In complex interacting materials handling systems, the key to maximising total system performance is in understanding the causes and effects that the inherent variability of the system has on production. Sources of variability include feed types, supply functions, resource sharing, work practices, random failures, congestion points, queuing, surge capacity, customer demand, etc.
All systems can be divided into a series of sub-processes. Conventional management and design practices focus on the optimisation of these system components. However, the interaction between sub processes mean that improvements made to the individual components do not necessarily translate into total system performance improvement.
Some of the challenges facing companies wanting to implement a new materials handling / conveying solution include:-
- Concept planning
- Evaluation of alternative locations for facilities
- Selection of plant modernisation options
- Plant expansion planning
- Planning of new processes
- Fine tuning of complex interacting systems
Simulation is a powerful tool that can be used for the design and analysis of systems that are far too complex for analysis using traditional methods. It can be used for all phases of a system’s life, including planning, design, analysis, operation and expansion. The method can be used to model almost any system and is used extensively in mining, manufacturing, infrastructure, retail and banking.
Specific applications of simulation modelling of materials handling systems include:-
- Confirming the expected throughput
- Investigating the value of capacity improvements associated with increased rates, bin sizes or better availability
- Considering the relative merits of alternative flow sheets
- General optioneering and what-if quantifying
By evaluating the complex trade-offs associated with real situations, testing the effectiveness of proposed modifications before they are implemented and examining alternatives without shutdowns, loss of production or capital expenditure, TSG Consulting can identify ways of reducing your costs and improving production quality.
TSG is a consulting firm specialising in simulation modelling and scheduling, with over ten years’ experience in mining, transportation and processing.
We use computers to build models of complex operations for clients who know that effective decisions are dependent upon clear and complete data supported by rigorous analysis.
TSG employs a phased approach to simulation studies to provide greater certainty for its clients and to ensure that the simulation is in fact the correct approach to deliver the required outcomes. Coding a simulation model is only part of any simulation study. Models must be verified and validated before rigorous scientific methods are applied to generate true insight into the system being studied.
We recommend a team-based approach for all simulation studies with the aim of involving all levels, from plant operators to vice presidents, in the simulation process. Collating these different perspectives results in a model that is more likely to capture all the relevant system interactions.
An example of a recent materials handling simulation study completed for an Australian client is described below.
The study objective was to determine the sustainable capacity given a proposed increase in production for the total minerals material handling system. This involved evaluating various options aimed at minimising the capital outlay for the expansion of the materials handling system.
The simulation model developed included the mining operation through to the processing stockpile. The operation was broken into four modules that represented the interfaces between the system components.
These were defined as hauling, primary crushing, secondary crushing and reclaiming / conveying / processing stockpile. Detailed data analysis was undertaken to ensure all data and logic rules used accurately modelled site operations. Planned and unplanned outages for all the fixed and mobile plants were included.
To achieve the proposed increase in tonnes, a process of bottleneck identification and shifting was undertaken. To ensure the mine could meet the demands of the increased tonnes the mining operation was tested using different truck capacities and variable sized fleets.
Once the mining operation had sufficient capacity to meet the target tonnes the bottleneck shifted to the conveying system. Sensitivity analysis was undertaken to determine the impact the operating hours, operating rate, scheduled maintenance and random breakdowns had on the system. Both a conservative and optimistic maintenance plan were tested at two different conveyor operating rates.
The simulation model provided the solutions to ensure that the operation would achieve the production target. This was achieved while minimising the capital expenditure required. The study showed that the most gain in trying to reach the production target was achieved through increasing the conveyor capacity and by revising the maintenance plan for the conveyor.
A number of areas provided detailed information for the client to make an informed decision regarding capital outlay. This included assessing the truck fleet to ensure the mines could produce sufficient feed to the conveyor. The model allowed fleet and truck sizing recommendations to be made to minimise the number of trucks required to meet current and future targets.
By using these proven methods, the case study participant now has the real problems are identified, and further opportunities for improvement were uncovered. In addition, the participant has a model which can be used through the entire life of the project to optimise performance and minimise costs.
Typical study benefits include:-
- Providing a valuable source of information to assist the owner’s team with key design criteria
- Evaluating the sensitivity of major design settings and quantifying their impact on sustainable production
- Providing operational insights into the system’s behaviour under varying conditions
- Assessing the component interfaces and the impact on the total integrated system
- Providing confidence in the final design’s ability to achieve production targets
Simulation modelling can be used to accurately predict the behaviour of any system, operating or proposed, to:-
- Solve production problems
- Eliminate bottlenecks
- Minimise queuing
- Deal with variations in supply and demand
- Confirm the most effective expansion path
- Utilise existing assets more effectively
- Understand why certain events occur
- Aid in strategic planning
- Communicate the understanding and ideas behind proposed changes
TSG models and analytical consulting services have helped Boards and management executives of major companies come to grips with the complex issues involved in both new projects and existing operations.
Better decisions can be made when the right facts can be examined, various options explored and conclusions tested. Simulation modelling and scheduling are the tools required to make this process work.