文摘
Mineral carbonation is considered to be a promising method for sequestering atmospheric CO2. This paper studied the technical feasibility of mineral carbonation of waste phosphogypsum assessed by investigating the details of the electrochemical reaction in an electrolytic cell. In a series of experiments, phosphogypsum was shown to exhibit high carbonation reactivity at conditions of room temperature and atmospheric pressure. Results show that preparation of a catholyte solution with an optimal alkalinity of pH 11 will enable production of large quantities of calcium carbonate of purity greater than 90 % at a carbonation rate of 95 %. In comparison with the traditional electrolysis process, membrane electrolysis can significantly reduce the necessary cell voltage required for the reaction to take place, while avoiding the production of chlorine gas. Injection of CO2 in the cathode chamber of the electrochemical cell decreases the pH of the catholyte, thereby depolarizing the cathode and reducing the energy consumption of the entire electrolytic process. This renders the method to be economically feasible.