High temperature pressure oxidation of ores and ore concentrates containing silver using controlled precipitation of sulfate species
AssigneeNewmont USA Limited
InventorsGary L. Simmons, John C. Gathje
Life of this patent
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Abstract
A method for the treatment of sulfide ores containing silver by pressure oxidation. The method includes the addition of a sulfate-binding material to reduce the formation of jarosite species during pressure oxidation. Silver can then be recovered from the solids portion of the discharge slurry. A jarosite reduction step, such as by a lime boil, that is typically required to recover silver after pressure oxidation can advantageously be eliminated.
Claims75
A method for processing a mineral feed comprising iron, sulfide sulfur and silver to facilitate recovery of silver, comprising the steps of:
- (a) pressure oxidizing an aqueous feed slurry comprising said mineral feed wherein at least about 70 percent of sulfide sulfur in said mineral feed is converted to sulfate sulfur;
- (b) recovering from said pressure oxidizing step an aqueous discharge slurry comprising discharge solids and aqueous discharge liquid, said discharge solids comprising at least a portion of said silver and at least apportion of said iron from said mineral feed;
- and
- (c) leaching at least a portion of said discharge solids with a leach solution to dissolve into the leach solution at least a portion of said silver from said discharge solids;
- wherein the concentration of dissolved iron in said discharge slurry is not greater than 1 gram of dissolved iron per liter of aqueous discharge liquid.
A method for the treatment of a mineral feed comprising iron, sulfide sulfur and silver, comprising the steps of:
- (a) pressure oxidizing an aqueous feed slurry comprising said mineral feed at a temperature of at least about 160° C.;
- and
- (b) withdrawing a discharge slurry from said pressure oxidation step comprising discharge solids and a discharge liquid,
- wherein said pressure oxidizing step is conducted in the presence of a sufficient concentration of a sulfate-binding material comprising a compound selected from the group consisting of carbonates, hydroxides and oxides of metals selected from the group consisting of calcium, sodium, potassium and magnesium such that at least about 75 percent of said silver contained in said mineral feed is discharged in said discharge solids and not greater than 25 wt. % of the silver contained in said discharge solids is associated with jarosite species.
A method for recovering silver from a mineral feed comprising sulfide sulfur, iron and silver, comprising the steps of:
- (a) pressure oxidizing an aqueous slurry comprising said mineral feed in the presence of oxygen gas to convert at least 80 percent of the sulfide sulfur in the mineral feed to sulfate sulfur, said pressure oxidizing step being conducted at a temperature of at least 210° C.;
- (b) recovering from said pressure oxidizing step a discharge solids comprising at least a portion of said iron and a portion of said silver from the mineral feed;
- and
- (c) leaching at least a portion of said silver from discharge solids recovered from said pressure oxidizing step;
- wherein not greater than 25 wt. % of the iron in said discharge solids is contained in sulfate-containing compounds.
A method for recovering silver from a mineral feed comprising silver, sulfide sulfur and iron, comprising the steps of:
- (a) pressure oxidizing said mineral feed in a reactor at a temperature of at least 190° C. to oxidize at least 90 percent of the sulfide sulfur in said mineral feed to sulfate sulfur and to produce silver-containing discharge solids;
- and
- (b) leaching at least a portion of said discharge solids with a leach solution to dissolve at least a portion of the silver into said leach solution;
- wherein said pressure oxidizing step comprises:
- (i) feeding an aqueous feed slurry comprising said mineral feed to said reactor;
- (ii) feeding an sulfate-binding material to said reactor separate from said feed slurry;
- and
- (iii) withdrawing from said reactor an aqueous discharge slurry comprising said discharge solids.
A method for recovering silver and a non-ferrous base metal from a mineral feed comprising sulfide sulfur, iron, silver and a non-ferrous base metal, with at least a portion of said non-ferrous base metal being contained in one or more sulfide minerals, comprising the steps of:
- (a) pressure oxidizing said mineral feed, the pressure oxidizing comprising:
- (i) feeding an aqueous feed slurry comprising said mineral feed to a reactor;
- (ii) feeding oxygen gas to the reactor;
- (ii) in the reactor, oxidizing at least 90 percent of the sulfide sulfur in the mineral feed to sulfate sulfur;
- (iii) dissolving at least 90 wt. % of the non-ferrous base metal from the mineral feed into aqueous liquid in the reactor;
- (iv) discharging from the reactor an aqueous discharge slurry comprising discharge solids and an aqueous discharge liquid, the discharge solids comprising at least 85 wt. % of the silver from the mineral feed and the aqueous discharge liquid having dissolved therein at least 90 wt. % of the non-ferrous base metal from the mineral feed;
- (b) after said pressure oxidizing step, separating the discharge solids from the aqueous discharge liquid;
- (c) after said separating step, processing the aqueous discharge liquid to remove at least a portion of the non-ferrous base metal from the aqueous discharge liquid and separately processing the discharge solids to remove at least a portion of the silver from the discharge solids;
- wherein, during said pressure oxidizing, the reactor is maintained at a temperature of at least 190° C. and dissolved iron in the discharge slurry is maintained at a concentration of not greater than 1 gram of dissolved iron per liter of the discharge liquid.
Dependencies are inferred from the claim text.