Le système quinaire H 2ONaClCaCl 2SrCl 2BaCl 2: exploitation de l'isotherme 65 °C en vue de l'extraction des chlorures de baryum et de strontium

Abstract

]Preliminary treatments of barytine ores led to an aqueous solution containing sodium, calcium, strontium and barium chlorides. In order to define a rational extraction process for barium and strontium chlorides, solid—liquid equilibria were studied in the system H 2ONaClCaCl 2SrCl 2BaCl 2. First, one isoplethic section of the equilibrium diagram was studied as a whole, and a rough shape of the quintic system was worked out at 65 °C. The optimal conditions for a cyclic process to precipitate dihydrated barium chloride were determined for each unit operation: evaporation, recycling of the initial and washing solutions. The residual barium chloride in the effluents can be selectively eliminated as sulphate compound. It is then possible to extract strontium chloride according to one of the following processes: crystallization, recyling and continuous purging in the quaternary system H 2ONaClCaCl 2SrCl 2; precipitation of calcium and strontium carbonates, dissolution in a hydrochloric acid solution and crystallization of strontium chloride in the system H 2OCaCl 2SrCl 2.