DIRECT MEASUREMENT OF GAS RATE IN A FLOTATION MACHINE

Gas rate measurement in a flotation cell and especially in a column has generally been a problem for the industry. Some of the reasons for this are: improper calibration and maintenance of the flowmeter, inadequate knowledge of the air pressure related to the measurement, and the correction for standard conditions (STP). A novel method was developed to allow direct measurement of the gas rate in a flotation machine. Tests were conducted in a laboratory flotation cell and in a 10-cm diameter laboratory column, with a water-air system and with three-phase systems having silica or sulfides as the solids. A 2.5-cm inside probe was located vertically above the flotation machine with its tip at a known depth in the pulp zone. Material was pumped from the pulp through a peristaltic pump. The slurry and air pumping rates, and the percentage of solids were measured. A correlation was developed that yields the gas rate in the cell from the slurry and air volumetric rates with a standard error of estimate of 0.05 cm/s. The correlation depends on the flotation machine geometry, and the amount of solids present. The method has been applied successfully in 3 plants, at 6 flotation columns.