Preparation of Highly Purified Sodium Sulfate and Hydrogen Sulfide from Smelt

Studies were made on the preparation of high purities of sodium sulfate and hydrogen sulfide.Material for testing was smelt (17.5% of Na2S ; 52.5% of Na2CO3 ; 3.12% of Na2S2O3 ; 14.7% of Na2SO4 ; 3.52% of Na2SO3 ;0.05% of Fe2O3 and Al2O3; 0.63% of SiO2, etc.) obtained from the combustion of a NSSC black liquor in a KP type recovery furnace. Several effective methods were found out, but Process D was the simplest of all.Process DThe smelt was dissolved by water to prepare an aqueous solution (a green liquor). The green liquor was treated with 6N-H2SO4 to prepare an acid solution while generating hydrogen sulfide (83.4% of H2S ; 13.6% of CO2