Hydrocarbon-oil encapsulated air bubble flotation of fine coal. Technical progress report for the fifth quarter, October 1, 1991--December 30, 1991

摘要

A main portion of this reporting period has been consumed in the following tasks: (i) Contact angle measurement using gasified collector encapsulated bubble; (ii) wettability measurement using film flotation method; (iii) induction time measurement; (iv) conducting atomized collector flotation tests in a stirred tank cell; (v) developing the experimental design and conducting a column flotation test. The coal samples used in this period of work are five ranks of coal samples from Mammoth, Lower Kittanning, Upper Freeport, Pittsburgh No. 8 and Wyodak seam coals. To better understand the fundamental steps involved in the modes of collector addition techniques in the froth flotation, contact angle, wettability and induction time were measurement. It was found increasing in the contact angles and decreasing in the induction time for a hydrocarbon-oil encapsulated air bubble compared to those for an oil-free bubble for all the coal samples measured. These observations may account for the improved flotation kinetics and, hence, the recovery with the hydrocarbon-oil encapsulated bubbles. Two level fractional factorial experimental design were developed for conducting the column flotation tests to obtain the optimal operating conditions. In the first series of the tests, seven operating parameters were considered with 16 runs. Based on those results, subsequently, the second experimental design was developed for six operating parameters with 16 runs. The third experiment design was formulated with three most significant operating parameters with 8 runs. A high combustible recovery was obtained for -200 mesh Upper Freeport coal sample. However, the results indicated that for further reduction of the ash content of the froth product, the height of column flotation cell needed to be increased.