Treatment of copper refinery slimes

Process for the recovery of gold, silver and selenium from copper refinery slimes containing these metals which comprises:

• treating the raw slimes with a dilute solution of sulfuric acid at a temperature of between about 40.degree. and 100.degree. C. and at a partial pressure of oxygen of between about 5 to 50 lbs. per square inch gauge to obtain a leach solution containing at least about 98% by weight of the copper content of the raw slimes and to obtain a decopperized leach residue containing the gold, silver and selenium content of the raw slimes,
• roasting the leach residue in an oxidizing atmpsphere at a temperature of about 400.degree. to 800.degree. C. for at least about 4 hours to obtain effluent roaster gases containing the selenium content of the raw slimes in the form of selenium dioxide and to obtain a deselenized roaster residue containing the gold and silver content of the raw slimes,
• treating the effluent roaster gases to recover the selenium dioxide content thereof,
• adding dilute hydrochloric acid or nitric acid and ferric chloride to the roaster residue to obtain a slurry containing about 20% by weight solids, and continuously bubbling chlorine and air through the slurry at a temperature of between about 25.degree. to 90.degree. C. for a period of at least about 5 hours to obtain an extraction liquor containing the gold and residual selenium content of the raw slimes and a solid chlorination residue containing the silver content of the raw slimes,
• separating the chlorination extraction liquor from the solid chlorination residue, treating said extraction liquor to recover the gold content thereof and treating said chlorination residue to recover the silver content thereof.