| 摘要 |
Superior quality magnesium calcium acetate (hydrate) granules of industrial grade are produced from a concentrated aqueous solution of magnesium acetate containing limited amounts of calcium acetate. The hot solution, or process liquor, is carefully pH-adjusted prior to further processing, and may be slightly acidified with excess acetic acid to offset downstream hydrolysis during the granulation/drying stage. Process liquor hydrolysis is avoided by maintaining liquor temperature and residence time within prescribed limits. Process liquor may be optionally clarified of mineral insolubles deriving from raw material, and of excess, unwanted calcium acetate solids prior to further processing. From such clarified liquor a purer, technical grade magnesium acetate (hydrate) granular product is derived. Hot process liquor may be passed through a short residence time heating zone prior to granulation/drying in order to provide additional sensible heat going to the granulation/drying operation. At the short residence times prescribed, hydrolysis of process liquor is avoided. A key feature of the invention is the relatively low energy requirement, due to the low process liquor drying requirement. Such a low net water loss requirement is due to the unusually high concentrations of process liquor achievable, and to the production of a stable tetrahydrate of magnesium acetate product. Product granules of the present invention, free of unreacted ore, and of hydrolysis product, show much improved rates of ice-melting, and are elatively less corrosive to metals.
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