| 摘要 |
<p>The invented process for producing extremely pure and fine platinum is characterized in that pH value of hexachloroplatinic(IV) acid aqueous solution with minimum concentration of 300 ppm is adjusted by addition of an alkali metal bromate or chromate. After boiling the above aqueous solution is diluted and pH value thereof is adjusted by addition of an alkali metal carbonate or hydrogencarbonate whereby insoluble metal hydroxides are precipitated from slightly acid to neutral medium. Subsequently those hydroxides are filtered off and the obtained filtrate is acidified and boiled. The solution can be optionally diluted, alkalized by an alkali metal hydroxide and from warm solution metal hydroxides are precipitated. These are then filtered off and the obtained filtrate is acidified and by addition of ammonium chloride ammonium hexachloroplatinate(IV) is precipitated and in the end the ammonium hexachloroplatinate(IV) reduced at elevated temperature with a mixture of water, ammonium hydroxide and hydrazine under formation of an extremely pure and fine platinum powder.</p> |
