Treating residual acidic waters from chemical fertiliser industry with phosphorus and opt. phospho-gypsum by use as reagent and creation of high calcium carbonate content

Residual acidic waters, obtd. in the chemical fertilizer industry with P, from the prodn. of H2SO4, H3PO4, superphosphate, AlF3, etc., contaminated with H2SO4, H3PO4, H2SiF6, HF etc., with or without phospho-gypsym, transported hydraulically, are treated by their use as treatment reagent.
A high content, e.g. 85-95%, of CaCO3 is formed, either as a powder having granulation below 3 mm or as a sludge contg. 5-65% chalk dust having granulation below 3 mm and 95-35% fresh water, treated and recirculated water, sea-water or directly, residual acidic waters sepd. from phospho-gypsum, as such as or in any mixt.