石炭の国際的市況変化と新規環境技術の展開 Ｍｕｌｔｉ‐Ｇｒａｖｉｔｙ Ｓｅｐａｒａｔｏｒによる選炭微粒ズリからの可燃分回収

Abstract

The recovery of fine combustible matter from coal washery waste was investigated using a laboratory/pilot scale Mozley multi-gravity separator (MGS). The effects of parameters such as drum rotational speed, wash water rate and feed rate on the yield, the recovery of combustible matter, and the ash content of the concentrate were studied. It was found that the yield, recovery and ash content decreased with the decrease in wash water rate and with the increase in drum rotational speed and feed rate. It is estimated that these separation performances depend on the amount of particles retained inside the MGS drum. Because MGS was not suitable for the separation of very fine particles of clay minerals from coal washery waste, we suggested introducing a two-inch hydrocyclone after MGS treatment to effectively eliminate these clay minerals. A process for the recovery of fine combustible matter from coal washery waste using four-inch and two-inch hydrocyclones and MGS was then proposed. The yield, combustible matter recovery, calorific value and ash content of concentrate obtained from the process were 37 %, 57 %, 5940 kcal/kg and 18 %, respectively. These results show the technical advantages of the proposed process to reduce waste materials and increase the recovery of salable products.