How to use Grade Control Polygon Method in Surpac

Champions Blog Post | Mohamed Durand | 

Introducing the Champions Blog series where we feature blogs written by GEOVIA Champions. In this blog post, Mohamed Durand presents a tutorial on using the Grade Control Polygon grade estimation in Surpac.


In an effort to minimize the cost of mining and maximize the recovery of ore, careful Grade Control is an integral and essential part of both open pit and underground mining operations. The grade control module provides you with tools to automate and simplify the more mundane aspects of production control tasks. This article provides solutions for polygon grade estimation for open pit.

This is done using the following methodology:

Step 1: From Database select Extract –> Sample Data

This function allows you to extract sample coordinate data from interval or point attribute tables and create a string file which contains the sample position (Y, X, Z coordinates) and values. The inputs and results of this function will vary depending upon whether the table being processed is a time dependent table or not.




For grade samples extract from drill hole.

Step 2: Generate mining polygon from Block Model

You use this function to display the line of intersection between the perimeter of the blocks of the block model, and the active plane. Usually, you would use this function when the block model is displayed as blocks, and you want to view the line of intersection between the blocks and the active plane.To generate mining polygon, on the Planes panel, click the Block model as polylines button, or, in the Function Chooser, type BLOCK MODEL AS POLYLINES, and press ENTER.


Step 3: From Design select Grade Control –> Open Sample file

This function allows to recall a string file containing interval or point sample grades so grade estimates can be made.



Recall and Display Samples for Grade Control :

  • From Define the sample file to be Use
    ◊ Location = string Extract
    ◊ Assay = samples extract fields D2
    ◊ Thickness = Bench height
    ◊ Specific gravity = density value
    ◊ Sample= tick one box interval or point
    ◊ Tick of the dilute blank or negative samples
  • From Define the description fields for the results
    After grade calculate in the Sting the field D2 = Grade, D3= Mass, D4 = Volume, D5 = Area, D6 = specific gravity, D7 = thickness



Step 4: From Design select Grade Control –> Average grade of polygon or Average length weighted grade

With this function you can estimate the grade inside all closed segments of a string. This function is only appropriate when the samples are Interval type samples. The function works by finding all portions of the samples which are inside the segments of the selected string and then calculating a length weighted average using the grade values of these samples and the length of the samples.



Click on the polygon to calculate average grade.



String 3, Net Grade=12.298, Net Volume=884.353, Net Mass=884.353, Net Area=884.353

Clockwise segment IDs=1, 3 Volume=1044.043, Mass=1044.043, Area=1044.043

Anticlockwise segment IDs=2 Volume=-159.691, Mass=-159.691, Area=-159.691


Position the cursor and select a point on the closed segment within which you wish to estimate the grade. After you have selected the segment the grade estimate is made and a message similar to the above is displayed in the message window.



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When mining companies seek to increase mine productivity, they turn to Dassault Systèmes for technology and services. It is home to world-renowned and award-winning mining solutions and to industry thought leaders who are pushing the boundaries of what’s possible in mining, through the GEOVIA brand. The largest global supplier of mining software, GEOVIA delivers comprehensive solutions in all major mining centers in more than 130 countries at over 4,000 sites.