Method for removing zinc from zinc powder replacement slag

Abstract

The invention relates to the technical field of platinum group metal refining, in particular to a method for removing zinc from zinc powder replacement slag, which comprises the following steps: adding the zinc powder replacement slag into hydrochloric acid, and then adding a saturated sodium chlorate solution to completely dissolve the zinc powder replacement slag; adding sodium oxalate of which the mass is 1.2-1.5 times of the total mass of zinc in the zinc powder replacement slag into the dissolving solution, reacting for 1.5-2.5 hours, continuously adding sodium oxalate of which the mass is 0.08-0.12 times of the total mass of zinc in the zinc powder replacement slag, and reacting for 20-40 minutes; cooling and filtering, recovering zinc from filter residues, and returning filtrate to the reaction kettle; and adding concentrated hydrochloric acid into the filtrate to decompose excessive sodium chlorate, and recovering platinum and palladium. According to the scheme, the dezincification rate ranges from 98% to 99%, almost 100% of platinum and palladium are recycled, the problems that the zinc content in the zinc powder replacement slag is high, and the influence on the follow-up platinum and palladium product recycling process is large are effectively solved, and the problem that zinc interferes with the quality of platinum and palladium products is solved. And meanwhile, the oxalate is relatively weak in corrosivity and is more friendly to field equipment.

Description

Technical Field

[0001] The invention relates to the technical field of platinum group metal refining, and in particular to a method for removing zinc from zinc powder replacement slag. Background Art

[0002] The statements in this section are merely intended to provide background information related to the technical solution of the present application to aid understanding, and they do not necessarily constitute prior art for the technical solution of the present application.

[0003] The waste liquid generated in the process of separation and purification of platinum group metals is often replaced with zinc powder, thus producing zinc powder replacement slag containing other precious metals. Since the zinc content in the zinc powder replacement slag is quite high, after the zinc powder replacement slag is dissolved, zinc will enter the dissolving liquid in the form of ions due to its active chemical properties, which will not only have a great impact on the subsequent process of recovering platinum and palladium products, but also zinc will reduce the quality of platinum and palladium products. Therefore, before recovering platinum and palladium, it is very necessary to eliminate zinc, an important influencing factor, economically and efficiently. Summary of the invention

[0004] In order to economically and efficiently eliminate zinc before recovering platinum and palladium, the present invention provides a method for removing zinc from zinc powder replacement slag, the zinc removal rate is between 98% and 99%, and almost 100% of platinum and palladium are recovered, which effectively solves the problem that the zinc content in zinc powder replacement slag is high and has a great impact on the subsequent process of recovering platinum and palladium products, and eliminates the problem that zinc interferes with the quality of platinum and palladium products. At the same time, the sodium oxalate used in the method is less corrosive and more friendly to on-site equipment.

[0005] One aspect of the present invention relates to a method for removing zinc from zinc powder replacement slag, wherein the zinc powder replacement slag is a replacement slag produced by replacing waste liquid generated in the process of separation and purification of platinum group metals with zinc powder, and the method comprises:

[0006] Step a: adding the zinc powder replacement slag into hydrochloric acid, wherein the concentration of the hydrochloric acid is controlled to be 5-5.5 mol / L, and the solid-liquid ratio of the zinc powder replacement slag to the hydrochloric acid is controlled to be 1:4-8, and then adding a saturated sodium chlorate solution to completely dissolve the zinc powder replacement slag to obtain a solution;

[0007] Step b: adding sodium oxalate in an amount of 1.2-1.5 times the total mass of zinc in the zinc powder replacement slag to the dissolving solution, reacting for 1.5-2.5 hours, and continuing to add sodium oxalate in an amount of 0.08-0.12 times the total mass of zinc in the zinc powder replacement slag, reacting for 20-40 minutes, to carry out thorough replacement;

[0008] Step c: After the replacement is completed, cooling and filtering are performed to recover zinc from the filter residue, and the filtrate is returned to the reactor;

[0009] Step d: adding concentrated hydrochloric acid with a concentration of 12 mol / L to the filtrate in the reactor to decompose the excess sodium chlorate, and then recovering platinum and palladium.

[0010] In one embodiment, the sodium oxalate is used to remove zinc from the dissolved solution.

[0011] In one embodiment, after the zinc powder replacement slag is added to the hydrochloric acid, the temperature is first raised to 85-90° C., and then a saturated sodium chlorate solution is added.

[0012] In one embodiment, completely dissolving the zinc powder replacement slag includes fully stirring during the dissolution process.

[0013] In one embodiment, in step b, the reaction temperature is maintained at 70-90°C.

[0014] In one embodiment, the zinc removal rate of the zinc powder replacement slag is 98% to 99%.

[0015] The zinc removal rate of the method for removing zinc from zinc powder replacement slag of the present invention is between 98% and 99%, and platinum and palladium are almost 100% recovered, which effectively solves the problem that the zinc content in zinc powder replacement slag is high and has a great impact on the subsequent process of recovering platinum and palladium products, and eliminates the problem that zinc interferes with the quality of platinum and palladium products. At the same time, the sodium oxalate used is less corrosive and more friendly to on-site equipment. The technology is very easy to realize industrialization, has a short process flow, is simple to operate, is economical and environmentally friendly, has a high zinc removal rate and a significant effect, and is of great significance for the separation and purification of platinum group metals. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The embodiments of the present invention are further described below with reference to the accompanying drawings, in which:

[0017] Figure 1 The figure is a schematic flow chart of a method for removing zinc from zinc powder replacement slag according to one embodiment. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below through specific embodiments in conjunction with the accompanying drawings. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0019] Figure 1 The present invention is a schematic flow diagram of a method for removing zinc from zinc powder replacement slag according to an embodiment, wherein the zinc powder replacement slag is a replacement slag produced by replacing waste liquid generated in the process of separation and purification of platinum group metals with zinc powder. The method comprises:

[0020] Step a: adding the zinc powder replacement slag into hydrochloric acid, wherein the concentration of the hydrochloric acid is controlled to be 5-5.5 mol / L, and the solid-liquid ratio of the zinc powder replacement slag to the hydrochloric acid is controlled to be 1:4-8, and then adding a saturated sodium chlorate solution to completely dissolve the zinc powder replacement slag to obtain a solution;

[0021] Step b: adding sodium oxalate in an amount of 1.2-1.5 times the total mass of zinc in the zinc powder replacement slag to the dissolving solution, reacting for 1.5-2.5 hours, and continuing to add sodium oxalate in an amount of 0.08-0.12 times the total mass of zinc in the zinc powder replacement slag, reacting for 20-40 minutes, to carry out thorough replacement;

[0022] Step c: After the replacement is completed, cooling and filtering are performed to recover zinc from the filter residue, and the filtrate is returned to the reactor;

[0023] Step d: adding concentrated hydrochloric acid with a concentration of 12 mol / L to the filtrate in the reactor to decompose the excess sodium chlorate, and then recovering platinum and palladium.

[0024] In the above method, sodium oxalate is used to remove zinc from the dissolved solution.

[0025] In one embodiment, after the zinc powder replacement slag is added to the hydrochloric acid, the temperature is first raised to 85-90° C., and then a saturated sodium chlorate solution is added to allow for sufficient reaction and dissolution.

[0026] In one embodiment, sufficient stirring is performed during the process of dissolving the zinc powder replacement slag to accelerate the dissolution process.

[0027] In one embodiment, in step b, the reaction temperature is maintained at 70-90°C to facilitate thorough replacement.

[0028] By adopting the above method, the zinc removal rate of zinc in zinc powder replacement slag can reach 98% to 99%, and at the same time, the platinum and palladium recovery rate is almost close to 100%.

[0029] Example 1

[0030] A method for removing zinc from zinc powder replacement slag, the steps are as follows: first, adding zinc powder replacement slag into hydrochloric acid, wherein the concentration of hydrochloric acid is controlled to be 5.5 mol / L, the solid-liquid ratio of zinc powder replacement slag to hydrochloric acid is controlled to be 1:8, heating to 90°C, and then adding saturated sodium chlorate (NaClO3) solution to completely dissolve the zinc powder replacement slag; second, adding sodium oxalate 1.2 times the total mass of zinc in the zinc powder replacement slag to the dissolving solution for reaction for 1.5 hours, and continuing to add sodium oxalate 0.1 times the total mass of zinc in the zinc powder replacement slag, reacting for 30 minutes, and performing thorough replacement; third, after the replacement is completed, cooling and filtering, recovering zinc from the filter residue, and returning the filtrate to the reactor; fourth, adding concentrated hydrochloric acid (12 mol / L) to the filtrate in the reactor to decompose the excess sodium chlorate, and recovering platinum and palladium. After the above steps, the zinc removal rate of zinc powder replacement slag is as high as 98.24%, the platinum and palladium dissolution rate reaches 100%, and the rhodium and iridium dissolution rate reaches 99.94%. Table 1 is the statistical analysis results of the content of each element in the zinc powder replacement slag, and Table 2 is the statistical analysis results of the content of each element in the dezincification liquid.

[0031] Table 1 Statistics of analysis results of each element content in zinc powder replacement slag

[0032]

[0033] Table 2 Statistics of analysis results of each element content in dezincification solution

[0034]

[0035] Example 2

[0036] A method for removing zinc from zinc powder replacement slag, the steps are as follows: first, adding zinc powder replacement slag into hydrochloric acid, wherein the concentration of hydrochloric acid is controlled to be 5 mol / L, the solid-liquid ratio of zinc powder replacement slag to hydrochloric acid is controlled to be 1:6, heating to 85°C, and then adding saturated sodium chlorate (NaClO3) solution to completely dissolve the zinc powder replacement slag; second, adding sodium oxalate 1.5 times the total mass of zinc in the zinc powder replacement slag to the dissolving solution for reaction for 2.5 hours, and continuing to add sodium oxalate 0.08 times the total mass of zinc in the zinc powder replacement slag, reacting for 40 minutes, and performing thorough replacement; third, after the replacement is completed, cooling and filtering, recovering zinc from the filter residue, and returning the filtrate to the reactor; fourth, adding concentrated hydrochloric acid (12 mol / L) to the filtrate in the reactor to decompose the excess sodium chlorate, and recovering platinum and palladium. After the above steps, the zinc removal rate of zinc powder replacement slag is as high as 98.71%, the platinum and palladium dissolution rate reaches 100%, and the rhodium and iridium dissolution rate reaches 99.87%. Table 3 is the statistical analysis results of the content of each element in the zinc powder replacement slag, and Table 4 is the statistical analysis results of the content of each element in the dezincification liquid.

[0037] Table 3 Statistics of analysis results of each element content in zinc powder replacement slag

[0038]

[0039] Table 4 Statistics of analysis results of each element content in zinc powder replacement slag

[0040]

[0041] Example 3

[0042] A method for removing zinc from zinc powder replacement slag, the steps are as follows: first, adding zinc powder replacement slag into hydrochloric acid, wherein the concentration of hydrochloric acid is controlled to be 5 mol / L, the solid-liquid ratio of zinc powder replacement slag to hydrochloric acid is controlled to be 1:4, heating to 90°C, and then adding saturated sodium chlorate (NaClO3) solution to completely dissolve the zinc powder replacement slag; second, adding sodium oxalate 1.3 times the total mass of zinc in the zinc powder replacement slag to the dissolving solution for 2 hours, and then continuing to add sodium oxalate 0.12 times the total mass of zinc in the zinc powder replacement slag, reacting for 20 minutes, and performing thorough replacement; third, after the replacement is completed, cooling and filtering, recovering zinc from the filter residue, and returning the filtrate to the reactor; fourth, adding concentrated hydrochloric acid (12 mol / L) to the filtrate in the reactor to decompose the excess sodium chlorate, and recovering platinum and palladium. After the above steps, the zinc removal rate of zinc powder replacement slag is as high as 98.56%, the platinum and palladium dissolution rate reaches 100%, and the rhodium and iridium dissolution rate reaches 99.87%. Table 5 is the statistical analysis results of the content of each element in the zinc powder replacement slag, and Table 6 is the statistical analysis results of the content of each element in the dezincification liquid.

[0043] Table 5 Statistics of analysis results of each element content in zinc powder replacement slag

[0044]

[0045] Table 6 Statistics of analysis results of each element content in zinc powder replacement slag

[0046]

[0047] The dezincification rate of the above method is between 98% and 99%, and almost 100% of platinum and palladium are recovered, which effectively solves the problem of high zinc content in zinc powder replacement slag, which has a great impact on the subsequent process of recovering platinum and palladium products, and eliminates the problem of zinc interfering with the quality of platinum and palladium products. At the same time, the sodium oxalate used is less corrosive and more friendly to on-site equipment. This solution is very easy to industrialize, with a short process flow, simple operation, economy and environmental protection, high dezincification rate and significant effect, which is of great significance for the separation and purification of platinum group metals.

[0048] References herein to "various embodiments", "some embodiments", "one embodiment" or "an embodiment" etc. refer to that a particular feature, structure or property described in conjunction with the embodiment is included in at least one embodiment. Therefore, the phrases "in various embodiments", "in some embodiments", "in one embodiment" or "in an embodiment" etc. appearing throughout this document do not necessarily refer to the same embodiment. In addition, particular features, structures or properties may be combined in any suitable manner in one or more embodiments. Therefore, the particular features, structures or properties shown or described in conjunction with one embodiment may be combined in whole or in part with features, structures or properties of one or more other embodiments without restriction, as long as the combination is not illogical or inoperable. Expressions similar to "according to A", "based on A", "through A" or "using A" appearing herein are intended to be non-exclusive, that is, "according to A" may cover "according to A only" or "according to A and B", unless it is specifically stated that its meaning is "according to A only". In this application, for the sake of clarity, some exemplary operating steps are described in a certain order, but those skilled in the art will understand that each of these operating steps is not essential, and some of the steps may be omitted or replaced by other steps. These operation steps do not have to be executed sequentially in the manner shown; on the contrary, some of these operation steps can be executed in different orders or in parallel according to actual needs, as long as the new execution manner is not illogical or inoperable.

[0049] Some exemplary embodiments of the present invention are described above. It can be understood that the above embodiments are only used to explain the present invention and do not constitute a limitation on the protection scope of the present invention. The features in these embodiments can be recombined in a suitable manner, and the scheme obtained thereby is still within the protection scope required by the present invention. Based on the above embodiments, all other embodiments obtained by those skilled in the art without making creative work, that is, all modifications, equivalent substitutions and improvements made within the spirit and principles of this application, fall within the protection scope required by the present invention.

Claims

1. A method for removing zinc from zinc powder replacement slag, wherein the zinc powder replacement slag is produced by replacing waste liquid generated in the process of separation and purification of platinum group metals with zinc powder, the method comprising: Step a: adding the zinc powder replacement slag into hydrochloric acid, wherein the concentration of the hydrochloric acid is controlled to be 5-5.5 mol / L, and the solid-liquid ratio of the zinc powder replacement slag to the hydrochloric acid is controlled to be 1:4-8, and then adding a saturated sodium chlorate solution to completely dissolve the zinc powder replacement slag to obtain a solution; Step b: adding sodium oxalate in an amount of 1.2-1.5 times the total mass of zinc in the zinc powder replacement slag to the dissolving solution, reacting for 1.5-2.5 hours, and continuing to add sodium oxalate in an amount of 0.08-0.12 times the total mass of zinc in the zinc powder replacement slag, reacting for 20-40 minutes, to carry out thorough replacement; Step c: After the replacement is completed, cooling and filtering are performed to recover zinc from the filter residue, and the filtrate is returned to the reactor; Step d: adding concentrated hydrochloric acid with a concentration of 12 mol / L to the filtrate in the reactor to decompose the excess sodium chlorate, and then recovering platinum and palladium.

2. A method for removing zinc from zinc powder replacement slag according to claim 1, wherein: The sodium oxalate is used to remove zinc from the dissolved solution.

3. A method for removing zinc from zinc powder replacement slag according to claim 1, wherein: After adding the zinc powder replacement slag into the hydrochloric acid, first heat it to 85-90°C, and then add the saturated sodium chlorate solution.

4. A method for removing zinc from zinc powder replacement slag according to claim 1, wherein: The step of completely dissolving the zinc powder replacement slag includes fully stirring during the dissolution process.

5. A method for removing zinc from zinc powder replacement slag according to claim 1, wherein: In step b, the reaction temperature is maintained at 70-90°C.

6. A method for removing zinc from zinc powder replacement slag according to claim 1, wherein: The zinc removal rate of the zinc powder replacement slag is 98% to 99%.

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