Ammonium complex system-based method for separating and purifying lead, zinc, cadmium, and copper

Abstract

An ammonium complex system-based method for separating and purifying lead, zinc, cadmium, and copper, comprising the following steps: a zinc-containing raw material is leached using a leach solution to produce a leached solution; a filtrate and a filter residue are produced by filtration; the filtrate is mixed with metal lead to displace copper, undergoes a solid-liquid separation to produce a first separated liquid, is mixed with metal cadmium to displace lead, undergoes a solid-liquid separation to produce a second separated liquid, is mixed with metal zinc to displace cadmium, and undergoes a solid-liquid separation to produce a third separated liquid; and, the third separated liquid is electrolyzed to produce metal zinc, and an electrolytic solution is returned to the leaching step.

Claims

1. An ammonium complex system-based method for separating and purifying lead, zinc, cadmium and copper, comprising: (1) leaching a zinc-containing raw material with a leach solution, so as to obtain an extracting solution; (2) filtering the extracting solution obtained in step (1), so as to obtain a filtrate and a filter residue; (3) mixing the filtrate obtained in step (2) with metal lead to displace copper, and performing a solid-liquid separation to obtain a first separated liquid; mixing the first separated liquid with metal cadmium to displace lead, and performing a solid-liquid separation to obtain a second separated liquid; mixing the second separated liquid with metal zinc to displace cadmium, and performing a solid-liquid separation to obtain a third separated liquid; (4) electrolyzing the third separated liquid obtained in step (3) to obtain metal zinc, and subjecting an electrolytic solution after the electrolysis back to step (1) to leach the zinc-containing raw material; wherein the metal lead in step (3) is added in an amount of 0.25-0.3 times a mass of copper in the filtrate in step (2); the metal cadmium in step (3) is added in an amount of 0.5-0.8 times a mass of lead in the first separated liquid; the metal zinc in step (3) is added in an amount of 3-10 times a mass of cadmium in the second separated liquid.

2. The method according to claim 1, wherein the leach solution in step (1) comprises a complexing agent.

3. The method according to claim 2, wherein the complexing agent comprises aqueous ammonia and/or liquid ammonia.

4. The method according to claim 1, wherein a complexing agent is added to the leach solution until a pH value of the leach solution is 3.5-8.

5. The method according to claim 1, wherein a method of the filtration in step (2) is a plate and frame filter press; optionally, the plate and frame filter press comprises a first plate and frame filter press and a second plate and frame filter press; optionally, a filtrate obtained by the first plate and frame filter press is subjected to step (3), a filter residue obtained is subjected to residue washing and the second plate and frame filter press sequentially, and a filtrate obtained by the second plate and frame filter press is subjected to step (3).

6. The method according to claim 1, wherein the amount of metal lead added in step (3) is 0.3 times a mass of copper in the filtrate in step (2).

7. The method according to claim 1, wherein a pH value of the electrolytic solution is 3.5-8 in the electrolysis in step (4).

8. The method according to claim 1, further comprising step (5) melting and casting the metal zinc obtained in step (4) to obtain zinc ingots and slags.

9. The method according to claim 8, further comprising subjecting the slags obtained from step (5) to a selection to obtain zinc ash and zinc particles, subjecting the zinc ash to step (1) for leaching, and subjecting the zinc particles back to step (3) to displace cadmium.

10. The method according to claim 1, comprising: (a) leaching a zinc-containing raw material with a leach solution, wherein the leach solution comprises aqueous ammonia and/or liquid ammonia, so as to obtain an extracting solution; (b) subjecting the extracting solution obtained in step (a) to a plate and frame filter press, wherein the plate and frame filter press comprises a first plate and frame filter press and a second plate and frame filter press, a filtrate obtained by the first plate and frame filter press is subjected to step (c), a filter residue obtained is subjected to residue washing and the second plate and frame filter press sequentially, and a filtrate obtained by the second plate and frame filter press is subjected to step (c); (c) mixing the filtrate obtained in step (b) with metal lead to displace copper, wherein metal lead is added in an amount of 0.25-0.3 times a mass of copper in the filtrate in step (b), and performing a solid-liquid separation to obtain a first separated liquid; mixing the first separated liquid with metal cadmium to displace lead, wherein metal cadmium is added in an amount of 0.5-0.8 times a mass of lead in the first separated liquid, and performing a solid-liquid separation to obtain a second separated liquid; mixing the second separated liquid with metal zinc to displace cadmium, wherein metal zinc is added in an amount of 3-10 times a mass of cadmium in the second separated liquid, and performing a solid-liquid separation to obtain a third separated liquid; (d) electrolyzing the third separated liquid obtained in step (c) to obtain metal zinc, wherein a pH value of an electrolytic solution is 3.5-8 in the electrolysis, and subjecting the electrolytic solution after the electrolysis back to step (a) to leach the zinc-containing raw material; and (e) melting and casting the metal zinc obtained in step (d) to obtain zinc ingots and slags, wherein the slags are subjected to a selection to obtain zinc ash and zinc particles, the zinc ash is subjected back to step (a) for leaching, and the zinc particles are subjected back to step (c) to displace cadmium.

11. The method according to claim 1, wherein a mass ratio of the zinc-containing raw material to the leach solution is determined according to a Zn content of an outlet purification solution being 45-120 g/L, optionally 50-90 g/L, and further optionally 70 g/L.

12. The method according to claim 1, wherein a liquid-solid mass ratio is 8-20:1 in the leaching stage of the zinc-containing raw material.

13. The method according to claim 1, wherein the metal cadmium in step (3) is added in an amount of 0.6 times a mass of lead in the first separated liquid.

14. The method according to claim 1, wherein the metal zinc in step (3) is added in an amount of 5 times a mass of cadmium in the second separated liquid.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1 is a schematic diagram of a system provided in Example 1 of the present application for capturing low-boiling point heavy metals from zinc-containing solid waste by combining separation with ammonium complex.

DETAILED DESCRIPTION

(2) In order to better illustrate the present application and facilitate the understanding of the technical solutions of the present application, the present application will be further described in detail hereinafter. However, the following embodiments are only simple examples of the present application, and do not represent or limit the protection scope of the claims of the present application. The protection scope of the present application is defined by the appended claims.

(3) The typical but non-limiting examples of the present application are described below.

EXAMPLE 1

(4) This example provides an ammonium complex system-based method for separating and purifying lead, zinc, cadmium and copper, the process flow of which is shown in FIG. 1, and the method includes the following steps: (1) a zinc-containing raw material was leached with a leach solution, in which the leach solution contained aqueous ammonia and had a pH of 7, so as to obtain a extracting solution, and a zinc content of the extracting solution was 70 g/L, and a liquid-solid mass ratio was 12:1 in the leaching stage of the zinc raw material; (2) the extracting solution obtained in step (1) was subjected to a plate and frame filter press, in which the plate and frame filter press included a first plate and frame filter press and a second plate and frame filter press, a filtrate obtained by the first plate and frame filter press was subjected to step (3), a filter residue obtained was subjected to residue washing and the second plate and frame filter press sequentially, and a filtrate obtained by the second plate and frame filter press was subjected to step (3); (3) the filtrate obtained in step (2) was mixed with metal lead to displace copper, in which an addition amount of metal lead was 0.25 times a mass of copper in the filtrate in step (2), and a solid-liquid separation was performed to obtain a first separated liquid; the first separated liquid was mixed with metal cadmium to displace lead, in which an addition amount of metal cadmium was 0.6 times a mass of lead in the first separated liquid, and a solid-liquid separation was performed to obtain a second separated liquid; the second separated liquid was mixed with metal zinc to displace cadmium, in which an addition amount of metal zinc was 7 times a mass of cadmium in the second separated liquid, and a solid-liquid separation was performed to obtain a third separated liquid; (4) the third separated liquid obtained in step (3) was electrolyzed to obtain metal zinc, in which a pH value of an electrolytic solution was 7 in the electrolysis, and the electrolytic solution after the electrolysis was subjected back to step (1) to leach the zinc-containing raw material; and (5) the metal zinc obtained in step (4) was melted and cast to obtain zinc ingots and slags, in which the slags were subjected to a selection to obtain zinc ash and zinc particles, the zinc ash was subjected back to step (1) for leaching, and the zinc particles were subjected back to step (3) to displace cadmium.

EXAMPLE 2

(5) This example provides an ammonium complex system-based method for separating and purifying lead, zinc, cadmium and copper, the process flow of which is shown in FIG. 1, and the method includes the following steps: (1) a zinc-containing raw material was leached with a leach solution, in which the leach solution contained aqueous ammonia and had a pH of 6.5, so as to obtain a extracting solution, and a zinc content of the extracting solution was 65 g/L, and a liquid-solid mass ratio was 13:1 in the leaching stage of the zinc raw material; (2) the extracting solution obtained in step (1) was subjected to a plate and frame filter press, in which the plate and frame filter press included a first plate and frame filter press and a second plate and frame filter press, a filtrate obtained by the first plate and frame filter press was subjected to step (3), a filter residue obtained was subjected to residue washing and the second plate and frame filter press sequentially, and a filtrate obtained by the second plate and frame filter press was subjected to step (3); (3) the filtrate obtained in step (2) was mixed with metal lead to displace copper, in which an addition amount of metal lead was 0.3 times a mass of copper in the filtrate in step (2), and a solid-liquid separation was performed to obtain a first separated liquid; the first separated liquid was mixed with metal cadmium to displace lead, in which an addition amount of metal cadmium was 0.7 times a mass of lead in the first separated liquid, and a solid-liquid separation was performed to obtain a second separated liquid; the second separated liquid was mixed with metal zinc to displace cadmium, in which an addition amount of metal zinc was 6 times a mass of cadmium in the second separated liquid, and a solid-liquid separation was performed to obtain a third separated liquid; (4) the third separated liquid obtained in step (3) was electrolyzed to obtain metal zinc, in which a pH value of an electrolytic solution was 6.5 in the electrolysis, and the electrolytic solution after the electrolysis was subjected back to step (1) to leach the zinc-containing raw material; and (5) the metal zinc obtained in step (4) was melted and cast to obtain zinc ingots and slags, in which the slags were subjected to a selection to obtain zinc ash and zinc particles, the zinc ash was subjected back to step (1) for leaching, and the zinc particles were subjected back to step (3) to displace cadmium.

EXAMPLE 3

(6) This example provides an ammonium complex system-based method for separating and purifying lead, zinc, cadmium and copper, the process flow of which is shown in FIG. 1, and the method includes the following steps: (1) a zinc-containing raw material was leached with a leach solution, in which the leach solution contained aqueous ammonia and had a pH of 7.5, so as to obtain a extracting solution, and a zinc content of the extracting solution was 60 g/L, and a liquid-solid mass ratio was 15:1 in the leaching stage of the zinc raw material; (2) the extracting solution obtained in step (1) was subjected to a plate and frame filter press, in which the plate and frame filter press included a first plate and frame filter press and a second plate and frame filter press, a filtrate obtained by the first plate and frame filter press was subjected to step (3), a filter residue obtained was subjected to residue washing and the second plate and frame filter press sequentially, and a filtrate obtained by the second plate and frame filter press was subjected to step (3); (3) the filtrate obtained in step (2) was mixed with metal lead to displace copper, in which an addition amount of metal lead was 0.28 times a mass of copper in the filtrate in step (2), and a solid-liquid separation was performed to obtain a first separated liquid; the first separated liquid was mixed with metal cadmium to displace lead, in which an addition amount of metal cadmium was 0.75 times a mass of lead in the first separated liquid, and a solid-liquid separation was performed to obtain a second separated liquid; the second separated liquid was mixed with metal zinc to displace cadmium, in which an addition amount of metal zinc was 9 times a mass of cadmium in the second separated liquid, and a solid-liquid separation was performed to obtain a third separated liquid; (4) the third separated liquid obtained in step (3) was electrolyzed to obtain metal zinc, in which a pH value of an electrolytic solution was 7.5 in the electrolysis, and the electrolytic solution after the electrolysis was subjected back to step (1) to leach the zinc-containing raw material; and (5) the metal zinc obtained in step (4) was melted and cast to obtain zinc ingots and slags, in which the slags were subjected to a selection to obtain zinc ash and zinc particles, the zinc ash was subjected back to step (1) for leaching, and the zinc particles were subjected back to step (3) to displace cadmium.

EXAMPLE 4

(7) This example provides an ammonium complex system-based method for separating and purifying lead, zinc, cadmium and copper, the process flow of which is shown in FIG. 1, and the method includes the following steps: (1) a zinc-containing raw material was leached with a leach solution, in which the leach solution contained aqueous ammonia and had a pH of 5.5, so as to obtain a extracting solution, and a zinc content of the extracting solution was 50 g/L, and a liquid-solid mass ratio was 18:1 in the leaching stage of the zinc raw material; (2) the extracting solution obtained in step (1) was subjected to a plate and frame filter press, in which the plate and frame filter press included a first plate and frame filter press and a second plate and frame filter press, a filtrate obtained by the first plate and frame filter press was subjected to step (3), a filter residue obtained was subjected to residue washing and the second plate and frame filter press sequentially, and a filtrate obtained by the second plate and frame filter press was subjected to step (3); (3) the filtrate obtained in step (2) was mixed with metal lead to displace copper, in which an addition amount of metal lead was 0.26 times a mass of copper in the filtrate in step (2), and a solid-liquid separation was performed to obtain a first separated liquid; the first separated liquid was mixed with metal cadmium to displace lead, in which an addition amount of metal cadmium was 0.8 times a mass of lead in the first separated liquid, and a solid-liquid separation was performed to obtain a second separated liquid; the second separated liquid was mixed with metal zinc to displace cadmium, in which an addition amount of metal zinc was 9 times a mass of cadmium in the second separated liquid, and a solid-liquid separation was performed to obtain a third separated liquid; (4) the third separated liquid obtained in step (3) was electrolyzed to obtain metal zinc, in which a pH value of an electrolytic solution was 5.5 in the electrolysis, and the electrolytic solution after the electrolysis was subjected back to step (1) to leach the zinc-containing raw material; and (5) the metal zinc obtained in step (4) was melted and cast to obtain zinc ingots and slags, in which the slags were subjected to a selection to obtain zinc ash and zinc particles, the zinc ash was subjected back to step (1) for leaching, and the zinc particles were subjected back to step (3) to displace cadmium.

(8) In a specific embodiment of the present application, a source of the zinc-containing raw material can be zinc hypoxide powders and one or more of blast furnace dust, converter dust, electric furnace dust, and a zinc-containing solid waste containing refractory impurities such as chlorine and fluorine. A zinc content is 40%-70%, and an electrolysis condition includes a voltage of 2.35-3.5 V, a current of 200-600 A, a current efficiency of more than or equal to 94%, and a electrolytic solution temperature of 50-80 C. The metal copper, lead, cadmium and zinc prepared in Examples 1-4 were tested for purity, and results are shown in Table 1.

(9) TABLE-US-00001 TABLE 1 Copper Lead Cadmium Zinc Purity/% Purity/% Purity/% Purity/% Example 1 54.23 93.87 80.37 99.997 Example 2 55.34 91.87 82.18 99.996 Example 3 54.86 92.49 85.94 99.995 Example 4 56.57 95.12 83.85 99.998

(10) It can be seen from the results in Table 1 that, by the ammonium complex system-based method provided in Examples 1-4 of the present application for separating and purifying lead, zinc, cadmium and copper, a purity of the final prepared zinc can reach more than or equal to 99.995%, a purity of the lead can reach more than or equal to 90%, and a purity of the cadmium can reach more than or equal to 80%.

(11) The applicant has stated that although the detailed methods of the present application are illustrated by the above embodiments in the present application, the present application is not limited to the above detailed methods, which means that the present application does not necessarily rely on the above methods to be implemented.