Seam Compositing in GEOVIA Minex

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GEOVIA Minex can store chemical or analytical data in a set of user-defined database tables. Typical datasets include coal seam proximate analysis, such as analysis of ash, moisture, FC, VM and UHV.
A unique feature of Minex is that the seam interpretation is separate to these data tables. Minex then composites or combines samples into a seam or working section.

Minex supports several types of compositing, one of them being Seam Compositing, which we will describe in today’s post. Our next post will focus on Bench Compositing.

The seam composite is based on accumulating samples within the seam. These samples are combined using:
1.    Thickness weighting
2.    Thickness and density weighting
3.    Thickness and density and wash plant yield weighting

The following table and image show a set of sample data with a seam R2. The data is ash, moisture, UHV and density.

Seam composite of ash based on thickness and density weighting – colors show ash content

To deactivate (or activate) density weighting, set the database header as shown in the following image. Here the RD weighting has been inactivated and weighting is by sample length.

Seam composite weighted by sample length only

 

In situations where coal is washed, the product quality such as product ash must be weighted by the wash plant yield.

Consider an example where a product ash has been created as 70% of the insitu ash and yield is 100 – ASH/2. The Minex SQL is shown below:

SELECT X
WHERE ASH # NULL
IF SELECT X
YIELD = ASH/2
YIELD = 100 – YIELD
PROD_ASH = ASH * 0.7
ELSE
YIELD = NULL
PROD_ASH = NULL
ENDIF

When initializing the product variable, the washery yield variable is specified.

Setup for a variable weighted by plant yield

The resultant data is as follows.

The following image shows this graphically.

Seam composite for product ash variable weighted by sample length, sample density and sample wash plant yield.

 

Seam composites are typically applied to a lithological correlatable seam. However, in thick coal seams it may be necessary to mine the seam in benches (for example benches of 10 metres height). In these cases the seam file is set up as a set of benches such as BEN1, BEN2 etc, and compositing occurs across the bench.

We will discuss this further in our next post on Bench Compositing.

You may also be interested in our other Minex posts on How to Plan Boreholes and Using the Seam Washout Grid.

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Ajay Reddy

Ajay Reddy

Senior Industry Process Consultant, Mining at Dassault Systèmes
Ajay Reddy is a qualified Geologist with over 24 years of experience in coal exploration, mining and resources estimation. He has previously worked for one of the largest Indian coal exploration and mining companies, Singareni Collieries, and TATA Steel. Based in Brisbane, Australia, Ajay specializes in GEOVIA Minex and Surpac.