Abstract: A process for preparing an elemental sulphur-containing fertilizer is disclosed. The process uses a dispersion mill, wherein a rotor turns within a slotted stator, to wet mill elemental sulphur in a liquid (preferably an aqueous liquid), thereby providing a dispersion of milled elemental sulphur in the liquid. The dispersion is combined with further components to provide a mixture of elemental sulphur and further components, and the mixture is granulated in a granulator unit to provide granulated elemental sulphur-containing fertilizer.

Abstract: A process for preparing an elemental sulphur-containing fertilizer is disclosed. The process uses a dispersion mill, wherein a rotor turns within a slotted stator, to wet mill elemental sulphur in a liquid (preferably an aqueous liquid), thereby providing a dispersion of milled elemental sulphur in the liquid. The dispersion is combined with further components to provide a mixture of elemental sulphur and further components, and the mixture is granulated in a granulator unit to provide granulated elemental sulphur-containing fertilizer.

Abstract: In one aspect, the invention includes a method of purifying phosphoric acid comprising filtering a feed solution of phosphoric acid through a membrane, wherein the feed solution is maintained at a temperature of from about 30.degree. F. to about 90.degree. F. during the filtering. In another aspect, the invention includes a method of purifying phosphoric acid comprising: a) providing a feed solution of phosphoric acid, said feed solution comprising greater than 17,000 ppm on a 100% P.sub.2 O.sub.5 basis of each of Al, Fe and Mg; and b) filtering the feed solution through a polyamide filter configured for nanofiltration, the filtering comprising a temperature of from about 30.degree. F. to 90.degree. F., and a pressure of from about 600 psig to about 1000 psig to form a purified phosphoric acid solution, the purified phosphoric acid solution comprising less than 1700 ppm on a 100% P.sub.2 O.sub.5 basis of each of Al, Fe and Mg.

Abstract: Fluorine in the form of fluoride is removed from phosphoric acid having an initial phosphate concentration of less than about 50 percent by determining the concentration of fluoride to be removed from the acid and the concentration of silicon in the acid. Silica is added to the acid in an amount sufficient that the molar ratio of fluoride to be removed from the acid to silicon in the acid is about 6. The acid is concentrated to a final phosphate concentration of greater than about 50 percent, whereupon fluoride is reacted to fluosilicic acid. By maintaining the indicated concentration ratio of fluoride to be removed and silicon, fouling of condenser and scrubber components with deposited silica is avoided.

Abstract: An apparatus for removing vanadium from phosphoric acid includes a precipitator that receives vanadium-containing process-feed phosphoric acid and adds an oxidant to the process-feed phosphoric acid, whereupon precipitates containing phosphorus and vanadium are formed in a phosphoric acid filter feed slurry. The solid precipitate is removed by a filter. The filtrate, after optional further oxidation, is contacted to an ion exchange resin to remove additional vanadium from the filtrate to produce a phosphoric acid product of reduced vanadium content. A first portion of the phosphoric acid product is removed from the apparatus for further use. A reducing agent is added to a second portion of the phosphoric acid product, and the reduced acid is used to strip vanadium from the loaded ion exchange resin. The vanadium-loaded second portion of the phosphoric acid is mixed with fresh phosphoric acid and fed to the precipitator.