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US 4,229,423 AGranted
Method of producing magnesium hydroxide
AssigneeKaiser Aluminum & Chemical Corporation
InventorsLloyd M. Housh, William R. Alder
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AssigneeKaiser Aluminum & Chemical Corporation
InventorsLloyd M. Housh, William R. Alder
Estimating the term…
A magnesium hydroxide of low lime and boron content is produced from a brine containing magnesium chloride and over 1 ppm boron (on a B.sub.2 O.sub.3 basis) by treating it to reduce its CO.sub.2 content to less than 15 ppm and reacting it with an excess of active lime in a first reaction stage, decanting the spent brine from the precipitated high lime magnesium hydroxide, and then reacting the high lime magnesium hydroxide with additional brine in a second reaction stage to produce a magnesium hydroxide containing less than 1% CaO and less than 0.1% B.sub.2 O.sub.3 on the ignited basis. A portion of the high lime magnesium hydroxide from the first reaction stage is recycled to that stage as seed. Before being discarded, the spent brine from the first reaction stage may be reacted with treated brine to precipitate magnesium hydroxide of relatively high CaO and B.sub.2 O.sub.3 content.
Method of producing magnesium hydroxide by (1) treating a brine containing Mg.sup.++ ions and at least 1 ppm boron (on a B.sub.2 O.sub.3 basis) so as to reduce its CO.sub.2 content to less than 15 ppm, (2) reacting, in a first reaction stage, the treated brine with an amount of calcined lime in excess of that needed to convert the Mg.sup.++ ion content thereof to magnesium hydroxide, (3) separating the high-lime magnesium hydroxide so produced from the spent brine, (4) recycling part of the high-lime magnesium hydroxide from the first reaction stage back to the first reaction stage as seed, and (5) reacting, in a second reaction stage, the remainder of the high-lime magnesium hydroxide produced in the first reaction stage with brine treated as in step (1), whereby a magnesium hydroxide is produced which contains, on the ignited basis, less than 1% CaO and less than 0.1% B.sub.2 O.sub.3, all percentages being by weight.
Dependencies are inferred from the claim text.