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Solid Modeling Methods for Mineral Resources “Wireframing”

Modeling processes conducted simultaneously from the beginning of exploration activities will bring advantages of foresight and project control in every aspect, from occupational safety to environmental concerns, from license management to mine planning. By gradually illuminating the ore body in the dark through the models you create, you can develop better operational plans, sustain better exploration activities, and produce more accurate models as a result of better exploration activities. Let’s address solid modeling or in other words “wireframing” methods, which are essential at every step of mining, for professionals at all levels.

In this presentation, solid modeling / wireframing methods related to “explicit‘”(manual) modeling will be provided.

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“We planned and completed the drilling, but we wish we had created this model from the beginning and updated our drilling plans as we progressed.”

Geoscience and mining professionals summarize all their work until they unearth the commodity with a model. Naturally, it is a great advantage for the team conducting the exploration activities to have an idea of how this model is created. Because during the modeling phase, we often hear complaints related to the exploration phase, such as, “Is that how it is?”, “We should have drilled one or two more holes there”, “Let’s immediately catch this adjacent license”, “Are these drillings insufficient for the resource reporting?” …

Without wasting time with the “chicken or the egg” paradox, let’s try to understand solid modeling (wireframing) methods and button the first one of the shirt correctly.

“Everyone has different habits; the method you’re accustomed to is the best method. The important thing is to start from a point.”

a. Why is it necessary?

With the data you obtain, it is necessary to quickly figure out the ore body, its characteristics, and faults as close to reality as possible, and to take solutions before that may cause more costly and time losses in the future to ensure the regular progress of the work.

In addition, this must be completed in advance for the block model from which you will calculate the ore tonnage and grade data to be used in resource reports or notifications in the later stages.

b. Is it difficult for my team to implement or learn?

Initially, the process of being reviewed by experienced professionals on many subjects such as geological and mineralization types, as well as drilling and drill core photographs, is important. For the rest, entry-level geologists can easily continue by updating the models under constant supervision.

c. Can we do without it?

Yes. It is a freedom to choose the execution of drilling programs and the ore body development process, akin to casting a fishing line into the dark, towards an unfamiliar place.

d. What do we gain by progressing with continuous modeling in exploration and operational activities?

You will approach the most realistic position of the mineralization with continuous updates. Updating your ongoing drilling plans according to faults or structural changes in the mass will prevent you from being affected by unexpected structures. It will also allow you to understand the secondary mineralizations as opportunities intersected by drillholes and to update the current plans quickly and follow them.

In summary, even if the drillhole logs are produced from a single hand, they often mean nothing to your exploration team unless seen on the big picture “model.” In fact, we can define modeling in today’s conditions as a unique “audit and work tracking” for exploration activities.

Warning! Adding arbitrary points in any of the solid modeling (wireframing) methods will reduce the reliability of the model, and the smallest detected error will invalidate the entire model and the resource data obtained.

Continue and save the point and linear (string, polyline etc.) elements you will determine for the surfaces you will create in standard colors, which will facilitate your work in updating (e.g., purple for the footwall, pink for the hanging wall).

Be sure to review the “Important Notes and Conclusions” section.

0. Introduction

Modeling starts by choosing the contact surface with the widest planar structure according to the mineralization concept. This surface is generally the footwall contact represented by the exit points in the mineralization intersected by the drillings.

Remember that an area/surface is represented by at least three points. The model of the mass underground is the volume bounded by the merging triangular unit surfaces.

Continue modeling in sequence with the footwall and hanging wall to construct masses parallel to each other, if applicable.

1. Modeling by Creating Surfaces with "Points"

This method is the fastest way to reveal the orientation / trending of mineralization.

To create unit surfaces with sampling, mapping, and structural measurement results, points representing the ore boundaries are determined. By placing points on the coordinates you have data on the drillings or connecting them like a Digital Terrain Model (DTM), you can create triangular surfaces.

When new drillhole data arrives in, you can quickly update your solid model by adding points to the regularly recorded point file. By combining the boundaries of the surfaces in the manner you see fit, you can complete the solid model for the desired sector.

2. Modeling by Drawing "Vertical Sections"

This method shows how important it was to draw drillhole sections by hand frequently in the past.

A vertical section is taken along the drillhole traces or systematic (linear) sampling directions such as line, channel, trench. Points are marked with ore boundaries on the sampling traces (line), and sections are created by connecting them with lines. Using the linear element tool defined as “String, line, polyline” in the 3D design program, contacts/boundaries considered 2D on the existing section are drawn.

If there are compass measurements, if not, the lines are extended by taking into account the direction/dip of the closest part combined with the drillings. The linear elements are automatically combined with commands from the 3D design program to create surfaces. By combining the ends of the surfaces in the manner you see fit, you can complete the solid model for the desired sector.

Measurements (Azi/Dip) recorded at different levels in open pit or underground operations can be used to extend and interpret structural elements to lower or upper levels, which provides useful insights.

3. Modeling by Drawing "Horizontal Sections"

This method is especially used during operations (underground/open pit) through level mapping & grade control sampling.

Horizontal sections are taken at production levels with data or where drillholes intersect contacts. Points are marked with ore boundaries on the samples (line), and horizontal sections are created by connecting them with lines. You can calculate the production grade by making updates with your grade control data or level maps, which are more consistent than your drillings, thus increasing your control over stockpiles.

Using the linear element tool defined as “String, line, polyline” in the 3D design program, contacts considered 2D on the existing section are drawn. If there are measurements, if not, the lines are extended by taking into account the direction/dip of the closest part combined with the drillholes. By combining the ends of the surfaces in the manner you see fit, you can complete the solid model for the desired sector.

 

Measurements (Azi/Dip) recorded at different levels in open pit or underground operations can be used to extend and interpret structural elements to lower or upper levels, which provides useful insights.

After creating the solid model of orebody, you can fill this model with blocks and estimate the desired grade values for each block with geostatistical methods. With the block model you create, you can calculate your resource quantity or the average production grade for a specific area.

4. Important Notes and Conclusions

Modeling should not be started before determining the mineralization concept and type.

Generally, it is thought that the boundary with the rock carrying the mineralization will be clearer due to gravity, and modeling should start from the “footwall” by creating contact surfaces.

You can also create the model by combining different methods in parts.

You do not have to model all the mineralization. Especially in operations, it will be very beneficial for the production departments to quickly model and shed light on specific sectors for the needs of the technical office, short term mine planning.

Detecting and recording the faults developed after mineralization encountered during the exploration phase or operational activities is of critical importance in model updating.

Meticulously archive your model creation/update files and all the data you use digitally.

The model file and folder name must include the date you received the data files for the update, and inform the person who delivered them. This will give you the most accurate information about which sector you updated last during the next updates.

Drillholes planned with experience and frequent updates, intersecting the ore body in the most regular pattern, will allow you to obtain the most efficient model and reduce your extra costs in later stages.

If resource or reserve reporting is to be done, certain standards must be followed from the beginning in exploration activities and sampling processes. Additionally, when it comes to presenting to institutions (stock exchange, etc.) or project sales, remember that your data acquisition standards may be audited for your report to be credible, so you must be meticulous in all matters.

The experience of the professional regarding underground or open pit mining in the relevant mineralization is extremely important for the success of the model. Because it is only possible to follow the consistency of the model with the ore underground by observations during production.

In case any of the following elements are detected on the solid model created for resource reporting or reporting purposes, remember that the reliability of the model will be lost. To mention a few:

  • Observing swelling or shrinking in the solid model due to points added without a reason,
  • Important faults causing slipping or dislocation in the mineralization being ignored and discontinuities not being correctly formed in the solid model,
  • Including drillholes at unacceptable distances according to the type and concept of mineralization in the model as if cutting the same mass,
  • Extending the section created with the drillholes closest to the boundaries of the model outwardly beyond acceptable limits to show the volume as larger,
  • Using drillhole or sample intervals cutting very low grade/quality in the model according to the commodity prices on the day of modeling, inflating the volume,
  • Calculating data by representing ore variety that should be differentiated geometallurgically (sulfide, oxide, transition, etc.) with a single mass, despite being aware.
  • Additionally, calculating parameters without a basis for geostatistical applications while creating and estimating the block model.

In this case, it is very important to question the resource data regarding the amount given or stated in the reports created for project acquisition/sale, management, or public information. Progressing with reputable independent consultants in the process will prevent possible frauds and enable you to make healthier decisions.

As with every design program, especially to prevent problems that will arise during model updates, determine a standard path while creating linear elements, if necessary, take notes aside,

  • Use vertical west-east or north-south sections, horizontal sections with north on top, and progress on these sections in a clockwise direction.
  • Knowing the number of points of the lines you draw while doing solid modeling in either ore modeling or pit planning will be beneficial. Because when design programs combine these lines to create a wireframe, having different numbers of points can cause problems that are perhaps easy to solve but quite troublesome. 
  • Do not be intimidated by setting these standards; you will surely gain the habit with a few trials.
 

Modeling is an art. The professional who will perform this art should have their standard, proceed without hesitation, and not insert other steps in between. Solid modeling (wireframing) is a job that is difficult to start but runs very quickly and easily once started with concentration. If there is no appropriate working environment and a concentrated start, a one-day project can take weeks and result in unrealistic models. Work that progresses quickly, being closed to external influences for as long as possible, is always healthier. Start in one way or another and close your thoughts to external influences.

Subjects discussed in this article may overlap with your mineral exploration, modeling, mining operation and business development issues and may provide solutions for those. However, remember that various factors specific to your business may bring about different challenges. Therefore, seek support from expert consultants to evaluate all data together in order to convert potential into profit most efficiently.

Should you have any questions regarding the articles or consulting services, please don’t hesitate to get in touch with us.

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