CN115896457A - A kind of method utilizing copper cadmium slag to prepare cadmium phosphide - Google Patents

Abstract

The invention relates to a method for preparing cadmium phosphide by using copper-cadmium slag, which comprises the following steps: carrying out oxidation acid leaching: mixing copper-cadmium slag, ammonium dichromate and water, stirring for reaction, controlling the end point pH to be = 5-5.2, and performing solid-liquid separation to obtain zinc sulfate and sulfuric acid respectivelyMixed solution of chromium, solid phase; separating zinc and chromium: adding ammonia water into the mixed solution of zinc sulfate and chromium sulfate to carry out chromium precipitation reaction to respectively obtain [ Zn (NH) ₃ ) ₄ ](OH) ₂ Mixed precipitation of the solution, chromium hydroxide and chromium oxysulfate; separating copper and cadmium: adding a sulfuric acid solution and water into the solid phase to carry out acid leaching reaction to respectively obtain a cadmium sulfate solution and copper slag with the copper content of more than 90%; preparing cadmium phosphide: pumping the cadmium sulfate solution into a reaction kettle, adding ammonia water to enable the pH of the solution to be = 9-12, sealing, then removing oxygen in the reactor, introducing phosphine gas for reaction, cooling to room temperature after the reaction is finished, filtering, washing and drying to obtain the cadmium phosphide product with the purity of more than 98%. The invention has short flow, simple operation and low cost.

Description

A kind of method utilizing copper cadmium slag to prepare cadmium phosphide

technical field

The invention relates to a hydrometallurgical process in the field of metallurgy, in particular to a method for preparing cadmium phosphide by utilizing copper cadmium slag.

Background technique

Copper-cadmium slag is the leaching slag produced in the hydrometallurgy zinc purification process. Every 10,000 tons of cathode zinc produced produces 300t of copper-cadmium slag, of which Zn is 45-50%, Cd 8-12%, Cu 6-10%, S 9 ~11%, O 20~32%, others 1~3%, high content of zinc, cadmium and copper.

At present, the copper cadmium slag recycling process is mainly divided into two kinds of pyrotechnics and wet process. The pyrotechnic process is mature, but the energy consumption is high and the equipment requirements are harsh; the wet process is simple and low energy consumption. The industrial treatment of copper cadmium slag is mainly carried out with the recovery of cadmium as the main line, and only by controlling the addition of zinc powder during the two-stage replacement. Ratio to control the grade of sponge cadmium obtained by replacement, can not remove impurities, improve the grade of sponge cadmium, and the economic benefit is low.

Therefore, there is an urgent need to develop a high-value comprehensive recycling process for copper-cadmium slag that is simpler, faster, lower-cost, and environmentally friendly.

Contents of the invention

The technical problem to be solved by the present invention is to provide a method for preparing cadmium phosphide by utilizing copper cadmium slag with short process, simple operation and low cost.

For solving the above problems, a kind of method utilizing copper cadmium slag of the present invention to prepare cadmium phosphide comprises the following steps:

⑴ Oxidative acid leaching:

Mix the copper cadmium slag, ammonium dichromate and water, stir and react, and control the end point pH=5~5.2, and separate the solid and liquid to obtain the mixed solution and solid phase of zinc sulfate and chromium sulfate respectively; the ammonium dichromate The mass ratio to the copper cadmium slag is 0.6~0.68:1; the ratio of the copper cadmium slag to the water is 1kg:10 L;

⑵Separation of zinc and chromium:

In the mixed solution of zinc sulfate and chromium sulfate, add ammonia water to carry out chromium precipitation reaction, the ratio of the copper cadmium slag and the ammonia water is 1kg: 4~8 L, and control the end point pH=8~12, through solidification liquid separation to obtain [Zn(NH ₃ ) ₄ ](OH) ₂ solution, mixed precipitation of chromium hydroxide and chromium oxychrome sulfate; the [Zn(NH ₃ ) ₄ ](OH) ₂ solution enters the electrolysis process after being acidified ; The mixed precipitation of the chromium hydroxide and chromium oxychrome sulfate is oxidized and then returned to the oxidative acid leaching process;

(3) Separation of copper and cadmium:

Add sulfuric acid solution and water with a concentration of 90-180g/L to the solid phase according to the liquid-solid ratio of 3-6 L: 1kg, carry out acid leaching reaction, and control the end point pH = 3-5, after solid-liquid separation , respectively obtain cadmium sulfate solution and copper slag with copper content > 90%; the copper slag is used for refining and recovering copper;

⑷Preparation of cadmium phosphide:

Pump the cadmium sulfate solution into the reaction kettle, first add ammonia water to make the pH of the solution = 9~12, and then seal it, then fill the solution with nitrogen for 3~5 minutes to remove the oxygen in the reactor, and then pass in phosphine The gas is reacted, and after the reaction is completed, it is cooled to room temperature, filtered, washed, and dried to obtain a cadmium phosphide product with a purity >98%; the consumption of the phosphine gas is determined according to the cadmium content.

The main chemical components of the copper cadmium slag in the step (1) are: Zn 45-50%, Cd 8-12%, Cu 6-8%, S 9-11%, O 21-26%, other 1-4%.

The stirring reaction conditions in the step (1) refer to a reaction temperature of 70-85° C., a stirring speed of 200 rpm, and a reaction time of 2-3 hours.

The conditions for the chromium precipitation reaction in the step (2) are that the reaction temperature is 100-120°C, the stirring speed is 200rpm, and the reaction time is 1-2h.

The conditions of the acid leaching reaction in the step (3) refer to that the reaction temperature is 75-90°C, the stirring speed is 150rpm, and the reaction time is 3-6h.

The reaction conditions in the step (4) refer to that the pressure in the reactor is 0.3~0.6MPa, the reaction temperature is 60~80°C, the stirring speed is 200rpm, and the reaction time is 1.5~3h.

Compared with the prior art, the present invention has the following advantages:

1. The present invention utilizes ammonium dichromate solution to carry out oxidative acid leaching to the copper cadmium slag produced in the purification process of wet zinc smelting to separate zinc from copper and cadmium, and then utilize oxidative alkali leaching to separate zinc and chromium and carry out normal pressure acid leaching Copper and cadmium are separated, and finally phosphine gas is introduced into the liquid after copper and cadmium separation to prepare cadmium phosphide products. The purpose of high-value utilization of valence metals and cadmium has important promotion value in industry.

2. The present invention uses ammonium dichromate to oxidize acid leaching copper and cadmium slag, which can realize the efficient separation of zinc, copper and cadmium; the chromium-containing precipitate after the separation of zinc and chromium can be recycled, which reduces the cost. , Cadmium content <10mg/L, meeting the requirements of zinc electrowinning. At the same time, the purity of cadmium phosphide prepared by introducing phosphine gas into the cadmium sulfate solution after separation of copper and cadmium can reach more than 98%, which has higher economic benefits.

Description of drawings

The specific implementation manners of the present invention will be further described in detail below in conjunction with the accompanying drawings.

Fig. 1 is a flowchart of the present invention.

Detailed ways

As shown in Figure 1, a kind of method utilizing copper cadmium slag to prepare cadmium phosphide comprises the following steps:

⑴ Oxidative acid leaching:

Mix copper cadmium slag, ammonium dichromate and water, the mass ratio (kg/kg) of ammonium dichromate to copper cadmium slag is 0.6~0.68:1, and the ratio of copper cadmium slag to water is 1kg:10 L. Stir the reaction at 70-85°C and a speed of 200rpm for 2-3 hours, and control the end point pH=5-5.2. After solid-liquid separation, the mixed solution and solid phase of zinc sulfate and chromium sulfate are obtained respectively.

Among them: the main chemical composition of copper cadmium slag is: Zn 45~50%, Cd 8~12%, Cu 6~8%, S 9~11%, O 21~26%, other 1~4%.

⑵Separation of zinc and chromium:

In the mixed solution of zinc sulfate and chromium sulfate, add ammonia water for chromium precipitation reaction, the ratio of copper cadmium slag to ammonia water is 1kg: 4~8 L, the reaction temperature is 100~120℃, the stirring speed is 200rpm, and the reaction time is 1 ~2h, and control the end point pH=8~12, so that Cr(III) can form chromium hydroxide and chromium oxysulfate precipitation, zinc and ammonia complex to form [Zn(NH ₃ ) ₄ ](OH) ₂ . After solid-liquid separation, [Zn(NH ₃ ) ₄ ](OH) ₂ solution, mixed precipitates of chromium hydroxide and chromium oxysulfate were obtained respectively. The [Zn(NH ₃ ) ₄ ](OH) ₂ solution is acidified and enters the electrolysis process; the mixed precipitate of chromium hydroxide and chromium oxysulfate returns to the oxidative acid leaching process after being oxidized.

(3) Separation of copper and cadmium:

Add sulfuric acid solution with a concentration of 90~180g/L in the solid phase according to the liquid-solid ratio of 3~6 L: 1kg, and carry out acid leaching reaction. The reaction temperature is 75~90°C, the stirring speed is 150rpm, and the reaction time is 3~ 6h, and control the end point pH=3~5. After solid-liquid separation, cadmium sulfate solution and copper slag with a copper content > 90% are obtained respectively; the copper slag is used for refining and recovering copper.

⑷Preparation of cadmium phosphide:

Pump the cadmium sulfate solution into the reactor, first add ammonia water to make the pH of the solution = 9~12, then seal it, then fill the solution with nitrogen gas for 3~5 minutes to remove the oxygen in the reactor, and then pass in phosphine gas, The consumption of phosphine gas is determined according to the cadmium content. Make the pressure in the reactor reach 0.3~0.6MPa, then stop the ventilation, and react at 60~80°C and the speed of 200rpm for 1.5~3h. After the reaction is completed, after cooling to room temperature, filter, wash, and dry to obtain a cadmium phosphide product with a purity >98%.

Ammonia, ammonium dichromate, phosphine gas and sulfuric acid are all industrial grade.

Embodiment 1 A kind of method utilizing copper cadmium slag to prepare cadmium phosphide comprises the following steps:

⑴ Oxidative acid leaching:

Put 1kg of copper cadmium slag (Zn 45%, Cd 12%, Cu 6%, S 10%, O 26%, and other 1%) after grinding to a particle size of -100 mesh in the reactor, add 0.6kg of heavy chromium Ammonium acid was mixed with 3 L of water, stirred and reacted at 70°C and 200 rpm for 2 hours, and the pH at the end point was controlled to be 5~5.2. After solid-liquid separation, 2.93 L of zinc sulfate and chromium sulfate mixed solution, 401 g Solid Phase.

⑵Separation of zinc and chromium:

Add 4.8L of ammonia water to the mixed solution of zinc sulfate and chromium sulfate to carry out the chromium precipitation reaction, the reaction temperature is 100°C, the stirring speed is 200rpm, the reaction time is 2h, and the pH at the end point is controlled to be 12. After solid-liquid separation, 4.7 The mixed precipitation of L [Zn(NH ₃ ) ₄ ](OH) ₂ solution, 430g of chromium hydroxide and chromium oxysulfate. The [Zn(NH ₃ ) ₄ ](OH) ₂ solution is acidified and enters the electrolysis process; the mixed precipitate of chromium hydroxide and chromium oxysulfate returns to the oxidative acid leaching process after being oxidized.

(3) Separation of copper and cadmium:

Add 0.56 L of sulfuric acid solution with a concentration of 180g/L to the solid phase, then add 0.7L of water for acid leaching reaction, the reaction temperature is 75°C, the stirring speed is 150rpm, the reaction time is 3h, and the pH at the end point is controlled to be 3. After solid-liquid separation, 1.25L of cadmium sulfate solution with a cadmium content of 90g/L and 226g of copper slag with a copper content of >90% were obtained respectively; the copper slag was used for refining and recovering copper.

⑷Preparation of cadmium phosphide:

Pump the cadmium sulfate solution into the reactor, first add ammonia water to make the pH of the solution = 9, then seal it, then fill the solution with nitrogen gas for 3-5 minutes to remove the oxygen in the reactor, and then inject 25L of phosphine gas to make the reactor After the pressure in the reactor reached 0.3 MPa, the aeration was stopped, and the reaction was carried out at 80° C. and a speed of 200 rpm for 1.5 h. After the reaction is finished, the excess phosphine gas is passed through the exhaust port into the copper sulfate solution for recovery, and the slurry is cooled to room temperature, filtered, washed, and dried to obtain 120 g of cadmium phosphide product with a purity of 98.5%.

Embodiment 2 A kind of method utilizing copper cadmium slag to prepare cadmium phosphide comprises the following steps:

⑴ Oxidative acid leaching:

Put 1kg of copper cadmium slag (Zn 48%, Cd 10%, Cu 7%, S 11%, O 23%, and others 1%) ground to a particle size of -120 mesh in the reactor, and add 0.68kg of heavy chromium Mix ammonium acid with 5L of water, stir and react at 80°C and 200rpm for 2.5h, and control the end point pH=5~5.2. After solid-liquid separation, 4.93L of zinc sulfate and chromium sulfate mixed solution, 384g Solid Phase.

⑵Separation of zinc and chromium:

Add 5.17L of ammonia water to the mixed solution of zinc sulfate and chromium sulfate to carry out the chromium precipitation reaction, the reaction temperature is 110°C, the stirring speed is 200rpm, the reaction time is 1.5h, and the pH at the end point is controlled to be 10. After solid-liquid separation, respectively, Mixed precipitation of 5.09L [Zn(NH ₃ ) ₄ ](OH) ₂ solution, 488g of chromium hydroxide and chromium oxysulfate. The [Zn(NH ₃ ) ₄ ](OH) ₂ solution is acidified and enters the electrolysis process; the mixed precipitate of chromium hydroxide and chromium oxysulfate returns to the oxidative acid leaching process after being oxidized.

(3) Separation of copper and cadmium:

Add 0.65 L of sulfuric acid solution with a concentration of 130g/L to the solid phase, then add 1.27L of water for acid leaching reaction, the reaction temperature is 80°C, the stirring speed is 150rpm, the reaction time is 4.5h, and the pH at the end point is controlled to be 5. After solid-liquid separation, 1.20L of cadmium sulfate solution with a cadmium content of 78g/L and 214g of copper slag with a copper content of >90% were obtained respectively; the copper slag was used for refining and recovering copper.

⑷Preparation of cadmium phosphide:

Pump the cadmium sulfate solution into the reactor, first add ammonia water to make the pH of the solution = 11, then seal it, then fill the solution with nitrogen gas for 3-5 minutes to remove the oxygen in the reactor, and then inject 20L of phosphine gas to make After the pressure in the reactor reached 0.4 MPa, the aeration was stopped, and the reaction was carried out at 70° C. and a speed of 200 rpm for 2.5 hours. After the reaction, excess phosphine gas was passed through the exhaust port into the copper sulfate solution for recovery, the slurry was cooled to room temperature, filtered, washed, and dried to obtain 100 g of cadmium phosphide product with a purity of 98.3%.

Embodiment 3 A kind of method utilizing copper cadmium slag to prepare cadmium phosphide comprises the following steps:

⑴ Oxidative acid leaching:

Put 1 kg of copper cadmium slag (Zn 50%, Cd 8%, Cu 8%, S 9%, O 21%, and other 4%) ground to a particle size of -100 mesh in the reactor, and add 0.65 kg of heavy chromium Mix ammonium phosphate with 9.9L water, stir and react at 85°C and 200rpm for 3h, and control the end point pH=5~5.2, and separate the solid and liquid to obtain 5.93L mixed solution of zinc sulfate and chromium sulfate, 376g Solid Phase.

⑵Separation of zinc and chromium:

Add 5.35L of ammonia water to the mixed solution of zinc sulfate and chromium sulfate to carry out the chromium precipitation reaction, the reaction temperature is 120°C, the stirring speed is 200rpm, the reaction time is 1h, and the pH at the end point is controlled to be 8. After solid-liquid separation, 5.27 Mixed precipitation of L[Zn(NH ₃ ) ₄ ](OH) ₂ solution, 466g of chromium hydroxide and chromium oxysulfate. The [Zn(NH ₃ ) ₄ ](OH) ₂ solution is acidified and enters the electrolysis process; the mixed precipitate of chromium hydroxide and chromium oxysulfate returns to the oxidative acid leaching process after being oxidized.

(3) Separation of copper and cadmium:

Add 0.75 L of sulfuric acid solution with a concentration of 90g/L to the solid phase, and then add 1.47L of water for acid leaching reaction. The reaction temperature is 85°C, the stirring speed is 150rpm, the reaction time is 6h, and the pH at the end point is controlled to be 5. After solid-liquid separation, 145L of cadmium sulfate solution with a cadmium content of 31g/L and 152g of copper slag with a copper content of >90% were obtained respectively; the copper slag was used for refining and recovering copper.

⑷Preparation of cadmium phosphide:

Pump the cadmium sulfate solution into the reactor, first add ammonia water to make the pH of the solution = 12, then seal it, then fill the solution with nitrogen gas for 3-5 minutes to remove the oxygen in the reactor, and then inject 18L of phosphine gas to make After the pressure in the reactor reached 0.6 MPa, the aeration was stopped, and the reaction was carried out at 60° C. and a speed of 200 rpm for 3 hours. After the reaction is finished, the excess phosphine gas is passed through the exhaust port into the copper sulfate solution for recovery. After the slurry is cooled to room temperature, it is filtered, washed, and dried to obtain 80 g of cadmium phosphide product with a purity of 98.7%.

Claims (6)

1. A method for preparing cadmium phosphide by using copper-cadmium slag comprises the following steps:

carrying out oxidation acid leaching:

mixing copper-cadmium slag, ammonium dichromate and water, stirring for reaction, controlling the terminal pH to be =5 to 5.2, and performing solid-liquid separation to obtain a mixed solution of zinc sulfate and chromium sulfate and a solid phase; the mass ratio of the ammonium dichromate to the copper-cadmium slag is 0.6 to 0.68:1; the proportion of the copper-cadmium slag to the water is 1kg:10 L;

separating zinc and chromium:

adding ammonia water into the mixed solution of zinc sulfate and chromium sulfate for chromium precipitation reaction, wherein the ratio of the copper-cadmium slag to the ammonia water is 1kg:4 to 8L, controlling the terminal pH to be =8 to 12, and performing solid-liquid separation to obtain [ Zn (NH) ₃ ) ₄ ](OH) ₂ Mixed precipitation of the solution, chromium hydroxide and chromium oxysulfate; said [ Zn (NH) ] ₃ ) ₄ ](OH) ₂ Acidifying the solution and then entering an electrolysis process; the mixed precipitate of the chromium hydroxide and the chromium oxysulfate is oxidized and then returns to the oxidation acid leaching process;

separating copper and cadmium:

and (3) to 6L in the solid phase: adding a sulfuric acid solution with the concentration of 90-180g/L and water into 1kg of the solution-solid ratio, carrying out acid leaching reaction, controlling the end point pH to be = 3-5, and carrying out solid-liquid separation to obtain a cadmium sulfate solution and copper slag with the copper content of more than 90 percent; the copper slag is used for refining and recovering copper;

preparing cadmium phosphide:

pumping the cadmium sulfate solution into a reaction kettle, adding ammonia water to enable the pH of the solution to be =9 to 12, sealing, then filling nitrogen into the solution for 3 to 5min to remove oxygen in the reactor, then filling phosphine gas for reaction, cooling to room temperature after the reaction is finished, and filtering, washing and drying to obtain a cadmium phosphide product with the purity of more than 98%; and the consumption of the phosphine gas is determined according to the cadmium content.

2. The method for preparing cadmium phosphide by using copper-cadmium slag as claimed in claim 1, wherein: the copper-cadmium slag in the step comprises the following main chemical components: 45 to 50 percent of Zn, 8 to 12 percent of Cd, 6 to 8 percent of Cu, 9 to 11 percent of S, 21 to 26 percent of O and 1 to 4 percent of the rest.

3. The method for preparing cadmium phosphide by using copper-cadmium slag as recited in claim 1, wherein the method comprises the following steps: the stirring reaction conditions in the step are that the reaction temperature is 70-85 ℃, the stirring speed is 200rpm, and the reaction time is 2-3h.

4. The method for preparing cadmium phosphide by using copper-cadmium slag as claimed in claim 1, wherein: the condition of chromium precipitation reaction in the step II is that the reaction temperature is 100-120 ℃, the stirring speed is 200rpm, and the reaction time is 1-2h.

5. The method for preparing cadmium phosphide by using copper-cadmium slag as claimed in claim 1, wherein: the conditions of the acid leaching reaction in the step three are that the reaction temperature is 75-90 ℃, the stirring speed is 150rpm, and the reaction time is 3-6 h.

6. The method for preparing cadmium phosphide by using copper-cadmium slag as claimed in claim 1, wherein the method comprises the following steps: the reaction conditions in the step four are that the pressure in the reaction kettle is 0.3 to 0.6MPa, the reaction temperature is 60 to 80 ℃, the stirring speed is 200rpm, and the reaction time is 1.5 to 3h.

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