Underground Mine Reserves
Function
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 PreCalc 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 PreCalc 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
Pre-Calculated option. The Pre-Calculated modeling 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 Pre-Calculated
Grids 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 PreCalc
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 PreCalc 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 Advanced 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 PreCalc.)
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
File Names: \lsp\mtntop.lsp, \lsp\makegrid.arx, \lsp\makegrid.dcl