CN101215641A - Technique for separating and extracting platinum and silver from platinum-containing silver iodide waste material - Google Patents

Abstract

The invention relates to novel metallurgical technology for recovering platinum silver iodide waste which combines a wet process and a pyrogenic process, which comprises firstly, removing partial iodine ion and improving grain size of waste through hydrazine hydrate pre-reduction which is beneficial for waste collection, secondly, reducing slag by pyrogenic process, fully separating iodine to form platinum-silver alloy particles, and finally dissolving silver and platinum in sulfuric acid to separate the silver and the platinum. The technology has the advantages of short flow process, high recovery rate and small environment pollution, which can effectively recover silver and platinum in platinum silver iodide waste.

Description

Novel process for separating and extracting platinum and silver from platinum-containing silver iodide waste

The invention relates to the technical field of precious metal metallurgy, in particular to a wet and fire combined process for separating and extracting platinum and silver from platinum-containing silver iodide waste.

Background of the inventionplatinum anticancer drugs mainly include cisplatin (cisplatin), carboplatin (carboplatin), oxaliplatin (oxa-lipoplatin), sulplatin (eptaplatin), nedaplatin (nedaplatin) and loplatin (lobaplatin). They are the most widely used anticancer drugs in clinic at present [ Li Shi Xin, the first choice for cancer chemotherapy, foreign medicineMedicine-synthetic medicine biochemical medicine preparation handbook, 1998, 19(2), 89-101; zhanglun, market analysis of platinum-based anticancer drugs, Chinese prescription, 2003, 3, 138-]. The anti-cancer drugs are synthesized by the classical method at home and abroad [ Alesandro P.A. new synthesis method for diamminemalonotium type compounds and the unexpected behaviour of PtCl]₂(trans-dach)，Inorg.Chim.Acta，1998，151，19-20；Fernande D.Rochon，Synthesis and characterization ofPt(II)complexes with amine and carboxylato ligands，Inorganica Chimica Acta，2000，306：193-204]Involving the addition of K₂PtCl₄The raw material is prepared by the steps of iodide ion substitution, ammonia/amination, silver salt hydrolysis and the like. During the synthesis process, about 7-25% of platinum enters the generated silver iodide waste residue to form a large amount of platinum-containing silver iodide residue. Through analysis, the platinum in the waste residue is mainly used as an intermediate cis- [ Pt (II) A of the synthetic reaction₂I₂](A₂＝2NH₃Or organic diamine), for the recovery of such waste materials, patent application [ Hexiaochan et al, method for recovering silver and platinum from platinum-containing silver iodide slag, CN 1339611A]A process for reducing hydrazine hydrate andseparating sulfuric acid is disclosed, but when hydrazine hydrate is used to reduce silver iodide dregs containing platinum, a layer of silver-platinum metal film is formed on the surface of silver iodide particles to prevent the silver iodide containing platinum from being reduced, so generating a lot of insoluble silver iodide in the next step of sulfuric acid dissolution and releasing a lot of brown toxic I₂Steam, polluting the environment. The undissolved platinum-containing silver iodide needs to be returned for further reduction and dissolution. The repeated reduction-dissolution process lengthens the process flow, and leads to the dispersion and loss of silver and platinum. Therefore, a new waste treatment process is urgently needed to be researched, silver and platinum are effectively recovered, and environmental pollution is reduced.

The invention aims at the problem that platinum-containing silver iodide waste is difficult to reduce, and adopts a new process combining a wet method and a fire method, which comprises the following steps: firstly, hydrazine hydrate is pre-reduced to remove part of iodide ions and increase the granularity of waste materials, thereby being beneficial to the collection of the waste materials; secondly, reducing and slagging by a pyrogenic process, and completely separating iodine to form silver-platinum alloy particles; and thirdly, dissolving and separating silver and platinum by sulfuric acid. The process has the advantages of short flow, high recovery rate and little environmental pollution, and can effectively recover silver and platinum in platinum-containing silver iodide waste.

The second step of the new process of the invention is a key process, and Na is used₂CO₃The reaction agent, the borax as the neutralizing agent and the agglomerant of the reaction slag are mixed with the pre-reduction slag in a graphite crucible, and are melted and reacted at 1300 ℃ to generate a silver-platinum metal liquid phase, the iodine-containing reaction slag is attached by the borax and floats on the upper surface of the metal phase, and is scraped and separated, and the metal phase is dropped into water rotating at high speed in a melting state to obtain the silver-platinum alloy particles. The analysis shows that the recovery rate of silver and platinum in the process is more than 99 percent, iodine-containing compounds are not detected in the silver-platinum alloy particles, and the separation and purification of silver and platinum can be achieved by one-time sulfuric acid dissolution in the next process. The chemical reactions involved are:

Detailed Description

(1) Hydrazine hydrate pre-reduction treatment

Collecting platinum-containing silver iodide waste (comprising wastewater and fine-particle yellow waste) formed in the production process of platinum drugs in a reaction bottle, adjusting the pH value to 10-11 by using ammonia water, adding hydrazine hydrate in an amount 2 times of the theoretical amount, heating and reducing for 4 hours to obtain reducing slag with larger particles, filtering, collecting and washing. After drying at 110 ℃ it was found by analysis that the product still contained 50% (calculated as iodine) iodide (unreduced silver iodide and cis- [ Pt (II) A)₂I₂])。

(2) Reducing and slagging by pyrogenic process

2000 g of pre-reduced slag (containing Pt3.33%, Ag46.63%, iodine 50%) was placed in a graphite crucible, and about 300 g of Na was added₂CO₃And 200 g of borax, heating to 1300 ℃ in a coke oven after mixing, and reacting for 50-60min to form a silvery white metal molten phase and a black reaction slag phase. After the slag phase was scraped off, the metal phase was poured into a stainless steel drum containing high-speed rotating water to obtain 993 g of silver-platinum alloy particles containing 93.2% silver, 6.67% platinum and less than 0.1% iodine, with the silver content in the reaction slag being 0.31% and the platinum content being less than 0.05%. The recovery rate of platinum is 99.4 percent and the recovery rate of silver is 99.2 percent.

(3) Separation of platinum and silver by dissolution in sulfuric acid

500 g of silver-platinum alloy particles are taken, concentrated sulfuric acid is added, silver is selectively dissolved at the temperature of 170 ℃, the concentrated sulfuric acid (v) and the platinum alloy particles (w) are 6: 1, the reaction time is 2 hours, and the leaching rate of the silver is 99.6 percent. The platinum residue after silver separation is 3.33 g, and the purity is more than 99.5%.

Claims (2)

1. A new process for recovering platinum-containing silver iodide waste is characterized by adopting the following process steps:

(1) hydrazine hydrate pre-reduction treatment;

(2) reducing and slagging by a pyrogenic process;

(3) and dissolving and separating silver and platinum by sulfuric acid.

2. The process of claim 1, wherein Na is used in the process of reducing and slagging by fire₂CO₃Is a reactant, borax is a neutralizer and an agglomerant of reaction slag, and is subjected to melt reaction at 1300-1350 ℃.