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%.

摘要 某铁矿企业扫选柱浮选工段（scavenger column flotation stage）的矿浆/泡沫界面液位（slurry/froth interface level）控制效率低下，严重制约了其工艺运行效能，致使尾矿中铁含量攀升至20%以上，进而未能达成企业既定的铁回收率与球团矿原料（pellet feed）生产目标。研究团队基于物料衡算（mass balance）与工艺数据开展水力计算（hydraulic calculations），结果显示现场配备的公称直径6.0英寸（15.24cm）大气腿管（barometric leg tubes）及控制系统阀门均符合设计要求。随后针对浮选柱推导了确定最大大气腿高度的计算公式，进一步计算表明需将大气腿高度从4.6米下调至最高3.4米。调整大气腿参数后，矿浆/泡沫界面液位的控制变异性显著降低，尾矿中铁含量从24.9%降至18.9%，该浮选工段的铁回收率（iron recovery）也从97.9%提升至98.7%。