Including pure iridium compound prepared is reduced to metal and calcined in two steps. The ammonium chloride white smoke is exhausted, cooled and transferred to a hydrogen reduction furnace for hydrogen reduction at a temperature of 800-900 ° C, and then replaced with an inert atmosphere and cooled to room temperature to obtain a metal ruthenium. China Metal Antimony Product Standard ( GB1422-89 ) /% species Ir Pt Pd Rh Ag Cu Ni Fe Al Pb  Sn Si Total impurity FIr-1 99.99 0.003 0.001 0.003 0.001 0.002 0 0 0 0.001 0.001 0.003 0.01 FIr -2 99.95 0.02 0.02 0.02 0.005 0.005 0.01 0.01 0 0.005 0.005 0.005 0.05 FIr -3 99.9 0.03 0.03 0.03 　 　 0.01 0.02 0 0.01 0.01 0.01 0.1 Twinkle System Technology Co Ltd , https://www.pickingbylight.com
1. The preparation of pure hydrazine compound has nitroso complexation, sulfurization and extraction methods.
(1) Sodium nitrite complexation The red chlorohydrazine solution was adjusted to a pH of about 1 with dilute lye, and was added to NaNO 2 to boil and converted to a pale yellow Na 3 Ir(NO 2 ) 6 solution. The reaction was:
H 3 IrCl 6 +6NaNO 2 =====Na 3 Ir(NO 2 ) 6 +3HCl+3NaCl
After cooling, the impurity precipitate was filtered off. The hydrazine solution is boiled with concentrated hydrochloric acid and re-converted to Na3 IrC}. The reaction is:
Na 3 Ir(NO 2 ) 6 +6HCI=====Na 3 IrCl 6 +6HNO 2
After repeated complexation to the required purity, the chlorine gas is oxidized and ammonium chloride is added to precipitate ammonium chlorate:
Na 3 IrCl 6 +2NH 4 Cl+0.5Cl 2 =====(NH 4 ) 2 IrCl 6 ↓+3NaCl
(2) Vulcanization method The purer chlorohydrazine solution (铱 concentration 60-80g/L) is slowly added (NH 4 ) 2 S, Na 2 S or H 2 S at room temperature to make trace impurities of noble and bismuth metals. The sulfide was precipitated, and after standing overnight, a pure chlorinic acid solution was obtained by filtration. Adding ammonium chloride and adding nitric acid or oxidizing with chlorine gas precipitates a black silky (NH 4 ) 2 IrCl 6 crystal:
H 3 IrCl 6 +2NH 4 Cl+0.5Cl 2 =====(NH 4 ) 2 IrCl 6 ↓+3HCl
Base metals and more soluble rhodium ammonium chloride remaining in the mother liquor. If the ammonium chloroantimonate obtained by filtration is not pure enough, it is slurried with water and added with an appropriate amount of hydrazine hydrate to reduce to soluble (NH 4 ) 3 IrCl 6 :
(NH 4 ) 2 IrCl 6 +N 2 H 4 ·H 2 O=====(NH 4 ) 3 IrCl 6 +0.5N 2 ↑+H 2 O
It is re-refined by the vulcanization method, and after passing the chlorine gas, the ammonium chloroantimonate is precipitated by oxidation.
(3) Extraction method The cerium-containing solution is extracted by P 204 to separate the ruthenium metal cation. The noble metal impurity is extracted by N 235 while maintaining the Ir(III) state, and the aqueous phase is oxidized by the chlorine gas to Ir(III) to Ir(IV). Extraction of [IrCl 6 ] 2- with 235 or TBP. The dilute sodium hydroxide solution is back-extracted, the stripping solution is boiled with hydrochloric acid, oxidized by chlorine gas, and ammonium chloride is precipitated by adding ammonium chloride. [next]
2. Metal preparation and product standards Pure ammonium chlorate is dried and heated to 350 ° C for 2 h, and then heated to 600 ° C to decompose the ammonium salt to produce metal bismuth: 
The Chinese metal bismuth product standard (GB1422-89) is shown in the table.