Harmless regeneration treatment method of aluminum ash

Abstract

The invention discloses a harmless regeneration treatment method of aluminum ash, and relates to the field of solid waste treatment, and the harmless regeneration treatment method comprises the following steps: S1, raw material proportioning, S2, homogenization slurrying, S3, metal aluminum extraction, S4, diversion electric wave specific gravity separation, S5, dynamic reaction, S6, reaction tail gas utilization, S7, ion separation, S8, drying treatment, S9, roasting phase inversion, S10, chlorine salt and sulfate recovery, and S11, Raymond powder grinding. Tiny metal aluminum in the aluminum ash can be extracted and used as an aluminum alloy production raw material; soluble salt in the aluminum ash can be recycled, and products such as sodium chloride industrial salt and aluminum alloy flux can be produced. Harmful nitrogen in the aluminum ash can be converted into ammonia water to be recycled; the hydrogen generated when the aluminum ash encounters water can be used as a heat source, an aluminum oxide substitute material, namely regenerated aluminum oxide, can be produced, and can be applied to the fields of refractory materials, abrasives, coatings, ceramic materials, white cement raw materials and the like; the comprehensive utilization of the aluminum ash slag is realized.

Description

Technical Field

[0001] The invention relates to the field of solid waste treatment, and in particular to a harmless regeneration treatment method for aluminum ash slag. Background Art

[0002] Aluminum ash is a waste product generated during the production process of the aluminum industry. The chemical components in aluminum ash are harmful to the environment and human health. Aluminum ash contains aluminum nitride, metallic aluminum, and aluminum carbide. When aluminum nitride comes into contact with water or humid air, it is very easy to undergo hydrolysis reaction to generate ammonia with a pungent odor, which pollutes the air; when metallic aluminum reacts with water, it will generate hydrogen, and when aluminum carbide reacts with water, it will generate methane. Both hydrogen and methane have the risk of combustion and explosion. Aluminum ash also contains a high content of alkali metal oxides, fluorides, chlorides, etc. Long-term accumulation will pollute the soil and groundwater, seriously affecting the ecological environment and people's health and safety. It has obvious toxicity (T) and reactivity (R).

[0003] Aluminum ash can be divided into primary aluminum ash and secondary aluminum ash according to the degree of treatment and disposal. Primary aluminum ash is mainly aluminum ash directly produced in the electrolytic aluminum section and the secondary aluminum melting section. It is manifested as aluminum slag directly discharged from the melting section and scum produced by the electrolytic alumina section. No metallic aluminum has been extracted. The main components are metallic aluminum, fluoride salts, aluminum oxide and aluminum nitride, etc., and it has a high value for the recycling of metallic aluminum. Secondary aluminum ash is the waste after the primary aluminum ash is melted to extract metallic aluminum or the aluminum-containing waste slag produced in the aluminum refining process. The metallic aluminum content contained is significantly lower than that of primary aluminum ash. The general extraction method can no longer extract metallic aluminum. Therefore, secondary aluminum ash no longer has recycling value, but is directly disposed of as hazardous waste.

[0004] Therefore, it is necessary to design a harmless regeneration treatment method for secondary aluminum ash. Summary of the invention

[0005] In order to overcome the above-mentioned shortcomings, the present invention provides a technical solution that can solve the above-mentioned problems.

[0006] A harmless regeneration method for aluminum ash slag comprises the following steps:

[0007] Step S1, pre-proportioning the aluminum ash slag so that the aluminum slag contains 25-55% aluminum, 2.8-10% magnesium, 0.8-5% silicon, 0.8-3.5% chlorine, 0.3-1.2% potassium, 0.8-2.2% sodium, 0.1-1% calcium, and 0.3-3.2% nitrogen;

[0008] Step S2, adding low-temperature water at 3-30°C to the aluminum ash slag for pulping, wherein the liquid-to-solid ratio of the pulping is 3-8:1, and adding a reaction inhibitor at a ratio of 1.8-6.2‰ during the pulping, wherein the reaction inhibitor forms a polymerized mucous film between the water and the metal surface;

[0009] Step S3, putting the slurry into an extraction system, which includes a diameter expansion processing device, a diversion device and a screening device. The diameter expansion processing device is provided with grinding balls, and the aluminum ash material in the slurry is repeatedly crushed and impacted by the high-hardness grinding balls. The grinding balls rotate continuously for 15-60 minutes, and then enter the diversion device. Finally, the metal aluminum with a particle size less than 200 mesh is screened out by the screening device;

[0010] Step S4, putting the slurry into a sorting device, wherein the sorting device is provided with a guide channel, wherein the guide channel has two or more diversion channels, wherein the two or more guide channels are arranged into a composite multiple spiral shape according to the magnetic field strength characteristics, and a mesh structure is interlaced in the middle of the guide channel, and the total length of the guide channel is 10-20 meters, and the slurry flows slowly in the guide channel, and the slurry removes the dyed metal oxide with the magnetic medium under the action of the high-intensity magnetic field;

[0011] Step S5, placing the slurry and the catalyst into a denitrification reactor at the same time to react and remove nitrogen, the denitrification reactor adopts a horizontal cylindrical ball mill;

[0012] Step S6: During the reaction process of the nitrogen removal reactor in step S5, a mixed gas is generated. The mixed gas includes ammonia, hydrogen and water vapor. The temperature of the mixed gas is 90-115°C. The mixed gas is cooled by heat exchange in the primary heat exchanger of the steam boiler and then enters the ammonia absorption tower. The ammonia absorption tower absorbs the ammonia into ammonia water with a concentration of 18-32%. The remaining hydrogen is used as the fuel gas source of the steam boiler. When the steam boiler is working, steam is generated. Part of the steam is used in the wastewater treatment device, and the excess steam is incorporated into the park. When the steam is stopped, the hydrogen enters the high-temperature phase-transition tunnel kiln and mixes with the natural gas to assist the combustion of the natural gas.

[0013] Step S7, after the deamination reaction, the liquid-solid ratio of the slurry is 3-6:1, and then the slurry is placed in an ion separation device, and the ion separation device washes and separates the soluble salt in the slurry;

[0014] Step S8, after ion separation, the water content of the slurry is 18-55%, and the slurry is dried to obtain a low-temperature regenerated alumina product;

[0015] Step S9, pressing the material with a water content of 5-15% into bricks, stacking them on a kiln car, and transporting them into a tunnel kiln through the kiln car for roasting at a temperature of 1000-1400° C. for 10-20 hours. After high-temperature roasting, aluminum trihydrate is converted into α-Al2O3, and high-temperature roasting can remove residual anions in the material;

[0016] Step S10: During high-temperature roasting, volatile chlorine and sulfate ions are generated. These gases are absorbed and dissolved by the circulating water spray of the exhaust tower as tail gas. When the circulating water concentration reaches the treatment standard, it is sent to the MVR wastewater treatment system for the recovery of chloride and sulfate.

[0017] Step S11, after roasting and cooling, the alumina product with high purity and whiteness is obtained, which is then roughly crushed by a coarse crusher, and then put into a Raymond mill, and ground into a product with a particle size of 100-1200 mesh by the Raymond mill.

[0018] Furthermore, in step S3, the temperature of the extraction system is maintained below 15°C, and a temperature measurement, pH control device and an automatic temperature-controlled water replenishing device are provided in the extraction system to keep the pH value of the slurry below 10.

[0019] Furthermore, in step S3, the temperature of the extraction system is maintained below 25°C, and a temperature measurement, pH control device and an automatic temperature-controlled water replenishing device are provided in the extraction system to keep the pH value of the slurry below 10.

[0020] Furthermore, in step S4, the magnetic flux of the guide channel in the sorting device is 20,000-30,000 Gauss.

[0021] Furthermore, in step S5, a spiral guide baffle with a height of 2 / 3 of the diameter is set inside the denitrification reactor, and high-aluminum grinding balls are installed in the denitrification reactor to drive the denitrification reactor to rotate continuously at a speed of 5-30 rpm, and the temperature during the deamination reaction is controlled at 60-110°C, the residence time of the slurry in the denitrification reactor is 30-75 minutes, and the particle size of the slurry after the deamination reaction increases to 300-600 mesh.

[0022] Furthermore, in step S5, under the action of the catalyst, the aluminum nitride and the metal aluminum in the slurry undergo the following reaction:

[0023] S501, AlN+3H2O=Al(OH)3+NH3↑;

[0024] S502, 2Al+6H2O→2Al(OH)3+3H2↑;

[0025] S503, 2Al+2NaOH+2H2O=2NaAlO2+3H2↑.

[0026] Further, in step S7, the ion separation device includes a high-speed centrifugal separation device, a filter press device and a vacuum filtration device;

[0027] S701, the slurry first enters a high-speed centrifugal separation device, and is rotated at a high speed by the high-speed centrifugal separation device, and the speed is maintained at 3000-5000 rpm. The water in the slurry is thrown out under the action of the centrifuge, and the slurry is dehydrated into a filter residue with a water content of 20-30%. Then, low salt water is added to the filter residue for stirring and slurrying. The liquid-to-solid ratio of the slurry is 3-5:1, and the dissolution stirring time is 10-20 minutes;

[0028] S702, input the slurry into a filter press device for filtration, the filter press device performs high pressure extrusion on the slurry, the pressure of which is 3-5Mpa, and the filtrate is discharged to obtain a filter residue, the water content of which is 30-40%, and then low salt water is added to the filter residue for stirring and slurrying, the liquid-to-solid ratio of the slurrying is 3-5:1, and the dissolution stirring time is 10-20 minutes;

[0029] S703, inputting the slurry into a vacuum filtration device, which dehydrates the slurry under the action of atmospheric pressure to obtain filter residue, wherein the water content of the filter residue is 35-50%;

[0030] S704, after separation by an ion separation device, a slurry with a soluble salt removal rate of more than 95% is obtained, and the filtrate obtained in the dehydration process is subjected to multi-stage washing by circulating water to obtain a salt water containing soluble salts;

[0031] S705. The salt water is input into the MVR wastewater treatment system for evaporation and condensation treatment. The treated low-salt water will enter the ion separation equipment for repeated use. The salt substances will produce industrial-grade sodium chloride salt and aluminum alloy flux raw materials.

[0032] Further, in step S8, the drying process includes the following two parts:

[0033] S801, centrifugal spray drying; the slurry is pressurized and input into a centrifugal atomization drying device. The slurry is output from the nozzle of the centrifugal atomization drying device. As the nozzle rotates at high speed, the slurry is sprayed into mist-like mud droplets under the action of pressure and centrifugal force. At this time, the mud droplets are sprayed onto the hot flue of the hot blast furnace. The temperature of the hot flue is 550-800°C. The mud droplets are instantly dried into approximately spherical particles when in contact with the high temperature. The spherical particles are then cooled by a cooler at the bottom of the tower until the temperature drops to 40-100°C. At this time, the slurry is discharged, and the moisture content of the discharged material is reduced to 15-45%;

[0034] S802. The granular material is input into the rotary drying device for further drying. The rotary drying device adopts a rotary kiln. The material is heated by the high temperature flame and rotary motion in the rotary kiln to evaporate the water. When the water content of the material drops to 5-15%, a discharging device is set to discharge the material. The discharged material will enter the next process. At the same time, some of the material will remain in the rotary kiln until it is dried to a water content of less than 0.5%, thereby obtaining a low-temperature regenerated alumina product.

[0035] Furthermore, in step S9, the material in the tunnel kiln will produce the following reaction:

[0036] S901, NaAlO2+2H2O=Al(OH)3+NaOH;

[0037] S902, 2Al(OH)3=Al2O3+3H2O;

[0038] S903, 2NaOH = Na2O + H2O;

[0039] S904, Al2O3→α-Al2O3;

[0040] S905, C+O2=CO2.

[0041] Furthermore, in step S11, a Raymond mill is used to grind products with particle sizes of 100-200 mesh, 200-250 mesh, 250-300 mesh, 300-500 mesh, 500-800 mesh, and 800-1200 mesh, respectively.

[0042] Compared with the prior art, the present invention has the following beneficial effects:

[0043] 1. The metallic aluminum in the secondary aluminum ash can be further recovered, and the extraction rate can reach 40-71%. The extracted metallic aluminum particles can be used as recycled aluminum raw materials to produce aluminum alloy rods, thereby improving the utilization value of the secondary aluminum ash.

[0044] 2. The secondary aluminum ash after the extraction of metallic aluminum can reduce the amount of hydrogen produced and improve the safety of the processing equipment during the subsequent harmless treatment process.

[0045] 3. The hydrogen and ammonia produced by the reaction can achieve the effect of full resource utilization. Ammonia can be prepared into ammonia water for use in the production of denitrification, and the surplus ammonia water can also be exported as a product. Hydrogen can be used as a heat source for steam boilers, or it can be mixed with natural gas in tunnel kilns to reduce the use of natural gas.

[0046] 4. The soluble salt in the aluminum ash can be fully recycled to produce industrial-grade sodium chloride salt, aluminum alloy flux and other products.

[0047] 5. The comprehensive utilization of aluminum ash slag has been realized to produce low-temperature regenerated alumina and high-temperature regenerated alumina products, with a production yield of more than 98%. The application areas can cover refractory materials, abrasives, coatings, ceramic materials, white cement raw materials, etc.

[0048] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0050] Figure 1 is a schematic diagram of the method of step S1 to step S10 of the present invention;

[0051] Figure 2 It is a schematic diagram of the operation flow of the present invention. DETAILED DESCRIPTION

[0052] The following will be combined with the specific implementation of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0053] Embodiment 1

[0054] like Figure 1-2 As shown, a harmless regeneration method of aluminum ash slag of the present invention comprises the following steps:

[0055] Step S1, pre-proportioning the aluminum ash slag so that the aluminum slag contains 30-50% aluminum, 1-8% magnesium, 1-4% silicon, 1-3% chlorine, 0.5-1% potassium, 1-2% sodium, 0.1-1% calcium, and 0.5-3% nitrogen;

[0056] Step S2, adding low-temperature water at 5-30°C to the aluminum ash slag for pulping, wherein the liquid-to-solid ratio of the pulping is 3-8:1, and adding a reaction inhibitor at a ratio of 2-6‰ during the pulping, wherein the reaction inhibitor forms a polymerized mucous film between the water and the metal surface;

[0057] Step S3, putting the slurry into an extraction system, the extraction system includes a diameter expansion processing device, a diversion device and a screening device, the diameter expansion processing device is provided with a grinding ball, the aluminum ash material in the slurry is repeatedly rolled and impacted by the high-hardness grinding ball, the grinding ball continuously rotates for 20-60 minutes, and then enters the diversion device, and finally the metal aluminum with a particle size less than 200 mesh is screened out by the screening device, preferably the metal aluminum with a particle size less than 160 mesh is screened out;

[0058] In step S3, the temperature of the extraction system is maintained below 15°C, and a temperature measurement, pH control device and an automatic temperature control water replenishment device are set in the extraction system to keep the pH value of the slurry below 10;

[0059] Step S4, putting the slurry into a sorting device, wherein a guide channel is provided in the sorting device, the guide channel is divided into 3-6 channels, the guide channel is arranged into a composite multiple spiral shape according to the magnetic field strength characteristics, and a mesh structure is interlaced in the middle of the guide channel, and the total length of the guide channel is 10-20 meters, the slurry flows slowly in the guide channel, and the slurry removes the dyed metal oxide with the magnetic medium under the action of the high-intensity magnetic field;

[0060] In step S4, the magnetic flux of the guide channel in the sorting device is 20000-30000 Gauss;

[0061] Step S5, placing the slurry and the catalyst into a denitrification reactor at the same time to react and remove nitrogen, the denitrification reactor adopts a horizontal cylindrical ball mill;

[0062] In step S5, a spiral guide baffle with a height of 2 / 3 of the diameter is set inside the denitrification reactor, and a high-aluminum grinding ball is installed in the denitrification reactor to drive the denitrification reactor to rotate continuously at a speed of 5-30 rpm, and the temperature during the deamination reaction is controlled at 60-110° C., the residence time of the slurry in the denitrification reactor is 30-75 minutes, and the particle size of the slurry after the deamination reaction increases to 300-600 meshes;

[0063] In step S5, under the action of the catalyst, the aluminum nitride and the metal aluminum in the slurry undergo the following reaction:

[0064] S501, AlN+3H2O=Al(OH)3+NH3↑;

[0065] S502, 2Al+6H2O→2Al(OH)3+3H2↑;

[0066] S503, 2Al+2NaOH+2H2O=2NaAlO2+3H2↑.

[0067] Step S6: During the reaction process of the nitrogen removal reactor in step S5, a mixed gas is generated. The mixed gas includes ammonia, hydrogen and water vapor. The temperature of the mixed gas is 95-110° C. The mixed gas is cooled by heat exchange in the primary heat exchanger of the steam boiler and then enters the ammonia absorption tower. The ammonia absorption tower absorbs the ammonia into ammonia water with a concentration of 20-30%. The remaining hydrogen is used as the fuel gas source of the steam boiler. When the steam boiler is working, steam is generated. Part of the steam is used in the wastewater treatment device, and the excess steam is incorporated into the park. When the steam is stopped, the hydrogen enters the high-temperature phase-transition tunnel kiln and mixes with the natural gas to assist the combustion of the natural gas.

[0068] Step S7, after the deamination reaction, the liquid-solid ratio of the slurry is 3-6:1, and then the slurry is placed in an ion separation device, and the ion separation device washes and separates the soluble salt in the slurry;

[0069] In step S7, the ion separation device includes a high-speed centrifugal separation device, a filter press device and a vacuum filtration device;

[0070] S701, the slurry first enters a high-speed centrifugal separation device, and is rotated at a high speed by the high-speed centrifugal separation device, and the speed is maintained at 3000-5000 rpm. The water in the slurry is thrown out under the action of the centrifuge, and the slurry is dehydrated into a filter residue with a water content of 20-30%. Then, low salt water is added to the filter residue for stirring and slurrying. The liquid-to-solid ratio of the slurry is 3-5:1, and the dissolution stirring time is 10-20 minutes;

[0071] S702, input the slurry into a filter press device for filtration, the filter press device performs high pressure extrusion on the slurry, the pressure of which is 3-5Mpa, and the filtrate is discharged to obtain a filter residue, the water content of which is 30-40%, and then low salt water is added to the filter residue for stirring and slurrying, the liquid-to-solid ratio of the slurrying is 3-5:1, and the dissolution stirring time is 10-20 minutes;

[0072] S703, inputting the slurry into a vacuum filtration device, which dehydrates the slurry under the action of atmospheric pressure to obtain filter residue, wherein the water content of the filter residue is 40-45%;

[0073] S704, after separation by an ion separation device, a slurry with a soluble salt removal rate of more than 95% is obtained, and the filtrate obtained in the dehydration process is subjected to multi-stage washing by circulating water to obtain a salt water containing soluble salts;

[0074] S705, inputting the salt water into the MVR wastewater treatment system for evaporation and condensation treatment, the treated low-salt water will enter the ion separation equipment for repeated use, and the salt substances will produce sodium chloride industrial-grade salt and aluminum alloy flux raw materials;

[0075] Step S8, after ion separation, the water content of the slurry is 20-50%, and the slurry is dried to obtain a low-temperature regenerated alumina product;

[0076] In step S8, the drying process includes the following two parts:

[0077] S801, centrifugal spray drying; the slurry is pressurized and input into a centrifugal atomization drying device. The slurry is output from the nozzle of the centrifugal atomization drying device. As the nozzle rotates at high speed, the slurry is sprayed into mist-like mud droplets under the action of pressure and centrifugal force. At this time, the mud droplets are sprayed onto the hot flue of the hot blast furnace. The temperature of the hot flue is 600-750°C. The mud droplets are instantly dried into approximately spherical particles when in contact with the high temperature. The spherical particles are then cooled by a cooler at the bottom of the tower until the temperature drops to 40-100°C. At this time, the slurry is discharged, and the water content of the discharged material is reduced to 20-40%;

[0078] S802, the granular material is input into the rotary drying device for further drying. The rotary drying device adopts a rotary kiln. The material is heated by the high temperature flame and rotary motion in the rotary kiln to evaporate the water. When the water content of the material drops to 5-15%, a discharging device is set to discharge the material. The discharged material will enter the next process. At the same time, some of the material will remain in the rotary kiln until it is dried to a water content of less than 0.5%, thereby obtaining a low-temperature regenerated alumina product.

[0079] Step S9, pressing the material with a water content of 5-15% into bricks, stacking them on a kiln car, and transporting them into a tunnel kiln through the kiln car for roasting at a temperature of 1000-1400° C. for 10-20 hours. After high-temperature roasting, aluminum trihydrate is converted into α-Al2O3, and high-temperature roasting can remove residual anions in the material;

[0080] In step S9, the materials in the tunnel kiln will produce the following reactions:

[0081] S901, NaAlO2+2H2O=Al(OH)3+NaOH;

[0082] S902, 2Al(OH)3=Al2O3+3H2O;

[0083] S903, 2NaOH = Na2O + H2O;

[0084] S904, Al2O3→α-Al2O3;

[0085] S905, C+O2=CO2.

[0086] Step S10: During high-temperature roasting, volatile chlorine and sulfate ions are generated. These gases are absorbed and dissolved by the circulating water spray of the exhaust tower as tail gas. When the circulating water concentration reaches the treatment standard, it is sent to the MVR wastewater treatment system for the recovery of chloride and sulfate.

[0087] Step S11, after roasting and cooling, the alumina product with high purity and whiteness is obtained, which is then roughly crushed by a coarse crusher, and then put into a Raymond mill, and ground into a product with a particle size of 100-1200 mesh by the Raymond mill;

[0088] In step S11, a Raymond mill is used to grind products with particle sizes of 100-200 mesh, 200-250 mesh, 250-300 mesh, 300-500 mesh, 500-800 mesh, and 800-1200 mesh, respectively.

[0089] Embodiment 2

[0090] like Figure 1-2 As shown, a harmless regeneration method of aluminum ash slag of the present invention comprises the following steps:

[0091] S1. Raw material ratio

[0092] The aluminum ash slag is pre-proportioned according to the product requirements. The proportion requirements are: aluminum 30-40%, magnesium 1-5%, silicon 1-4%, chlorine 1-3%, potassium 0.5-1%, sodium 1-2%, calcium 0.1-1%, nitrogen 0.5-3%, etc.

[0093] The ingredient formula is determined based on the characteristics of each element in the aluminum ash and the reaction mechanism in the subsequent production process. It is determined after many proportioning experiments. Through a specific ingredient formula, the production system can be kept stable and efficient, and various types of recycled alumina products with special application fields can be prepared. The application fields cover refractory materials, abrasives, coatings, ceramic materials, white cement raw materials, etc.

[0094] S2. Homogenization and pulping

[0095] The production system uses low-temperature water as the dispersion medium and adopts a liquid-to-solid ratio of 3:1 for slurrying. There are also alternative solid-liquid ratio schemes of 5:1 and 8:1 respectively. Low-temperature water is produced by circulating refrigeration equipment, and the temperature is controlled at 5-30°C. Low-temperature water can effectively inhibit the reactivity of aluminum ash slag with water, and a reaction inhibitor is added at a ratio of 2-6‰. The inhibitor is prepared from several organic polymers, and the main components are carbon, hydrogen, oxygen, and nitrogen. It can form a polymerized mucous film between water and the metal surface to prevent the aluminum ash slag from reacting with water too early and ensure the extraction rate of metallic aluminum particles.

[0096] S3. Metal Aluminum Extraction

[0097] The extraction system is divided into a diameter expansion device, a diversion device, and a screening device. The rotating device of the diameter expansion device is equipped with alumina grinding balls. The high-hardness grinding balls repeatedly roll and impact the aluminum ash material to increase the particle size of the metal aluminum particles. The rotation lasts for 20-60 minutes. Then enter the diversion device, and in the multi-stage screening device, the metal aluminum with a particle size of less than 160 mesh is screened out. The alternative is to screen out the metal aluminum with a particle size of less than 200 mesh.

[0098] The extraction system is equipped with temperature measurement, pH control devices, and automatic temperature-controlled water replenishment devices at multiple equipment points to ensure that the temperature of the entire process is below 15°C. The backup plan is to keep the temperature below 25°C. The pH value of the medium material needs to be controlled below 10 to ensure that the hydrolysis reaction of the material is suppressed.

[0099] S4, guided wave specific gravity sorting

[0100] The device has a guide channel with a magnetic flux of 20,000 Gauss, and a backup guide channel with a magnetic flux of 30,000 Gauss. The guide channels are divided into 3-6 channels, which are distributed in a complex multiple spiral shape according to the intensity characteristics of the magnetic field, and have a mesh structure in the middle. The total length is 10-20 meters. The material flows slowly in the guide channel. Under the action of the high-intensity magnetic field, the coloring metal oxides such as iron, manganese, and nickel in the material are sorted and removed. Through this process, the roasting whiteness of the material can be increased by 10-20%.

[0101] S5. Dynamic response

[0102] The materials treated by the above process are subjected to nitrogen removal reaction in a specially made reactor. The main body of the reactor is a horizontal cylindrical ball mill, which is equipped with a spiral guide baffle with a height of 2 / 3 of the diameter inside the reactor and is filled with high-aluminum grinding balls. Through the continuous rotation of the reactor, the speed is 5-30 rpm. Under the action of the catalyst, the aluminum nitride and metal aluminum in the material undergo the following reactions:

[0103] AlN+3H2O=Al(OH)3+NH3↑;

[0104] 2Al+6H2O→2Al(OH)3+3H2↑;

[0105] 2Al+2NaOH+2H2O=2NaAlO2+3H2↑.

[0106] The materials in the reactor react rapidly under the action of the catalyst, and the temperature is controlled at 60-110°C. As the equipment rotates continuously, the grinding balls continuously stir and grind the materials, and under the action of the guide baffle, the materials are discharged from the tail of the reactor at a uniform speed, ensuring that the time of the materials in the reactor is controlled within 30-75 minutes. During this time, the materials can fully react, and the particle size can be increased to 300-600 meshes, with a median particle size of 500 meshes.

[0107] S6. Utilization of reaction tail gas

[0108] The deamination reaction will produce a mixed tail gas containing ammonia, hydrogen and water vapor with a temperature of 95-110°C. The mixed gas passes through the primary heat exchanger of the steam boiler equipped with the production system, and enters the ammonia absorption tower after heat exchange and cooling. The ammonia absorption tower absorbs the ammonia into ammonia water with a concentration of 30%. The remaining hydrogen is used as the fuel source of the steam boiler to produce steam. The steam is used in the wastewater treatment device in the production system, and the excess steam is incorporated into the park for use. When the steam is stopped, the hydrogen can enter the high-temperature phase-transition tunnel kiln and mix with natural gas for combustion, which can reduce the natural gas consumption by 30-45%.

[0109] S7, ion separation

[0110] The liquid-to-solid ratio of the material slurry after the reaction is 3:1, and there are alternative solutions with a liquid-to-solid ratio of 5:1 and a liquid-to-solid ratio of 6:1. In the ion separation system equipment, the soluble salt in the material is washed and separated. The ion separation system has three types of solid-liquid separation devices:

[0111] The first is a high-speed centrifugal separation device, which can rotate at a high speed of 3000-5000 rpm. The water in the slurry is thrown out due to the centrifugal effect, and the slurry is dehydrated into a filter residue with a moisture content of 20-30%, so that the soluble salt is separated with the water. The filter residue is then stirred with low-salt water to make a slurry. The liquid-to-solid ratio of the slurry is 3-5:1, and the dissolution and stirring time is 10-20 minutes;

[0112] The second is a filter press device, in which the slurry is filtered. When the amount of slurry passing through reaches a predetermined amount, the slurry is stopped and the filter press device is used for high-pressure extrusion at a pressure of 3-5Mpa to discharge the filtrate. The water content of the remaining filter residue is 30-40%. The filter residue is then stirred with low salt water to make a slurry. The liquid-to-solid ratio of the slurry is 3:1, and there is also a backup plan of 5:1. The dissolution stirring time is 10-20 minutes;

[0113] The third type is a vacuum filtration device. The slurry is placed in the vacuum filtration device and dehydrated under atmospheric pressure to obtain a filter residue with a moisture content of 40-45%.

[0114] The ion separation system is a combination of these three types of solid-liquid separation equipment. It can remove soluble salts from the slurry with a removal rate of over 95%. The circulating water is then washed through multiple stages to gradually increase the concentration of soluble salts. Finally, the salty water with the highest concentration is input into the MVR wastewater treatment system for evaporation and condensation treatment. The treated low-salt water enters the three solid-liquid separation devices in the ion separation system for repeated use. The salt substances can produce industrial-grade sodium chloride salt and raw materials for aluminum alloy flux.

[0115] S8. Drying

[0116] After ion separation, the water content of the slurry is 20-50%, and it needs to be dried to remove the remaining moisture. The slurry drying system is divided into two parts. One is the centrifugal spray drying. The equipment used to implement the process is a centrifugal atomization drying device. The slurry is pressurized and sent to the nozzle position. Through the high-speed rotation of the nozzle, the slurry is sprayed into a mist under the action of pressure and centrifugal force. The area of ​​contact between the mud droplets and the gas is very large. When it meets the hot flue gas generated by the hot blast furnace, the gas temperature of the hot flue gas is 600-750℃, and it will be dried into approximately spherical particles in a very short time. The particles are cooled to 40-100℃ through the cooler at the bottom of the tower and then discharged. At this time, the water content of the material will drop to 20-40%.

[0117] The granular material is placed in a rotary drying device for further drying. The rotary drying device uses a rotary kiln, which heats the material through high-temperature flames and rotary motion to evaporate the moisture therein, thereby achieving the purpose of drying. The fuel and primary air for combustion are sent into the combustion chamber through the kiln head burner to form a high-temperature flame, releasing a large amount of heat, which is then transferred to the material to increase its temperature and evaporate the moisture.

[0118] In the rotary drying device, as the drying process continues, the material is dried until it is nearly dry, and the moisture content of the material will drop to the stage of 5-15%. A discharging device is also provided to discharge part of the material with a moisture content of 5-15%. The discharged material will enter the next process, and the remaining material will continue to be dried to a moisture content of <0.5%, which can be used as a low-temperature regenerated alumina product. The characteristic of this part of the regenerated alumina product is that it contains aluminum trihydrate, which can be used as a raw material for aluminum-silicon refractory materials.

[0119] S9, calcination phase transition

[0120] The materials with water content reduced to 5-15% are pressed into bricks and stacked on kiln cars. The kiln cars enter the tunnel kiln for baking at 1000-1400℃ for 10-20 hours. In the tunnel kiln, the materials undergo the following reactions:

[0121] NaAlO2+2H2O=Al(OH)3+NaOH;

[0122] 2Al(OH)3=Al2O3+3H2O;

[0123] 2NaOH=Na2O+H2O;

[0124] Al2O3→α-Al2O3;

[0125] C+O2=CO2.

[0126] S10, recovery of chloride and sulfate

[0127] After high-temperature roasting, aluminum trihydrate is converted into α-Al2O3. At the same time, high-temperature roasting can remove residual anions such as chlorine, fluorine, and sulfate in the material. The tail gas generated by the volatile chlorine and sulfate ions will be absorbed and dissolved by the circulating water spray of the exhaust tower. When the circulating water concentration reaches the treatment standard, it is sent to the MVR wastewater treatment system to recover chloride and sulfate, realizing the full recycling of resources.

[0128] S11, Raymond mill

[0129] The material after roasting and cooling is an alumina product with high purity and whiteness. It is then coarsely crushed and Raymond ground into powder with a wide range of particle size distribution. It is then screened at multiple levels to ultimately produce products with a variety of particle sizes, including products with particle sizes of 100-200 mesh, 200-250 mesh, 250-300 mesh, 300-500 mesh, 500-800 mesh, and 800-1200 mesh, to meet the needs of different customers.

[0130] In the above two implementation cases of the present invention, both are applicable to the resource-based recycling of various substances in aluminum ash slag hazardous waste, achieving the following technical effects:

[0131] 1. Tiny metallic aluminum can be extracted from aluminum ash and used as raw material for aluminum alloy production.

[0132] 2. The soluble salt in aluminum ash can be recycled to produce products such as industrial-grade sodium chloride salt and aluminum alloy flux.

[0133] 3. Harmful nitrogen in aluminum ash can be converted into ammonia water for recycling.

[0134] 4. The hydrogen generated by aluminum ash slag in contact with water can be used as a heat source.

[0135] 5. It can produce alumina substitute materials: recycled alumina, which has application areas including refractory materials, abrasives, coatings, ceramic materials, white cement raw materials, etc.

[0136] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be considered exemplary and non-restrictive in all respects, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims be included in the present invention.

Claims

1. A harmless regeneration method for aluminum ash slag, characterized in that: The steps include: Step S1, pre-proportioning the aluminum ash slag so that the aluminum slag contains 25-55% aluminum, 2.8-10% magnesium, 0.8-5% silicon, 0.8-3.5% chlorine, 0.3-1.2% potassium, 0.8-2.2% sodium, 0.1-1% calcium, and 0.3-3.2% nitrogen; Step S2, adding low-temperature water at 3-30°C to the aluminum ash slag for pulping, wherein the liquid-to-solid ratio of the pulping is 3-8:1, and adding a reaction inhibitor at a ratio of 1.8-6.2‰ during the pulping, wherein the reaction inhibitor forms a polymerized mucous film between the water and the metal surface; Step S3, putting the slurry into an extraction system, which includes a diameter expansion processing device, a diversion device and a screening device. The diameter expansion processing device is provided with grinding balls, and the aluminum ash material in the slurry is repeatedly crushed and impacted by the high-hardness grinding balls. The grinding balls rotate continuously for 15-60 minutes, and then enter the diversion device. Finally, the metal aluminum with a particle size less than 200 mesh is screened out by the screening device; Step S4, putting the slurry into a sorting device, wherein the sorting device is provided with a guide channel, wherein the guide channel has two or more diversion channels, wherein the two or more guide channels are arranged into a composite multiple spiral shape according to the magnetic field strength characteristics, and a mesh structure is interlaced in the middle of the guide channel, and the total length of the guide channel is 10-20 meters, and the slurry flows slowly in the guide channel, and the slurry removes the dyed metal oxide with the magnetic medium under the action of the high-intensity magnetic field; Step S5, placing the slurry and the catalyst into a denitrification reactor at the same time to react and remove nitrogen, the denitrification reactor adopts a horizontal cylindrical ball mill; Step S6: During the reaction process of the nitrogen removal reactor in step S5, a mixed gas is generated. The mixed gas includes ammonia, hydrogen and water vapor. The temperature of the mixed gas is 90-115°C. The mixed gas is cooled by heat exchange in the primary heat exchanger of the steam boiler and then enters the ammonia absorption tower. The ammonia absorption tower absorbs the ammonia into ammonia water with a concentration of 18-32%. The remaining hydrogen is used as the fuel gas source of the steam boiler. When the steam boiler is working, steam is generated. Part of the steam is used in the wastewater treatment device, and the excess steam is incorporated into the park. When the steam is stopped, the hydrogen enters the high-temperature phase-transition tunnel kiln and mixes with the natural gas to assist the combustion of the natural gas. Step S7, after the deamination reaction, the liquid-to-solid ratio of the slurry is 3-6:1, and then the slurry is placed in an ion separation device, and the ion separation device washes and separates the soluble salt in the slurry; Step S8, after ion separation, the water content of the slurry is 18-55%, and the slurry is dried to obtain a low-temperature regenerated alumina product; Step S9, pressing the material with a water content of 5-15% into bricks, stacking them on a kiln car, and transporting them into a tunnel kiln through the kiln car for roasting at a temperature of 1000-1400° C. for 10-20 hours. After high-temperature roasting, aluminum trihydrate is converted into α-Al2O3, and high-temperature roasting can remove residual anions in the material; Step S10: During high-temperature roasting, volatile chlorine and sulfate ions are generated. These gases are absorbed and dissolved by the circulating water spray of the exhaust tower as tail gas. When the circulating water concentration reaches the treatment standard, it is sent to the MVR wastewater treatment system for the recovery of chloride and sulfate. Step S11, after roasting and cooling, the alumina product with high purity and whiteness is obtained, which is then roughly crushed by a coarse crusher, and then put into a Raymond mill, and ground into a product with a particle size of 100-1200 mesh by the Raymond mill.

2. The harmless regeneration method of aluminum ash slag according to claim 1 is characterized in that: In step S3, the temperature of the extraction system is maintained below 15°C, and a temperature measurement, pH control device and an automatic temperature control water replenishment device are provided in the extraction system to keep the pH value of the slurry below 10.

3. The harmless regeneration method of aluminum ash slag according to claim 1 is characterized in that: In step S3, the temperature of the extraction system is maintained below 25°C, and a temperature measurement, pH control device and an automatic temperature control water replenishment device are provided in the extraction system to keep the pH value of the slurry below 10.

4. The harmless regeneration method of aluminum ash slag according to claim 1 is characterized in that: In step S4, the magnetic flux of the guide channel in the sorting device is 20000-30000 Gauss.

5. The harmless regeneration method of aluminum ash slag according to claim 1 is characterized in that: In step S5, a spiral guide baffle with a height of 2 / 3 of the diameter is set inside the denitrification reactor, and high-aluminum grinding balls are installed in the denitrification reactor to drive the denitrification reactor to rotate continuously at a speed of 5-30 rpm, and the temperature during the deamination reaction is controlled at 60-110°C, the residence time of the slurry in the denitrification reactor is 30-75 minutes, and the particle size of the slurry after the deamination reaction increases to 300-600 mesh.

6. A harmless regeneration method for aluminum ash slag according to any one of claims 1 or 5, characterized in that: In step S5, under the action of the catalyst, the aluminum nitride and the metal aluminum in the slurry undergo the following reaction: S501, AlN+3H2O=Al(OH)3+NH3↑; S502, 2Al+6H2O→2Al(OH)3+3H2↑; S503, 2Al+2NaOH+2H2O=2NaAlO2+3H2↑.

7. The harmless regeneration method of aluminum ash slag according to claim 1 is characterized in that: In step S7, the ion separation device includes a high-speed centrifugal separation device, a filter press device and a vacuum filtration device; S701, the slurry first enters a high-speed centrifugal separation device, and is rotated at a high speed by the high-speed centrifugal separation device, and the speed is maintained at 3000-5000 rpm. The water in the slurry is thrown out under the action of the centrifuge, and the slurry is dehydrated into a filter residue with a water content of 20-30%. Then, low salt water is added to the filter residue for stirring and slurrying. The liquid-to-solid ratio of the slurry is 3-5:1, and the dissolution stirring time is 10-20 minutes; S702, input the slurry into a filter press device for filtration, the filter press device performs high pressure extrusion on the slurry, the pressure of which is 3-5Mpa, and the filtrate is discharged to obtain a filter residue, the water content of which is 30-40%, and then low salt water is added to the filter residue for stirring and slurrying, the liquid-to-solid ratio of the slurrying is 3-5:1, and the dissolution stirring time is 10-20 minutes; S703, inputting the slurry into a vacuum filtration device, which dehydrates the slurry under the action of atmospheric pressure to obtain filter residue, wherein the water content of the filter residue is 35-50%; S704, after separation by an ion separation device, a slurry with a soluble salt removal rate of more than 95% is obtained, and the filtrate obtained in the dehydration process is subjected to multi-stage washing by circulating water to obtain a salt water containing soluble salts; S705. The salt water is input into the MVR wastewater treatment system for evaporation and condensation treatment. The treated low-salt water will enter the ion separation equipment for repeated use. The salt substances will produce industrial-grade sodium chloride salt and aluminum alloy flux raw materials.

8. The harmless regeneration method of aluminum ash slag according to claim 1 is characterized in that: In step S8, the drying process includes the following two parts: S801, centrifugal spray drying; the slurry is pressurized and input into a centrifugal atomization drying device. The slurry is output from the nozzle of the centrifugal atomization drying device. As the nozzle rotates at high speed, the slurry is sprayed into mist-like mud droplets under the action of pressure and centrifugal force. At this time, the mud droplets are sprayed onto the hot flue of the hot blast furnace. The temperature of the hot flue is 550-800°C. The mud droplets are instantly dried into approximately spherical particles when in contact with the high temperature. The spherical particles are then cooled by a cooler at the bottom of the tower until the temperature drops to 40-100°C. At this time, the slurry is discharged, and the moisture content of the discharged material is reduced to 15-45%; S802. The granular material is input into the rotary drying device for further drying. The rotary drying device adopts a rotary kiln. The material is heated by the high temperature flame and rotary motion in the rotary kiln to evaporate the water. When the water content of the material drops to 5-15%, a discharging device is set to discharge the material. The discharged material will enter the next process. At the same time, some of the material will remain in the rotary kiln until it is dried to a water content of less than 0.5%, thereby obtaining a low-temperature regenerated alumina product.

9. The harmless regeneration method of aluminum ash slag according to claim 1, characterized in that: In step S9, the materials in the tunnel kiln will produce the following reactions: S901, NaAlO2+2H2O=Al(OH)3+NaOH; S902, 2Al(OH)3=Al2O3+3H2O; S903, 2NaOH = Na2O + H2O; S904, Al2O3→α-Al2O3; S905, C+O2=CO2.

10. The harmless regeneration method of aluminum ash slag according to claim 1, characterized in that: In step S11, a Raymond mill is used to grind products with particle sizes of 100-200 mesh, 200-250 mesh, 250-300 mesh, 300-500 mesh, 500-800 mesh, and 800-1200 mesh, respectively.

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