Calculated Blends

Note: MineMarket has two blending modules. See also Manual Blends.

Introduction

The simplest form of calculated blending is to calculate an optimal blend 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, minimising the overall deviation from the target specification, and 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:

  • 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 a specific blend period. 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 minimum and maximum values. In the above case, allow CV to be no lower than 6950.
  • 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 desirability. So, in the above example, Stockpile A and B could have a desirability of 5, while Stockpile C has a desirability of 1. The algorithm should attempt to use A and B in preference to C.

Note: The analytes blend as weighted-averages.

Process Overview

To calculate a blend in MineMarket, the minimum process is to:

  1. Set up a Blend Template Category.
  2. Set up a Blend Template:
    1. Select default configuration settings.
    2. Specify stock (or mine) locations, stockpile categories or individual stockpiles or mine sources to be blend sources.
    3. Set the target specifications.
  3. Calculate a Blend. If required, you can change the configuration settings, include or exclude sources and update various quantities and values. However, you cannot add new blend sources.
  4. Export or print the blend results.

Blend Templates

Blend templates are mandatory.

Blend templates store the blending details of the sources (most typically, stockpiles) to be included in a blend, and the desired specifications. You can assign priorities to stockpiles, include or exclude blend sources and specify minimum reclaim quantities.

Blend templates are specific to the Calculated Blending module of MineMarket and are not used with manual blends.

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 blend templates to a stock location, despatch location or stockyard. See Assign Blend Templates to a Location or Stockyard. Assigned blend templates display in the Solution Explorer context menu for the location and its stockpiles.

Configuration Settings

The most important setting is the default target number of tonnes per period.

You can specify between 1 and 24 periods. By default a period is a day, but you can select a shift definition to calculate multiple blends per day, or a calendar to limit the blending to working days.

Other configuration settings control the display of columns for analytes, contributors and other data.

Blend Sources

Stockpiles – most typically mine sources or weighted-average grade (WAG) stockpiles – are used as blend sources.

The Calculated Blending module does not take into account the layers in first-in-first-out (FIFO), last-in-first-out (LIFO) stockpiles. Therefore, the use of FIFO or LIFO stockpiles as blend sources is not recommended, even though they can be selected. Do not use 3D stockpiles with the Calculated Blending module.

When configuring the template, you might choose to add a Stock Location or Stockpile Category as a blend source. If you select a stock location, the stockpiles only display when you use the template to calculate a blend. This simplifies the blend template configuration for locations with many stockpiles, or if stockpiles are often opened or closed at that location. If you select a stockpile category, the stockpiles display in the blend template, allowing for more complex template configuration. When you create a blend using the template, you can refresh the list of available stockpiles at the location or in the category.

You can pre-filter the blend sources in the Source Stockpiles table. In the blend execution, the sources that display after filtering are the only sources that can be included in blend. That is, for any sources that are filtered out, Include is unchecked.

Other configuration of blend sources in the template can include specifying:

  • The desirability of each source
  • The expected production per period
  • A minimum reclaim amount per blend

Specifications

The specifications dictate the target quality and acceptable quality range of the blended material. The specifications can be based on the specifications of a product, brand, stockpile or specification template.

For each analyte in the specifications, you can:

  • Select whether to Include the analyte in the blend calculation.
  • Override the Target, Minimum and Maximum values required for the blend.

Blend Execution

Blend sources can only be used if:

  • The mine source or stockpile is open on the blend date.
  • Analyte values are available in MineMarket, or are entered manually when creating the blend.

You can filter the blend sources in the Source Stockpiles table. The sources that display after filtering are the only sources that can be included in the blend. That is, for any sources that are filtered out, Include is unchecked.

For each source, you can:

  • Select whether to Include the source as a possible source for the blend. MineMarket will not necessarily include every source for which Include is checked. If a source must be used, specify a quantity for Forced Usage. You can also choose to exclude a source for individual blend periods if required.
  • View the Balance, which is the quantity available at the Base Blend Date. All quantities in the Calculated Blending module display in metric tonnes. For mine sources, the available quantity is considered to be infinite.
  • Set a Desirability level. When blending for a stockpile, the current stockpile should always have a desirability of 10 in the blend because its contents will be part of the blend result.
  • Specify a Minimum Reclaim. A quantity entered for minimum reclaim is only used if MineMarket calculates that that source should be included in the blend. Specifying a minimum reclaim is useful to ensure that the suggested blend does not include a small quantity for one source that would be impractical to reclaim.
  • Enter an amount for Production Per Period. This amount is added each period to the calculated Balance. If you specify a production per period for a stock location in a blend template, that quantity is assigned to each stockpile.
  • Update analyte values if required. The values default to the best known values for the source at the Base Blend Date, but these values can be overridden. All analytes in the blend specifications can display for the source stockpiles. The configuration settings include options for the analyte display that can be used in combination:
    • Select an analyte group to limit the display of analyte values and determine the order of the analytes.
    • Only show the included analytes in the blend calculation specifications.
    • Hide analytes without values.
  • Specify a quantity for forced usage per period if required.

    Note: One column displays per blend period. The column header shows the date (and time if required) of the blend. MineMarket uses the Base Blend Date and various configuration settings to determine the date (and time) of the first blend column, and how many blend columns to display.

In the configuration settings, you can select a Contributor Group to display read-only contributor values for the blend sources.

Tooltips display when hovering over different types of cells to convey additional information including validation issues and stockpile balance details for specific blend dates.

You can update the blend specifications inherited from the template if required.

Blend Results

If a blend is possible, the blend displays within the Source Stockpiles table. Otherwise, an error message explains why the blend with the current criteria is not possible.

The blend results can be exported to Excel, copied to the clipboard or printed. They cannot be saved in MineMarket.

The Blend Results Script Editor can be used to enter a C# script to update the results of a calculated blend if required.

Transaction Creation

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. (However, in Manual Blends, MineMarket can create transactions and any required process flow.)