Cooperative treatment and comprehensive recovery method for precious metal smelting wastewater

Abstract

The invention discloses a precious metal smelting wastewater co-treatment comprehensive recovery method which comprises the following steps: (1) neutralizing and precipitating bismuth: adding alkaline wastewater into acid wastewater for neutralizing to obtain bismuth concentrate and neutralized liquid, (2) vulcanizing and precipitating copper: continuously adding alkaline wastewater 8 into the neutralized liquid, adding sodium sulfide to obtain copper precipitation slag and vulcanized liquid, and (3) cooling and crystallizing. And (4) concentrating the liquid after primary crystallization, so as to obtain sodium sulfite, sodium chloride and condensed water. The sodium chloride solution is added into the liquid after the primary crystallization, so that the concentration of chloride ions is reduced to be lower than 10 DEG C, and the sodium sulfite crystal and the liquid after the primary crystallization are obtained. Through collocation treatment of acidic wastewater and alkaline wastewater generated in the precious metal smelting process, stepped separation and recovery of valuable metals in the wastewater are realized, and the wastewater treatment cost is saved.

Description

Technical Field

[0001] The present invention relates to the technical field of precious metal smelting wastewater treatment, and particularly to a comprehensive recovery method for co - treating precious metal smelting wastewater. Background Technique

[0002] Precious metal elements have characteristics such as high value, high stability, and high melting point, and are widely used in the manufacture of ultra - precision electronic components in the electronics industry. Precious metal elements mainly come from the by - production of heavy non - ferrous metal smelting. They are enriched in anode slime during the smelting processes of heavy non - ferrous metals such as lead, copper, and nickel. Recovering precious metal elements from heavy non - ferrous metal smelting has become a profit growth point for enterprises.

[0003] Traditional methods for recovering precious metals from non - ferrous smelting by - products mainly include pyrometallurgical processes, hydrometallurgical processes, and pyrometallurgy - hydrometallurgy combined processes. The pyrometallurgical process has a large processing capacity, strong adaptability to raw materials, and high precious metal recovery rate, but it has high energy consumption, serious environmental pollution, and a long production cycle. The hydrometallurgical process has advantages such as low energy consumption, short process, good comprehensive utilization economic benefits, and less environmental pollution. However, it has a large amount of wastewater, serious equipment corrosion, and high production costs. The pyrometallurgy - hydrometallurgy combined process can give full play to the advantages of pyrometallurgy in enrichment and the advantages of hydrometallurgy in separation and purification. Wastewater generated from precious metal smelting by any process has characteristics such as high acid, high chlorine, and high sodium salt, and the wastewater also contains valuable metal elements with relatively high economic value, which has always been an important source for comprehensive recovery.

[0004] The high - acid, high - chlorine, and high - sodium - salt wastewater generated from precious metal smelting has problems such as difficult treatment and high costs. Therefore, how to effectively co - treat precious metal smelting wastewater and conduct comprehensive recovery is a technical problem that needs to be urgently solved by those skilled in the art. Summary of the Invention

[0005] In view of this, the present invention provides a comprehensive recovery method for co - treating precious metal smelting wastewater. The wastewater is strong - acid wastewater containing chloride ions and sulfate ions, weak - acid wastewater containing sulfate ions, and alkaline wastewater containing sulfite ions.

[0006] To achieve the above object, the present invention adopts the following technical scheme:

[0007] A comprehensive recovery method for co - treating precious metal smelting wastewater includes the following steps:

[0008] (1) Pump the strong - acid wastewater into a reaction kettle, add alkaline wastewater at a rate of 50 L / min, stir and react until pH = 2 - 3, filter to obtain bismuth concentrate and neutralized liquid, and send the bismuth concentrate to the bismuth recovery process for treatment;

[0009] (2) Pump the neutralized solution obtained in step (1) and the weak acid wastewater into a reaction kettle, mix them according to the volume ratio, stir evenly, then add alkaline wastewater or sodium hydroxide at a rate of 50 L / min until the pH is 6 - 8, and then add sodium sulfide for sulfide precipitation. Filter to obtain copper slag and post-sulfide solution. The copper slag is returned to the copper smelting pyrometallurgy system for treatment;

[0010] (3) Heat the post-sulfide solution obtained in step (2) to 40 - 60 °C, add sodium chloride to control the mass concentration of sodium chloride in the solution to 18% - 20%, stir and dissolve, then quickly cool to below 10 °C to precipitate sodium sulfite crystals, and perform solid-liquid separation to obtain sodium sulfite and the primary crystallization solution;

[0011] (4) Feed the primary crystallization solution obtained in step (3) into a multi-effect evaporator for evaporation. Continuously precipitate sodium sulfite and sodium chloride crystals to obtain a concentrated solution. Add post-sulfide solution to the concentrated solution, repeat steps (3) and (4), continuously precipitate sodium sulfite crystals, and when the sodium chloride solution reaches saturation, perform solid-liquid separation to obtain a saturated sodium chloride solution and evaporation condensate;

[0012] (5) Evaporate and concentrate the saturated sodium chloride solution obtained in step (4) to obtain sodium chloride crystals and evaporation condensate. The sodium chloride is sent to copper anode slime chlorination as a gold separation reagent, and the condensate is sent to the copper anode slime smelting hydrometallurgy system.

[0013] The strong acid wastewater contains the following components: hydrogen ions 3 - 5 g / L, copper 5 - 10 g / L, silver 30 - 60 mg / L, bismuth 15 - 20 g / L, gold 0.1 mg / L, tellurium 3 - 5 g / L, chloride ions 70 - 100 g / L;

[0014] The alkaline wastewater components are: silver 1 - 2 g / L, chloride ions 30 - 50 g / L, sodium sulfite 160 - 180 g / L.

[0015] The components of the weak acid wastewater are: copper 15 - 25 g / L, silver 10 - 20 mg / L, chloride ions 0.5 - 1 g / L, hydrogen ions 0.2 - 1 g / L.

[0016] The volume ratio of the neutralized solution to the weak acid wastewater is 1:1 - 1.5;

[0017] The mass ratio of sulfur in the sodium sulfide to copper ions in the solution is 2:1.

[0018] The addition amount of sodium chloride is such that the mass concentration of sodium chloride is 18 - 20%.

[0019] The evaporation temperature is 80 - 100 °C.

[0020] The sodium chloride is returned to step (3) for use without adding new sodium chloride, and is recycled in the system.

[0021] The beneficial effects of the present invention are as follows:

[0022] 1. Through the combined treatment of acidic wastewater and alkaline wastewater generated in the precious metal smelting process, the present invention realizes the cascade separation and recovery of valuable metals in the wastewater, saving the cost of wastewater treatment.

[0023] 2. The present invention utilizes different solubilities quickly to realize the regeneration and reuse of some reagents. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the comprehensive recovery process for the collaborative treatment of precious metal smelting wastewater of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0025] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0026] Example 1

[0027] A comprehensive recovery method for the collaborative treatment of precious metal smelting wastewater. In this example, the strong acid wastewater contains the following components: the main components are 3 g / L of hydrogen ions, 8 g / L of copper, 50 mg / L of silver, 20 g / L of bismuth, 0.1 mg / L of gold, 4 g / L of tellurium, and 100 g / L of chloride ions; the main components of the alkaline wastewater are 1.5 g / L of silver, 40 g / L of chloride ions, and 180 g / L of sodium sulfite; the components of the weak acid wastewater are: 20 g / L of copper, 10 mg / L of silver, 0.5 g / L of chloride ions, and 0.2 g / L of hydrogen ions.

[0028] (1) Pump the strong acid wastewater into the reaction kettle, add the alkaline wastewater at a rate of 50 L / min, stir and react. The pH at the end point of the reaction is 2.5. Filter to obtain bismuth concentrate and the neutralized liquid. Analyze that the main components of the bismuth concentrate are 65% of bismuth, 0.2% of copper, 1.2% of tellurium, and 0.08% of silver. The bismuth recovery rate in the bismuth neutralization section is 99.1%, the copper recovery rate is 1.8%, the tellurium recovery rate is 15%, and the silver recovery rate is 21%. The bismuth concentrate is sent to the bismuth recovery process for treatment;

[0029] (2) Pump the neutralized solution and the weak acid wastewater obtained into the reaction kettle, mix them in a volume ratio of 1:1, stir evenly, then add the alkaline wastewater at a rate of 50 L / min. When the pH at the reaction end point is 6, add sodium sulfide for sulfide precipitation. After filtration, copper slag and sulfided solution are obtained. The main components of the copper slag after precipitation analysis are 0.25% bismuth, 24.5% copper, 4.2% tellurium, and 0.11% silver. The bismuth recovery rate in the copper sulfide precipitation stage is 98.5%, the copper recovery rate is 99.8%, the tellurium recovery rate is 99.2%, and the silver recovery rate is 99.7%. The copper slag is returned to the copper smelting pyrometallurgy system for treatment;

[0030] (3) Heat the sulfided solution obtained to 50 °C, add sodium chloride to control the mass concentration of sodium chloride in the solution to 18%, stir and dissolve it, then quickly cool it to below 8 °C to precipitate sodium sulfite crystals, and perform solid-liquid separation to obtain sodium sulfite and the first crystallization solution;

[0031] (4) Feed the first crystallization solution obtained into a multi-effect evaporator for evaporation. Sodium sulfite and sodium chloride crystals are continuously precipitated to obtain a concentrated solution. Add the sulfided solution to the concentrated solution, and repeat steps (3) and (4). Sodium sulfite crystals are continuously precipitated. After concentration until the sodium chloride solution reaches saturation, perform solid-liquid separation to obtain a saturated sodium chloride solution and evaporation condensate;

[0032] (5) Evaporate and concentrate the saturated sodium chloride solution obtained to obtain sodium chloride crystals and evaporation condensate. The sodium chloride is sent to the copper anode slime chlorination as a gold separation reagent, and the condensate is sent to the copper anode slime smelting wet process system.

[0033] Example 2

[0034] A comprehensive recovery method for co-treatment of precious metal smelting wastewater. In this example, the strong acid wastewater contains the following components: the main components are 4 g / L hydrogen ions, 10 g / L copper, 60 mg / L silver, 15 g / L bismuth, 0.1 mg / L gold, 3 g / L tellurium, and 90 g / L chloride ions; the main components of the alkaline wastewater are 1 g / L silver, 50 g / L chloride ions, and 170 g / L sodium sulfite; the components of the weak acid wastewater are: 25 g / L copper, 15 mg / L silver, 0.8 g / L chloride ions, and 0.4 g / L hydrogen ions.

[0035] (1) Pump the strong acid wastewater into the reaction kettle, add the alkaline wastewater at a rate of 50 L / min, stir and react. When the pH at the reaction end point is 3, filter to obtain bismuth concentrate and the neutralized solution. The main components of the bismuth concentrate after analysis are 67% bismuth, 0.17% copper, 1.3% tellurium, and 0.06% silver. The bismuth recovery rate in the bismuth neutralization precipitation stage is 99.5%, the copper recovery rate is 1.5%, the tellurium recovery rate is 17%, and the silver recovery rate is 19%. The bismuth concentrate is sent to the bismuth recovery process for treatment;

[0036] (2) Pump the obtained neutralized solution and weak acid wastewater into a reaction kettle, mix them in a volume ratio of 1:1.5, stir evenly, then add sodium hydroxide solution at a rate of 50 L / min until the pH at the reaction end point is 8. Then add sodium sulfide for sulfide precipitation, and filter to obtain copper slag and sulfided solution. Analyze that the main components of the copper slag are 0.21% bismuth, 25.5% copper, 4.1% tellurium, and 0.13% silver. The bismuth recovery rate in the copper sulfide precipitation stage is 99.1%, the copper recovery rate is 99.7%, the tellurium recovery rate is 99.4%, and the silver recovery rate is 99.5%. The copper slag is returned to the copper smelting pyrometallurgical system for treatment;

[0037] (3) Heat the obtained sulfided solution to 60 °C, add sodium chloride to control the mass concentration of sodium chloride in the solution to 20%, stir and dissolve it, and then quickly cool it to below 6 °C to precipitate sodium sulfite crystals. Perform solid-liquid separation to obtain sodium sulfite and primary crystallization solution;

[0038] (4) Feed the obtained primary crystallization solution into a multi-effect evaporator for evaporation. Continuously precipitate sodium sulfite and sodium chloride crystals to obtain a concentrated solution. Add sulfided solution to the concentrated solution, and repeat steps (3) and (4). Continuously precipitate sodium sulfite crystals. After concentrating until the sodium chloride solution reaches saturation, perform solid-liquid separation to obtain a saturated sodium chloride solution and evaporation condensate;

[0039] (5) Evaporate and concentrate the obtained saturated sodium chloride solution to obtain sodium chloride crystals and evaporation condensate. The sodium chloride is sent to the chlorination of copper anode slime as a gold separation reagent, and the condensate is sent to the hydrometallurgical system of copper anode slime smelting.

[0040] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for the coordinated treatment and comprehensive recovery of precious metal smelting wastewater, characterized in that: The following steps are involved: (1) pumping strong acid wastewater into a reactor, adding alkaline wastewater at 50 L / min, stirring and reacting until the pH value is 2-3, filtering to obtain bismuth concentrate and neutralized liquid, and sending the bismuth concentrate to a bismuth recovery process for treatment; (2) pumping the neutralized liquid and weak acid wastewater obtained in step (1) into a reaction kettle, mixing them according to a volume ratio, stirring them evenly, adding alkaline wastewater or sodium hydroxide at 50 L / min until the pH value is 6-8, then adding sodium sulfide for sulfide precipitation, filtering to obtain copper slag and sulfide liquid, and returning the copper slag to the copper smelting pyrometallurgical smelting system for treatment; (3) heating the sulfided liquid obtained in step (2) to 40-60° C., adding sodium chloride to control the mass concentration of sodium chloride in the solution to be 18%-20%, stirring and dissolving, and then rapidly cooling to below 10° C. to precipitate sodium sulfite crystals, and performing solid-liquid separation to obtain sodium sulfite and primary crystallization liquid; (4) sending the primary crystallization liquid obtained in step (3) into a multiple-effect evaporator for evaporation, continuously precipitating sodium sulfite and sodium chloride crystals to obtain a concentrated solution, adding the sulfided liquid to the concentrated solution, repeating steps (3) and (4), continuously precipitating sodium sulfite crystals, concentrating until the sodium chloride solution reaches saturation, and performing solid-liquid separation to obtain a saturated sodium chloride solution and evaporated condensed water; (5) The saturated sodium chloride solution obtained in step (4) is evaporated and concentrated to obtain sodium chloride crystals and evaporation condensed water, the sodium chloride is sent to the copper anode mud chlorination as a gold separation reagent, and the condensed water is sent to the copper anode mud smelting wet process system.

2. According to claim 1, a method for coordinated treatment and comprehensive recovery of precious metal smelting wastewater is characterized in that: The strong acid wastewater in step (1) contains the following components: 3-5 g / L hydrogen ions, 5-10 g / L copper, 30-60 mg / L silver, 15-20 g / L bismuth, 0.1 mg / L gold, 3-5 g / L tellurium, and 70-100 g / L chloride ions; The alkaline wastewater contains 1-2 g / L silver, 30-50 g / L chloride ions and 160-180 g / L sodium sulfite.

3. According to claim 1, a method for coordinated treatment and comprehensive recovery of precious metal smelting wastewater is characterized in that: The components of the weak acid wastewater described in step (2) are: 15-25 g / L copper, 10-20 mg / L silver, 0.5-1 g / L chloride ions, and 0.2-1 g / L hydrogen ions.

4. According to claim 4, a method for coordinated treatment and comprehensive recovery of precious metal smelting wastewater is characterized in that: The volume ratio of the neutralized liquid to the weak acid wastewater in step (2) is 1:1 to 1.

5.

5. A method for the coordinated treatment and comprehensive recovery of precious metal smelting wastewater according to claim 6, characterized in that: The mass ratio of sulfur in the sodium sulfide to copper ions in the solution described in step (2) is 2:

1.

6. According to claim 1, a method for the coordinated treatment and comprehensive recovery of precious metal smelting wastewater is characterized in that: The amount of sodium chloride added in step (3) is such that the mass concentration of sodium chloride is 18-20%.

7. A method for the coordinated treatment and comprehensive recovery of precious metal smelting wastewater according to claim 1, characterized in that: The evaporation temperature in step (4) is 80-100°C.

8. A method for the coordinated treatment and comprehensive recovery of precious metal smelting wastewater according to claim 1, characterized in that: The sodium chloride in step (5) is returned to step (3) for use, and no additional sodium chloride is needed, and it is circulated in the system.

Images