洗煤对高碱煤碱金属迁移及灰熔融特性的影响

In the light of such difficulties encountered in burning a coal rank with a high alkali content as excessively more fouling and slagging, a typical coal rank was chosen to perform coal washing by using deionised water, 1 mol/L nitric acid and 1 mol/L ammonium acetate respectively and an ICP-OES (induction coupled plasma object emission spectrometer), XRF (X-ray fluorescence) and XRD (X-ray diffraction) meter etc. analyzer and instruments to conduct an analysis and testing of the alkali metal elements and mineral substance components of coal before and after coal washing by using various solvents. The research results show that the above-mentioned three kinds of solvents for coal washing have almost no removal effectiveness to Ca and Si in coal while the deionised water has an around 50% removal rate of Na, K, S and Fe in coal. The nitric acid and ammonia acetate can attain an about 90% removal rate of Ca and Na in coal. Albeit the fusion temperature of the coal ash after coal washing has no big change (a deformation temperature of the ash increases by 11 to 42°C). However, due to the removal of Na and S etc. alkali metals after the coal washing, the precipitation temperature of the initial liquid phase in the ash fusion process will increase from 700°C, if raw coal is used, to 900°C (nitric acid) and 1100°C (ammonium acetate) and the mass percentage of the initial liquid phase precipitated will also decrease from 17wt/% to 5.38wt% (deionised water)/5.09wt% (nitric acid). This plays a vitally important role in reducing the fouling degree caused by burning coal with a high alkali content.