To keep abreast of the global drive towards system integration as a means of enabling lean production and process optimisation, State-owned minerals technology organisation Mintek is focusing on shifting the South African mining sector to greater degrees of operation and control of local mineral processing and metallurgical plant.

Mintek measurement and control process engineer Niel Knoblauch notes that the traditional, siloed approaches to the operation and control of processes or value chains consisting of many subsections, or subprocesses, are quickly making way for integrated, interconnected operation and control practices. This allows for goal and objective alignment along a value chain, which translates into an improvement of overall operational efficiency.

“When looking at the value streams of . . . gold or platinum mines – from mine to crushing to concentrator to refinery – the old silo approach is still very much at play,” he highlights.

Knoblauch adds that, even at concentrator plant level, one typically finds that there is no automatic communication between the different sections or even smaller process components within these sections. He says isolated, single-loop controllers still do the work of controlling individual process components, unaware of the way in which the wider concentrator needs to operate to improve overall benefit under any given conditions.

According to Knoblauch, the answer to this fragmented approach is to take a step back and control the whole process, which, he states, requires solutions capable of successfully controlling the process in such a way that individual process components are not compromised.

Mintek has developed an advanced process control (APC) toolbox software toolbox, which allows for multivariable control and the improvement of large integrated processes. Knoblauch explains that the APC software uses model-based techniques for control and optimisation, which has proven to be best suited to the local mining sector’s complex operator interfaced processes.

“This toolbox entails not only a model predictive controller but also a real-time optimisation functionality that ensures the tracking of high-level objectives, [guaranteeing] optimal control,” he notes. “The toolbox can generate models for controllers automatically, allowing for unsupervised, long-term modelling while the process is being controlled.

“This enables Mintek engineers to add value at a higher level when installing and supporting control installations across the globe,” Knoblauch states, noting that this locally developed technology competes with, and “arguably outperforms”, other APC packages.

Mintek’s APC toolbox has been installed at many local platinum-group metals (PGMs) concentrator plants, where process components in milling and flotation circuits are controlled together and improved to meet sectional objectives as a whole.

“In an industry that is rather risk averse and, therefore, slow to adopt innovation, a big vision, such as the integration of PGMs, gold or other value streams, needs to be pursued patiently to add as much value as possible with every step,” Knoblauch comments.

He adds that the plants where these overarching control methods are being implemented are reaping the benefits through not only controlling key variables, such as the rate of feed to flotation tightly to setpoints, but also “remarkable recovery improvements”.

The control system responds holistically to process disturbances, resulting in clients not having to intervene even during large process disruptions, Knoblauch asserts, adding that system use is reaching more than 98% use over months of operation at local PGM plants.

Meanwhile, Knoblauch says the next step for the sector is to move beyond the unification of process components in a process section to controlling several process sections together as one plant.