CN110668477B - Process and system for producing sintered magnesia by taking magnesium hydroxide as raw material - Google Patents
Process and system for producing sintered magnesia by taking magnesium hydroxide as raw material Download PDFInfo
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- CN110668477B CN110668477B CN201911059054.4A CN201911059054A CN110668477B CN 110668477 B CN110668477 B CN 110668477B CN 201911059054 A CN201911059054 A CN 201911059054A CN 110668477 B CN110668477 B CN 110668477B
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
- C01F5/00—Compounds of magnesium
- C01F5/02—Magnesia
- C01F5/06—Magnesia by thermal decomposition of magnesium compounds
- C01F5/08—Magnesia by thermal decomposition of magnesium compounds by calcining magnesium hydroxide
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
- C04B35/622—Forming processes; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
- C04B35/626—Preparing or treating the powders individually or as batches ; preparing or treating macroscopic reinforcing agents for ceramic products, e.g. fibres; mechanical aspects section B
- C04B35/62605—Treating the starting powders individually or as mixtures
- C04B35/62645—Thermal treatment of powders or mixtures thereof other than sintering
- C04B35/6267—Pyrolysis, carbonisation or auto-combustion reactions
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
- C04B35/66—Monolithic refractories or refractory mortars, including those whether or not containing clay
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2006/00—Physical properties of inorganic compounds
- C01P2006/10—Solid density
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2006/00—Physical properties of inorganic compounds
- C01P2006/80—Compositional purity
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- 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
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P20/00—Technologies relating to chemical industry
- Y02P20/10—Process efficiency
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- 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
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P20/00—Technologies relating to chemical industry
- Y02P20/10—Process efficiency
- Y02P20/129—Energy recovery, e.g. by cogeneration, H2recovery or pressure recovery turbines
Abstract
The invention relates to a process and a system for producing sintered magnesia by taking magnesium hydroxide as a raw material, wherein the system comprises a filter cake storage bin, a variable combined feeding unit, a quick drying device, a shaftless screw conveyor, a first bucket elevator, a suspension roasting device, a high-temperature high-pressure ball system, a second bucket elevator, a shaft kiln feeding bin and a high-temperature shaft kiln; feeding a magnesium hydroxide filter cake prepared from seawater or brine serving as a raw material through a variable combination feeder unit, conveying the magnesium hydroxide filter cake into a rapid drying device for drying, conveying the dried magnesium hydroxide powder into a suspension roasting device by using a shaftless screw conveyor for roasting, and obtaining high-activity magnesium oxide powder; and (3) circularly hot-pressing the high-activity magnesia powder by a high-temperature high-pressure ball pressing system, and then sending the high-activity magnesia powder into a high-temperature shaft kiln for calcination to obtain a sintered magnesia product. The invention has short process flow, low production energy consumption, little environmental pollution and low production cost; the prepared high-purity and high-density sintered magnesia product can replace sintered magnesia products and electrofusion products calcined by magnesite.
Description
Technical Field
The invention relates to the technical field of magnesium material production, in particular to a process and a system for producing sintered magnesia by taking magnesium hydroxide as a raw material.
Background
Currently, there are two main methods for producing magnesite in the world: the magnesium hydroxide is prepared by calcining or electrofusion of natural magnesite, and the magnesium hydroxide prepared from seawater or brine is calcined at high temperature. The obtained sintered magnesia product with high density and high purity is always the development direction of magnesia production.
The Liaoning region of China has high-quality magnesite resources, and the magnesite resources become the main production base and export base of the global magnesite market from the 90 th century. For a long timeThe obtained disordered and rough mining results in the reduction of ore quality, resource waste, ecological damage and serious environmental pollution. Meanwhile, the sea water and brine resources in China are rich, tens of millions of tons of concentrated sea water and brine rich in magnesium can be produced each year, the magnesium sand product produced by taking the magnesium hydroxide chemically treated by the sea water and brine as the raw material has the purity more easily reaching more than 98 percent and the volume density reaching 3.45g/cm 3 The above; however, the prior art for producing magnesia by using magnesium hydroxide as a raw material generally has the problems of long process flow and high production cost, and related domestic production enterprises are few.
Aiming at the problems of increasingly deficient magnesite resources, particularly high-quality magnesite resources, and serious ecological environment damage, the invention intensively researches and develops a method for preparing sintered magnesite by taking magnesium hydroxide prepared from seawater or brine as a raw material, which is beneficial to shortening the process flow, popularizing the energy-saving and consumption-reducing technology and reducing the production cost, and the product can finally replace magnesite calcined magnesite products, and has extremely important significance for promoting sustainable development of magnesium resources and energy conservation and environmental protection.
Disclosure of Invention
The invention provides a process and a system for producing sintered magnesia by taking magnesium hydroxide as a raw material, which have the advantages of short process flow, low production energy consumption, little environmental pollution and low production cost; the prepared high-purity and high-density sintered magnesia product can replace sintered magnesia products and electric melting products calcined by magnesite, is used as a raw material for producing various magnesia refractory bricks and unshaped refractory materials, and is widely applied to high-temperature industries such as metallurgy, petrochemical industry, color industry and the like; is beneficial to reducing natural resource and energy consumption, improving ecological environment and realizing sustainable development of magnesium resources.
In order to achieve the above purpose, the invention is realized by adopting the following technical scheme:
the process for producing sintered magnesia by using magnesium hydroxide as raw material uses magnesium hydroxide filter cake prepared from sea water or bittern as raw material, and adopts variable combination feeder unit to feed, and feeds into quick drying device to make drying, and uses shaftless screw conveyor to convey the dried magnesium hydroxide powder into suspension roasting device to make roasting so as to obtain the high-activity magnesium oxide powder; and (3) circularly hot-pressing the high-activity magnesia powder by a high-temperature high-pressure ball pressing system, and then sending the high-activity magnesia powder into a high-temperature shaft kiln for calcination to obtain a sintered magnesia product.
The variable combined feeding unit consists of a manual gate valve, a star-shaped feeding machine, a screw conveyor, a crushing machine and a variable frequency motor, and a feeding end of the variable combined feeding unit is provided with the manual gate valve; the star-shaped feeder and the screw conveyor are driven by a variable frequency motor, and a feeding end of the screw conveyor is provided with a breaking machine; the manual gate valve can directly adjust the feeding amount, the shredder is used for scattering the agglomerated materials, the star-shaped feeder and the screw conveyor are used for forced feeding and conveying, and the shredder has the functions of further scattering and homogenizing the materials; the variable frequency motor is used for adjusting the feeding speed.
The rapid drying device is used for drying by utilizing the waste heat of the flue gas of the suspension roasting device, the inlet temperature of the hot flue gas is 300-450 ℃, and the exhaust temperature of the flue gas is 50-150 ℃; the flue gas outlet is connected with a flue gas purifying treatment system; the water content of the dried magnesium hydroxide is less than or equal to 5 percent.
The suspension roasting device utilizes the waste heat of the flue gas of the high-temperature shaft kiln to roast, the inlet temperature of the hot flue gas is 500-650 ℃, and the exhaust temperature of the flue gas is 300-450 ℃; the suspension roasting device is provided with 2 to 5 cyclones.
The high-temperature high-pressure ball pressing system comprises a pre-pressing device and a high-pressure device, and is used for circularly hot-pressing the light burned magnesium oxide, wherein the hot-pressing temperature is 400-600 ℃; the line pressure of the ball press is 80-110 kN/cm; the ball groove is almond-shaped or peach-shaped, and the capacity is 10 cm to 20cm 3 。
The high-temperature shaft kiln takes heavy oil or natural gas as fuel, and is controlled by a PLC control system to carry out continuous production, and the calcination temperature is 1800-2000 ℃.
The MgO content of the produced sintered magnesia is more than or equal to 98 percent, and the volume density is more than or equal to 3.45g/cm 3 。
The invention relates to a system for producing sintered magnesia by taking magnesium hydroxide as a raw material, which comprises a filter cake storage bin, a variable joint feeding unit, a quick drying device, a shaftless screw conveyor, a first bucket elevator, a suspension roasting device, a high-temperature high-pressure ball pressing system, a second bucket elevator, a shaft kiln feed bin and a high-temperature shaft kiln, wherein the filter cake storage bin is connected with the variable joint feeding unit; the discharge port of the filter cake storage bin is connected with the feed port of the variable combination feeding unit; the discharge port of the variable combined feeding unit is connected with the feed port of the quick drying device, the discharge port of the quick drying device is connected with the feed port of the shaftless screw conveyor, the discharge port of the shaftless screw conveyor is connected with the feed end of the bucket elevator I, and the discharge end of the bucket elevator I is connected with the feed port of the suspension roasting device; the discharge port of the suspension roasting device is connected with the feed port of the high-temperature high-pressure ball system, the discharge port of the high-temperature high-pressure ball system is connected with the feed end of the bucket elevator II, and the discharge end of the bucket elevator II is connected with the feed port of the shaft kiln feed bin, and the feed port of the shaft kiln feed bin is connected with the feed port of the high-temperature shaft kiln.
The flue gas outlet of the high-temperature shaft kiln is connected with the roasting heat source inlet of the suspension roasting device through a first flue gas pipeline, and the flue gas outlet of the suspension roasting device is connected with the drying heat source inlet of the quick drying device through a second flue gas pipeline; the flue gas outlet of the quick drying device is connected with the flue gas inlet of the flue gas purifying treatment system through a third flue gas pipeline, and the clean flue gas outlet of the flue gas purifying treatment system is connected with a chimney.
The variable combined feeder unit, the quick drying device, the shaftless screw conveyor, the suspension roasting device, the high-temperature high-pressure ball pressing system and the high-temperature shaft kiln are all of a fully-closed structure.
Compared with the prior art, the invention has the beneficial effects that:
1) Compared with the traditional high-purity magnesia production process, the preparation process of the sintered magnesia is a continuous and totally-enclosed production process, the magnesium hydroxide raw material is prepared into the sintered magnesia through the processes of drying, roasting, removing bound water, high-temperature ball pressing, high-temperature sintering and the like, and only one set of fuel system and one set of kiln flue gas purifying treatment and smoke discharging system are arranged, so that the flue gas waste heat is fully utilized, the process is simple, the flow is short, the environmental pollution is small, and the energy-saving and environment-friendly benefits are good;
2) The variable combined feeder unit is adopted for feeding, the equipment structure is compact, the whole is closed, the use site installation is convenient, and no dust overflows; the manual gate valve can directly adjust the material quantity, reduce the running resistance of the star feeder, and completely cut off the material flow, thereby being convenient for maintenance operation in failure; the breaking machine is used for breaking up the agglomerated materials, so that the subsequent conveying is convenient; the star feeder and the screw conveyor can carry out forced feeding and conveying, and have the functions of further scattering and homogenizing, so that the drying efficiency of the magnesium hydroxide filter cake can be improved; the variable frequency motor transmission system is adopted, so that the feeding speed can be adjusted, and the automatic control is realized;
3) The shaftless screw conveyor adopts totally-enclosed conveying, the screw surface is easy to clean, the structure is compact, the space is saved, the energy consumption is low, the magnesium hydroxide is not polluted, leaked and blocked easily;
4) The suspension roasting device is adopted to remove the bound water of the magnesium hydroxide at the temperature of 500-650 ℃, because the lower the roasting temperature is, the smaller the size of magnesium oxide grains obtained by decomposition is, and the better the high-temperature sintering performance is after ball pressing. The traditional magnesite two-step calcination method is used for producing high-purity magnesia, active magnesia can be produced only by light calcination at about 900 ℃, and magnesium hydroxide starts to decompose and unbound water at about 300 ℃, so that double vacancies can be produced after the bound water is removed, the structure is loose, defects are increased, and the sintering of magnesia is promoted;
5) The suspension roasting device is divided into a preheating section and a roasting section, a combustion system is not arranged, the roasting temperature is low, the number of the cyclone cylinders is reduced, the structure is simple, and the operation is convenient; the heat source of the suspension roasting device is from the hot flue gas of the high-temperature shaft kiln, and the flue gas exhausted by the suspension roasting device can be used for the secondary use of the quick drying device, so that the production cost and the energy consumption are reduced, and the energy conservation and the consumption reduction are realized;
6) The roasted magnesium oxide is directly hot-pressed without cooling, so that the volume shrinkage of the cooled magnesium oxide can be avoided, and the balling volume density can be improved by 0.1-0.3 g/cm compared with the prior art 3 The method comprises the steps of carrying out a first treatment on the surface of the The circulating ball pressing process (the undersize crushed aggregates return system is used for re-pressing balls) is adopted, so that the problem of difficult ball forming of powder materials is solved, and the ball forming rate is improved;
7) The high-temperature shaft kiln is fully automatically controlled by a PLC control system, and the whole system is provided with a set of fuel system only at the high-temperature shaft kiln, so that the waste heat of flue gas is fully utilized;
8) The prepared sintered magnesia has high purity, less impurity, uniform and stable quality and volume density up to 3.45g/cm 3 The above. The refractory product prepared by using the material has good high-temperature performance, heat resistance, slag resistance and erosion resistance, long service life, high quality and wide application and prospect.
Drawings
FIG. 1 is a schematic diagram of a system for producing sintered magnesia using magnesium hydroxide as a raw material according to the present invention.
FIG. 2 is a flow chart of a process for producing sintered magnesia by using magnesium hydroxide as a raw material according to the invention.
In the figure: 1. the device comprises a filter cake storage bin 2, a variable joint feeding unit 3, a quick drying device 4, a shaftless screw conveyor 5, a first bucket elevator 6, a suspension roasting device 7, a high-temperature high-pressure ball pressing system 8, a second bucket elevator 9, a shaft kiln feeding bin 10, a high-temperature shaft kiln 11, a flue gas purifying treatment system 12, a chimney 13 and a fuel system
Detailed Description
The following is a further description of embodiments of the invention, taken in conjunction with the accompanying drawings:
as shown in fig. 1 and 2, in the process for producing sintered magnesia by using magnesium hydroxide as a raw material, a magnesium hydroxide filter cake prepared from seawater or brine is used as a raw material, fed by a variable combination feeder unit 2, sent into a rapid drying device 3 for drying, and the dried magnesium hydroxide powder is conveyed into a suspension roasting device 6 by a shaftless screw conveyor 4 for roasting to obtain high-activity magnesia powder; and (3) circularly hot-pressing the high-activity magnesia powder by a high-temperature high-pressure ball system 7, and then delivering the magnesia powder into a high-temperature shaft kiln 10 for calcination to obtain a sintered magnesia product.
The variable combined feeder unit 2 consists of a manual gate valve, a star feeder, a screw conveyor, a shredder and a variable frequency motor, and the feeding end of the variable combined feeder unit 2 is provided with the manual gate valve; the star-shaped feeder and the screw conveyor are driven by a variable frequency motor, and a feeding end of the screw conveyor is provided with a breaking machine; the manual gate valve can directly adjust the feeding amount, the shredder is used for scattering the agglomerated materials, the star-shaped feeder and the screw conveyor are used for forced feeding and conveying, and the shredder has the functions of further scattering and homogenizing the materials; the variable frequency motor is used for adjusting the feeding speed.
The rapid drying device 3 utilizes the waste heat of the flue gas of the suspension roasting device 6 to carry out drying, the inlet temperature of the hot flue gas is 300-450 ℃, and the exhaust temperature of the flue gas is 50-150 ℃; the flue gas outlet is connected with a flue gas purifying treatment system; the water content of the dried magnesium hydroxide is less than or equal to 5 percent.
The suspension roasting device 6 carries out roasting by utilizing the waste heat of the flue gas of the high-temperature shaft kiln 10, the inlet temperature of the hot flue gas is 500-650 ℃, and the exhaust temperature of the flue gas is 300-450 ℃; the suspension roasting device 6 is provided with 2 to 5 cyclones.
The high-temperature high-pressure ball pressing system 7 comprises a pre-pressing device and a high-pressure device, and is used for circularly hot-pressing the light burned magnesium oxide, wherein the hot-pressing temperature is 400-600 ℃; the line pressure of the ball press is 80-110 kN/cm; the ball groove is almond-shaped or peach-shaped, and the capacity is 10 cm to 20cm 3 。
The high-temperature shaft kiln 10 takes heavy oil or natural gas as fuel, and is controlled by a PLC control system to carry out continuous production, and the calcination temperature is 1800-2000 ℃.
The MgO content of the produced sintered magnesia is more than or equal to 98 percent, and the volume density is more than or equal to 3.45g/cm 3 。
The invention relates to a system for producing sintered magnesia by taking magnesium hydroxide as a raw material, which comprises a filter cake storage bin 1, a variable combination feeder unit 2, a quick drying device 3, a shaftless screw conveyor 4, a first bucket elevator 5, a suspension roasting device 6, a high-temperature high-pressure ball system 7, a second bucket elevator 8, a shaft kiln feed bin 9 and a high-temperature shaft kiln 10; the discharge port of the filter cake storage bin 1 is connected with the feed port of the variable combination feeder unit 2; the discharge port of the variable combination feeder unit 2 is connected with the feed port of the quick drying device 3, the discharge port of the quick drying device 3 is connected with the feed port of the shaftless screw conveyor 4, the discharge port of the shaftless screw conveyor 4 is connected with the feed end of the bucket elevator I5, and the discharge end of the bucket elevator I5 is connected with the feed port of the suspension roasting device 6; the discharge port of the suspension roasting device 6 is connected with the feed port of the high-temperature high-pressure ball system 7, the discharge port of the high-temperature high-pressure ball system 7 is connected with the feed end of the bucket elevator II 8, the discharge end of the bucket elevator II 8 is connected with the feed port of the shaft kiln feed bin 9, and the discharge port of the shaft kiln feed bin 9 is connected with the feed port of the high-temperature shaft kiln 10.
The flue gas outlet of the high-temperature shaft kiln 10 is connected with the roasting heat source inlet of the suspension roasting device 6 through a first flue gas pipeline, and the flue gas outlet of the suspension roasting device 6 is connected with the drying heat source inlet of the quick drying device 3 through a second flue gas pipeline; the flue gas outlet of the quick drying device 3 is connected with the flue gas inlet of the flue gas purifying treatment system 11 through a third flue gas pipeline, and the clean flue gas outlet of the flue gas purifying treatment system 11 is connected with the chimney 12.
The variable combined feeder unit 2, the quick drying device 3, the shaftless screw conveyor 4, the suspension roasting device 6, the high-temperature high-pressure ball pressing system 7 and the high-temperature shaft kiln 10 are all of a full-closed structure.
The invention relates to a process for producing sintered magnesia by taking magnesium hydroxide as a raw material, which comprises the following steps:
1) The magnesium hydroxide filter cake prepared from seawater or brine stored in the filter cake storage bin 1 is firstly scattered and conveyed by a variable combined feeding unit 2 (commercial fixed-set equipment), and the feeding rate is determined according to the magnesia yield;
2) The scattered magnesium hydroxide is sent into a quick drying device 3 for drying, the drying temperature is 300-450 ℃, and the magnesium hydroxide with the water content less than or equal to 5% is obtained;
3) The dried magnesium hydroxide is conveyed into a suspension roasting device 6 by a shaftless screw conveyor 4 and a bucket elevator I5, and the conveying speed of the shaftless screw conveyor 4 is determined according to the magnesia yield;
4) The magnesium hydroxide powder is preheated in a preheating section in a suspension roasting device 6, and then enters a roasting section for roasting, wherein the suspension roasting device is provided with 2-5 cyclones (the number of the cyclones is determined according to the magnesia yield and the cyclone specification), and the roasting temperature is 500-650 ℃;
5) The roasted active magnesium oxide is directly sent into a closed high-temperature high-pressure ball pressing system 7 for circulating hot pressing, after prepressing and high-pressure pressing, ball materials are sent into a vertical kiln feed bin 9 through a bucket elevator II 8, crushed materials return to circulating ball pressing in the high-temperature high-pressure ball pressing system 7 (the circulating ball pressing mode is shown in fig. 1, but the invention is not limited to the circulating ball pressing mode), and the hot pressing temperature is 400-600 ℃.
6) The green pellets in the shaft kiln feed bin 9 are sent into a high-temperature shaft kiln 10 for calcination, and the calcination temperature is 1800-2000 ℃ to obtain a sintered magnesia product;
7) The high-temperature shaft kiln 10 is provided with a combustion system 13, hot flue gas generated by the combustion system is sent into the suspension roasting device 6 to roast magnesium hydroxide, and the temperature of the hot flue gas is 500-650 ℃; the hot flue gas generated by the suspension roasting device 6 is sent into the quick drying device 3 to dry magnesium hydroxide, and the flue gas temperature is 300-450 ℃; the temperature of the flue gas discharged by the quick drying device 3 is 50-150 ℃;
8) And the flue gas discharged by the quick drying device 3 is discharged through a chimney 12 after reaching the standard through the flue gas purification treatment system 11.
In the process, the steps 1), 2) and 3) mainly carry out pretreatment of raw materials, including dispersion and drying of a magnesium hydroxide filter cake, so as to obtain magnesium hydroxide powder, wherein the purpose of the magnesium hydroxide powder is to prepare for roasting of magnesium hydroxide in a suspension roasting device; step 4) roasting the dried magnesium hydroxide in a suspension roasting device to obtain high-activity magnesium oxide, wherein the purpose is to prepare high-quality magnesia for high-temperature shaft kiln calcination; step 5) carrying out circulating hot-pressing on the calcined active magnesia powder, so as to improve the volume density of the magnesia balls and facilitate the calcination of high-density magnesia in a high-temperature shaft kiln; step 6) calcining the magnesia balls in a high-temperature shaft kiln to obtain high-density and high-quality magnesia; the steps 7) and 8) are reasonable utilization of the waste heat of the flue gas of the high-temperature shaft kiln and the suspension roasting device and the purification treatment process of the flue gas, and the process furthest reduces the pollution to the environment and the waste of resources and realizes energy conservation and environmental protection.
In summary, the process and the system for producing the sintered magnesia by taking the magnesium hydroxide as the raw material finally realize the purposes of full-automatic control, energy conservation and environmental protection of the sintered magnesia production by simplifying and automatically controlling the process flow, adopting low-temperature roasting and circulating hot pressing, reducing fuel combustion and reasonably utilizing smoke.
The foregoing is only a preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art, who is within the scope of the present invention, should make equivalent substitutions or modifications according to the technical scheme of the present invention and the inventive concept thereof, and should be covered by the scope of the present invention.
Claims (6)
1. A process for producing sintered magnesia by taking magnesium hydroxide as a raw material is characterized in that a magnesium hydroxide filter cake prepared from seawater or brine is taken as a raw material, fed by a variable combination feeder unit, sent into a rapid drying device for drying, and the dried magnesium hydroxide powder is conveyed into a suspension roasting device by a shaftless screw conveyor for roasting, so as to obtain high-activity magnesia powder; circularly hot-pressing the high-activity magnesia powder by a high-temperature high-pressure ball pressing system, and then sending the magnesia powder into a high-temperature shaft kiln for calcination to obtain a sintered magnesia product;
the variable combined feeding unit consists of a manual gate valve, a star-shaped feeding machine, a screw conveyor, a crushing machine and a variable frequency motor, and a feeding end of the variable combined feeding unit is provided with the manual gate valve; the star-shaped feeder and the screw conveyor are driven by a variable frequency motor, and a feeding end of the screw conveyor is provided with a breaking machine; the manual gate valve can directly adjust the feeding amount, the shredder is used for scattering the agglomerated materials, the star-shaped feeder and the screw conveyor are used for forced feeding and conveying, and the shredder has the functions of further scattering and homogenizing the materials; the variable frequency motor is used for adjusting the feeding speed;
the rapid drying device is used for drying by utilizing the waste heat of the flue gas of the suspension roasting device, the inlet temperature of the hot flue gas is 300-450 ℃, and the exhaust temperature of the flue gas is 50-150 ℃; the flue gas outlet is connected with a flue gas purifying treatment system; the water content of the dried magnesium hydroxide is less than or equal to 5 percent;
the suspension roasting device utilizes the waste heat of the flue gas of the high-temperature shaft kiln to roast, the inlet temperature of the hot flue gas is 500-650 ℃, and the exhaust temperature of the flue gas is 300-450 ℃; the suspension roasting device is provided with 2 to 5 cyclones;
the high-temperature high-pressure ball pressing system comprises a pre-pressing device and a high-pressure device and is used for oxidizing after light burningCircularly hot-pressing magnesium at 400-600 deg.c; the line pressure of the ball press is 80-110 kN/cm; the ball groove is almond-shaped or peach-shaped, and the capacity is 10 cm to 20cm 3 。
2. The process for producing sintered magnesia by using magnesium hydroxide as raw material according to claim 1, wherein the high temperature shaft kiln uses heavy oil or natural gas as fuel, and is controlled by a PLC control system to perform continuous production, and the calcination temperature is 1800-2000 ℃.
3. The process for producing sintered magnesia with magnesium hydroxide as material as claimed in claim 1, wherein MgO content of the produced sintered magnesia is not less than 98% and volume density is not less than 3.45g/cm 3 。
4. A system for producing sintered magnesia by taking magnesium hydroxide as a raw material for realizing any one of the processes of claims 1-3, which is characterized by comprising a filter cake storage bin, a variable combination feeder unit, a quick drying device, a shaftless screw conveyor, a bucket elevator I, a suspension roasting device, a high-temperature high-pressure ball pressing system, a bucket elevator II, a shaft kiln feed bin and a high-temperature shaft kiln; the discharge port of the filter cake storage bin is connected with the feed port of the variable combination feeding unit; the discharge port of the variable combined feeding unit is connected with the feed port of the quick drying device, the discharge port of the quick drying device is connected with the feed port of the shaftless screw conveyor, the discharge port of the shaftless screw conveyor is connected with the feed end of the bucket elevator I, and the discharge end of the bucket elevator I is connected with the feed port of the suspension roasting device; the discharge port of the suspension roasting device is connected with the feed port of the high-temperature high-pressure ball system, the discharge port of the high-temperature high-pressure ball system is connected with the feed end of the bucket elevator II, and the discharge end of the bucket elevator II is connected with the feed port of the shaft kiln feed bin, and the feed port of the shaft kiln feed bin is connected with the feed port of the high-temperature shaft kiln.
5. The system for producing sintered magnesia by using magnesium hydroxide as a raw material according to claim 4, wherein the flue gas outlet of the high-temperature shaft kiln is connected with the roasting heat source inlet of the suspension roasting device through a first flue gas pipeline, and the flue gas outlet of the suspension roasting device is connected with the drying heat source inlet of the quick drying device through a second flue gas pipeline; the flue gas outlet of the quick drying device is connected with the flue gas inlet of the flue gas purifying treatment system through a third flue gas pipeline, and the clean flue gas outlet of the flue gas purifying treatment system is connected with a chimney.
6. The system for producing sintered magnesia by using magnesium hydroxide as raw material according to claim 4, wherein the variable combination feeder unit, the quick drying device, the shaftless screw conveyor, the suspension roasting device, the high-temperature high-pressure ball system and the high-temperature shaft kiln are all of a totally-enclosed structure.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201911059054.4A CN110668477B (en) | 2019-11-01 | 2019-11-01 | Process and system for producing sintered magnesia by taking magnesium hydroxide as raw material |
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