New method for carbon dioxide mineraliza

A new carbon mineralization method was designed based on a sequestration agent synthesized exclusively from industrial wastes. Phosphogypsum waste from the fertilizer industry was dissolved into caustic aqueous waste from the aluminum anodizing industry. The resulting precipitate consisted of katoite (Ca3Al2(OH)12, a Si-free hydrogrossular solid solution end member of the Al-containing hydrogarnet) and thenardite (Na2SO4), the latter easily removed by rinsing with water. The carbonation performance of this katoite-rich sequestration agent was evaluated using two different methods: by bubbling in aqueous media and by weathering. Both procedures yielded high carbonation efficiencies (80% and 100%, respectively) and resulted in a solid precipitate composed primarily of calcite (CaCO3) and aluminum hydroxide (Al(OH)3). Priority attention was given to the transfer of trace elements and radionuclides of the uranium series typically present in the phosphogypsum. Results confirmed that the traces were transferred to the resulting final solid carbonate at concentrations similar to those present in the raw phosphogypsum. In conclusion, these carbonated minerals would trap substantial amounts of CO2 and produce final materials with similar civil engineering uses.