There are basically two types of modeling algorithms to represent the grade, volume and location of mineralized rocks. These algorithms can be used to build models manually or by using a computer. Almost all mining models are now built using computer software due to the much increased speed and accuracy of this methodology.

The first modeling algorithm is the two dimensional gridded seam model. In this case a geographic grid is overlain on the orebody. One can think of the grid in terms of parallel lines on a piece of paper with another set of parallel lines at 90 degrees to the first set. The two sets of lines intersect at grid nodes and each grid node is identifiable by a “x” and “y” values or by easting and northing coordinates. The third value of each grid node can represent the surface elevation of the ground at that point, the elevation of the top of a mineralized surface, the specific gravity of the rock, the grade of copper at that geographic position or any other value that is to be modeled.

When a series of grids have been created they can be used to create new grids. Note that the grid nodes for each grid have the same values and so arithmetic operations can be undertaken. For example, if there is a grid for the top of a mineralized surface and a separate grid for the bottom of the mineralized surface then the thickness of the surface can be determined by subtracting the bottom surface grid from the top surface grid. Or if the mining system chosen will result in the loss of .6 meters of the mineralized material then this value can be added to the bottom surface grid to change the elevation of the actual mined lower surface.

The location of the grid nodes is a function of the distribution of the original drill hole and other data. If the data is widely distributed then the grid nodes should not be close together. Otherwise the values for the grid nodes will be based on interpreted data and not original data.

The second modeling algorithm is the three dimensional block model. In this case the mineralization is represented as a block with three and not just two dimensions; “x”, “y” and “z” values or easting, northing and elevation coordinates. This type of algorithm allows many more types of values to be modeled and also permits the use of optimization software to automatically define the most economic mine opening. Values such as “% ore” can be modeled in the blocks. Given that each block is of a defined volume it is relatively easy to calculate the total volume of the orebody. Also economic parameters such as mining cost, metallurgical recovery and mill costs for particular blocks can be modeled.

Using these algorithms to create computer models of mineral occurrences is specialized work and it is always best to leave the job to skilled modelers. As with all things computer it is relatively easy to operate the software but much more difficult to build an accurate model. All good modelers will spend as much time verifying their model as it took to create it. Verification involves printing out the model results and confirming their accuracy by calculating them by hand. Never trust the output of a computer until it has been verified.