Systems and methods of producing potassium sulfate can involve converting a mixed salts feed stream into a conversion end slurry in a conversion unit, the mixed salts feed comprising at least one potassium-containing salt, at least one chloride-containing salt, at least one magnesium-containing salt and at least one sulfate-containing salt and the conversion end slurry comprising schoenite; separating conversion end slurry into a conversion end solids stream and a conversion brine; leaching the conversion end solids stream in a crystallization unit to produce a potassium sulfate product stream comprising potassium sulfate and a crystallizer mother liquor comprising magnesium sulfate and potassium sulfate; collecting heat generated in the conversion unit by a heat pump; and providing at least a portion of the heat collected to the crystallization unit to regulate a temperature of the potassium sulfate product stream and the crystallizer mother liquor stream contained in the crystallization unit.

Systems and methods of producing potassium sulfate can involve converting a mixed salts feed stream into a conversion end slurry in a conversion unit, the mixed salts feed comprising at least one potassium-containing salt, at least one chloride-containing salt, at least one magnesium-containing salt and at least one sulfate-containing salt and the conversion end slurry comprising schoenite; separating conversion end slurry into a conversion end solids stream and a conversion brine; leaching the conversion end solids stream in a crystallization unit to produce a potassium sulfate product stream comprising potassium sulfate and a crystallizer mother liquor comprising magnesium sulfate and potassium sulfate; collecting heat generated in the conversion unit by a heat pump; and providing at least a portion of the heat collected to the crystallization unit to regulate a temperature of the potassium sulfate product stream and the crystallizer mother liquor stream contained in the crystallization unit.

A method is used for treating a salt solution using a treatment system. The treatment system has an evaporation device to which the salt solution produced in an upstream operation is supplied. A crystallizate suspension having kainite, halite, and sylvite is obtained from the evaporation device, and the kainite is then separated from the crystallizate suspension. The method for separating the kainite from the crystallizate suspension has at least the following steps: supplying the crystallizate suspension to a preliminary classifying device in which kainite is partly separated from the crystallizate suspension by means of a preliminary removal process based on the particle size of the kainite, thereby obtaining a kainite-reduced fraction, and transferring the kainite-reduced fraction to a flotation device in which the remaining content of kainite is separated from the kainite-reduced fraction.

A method is used for treating a salt solution using a treatment system. The treatment system has an evaporation device to which the salt solution produced in an upstream operation is supplied. A crystallizate suspension having kainite, halite, and sylvite is obtained from the evaporation device, and the kainite is then separated from the crystallizate suspension. The method for separating the kainite from the crystallizate suspension has at least the following steps: supplying the crystallizate suspension to a preliminary classifying device in which kainite is partly separated from the crystallizate suspension by means of a preliminary removal process based on the particle size of the kainite, thereby obtaining a kainite-reduced fraction, and transferring the kainite-reduced fraction to a flotation device in which the remaining content of kainite is separated from the kainite-reduced fraction.

According to some embodiments there is provided a process for the recovery of SOP from Sulphate bearing mineral and Carnallite or Sylvenite, comprising: Dissolving Carnallite in water to obtain Sylvenite and high Magnesium Chloride brine; Adding Sodium Sulphate to said Carnallite to produce mixture of Kainte\Leonite, KCl and NaCl precipitant and brine containing Mg Cl.sub.2, KCl, NaCl; Separating the NaCl from the mixture; Obtaining a precipitant mixture of Leonite with KCl; Filtering said Leonite and washing with water to yield pure mixture of Leonite with KCl; Adding KCl to the Leonite with the KCl; and Decompose said Leonite with the KCl to SOP.

According to some embodiments there is provided a process for the recovery of SOP from Sulphate bearing mineral and Carnallite or Sylvenite, comprising: Dissolving Carnallite in water to obtain Sylvenite and high Magnesium Chloride brine; Adding Sodium Sulphate to said Carnallite to produce mixture of Kainte\Leonite, KCl and NaCl precipitant and brine containing Mg Cl.sub.2, KCl, NaCl; Separating the NaCl from the mixture; Obtaining a precipitant mixture of Leonite with KCl; Filtering said Leonite and washing with water to yield pure mixture of Leonite with KCl; Adding KCl to the Leonite with the KCl; and Decompose said Leonite with the KCl to SOP.

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 and reducing or removing halite therefrom; 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), further involving a process brine sulphate control step, based on bloedite precipitation, to control the overall level of sulphate in the method and further comprising a step for the substantially complete reduction or removal of halite from the flotation concentrate, accompanied by an additional precipitation of kainite, thus also increasing the overall recovery of kainite in the process. 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 and reducing or removing halite therefrom; 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), further involving a process brine sulphate control step, based on bloedite precipitation, to control the overall level of sulphate in the method and further comprising a step for the substantially complete reduction or removal of halite from the flotation concentrate, accompanied by an additional precipitation of kainite, thus also increasing the overall recovery of kainite in the process. 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.

A method for removing alkali earth metals from a filtrate including a first crystallization step and a second crystallization step, wherein the first crystallization step is a forced circulation crystallizer, and wherein the second crystallization step is a draft tube crystallizer. Also included is a method for reducing magnesium in a chemical liquor including crystallizing magnesium into a magnesium sulfate hydrate in a first crystallization step and precipitating magnesium via addition of a caustic material in a chemical precipitation step.

A method for removing alkali earth metals from a filtrate including a first crystallization step and a second crystallization step, wherein the first crystallization step is a forced circulation crystallizer, and wherein the second crystallization step is a draft tube crystallizer. Also included is a method for reducing magnesium in a chemical liquor including crystallizing magnesium into a magnesium sulfate hydrate in a first crystallization step and precipitating magnesium via addition of a caustic material in a chemical precipitation step.