Refining iridium powder is a complex process that involves multiple steps of chemical and metallurgical techniques. Here are the basic steps for refining iridium powder:
Ore Processing:
Iridium is usually found in platinum and nickel ores. In the initial refining stages, the ore is crushed and ground to release iridium and other metals.
Flotation and Roasting:
The iridium is separated from other metals using flotation methods, followed by roasting to oxidize iridium minerals.
Acid Leaching:
The roasted ore is treated with concentrated acids, such as aqua regia (a mixture of concentrated nitric acid and hydrochloric acid), to dissolve iridium and other metals: Ir+6HCl+HNO3→H2[IrCl6]+NO2+2H2O\text{Ir} + 6\text{HCl} + \text{HNO}_3 \rightarrow \text{H}_2[\text{IrCl}_6] + \text{NO}_2 + 2\text{H}_2\text{O}
Extraction and Precipitation:
Iridium ions are extracted from the solution using various chemical reagents, such as chloriridic acid (H₂IrCl₆) or other organic extractants.
Iridium ions are then precipitated from the solution, usually using ammonium or sodium salts to precipitate iridium.
Reduction:
The precipitated iridium compound is reduced to metallic iridium. The reducing agent can be hydrogen gas or other reducing gases. The reduction reaction typically occurs at high temperatures: H2[IrCl6]+3H2→2Ir+6HCl\text{H}_2[\text{IrCl}_6] + 3\text{H}_2 \rightarrow 2\text{Ir} + 6\text{HCl}
Electrolytic Refining:
Further purification of iridium metal is achieved through electrolysis, using impure iridium as the anode and pure iridium as the cathode in an electrolytic cell.
During electrolysis, iridium ions dissolve from the anode and deposit onto the cathode, forming high-purity iridium metal.
Melting and Casting:
The final iridium metal powder is melted at high temperatures to form iridium ingots. These ingots can be further processed into various shapes and sizes to meet different application requirements.
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silver-concentrate extraction processsilver-concentrate extraction processMethods of Silver-concentrate Extraction:
Silver refining is often conducted in cyano and thiosulfate solutions, while the use of HCl and HNO3 for silver leaching is limited. In HCl solution, silver primarily exists as AgCl, forming precipitates under high chloride concentrations. Thus, precipitation methods are commonly used to recover silver rather than leaching methods.
In HNO3 solution, silver mainly exists as AgNO3 with a higher solubility. However, nitric acid acts as a strong oxidizer, which can degrade or age the leach solutions. For effective silver leaching, the leaching agents must possess good anti-oxidation properties. As a result, there are very few effective leaching agents for silver.
In cyano compounds, silver reacts similarly to gold, forming complexes like K3[Ag(CN)2]. These can be leached using appropriate cyanide-based leach solutions.
In thiosulfate-containing solutions, silver forms Ag(S₂O₃), which can be leached by specific reagents. -
electrolytic silver refining processelectrolytic silver refining processAn electrolytic silver refining process in which crude silver is anodically dissolved and refined silver is cathodically deposited and at the same time accompanying metals are selectively extracted from the spent electrolyte and separately cathodically deposited after having been transferred into an aqueous phase and the regenerated electrolyte stripped of accompanying metals is recycled to the refining process and in which further the spent electrolyte is anodically enriched in silver and accompanying metals are cathodically deposited from the aqueous phase in a joint electrolysis step.
The invention resides in that the joint electrolysis step is carried out in a diaphragm cell in which a diffusion zone is provided between one each cathode and one each anode and separated from the anode zone by an anionic separating membrane and from the cathode zone by a cationic separating membrane and that the diaphragm cell is charged via the diffusion zone with accompanying metal extract.
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process for refining copper anode slimeprocess for refining copper anode slimeProcess For Refining Copper Anode Slime.:
1、Sulfuric roasting: recovery of selenium from the fumes;
2、Sulfuric immersion of copper: separation of copper solution and silver, followed by recovery of copper from the silver residue;
3、Alkaline leaching: removal of boric acid from alkaline solutions;
4、Chloride separation of gold: initial gold solution is reduced (the rough gold is refined into fine gold); after reduction, the solution is replaced with palladium and platinum;
5、sodium sulfite separation of silver: sodium sulfite separates silver from sodium sulfite solution; followed by ethanol reduction of rough silver powder;
6、Refining of rough silver: electrorefining of silver
