Simulation of mineral processing systems
By simulation of the whole or part of processes it is possible to make qualified estimates of the influence of different alterations in a concentration process. Often it is different what-if scenarios that come into question, and where it is costly to do time consuming tests on pilot or full scale. One simply wants to know the approx. influence a certain change will have. It may also be to do a cost-benefit analysis, where the proposed changes are ordered after their assumed influence and the cost for doing them.

Grinding section with rod and pebble mills in closed circuit with a hydrocyclone.
Introduction
Simulation of mineral processing systems is complicated since it is very much dependent on good and representative descriptions of the feed material and the machines used.
- Drawing of a principally correct, but also simplified flowsheet.
- Defining the feed material's particle size distribution, its mineral composition and grades, the amount of mixed particles, and how composition and grades vary by particle size.
- Selection of simulation models for the flowsheet's machines. Here, it is often wise to start with simple models, and then continue with more advanced models for the specific machine or sub-process that is especially interesting.
- Simulation of the full flowsheet, and adjusting the model parameters to get a reasonable fit to observed data.
- Validation of the simulation with another dataset or changed running conditions.
Objectives
Simulation of mineral processing systems is since nearly ten years an activity that is done in close cooperation with LKAB. The objective has been to get an understanding of the limitations and the benefits of simulations with data from real processes. Furthermore, that the simulation technology shall be introduced as a natural step in LKAB's process development. Additionally, the simulation will provide a basis for the teaching at LTU.
Approach
During the years several simulation studies have been done. They have had different aim and depth, and have in some cases been openly presented.
- Simulation of a capacity increase at Malmberget that provided a part of the basis for design of a new grinding circuit.
- The groundwork for tests with classification in the Malmberget concentrator.
- Bottle-neck analysis of the cobbing plant at Malmberget.
- Cost-benefit analysis for a future expansion of the Malmberget concentrator.
Results
Some of the results are very specific for the studied circuit, but a few general observations are:
- The simulations have to a part replaced pilot runs and shortened the time for implementation of changes in the processes.
- It has been possible to do what-if analyses of different circuit proposals and to sort out the probably best/simplest to implement.
- Bottle-neck analyses for varying feed rates and composition of the feed material is such a complex undertaking that it is not possible to do without simulation.
- In the cost-benefit analysis, simulation is a powerful tool to classify different possible modifications according to their influence and cost.
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