BUBBLE LOAD MEASUREMENTS IN FLOTATION – A CRITICAL REVIEW OF CURRENT PRACTICE

摘要

In the flotation process, the valuable material is recovered selectively in the pulp phase and isrncarried by the bubble flux into the froth phase and, along with material unselectively recovered byrnentrainment, reports to the concentrate. This is termed the ‘bubble load’ and can be assessed relativernto various operating parameters such as volume of air recovered, surface area of the flux, flow raternrelative to the concentrate etc. The measurement of ‘bubble load’ is being developed for variousrnpurposes, including the evaluation of froth recovery, characterising ore differences and changes tornmineral floatability, all of which are aimed at getting a better understanding of the role of the froth andrnpulp phases. This paper assesses the current published techniques used to measure the bubble loadrnin industrial cells from two perspectives: i) sampling efficiency and ii) sample representativeness.rnSampling efficiency refers to understanding the loss of information when sampling a certain volumernout of a complex population such as a stirred pulp. Changes in the physical and chemical conditionsrnof the sample may lead to measurement biases particularly in the sealed devices; the physicalrnmechanisms occurring during sampling are also evaluated. The sample representativeness refers tornhow well a sample can represent the turbulent three-phase system. In this case, the relationship ofrnthe bubble load measurements to operational conditions such as cell feed grade and the concentraternor tail samples are assessed. This paper compares the measurement techniques and the data thatrnhave been published to evaluate their value and limitations in flotation operations, and recommendsrna strategy to improve them.