The Millstar Advanced Control System has a comprehensive suite of control strategies that can be applied to provide an innovative control solution for almost any milling circuit configuration.
- Maximises throughput.
- More consistent feed to downstream processes, thereby increasing recovery.
- Optimal usage of mills.
- Individual customisation
- Improved control of mill feed rate.
- Better management of fine and coarse material, thereby preventing mill overloads.
- Prevents violation of constraints, making daily operation easier.
- Robust control solutions for effectively handling instrumentation failures.
- MillStar boasts a typical payback period of just a few months.
MILL FEED CONTROL
There are a host of difficulties related to the controlling of the feed to the mill, such as long time delays between feeders and weightometers, and variable ore. MillStar’s feed controllers have been specifically designed to compensate for long time delays and handling changes in the process dynamics due to variable ore and/or changes in the feeders responses.
The MillStar Feed Controllers module has several sub-modules:
Segregated Ore Feed Controller
These controllers complement the normal control strategies by addressing problems and requirements with multiple feeders and potential ore segregation.
MILL THROUGHPUT OPTIMISATION
Obtaining optimum power usage from a mill is highly process-dependent. MillStar’s Power Optimiser dynamically determines the optimum operating point for the mill and controls the mill to maintain the power. A number of safety checks are also present to substantially reduce the number of mill overloads. By operating at the optimum power and minimising the overloads, the throughput is also maximised.
The modularised approach allows clients to select a combination of modules best suited to their plant problems and objectives and build on it with time
Recirculating Load Optimiser
By optimising the recirculating load in a milling circuit it is possible to maximise the possible throughput of the milling circuit.
MILL DISCHARGE PRODUCT CONTROL
Typically, the mill discharge section is controlled using many separate single-input single-output control loops; however, the system is multivariable. MillStar’s Model Predictive Controller (MPC) provides a superior multi-input, multi-output control solution by minimising all variable errors from setpoint simultaneously while taking both control variable and controlled variable constraints into account.
Millstar Sump/Product Stabilisation
This module takes into account multivariable interactions between input and output mill discharge variables and controls the sump level and cyclone overflow product size and/or density.
Model Predictive Controller
The MillStar Model Predictive Controller (MPC) allows for the control of milling circuits, which are in essence multi-variable systems, using novel technologies to handle the integrating nature of these circuits as well as the constraints associated with them.
Cyclone Switching Control
Clusters of cyclones are often used for mill discharge classification. By controlling the number of open cyclones, the pressure within the cluster can be controlled. Stabilising the pressure improves the stability of the cyclone overflow particle size and density, which improves the consistency of the feed to the flotation.
Mill Discharge Density Estimator
The Mill Discharge Density Estimator provides an estimate of the mill discharge density and flow rate. It is able to use two distinct algorithms to achieve this and is based on first-principle models. It relies on signals from plant instruments, which can include thermocouple temperature readings.
Particle Size Estimator
The Particle Size Estimator (PSE) is a soft-sensor capable of accurately predicting the particle size of the hydrocyclone overflow product on a closed loop milling circuit. It is based on an empirical model, identified from extensive plant test work. The PSE can be used to:
- Estimate the cyclone overflow particle size on plants without a physical measurement.
- Act as an intelligent filter, a backup sensor, or be used in a fault detector on plants that do have a physical measurement of the cyclone overflow size.
- Intelligently interpolate readings when a physical measurement instrument is multiplexed between different streams.
The accurate measurement of the power consumption of a mill is very important in industry, as this measurement is used to control feed rates, mill loading and other control parameters. A reliable measurement is, however, difficult to obtain, as the power drawn fluctuates over the period of rotation and is subject to process noise. The MillStar Power Filter is capable of removing the noise to obtain a true reflection of the base power consumption of the mill for use in control systems.
MillStar completes and complements its control suite with a range of fault detection and signal conditioning tools that can be used in conjunction with expert rules to timeously detect instrumentation failure and take necessary action to ensure smooth operation.
The Maintenance Managers are helper modules that assist in the normal operation of the plant.
Steel Ball Manager
The StarCS Steel Ball Manager is a tool for estimating the steel ball load in the mill. This helps plant personnel to determine when to add steel balls.