. 1 is a schematic view of a neutral energy-saving roasting furnace according to the present invention;
FIG. 2 is a top view of a primary combustion chamber of the neutral energy-saving roasting furnace of the present invention;
FIG. 3 is a schematic diagram of the operation of the neutral energy-saving roasting furnace of the present invention;
fig. 4 is a process flow diagram of the present invention.
Reference numerals:
1. a feed mechanism; 11. a feed hopper; 12. a screw feeder; 13. a flow guiding pipe; 14. a spreading disc;
2. a primary combustion chamber; 21. a first combustion gun; 22. a first heat exchange tube; 22a, a first tuyere; 23. a first boiling plenum; 23a, a first air inlet; 24. a discharging device; 241. a discharge pipe; 242. a wind box; 242a, a third air inlet;
3. a secondary combustion chamber; 31. a second combustion gun; 32. a second heat exchange tube; 32a, a second tuyere; 33. a second boiling plenum; 33a, a second air inlet;
4. a material receiving mechanism; 41. a receiving hopper; 42. a material receiving pipe;
5. A heat exchanger; 51a, refrigerant inlet; 51b, a refrigerant outlet; 52a, a heating medium inlet; 52b, a heating medium outlet;
G1, a pipeline;
Q1, first waste gas and organic gas; q2, mixing hot gas; q3, second waste gas; q4, tail gas;
L1, first cold air; l2, second cold air; l3, third cold air; r1, hot air.
Detailed Description
The present invention will be further described in detail with reference to the following specific examples and the accompanying drawings, for the purpose of making the objects, technical solutions and advantages of the present invention more apparent, but the scope of the present invention is not limited to the examples.
Example 1:
A method for recycling foundry waste sand based on a vertical energy-saving roasting furnace comprises the following steps:
s1, crushing foundry waste sand, and then carrying out magnetic separation and screening to obtain pretreated waste sand;
s2, fully mixing the pretreated waste sand with an acid solution in a spraying mode, reacting for 10-20min while stirring, washing with water, and airing; the acid solution is a mixed solution of hydrofluoric acid and 10% sulfuric acid, and the mass ratio of the hydrofluoric acid to the 10% sulfuric acid is 1:1;
s3, adding brown corundum abrasive into the dried waste sand, and roasting in a roasting furnace at the temperature of 700 ℃ for 10min; the addition amount of the brown corundum abrasive is 6% of the weight of the waste sand; cooling and screening after roasting to obtain a regenerated sand primary product;
S4, performing wet scrubbing on the reclaimed sand primary product, wherein stirring and ultrasonic treatment are simultaneously carried out in the scrubbing process; and then rinsing, concentrating, dehydrating and drying.
Example 2:
A method for recycling foundry waste sand based on a vertical energy-saving roasting furnace comprises the following steps:
s1, crushing foundry waste sand, and then carrying out magnetic separation and screening to obtain pretreated waste sand;
S2, fully mixing the pretreated waste sand with an acid solution in a spraying mode, reacting for 10-20min while stirring, washing with water, and airing; the acid solution is a mixed solution of hydrofluoric acid and 10% sulfuric acid, and the mass ratio of the hydrofluoric acid to the 10% sulfuric acid is 2:1;
S3, adding brown corundum abrasive into the dried waste sand, and roasting in a roasting furnace at 900 ℃ for 5min; the addition amount of the brown corundum abrasive is 10% of the weight of the waste sand; cooling and screening after roasting to obtain a regenerated sand primary product;
S4, performing wet scrubbing on the reclaimed sand primary product, wherein stirring and ultrasonic treatment are simultaneously carried out in the scrubbing process; and then rinsing, concentrating, dehydrating and drying.
Example 3:
A method for recycling foundry waste sand based on a vertical energy-saving roasting furnace comprises the following steps:
s1, crushing foundry waste sand, and then carrying out magnetic separation and screening to obtain pretreated waste sand;
S2, fully mixing the pretreated waste sand with an acid solution in a spraying mode, reacting for 10-20min while stirring, washing with water, and airing; the acid solution is a mixed solution of hydrofluoric acid and 10% sulfuric acid, and the mass ratio of the hydrofluoric acid to the 10% sulfuric acid is 1.5:1;
s3, adding brown corundum abrasive into the dried waste sand, and roasting in a roasting furnace at 800 ℃ for 6min; the addition amount of the brown corundum abrasive is 7% of the weight of the waste sand; cooling and screening after roasting to obtain a regenerated sand primary product;
S4, performing wet scrubbing on the reclaimed sand primary product, wherein stirring and ultrasonic treatment are simultaneously carried out in the scrubbing process; and then rinsing, concentrating, dehydrating and drying.
Example 4:
A method for recycling foundry waste sand based on a vertical energy-saving roasting furnace comprises the following steps:
s1, crushing foundry waste sand, and then carrying out magnetic separation and screening to obtain pretreated waste sand;
S2, adding brown fused alumina abrasive into the pretreated waste sand, and roasting in a roasting furnace at 800 ℃ for 10min; the addition amount of the brown corundum abrasive is 8% of the weight of the pretreated waste sand; cooling and screening after roasting to obtain a regenerated sand primary product;
S3, fully mixing the reclaimed sand primary product with an acid solution in a spraying mode, reacting for 10-20min while stirring, then scrubbing the reclaimed sand primary product by a wet method, rinsing with clear water, concentrating, dehydrating and drying.
Example 5:
A method for recycling foundry waste sand based on a vertical energy-saving roasting furnace comprises the following steps:
s1, crushing foundry waste sand, and then carrying out magnetic separation and screening to obtain pretreated waste sand;
S2, adding brown fused alumina abrasive into the pretreated waste sand, and roasting in a roasting furnace at 900 ℃ for 8min; the addition amount of the brown corundum abrasive is 7% of the weight of the pretreated waste sand; cooling and screening after roasting to obtain a regenerated sand primary product;
S3, fully mixing the reclaimed sand primary product with an acid solution in a spraying mode, reacting for 10-20min while stirring, then scrubbing the reclaimed sand primary product by a wet method, rinsing with clear water, concentrating, dehydrating and drying.
The roasting operations in the above embodiments 1 to 5 all use the novel vertical energy-saving roasting furnace designed by the invention. The structure and application of the novel vertical energy-saving roasting furnace are specifically described below.
As shown in figures 1-3 of the drawings,
The top of the roasting furnace is provided with a feeding mechanism 1, the inside of the roasting furnace is sequentially provided with a primary combustion chamber 2, a secondary combustion chamber 3 and a receiving mechanism 4 from top to bottom, and the bottom of the roasting furnace is provided with a plurality of supporting feet for supporting the whole roasting furnace. The side walls of the primary combustion chamber 2 and the secondary combustion chamber 3 are sequentially provided with refractory bricks, heat-insulating rock wool and a shell from inside to outside.
The feeding mechanism 1 comprises a feeding hopper 11, a screw feeder 12, a flow guide pipe 13 and a spreading disc 14, and it is to be noted that the screw feeder 12 is provided with a motor (not shown) and a screw impeller (not shown), the screw impeller is in driving connection with the motor, the screw feeder 12 is used for quantitatively feeding materials, and the screw feeder 12 is horizontally placed or is obliquely inclined downwards by 8-12 degrees with the horizontal direction for ensuring uniform and stable material conveying;
Specifically, the feed hopper 11 is used for containing materials to be roasted, and the materials refer to foundry waste sand and abrasive materials to be roasted. The outlet of the feed hopper 11 is communicated with a screw feeder 12, the screw feeder 12 dynamically conveys the material to be roasted into the roasting furnace along a guide pipe 13, the material to be roasted is enabled to flow downwards in a waterfall shape through the material spreading disc 14, and the material flowing downwards exchanges heat with first waste gas discharged from the primary combustion chamber 2 to form a preheated material.
A plurality of first combustion guns 21 are arranged on the side wall of the middle of the primary combustion chamber 2, specifically, the number of the first combustion guns 21 is two, and the muzzle of the first combustion guns 21 sprays flame towards the inside of the primary combustion chamber 2 and is used for heating and burning preheated materials;
The lower part of the primary combustion chamber 2 is provided with a plurality of first heat exchange tubes 22, the upper ends of the first heat exchange tubes 22 are provided with first air nozzles 22a, the lower ends of the first heat exchange tubes are communicated with a first boiling air chamber 23, the first boiling air chamber 23 is provided with a first air inlet 23a, and hot air R1 enters the first boiling air chamber 23 through the first air inlet 23a and then is blown into the primary combustion chamber 2 through the first air nozzles 22a to heat boiling materials; the bottom of the primary combustion chamber 2 is provided with a discharge device 24, the discharge device 24 is communicated with the secondary combustion chamber 3, and roasted materials are discharged into the secondary combustion chamber 3 through the discharge device 24;
A pipeline G1 is also communicated between the upper side wall of the primary combustion chamber 2 and the secondary combustion chamber 3, a second burning gun 31 is arranged at the joint of the pipeline G1 of the primary combustion chamber 2 and is used for heating and burning organic gas volatilized in the process of preheating materials and exchanging heat, the organic gas and the first waste gas form mixed hot gas Q2 after being burned, the mixed hot gas Q2 is conveyed to the secondary combustion chamber 3 along the pipeline G1, and materials discharged by the discharging device 24 are heated and burned again;
The lower part of the secondary combustion chamber 3 is provided with a plurality of second heat exchange pipes 32, the upper end of each second heat exchange pipe 32 is provided with a second air nozzle 32a, the lower end of each second heat exchange pipe is communicated with a second boiling air chamber 33, the second boiling air chamber 33 is provided with a second air inlet 33a, first cold air L1 sequentially enters the second boiling air chamber 33 and the second heat exchange pipes 32 from the second air inlet 33a, the temperature is raised after the second heat exchange pipes 32 exchange heat with the secondarily roasted materials, and the secondarily roasted materials are blown into the secondary combustion chamber 3 from the second air nozzles 32a to heat the boiled materials; the first heat exchange tube 22 and the second heat exchange tube 32 are both spiral heat exchange tubes, the inside of each spiral heat exchange tube is a high-pressure air channel, a long and narrow gap is arranged between every two spiral heat exchange tubes, and the roasted material flows from top to bottom through the long and narrow gap and exchanges heat with the high-pressure air inside the spiral heat exchange tube.
The discharging device 24 comprises a plurality of discharging pipes 241, the feeding end of each discharging pipe 241 is communicated with the primary combustion chamber 2, the discharging end extends to the secondary combustion chamber 3, and the materials after primary roasting are conveyed to the discharging end through the feeding end of the discharging pipe 241; the discharge pipes 241 are respectively provided with a guide pipe near the discharge end, the guide pipes are respectively communicated to a bellows 242, a third air inlet 242a is arranged on the bellows 242, third cold air L3 sequentially enters the bellows 242, the guide pipes and the discharge end of the discharge pipe 241 from the third air inlet 242a, and the materials after primary roasting are blown into the secondary combustion chamber 3 from the discharge end of the discharge pipe 241; it should be noted that, the blockage phenomenon easily occurs in the material discharging process in the conventional roasting furnace, and further, each material discharging pipe 241 is respectively communicated to the air box 242 through a guide pipe, and the blowing effect of the air box 242 is utilized, so that the material is blown from the inside of the material discharging pipe 241 to the direction of the material discharging end, thereby being beneficial to smooth discharging of the material and ensuring the continuous working performance of the novel vertical energy-saving roasting furnace.
The discharging pipes 241 are distributed on two sides of a pipeline G1 interface of the secondary combustion chamber 3 in a fan shape, the discharging ends of the discharging pipes 241 face the pipeline G1 interface of the secondary combustion chamber 3, more specifically, the discharging ends of the discharging pipes 241 extend horizontally to form a section of elbow, the materials discharged by the discharging pipes 241 are transversely blown out from the elbow and form convection with mixed hot gas Q2 conveyed by the pipeline G1, and it is required that the novel vertical energy-saving roasting furnace mainly places the materials in the primary combustion chamber 2, rapidly burns organic matters on the surfaces of the materials by boiling and heats the materials, introduces high-temperature residual heat into the secondary combustion chamber 3, and roasting the materials which are not completely roasted again, so that the materials which are difficult to burn are also effective in roasting treatment effect; further, each material discharging pipe 241 is arranged on two sides of a pipeline G1 interface of the secondary combustion chamber 3 in a fan-shaped mode, so that convection is formed between materials discharged from the primary combustion chamber 2 and high-temperature waste heat, the materials are subjected to secondary roasting while boiling, the surface quality of finally produced regenerated sand is more uniform and excellent, and the waste sand regeneration and recycling effect is obvious.
The bottom of the secondary combustion chamber 3 is communicated with a receiving mechanism 4, the receiving mechanism 4 comprises a receiving hopper 41 and a plurality of receiving pipes 42, the feeding end of each receiving pipe 42 is communicated with the secondary combustion chamber 3, the discharging end extends to the receiving hopper 41, and the materials after secondary roasting are cooled after heat exchange with the second heat exchange pipe 32 and are conveyed to the receiving hopper 41 through each receiving pipe 42;
the heat exchanger 5 comprises a refrigerant inlet 51a, a refrigerant outlet 51b, a heat medium inlet 52a and a heat medium outlet 52b, wherein the heat medium inlet 52a is communicated with the secondary combustion chamber 3, the refrigerant outlet 51b is communicated with the first air inlet 23a, second waste gas Q3 discharged from the secondary combustion chamber 3 enters the heat exchanger 5 through the heat medium inlet 52a and exchanges heat with second cold air L2 entering the heat exchanger 5 through the refrigerant inlet 51a, the exchanged second waste gas Q3 is discharged from the heat medium outlet 52b to form tail gas Q4 from the roasting furnace, and the exchanged second cold air L2 is heated to form hot air R1; the hot air R1 reenters the primary combustion chamber 2 through the first boiling air chamber 23 to boil materials.
The pipeline G1 is positioned at one side of the roasting furnace and vertically extends to the top of the secondary combustion chamber 3 along the outer wall of the primary combustion chamber 2; specifically, the heat exchanger 5 is located at one side of the roasting furnace far away from the pipeline G1, and the heat medium inlet 52a of the heat exchanger 5 faces downwards and is communicated with the top of the secondary combustion chamber 3; furthermore, in order to reasonably arrange the spatial positions of the pipeline G1 and the heat exchanger 5 and improve the space utilization rate of the roasting furnace, the pipeline G1 is arranged on one side of the roasting furnace, the heat exchanger 5 is arranged on one side far away from the pipeline G1, on one hand, the mixed hot gas Q2 guided by the pipeline G1 and the primary roasted material form convection, and the boiling material is subjected to secondary roasting at the same time of boiling, so that the material which is difficult to burn is also effectively roasted; on the other hand, the organic gas generated by roasting is burnt and oxidized after the secondary roasting treatment by the positions of the distribution pipeline G1 and the heat exchanger 5, the second waste gas Q3 generated by the materials after the secondary roasting can be smoothly discharged out of the roasting furnace along with air convection by the heat exchanger 5, and the tail gas Q4 is sufficiently purified, so that the harm of the discharge of the tail gas Q4 of the roasting furnace to the environment is effectively avoided.
The heat exchanger 5 is a counter-flow heat exchanger; more specifically, a tube-in-tube type counter-flow heat exchanger is preferable; in order to more efficiently recycle waste heat in the novel vertical energy-saving roasting furnace, further, through setting up counter-flow heat exchanger in the roasting furnace, the required air quantity of the roasting furnace in the secondary roasting process is smaller, so that the aim of remarkable energy-saving effect is achieved, and compared with the traditional vertical roasting furnace, the energy consumption is low, the regeneration cost is low, and the roasting furnace has excellent large-scale popularization and application prospects.
The central axis of the primary combustion chamber 2 coincides with the central axis of the secondary combustion chamber 3, and the height dimension of the primary combustion chamber 2 is larger than that of the secondary combustion chamber 3; in the cross section in the vertical direction, the maximum width dimension of the primary combustion chamber 2 is smaller than the maximum width dimension of the secondary combustion chamber 3; further specifically, the height dimension of the primary combustion chamber 2 is 2 to 4 times the height dimension of the secondary combustion chamber 3; on the cross section in the vertical direction, the maximum width dimension of the primary combustion chamber 2 is 1/4-1/2 of the maximum width dimension of the secondary combustion chamber 3;
It should be noted that, this novel vertical energy-saving roasting furnace adopts unique secondary roasting technology, all carries out the secondary roasting to tail gas Q4, material, and is further, and the calcination of one-level combustion chamber 2 to the material includes three parts: on one hand, the height of the primary combustion chamber 2 is 2-4 times of the height of the secondary combustion chamber 3, so that the downward flow stroke of the material to be roasted in the primary combustion chamber 2 in the vertical direction is longer than that of the traditional vertical roasting furnace, and the material to be roasted and the hot waste gas discharged by the primary combustion chamber 2 can fully perform heat exchange, thereby achieving a good preheating effect; on the other hand, the maximum width dimension of the primary combustion chamber 2 is 1/4-1/2 of the maximum width dimension of the secondary combustion chamber 3, so that the roasting treatment of the material by the combustion gun in the primary combustion chamber 2 is more concentrated, the surface incineration and oxidation treatment of the material is more sufficient, and the roasting treatment efficiency is greatly improved.
The novel vertical energy-saving roasting furnace is applied in the specific fields:
the material to be roasted is put into a feed hopper 11, the outlet of the feed hopper 11 is communicated with a screw feeder 12, the screw feeder 12 dynamically conveys the material to be roasted into a roasting furnace along a guide pipe 13, the material to be roasted flows downwards in a waterfall shape through a material spreading disc 14, the material flowing downwards exchanges heat with first waste gas discharged from a primary combustion chamber 2 to form a preheated material, and organic gas is discharged;
The hot air R1 sprayed by the first air nozzle 22a of each first heat exchange tube 22 heats and boils in the falling process of the preheated material, in the process, the two first combustion guns 21 roast the preheated material at high temperature, the material after primary roasting is subjected to heat exchange with the first heat exchange tubes 22 and then falls to the discharging device 24, the heat exchange between the first heat exchange tubes 22 and the material can ensure that the temperature in the primary roasting furnace is maintained at a high temperature state, and the generated hot air R1 can preheat the material and effectively reduce the energy loss of the primary roasting furnace;
at this time, the once calcined material is conveyed to the discharge end through the feed end of the discharge pipe 241; the discharge pipes 241 are respectively provided with a guide pipe near the discharge end, each guide pipe is respectively communicated with a bellows 242, third cold air L3 sequentially enters the bellows 242, the guide pipes and the discharge end of the discharge pipe 241 from a third air inlet 242a, and the materials after primary roasting are blown into the secondary combustion chamber 3 from the discharge end of the discharge pipe 241;
The materials after primary roasting fall into the secondary combustion chamber 3, the first cold air L1 sequentially enters the second boiling air chamber 33 and the second heat exchange tube 32 from the second air inlet 33a, the temperature is raised after the heat exchange of the second heat exchange tube 32, and the boiling materials are blown into the secondary combustion chamber 3 from the second air nozzle 32a to be heated; at this time, the organic gas discharged after heat exchange of the preheated material is burnt by the second burning gun 31 to form mixed hot gas Q2 with the first waste gas, the mixed hot gas Q2 is conveyed to the secondary combustion chamber 3 along the pipeline G1, and forms convection with the material discharged by the discharging device 24, and the material is subjected to secondary heating roasting; the material after the secondary roasting exchanges heat with the second heat exchange tube 32, is cooled, and is conveyed to a receiving hopper 41 through each receiving pipe 42;
The second waste gas Q3 discharged from the secondary combustion chamber 3 enters the heat exchanger 5 through the heat medium inlet 52a and exchanges heat with the second cold air L2 entering the heat exchanger 5 through the refrigerant inlet 51a, the exchanged second waste gas Q3 is discharged from the roasting furnace through the heat medium outlet 52b to form tail gas Q4, the exchanged second cold air L2 is heated to form hot air R1 entering the primary combustion chamber 2, and the hot air R1 is recycled repeatedly.
Variations and modifications to the above would be obvious to persons skilled in the art to which the invention pertains from the foregoing description and teachings. Therefore, the invention is not limited to the specific embodiments disclosed and described above, but some modifications and changes of the invention should be also included in the scope of the claims of the invention. In addition, although specific terms are used in the present specification, these terms are for convenience of description only and do not limit the present invention in any way.
Claims (8)
1. The method for recycling the foundry waste sand based on the vertical energy-saving roasting furnace is characterized by comprising the following steps of:
S1, crushing foundry waste sand, and then carrying out magnetic separation and screening to obtain pretreated waste sand;
S2, fully mixing the pretreated waste sand with an acid solution in a spraying mode, reacting for 10-20min while stirring, washing with water, and airing;
S3, adding brown corundum abrasive into the dried waste sand, and roasting in a roasting furnace at 700-900 ℃ for 5-10min; the addition amount of the brown corundum abrasive is 5-10% of the weight of the waste sand; cooling and screening after roasting to obtain a regenerated sand primary product;
S4, wet scrubbing is carried out on the reclaimed sand primary product, and then rinsing, concentrating, dehydrating and drying are carried out;
The top of the roasting furnace is provided with a feeding mechanism, the inside of the roasting furnace is sequentially provided with a primary combustion chamber, a secondary combustion chamber and a receiving mechanism from top to bottom,
The feeding mechanism comprises a feeding hopper, a screw feeder, a flow guide pipe and a material spreading disc, wherein the feeding hopper is used for containing materials to be roasted, an outlet of the feeding hopper is communicated with the screw feeder, the screw feeder is used for conveying the materials to be roasted into the roasting furnace along the flow guide pipe power, the materials to be roasted are enabled to flow downwards in a waterfall shape through the material spreading disc, and the materials flowing downwards are subjected to heat exchange with first waste gas discharged from the primary combustion chamber to form preheated materials;
A plurality of first burning guns are arranged on the side wall of the middle part of the primary combustion chamber and are used for heating and burning the preheated materials; the lower part of the primary combustion chamber is provided with a plurality of first heat exchange pipes, the upper end of each first heat exchange pipe is provided with a first tuyere, the lower end of each first heat exchange pipe is communicated with a first boiling air chamber, the first boiling air chamber is provided with a first air inlet, and hot air enters the first boiling air chamber through the first air inlet and then is blown into the primary combustion chamber through the first tuyere to heat boiling materials; the bottom of the primary combustion chamber is provided with a discharge device which is communicated with the secondary combustion chamber, and the roasted material is discharged into the secondary combustion chamber through the discharge device;
A pipeline is also communicated between the side wall of the upper part of the first-stage combustion chamber and the second-stage combustion chamber, a plurality of second combustion guns are arranged at the pipeline interface of the first-stage combustion chamber and are used for heating and incinerating volatile organic gas in the process of preheating materials, the organic gas and the first waste gas form mixed hot gas after being incinerated, and the mixed hot gas is conveyed to the second-stage combustion chamber along the pipeline and is used for reheating and combusting materials discharged by the discharging device; the lower part of the secondary combustion chamber is provided with a plurality of second heat exchange pipes, the upper end of each second heat exchange pipe is provided with a second tuyere, the lower end of each second heat exchange pipe is communicated with a second boiling air chamber, the second boiling air chamber is provided with a second air inlet, first cold air sequentially enters the second boiling air chamber and the second heat exchange pipes from the second air inlet, the temperature of the materials after the second heat exchange pipes and the secondary roasting is raised, and the materials are blown into the secondary combustion chamber from the second tuyere to heat the boiling materials;
The bottom of the secondary combustion chamber is communicated with a receiving mechanism, the receiving mechanism comprises a receiving hopper and a plurality of receiving pipes, the feeding end of each receiving pipe is communicated to the secondary combustion chamber, the discharging end extends to the receiving hopper, and the materials after secondary roasting are cooled after heat exchange with the second heat exchange pipe and are conveyed to the receiving hopper through each receiving pipe;
the heat exchanger comprises a refrigerant inlet, a refrigerant outlet, a heating medium inlet and a heating medium outlet, wherein the heating medium inlet is communicated with the secondary combustion chamber, the refrigerant outlet is communicated with the first air inlet, second waste gas discharged from the secondary combustion chamber enters the heat exchanger through the heating medium inlet and exchanges heat with second cold air entering the heat exchanger through the refrigerant inlet, the second waste gas after heat exchange is discharged from the heating medium outlet to form tail gas from the roasting furnace, the second cold air after heat exchange is heated to form hot air, and the hot air enters the first-stage combustion chamber to boil materials through the first boiling air chamber.
2. The method for recycling the foundry waste sand based on the vertical energy-saving roasting furnace is characterized by comprising the following steps of:
S1, crushing foundry waste sand, and then carrying out magnetic separation and screening to obtain pretreated waste sand;
S2, adding brown fused alumina abrasive into the pretreated waste sand, and roasting in a roasting furnace at 700-900 ℃ for 5-10min; the addition amount of the brown corundum abrasive is 5-10% of the weight of the pretreated waste sand; cooling and screening after roasting to obtain a regenerated sand primary product;
S3, fully mixing the reclaimed sand primary product with an acid solution in a spraying mode, reacting for 10-20min while stirring, then scrubbing the reclaimed sand primary product by a wet method, rinsing with clear water, concentrating, dehydrating and drying;
The top of the roasting furnace is provided with a feeding mechanism, the inside of the roasting furnace is sequentially provided with a primary combustion chamber, a secondary combustion chamber and a receiving mechanism from top to bottom,
The feeding mechanism comprises a feeding hopper, a screw feeder, a flow guide pipe and a material spreading disc, wherein the feeding hopper is used for containing materials to be roasted, an outlet of the feeding hopper is communicated with the screw feeder, the screw feeder is used for conveying the materials to be roasted into the roasting furnace along the flow guide pipe power, the materials to be roasted are enabled to flow downwards in a waterfall shape through the material spreading disc, and the materials flowing downwards are subjected to heat exchange with first waste gas discharged from the primary combustion chamber to form preheated materials;
A plurality of first burning guns are arranged on the side wall of the middle part of the primary combustion chamber and are used for heating and burning the preheated materials; the lower part of the primary combustion chamber is provided with a plurality of first heat exchange pipes, the upper end of each first heat exchange pipe is provided with a first tuyere, the lower end of each first heat exchange pipe is communicated with a first boiling air chamber, the first boiling air chamber is provided with a first air inlet, and hot air enters the first boiling air chamber through the first air inlet and then is blown into the primary combustion chamber through the first tuyere to heat boiling materials; the bottom of the primary combustion chamber is provided with a discharge device which is communicated with the secondary combustion chamber, and the roasted material is discharged into the secondary combustion chamber through the discharge device;
A pipeline is also communicated between the side wall of the upper part of the first-stage combustion chamber and the second-stage combustion chamber, a plurality of second combustion guns are arranged at the pipeline interface of the first-stage combustion chamber and are used for heating and incinerating volatile organic gas in the process of preheating materials, the organic gas and the first waste gas form mixed hot gas after being incinerated, and the mixed hot gas is conveyed to the second-stage combustion chamber along the pipeline and is used for reheating and combusting materials discharged by the discharging device; the lower part of the secondary combustion chamber is provided with a plurality of second heat exchange pipes, the upper end of each second heat exchange pipe is provided with a second tuyere, the lower end of each second heat exchange pipe is communicated with a second boiling air chamber, the second boiling air chamber is provided with a second air inlet, first cold air sequentially enters the second boiling air chamber and the second heat exchange pipes from the second air inlet, the temperature of the materials after the second heat exchange pipes and the secondary roasting is raised, and the materials are blown into the secondary combustion chamber from the second tuyere to heat the boiling materials;
The bottom of the secondary combustion chamber is communicated with a receiving mechanism, the receiving mechanism comprises a receiving hopper and a plurality of receiving pipes, the feeding end of each receiving pipe is communicated to the secondary combustion chamber, the discharging end extends to the receiving hopper, and the materials after secondary roasting are cooled after heat exchange with the second heat exchange pipe and are conveyed to the receiving hopper through each receiving pipe;
the heat exchanger comprises a refrigerant inlet, a refrigerant outlet, a heating medium inlet and a heating medium outlet, wherein the heating medium inlet is communicated with the secondary combustion chamber, the refrigerant outlet is communicated with the first air inlet, second waste gas discharged from the secondary combustion chamber enters the heat exchanger through the heating medium inlet and exchanges heat with second cold air entering the heat exchanger through the refrigerant inlet, the second waste gas after heat exchange is discharged from the heating medium outlet to form tail gas from the roasting furnace, the second cold air after heat exchange is heated to form hot air, and the hot air enters the first-stage combustion chamber to boil materials through the first boiling air chamber.
3. The method for recycling foundry waste sand based on the vertical energy-saving roasting furnace according to claim 1 or 2, wherein the discharging device comprises a plurality of discharging pipes, the feeding end of each discharging pipe is communicated with the primary combustion chamber, the discharging end extends to the secondary combustion chamber, and the materials after primary roasting are conveyed to the discharging end through the feeding end of the discharging pipe; each row of material pipe is close to discharge end department and all is equipped with the pipe, and each pipe communicates to an bellows respectively, be equipped with the third air intake on the bellows, the third cold wind gets into bellows, pipe and row material's discharge end in proper order from the third air intake, blows in the secondary combustion chamber with the material after once roasting from row material's discharge end.
4. The method for recycling foundry waste sand based on the vertical energy-saving roasting furnace according to claim 3, wherein the material discharging pipes are distributed on two sides of the pipeline interface of the secondary combustion chamber in a fan shape, the material discharging ends of the material discharging pipes face the pipeline interface of the secondary combustion chamber, and the material discharged by the material discharging pipes and the mixed hot gas conveyed by the pipeline form convection.
5. The method for recycling foundry waste sand based on the vertical energy-saving roasting furnace according to claim 1 or 2, wherein the acidic solution is a mixed solution of hydrofluoric acid and 10% sulfuric acid.
6. The method for recycling foundry waste sand based on the vertical energy-saving roasting furnace according to claim 1 or 2, wherein the primary product of the recycled sand is simultaneously provided with stirring and ultrasonic treatment in the wet scrubbing process.
7. The method for recycling foundry waste sand based on the vertical energy-saving roasting furnace according to claim 1 or 2, wherein the dehydration adopts a microfiltration dehydration dryer, the microfiltration dehydration dryer comprises a cylindrical tank body, a feed inlet is arranged at the upper end of the tank body, a discharge outlet is arranged at the lower end of the tank body, an inner cavity is arranged in the tank body, a gap between the inner cavity and the tank body forms an air guide interlayer, an air inlet is arranged on the side wall of the tank body, a plurality of vent holes for communicating the tank body and the inner cavity are arranged on the side wall of the inner cavity, and an exhaust system is arranged in the inner cavity; the air inlet is filled with hot air at 80-100 ℃.
8. The method for recycling foundry waste sand based on the vertical energy-saving roasting furnace according to claim 1 or 2, wherein the foundry waste sand is mixed foundry waste sand, and the binder comprises phenolic resin, cold box resin, clay and water glass.
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| CN115415477B (en) * | 2022-11-03 | 2023-03-24 | 托普工业(江苏)有限公司 | 3D prints casting sand mould recovery processing system |
| CN115846588B (en) * | 2022-11-17 | 2024-01-12 | 柳晶科技集团股份有限公司 | Regeneration method of foundry inorganic waste sand and regenerated sand |
| CN116727600B (en) * | 2023-06-16 | 2024-01-26 | 广东万嘉精铸材料有限公司 | Precision casting surface sand powder and preparation method thereof |
| CN117718433B (en) * | 2024-02-06 | 2024-04-26 | 康硕(山西)智能制造有限公司 | Automatic cleaning and recycling device for precision casting molding sand |
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