Coal Preparation » General
There is no real-time measurement for coal flotation performance, making it difficult to control the flotation process. Previous laboratory test work in project C23035 has developed a froth diagnostic tool and a frother concentration measuring tool. This project further developed and assessed these two tools in a coal preparation plant.
The first was concerned with real-time monitoring of flotation performance. A sensor based on drag force measurement was developed to measure the drag force exerted by the overflowing froth. The sensor was installed above a large industrial column flotation cell, and its diagnostic ability was tested at a wide range of the flotation operation conditions. The performance of this sensor was compared to two other systems; one based on the air-recovery concept and the other based on gas holdup measurement. The correlation between flotation performance and the output of each of these systems was analysed. The sensor based on the drag force measurement outperformed the other two for monitoring the clean coal yield. When monitoring the combustible recovery, the sensor based on drag force measurement performed similarly to the air recovery based system but outperformed the gas holdup sensor being used by the site. The sensor based on drag force measurement is a lowcost, stand alone device that can be used to monitor flotation performance online and provide instant feedback for process optimisation and control.
The second involved development and assessment of a simple and fast tool for measuring MIBC concentration in a coal flotation plant. The MIBC concentration measurement method was upgraded and demonstrated its potential by measuring MIBC concentrations throughout the participating coal preparation plant. It was found that a considerable amount of residual MIBC was present in the process water, with the MIBC concentrations of the tailing thickener overflow and return water being 4.2 and 2.8 ppm, respectively. The MIBC concentration measurement made it possible to maximise and maintain the yield and in the meantime avoid the overfrothing ('froth out') problem. The relability of this tool was confirmed by using a colorimetric method developed by McGill University.
Overall, this project provided an effective real time froth monitoring tool and a simple and fast tool for monitoring frother concentration in flotation cells and in the water circuits. The ability to measure frother concentration will help coal flotation plants identify the amount and location of frother addition to optimise the process and improve its smoothness.