Dry Cleaning of Law Grade Lump Coal Using Leap-bound Picker

초록

The coal is cleaned by screening and hand picking, or partly heavy medium seperation in most of the coal mines of Korea. Generally, coal ore of +65mm size is treated by hand picking and the less size range is treated by screening or heavy medium seperation. Howevwr, the low grade small lump coal ores of -65mm +25mm are left in large quantities owing to uneconomic cleaning cost. Therefore, in the present study "Leap-bound picker" was newly designed and applied as a method of dry type coal cleaning for simple to upgrade low-grade lump coal.The coal samples used in this study are dump coal and coal midding obtained from the Gyung-dong coal mine."Leap-bound picker" consists of feeding chute, ratating elastic drum and divider of cleaning products. It was also manufactured os that the revolution speed of rotating elastic drum, appropriate length and slop angle of feeding chute , and the drop length between chute tip and top of the elastic drum could be controlled well. The principle of coal cleaning by the "Leap-bound picker" is based on the differences of physical properties between coal and ganggue minerals such as shape, specific gravity, friction force and elasticity when the small lump coals are dropped from the chute to the upper surface of rotating elastic drum. From the results of coal cleaning experiment, clean coal of 3600Kcal/kg with the recovery of 91% and in addition, coal midding of 3800 kcal/kg was cleaned to 4600kcal/kg with the recovery of 94% using the leap-bound picker.