湿式亜鉛製錬工程におけるシリカの基礎的挙動について [in Japanese] Behavior of Silica in the Zinc Refinery Process [in Japanese]
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In recent year, it is necessary to treat imported ore in zinc hydrometallurgy because of stable demand of material and depletion of domestic mine. However, the imported ore often contains a lot of impurities. Among them, SiO<SUB>2</SUB> complicates solid-liquid separation after leaching process. The cause of this degradation is understood that Zn<SUB>2</SUB>SiO<SUB>4</SUB> produced in roasting process is leached in leaching process, and then supersaturated silica solves in solution. In previous research, it was reported that solid-liquid separation was improved by increasing of pH and temperature, and seed method was effective for reducing SiO<SUB>2</SUB> concentration. However, mechanism of the solid-liquid separation improvement hasn't been well understood. The purpose of this paper is to obtain the knowledge for the effects of temperature, pH and impurities on silica polymerization.<BR>(1) Solution temperature influences the colloidal silica polymerization, and the polymerization is promoted as the temperature is elevated.<BR>(2) In the solution of pH range from 1 to 3, the polymerization rate is almost the same. When pH is raised to 4, the polymerization rate has been promted.<BR>(3) Hydrolysis reaction of Fe and Al influences the decreasing of SiO<SUB>2</SUB> concentration by rising pH in field test.<BR>(4) Addition of silica seed has greatly reduced the ionic and colloidal silica in the solution.
Shigen-to-Sozai 124(3), 173-178, 2008-03-25
The Mining and Materials Processing Institute of Japan