Abstract: A process for treatment of precious metal ores in which gold is leached from an oxidized ore slurry using a thiosulfate salt lixiviant and copper catalyst. Gold and copper are subsequently loaded onto an ion exchange resin. Copper is recovered from the resin by elution with a thiosulfate solution; gold is recovered from the resin by elution with a thiocyanate colution. Gold is recovered from the eluate by precipitation, electrowinning, or cementation.

Abstract: Provided is a method for processing a gold-bearing sulfide ore which involves maintaining the ore in a substantially oxygen free environment, preferably beginning with comminution of the ore and ending when a desired final concentrate, enriched in sulfide minerals, is obtained by flotation. In one embodiment, nitrogen gas is used to substantially prevent contact between the ore and air during comminution of the ore and during flotation operations. It is believed that oxygen gas present in air detrimentally affects the recovery of sulfide minerals in a flotation concentrate through surface oxidation of sulfide mineral particles. The use of a gas such as nitrogen can significantly reduce the potential for such surface oxidation.

Abstract: Provided is a process for treating refractory precious metal-containing ores, particularly gold-bearing ores, which are refractory due to the presence of organic carbon, to reduce the ability of organic carbon to interfere with recovery of the precious metal. The ore may also contain sulfide materials with which the gold is associated and from which the gold is difficult to separate. The ore is comminuted to a size at which at least about 80 weight percent of the ore is smaller than about 40 microns in size. The comminuted ore is then slurried and subjected to pressure oxidation at severe operating conditions. The treating temperature is greater than about 190.degree. C. When sulfide minerals are present, substantially all of the sulfide sulfur must first be oxidized prior to obtaining significant benefit from the treatment of the organic carbon. Greater than about 96% of the sulfide sulfur must be oxidized.

Abstract: A process for recovering gold in which an ore slurry of refractory sulfidic and refractory carbonaceous ore having preg-robbing characteristics due to the presence of organic carbon is subjected to pressure oxidation in an autoclave. The oxidized ore slurry is mixed with a thiosulfate salt lixiviant, which mixture is maintained at a pH between 7 and 8.7 while the slurry is agitated in a stirred tank reactor system having agitated leach tanks. Gold is recovered from the gold-bearing leachate by cementation, adsorption on an adsorbent, or cyanidation.

Abstract: A process for recovering gold from a refractory auriferous ore containing sulfide sulfur. An aqueous slurry of refractory auriferous ore is subjected to pressure oxidation in an autoclave while the distribution of oxygen to the various compartments of the autoclave is controlled in order to achieve increased oxygen utilization.

Abstract: A process is provided for recovering gold from refractory sulfide ores. Preferred feed materials have multiple different sulfide mineralogies, with gold being primarily contained within one or more, but not all, of the sulfide mineralogies. Sulfide mineralogies with the highest gold values are preferentially oxidized, while those sulfide mineralogies with relatively little gold remain largely unoxidized. In one embodiment, dissolved arsenic following pressure oxidation is precipitated as ferric arsenate through the control of pH during neutralization. In another embodiment, the oxidized slurry following pressure oxidation is contacted with an oxidizing agent to convert at least a portion of ferrous iron to ferric iron. Following, pressure oxidation, the slurry can be subjected to cyanidation recovery of gold, and liquid from the tailings stream can be recycled upstream of the pressure oxidation step in a substantially untreated form.

Abstract: An oil-burning furnace including a combustion zone, an air passageway through which air is routed to the combustion zone, an air compressor for moving the air through the combustion zone in a pressurized condition and an oil passageway through which oil is routed to the combustion zone for burning in the presence of air utilizes a shutoff assembly for positively shutting of the flow of oil through the fuel passageway upon shutdown of the furnace operation. The shutoff assembly is associated with the air passageway and is actuated in response to a drop in the pressure of air in the air passageway below a preselected level. Thus, the actuation of the shutoff means is coordinated with the de-energizing of the air compressor. In addition, the oil passageway is adapted to shut off the flow of oil at a location along the passageway which is disposed in relatively close proximity to the combustion zone.

Abstract: An oil-burning furnace including a combustion zone and a nozzle block assembly through which oil and pressurized air are introduced into the combustion zone utilizes an oil pump of trochoidal design for delivering oil to the combustion zone at a metered rate and a purge control for withdrawing oil from the nozzle block assembly upon shut down of the furnace operation. The flow rate at which the oil pump delivers the oil to the nozzle block assembly is relatively constant regardless of the weight or viscosity of the oil burned by the furnace, and the purge control cooperates with an air compressor used for delivering air, under pressure, to the nozzle block assembly and includes an expandable zone for extracting oil from the nozzle block assembly upon a de-energizing of the air compressor.

Abstract: A furnace including an elongated housing having an air intake adjacent one end of the housing and an air discharge vent adjacent the other end of the housing utilizes a substantially U-shaped heat exchanger positioned within the housing and a partition supported within the housing so as to separate the interior of the housing into first and second zones. A fuel burner assembly directs a flame and attending combustion products into one leg section of the heat exchanger so that the heat generated by the flame and combustion products are absorbed through the inside surfaces of both leg sections. The furnace also includes a fan so that a fraction of the air move through the first zone and absorbs heat from the outer surfaces of the one leg section and so that a remainder of the air moves through the second zone and absorbs heat from the other surfaces of the other leg section. The partition provides a first and a second opening through which the first and second zones communicate with one another.

Abstract: A cylindrical tank (12) is formed from stainless steel plates. Proximate an open top end (17) of the tank (12) are four evenly spaced mixing assemblies (20). An intake pipe (22) is positioned with an open end (38) below the surface of a biological conversion medium (16) to allow a pump (28) to draw the medium (16) into a receiving box (24). A downcomer (26) merges with the receiving box (24) in order to allow the medium (16) to be injected with a biological conversion component such as air through an inlet pipe (34). The medium (16) and the injected component then pass through a static in-line mixer (30) which thoroughly mixes the medium (16) with the component and creates a multitude of finely-divided air bubbles for circulation and feeding of the medium (16) throughout the tank (12).

Abstract: A cylindrical tank (12) is formed from stainless steel plates. Proximate an open top end (17) of the tank (12) are four evenly spaced mixing assemblies (20). An intake pipe (22) is positioned with an open end (38) below the surface of a biological conversion medium (16) to allow a pump (28) to draw the medium (16) into a receiving box (24). A downcomer (26) merges with the receiving box (24) in order to allow the medium (16) to be injected with a biological conversion component such as air through an inlet pipe (34). The medium (16) and the injected component then pass through a static inline mixer (30) which thoroughly mixes the medium (16) with the component and creates a multitude of finely-divided air bubbles for circulation and feeding of the medium (16) throughout the tank (12).

Abstract: A process for the biological oxidation of sulfide in sulfide-containing ore. Preferably, the ore is then subjected to cyanide leaching. The resulting leach tail solution can be subjected to cyanide precipitation, employing ferric sulfate which is generated during the biological oxidation step of the process. Furthermore, a process for efficiently aerating the ore slurry during the biological oxidation step is provided.

Abstract: A thin lightweight strip of booklets and method of making the same are disclosed. The booklets are comprised of one elongated sheet folded in thirds, then in half, then in half to define pages of the same size without the use of fasteners. The booklets are connected end to end to form a strip which is separable along perforation lines. The strip of booklets has a fold line between and adjacent the free ends of said sheet along one edge of said strip and only fold lines along the opposite edge of said strip. The strip of booklets is adapted to be sealed within an envelope.