A method for the production of slags with increased soluble phosphate content

摘要

Prodn. of phosphate materials suitable for use as fertilisers from blast furnace or steel making slag comprises subjecting the slag, straight from the ladle, to rapid shock cooling under anhydrous conditions by contact with substances which decompose endothermically at high temp. The decomposable substance is pref. limestone or dolomite used in powder from (20 mu to 10 mm.) in an amt. of 5-30 kg./t. of slag. This material can be mixed with substances which supply extra P2O5 and/or promote the formation of soluble phosphate, e.g., silicocarnotite or nagelschmidtite. The treatment stabilises the tricalcium phosphate in its alpha form, inhibits hydroxyapatite formation, and increases the friability of the prod. Prods. contg. =95% citric acid soluble phosphate can be obtd.