We are passionate about process control, and strongly believe in the benefits the right technology can deliver to minerals processing plants.
Greenfern Dynamics has extensive experience implementing value-adding process control solutions in metals and minerals processing facilities.
- Ores of variable composition and physical properties which are often not measured in a dynamically useful manner;
- Operating conditions which can include two or three-phase flows and scaling, corrosive or erosive environments;
- They typically have large installed capacity, with long time delays and complex interactions;
- Specific process units may operate at high temperatures and pressures. The plants may use highly acidic, alkaline or otherwise toxic solvents to extract product;
- Strict environmental conditions govern site emissions and residue or gangue disposal;
- Process chemistry is often difficult to characterise. There may be a lack of accurate or reliable online instrumentation to infer process performance in real time;
- There is often a high degree of equipment and process line redundancy which results in inconsistent process characteristics making automation more difficult.
These plants present challenging process control problems. Operating staff are required to manage competing objectives and frequent disturbances, while attempting to maximise production and minimise costs – and of course operate safely.
Greenfern Dynamics Control Solutions
Our control solutions have provided measurable and compelling paybacks to minerals processing clients. We have helped clients realise value through increased production, reduced energy and reduced reagent costs. We have also provided other benefits including improving process operability and safety, product quality and site environmental compliance.
Our solutions have typically demonstrated improvements when audited of 2 to 5% in relevant KPIs.
Process Control Benefits in 3 steps:
- Assess Performance
- Reduce Variation
- Optimise average to constraint limit = shift in average.
Choice of Control Technique
We have implemented solutions ranging from traditional Advanced Regulatory Control (ARC) schemes to Advanced Process Control (APC) techniques such as Model Predictive Control (MPC). Our choice of solution depends on the characteristics of the process and the needs of the client.
ARCs can be applied when there is a small number of process constraints (typically three or less), the process dynamics are low order (typically two or less) and where the number of manipulated variables is small (usually only one or two).
APCs are applied to more complex minerals control problems, ranging from regulation of process units with higher order or multivariable dynamics, through to optimisation of entire process areas. APCs also provide faster start-up and recovery from process disturbances, such as equipment trips or re-start from maintenance.
We have used APCs to maximise process throughput, and to assist operators to manage competing process objectives, often when the number of controlled variables is much greater than the number of process adjustments (the ability to manage “non-square” processes is one of the strengths of MPC technology).
We also have capability to provide real time optimisation of more difficult problems using industry proven and pragmatic technologies. These techniques are ideally suited to very wide scopes (e.g. the whole facility), nonlinear process characteristics which can result in unconstrained optima and/or mixed integer related problems. Often these applications do not have to include the entire scope of each individual underlying APC. Examples of our Dynamic Optimisation projects include seed inventory control, mud inventory control, and overall refinery volume and concentration.
Minerals Processing Expertise
- crushing and milling
- leaching and digestion
- solids removal including cyclone and dense phase separation, centrifugation and filtration
- crystallisation and precipitation
- froth flotation and carbon-in-leach processing
- sedimentation including thickening and residue washing
- drying and calcination
- lime slaking and causticisation
- organics removal processes
- evaporation and heat exchange
- circuit inventory and flow management
We also have expertise in alarm management, traditional regulatory control and project management of process control projects.