| 摘要 |
<p>1487902 Fe(OH) 3 , Fe 2 (SO 4 ) 3 and (NH 4 ) 2 SO 4 ; soil modifiers SOC ITALIANA RESINE SIR SpA 19 Dec 1975 [20 Dec 1974] 52172/75 Headings C1A and C1B A soil modifying composition and a concentrated (NH 4 ) 2 SO 4 solution are prepared from the solid by-products obtained in TiO 2 production from ilmenite or ilmenite slag by the sulphate process (a) contacting the by-product consisting essentially of FeSO 4 7H 2 O with gaseous NH 3 to obtain essentially (NH 4 ) 2 SO 4 and Fe(OH) 2 , (b) oxidizing the product of step (a) to obtain Fe(OH) 3 using O 2 or a molecular oxygen containing gas, (c) lixiviating the product of step (b) with water to remove 85 to 95 wt. per cent of the (NH 4 ) 2 SO 4 in the form of an aqueous solution having an average (NH 4 ) 2 SO 4 content of at least 40 wt. per cent and separating the solution from the residual solids, and, (d) drying the solids to a water content of <20% by wt. to obtain the soil modifier composition. Step (a) may be carried out at from 20‹ C. up to just below the melting point of FeSO 4 7H 2 O; under these conditions step (a) may be carried out simultaneously with step (b) in a single reaction stage. The dried residual solid step (d) may be treated with H 2 SO 4 to convert at least 5 mole per cent of Fe(OH) 3 on to the sulphate for use as soil modifier. Reference has been directed by the Comptroller to Specification 1,418,623.</p> |
