Rutto Hillary, Siagi Zachariah, Mbarawa M
Department of Mechanical Engineering, Pretoria Campus, Tshwane University of Technology, Private Bag X680, 0001 Pretoria, South Africa.
J Hazard Mater. 2009 Sep 15;168(2-3):1532-6. doi: 10.1016/j.jhazmat.2009.03.097. Epub 2009 Mar 31.
The rate at which limestone dissolves is very important in wet flue gas desulphurisation process (FGD). High dissolution rates provide better alkalinity that is important for sulphur dioxide (SO(2)) absorption. The dissolution characteristics have been studied by using a pH-Stat method at 60 degrees C, at pH value of 5, stirrer speed of 100 rpm and particle size of 44 microm. This paper examines the use of ammonium compound as the possible additives that will enhance the dissolution rate of limestone. The dissolution rates were measured according to the shrinking core model with surface control, i.e. (1-(1-X)(1/3))=k(r)t. It was found that the dissolution rate increases in the presence of ammonium compounds. Upon addition of 0.5 g of ammonium nitrate, the dissolution rate constants increased by 170%. As the pH is increased the dissolution rate decreases. The dissolution reaction follows a shrinking core model with the chemical reaction control as the rate-controlling step.
在湿法烟气脱硫工艺（FGD）中，石灰石的溶解速率非常重要。高溶解速率能提供更好的碱度，这对二氧化硫（SO₂）吸收至关重要。在60℃、pH值为5、搅拌速度为100转/分钟且粒径为44微米的条件下，采用pH计法研究了溶解特性。本文研究了使用铵化合物作为可能的添加剂来提高石灰石的溶解速率。根据具有表面控制的缩核模型测量溶解速率，即(1-(1-X)(1/3))=k(r)t。结果发现，在铵化合物存在下溶解速率会增加。加入0.5克硝酸铵后，溶解速率常数增加了170%。随着pH值升高，溶解速率降低。溶解反应遵循缩核模型，化学反应控制为速率控制步骤。
