阅读说明：本技术 一种二次铝灰无害化处置工艺 (Harmless treatment process for secondary aluminum ash ) 是由 任玉宝 刘昌明 王帅 冯静阳 张新岩 张弟 于 2020-07-23 设计创作，主要内容包括：本发明属于有色冶金环保技术领域,涉及一种二次铝灰无害化处置工艺,包括以下步骤：破碎筛分、催化脱氨、氢氧化铝转化、氧化铝回收、催化剂回收以及熔铝精炼剂回收,该二次铝灰无害化处置工艺,能够实现二次铝灰的无害化处理,并且能够高效的回收二次铝灰中的有用成分,铝灰的水解相对彻底,铝灰中氮化铝的分解率高,使用的催化剂无毒且回收比较方便,即使有少量存留,也可将其转变成氯化钠或氯化钾,最后变成精炼剂,不会引入新杂质。(The invention belongs to the technical field of nonferrous metallurgy environmental protection, and relates to a secondary aluminum ash harmless treatment process, which comprises the following steps: crushing and screening, catalytic deamination, aluminium hydroxide conversion, alumina recovery, catalyst recovery and molten aluminum refining agent recovery, this secondary aluminium ash innocent treatment technology can realize the innocent treatment of secondary aluminium ash, and can the useful component in the efficient recovery secondary aluminium ash, the hydrolysis of aluminium ash is relatively thorough, the decomposition rate of aluminium nitride in the aluminium ash is high, the catalyst that uses is nontoxic and retrieve more conveniently, even there is a small amount of persistence, also can change it into sodium chloride or potassium chloride, become the refining agent at last, can not introduce new impurity.)

1. The secondary aluminum ash harmless treatment process is characterized by comprising the following steps:

A. crushing and screening: grinding and screening the secondary aluminum ash by using a crusher, wherein the crushing particle size is controlled to be 100-200 meshes;

B. catalytic deamination: b, adding solvent water into the secondary aluminum ash crushed in the step A to perform catalytic deamination reaction, and absorbing ammonia gas generated by decomposing aluminum nitride by using dilute sulfuric acid through an absorption tower to prepare an ammonium sulfate solution;

C. aluminum hydroxide conversion: c, introducing carbon dioxide gas into the aluminum ash slurry subjected to catalytic deamination in the step B, completely converting aluminate in the slurry into aluminum hydroxide, and performing solid-liquid separation, wherein the pH of the aluminum ash slurry is 9-10 after the carbon dioxide is introduced;

D. and (3) recovering aluminum oxide: calcining the ash slag subjected to solid-liquid separation in the step C to convert the ash slag into aluminum oxide, wherein the calcining temperature is 900-1000 ℃, and the calcining time is 0.5-3 h;

E. catalyst recovery: c, evaporating and concentrating the upper-layer filtrate obtained after the solid-liquid separation in the step C, controlling the specific gravity of the upper-layer filtrate after evaporation and concentration to be 1.20-1.26, and precipitating catalyst crystals after condensation and centrifugation;

F. recovering molten aluminum refining agent: and E, adjusting the filtrate generated in the evaporation concentration process in the step E to be neutral by using a small amount of hydrochloric acid, and evaporating the solution to obtain mixed salt which is used as a molten aluminum refining agent for secondary use.

2. The secondary aluminum ash harmless disposal process according to claim 1, wherein ammonium sulfate solid is obtained after the ammonium sulfate solution is concentrated and crystallized in the step B.

3. The secondary aluminum ash harmless treatment process as claimed in claim 2, wherein the mass ratio of the solvent water to the secondary aluminum ash in the step B is 3-10, the mass ratio of the secondary aluminum ash to the catalyst is 0.2-20, the catalytic deamination reaction time is 4-36 h, and the reaction temperature is 40-120 ℃.

4. The secondary aluminum ash harmless treatment process as claimed in claim 3, wherein the catalyst added in the catalytic deamination process of step B is one or more of sodium carbonate, potassium carbonate, sodium hydroxide and potassium hydroxide.

5. The secondary aluminum ash harmless disposal process according to claim 1, wherein in the step E, the upper layer filtrate is concentrated by heating evaporation or concentration by a filter membrane.

6. The secondary aluminum ash harmless disposal process of claim 1, wherein the supernatant liquid produced by solid-liquid separation after the conversion of aluminum hydroxide in the step C, the supernatant liquid produced by evaporation and concentration of the supernatant liquid in the step E and the supernatant liquid produced by crystallization of the catalyst in the step E are collected into a circulating water tank for mixing the secondary aluminum ash with the solvent water in the step B.

7. The secondary aluminum ash harmless disposal process of claim 1, wherein the main components of the mixed salt in the step F are potassium chloride, sodium chloride and fluoride.

Technical Field

The invention belongs to the technical field of nonferrous metallurgy environmental protection, and relates to a secondary aluminum ash harmless treatment process.

Background

The secondary aluminum ash is solid matter containing metallic aluminum and other components generated in the processes of production, use, recovery and the like of electrolytic aluminum, cast aluminum or other aluminum industries. The aluminum ash harmless treatment method is characterized in that the aluminum ash harmless treatment engineering is significant because the aluminum ash harmless treatment method generally comprises the following components of metal aluminum, aluminum oxide, aluminum nitride, silicon dioxide, magnesium oxide, potassium chloride, sodium chloride, a small amount of fluoride and cyanide, and the like, the aluminum nitride can be hydrolyzed to generate ammonia gas after meeting water, the fluoride and the cyanide can pollute water sources after being dissolved in the water, and the fluoride and the cyanide are defined as dangerous wastes according to national environmental protection and government regulations.

At present, there are many domestic patent technologies on the comprehensive utilization of aluminum ash, and after the technologies are classified, the typical technologies are as follows:

the invention patent with publication number CN109678180A discloses a method for comprehensively recycling mixed secondary aluminum ash, which comprises the steps of firstly carrying out catalytic deamination on the aluminum ash, and then carrying out solid-liquid separation to obtain filtrate and solid materials. The solid material is calcined and then converted into alumina, and the filtrate is evaporated for a plurality of times to respectively obtain sodium fluoride, potassium fluoride, sodium chloride and potassium chloride. The process has the following problems: the fluoride is selected as a catalyst to be introduced into hazardous waste substances, the solubility of the two fluorides is less influenced by temperature, the fluoride separation is realized by evaporation, the recovery efficiency is low, the content of the fluoride in a NaCl and KCl mixture obtained by secondary evaporation is easy to exceed the standard, and the possibility of becoming secondary hazardous waste exists.

The invention patent with publication number CN110482503A discloses a method for comprehensive utilization of secondary aluminum ash resources, which is a method for preparing aluminum nitride by using secondary aluminum ash as a raw material. Although the process is simple, the process is basically high in temperature and pressure, and the industrialization difficulty is large. And because the aluminum ash has complex components, non-reactive or non-volatile substances can enter the product aluminum nitride in the high-temperature desalting process.

The invention patent with publication number CN107555447A discloses a method for harmless comprehensive utilization of secondary aluminum ash, namely a method for preparing calcium aluminate by taking the secondary aluminum ash as a raw material, firstly adding water into the secondary aluminum ash to prepare slurry, stirring to deaminate, and evaporating and crystallizing a liquid phase after solid-liquid separation to obtain a mixture of chloride and fluoride; the separated solid phase is used to produce a calcium aluminate material. The process has the following problems: the hydrolysis of the aluminum ash is reversible and the reaction rate is low, and the hydrolysis catalyst is not developed in the process, so that the aluminum nitride in the calcium aluminate material possibly exceeds the standard.

The invention patent with publication number CN105347361A discloses a comprehensive utilization and treatment method of aluminum ash, which comprises the steps of carrying out catalytic deamination on the aluminum ash, mixing and forming after alkali is added to obtain dispersed particles, drying and sintering at high temperature, and finally dissolving out the particles in water to obtain sodium aluminate solution and solid slag. The process has the following problems: the process is complicated, after the aluminum ash is hydrolyzed, the solid part is mixed with alkali for molding and then dissolved in water to extract aluminum hydroxide, and the product of the calcination is aluminum oxide. The steps are eliminated, and the direct calcined product is alumina. And the filtrate treatment scheme is unreasonable, and secondary hazardous waste is easy to occur.

Disclosure of Invention

In view of the above, the invention provides a harmless treatment process for secondary aluminum ash, which aims to solve the problems of low resource utilization degree, high pollution, easy occurrence of secondary hazardous waste and low recovery efficiency of the secondary aluminum ash.

In order to achieve the purpose, the invention provides a secondary aluminum ash harmless treatment process, which comprises the following steps:

A. crushing and screening: grinding and screening the secondary aluminum ash by using a crusher, wherein the crushing particle size is controlled to be 100-200 meshes;

B. catalytic deamination: b, adding solvent water into the secondary aluminum ash crushed in the step A to perform catalytic deamination reaction, and absorbing ammonia gas generated by decomposing aluminum nitride by using dilute sulfuric acid through an absorption tower to prepare an ammonium sulfate solution;

C. aluminum hydroxide conversion: c, introducing carbon dioxide gas into the aluminum ash slurry subjected to catalytic deamination in the step B, completely converting aluminate in the slurry into aluminum hydroxide, and performing solid-liquid separation, wherein the pH of the aluminum ash slurry is 9-10 after the carbon dioxide is introduced;

D. and (3) recovering aluminum oxide: calcining the ash slag subjected to solid-liquid separation in the step C to convert the ash slag into aluminum oxide, wherein the calcining temperature is 900-1000 ℃, and the calcining time is 0.5-3 h;

E. catalyst recovery: c, evaporating and concentrating the upper-layer filtrate obtained after the solid-liquid separation in the step C, controlling the specific gravity of the upper-layer filtrate after evaporation and concentration to be 1.20-1.26, and precipitating catalyst crystals after condensation and centrifugation;

F. recovering molten aluminum refining agent: and E, adjusting the filtrate generated in the evaporation concentration process in the step E to be neutral by using a small amount of hydrochloric acid, and evaporating the solution to obtain mixed salt which is used as a molten aluminum refining agent for secondary use.

And further, concentrating and crystallizing the ammonium sulfate solution in the step B to obtain an ammonium sulfate solid.

Further, in the step B, the mass ratio of the solvent water to the secondary aluminum ash is 3-10, the mass ratio of the secondary aluminum ash to the catalyst is 0.2-20, the catalytic deamination reaction time is 4-36 h, and the reaction temperature is 40-120 ℃.

Further, the catalyst added in the catalytic deamination process in the step B is one or more of sodium carbonate, potassium carbonate, sodium hydroxide and potassium hydroxide.

Further, in the step E, the upper-layer filtrate evaporation and concentration mode includes heating evaporation and concentration or filtration membrane concentration.

And further, collecting the supernatant generated by solid-liquid separation after the aluminum hydroxide is converted in the step C, the supernatant generated by evaporation and concentration of the supernatant filtrate in the step E and the supernatant generated by crystallization of the catalyst in the step E into a circulating water tank for mixing the secondary aluminum ash and the solvent water in the step B.

Further, the main components of the mixed salt in the step F are potassium chloride, sodium chloride and fluoride.

The invention has the beneficial effects that:

1. the harmless treatment process of the secondary aluminum ash disclosed by the invention can realize the harmless treatment of the secondary aluminum ash, and can efficiently recover useful components in the secondary aluminum ash, the hydrolysis of the aluminum ash is relatively thorough, the decomposition rate of aluminum nitride in the aluminum ash is high, the used catalyst is non-toxic and is convenient to recover, and even if a small amount of the catalyst is left, the catalyst can be converted into sodium chloride or potassium chloride and finally into a refining agent, so that new impurities cannot be introduced.

2. The harmless treatment process of the secondary aluminum ash disclosed by the invention has the advantages that the product after the secondary aluminum ash is separated has practical application, the ammonium sulfate can be used as a fertilizer for external sale, the aluminum oxide can be used as an electrolytic aluminum raw material again, and the refining agent is remained in an aluminum plant to be used as an aluminum melting refining agent repeatedly, so that the harmless circulation in the aluminum plant is realized.

3. The harmless treatment process of the secondary aluminum ash disclosed by the invention has the advantages of simple steps, no need of harsh conditions such as high temperature and high pressure, easiness in industrial implementation, environmental friendliness, no pollution and wide applicability.

Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objectives and other advantages of the invention may be realized and attained by the means of the instrumentalities and combinations particularly pointed out hereinafter.

Drawings

For the purposes of promoting a better understanding of the objects, aspects and advantages of the invention, reference will now be made to the following detailed description taken in conjunction with the accompanying drawings in which:

FIG. 1 is a process flow diagram of the harmless treatment process of secondary aluminum ash.

Detailed Description

The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention.