Dimensional design of the barometric leg of a flotation column: a key to operational stability

Abstract The inefficiency in controlling the slurry/froth interface level of a scavenger column flotation stage was severely impairing the process performance of an iron mining company, increasing the iron content in the tailings to levels above 20% and, consequently, not meeting the company's iron recovery and pellet feed production targets. Based on mass balance and process data, hydraulic calculations were performed and showed that the installed 6.0" (15.24cm) diameter barometric leg tubes and the control system valve were adequate. An equation to determine the maximum barometric leg height was developed for the flotation column and other calculations showed the necessity to reduce this height from 4.6m to a maximum of 3.4m. The barometric leg adequacy considerably decreased the variability in controlling the slurry/froth interface level, reduced the iron content in the tailings from 24.9% to 18.9% and increased the iron recovery in the flotation stage from 97.9% to 98.7%.