Process for the preparation of fertilizers and soil modifiers
AssigneeSocieta' Italiana Resine S.I.R. S.p.A.
InventorsLuigi Piccolo, Marcello Ghirga, Antonio Paolinelli, Gian Pietro Paganessi
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Abstract
A soil modifying composition and a concentrated solution of ammonium sulphate with a high purity degree are obtained from by-products consisting essentially of ferrous sulphate heptahydrate, obtained in the production of titanium dioxide from ilmenites by the sulphate process, by contacting solid particles of said by-products with gaseous ammonia, lixiviating the resulting product with water, thereby to recover said concentrated solution of ammonium sulphate, the dried residual solid yielding said soil modifying composition.
Claims12
A method for the preparation of a composition useful as soil modifier and of a concentrated solution of ammonium sulphate with a high purity degree, starting from by-products obtained in the production of titanium dioxide from ilmenites or ilmenite slag by the sulphate process, said by-products consisting essentially of ferrous sulphate heptahydrate, which comprises:
- a. contacting solid particles of said-by products with gaseous ammonia, thereby to obtain a reaction product consisting essentially of ammonium sulphate and ferrous hydroxide;
- b. subjecting said reaction product to oxidation by oxygen or a gas containing molecular oxygen, thereby to convert said ferrous hydroxide into ferric hydroxide;
- c. lixiviating with water the product obtained in stage (b), thereby to remove from 85 to 95 wt. % of said ammonium sulphate in the form of an aqueous solution having an ammonium sulphate content of at least 40 wt. %, and separating said solution from the residual solid;
- and
- d. drying said residual solid to a water content of less than 20% by weight, said steps (a) and (b) being carried out at a temperature not higher than 90.degree. C.
Dependencies are inferred from the claim text.