Treatment of sulfuric acid wastewater
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For wastewater containing 5% sulfuric acid, 10% lime milk is added; filtration under a pH of 2 yields anhydrous gypsum. How can the product be converted into gypsum dihydrate? Many documents and papers state that the product formed in such wastewater is gypsum dihydrate; how is this achieved?
Is it to produce calcium sulfate dihydrate?
What is your production process? Is the purpose to produce calcium sulfate dihydrate?
After filtration, how do you determine whether it is anhydrous gypsum or dihydrate gypsum?
Drying at 235 degrees to determine the amount of crystalline water is the standard method; I am aiming to produce calcium sulfate dihydrate
OP, is sulfuric acid wastewater the phosphorus-removal wastewater from steel mills? The latest approach involves using specialized membrane separation technology to recover sulfuric acid from sulfuric acid wastewater, which can then be reused ； It reduces waste discharge, recovers sulfuric acid, and saves production costs.
Is your acid produced from pyrite or from flue gas from smelting?
I just want to remind you: why use precipitation conditions with pH=2? What is the dissociation constant pKa2 of the bisulfate ion, as a weak acid? PKa2=1.98. What is the solubility of calcium sulfate? What is the solubility of calcium bisulfate? Do you intend to obtain a mixed precipitate of calcium sulfate (regardless of the amount of water it contains) and calcium bisulfate?