US 6,190,625 B1Granted

Fluidized-bed roasting of molybdenite concentrates

AssigneeQualchem, Inc.

InventorsMahesh C. Jha, William A. May

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Abstract

The present invention provides a method for fluidized bed roasting of molybdenite to molybdenum trioxide. A fluid bed reactor separated into separate zones is used to provide plug flow conditions. A cooling tube is submerged in the fluid bed to control temperature. A vibrator is used to enhance fluidization.

Claims24

Dependent claims

A method for converting molybdenum sulfides into molybdenum oxides, comprising:

introducing a feed material comprising molybdenum sulfides into a fluidized bed of particulate solids contained within a fluidized bed reactor, the fluidized bed being separated into a plurality of different zones with adjacent zones being separated by a baffle with an opening between the adjacent zones such that the material flows through the fluidized bed reactor in plug flow mode;
contacting the particulate solids of the fluidized bed, including the feed material, with an oxygen containing fluidizing gas while vibrating the fluidized bed reactor, to convert at least a portion of the molybdenum sulfides into molybdenum oxides and thereby form a product comprising mnolybdenum oxides;
maintaining a fluidized bed temperature in a range of from about 400° C. to about 580° C., comprising (i) cooling at least a portion of the particulate solids in at least a first zone of the fluidized bed, during the contacting step, with cooling means for removing heat from the first zone of the fluidized bed to maintain a fluidized bed temperature in the first zone of no more than about 580° C., the cooling means being submerged in the fluidized bed during the cooling step, an cd (ii) heating at least a portion of the particulate solids in at least a second zone of the fluidized bed to maintain a fluidized bed temperature in the second zone of at least about 400° C.;
wherein, the particulate solids in the first zone have a higher sulfide content, than the sulfide content of the particulate solids in the second zone, and exothermic reaction of the sulfides in the first zone produces excess heat in the first zone and heat is removed from the first zone by the cooling to maintain the temperature in the first zone within the range;
wherein, the particulate solids of the second zone have a lower sulfide content, than the sulfide content of particulate solids in the first zone, and exothermic reaction of sulfides in the second zone produces insufficient beat in the second zone and heat is added to the second zone by the heating to maintain the temperature in the second zone within the the range;
and
removing product comprising the molybdenum oxides from the fluidized bed reactor.

4 more elements

Dependencies are inferred from the claim text.

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Abstract

A method for converting molybdenum sulfides into molybdenum oxides, comprising:

introducing a feed material comprising molybdenum sulfides into a fluidized bed of particulate solids contained within a fluidized bed reactor, the fluidized bed being separated into a plurality of different zones with adjacent zones being separated by a baffle with an opening between the adjacent zones such that the material flows through the fluidized bed reactor in plug flow mode;
contacting the particulate solids of the fluidized bed, including the feed material, with an oxygen containing fluidizing gas while vibrating the fluidized bed reactor, to convert at least a portion of the molybdenum sulfides into molybdenum oxides and thereby form a product comprising mnolybdenum oxides;
maintaining a fluidized bed temperature in a range of from about 400° C. to about 580° C., comprising (i) cooling at least a portion of the particulate solids in at least a first zone of the fluidized bed, during the contacting step, with cooling means for removing heat from the first zone of the fluidized bed to maintain a fluidized bed temperature in the first zone of no more than about 580° C., the cooling means being submerged in the fluidized bed during the cooling step, an cd (ii) heating at least a portion of the particulate solids in at least a second zone of the fluidized bed to maintain a fluidized bed temperature in the second zone of at least about 400° C.;
wherein, the particulate solids in the first zone have a higher sulfide content, than the sulfide content of the particulate solids in the second zone, and exothermic reaction of the sulfides in the first zone produces excess heat in the first zone and heat is removed from the first zone by the cooling to maintain the temperature in the first zone within the range;
wherein, the particulate solids of the second zone have a lower sulfide content, than the sulfide content of particulate solids in the first zone, and exothermic reaction of sulfides in the second zone produces insufficient beat in the second zone and heat is added to the second zone by the heating to maintain the temperature in the second zone within the the range;
and
removing product comprising the molybdenum oxides from the fluidized bed reactor.

4 more elements