BigPatents India

This invention relates to an improved process for recovering sulphur dioxide from phosphogypsum. The said process is energy efficient and gives valuble solid by-products adding to the economic feasibility of the process. The use of ferrous-ferric oxide as a reducing agent for the reduction of phosphogypsum has been made for the first time to obtain sulphur dioxide and the solid product containing calcium ferrate and the reaction has been found to be feasible at lower temperature below 11oooC.