Abstract: Submicronic zirconia particulates containing stabilizing amounts of yttrium or cerium, well adapted for ceramics applications, are produced by (i) admixing an aqueous suspension of zirconium fluosulfate particles having a pH of from about 0 to 3 with an aqueous solution of a salt of yttrium or cerium, (ii) neutralizing the resulting mixture at a pH of at least 7, (iii) separating a mixture of zirconium/yttrium or zirconium/cerium hydroxides from the medium of neutralization, (iv) washing said mixture of hydroxides to eliminate sulfate and fluoride ions therefrom, and then (v) calcining said mixture of hydroxides.

Abstract: Pigmentary red iron oxide particulates essentially devoid of manganese impurities and ranging in shade from the orange-reds to the purplish reds, are conveniently prepared by (1) calcining, even at higher temperatures, an intimate admixture of (i) a ferrous sulfate hydrate containing contaminating amounts of manganese values, e.g., a by-product stream of ferrous sulfate, and (ii) an alkali metal compound, said admixture comprising from 0.08 to 1 gram-atom of alkali metal per mole of Fe.sub.2 O.sub.3 produced, (2) washing the calcined admixture with water to remove essentially all water-soluble manganese values therefrom, and advantageously (3) drying and (4) grinding the calcined and washed admixture.

Abstract: Pigment grade Fe.sub.2 O.sub.3 is prepared from ferrous sulphate by a roasting process. The ferrous sulphate, partly dehydrated and granulated, is partially converted to the oxide by roasting. After elimination of soluble constituents by washing with water, the oxide is subjected to pigmentary calcination and then crushed and optionally micronized. This process makes it possible to prepare red pigments of excellent quality characterized particularly by pure tints ranging from orange-red to purplish-red. The oil absorptions are especially low. Low toxic impurity concentrations permit the use of these pigments in foodstuffs.

Abstract: In the sulphuric acid process for the production of pigmentary titanium dioxide from titaniferous ores such as ilmenite, in which the sulphuric acid digestate is reduced electrolytically in the cathode compartment of an electrolytic cell, to convert Fe III in the digestate to Fe II, substantial reductions in electric power consumption can be achieved by introducing a ferrous sulphate solution as anolyte instead of sulphuric acid. The ferrous sulphate used is preferably recycle material obtained in the catholyte in an earlier reduction cycle.