TY JOUR TI RESEARCH OF PHYSICAL AND CHEMICAL PROCESSES IN THE CALCIUM SULPHATE – MAGNETITE SYSTEM KW magnetite KW hematite KW insoluble anhydrite KW plaster KW cement plaster KW iron ore concentrate of Lebedinsky GOK KW potentiometry KW XRF KW Gibbs free energy JO Bulletin of Belgorod State Technological University named after. V. G. Shukhov AU Klimenko, V.. AU Gasanov, S.K. AU Kashin, G.A. PY 2017 IS 2 PB Belgorod State Technological University named after V.G. Shukhov