Removal of sulfur dioxide from waste gases by aqueous suspensions of dolomitized phosphates

The oxidation of the SO/sub 2/ from waste gases to form H/sub 2/SO/sub 4/ which reacts to decompose the carbonate in the phosphate rock suspensions to sulfates is catalyzed by the presence in the ores of compounds of Mg, Fe, Ca, etc. CaSO/sub 4/ is precipitated in the form of crystals while the MgSO/sub 4/ that is formed is passed into solution. The proposed reaction is CaMg(CO/sub 3/)/sub 2/ + 2H/sub 2/SO/sub 4/ ..-->.. CaSO/sub 4/ + MgSO/sub 4/ + 2H/sub 2/O + 2CO/sub 2/. The reaction rate is controlled by the oxidation of SO/sub 2/ which is dependent upon the temperature and the concentration of O/sub 2/ in the liquid phase of the suspension. 100% oxidation of the SO/sub 2/ is realized if the optimum temperature range for the process is 60 to 90/sup 0/C and the oxygen concentration in the gas is >5%. Under experimental conditions, a froth absorber with 3 or 4 traps was found to insure complete absorption of the SO/sub 2/. (BLM)