Abstract: A method for chemical processing of sewage sludge ash comprises dissolving a start material, emanating from sewage sludge ash, in an acid comprising hydrochloric acid. The start material comprising at least silicon and iron compounds. Undissolved residues are separated, whereby a leachate remains. The amount of colloidal silica in the dissolved sewage sludge ash is controlled. At least one of iron and phosphorus is extracted from the leachate by liquid-liquid extraction with an organic solvent. At least a part of a raffinate at least partly depleted in at least one of iron and phosphorus originating from the step of extracting at least one of iron and phosphorus is recirculated for dissolving the start material, emanating from sewage sludge ash. The recirculated part of the raffinate at least partly depleted in at least one of iron and phosphorus comprises chloride ions.

Abstract: A method for recovery of commercial substances from apatite mineral comprises dissolving of apatite mineral in an acid comprising hydrochloride. The dissolution gives a first liquid solution comprising phosphate, calcium and chloride ions. The first liquid solution is treated into a second liquid solution comprising calcium and chloride ions. This treatment in turn comprises extracting of a major part of the phosphate ions with an organic solvent. A bleed solution is removed from the second solution. Solid gypsum comprising at least 70% in a di-hydrate crystal form is precipitated from the second solution. This precipitation of solid gypsum comprises adding the second solution and sulfuric acid simultaneously into a continuous-stirred reactor in the presence of gypsum crystals. Thereby, the precipitation of solid gypsum gives a third liquid solution comprising hydrochloride. An arrangement for recovery of commercial substances from apatite mineral is also presented.

Abstract: An arrangement for production of fully soluble, pure and well-defined mono- or di-potassium phosphates, comprises an extraction section, a stripping section and end treatment arrangements. The extraction section performs a liquid-liquid extraction of phosphate between a feed liquid comprising phosphoric acid. The stripping section performs a liquid-liquid extraction of phosphate between solvent loaded with phosphate and a strip solution. The solvent depleted in phosphate is recirculated to the extraction section for further extraction of phosphate. The strip solution is an aqueous potassium phosphate solution. The end treatment arrangements comprise a source of potassium base, an adding arrangement, a cooling arrangement, a precipitate remover and a recirculation system.