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Statistical analysis of the removal of aluminum and magnesium impurities from wet‐process phosphoric acid
Author(s) -
Feki M.,
Chaabouni M.,
Ayedi H. F.,
Heughebaert J. C.,
Vaillant M.
Publication year - 1987
Publication title -
the canadian journal of chemical engineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.404
H-Index - 67
eISSN - 1939-019X
pISSN - 0008-4034
DOI - 10.1002/cjce.5450650121
Subject(s) - phosphoric acid , hydrofluoric acid , magnesium , impurity , precipitation , chemistry , inorganic chemistry , aluminium , ammonium , magnesium nitrate , ammonium nitrate , salt (chemistry) , nuclear chemistry , organic chemistry , physics , meteorology
The present paper relates to the treatment of crude wet‐process phosphoric acid with ammonium nitrate and hydrofluoric acid to precipitate aluminum and magnesium impurities in the form of an easily separable phase: (NH 4 ) x Mg y Al z (F, OH) 6 .2 H 2 O. To check the effect of some concentration factors on this reaction, an orthogonal central composite design is realized with three variables: %Al 3+ , %NH 4 + and %F − . It is concluded that the amount of aluminum in acid is the limiting factor of magnesium precipitation. Thus complete removal of magnesium, which is a major impurity in wet‐process phosphoric acid, can be obtained by adding to the crude acid extra soluble aluminum salt simultaneously with hydrofluoric acid and ammonium nitrate.