Experimental Research on Contamination Dissolution-Releasing Characteristic of Coal Gangue in Soaking Operation

Abstract

In order to investigate the dissolution-releasing characteristics of the pollutants in coal gangue, this article carries out soaking experiment of coal gangue in different wind erosion degree of XINQIU strip mine under different conditions. The results show that the main dissolution releasing pollutants of the coal gangue are total hardness (CaCO3), sulfate (SO42-), natrium (Na+), total dissolved solid (TDS), fluoride (F-), CODMn, and total iron (Fe). Chloride (Cl-), manganese (Mn) and zinc (Zn) occur in small quantities and heavy metals and arsenic (As) in trace concentration. The pH scale is nearly neutral. The higher the wind erosion degree is, the larger the quantity of the inorganic pollutants released by the gangue is. The quantity of the inorganic pollutants released by mixed coal gangue in high wind erosion degree inside the mountaintop is larger. Fluoride (F-), oxygen consumed (OC), and total Fe are released by fresh mixed coal gangue in higher concentration. Soaking time, solid-to-liquid ratio, acidity, granularity and stirring have a significant impact on the dissolution-releasing of the pollutants. The longer the soaking time, the smaller the solid-to-liquid ratio, the stronger the acidity, the smaller the granularity and the faster the stirring intensity is, the quicker the rate of the pollutants dissolution-releasing is and the larger the total quantity of the pollutants is. Which can accelerate the dissolution-releasing of the pollutants which is controlled by diffusion.