The Application of Microcel^TMColumn Flotation to Fine Coal Cleaning

Abstract

Column flotation is widely recognized as providing an improved separation efficiency, primarily as a result of incorporating a froth washing mechansim to remove the entrained mineral matter. However, the use of columns has several shortcomings, including low throughput and plugging problems associated with bubble generators. To overcome some of these problems, a new column known as Microcel TM has been developed. It is based on using microbubbles in the range of 0.1–0.4 mm by employing static, in‐line mixers for bubble generation. The use of smaller air bubbles improves the probability of bubble‐particle collision and, hence, the flotation rate, allowing shorter columns to be used and reducing both air and energy consumption. In addition, the bubble generators are non-plugging, require no fresh water and are externally mounted for easy maintenance. In this communication, the underlying principles of this technology are presented with the test results obtained using laboratory, pilot‐scale, and full‐size columns on a variety of coal samples. The results are compared with those obtained using a bank of mechanically agitated flolation cells.