Abstract: The present invention is directed to a precious metal recovery process in which carbonaceous material, such as preg robbing carbon, is floated after sulfide oxidation to separate the carbonaceous material from the precious metal.

Abstract: The present invention is directed to flotation of refractory gold sulfide ores in which the ore is ground, floated, the tailings reground, and refloated to produce gold-bearing concentrates.

Abstract: A method for suppressing mercury dissolution during pressure oxidation of precious metal-containing materials in the presence of halogens and halides is provided. Pressure oxidation is performed under controlled oxidative conditions to maintain the mercury predominantly in the solid residue.

Abstract: In the process of recovering platinum group metals from platinum group metal- and base metal-containing materials, the present invention uses reductants and a sulfur-deficient matte to aide the separation of the furnace matte from the furnace slag and therefore improve recovery of platinum group metals.

Abstract: The present invention is directed to flotation of refractory gold sulfide ores and to pressure oxidized residue neutralization using flotation tailings that have been contacted with an off gas of pressure oxidation.

Abstract: A method for recovering zinc ions by selective zinc sulfide precipitation from an aqueous solution comprising zinc ions and metal ions of a metal that precipitates as a metal sulfide at a pH lower than a pH at which zinc ions precipitate as a zinc sulfide.

Abstract: The present invention is directed to a precious metal recovery process in which basic ferric sulphates and/or jarosites are controlled by hot curing of the autoclave discharge slurry followed by decomposition of argentojarosite using strong acid consumers.

Abstract: The present invention is directed to a multi-compartment autoclave using inter-compartment dividers having one or more underflow openings for passing a feed stream between compartments.

Abstract: Precious metal recovery by thiosulfate leaching where thiosulfate lixiviant is generated in situ employing elemental sulfur generated from partial oxidation of sulfidic precious metal-bearing feed and/or employing reactants from processing effluent.

Abstract: A process for the recovery of arsenic trioxide from acid solutions, particularly the aqueous acid effluent produced by a gas-washing process in the pyrometallurgy of copper sulfide ores is provided. Generally, the process comprises concentrating the acid solution in one or more evaporators in series; crystallizing arsenic contained in the concentrated solution as arsenic trioxide crystals; filtering the crystallized solution to obtain a solid phase comprising impure arsenic trioxide crystals; and purifying the solid phase to obtain a purified crystal product comprising arsenic trioxide. The process produces a commercially salable arsenic trioxide product without producing any solid or liquid residues subject to special handling or treatment regulations.

Abstract: A wear-resistant flash tank pressure let down nozzle for use in passing an ore slurry into an ore slurry flash tank to release steam from the slurry and reduce the pressure of the slurry. The nozzle has an expansion cone flaring toward the discharge end of the nozzle. The cross-sectional area of a choke section of the nozzle and the exit diameter of the expansion cone are selected to establish a relationship between pressure upstream of the nozzle and pressure in the flash tank so that underflashing, overflashing, and shock waves inside the flash tank are minimized.

Abstract: A flame retention head for a nozzle block assembly of a waste oil-burning system, such as a furnace, having a combustion zone within which oil is burned in the presence of air utilizes a platen-like body of substantially circular form having a central opening through which an atomizing nozzle is positioned for directing air and oil into the combustion zone for burning. The central opening has a diameter of no less than about 1.3 inches, and the platen-like body including a plurality of radially-extending vanes formed therein wherein each vane forms with the remainder of the platen-like body a gap which is joined to and extends radially-outwardly of the central opening. Each gap formed by a vane has a width which is no less than about 0.07 inches. Associated with the nozzle block assembly is at least one air vane for balancing the air flow moving past the flame retention head and toward the combustion zone.

Abstract: A process for recovering gold from thiosulfate leach solutions and slurries in which gold is loaded into an ion exchange resin. Gold is recovered from the resin by elution with polythionate ions and the resin is regenerated with sulfide or sulfite. Gold is recovered from the eluate by precipitation with sulfide ions, cementation or electrowinning. The invention also provides for a process of manufacturing polythionate ion solutions suitable for eluting gold from ion exchange resins.

Abstract: A process for reducing boron and/or fluoride ion content of water. Feed water is contacted, in the presence of magnesium, with an alkaline hydroxide to produce treated water and a magnesium precipitate containing boron and fluorine. The precipitate is separated from the treated water. The boron content of water is reducible from above about 0.8 mg/L to below about 0.7 mg/L, and the fluoride ion content is reducible from above about 1 mg/L to below about 0.9 mg/L. The magnesium precipitate is optionally used to neutralize pressure oxidized ore slurry or roaster calcine in the context of gold recovery operations.

Abstract: A method for controlling a froth flotation system in a mineral processing operation for recovering metal from a metal source. A rule-based expert system adjusts performance of the froth flotation system.

Abstract: A wear-resistant flash tank pressure let down nozzle for use in passing an ore slurry into an ore slurry flash tank to release steam from the slurry and reduce the pressure of the slurry. The nozzle has an expansion cone flaring toward the discharge end of the nozzle. The cross-sectional area of a choke section of the nozzle and the exit diameter of the expansion cone are selected to establish a relationship between pressure upstream of the nozzle and pressure in the flash tank so that underflashing, overflashing, and shock waves inside the flash tank are minimized.

Abstract: A process for reducing boron and/or fluoride ion content of water. Feed water is contacted, in the presence of magnesium, with an alkaline hydroxide to produce treated water and a magnesium precipitate containing boron and fluorine. The precipitate is separated from the treated water. The boron content of water is reducible from above about 0.8 mg/L to below about 0.7 mg/L, and the fluoride ion content is reducible from above about 1 mg/L to below about 0.9 mg/L. The magnesium precipitate is optionally used to neutralize pressure oxidized ore slurry or roaster calcine in the context of gold recovery operations.

Abstract: A cement composition for use in acidic environments containing an acid resistant particulate aggregate of fused mullite aggregate or other aggregate material, with quartz, and microsilica in combination with a colloidal silica sol binder and being substantially free of Na compounds and K compounds which react in the presence of sulfuric acid to form alkali sulfates in service, thus reducing the durability or the service life.

Abstract: A fuel control and preheating module for use with an oil-burning furnace including a fuel line providing a passageway section through which oil is routed from a reservoir to the furnace for burning includes an electrically-powered positive temperature coefficient (PTC) heating element mounted in heat transfer relationship with oil contained with the passageway section. During the operation of the PTC element, the PTC element heats the oil contained within the passageway section to a preselected temperature and maintains the oil contained within the passageway section at the preselected temperature. Also associated with the module is a movable diaphragm and shutoff plate which is responsive to the internal pressure changes in the air passageway of the furnace upon shutdown and start-up of the furnace to withdraw oil from and shut off delivery of oil to the nozzle upon furnace shutdown and to push oil toward the nozzle upon start-up of the furnace.