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.