TREATMENT OF WASTE WATER GENERATED IN PRODUCING PHOSPHORIC ACID BY PERFORMING WET DECOMPOSITION OF PHOSPHATE ORE WITH SULFURIC ACID

摘要

In this process, the gypsum slurry produced in the crude phosphate digestion is stored as a liquid and the waste water draining from the gypsum slurry dump is subjected to a two-stage neutralization. In this, the waste water is first brought to a pH of 2.5 to 4.5 by addition of calcium ions and is then brought to a pH of 9 to 13. After the slurry separation has been carried out, all or part of the neutralized waste water is returned as washing water to the phosphoric acid filtration stage. Excess waste water in this case can be disposed of by evaporation.