Mineteck Scheduler is a strategic scheduling tool for open pit mine.
It applies a novel optimisation algorithm which simultaneously optimises major variables including stockpiles and blending. This new scheduling algorithm allows Mineteck Scheduler to generated solutions with better NPV than major tools on the market based on over 10 test cases.
Mineteck Scheduler allows company to optimise the project value and at same time generate stable cash flow for each period.
Mineteck Scheduler has an auto-stockpile program. Stockpile are automatically configured and reclaimed in the scheduling tool.
Global optimisation is achieved by simultaneously trade-off between major variables of open pit mining and at same time meeting all the constraints. When major variables and constraints are missing in that trade-off, the solution from the optimisation can only be considered as sub-optimal.
Mineteck has developed an algorithm to simultaneously trade-off between all the major variables with linearization of some variables. The constraints include:
- Mining capacity.
- Process capacity.
- The minimal and maximal grades for process feed.
- The minimal and maximal metal production.
- The minimal and maximal cash flow.
- The maximal sink rate for each pushback.
- The maximal advanced rate between pushbacks.
- User defined constraints.
- Stockpile limit.
- Existing stockpiles.
- Truck hour limit.
Mineteck Scheduler is possible the first tool to include all the major variables and constraints in open pit mine scheduling optimisation model. Although simplicity applied in the model may sometimes compromise the optimality of the solution, it provides an opportunity to achieve the life – long global optimisation. Improvement in NPV has demonstrated the advantage of the new scheduling algorithm.
Stockpile is usually configured before scheduling. Each stockpile has a minimal and a maximal grades or equivalent grades for major elements.
Well-configured stockpiles should cover all the possibility of the grade combination to avoid wasting ore and at same time does not mix ores with positive value and negative value.
Mixing ores with positive value and negative value can happen even for a single element case. Configuring stockpiles before scheduling means no cut-off grades are available during stockpile configuration. It is hard to avoid the economical cut-off grade to become a value which is larger than the minimal grade but smaller than the maximal grades of one stockpile and results in the mixture of ore with waste in that stockpile.
A novel stockpile configuration system is applied in Mineteck Scheduling algorithm. In the algorithm, stockpiles are generated automatically, dynamically as well as reclaimed automatically. They are optimised in the scheduling algorithm. It avoids the possible loss of the NPV due to improper configuration of stockpiles.
In a mine with multiple processes, algorithm needs to properly handle ore from mine to one of the processes and stockpiles as well as reclaiming ore from stockpiles to processes. For example, in a mine project with two processes – Mill and Leach, due to the different recovery rates and costs of MILL and Leach, ore is preferred to be processed by the plant which produces better cash flow. However when the preferred process reaches its capacity limit, there are two options for ore’s destinations. In the first option, ore is sent to the less profitable process assuming it produces positive value. In another option, ore is sent to a stockpile and is reclaimed and processed in later period to its preferred process. The second option incurs extra reclaim cost and lost NPV due to time delay when it is processed. Sending ore to less profitable process in the same period or sending ore to stockpile and process it in later period is a trade-off process. It is properly handled in Mineteck Scheduler.
In some project, there are requirements for minimal and/or maximal grades for some element to mineral process. To meet these grade requirements, ore from mines and stockpiles are blended to increase the productivity and return of the project.
Traditionally blending is undertaken independently to mine scheduling. After a mine schedule is generated without grades requirements, blending is undertaken between ore to process and ore from stockpiles period by period.
Two blending algorithms have been implemented in Mineteck Scheduler. Blending is part of the schedule optimisation and provides an opportunity to improve the productivity and NPV.
Ultimate pit generated by pit optimisation tools sometimes is over-sized due to undiscounted block value applied in pit optimisation algorithms. The optimal final pit is believed to be a subset of the final pit generated by pit optimisation algorithm such as LG.
Over-sized final pit issue is very difficult to be avoided during pit optimisation stage. However, final pit which is close to optimal can be found by try and error.
If an over-sized pit shell is chosen as the final pit, some scheduling algorithms on the market will mine everything inside the final pit even the last pushback generates negative NPV.
Mineteck scheduling algorithm at least can avoid mining the pushback with negative NPV.
Mineteck Scheduler provides a functionality to allow user to take control on the schedule solution. User can provide information about the requirement, the algorithm will adjust the solution to generate a schedule to meet user’s requirement.