Investigation On The Hazardous Elements Of Coal Gangue And Fired Brick

In this paper, the coal gangue which came from the No.1 Mine of China Pingmei Shenma Group was taken as the research object. The mineral composition of the coal gangue was investigated by XRD, FT-IR, SEM (EDS), DSC-TG, etc. The chemical composition, especially the content of the harmful elements (F, S, Cl, Be, V, Cr, Co, Ni, Cu, Zn, Sr, Mo, Cd, Sb, Ba, Tl, Pb, Th, U, Hg, As, Se) of the coal gangue was studied by XRF, ICP-MS, AFS, etc. In addition, the fractions of these harmful elements were studied using the sequential chemical extraction method. The results showed that the main minerals of the coal gangue were Kaolinite, Quartz and Muscovite. The content of most harmful elements in the coal gangue was higher than the average background value in the Chinese soil. The harmful elements mainly existed in exchangeable, bound to carbonate, bound to oxides, oxidized matter and silicate. Besides, the distribution of mostly harmful elements was more in the silicate than in other fractions. However, Zn, Tl were mainly associated with carbonate.The fired brick was prepared at 1100℃by using coal gangue as the raw material. The water absorption and compressive strength of the brick was 18.2% and 22.51MPa respectively, which met the performance standard of the normal MU20 in National Standard GB5101-2003. Comparing with the coal gangue, the content of most harmful elements in the fired brick had few changes, and some elements such as Cl, Hg and Se released to the environment as gas. The leaching behaviors of harmful elements in the coal gangue and the fired brick were studied by static leaching experiments. The results indicated that the leaching activities of F, S, V, Zn, Mo and As were higher in the fired brick than in the coal gangue.The condensation in the heat exchanger of the tunnel kiln brick wall in the No.1 Mine gangue brick factory of China Pingmei Shenma Group was also studied. The results showed that the main component of the condensation was hydrated ferrous sulfate, and a small amount of organic matters and some harmful elements were also included. The content of F, S, As, Se, Zn, Mo and Pb in the condensation was much higher than that in the coal gangue material. Moreover, the content of sulfur in the condensation was 57 times as many as that in the coal gangue material.