Method for treating copper-containing high-arsenic hazardous waste and application thereof

Abstract

The invention discloses a method for treating copper-containing high-arsenic hazardous waste and application of the method, and relates to the technical field of chemical metallurgy. The method comprises the following steps: carrying out acid leaching on the white smoke dust, and carrying out solid-liquid separation to obtain acid leaching residues and an acid leaching solution; adding goethite slag into the acid leaching solution to carry out first reaction to obtain arsenic-iron leaching slag and first reaction solution; iron powder is added into the first reaction liquid for second reaction, and copper slag and second reaction liquid are obtained; and adding steel mill soot and an oxidizing agent into the second reaction liquid to carry out third reaction to obtain goethite slag and iron-removed liquid. When the method is used for treating the copper-containing high-arsenic hazardous waste white smoke dust, only one kind of arsenic acid iron slag is generated and piled, other filter residues are even and can be sold in a pricing mode, and the method has good application prospects in the aspects of efficient recycling of valuable metal and high-value utilization of the white smoke dust.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of chemical metallurgy, in particular to a method for treating copper-containing high-arsenic hazardous waste and application thereof. BACKGROUND

[0002] In the process of copper smelting, trace amounts of Pb, Zn, As, Sb, Bi, Cd and other elements contained in the charging material are enriched in the flue dust (referred to as white flue dust). The treatment process of white flue dust is mainly based on wet extraction, among which the sulfuric acid system leaching occupies a dominant position. Its essence is to take advantage of the characteristics that Pb, Bi and their compounds are almost insoluble in dilute sulfuric acid solution, to realize the separation of Pb, Bi from Cu, Zn, In, Cd and other metals through leaching, while a large amount of impurity elements such as As and Fe enter the leaching solution.

[0003] At present, there are mainly two types of methods for separating arsenic from sulfuric acid system arsenic-containing solution in the related art: (1) Patent "Method for cooperatively treating copper smelting arsenic sulfide slag and arsenic-containing flue dust" (application number 202110999586.7) uses arsenic sulfide slag to sulfide precipitate copper in the acid leaching solution of flue dust. After copper precipitation, ferrous sulfate (FeSO4) is added to the solution, and a stable iron arsenate (FeAsO4) is generated under oxygen pressure conditions. However, a large amount of sulfuric acid is generated during the arsenic precipitation process, and these excess sulfuric acid needs to be neutralized and treated, thereby generating a large amount of neutralization slag that needs to be further treated. (2) In the patent "Method for mixed leaching of zinc oxide and copper white flue dust" (application number 202210667812.6), zinc oxide is mixed with copper white flue dust and then added to the acid leaching solution for neutral leaching treatment. Iron powder is added to the neutral leaching solution to achieve copper precipitation and dechlorination. Oxygen is introduced into the solution after copper precipitation and dechlorination, and under specific temperature, pressure and time conditions, iron arsenate slag is generated by oxygen pressure iron precipitation and arsenic removal. However, only within a strict range of process parameters can arsenic be precipitated in the form of iron arsenate.

[0004] In view of the above shortcomings, the present research proposes a method for treating copper-containing high-arsenic hazardous waste, aiming to solve the problems of harmless treatment of intermediate products and comprehensive recovery of valuable metals in the process of copper smelting. SUMMARY

[0005] The present application aims to solve at least one of the technical problems existing in the prior art. To this end, the present application proposes a method for treating copper-containing high-arsenic hazardous waste.

[0006] The present application also provides the application of the above method.

[0007] The method for treating copper-containing high-arsenic hazardous waste according to the first aspect of the present application comprises the following steps: (1) After acid leaching of the white flue dust, solid-liquid separation is performed to obtain acid leaching residue and acid leaching solution; (2) adding goethite slag into the acid leaching solution to perform a first reaction, thereby obtaining arsenic-iron leaching residue and a first reaction solution; (3) adding iron powder into the first reaction solution to perform a second reaction, thereby obtaining copper residue and a second reaction solution; (4) adding steel plant soot and an oxidizing agent into the second reaction solution to perform a third reaction, thereby obtaining goethite slag and a solution after iron removal.

[0008] In some embodiments of the present application, the white dust includes arsenic-containing copper white dust.

[0009] In some embodiments of the present application, the white dust includes the following components in percentage by mass: 2-8 wt% of Cu, 5-20 wt% of Pb, 2-15 wt% of Zn, 1-5 wt% of Bi, 4-15 wt% of As, and 0.1-3 wt% of Fe.

[0010] In some embodiments of the present application, the white dust includes the following components in percentage by mass: 4-8 wt% of Cu, 10-20 wt% of Pb, 6-10 wt% of Zn, 1-3 wt% of Bi, 4-10 wt% of As, and 0.1-1 wt% of Fe.

[0011] In some embodiments of the present application, the white dust includes the following components in percentage by mass: 5-7 wt% of Cu, 10-15 wt% of Pb, 8-10 wt% of Zn, 2-3 wt% of Bi, 4-8 wt% of As, and 0.1-0.1 wt% of Fe.

[0012] In some embodiments of the present application, the acid solution used in the acid leaching treatment is a solution containing sulfuric acid.

[0013] In some embodiments of the present application, the initial sulfuric acid concentration of the acid leaching treatment is 40 g / L-50 g / L.

[0014] In some embodiments of the present application, the solid-liquid ratio of the white dust to the solution containing sulfuric acid is 1: (2~3) (mL / g).

[0015] In some embodiments of the present application, the temperature of the acid leaching treatment is 80-90 °C.

[0016] In some embodiments of the present application, the time of the acid leaching treatment is 0.5 h-2 h.

[0017] In some embodiments of the present application, the final acid concentration of the acid leaching treatment is 2 g / L-7 g / L.

[0018] In some embodiments of the present application, the final acid concentration of the acid leaching treatment is 4-6 g / L.

[0019] In some embodiments of the present application, the solid-liquid separation is performed by pressure filtration.

[0020] In some embodiments of the present application, the goethite residue is prepared in step (4).

[0021] In some embodiments of the present application, the first reaction is performed in an autoclave.

[0022] In some embodiments of the present application, the first reaction is performed at a temperature of 150-170°C, a pressure of 1-1.4 MPa, and an oxygen partial pressure of 0.4-0.8 MPa.

[0023] In some embodiments of the present application, the first reaction is performed at a temperature of 155-165°C, a pressure of 1.1-1.3 MPa, and an oxygen partial pressure of 0.5-0.7 MPa.

[0024] In some embodiments of the present application, the first reaction is performed for 2-4 h, specifically, 2 h, 3 h, or 4 h.

[0025] In some embodiments of the present application, the molar ratio of copper to iron powder in the first reaction solution is 1:1-2.

[0026] In some embodiments of the present application, the second reaction is performed at a temperature of 70-75°C.

[0027] In some embodiments of the present application, the second reaction is performed for 30-55 min.

[0028] In some embodiments of the present application, the second reaction is performed for 40-50 min.

[0029] In some embodiments of the present application, the steel plant fly ash comprises the following components in terms of mass percentage: 1-15 wt% of Fe, 0.1-1 wt% of As, and 50-70 wt% of Zn.

[0030] In some embodiments of the present application, the steel plant fly ash comprises the following components in terms of mass percentage: 2-10 wt% of Fe, 0.2-0.8 wt% of As, and 58-65 wt% of Zn.

[0031] In some embodiments of the present application, the third reaction is performed for 4-6 h, specifically, 4 h, 5 h, or 6 h.

[0032] In some embodiments of the present application, the iron content in the solution after iron removal is less than or equal to 2 g / L.

[0033] In some embodiments of the present application, the pH value at the end point of the third reaction is 5.0-5.4.

[0034] In some embodiments of the present application, the solution after iron removal is further treated to remove impurities to prepare zinc sulfate heptahydrate.

[0035] In some embodiments of the present application, the oxidizing agent comprises oxygen.

[0036] In some embodiments of the present application, the oxidizing agent comprises oxygen-enriched air.

[0037] In some embodiments of the present application, the oxygen concentration in the oxygen-enriched air is 35-40 v%.

[0038] According to the second aspect of the present application, the above method is applied in any one of the following: 1) recovering valuable metals in white fume dust; 2) removing arsenic from white fume dust.

[0039] In some embodiments of the present application, the valuable metals include lead, bismuth, arsenic, iron, copper and zinc.

[0040] According to some embodiments of the present application, at least the following beneficial effects are achieved: 1) The present application provides a method for treating copper-containing high-arsenic hazardous waste. Cu, Zn, Fe and As in the smelting slag are dissolved into the solution by acid leaching of white fume dust, while Pb and Bi elements are enriched in the leaching residue and sold. After treatment in an autoclave, the iron powder is used to replace and recover sponge copper. After copper precipitation, the needle iron ore slag is formed by adding steel dust in the iron removal process. The needle iron ore slag is used as an iron supplement for arsenic precipitation in the autoclave, and 95% of the arsenic is precipitated and converted into stable ferric arsenate precipitate. The solution after iron removal is further purified to recover valuable metals such as zinc. (1) Acid leaching of white fume dust makes Cu, Zn, Fe and As enter the solution, while Pb and Bi elements remain in the leaching residue, ensuring that the recovery rate of Pb and Bi is greater than 95%; (2) The needle iron ore slag is used as an arsenic precipitant, and there is no "acid swelling" phenomenon of FeSO4 arsenic precipitation in the autoclave, and no neutralization slag is produced. The needle iron ore slag is used as an iron supplement for arsenic removal in the white fume dust acid leaching solution in the autoclave, achieving arsenic-iron balance in the system, and 95% of the arsenic forms stable ferric arsenate slag, with a ferric arsenate content of greater than 80% in the slag; (3) Iron powder is used to replace and recover copper, ensuring that the copper recovery rate is greater than 95%. The added iron powder is used to produce needle iron ore slag in the iron removal process, and is returned to the autoclave as an iron supplement for arsenic precipitation, achieving "one iron for two purposes". (4) using steel plant fly ash as the neutralizing agent for the goethite iron removal process, controlling the iron removal end point pH=5~5.4, and ensuring that the liquid iron after iron removal is ≤2g / L; 2, the method of the application is used for treating the copper-containing high-arsenic hazardous waste white smoke dust, only one ferric arsenate slag is generated for stacking, and other filter residues can be sold at a price, and has a good application prospect in realizing efficient recovery of valuable metals and high-value utilization of white smoke dust.

[0041] Other features and advantages of the present application will be set forth in the following description, and in part will become apparent to those skilled in the art from the description, or can be learned by practice of the present application. BRIEF DESCRIPTION OF DRAWINGS

[0042] Figure 1 is the process flow chart of the application for treating copper-containing high-arsenic hazardous waste. DETAILED DESCRIPTION

[0043] The concept and technical effects of the present application will be described below in conjunction with examples, so as to fully understand the purpose, features and effects of the present application. Obviously, the described examples are only part of the examples of the present application, but not all examples. Based on the examples of the present application, other examples obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0044] In the examples, the specific conditions not mentioned are carried out according to the conventional conditions or the conditions recommended by the manufacturer. The reagents or instruments used are not marked with the manufacturer, which are conventional products that can be purchased on the market.

[0045] In the description of the present application, if the first, second, etc. are described, it is only for the purpose of distinguishing technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features or the sequence of indicated technical features.

[0046] In the description of the present application, it should be noted that, unless otherwise explicitly limited, the words such as setting, communication, etc. should be broadly understood, and those skilled in the art can reasonably determine the specific meaning of the above words in the present application in combination with the specific content of the technical solution.

[0047] When a numerical range is disclosed herein, the above range is considered to be continuous, and includes the minimum value and the maximum value of the range, and every value between the minimum value and the maximum value. Further, when the range refers to an integer, every integer between the minimum value and the maximum value of the range is included. In addition, when multiple ranges are provided to describe a feature or a characteristic, the ranges can be combined. In other words, unless otherwise indicated, all ranges disclosed herein should be understood to include any and all sub-ranges incorporated therein.

[0048] The term "not higher than" means less than or equal to, and should be understood to include the number itself.

[0049] The term "not less than" means greater than or equal to, and should be understood to include the number itself.

[0050] In the embodiments of this invention, the white dust involved is white dust produced as an intermediate product in copper smelting (containing approximately 6.19 wt% Cu, approximately 14.4 wt% Pb, approximately 8.59 wt% Zn, approximately 2.65 wt% Bi, approximately 6.24 wt% As, and approximately 0.78 wt% Fe) and steel mill dust (containing approximately 0.5 wt% As, approximately 62 wt% Zn, and approximately 2.56 wt% Fe). In the dust, Pb, Zn, and Cu mainly exist in the form of sulfates or oxides, while As mainly exists in the form of As₂O₃.

[0051] Example 1 This example provides a method for treating hazardous waste containing high levels of copper and arsenic. The method involves adding goethite slag from the iron removal process to an autoclave used in the acid leaching solution for treating white dust, using it as an iron source for arsenic precipitation from the white dust. This allows the arsenic in the solution to react with the iron to form FeAsO4. The process flow diagram is shown below. Figure 1 As shown, the main chemical reaction principle is as follows: 2H3AsO3 + O2 → 2H3AsO4; FeOOH + H₂O → Fe(OH)₃; H3AsO4+Fe(OH)3→FeAsO4↓+3H2O.

[0052] The specific steps are as follows: (1) White dust (containing 6.19 wt% Cu, 14.4 wt% Pb, 8.58 wt% Zn, 2.65 wt% Bi, 6.25 wt% As, and 0.78 wt% Fe) is uniformly fed into an acid leaching tank (white dust feed rate is 10 t / h) via a metering screw feeder, and mixed with sulfuric acid solution at a liquid-to-solid ratio of 2.5:1 (a liquid-to-solid ratio of (2~3):1 is acceptable) (mL / g). The sulfuric acid concentration in the resulting slurry is 45 g / L, and the total amount of sulfuric acid solution added is 26.75 m 3 / h. The reaction temperature is controlled within the range of 80-90℃ (85℃ in this example), the reaction time is 60min, and the final acid content is controlled not to exceed 5.5 g / L. After the reaction is completed, the material is cooled to below 70℃ and pumped to a filter press for filtration to separate lead-bismuth slag (containing 23.06wt.% Pb and 4.24wt.% Bi) and filtrate. The lead-bismuth slag is sold externally, and the filtrate is mixed with goethite slag returned from the iron removal process to form a slurry. The prepared slurry is then pumped to an autoclave via a relay pump.

[0053] (2) Control the reaction temperature of the autoclave at 160°C, maintain the pressure at 1.2 MPa, and set the oxygen partial pressure at 0.6 MPa, and the reaction lasts for 3 h. After the reaction is completed, the material is discharged into a flash tank to achieve rapid cooling and pressure reduction, then transferred to a conditioning tank for further cooling, and finally separated into liquid and solid by a thickener to obtain arsenic-iron leaching residue and high-pressure leaching solution; the produced arsenic-iron leaching residue (ferric arsenate residue, containing 28.89 wt% of Fe and 29.47 wt% of As) is stored.

[0054] (3) Iron powder (the amount of iron powder added is 0.55 t / h, and the iron content of the iron powder is 98.50 wt%) is added to replace copper in the high-pressure leaching solution, the temperature is controlled at 70-75°C (72°C in this example), the reaction time is 45 min, and after the reaction is completed, the filter residue and the copper deposition solution are obtained by liquid-solid separation; the filter residue is sponge copper (containing 98.58 wt% of Cu) and is sold externally; (4) Steel plant soot (containing 2.56 wt% of Fe, 0.50 wt% of As, and 62 wt% of Zn, and the amount of air introduced is 1.09 t / h) and oxygen-enriched air (the amount of air introduced is 100 m 3 / h, and the oxygen concentration in the oxygen-enriched air can be 35-40 v%, and in this example, it is about 38 v%) are added to the copper deposition solution, stirring is started, the reaction time is 5 h, the final liquid iron content is controlled at ≤2 g / L, the final pH is 5-5.4, and after the reaction is completed, the goethite residue and the iron-removed solution are obtained by liquid-solid separation. The goethite residue is returned to the slurry tank before the autoclave and is pumped into the autoclave by a booster pump; and the iron-removed solution (containing 1.84 g / L of Fe, 0.18 g / L of As, and 49.09 g / L of Zn) is further purified and sold externally or used to produce zinc sulfate heptahydrate products.

[0055] The compositions in the separated lead-bismuth residue, ferric arsenate residue, sponge copper, and iron-removed solution are detected, the generated amounts are counted, and the copper recovery rate, zinc leaching rate, and arsenic removal rate are calculated.

[0056] Table 1

[0057] The results are shown in Table 1. As can be seen from the table, the copper recovery rate is 95.38%, the zinc leaching rate is 98.33%, and the arsenic removal rate is 95.55%.

[0058] Example 2 This example provides a method for treating copper-containing high-arsenic hazardous waste, and the specific steps are as follows: The specific steps are as follows: (1) The white fume dust (containing 5.25 wt% of Cu, 14.40 wt% of Pb, 8.59 wt% of Zn, 2.65 wt% of Bi, 6.54 wt% of As, 0.26 wt% of Fe) is uniformly fed into the acid leaching tank through the metering screw feeder (the white fume dust input amount is 10 t / h) and mixed with the sulfuric acid solution at a liquid-solid ratio of 2.5:1 (the solid-liquid ratio can be (2-3):1) (mL / g). The sulfuric acid concentration in the obtained slurry is 45 g / L, and the total amount of the added sulfuric acid solution is 22.88 m 3 / h. The reaction temperature is controlled in the range of 80-90°C (85°C in this embodiment), the reaction time is 60 min, the final acid content is controlled to be not more than 5.5 g / L, after the reaction is completed, the material is cooled to below 70°C, pumped to the filter press for pressure filtration treatment, and the lead bismuth residue (containing Pb 22.55 wt.%, containing Bi 4.15 wt.%) and the filtrate are separated. The lead bismuth residue is sold, and the filtrate is mixed with the goethite residue returned from the iron removal process to adjust the slurry, and the adjusted slurry is delivered to the autoclave by the relay pump.

[0059] (2) The reaction temperature of the autoclave is controlled at 160°C, the pressure is maintained at 1.2 MPa, the oxygen partial pressure is set to 0.6 MPa, and the reaction lasts for 3 h. After the reaction is completed, the material is discharged into the flash tank to realize rapid cooling and pressure reduction, then transferred to the adjusting tank for further cooling, and finally separated by the thickener to obtain the arsenic-iron leaching residue and the high-pressure leaching liquid; the produced arsenic-iron leaching residue (ferric arsenate residue, containing Fe 28.01 wt.%, containing As 34.61 wt.%) is stored.

[0060] (3) Iron powder (the iron powder (added amount is 0.47 t / h, the iron content of the iron powder is 98.50 wt%) is added in an amount of 1.05 times the copper molar amount) is added to replace the copper, the temperature is controlled at 70-75°C (72°C in this embodiment), the reaction time is 45 min, and after the reaction is completed, the filter residue and the copper deposition liquid are obtained by liquid-solid separation; the filter residue is sponge copper (containing Cu 98.50 wt.%), which is sold; (4) The copper deposition liquid is added with steel plant soot (containing 8.12 wt% of Fe, 0.49 wt% of As, 61.90 wt% of Zn, the input amount is 0.89 t / h) and oxygen-enriched air (the input amount is 100 m 3 / h, the oxygen concentration in the oxygen-rich air is 35-40v%, and in this embodiment, it is about 38v%), the stirring is started, the reaction time is 5 hours, the final liquid iron content is controlled to be less than or equal to 2g / L, the final pH is 5-5.4, after the reaction is completed, the goethite slag and the iron-removed liquid are obtained through liquid-solid separation. The goethite slag is returned to the slurry tank in front of the kettle and is pumped into the autoclave by a booster pump; and the iron-removed liquid (containing Fe 1.84g / L, As 0.17g / L, and Zn 51.47g / L) is subjected to deep impurity removal and is sold or used to produce zinc sulfate heptahydrate products.

[0061] The components in the separated lead-bismuth slag, iron arsenate slag, sponge copper, and iron-removed liquid are detected, the generated amount is counted, and the copper recovery rate, zinc leaching rate, and arsenic removal rate are calculated.

[0062] Table 2

[0063] The results are shown in Table 2. As can be seen from the table, the copper recovery rate is 90.24%, the zinc leaching rate is 99.01%, and the arsenic removal rate is 95.15%.

[0064] Comparative Example 1 This example provides a method for treating copper-containing high-arsenic hazardous waste. The difference between this example and the steps of Example 1 is that the initial concentration of the white smoke dust and sulfuric acid mixed slurry is 55g / L, and the final acid leaching liquid is controlled to be 10.13g / L.

[0065] The components in the separated lead-bismuth slag, iron arsenate slag, sponge copper, and iron-removed liquid are detected, the generated amount is counted, and the copper recovery rate, zinc leaching rate, and arsenic removal rate are calculated.

[0066] The slag rate of iron arsenate (accounting for white smoke dust) is 21.06%, the arsenic output rate is 95.39%, the copper recovery rate is 95.34%, and the high-acid leaching has little effect on the copper recovery rate and the arsenic removal rate.

[0067] The above embodiments of the present application are described in detail in combination with the examples, but the present application is not limited to the above examples. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the purpose of the present application.

Claims

1. A method for treating hazardous waste containing high levels of copper and arsenic, characterized in that, Includes the following steps: (1) After acid leaching of white smoke dust, solid-liquid separation is performed to obtain acid leaching residue and acid leaching solution; (2) Add goethite slag to the acid leaching solution to carry out the first reaction, and obtain arsenic iron leaching residue and the first reaction solution; (3) Add iron powder to the first reaction solution to carry out a second reaction, and obtain copper slag and a second reaction solution; (4) After adding steel plant ash and oxidant to the second reaction solution to carry out the third reaction, goethite slag and iron-removed liquid are obtained.

2. The method according to claim 1, characterized in that, The white smoke dust comprises the following components by mass percentage: 2-8 wt% Cu, 5-20 wt% Pb, 2-15 wt% Zn, 1-5 wt% Bi, 4-15 wt% As, and 0.1-3 wt% Fe.

3. The method according to claim 1, characterized in that, The acid solution used in the acid leaching is a solution containing sulfuric acid; And / or, the acid leaching treatment is performed at a temperature of 80-90°C; And / or, the acid leaching treatment time is 0.5 h-2 h; And / or, the final acid concentration of the acid leaching treatment is 2 g / L-7 g / L.

4. The method according to claim 1, characterized in that, The first reaction was carried out in an autoclave; And / or, the conditions for the first reaction are: temperature of 150-170℃, pressure of 1-1.4MPa, and oxygen partial pressure of 0.4-0.8MPa; And / or, the reaction time of the first reaction is 2-4 hours.

5. The method according to claim 1, characterized in that, The temperature of the second reaction is 70-75℃; And / or, the second reaction takes 30-55 minutes.

6. The method according to claim 1, characterized in that, The steel plant ash comprises the following components by weight percentage: 1-15 wt% Fe, 0.1-1 wt% As, and 50-70 wt% Zn.

7. The method according to claim 1, characterized in that, The third reaction takes 4-6 hours; And / or, the endpoint of the third reaction is at a pH of 5.0-5.

4.

8. The method according to claim 1, characterized in that, The iron content in the liquid after iron removal is ≤2g / L; And / or, the oxidant includes oxygen-enriched air.

9. The application of the method according to any one of claims 1 to 8 in any of the following: 1) Recover valuable metals from white smoke dust; 2) Arsenic removal from white smoke dust.

10. The application according to claim 9, characterized in that, The valuable metals include lead, bismuth, arsenic, iron, copper, and zinc.

Images