Clean Ton Per Foot of Advance (CTPF) map in Coal Reserve Study

By admin • June 7, 2008

Well, I am sure you all are very efficient in mapping Total Coal or Total Seam of coal. Sometimes however a different isopatch is required for some coal reserve study. Here I will just give you a small guide of making Clean Ton Per Foot of 25 feet wide entry Advance. You can change the width of the entry if you know you are using a different width of entry in the coal mine. To map CTPF for a “section” just figure out how many entries are there in a section and multiply that with the CTPF value you get for single entry. It is just simple mathematics and basic unit conversion.

Say, you have a 5 feet coal seam in one of the drill holes in your reserve area. You need to convert 5 feet of coal seam to Clean Tons Per Foot of entry advance.

Deep Mine Workings

Seam Height (feet) x Weidht of Entry (feet) x 0.04048471 (Tons/Cubic Feet) x Recovery (%)= CTPF in Feet per Entry
Example:
Coal seam= 5 Feet
Weidth of Entry=25 Feet
Recovery = 95% (Not Mining Recovery, rather estimated visual recovery)
5×25x0.04048471x.95=4.82 CTPF of 25 feet entry advance

Note: You many or may not use the recovery in your calculation. This is not the mining recovery, which is in most cases 50% for deep coal mine and about 90% for surface mining methods. For you coal reserve estimation you need to use the Mining recovery number in your calculations.

How to get conversion factor?
If you convert that to Tons/Acre-inch, use the formula:
1. Convert to Tons/Acre Inch

Tons/Acre-inch= Specific Gravity x 113.325
Example1: for a coal seam with Specific Gravity=1.3
1.3 x 113.325=147.3225 Tons/Acre inch

Example 2: for coal seam with Specific Gravity = 1.47 (Anthracite Coal)
1.47 x 113.325= 166.58 Tons/Acre-inch

2. Convert Acre-inch to Acre Feet (1 acre inch=0.0833333333)

Using example 1:
147 Tons/Acre-inch= (147/0.08333333) Tons/Acre-Foot = 1767.87 Tons/Acre-foot

3. Convert Tons/Acre Foot to Tons/cubic-foot to use the conversion factor you need for your coal seam (1 acre = 43560 square feet)

So, using the above example,
1767.87 Tons/Acre-foot = 1767.87/43560 (Cubic Foot)=0.04058471 Cubic-foot

Note: So, it is just a matter of unit conversion to get your CTPF map. Many times the client may ask for a CTPF map. Remember to get required information on weidth of entry and coal specific gravity. Calculate CTPF values for each drill hole location for the particular coal seam you are interested in. Then simply contour either by hand or using some simple comtouring program.

Tips: If you have prepared a Total Coal contour map (NOT Total Seam map), your CTPF map should be very similar to that one. Think WHY and let me know if you have found the answer.

References: I am just providing two very important references that you can use to cross check some of your calculations. They are also very useful if you are working with a coal reserve study.

Categories: Coal, Underground Mine
Tags: Clean Tons, Coal, Contour Map, CTPF, Deep Mine, Maps, Reserve

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Coal Geology

Coal, Mining, Permitting, Gallery, Consultancy, Geochemistry, Reserve, Resource