Abstract: A process for purifying a manganese sulfate solution and precipitating high purity manganese sulfate monohydrate crystals. The concentration of manganese sulfate is increased and calcium and magnesium are removed by precipitating calcium and magnesium fluoride, which are separated from the concentrated solution to produce a clarified solution. In a first crystallization step, the clarified solution is combined with a recycled manganese sulfate solution and manganese sulfate seed crystals and the mixture is heated to produce a crystal suspension. Manganese sulfate crystals are separated and the remaining solution is used to prepare solid manganese fluoride, which is separated and returned to the process to remove calcium and magnesium. The manganese sulfate crystals are redissolved in water. Undissolved solids are removed to produce a second clarified manganese sulfate solution.

Abstract: A process for purifying a manganese sulfate solution and precipitating high purity manganese sulfate monohydrate crystals. The concentration of manganese sulfate is increased and calcium and magnesium are removed by precipitating calcium and magnesium fluoride, which are separated from the concentrated solution to produce a clarified solution. In a first crystallization step, the clarified solution is combined with a recycled manganese sulfate solution and manganese sulfate seed crystals and the mixture is heated to produce a crystal suspension. Manganese sulfate crystals are separated and the remaining solution is used to prepare solid manganese fluoride, which is separated and returned to the process to remove calcium and magnesium. The manganese sulfate crystals are redissolved in water. Undissolved solids are removed to produce a second clarified manganese sulfate solution.

Abstract: In accordance with the process of the invention, bacteria are used to provide hydrogen sulfide and carbonate compounds for treating solutions containing metal ions. To produce the hydrogen sulfide, the bacteria utilize sulfate ions present in the solution. Hydrogen sulfide produced by the bacteria is used to remove metals from the solution as insoluble metal sulfides. The process of the invention thereby removes sulfate and metal ions from the treated solution. The bacteria used are mixed populations, including strains of naturally-occurring sulfate reducing bacteria, which have been serially adapted and selected to be highly active with the particular solutions to be treated and with the carbon and hydrogen sources being utilized. The bacteria may be fed gaseous hydrogen and carbon nutrients produced by a partial oxidation burner. Carbonate compounds produced by the bacteria may be used to raise the solution pH for treatment and discharge.