CN114737058A

CN114737058A - Method for separating platinum, palladium, rhodium and iridium from solution

Info

Publication number: CN114737058A
Application number: CN202210282050.8A
Authority: CN
Inventors: 夏军; 张梦晨; 巩伟龙; 张柏松; 李富荣
Original assignee: Xuzhou Hootech New Materials Science & Technology Co ltd
Current assignee: Xuzhou Hootech New Materials Science & Technology Co ltd
Priority date: 2022-03-22
Filing date: 2022-03-22
Publication date: 2022-07-12

Abstract

A process for separating Pt, Pd, Rh and Ir from solution includes adding strong oxidant and saturated ammonium chloride solution to deposit the chloroplatinic acid amine, chlororhodic acid amine and chloroiridic acid amine. Adding ammonia water for slurrying, heating and stirring, and allowing palladium salt to enter a solution. The filtrate is palladium solution, and the filter residue is amine chloroplatinate, amine chlororhodate and amine chloroiridate. And refining the palladium liquid to recover the palladium. Adding water into the residue of amine chloroplatinate, amine chlororhodate and amine chloroiridate to make slurry, heating, adding hydrazine hydrate, reducing platinum and rhodium into simple substance, reducing quadrivalent iridium salt into trivalent, adjusting the solution to acidity, transferring iridium salt into solution, and transferring iridium liquid into refining to recover iridium. The filter residue is platinum and rhodium powder, and is dried, dissolved by hydrochloric acid and hydrogen peroxide, the platinum is transferred into the solution, and the platinum solution is transferred into refining after filtration. And refining the filter residue which is the crude rhodium to obtain rhodium powder. The invention provides a separation means of complex precious metal materials, and solves the problems of incomplete separation, large waste water and liquid in separation, complex process, high cost and the like.

Description

Method for separating platinum, palladium, rhodium and iridium from solution

Technical Field

The invention belongs to the technical field of chemical metallurgy, and particularly relates to a method for quickly separating platinum, palladium, rhodium and iridium from a solution in an environment-friendly and efficient manner.

Background

After the noble metal is enriched to make liquid, the solution often contains noble metal elements such as platinum, palladium, rhodium, iridium and the like. The prior art only aims at one precious metal and complex materials, and has imperfect process route and low separation yield. In the production, the original separation method needs to be changed to improve the separation efficiency and increase the yield. The original separation method mostly adopts an extraction method, a resin exchange method, a precipitation method and the like. The extraction method often faces the problems that each batch of materials has large difference, the extraction is difficult to be continuously carried out, in the extraction process, due to large noble metal types, slight error in condition control and serious noble metal co-extraction, the workload is increased, and although the resin method has the advantages of convenient operation and small labor amount, the resin is still high in price, the noble metal is large in entrainment and difficult to recover.

In the past, the method for separating precious metals is usually used for extracting base metals by P204 and extracting platinum by hydrolysis, but a problem is always faced, the hydrolysis of platinum in complex materials is often incomplete, the amount of residual platinum in hydrolysis residues is large after the hydrolysis, and a solution still contains a platinum, palladium, rhodium and iridium system, so that the problem of separating platinum, palladium, rhodium and iridium still exists after the hydrolysis and platinum extraction. If the method disclosed by the patent is adopted, the problems can be solved, and the separation efficiency is greatly improved.

In the patent 200410078045.7, the feed liquid is also a complex material containing platinum, palladium, rhodium and iridium. The separation method is characterized in that firstly, the platinum, palladium, rhodium and iridium solution after gold separation is obtained, firstly, the palladium is extracted by using an extraction liquid, the extraction technology is large, the extraction liquid needs to be reversely extracted to extract the palladium, after the extraction is finished, the extraction liquid is subjected to pH adjustment and then passes through resin, the base metal copper iron aluminum is separated, and the like. Compared with the patent, the organic solution generates more and pollutes the environment.

Comparing with 201410461779.7 separation method of many kinds of noble metals, the residue after steaming ruthenium and osmium is firstly deposited iridium, oxidant is added into the solution, ammonium chloride is deposited, most noble metals are in high valence state, and other noble metals are mixed in the deposition process, which affects direct yield. And separating the rest of the platinum, the palladium and the rhodium by using a precipitation method to separate the platinum, yellow drug precipitation palladium and copper powder to replace the rhodium. The solution amount is large, the base metal in the solution is much, the platinum is separated by the precipitation method, the rhodium and palladium solution tend to precipitate in a small amount, the direct yield is low, the rhodium is separated by replacement, the copper consumption in the replacement is high, the cost is not high economically,

it is necessary to optimize a new method with high separation efficiency, high direct yield and good economic benefit.

Disclosure of Invention

The invention aims to provide a method for separating platinum, palladium, rhodium and iridium from a solution, which is environment-friendly, efficient and rapid, has an environment-friendly and short overall process flow, and can solve the problems of incomplete separation of a complex precious metal solution material similar to platinum, palladium, rhodium and iridium, large waste water and liquid, complex process, high cost and the like.

In order to achieve the above object, the present invention provides a method for rapidly separating platinum, palladium, rhodium and iridium from a solution in an environment-friendly and efficient manner, comprising the following steps:

(1) and (3) precious metal precipitation: the solution containing platinum, palladium, rhodium and iridium is fully oxidized. And then adding a saturated ammonium chloride solution with the theoretical calculated amount of 1.5-2 times to precipitate the platinum, the palladium, the rhodium and the iridium into chloroplatinic acid amine, chlororhodic acid amine and chloroiridic acid amine.

(2) And (3) filtering: filtering the precipitate obtained in step (1) from the solution and separating the noble metal from the solution. After the precious metal is precipitated once, the base metal and the precious metal are separated, so that the solution amount is reduced and the production difficulty is reduced in subsequent experiments.

(3) Separating and recovering palladium: adding ammonia water into the precipitate obtained in the step (2) for slurrying, heating to 70-80 ℃, stirring for several hours, transferring all palladium salt and a small amount of other noble metals into the solution, filtering, obtaining palladium liquid from filter residues, namely chloroplatinic amine, chlororhodic amine and chloroiridic amine salt, refining the palladium liquid and recovering palladium powder. The ammonia water amount is small, the separation is incomplete, the ammonia water amount is large, and part of other noble metals also enter the solution, so that the ammonia water is used for separating the noble metals pioneering.

(4) And (3) separating and recovering iridium: and (4) adding sodium hydroxide into the filter residue obtained in the step (3) for slurrying, heating to 60-80 ℃, preferably 70 ℃, adding a hydrazine hydrate solution, quantitatively reducing platinum and rhodium into simple substances, and reducing tetravalent iridium into trivalent iridium salt. After the reduction is finished, hydrochloric acid is added to adjust the solution to be acidic, and the trivalent iridium salt is transferred into the solution. Filtering, wherein the filtrate is iridium liquid, and the filter residue is platinum and rhodium powder. And (4) refining the iridium liquid to recover iridium powder.

(5) Separating and recovering platinum and rhodium: and (4) drying the platinum and rhodium residues in the step (4) at 400 ℃ through 300-. The filter residue is the main crude rhodium, and pure rhodium powder can be obtained by refining.

Preferably, in the step (2), the oxidizing agent may be chlorine gas, sodium chlorate, sodium bromate or the like, and if the oxidizing agent is sodium bromate or the like, the addition amount is 5 times of the theoretical amount, and the ammonium chloride is 1.5 times or more of the theoretical amount, so that the noble metal can be completely separated from the solution.

Preferably, the adding amount of the ammonia water in the step (3) is 1kg of noble metal ammonium salt, and 6-8L of ammonia water solution can realize the complete separation of palladium.

The alkalinity of the sodium hydroxide slurrying in the step (4) is pH =13, the addition amount of hydrazine hydrate is strictly added according to the calculated amount, 1-2mL of hydrazine hydrate is needed for 1g of platinum, and 0.6-0.85mL of hydrazine hydrate is needed for 1g of rhodium, and at the moment, the separation effect of platinum, rhodium and iridium is good. At the moment, the platinum, rhodium and iridium can be ensured to be separated, if the hydrazine hydrate is too large, much iridium is converted into a simple substance, and the subsequent separation is not favorable.

Preferably, the platinum and rhodium slag in the step (5) needs to be dried at the temperature of between 300 ℃ and 400 ℃.

The invention has the beneficial effects that: (1) the invention adopts one-step precipitation and fractional recovery, the whole process flow is short, the operation is simple, the manual requirement is low (2) the invention adopts chemical reagents which are common reagents, and the price is cheap and easy to obtain. (3) The technical scheme adopted by the invention has the advantages of small waste water amount, no organic pollution and environmental protection. (4) The invention can solve the problems of incomplete separation of complex noble metal solution materials containing platinum, palladium, rhodium and iridium, large waste water and liquid, complex process, high cost and the like. The noble metal separation effect is good, and the direct recovery rate is high.

Drawings

FIG. 1 is a flow chart of the method of the present invention.

Detailed description of the invention

Example 1

Purifying 500L of noble metal solution containing noble metal platinum, palladium, rhodium and iridium. The raw material data are shown in table 1. Transferring the noble metal solution of noble metal containing platinum, palladium, rhodium and iridium into a reaction kettle, heating to 50-60 ℃, introducing chlorine, and fully oxidizing for 12 h. After the oxidation was complete, 61.6kg of ammonium chloride was quickly added to precipitate the noble metal while maintaining the solution at 50-60 ℃. And after the precipitation is finished, cooling the reaction kettle to 40-50 ℃ by water, and filtering out chloroplatinic acid amine, chloropalladic acid amine, chlororhodic acid amine and chloroiridic acid amine. The filter residue was washed with a solution of 17% NH4Cl at pH 1 until the wash water was colorless. And detecting the precipitation tail liquid. The tail liquid data are shown in Table 2. From the data, the noble metal precipitation rates were all greater than 99%.

TABLE 1 raw data for noble metal solutions containing platinum, palladium, rhodium, iridium

Element(s)	Platinum (II)	Palladium (II)	Rhodium	Iridium (III)	Iron	Copper (Cu)	Aluminium
								Content g/L	35	22	30	15	6	11	4

TABLE 2 precipitation tail solution analysis data

Element(s)	Platinum (II)	Palladium (II)	Rhodium	Iridium (III)	Iron	Copper (Cu)	Aluminium
								Content g/L	0.175	0.33	0.81	0.22	5.86	10.3	2.97

Then adding 180kg of precious metal ammonium salt wet weight into 1200L of strong ammonia water for slurrying, then heating to 70-80 ℃, starting stirring for reaction for 8h, and cooling. Filtering, washing the filter residue with ammonia water for 3 times, and transferring the washing water into ammoniation solution. The filter residue is taken for dissolution analysis, and the solution contains 12.51g/L of platinum, 0.075g/L of palladium, 11.25g/L of rhodium and 5.41g/L of iridium. After being concentrated, the ammoniated solution is analyzed to have the palladium content of 45g/L, the platinum content of 0.4g/L, the rhodium content of 0.1g/L and the iridium content of 0.03 g/L. After ammonia water treatment, palladium separation is realized, the crude palladium ammoniation solution is refined, and pure palladium powder is collected.

TABLE 3 ammoniated liquid analytical data

Element(s)	Platinum (II)	Palladium (II)	Rhodium	Iridium (III)
					Content g/L	0.4	45	0.1	0.03

Standard 4 slag analysis data

Element(s)	Platinum (II)	Palladium (II)	Rhodium	Iridium (III)
					Content g/L	12.51	0.075	11.25	5.41

Adding the rest 150kg of platinum, rhodium and iridium ammonium salt slag into 600kg of 0.1M sodium hydroxide solution for slurrying, heating to 60-80 ℃, preferably 70 ℃, slowly adding 80L of hydrazine hydrate, stirring for reacting for 8h, and then boiling for 1 h. After the complete reaction, hydrochloric acid is added to adjust the pH value to about 0.5, and the mixture is cooled and filtered. The filter residue is washed several times with 0.5MHCl and the solution is transferred into solution. The filter residue is platinum rhodium powder, and the dry weight is 32.21 kg. A small amount of filter residue is taken and converted into a solution for analysis, wherein platinum is 50g/L, rhodium is 44g/L, and iridium is 0.13 g/L. After the filtrate was concentrated, 0.065g/L of platinum, 0.03g/L of rhodium and 10g/L of iridium were analyzed. And (5) converting the filtrate into iridium for refining to obtain pure iridium powder.

TABLE 5 hydrazine hydrate slag analysis data

Element(s)	Platinum (II)	Rhodium	Iridium complex (III)
				Content g/L	50	44	0.5

TABLE 6 analysis data of hydrazine hydrate reducing solution

Element(s)	Platinum (II)	Rhodium	Iridium (III)
				Content g/L	50	44	0.5

And (3) placing the platinum and rhodium powder in a muffle furnace for roasting for 5 hours at the temperature of 350 to 60 ℃, slurrying with hydrochloric acid in a ratio of 1:1, heating to 50 to 60 ℃, slowly adding hydrogen peroxide, and reacting for about 10 hours. And (5) cooling and filtering. And (4) after the filtrate is concentrated and analyzed, 36g/L of platinum, 0.4g/L of rhodium and absolute dominance of platinum are obtained, and pure platinum powder is prepared by refining. A small amount of filter residue is analyzed by liquid making, platinum is 0.051g/L, and rhodium is 23 g/L. Transferring to a rhodium refining workshop to prepare pure rhodium powder.

TABLE 7 analysis data for hydrogen peroxide hydrochloride dissolution

Element(s)	Platinum (II)	Rhodium	Iridium (III)
				Content g/L	50	44	0.5

The above-described embodiments are preferred embodiments of the present invention, and the scope of the invention is defined by the claims.

Claims

1. A method for separating platinum, palladium, rhodium and iridium from a solution is characterized by comprising the following steps:

and (3) full precipitation of noble metals: adding a strong oxidant into a solution containing platinum, palladium, rhodium and iridium to keep noble metal in a high valence state; then adding saturated ammonium chloride solution with the theoretical calculated amount of 1.5-2.0 times to precipitate platinum, palladium, rhodium and iridium in the form of chloroplatinic acid amine, chlororhodic acid amine and chloroiridic acid amine;

and (3) filtering: filtering the precious metal precipitate obtained in the step (1) from the solution, and separating the precious metal from the solution;

separating and recovering palladium: adding ammonia water into the precipitate obtained in the step (2) to pulpify, heating to 70-80 ℃, stirring for a plurality of hours, filtering, wherein filter residues are chloroplatinic acid amine, chlororhodic acid amine and chloroiridic acid amine salt, filtrate is palladium liquid, and pure palladium powder is recovered from the main palladium liquid through refining;

and (3) separating and recovering iridium: adding water into the filter residue obtained in the step (3) for slurrying, heating to 60-80 ℃, controlling the amount of added hydrazine hydrate, quantitatively reducing platinum and rhodium into simple substances, and reducing tetravalent iridium into trivalent iridium salt; after the reduction is finished, adding hydrochloric acid to adjust the solution to be acidic, and transferring the trivalent iridium salt into the solution; filtering to obtain filtrate as iridium solution and filter residue as platinum and rhodium powder; refining the main iridium liquid to recover iridium powder;

separating and recovering platinum and rhodium: drying the platinum and rhodium residues in the step (4) at 400 ℃ through 300-; the filter residue is crude rhodium, and pure rhodium powder can be obtained by refining.

2. The method of claim 1, wherein the strong oxidant is selected from the group consisting of chlorine, sodium chlorate, sodium bromate.

3. The method of claim 2, wherein the amount of sodium bromate added is 5 times the theoretical amount and the amount of ammonium chloride added is 1.5 times or more the theoretical amount.

4. The method for separating Pt, Pd, Rh and Ir from their solutions as claimed in claim 1, wherein said ammonia is added in an amount of 1kg of ammonium salts of noble metals and 6-8L of aqueous ammonia.

5. The method of claim 1, wherein the hydrazine hydrate is added in an amount theoretically calculated to yield 1-2mL of hydrazine hydrate for 1g of platinum and 0.6-0.85mL of hydrazine hydrate for 1g of rhodium.