2.0 MicroMODEL SYSTEM OVERVIEW

Subheadings for this chapter are as follows:

MicroMODEL is comprised of several modules which assist the user in the analysis of mineral deposits amenable to block modeling methods.

This software package enables the user to enter drill hole data, and then statistically analyze and display this data. Next, a two-dimensional model of the surface topography is built. Upon completion of the topographic model, a three-dimensional geologic model of the deposit is constructed either from the drill hole information or digitized polygons. Drill hole data is then composited, for statistical reasons. Next, the necessary grade models are built as three-dimensional grids using polygonal, Inverse Distance to a Power, (IDP) or kriging estimation methods. Finally, the user can evaluate material within digitized polygons for contained volumes, tonnages, grades and stripping ratios. A floating cone algorithm is available to aid in open pit design.

The main modules within MicroMODEL are:

The following text contains a brief overview of each MicroMODEL module. A more comprehensive discussion of each program can be found in the MicroMODEL Program Documentation, Volume II, Sections 1.0 through 9.0.

2.1 Data Entry Module Overview

The Data Entry Module is invoked when the user needs to input, output, plot, statistically analyze, or manipulate the sample drill hole database. A sample database is generally comprised of drill hole information as it appears in the drill hole logs.

Prior to entering the drill hole data, the Project Information File must be established. This file contains information that each program will need for execution such as model orientation and dimensions, number and names of the labels, etc. It is mandatory to have run the Project Information Program before any other programs can be run.

The remaining programs in this module enable the user to enter and analyze sample drill hole data. Drill holes are allowed at any orientation with up to 1000 downhole directional surveys per drill hole. (Drill hole collar card plus 999 downhole survey cards). Each drill hole interval is specified by its interval FROM and TO, rock type (code), and assay values. Continuous intervals and sampling are not necessary, but are highly recommended. Simply enter unsampled values for all intervals that are not sampled.

Two methods of entering drill hole data into a MicroMODEL database are available:

The user can specify the record formats of the ASCII data file that is to be read.

At any point, the sample drill hole database can be output to a printer in a report style format allowing the user to verify the input data. This program can also be used to create a free format ASCII file which can be subsequently edited and reread into MicroMODEL. This ASCII file also serves as a backup of the drill hole database.

It is highly recommended that the user maintain all original data in some sort of a spreadsheet format, since almost every user has a copy of Lotus, Excel, Quattro, or some similar program. Use the program that reads separate data files to create a standard MicroMODEL input file. Note that special tools may be available for converting from a wide variety of data formats directly into the standard MicroMODEL input format. Contact support if you need to convert from another format.

Three plotting programs are available to produce maps of the drillhole sample data. The first program plots drill hole collar locations along with several user specified lines of information. The second program plots drill hole mid-bench pierce points and corresponding data for any user specified level of the model. The third program plots drill hole cross sections at any orientation and vertical exaggeration. This program can be instructed to plot a drill hole interval value numerically, or as a histogram along the left or right side of each drill hole. Optionally, filled color bars may be plotted to depict different rock types or grade ranges. The cross-sectional topographic trace can also be plotted with this program. Each of the map plotting programs enable the user to design the format of the plot to suit his particular needs.

As with all plot files created by MicroMODEL, the graphical display plots can be previewed on the computer screen before being sent to the plotter.

By utilizing the programs in the Data Entry Module, the user can enter, display, and verify the drill hole database. Once the user is confident he has a "clean" drill hole database, it can be used in subsequent rock modeling, compositing, and grade modeling.

Finally, the unnecessary temporary, print, and plot files can be deleted by MicroMODEL if the user is satisfied with the drill hole database. This step does not delete any files that will be required later.

2.2 Surface Modeling Module Overview

The Surface Modeling Module contains a series of programs that enable the user to analyze prepared point data. Point data can be prepared from any combination of digitized contours, drillhole collars or downhole rock horizons, or XYZ data files. The prepared point data can be used to create 2-D grid models of topopgraphy, or of thickness. Once the models have been created, they can be displayed in one of several different ways.

From input data comprised of drill hole collar locations and/or digitized data, MicroMODEL has three methods to create a surface model:

Each of these modeling methods assigns an elevation or thickness value to the center of each cell that can be estimated. Unestimated cells can be remodeled using different sorting and modeling parameters or directly assigned elevations with the Grid Editor program (in Module 7).

Before the topographic or thickness data can be used for 2-D grid modeling, it must be prepared. This step aggregates all surface data, digitized and/or drill hole information to be used into one file which is subsequently used for variogram analysis and modeling.

MicroMODEL's kriging or Inverse Distance to a Power (IDP) surface modeling techniques can be used. Prior to modeling grid values with either kriging or IDP, the user can utilize the Variogram Analysis programs to geostatistically analyze the topographic data.

Before cell elevations are actually estimated, MicroMODEL must presort the data relevant to estimating each cell, according to user specified search radii, ellipse of anisotropy, and type of search (closest point or octant). This extra step before actual cell estimation saves in modeling runtime because the user can try several modeling runs with different modeling parameters using the same presort file. If the search parameters are changed, though, the prepared surface data must be presorted again.

The 2-D grids can be displayed by five methods within MicroMODEL. Each method allows the user to design the output to fit his particular needs. The types of grid displays offered by MicroMODEL are:

As with all plot files created by MicroMODEL, the graphical display plots can be previewed on the computer screen before being sent to the plotter.

Finally, the unnecessary temporary, print, and plot files can be deleted by MicroMODEL if the user is satisfied with the topographic model. This step does not delete any files that will be required later.

2.3 Rock Modeling Module Overview

Once a satisfactory two-dimensional topographic model has been built, the user must build a three-dimensional model of the deposit geology (rock model). The purpose of the rock model is to enable the user to control how the drill hole data is used during grade modeling, as different rock types may need to be modeled independently. MicroMODEL offers four methods to build a rock model, which can be used in any combination:

Rock modeling from drill hole data is the simplest way to develop a rock model. This method is generally used when detailed control during grade modeling is not required. This method makes nearest neighbor assignments from the sampled or composited drill hole interval data to each block center. Ellipsoids of anisotropy can be used to further control the block assignments.

Plan view polygonal modeling assigns all rock model blocks that are below the topography and contained within a "rock volume" with a user specified rock code. The "rock volume" is defined by the digitized polygonal shape, a bottom elevation, and a top elevation.

Cross-sectional polygonal modeling also assigns a user specified rock code to all rock model blocks that are below the topography and contained within a "rock volume". In the case of cross-sectional rock modeling, the "rock volume" is defined by the cross-sectional shape extended a user specified distance, perpendicular to the section line.

Rock modeling from a grade model allows the user to specify grade cutoffs and assign a rock value to each interval. The user must create an interim rock model with dummy codes first, in order to create the grade model.

Generally, the cross-sectional polygon method is most frequently used, as geologic information is normally recorded in cross section. As stated earlier, the three methods can be used in combination. For example, it may be advantageous to use digitized polygons in cross section to define the geology, and then overlay a plan view polygon which limits the extent of the deposit mineralization to prevent the grade modeling programs from estimating grade into known barren zones.

The rock model grid can be displayed by six methods within MicroMODEL. Each method allows the user to design the output to fit his particular needs. The types of grid displays offered by MicroMODEL are:

As with all plot files created by MicroMODEL, the graphical display plots can be previewed on the computer screen before being sent to the plotter.

Finally, the unnecessary temporary, print, and plot files can be deleted by MicroMODEL if the user is satisfied with the drill hole database. This step does not delete any files that will be required later.

2.4 Drill Hole Compositing Module Overview

The programs from the Compositing Module are invoked when the user wants to composite the sample drill holes, output, statistically analyze, or manipulate the composited drill hole database. Most of the programs in this module are identical to those contained in the Data Entry Module (Section 2.1). When these programs are invoked from the Compositing Module, they access the composited drill hole database rather than the sampled drill hole database.

Compositing the drill holes creates a composited database which is usually considerably smaller than the sampled database. MicroMODEL has three types of compositing:

Drill hole compositing prorates the sample drill hole interval assay values into composite intervals equal to the model bench height down the hole. This method does not take into account the dip of the drill hole or the composite interval relative to the bench location. See Volume II, Compositing, Calculation of Composite Values for more information.

Mixed compositing is an attempt to bench composite all drill hole intervals. Drill holes that cannot be bench composited due to shallow drill hole dip are composited downhole (drill hole compositing).

Bench compositing prorates the sample drill hole interval assay values into composite intervals such that the "from" elevation of the composite corresponds to the top (crest) elevation of the bench and the "to" elevation corresponds to the bottom (toe) elevation of the bench. See Volume II, Compositing, Calculation of Composite Values for more information.

Rock type compositing calculates composites using assay values only from within a consecutive string of internals with identical rock codes. Composites are created in equal lengths that are as close as possible to a target length specified by the user. The user must also specify a minimum length for a composite. If a consecutive interval has a total length that is less than the minimum composite length, then no composite is created for that particular consecutive interval. Each composite is given a rock code that is the same as the code for the consecutive string of identical codes. See Volume II, Compositing, Calculation of Composite Values for more information.

Rock type compositing should be used in situations where definite discontinuities exist at rock boundaries. A classic example would be a large quartz vein, where the vein carries grade, but the surrounding host rock is barren.

Composite rock codes for both bench and drill hole composites can be extracted from either the rock model or the most prominent sample rock code within the composite. Generally, the composite rock codes are extracted from the rock model since the rock model represents an interpretation of the deposit geology.

At any point after compositing, the composited database can be output to the printer in a report style format, allowing the user to verify the composited data. The drill hole database editor can be used to correct errors discovered in the composited drill hole database.

The remaining programs in the Compositing Module, including statistical and display programs, are identical to the programs described in Section 2.1, Data Entry Module Overview. Remember, the programs invoked from the Compositing Menu will access the composited drill hole database.

Finally, the unnecessary temporary, print, and plot files can be deleted by MicroMODEL if the user is satisfied with the drill hole database. This step does not delete any files that will be required later.

2.5 Grade Modeling Module Overview

The Grade Modeling Module contains a series of programs which enable the user to geostatistically analyze drill hole assay data, model the assay data into three-dimensional grade models, manipulate the models, and display the models.

The grade modeling methods available are polygonal, Inverse Distance to a Power (IDP), and kriging. Grade modeling can be controlled by rock type to separate populations with different characteristics. Further control of the grade modeling can be achieved by using anisotropic data searches and anisotropically weighted modeling.

For each estimated cell within a grade model, the modeled grade block value applies to all material within the cell bounded above by the bench crest (or topography) and below by the bench toe. The unestimated blocks do not affect the statistical calculations, but are processed with 0.00 grade values during pit evaluation computations in the Pit Generation and Reserves Evaluation Module (See Section 2.6).

Prior to modeling grade values with either kriging or IDP, the user can utilize the Variogram Analysis programs to geostatistically analyze the drill hole assay data for the current label. Point Validation can be used to cross validate the selected modeling parameters by comparing the estimated values of drill hole intervals against the actual interval values. Manipulation of the grade model is also available to perform algebraic operations on the block grade values. For example, the user may want to convert from ounces/ton to milliounces/ton.

The grade model grids can be displayed by six methods within MicroMODEL. Each method allows the user to design the output to fit his particular needs. The types of grid displays offered by MicroMODEL are:

As with all plot files created by MicroMODEL, the graphical display plots can be previewed on the computer screen before being sent to the plotter.

The user can run basic statistics and cumulative frequency analyses upon the current label's grade model. Correlation analysis can be performed between any two grade models that have been created.

Once the necessary grade grids have been modeled and verified, the user can proceed to the Pit Generation and Reserves Evaluation Module. It is not necessary to model each label present in the drill hole sample or composite database. Only the grade models of interest for Pit Evaluation and Reserves Evaluation need to be modeled.

Finally, the unnecessary temporary, print, and plot files can be deleted by MicroMODEL if the user is pleased with the grade models. This step does not delete any files that will be required later.

2.6 Pit Generation and Reserves Evaluation Module Overview

Once topography, rock, and grade models have been created, the user can calculate mineral resources and evaluate pit designs with the programs in this module. MicroMODEL allows the user to quickly analyze a variety of pit designs and sequences based upon user specified pit parameters by relieving the user of the time-consuming pit evaluation computations. An efficient floating cone algorithm can be used to help design an open pit, based on a given set of economic and physical design constraints.

This module utilizes the previously modeled topography, rock and grade models, and analyzes material within digitized polygons for ore, low-grade, and waste volumes and tonnages, run of mine grades, and stripping ratios. The user has control of the pit slopes and densities that will be used for different rock zones.

The program then reports volume, tonnages, and grade for ore, low-grade, and waste and stripping ratios for each bench containing mineable material for the digitized increment. If the increment is profitable, the user can instruct MicroMODEL to "mine-out" the rock model which prevents the "mined" material from being recounted later. The original topography, grade, and rock models are not permanently changed and that the user can start again with an "unmined" model at any time.

The Open Pit Design (OPD) routines within MicroMODEL enable the user to evaluate ore zones incrementally. However, the floating cone algorithm included under the OPD Main Menu is an easier, automated way to design open pits.

Once the ultimate pit boundaries have been established, the pit model can be inverted, which makes all material outside the pit unavailable for mining. This enables the user to perform sequencing and scheduling within the ultimate pit without accidentally exceeding the current ultimate pit.

The main graphical display programs offered in the Pit Generation and Reserves Evaluation Module are identical to those offered in the Grade Modeling Module with one exception. The contouring program in this model interfaces with the topography and mined-out rock models to give a toe elevation contour map of the current pit model.

In addition, there is a graphical display choice that allows the user to plot a section profile of any digitized contour map.

Finally, the unnecessary temporary, print, and plot files can be deleted by MicroMODEL if the user is pleased with the grade models. This step does not delete any files that will be required later.

2.7 File Management Module Overview

The programs in this module allow the user to make global changes and manipulations to the MicroMODEL database as required throughout the modeling process. This module also includes programs for selecting subsets of drillhole data, and a program for overlaying several plots.

The statistical and modeling programs access the current label. One of the programs in the File Management Module enables the user to change the pointer to the current sample, composite, or grade label. It should be noted that it is much easier to simply change labels by clicking on the Sample, Composite, and Grade Label buttons at the top of most program menus.

The grid editing program allows the user to display and make direct edits to the surface, rock, and grade models on a block by block basis. These edits may be necessary because the user wants to replace unestimated cell values caused by insufficient modeling data or adjust known anomalous grid values. The grid editing program is not intended to replace carefully selected modeling parameters and sound modeling practices.

The next two programs offered in this module enable the user to process ASCII files containing surface, rock, and grade block model data. The first program produces an ASCII file of the specified grid values, while the second program enables the user to read in grid values from an existing ASCII file.

The program to create a combined plot is a very powerful feature of MicroMODEL. It allows the user to overlay as many as twelve different individual plots into one single output plot In addition, a powerful annotation language is available that allows the user to create custom files for adding north arrows, scale bars, grade range legends, reference lines, etc.

The next three programs in the file manager allow the user to define various class types for the drillholes that are entered in the current project. For example, it may be desirable to run separate statistics for core holes vs. RC holes. By defining and setting drillhole class limits, the user can have precise control over which drillholes are used in almost every MicroMODEL program that accesses the drillhole data base.

The user can write drillhole data points (sample or composite) to an ASCII (text) output file. Information from this file can be used as input to other data analysis programs.

There is a choice under File Manager that allows the user to create an annotation file that can be used with the merge plot program. The annotation file shows colored boxes along with either grade ranges, or rock codes.

The last two choices allow the user to Import or Export multiple 3-D block model files.

2.8 Grade Thickness Modeling Overview

This module contains programs that allow the user to calculate and display grade-thickness (G-T) values for a given rock code, or combination of codes, above a given cutoff. These individual values can be displayed in plan view, or a two-dimensional grid file can be created so that a contour plot of the G-T values can be displayed.

G-T plots are useful for obtaining a general feel for grade continuity and depositional trends for a given rock unit in the deposit.

2.9 Special Tools Overview

This module allows the user to access a number of special add-on programs that were written to perform tasks that could not be handled by the standard set of MicroMODEL programs.

The first tool allows the user to move grid files from one MicroMODEL project to another. The user may only move grids that are of the same sized blocks, and the blocks must have an edge that matches exactly between the old and new project.

The next tool allows the user to report reserve summaries for more complicated cutoff and rock type combinations

The user can adjust the current rock model for a New topography grid (T200)

The user can view the number of different rock types, and a count of these rock codes, from the Sample data base, the Composite data base, or the 3-D Rock Model.

A pair of programs allows the user to write out a rock interval coding file, which contains the drillhole name plus from, to, and rock code for each interval in the sample data base. This file can then be edited with a text editor to revise the rock codes, and the user may then change the rock codes in the data base based on this updated information.

A triangulation program is available that allows the user to assign confidence categories of proven, probable, and possible (or measured, indicated, and inferred), based on the spatial location of bench composite data.

A program is available that will calculate the volume of a waste dump, as defined by a digitized set of contours that tie into the original topography.

A program is available that will check drillhole collar locations and elevations against modeled topo. This program is useful in finding drillholes with collar information that was incorrectly entered into the system.

A program is available that will create an X-Y-Z data file based on a digitized plan view polyline. The program assumes that the line follows a seam outcrop, and the Z value is extracted from the modeled topography file (T200).

2.10 PolyMap Interface Overview

This module allows the user to seamlessly interface between MicroMODEL and PolyMap, a graphical digitizing and pit planning software program.

The user may define slope angles based on rock type that will be used in the PolyMap interactive pit design program. The user may also create a colored block background display for each level (bench) in the model that can be shown by the PolyMap interactive pit design program.

Floating cone contours, or original topography contours, can be exported to PolyMap or to an ASCII file.

The user may prepare the necessary files for running the interactive waste dump design program in PolyMap.

Finally, the user may prepare the necessary files for calculating pit reserves from the interactive open pit design program in PolyMap.

2.11 3D Display Overview

This module allows the user to display data from one or more categories of information. Drillholes, surface grids, 3D block models (grade or rock), and digitized data can all be displayed in three dimensions.

The user may select drillholes and display intervals in 3D. Sample or Composite intervals are selected. Intervals can be color coded by grade label or rock code.

The user may select surface grids and display them in 3D.

The user may select to display the rock model in 3D, or a grade model in 3D. Or, a combination of rock and grade values can be shown.

The user can display digitized data for topography, pits, rock polygons in plan view, or rock polygons in section.

3D display can be done using the built in MicroMODEL viewer, but it is highly recommended that data be transformed into facet files which can then be displayed using ParaView. ParaView is a free program that contains a very powerful set of display tools.

PolyMap.