A process for improving the grade and optical quality of zircon, comprising: baking a mixture of a zircon feed and concentrated sulphuric acid at a baking temperature in the range of from 200 up to 400° C., and for a time to form water leachable sulphates with impurities therein including at least iron and titanium; leaching the baked mixture to dissolve the leachable sulphates; and separating the zircon from the leachate containing the leached sulphates, which separated zircon is thereby of improved grade and optical quality.

The present disclosure broadly relates to a process for recovering vanadium, iron, titanium and silica values from vanadiferous feedstocks. More specifically, but not exclusively, the present disclosure relates to a metallurgical process in which vanadium, iron, titanium and silica values are recovered from vanadiferous feedstocks such as vanadiferous titanomagnetite, iron ores, vanadium slags and industrial wastes and by-products containing vanadium. The process broadly comprises digesting the vanadiferous feedstocks into sulfuric acid thereby producing a sulfation cake; dissolving the sulfation cake and separating insoluble solids thereby producing a pregnant solution; reducing the pregnant solution thereby producing a reduced pregnant solution; and crystallizing ferrous sulfate hydrates from the reduced pregnant solution, producing an iron depleted reduced solution. The process further comprises removing titanium compounds from the iron depleted reduced solution thereby producing a vanadium-rich pregnant solution; concentrating vanadium and recovering vanadium products and/or a vanadium electrolyte.

The present disclosure broadly relates to a process for recovering vanadium, iron, titanium and silica values from vanadiferous feedstocks. More specifically, but not exclusively, the present disclosure relates to a metallurgical process in which vanadium, iron, titanium and silica values are recovered from vanadiferous feedstocks such as vanadiferous titanomagnetite, iron ores, vanadium slags and industrial wastes and by-products containing vanadium. The process broadly comprises digesting the vanadiferous feedstocks into sulfuric acid thereby producing a sulfation cake; dissolving the sulfation cake and separating insoluble solids thereby producing a pregnant solution; reducing the pregnant solution thereby producing a reduced pregnant solution; and crystallizing ferrous sulfate hydrates from the reduced pregnant solution, producing an iron depleted reduced solution. The process further comprises removing titanium compounds from the iron depleted reduced solution thereby producing a vanadium-rich pregnant solution; concentrating vanadium and recovering vanadium products and/or a vanadium electrolyte.

The invention provides for the orchestrated treatment of disparate fractions of a shale deposit to recover vanadium values, with distinct steps of beneficiation that together provide a combined vanadium-enriched concentrate amenable to subsequent combined steps of hydrometallurgical vanadium extraction.

This application pertains to methods of recovering metals from metal sulfides that involve contacting the metal sulfide with an acidic sulfate solution containing ferric sulfate and a reagent that has a thiocarbonyl functional group, wherein the concentration of reagent in the acidic sulfate solution is sufficient to increase the rate of metal ion extraction relative to an acidic sulfate solution that does not contain the reagent, to produce a pregnant solution containing the metal ions.

This application pertains to methods of recovering metals from metal sulfides that involve contacting the metal sulfide with an acidic sulfate solution containing ferric sulfate and a reagent that has a thiocarbonyl functional group, wherein the concentration of reagent in the acidic sulfate solution is sufficient to increase the rate of metal ion extraction relative to an acidic sulfate solution that does not contain the reagent, to produce a pregnant solution containing the metal ions.

A degradation agent for viscous fluids to be used in hydraulic fracturing methods is provided according to one aspect of the present invention, the degradation agent comprising a persulfate and an iron salt serving as an activator for the persulfate, wherein the persulfate and the iron salt have been coated and the ratio of the coating-film thickness (Y) in the iron salt to the coating-film thickness (X) in the persulfate, Y/X, is in the range of 0.35 to 1.0. The degradation agent for viscous fluids has properties suitable for use in hydraulic fracturing methods.

A degradation agent for viscous fluids to be used in hydraulic fracturing methods is provided according to one aspect of the present invention, the degradation agent comprising a persulfate and an iron salt serving as an activator for the persulfate, wherein the persulfate and the iron salt have been coated and the ratio of the coating-film thickness (Y) in the iron salt to the coating-film thickness (X) in the persulfate, Y/X, is in the range of 0.35 to 1.0. The degradation agent for viscous fluids has properties suitable for use in hydraulic fracturing methods.

The invention relates to a method for drying salts with a water of crystallisation content in convective apparatuses that can additionally be indirectly heated. The invention is primarily characterised in that the drying process takes place with a moisture content of the drying gas above a determined level. The gas surrounding the salt particles during the drying process therefore has a specific humidity. In this way, the rate of drying is positively influenced.

The invention relates to a method for drying salts with a water of crystallisation content in convective apparatuses that can additionally be indirectly heated. The invention is primarily characterised in that the drying process takes place with a moisture content of the drying gas above a determined level. The gas surrounding the salt particles during the drying process therefore has a specific humidity. In this way, the rate of drying is positively influenced.