Distribution of Impurities in Crystallization of Ammonium otassium A DAVID SCHLAIN, JOHN D. PRATER, AND S. F. KAVZTZ Intermountain Experiment Station, U . S . Bureuu of Mines, Salt Lake City, Utah
A study has been made of
Accordingly, most of the tests in the present investigation were made under similar conditions.
the distribution of ferric iron,
ferrous iron, potassium, phosphorus, magnesium, and
sodium in the crystallization of ammonium alum, and of ferric iron and ferrous iron in the crystallization of potassium alum. The results are correlated with the ionic radii of the ions concerned and with distribution laws.
A separate series of tests was carried out for each impurity, the pregnant solutions for each series containing a constant concentration of ammonium or potassium alum, various concentrations of the impurity, and 0.5% sulfuric acid. All solutions were prepared from C.P. chemicals and distilled water, the ammonium and potassium alums first being purified by several recrystallizations so that their impurity content was nrg!igible. In tests with ferrous iron, the solutions were prepared with freshly boiled water, and nitrogen was passed through the solutions during preparation and crystallization to prevent oxidation by air. I n most of the tests the ammonium alum pregnant solutions contained 608 grams of IVIIdAl(SQ4)2.12H& per liter, corresponding to a saturation temperature of 73.6" C. for the alum alone, and the potassium alum pregnant solutions contained 908 grams of I
