Effect of Coal Gasification Fine Slag on the Physicochemical Properties of Soil

Coal gasification fine slag (CGFS), which is the by-product of entrained-flow coal gasification, has superior properties, such as a large surface area, a broad pore size distribution, and a high content of carbon. This material has the potential to amend poor soils. This study was carried out to investigate the use of CGFS as a soil amendment for alkaline sandy lands. Special focus was given to the mechanisms by which CGFS changes the physicochemical properties of soil. Characterization tests and chemical composition results further attested that the large amounts of residual carbon, fluffy structure, high surface area, and wide pore diameter of CGFS are key factors that enhance the soil physicochemical properties. When 20% CGFS was applied, the bulk density of the soil decreased from 1.47 to 1.05g/cm(3), the carbon content increased significantly from 4.86 to 55.38g/kg, the pH decreased from 8.49 to 8.23, the cation exchange capacity (CEC) increased from 2.17 to 4.68cmol/kg, and the water holding capacity (WHC) increased from 29 to 44%. Potted plant experiments in a greenhouse showed that 20%wt. incorporation of CGFS significantly increased the germination rates of maize and wheat from 0 to 100%. Pearson correlation analysis results indicated that the changes in the soil physicochemical properties were significantly correlated with each other (p<0.05 or 0.01) and that the WHC was significantly correlated with the germination rates of the crops. This work demonstrated that judicious application of CGFS as a natural soil amendment could not only enhance the soil physicochemical properties but also provide a new approach for the safe and environmentally friendly utilization of CGFS.