Abstract: A gold recovery pretreatment process is disclosed in which the gold content is more completely extracted from refractory sulfidic ores which contain large quantities of metal carbonates such as dolomite than occurs in traditional gold extraction methods. The process includes treating the ore in an autoclave at elevated temperature and oxygen overpressure conditions in the presence of soda ash or other alkaline materials. The autoclaving of the slurried ore is performed for a sufficient amount of time to oxidize the sulfidic compounds in the ore. The oxidized ore is then more amenable to subsequent conventional gold extraction techniques.

Abstract: Tilting filter pans is disclosed having generally parallel leading and trailing sidewalls which are sloped at an angle to permit increased filtration rates for a predetermined filtering efficiency, and also to permit increased filtering efficiency where the feed rate is constant. The feed is a slurry from which the liquid is removed, and the filter cake being dumped by rotation of each filter pan at a predetermined point of movement of the filter pan along a cyclical path. Hold-down devices having a reduced volume are also used in combination with the improved pan design, so that an increased filtration rate is possible due to decrease in the required filter cake height. A cam arrangement is provided for turning the pans with minimum stress in a minimum length of pan travel, while avoiding collisions between adjacent pans and while permitting washing of each pan.

Abstract: Wet process phosphoric acid, stabilized with respect to the precipitation of solids upon aging, and containing significantly reduced levels of magnesium and aluminum, is prepared by the controlled addition of fluosilicic acid to wet process filter grade phosphoric acid followed by a series of evaporation, crystallization and centrifugation steps. Sufficient fluosilicic acid is added to provide a fluorine to magnesium ratio of about 2.5:1 to 10.1:1, preferably 5:1. The final product, which has a P.sub.2 O.sub.5 content of at least 56 percent, contains low amounts of magnesium and aluminum, and exhibits low solids precipitation characteristics during shipment, storage and eventual processing into end products such a fertilizers.

Abstract: Tilting filter pans having generally parallel leading and trailing sidewalls which are sloped at an angle to permit increased filtration rates for a predetermined filtering efficiency, and also to permit increased filtering efficiency where the feed rate is constant. Drainage of the pans may also be improved. The feed is a slurry from which the liquid is removed, and the filter cake is dumped by rotation of each filter pan at a predetermined point of movement of the filter pan along a cyclical path.

Abstract: A process for placing heat-shrinkable polyfluoroolefin polymer sleeves, preferably, FEP resin or PFA resin, over Frasch sulfur well piping and other downhole well piping to protect such piping from corrosion.A heat chamber for heat-shrinking the polyfluoroolefin polymer sleeves onto the piping.

Abstract: Residual hypochlorite contained in chlorinated slurries of either carbonaceous gold-containing ores or mixtures of carbonaceous and oxide gold-containing ores are reduced by reaction with sulfide ion-providing chemical compounds preferably sodium hydrosulfide, sodium sulfide or hydrogen sulfide. The hypochlorite "kill" step enables subsequent cyanide leach operations to be conducted more efficiently.

Abstract: Phosphate rock contained in an acidic slurry is ground by equipment wherein the acidic slurry contacts the metallic surfaces of the equipment. A method for monitoring and controlling grinding ball consumption is provided in which acid-neutralizing particulate iron contained in the acidic slurry is measured and correlated to control curves, which relate particulate iron concentration to slurry pH and slurry pH to the rate grinding ball consumption. If the measured particulate iron concentration equates to an unacceptable ball corrosion rate, the equilibrium of the slurry pH and particulate iron concentration can be varied to maintain a predictable ball consumption. When making the slurry, waste water from other steps of the wet process manufacture of phosphoric acid can be used as part of an acidic diluting medium.

Abstract: A method for the recovery of precious metals such as gold and silver from various ore types is described which involves subjecting a slurry of the ore to a simultaneous leaching and electrodeposition process by mixing the slurry with a reagent such as an alkaline cyanide solution which provides for the leaching requirement and contacting said slurry with a metallic cathode with a negative electric potential applied thereto providing for the electrodeposition requirement. The cathode is made of a metal selected from the group consisting of cadmium, copper, iron, lead, molybdenum, tin, zinc, cobalt, nickel, silver, titanium, tungsten, vanadium and alloys and mixtures containing at least one of these metals. The simultaneous leaching and electrodeposition occur under conditions controlled to afford at least partial dissolution of the precious metal values from the ore, whereby continuous transfer of the precious metal from the ore onto the surface of the cathode is promoted.

Abstract: An improved method for producing wet process phosphoric acid with low post-precipitation characteristics from an unclarified dilute wet process phosphoric feed acid is described. The feed acid is processed through crystallization, centrifugation and concentration steps under controlled conditions to produce the desired products. The method also allows for the simultaneous production of merchant grade phosphoric acid and clarified merchant phosphoric acid.

Abstract: A pipe coupling is disclosed for connecting two pipelines of different materials together in a high temperature, corrosive environment which, at the same time, prevents deterioration of the pipelines due to galvanic action. The coupling achieves its purpose by using a relatively rigid insulating material to prevent contact between the pipelines. It also achieves high pullout resistance while maintaining minimum outer dimensions to facilitate its use in all types of wells, such as oil, gas, sulfur, etc.

Abstract: The recovery of gold from refractory carbonaceous gold-containing ores by cyanidation techniques is improved by subjecting an oxidized slurry of this type of ores to simultaneous cyanidation and countercurrent granular activated carbon adsorption in two or more stages. The gold transfers to the carbon and may be separated from it by conventional methods.

Abstract: A novel system is disclosed for utilizing, in the mining of subterranean sulfur by the Frasch process, the heat of water that has accumulated underground above at least a portion of the subterranean sulfur deposit from previous mining operations wherein the underground water is brought to the surface, mixed with fresh heated water, and returned underground to melt the subterranean sulfur via a return pipeline which is separate and distinct from the pipeline through which the molten sulfur is brought to the surface. In one embodiment the return pipeline is in the same well casing as the sulfur pipeline, but displaced laterally from it. In a second embodiment, the return pipeline extends through a separate well casing.

Abstract: A method for pretreating phosphoric acid to prevent the formation of a mass of suspended solids (i.e., "crud") during solvent extraction of the acid is described. Prior to solvent extraction, the acid is contacted with a liquid hydrocarbon such as kerosene which collects the crud-forming agents. The mixture of liquid hydrocarbon and collected crud-forming agents is separated from the acid and the liquid hydrocarbon is regenerated for reuse in the first step of the method.

Abstract: A method for handling the problem of crud formation in the solvent extraction of wet-process phosphoric acid is described. Crud is the name ordinarily given to the thick interfacial layer of semi-floatable material which tends to form and accumulate, and which interferes with many of the extraction processes and, in particular, with the solvent extraction of wet-process phosphoric acid. The method described provides for the operation of the solvent extraction stages in a manner that allows the formation and temporary accumulation of crud in those stages whereupon the solvent and the crud are then removed from the extraction stages and treated in a series of operations which include a clarification step, an acid removal step, a water wash step and a caustic treatment step, which steps effectively separate the solvent from the crud, and remove the crud components from the system and regenerate otherwise unusable solvent.

Abstract: A process for the selective separation of ferric iron from an aluminum fluoride aqueous solution containing ferric iron is effected by contacting said solution with an organic extractant phase consisting essentially of a mixture of a mono (higher alkyl-substituted phenyl) phosphoric acid and a di(higher alkyl-substituted phenyl) phosphoric acid dissolved in an inert diluent to thereby transfer the ferric iron to said organic extractant phase. The efficiency of the process is further improved by adjusting the aluminum fluoride aqueous feed solution to a temperature in the range of about 140.degree. F. to about 175.degree. F. prior to contacting it with the organic extractant phase, maintaining the temperature within this range throughout the ferric iron extraction stage or stages, then heating the resulting iron-depleted aqueous raffinate to a temperature higher than 195.degree. F., and then crystallizing aluminum fluoride trihydrate out of the raffinate at this higher temperature.

Abstract: Novel method and apparatus for utilizing, in the mining of subterranean sulphur by the Frasch process, the heat of water that has accumulated underground above at least a part of said subterranean sulphur from previous mining operations comprising subterraneanly recycling said accumulated underground water downwardly to contact and heat additional solid subterranean sulphur. In one embodiment further heat is added to the accumulated underground water. For example, pressurized, superheated drive water generated above ground is subterraneanly commingled with said accumulated underground water in a jet pump or ejector to further heat it and to recycle it subterraneanly.

Abstract: An integrated system and process is provided to heat and chemically treat an aqueous process fluid such as the water required for producing sulfur by the Frasch process without undue scaling and corrosion of apparatus when a sulfur-containing fuel such as oil is employed as the energy source.

Abstract: An apparatus and method are provided for handling the problem of crud formation in solvent extraction equipment. "Crud" is the name commonly given to the thick interfacial layer of semi-floatable material that accumulates and interferes with many solvent extraction operations.The apparatus disclosed is used in combination with mixer-settler equipment, and it includes a rotatable shaft, a blade mounted on the shaft, apparatus for moving the shaft and blade across a plane parallel to the surface of the liquid inside a rectangular settler vessel, equipment for rotating the blade and shaft about the shaft's longitudinal axis, and a locking device for locking the blade into an extended or retracted position.

Abstract: A method is disclosed for sealing a sulfur well wherein the well is made to discharge only sulfur and air instead of mixtures of sulfur, water and air. The method is used in conjunction with the Frasch mining technique when starting a new well for the first time and when an active well has "blown". The method consists of shutting off the sulfur line and air line, "boosting" the well by sending down hot "superheated water" through the water line to raise the level of the sulfur pool by melting additional sulfur, slowly applying a pressurized gas to the top of the sulfur line and holding at an elevated pressure for a period of time and then slowly releasing the pressurized gas. The air line is then opened and pressurized, and a mixture of sulfur and air, devoid of water, exits through the sulfur line.

Abstract: An integrated sulfur mining -- sulfuric acid production system is provided wherein a portion of the sulfur produced in the mining operation is consumed in a sulfuric acid manufacturing plant which also generates sufficient heat to raise the temperature of the aqueous mining fluid to the level required by a mining operation of the type that uses the Frasch sulfur mining technique.