BACKGROUND

Issues related to treating ultra fines experienced at other mines in Mpumalanga highlighted an opportunity to improve the design of the Belfast coal beneficiation plant. The average standing time in most of the Mpumalanga operations, as a result of ultra-fines circuit overloads, can be as high as 48 hours per month. These challenges usually occur when treating RoM that is weathered or contains an excessive percentage of ultra fines. The thickener is then overloaded with ultra-fine material, which requires the beneficiation plant to be stopped until the ultra-fines circuit has been cleared of material build-up.

SOLUTION

To solve this problem, the thickener smart control solution was implemented. The solution influences the operation of the thickener by measuring certain parameters such as rake torque, overflow clarity and thickener underflow density. These parameters are then used to pre-empt overloading of the ultra-fines circuit. As soon as the thickener smart control detects the build-up of fines, it automatically reduces plant feed tonnage. This decreases the ultra-fines feed into the thickener until the circuit is cleared.

VALUE REALISED

The implementation of this solution enabled the collection of data which was to predict and prevent the occurrence of system overloads. This enabled better management of the thickener and lessened occurrences of black water. Ultimately, the system has improved plant utilisation by reducing downtime hours from the anticipated 48 hours to an average of 10 hours per month.