Abstract

Process for insolubilizing water soluble wastes from alkaline sodium or ammonium type sulfur dioxide control systems used in conjunction with industrial or power plants. The sodium or ammonium sulfite or sulfate wastes are reacted in solution with ferric ions and sulfuric acid to produce an insoluble basic, hydrous or anhydrous, sodium and/or ammonium hydroxy ferric sulfate or sulfite compounds of the generic type Mv (Na, NH4)w Fex (SOu)y (OHz)nH2 O, wherein M is selected from an alkali metal other than sodium, or an authigenic metal or other cation present in industrial or power plant wastes, v is selected from zero to six, w is selected from zero to five, x is selected from zero to six, y is selected from one to five, u is 3 and/or 4, z is selected from zero to 12, and n is selected from zero to 20. Principal end product compounds include Natrojarosite, Ammoniojarosite, Metasideronatrite, Sideronatrite, Depegite, Rosarite, Iriite, and mixtures thereof. The reaction takes place at an acid pH in a temperature ranging from about 50°-300° F. and may occur in single or multi-stage reactors. Air and/or bacterial activation at a pH of less than about 5.5 may be employed. The end product basic, sodium and/or ammonium hydroxy ferric sulfate and sulfite compounds are water insoluble as compared to the standard in the industry, CaSO4, and may be disposed of by simple landfill without the water pollution hazards inherent with landfilling of wet or dry sodium or ammonium sulfite and/or sulfate baghouse or wet scrubber wastes. The process also uses, and conversely can dispose of, other pollutants as reactants, such as hot waste water from power plant ash tanks, waste sulfuric acid, pickle liquior, acid mine water (blackwater), iron slag or scrap, or gob or pyrite leachate as part of an integrated, multiple-pollutant disposal process.

Other References

• Mellor, "A Comprehensive Treatise on Inorganic & Theoretical Chemistry," vol. 14 p. 345