FLOTATION
If the froth is too thin, the process has not been given adequate reaction time and the froth does not contain enough product. If the froth is too thick, the chemicals have been given too much time to react and they are not processing as much product as they could. In either case the process is inefficient.
Maintaining the highest efficiency in the process means tightly controlling the froth thickness. Froth thickness is controlled by the fluid level, which is constantly changing density with the addition of chemicals, water and ore. In this case an accurate density-compensated level measurement eliminates waste in this application.
VEGA uses an electronic differential pressure system( EDP) to track density-compensated level and, by extension, froth thickness. Consisting of two VEGABAR 80 series pressure transmitters, EDP systems measure differential pressure using electronics instead of capillaries or impulse lines. The two independent transmitters measure the pressure at the mounting point and then provide the difference as an output.
One of the many advantages EDP has over its traditional counterpart is the ability to output more than just the differential pressure, VEGA says. Multiple output variables are available to users, who may select built-in applications including density, level, flow, interface, and density-compensated level. With two independent transmitters any of these variables can be set as the primary analogue output, or two with the optional second current output. Additionally, up to four variables can be accessed digitally. The VEGABAR Series 80 devices can be mounted from any vessel position as well as suspended from the top to make installation easy.
Density-compensated level presents a dependable option for a mining industry accustomed to using an unreliable float system to measure the froth thickness in flotation cells.“ The current mechanical solution is maintenance intensive and fraught with errors absent from VEGA’ s electronic system,” says VEGA.
Froth level control
ElectraulicT Actuators from REXA, an industry leader in electro-hydraulic actuation, have been chosen as the primary actuation technology to control flotation cell froth level at a mine located in the southwest US. At the large open pit copper mine, the concentrator can process up to 56,200 t / d of sulphide ore a day. The mine had previously relied on pneumatic actuators to control the pulp level in its flotation cells via modulating dart valves. These actuators lacked the precise modulation required due to the compressibility of air. The froth level needed to be controlled by actuators that provided precise modulation in opening and closing the dart valves.
Cheminova
A / S Thyborønvej 78 DK-7673 Harboøre · Denmark Tel. + 45 9690 9690 Fax. + 45 9690 9691 www. danafloat. com info @ danafloat. com
REXA ' s unique ElectraulicT Technology is a revolutionary approach to actuation that combines the simplicity of electric operation, the power of hydraulics, the reliability of solid state electronics, and the flexibility of user configured control. ElectraulicT Actuators and drives offer a self-contained, positive pressure, hermetically sealed system that requires minimal power consumption. There are no filters, large reservoirs or routine oil maintenance needed. Here they are being used in a southwest US copper concentrator
When initially installed in only three flotation cells on a rougher bank, the REXA Actuators resulted in an immediate improvement in valve control, which should improve the recovery of copper content, with a ~ 1-4 % Cu grade increase during the flotation separation process. The
Danafloat™ flotation reagents
Wide range sulfide flotation collectors and chemistry families Largest manufacturer organophosphorous compounds Unique manufacturing process results in very high quality collectors Danafloat™ products provide unique process performance and hydrodynamics Danafloat™ collectors improve kinetics, recoveries Flotation frothers for any mineral flotation process, hydrodynamic situation Established global network of regionally based sales channel partners Comprehensive technical and plant operations optimization support True global supplier, effective logistics and business support to all corners of the world
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NOVEMBER 2017 | International Mining 31