| 摘要 |
PURIFICATION OF PHOSPHORIC ACID A mixture of hydrophobic and hydrophilic extractants is used to separate phosphate values from impurities found in phosphoric acid. In one approach, impurities are removed from phosphonic acid and the phosphate values are recovered, by introducing polyphosphates and ammonium ions into the impure acid, and contacting the impure acid with a mixture of low and high molecular weight alcohols, one of which is hydrophilic and the other hydrophobic, in a single stage. The phosphate values segregate to the high molecular weight alcohol fraction, and the impurities segregate to the low molecular weight alcohol fraction. After separation of the alcohol solutions, the phosphate values and the impurities are. separated from their respective extractant solutions, and the alcohols recirculated. Polyphosphates and ammonia are preferably provided by reacting a portion of the original feed acid with ammonia at elevated temperature in a pipe reactor.
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