Sept/Oct 2008

Providing mine scheduling solutions

The XPAC AutoScheduler helps Petro-Canada meet targets at the Fort Hills mining project

By M. Sabourin

The Fort Hills lease, located on the east side of the Athabasca River, is one of the largest undeveloped oil sands leases left in northern Alberta. The Fort Hills mining project, which is a partnership between Petro-Canada (60 per cent), UTS Energy Corporation (20 per cent) and Teck Cominco Limited (20 per cent), is anticipated to produce 165,000 barrels of recovered bitumen a day, with a mine life expectancy of about 80 years.

In 2006, Petro-Canada Oil Sands Inc., which is responsible for the lead development as well as the operation of the project, drafted some plans for the mine. At that time, only three major mining scenarios could be generated due to existing time limits and the lengthy process that is inherent to manual scheduling. Consequently, Petro-Canada began to review some software packages in order to optimize their future mine planning and scheduling. After careful consideration, they chose the XPAC AutoScheduler software application, which was developed by the international mining consultancy company

Manual scheduling versus the XPAC AutoScheduler

When manually producing a schedule for a mine, the user personally selects the order in which blocks of material will be extracted. Once this schedule is complete, results are analyzed to see if corporate objectives for the mine are met. If not, the user goes back and adjusts the order in which the blocks are mined and tries again. The process is iterative and very time-consuming. In the case of the Fort Hills project, approximately one to three weeks were required to manually generate each new schedule.

Comparatively, Runge Mining’s XPAC AutoScheduler software enables multiple planning and scheduling scenarios to be created in a very short period of time — mere minutes, in fact. The scheduling process is not completely automatic, as some manual input is still required from the user, but the procedure is far simpler.

  • First the user imports geological quantities and qualities into XPAC.
  • Next they identify the “rules” and “constraints” of the mining operation and enter them into the program. These can include, but are not limited to: general relationships about how blocks are mined (for example, no underground mining); the exclusion of blocks outside geological boundaries; and restriction of  mined quantities in certain scheduling periods.
  • Next, the user enters the targets and/or corporate objectives for the mine. These can include financial targets, objectives to preferentially mine ore of a certain grade, as well as other priorities.
  • Finally, the XPAC AutoScheduler quickly produces a schedule for the mining operations. It selects an order for the blocks to be mined that will aim to meet the targets and objectives, while respecting the rules and constraints that were previously defined.

As explained by Fraser Rowe, manager of North American Operations at Runge Mining Ltd., it is not a situation where you can simply push a button and obtain your solution. “But what it does enable you to do,” said Rowe, “is look at a lot of scenarios very quickly, which you would never be able to do with manual scheduling, and then you can determine the two or three schedules that you wish to pursue in more detail.”

In addition to being able to quickly run multiple schedule scenarios, the XPAC AutoScheduler is particularly useful in the planning of mines where product blending or complex stockpiling is required, or for mines that have very large data sets. “The software is also applicable to a number of different styles of mining, including underground mining,” added Rowe. So far, Runge Mining’s XPAC AutoScheduler has had great application — and success — in oil sands projects such as Fort Hills.

Planning and scheduling extractions

In May 2007, in order to complete Phase I of their conceptual mine planning, Petro-Canada Oil Sands Inc. requested Runge Mining’s services to help construct and carry out a very specific XPAC AutoScheduler model for the Fort Hills mining project. The goal was to quickly produce as many schedules as possible for the extraction of the material within the Fort Hills deposit and then to choose one that would best suit the corporate objectives. Multiple scenarios were looked at, such as maximizing or minimizing bitumen grade as a priority in the extraction sequence.

Another variable that was considered when running potential mining schedules through the XPAC AutoScheduler model was the strip ratio. The strip ratio pertains to the amount of overburden that has to be removed in order to attain bitumen deposits below. “Ideally you want to minimize [the stripping ratio],” pointed out Rebecca Jones, mining consultant at Runge Mining Ltd. “But at the end of the day you will still have to move that overburden to get to some of the bitumen deposits; therefore, you want to try and plan for it — that is, when and how you’re going to move it.”

Jones, who has been working closely with Petro-Canada, went on to explain how keeping the strip ratio fixed during mining operations will, in turn, keep the equipment requirement (the number of loaders needed) fixed. By taking the strip ratio into consideration when planning an extraction sequence, the need to buy new equipment can be foreseen, which helps meet corporate objectives.

It took the Runge Mining and Petro-Canada team four weeks to set up the XPAC model. Thereafter, the model could successfully produce various scheduling scenarios in mere minutes. Nevertheless, they were faced with a few problems. “Initially, it was a challenge to get the reserve — the material quantity — out of [Petro-Canada’s] design package to enter it into XPAC,” explained Jones. “We overcame that problem with the help of the company that was looking after the design package. They worked with us to get the information that we needed for the model.”

Integrating a dump schedule into the existing schedule

Currently, as part of Phase II, the Runge Mining and Petro-Canada team are working hard to incorporate dump scheduling into the extraction schedule that was produced during Phase I at Fort Hills. “It’s an order of magnitude higher,” stated Rowe. “That’s what we do with all our clients — we do the easy bit first, and once we’ve got that right, we get progressively more complex.”

In addition to scheduling and planning the placement of the dump material, the characterization of the haulage requirement is also an integral part of Phase II of the project. Potential uses for the XPAC AutoScheduler model in the future, within the scope of the Fort Hills mining project, could include more complex in-pit/ex-pit dump scheduling as well as tailings dyke construction scheduling.

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