The process of recrystallization of apatite phosphogypsum (PHG) in a solution of ammonium sulphate (AS) with the subsequent decomposition of the binary salt was investigated and the resulting highly dispersed products with a low P2O5 content have been discussed. The following effects were examined: (NH4)(2)SO4 concentration, the quantity of ammonium sulphate, the reaction temperature of phosphogypsum with (NH4)(2)SO4 solution, the time of treatment of phosphogypsum with (NH4)(2)SO4 solution and the decomposition of the binary salt, as well as the liquid/solid ratio for the binary salts. Based on the results of the chemical and X-ray analysis, it was established that, depending on the technological conditions of the processes of recrystallization, binary salts of (NH4)(2)SO4 . CaSO4 . H2O and of (NH4)(2)SO4 . 5 CaSO4 . H2O were formed. As a result of the investigations carried out, a product with a low P2O5 content, suitable for direct processing to secondary products has been prepared.