Chevron Research & Technology Company

Chevron U.s.a. Inc.

Chevron Research Company

Other

Michael Dubrovsky

Steven F Sciamanna

Alexander E Kuperman

Gale L Hubred

Paul J Marcantonio

Rahul Shankar Bhaduri

Steven D Lynch

A process for treating acid mine drainage containing heavy metals and soluble contaminants is provided. In one embodiment, at least a metal cation is added to the acid mine drainage at a pre-select pH to form insoluble heavy metal complexes. In one embodiment, the metal cation is a trivalent metal ion, e.g., ferric iron such as in ferric sulfate. In another embodiment, a divalent metal ion such as in ferrous sulfate is used. After the removal of the heavy metal complexes, the effluent water is treated with at least a phosphate additive to remove remaining soluble contaminants, thus producing a treated water stream with reduced levels of contaminants.

Method for treating acid mine drainage

The present invention relates to a chewing gum base formulation comprising a biocompatible particulate polymer having an average particle size of from about 200 &#x3bc;m to about 2000 &#x3bc;m wherein the polymer fibrillates when subjected to a shear stress such as that encountered during chewing.

Chewing gum composition

The present invention provides a method for removing selenium from an aqueous stream by passing the aqueous stream, in combination with a quaternary amine compound, through a filter and recovering a treated aqueous stream which is depleted in selenium content relative to the untreated aqueous stream. The present method removes selenium from an aqueous refinery stream by passing the aqueous stream, in combination with a quaternary amine compound, through a filter that can include clay, cellulose, starch, activated carbon, and the like.

Selenium removal method

A process for removing oily residues from aqueous waste streams using a cross flow filtration system in which the efficiency of a dynamic membrane system comprising a gel layer and supporting semipermeable membrane is optimized by applying a controlled shear force parallel to the plane of the membrane.

Removal of oily residues from aqueous waste streams

Disclosed is a process for recovering precious metals using a combination of smelting and an effective utilization of molten salt chlorination. More specifically, disclosed is a process including the steps of (i) contacting, for example, a matte with a chloride salt containing at least one of potassium, cesium or rubidium, but not sodium or lithium to form a matte/salt solids mixture, (ii) introducing the solids mixture into a chloride melt having a temperature ranging from 300.degree. C. to 650.degree. C., said melt containing at least one of potassium, cesium, rubidium, sodium or lithium, (iii) introducing a chlorine containing gas into the melt, and (iv) maintaining the salt ratio in the matte/salt mixture at a stoichiometrically equivalent amount with the precious metals and base metals contained in the matte. Also disclosed is a selective dissolution technique which involves multiple dissolution stages wherein each stage the oxidation potential is maintained at a certain level and an alkali metal chloride is added such that platinum and palladium can be separately recovered.

Processes for recovering precious metals

A process is disclosed for removing dissolved organics from an aqueous composition, said composition comprising water, carbon dioxide and dissolved organics, and said composition having a pH of 6.5 or less and an inlet organics concentration. The process comprises the steps of feeding said aqueous composition to a centrifugal separation zone, preferably to a hydrocyclone, depressurizing said composition in said centrifugal separation zone to regasify at least a portion of said carbon dioxide. An aqueous product stream is removed from the centrifugal separation zone wherein the concentration of said organics is less than said inlet organics concentration. The process is particularly useful in the cleanup of industrial wastewater, and also for removing organics from water produced in petroleum production operations.

Process for removing dissolved organics from aqueous compositions

The present invention is a process to recover metals from refractory ores. It involves the chlorination of an ore concentrate in the presence of solid salt at a temperature between 300.degree. and 650.degree. C. Thereafter, an oxidation step can be used to convert iron chloride to iron oxide. Subsequent separation steps remove the salt, gangue, and iron oxides. Separate pathways are described for precious and base metal recovery.

Process for recovering metals from refractory ores

The present invention is a process to recover precious metals from sulfide ores. It involves chlorinating a mixture of an ore concentrate and salt to form a liquid melt. The salt preferably contains potassium chloride. This chlorination is carried out at a temperature between 300.degree. and 600.degree. C. while stirring. The process converts precious metals in the elemental and sulfide forms into precious metal chlorides which are recovered by subsequent processing steps.

Process for recovering precious metals from sulfide ores

A process for the reduction of Co.sup.III to Co.sup.II in an aqueous ammoniacal solution in the presence of a porous cathode is disclosed.

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Berkeley, CA, United States of America

Michael Dubrovsky