Obtaining ammophosphate and sulfoammophosphate fertilizers on base of the washed dry concentrate containing 26% P₂O₅

¹ Namangan State University, Namangan, Republic of Uzbekistan
² Institute General and inorganic chemistry Academy Sciences of the Republic Uzbekistan, Toshkent, Republic of Uzbekistan
³ Navoi State University of Mining and Technologies, Navoi, Republic of Uzbekistan

^* Corresponding author: temirov-2012@mail.ru

Abstract

The process of obtaining ammophosphate by means of phosphoric acid decomposition of washed dried concentrate (WDC with 26% P₂O₅ and 10% CO₂) - raw material for the production of thermally fired concentrate, has been studied. The wet process phosphoric acid (WPA) contains (wt.%): 16.46 P₂O₅, 0.06 CaO, 1.11 MgO, 0.27 Fe₂O₃, 0.41 Al₂O₃, 2.98 SO₃ and 0.99 F. The weight ratio of WPA:WDC ranged from 100: 10 to 100: 30. Then acidic phosphate pulps (at 65 °C) after 45 minutes were ammoniated to pH = 3.8, granulated and dried at 85-90 °C. It has been shown that the nitrogen content in the finished product ranges from 4.92-7.11%, total phosphorus (P₂O_5t.) 41.48-46.44%, phosphorus acceptable by citric acid (P₂O_5ac.c.a.) 34.79-45.11%, phosphorus form of water soluble (P₂O_5w.s.) 23.49-37.73%. Weight fractions of H₂SO₄ - 5 and 7.5 were optimal and the product contains 37.6 and 34.47% of P₂O_5t.; 24.11 and 22.06% CaO_t., 88.75 and 92.40% P₂O_5ac.c.a.by citric acid: P₂O_5t., 84.21 and 89.7% P₂O_5ac.tr.b. by trilon B: P₂O_5t., 77.39 and 79.54% P₂O_5w.s.:P₂O_5t., 6.03 and 7.08% nitrogen, respectively. The strength of granules of fertilizers averages 3.50 MPa and are quite suitable for bulk storage and transportation.