Refining of osmium refers to the process of refining impurities in the crude crucible to produce pure rhodium in the platinum group metal refining process. It is composed of two stages of purification and purification of the absorbing liquid and preparation of the metal ruthenium, and the former is often more important.
A solution of sodium citrate (Na2OSO4) containing about 1 g/L of hydrazine was added to a pH of 8 to 9 by a pressurized hydrogen reduction method, and then SO2 was introduced to pH = 6 and heated to a slight boiling, allowed to stand overnight, and precipitated. Brownish sodium salt, the reaction is:
The filtered sodium sulphate precipitate was re-introduced into the distiller, dissolved by heating with 1:1H2SO4, and reoxidized by adding 40% NaCIO3 solution at 90 ° C, and absorbed by sodium hydroxide solution. A small amount of methanol was added to the first-stage absorption liquid containing bismuth 15-35 g/L, and Ru(OH)4 was precipitated by standing at 40 ° C overnight, and purple K2OsO4 was precipitated by adding KOH to the pure sodium citrate solution after filtration, and the reaction was as follows:
The precipitated potassium citrate obtained by filtration was further slurried with 1:1 HCl, placed in an autoclave, and hydrogenated at a temperature of 125 ° C (hydrogen pressure 3-4 kPa) for 1-2 h to obtain a sponge mash. The reaction was as follows:
The metal cerium powder is filtered in time and washed with ethanol, re-inserted into the tube furnace, dried at low temperature by hydrogen or nitrogen, slowly heated to 900 ° C and reduced with hydrogen for 1 h, and cooled to room temperature to obtain metal cerium powder.