Characterization and Processing of Phosphate Rock as a Raw Material for Potential Use as Biomaterials

Seventy-five percent of the phosphate rock extracted is used for the production of phosphoric acid. However, during the leaching process, it is also possible to dissolve calcium compounds, allowing for the extraction of phosphorus and calcium ions from the resulting solution. This study focused on the application of hydrometallurgical processes directly to phosphate rock to obtain calcium phosphates with potential applications in the manufacture of biomaterials. After a physicochemical characterization of four phosphate rock samples, one sample was subjected to a hydrometallurgical process using nitric acid. The leachate was then neutralized with sodium hydroxide to achieve a pH between 4.5 and 12. One sample of the precipitate was dried at ambient temperature, while another was dried at 70°C. Depending on the pH and the Ca/P molar ratio, three types of calcium phosphates were obtained. X-ray diffraction analysis identified the three phases as octacalcium phosphate, hydroxyapatite, and monetite, all of which are recognized as biomaterials.