ENHANCING FERTILIZER FORMULATION USING MINING WASTE: SUBSTITUTION OF PHOSPHORIC ACID WITH SLIMES AND CHARACTERIZATION OF RESULTING FERTILIZERS

This study aims to valorize the slimes (<40 µm and rich in P₂O₅) generated during the processing of phosphate ore from Taiba by formulating complex compound fertilizers using these wastes as a source of P₂O₅ through the progressive substitution of phosphoric acid. Following a complete characterization of the raw material using atomic absorption spectrophotometry and X-ray fluorescence, NPK complex fertilizers of formulas 6-20-10, 15-10-10 and 15-15-15 were produced for local use. To obtain these fertilizers, different sources of fertilizer were used, such as urea containing 46% N, potassium sulfate with 51% K₂O, phosphoric acid with 52% and slimes with 24% P₂O₅. The primary objective was to develop calculation methods to control the concentrations, while the secondary objective was to produce fertilizers assimilable by plants. The analyses yielded highly satisfactory results for the 3 formulas, with differences of -2% for the 6-20-10 and 15-10-10 formulas and slightly +2% for the 15-15-15. The values of total P₂O₅ and that assimilable by plants were very close, with a difference of -1%, highlighting the quality of the fertilizer produced, as also indicated by the ratio C/N<10. Moisture content between 4 and 15% are indicative of granulation, but does not affect quality of the fertilizer. In 95% of cases, the organic matter (OM) content far exceeds the required value of 0.5% for optimum plant development