Abstract: A process for the removal of substantially chromium free sulfate from aqueous alkali metal solutions containing chromate and sulfate which includes mixing the solutions while having a pH of between about 2.5 and 4.5 with a calcium-containing material for a time and at a temperature sufficient to form a gypsum precipitate and separating that precipitate from the solutions; as well as a process for the production of alkali metal chlorate by electrolysis of alkali metal chloride including the removal of chromium free sulfate.

Abstract: Mixer-settler apparatus of the reverse liquid flow type having at least one assembly which includes one or more mixers in series, each being fitted with stirrers and pumps, at least one settling tank in which liquids separate, and at least one submerged chute extending into the settling tank from a pump to convey the mixture of liquids from the pumps to the settling tank. The chute is constructed of enlarged dimensions which extend over a major portion of the width of the tank to facilitate a pre-settling action within the chute, and the chute extends a substantial distance into the settling tank to allow extended pre-settling time.