Aluminum Company of America

William A Nigro

Gary A O'Neill

Paul J The

Richard H Goheen

A method for treating caustic solutions to remove colorants, including iron, therefrom comprises: contacting the solution with a substance comprising a calcined product of a compound having the formula: A.sub.w B.sub.x (OH).sub.y C.sub.z.nH.sub.2 O, wherein A represents a divalent metal cation; B a trivalent metal cation; C a mono- to tetravalent anion; and w, x, y, z and n satisfying the following: 0&lt;z.ltoreq.x.ltoreq.4.ltoreq.w.ltoreq.1/2y and 12.gtoreq.n.gtoreq.1/2(w-x). On a preferred basis, the contacted substance is a hydrotalcite derivative made by reacting activated magnesia with an aqueous solution of aluminate, carbonate, and hydroxyl anions before calcining at one or more temperatures between about 400.degree.-650.degree. C. There is further disclosed a method for producing an aluminum hydroxide having improved whiteness according to the invention.

Method for reducing the amount of colorants in a caustic liquor

A process for producing aluminum hydroxide including the steps of:

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Benton, AR, United States of America

William A Nigro