CN116287759A

CN116287759A - Treatment method of arsenic-containing smoke dust in copper smelting

Info

Publication number: CN116287759A
Application number: CN202310422975.2A
Authority: CN
Inventors: 张旭; 李清湘; 段志勇; 崔鹏; 张云彭; 乔涛
Original assignee: Shenzhen Xinnengtong Environmental Technology Co ltd; Kunming Hanchuang Technology Co ltd
Current assignee: Shenzhen Xinnengtong Environmental Technology Co ltd; Kunming Hanchuang Technology Co ltd
Priority date: 2023-04-19
Filing date: 2023-04-19
Publication date: 2023-06-23

Abstract

The invention relates to a treatment method of arsenic-containing smoke dust in copper smelting. And leaching the arsenic-containing smoke dust in copper smelting by adopting sulfuric acid aqueous solution to obtain lead bismuth slag. Copper and arsenic in the leaching solution are separated by adopting arsenic sulfide slag, copper sulfide slag with low arsenic is obtained, a copper-precipitating solution is cooled to obtain arsenic trioxide crystals with higher purity, the crystallized solution is returned to a copper smelting arsenic-containing smoke leaching system for recycling, zinc is circularly enriched in the process to obtain a high-concentration zinc sulfate solution, the zinc can be recovered by adopting a traditional zinc recovery method, no waste liquid and waste gas are discharged in the whole process, a large amount of arsenic sulfide slag can be treated simultaneously while the complete separation of valuable elements in the copper smelting arsenic-containing smoke is realized, and the economic benefit of the treatment of the copper smelting arsenic-containing smoke is greatly improved.

Description

Treatment method of arsenic-containing smoke dust in copper smelting

Technical Field

The invention relates to the field of nonferrous metal metallurgy, mainly relates to a treatment method of arsenic-containing smoke dust in copper smelting, in particular to a method for separating arsenic from high-arsenic smoke dust produced in copper smelting and recovering valuable metals, and aims at overcoming the defects of the existing wet treatment high-arsenic smoke dust treatment technology.

Background

The exploration reserve of the global arsenic mine resource is 70% concentrated in China. About 70% of arsenic is collected from the tailings of ore dressing, and only about 20% of the arsenic enters a smelting plant. According to incomplete statistics, the total amount of arsenic entering the smelting plant with concentrate is more than 8 ten thousand tons each year, but the recovered arsenic accounts for only about 10% of the total arsenic entering the plant. Copper pyrometallurgy is more in variety and can be classified into floating smelting (flash smelting, flash blowing) and molten pool smelting (bottom blowing or side blowing smelting) according to smelting types, because associated arsenic in copper ores is easy to volatilize in the smelting process, a large amount of arsenic-containing smoke dust is generated in the pyrometallurgy copper smelting process, smoke dust generated in the copper matte blowing process is called white smoke dust, smoke dust generated in the Issate furnace or Australian furnace smelting is called Issate furnace smoke dust or Australian furnace smoke dust, the smoke dust has high arsenic content, complex components and large component variation, and the smoke dust has a common point of containing a large amount of Cu, pb, zn, bi valuable metals and is a main solid byproduct generated in the copper smelting process. If the smoke dust returns to the smelting system, the furnace condition is deteriorated due to the circulation accumulation of impurity elements such as arsenic in the smelting system, and the smoke dust must be subjected to open-circuit treatment, but the economic benefit is poor due to the imperfect treatment process of a part of copper smelting enterprises, and the other part of copper smelting enterprises sell the smoke dust to professional treatment factories with relevant qualification in a public bidding mode.

The arsenic sulfide slag is an arsenic sulfide produced by the waste acid generated by washing the arsenic acid making flue gas through the sulfuration precipitation, and is also a dangerous waste containing arsenic. The two kinds of arsenic-containing hazardous wastes are produced by a pyrometallurgical smelting system of a copper smelting plant and are mainly sent to a professional hazardous waste treatment plant for centralized treatment, and as the national environmental protection policy becomes stricter, the hazardous waste transfer requirements are gradually increased, and the on-site treatment is urgent.

The arsenic-containing smoke dust and the arsenic sulfide slag in copper smelting are generally treated by adopting a pyrogenic process or a wet process technology. The pyrogenic process treatment technology utilizes the volatile property of arsenic trioxide to volatilize arsenic and separate heavy metals at high temperature, and has the advantages of simple flow and large treatment capacity, but the dust collection system of the flue gas has higher requirement, and secondary environmental pollution is easy to cause due to leakage of the flue gas containing arsenic in the production process, and the flue gas is harmful to the body of operators. The wet treatment process mainly adopts an acid leaching method and a water leaching method, has a good operation environment, is a main stream direction of development in the future, and is still required to be perfected. The documents [1, 5] summarize the existing copper smelting white smoke dust process and indicate the defects of the existing treatment process.

The existing treatment method has the defects of lower copper and arsenic leaching rate, incomplete copper and arsenic separation and the like because arsenic is produced into arsenic-containing slag hazardous waste in the wet treatment process. In order to solve the problem of low copper and arsenic leaching rate under normal pressure, some researches propose to use a high-pressure leaching process [2], and although the high-pressure leaching can obtain higher arsenic leaching rate, equipment and operation are complex, and the treatment cost is high.

The leaching solution obtained by wet treatment contains a large amount of valuable elements such as arsenic, copper, zinc and the like, most of the arsenic exists in the form of pentavalent arsenic, in order to separate the elements, the prior art [3-6] usually adopts iron powder to replace copper or an electrowinning method to deposit copper, the copper separation effect is good, the pentavalent arsenic in the solution is reduced into trivalent arsenic by adopting a sulfur dioxide reduction method, the trivalent arsenic has lower solubility, part of the arsenic is separated from the solution and can be produced in the form of arsenic trioxide crystal, but the method has the problem of large acid output, for the liquid after crystallization, ferrous iron is oxidized into trivalent iron by adopting an oxidant, then lime is added to deposit arsenic to obtain iron-arsenic slag containing a large amount of calcium sulfate, and the liquid after arsenic removal, after the arsenic removal, zinc sulfate products are produced by concentrating and cooling crystallization, and the crystallization mother liquor returns to leaching. Obviously, the methods have long flow, high energy consumption and poor economic benefit, and the waste of the arsenic-iron slag which is difficult to treat is produced.

In order to solve the defects of the leaching solution treatment process, some patents propose a method for precipitating copper by adopting arsenic sulfide slag as a copper precipitating agent, and the arsenic sulfide slag is arsenic sulfide produced by adopting sulfuration precipitation of waste acid generated by washing arsenic-containing acid making flue gas, and is also a dangerous waste containing arsenic, so that obviously, the idea has good development prospect.

Japanese patent Sho 59-128216 discloses a method for treating arsenic sulfide slag with a copper sulfate solution, which comprises the following steps:

As ₂ S ₃ +3CuSO ₄ +4H ₂ O＝3CuS+2HAsO ₂ +3H ₂ SO ₄

the concentration of trivalent arsenic in the leached liquid is increased by adopting a concentration method, so that arsenic trioxide is separated out, and arsenic trioxide crystals are obtained through filtration.

The advantage of this method is that purer arsenic and copper sulphide slag with low arsenic can be obtained, but there is the problem of producing a large amount of acid, which patent does not take into account the problem of solution circulation.

In order to solve the problem of acid regenerated copper sulfate produced, in 1989, china river copper group introduced technology for treating arsenic sulfide slag by Japanese Sumitomo similar copper sulfate substitution method [2 ]]The technology comprises 4 procedures of replacement, oxidation, reduction crystallization, preparation of copper sulfate and the like, firstly copper powder is oxidized to generate sulfuric acid, copper sulfate replaces arsenic in arsenic sulfide slag to generate arsenite, air is blown into the arsenite under the condition of normal pressure and temperature rise to oxidize the arsenite to generate pentavalent arsenic acid, and the pentavalent arsenic acid is reduced, cooled and crystallized to produce As ₂ O ₃ The process utilizes the property of higher solubility of pentavalent arsenic acid, so that arsenic in the solution mainly exists in pentavalent arsenic form, the problem of concentration of the solution is avoided, and the main reaction formula is as follows:

As ₂ S ₃ +3CuSO ₄ +4H ₂ O＝2HAsO ₂ +3CuS+3H ₂ SO ₄

2HAsO ₂ +O ₂ +2H ₂ O＝2H ₃ AsO ₄

H ₃ AsO ₄ +SO ₂ ＝HAsO ₂ +H ₂ SO ₄

from the above reaction, 1mol of arsenic sulfide needs to be produced into 5mol of sulfuric acid to be neutralized, in order to avoid the problem of low solubility of arsenite, the method adopts trivalent arsenic acid solution to oxidize pentavalent arsenic acid, and then the pentavalent arsenic acid is reduced into trivalent arsenic acid with low solubility by sulfur dioxide, so that arsenic trioxide crystals are obtained. This results in a long and costly process for treating arsenic sulphide slag using this method, but this method has so far been the most successful method used industrially.

Whereas, japanese patent Sho 59-88320 discloses a method for producing arsenic trioxide by reducing pentavalent arsenic with arsenic sulfide, which comprises the following steps:

3H ₃ AsO ₄ +As ₂ S ₃ ＝5HAsO ₂ +3S+2H ₂ O

3H ₃ AsO ₄ +As ₂ S ₅ ＝5HAsO ₂ +5S+2H ₂ O

the method avoids the problem that a great amount of acid is generated by reducing the pentavalent arsenic, but has the problem that the post-liquid needs to be concentrated, and has higher energy consumption, and in addition, the patent also has the problem that the reaction of the arsenic sulfide and the pentavalent arsenic is not thorough. The elemental sulphur residue obtained from the low acid conditions of example 1 contained 9.6% arsenic and the elemental sulphur residue contained 17.2% arsenic at high acid (100 g/L), and concentration was also required to crystallize arsenic trioxide due to the low concentration of arsenic in the leached liquid.

Based on the above two Japanese patents and the introduced Sumitomo [2], many researchers have improved.

Chinese patent CN108249480a proposes a comprehensive recovery method of arsenic sulfide slag and arsenic from smoke leachate in copper smelting, which is characterized in that the smoke leachate and the arsenic sulfide slag are subjected to normal pressure copper sulfide precipitation to obtain solid copper sulfide slag and copper precipitation post-liquid; and introducing sulfur dioxide into the copper-precipitating solution to reduce pentavalent arsenic, concentrating, crystallizing and filtering the reduced solution to obtain sulfate mixed crystals and concentrated solution. And (3) dissolving the copper sulfate and the zinc sulfate in the mixed crystal in water, and filtering to obtain arsenic oxide and copper sulfate and zinc sulfate solutions. In the disclosure of the patent, it is not clearly pointed out what kind of leaching solution is the leaching solution, the existing technology and patent use dilute sulfuric acid aqueous solution or water to leach white smoke dust, but can be judged from the final products of copper sulfate and zinc sulfate, the leaching solution is sulfuric acid or water leaching solution, although this patent proposes a method for precipitating copper under normal pressure by adopting arsenic sulfide slag, but can be seen from claim 1, the leaching solution and the arsenic sulfide slag are subjected to normal pressure copper sulfide precipitation treatment at the temperature of 50-80 ℃ for 3-8 h, and the copper sulfide slag obtained by adopting normal pressure arsenic sulfide slag copper precipitation contains arsenic more than 7%, copper in the copper precipitation solution is about 10g/L, which indicates incomplete copper precipitation. Copper sulphide slag contains only 40-50% copper, and for pentavalent arsenic in solution, this patent uses a conventional sulphur dioxide reduction process, which will necessarily lead to the production of large amounts of acid, and this highly acidic solution containing arsenic, zinc and copper does not provide a solution in its patent. In addition, the method of concentrating all copper-precipitating liquid inevitably results in higher energy consumption, and the patent finally only obtains the mixed solution of copper sulfate and zinc sulfate and impure arsenic trioxide, and does not realize better separation of copper, zinc and arsenic.

In order to solve the problem that copper is not completely precipitated by adopting arsenic sulfide slag under normal pressure, chinese patent CN110983059B discloses a method for recovering copper and arsenic from white smoke leaching liquid and arsenic filter cake of copper smelting, which comprises the steps of pressure copper precipitation, cooling filtration, cooling crystallization, arsenic trioxide refining and the like. The method is to add arsenic filter cake into high pressure reactor under the protection of nitrogen or inert gas to deposit copper under pressure. The method for calculating the theoretical amount is not mentioned in the claims and the description, but the method for calculating the theoretical amount is not described in the claims, the method for calculating the theoretical amount is implemented by adding the arsenic filter cake according to the condition of 0.7 times of the theoretical amount in embodiment 1 according to the copper and arsenic components of the white smoke leaching solution and the arsenic filter cake, and the pulping is implemented by controlling the dosage of the arsenic filter cake to be 0.4-1.0 times of the theoretical amount.

We calculate for example 1 thereof that the amount of arsenic in the arsenic sulfide slag actually added is 0.1mol, and the copper deposition adopts the arsenic sulfide slag, and the reaction is as follows:

As ₂ S ₃ +3CuSO ₄ +4H ₂ O＝2HAsO ₂ +3CuS+3H ₂ SO ₄

according to this reaction, the molar ratio of arsenic to copper is 2/3, the leachate in example 1 precipitates copper, the theoretical amount of arsenic in arsenic sulfide to be added is 0.146mol, the actual molar ratio of arsenic to copper to be added is 0.1/0.146=0.7, and the same result is obtained by calculation in examples 2 and 3, which shows that the addition amount of arsenic sulfide slag is calculated according to copper precipitation, and reduction of pentavalent arsenic in solution is not considered. Although the reactions of pentavalent arsenic and arsenic sulfide slag are listed in the claims and specification thereof:

As ₂ S ₃ +3H ₃ AsO ₄ ＝5HAsO ₂ +3S+2H ₂ O

The reduction of pentavalent arsenic is not considered from the claims and examples of the addition of arsenic sulphide slag. Therefore, according to the attached drawing in the specification, the crystallized liquid returns to white smoke dust leaching, and the concentration of pentavalent arsenic is inevitably increased in the returning process.

For zinc recovery, most of the wet treatment processes are used for producing zinc sulfate products to recover zinc, and due to the fact that the zinc content in raw materials is low, a large amount of solution is required to be purified for removing arsenic and then concentrated for crystallization, and crystallization mother liquor returns to leaching, so that energy consumption is high.

For the treatment of arsenic sulphide slag, most plants use the roasting method [2]]Oxidizing and roasting arsenic sulfide to obtain As ₂ O ₃ Directly volatilize the human smoke, and recycle the smoke through condensation, and the reaction is as follows:

2As ₂ S ₃ +3O ₂ ＝2As ₂ O ₃ +6SO ₂

the method has the advantages of simple process equipment, low arsenic recovery rate, easy environmental pollution, poor product quality, and capability of generating a large amount of low-concentration sulfur dioxide flue gas to be treated, belongs to an obsolete process, and is gradually treated by a wet process.

Document [2] after the common treatment technology of arsenic sulfide slag is summarized, a pressurized acid leaching method of the arsenic sulfide slag is proposed, the method is that in sulfuric acid aqueous solution, high-pressure oxygen leaching is adopted, sulfur generates element sulfur, copper-arsenic sulfide is leached out and enters into solution, arsenic in the solution is pentavalent arsenic, then sulfur dioxide flue gas is adopted to reduce pentavalent arsenic into trivalent arsenic for crystallization, copper is concentrated and crystallized to obtain copper sulfate products after extraction and dearsenization, the process has high concentrating energy consumption, and in addition, the use and maintenance cost of high-pressure leaching equipment is high. Compared with the Sumitomo method, the method avoids the problem of a large amount of sulfuric acid produced by the copper sulfate displacement method, but still has the problem that the sulfur dioxide reduces pentavalent arsenic to produce acid, and the method needs to produce copper sulfate by evaporation and concentration.

Chinese patent CN 110028101a discloses a method for preparing arsenic trioxide by using arsenic sulfide slag, which comprises the following main steps: adding hydrogen peroxide into the aqueous solution under normal pressure to directly oxidize arsenic sulfide slag, filtering and collecting filtrate to obtain pentavalent arsenic acid solution; leaching arsenic sulfide slag by using the pentavalent arsenic acid solution, filtering and collecting filtrate; evaporating, concentrating, cooling and crystallizing to obtain arsenic trioxide. The method of the invention firstly uses hydrogen peroxide to oxidize arsenic sulfide slag to obtain pentavalent arsenic aqueous solution, and then uses the product to leach the arsenic sulfide slag, and the purity of the obtained arsenic trioxide is higher than 99 percent, and obviously, the method uses the pentavalent arsenic leaching method.

When the arsenic sulfide slag is oxidized by hydrogen peroxide to prepare the pentavalent arsenic acid solution, the reaction equation is as follows:

As ₂ S ₃ +5H ₂ O ₂ ＝2H ₃ AsO ₄ +2H ₂ O+3S

As ₂ S ₃ +3H ₃ AsO ₄ ＝5HAsO ₂ +3S+2H ₂ O

from the reaction formula, the molar ratio of the arsenic sulfide slag to the hydrogen peroxide is 1:5, but in the preferred range of 1:15.5-18.2 as set forth in claim 2, it is evident that the hydrogen peroxide consumption is much greater than the theoretical value. In the process, evaporation and concentration are needed, so that the energy consumption is high, and the consumption of hydrogen peroxide is high, so that the treatment cost of the method is high.

Technically, the above-mentioned prior art can obtain a better arsenic-sulfur separation effect by treating the arsenic sulfide slag, but there is a problem that the separate treatment of the arsenic sulfide slag has limited use of arsenic except a small amount of sulfur from the viewpoint of raw material components, so that it is difficult to realize profitability economically, which is also an important cause that the separate treatment process of the arsenic sulfide slag is difficult to be industrially applied.

In summary, the presently disclosed methods for treating arsenic-containing dust and arsenic sulfide slag in copper smelting have some disadvantages, which are mainly reflected in three aspects: 1. the leaching rate of copper sulfide and arsenic in the arsenic-containing smoke dust is low. 2. The solution treatment cost is high, and the separation is incomplete or the equipment is complex. 3. A large amount of arsenic-containing hazardous waste is produced, the requirement of zero emission of metallurgical enterprises cannot be met, the treatment cost of 4-arsenic sulfide slag is high, and the economic benefit is poor. The method is urgently needed, and a certain amount of arsenic sulfide slag is additionally treated while the high-arsenic smoke dust of copper smelting is treated, so that arsenic and valuable elements are thoroughly separated, the treatment cost is low, no waste liquid or waste gas is discharged, and the economic benefit of the treatment of the high-arsenic smoke dust of copper smelting is improved.

Citation document

1. Jiang Qingyuan, et al, copper converting white dust treatment and application, hunan nonferrous metal, volume 35, phase 4, 2019.

2. Jiang Kaixi, and the like, and the arsenic sulfide slag comprehensive utilization technology in the copper smelting process is 2014, stage 5 of nonferrous metal science and engineering.

3. Liu Fei, research on white smoke and dust pressure leaching technology of copper converters, nonferrous metals (smelting part), 2018, 4 th period.

4. Li Tao wet treatment process and practice of high-arsenic white smoke dust, chinese nonferrous metallurgy, stage 5 of 2015

5. Liu Zhiming the comprehensive recovery process of copper smelting smoke dust is shallow and proposed, and China nonferrous metallurgy is in the 5 th stage of 2015.

6. Jiao Xiaojie and the like, and the comprehensive recovery process of copper smelting smoke dust is shallow and recommended, chinese metal is notified, and the 10 th stage of 2022 is proposed.

Disclosure of Invention

According to the patent and research literature and the current production situation, aiming at the defects of the treatment technology of the arsenic-containing smoke dust and the arsenic sulfide slag in copper smelting, the invention aims at:

aiming at the defects of the existing treatment technology of the arsenic-containing smoke dust and the arsenic sulfide slag in copper smelting, the invention aims to provide the treatment method which has thorough process separation and low cost and can simultaneously consider the arsenic-containing smoke dust and the arsenic sulfide slag in copper smelting. The method provided by the invention can thoroughly separate copper, lead bismuth and arsenic in the arsenic-containing smoke dust and arsenic sulfide slag of copper smelting, lead bismuth can obtain lead bismuth slag with low arsenic content and higher lead grade, and can be used as a high-quality raw material for lead smelting enterprises; the high-quality copper sulfide slag with higher copper content and lower arsenic content is obtained and can be used as a high-quality raw material for copper smelting; arsenic is arsenic trioxide with higher content, and can be used as a raw material of arsenic products; the zinc and cadmium are enriched in the treatment process, the zinc and cadmium can be recovered by adopting the prior art, no waste liquid or waste gas is generated in the process, and the whole process is carried out under normal pressure.

To achieve the object of the invention, which is consistent with the claims, the invention is composed of the following steps:

the treatment method of the arsenic-containing smoke dust in copper smelting improves the known wet treatment flow of the sulfuric acid aqueous solution of the arsenic-containing smoke dust in copper smelting, and is characterized by comprising the following steps:

a) The method comprises the steps of leaching arsenic-containing smoke dust in copper smelting by taking an arsenic-containing sulfuric acid aqueous solution as a leaching solution at a certain temperature for a certain time through stirring reaction, obtaining leaching residues and leached liquid after partial copper, arsenic and zinc removal after solid-liquid separation, and sending the leaching residues into a lead smelting system to serve as raw materials;

b) Adding a proper amount of arsenic sulfide slag into the leached liquid obtained in the step a) to carry out copper precipitation reduction, precipitating copper and reducing pentavalent arsenic in the leached liquid, carrying out stirring reaction for a certain time at a certain temperature, and carrying out hot filtration to obtain copper precipitation slag and hot copper precipitation liquid, wherein the obtained copper precipitation slag can be directly fed into a copper smelting system to be used as a raw material, and can also be transferred into the subsequent step c)

Processing;

c) A certain amount of copper slag produced in the step b) is subjected to washing and dearsenification by adopting a certain volume of the part of leached liquid in the step a) and stirring and reacting for a certain time at a certain temperature to obtain washing copper slag and washing liquid, wherein the washing copper slag is low-arsenic copper slag, and the washing liquid is singly or/and after being mixed with the leached liquid, preferably after being mixed with the leached liquid, the washing liquid returns to the step b) for copper precipitation reduction;

d) Indirectly cooling the hot copper-precipitating solution obtained in the step b), cooling to a certain temperature under stirring, performing solid-liquid separation to obtain arsenic trioxide crystals and crystallized solution, adding sulfuric acid and water into the crystallized solution to adjust acidity, regenerating to obtain the leaching solution obtained in the step a), recycling the leaching solution to the leaching process of the step a), enriching zinc and cadmium in the solution, repeating the steps a-d), and after multiple rounds/cycles, obtaining an acidic arsenic-containing zinc sulfate solution with higher zinc concentration, and conveying the acidic arsenic-containing zinc sulfate solution into a zinc recovery system to treat and recover zinc by adopting a known technology;

the concentration of the arsenic-containing sulfuric acid aqueous solution in the step a) is that the liquid-solid ratio and the sulfuric acid concentration of the leaching solution are adjusted according to different smoke dust acid consumption, the concentration of the leached liquid sulfuric acid is controlled to be not lower than 50g/L, the temperature is 75-95 ℃, and the leaching time is 30-90 minutes.

Adding a proper amount of copper in the arsenic sulfide slag precipitation solution and pentavalent arsenic in the reduction solution into the leached liquid in the step a), wherein the added arsenic sulfide slag amount is 1.05-1.2 times of the theoretical amount of copper precipitation and pentavalent arsenic reduction in the solution, the reaction temperature is 75-95 ℃, the reaction time is 30-90 minutes, the pentavalent arsenic concentration in the copper precipitation solution is less than 1g/L, the copper concentration is less than 1g/L, the theoretical amount of arsenic sulfide slag addition is the mole number of arsenic added into the arsenic sulfide slag calculated according to two thirds of the sum of the mole numbers of copper and pentavalent arsenic in the solution, and the added arsenic sulfide slag is converted into the added arsenic sulfide slag according to the weight percentage of the arsenic content in the arsenic sulfide slag.

And c) washing the copper-precipitated slag obtained through copper precipitation in the step b) by using the leached liquid obtained in the step a), and controlling the liquid-solid ratio of washing so that the concentration of copper in the liquid after washing is not less than 2g/L to obtain the washed copper slag and the liquid after washing, wherein the washing temperature is 75-95 ℃ and the time is 30-90 minutes.

The hot copper-precipitating liquid is cooled and crystallized in the step d), the temperature of the hot copper-precipitating liquid is 75-95 ℃, and the cooling is carried out to a certain temperature of 0-35 ℃.

And d) adding acid and water to adjust the concentration of sulfuric acid to be 50-150 g/L, wherein the multi-round return times are controlled according to the condition that the concentration of zinc in the crystallized liquid is not lower than 80g/L, and the concentration of sulfuric acid in the produced crystallized liquid with the concentration of zinc not lower than 80g/L is 50-150 g/L and the concentration of arsenic is 5-15 g/L.

For a better understanding of the present invention, several steps described in the above invention are further described below.

For leaching of arsenic-containing smoke dust in copper smelting, the most common method is to leach with pure sulfuric acid aqueous solution or water solution, and the advantage is that bismuth does not enter leaching liquid in the leaching process, and the obtained leaching slag is directly sent into a lead smelting system for reduction smelting. The resulting leachate is costly to dispose of as described above.

In the process of leaching the arsenic-containing smoke dust in copper smelting, the leaching process is basically the same as the known sulfuric acid aqueous solution leaching process, the dilute sulfuric acid aqueous solution is adopted in the first leaching process, and in the specification, newly matched leaching solutions are prepared according to the method. The step of the invention is carried out, and the obtained arsenic trioxide crystallization mother liquor is added with sulfuric acid to obtain the dilute sulfuric acid aqueous solution containing trivalent arsenic for leaching. Of course, arsenic trioxide can be added to the pre-leaching solution in the first leaching, but this is not reasonable. According to the fact that the arsenic-containing smoke dust is leached by adopting a dilute sulfuric acid aqueous solution, the obtained leaching solution contains a large amount of pentavalent arsenic and a large amount of production practice results show that arsenic in the copper smelting arsenic-containing smoke dust mainly exists in the form of pentavalent arsenic, trivalent arsenic accounts for a small amount, copper part is copper sulfate, the rest is copper sulfide and a small amount of copper oxide and cuprous oxide according to raw material differences, white smoke dust contains more oxides, such as copper oxide, zinc oxide, cadmium oxide, lead oxide and the like, and the main reactions which can occur in the dilute sulfuric acid aqueous solution of the copper smelting arsenic-containing smoke dust are as follows:

PbO+H ₂ SO ₄ ＝PbSO ₄ +H ₂ O

CuO+H ₂ SO ₄ ＝CuSO ₄ +H ₂ O

As ₂ O ₃ +H ₂ O＝2HAsO ₂

Pb ₃ (AsO ₄ ) ₂ +3H ₂ SO ₄ ＝2H ₃ AsO ₄ +3PbSO ₄

ZnO+H ₂ SO ₄ ＝ZnSO ₄ +H ₂ O

copper sulfate is directly dissolved into leaching solution, the reaction is acid consumption reaction, the acid consumption in the process is greatly different according to different raw materials, and in order to obtain stable leaching rate, the sulfuric acid concentration and the liquid-solid ratio of the liquid before leaching are regulated and controlled according to the acid consumption of the raw materials, so that the acidity of the liquid after leaching is controlled.

The acid leached liquid (leached liquid) containing copper, zinc, cadmium, pentavalent arsenic acid and a small amount of trivalent arsenic acid is obtained through leaching, and besides lead bismuth enters leaching slag, the leaching slag also contains a small amount of copper oxide difficult to leach, copper sulfide and part of arsenic compounds difficult to leach, and the elements and the lead bismuth in the leaching slag are sent to a lead smelting system for recovery.

For the obtained leached liquid, a great deal of researches show that arsenic in the solution mainly exists in the form of pentavalent arsenic acid and a small amount of trivalent arsenic acid, and the leached liquid contains a great deal of copper ions, so that how to separate various valuable elements from arsenic in the solution becomes the key for solving the problem by utilizing the characteristic of the solution.

After a lot of researches, we find that when excessive arsenic sulfide slag is added to deposit copper, copper in the solution can be simultaneously deposited into copper sulfide and pentavalent arsenic is reduced into trivalent arsenic, so that the problem of reduction of pentavalent arsenic in leached liquid is solved, and we refer to the process as copper deposition reduction, which is the biggest difference between the invention and the prior art, and possible main reactions are as follows:

3Cu ²⁺ +As ₂ S ₃ +4H ₂ O＝2HAsO ₂ +3CuS+6H ⁺

2H ₃ AsO ₄ +As ₂ S ₃ ＝2HAsO ₂ +3S+2H ₂ O

from the above reaction, it can be seen that: in the process, the product of reducing pentavalent arsenic by arsenic sulfide is trivalent arsenic acid and elemental sulfur, so that the problem of sulfuric acid produced by reducing pentavalent arsenic by sulfur dioxide is avoided, the produced elemental sulfur and copper enter copper precipitation slag together, and sulfur in the arsenic sulfide slag is recovered in the subsequent copper smelting process. In the research, the reaction between arsenic sulfide slag and copper ions and pentavalent arsenic in the solution is mild, no harmful gas is discharged in the process, and the obtained copper-precipitating reduction slag has good filtering performance. When excessive arsenic sulfide slag is added, copper ions in the solution are almost completely precipitated into the slag in the process, pentavalent arsenic is almost completely reduced into trivalent arsenic, and most of arsenic in the added arsenic sulfide slag is also dissolved into copper-precipitating liquid, so that copper-precipitating liquid with higher trivalent arsenic concentration and lower pentavalent arsenic concentration is obtained. Because the arsenic sulfide slag is excessively added, the excessive arsenic sulfide slag inevitably remains in the precipitated copper reducing slag (the precipitated copper slag for short), the produced precipitated copper slag contains high arsenic, but because the produced precipitated copper slag is small in quantity, when the copper smelting plant circulates back to the burden, the arsenic can be directly returned to the smelting burden without further dearsenization, and obviously, the method can lead some arsenic to be circulated back to the copper smelting system along with the precipitated copper slag. In order to reduce arsenic content in the copper-precipitating slag, the invention also provides another option, namely, the leaching solution is utilized to wash the obtained copper-precipitating slag at a certain temperature, so that arsenic in the copper-precipitating slag reacts with copper and pentavalent arsenic in the leaching solution, and most of arsenic in the copper-precipitating slag is dissolved into the washed liquid, thereby obtaining lower washed copper slag, but an operation process is added. The implementation enterprises of the patent can flexibly select whether to add the process according to own conditions.

In the copper precipitation reduction process, the arsenic sulfide slag is used as a copper precipitation reagent and also used as a reducing agent of pentavalent arsenic, a large amount of arsenic sulfide slag is treated while copper precipitation and pentavalent arsenic reduction are realized, arsenic in the arsenic sulfide slag is leached into copper precipitation liquid in the copper precipitation and pentavalent arsenic reduction process, and part of sulfur and copper ions are combined into copper sulfide to enter the copper precipitation slag. The other part of sulfur in the arsenic sulfide slag reacts with pentavalent arsenic to generate elemental sulfur which enters the copper-precipitating slag, and in the copper-precipitating reduction process, zinc and cadmium do not react with the arsenic sulfide slag and remain in the solution after copper-precipitating reduction, so that the separation of copper and arsenic zinc is realized, which is the most important technical core of the invention.

During this process, due to the combination of copper sulphate in solution and sulphur in arsenic sulphide, a portion of the sulphuric acid is produced, which is advantageous in reducing the consumption of sulphuric acid during leaching, and in general it is known that copper ions react with arsenic sulphide as follows:

3Cu ²⁺ +As ₂ S ₃ +4H ₂ O＝2HAsO ₂ +3CuS+6H ⁺

and for the obtained copper-precipitating liquid, arsenic in the solution mainly exists in a trivalent arsenic form, the concentration is high, most of trivalent arsenic can be crystallized into arsenic trioxide by direct cooling, and the crystallization liquid with low arsenic content can be obtained after solid-liquid separation. In the processes of copper precipitation reduction and cooling crystallization of the solution after copper precipitation reduction, because the sulfate of zinc and cadmium has high solubility and does not enter arsenic trioxide crystals, the zinc and cadmium sulfate is left in crystallization mother liquor, and the obtained crystallization mother liquor is only dilute sulfuric acid solution containing a small amount of trivalent arsenic, and because part of sulfuric acid is consumed and part of water is evaporated in leaching, the leaching can be returned by adding industrial concentrated sulfuric acid and additional water, so that the circulation of leaching liquid is completed.

For the return of the crystallization liquid with lower arsenic content, part of trivalent arsenic in the crystallization liquid can not be crystallized, and the valence state of the part of trivalent arsenic is not changed in the circulating process. When the arsenic-containing smoke dust is returned to the copper smelting and leaching, the total concentration of arsenic is arsenic which enters the solution in the leaching process of adding arsenic in the crystallized solution into the copper smelting and leaching of the arsenic-containing smoke dust. The arsenic concentration of the liquid after crystallization is low, the change is small, the solution is partially concentrated during copper precipitation reaction, arsenic contained in the liquid after crystallization in circulation is subtracted, arsenic in the liquid after leaching of the arsenic-containing smoke dust in copper smelting and arsenic in arsenic sulfide slag can be almost completely crystallized in the form of arsenic trioxide, and the crystallization rate can exceed 100 percent according to the arsenic dissolved by leaching the arsenic-containing smoke dust in copper smelting and the arsenic added into the arsenic sulfide slag, so that the process of improving the arsenic concentration by evaporation concentration and the method of reducing pentavalent arsenic by sulfur dioxide are avoided, and a large amount of arsenic sulfide slag can be treated simultaneously.

As can be seen from Table 1d of example 1, the lower the cooling crystallization end point temperature, the more arsenic trioxide crystals are obtained. The higher the crystallization rate is, the higher the cooling end temperature depends on the natural environment temperature, the crystallization rate is increased in winter and is reduced in summer, and generally, the most common cooling crystallization means is to use an air cooling tower for cooling, so that cooling crystallization water is recycled, and the cooling water temperature obtained by the cooling mode depends on the outdoor temperature and humidity. The invention is not limited to the way in which the solution is cooled, for example, a refrigeration device can be used to obtain a lower temperature cooling water for recycling in summer. However, in this patent, when the temperature of the liquid after cooling and crystallization is high, only the arsenic concentration in the liquid after crystallization is slightly high, and the leaching effect of the regenerated and returned smoke is not affected, and only the time required for cooling and crystallization is prolonged, but this can be solved by parameters related to a cooling system, which are known technical means.

Because the arsenic-containing smoke dust in copper smelting contains some zinc, in the solution circulation process, zinc mainly remains in the liquid after crystallization due to the fact that the solubility of zinc sulfate is large, and along with the increase of circulation times, the concentration of zinc can reach high concentration. Therefore, when the post-crystallization liquid is recycled, the zinc concentration should be controlled below 80 g/L. The obtained crystallization liquid containing a small amount of trivalent arsenic and having higher zinc content can be sent to a zinc recovery system, and the zinc is recovered by a known method.

By the processes of the solution, the recycling of the solution is realized, the output of the discharged solution is greatly reduced, and the treatment of the discharged solution amount is correspondingly reduced.

By the treatment method for the copper smelting arsenic-containing smoke dust, copper and arsenic in the copper smelting arsenic-containing smoke dust and arsenic sulfide slag can be separated into copper sulfide slag with high copper content and low arsenic content, lead and bismuth are separated into lead and bismuth slag with a small amount of arsenic and copper content, and arsenic is separated into arsenic trioxide crystals with high content and crystallization post-liquid with high zinc content and arsenic content.

In summary, on the basis of adopting the treatment method of the arsenic-containing dust for copper smelting provided by the invention, the resource utilization of the arsenic-containing dust for copper smelting and arsenic sulfide slag can be realized by matching with the matched solution provided by the invention, the treatment capacity of arsenic-containing solution is greatly reduced, and the economic benefit of the treatment of the arsenic-containing dust for copper smelting is improved.

The various processes of the present invention are described in detail above and are further described below in conjunction with the examples.

Drawings

FIG. 1 shows the treatment process flow of arsenic-containing smoke dust in copper smelting

Detailed Description

The arsenic-containing smoke dust produced in the copper smelting process is a product in the copper pyrometallurgy process and arsenic sulfide slag produced by smelting waste acid, and the components are shown in table 1

TABLE 1 arsenic-containing dust and slag components for copper smelting

Element(s)	Cu％	Pb％	Zn％	Cd％	As％	Bi％	S％
								Arsenic-containing smoke 1#	15.97	15.19	4.02	0.38	8.76	1.87
Arsenic-containing dust 2#	9.69	37.94	5.51	0.63	13.18	1.35
								Arsenic sulfide slag					47.93		42.56

Example 1

According to the claims and the attached drawing 1, the embodiment is the implementation result of the wet combined treatment of the arsenic-containing dust 1# and the arsenic sulfide slag in copper smelting:

1-a) arsenic-containing dust leaching of copper smelting

The solution used was 5L of fresh dilute sulfuric acid aqueous solution, the sulfuric acid concentration was 150g/L, the sulfuric acid used was 98% industrial sulfuric acid (the same applies below), the solution was heated to 95℃and reacted for 0.5 hour with stirring, the leaching residue was obtained by filtration, and the obtained results are shown in Table 1a.

TABLE 1a

The arsenic valence state of the leached liquid is detected, wherein 95.2 percent of the arsenic is pentavalent arsenic, 4.8 percent of the arsenic is trivalent arsenic, the concentration of the pentavalent arsenic is 10.69g/L, and the concentration of the trivalent arsenic is 0.54g/L, which indicates that the arsenic in the leached liquid is mainly pentavalent arsenic. As can be seen from Table 1a, the leaching rates (in terms of liquor) of leached copper, arsenic, zinc and cadmium reached 97.82%, 96.43%, 93.16% and 90.22%, respectively, when leached with dilute aqueous sulfuric acid. Lead and bismuth do not enter the solution in the process.

1-b) copper deposition from leached liquid arsenic sulfide slag

Experiment 1b-1, post-leach liquor from table 1a, reaction conditions: the reaction was carried out for 30 minutes at 95℃and the amount of arsenic sulfide slag added was 1.05 times the theoretical amount of copper precipitation and reduction of pentavalent arsenic in the solution, and the results are shown in Table 1b-1.

TABLE 1b-1

Experiment 1b-1	Volume L/weight g	Cu(g/L)	Total As (g/L)	As ⁵⁺ (g/L)	As ³⁺ (g/L)	Zn(g/L)	Free sulfuric acid (g/L)
								Post-leaching liquor	1.00	20.97	11.23	10.69	0.54	4.68	134.83
Arsenic sulfide slag	51.72		47.93％
								Copper precipitation post-treatment liquid	1.01	1.05	34.25	0.38	33.87	4.63	137.71
Copper slag	51.75	40.52％	2.70％

Using the post-leach liquors in table 1a, reaction conditions: the reaction was carried out for 90 minutes at 75℃and the amount of arsenic sulfide slag added was 1.2 times the theoretical amount of copper precipitation and reduction of pentavalent arsenic in the solution, and the results are shown in tables 1b-2.

TABLE 1b-2

Using the post-leach liquors in table 1a, reaction conditions: the reaction was carried out for 60 minutes at 85℃and the amount of arsenic sulfide slag added was 1.1 times the theoretical amount of copper precipitation and reduction of pentavalent arsenic in the solution, and the results are shown in tables 1b-3.

Tables 1b-3

Using the post-leach liquors in table 1a, reaction conditions: the reaction was carried out for 90 minutes at 70℃and the amount of arsenic sulphide slag added was 1.1 times the theoretical amount of copper precipitation and reduction of pentavalent arsenic in the solution, and the results are shown in tables 1b-4.

Tables 1b to 4

As can be seen from the results in tables 1b-4, when the temperature was lowered to 70 ℃, the reaction time was prolonged to 90 minutes, and the action rate of arsenic sulfide slag was very low, resulting in incomplete copper precipitation in the solution, the arsenic content in the copper precipitation slag was as high as 14.97%, and the copper content was reduced to 25.65%.

As can be seen from tables 1b-1 to 1b-3, when arsenic sulfide slag is added in an amount of 1.05 to 1.2 times the theoretical amount, a better copper precipitation effect can be obtained at a temperature of 75 ℃ or higher. The arsenic content of the obtained copper-precipitating slag is between 2.7 and 6.67 percent, calculated according to the arsenic content of raw material smoke dust, the arsenic content of the copper-precipitating slag which is directly returned to a copper smelting system is 17.91 to 36.55 percent of the arsenic content of the smoke dust, which is obviously higher, and the part of arsenic circulates in the copper smelting system, but the scheme can be selected by a copper smelting plant according to the flow. If the precipitated copper slag is directly sold, the selling price is reduced, and the economic benefit is poor, in order to solve the problem, the invention provides another scheme for obtaining the low-arsenic washed copper slag by adopting leached liquid for washing and dearsenifying.

1-c) washing copper-precipitating slag and reducing copper-precipitating liquid after washing

Experiment No. 1c-1 the copper-precipitated slag in table 1b-1 was washed with the post-leaching liquor in table 1a, reaction conditions: the reaction was carried out for 30 minutes at 95℃and the results are shown in Table 1c-1.

TABLE 1c-1

Experiment 1c-1	Volume L/weight g	Cu(g/L)	Total As (g/L)	Free sulfuric acid (g/L)
					Post-leaching liquor	1.00	20.97	11.23	134.83
Copper slag	51.75	40.52％	2.70％
					Post-washing liquid	0.99	19.19	12.65	137.87
Washing copper slag	42.44	54.05％	0.24％

Because the concentration of copper and arsenic in the leached liquid and the washed liquid are not greatly changed, arsenic in the leached liquid is mainly pentavalent arsenic, and therefore arsenic in the washed liquid is mainly pentavalent arsenic, and the total arsenic content can be calculated as pentavalent arsenic. The washing liquid adopts arsenic sulfide slag to deposit copper, and the reaction conditions are as follows: the reaction was carried out for 30 minutes at 95℃and the amount of arsenic sulfide slag added was 1.05 times the theoretical amount of copper precipitation and reduction of pentavalent arsenic in the solution, and the results are shown in tables 1c-2.

TABLE 1c-2

The copper-precipitated slag in table 1b-2 was washed with the post-leaching liquor in table 1a, reaction conditions: the reaction was carried out for 90 minutes at 75℃and the results are shown in tables 1c-3.

TABLE 1c-3

Experiment 1c-3	Volume L/weight g	Cu(g/L)	Total As (g/L)	Free sulfuric acid (g/L)
					Post-leaching liquor	1.00	20.97	11.23	134.83
Copper slag	57.59	36.25％	6.67％
					Post-washing liquid	0.99	16.25	15.10	142.37
Washing copper slag	48.22	53.43％	0.25％

The washing liquid adopts arsenic sulfide slag to deposit copper, and the reaction conditions are as follows: the reaction was carried out for 90 minutes at 75℃and the amount of arsenic sulfide slag added was 1.2 times the theoretical amount of copper precipitation and reduction of pentavalent arsenic in the solution, and the results are shown in tables 1c to 4.

Tables 1c-4

Experiment 1c-4	Volume L/weight g	Cu(g/L)	Total As (g/L)	Free sulfuric acid (g/L)
					Post-washing liquid	0.99	16.25	15.10	142.37
Arsenic sulfide slag	56.61		47.93％
					Copper precipitation post-treatment liquid	0.99	0.0022	37.75	149.12
Copper slag	40.63	39.59％	11.13％

As can be seen from tables 1c-4, due to the excessive addition of arsenic sulfide slag, the unreacted portion of the arsenic sulfide slag entered the copper precipitation slag, resulting in an arsenic content of 11.13%.

The copper-precipitated slag in tables 1b-3 was washed with the post-leaching liquor in table 1a, reaction conditions: the reaction was carried out for 60 minutes at 85℃and the results are shown in tables 1c-5.

Tables 1c-5

Experiment 1c-5	Volume L/weight g	Cu(g/L)	Total As (g/L)	Free sulfuric acid (g/L)
					Post-leaching liquor	1.00	20.97	11.23	134.83
Copper slag	58.51	35.84％	3.31％
					Post-washing liquid	0.98	18.88	13.31	138.63
Washing copper slag	43.41	53.98％	0.24％

The washing liquid adopts arsenic sulfide slag to deposit copper, and the reaction conditions are as follows: the reaction was carried out for 60 minutes at 85℃and the amount of arsenic sulfide slag added was 1.1 times the theoretical amount of copper precipitation and reduction of pentavalent arsenic in the solution, and the results are shown in tables 1c-6.

Tables 1c-6

Experiment 1c-6	Volume L/weight g	Cu(g/L)	Total As (g/L)	Free sulfuric acid (g/L)
					Post-washing liquid	0.98	18.88	13.31	138.63
Arsenic sulfide slag	53.36		47.93％
					Copper precipitation post-treatment liquid	0.96	0.0023	37.81	145.43
Copper slag	45.57	40.60％	5.10％

As can be seen from tables 1c-1 to 1c-6, the obtained low-arsenic copper-precipitation washing slag contains about 0.24% of arsenic after washing, is thoroughly separated from copper and arsenic, is directly sold, and has higher selling price. From the results obtained in tables 1c-1,1c-3,1c-5, it can be seen that the concentration of copper and arsenic in the post-leaching solution and the post-leaching solution does not change much, and the post-leaching solution can be singly or/and mixed with the post-leaching solution, and a proper amount of arsenic sulfide slag is added for copper precipitation reduction, and for the sake of simplifying the process, it is preferable that the post-leaching solution and the post-leaching solution are combined for copper precipitation reduction.

1-d) liquid cooling crystallization and leaching liquid regeneration after copper precipitation

The mixed solution of the post-copper deposition solutions obtained in tables 1b-1,1b-2,1b-3 was used for cooling crystallization to obtain a post-crystallization solution and arsenic trioxide crystals. The cooling crystallization terminal temperatures were 35℃and 25℃and 0℃respectively, and the results are shown in Table 1d.

TABLE 1d

Experiment 1d	Volume L/weight g	Cu(g/L)	As(g/L)	Zn(g/L)	Crystallization Rate	Temperature (DEG C)	Free sulfuric acid (g/L)
								Copper precipitation post-treatment liquid	1.00	0.0025	34.26	4.88		80	137.18
Post-crystallization liquid	0.95	0.0020	11.50	5.14		35	144.40
								Arsenic trioxide crystals	31.13		73.46％		66.75％
	Volume L/weight g	Cu(g/L)	As(g/L)	Zn(g/L)		Temperature (DEG C)
								Copper precipitation post-treatment liquid	1.00	0.0025	34.26	4.88		80	137.18
Post-crystallization liquid	0.94	0.0020	10.15	5.19		25	145.94
								Arsenic trioxide crystals	32.64		74.22％		70.71％
	Volume L/weight g	Cu(g/L)	As(g/L)	Zn(g/L)		Temperature (DEG C)
								Copper precipitation post-treatment liquid	1.00	0.0025	34.26	4.88		80	137.18
Post-crystallization liquid	0.92	0.0020	6.50	5.30		0	149.11
								Arsenic trioxide crystals	36.13		74.37％		78.42％

As can be seen from Table 1d, the lower the cooling crystallization end point temperature, the more arsenic trioxide crystals were obtained, the higher the crystallization rate, the cooling end point temperature was dependent on the natural environment temperature, the crystallization rate increased in winter and decreased in summer. From the concentration of free sulfuric acid in the post-crystallization solution obtained in Table 1d, the initial sulfuric acid concentration in Table 1a is 150g/L, the acid concentration in the post-crystallization solution is 144.40 g/L-149.11 g/L, which means that part of the acid is consumed in the process of a) to d), sulfuric acid is needed to be added, the volume of the solution in the process is reduced, and each liter of solution is added with 0.89 g-5.60 g of industrial sulfuric acid (98%) to obtain regenerated leaching solution, and the regenerated leaching solution is returned to the circulation leaching.

From the results obtained in example 1, it can be seen that by adopting the method provided by the invention, better separation of valuable elements of the arsenic-containing smoke dust from arsenic in copper smelting is realized, and the solution is circulated.

Example 2

This example shows the results of the leaching of arsenic-containing fumes 1# from copper smelting as set forth in Table 1:

the leaching solution was a newly prepared dilute sulfuric acid aqueous solution (5L) with a sulfuric acid concentration of 135g/L and a 98% sulfuric acid solution (the same applies below), the solution was heated to 75℃and stirred for 1.5 hours, and the leaching residue was obtained by filtration, and the results are shown in Table 2a.

TABLE 2a

The leaching solution was a newly prepared dilute sulfuric acid aqueous solution (5L) with a sulfuric acid concentration of 150g/L and a 98% sulfuric acid solution (the same applies below), the solution was heated to 80℃and stirred for 1 hour, and the leaching residue was obtained by filtration, and the obtained results are shown in Table 2b.

TABLE 2b

From the results obtained in example 2, it can be seen that the method provided by the invention can be used for better separation of valuable elements of the arsenic-containing smoke dust from arsenic in copper smelting, and lead bismuth slag with low copper and arsenic can be obtained.

Example 3

The embodiment is the implementation result of the arsenic-containing smoke dust 2# leaching in copper smelting: the solution obtained by regenerating the mixed solution of the post-crystallization solution in example 1 was used as a leaching solution, the sulfuric acid concentration was 65g/L, the sulfuric acid used was 98% industrial sulfuric acid (the same applies below), the solution was heated to 70℃and reacted with stirring for 1 hour, leaching residue was obtained by filtration, and the obtained results are shown in Table 3b.

TABLE 3b

Experiment 3b

Volume L/weight g

Cu(g/L)

Total As (g/L)

Zn(g/L)

Bi(g/l)

Pb％

Free acid (g/L)

Arsenic-containing dust 2#

110.00

9.69％

13.18％

5.51％

1.35％

37.94％

Leachate solution

1.00

0.0051

9.36

5.21

0.00

65.00

Leaching residue

101.17

6.27％

3.85％

1.78％

1.47％

41.25％

Post-leaching liquor

0.96

4.49

20.79

9.86

0.001

0.00

47.13

Leaching rate (in terms of liquid)

40.36％

73.12％

70.26％

0.001％

0.00

From the results obtained in example 3, it can be seen that with the reaction temperature and the sulfuric acid concentration of the leached liquid below 50g/L, the leaching rate of leached copper, arsenic and arsenic is significantly reduced, and the copper and arsenic content in the leached slag is greatly increased.

Example 4

The embodiment is an implementation result of repeatedly recycling and leaching the 1# leaching solution of the arsenic-containing smoke dust in copper smelting:

the solution obtained by regenerating the mixed solution of the post-crystallization solutions in example 1 was used as the first leaching solution, the leaching solution recycled to the nineteenth leaching was used as the leaching solution for the twentieth leaching, the concentration of the leached sulfuric acid was 150g/L, the concentration of the used sulfuric acid was 98% industrial sulfuric acid (the same applies below), the solution was heated to 80 ℃, stirred and reacted for 1 hour, and the leaching residue was obtained by filtration, and the obtained results are shown in Table 4a.

As can be seen from example 4, since the concentrations of copper and arsenic in the liquid after crystallization do not accumulate, the leachate is used for leaching after repeated cyclic regeneration, and only the concentrations of zinc and cadmium ions are continuously increased in the cyclic regeneration process, so that the viscosity of the solution is increased, and the solid-liquid separation speed after leaching is easily reduced. When the concentration of zinc is enriched to a certain extent, the well-known technology can be used for recovering zinc.

From the above rich examples we can see: by adopting the treatment method of the copper smelting arsenic-containing smoke dust, valuable lead, copper, zinc, bismuth and arsenic in the copper smelting arsenic-containing smoke dust are thoroughly separated, and the solution in the whole treatment process is circulated, compared with the prior art, the treatment method has the following characteristics:

(1) For the treatment of the leaching solution, arsenic sulfide slag is used as a separating reagent of the leaching solution, in the treatment process of the arsenic-containing smoke dust leaching solution in copper smelting, sulfur ions in the arsenic sulfide slag are used as a copper sulfide precipitating agent, and part of acid can be regenerated in the copper precipitating process. The arsenic sulfide slag is used as a reducing agent to reduce pentavalent arsenic in the solution into trivalent, acid is not generated in the process, and the problem of acid expansion caused by sulfuric acid produced by reduction of sulfur dioxide is avoided. In the copper precipitation and reduction of pentavalent arsenic, sulfur in the arsenic sulfide slag enters the copper sulfide slag, and the sulfur is recovered as a raw material in subsequent processing, and a large amount of arsenic sulfide slag is additionally treated in the copper precipitation.

(2) In the method provided by the invention, the two elements realize circulating enrichment in the process, and the zinc and the cadmium can be recovered by adopting a known method.

(3) Because the arsenic-containing dust for copper smelting contains a large amount of sulfate, a certain amount of sulfuric acid is consumed for leaching the arsenic-containing dust for copper smelting, and when copper is precipitated by adopting the arsenic sulfide slag, part of sulfuric acid is regenerated by the solution, so that the consumption of sulfuric acid for one-stage leaching is reduced, and the cost is reduced.

(4) In the invention, after separating arsenic, copper, bismuth and lead, the solution is completely returned to the system for leaching, and the water in the solution is partially volatilized in the process due to the adoption of high-temperature leaching, so that the volume of the solution is reduced. In general, in the hydrometallurgy process, in order to reduce metal loss in slag, a small amount of water is generally needed to wash the slag, and the washing water can be returned to the leaching process to supplement the volatilization loss of water in the leaching process, and the volume balance of the solution can be realized by only adding a small amount of water in the insufficient part, so that a necessary condition is created for long-term stable closed recycling of the solution. The whole treatment process has no generation of highly toxic gases such as arsine, hydrogen sulfide and the like, arsenic is not volatilized in dilute sulfuric acid solution in the process, the process is safe, the relatively thorough separation of valuable elements in arsenic-containing smoke dust and arsenic sulfide slag in copper smelting is realized, and no waste liquid and waste gas are produced in the treatment process. Arsenic is produced in the form of arsenic trioxide, has higher purity, and provides raw materials for the subsequent recycling of arsenic-containing products.

(5) The technical scheme provided by the invention is carried out under normal pressure, the equipment is simple, the operation is easy, the cost is low, and the industrial application is easy.

(6) The method for treating the arsenic-containing smoke dust in copper smelting, which is adopted by the invention, not only can reduce the treatment cost of the arsenic-containing smoke dust in copper smelting, but also can save huge arsenic sulfide slag treatment cost, greatly reduces the treatment cost on the premise of realizing good separation of valuable elements and arsenic in two dangerous waste raw materials, and improves the economic benefit of independently treating the arsenic-containing smoke dust in copper smelting and the arsenic sulfide slag.

In conclusion, the treatment method for the arsenic-containing dust in copper smelting provided by the invention realizes the purposes of treating the arsenic-containing dust and arsenic sulfide slag in copper smelting with low cost and low pollution, can realize better economic benefit, can generate good economic and social benefits after industrialization, and has great promotion effect on solving arsenic pollution of nonferrous metallurgy enterprises.

Finally, the above embodiments and the accompanying drawings are only for illustrating the technical solution of the present invention and not for limiting it, and although the present invention has been described in detail by the specification and the above embodiments, it should be understood by those skilled in the art that various changes in form and details may be made therein without departing from the scope of the present invention as defined in the appended claims.

Claims

1. The treatment method of the arsenic-containing smoke dust in copper smelting improves the known wet treatment flow of the sulfuric acid aqueous solution of the arsenic-containing smoke dust in copper smelting, and is characterized by comprising the following steps:

b) Adding a proper amount of arsenic sulfide slag into the leached liquid obtained in the step a) to carry out copper precipitation reduction, precipitating copper and reducing pentavalent arsenic in the leached liquid, reacting for a certain time at a certain temperature under stirring, and carrying out hot filtration to obtain copper precipitation slag and hot copper precipitation liquid, wherein the obtained copper precipitation slag can be directly fed into a copper smelting system to serve as a raw material, and can also be transferred into a subsequent step c) for treatment;

c) A certain amount of copper slag precipitated from the step b) is washed and dearsenified by adopting a certain volume of the part of leached liquid from the step a) and stirring reaction for a certain time at a certain temperature to obtain washed copper slag and washed liquid, wherein the washed copper slag is low-arsenic copper slag, and the washed liquid is singly or/and after being mixed with the leached liquid,

Preferably, the copper precipitation reduction is carried out by returning to the step b) after being mixed with the leached liquid;

d) And b) indirectly cooling the hot copper-precipitating solution obtained in the step b), cooling to a certain temperature under stirring, carrying out solid-liquid separation to obtain arsenic trioxide crystals and crystallized solution, adding sulfuric acid and water into the crystallized solution to adjust acidity, regenerating to obtain the leaching solution obtained in the step a), recycling the leaching solution to the leaching process in the step a), enriching zinc and cadmium in the solution, repeating the steps a-d), and carrying out multiple rounds/cycles to obtain an acidic arsenic-containing zinc sulfate solution with higher zinc concentration, wherein the acidic arsenic-containing zinc sulfate solution is sent into a zinc recovery system, and zinc is recovered by adopting the known technology.

2. The method according to claim 1, characterized in that: the concentration of the arsenic-containing sulfuric acid aqueous solution in the step a) is that the liquid-solid ratio and the sulfuric acid concentration of the leaching solution are adjusted according to different smoke dust acid consumption, the concentration of the leached liquid sulfuric acid is controlled to be not lower than 50g/L, the temperature is 75-95 ℃, and the leaching time is 30-90 minutes.

3. The method according to claim 1, characterized in that: adding a proper amount of copper in the arsenic sulfide slag precipitation solution and pentavalent arsenic in the reduction solution into the leached liquid in the step a), wherein the added arsenic sulfide slag amount is 1.05-1.2 times of the theoretical amount of copper precipitation and pentavalent arsenic reduction in the solution, the reaction temperature is 75-95 ℃, the reaction time is 30-90 minutes, the pentavalent arsenic concentration in the copper precipitation solution is less than 1g/L, the copper concentration is less than 1g/L, the theoretical amount of arsenic sulfide slag addition is the mole number of arsenic added into the arsenic sulfide slag calculated according to two thirds of the sum of the mole numbers of copper and pentavalent arsenic in the solution, and the added arsenic sulfide slag is converted into the added arsenic sulfide slag according to the weight percentage of the arsenic content in the arsenic sulfide slag.

4. The method according to claim 1, characterized in that: and c) washing the copper-precipitated slag obtained through copper precipitation in the step b) by using the leached liquid obtained in the step a), and controlling the liquid-solid ratio of washing so that the concentration of copper in the liquid after washing is not less than 2g/L to obtain the washed copper slag and the liquid after washing, wherein the washing temperature is 75-95 ℃ and the time is 30-90 minutes.

5. The method according to claim 1, characterized in that: the hot copper-precipitating liquid is cooled and crystallized in the step d), the temperature of the hot copper-precipitating liquid is 75-95 ℃, and the cooling is carried out to a certain temperature of 0-35 ℃.

6. The method according to claim 1, characterized in that: and d) adding acid and water to adjust the concentration of sulfuric acid to be 50-150 g/L, wherein the multi-round return times are controlled according to the condition that the concentration of zinc in the crystallized liquid is not lower than 80g/L, and the concentration of sulfuric acid in the produced crystallized liquid with the concentration of zinc not lower than 80g/L is 50-150 g/L and the concentration of arsenic is 5-15 g/L.