A method for the collaborative utilization of dust collected during the pyroresource utilization process of secondary aluminum ash

Abstract

The present invention discloses a method for synergistically utilizing the dust collection ash in the pyroresource utilization process of secondary aluminum ash. The dust collection ash generated in the pyroresource utilization process of secondary aluminum ash is slurried to obtain a deacidification slurry; the flue gas generated in the pyroresource utilization process of secondary aluminum ash is introduced into the deacidification slurry to remove acidic pollutants, and the flue gas is discharged up to the standard after the acidic pollutants are removed; the deacidified slurry obtained after the acidic pollutants in the flue gas are removed is subjected to a secondary reaction including calcification and oxidation and then liquid-solid separation is carried out. The obtained filter cake is dried and used as a pyroresource utilization product of secondary aluminum ash, and the obtained filtrate is subjected to evaporation crystallization and used as an aluminum refining agent for upstream aluminum smelting enterprises. The present invention efficiently utilizes the dust collection ash in the pyroresource utilization process of secondary aluminum ash as a deacidifying agent, saving resources such as traditional deacidifying agents. For production enterprises, the present invention can be directly used in existing desulfurization systems without modification.

Description

Technical Field

[0001] The present invention relates to the technical field of environmental protection production, and particularly relates to a method for synergistically utilizing the dust collected during the pyroresource utilization process of secondary aluminum ash. Background Art

[0002] With the increasingly stringent national and aluminum industry environmental protection policies, the harmless and resourceful application of secondary aluminum ash, one of the hazardous wastes in the aluminum industry, has gradually become a hot topic in the environmental protection industry. In terms of resource utilization, the pyroresource utilization accounts for more than 70% of the market, that is, secondary aluminum ash is mixed with one or several raw materials such as calcium-based, magnesium-based, and sodium-based in a certain proportion, and then products such as calcium aluminate, sodium aluminate, and magnesium aluminate spinel are prepared under high temperature (≥1100°C) conditions. During the production process, components such as sodium-based and potassium-based in the secondary aluminum ash volatilize under high temperature conditions and enter the dust collector through the high-temperature flue gas. After low-temperature condensation, they are discharged from the system together with the dust in the flue gas as collected dust. The proportion of sodium-based, potassium-based and other components in this part of the collected dust is 40-80%, and the rest is one or several of calcium aluminate, magnesium aluminate spinel, sodium aluminate, etc., and the aqueous solution is alkaline. At present, most of the collected dust in the pyroresource utilization process of secondary aluminum ash is in a stockpiled state and cannot be utilized yet. At the same time, during the pyroresource production process, the flue gas emissions contain one or several acidic pollutants such as a large amount of sulfur dioxide (SO2), hydrogen fluoride (HF), and hydrogen chloride (HCl). Currently, most of them use one or several of traditional lime (stone), sodium carbonate, sodium hydroxide, etc. as deacidifying agents, and a large amount of deacidification products formed after deacidification still cannot be disposed of.

[0003] Currently, there is no research on the synergistic utilization of the collected dust during the pyroresource utilization process of secondary aluminum ash for deacidification at home and abroad, nor are there relevant literatures or patents. Summary of the Invention

[0004] Aiming at the deficiencies of the prior art, the present invention aims to provide a method for synergistically utilizing the collected dust during the pyroresource utilization process of secondary aluminum ash

[0005] To achieve the above purpose, the present invention adopts the following technical solutions:

[0006] A method for synergistically utilizing the collected dust during the pyroresource utilization process of secondary aluminum ash, in which the collected dust generated during the pyroresource utilization process of secondary aluminum ash is slurried to obtain a deacidification slurry; the flue gas generated during the pyroresource utilization process of secondary aluminum ash is introduced into the deacidification slurry to remove acidic pollutants, and the flue gas is discharged up to standard after removing the acidic pollutants; the deacidified slurry obtained after removing the acidic pollutants from the flue gas undergoes a secondary reaction including calcification and oxidation and then is subjected to liquid-solid separation. The obtained filter cake is dried and used as a pyroresource utilization product of secondary aluminum ash, and the obtained filtrate is subjected to evaporation crystallization and drying and used as an aluminum refining agent for upstream aluminum smelting enterprises.

[0007] Further, the acidic pollutants in the flue gas include one or more of sulfur dioxide, hydrogen fluoride, and hydrogen chloride.

[0008] Further, the dosage of the dust collected in the deacidification slurry is measured according to the molar ratio of the active alkali in the dust collected to the acidic pollutants in the flue gas, which is 1.0 - 2.0.

[0009] Further, the dust collected during the pyroresource utilization process of secondary aluminum ash is used to prepare a deacidification slurry with a concentration of 15% - 25% by mass. The prepared deacidification slurry is pumped into a deacidification tower by a deacidification pump to react with the flue gas generated during the pyroresource utilization process of secondary aluminum ash to remove the acidic pollutants in the flue gas. When the pH value of the deacidified slurry in the deacidification tower drops to 5.5 - 7.5, it is discharged into a secondary reaction tank for a secondary reaction.

[0010] Further, the specific process of the secondary reaction is as follows: a calcifying agent and an oxidizing agent are added to the deacidified slurry for a calcification reaction and an oxidation reaction. Among them, the calcifying agent is one or more of calcium chloride, calcium carbonate, and calcium oxide, which is used to remove the dissolved sulfate and fluoride ions in the deacidified slurry. The dosage of the calcifying agent is measured according to the molar ratios of the effective calcium [C] in the calcifying agent to the leached sulfate [SO4] and fluoride ions [F] in the deacidified slurry, [C] / [SO4] = 1.0 - 1.2 and [C] / [F] = 1.0 - 1.2. The oxidizing agent is one or more of natural air, calcium hypochlorite, sodium hypochlorite, hydrogen peroxide, and ozone, which is used to oxidize the sulfite ions in the deacidified slurry. The dosage of the oxidizing agent is measured according to the molar ratio of the active oxygen [O] in the oxidizing agent to the sulfite ions [SO3] in the deacidified slurry, [O] / [SO3] = 1.2 - 4. The time for the secondary reaction is 20 - 60 min.

[0011] Further, after the deacidified slurry after the secondary reaction is subjected to liquid-solid separation, the heat required for drying the obtained filter cake is the waste heat of the flue gas during the pyroresource utilization process of secondary aluminum ash.

[0012] Further, after the deacidified slurry after the secondary reaction is subjected to liquid-solid separation, the obtained filtrate is subjected to evaporation crystallization at 85 - 120 °C, and then dried and mixed evenly. The obtained product is directly used as an aluminum refining agent in the aluminum smelting or the primary aluminum ash ash frying process. The heat required for drying is the waste heat of the flue gas during the pyroresource utilization process of secondary aluminum ash. The evaporation condensate water during the evaporation crystallization process is returned for preparing the deacidification slurry.

[0013] The beneficial effects of the present invention are as follows: Aiming at the technical characteristics of the pyrometallurgical resource utilization of secondary aluminum ash, the dust collected from the flue gas during the production process is used as a deacidifying agent to wet-remove pollutants such as sulfur dioxide (SO2), hydrogen chloride (HCl), and hydrogen fluoride (HF) in the flue gas. After the deacidified slurry is subjected to liquid-solid separation, the filter cake is dried and used as a product for the pyrometallurgical resource utilization of secondary aluminum ash, and the filtrate is evaporated and crystallized and then returned to the upstream aluminum smelting enterprise for use as a refining agent for aluminum. The present invention uses the dust collected during the pyrometallurgical resource utilization process as a flue gas deacidifying agent, which not only treats waste with waste but also recovers valuable components such as sodium-based components in the dust, realizing the efficient collaborative utilization of resources and 100% full-cycle utilization of resources. After the flue gas is deacidified, the emission concentrations of SO2, HCl, and HF can reach ≤35 mg / Nm 3 , ≤1 mg / Nm 3 , ≤3 mg / Nm 3 , meeting the requirements of ultra-low emissions.

[0014] Compared with the existing pyrometallurgical resource utilization technology for secondary aluminum ash, the present invention fills the gap in the existing pyrometallurgical resource utilization technology for secondary aluminum ash, solves the problem of the storage of a large amount of collected dust, and realizes 100% full-cycle utilization of resources. Compared with the traditional wet desulfurization technology, the present invention efficiently uses the dust collected during the pyrometallurgical resource utilization process of secondary aluminum ash as a deacidifying agent, saving resources such as traditional deacidifying agents. For production enterprises, the present invention can be directly used in existing desulfurization systems without modification. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a process flow chart of the methods of the embodiments of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0016] The present invention will be further described below in conjunction with the drawings. It should be noted that this embodiment is based on the present technical solution and provides detailed implementation manners and specific operation processes, but the protection scope of the present invention is not limited to this embodiment.

[0017] Example 1

[0018] This embodiment provides a method for the collaborative utilization of the dust collected during the pyrometallurgical resource utilization process of secondary aluminum ash. As Figure 1 shown, according to the molar ratio of the active alkali in the dust collected during the pyrometallurgical resource utilization process of secondary aluminum ash to the acidic pollutants in the flue gas = 1.0, the dust collected is configured into a deacidifying slurry with a mass concentration of 15%. The configured deacidifying slurry is pumped into the deacidifying tower by a deacidifying pump to react with the acidic pollutants in the flue gas to remove the acidic pollutants in the flue gas. After the flue gas is deacidified, the emission concentrations of SO2, HCl, and HF reach ≤35 mg / Nm 3 , ≤1 mg / Nm 3 , ≤3 mg / Nm 3, meeting the requirements of ultra-low emissions. When the pH of the slurry after deacidification reaches 7.5, it is discharged into the secondary reaction tank, and a calcifying agent and an oxidizing agent are added to the secondary reaction tank. The dosage of the calcifying agent (calcium oxide) is measured according to the ratio of active calcium [C] in the calcifying agent to sulfate [SO4] in the slurry after deacidification = 1.0, and the ratio of active calcium [C] in the calcifying agent to fluoride ion [F] in the slurry after deacidification = 1.2. Natural air is used as the oxidizing agent, and the dosage of the oxidizing agent is measured according to the molar ratio of active oxygen [O] in the oxidizing agent to sulfite ion [SO3] in the slurry after deacidification being 4, and the reaction time is 60 min. The slurry after deacidification after the secondary reaction is pumped into a centrifuge by a slurry pump for liquid-solid separation, and the obtained filter cake is directly sold as a product after being dried by the waste heat of the high-temperature flue gas during the secondary aluminum ash pyrometallurgical resource utilization process. The obtained filtrate is evaporated - crystallized - dried - mixed evenly at 120 °C and then sold to the upstream aluminum smelting enterprise as an aluminum refining agent in the aluminum smelting or primary aluminum ash ash roasting process.

[0019] Example 2

[0020] This example provides a method for synergistic utilization of dust collection ash in the secondary aluminum ash pyrometallurgical resource utilization process, as Figure 1 shown. According to the molar ratio of active alkali in the dust collection ash generated during the secondary aluminum ash pyrometallurgical resource utilization process to acidic pollutants in the flue gas = 1.2, the dust collection ash is configured into a deacidification slurry with a mass concentration of 25%. The prepared deacidification slurry is pumped into the deacidification tower by a deacidification pump to react with acidic pollutants in the flue gas to remove acidic pollutants in the flue gas. After the flue gas is deacidified, the emission concentrations of SO2, HCl, and HF are respectively ≤ 30 mg / Nm 3 , ≤ 1 mg / Nm 3 , ≤ 3 mg / Nm 3 , meeting the requirements of ultra-low emissions. When the pH of the slurry after deacidification reaches 5.5, it is discharged into the secondary reaction tank, and a calcifying agent (calcium carbonate) and an oxidizing agent are added to the secondary reaction tank for secondary reaction. The dosage of the calcifying agent is measured according to [C] / [SO4] = 1.2 and [C] / [F] = 1. Calcium hypochlorite is used as the oxidizing agent, and the dosage of the oxidizing agent is measured according to the molar ratio of active oxygen [O] in the oxidizing agent to sulfite ion [SO3] in the slurry after deacidification being 1.2, and the reaction time is 20 min. The slurry after deacidification after the secondary reaction is pumped into a filter press by a slurry pump for liquid-solid separation, and the filter cake is directly sold as a product after being dried by the waste heat of the high-temperature flue gas during the secondary aluminum ash pyrometallurgical resource utilization process. The filtrate is evaporated - crystallized - dried - mixed evenly under negative pressure at 85 °C and then sold to the upstream aluminum smelting enterprise as an aluminum refining agent in the aluminum smelting or primary aluminum ash ash roasting process.

[0021] For those skilled in the art, various corresponding changes and deformations can be given according to the above technical solutions and concepts, and all these changes and deformations should be included within the protection scope of the claims of the present invention.

Claims

1. A method for the collaborative utilization of dust collected during the pyrometallurgical resource utilization process of secondary aluminum ash, characterized in that, The dust collected during the pyroresource utilization process of secondary aluminum ash is slurried to obtain a deacidified slurry; the flue gas generated during the pyroresource utilization process of secondary aluminum ash is introduced into the deacidified slurry to remove acidic pollutants, and the flue gas meets the discharge standards after the acidic pollutants are removed. The deacidified slurry obtained after the removal of acidic pollutants from the flue gas undergoes a secondary reaction including calcification and oxidation and then liquid-solid separation. The obtained filter cake is dried and used as a pyroresource utilization product of secondary aluminum ash, and the obtained filtrate is evaporated, crystallized, and dried and used as a refining agent for aluminum by upstream aluminum smelting enterprises. The specific process of the secondary reaction is as follows: a calcifying agent and an oxidizing agent are added to the deacidified slurry for calcification reaction and oxidation reaction; the calcifying agent is one or more of calcium chloride, calcium carbonate, and calcium oxide, which is used to remove the dissolved sulfate and fluoride ions in the deacidified slurry. The dosage of the calcifying agent is measured according to the molar ratios of the effective calcium [C] in the calcifying agent to the leached sulfate [SO4] and fluoride ions [F] in the deacidified slurry, [C] / [SO4]=1.0-1.2 and [C] / [F]=1.0-1.2; the oxidizing agent is one or more of natural air, calcium hypochlorite, sodium hypochlorite, hydrogen peroxide, and ozone, which is used to oxidize the sulfite ions in the deacidified slurry. The dosage of the oxidizing agent is measured according to the molar ratio of the active oxygen [O] in the oxidizing agent to the sulfite ions [SO3] in the deacidified slurry, [O] / [SO3]=1.2-4; the time of the secondary reaction is 20-60 min. After the deacidified slurry after the secondary reaction undergoes liquid-solid separation, the obtained filtrate is evaporated and crystallized at 85-120 °C, then dried and mixed evenly. The obtained product is directly used as a refining agent for aluminum in the aluminum smelting or primary aluminum ash ash frying process. The heat required for drying is the waste heat of the flue gas during the pyroresource utilization process of secondary aluminum ash; the evaporation condensate during the evaporation and crystallization process is returned for preparing the deacidified slurry.

2. The method according to claim 1, characterized in that, The acidic pollutants in the flue gas include one or more of sulfur dioxide, hydrogen fluoride, and hydrogen chloride.

3. The method according to claim 1, characterized in that, The dosage of the dust collected during the pyroresource utilization process of secondary aluminum ash in the deacidified slurry is measured according to the molar ratio of the active alkali in the dust collected to the acidic pollutants in the flue gas, which is 1.0-2.

0.

4. The method according to claim 1, characterized in that, The dust collected during the pyroresource utilization process of secondary aluminum ash is configured into a deacidified slurry at a concentration of 15%-25% by mass. The configured deacidified slurry is pumped into the deacidification tower by a deacidification pump to react with the flue gas generated during the pyroresource utilization process of secondary aluminum ash to remove the acidic pollutants in the flue gas; when the pH value of the deacidified slurry in the deacidification tower drops to 5.5-7.5, it is discharged into the secondary reaction tank for secondary reaction.

5. The method according to claim 1, characterized in that, After the deacidified slurry after the secondary reaction undergoes liquid-solid separation, the heat required for drying the obtained filter cake is the waste heat of the flue gas during the pyroresource utilization process of secondary aluminum ash.

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