Obtaining phosphate fertilizer with additional nutrients

In order to obtain phosphorus fertilizer enriched with additional nutrients, the decomposition process of apatite concentrate with sulfuric acid was carried out with an additive, in the first variant - ammonium hydrophosphate, and in the second variant - ammonium and potassium hydrophosphates. Experimental studies have studied the effect of additives on the interaction of sulfuric acid with fluorapatite, as well as X-ray phase and IR spectroscopic analyses have studied the structural composition of the resulting product. It was found that with the use of additives, the resulting phosphorus fertilizer contains, along with calcium dihydrophosphate, also ammonium dihydrophosphate. A distinctive feature is the decomposition of sulfuric acid phosphates, resulting in a poorly soluble calcium sulfate that passes into the solid phase, which has traces of its presence in the resulting fertilizer, and may also not be part of the solution. The process of decomposition of fluorapatite with sulfuric acid using an additional part (NH4)2HPO4, the optimal amount of the additional part should be considered 12-18% (by weight of sulfuric acid) additive, while the highest degree of decomposition of apatite concentrate is achieved, which is 95-97%. The conducted studies have established that the introduction of an additive - ammonium and potassium hydrophosphates - into the process of sulfuric acid decomposition of apatite concentrate also has a positive effect on the duration of the superphosphate maturation period. To clarify the structural composition of the finished product, X-ray phase studies and IR spectrometric analysis of the powdered product were carried out. Thus, mineral fertilizers obtained with the use of additives having an additional nutrient element in their composition, namely nitrogen - in the first variant, and nitrogen and potassium - in the second variant.