Create an Optimized Pit/Ore Extraction Model

RockWorks | ModOps | Volume | Extract via Surface Excavation

This program reads an existing solid model (such as soil chemistry or lithology model), determines the volume of a pit that would be required to extract the portions of the solid model that fall within a specified range (e.g. contaminated soil or a selected lithotype). The program allows you to specify the name of a surface grid model so that the final diagram is not based on a flat surface.

The output is a report that lists the pit and contaminant volumes and the stripping ratios, a 2D diagram illustrating the pit elevations, and/or a 3D diagram showing the filtered solid and the pit elevations.

This program assumes you have already created a solid model that illustrates the distribution of the desired material. This can be created using the ModOps | Solid | Create program (for XYZG data in the datasheet or external file) or using the Borehole Manager Model tools (Lithology, Stratigraphy, P-Data, I-Data menus). You may also input solid models that have already been filtered for G value range or with a polygon filter (Solid | Logic or Solid | Filter programs).

This program also assumes that you have already created a grid model of the surface topography that will be used when modeling the pit. The surface grid model must have the same dimensions and node counts as the X and Y dimensions of the input solid model.

Feature Level: RockWorks Basic and higher

Menu Options
Step-by-Step Summary

Menu Options

• Rules & Filters
  Use the tabs at the top of the window to apply spatial filters, time/date filters, or stratigraphic rules to data being displayed in your striplogs, if activated. (More info)
• 
  
• 3D Log Design
  If you decide to include logs with this diagram ("Striplogs" setting, below), click on this tab at the top of the window to set up how you want the 3D logs to look.
  See Visible Item Summary and Using the 3D Log Designer for details.
• 
  

  ---

• Options
  Click this tab to set up the model extraction parameters.
  • Environmental Remediation: Choose this if the solid model being extracted represents contaminant concentrations.
  • Mining: Choose this if the solid model being extracted represents ore.
  • 
    
• Input/Output Models
• • Pre-Excavation Models (Input)
    • Ground Surface Grid Model: Click on this prompt to locate the name of the existing RockWorks grid file (.RwGrd) that represents the surface topography, in elevations, for the solid model to be processed. The grid must have the same dimensions and number of nodes as the solid model in the west <-> east and south <-> north directions. The program will use this surface to more accurately drape the output grid and represent computed volumes.
    • Resource Model (Solid): Click on this prompt to browse for the existing solid model to be filtered. This model can represent lithology types, soil geochemistry, etc. This file should have an .RwMod file name extension.
    • 
      
  • Post-Excavation Models (Output)
  • • Pit Grid (Post-Extraction Surface): Click on this prompt to enter a name for the grid (.RwGrd file) that the program will create. This grid will represent the surface elevations of the extraction pit.
      
    • Ore (Solid): Click here to type in a name to assign to the filtered solid model (.RwMod file). This will be a real-number solid model, not a Boolean model.
    • Mined Waste (Solid): Click here to type in a name to assign to the waste surrounding the solid model (.RwMod file).
    
    
• Thresholds and Filters
• • Thresholds: Use these settings to specify the range of G values in the solid model to be extracted. If you are using an I-data or P-data model from the Borehole Manager, the thresholds will be entered as real number values. If you are using a Borehole Manager lithology model, the thresholds should be real numbers on either side of the integer lithology value to be extracted. If you are using a Boolean model, the thresholds should represent "0" or "1".
  • • Lower Threshold: Enter the lowest value in the input model to be extracted.
    • Upper Threshold: Enter the highest value in the input model to be extracted.
    • Maximum Slope: Click on this settings to specify the maximum slope angle for the excavation surface (pit). Slope angles must be expressed in negative degrees from -90 (vertical) to zero (horizontal).

    • 

      
      
    • Maximum Depth: Insert a check here if you want to specify a maximum extraction depth relative to the surface. This setting is also shown (if enabled) within the statistical report. Enter the maximum depth into the prompt. The units must match your output elevation units.
    • Maximum Acceptable Stripping Ratio: Insert the ratio you wish to use. Starting at the base of the model, an imaginary inverted cone is constructed based on the Maximum Slope and helps to determine if the unit is mineable.

    • 

  • Add Benches Activating the Add Benches option will set adjacent lateral non-ore voxels adjacent to ore voxels within the specified Width to a mined waste classification. This will provide space for mining equipment to extract the ore. Note: Adding benches will increase the overall stripping ratio.
  • • Bench Height: Type in the height for the benches, in your output elevation units.
    • Bench Width: Type in the width for the benches, in your output elevation units.
    • 
      
  • Perimeter (Property Boundary) Filter: Check this item to filter the model within a pre-defined polygonal area. All areas of your extraction model that lie outside the polygon will be excluded from the calculations.
  • Add Unmined Vertical Pedestals Based on Boolean Grid Model: Use to modify the excavation surface model based on a Boolean grid model. Specifically, pit shell elevations that are coincident with “true” (z=1) Boolean grid cells will be restored to the initial ground surface elevation while any ore voxels below these cells will be classified as “unmined”.
  • 
    

  • 

  • Optimize Pit Design: This option will be displayed if you have set the Nomenclature (above) to Mining. If activated, this option will start by computing the configuration for a pit that extracts all of the material within the specified grade range. It will then decrease the maximum pit depth (by the increments specified by the "Depth Increment" setting) until the stripping ratio is equal to or less than the specified "Maximum Acceptable Stripping Ratio".

  • 

• Report Options
  • Material Density: This setting is used to convert volume (in cubic feet or meters, depending on your X, Y, and depth units ) to mass, to result in pounds or kilograms or tons per cubic foot or meter.
  • 
    
  • Report Captions: Enter the text for the extraction report so that it makes sense for your project: In this example, you can use the text colors shown below to match the report item to the report example at the end of this topic.
    • Cutoff Units: This represents the G value units in the model for which you are filtering. For example, if the model represents soil contamination concentrations of PCB’s in parts per million, you could enter ppm.
    • Target name: This represents the name of what the G values represent in the model, such as PCB for the above soil contamination example. For a lithologic model, it could be "clay".
• 3D Solid Diagram
  Check this box to display the extraction surface and the output (extracted) solid model as a 3D diagram at this time. They will be displayed using the colors defined above, under Options | Input/Output Options.
  
  • Striplogs -> Other 3D Files: Use these tabs to set up the 3D solid layers.
  • Output Options: Use these settings to define whether the output scene is to be saved (or displayed as "untitled"), how the file should be named, and whether it is to be displayed after it is created. It also offers export options. (More info)
  • 
    
• Report
  • Click this tab to define the output format(s) for the report. (More info)
  • 
    

  Step-by-Step Summary

  1. Select the ModOps | Volume | Extract via Surface Excavation menu option.
  2. Enter the requested model, filter, and diagram settings, described above.
  3. Click the Continue button at the bottom of the window to proceed.

     RockWorks will read the input solid model and determine those voxels that fall within the declared thresholds. It will determine the extent of a vertical-wall pit for extraction of these solid model areas. It will compute total extracted volume, total solid model volume, and stripping ratio (overburden:solid).

     If requested, the report will be displayed in a text tab in the Options window. (See Example, below.) The requested diagram will be displayed in a RockPlot3D tab in the Options window.

  4. You can adjust any of the settings via the Options tab to the left and then click the Continue button again to regenerate the diagram(s).
  5. View / save / manipulate / export / print the diagram in the RockPlot3D window.
     

  Example

  Solid Extraction Statistics
  ---------------------------
     PCB Volume ... 37,132 Cubic Feet
     PCB Mass ..... 427.0 Tons

     Soil remediation site Volume ... 331,777 Cubic Feet
     Soil remediation site Mass ..... 3,815.4 Tons

     Maximum Soil remediation site Depth: 25.6 Feet

     Stripping Ratio: 8.935:1

     Assumptions:
        - Initial ground surface is assumed to be flat.
        - Excavation walls are vertical (no benches or slopes).
        - PCB volume based on the following cutoff values;
          Minimum PCB Value: 0.5 ppm
          Maximum PCB Value: 9,999.0 ppm
        - Density Conversion Factor: 0.0115 Tons Per Cubic Feet

  See also

  • Measuring Your Rock Density
  • Adding this program to your Playlist
  • Adding this program to your Favorites
  • Save/load/view menu settings
  • 
    

  ---

  Back to Volumetrics Menu Summary

  

  RockWare home page