manner of forced cycle and concentration such that the heat transfer efficiency is improved the cycle is intensive the evaporation rate is fast the heating time is short and the scaling will not readily occur the temperature of the feed magnesium sulfate solution of the three effect evaporation and concentration is 30 u02dc 40 u00b0 c and the density is 1 1 u02dc 1 26 t m 3 the temperature of the magnesium sulfate solution after evaporation is 60 u02dc 70 u00b0 c and the density is 1 32 u02dc 1 46 t m 3 the crystallization equipment of the present invention is configured to receive the concentration product formed from the concentration equipment and generate crystal particles in the concentration product so as to acquire a concentration product containing magnesium sulfate crystals preferably the crystallization equipment of the present invention is configured for cooling crystallization of the concentration product so as to precipitate magnesium sulfate from the solution the crystallization equipment is preferably a continuous cooling crystallizer further preferably dtb continuous cooling crystallizer most preferably three stage recrystallization flash tank where the magnesium sulfate waste solution goes from a first effect concentration through a second effect concentration and to a third effect concentration with a concentration degree reaching 38 which is already a saturated solution and then the crystal solution is pumped out by a discharging pump and delivered to a three stage recrystallization flash tank to precipitate for crystallization the.