1. Slopes in MSOPT Calculations ©2012 Dr B. C. Paul Note – These Slides are based on and include screen shots from the program MineSight by Mintec. Credit is given to Mintec for development of the program and the screen interfaces seen in the screen shots.

2. Slope Options in MSOPT MSOPT generates smooth open pit shells or surfaces which can be seen in model views. The slope of those shells is controlled by options set in the MSOPT interface MSOPT allows four options –Constant slope – the slope is the same for all directions and rock types –Slope by Azimuth – the slope changes by direction –Complex Slope – the slope changes according to the type of rock it passes through –Complex Slope by Azimuth – the slope changes both by direction and rock type

3. Slope by Azimuth What causes changes in slope by Azimuth –The most common cause is joints or fracture patterns that dip at shallow or moderate angles Pit Slope Fracture Pattern Note – that the pit slope is exposing “day-lighting” the fracture pattern, allowing Whole sections of the mine slope to break loose along the fracture and slide in

4. Note that on the other side of the Pit the Joints have no effect Although the pit slope cuts these fractures there is No chance for sides of the pit to break along these Fractures and slide in.

5. How MineSight Addresses the Problem On the pit slope angle panel in MSOPT pick the radio button for slope by Azimuth Note that this causes another panel to become active and you must now fill in additional Info. (If you do not the routine will run constant slope at the minimum slope specified On this panel).

6. On the Next Panel Let us suppose that we have a fracture pattern that has a direct north south strike And dips 36 degrees to the west. Let us suppose that daylighting this fracture Pattern will bring in the side of the pit. Thus the west facing pit slope will need to Be no steeper than about 35 degrees while the east facing slope could still be at Maximum steepness – say 65 degrees

7. A Plan View of Our Pit and Joints N Note on this Side of the pit From an Azimuth of 180 to 360 Degrees the Fractures will Dip into the Face and not Limit the slope At azimuth 90 the slope Must not exceed about 35 The maximum steepness now Moves up incrementally around The pit. (Exact sustainable slopes can be obtained Using a stereonet)

8. An interesting Note The pit wall running parallel to the strike of the fracture will see the full dip of the fracture –What happens if the dip of the fracture is greater than the pit slope? The fracture might not be daylighted at all

9. As We Move Around the Pit The Apparent slope will decline Rise Run Angle

10. Impact Slopes hitting the fracture plane at an angle will have even a shallower slope to contend with Eventually the apparent slope will drop below the angle of internal friction on the fracture and the fracture will cease to be a daylighted threat.

11. Entering Data into MSOPT Let us suppose that from an azimuth of 70 to 110 we determine we should keep The slope at 35 degrees. We enter the point at which our azimuth limit begins and then the corresponding Maximum slope.

12. Moving Round the Circle A rule of thumb is to move around the circle in no more than 10 degree increments. Suppose from 40 to 70 and 110 to 140 azimuth we want no more than 45 degrees. We enter the lower limit azimuth for each slope zone and the corresponding slope.

13. More Circle Movement Suppose from 10 to 40 and 140 to 170 azimuth we limit to 55 degree slopes. That’s easy for the 10 to 40, but we are out of space for the 140 to 170. To fix this problem click on the add button.

14. Another Azimuth Box Appears and We Fill In Our Data

15. Finishing Up Let us suppose the rest of the azimuths allow the full 65 degree slope.

16. Looking at the Main Slide So what does this minimum slope do? If the constant slope option is selected it controls the slope in all directions. In other cases it identifies the blocks that MSOPT will do calculations for when it Projects slopes. You can speed things up by limiting calculations for blocks that Will never be in a cone, but the routine may foul up if it need to consider a block That has been excluded by the limiting cone.

17. Another Possibility Some rock types will hold a steeper slope than others. It may be possible (even likely) that our pit will pass through different types of rock –Or that later alteration of the rock during mineralization has influenced the sustainable slope.

18. To Understand Why We Do Things We Need to Know How MSOPT Works One way to project a cone up at variable slope is to have the routine check the code in each block as the slope is projected up through the block. –This is very straight forward –And as long as taking all day and all night to run the algorithm is ok it works fine.

19. For Those Who Want Faster Results Consider this Take an entire column of blocks and code The point where a slope change occurs Into a model surface

20. Now As A Slope Projects Up – Periodically Look Down at the First Surface Below for a Slope Code The slope is Projecting up Periodically it looks down at the slope code Surface right below it to select the slope to Continue projecting up at. Result – A Faster Executing Routine

21. Of Course We Need to Set Those Surfaces From MineSight Compass Select MSPTSP (the procedure to extract the slope Code from a block model)

22. First We Need to Pick the Surface and Block Model Files Pick your block model that contains what ever characteristic you will use to Control your maximum slope. (Its probably your main block model – what ever You chose to name it in your project) Next pick the surface file (file 13) you will use. Since MineSight Economic Planner Relies on a special file 13 that contains variables it needs you probably have more Than one file 13. You need the one optimized for Economic Planner.

23. Next Pick Which Variable in Your Block Model Will Control Slope

24. You Can Always Drop Down a List of Variables in Your Block Model Our slope controlling Variable could be the Rock type It could also be the alteration In this case we are going To set slope by alteration Type.

25. The Last Item Is Our Work Area If we do not need to Do coding from the Entire block model We can speed things Up by only Considering the Columns, Rows, And Levels in our Block Model where Something is happening For smaller projects calculating over the entire block model is common

26. Move On To Our Last Panel Click on the Panel we want To go to.

27. All We Need to Do Here Is Set Our Run File Extensions Each routine we run in MineSight saves a record of run variables and result outputs. We can organize the names of these files and store them as documentation of Exactly what we did. (Computers enable us to do a lot of different things quickly, But for legal and professional reasons we need to be able to explain how we did Things or reached certain conclusions. MineSight helps you keep this legal And professional paper trail).

28. Now Run Your Routine Click on the File tab to drop down a menu Highlight and click on Run Procedure.

29. Now Lets Use Our Complex Slopes in MSOPT On Pit Slope Angle Options – click on the radio button for complex slopes

30. Match the Maximum Slope to Each Rock or Alteration Type Remember you have given a number to each rock or alteration type. In our case it Is alterations types numbered 1 to 6 (MineSight allows numbers up to 50)

31. Looking at the Remaining Panel Entries Your specialized file 13 has data spaces for up to 4 slope break surfaces. You can Control how many of those surfaces you will use. Almost always you will allow the Program to use all 4.

32. As the Slope Is Projected Up You Can Choose How the Slope Will Be Projected On. The way we have chosen is the floating ray I have described. There is an option for looking in down to the slope code surface every time You enter a new block but it will run much slower.

33. Complex Slopes Use An Existing Pit Shell to Limit Search Area This means for a floating ray it needs to know how big the pit might be. As a Practical mater this usually means you run an ultimate pit at a constant slope set As low as the slope will be at any point while boosting the metal price to get a big Pit. This pit then tells the program never to project cone rays outside of an Ultimate pit. (Again saves on computation).

34. Whats this Extended Ray Option? Normal Pit Juicy ore blocks on the side Above the regular pit level An extending ray keeps Searching for more ore Even after the ray first Breaks into air.

35. Whats Create Floating Ray for Every Bench? It means every time the ray reaches a bench level it automatically stops and Rechecks the slope to project up with. Again it improves absolute accuracy At considerable cost to speed.

36. What Happens with Both Rock Type and Slope Direction Control Slope? For a complex slope by azimuth you enter first the type of rock, then a direction, and Then the maximum slope. You keep on adding till you have covered all azimuth Directions for each rock type. (Just like our other cases but now you deal with Both at once).