| 摘要 |
Process for the production of aluminium hydroxide by digesting bauxite with alkali solution and precipitating aluminium hydroxide from the digestion solution, comprising: a combining bauxite and alkali solution having a caustic concentration of at least 180 grams per liter expressed as sodium carbonate and digesting partly the bauxite in the combined product in a first digestion step at relatively low temperature, b separating reaction product obtained in step a into a liquid phase and a solids/liquid slurry, c combining liquid phase and solids/liquid slurry obtained in step b and digesting the combined product in a second digestion step at relatively high temperature, d releasing heat from the reaction product obtained in step c to preheat liquid phase obtained in step b, e separating the reaction product obtained in step d into a supersaturated sodium aluminate solution and undissolved material, f precipitating aluminium hydroxide from the supersaturated sodium aluminate solution obtained in step e and separating aluminium hydroxide from the spent liquor, and recycling spent liquor obtained in step f to step a for use as alkali solution.
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