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.

The present invention relates to a process for producing sodium sulphate from phosphogypsum, comprising: a step (101) of lixiviation of phosphogypsum by means of a basic solution so as to obtain a sodium sulphate solution (S) containing metal impurities, said basic solution comprising a chelating agent suitable for forming complexes with at least one part of said metal impurities, at least one first step (103, 104) of filtration of the sodium sulphate solution by a nanofiltration membrane (NF1, NF2), so as to form a concentrate (C1, C2) containing said complexes and a permeate (P1, P2), a step (105) of evaporation of the permeate (P1, P2) so as to form anhydrous sodium sulphate.

The present invention relates to a process for producing sodium sulphate from phosphogypsum, comprising: a step (101) of lixiviation of phosphogypsum by means of a basic solution so as to obtain a sodium sulphate solution (S) containing metal impurities, said basic solution comprising a chelating agent suitable for forming complexes with at least one part of said metal impurities, at least one first step (103, 104) of filtration of the sodium sulphate solution by a nanofiltration membrane (NF1, NF2), so as to form a concentrate (C1, C2) containing said complexes and a permeate (P1, P2), a step (105) of evaporation of the permeate (P1, P2) so as to form anhydrous sodium sulphate.

A process for the recovery of sodium sulfate from water, in particular from water deriving from a silica manufacturing process.

A process for the recovery of sodium sulfate from water, in particular from water deriving from a silica manufacturing process.

The present invention relates to a process for producing sodium sulphate from phosphogypsum, comprising: a step (101) of lixiviation of phosphogypsum by means of a basic solution so as to obtain a sodium sulphate solution (S) containing metal impurities, said basic solution comprising a chelating agent suitable for forming complexes with at least one part of said metal impurities, at least one first step (103, 104) of filtration of the sodium sulphate solution by a nanofiltration membrane (NF1, NF2), so as to form a concentrate (C1, C2) containing said complexes and a permeate (P1, P2), a step (105) of evaporation of the permeate (P1, P2) so as to form anhydrous sodium sulphate.

The present invention relates to a process for producing sodium sulphate from phosphogypsum, comprising: a step (101) of lixiviation of phosphogypsum by means of a basic solution so as to obtain a sodium sulphate solution (S) containing metal impurities, said basic solution comprising a chelating agent suitable for forming complexes with at least one part of said metal impurities, at least one first step (103, 104) of filtration of the sodium sulphate solution by a nanofiltration membrane (NF1, NF2), so as to form a concentrate (C1, C2) containing said complexes and a permeate (P1, P2), a step (105) of evaporation of the permeate (P1, P2) so as to form anhydrous sodium sulphate.

A process for water removal and/or recycling of sodium sulfate and/or sodium dithionate containing liquors derived from processing cobalt resource material essentially free of lithium comprising the steps of precipitation of cobalt as cobaltous carbonate or cobaltous hydroxide followed by removal thereof from the liquor, crystallization of sodium sulfate and sodium dithionate and removal of the crystals, followed by heating of the crystals to anhydrous sodium sulfate, sulphur dioxide and water and then separating the anhydrous sodium sulfate.

A process for water removal and/or recycling of sodium sulfate and/or sodium dithionate containing liquors derived from processing cobalt resource material essentially free of lithium comprising the steps of precipitation of cobalt as cobaltous carbonate or cobaltous hydroxide followed by removal thereof from the liquor, crystallization of sodium sulfate and sodium dithionate and removal of the crystals, followed by heating of the crystals to anhydrous sodium sulfate, sulphur dioxide and water and then separating the anhydrous sodium sulfate.