Iridium is a rare and precious metal, and it has a wide range of applications in chemical, industrial, medical, and other fields. Iridium is as high as $1,000 per gram, so using discarded iridium-containing materials is an effective way to conserve resources and reduce costs. This article will introduce a method for extracting iridium from spent sulfuric acid, as well as the principle, advantages, and precautions of this method.
Methods for extracting iridium.
The method of extracting iridium from waste sulfuric acid is mainly divided into the following steps:
Waste sulfuric acid is mixed with hydrazine hydrate and heated to 80 90 to reduce iridium to monovalent iridium ions to generate chlororuthenic acid solution.
2.The chlororuthenic acid solution was mixed with ammonia, and the pH value was adjusted to 8 10 to form a stable complex between the monovalent iridium ions and ammonia, and the impurities were filtered to obtain an iridium ammonia complex solution.
3.The iridium ammonia complex solution is reacted with sodium sulfide to form a water-insoluble iridium sulfide precipitate, which is filtered, washed, and dried to obtain an iridium sulfide solid with a purity of up to 99%.
4.The iridium sulfide solid and oxygen are calcined at high temperature to oxidize the iridium sulfide to iridium tetroxide, and then dissolved with hydrochloric acid to obtain a chlororuthenic acid solution.
5.The chlororustateate solution is evaporated, concentrated, crystallized, and dried to obtain a solid chlororuthenate acid, which is as pure as 999% iridium metal.
The principle of extracting iridium from waste sulfuric acid is mainly to use the chemical properties of iridium in different media to achieve the separation and purification of iridium through reduction, complexation, precipitation, oxidation and other reactions.
The method of extracting iridium from spent sulfuric acid has several advantages:
The reducing agent hydrazine hydrate is easy to obtain, inexpensive, strong reducing ability, low reaction temperature, fast reaction speed and high reduction efficiency.
Iridium ammonia complex is soluble in water, easy to separate and purify, and is not interfered by other metal ions, which can effectively improve the ** rate and purity of iridium.
The iridium sulfide precipitate is insoluble in water, easy to filter and wash, and has high thermal stability, can withstand high-temperature calcination, and provides convenience for subsequent oxidation and dissolution.
Iridium tetroxide dissolves in hydrochloric acid to produce chloro-ruthenate, a common precursor of iridium metal that can be used to prepare iridium products in a variety of forms and uses.
Precautions for extracting iridium.
Although the method of extracting iridium from waste sulfuric acid has many advantages, it also needs to pay attention to the following issues:
Hydrazine hydrate is a toxic, flammable and explosive chemical, pay attention to safety protection when using, avoid contact with ** and eyes, keep away from fire and static electricity, seal and store when storing, and avoid contact with oxidants.
Chlororuthenic acid is a strong oxidizing agent, corrosive and toxic, wear protective clothing and gloves when using, avoid inhalation or ingestion, operate in a well-ventilated place, and store away from reducing agents and organic matter.
Sodium sulfide is a strong reducing agent, corrosive and toxic, should be handled with care when using, avoid contact with acids or oxidants, produce toxic hydrogen sulfide or sulfate, and be sealed and stored when stored to avoid moisture or heat.
During the calcination process, the temperature and time should be controlled to avoid overheating or incomplete oxidation, which will affect the efficiency and purity of iridium, and at the same time, attention should be paid to the collection and treatment of sulfur dioxide and other waste gases to prevent harm to the environment and human body.
The method of extracting iridium from waste sulfuric acid is a simple, effective and economical method of using iridium metal, which uses the chemical properties of iridium in different media to realize the separation and purification of iridium through reduction, complexation, precipitation, oxidation and other reactions, improves the rate and purity of iridium, reduces the cost of iridium, and provides a feasible way for the reuse of iridium. However, there are also some safety and environmental problems in this method, which require careful protection and handling during operation and storage to ensure the smooth progress of iridium ** and the health of the human body.