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Raw calcium phosphate obtained by adding phosphoric acid to phosphate ore yields industrial triple super phosphate (TSP), consisting of calcium phosphate that contains many impurities. TSP was dissolved in a minimum amount of water, filtered to remove insoluble compounds and evaporated to dryness. This produced monocalcium phosphate monohydrate of high purity and solubility. The starting materials and final recrystallized products were analyzed by several methods (X-ray diffraction (XRD), infrared (IR), nuclear magnetic resonance (NMR), thermogravimetry−differential scanning calorimetry (TG-DSC), scanning electron microscopy (SEM)) confirming that the purified product is monocalcium phosphate monohydrate that can be used as a soluble fertilizer free of contaminants.

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The Sekarna Zn-Pb deposit is located in Central Tunisia at the northeastern edge of the Cenozoic Rohia graben. Mineralization comprises two major ore types: (1) disseminated Zn-Pb sulfides that occur as lenses in sedimentary phosphorite layers and (2) cavity-filling zinc oxides (calamine-type ores) that crosscut Late Cretaceous and Early Eocene limestone. We studied Zn sulfide mineralization in the Saint Pierre ore body, which is hosted in a 5-m-thick sedimentary phosphorite unit of Early Eocene age. The sulfide mineralization occurs as replacements of carbonate cement in phosphorite. The ores comprise stratiform lenses rich in sphalerite with minor galena, Fe sulfides, and earlier diagenetic barite. Laser ablation-inductively coupled plasma mass spectrometry analyses of sphalerite and galena show a wide range of minor element contents with significant enrichment of cadmium in both sphalerite (6,000-20,000 ppm) and galena (12-189 ppm). The minor element enrichments likely reflect the influence of the immediate organic-rich host rocks. Fluid inclusions in sphalerite give homogenization temperatures of 80-130°C. The final ice melting temperatures range from −22°C to −11°C, which correspond to salinities of 15-24 wt. % NaCl eq. and suggest a basinal brine origin for the fluids. Sulfur isotope analyses show uniformly negative values for sphalerite (−11.2‰ to −9.3‰) and galena (−16‰ to −12.3‰). The δ 34 S of barite, which averages 25.1‰, is 4‰ higher than the value for Eocene seawater sulfate. The sulfur isotopic compositions are inferred to reflect sulfur derivation through bacterial reduction of contemporaneous seawater sulfate, possibly in restricted basins where organic matter was abundant. The Pb isotopes suggest an upper crustal lead source.