Intelligent Mining Software Solutions IMS - Model Definitions

Intelligent Mining Software “Solutions” IMS - Model Definitions

Table of Contents

INTRODUCTION 3

WORKING WITH A DEFINITION 4

Create a New Definition 4

Save a Definition 4

Open a Definition 4

Summary of Definitions 5

MODEL SETTINGS PROPERTY SHEET 6

Main Page 6

Stratigraphy Page 9

Assays Page 16

MODEL ALGORITHM SETTINGS PROPERTY SHEET 19

Triangulation Page 20

Inverse (2D And 3D) Page 21

Ellipsoidal Page 23

OTHER ALGORITHMS 25

Length Weighted Average 25

Normal Kriging 25

Log Normal Kriging 25

INTRODUCTION

In IMS, a model is stored in a proprietary binary file that contains a model definition section and a data section. In this manual we consider only the model definition section which is simply a set of parameters relating to a IMS model. These model definitions are used in IMS to identify models, regions, stratigraphic lists, algorithms, and drillhole data files.

The parameters within a model definition include:

· A title for output

· Base point coordinates

· Cell parameters

· Algorithms and parameters

· Stratigraphic units

· Assay / quality lists

· Subcrop and barren area plan file names

· Trend plan file names

· Boundary of interest (region) plan file name

Not all the parameters listed above are required for all definitions. A block model, for example, does not use subcrop, barren area or trend files.

A model definition can be created or modified via the Model Settings property sheet.

WORKING WITH A DEFINITION

Create a New Definition

IMS provides three ways of accessing the Model Settings property sheet:

1) From the main menu select <File<New<Model…>

2) Right click within the required folder in the File Explorer Pane and select <New Model…>

3) Right click in the Loaded Files Pane and select <New Model…>

The Model Settings property sheet appears in all cases with a blank definition. Fill in the parameters as appropriate (see MODEL SETTINGS PROPERTY SHEET).

Save a Definition

When you finish with the Model Settings property sheet simply close it by pressing the <OK> button. If IMS determines that the property sheet was changed in any way then it will prompt you to save those changes (Figure 1).

Figure 1: IMS prompts to save a model definition

Open a Definition

There are two ways of opening a definition:

1. Double click on the definition in the File Explorer Plane

2. Drag the definition from the File Explorer Pane to either the 3D Pane or the Loaded File Pane.

Summary of Definitions

Right click on a folder in the File Explorer Pane and select <Summary of Model Files>. IMS will display a list of all the definitions in the folder together with a subset of their properties (Figure 2).

Figure 2: A list of all definitions in a folder

MODEL SETTINGS PROPERTY SHEET

Main Page

Figure 3: Model Settings - Main Page

This page is used to specify the major parameters for a model definition. A model is defined in terms of coordinates, extent and cell sizes. By defining a matrix, it also defines limitation on the area of interest.

The fields on this page are described in the sections that follow.

File

This is the name of the definition and will be used as the filename. Change this name only if you want to store the definition under a different name without creating a new definition.

Title

This is the definition’s title which is used to identify and describe the definition.

Base point

This is the lower right-hand (south-east) extremity of the model area before rotation. The model is rotated about this point if a rotation is nominated.

Easting and northing coordinates can be based on any coordinate system, such as AMG or ATM, but should be the same as the system used by the CAD and drillhole data.

The "Datum Elevation" is a convenient elevation far above the highest part of the modelled data so that all plan files and data to be used in the project lies under it. A typical value is 10,000m.

The "Rotation" (in degrees) of the model takes place in the Easting-Northing plane. A positive value rotates the model anti-clockwise about the base point. Rotation enables the model boundaries to more closely approximate an irregularly shaped deposit or allows the model axes to run approximately parallel to the predominant structural features.

Cells

This section specifies the size of a cell and the number of cells in the Easting-Northing plane. The X and Y model dimensions equal the cell size multiplied by the number of cells in the respective directions.

NOTE: A good method of determining the number of model cells required for the model area is to check the extents of the drill data and add 25-50m to those extents (for the purposes of running Lerch-Grossman Pit Optimisation).

Model cells need not be square. Use a smaller cell size in the direction of greatest variation if justified. Smaller cells increase accuracy but also increase computer time and space required for model generation.

There is no limit to the number of cells in the X or Y directions.

Model Frame

This is an optional field used to specify the width of the border (in units of distance) around a model within which drillholes are to be used. It allows you to include in drillhole data that lies outside the model area.

Plan File

This is a IMS CAD file that delineates a region within the defined model area. All surfaces outside this region are classed as non-existent (flagged out). The polygon(s) in the CAD file must be closed.

<Model Area File…>

This button brings up the Model Area File dialog box (Figure 4).

Figure 4: Parameters for the model area file

The dialog box allows you to write two polygons to a IMS CAD file: a polygon that encompasses the entire model area and a polygon that encompasses the area of the cell at the base point. If an ellipsoid is defined for the model then the polygons representing the ellipsoid are also written.

NOTE: The reference RL is typically the elevation of the top bench of the definition or above the highest RL of any data.

<Algorithms…>

This button brings up the Algorithms property sheet.

Stratigraphy Page

Figure 5: Model Settings - Stratigraphy Page

This page allows you to enter the parameters for all the stratigraphic units in the model. All stratigraphic units in the model must be defined here and must be listed in their order of occurrence from the surface.

A stratigraphic unit is defined differently for laminar and block models as follows:

Laminar models

A stratigraphic unit is defined as seam names in the model or stratigraphic units of interest when accessing drill data.

Each modelled seam (e.g. coal) generally has an interburden seam name (not modelled) nominated between it and the next modelled seam, even if the modelled seams are adjacent, i.e. the interburden has zero thickness. The exception is when the modelled seam is waste in which case the adjacent seams may be either modelled or not modelled. This convention enables all intervals to be referenced in the model reports.

NOTE: if a seam is not modelled then it can have any suitable name; modelled seams, however, should have the same seam name as specified in the drillhole data file(s).

Block models

A stratigraphic unit is defined as bench names reflecting the elevations in the model or as a general sample unit (normally defined as “C1”) when accessing drill data.

Each stratigraphic unit refers to a bench, which is normally named according to the elevation of the top of the bench. Each bench should be the same thickness if the Lerch-Grossman pit optimiser is to be run on the model. The bench thickness is specified when creating the block model.

There are different ways of accessing and editing the stratigraphic names; the most appropriate depends on the function. These are discussed in the following sections.

Multiple Stratigraphies

Use the parameters in this section to add multiple benches below a specified (existing) stratigraphy. Each new stratigraphy name is calculated by adding the increment to the name of the stratigraphy above it. This, obviously, works only if the seam names are numeric values as is the case for block models.

Example: In figure 5 we want to add 23 new seams below the stratigraphy named 530. With an increment of -5 the new seams will be 525, 520, 515, …, 430.

Add Stratigraphic Units

If there are no existing stratigraphies then select the <Add...> button to add the first stratigraphy. To add a stratigraphic unit when there are existing stratigraphic units:

1. Select an existing stratigraphy.

2. Select the <Add below…> or <Add above…> button to insert a new stratigraphic unit below or above the selected unit.

1. Right click on an existing stratigraphy.

2. Select <Insert Strat (Below)…> or <Insert Strat (Above)…> from the context menu to insert a new stratigraphic unit below or above the selected unit.

Delete Stratigraphic Units

To delete one or more stratigraphic units:

1. Select all the required stratigraphic units.

2. Select the <Delete> button.

To delete a single stratigraphy follow the procedure above or:

1. Right click on the stratigraphy

2. Select <Delete> from the context menu.

Edit a Stratigraphic Unit

To edit a stratigraphy:

1. Select a stratigraphy.

2. Select the <Edit…> button.

1. Right click on a stratigraphy.

2. Select <Edit Strat…> from the context menu.

Or simply double click on the desired stratigraphy.

Stratigraphy Selection

<Select all> selects all the stratigraphies in the list.

<Select none> resets the selection so that none of the stratigraphies in the list are selected.

<Reverse> reverses the selection so that all previously selected stratigraphies are unselected and the previously unselected stratigraphies are selected.

The standard Windows™ <SHIFT> click and <CTRL> click are also available. See Windows™ help for more details.
Stratigraphy Parameters

In addition to a common set of parameters, there are specific parameters that differ between laminar and block models.

A Block Model is simple in its construction in terms of stratigraphic units (though not in terms of the grades) so the benches only require a commodity ("C") classification which tells the system that the benches will carry assays/grades. For those benches that are well above the ore body, a waste classification ("W") is acceptable and this will also reduce the size of the model since no assays are carried for waste benches.

A Laminar Model, on the other hand, has a far more complex stratigraphic definition that encompasses additional parameters such as surface files (Figure 6).

Figure 6: Stratigraphic units for a laminar model

Class of Material

The stratigraphy can be classed as:

Ore: Truncated by the seam above and truncates the seams below. A surface file name must be specified for model generation.

Waste: Truncated by the seam above and truncates the seams below. A surface file is not required but can be specified, e.g. "surface seam", toxic material, intrusions, etc.

Basement: Truncates the seams above. A surface file is required for model generation. This class of material is useful in limiting the extrapolation of overlying seams.

Surface File Name

Each modelled seam is generated separately and stored in a separate file. The name specified here is the unique part of the full model file name for the surface being generated. Select the name carefully so as not to overwrite a previously generated surface file which you may want to use again. The seam name is usually used with an extra letter or two to indicate the purpose of the model.

Enter a name here only for seams that are to be modelled (i.e. containing ore). If no surface file name is specified then the seam will not to be modelled so will be a waste unit.

Trend File Name (Optional)

The application of a trend in seam generation superimposes the structure defined in the trend file (a IMS CAD file) with respect to the elevations of the modelled seam. Trends are a powerful and flexible modelling tool in laminar modelling.

Subcrop/Barren Files (Optional)

These are IMS CAD files which are used predominantly in laminar modelling and have very little use in block modelling.

Figure 7: Stratigraphic units with subcrop and barren files

Subcrop files contain closed polygons that define the limits of ore for the seam. All material outside the limits is defined as non-existent. The limits may be real or arbitrary. The plan outline can extend outside the model boundary.

Barren files are similar to subcrop files but all material inside the limits is defined as non-existent. This is useful for excluding reserves sterilised by shafts, buildings, etc.

Assays Page

This page lists all the assays and qualities that are in the model. It also has a direct link to the algorithm manager (see MODEL ALGORITHM SETTINGS PROPERTY SHEET).

The fields on this page are described in the sections that follow.

Add Assay

To add an assay press the <Add…> button and enter the assay properties in the resulting dialog box. The assay properties are:

Figure 8: Adding an assay

Assay Name

Enter a new assay name or select one of the assays from the drop down list.

Precision

This is the number of decimal places used when grades are reported. It does not affect the actual value stored.

Algorithm

Select the modelling algorithm from the drop down list.

Search Distance

This is the radius from the model cell centre undergoing the algorithmic calculation, within which drillhole data will be included. It is used by all algorithms except “Triangulation” and “Ellipsoidal 3D IDW”.

Use

Select the assay usage from the drop down list. IMS provides the following assay usages (Table 1):