METHOD OF COBALT-ZINC DOUBLE CYCLO-TETRA-PHOSPHATES' HIGH-TEMPERATURE PREPARATION

摘要

The invention is based on the calcination of the initial mixture composed of compounds of the cobaltous and zincous type of dihydrogen phosphates, or mixtures of phosphoric acid with cobalt or zinc hydrogen phosphates or phosphates, or with cobalt or zinc oxides, hydroxides or carbonates in a quantity corresponding to the molar ratio Co/Zn = (2-x)/x and P2O5/(Co+Zn) equal to 0.98 to 1.10 to temperatures higher than 800 degrees C, when melting occurs. By intensive cooling this is transformed into a vitreous intermediate product, which, by repeated heating to a temperature of at least 500 degrees C and lower than 800 degrees C, re-crystallises causing the occurrence of microcrystals of zinc-cobalt double cyclo-tetraphosphates.