Ammonized Superphosphate and Liquid Nitrogen-Phosphorus Fertilizer Based on the Decomposition of Washed Dryed Concentrate with a Mixture of Sulfuric and Phosphoric Acids

Abstract

The process of obtaining ammoniated superphosphate and liquid NP-fertilizer by phosphorus-sulphuric acid processing of washed and burned phosphorus concentrate (WBPC) in one cycle were studied. It has been established that at ratios of 100 : 5÷10 : 15 the compositions of ammoniated superphosphate samples are characterized as follows (wt., %): Р2О5total(t.). - 20.60-24.85; Р2О5free - absent; Р2О5acceptable by citric acid(ac.c.a.):Р2О5t. = 91.03-100; Р2О5water.solubility(w.s.). : Р2О5t. = 78.87-96.86; N - 4.20-4.79; pH - 2.95-3.17. The product is mainly from calcium sulfate di- and hemihydrate, mono-ammonium phosphate, mono- and dicalcium phosphate, quartz and activated fluorocarbonate apatite. A liquid NP fertilizer consists of 3.22-4.49% N, 16.92-17.75% P2O5, 2.18-2.86% CaO, 0.09-0.19% MgO, 0.5 -0.6% SO3, 0.10-0.11% Fe2O3, 0.003-0.007% Al2O3, while Р2О5ac.c.a.:Р2О5t. = 97.75-100% and Р2О5w.s.: Р2О5t. = 96.93-100%. The material balance of obtaining ammoniated superphosphate and liquid NP-fertilizer in one cycle is calculated. It has been shown that the ammonization of phosphorus-sulfuric acid phosphate pulp results in the maximum precipitation of insoluble components in the form of complex salts, which ensures the production of a purified liquid complex fertilizer for drip irrigation.