Systems and processes for producing potassium sulfate that include providing an industrial waste material that includes at least sodium sulfate, reacting the sodium sulfate with potassium chloride to produce a byproduct comprising potassium sulfate and a chloride-containing brine, and reacting the chloride-containing brine with barium chloride to produce barium sulfate and sodium chloride.

Systems and methods for producing potassium sulfate. Such a method involves providing an industrial waste material that includes at least one metal sulfate or a metal product that has been reacted with sulfuric acid to produce metal sulfates, and then reacting the metal sulfate with potassium carbonate to produce a byproduct that contains potassium sulfate.

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 for producing potassium sulfate. Such a method involves providing an industrial waste material that includes at least one metal sulfate or a metal product that has been reacted with sulfuric acid to produce metal sulfates, and then reacting the metal sulfate with potassium carbonate to produce a byproduct that contains potassium sulfate.

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.

The present invention relates to a method for producing a potassium sulfate containing fertilizer composition from a sodium sulfate containing residue process stream of a battery manufacturing facility, battery recycling facility, or steel production plant, wherein residue process stream from a battery manufacturing facility, battery recycling facility, or steel production plant is provided; optionally water is provided; potassium chloride is provided; and a reaction mixture is provided comprising said optional water, potassium chloride and residue process stream, and is allowed to react, wherein potassium sulfate is obtained.

The present invention relates to a method for producing a potassium sulfate containing fertilizer composition from a sodium sulfate containing residue process stream of a battery manufacturing facility, battery recycling facility, or steel production plant, wherein residue process stream from a battery manufacturing facility, battery recycling facility, or steel production plant is provided; optionally water is provided; potassium chloride is provided; and a reaction mixture is provided comprising said optional water, potassium chloride and residue process stream, and is allowed to react, wherein potassium sulfate is obtained.

Methods are provided for processing a lithium-containing material, such as spodumene, whereby a lithium sulfate solution derived from the material is reacted with sodium hydroxide to produce an intermediate solution comprising a first and second portion comprising lithium hydroxide and sodium sulfate. Lithium hydroxide and sodium sulfate are produced from the first portion. Lithium carbonate and sodium sulfate are produced from the second portion by reacting the intermediate solution with carbon dioxide. The intermediate solution may also be subjected to freezing thereby separating the lithium hydroxide from the sodium sulfate, and the separated lithium hydroxide may be reacted with carbon dioxide to produce a lithium product comprising lithium carbonate. Sodium sulfate from these processes may be reacted with an alkali chemical to produce a byproduct and a sodium hydroxide reaction fluid. The reaction fluid circulated in a continuous closed-loop into the reaction system to produce LiOH/Na.sub.2SO.sub.4 intermediate solution.

Methods to recover or separate cesium formate or rubidium formate or both from a mixed alkali metal formate blend are described. One method involves adding cesium sulfate or rubidium sulfate to the mixed alkali metal formate blend in order to preferentially precipitate potassium sulfate from the mixed alkali metal formate blend. Another method involves adding cesium carbonate or cesium bicarbonate or both to preferentially precipitate potassium carbonate/bicarbonate and/or other non-cesium or non-rubidium metals from the mixed alkali metal blend. Further optional steps are also described. Still one other method involves converting cesium sulfate to cesium hydroxide.

Methods to recover or separate cesium formate or rubidium formate or both from a mixed alkali metal formate blend are described. One method involves adding cesium sulfate or rubidium sulfate to the mixed alkali metal formate blend in order to preferentially precipitate potassium sulfate from the mixed alkali metal formate blend. Another method involves adding cesium carbonate or cesium bicarbonate or both to preferentially precipitate potassium carbonate/bicarbonate and/or other non-cesium or non-rubidium metals from the mixed alkali metal blend. Further optional steps are also described. Still one other method involves converting cesium sulfate to cesium hydroxide.