オゾン法による粘土原料の脱鉄処理

概要

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Ozone was used for purification of the pyrophyllitic roseki clay contaminated with pyrite impurities. The greater part of pyrite particles were removed in advance by froth flotation from the crude slurry prepared with special attention to avoid the excess size reduction of pyrite. Then the remaining pyrite in the clay was oxidized with ozone, resulting in the formation of iron sulfate and sulfuric acid. As the oxidation reaction occurs at the interface of pyrite and the sorrounding solution, the rate of iron dissolution depends on the specific surface area of pyrite. The pyrite in the clay fractions with particle size under 2μm existed almost in the form of isolated particles and is found to be dissolved with high efficiency. In contrast, a considerable amount of pyrite in the clay fractions with coarse particle size is encapsulated in the roseki clay particles. Consequently, the rate of iron dissolution from the pyrite is low, resulting in the decrease of deironation efficiency. On the other hand, the deironation efficiency was also influenced by the pH condition of the clay slurries and tends to become higher as the pH value is lower due to the increase in the solubility of iron ion~ However, since the clay structure degrades in a low pH region, the pH conditions are appropriate for the deironation treatment of the roseki clay are around pH2.5-3 at the start and around pH2-2.5 at the final.
日本粘土学会の論文
1993-08-31