Development of an index for the floatability of Indian coal fines

Batch flotation experiments were carried out on four different Indian bituminous coal samples in the size -74 μm at various levels of variables. It has been noticed from the results that at any flotation time, the yield of concentrate Y (t) follows a linear relationship of the following form with the amount of water W(t) reporting to the concentrate. Y(t)=F_w(t)+E_w(t)·W(t)The intercept value F_y(t) which is termed as the true flotation component of yield when hypothetically no water reports to the concentrate has been found to increase with flotation time as given by the equation F_w(t)=F_w(∞)·[1−exp(−k_w·t)]Based on these observations, an index called “floatability index (FI)” has been proposed to quantify the response of coals towards froth flotation. This index is defined as The floatability index varies from 0 to 100. Consequently, the higher the value of the index for any coal, the better is its response towards flotation. The floatability index has been found to be specific for a given coal and is independent of process variables like reagent dosages, solid content of feed slurry and flotation time.