| 摘要 |
<p>1. Method of treating liquors used in the causticisation cycle for digestion of wood by the kraft process allowing obtaining of calcium carbonate which may be used, notably, as a pigment for coating paper, characterised in that it comprises the following operations : dissolving of the saline material in at least part of the weak white liquor, obtained from washing of the calcium carbonate, giving a more concentrated green liquor, filtering of the green liquor at a temperature greater than about 80 degrees C, slaking of the lime at a temperature of about 100 degrees C, causticising the filtered green liquor at a temperature greater than 90 degrees C by addition of the milk of slaked lime obtained, separating the strong white liquor from the precipitate containing calcium carbonate, washing the precipitate with water at a temperature greater than about 80 degrees C to separate the solid calcium carbonate from the remaining white liquor and soluble iron salts at this temperature, recovering the calcium carbonate which has been subjected to treatment, notably hydrocycloning, to give it the desired grain size, less than about 15 mu m, recycling the weak white liquor, notably for dissolving of the saline material.</p> |
