US 4,372,865 AGranted

Carbonate/hydroxide coprecipitation process

AssigneeSpang Industries, Inc.

InventorsBu-Fan B. Yu, Alex Goldman

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Abstract

The present invention improves the processing and products of coprecipitation of Fe and other metals selected from Mn, Zn, Ni, and Mg as carbonates and hydroxides in the manufacture of magnetically soft ferrites. Teachings are provided which enable control of the characteristics, especially the particle shape of coprecipitated metal carbonates and hydroxides, to bring about significant advantages in further processing such as relief of critical sintering requirements to meet commercial specifications, improved intermediate products which can be more easily handled during processing, and improved quality magnetically-soft, compacted, ferrite components. In the manufacture of MnZn ferrites, sintering furnace temperatures encountered by components from the same batch can vary as much as 100.degree. C. while maintaining specifications of permeability and loss factor whereas, with prior ferrite materials, a variation of as little as 5.degree. C. to 10.degree. C. can make the difference between acceptable and non-acceptable product.

Claims9

Dependent claims

Method for carbonate-hydroxide coprecipitation of materials for manufacture of magnetically soft ferrites and for controlling characteristics of such coprecipitated materials comprising

forming an aqueous metal ion solution of ferrous ions and divalent ions of at least one other metal in which the divalent metal ions of said at least one other metal are selected from the group consisting of Mn++, Ni++, Mg++, and Zn++,
providing a base solution of carbonates and hydroxides by combining in solution carbonate ion and hydroxide ion source materials selected from the group consisting of ammonium carbonate, ammonium bicarbonate, ammonium hydroxide, sodium carbonate, sodium hydroxide, potassium carbonate, and potassium hydroxide,
the base solution having a pH of about eleven,
combining such metal ion solution and such base carbonate and hydroxide ion solution to form a reaction liquor for precipitation of metal carbonates and metal hydroxides, the reaction liquor having a pH between about 7.5 and about 8.5, and
controllably limiting physical agitation applied in combining such metal ion and base solutions by limiting mixing times of such solutions between about five and about thirty seconds and controllably holding the resulting slurry of metal carbonate-hydroxide precipitate in mother liquor substantially free of applied physical agitation for a time sufficient to effect formation of spherical particles having a size between about one and about ten microns in diameter.

2 more elements

Dependencies are inferred from the claim text.