Title : Production of DCF, phosphate fertilizer from the waste precipitate of acidic water neutralization at the kutina phosphate gypsum landfill
Abstract:
By neutralizing acidic water with pH 2.4 using CaO, a neutralization precipitate (TN) is formed containing 21% P2O5, 18% F (fluoride), 39% CaO, 6% SiO2, and 14% LOI. In a two-step process, by acting on TN with Ca(OH)2, in the first step CaF2 is separated by changing the pH value, and in the second step DCF is formed. DCF, dicalcium phosphate, is prepared using an innovative process by changing the pH and contains 12 to 14% P (phosphorus), less than 2% F, about 42% CaO, and a range of trace elements. Potassium sulphate, K2SO4, produced from KCl and phosphogypsum, has a composition of 22% S, 20% CaO, 3.7% K2O, and 52% LOI. Procedures for converting K2SO4 fertilizer were also tested: CaSO4·2H2O + 2 KCl = K2SO4 + CaCl2 + H2O……CaCl2, and (NH4)2SO4 + 2 KCl = K2SO4 + 2 NH4Cl……NH4Cl is a liquid fertilizer. NH4Cl + UREA - in a 50/50 ratio gives a fertilizer with total N = 36%. It is important to note that the process takes place in a reactor (equipped with a water bath up to 95°C to accelerate the process and a stirrer up to 500 rpm), without pressure and within the range of normal temperatures (usually 20 to 35°C).
