We studied the processes of desulfurization of phosphoric acid obtained by wet process from washed and roasted concentrate and subsequent purification of acid from bivalent and trivalent metals and fluorine via partial ammonization (at pH of 2 to 4). Purified ammoniated slurry containing 16.96% P2O5, 8.06% N, 0.09% CaO, 0.58% MgO, 0.004% Fe2O3, 0.031% A12O3, 0.78% SO3 and 0.52% F was fabricated by the removal of precipitates at the stages of desulfurization and partial ammonization. The rheological properties of ammoniated slurry with 40% moisture were studied. When the temperature is increased from 40 to 800C, both the density and viscosity decrease from 1.395 to 1.365 g cm–3 and from 80.8 to 48.7 cP, respectively. Ammoniated suspension with pH of 5.5 and 8.5 was applied to prepare mono- and diammonium phosphates with the ratio P2O5:N of 52:14 and 48:18, respectively. The sludge obtained after desulfurization and ammonization processes can be used as a slow-release fertilizer.
Methods for improving the composition and properties of ammonium nitrate (AN) using various inorganic additives are considered. It has been shown that the employing Suprefos-NS, a product of JSC “Ammofos-Maxam”, as an additive in the AN melt allows obtaining a stabilized fertilizer containing, except nitrogen and phosphorus, macroelements such as calcium and sulfur, exclusively in assimilable forms. In this case, the mass ratio AN: Suprefos-NS varied in the range from 100: 5 to 100: 35. It was found that any amount of Suprefos-NS additives significantly improves the composition and properties of the AN.
Complex, nitrogen-phosphate fertilisers are applied before seeding, with seeding and extra nutrition, while single phosphoric ones are the most effective under autumn ploughing. In that case, enriched superphosphate, more concentrated than single superphosphate, was obtained using phosphoric acid gypsum slurry semiproduct produced by the interaction of thermo concentrate with sulphuric acid and recycled phosphoric acid in accordingly dihydrate operation (60-80°C). However, the mix of sulphuric and phosphoric acids was not used those are usually applied in conventional ways for enriched superphosphate production. Phosphate raw material (PRM) is dosed into phosphoric acid gypsum slurry (PAGS) upon weight ratio of PAGS: PRM equal from 100: 15 to 100: 40 that provides a condition for slurry fluidity. Interaction of the components was
Original Research Article
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