Ore waste
This function classifies intervals down a drill hole as ORE or WASTE according to cutoff and minimum thickness criteria supplied by the user.
To run this function: Choose Database > Analysis > Ore/waste discrimination, or...
Interval table
Enter the name of the database interval table to use, for example geology.
Digging zones
Digging zones allow for the specification of different thicknesses for ore and waste depending on where we are in the drill hole. The determination of digging zones follows different rules for different mining strategies.
The upper digging zone will always be the first band in the drill hole.
Select the mining method to use to determine digging zones:
- None, no digging zones
- Truck & Shovel
- Dragline
The lower digging zone will be the last band in the drill hole.
The lower digging zone will comprise all bands that lie below a given depth.
The middle zone will be all other bands.
Depth to lower zone
If `Dragline' is selected for Digging zones then the depth from the top of the drill hole to the lower digging zone must be entered.
Maximize
Select the property to maximize when resolving thick unclassified drill holes:
- Contained Product
- Ore Volume
- Ore Grade
Minimum thicknesses
Enter the thicknesses which bands must meet or exceed for them to be classified as ORE or WASTE. If digging zones have been specified, thicknesses must be specified for each zone. Example values are Ore: 20, Waste: 10.
Attributes to composite
D-Field
Enter the description field of the resultant string file to which the composited assays will be written.
Attribute
Select a numeric field from the specified table to composite. The first field in this list will be the master attribute whose value relative to cutoff will determine possible ORE and WASTE classifications. Any negative value for this attribute will be treated as zero.
Cutoff
Enter the value which the master attribute value of a band must meet or exceed for that band to be classed as ORE or possible ore. An example value is 5.
Result file
Enter the name (location) of the results file. This name will be used to form two output string files and one note file. For example, if the name is `output' the files will be `output1.str', `output2.str' and `output1.not' respectively.
The formats of the output string files are described below.
Zone selection method
Select the method that you wish to use for defining the samples to be selected for this function:
- NO SELECTION, do not select by geology, and so all samples in a drill hole will be used.
- MULTIPLE ZONES, define the interval by entering one or more geology codes.
- ZONE FROM TO, define the interval by entering the code at the top of the interval and the code at the bottom of the interval.
Missing data method
Select the method that you wish to use for dealing with missing intervals or negative data:
- ASSIGN CONSTANT, the missing or negative samples will be assigned a user specified value.
- WEIGHTED AVERAGE, the missing or negative samples will be assigned a value based on the length weighted average of the sample directly above and the sample directly below. Missing samples at the top and bottom of the hole will be set to the first or last positive sample respectively.
- ARITHMETIC AVERAGE, the missing or negative samples will be assigned a value based on the average of the sample directly above and the sample directly below. Missing samples at the top and bottom of the hole will be set to the first or last positive sample respectively.
Constant value
Enter the value to assign to missing or negative samples, if the Missing data method is specified as `ASSIGN CONSTANT'.
Complete the DRILLHOLE ORE/WASTE DISCRIMINATION form and choose Apply. The VERIFY CREATION OF A FILE form is displayed if the result filenames already exist.
If you chose 'MULTIPLE ZONES' or 'ZONE FROM TO' at the Zone selection method prompt, one of two forms is displayed to allow you to select geological zones to process.
If you chose `NO SELECTION' at the Zone selection method prompt, or have completed the zone selection forms, the DEFINE QUERY CONSTRAINTS form is displayed.
Complete the DEFINE QUERY CONSTRAINTS form and choose Apply to begin the discrimination process.
Processing
The Drillhole Data Ore / Waste Discrimination function classifies drill hole intervals as ORE or WASTE according to cutoff and minimum thickness criteria supplied by the user and applied to drill holes.
The process first identifies all of the bands in the drill hole and classifies those that meet the minimum width criteria as ORE or WASTE.
Unclassified bands that remain will fall into one of three groups:
- A sequence of bands whose aggregate width is less than the minimum and is bounded by layers of the same class.
If the composited grade of the unclassified bands has the same relation to the cutoff as the surrounding layers then the unclassified bands are classified as the same class as those layers.
For example, if the composite grade is less than cutoff and the surrounding layers are WASTE, the unclassified bands are classified as WASTE. Otherwise, if the surrounding layers are ORE, the lowest grade composite that comprises either the layer above with the unclassified bands or the layer below with the unclassified bands is classified as WASTE.
Conversely, if the surrounding layers are WASTE, the highest grade composite that comprises either the layer above with the unclassified bands or the layer below with the unclassified bands is classified as ORE.
- A sequence of bands whose aggregate width is less than the minimum width and are bounded by layers of different classes.
The two upper and two lower bands of the unclassified interval are composited and the composites are classified depending on the composite grades.
- A sequence of bands whose aggregate width is greater than or equal to the minimum.
A window with a width at least that of the minimum is moved over the bands. If the specified objective is to maximise ore volume then the bands in the window whose composite grade is greatest are classified as ORE or WASTE depending on that grade. If the specified objective is to maximise ore grade then the bands in the window whose composite grade is least are classified as ORE or WASTE depending on that grade. If the specified objective is to maximise contained product then the bands in the window whose composite grade differs most from the cutoff grade are classified as ORE or WASTE depending on composite grade.
After an unclassified band is classified, the process is repeated until all bands are classified as ORE or WASTE.
Result
Two string files and a note file will be created as a result of this function.
The first string file produced as a result of this function will have the following format:
- Each string in the file represents a single hole containing a single point at the collar coordinates of the hole.
Each point contains the following information about the hole:
Y, X, Z = coordinates of the point in space D1 Hole ID D2 Total overburden thickness (thickness of WASTE above uppermost ORE layer) D3 Sum of ore thickness D4 Weighted average ore grade D5 Sum of internal waste thickness (excluding any WASTE below lowermost ORE layer) D6 Weighted average internal waste grade D7 onwards represent the weighted averages of the fields specified in the Attributes to composite scrolling region.
The second string file produced as a result of this function will have the following format:
- Each string in the file represents a single hole.
- Each segment of a string represents a contiguous set of ore or waste layers.
- Each point of the segment, except the last point, represents the top of an ore or waste layer from the hole. The last point of each segment represents the bottom of the contiguous set of layers.
- The points representing the tops of ore or waste bands will contain the following information:
| Y, X, Z = coordinates of the point in space | |
| D1 | Hole ID |
| D2 | 'ORE' or 'WASTE' |
| D3 | Width of the band |
| D4 | Depth of the top of the band down the hole |
| D5 | Depth of the bottom of the band down the hole |
| D6 | Blank, for consistency with the Dilution & Reduction function |
| D7 onwards represent the composited values of the fields specified in the Attributes to composite scrolling region. | |
A note file will also be created, with the same name as the output file, but with a `.not' extension. It will contain information on description fields holding input and output, and the constraints used.