| 摘要 |
PROBLEM TO BE SOLVED: To provide a novel method for removing arsenic from phosphoric acid which does not require any of a filtering and a degassing processes, which are necessary in the sulfide precipitation method, does not give a large amount of residual sodium, can be applied to a phosphoric acid having a high concentration, particularly to polyphosphoric acid, and can be practiced at a low cost; and to provide a high-purity polyphosphoric acid having a low content of arsenic, which is not conventionally seen, and low contents of heavy metals, silica, sodium and the like, that is, ≤20 ppm of iron (Fe), ≤100 ppm of sodium (Na), ≤50ppm of silica (SiO<SB>2</SB>) and ≤1 ppm of arsenic (As), and further ≤5 ppm of chromium (Cr), ≤5 ppm of nickel (Ni) and ≤5 ppm of molybdenum (Mo). SOLUTION: The method for purification of phosphoric acid comprises contacting phosphoric acid containing arsenic with a hydrogen halide to remove the arsenic from the phosphoric acid and comprises contacting phosphoric acid containing arsenic with a hydrogen halide in the presence of a compound which can produce a hydrogen halide under an acidic condition. COPYRIGHT: (C)2009,JPO&INPIT
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