Blending

The simplest form of blending is where a user wants to calculate an optimal blend on a one-off basis from a set of source stockpiles: Given a set of source stockpiles of known quantity and quality (for example, finished coal), calculate the best possible blend for a target blend specification (for example, a train), minimising the overall deviation from the target specification, taking several constraints into account.

For example, take the case of two analytes, where the sources of the destination blend are Stockpiles A, B and C. Stockpile A contains 1000 tonnes, 12% ash, 6500 CV. Stockpile B contains 2500 tonnes, 14% ash, 6100 CV. Stockpile C contains 1500 tonnes, 8% ash, 6800 CV. The blend target is 2000 tonnes, 9.5% ash, 7100 CV.

This is subject to:

Analytes are not all equivalent in importance. CV may be more important than ash, so the algorithm must allow weighting factors to be assigned to each analyte. In this case, CV could be set to have a weighting of 3, and ash to have a weighting of 1.
The blend must be practical in terms of reclaiming. A minimum reclaimable quantity for each source stockpile must be configurable. In this case, set a minimum of 20 tonnes for each source stockpile (that is, the calculated blend must not call for less than 20 tonnes from any stockpile, but it can call for zero tonnes from a stockpile).
The user may want to force a certain amount of a material to be used from a specific stockpile. For the above case, specify that exactly 500 tonnes must be used from Stockpile A.
Absolute limits must be enforceable. Even though the algorithm is being asked to calculate the blend that is as close as possible to the target (but does not necessarily exactly meet the target for every analyte), some analytes can have rejection limits that may not be violated. In the above case, allow CV to be no lower than 6950.
Warning limits for analytes may be exceeded, but only if absolutely required. In the above case, allow CV to have a warning limit of 7050.
The sum of material from Stockpiles A, B and C must equate to 100% of the blend, and no proportion may have a negative value.
In some cases, it is desirable to be able to specify a factor for each stockpile that indicates its desirability in the blend. For example, if many blend combinations are feasible, the algorithm should pick the blend that uses the stock in order of preference, based on the factor. So, in the above example, Stockpile A and B could have a factor of 5, while Stockpile C has a factor of 1. The algorithm should attempt to use A and B in preference to C.

Note: The analytes blend as weighted-averages.

Blend Sources

Blend sources can be mine sources or weight-average grade (WAG) stockpiles. The Blending module is not designed to work with first-in-first-out (FIFO), last-in-first-out (LIFO) or 3D stockpiles.

A product or brand can be added as a blend source to represent material that is expected to be already in transit (that is, currently loaded on despatches) to the blending location.

Blend Templates

Blend templates are optional (but recommended). Blend templates save time when creating similar blends. Blend templates store the blending details of the locations or stockpiles to be included in a blend, along with the desired specifications. You can assign priorities to analytes and stockpiles, filter and exclude blend sources and specify minimum and forced usage reclaim quantities.

You can create blend templates directly from the Solution Explorer under a blend category, or by saving a blend as a blend template.

A blend template must belong to a blend template category or sub-category. If you save a blend as a blend template, MineMarket stores the blend template in the Unassigned Blend Templates category. You can drag blend templates to another blend template category if required.

You can assign a blend template to a stock location, stockyard, despatch location or waste location. Assigning a blend template to a location makes the blend template available via the context menu for that location in the Solution Explorer.

Blend Calculation

You can calculate blends for the following objects: locations, stockpile categories and WAG stockpiles (via the Solution Explorer), trains (via the Train Explorer), service trips (via the Barge Explorer), and shipments (via the Shipment Explorer), and despatch orders on despatches (Train, Truck Despatch, Service Trip, Shipment or Lot Despatch).

For blends calculated without using a template, default blend source stockpiles are the stockpiles at locations for which there is a process flow to the blending location. You can add stockpiles at other locations, which is reasonable if those stockpiles are further back in the supply chain. There may also be material known to be in transit, and you can model this material by adding products or brands as 'source stockpiles'.

Example: Consider 20,000 tonnes of Product A on trains and 15,000 tonnes of Product B on barges (all in transit to the blending location). When blending, material that is loaded onto trains and barges cannot be seen, even if it is in transit to the blend location at the time. To overcome this, add Product A and Product B as virtual product stockpiles, and enter the tonnes for each: Product A (20,000) and Product B (15,000). Then modify the quality values (if required, because they default to the product target values) to simulate the total quality on these trains and barges.

Blend Results

If a blend is possible, the blend displays on the Results tab. Otherwise, an error message explains why the blend with the current criteria is not possible.

In the blend results, colour indicates the range in which the analyte value falls. Between the lower warning and upper warning, the colour of the row is the system-defined background colour. Between the minimum and lower warning, or upper warning and maximum, the colour of the row is orange. If the value of the analyte is on or outside the maximum or minimum, the colour of the row is red.

Blend Assignment

You can assign stockpile or despatch order blend results to later compare the analyte values of the blend with actual analyte values. These planned analyte values display on the Current State tab of the stockpile or the Summary tab of the applicable despatch.

'Assembly blending' occurs when a blend is assigned before any loading transactions occur, and then interim blends are calculated that take account of the actual transactions.

Blending Module Limitations

The Stockpile Results and Blend Results tables can be copied to the clipboard or printed. However, MineMarket cannot automatically create transactions from the suggested blend stockpiles. This is because source stockpiles may have been used for which there is no direct process flow between the locations.

Only the latest assigned blend values can be viewed on the stockpile or despatch. However, you can view all blends via the Blending screen.

Analyte values from a blend assigned to a despatch order cannot be viewed on the Despatch Order; however, the analyte values can be viewed on the Summary tab of the applicable despatch.

Blends can be calculated for service trips and shipments without a despatch order (via the Barge Explorer or Shipment Explorer); however, these blends cannot be assigned. Nevertheless, the blend results can be copied to the clipboard or printed, and remain available via the Blending screen. Blends for trains without a despatch order can be calculated (via the Train Explorer) and assigned to a train rake.

Likewise, blends calculated for locations and stockpile groups (via the Solution Explorer) cannot be assigned.

Blends cannot be calculated for truck despatches; however, can be calculated for despatch orders on a truck despatch or on a lot despatch of trucks.

Do not use the Blending module with first-in-first-out (FIFO), last-in-first-out (LIFO) or 3D stockpiles.