The present invention provides process for production of potassium ammonium sulfate compound fertilizer through the reaction of Epsom salt, obtained in course of chilling of concentrated sea bittern (32-33 Be), with potassium bitartrate, precipitated from such bittern, and ammonium hydroxide. While process integration was achieved through utilisation of Epsom salt; partial desulphatation of bittern, through crystallization of Epsom salt, resulted in about 17% improvement in K.sup.+ precipitation efficiency.

The present invention provides process for production of potassium ammonium sulfate compound fertilizer through the reaction of Epsom salt, obtained in course of chilling of concentrated sea bittern (32-33 Be), with potassium bitartrate, precipitated from such bittern, and ammonium hydroxide. While process integration was achieved through utilisation of Epsom salt; partial desulphatation of bittern, through crystallization of Epsom salt, resulted in about 17% improvement in K.sup.+ precipitation efficiency.

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). 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). 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.