Cominco, Ltd.

Gordon C Hildred

John T Higgins

Stewart G Bexton

James G Whitham

A process is disclosed for the production of a urea sulfur fertilizer by mixing urea and molten sulfur to obtain a molten mixture and solidifying the molten mixture to obtain a homogeneous, solid, particulate urea sulfur fertilizer wherein the sulfur has particle sizes of smaller than about 100 micron. The process comprises passing molten urea and molten sulfur through a mixing device at a temperature above the melting points to produce a finely divided sulfur dispersed in urea with the molten sulfur added in amounts sufficient to produce said urea sulfur fertilizer, maintaining a pressure drop across said mixing device of at least about 200 kPa to form a homogenized melt of urea sulfur, and solidifying said homogenized melt by prilling or agglomeration.

Manufacture of urea sulfur fertilizer

A process for the production of granular sulfur in a rotating drum in which molten sulfur at a temperature within the range of about 110.degree. to 160.degree. C. is sprayed in a contact zone onto a bed of moving sulfur particles and a continuous curtain of said particles and resulting particles are passed to a cooling zone prior to discharge. A countercurrent flow of substantially inert cooling gas at a temperature in the range of about 10.degree. to 50.degree. C. and containing not more than 8% by volume oxygen is introduced to the cooling zone and a portion or all of said cooling gas is passed through the contact zone. The contact and cooling zones can be formed in a single rotating drum and separated from each other by a retaining ring or formed in separate vessels. Discharge particles from the cooling zone are separated according to size and undersized particles are recycled as fines to the contact zone at a ratio of 4:1 to 2:1 of fines to product granules.

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Calgary, Canada

Gordon C Hildred