Pulp And Black Liquor Alkali Recovery Of New Technology And Its Analysis

In this paper,two methods of treating black liquor for small or middle paper manufature factory were studied.One of the methods is physical chemisty alkali recovery,the other is electrochemistry alkali recovery.The method of physical chemisty alkali recovery is using recovery alkali not only to treat black liquor of straw pulp but also to make pulp circularly. The fitting condition of acid and alkali treatment was found by experiment in this study:when treated with acid,pH is about 3.0,the temperature is 60 ℃ and keeping to be heated by water for 15 minutes at this temperature,the speed of adding acid is middle,thus it would not bring much foam when adding acid;when treated with alkali,the temperature is 70℃,the dosage of CaO is 20.34g/L. The better times of circulation was also found in this study:it is 3 times. The feasibility and effect of the method was validated.The method of electrochemistry alkali recovery is to electrolyze black liquor of straw pulp by direct current electrical source and recovery residual alkali. The best current , voltage and time of electrolyse was found by experiment in this study :I=1.0A,U=8.0V,T=12h.Then treating black liquor by direct current on this condition for 12 hours,the experiment result showed that the black liquor pollution could be reducedeffectively, high alkali recovery rate was gained.Inadditional, using lignin separated out from black liquor to make lignin-qitaternary amic salt flocculant was studied in this paper.The better technical condition of synthesizing it was gained by conditional experiment.Utilizing self-made flocculant to treat living wastewater ,the effect of treatment is satisfactory.