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Laboratory Studies on the Treatment of Ferric Chloride Stripping Liquor from a Clay-hydrochloric Acid Leaching Process.
MISSING :7 pages
In a process being investigated by the Bureau of Mines for recovering alumina from domestic nonbauxitic resources, calcined kaolinitic clay is leached with hydrochloric acid. Iron impurity in the clay is coleached and is removed in a solvent extraction step prior to crystallization of aluminum chloride hexahydrate, which is subsequently thermally decomposed to alumina. The fecl3-hcl stripping liquor from the solvent extraction step is unsuitable for discharging to the environment; furthermore, economics requires recovery of the contained chloride values. In the present research, it was shown that the stripping liquor can be reacted with calcined clay to yield alcl3 in solution, plus precipitated iron oxides, residual silica, and unreacted excess clay as mixed solids. For the recovery of the alcl3 solution, the slurry could be separated or returned to the clay-hcl process stream at the solids washing step that follows primary hcl leaching of the clay. For the range 20 deg to 99 deg c, the time (t) (10 3 sec) required to react the waste liquor with excess clay, for essentially complete iron precipitation, depends on the absolute temperature (t) chosen, according to the expression: t = e [(9,000/t) - 23.5]. Alumina was tried as a reagent alternative to clay but was not very effective, even under pressure and at high temperatures.
IH; Report of Investigations
Page last reviewed: April 12, 2019
Content source: National Institute for Occupational Safety and Health Education and Information Division