The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Sep. 09, 2003
Filed:
Apr. 01, 2002
Hiroshi Sumita, Okayama-ken, JP;
Toda Kogyo Corporation, Hiroshima-ken, JP;
Abstract
The process for producing granular hematite particles of the present invention, comprises passing an oxygen-containing gas through an aqueous ferrous nitrate solution in the presence of iron materials and hematite seed crystals at a temperature of 80 to 90° C., thereby obtaining reddish brown precipitates containing granular hematite particles as a main component; subjecting the reddish brown precipitates to filtration, water-washing and then drying; and heat-treating the reddish brown precipitates in air at a temperature of 450 to 900° C. In accordance with the process of the present invention, the granular hematite particles exhibiting a high purity, a small equilibrium water content and a reduced oil absorption can be produced using inexpensive iron raw materials without use of a specific device such as autoclave in an industrially and economically useful manner.