What is red sludge?
AP noted: Hungary declared a state of emergency in three counties Tuesday [5 Oct 10] after a flood of toxic red sludge from an alumina plant engulfed several towns and burned people through their clothes.
US 6,248,302 gives a view of the content of red sludge: The Bayer process is used for recovering substantially pure alumina from bauxite and uses NaOH to dissolve the alumina in the bauxite. Most of the other components of the bauxite are inert in the process, except silica, some of which reacts with the hydroxide. The inert components and the silica and silica compounds are rejected and are referred to as red mud or red sludge. This waste product from the Bayer process has presented serious disposal problems. Red mud can contain 11 to 45 wt. % Al.sub.2 O.sub.3, 5 to 66 wt. % Fe.sub.2 O.sub.3, 1 to 16 wt. % SiO.sub.2, 6 to 17 wt. % TiO.sub.2 and 3 to 8 wt. % Na.sub.2 O.
US 6,248,302 gives a view of the content of red sludge: The Bayer process is used for recovering substantially pure alumina from bauxite and uses NaOH to dissolve the alumina in the bauxite. Most of the other components of the bauxite are inert in the process, except silica, some of which reacts with the hydroxide. The inert components and the silica and silica compounds are rejected and are referred to as red mud or red sludge. This waste product from the Bayer process has presented serious disposal problems. Red mud can contain 11 to 45 wt. % Al.sub.2 O.sub.3, 5 to 66 wt. % Fe.sub.2 O.sub.3, 1 to 16 wt. % SiO.sub.2, 6 to 17 wt. % TiO.sub.2 and 3 to 8 wt. % Na.sub.2 O.
posted by Lawrence B. Ebert at 10:17 AM
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