Process for comprehensively recovering valuable metals from tin-containing soot

Abstract

The invention provides a process for comprehensively recovering valuable metals from tin-containing soot, which comprises the following steps: taking the tin-containing soot, carrying out first-stage high-pressure oxygen leaching to obtain a first-stage leaching solution and first-stage leaching residues, and recovering lead, bismuth and tin valuable metals from the first-stage leaching residues; the tin-containing soot and the first-section leachate are subjected to second-section high-pressure oxygen leaching, second-section leachate and second-section leaching residues are obtained, and the second-section leaching residues are returned to the first-section high-pressure oxygen leaching; copper recovery is conducted on the second-section leaching solution, and copper deposition post-solution and copper sulfide slag are obtained; the copper sulphide slag is subjected to alkali washing to obtain alkali washing liquid and copper sulphide; reacting the copper-deposited solution with sulfur dioxide, and then reacting with hydrogen sulfide to obtain an arsenic-deposited solution and arsenic sulfide slag; and the arsenic sulfide slag is subjected to copper replacement and arsenic replacement, and arsenic trioxide and copper sulfide are recycled. According to the method, valuable metals such as arsenic, copper, bismuth and tin in the tin-containing soot are separated and comprehensively recycled one by one, the recycling efficiency is high, the cost is low, the hazardous waste tin-containing soot is effectively treated, meanwhile, the wastewater yield is small, almost no waste residue is generated, and secondary pollution to the environment is avoided.

Description

Technical Field

[0001] The invention relates to the technical field of hazardous waste treatment, and in particular to a process for comprehensively recovering valuable metals from tin-containing smoke ash. Background Art

[0002] In the pyrometallurgical process of tin raw materials (such as pyrometallurgical smelting of tin concentrate and pyrometallurgical smelting of tin-containing copper ore), tin-containing ash will be produced. In addition to tin, tin-containing ash often contains various valuable metals such as arsenic, copper, bismuth, antimony, etc. If these ash are not handled in time or improperly handled, they will flow into water or soil and cause great pollution to the environment. At the same time, these metals are also indispensable raw materials in the physical manufacturing industry. Therefore, properly handling these heavy metal ash is one of the focuses of current work. At present, although various recycling processes have appeared, due to improper handling, the recycling efficiency is very low, and the quality of the valuable metals recovered is low. In addition, waste water, waste residue, etc. will also be produced, which will cause secondary pollution to the environment, and further treatment is required, which is very troublesome and greatly increases the cost. Summary of the invention

[0003] In view of this, the present invention proposes a process for comprehensively recovering valuable metals such as arsenic, copper, and zinc from tin-containing soot. The present invention separates and recovers valuable metals such as arsenic, copper, bismuth, and tin in the tin-containing soot one by one, and comprehensively recovers valuable metals such as arsenic, copper, bismuth, and tin therein. In the entire production process, no wastewater is discharged, and no worthless hazardous waste is generated, which is conducive to the comprehensive treatment of hazardous wastes.

[0004] The technical solution of the present invention is achieved in this way:

[0005] A process for comprehensive recovery of valuable metals from tin-containing soot comprises the following steps:

[0006] (1) One-stage high-pressure oxygen leaching: The tin-containing ash is subjected to one-stage high-pressure oxygen leaching with sulfuric acid, water and oxygen to obtain a first-stage leaching solution and a first-stage leaching residue, which is then sent to pyrometallurgical smelting to recover valuable metals such as lead, bismuth and tin;

[0007] (2) Two-stage high-pressure oxygen leaching: The tin-containing fly ash is subjected to two-stage high-pressure oxygen leaching with the first-stage leaching solution and oxygen. After the reaction is completed, a second-stage leaching solution and a second-stage leaching residue are obtained, and the second-stage leaching residue is returned to the first-stage high-pressure oxygen leaching process in step (1);

[0008] (3) Copper recovery: hydrogen sulfide gas is introduced into the second-stage leaching solution for stirring and reaction, and filtered to obtain copper precipitation liquid and copper sulfide slag;

[0009] (4) Alkaline washing of copper sulfide slag: stirring the copper sulfide slag and sodium hydroxide solution to react to obtain an alkaline washing solution and copper sulfide;

[0010] (5) Sulfur dioxide reduction: adding sulfur dioxide to the copper precipitation solution and stirring to react to obtain a sulfur dioxide reduced solution;

[0011] (6) Arsenic precipitation: adding hydrogen sulfide to the sulfur dioxide reduction solution and continuing to stir the reaction, filtering to obtain the arsenic precipitation solution and arsenic sulfide slag;

[0012] (7) Copper replacement: adding the second-stage leaching solution to the arsenic sulfide slag for reaction, filtering, and obtaining replacement slag and arsenic-containing solution; recovering arsenic trioxide from the arsenic-containing solution;

[0013] (8) Arsenic replacement: adding the second-stage leaching solution to the replacement slag for reaction, filtering, and obtaining arsenic replacement solution and copper sulfide slag; the copper sulfide slag is returned to the alkaline washing step to obtain a copper sulfide product.

[0014] Furthermore, in step (1), the solid-liquid g / mL ratio of the tin-containing ash to water is 1:3-4; the amount of sulfuric acid added is 30%-40% of the weight of the tin-containing ash; the leaching temperature of the one-stage high-pressure oxygen leaching is 120-150° C., the leaching oxygen pressure is 0.6-0.8 MPa, and the leaching time is 1.5-2.0 h.

[0015] Furthermore, the sulfuric acid is industrial sulfuric acid with a mass fraction of 98%.

[0016] Furthermore, in step (2), tin-containing fly ash is used as a regulator to ensure that the pH at the end of the reaction is 2.0-3.0; the leaching temperature of the second stage high-pressure oxygen leaching is 120-150° C., the leaching oxygen pressure is 0.6-0.8 MPa, and the leaching time is 1.5-2.0 h.

[0017] Furthermore, in step (3), the amount of hydrogen sulfide added is 0.58-0.62 times the mass of copper in the solution, and the speed of hydrogen sulfide addition is 0.05-0.12 g / min; the reaction temperature is room temperature, and the stirring reaction is continued for 0.5-0.6 h after all the hydrogen sulfide is added.

[0018] Furthermore, in step (4), the concentration of the sodium hydroxide solution is 100 g / L-150 g / L; the solid-liquid ratio of the copper sulfide slag to the sodium hydroxide solution is g / mL≥4:1; the temperature of the stirring reaction is 85-95°C, and the reaction time is 2-3h.

[0019] Furthermore, in step (5), the mass of sulfur dioxide is 3.5-5.5 times the mass of arsenic in the solution, and the rate of introducing sulfur dioxide is 20-30 mL / min; the reaction temperature is room temperature, and the reaction is continued to be stirred for 0.5-0.6 h after all the sulfur dioxide is added.

[0020] Furthermore, in step (6), the amount of hydrogen sulfide added is 0.5-0.55 times the mass of arsenic in the liquid after sulfur dioxide reduction, the speed of hydrogen sulfide addition is 0.05-0.12 g / min, and after all the hydrogen sulfide is added, the stirring reaction is continued for 0.5-0.6 h.

[0021] Furthermore, in step (6), the arsenic precipitation liquid is returned to a high-pressure leaching process, and after repeated circulation, when the total non-sulfate salt content is greater than 100 g / L, it is sent to a wastewater treatment workshop, neutralized with copper sulfide slag alkaline washing liquid, and then continued to be treated.

[0022] Furthermore, in step (7), during the copper replacement reaction, the arsenic-copper mass ratio is controlled to be ≥ 0.8; the reaction temperature is 85-95° C., and the reaction time is 2.5-3 h.

[0023] Furthermore, in step (8), during the arsenic replacement reaction, the arsenic-copper mass ratio is controlled to be ≤0.6; the reaction temperature is 85-95° C., and the reaction time is 2.5-3 h.

[0024] The main chemical reaction equation of the process of the present invention is as follows:

[0025] As2O3+H2O=2HAsO2

[0026] As2O5+3H2O=2H3AsO4

[0027] 2HAsO2+O2=2HAsO3

[0028] CuO+H2SO4=CuSO4+H2O

[0029] CuSO4+H2S=CuS+H2SO4

[0030] As2S3+3Cu 2+ +6H2O=3CuS+2H3AsO3+6H +

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] (1) The present invention adopts a high-pressure oxygen leaching method, so that the tin in the tin-containing fly ash is not leached in a high-valent state, but remains in the leaching residue to be separated from copper and arsenic, thereby eliminating the volatilization of arsenic in the traditional oxidation roasting method and improving the recovery rate of arsenic and other valuable metals.

[0033] (2) The present invention adopts high-pressure oxygen leaching to leach arsenic in the tin-containing fly ash in a high-valent state, thereby reducing the precipitation of copper by hydrogen sulfide and significantly reducing the content of arsenic trisulfide (As2S3) in the copper sulfide slag.

[0034] (3) The present invention combines a first-stage high-pressure oxygen leaching and a second-stage high-pressure oxygen leaching, and controls the pH of the second-stage high-pressure oxygen leaching so that a small amount of antimony and bismuth entering the first-stage leaching solution re-enters the leaching slag, thereby ensuring the recovery rate of bismuth and antimony while also ensuring the quality of copper sulfide.

[0035] (4) For the arsenic sulfide precipitation slag, the traditional roasting method is not used to recover the arsenic in the form of arsenic trioxide. Instead, the copper in a certain amount of the second-stage leaching solution is completely replaced in the form of an excess of arsenic sulfide slag, so that the copper in this part of the second-stage leaching solution is completely replaced and becomes a relatively pure arsenic-containing solution. After filtering, the arsenic in the replaced slag is completely converted into copper sulfide slag with an excess of the second-stage copper-containing solution. In this way, the arsenic sulfide slag is converted into a relatively pure high-concentration arsenic-containing solution and copper sulfide slag without adding any auxiliary materials, and most of the sulfur in the hydrogen sulfide in the whole system is fully converted into copper sulfide, thereby converting it into arsenic trioxide copper sulfide products at low cost and high recovery.

[0036] (5) The process of the present invention allows copper and arsenic in tin-containing fly ash to be recovered in the form of copper sulfide products and arsenic trioxide products. Other metals can be recovered by entering the pyrometallurgical system using conventional processes to continue to recover lead, tin and bismuth. The entire process not only disposes of hazardous waste tin-containing fly ash, but also generates relatively small amounts of wastewater, almost no waste residue, and does not cause secondary environmental pollution.

[0037] (6) Since the entire process system of the present invention only uses cheap reagents such as sulfuric acid, hydrogen sulfide, and sulfur dioxide, the process is relatively simple and the production cost of the entire system is low. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 The process flow chart of the invention for recovering valuable metals. DETAILED DESCRIPTION

[0039] In order to better understand the technical content of the present invention, specific embodiments are provided below to further illustrate the present invention.

[0040] Unless otherwise specified, the experimental methods used in the embodiments of the present invention are all conventional methods.

[0041] Unless otherwise specified, the materials, reagents, etc. used in the embodiments of the present invention can be obtained from commercial sources.

[0042] The valuable metal recovery process flow chart of the embodiment of the present invention is as follows: Figure 1 shown.

[0043] Example 1

[0044] (1) Take 100 g of tin-containing fly ash, which contains 6.22% arsenic, 13.11% copper, 5.32% tin, 20.39% lead, 3.17% bismuth, and 2.13% antimony;

[0045] (2) One-stage high-pressure oxygen leaching: 300 mL of water and 18 mL of 98% sulfuric acid were added to the tin-containing fly ash and mixed well, and then oxygen was introduced. One-stage high-pressure oxygen leaching was carried out at a temperature of 130° C. and a leaching oxygen pressure of 0.65 MPa. The leaching time was 2.0 h. After the reaction was completed, 305 mL of the first-stage leaching liquid and 66.32 g of the first-stage leaching residue were obtained by filtration;

[0046] (3) Second stage high pressure oxygen leaching: Add tin-containing soot to the first stage leaching solution in step (2), mix well, introduce oxygen, and carry out second stage high pressure oxygen leaching at a temperature of 120° C. and a leaching oxygen pressure of 0.6 MPa. The leaching time is 1.5 h. A total of 12.12 g of tin-containing soot is added. The pH at the end point of the reaction is controlled to be between 2.0 and 3.0 to precipitate antimony and bismuth in the first stage leaching solution. After the reaction is completed, 302 mL of second stage leaching solution and second stage leaching residue are obtained by filtration. The second stage leaching residue is returned to the first stage high pressure oxygen leaching process in step (2);

[0047] (4) Copper recovery: Add hydrogen sulfide to the second-stage leaching solution, the amount of hydrogen sulfide added is 8.67 g, the speed of hydrogen sulfide addition is 0.08 g / min, and the reaction is carried out at room temperature. After all the hydrogen sulfide is added, continue to stir and react for 0.5 h, and then filter to obtain the copper precipitation liquid and copper sulfide slag;

[0048] (5) Alkaline washing of copper sulfide slag: 120 mL of a sodium hydroxide solution with a concentration of 120 g / L was added to the copper sulfide slag, and the mixture was reacted at 95° C. for 3 h. After the reaction was completed, 21.69 g of an alkaline washing liquid and a copper sulfide product were obtained by filtration, wherein the content of the copper sulfide was 99.32% and the direct copper recovery rate was 97.69%. The copper sulfide alkaline washing liquid was used to neutralize the acidic wastewater of the open circuit;

[0049] (6) Sulfur dioxide reduction: 9.5 L of sulfur dioxide was introduced into the copper precipitation solution at a rate of 20 mL / min, and the reaction was carried out at room temperature. After all the sulfur dioxide was added, the reaction was continued with stirring for 0.5 h to obtain a sulfur dioxide reduced solution;

[0050] (7) Arsenic precipitation: add 3.62 g of hydrogen sulfide to the sulfur dioxide reduced solution at a rate of 0.08 g / min. After all the hydrogen sulfide is added, continue stirring and reacting for 0.5 h, then filter to obtain the arsenic precipitation solution and arsenic sulfide slag;

[0051] (8) Copper replacement: 170 mL of the second-stage leaching solution was added to the arsenic sulfide slag and reacted at a temperature of 95° C. for 3 h. The second-stage leaching solution was prepared under the same conditions as the second-stage leaching solution in step (3). After the reaction was completed, the replacement slag and the arsenic-containing solution were filtered out. The arsenic-containing solution was subjected to reduction-three-effect crystallization to obtain 8.53 g of arsenic trioxide product, which contained 74.98% arsenic and had an arsenic recovery rate of 98.12% (calculated based on the arsenic leaching rate and the three-effect crystallization loss rate);

[0052] (9) Arsenic replacement: 200 mL of the second-stage leaching solution was added to the arsenic sulfide slag and reacted at 95° C. for 3 h. The second-stage leaching solution and the second-stage leaching solution in step (3) were prepared under the same conditions. After the reaction was completed, the arsenic replacement solution and copper sulfide slag were obtained by filtration. The copper sulfide slag was returned to the alkaline washing step to obtain a copper sulfide product containing 99.12% copper sulfide.

[0053] Example 2

[0054] (1) Take 100 g of tin-containing fly ash, which contains 4.18% arsenic, 11.28% copper, 9.19% tin, 15.12% lead, 2.26% bismuth and 2.58% antimony.

[0055] (2) One-stage high-pressure oxygen leaching: 300 mL of water and 17 mL of 98% sulfuric acid were added to the fly ash and mixed well. Then, oxygen was introduced and one-stage high-pressure oxygen leaching was carried out at a temperature of 120°C and a leaching oxygen pressure of 0.6 MPa. The leaching time was 2.0 h. After the reaction was completed, 300 mL of the first-stage leaching liquid and 68.19 g of the first-stage leaching residue were obtained by filtration.

[0056] (3) One-stage high-pressure oxygen leaching: Add tin-containing soot to the first-stage leaching solution in step (2), mix well, introduce oxygen, and carry out two-stage high-pressure oxygen leaching at a temperature of 120° C. and a leaching oxygen pressure of 0.6 MPa. The leaching time is 1.5 h. A total of 14.16 g of tin-containing soot is added. The pH at the end point of the reaction is controlled to be between 2.0 and 3.0 to precipitate antimony and bismuth in the first-stage leaching solution. After the reaction is completed, 298 mL of the second-stage leaching solution and second-stage leaching residue are obtained by filtration. The second-stage leaching residue is returned to the first-stage high-pressure oxygen leaching process in step (2);

[0057] (4) Copper recovery: Add hydrogen sulfide to the second-stage leaching solution, the amount of hydrogen sulfide added is 7.72 g, the speed of hydrogen sulfide addition is 0.10 g / min, and the reaction is carried out at room temperature. After all the hydrogen sulfide is added, continue to stir and react for 0.5 h, and then filter to obtain the copper precipitation liquid and copper sulfide slag;

[0058] (5) Alkali washing of copper sulfide slag: 100 mL of a sodium hydroxide solution with a concentration of 130 g / L was added to the copper sulfide slag, and the mixture was reacted at 95° C. for 3 h. After the reaction was completed, 19.80 g of an alkaline washing liquid and a copper sulfide product were obtained by filtration. The product contained 99.20% copper sulfide and had a direct copper recovery rate of 98.33%. The copper sulfide alkaline washing liquid was used to neutralize the acidic wastewater of the open circuit.

[0059] (6) Sulfur dioxide reduction: 6.4 L of sulfur dioxide was introduced into the copper precipitation solution at a rate of 25 mL / min, and the reaction was carried out at room temperature. After all the sulfur dioxide was added, the reaction was continued with stirring for 0.5 h to obtain a sulfur dioxide reduced solution;

[0060] (7) Arsenic precipitation: add 2.53 g of hydrogen sulfide to the sulfur dioxide reduced solution at a rate of 0.01 g / min. After all the hydrogen sulfide is added, continue stirring and reacting for 0.5 h, then filter to obtain the arsenic precipitation solution and arsenic sulfide slag;

[0061] (8) Copper replacement: 100 mL of the second-stage leaching solution was added to the arsenic sulfide slag and reacted at a temperature of 95° C. for 3 h. The second-stage leaching solution and the second-stage leaching solution in step (3) were prepared under the same conditions. After the reaction was completed, the replacement slag and the arsenic-containing solution were filtered out. The arsenic-containing solution was reduced and crystallized by three-effect crystallization to obtain 6.51 g of arsenic trioxide product, which contained 74.99% arsenic and had an arsenic recovery rate of 97.43% (calculated based on the arsenic leaching rate and the three-effect crystallization loss rate);

[0062] (9) Arsenic replacement: 150 mL of the second-stage leaching solution was added to the arsenic sulfide slag and reacted at 95° C. for 3 h. The second-stage leaching solution and the second-stage leaching solution in step (3) were prepared under the same conditions. After the reaction was completed, the arsenic replacement solution and copper sulfide slag were obtained by filtration. The copper sulfide slag was returned to the alkaline washing step to obtain a copper sulfide product containing 99.08% copper sulfide.

[0063] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A process for comprehensive recovery of valuable metals from tin-containing soot, characterized in that: The method comprises the following steps: (1) one-stage high-pressure oxygen leaching: taking tin-containing ash and sulfuric acid, water and oxygen for one-stage high-pressure oxygen leaching to obtain a first-stage leaching solution and a first-stage leaching residue, and the first-stage leaching residue is sent to pyrometallurgy to recover valuable metals such as lead, bismuth and tin; (2) Two-stage high-pressure oxygen leaching: The tin-containing fly ash is subjected to two-stage high-pressure oxygen leaching with the first-stage leaching solution and oxygen. After the reaction is completed, a second-stage leaching solution and a second-stage leaching residue are obtained, and the second-stage leaching residue is returned to the first-stage high-pressure oxygen leaching process in step (1); (3) Copper recovery: hydrogen sulfide gas is introduced into the second-stage leaching solution for stirring and reaction, and filtered to obtain copper precipitation liquid and copper sulfide slag; (4) Alkaline washing of copper sulfide slag: stirring the copper sulfide slag and sodium hydroxide solution to react to obtain an alkaline washing solution and copper sulfide; (5) Sulfur dioxide reduction: adding sulfur dioxide to the copper precipitation solution and stirring to react to obtain a sulfur dioxide reduced solution; (6) Arsenic precipitation: adding hydrogen sulfide to the sulfur dioxide reduction solution and continuing to stir and react, filtering to obtain arsenic precipitation solution and arsenic sulfide slag; (7) Copper replacement: adding the second-stage leaching solution to the arsenic sulfide slag for reaction, filtering, and obtaining replacement slag and arsenic-containing solution; recovering arsenic trioxide from the arsenic-containing solution; (8) Arsenic replacement: adding the second-stage leaching solution to the replacement slag for reaction, filtering, and obtaining arsenic replacement solution and copper sulfide slag; the copper sulfide slag is returned to the alkaline washing step to obtain a copper sulfide product.

2. The process for comprehensive recovery of valuable metals from tin-containing fly ash according to claim 1, characterized in that: In step (1), the solid-liquid g / mL ratio of the tin-containing ash to water is 1:3-4; the amount of sulfuric acid added is 30-40% of the weight of the tin-containing ash; the leaching temperature of the one-stage high-pressure oxygen leaching is 120-150° C., the leaching oxygen pressure is 0.6-0.8 MPa, and the leaching time is 1.5-2.0 h.

3. The process for comprehensive recovery of valuable metals from tin-containing fly ash according to claim 1, characterized in that: In step (2), tin-containing fly ash is used as a regulator to ensure that the pH at the end of the reaction is 2.0-3.0; the leaching temperature of the second stage high-pressure oxygen leaching is 120-150° C., the leaching oxygen pressure is 0.6-0.8 MPa, and the leaching time is 1.5-2.0 h.

4. The process for comprehensive recovery of valuable metals from tin-containing fly ash according to claim 1, characterized in that: In step (3), the amount of hydrogen sulfide added is 0.58-0.62 times the mass of copper in the solution, and the speed of hydrogen sulfide addition is 0.05-0.12 g / min; the reaction temperature is room temperature, and the stirring reaction is continued for 0.5-0.6 h after all the hydrogen sulfide is added.

5. The process for comprehensive recovery of valuable metals from tin-containing fly ash according to claim 1, characterized in that: In step (4), the concentration of the sodium hydroxide solution is 100 g / L-150 g / L; the solid-liquid ratio of the copper sulfide slag to the sodium hydroxide solution is g / mL≥4:1; the temperature of the stirring reaction is 85-95° C., and the reaction time is 2-3 h.

6. The process for comprehensive recovery of valuable metals from tin-containing fly ash according to claim 1, characterized in that: In step (5), the mass of sulfur dioxide is 3.5-5.5 times the mass of arsenic in the solution, and the rate of introducing sulfur dioxide is 20-30 mL / min; the reaction temperature is room temperature, and the stirring reaction is continued for 0.5-0.6 h after all the sulfur dioxide is added.

7. The process for comprehensive recovery of valuable metals from tin-containing fly ash according to claim 1, characterized in that: In step (6), the amount of hydrogen sulfide added is 0.5-0.55 times the mass of arsenic in the liquid after sulfur dioxide reduction, the speed of hydrogen sulfide addition is 0.05-0.12 g / min, and the stirring reaction is continued for 0.5-0.6 h after all the hydrogen sulfide is added.

8. The process for comprehensive recovery of valuable metals from tin-containing fly ash according to claim 1, characterized in that: In step (6), the arsenic precipitation liquid is returned to a high-pressure leaching process. After repeated circulation, when the total non-sulfate salt content is greater than 100 g / L, it is sent to a wastewater treatment workshop and neutralized with copper sulfide slag alkaline washing liquid before continuing wastewater treatment.

9. The process for comprehensive recovery of valuable metals from tin-containing fly ash according to claim 1, characterized in that: In step (7), during the copper replacement reaction, the arsenic-copper mass ratio is controlled to be ≥ 0.8; the reaction temperature is 85-95° C. and the reaction time is 2.5-3 h.

10. The process for comprehensive recovery of valuable metals from tin-containing fly ash according to claim 1, characterized in that: In step (8), during the arsenic replacement reaction, the arsenic-copper mass ratio is controlled to be ≤0.6; the reaction temperature is 85-95° C., and the reaction time is 2.5-3 h.

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