Union Carbide Corporation

U.S. Vanadium Corporation

Praxair Technology, Inc.

John B Goddard

Donald J Hansen

Michael M Litwin

Rodney F Merkert

Sateria Salim

Oreste J Malacarne

William N Johnson

The method measures hydrogen sulfide concentrations in hydride gases in a sealed vessel. The sealed vessel has a gas inlet to receive a stream of hydride gas, a gas outlet to remove the stream of hydride gas and a metal acetate substrate. The stream of hydride gas contains a concentration of hydrogen sulfide gas. Introducing the stream of hydride gas through the gas inlet contacts the acetate substrate with the stream of hydride gas. Reacting the hydrogen sulfide gas contained in the stream of hydride gas with the acetate substrate modifies optical properties of the acetate substrate. Then measuring the optical properties of the acetate substrate determines the concentration of the hydrogen sulfide gas contained in the stream of hydride gas.

Analysis of hydrogen sulfide in hydride gases

Vanadium is recovered from vanadium-containing ores that have been roasted in the presence of a sodium source through heap leaching with an aqueous leaching solution so that high grade leach liquors can be obtained.

Method for recovering vanadium from vanadium-containing ore

A process is provided for the recovery of vanadium values from vanadium-bearing residues, such as fly ash, boiler ash and scrubber residues from the combustion of crude oil fractions. The process employs a combination of alkaline metal bases, such as sodium carbonate and sodium hydroxide.

Alkaline leaching of vanadium bearing residues

A low-carbon vanadium nitride is prepared in a furnace at an elevated temperature of about 1400.degree. C. under nitrogen atmosphere from a feed material containing a mixture of vanadium oxynitride and carbon. The vanadium oxynitride is prepared by the partial ammonia reduction of a vanadium-containing oxidic compound such as ammonium metavanadate (NH.sub.4 VO.sub.3) or oxides of vanadium such as V.sub.2 O.sub.3 and V.sub.2 O.sub.5.

Preparation of low-carbon vanadium nitride

A spent or scrap tungsten-containing, aluminosilicate catalyst material is blended with a silicate-containing, tungsten-bearing ore concentrate in amounts such that at least about 2.0% by weight of the total tungsten values in the mixture are present in the catalyst material, and then digested with an alkaline solution, e.g., sodium carbonate, under pressure and at an elevated temperature for a period of time sufficient to extract substantially all of the tungsten values from the mixture components. The presence of the catalyst material substantially suppresses the dissolution of silica in the leach liquor.

Extraction of tungsten from spent or scrap catalyst materials

A process is provided for extracting vanadium values from a vanadium-bearing ore in which a carbonaceous material is added to a salt roast mixture containing ore and an alkali metal salt, e.g., NaCl. The mixture is subjected to roast temperatures (e.g., 825.degree. C.) for a period of time sufficient to burn off substantially all of the carbon in the mixture. The carbonaceous material is preferably a vanadium-containing carbon source, e.g., residue from the combustion of heavy petroleum oil.

Salt roasting of vanadium ore in the presence of carbon

Prior to evaporative crystallization of ammonium tungstate solutions to give ammonium paratungstate (APT), an aluminum compound, e.g. aluminum sulfate solution, is added to precipitate silicon and phosphorus impurities. The yield of crystallized ammonium paratungstate is thereby increased.

Purification of ammonium tungstate solutions

Method of electrodepositing manganese metal from a manganese metal electrolyte which contains small quantities of sulfur dioxide, selenium and a polyacrylamide compound. The electrodeposited manganese is smoother and exhibits less 'treeing', i.e. dendritic growths and high current efficiencies are achieved.

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Grand Island, NY, United States of America

John B Goddard