CN114100847B - Aluminum ash treatment method - Google Patents
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- CN114100847B CN114100847B CN202111374769.6A CN202111374769A CN114100847B CN 114100847 B CN114100847 B CN 114100847B CN 202111374769 A CN202111374769 A CN 202111374769A CN 114100847 B CN114100847 B CN 114100847B
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Abstract
The invention belongs to the technical field of environment-friendly treatment of nonferrous metallurgy solid waste resources, and relates to an aluminum ash treatment method. Recovering metal aluminum by the primary aluminum ash winnowing roller mill, and denitrifying the aluminum ash milled to a certain size grade by fluidized steam, wherein the steps are as follows: the primary aluminum ash is separated by a gravity air separator, metal aluminum and coarse-particle aluminum ash are discharged through a discharge opening of a gravity powder separator to recover the metal aluminum, and the coarse-particle aluminum ash is subjected to fine-particle aluminum ash after high-pressure roller grinding-gravity air separation closed cycle, then is subjected to separation by a dynamic powder separator and fluidized steam denitrification treatment. The invention is characterized in that: the method has the advantages of wide raw material adaptation, low system power consumption and water consumption, fluidized steam denitrification treatment, energy waste and environmental pollution caused by aluminum ash frying, long flow and environmental problems caused by wet denitrification treatment, realization of the effect of denitrification innocent treatment of the recycled aluminum reground aluminum ash, and achievement of the purpose of high-efficiency, energy-saving and innocent treatment zero emission treatment of the aluminum ash in the aluminum industrial production system.
Description
Technical Field
The invention belongs to the technical field of environment-friendly treatment of nonferrous metallurgy solid waste resources, and particularly relates to an aluminum ash treatment method.
Background
The aluminum ash is a renewable resource and mainly comprises a metallic aluminum simple substance, an oxide, a nitride and a salt solvent. The metallic aluminum is present under the aluminum oxide and aluminum nitride cladding. The aluminum ash comprises primary aluminum ash and secondary aluminum ash, wherein the primary aluminum ash is mainly derived from electrolytic aluminum, the aluminum ash is directly produced in aluminum processing casting and secondary aluminum industry, and the secondary aluminum ash is the aluminum ash obtained after the primary aluminum ash recovers metal aluminum.
At present, with the development of the aluminum industry in China, the amount of aluminum ash in aluminum smelting waste residues is increasing, hazardous waste generated in the aluminum smelting process is re-carded by the Ministry of ecological environment of 11-month and 5-month in 2020 through the national hazardous waste book (2021-year edition), and the aluminum ash is classified into hazardous waste (HW 48), which is implemented from 1-month and 1-month in 2021. The treatment of the aluminum ash is required to be carried out strictly according to the relevant requirements of hazardous wastes, and a great deal of work is carried out on the aluminum ash treatment technology by scholars at home and abroad.
The current processing route for the primary aluminum ash is as follows.
The main treatment of primary aluminum ash mainly aims at recovering the metal aluminum in the primary aluminum ash, and the current main methods comprise: parching aluminum ash, hot pressing, ball milling, dry grinding and sieving. The method is formed by utilizing the principle that aluminum in the aluminum ash is oxidized and released in air, aluminum metal particles are poor in wettability with the aluminum ash, and the contact angle is high. The aluminum ash is directly placed in a rotary pot, and molten aluminum beads are concentrated at the bottom of the pot and returned for casting by stir-frying the aluminum ash. The hot pressing method is to heat the aluminum ash to a hot state and to extrude the liquid aluminum by applying an external force. And (4) putting the hot aluminum ash into a slag tank, and extruding and recovering the aluminum liquid by applying pressure. The ball milling dry milling and screening process includes ball milling to extrude aluminum into sheet and screening to recover aluminum grains. The method has simple equipment and high recovery rate, is widely applied at home, but has higher energy consumption, and the aluminum ash is easy to be polluted by steel balls and carry iron impurities.
The process route for the harmless treatment of the secondary aluminum ash is as follows.
The secondary aluminum ash is treated by harmless treatment of the aluminum ash after the metal aluminum is extracted, and the purpose is to remove nitrogen and salt in the secondary aluminum ash and avoid environmental pollution. The main method comprises the following steps: a fire sintering process and a wet hydrolysis process. The pyrogenic process sintering treatment adopts a roasting consolidation mode, harmful ingredients in the aluminum ash are removed in a high-temperature sintering mode, and then the purpose of harmless utilization of the aluminum ash is achieved. The wet hydrolysis process utilizes hydrolysis reaction of aluminum ash to perform denitrification treatment after pulping the aluminum ash, and the method has good denitrification and desalination effects, but the wet treatment faces the working procedures of concentration, filtration, drying and the like of the aluminum ash slurry. The wet method has good treatment effect, but has long production process and relatively high treatment cost.
The aluminum ash treatment process basically realizes the recovery and harmless treatment of metal aluminum, but has the following defects.
1. The processes of ash frying, extruding and ball milling and screening are mostly original, the automation degree of equipment is low, the working condition of workers is poor, the labor intensity is high, and the environmental problems of unorganized discharge and the like are prominent.
2. The common stir-frying and ball-milling screening has high power consumption, high iron impurity content in the aluminum ash and serious blockage and hardening phenomena of the ball-milling screened aluminum ash.
3. A large amount of byproducts such as dust, inorganic salt, ammonia gas and the like can be generated in the primary aluminum ash frying treatment, and the treatment cost for treating secondary three wastes is high.
4. The traditional aluminum ash harmless treatment wastes a large amount of energy by adopting roasting treatment, and the problems of multiple treatment procedures, high energy consumption and the like exist by adopting a wet treatment process.
Disclosure of Invention
The invention aims to overcome the problems in the prior art and provides an aluminum ash treatment method. The method is an efficient, energy-saving and environment-friendly method integrating metal aluminum separation, aluminum ash dry grinding classification and denitrification harmless treatment.
In order to achieve the purpose, the invention adopts the following technical scheme.
An aluminum ash treatment method comprises the following steps:
step 1, scattering aluminum ash raw materials, and performing gravity winnowing: aluminum ash in electrolytic aluminum, secondary aluminum and aluminum processing production processes is scattered at a feed inlet of a gravity powder concentrator through a metering and belt conveying system, coarse-particle aluminum ash and metal aluminum are sorted through gravity and wind force and discharged from a lower discharge outlet, and fine powder and subdivision are carried out by airflow.
Step 2, fine crushing and regrinding: and (3) sorting the coarse-grained aluminum ash obtained in the step (1) by using metal aluminum, conveying the metal aluminum into a high-pressure roller mill system for roller milling, feeding the material subjected to roller milling into a gravity winnowing system again, and returning the coarse-grained aluminum ash to the high-pressure roller mill to form closed circulation.
Step 3, separating metal aluminum: and (3) sorting the aluminum ash subjected to roller milling by the high-pressure roller milling system in the step (2) by a gravity winnowing machine, recovering a metal aluminum sheet from a grain-level discharge opening in the gravity winnowing machine, feeding the fine-grain-level aluminum ash into a medium-fine powder dynamic powder sorting machine along with air, and rolling the metal aluminum into sheets so as to facilitate sorting and improve the recovery rate of the metal aluminum.
And 5, fine-grained denitrification. And 4, discharging the fine-grained aluminum ash from the upper discharge port of the dynamic powder concentrator into an aluminum ash denitrification reaction tower, discharging the fine-grained aluminum ash into the lower part of the denitrification reaction tower, and discharging the aluminum ash subjected to denitrification treatment from the upper part of the reaction tower.
And 6, recovering fine-grained denitrified aluminum ash, feeding the aluminum ash and steam discharged from the denitrification reaction tower into a cyclone dust removal and settling chamber for dust collection, recovering the fine-grained denitrified aluminum ash from a dust removal feed opening, and feeding dust-containing gas into the next step for treatment.
And 7, finally, the dust-containing gas in the step 6 passes through a dust collector to complete gas-solid separation, the dust collector collects ultrafine grained denitrified aluminum ash, and the gas after dust collection and purification is sent to a desulfurization and denitration system of an aluminum plant or a carbon plant by a fan to be comprehensively treated and then discharged.
Preferably, in the step 1, the aluminum ash fraction entering the high-pressure roller mill system is controlled within the treatment range of 1mm-35mm fraction raw materials through gravity air separation.
Preferably, in step 1, the gravity separator may be a gravity separator, and the gravity separator has functions of material grid scattering, airflow adjustment, gravity classification, air separation, and the like.
In the step 1, an adjusting air adjusting blade is arranged in the gravity powder concentrator, the opening of the blade is adjusted according to the material condition, and an angle adjusting plate is adjusted within the range of 5-45 degrees, so that the internal part of the gravity air classifier, the air flow distribution and the flow velocity are changed, and the middle-fine powder aluminum ash with the size fraction of 1-3 mm can be separated by air.
Preferably, in the step 1, the gravity air separator can adopt a gravity powder separator, air separation can adopt hot air or water vapor according to the requirement of harmless treatment of aluminum ash, and resources of the hot air and the water vapor can be obtained from an electrolytic aluminum or carbon workshop.
Preferably, in the step 1, the gravity separator can be a gravity powder separator, and the rotation speed of the air separation fan can be controlled at 100-.
In the step 2, a constant weight buffer bin is arranged before the high-pressure roller mill, so that the stability of the material column is ensured.
Preferably, in the step 2, the stud of the high-pressure roller mill is made of tungsten carbide hard alloy, the material flow is ensured to be stable by hydraulic control of a moving roller system, and the rotating speed of the high-pressure roller is 10-20 r/min.
Preferably, in the step 2, the high-pressure roller mill system is provided with a closed cycle, and the mechanical activation strength is adjusted and controlled according to the activity requirement of the denitrification reaction of the aluminum ash, so that the qualified particle size is controlled.
In the step 3, the grain-level aluminum ash in the powder concentrator is distributed in a range of 1mm-3mm, the metal aluminum is sorted after the bottom of the powder concentrator is unloaded, and the sorted aluminum ash is lifted by a bucket and returned to the high-pressure roller mill system to form a closed cycle.
Preferably, in the step 3, one of a jigger, a dry high-frequency screening machine and a manual sorting machine is used for sorting the metal aluminum.
Preferably, in the step 4, the fine particles in the aluminum ash are discharged from a discharge outlet of the dynamic powder concentrator, the granularity of the medium and fine particle grades is 2-0.15mm, the rotor speed of the dynamic powder concentrator is 40-400r/min, and the angle of guide vanes of the dynamic powder concentrator is 0-30 degrees.
Preferably, in the step 5, the superfine material is brought into the denitrification reaction tower along with wind, the reaction towers are connected in series in multiple stages, and nozzles are arranged to spray water vapor and a catalyst.
Preferably, in the step 5, the temperature of the water vapor in the denitrification reaction tower is controlled at 120-250 ℃, and the vapor pressure is controlled at 0.1-0.8 MPa.
Preferably, in the step 5, the ratio of the aluminum ash to the steam in the denitrification reactor is controlled to be in the range of 100 to 10.
Preferably, in the step 5, the denitrification reaction time in the denitrification reaction tower is 10-60min, and the control of the reaction time is realized by controlling the gas flow rate according to the exhaust fan and the hot air blower, and can also be realized by designing the length of the reaction tower and connecting a plurality of stages in series.
Preferably, in the step 5, the particle size of the fine aluminum ash particles in the denitrification reactor is controlled to be between 0.15 and 0.01 mm.
As a preferred mode, all steps are connected systematically, and a closed dust collector is adopted to prevent unorganized emission; and pneumatic valves or electric valves are adopted for controlling valves of all systems, so that automatic interlocking control of the whole system can be realized.
Preferably, in the step 6, the denitrified harmless aluminum ash is recovered by the cyclone dust collection and the sedimentation dust collection after the denitrification treatment.
Preferably, in step 7, the dust collector may be a bag dust collector, an electrostatic dust collector or a pre-charged bag dust collector according to the local solid particle emission standard, and the dust collection discharge port collects ultrafine particle-grade harmless aluminum ash.
Preferably, in the step 7, the gas finally subjected to the dust removal contains NH3And the waste aluminum ash is sent to a desulfurizing tower of an electrolytic aluminum plant or a carbon plant for treatment through an exhaust fan, so that the desulfurization efficiency can be improved, and the zero emission trend of the comprehensive treatment of the aluminum ash in the electrolytic aluminum plant is finally realized.
Compared with the prior art, the invention has the beneficial effect that.
1. The invention adds a high-pressure roller grinding process with low energy consumption, adopts a winnowing classification and high-pressure rolling closed cycle treatment method, reduces the power consumption of ore grinding, continuously grinds the aluminum ash and synchronously separates the metal aluminum and regrind the aluminum ash, and has no consumption of steel balls and lining plates.
2. The production of three different grade aluminum ashes can be controlled by adopting winnowing classification, and the grade distribution of the aluminum ashes can be flexibly controlled according to the harmless process and the final aluminum ash recycling requirement.
3. The dry grinding winnowing process method is adopted, so that the consumption of ore grinding water is reduced, and the wastewater treatment generated by the harmless treatment of aluminum ash is avoided.
4. The technological scheme of dry grinding and air separating to extract metal aluminum is provided, and the process requirement that inorganic salt is added into the aluminum ash without harmless treatment is avoided.
5. The method for mechanical activation by using the high-pressure roller mill is provided, the surface activity of denitrification and hydrolysis of the aluminum ash is increased, and the denitrification efficiency and the reaction speed are improved.
6. The method utilizes fluidization of fine-particle aluminum ash and denitrification reaction of water vapor, has high reaction efficiency and high speed, and achieves the aim of denitrification reaction by controlling the granularity of the aluminum ash, the wind flow rate, the proportion of the water vapor, the steam temperature, the steam pressure and the series stages of reaction towers.
7. The high-efficiency short-flow aluminum ash denitrification dry process is provided, the processes of concentration, filtration, water treatment and the like after the harmless wet process treatment of the aluminum ash are avoided, and the method is energy-saving and environment-friendly.
8. The method can combine the existing working conditions of electrolytic aluminum and carbon plants, utilize the existing energy medium resources and process equipment, and embed the aluminum ash harmless comprehensive treatment system into an electrolytic aluminum production system, thereby realizing the comprehensive resource utilization of the aluminum ash in the ecological circle of the electrolytic aluminum industry and improving the enterprise competitiveness.
9. The method and the system are easy to realize the continuous production and treatment of aluminum ash in large batch, the automation degree is high, and the production system can be flexibly adjusted according to the characteristics of the aluminum ash raw material.
Drawings
FIG. 1 is a flow chart of the process of the present invention.
FIG. 2 is a connection diagram of the apparatus of the present invention; labeled as: the device comprises a 1-aluminum ash bin, a 2-gravity winnowing machine, a 3-air blower, a 4-sorting belt, a 5-ingot casting machine, a 6-power winnowing machine, a 7-constant weight material bin, an 8-high pressure roller mill, a 9-denitrification reaction tower, a 10-settling and cyclone dust collection device, a 11-main exhaust fan, a 12-dust remover, a 13-air pressure station and a 14-outer exhaust fan.
Detailed Description
All of the features disclosed in this specification, or all of the steps of any method or process so disclosed, may be combined in any combination, except features and/or steps which are mutually exclusive, unless expressly stated otherwise, or alternatively may be replaced by alternative features which are equivalent or which serve a similar purpose, i.e. a series of equivalents for each feature or step which is individually listed or which is an example of a similar feature, unless expressly stated otherwise.
An aluminum ash treatment method comprises the following steps:
step 1, scattering aluminum ash raw materials, and performing gravity winnowing: aluminum ash in electrolytic aluminum, secondary aluminum and aluminum processing production processes is scattered at a feed inlet of a gravity powder concentrator through a metering and belt conveying system, coarse-particle aluminum ash and metal aluminum are sorted through gravity and wind force and discharged from a lower discharge outlet, and fine powder and subdivision are carried out by airflow.
Step 2, fine crushing and regrinding: and (3) sorting the coarse-grained aluminum ash obtained in the step (1) by using metal aluminum, conveying the metal aluminum into a high-pressure roller mill system for roller milling, feeding the material subjected to roller milling into a gravity winnowing system again, and returning the coarse-grained aluminum ash to the high-pressure roller mill to form closed circulation.
Step 3, separating metal aluminum: and (3) sorting the aluminum ash subjected to roller milling by the high-pressure roller milling system in the step (2) by a gravity winnowing machine, recovering a metal aluminum sheet from a grain-level discharge opening in the gravity winnowing machine, feeding the fine-grain-level aluminum ash into a medium-fine powder dynamic powder sorting machine along with air, and rolling the metal aluminum into sheets so as to facilitate sorting and improve the recovery rate of the metal aluminum.
And 5, fine-grained denitrification. And 4, discharging the fine-grained aluminum ash from the upper discharge port of the dynamic powder concentrator into an aluminum ash denitrification reaction tower, discharging the fine-grained aluminum ash into the lower part of the denitrification reaction tower, and discharging the aluminum ash subjected to denitrification treatment from the upper part of the reaction tower.
And 6, recovering fine-grained denitrified aluminum ash, feeding the aluminum ash and steam discharged from the denitrification reaction tower into a cyclone dust removal and settling chamber for dust collection, recovering the fine-grained denitrified aluminum ash from a dust removal feed opening, and feeding dust-containing gas into the next step for treatment.
And 7, finally, the dust-containing gas in the step 6 passes through a dust collector to complete gas-solid separation, the dust collector collects ultrafine grained denitrified aluminum ash, and the gas after dust collection and purification is sent to a desulfurization and denitration system of an aluminum plant or a carbon plant by a fan to be comprehensively treated and then discharged.
Preferably, in the step 1, the aluminum ash fraction entering the high-pressure roller mill system is controlled within the treatment range of 1mm-35mm fraction raw materials through gravity air separation.
Preferably, in step 1, the gravity separator may be a gravity separator, and the gravity separator has functions of material grid scattering, airflow adjustment, gravity classification, air separation, and the like.
In the step 1, an adjusting air adjusting blade is arranged in the gravity powder concentrator, the opening of the blade is adjusted according to the material condition, and an angle adjusting plate is adjusted within the range of 5-45 degrees, so that the internal part of the gravity air classifier, the air flow distribution and the flow velocity are changed, and the middle-fine powder aluminum ash with the size fraction of 1-3 mm can be separated by air.
Preferably, in the step 1, the gravity air separator can adopt a gravity powder separator, air separation can adopt hot air or water vapor according to the requirement of harmless treatment of aluminum ash, and resources of the hot air and the water vapor can be obtained from an electrolytic aluminum or carbon workshop.
Preferably, in the step 1, the gravity separator can be a gravity powder separator, and the rotation speed of the air separation fan can be controlled at 100-.
In the step 2, a constant weight buffer bin is arranged before the high-pressure roller mill, so that the stability of the material column is ensured.
Preferably, in the step 2, the stud of the high-pressure roller mill is made of tungsten carbide hard alloy, the material flow is ensured to be stable by hydraulic control of a moving roller system, and the rotating speed of the high-pressure roller is 10-20 r/min.
Preferably, in the step 2, the high-pressure roller mill system is provided with a closed cycle, and the mechanical activation strength is adjusted and controlled according to the activity requirement of the denitrification reaction of the aluminum ash, so that the qualified particle size is controlled.
In the step 3, the grain-level aluminum ash in the powder concentrator is distributed in a range of 1mm-3mm, the metal aluminum is sorted after the bottom of the powder concentrator is unloaded, and the sorted aluminum ash is lifted by a bucket and returned to the high-pressure roller mill system to form a closed cycle.
Preferably, in the step 3, one of a jigger, a dry high-frequency screening machine and a manual sorting machine is used for sorting the metal aluminum.
Preferably, in the step 4, the fine particles in the aluminum ash are discharged from a discharge outlet of the dynamic powder concentrator, the granularity of the medium and fine particle grades is 2-0.15mm, the rotor speed of the dynamic powder concentrator is 40-400r/min, and the angle of guide vanes of the dynamic powder concentrator is 0-30 degrees.
Preferably, in the step 5, the superfine material is brought into the denitrification reaction tower along with wind, the reaction towers are connected in series in multiple stages, and nozzles are arranged to spray water vapor and a catalyst.
Preferably, in the step 5, the temperature of the water vapor in the denitrification reaction tower is controlled to be 120-250 ℃, and the vapor pressure is 0.1-0.8 MPa.
Preferably, in the step 5, the ratio of the aluminum ash to the steam in the denitrification reactor is controlled to be in the range of 100 to 10.
Preferably, in the step 5, the denitrification reaction time in the denitrification reaction tower is 10-60min, and the control of the reaction time is realized by controlling the gas flow rate according to the exhaust fan and the hot air blower, and can also be realized by designing the length of the reaction tower and connecting a plurality of stages in series.
Preferably, in the step 5, the particle size of the fine aluminum ash particles in the denitrification reactor is controlled to be between 0.15 and 0.01 mm.
As a preferred mode, all steps are connected systematically, and a closed dust collector is adopted to prevent unorganized emission; and pneumatic valves or electric valves are adopted for controlling valves of all systems, so that automatic interlocking control of the whole system can be realized.
Preferably, in the step 6, the denitrified harmless aluminum ash is recovered by the cyclone dust collection and the sedimentation dust collection after the denitrification treatment.
Preferably, in step 7, the dust collector may select a bag-type dust collector, an electrostatic dust collector or a pre-charged bag-type dust collector according to local solid particle emission standards, and the dust collecting discharge port collects ultrafine particle-level harmless aluminum ash.
Preferably, in step 7, the gas finally subjected to dust removal contains NH3And the waste aluminum ash is sent to a desulfurizing tower of an electrolytic aluminum plant or a carbon plant through the exhaust fan for treatment, so that the desulfurization efficiency can be improved, and the zero emission trend of the comprehensive treatment of the aluminum ash in the electrolytic aluminum plant is finally realized.
Example 1.
The raw material adopts aluminum ash of a certain electrolytic aluminum plant in inner Mongolia region of China, the content of aluminum oxide is 67.4%, the content of metal aluminum is 5.67%, the content of nitrogen is 6%, the water content of the raw material is 1%, and the particle size of the raw material D50=3 mm.
2000kg of raw materials to be processed are selected, feeding is carried out through spiral conveying, the materials are sent into a gravity V-shaped air separator, the angle of a flow deflector is 20 degrees, the rotating speed of a fan is 1400r/min, the materials with the granularity of more than 1mm are recovered from a discharge opening of the gravity V-shaped air separator, metal aluminum and aluminum ash are sorted and selected, 106.3kg of metal aluminum is recovered, the recovery rate of the metal aluminum is 93.7 percent, the materials are sent into a high-pressure roller grinding constant weight bin through a bucket elevator, then the materials enter a high-pressure roller grinding system, the processing capacity of the high-pressure roller grinding machine is 10t/h, the roller distance is 5mm, the materials enter the gravity V-shaped air separator, the particles with the granularity of more than 1mm are sorted and then returned to the high-pressure roller grinding system again to form closed circulation, the material recovery amount of a discharge opening of the gravity V-shaped air separator is 32 percent, medium and fine particles enter a dynamic powder separator along with wind force, the rotating speed of a rotor of the dynamic powder separator is 250r/min, the angle of the flow deflector is 12 degrees, sorting out medium and fine particle-level aluminum ash with the particle size of 1-0.15 mm, wherein the recovery rate of the medium and fine particle-level aluminum ash is 46%, returning the air-sorted aluminum ash to a high-pressure roller mill system for circular roller milling according to the system condition, conveying the fine particle-level aluminum ash of a dynamic powder concentrator into a denitrification reaction tower by wind power, setting a two-level series mode for the denitrification reaction tower, wherein the denitrification reaction time is 40min, the steam temperature (180 ℃) of the first-level reaction tower, spraying 20kg of catalyst sodium hydroxide and 20kg of active agent absolute ethyl alcohol into the first-level reaction tower, and the ratio of the aluminum ash to the steam is 10: 1, the steam temperature of the secondary reaction tower is 250 ℃, the steam pressure is 0.8Mpa, the denitrified aluminum ash passes through a settling chamber and a cyclone dust collection system, the fine-grade denitrified aluminum ash is recovered, the nitrogen content in the denitrified aluminum ash is 0.45%, the aluminum ash grade is D80=0.05mm, 2200kg of the final denitrified aluminum ash is recovered, and the water content of the aluminum ash is 11.23%.
Example 2.
The raw material adopts aluminum ash of a regenerated aluminum plant in Guangdong area of China, the content of aluminum oxide is 42.5%, the content of metal aluminum is 30.8%, the content of nitrogen is 4.32%, the water content of the raw material is 0.6%, and the particle size of the raw material D50=10 mm.
2000kg of raw materials to be processed are selected, feeding is carried out through screw conveying, the materials are sent into a gravity V-shaped air separator, the angle of a flow deflector is 25 degrees, the rotating speed of a fan is 1200r/min, the materials with the granularity of more than 2mm are recovered from a discharge opening of the gravity V-shaped air separator, metal aluminum and aluminum ash are sorted and selected, 552.03kg of metal aluminum is recovered, the recovery rate of the metal aluminum is 89.61 percent, the materials are sent into a high-pressure roller grinding constant weight material bin through a bucket elevator, then the materials enter a high-pressure roller grinding system, the processing capacity of the high-pressure roller grinding machine is 10t/h, the roller distance is 8mm, the materials enter the gravity V-shaped air separator, the particles with the granularity of more than 2mm are sorted and then returned to the high-pressure roller grinding system again to form closed circulation, the material recovery amount of the discharge opening of the gravity V-shaped air separator is 43.35 percent, the medium and fine particles enter a dynamic powder separator along with the air force, the rotating speed of a rotor of the dynamic powder separator and the rotating speed of the rotor of the dynamic powder separator is 300r/min, the angle of a rotor flow deflector is 12 degrees, medium and fine particle aluminum ash with the particle size of 2mm-0.15mm is sorted, the recovery rate of the medium and fine particle is 28.89%, the air-sorted aluminum ash is returned to a high-pressure roller grinding system for circular roller grinding according to the system condition, the fine particle aluminum ash is conveyed into a denitrification reaction tower through a dynamic powder concentrator by wind power, the denitrification reaction tower is provided with a three-stage series mode, the denitrification reaction time is 60min, the steam temperature of the first-stage reaction tower is 120 ℃, and the ratio of the aluminum ash to the steam is 30: 1, the steam temperature of the secondary reaction tower is 200 ℃, the steam pressure is 0.1MPa, the denitrified aluminum ash passes through a settling chamber and a cyclone dust collection system, the fine-grade denitrified aluminum ash is recovered, the nitrogen content in the aluminum ash is 1.2%, the aluminum ash grade is D80=0.07mm, 1628.76kg of final denitrified aluminum ash is recovered, and the water content of the aluminum ash is 6.5%.
Example 3.
The raw material adopts aluminum ash of an aluminum processing factory in inner Mongolia areas of China, the content of aluminum oxide is 78%, the content of metal aluminum is 8.2%, the content of nitrogen is 6.5%, the water content of the raw material is 2%, and the particle size of the raw material D50=1 mm.
2000kg of raw materials to be processed are selected, feeding is carried out through spiral conveying, the materials are sent into a gravity V-shaped air separator, the angle of a flow deflector is 20 degrees, the rotating speed of a fan is 1200r/min, the materials with the granularity of more than 2mm are recovered from a discharge opening of the gravity V-shaped air separator, metal aluminum and aluminum ash are sorted and selected, 149.6kg of metal aluminum is recovered, the recovery rate of the metal aluminum is 91.22 percent, the materials are sent into a high-pressure roller grinding constant weight bin through a bucket elevator, then the materials enter a high-pressure roller grinding system, the processing capacity of the high-pressure roller grinding machine is 10t/h, the roller distance is 8mm, the materials enter the gravity V-shaped air separator, the particles with the granularity of more than 2mm are sorted and then returned to the high-pressure roller grinding system again to form closed circulation, the material recovery amount of the discharge opening of the gravity V-shaped air separator is 18.46 percent, the medium and fine particles enter a dynamic powder separator along with the wind force, the rotating speed of a rotor of the dynamic powder separator is 350r/min, the angle of the flow deflector is 12 degrees, separating medium and fine fraction aluminum ash with the particle size of 2-0.15mm, wherein the recovery rate of the medium and fine fraction is 12.24%, returning the air-separated aluminum ash to a high-pressure roller mill system for circular roller milling according to the system condition, conveying the fine fraction aluminum ash of a dynamic powder concentrator into a denitrification reaction tower by wind power, arranging a first-stage reaction tower in the denitrification reaction tower, wherein the denitrification reaction time is 20min, the steam temperature of the first-stage reaction tower is 200 ℃, and the ratio of the aluminum ash to the steam is 100: 1, the steam temperature of the secondary reaction tower is 250 ℃, the steam pressure is 0.5MPa, the denitrified aluminum ash passes through a settling chamber and a cyclone dust collection system, the fine-grade denitrified aluminum ash is recovered, the nitrogen content in the aluminum ash is 0.8%, the grade of the aluminum ash is D80=0.02mm, 2300.46kg of finally recovered denitrified aluminum ash is obtained, and the water content of the aluminum ash is 4.5%.
Comparative example 1. Patent CN111994928A discloses a method for treating aluminum ash.
Placing the collected aluminum ash into a ball mill for ball milling, placing the ball-milled materials into a drum screen for screening, placing the screened upper-layer substances (the upper-layer substances mainly comprise aluminum particles containing iron and aluminum ash, and the content of the aluminum simple substance is more than 60%) into a magnetic separator for magnetic separation, and placing the residual aluminum particles after magnetic separation into an aluminum particle storage tank for recovery; the middle layer material obtained by screening is particles with the particle size within the range of 60-80 meshes, and the particles with the particle size of 60-80 meshes are conveyed into a ball mill for ball milling again so as to more fully recover the resources in the particles; conveying the particles with the particle size of less than 80 meshes obtained by screening to an aluminum ash reaction system through a material pipeline for reaction; conveying aluminum ash particles with the particle size of less than 80 meshes into a stirring tank to be mixed with a sodium hydroxide solution in the stirring tank (the mass ratio of the particles to the sodium hydroxide solution is 100: 5, and the mass fraction of the sodium hydroxide solution is 32%), uniformly mixing, conveying the mixture into a reaction tank to react, and reacting at the temperature of 80-120 ℃ until the aluminum ash in the mixture is completely reacted (the content of aluminum nitride in the material after the reaction is finished is below 0.5%); when the aluminum ash particles smaller than 80 meshes are conveyed into the stirring tank and the reaction tank, firstly introducing nitrogen into the stirring tank and the reaction tank to discharge air in the stirring tank and the reaction tank, introducing the nitrogen, the air and a small amount of dispersed reaction gas into a washing tower through a water-sealed tank, washing by using dilute sulfuric acid to obtain ammonium sulfate for recycling, wherein the residual nitrogen can be discharged up to the standard and can also be recycled; and conveying the solid-liquid reaction material obtained after the reaction into a five-section vacuum belt conveyor by a material conveying pump for solid-liquid separation (the water content of the solid obtained after the solid-liquid separation is 25-35%), conveying the solid obtained after the separation into an aluminum ash drying machine for drying (the temperature is 300-600 ℃ when the aluminum ash drying machine is used for drying, and the material obtained after the drying is dried until the water content is less than 1%) is recycled.
Comparative example 2.
The raw material adopts the primary aluminum ash of an electrolytic aluminum plant in inner Mongolia areas of China, the content of aluminum oxide is 53.4 percent, the content of metal aluminum is 5.67 percent, the content of nitrogen is 17.6 percent, the water content of the raw material is 1 percent, and the particle size D50=3 mm.
Selecting 2000kg of raw materials to be treated, extracting metal aluminum by an ash frying machine, adding the treated secondary aluminum ash into a slurry mixing tank, adding water with the temperature of 25 ℃ and the temperature of 4000kg, starting a stirrer to uniformly stir for 30min, conveying the slurry into a wet overflow type ball mill by a screw feeder, adding zirconia ceramic balls with the diameter of 30mm into the ball mill, adding 20kg of sodium hydroxide catalyst solution with the weight =20%, adding 15kg of absolute ethyl alcohol accelerant solution with the weight =15%, grinding ores in the ball mill and the slurry mixing tank in a closed loop circulation manner for 2h, discharging the reacted gas from an exhaust port, absorbing the reacted gas by dilute sulfuric acid, introducing the slurry and grinding balls into a screening machine, selecting 100-mesh screening, wherein the screen material amount accounts for 21 percent of the treated raw materials, wherein the metal aluminum is 101.64kg, the recovery rate of the metal aluminum is 89.64 percent, precipitating the recovered slurry by a flocculating agent, conveying the slurry to a vacuum disc type filter by a slurry pump, and obtaining a denitrified aluminum ash filter cake with the water content of 19.31%, wherein the nitrogen content in the aluminum ash is 1.5%, the particle size fraction of the aluminum ash is D80=0.05mm, 3696.92kg of denitrified aluminum ash is finally recovered, and the filtrate is discharged after being crystallized and recovered.
Compared with the aluminum ash treatment method provided by the comparative example 1, the treatment method provided by the invention has the following advantages: according to the invention, the high-pressure roller mill and the air separation are combined, so that the metal aluminum and the aluminum ash of the aluminum ash are separated once, the recovery rate of the metal aluminum is higher, and three aluminum ash products with different particle sizes can be obtained; according to the invention, a high-pressure roller grinding crushing grinding mode is adopted to replace a traditional ball grinding mode, the energy consumption of the whole system is low, the useful ore grinding power of the ball grinder is 10-30%, and the useful ore grinding power of the high-pressure roller grinding is 50-60%, so that in the aluminum ash fine grinding process, the efficiency is high, the energy consumption is low, and the energy consumption of ball grinding and the energy consumption of high-pressure roller grinding aluminum ash grinding are compared in the table 1; the method adopts dynamic powder selection to control the particle size of the fine aluminum ash powder, utilizes wind power to control the fluidization of the aluminum ash, and carries out rapid reaction with water vapor; the aluminum ash ore grinding classification and the denitrification reaction are processed by a dry method, so that the water consumption of the traditional processing method is saved, the product does not need to be dehydrated and dried, the process flow is short, the energy consumption is low, and the treatment of filtrate water is reduced; the medium energy and the discharged waste gas used by the process design can be obtained and consumed in the existing aluminum industry ecosphere, and zero emission of aluminum ash treatment in the aluminum industry is realized.
Table 1 comparative table of energy consumption of milling of aluminum ash and high pressure roller mill (0.074 mm).
Claims (10)
1. The aluminum ash treatment method is characterized by comprising the following steps:
step 1, scattering aluminum ash raw materials, and performing gravity winnowing: aluminum ash in the production process of electrolytic aluminum and secondary aluminum is scattered at a feed inlet of a gravity air separator through a metering and belt conveying system, coarse-grained aluminum ash and metal aluminum are separated and discharged from a lower discharge port through gravity and wind separation, and medium and fine grain grades are carried out by airflow;
step 2, fine crushing and regrinding: sorting the coarse-grained aluminum ash and the metal aluminum in the step 1 through the metal aluminum, conveying the sorted metal aluminum into a high-pressure roller mill system for roller milling, feeding the material subjected to roller milling into a gravity winnowing machine again, and returning the coarse-grained aluminum ash to the high-pressure roller mill to form closed cycle;
step 3, separating metal aluminum: separating the aluminum ash subjected to the roller grinding by the high-pressure roller grinding system in the step 2 by using a gravity air separator, recovering coarse-particle aluminum ash and metal aluminum from a lower discharge port of the gravity air separator, and feeding the middle-fine particle-level and fine-particle-level aluminum ash into a middle-fine powder dynamic powder separator along with air;
step 4, recovering medium and fine fractions: discharging the medium and fine particle size particles in the step 3 from the upper part of the gravity winnowing machine, conveying the particles to a dynamic powder concentrator by wind power, collecting and recycling the aluminum ash of the medium and fine particle size at a discharge outlet of the dynamic powder concentrator, and recycling and storing the aluminum ash or returning the aluminum ash to a roller grinding system according to application;
step 5, fine-grained denitrification: discharging the fine-grained aluminum ash in the step 4 from the upper discharge port of the dynamic powder concentrator, feeding the fine-grained aluminum ash into an aluminum ash denitrification reaction tower, feeding the fine-grained aluminum ash into the lower part of the denitrification reaction tower, and discharging the aluminum ash subjected to denitrification treatment from the upper part of the reaction tower;
step 6, recovering fine-fraction denitrified aluminum ash: aluminum ash and steam discharged from the denitrification reaction tower enter a cyclone dust removal and settling chamber for dust collection, a dust removal feed opening recovers fine-grade denitrification aluminum ash, and dust-containing gas enters the next step for treatment;
and 7, the dust-containing gas in the step 6 passes through a dust collector to complete gas-solid separation, the dust collector collects ultrafine grained denitrified aluminum ash, and the gas after dust collection and purification is sent to a desulfurization and denitrification system of an aluminum plant or a carbon plant by a fan to be comprehensively treated and then discharged.
2. The aluminum ash treatment method of claim 1, wherein: in the step 1, the aluminum ash entering the high-pressure roller grinding system is controlled within the range of 1mm-35mm through gravity air separation; the gravity winnowing machine can winnow out aluminum ash with the grain size of 1mm-3 mm; the gravity air separator is matched with a blower with the rotating speed controlled at 100-.
3. The aluminum ash treatment method as claimed in claim 1, wherein: in the step 2, a constant weight buffer bin is arranged before the high-pressure roller mill; the stud of the high-pressure roller milling equipment is made of tungsten carbide hard alloy, the rotating speed of a high-pressure roller is 10-20r/min, and the roller distance of the high-pressure roller is 5-15 mm; the high-pressure roller milling system is provided with closed circulation, an edge material circulating system is arranged according to the activity requirement of the denitrification reaction of the aluminum ash, the roller milling circulation frequency is adjusted and controlled, and the qualified particle size is controlled.
4. The aluminum ash treatment method of claim 1, wherein: in the step 3, discharging aluminum ash at the bottom of the gravity air separator to a size fraction of more than 1mm-3mm, sorting metal aluminum after discharging at the bottom, and returning the sorted aluminum ash to the high-pressure roller grinding system by bucket lifting to form closed cycle; the sorting of the metal aluminum adopts one of a jigger, a dry high-frequency screening machine or manual sorting.
5. The aluminum ash treatment method of claim 1, wherein: in the step 4, fine particles in the aluminum ash are discharged from a discharge outlet of the dynamic powder concentrator, the granularity of the fine and medium particles is 2-0.15mm, the rotor speed of the dynamic powder concentrator is 40-400r/min, and the angle of a guide vane of the dynamic powder concentrator is 0-30 degrees.
6. The aluminum ash treatment method of claim 1, wherein: in the step 5, the fine-grade materials are brought into a denitrification reaction tower along with wind, the granularity of fine-grade aluminum ash particles is controlled to be 0.15-0.01mm, the denitrification reaction tower is connected in series in multiple stages, and a nozzle is arranged to spray water vapor and a catalyst; in the denitrification reaction tower, the temperature of the water vapor is controlled to be 120-250 ℃, and the vapor pressure is 0.1-0.8 MPa; the ratio of the aluminum ash to the steam is controlled to be 100-10; the denitrification reaction time is 10-60 min.
7. The method for treating aluminum ash as recited in claim 1, wherein in the step 6, the denitrified aluminum ash is recovered by cyclone dust collection and settling chamber dust collection.
8. The aluminum ash treatment method of claim 1, wherein in the step 7, the dust collector selects one of a bag dust collector, an electrostatic dust collector or a pre-charged bag dust collector according to local solid particle emission standards, and the dust collection discharge port collects the ultrafine particle level harmless aluminum ash.
9. The method of claim 1, wherein in the step 7, the gas finally removed by dust contains NH3And the waste gas is sent to a desulfurizing tower of an electrolytic aluminum or carbon plant for treatment through an exhaust fan.
10. The aluminum ash treatment method according to any one of claims 1 to 9, wherein each step is systematically connected and adopts a closed dust collection method to control the inorganized emission; and the valves of all systems are controlled by pneumatic valves or electric valves.
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