CN111471866A - Method for recycling and harmlessly treating waste aluminum raw material - Google Patents
Method for recycling and harmlessly treating waste aluminum raw material Download PDFInfo
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- CN111471866A CN111471866A CN202010477997.5A CN202010477997A CN111471866A CN 111471866 A CN111471866 A CN 111471866A CN 202010477997 A CN202010477997 A CN 202010477997A CN 111471866 A CN111471866 A CN 111471866A
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- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B7/00—Working up raw materials other than ores, e.g. scrap, to produce non-ferrous metals and compounds thereof; Methods of a general interest or applied to the winning of more than two metals
- C22B7/001—Dry processes
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B1/00—Preliminary treatment of ores or scrap
- C22B1/005—Preliminary treatment of scrap
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B21/00—Obtaining aluminium
- C22B21/0007—Preliminary treatment of ores or scrap or any other metal source
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
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- C22B21/00—Obtaining aluminium
- C22B21/0084—Obtaining aluminium melting and handling molten aluminium
- C22B21/0092—Remelting scrap, skimmings or any secondary source aluminium
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- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B21/00—Obtaining aluminium
- C22B21/06—Obtaining aluminium refining
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Abstract
The invention discloses a method for recycling and harmlessly treating a waste aluminum raw material, which is characterized by comprising the following steps of: the method mainly comprises the following steps: (1) the raw material of the aluminum scrap is put into a factory for inspection; (2) pretreating a waste aluminum raw material; (3) preheating and depainting; (4) smelting; (5) refining by quenching and tempering; (6) the invention can effectively recycle the waste aluminum raw material, reduces the waste of waste aluminum resources, reduces environmental pollution in the treatment process, improves the purity of molten aluminum, is combined with an aluminum ash harmless treatment method, has large treatment capacity, can treat aluminum ash such as electrolytic aluminum ash, regenerated aluminum ash, dust collection ash and the like, has high fluorine removal efficiency (generally more than 99 percent), does not discharge fluorine-containing waste water, does not have the problems of secondary pollution, equipment corrosion and the like, and has lower capital construction cost and operating cost.
Description
Technical Field
The invention relates to the field of waste aluminum recycling, in particular to a method for recycling and harmlessly treating a waste aluminum raw material.
Background
In order to improve the recovery utilization rate, the residual aluminum scraps produced in the processing of aluminum profile manufacturers are recovered and uniformly sent to a manufacturer for processing aluminum bars by the aluminum scraps to be smelted and recast. In the process of smelting the aluminum scrap, if impurities in the aluminum scrap are not removed in advance, the smelting quality in the aluminum scrap is seriously influenced, so the impurities are removed when the aluminum scrap is smelted, and the smelting quality of the aluminum scrap is improved.
In addition, various byproducts are generated in the aluminum smelting and forming processes. As a main byproduct in the aluminum industry, aluminum ash is generated in all aluminum melting processes, wherein the aluminum content accounts for about 1-12% of the total loss amount in the aluminum production and use process. In the past, people regarded aluminum ash as waste slag to be dumped, which not only causes aluminum resource waste, but also brings environmental problems.
Therefore, an economic and effective method is found for utilizing and treating the aluminum ash, so that the economic benefit of the aluminum industry is improved, the effective cyclic utilization of resources is realized, and meanwhile, the important influence on the sustainable development of economy and society is generated.
Disclosure of Invention
The invention aims to solve the problems in the prior art and provides a method for harmlessly treating hazardous waste electrolytic aluminum ash.
The technical scheme of the invention is as follows: a method for recycling and harmlessly treating a waste aluminum raw material is characterized by comprising the following steps: the method mainly comprises the following steps:
(1) factory inspection of aluminum scrap raw material
Carrying out analysis and detection on the waste aluminum materials when the waste aluminum materials are transported into a factory area, wherein the analysis and detection comprise the monitoring of containers entering the factory and the monitoring of the waste aluminum materials before the waste aluminum materials are fed into a furnace, and the waste aluminum materials are directly returned to suppliers after the detection is unqualified; the heavy metal content in the waste aluminum materials before entering the furnace is strictly controlled, the raw materials meeting the requirements are sent into a closed material grid of a material processing workshop for stacking, and the goods not meeting the requirements are returned to a supplier;
(2) pretreatment of aluminum scrap raw material
The raw material pretreatment process is arranged in a closed material processing workshop, 3 sets of full-automatic aluminum scrap raw material shredding, screening, winnowing, magnetic separation and eddy current separation equipment are arranged in the step, each set of pretreatment equipment comprises 2 pretreatment production lines and is used for respectively treating the aluminum scrap raw material packed into blocks and scattered aluminum scrap raw material;
(3) preheating paint removal
In the preheating stage, a paint removing roller is adopted, and the preheating process realizes the preheating of the waste aluminum raw material and the paint removing of the waste aluminum raw material at the same time; in the preheating and paint removing process, only when the temperature of the furnace is raised in the driving stage and the material is not fed yet, the preheating waste gas of the roller directly enters a waste gas treatment system of a production line without secondary treatment of a combustion chamber. In the step, a central heat accumulating type heat exchange system is adopted, so that the temperature of the flue gas is quickly reduced from more than 900 ℃ to less than 230 ℃ within 1s after heat exchange is carried out by a heat accumulator when the flue gas is led out of a hearth, and the flue gas after being rapidly cooled avoids the re-synthesis of dioxin substances;
(4) melting
The method adopts a double-chamber reflection smelting furnace, divides a partition wall for the traditional reflection furnace into a heating chamber and a feeding chamber, and mainly comprises the heating chamber, the feeding (slagging) chamber, an aluminum liquid circulating system, a regenerative combustion system, a control system, a feeding system and the like;
the heating chamber is mainly used for providing main energy for smelting, and discharging the aluminum liquid after the temperature and chemical components are adjusted to be proper; the feeding (slagging-off) chamber is mainly used for feeding and melting the waste aluminum materials, is separated from the heating chamber by a partition wall with channels at the upper part and the lower part, and the two channels are respectively used for the passing of smoke and aluminum liquid;
(5) refining by tempering
After the smelting is finished, entering a quality-adjusting refining process, wherein the quality-adjusting refining process can be carried out in a smelting furnace and a heat-preserving furnace; the aluminum liquid needs to stay for about 2 hours in the quenching and tempering refining process, the temperature of a molten pool is kept at 680-750 ℃, and the temperature of a hearth is kept at 800-1000 ℃; the furnace liquid is subjected to the working procedures of stirring, tempering, degassing, standing, slagging-off and heat preservation in sequence, and the additive is introduced into the aluminum liquid by taking nitrogen as carrier gas;
(6) rotary furnace and aluminum ash harmless treatment
Each production line in the step is provided with 23 t rotary furnaces, 1 cold ash cylinder, 1 set of aluminum ash crushing/screening system and 1 set of aluminum ash innocent treatment system in a matching way, and the systems are used for the innocent treatment of metal aluminum and aluminum ash, collected dust, electrolytic aluminum ash and regenerated aluminum ash in the recovered slag;
in the smelting furnace and the refining heat preservation furnace, furnace slag is generated besides the aluminum liquid; slagging-off generated by the smelting and refining furnace contains about 30-50% of metal aluminum, and the hot aluminum slag after mechanical slagging-off is sent into a matched aluminum slag rotary furnace; further recovering the metallic aluminum therein. 23 t rotary furnaces are arranged on each production line of the project; is used for treating the aluminum slag and recovering the metal aluminum.
Preferably, the step (2) includes the following steps:
firstly, feeding a waste aluminum raw material into pretreatment equipment for shredding, wherein the size of the shredded waste aluminum raw material is 2-10 cm;
then, sorting the aluminum materials after shredding by the particle size of the waste aluminum materials through a screening roller, and returning the aluminum materials with large particle size to the shredder for reprocessing;
then, separating ferromagnetic impurities and impurities with a large amount of iron inserts from the waste aluminum materials by the magnetic separator under the action of magnetic force;
and finally, separating other metal impurities from the material by eddy current, pretreating the waste aluminum material, manually separating, classifying and stacking the waste aluminum material in a material grid.
Preferably, the step (4) includes the following steps:
the method comprises the following steps:
① feeding, namely, the preheated and depainted fine aluminum scrap is sent to a vortex feeding well through a closed pipeline by a vibrating feeder and a belt conveyor, and the scattered aluminum scrap is quickly involved in the high-temperature aluminum liquid vortex to be quickly melted;
② melting, namely injecting natural gas into 2 burners on the side wall of a melting furnace (100T) and burning in a hearth, keeping the temperature of a molten pool at 720-810 ℃, keeping the temperature of the hearth at 900-1050 ℃, after feeding, closing a charging chamber furnace door, and melting the waste aluminum material by the molten pool, wherein the melting furnace takes the natural gas as fuel, the melting time of one production period is about 6 hours, the double-chamber furnace takes the aluminum liquid as the molten pool, and the preheated furnace burden directly enters the molten pool to be melted;
preferably, the step (6) of performing dry defluorination denitrification aluminum ash harmless treatment on the collected aluminum ash comprises the following processes:
① heating the slag in a rotary furnace to be used as an initial heat source, and performing heat treatment in a direct heating mode, wherein the temperature is controlled at 900-1200 ℃;
② starting the rotary furnace to rotate at a certain speed, gradually adding the collected fine aluminum ash, and introducing compressed air at 3-5 m/hr to assist the complete combustion in the furnace.
③ when the rotary furnace continuously rotates and burns for 3 hours until the metal aluminum burns completely, the rotation is stopped;
④ sending the completely combusted aluminum ash to a cold ash system for cooling;
⑤ when the aluminum ash is cooled to normal temperature, the aluminum ash is harmless, and the aluminum ash is directly packed by ton bags and can be used as raw materials of concrete pavement bricks and refractory materials.
The invention can effectively recycle the waste aluminum raw material, reduces the waste of waste aluminum resources, reduces environmental pollution in the treatment process, improves the purity of the molten aluminum, is combined with an aluminum ash harmless treatment method, has large treatment capacity, can treat aluminum ash such as electrolytic aluminum ash, regenerated aluminum ash, dust collection ash and the like, has high fluorine removal efficiency (generally more than 99 percent), does not discharge fluorine-containing waste water, has no problems of secondary pollution, equipment corrosion and the like, and has lower capital construction cost and operating cost.
When the electrolytic aluminum ash is treated, a calcium series compound is most suitable as a purifying agent, wherein the calcium series compound has large surface area, more micropores and strong adsorption force, fluorine in fluorine-containing flue gas passes through the purifying agent, the fluorine is adsorbed on the surface of the purifying agent, the formed fluoride can be recovered, the purified gas is separated by a dust removal filter to reach the standard and is discharged, and harmless fine powder after fluorine fixation is packaged to be used as a raw material of a concrete pavement brick and a refractory material.
Drawings
FIG. 1 is a flow chart of the present invention.
Detailed Description
In order to make the technical means, technical features, objects and technical effects of the present invention easily understandable, the present invention is further described below with reference to the specific drawings.
Referring to fig. 1, a method for recycling and harmless treatment of a waste aluminum raw material is characterized in that: the method mainly comprises the following steps:
(1) factory inspection of aluminum scrap raw material
The main raw materials are waste aluminum zip-top cans and partial waste aluminum, which are conveyed to a factory after being primarily sorted by a supplier. Carrying out analysis and detection on the waste aluminum materials when the waste aluminum materials are transported into a factory area, wherein the analysis and detection comprise the monitoring of containers entering the factory and the monitoring of the waste aluminum materials before the waste aluminum materials are fed into a furnace, and the waste aluminum materials are directly returned to suppliers after the detection is unqualified; the content of organic matters, lead, chromium and other heavy metals in the waste aluminum materials before furnace entry is strictly controlled (the content of lead in the waste aluminum materials before furnace entry is controlled to be below 0.01 percent, the content of heavy metals in the waste aluminum materials is detected, raw materials meeting requirements are sent into a closed material grid of a material processing workshop to be stacked, and goods not meeting the requirements are returned to a supplier.
(2) Pretreatment of aluminum scrap raw material
The raw material pretreatment process is arranged in a closed material processing workshop, 3 sets of full-automatic aluminum scrap raw material shredding, screening, winnowing, magnetic separation and eddy current separation equipment are arranged in the step, each set of pretreatment equipment comprises 2 pretreatment production lines and is used for respectively treating the aluminum scrap raw materials packed into blocks and scattered aluminum scrap raw materials.
The method mainly comprises the following steps:
firstly, feeding a waste aluminum raw material into pretreatment equipment for shredding, wherein the size of the shredded waste aluminum raw material is 2-10 cm.
And then, sorting the aluminum materials after shredding by the particle size of the waste aluminum materials through a screening roller, and returning the aluminum materials with large particle size to the shredder for reprocessing.
And then, separating ferromagnetic impurities and impurities with a large amount of iron inserts from the waste aluminum materials by using a magnetic separator under the action of magnetic force.
And finally, separating other metal impurities from the material by eddy current, pretreating the waste aluminum material, manually separating, classifying and stacking the waste aluminum material in a material grid.
(3) Preheating paint removal
In the preheating stage, a paint removing roller is adopted, and the preheating process realizes the preheating of the waste aluminum raw material and the paint removing of the waste aluminum raw material at the same time.
The roller paint removing technology in the embodiment is a fire treatment technology, a preheating roller is designed to be a closed negative pressure, waste aluminum fragments automatically fall into a receiving port of a drying roller through a feeding conveyer belt and then enter the roller, high-temperature smoke led out by an auxiliary smoke exhaust channel of a heat accumulating type double-chamber aluminum melting furnace enters the drying roller to heat materials, the temperature is controlled to be 350-400 ℃, an aluminum sheet rapidly rises in the furnace, and the paint removing temperature is reached in a short time, so that a paint layer on the surface of the aluminum material is decomposed and carbonized.
Because the preheating roller rotates at a certain speed, the materials collide and rub with each other, and the coating is gradually carbonized and falls off. And residual moisture in the aluminum scrap is dried in the process, so that the possibility of reaction between water and molten aluminum in the smelting process of the subsequent process is eliminated, and the smelting quality and the production safety are ensured. H generated by decomposition and carbonization of waste aluminum paint layer in preheating roller2CO and organic gas are introduced into a matched combustion chamber, the depainting waste gas reaches a certain concentration and can be combusted automatically, the combusted waste gas enters a heat storage chamber of the double-chamber furnace, the post-combustion and the combustion waste gas of the double-chamber furnace enter a waste gas treatment system together, and the preheating and depainting of aluminum sheets are completed and fall into a smelting furnace feeding system from an outlet of a drying roller.
In the preheating and paint removing process, only when the temperature of the furnace is raised in the driving stage and the material is not fed yet, the preheating waste gas of the roller directly enters a waste gas treatment system of a production line without secondary treatment of a combustion chamber. In the step, a central heat accumulating type heat exchange system is adopted, so that the temperature of the flue gas is quickly reduced from more than 900 ℃ to less than 230 ℃ within 1s after heat exchange through a heat accumulator when the flue gas is led out of a hearth, and the flue gas after being rapidly cooled avoids the re-synthesis of dioxin substances.
The working principle of the double-chamber furnace regenerative chamber is as follows:
① when cold air passes through the regenerator B, the heat absorbed by the heat accumulator is heated to above 900 ℃ (50-100 ℃ lower than the furnace temperature) and enters the furnace to support combustion, the combustion temperature in the furnace is maintained at about 1000 ℃ and below 1050 ℃, and according to the characteristic that dioxin (PCDD/Fs) can be decomposed at 700-800 ℃, the combustion temperature of the smelting furnace in the step is about 1000 ℃, and the PCDD/Fs are almost decomposed;
② introducing hot flue gas in the furnace into the heat storage chamber A, absorbing heat by the heat storage body, rapidly reducing the temperature of the flue gas to below 230 ℃ and discharging, wherein the cooling time of the flue gas in the heat storage body is less than 1 s;
③ when the heat accumulation of the regenerator A is finished, the regenerator B is cooled by the air at room temperature, the reversing valve reverses, and the cold air flows through the regenerator A to be preheated and heated to above 900 ℃ and is blown into the furnace to support combustion;
④ the hot flue gas flows through the regenerator B to release heat, cool and discharge;
⑤ the reversing valve switches cyclically, the two regenerators accumulate heat and release heat alternately, the combustion-supporting air is kept above 900 deg.C all the time, the discharged flue gas is below 230 deg.C all the time, the fuel spray gun sprays fuel into the furnace continuously in the whole process to burn, the burning is continuous and stable, and the heat accumulator transfers the heat accumulated in the cooling process of the flue gas to the combustion-supporting air to return to the furnace in the next operating period.
(4) Melting
The double-chamber reflection smelting furnace is adopted in the step, a partition wall for the traditional reflection furnace is divided into a heating chamber and a feeding chamber, and the double-chamber reflection smelting furnace mainly comprises the heating chamber, the feeding (slagging) chamber, an aluminum liquid circulating system, a heat accumulating type combustion system, a control system, a feeding system and the like.
The heating chamber is mainly used for providing main energy for smelting, and discharging the aluminum liquid after the temperature and chemical components are adjusted to be proper. The feeding (slagging-off) chamber is mainly used for feeding and melting aluminum scrap, is separated from the heating chamber by a partition wall with an upper channel and a lower channel, and the two channels are respectively used for smoke and aluminum liquid to pass through.
The aluminum liquid circulating system mainly comprises a feeding chamber molten pool and a heating chamber molten pool, wherein a mechanical aluminum liquid pump drives aluminum alloy liquid to enter the feeding chamber from the heating chamber molten pool through a pump well, the energy of the heating chamber is transferred to the feeding (slagging) chamber, so that the temperature of the aluminum liquid in the feeding (slagging) chamber is gradually increased, and a main heat source is provided for melting the waste aluminum materials. The aluminum liquid in the feeding (slagging-off) chamber returns to the heating chamber through an aluminum liquid channel on the partition wall of the two chambers, thereby completing an aluminum liquid circulation process, and the forced stirring effect generated by the aluminum liquid circulation ensures that the temperature and chemical components of the molten pool aluminum liquid are more uniform.
The special structure of the mechanical aluminum liquid pump well in the system ensures that aluminum liquid flowing at high speed forms a vortex, namely the vortex well, which can be used for adding scattered materials. The smelting furnace adopts the graphite stirring technology to stir, utilizes the graphite pump to drive the aluminium water and rotates the raw materials in the smelting furnace to the production process burns and decreases greatly, improves the rate of recovery.
The method comprises the following steps:
① feeding, namely, the preheated and depainted fine aluminum scrap is conveyed to a vortex feeding well through a closed pipeline by a vibrating feeder and a belt conveyor, and the scattered aluminum scrap is quickly involved in the high-temperature aluminum liquid vortex to be quickly melted.
② melting, wherein natural gas is injected into 2 nozzles on the side wall of a melting furnace (100T) and is combusted in a hearth, the temperature of a molten pool is kept at 720-810 ℃, the temperature of the hearth is 900-1050 ℃, after feeding, a furnace door of a feeding chamber is closed, and waste aluminum materials are melted by the molten pool.
(5) Refining by tempering
And after the smelting is finished, entering a quality-adjusting refining process, wherein the quality-adjusting refining process can be carried out in a smelting furnace and a heat-preserving furnace. The aluminum liquid needs to stay for about 2 hours in the quenching and tempering refining process, the temperature of a molten pool is kept at 680-750 ℃, and the temperature of a hearth is kept at 800-1000 ℃. The furnace liquid is sequentially subjected to the working procedures of stirring, tempering, degassing, standing, slagging, heat preservation and the like, and additives (a degassing agent and a deslagging agent) are introduced into the aluminum liquid by taking nitrogen as a carrier gas.
The degassing system adopted in the step can realize continuous degassing of the aluminum liquid, has the capability of removing hydrogen, alkaline metal and impurities, and achieves the purpose of purifying the aluminum alloy liquid. The slag removing agent used in the step consists of various chlorides and fluorides, the slag removing agent is decomposed under the action of high temperature after entering the aluminum melt, and reacts with the aluminum melt to generate gas, such as HCl, hydrogen atoms in the melt are diffused into the bubbles and taken away, the bubbles can capture impurities, scum and the like in the floating process to play a purifying role, and the chlorides, the fluorides and the aluminum melt after being added into the slag removing agent generate the following chemical reactions:
nAl＋3MeCln（MeFn）＝ nAlCl3（AlF3）＋3Me
the slag remover has obvious slag removing effect, and also has the functions of degassing and covering, wherein the degassing rate reaches 81.5 percent.
After quenching and tempering and refining, the qualified aluminum liquid further flows into a heat preservation furnace for heat preservation through inspection, and the aluminum liquid in the heat preservation furnace is delivered to customers for use in the form of ladles according to the needs of the customers. In the smelting furnace and the heat preservation furnace, apart from aluminum liquid, partial furnace slag still exists. The scum is removed mechanically (commonly known as "skimming"). The accumulated slag skimming time is about 0.75 h.
The double-chamber furnace and the heat preservation furnace both adopt natural gas as fuel, and combustion flue gas is collected by an exhaust system. High-temperature smelting smoke generated in the smelting and refining processes is provided with a smoke exhaust hood and a mechanical exhaust system above the furnace door, and smelting and refining waste gas and combustion smoke are collected into a waste gas treatment system for treatment.
(6) Rotary furnace and aluminum ash harmless treatment
In the step, each production line is provided with 23 t rotary furnaces (one for one), 1 cold ash cylinder, 1 set of aluminum ash crushing/screening system and 1 set of aluminum ash innocent treatment system in a matching way, and the aluminum ash innocent treatment system is used for the innocent treatment of metal aluminum and aluminum ash in the recovered slag, dust collection ash, electrolytic aluminum ash and regenerated aluminum ash.
Besides aluminum liquid, slag is also generated in the smelting furnace and the refining heat preservation furnace. The slagging-off generated by the smelting and refining furnace contains about 30-50% of metallic aluminum, and the hot aluminum slag after mechanical slagging-off is sent to a matched aluminum slag rotary furnace (3 t) for further recovering the metallic aluminum. 23 t rotary furnaces (one for one and one standby) are arranged on each production line of the project and used for treating aluminum slag and recycling metal aluminum.
The rotary furnace takes heat released by spontaneous combustion of aluminum slag as energy for smelting, the temperature in the rotary furnace is controlled to be 700-850 ℃ in the smelting process of the rotary furnace, the recovered aluminum liquid is returned to the smelting furnace for reuse, and the residual aluminum ash is cooled by aluminum ash cooling equipment (an ash cooling cylinder) and then enters an aluminum ash crushing/screening system for crushing and grading. After the aluminum ash is treated by the crushing/screening system, the granular aluminum with larger grain size returns to the rotary furnace (3 t) to recover the metal aluminum again, and the rest aluminum ash enters the aluminum ash harmless treatment system for treatment.
The collected aluminum ash is subjected to dry defluorination denitrification aluminum ash innocent treatment, and the method comprises the following steps:
① adding calcium series compounds into the rotary furnace and using the hot furnace slag as an initial heat source, and performing heat treatment in a direct heating mode, wherein the temperature is controlled at 900-;
② starting the rotary furnace to rotate at a certain speed, gradually adding the collected fine aluminum ash, and introducing compressed air at 3-5 m/hr to assist the complete combustion in the furnace.
③ when the rotary furnace continuously rotates and burns for 3 hours until the metal aluminum burns completely, the rotation is stopped;
④ sending the completely combusted aluminum ash to a cold ash system for cooling;
⑤ when the aluminum ash is cooled to normal temperature, the aluminum ash is harmless, and the aluminum ash is directly packed by ton bags and can be used as raw materials of concrete pavement bricks and refractory materials.
The calcium series compound in the invention is calcium oxide, calcium hydroxide or calcium carbonate; the dry treatment of fluorine gas as an absorbent can reduce problems of toxicity, corrosive gas leakage, corrosion of pipelines, treatment of acidic wastewater and the like.
The calcium series compound, the fine aluminum ash and the dust collecting ash collected by the dust remover enter a rotary furnace of an aluminum ash harmless system together for high-temperature aluminum removal, denitrification and fluorine fixation. Adding hot slag as an initial heat source into the rotary furnace, and performing heat treatment by adopting a direct heating mode and controlling the temperature at 900-1200 ℃.
The working principle of the aluminum ash harmless treatment in the step is as follows:
hot slag → calcium series compounds (calcium oxide, calcium hydroxide or calcium carbonate), fine aluminum ash, dust collection ash collected by a dust remover (metal aluminum can be combusted by itself to raise the temperature) → oxygen-deficient combustion by introducing air → continuous rotary combustion for 3-6 hours → pouring out the hot aluminum ash into a cold ash system (for cooling).
The working principle of the cold ash system in the step is as follows: feeding → cooling water indirect cooling → cold ash discharging.
The principle of the present invention for detoxification is explained as follows:
① removing aluminum
Under the high-temperature condition of the rotary furnace, the metallic aluminum is self-ignited to generate aluminum oxide.
② denitrification
Controlling the temperature of the rotary furnace (at 1000 ℃) to perform oxygen-deficient combustion, so that aluminum nitride (AlN) in the aluminum ash is subjected to oxidation reaction under the high-temperature condition, and the aluminum oxide with the purity of more than 70% is obtained.
Under the conditions of set process and temperature, more than 90 percent of nitrogen elements in aluminum nitride in aluminum ash are converted into nitrogen gas, and the rest nitrogen elements are converted into NOx. The main chemical reactions involved in the deamination process are:
AlN+O2→Al2O3+N2+NOX
4AlN+3O2→2Al2O3+2N2
③ Dry fluorine fixation
The calcium compound (calcium oxide, calcium hydroxide, or calcium carbonate) charged into the rotary kiln undergoes a fluorine-fixing reaction with fluorine elements that can be precipitated from the fine aluminum ash at a high temperature, and is converted into insoluble calcium fluoride CaF 2.
The main chemical reactions involved in the fluorine fixing procedure are as follows:
CaO + Na2SiF6+ H2O → CaSiF6↓+ 2NaOH
CaO + 2NaF + H2O → CaF2↓+ 2NaOH
the harmless fine powder after fluorine fixation can be used as the raw material of concrete pavement bricks and refractory materials after being packaged.
In this embodiment, the system for harmless treatment of aluminum ash comprises 2 5t rotary furnaces (one for one use and one for standby) and 1 aluminum ash cooling device (cold ash drum).
In this example, each production line is provided with 2 rotary kilns (one for one) and 5t for further harmless treatment of collected dust and crushed/screened aluminum ash in the waste gas treatment system of the production line.
The rotary furnace (5 t) takes the heat released by the spontaneous combustion of the aluminum ash as energy to carry out combustion reaction, the combustion temperature can reach about 1200 ℃, and the collected dust and the metal aluminum in the aluminum ash are converted into Al after combustion2O3Aluminum nitride (AlN) is converted to Al after combustion2O3And nitrogen oxide, wherein the activated carbon in the dust collection ash is converted into carbon-oxygen compounds after being combusted, dioxin sprayed by the activated carbon is decomposed at high temperature and enters waste gas, and part of the fluoride and the chloride enters the waste gas after being combusted.
Therefore, the main component of the waste ash (fine ash) finally remaining after the high-temperature combustion treatment in the rotary kiln (5 t) is Al2O3. The fine ash after the combustion treatment of the rotary kiln (5 t) is sent into a cold ash cylinder for cooling. And directly loading the cooled fine ash into a ton bag, sealing and collecting the fine ash, temporarily storing the fine ash in a factory, identifying the hazardous waste property, and reasonably disposing according to the identification result.
The complete equipment of the rotary furnace, the aluminum ash cooling system, the crushing/screening system and the harmless treatment system in the embodiment is of a closed design, dust unorganized emission can be effectively prevented, the gas collecting hood and the air draft device are arranged at the feeding end and the discharging end, and waste gas is merged into the waste gas treatment system of the smelting production line for treatment.
The invention has the following characteristics:
large treatment capacity, high defluorination efficiency (generally more than 99 percent), no discharge of wastewater containing fluorine, no problems of secondary pollution, equipment corrosion and the like, and lower capital construction cost and operating cost.
The purifying agent is prepared with calcium series compound (calcium oxide, calcium hydroxide or calcium carbonate) and has great surface area, many pores and powerful adsorption capacity, and the fluorine-containing fume is first purified to adsorb fluorine onto the surface of the purifying agent to form recoverable fluoride. The harmless fine powder after fluorine fixation can be used as the raw material of concrete pavement bricks and refractory materials after being packaged.
In summary, the embodiments of the present invention are merely exemplary and should not be construed as limiting the scope of the invention. All equivalent changes and modifications made according to the content of the claims of the present invention should fall within the technical scope of the present invention.
Claims (4)
1. A method for recycling and harmlessly treating a waste aluminum raw material is characterized by comprising the following steps: the method mainly comprises the following steps:
(1) factory inspection of aluminum scrap raw material
Carrying out analysis and detection on the waste aluminum materials when the waste aluminum materials are transported into a factory area, wherein the analysis and detection comprise the monitoring of containers entering the factory and the monitoring of the waste aluminum materials before the waste aluminum materials are fed into a furnace, and the waste aluminum materials are directly returned to suppliers after the detection is unqualified; the heavy metal content in the waste aluminum materials before entering the furnace is strictly controlled, the raw materials meeting the requirements are sent into a closed material grid of a material processing workshop for stacking, and the goods not meeting the requirements are returned to a supplier;
(2) pretreatment of aluminum scrap raw material
The raw material pretreatment process is arranged in a closed material processing workshop, 3 sets of full-automatic aluminum scrap raw material shredding, screening, winnowing, magnetic separation and eddy current separation equipment are arranged in the step, each set of pretreatment equipment comprises 2 pretreatment production lines and is used for respectively treating the aluminum scrap raw material packed into blocks and scattered aluminum scrap raw material;
(3) preheating paint removal
In the preheating stage, a paint removing roller is adopted, and the preheating process realizes the preheating of the waste aluminum raw material and the paint removing of the waste aluminum raw material at the same time; in the preheating and paint removing process, only when the temperature of the furnace is raised in the driving stage and the material is not fed yet, the preheating waste gas of the roller directly enters a waste gas treatment system of a production line without secondary treatment of a combustion chamber;
in the step, a central heat accumulating type heat exchange system is adopted, so that the temperature of the flue gas is quickly reduced from more than 900 ℃ to less than 230 ℃ within 1s after heat exchange is carried out by a heat accumulator when the flue gas is led out of a hearth, and the flue gas after being rapidly cooled avoids the re-synthesis of dioxin substances;
(4) melting
The method adopts a double-chamber reflection smelting furnace, divides a partition wall for the traditional reflection furnace into a heating chamber and a feeding chamber, and mainly comprises the heating chamber, the feeding (slagging) chamber, an aluminum liquid circulating system, a regenerative combustion system, a control system, a feeding system and the like;
the heating chamber is mainly used for providing main energy for smelting, and discharging the aluminum liquid after the temperature and chemical components are adjusted to be proper; the feeding (slagging-off) chamber is mainly used for feeding and melting the waste aluminum materials, is separated from the heating chamber by a partition wall with channels at the upper part and the lower part, and the two channels are respectively used for the passing of smoke and aluminum liquid;
(5) refining by tempering
After the smelting is finished, entering a quality-adjusting refining process, wherein the quality-adjusting refining process can be carried out in a smelting furnace and a heat-preserving furnace; the aluminum liquid needs to stay for about 2 hours in the quenching and tempering refining process, the temperature of a molten pool is kept at 680-750 ℃, and the temperature of a hearth is kept at 800-1000 ℃; the furnace liquid is subjected to the working procedures of stirring, tempering, degassing, standing, slagging-off and heat preservation in sequence, and the additive is introduced into the aluminum liquid by taking nitrogen as carrier gas;
(6) rotary furnace and aluminum ash harmless treatment
Each production line in the step is provided with 23 t rotary furnaces, 1 cold ash cylinder, 1 set of aluminum ash crushing/screening system and 1 set of aluminum ash innocent treatment system in a matching way, and the systems are used for the innocent treatment of metal aluminum and aluminum ash, collected dust, electrolytic aluminum ash and regenerated aluminum ash in the recovered slag;
in the smelting furnace and the refining heat preservation furnace, furnace slag is generated besides the aluminum liquid; slagging-off generated by the smelting and refining furnace contains about 30-50% of metal aluminum, and the hot aluminum slag after mechanical slagging-off is sent into a matched aluminum slag rotary furnace; further recovering the metal aluminum therein;
23 t rotary furnaces are arranged on each production line of the project; is used for treating the aluminum slag and recovering the metal aluminum.
2. The method of claim 1, wherein: the step (2) comprises the following steps:
firstly, feeding a waste aluminum raw material into pretreatment equipment for shredding, wherein the size of the shredded waste aluminum raw material is 2-10 cm;
then, sorting the aluminum materials after shredding by the particle size of the waste aluminum materials through a screening roller, and returning the aluminum materials with large particle size to the shredder for reprocessing;
then, separating ferromagnetic impurities and impurities with a large amount of iron inserts from the waste aluminum materials by the magnetic separator under the action of magnetic force;
and finally, separating other metal impurities from the material by eddy current, pretreating the waste aluminum material, manually separating, classifying and stacking the waste aluminum material in a material grid.
3. The method of claim 1, wherein: the step (4) comprises the following steps:
the method comprises the following steps:
① feeding, namely, the preheated and depainted fine aluminum scrap is sent to a vortex feeding well through a closed pipeline by a vibrating feeder and a belt conveyor, and the scattered aluminum scrap is quickly involved in the high-temperature aluminum liquid vortex to be quickly melted;
② melting, namely injecting natural gas into 2 burners on the side wall of a melting furnace (100T), burning in a hearth, keeping the temperature of a molten pool at 720-810 ℃, keeping the temperature of the hearth at 900-1050 ℃, after feeding, closing a charging chamber furnace door, and melting the waste aluminum material by the molten pool, wherein the melting furnace takes the natural gas as fuel, the melting time is about 6 hours in one production period, and the double-chamber furnace takes the aluminum liquid as the molten pool, and the preheated furnace material directly enters the molten pool to be melted.
4. The method of claim 1, wherein: the step (6) of performing dry defluorination denitrification aluminum ash harmless treatment on the collected aluminum ash comprises the following processes:
① heating the slag in a rotary furnace to be used as an initial heat source, and performing heat treatment in a direct heating mode, wherein the temperature is controlled at 900-1200 ℃;
② starting the rotary furnace to rotate at a certain speed, gradually adding the collected fine aluminum ash, and introducing compressed air at 3-5m speed/hr to assist the furnace to burn completely;
③ when the rotary furnace continuously rotates and burns for 3 hours until the metal aluminum burns completely, the rotation is stopped;
④ sending the completely combusted aluminum ash to a cold ash system for cooling;
⑤ when the aluminum ash is cooled to normal temperature, the aluminum ash is harmless, and the aluminum ash is directly packed by ton bags and can be used as raw materials of concrete pavement bricks and refractory materials.
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| CN113293302A (en) * | 2021-06-02 | 2021-08-24 | 洛阳托普热能技术有限公司 | Waste aluminum wheel hub recycling production line and production method thereof |
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| CN112280985A (en) * | 2020-10-07 | 2021-01-29 | 东北大学 | Method for manufacturing high-strength and high-toughness aluminum alloy by adopting recycled aluminum |
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| CN116103510A (en) * | 2022-12-08 | 2023-05-12 | 秦皇岛信宝资源循环科技有限公司 | Circulating composite aluminum smelting process |
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