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Assignment #6 Assignment #6 Stripping Ratios by Stripping Ratios by Planimeter Planimeter ©Dr. B. C. Paul Summer 2003 ©Dr. B. C. Paul Summer 2003

Assignment #6 Stripping Ratios by Planimeter ©Dr. B. C. Paul Summer 2003

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Page 1: Assignment #6 Stripping Ratios by Planimeter ©Dr. B. C. Paul Summer 2003

Assignment #6 Stripping Assignment #6 Stripping Ratios by PlanimeterRatios by Planimeter

©Dr. B. C. Paul Summer 2003©Dr. B. C. Paul Summer 2003

Page 2: Assignment #6 Stripping Ratios by Planimeter ©Dr. B. C. Paul Summer 2003

AssignmentAssignment

• Stripping Ratios can be done by average Stripping Ratios can be done by average end area on pit cross sectionsend area on pit cross sections

• You will find an autocad file showing 4 You will find an autocad file showing 4 cross sectionscross sections

• Determine the area of the overburden in Determine the area of the overburden in each cross sectioneach cross section– Assume each cross section covers 400 feetAssume each cross section covers 400 feet– Get the volume of overburden in each cross Get the volume of overburden in each cross

sectionsection

Page 3: Assignment #6 Stripping Ratios by Planimeter ©Dr. B. C. Paul Summer 2003

More AssignmentMore Assignment

• Use autocad to get the area of the mined Use autocad to get the area of the mined ore body in the 4 cross sectionsore body in the 4 cross sections– Assume each cross-section covers 400 feetAssume each cross-section covers 400 feet– Get the total volume of oreGet the total volume of ore

• Using the volume of waste and the volume Using the volume of waste and the volume of ore, calculate the volumetric stripping of ore, calculate the volumetric stripping ratio for the pitratio for the pit

• Assuming ore weight 4900 lbs/cubic yard Assuming ore weight 4900 lbs/cubic yard and overburden is 4100 lbs/cubic yard and overburden is 4100 lbs/cubic yard calculate the weight based SR for the pitcalculate the weight based SR for the pit

Page 4: Assignment #6 Stripping Ratios by Planimeter ©Dr. B. C. Paul Summer 2003

Get Ready to Load Your FileGet Ready to Load Your File• You will need to get an e-mailed or disk You will need to get an e-mailed or disk

copy of the autocad filecopy of the autocad file

Go to File to loadThe needed drawing

Page 5: Assignment #6 Stripping Ratios by Planimeter ©Dr. B. C. Paul Summer 2003

Using AutocadUsing AutocadYou are viewing Cross-Section 1

The LayerIs turnedon

Page 6: Assignment #6 Stripping Ratios by Planimeter ©Dr. B. C. Paul Summer 2003

Enter the Area CommandEnter the Area Command

Note that theWord “Area”Has beenTyped in

Page 7: Assignment #6 Stripping Ratios by Planimeter ©Dr. B. C. Paul Summer 2003

Specify that you want the area Specify that you want the area of an Object (in this case the of an Object (in this case the hatched Overburden)hatched Overburden)

After pushing EnterAfter the AreaCommand, theProgram is askingFor you to traceSomething or selectAn object.

You specify anObject by typing “o”

Page 8: Assignment #6 Stripping Ratios by Planimeter ©Dr. B. C. Paul Summer 2003

You Select Your ObjectYou Select Your ObjectI placed the curserOn the edge of theOverburden.

The MachineImmediately spitsOut the area of theoverburden

Page 9: Assignment #6 Stripping Ratios by Planimeter ©Dr. B. C. Paul Summer 2003

Issue the Area Command and Issue the Area Command and Select the OreSelect the Ore

Curser

Answer

Page 10: Assignment #6 Stripping Ratios by Planimeter ©Dr. B. C. Paul Summer 2003

Go to Cross Section #2Go to Cross Section #2Note that a pull downMenu is activated.

The light bulbs by theThree otherCross-sections are dark(meaning they are notOn for viewing)

Page 11: Assignment #6 Stripping Ratios by Planimeter ©Dr. B. C. Paul Summer 2003

Click on the light bulbsClick on the light bulbsClick the Cross Section #1Light bulb to turn it off

Now click the CrossSection #2 light bulb to turnIt on.

Page 12: Assignment #6 Stripping Ratios by Planimeter ©Dr. B. C. Paul Summer 2003

The Drawing Switches to the The Drawing Switches to the Second Cross SectionSecond Cross Section

Page 13: Assignment #6 Stripping Ratios by Planimeter ©Dr. B. C. Paul Summer 2003

Use this Procedure to Obtain Use this Procedure to Obtain Areas for Each Layer in TurnAreas for Each Layer in Turn

• You now have the areas of Ore and You now have the areas of Ore and Overburden in each of the 4 cross-sectionsOverburden in each of the 4 cross-sections

• We are assuming equal weight for each We are assuming equal weight for each cross section so simply take the average cross section so simply take the average overburden and average ore areasoverburden and average ore areas

• Multiply the average ore or overburden area Multiply the average ore or overburden area by 1600 ft (400 ft * 4 sections) to get a by 1600 ft (400 ft * 4 sections) to get a volume for ore and a volume for overburdenvolume for ore and a volume for overburden– Do note that the drawing units are in feet so your Do note that the drawing units are in feet so your

answer is in cubic feetanswer is in cubic feet

Page 14: Assignment #6 Stripping Ratios by Planimeter ©Dr. B. C. Paul Summer 2003

Getting Volumetric Stripping Getting Volumetric Stripping RatioRatio

• Volumetric Stripping Ratio is just the Volumetric Stripping Ratio is just the Overburden volume divided by the ore Overburden volume divided by the ore volumevolume

• To get the weight based stripping ratio To get the weight based stripping ratio you must convert cubic feet to cubic you must convert cubic feet to cubic yards (or convert you densities which yards (or convert you densities which are expressed in lbs per cubic yard)are expressed in lbs per cubic yard)– There are 27 cubic feet in a cubic yardThere are 27 cubic feet in a cubic yard