Rotork CVA electric control valve actuators have been specified for critical flow control duties on heavy duty mineral processing machinery manufactured by Mineral Engineering Processes Ltd. (MEP).
The MEP TBS Hydrosizer is used in the mining and mineral process industries throughout the world to separate materials, remove contaminants and beneficiate mineral particles that are generally less than 5mm in size.
The TBS Hydrosizer process utilises an upward current of water to create a hindered settling classifier in which material within a narrow size band can be held in a state of ‘teeter’. Smaller or lighter particles entering the classifier are displaced to the overflow, where they can be collected, whilst larger or heavier particles migrate to the bottom and are discharged through spigot valves.
A well-defined separation is achieved by maintaining a constant flow of upward current water, even though the level and nature of the mineral content in the water can cause the density to fluctuate. The constant flow of material is achieved by means of a 4-20mA signal from a hydrostatic density probe within the Hydrosizer Tank, which is used to control the CVA actuator operation. The CVA adjusts the position of a valve, allowing material to discharge at a rate that is determined by the hydrostatic head.
With resolution, repeatability and hysteresis performance quoted at less than 0.1% of full scale, the swift response and positional accuracy delivered by the CVA actuator enhances the efficiency of the process.