Process for removal of arsenic from sulfo-ore

Claim 2

A process according to claim 1 wherein said leaching solution is a hot solution of sodium sulfide containing from about 100 to about 600 grams per liter of sodium sulfide.

Claim 3

A process according to claim 3 wherein said leaching solution is at a temperature of from about 75* to about 105*C and said leaching is carried out for from about 4 to about 12 hours.

Claim 4

A process according to claim 1 wherein said acidifying gas is sulfur dioxide.

Claim 5

A process according to claim 5 wherein said pH is reduced to about 9 to about 11, any precipitated residue filtered off and recovered and thereafter the pH further reduced to about 2 to about 6.

Claim 6

A process according to claim 1 wherein said precipitated salts are roasted to a temperature of from about 150* to about 600*C.

Claim 7

A process according to claim 1 wherein said solid residue is roasted to a temperature of from about 850* to about 1,200* C for from about 3 to about 6 hours in the presence of a reducing agent.

Claim 8

A process according to claim 8 wherein said reducing agent is pulverized coal.

Claim 9

A process for the removal of arsenic from ore concentrates containing the same which comprises the steps of leaching said ore concentrate with a solution containing from about 100 to about 600 grams per liter of sodium sulfide at a temperature of from about 100* to about 105* C to form an arsenic pregnant solution and an insoluble residue; separating said arsenic pregnant solution from said residue; treating said arsenic pregnant solution with sulfur dioxide gas to reduce thE pH to about 9 to about 11 to precipitate gold compounds therefrom; separating the precipitated gold compounds; further reducing the pH of the solution with sulfur dioxide gas to about 3-4 to precipitate arsenic compounds and to form an arsenic barren solution; separating and discarding said arsenic compounds; evaporating said arsenic barren solution to crystallize salts therefrom; roasting said crystallized salts in the presence of oxygen at a temperature of from about 400* to about 500* C to form a recycle dioxide and a solid residue; recycling said sulfur dioxide to the process; furnacing said solid residue at a temperature of from about 850* to 1,200* C in the presence of carbon to recover solid sodium sulfide therefrom; dissolving solid sodium sulfide in water to form a solution thereof; and recycling sodium sulfide solution to the process.