Abstract: Molybdenum trioxide is produced from molybdenite by a pressure oxidation process comprising of the steps of forming an aqueous slurry of molybdenite, pressure oxidizing the slurry to form soluble and insoluble molybdenum species, converting the insoluble molybdenum species to soluble molybdenum species by alkaline digestion, separating the soluble molybdenum species from insoluble residue contaminants (if present), removing the molybdenum species from the aqueous media through solvent extraction, and recovering the molybdenum values as molybdenum trioxide from the organic solvent. Low grade molybdenite concentrates, including concentrator slimes containing talc and sericite, can be used as a feed. The process produces technical grade molybdenum trioxide.

Abstract: A copper alloy plumbing fixture containing interdispersed lead particles coated non-continuously on a water contact surface to resist the leaching of lead into potable water systems. The leach resistant fixture is prepared by immersing conventional copper alloys in a bismuth nitrate solution, selectively and non-continuously coating the lead dispersoid particles on the water contact surface with bismuth, tin or copper.

Abstract: A copper alloy plumbing fixture containing interdispersed lead particles coated noncontinuously on a water contact surface to resist the leaching of lead into potable water systems. The leach resistant fixture is prepared by immersing conventional copper alloys in a bismuth nitrate solution, selectively and noncontinuously coating the lead dispersoid particles on the water contact surface with bismuth. Tin may be substituted for bismuth to obtain similar results.

Abstract: A copper alloy plumbing fixture containing interdispersed lead particles coated noncontinuously on a water contact surface to resist the leaching of lead into potable water systems. The leach resistant fixture is prepared by immersing conventional copper alloys in a bismuth nitrate solution, selectively and noncontinuously coating the lead dispersoid particles on the water contact surface with bismuth. Tin may be substituted for bismuth to obtain similar results.

Abstract: The present invention provides a novel method of extracting zinc from geothermal brines and synthetic brines which can be performed in a continuous, in-line process.

Abstract: A process is provided for removing cyanide from a dilute cyanide solution. The solution is passed through a weak base anion exchange resin to absorb cyanide complexes. The resin is eluted with a weakly basic Ca(OH).sub.2 solution, to produce a cyanide-rich eluate. Elution is accomplished by recycling the eluting fluid past a bed of solid Ca(OH).sub.2, to maintain the eluting fluid in Ca(OH).sub.2 saturation. Recycling in this manner produces an eluate with relatively high cyanide concentration using economical reagents. The eluate is subjected to an acidification/volatilization process including acidification, preferably with H.sub.2 SO.sub.4, heating by introduction of steam and removal of volatilized HCN by an air sparge. The HCN-rich off-gas and slats produced therefrom may be recycled in the process. The cyanide-depleted waste streams may be disposed of in, for example, tailings ponds.

Abstract: The invention comprises the treatment of metal oxides and mixed metal oxides and metal sulfides in a vertical tube reactor system having a downcomer section and a riser section in order to oxidize and dissolve the metal values in aqueous slurry primarily in the downcomer section and introducing a reducing agent comprising a formate species and reducing the dissolved metal values in the riser section. The reduced metal values are then separated with the gangue values from the product solution downstream from the vertical tube reactor system. The reduced metal values may then be separated from the gangue material by conventional solid separation techniques, such as flotation.

Abstract: An arsenic-recovery process primarily for use in conjunction with the hydrometallurgical processing of arsenic-containing materials for metal recovery. Arsenic is recovered from ferric arsenate by reaction with sodium hydroxide in accordance with the following general reaction:3NaOH+FeAsO.sub.4 .fwdarw.Na.sub.3 AsO.sub.4 +Fe(OH).sub.3During the processing of high arsenic materials such as smelter flue dust, extremely insoluble ferric-arsenic compounds are generated to immobilize the arsenic during leaching of the metals. The arsenic may be recovered in saleable form from the arsenic-containing residues by leaching with sodium hydroxide and crystallizing the arsenic salts from the leach residue.

Abstract: An improvement in the hydrometallurgical recovery of metals, such as, lead, silver, gold, antimony, and bismuth from materials such as flue dust in the presence of arsenic, comprising precipitating arsenic as an insoluble ferric-arsenic compound in the first processing step, carrying the insoluble arsenic compound through a chloride leach step, in which it is insoluble, to recover the metals, and disposing of the residue in which the arsenic has been fixed with ferric ions to render it non-polluting, or alternatively, recovering the arsenic by caustic leach and crystallization.

Abstract: An improvement in hydrometallurgical recovery of metals, i.e. copper, zinc, cadmium, germanium, indium, lead, silver, gold, antimony and bismuth from materials such as flue dust containing arsenic in which the metals are selectively separated in successive process steps for final recovery, the improvement comprising precipitating arsenic as an insoluble ferric-arsenic compound in the first processing step, carrying the insoluble arsenic compound through subsequent processing steps in which it is insoluble until the other metals have been recovered leaving the ferric-arsenic compound as the final residue which can be disposed of without violating pollution requirements or converted to soluble sodium arsenate and recovered from solution by crystallization.

Abstract: A process is disclosed for treating mixed metal sulfides containing trivalent antimony sulfide wherein the sulfide concentrates are leached with an excess of sodium sulfide in order to isolate copper sulfide and other insolubles in solid form while solubilizing the remaining metal sulfides and producing sodium thioantimonite, separating the insoluble sulfides from the solution; oxidizing the sodium thioantimonite with elemental sulfur to produce sodium thioantimonate in solution; crystallizing a portion of the sodium thioantimonate along with other available metal sulfides from solution; and recirculating the remainder of the solution to the sodium sulfide leach stage. The crystallized metal sulfides may be further treated, isolated, and recovered as desired.

Abstract: A process is disclosed for separating antimony sulfides from solutions comprising anitmony sulfides and arsenic sulfides by subjecting the solution to partial oxidation within prescribed pH limits in order to oxidize and precipitate a substantial portion of the antimony sulfides while leaving substantially all of the arsenic sulfides in solution.

Abstract: An improvement in conventional processes for recovering metal values from sulfide ores containing lead, zinc and silver sulfides in which process the metal sulfides are converted to chlorides by chlorination followed by solubilization of the chlorides with a sodium chloride leach and subsequent recovery of the metals from their chlorides in accordance with a conventional flow sheet including crystallization, cementation, precipitation, fused salt electrolysis, etc., with chlorine being recovered for reuse by electrolysis of the sodium chloride leach solution substantially depleted of lead, silver and zinc, the improvement being a pollution-free process which comprises:1. recycling the sodium chloride solution depleted of a major percentage of lead and silver to the sodium chloride or brine leaching step; and2.

Abstract: Copper is recovered from chalcopyrite by means of a pollution-free hydrometallurgical process which entails leaching and converting the chalcopyrite with copper sulfate in order to produce an insoluble copper sulfide, a soluble iron sulfate and sulfuric acid. A secondary leach is then conducted in order to react the copper sulfide with oxygen in the presence of a jarosite-forming cation to produce a soluble copper sulfate and an insoluble iron bearing jarosite. This copper sulfate is separated from the jarosite and sent to a copper recovery process and/or recycled. Alternatively, the copper sulfide from the initial leach may be separated from the iron sulfate solution immediately after the initial leach, and this copper sulfide can be treated with other processes to produce elemental copper and sulfur.