Method for extracting arsenic and heavy metals from phosphoric a

Details Method for extracting arsenic and heavy metals from phosphoric a Method for extracting arsenic and heavy metals from phosphoric a

1988-08-23

1989-04-25

Heller, Gregory A.

Chemistry of inorganic compounds

Phosphorus or compound thereof

Oxygen containing

423321S, C01B 2516

Patent

active

048246506

ABSTRACT:
An improved, low cost, liquid extraction method for significantly reducing the arsenic and other heavy metal content of phosphoric acid is disclosed which can routinely achieve essential elimination of arsenic compounds while producing relatively small amounts of usable heavy metal by-product. Preferably, the impure acid (wet process or furnace grade having a P.sub.2 O.sub.5 content of about 50-65%) is initially sulfided at elevated temperatures to form arsenic and other heavy metal sulfides, whereupon the sulfided acid is allowed to set and cool; a liquid extractant, preferably carbon disulfide, is then added with agitation and subsequent setting, to form easily separable phosphoric acid and heavy metal-bearing fractions. Residual extractant can be removed from the separated acid by oxidation, leaving phosphoric acid having a very low arsenic content.

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