Geologic Block Modeling enu

7/28/2019 Geologic Block Modeling enu

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Carlson User Training Conference 2009

Carlson Geology: Block Modeling

Grant Wenker, PE Mining Sales and [email protected]

April 07, 3:15 5:00 p.m.

This class takes a set of drillholes and goes through the steps that create the blockmodel. The different grades are defined in the Grade Parameter File. Blocks are drawnand viewed in 3D for analysis. Cross sections are cut and volumes by grade arecalculated with reserves. The Optimized Pit Design is found with the Lerch-Grossmanalgorithm.

Grant Wenker joined Carlson Software in March, 1998. Grant has a M.S. from the South Dakota School of Mines &Technology and a B.S. from the University of North Dakota. He is a registered mining engineer. Prior to joiningCarlson Software, Grant worked on abandoned mine reclamation in the Black Hills of SD, in seismic exploration forhydrocarbons on the North Slope of Alaska, and as a consulting engineer at various PRB mines in Wyoming.
mailto:[email protected]:[email protected]


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Carlson Geology: Block Modeling

Drawing with Drillholes

The first step is to import the drillholes and name the beds based on how the seams are

to be modeled. This example is a limestone bed with a thin layer of overburden, sothere are just two main stone types in the drilling, OB and LS are the bed names.

Drillholes in the Drawing

Make Block Model

This command is used to create the block model. The first selection is to choose theBed Name to model, and then the quality or qualities.

Make Block Model

The next window sets the block size and modeling method. There are two distinctmethods for the blocks. They can be set to a fixed elevation and size, or can follow thetop and bottom of the ore model from the drillholes. This creates almost a stratifiedblock model where the elevations of the block follow the top or bottom of the oreelevations. Both methods work the same. If using the Elevations method, then the topand bottom of the model are entered, with the number of samples chosen to set theblock height. This example will use Inverse Distance as the modeling method with avertical factor of 1. Selecting OK builds all of the blocks and puts them in the BLK file.


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Block Model Sizing

Define Grade Parameter File

This command defines the grade ranges of the ore. This is what defines the blocks forcolors and position for cross sections and volumes. There is a Draw Legend button toput it on the map. The price per pound is also defined here for the cost model.

Define the Grade Parameters

Block Model Viewer

Now that the block model is built and the grade ranges are defined, the model can beinspected and viewed in 3D to make sure it is all correct. If the model is large, it is bestto use an inclusion polyline to view just a subset of the entire model. In the AdvancedTab, there is a way to turn the blocks on and off like layers. Just click on the line to turnon or off and the blocks are removed or added from the screen. This allows 3D view tosee what the quality is inside the middle of the blocks.


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Full Block Model vs/ Partial Grades in View

Draw Block Model

This command will draw the blocks on screen in CAD as permanent nodes or dots.

These nodes can then be brought into the 3D Viewer window and rendered the same asthe Block Model 3D Viewer does. This option allows to have a top and bottom limitingsurface to crop the blocks.

Draw Block Model

Block nodes in the drawing

Define PreCalculated Grids

This step is necessary to combine the block model with the surface topo and any top orbottom elevation grids that will make up the entire model. The procedure is to just addthe elevation grids as normal, and then add the BLK block model file to the appropriateinterval. Flat elevation grids can be used for this, if it isnt a stratified model that hasroofs and floors, like many hard rock mines and quarries that arent.


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PreCalc File with the Block Model attached

Fence Diagram

Now that the entire model is put together, the Fence Diagram can be drawn to see theblocks in section view. It has an option to Hatch by Block Model. This can be drawn intwo ways. The initial section shows it on a 2D Grid, the second one can be seen in 3Dwhere it draws and hatches the fence in 3D below the line.

Cross Section Fence Hatched by Block Model

3D Fence Diagrams and Drillholes


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Surface Mine Reserves

The last step is to get the volume and tons of the different grades with the Surface MineReserves. There is one check box to turn on that is Breakout Quantities by Attributes.This will not only give total tons of the granite, but also the tons in the various grades.

Breakout Quantites by Attributes Option

Shown here is the report of the data dumped into Excel. Notice how the total Key tonsmatch the individual grade tons added up in the yellow cell. This is a good check tomake sure all grades are accounted for in the report.

Excel Report confirming the tons

Prepare Value Block Model

This command initially needs the parameters defined. Enter Economic Parametersbrings up the next dialog where costing is entered.


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Grade Parameters

Economic Parameters

This writes the value block model, where each block now has a value assigned to itwhether it is profitable or not. This file is named Value Block Model.BLK.

Optimized Pit Design

Now that the Value Block Model is written, the Optimized Pit Design is run to create theultimate pit and create the ultimate pit block model. The Value Block Model is now thefile to process. This creates an ultimate pit grid, block model and a report. The blockmodel is just for calculation purposes and contains cost values.

Ultimate Pit Options


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Ultimate Pit Grid in 3D

The final report shows that most of the blocks are mineable. The lowest level, 5 is notmineable. The blocks that are not profitable are what is left in the above images. It iseasy to make changes in the input parameters and run it again. The cost to mine orprocess the ore can be modified and the new cost model created to see how it affectsthe output.

Ultimate Pit Report

Geologic Block Modeling enu

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