Industrial Products for Advanced Control of Mineral Processing Plants - Advanced Control and Supervision of Mineral Processing Plants - page 304

Metso has developed control strategies for flotation plants that combine Vi-
sioFroth with feed-forward and froth speed control techniques using a cascade con-
trol system in which the controller sets the pulp and air reference levels. An assess-
ment of the benefits obtained from these strategies at the Grasberg mine in Freeport,
Indonesia, which included the installation of 172 cameras, reported a recovery in-
crease of 2.6 to 3.9%, a reduction in frother dosage of 25% and a project payback
time of 51 days.

MINTEK

Mintek offers a family of products for mineral processing control known as StarCS,
an open system with OPC communication and a series of functionalities integrated
in specific applications such as MillStar and FloatStar [58].
Among these functionalities are:

• StarCS Autotuner, for self-tuning of PID controllers;

• Advanced Control Package, which includes ratio controllers, advanced PID, a

soft limiter, a dead time compensator, feed-forward control, advanced filters and
non-linear compensators;

• StarSC MMPC, a model-based multivariable predictive controller specially adapted

for processes with different numbers of controlled and manipulated variables;

• StarSC Deadbeat Controller, for processes with very long dead times;

• fuzzy logic environment for fuzzy expert control;

• dynamic simulator for continuous and discrete time systems, with non-linear

blocks and white noise generators.

Figure 7.8 shows the structure of FloatStar, a flotation control system developed
by Mintek for stabilizing pulp or froth levels and optimizing cell bank residence
times, grades and recoveries. The product includes modules for process monitoring,
level stabilization, optimization (Flow Optimiser), pH control and flotation dynam-
ics simulation. Flow Optimiser is a multivariable predictive controller whose manip-
ulated variables are the cell level and air flow references. Craig and Henning [59]
and Houseman et al. [60] detail the benefits of the FloatStar system.

SGS

SGS offers advanced process control solutions through the implementation of fuzzy
ES that utilize MET (MinnovEX Expert Technology), FLEET™ 11 (Flotation Eval-
uation Tool) and JKFrothCam [61]. MET is implemented on Gensym's G2 plat-
form, which combines real-time reasoning technologies including rules, workflows,
procedures, object modeling, simulation, and graphics in a single development and
deployment environment. Two of the specific tools employed: NeurOn-Line Studio
and NeurOn-Line, are also Gensym products [62]. NeurOn-Line Studio is employed
for viewing and cleaning training data and determining sensitivities and time lags
for various model inputs. NeurOn-Line, on the other hand, is used to deploy the

11

FLEET is a registered trademark of SGS Group, http://www.sgs.com/