Amax Incorporated

Richard A Ronzio

Robert C Ziegler

Michael A Vertes

Deepak Malhotra

Phillip K Davis

Maurice R Hoover

Fred N Oberg

Joseph G Brown

R Stanley Rickard

Fredrick N Bender

Tommy C Kearns

A process for producing a high grade molybdenum disulfide powder suitable for use in the formulation of chemicals and as an intermediate for synthesizing high purity molybdenum compounds by which an impure particulated molybdenite concentrate feed material is pulverized and thereafter is subjected to a plurality of purification treatments to effect a progressive extraction of the contaminating mineral constituents entrapped within the molybdenite particles. The purification treatments comprise a wash treatment of the molybdenite concentrate containing up to 10% by weight of hydrocarbon oil employing an aqueous solution forming a slurry which is subjected to successive steps of high shear agitation and low shear agitation to break up the agglomerated molybdenite particles and to effect a release of the mechanically entrapped very fine mineral particles which remain suspended in the aqueous liquid phase. At the completion of the high and low shear treatment, the slurry is transferred to a separator in which the agglomerated molybdenite particles are extracted from the predominant portion of the liquid phase which contains a substantial proportion of the released mineral contaminants. The molybdenite concentrate and the aqueous wash solution are transferred through the plurality of purification treatments in a countercurrent fashion. The resulting agglomerated molybdenite concentrate, free of the contaminants, is then subjected to regular froth flotation to remove any coarse contaminants.

Process for producing high grade molybdenum disulfide powder

A process for producing a high purity ammonium heptamolybdate and/or ammonium dimolybdate product by which a particulated molybdenum oxide concentrate is purified to remove contaminating metal cations, whereafter it is leached with an ammoniacal leach solution to extract the molybdenum trioxide constituent therein as soluble ammonium molybdate compounds. The resultant ammoniacal leach solution is thereafter concentrated at an elevated temperature, whereafter at least a portion thereof is adjusted to provide an ammonia-to-molybdenum trioxide mol ratio ranging from about 0.86:1 to about 1.25:1, and the adjusted solution thereafter is cooled to effect a precipitation of ammonium heptamolybdate crystals which are separated and recovered, and the balance of the cooled solution is recirculated for admixture with additional ammoniacal leach solution. A portion of the concentrated ammoniacal leach solution can be further concentrated by evaporation to effect crystallization of ammonium dimolybdate which is separated and recovered.

Process for producing ammonium heptamolybdate and/or ammonium dimolybdate

A process for purifying an impure molybdenum oxide concentrate feed material to remove therefrom the predominant portion of contaminating metals present by autoclaving at an elevated temperature under an oxygen partial pressure of at least about 100 psi, a slurry of the particulated feed material in an aqueous acid solution containing a mineral acid for a period of time sufficient to convert the predominant portion of molybdenum compounds to molybdenum trioxide and to convert the contaminating metal compounds present to aqueous acid soluble compounds. The autoclaved slurry is thereafter filtered and the solids are subjected to an aqueous alkali hydroxide leach treatment to extract the molybdenum trioxide constituent therein in the form of alkali metal molybdate compounds, which subsequently are recovered from the leach liquor in the form of a high purity alkali metal molybdate product. When ammonium hydroxide is employed, the ammonium molybdate product may be further calcined to produce a high purity molybdic oxide product.

Purification process for technical grade molybdenum oxide

A simple, efficient and economical process for purifying molybdenum disulfide concentrates by contacting and digesting the molybdenum disulfide feed material with an aqueous acid solution containing a controlled combination of hydrofluoric acid and sulfuric acid in a manner to convert substantially all of the contaminating silica bearing minerals therein to aqueous soluble fluoride and sulfate compounds and any contaminating lead sulfide compounds to lead sulfate compounds, and thereafter washing, neutralizing and drying the purified molybdenum disulfide powder product. In accordance with a preferred practice, when the molybdenum disulfide feed material contains in excess of about 0.1% iron as an indication of pyrite concentration, the concentrate is calcined at an elevated temperature in a nonoxidizing atmosphere prior to the digestion step to effect a conversion of the pyrites to synthetic pyrrhotites, which are softer and less abrasive and are more acid soluble. The product thus derived is eminently suitable for use in the formulation of lubricants and as an intermediate in the synthesis of high purity molybdenum compounds.

Process for treating molybdenite concentrates to produce a lubricant

A process for purifying concentrates of molybdenum oxide containing a variety of naturally-occurring contaminating metals, such as potassium, copper, calcium, magnesium, iron, aluminum, lead, zinc, bismuth, and the like, as well as compounds thereof, by roasting the impure concentrate at an elevated temperature in an oxygen atmosphere to convert sub-oxides of molybdenum to molybdenum trioxide and contaminating metal molybdites to corresponding metal molybdates, which are extracted by a hot aqueous leaching of the concentrate and the solubilized molybdate ions are recovered. The aqueous leached concentrate, after separation from the aqueous leach solution, is leached with an ammoniacal leach solution for converting the molybdenum trioxide constituent therein into soluble ammonium molybdate compounds, and the resultant leach solution is removed from the remaining insoluble residue, which is discarded. The ammoniacal leach solution containing only minimal quantities of remaining contaminating metal ions can be further purified by passage through a chelating cation exchange resin, whereafter the ammonium molybdate compounds are recovered, such as by evaporative crystallization, to produce a high purity ammonium dimolybdate (ADM) product, or alternatively, can be calcined at an elevated temperature to produce a high purity molybdenum trioxide product.

Molybdenum oxide purification process

A method for purifying technical grade molybdenum oxide derived from the roasting of molybdenite concentrates by which the molybdenum oxide feed material is admixed with sulfuric acid and pugged to form a plurality of reaction pellets which are heated to an elevated temperature to effect a baking and subsequent roasting thereof and a reaction between the metal contaminants and the sulfuric acid to produce aqueous soluble sulfate compounds. The resultant roasted pelletized oxide is ground and leached to remove the contaminating metal sulfates, whereafter the leached pellets are contacted with an aqueous ammoniacal solution for converting the molybdenum oxide constituent therein to ammonium molybdate dissolved in the solution, which is separated from the insoluble residue, which is discarded to waste and the solution is crystallized to recover the ammonium molybdate product which, in turn, may be calcined to produce a high purity molybdenum oxide product.

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Golden, CO, United States of America

Richard A Ronzio