Underground Mine Reserves
This command calculates quantities and qualities from drillholes
or predefined grid or block models. Key strata are intended to be
the target ore, and non-key strata are intended to be the
overburden, interburden and parting strata. Within the drillholes
or Geologic Model file, each strata has a field that specifies
whether the strata is key or non-key. There are many options
for reserve calculation and they are detailed in order of
appearance below.
- Modeling Method: The
reserves can be generated on-the-fly from the selected drillholes
or read from stored grid files put into a Geologic Model file. The
on-the-fly modeling method can be either Triangulation, Inverse
Distance, Kriging, Polynomial or Linear Least Squares. An
explanation of these different methods is found under Make Strata
Grid Files. The stored grid file method is the Geologic Model
option. The Geologic Model method uses prepared grid files that
represent the bottom elevation or thickness and quality attributes
(i.e. BTU) of the strata. The grid files associated with each
strata and the ground surface are set in the Define Geologic Model
command under Drillhole.
- Use Triangulation
Subdivision: This option only applies to the modeling
methods of Triangulation and Polynomial. It subdivides the
triangles to create smoother surfaces and ensure that contours do
not cross.
- Use Global Trend
Extrapolation: This also applies only to Triangulation and
Polynomial. This option finds the average slope and direction of
the existing data and applies this slope to extrapolating where
there is not surface data. .
- Make Thickness Grids:
Turning this option on will create thickness grids of the selected
or all strata. It will prompt to create an overburden thickness
grid, a key thickness grid and a key tons grid (tons/sq ft. or
m).
- Output Grids for Each
Strata: Turning this option on will create grid files for
the bottom of each strata found in the drillholes. Each grid needs
to be named separately. The command Make Strata Grids is a better
way to create these grids.
- Report Areas On One
Row: This option puts all the strata quantities and
qualities for each inclusion polyline on one row. This format is
best suited for only a few strata and for printing landscape on a
page. If it is not selected, then each strata will appear on a
separate row.
- Use Property
Boundaries: Property boundaries can be used to break up the
reserve by owner and property. The commands for laying out property
boundaries are in the Boundary menu. Essentially, property
boundaries are closed polylines with owner and property ID names.
The property polylines do not need to be clipped with the
calculation inclusion perimeter or pit polylines. The program will
internally clip the properties with the calculation areas and
report the amounts by property within each pit area. If a pit or
inclusion polyline is not covered by a property, the property name
used for these quantities is "unknown". To activate property
boundaries, click on the Use Property Boundaries toggle and the
program will search and find them automatically.
- Calculate Strata
Qualities: This
toggle will report the average qualities for strata attributes such
as BTU and sulfur. Otherwise the program skips calculating
qualities to save time. Besides reporting the qualities for each
strata individually, the program can also report the total averaged
qualities. By default, the qualities are weight averaged by tons
which are calculated by using the strata volume and density.
- Recovery Percent: This
window defines the percentage of Key strata volume that was
recovered in mining and to include in the volume and strip ratio
reporting. The non-recovered key strata is added to the NonKey
volume. The recovery percent in the Reserves dialog applies to all
the Key strata. Enter in as 100 or 95.4 or 92, etc.
- Use Strata Definitions (for
Recovery): To have different recoveries for each Key strata,
use Define Strata to create a strata definition for each Key strata
with the appropriate recovery percent. Then run Surface Mine
Reserves and click on Use Strata Definitions.
- Use Attribute (for Recovery):
Another recovery method is to
have a strata attribute for recovery. This allows for different
recovery percents at different drillholes. Then the recovery is
modeled for the area. The name of the recovery attribute is
specified in the dialog. This attribute will need to appear in the
drillholes for modeling on the fly, or in the Geologic Model as a strata attribute, with
the name spelled as it appears in the Name window to the
right.
- Name (Attribute): This
is the name of the recovery attribute that will be referenced when
using the Use Attribute option for recovery percentage.
- Min Key Thickness To
Use: This
option adds key strata to the nonkey strata above, in areas that
have thickness less than the specified minimum thickness. Also
areas with thickness less than the minimum are not counted in the
reported strata area.
- Min Minable Parting
Thickness: This setting will add the non-key parting
quantities with the key quantities when the non-key parting
thickness is less than the specified amount. For example, if the
Min Minable Parting is set to 0.5, then a non-key strata between
two key strata would be combined with the key in areas where the
non-key thickness is less than 0.5 feet. In areas where the
thickness is greater than 0.5, the non-key quantities are not
adjusted. Combining the non-key quantities to the key will add to
the total key tons and affect the strip ratio. If the non-key
strata has qualities (i.e. ASH, Sulfur), then these non-key
qualities will be composited by nonkey tons with the key tons for
the portion of non-key that is less than the minimum parting. This
will dilute the key qualities.
- Non-Key Thickness To Add To
Key: Above Key/Below Key: These fields allow you to specify
the amount of non-key thickness above and/or below the key strata
that will be combined with the key (roof and floor dilution) This
amount will be taken from the non-key quantities and added to the
key. Similar to the Min Minable Parting Thickness, the non-key
quantities will increase the total key tons which affects the strip
ratio and key volume mined. Also any non-key strata qualities will
be combined by thickness, weighted by NonKey density, and added to
the key which dilutes the key qualities. For example, if you
estimate that 0.25 feet on average of the overburden is taken with
the coal, then you could set the Non-Key to Add to Key for Above to
0.25.
- Which Strata To
Include...: This determines what will be calculated for the
reserve. If All is chosen, then all strata in the drillholes or
Geologic Model file will be calculated and reported. If Selected is
chosen, then the next window to appear is where one or multiple
strata can be selected. This can be used for multiple reserve runs,
selecting different strata to represent each bench.
- Use Named Pit Areas:
The area for calculating quantities defaults to the limits of the
selected surface entities and drillholes if no inclusion perimeters
are selected. To control the calculation area, multiple closed
polylines for areas to include and/or exclude can be selected. An
unnamed pit polyline will limit the area of calculations. Also,
areas can be labeled with site and pit names (i.e. Site 1, Pits
101, 102, ...). Surface Mine Reserves will then calculate the strip
ratios and volumes for each site and pit area. To use site and pit
names, there are several commands for creating named pit polylines
in the Boundary menu of Underground Mining. If this is selected,
then it will look just for named pit polylines, ignoring anything
else. The Specify Names button will name the polylines from inside
this command if they are not already named using commands found
under Boundary.
The Report Formatter Options dialog is the final step of the
Underground Reserves routine. It is documented elsewhere in the
manual for more details on its operation.
Prompts
Underground Mine Reserves dialog
Select surface entities and at least 3 drillholes. (Unless
using a Geologic Model.)
Select objects: select the drillhole symbols and surface
entities Surface entities can include points, lines, and
polylines.
Select the Inclusion perimeter polylines and ENTER for none:
Select objects: select the polylines or named pit
polylines The area within these polylines will be included in
the calculations. They must be closed polylines.
Select the Exclusion perimeter polylines and ENTER for none:
Select objects: select the polylines The area within
these polylines will be excluded from the calculations. They must
be closed polylines.
Make Grid File Set grid resolution
Triangulating points ... 49
Pass> 6 NULL Z values left> 0
Processing cell 2500 ...
Finished strata Y2
The above four steps are repeated for each strata.
Report Formatter
Pulldown Menu Location: StrataCalc in Advanced Mining
Keyboard Command: reserves