There are provided methods for the production of potassium sulphate. The methods comprise contacting an aqueous potassium- and sulphate-containing composition with magnesium chloride (MgCl.sub.2), thereby obtaining a composition comprising kainite; optionally concentrating the kainite from the composition; reacting the kainite with magnesium sulphate (MgSO.sub.4) and potassium sulphate (K.sub.2SO.sub.4) so as to convert the kainite into leonite (K.sub.2SO.sub.4.MgSO.sub.4.4H.sub.2O); optionally contacting the leonite with water to remove excess MgSO.sub.4 and contacting the leonite with water so as to leach the MgSO.sub.4, contained in the leonite, and to at least substantially selectively precipitate potassium sulphate (K.sub.2SO.sub.4), and further involving a process brine sulphate control step, based on bloedite precipitation, to control the overall level of sulphate in the method. The method according to the invention can be operated at higher temperatures, in particular at temperatures above 35 C. and does not require a cooling step at 20 to 25 C. The method produces potassium sulphate with a low amount of chloride.

There are provided methods for the production of potassium sulphate. The methods comprise contacting an aqueous potassium- and sulphate-containing composition with magnesium chloride (MgCl.sub.2), thereby obtaining a composition comprising kainite; optionally concentrating the kainite from the composition; reacting the kainite with magnesium sulphate (MgSO.sub.4) and potassium sulphate (K.sub.2SO.sub.4) so as to convert the kainite into leonite (K.sub.2SO.sub.4.MgSO.sub.4.4H.sub.2O); optionally contacting the leonite with water to remove excess MgSO.sub.4 and contacting the leonite with water so as to leach the MgSO.sub.4, contained in the leonite, and to at least substantially selectively precipitate potassium sulphate (K.sub.2SO.sub.4), and further involving a process brine sulphate control step, based on bloedite precipitation, to control the overall level of sulphate in the method. The method according to the invention can be operated at higher temperatures, in particular at temperatures above 35 C. and does not require a cooling step at 20 to 25 C. The method produces potassium sulphate with a low amount of chloride.

The invention relates to a process for selective flotation of kainite from crushed crude potash salts or, for example, from crystallized salt mixtures obtained by evaporation processes, which in addition to kainite may contain further minerals such as halite, sylvine and other salt minerals, for example, in order to produce a kainite concentrate fraction and a residues fraction. The separation process is characterized in that the crushed or crystallized salt mixture is intensively mixed as a crystallizate suspension with a combination of conditioning agents consisting of a sulfated fatty acid or its alkali metal salt as collecting reagent and a frothing agent known for flotation (for example, glycol ether, monohydric aliphatic alcohols, terpene alcohols, polyglycol ethers, etc.) and is then separated by agitator-driven or pneumatic flotation into a kainite concentrate fraction and a residues fraction. The resulting fractions may be further processed in downstream processes. This process permits industrial-scale processing for selective extraction of kainite from mineral mixtures by means of the flotation process.

The invention relates to a process for selective flotation of kainite from crushed crude potash salts or, for example, from crystallized salt mixtures obtained by evaporation processes, which in addition to kainite may contain further minerals such as halite, sylvine and other salt minerals, for example, in order to produce a kainite concentrate fraction and a residues fraction. The separation process is characterized in that the crushed or crystallized salt mixture is intensively mixed as a crystallizate suspension with a combination of conditioning agents consisting of a sulfated fatty acid or its alkali metal salt as collecting reagent and a frothing agent known for flotation (for example, glycol ether, monohydric aliphatic alcohols, terpene alcohols, polyglycol ethers, etc.) and is then separated by agitator-driven or pneumatic flotation into a kainite concentrate fraction and a residues fraction. The resulting fractions may be further processed in downstream processes. This process permits industrial-scale processing for selective extraction of kainite from mineral mixtures by means of the flotation process.

The present invention is to provide a process for removing magnesium contained as an impurity from nickel sulfate and producing high-purity nickel sulfate.

The process for producing an aqueous nickel sulfate solution from which magnesium is removed from nickel sulfate, comprises the following steps (1) to (3): (1) a carbonation step obtaining a slurry comprising nickel carbonate as a solid content by mixing a nickel sulfate aqueous solution and lithium carbonate, (2) a solid-liquid separation step of separating the slurry obtained in the carbonation step into a solid content and liquid component, and (3) a dissolution step dissolving the solid content obtained in said solid-liquid separation step with a solution containing sulfuric acid.

The present invention is to provide a process for removing magnesium contained as an impurity from nickel sulfate and producing high-purity nickel sulfate.

The process for producing an aqueous nickel sulfate solution from which magnesium is removed from nickel sulfate, comprises the following steps (1) to (3): (1) a carbonation step obtaining a slurry comprising nickel carbonate as a solid content by mixing a nickel sulfate aqueous solution and lithium carbonate, (2) a solid-liquid separation step of separating the slurry obtained in the carbonation step into a solid content and liquid component, and (3) a dissolution step dissolving the solid content obtained in said solid-liquid separation step with a solution containing sulfuric acid.

The present invention relates to an apparatus for manufacturing a potassium compound and a method of recovering a potassium compound from a brine, and provides the apparatus for manufacturing the potassium compound, including: a continuous pre-treatment apparatus including a crushing portion, a pulverization portion, and a particle size separation portion for processing a mixed raw material salt obtained after lithium, magnesium, and calcium are extracted from a brine to have a particle size for easy separation and sorting; a continuous potassium compound lump recovering apparatus continuously separating and recovering the potassium compound from the pre-treated mixed raw material salt; a continuous potassium compound separating and sorting apparatus continuously separating and sorting potassium chloride and a glaserite (Na.sub.2SO.sub.4.3K.sub.2SO.sub.4) from the recovered potassium compound; and a continuous potassium sulfate conversion apparatus extracting potassium sulfate from the separated glaserite.

The present invention relates to an apparatus for manufacturing a potassium compound and a method of recovering a potassium compound from a brine, and provides the apparatus for manufacturing the potassium compound, including: a continuous pre-treatment apparatus including a crushing portion, a pulverization portion, and a particle size separation portion for processing a mixed raw material salt obtained after lithium, magnesium, and calcium are extracted from a brine to have a particle size for easy separation and sorting; a continuous potassium compound lump recovering apparatus continuously separating and recovering the potassium compound from the pre-treated mixed raw material salt; a continuous potassium compound separating and sorting apparatus continuously separating and sorting potassium chloride and a glaserite (Na.sub.2SO.sub.4.3K.sub.2SO.sub.4) from the recovered potassium compound; and a continuous potassium sulfate conversion apparatus extracting potassium sulfate from the separated glaserite.

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.