6 Raw Composition of Neutralized Gypsum for Cement
and Method for Producing the Neutralized Gypsum

(43) 09.06.2025

The present invention relates to a technology for manufacturing neutralized gypsum, which can be advantageously used in the manufacture of cement with reduced hexavalent chromium by utilizing waste sulfuric acid discharged from semiconductor processes, etc., to produce and manufacture iron sulfate hydrate together with neutralized gypsum.

The neutralized gypsum manufacturing technology according to the present invention is characterized by manufacturing the neutralized gypsum using a raw material composition including: waste sulfuric acid; limestone mineral selected from at least one of calcium carbonate, slaked lime, and quicklime; supercritical fluidized bed boiler bottom ash; sodium sulfate; and a mixture of a steelmaking by-product and a weak acid. More preferably, it comprises 10 to 40 wt% of spent sulfuric acid having a purity of 40 to 55 wt%; 20 to 35 wt% of limestone mineral; 15 to 25 wt% of supercritical fluidized bed boiler bottom ash; 0.1 to 0.5 wt% of sodium sulfate; and 20 to 35 wt% of a mixture of a steelmaking by-product and a weak acid. However, it can be manufactured using a mixture of a steelmaking by-product and a weak acid, in which 100 wt% of a steelmaking by-product containing 40 to 55 wt% of T.Fe is mixed with 0.5 to 3.0 wt% of a weak acid containing 55 to 70 wt% of sodium acetate.