| 摘要 |
<p>Alkali waste liquors, e.g. pulp waste liquors, are desilicified in 2 steps. In 1st step, the waste liquor is treated with dil. CO2 until reaching a pre-determined pH, pref. 9.8-10.2. At least 75% of the silicic acid in waste liquor is pptd. and separated from the waste liquor. In 2nd step, the partly desilicified waste liquor from 1st step is treated with milk of lime so as to achieve the desired degree of desilicification by the pptn. and separation of Ca silicate. Max. desilicification is achieved with mon. organic and alkali losses. The heating value of the desilicified conc. waste liquor is at least equal to that of untreated waste liquor. The CaO-slurry can be burnt in a rotary furnace or turbulent bed reactor, to reduce the fresh lime requirement by over 90%. The process can be operated continuously and monitored by 1 operator.</p> |
