Testing of pneumatic flotation in iron ore processing

It is well recognized that machine type and machine characteristics play vi tal roles in the successful application of froth flotation in mineral proce ssing. Since the early 1900s, a multitude of machine designs have been and are still being introduced in an attempt to improve flotation efficiency. M achines based on mechanical agitation have been the most dominant in indust rial practice. However, in recent years there has been a growing interest i n pneumatic flotation units because of their claimed simplicity, low cost, high throughput and good metallurgical performance. This work was carried o ut to assess the effectiveness of pneumatic flotation on a magnetite ore. T he method was applied using a prototype pneumatic flotation device that uti lized a suitable nozzle for bubble generation. Important variables of the p rocess were examined and optimized, including the nozzle size, air flow rat e and froth thickness. Further tests were conducted to determine the influe nce of frother dosage and to explore the improvements that could be made on concentrate grade and recovery by cleaning and scavenging. Under the best test conditions, an iron concentrate was obtained with a grade of 66.4% Fe and a recovery of 97.7%. Particularly, the recovery was superior in compari son to that of mechanical flotation. This was attributed to the ability of pneumatic flotation to create and maintain a relatively thick froth layer.