Hi,
I've inherited a spreadsheet that is used for tracking how many tonnes of dirt has been mined/removed from a stope (a stope is a void/hole in an underground mine). Stopes are broken up into firings that are blasted at different times. The purpose of this section of the spreadsheet is to track how much of the planned firings have been trucked (depleted), how much of each firing is remaining, and how much of the material that has been trucked is overbreak (overbreak is essentially extra material that has fallen into the stope, making the void larger than planned). The problem is that each firing may not be fully depleted before the next firing is blasted on top of the remaining dirt from the previous firing. At which point the depletions work backwards, e.g. if Firing 1 has 519 tonnes of dirt remaining (undepleted) when Firing 2 is dropped on top of the remains of Firing 1, then once Firing 2 has been fully depleted depletion will resume of Firing 1. This process gets rather complex when there are multiple firings in a stope and each firing isn't depleted before the next firing is blasted. I have attached an example that contains 9 firings. The attached sheet has three worksheets, one entitled "Original" which is the sheet as I inherited it and one entitled "New" which is where I've got to with my changes, and then one entitled "Test" in which I was playing with an idea.
The sheet, as I inherited it, has these depletions as a manual process. The cells in column J contain the following formula:
=IF(D6="","",(D6))-G7-G9-249-270
As you can see by the formula the user has to manually add in each depletion. This process is done for each firing until each firing is fully depleted (i.e. =0). This can also be evidenced by the Overbreak total in column D4 which contains the following formula:
=360+490+G59+G61+812+G137+G139+G141+G145+G147+G149+986
The only way the amount of overbreak attributed to each days trucking is recorded is in the "Comments" column.
If a firing has been depleted to 0 but more dirt is still coming out the user has to attribute the extra dirt to previous firings that haven't been fully depleted or overbreak. The user then has to calculate the weighted grade of the dirt trucked that day using the "Calculator", which is essentially a sumproduct of the amounts of each dirt attributed to each firing. This is the grade that is then entered into Column H for that day.
What I'm trying to do is automate this whole process so that all the user needs to do is input the trucking tonnes in column G.
So far I've used the following formula in column J for the depletions:
=IF(C4="","",IFERROR(IF(D4-SUM(G5:INDEX(C5:$G$420,MATCH("*",C5:$C$420,0),5))<=0,0,D4-SUM(G5:INDEX(C5:$G$420,MATCH("*",C5:$C$420,0),5))),IF(D4-SUM(G5:$G$420)<=0,0,D4-SUM(G5:$G$420))))
And I've used this formula in column M for the overbreak:
=IF(ISBLANK(C4),"",IFERROR(IF(D4-SUM(G5:INDEX(C5:$G$420,MATCH("*",C5:$C$420,0),5))<=0,SUM(G5:INDEX(C5:$G$420,MATCH("*",C5:$C$420,0),5))-D4,""),IF(SUM(G5:$G$420)-D4<=0,"",SUM(G5:$G$420)-D4)))
The problem with this approach is that the Depletion and Overbreak summaries don't balance properly.
I had a bit of a play around using some interim working columns, which I've included in the "Test" worksheet, in which I could get the Depletion to balance out correctly...but I couldn't quite work out the formula to use for the overbreak in column S.
Even with a working formula in column S I still require a way to automate the calculation of the grades in columns H, column N and column T that would normally be done manually each day using the "Calculator".
If anyone has a solution to my issue I would be greatly appreciative!
Thanks,
Daniel
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