| 摘要 |
<p>The process relates to continuous treatment of a fiber pulp with a chemical solution by forming on a filter surface a bed of a fiber material suspension and by feeding it through one or several chemical treatment steps in which the chemical solution is displaced through the bed. According to the method, there are used in each treatment step two different treatment liquids which are successively displaced through the bed. The first treatment solution is a chemical solution which contains a greater amount of active chemicals than is consumed in the reactions occurring in the pulp bed, preferably approx. twice the amount. The second treatment liquid is a solution which does not contain active chemicals in an amount significant in terms of the reaction. Its purpose is not only to displace that portion of the first treatment liquid from which the active chemicals have been spent but also that portion which still contains active chemicals upon leaving as a filtrate. Of the filtrate of the treatment step, that fraction is recovered which has the highest concentration of active chemicals and contains most of the active chemicals leaving the bed and is in its amount only so large that, when reinforced with a fresh chemical solution, it can be used in its entirety as the first treatment solution. The total liquid volume of the treatment liquids is substantially greater than the liquid volume present in the bed upon its leaving the treatment step - preferably 2- to 3-fold.</p> |
