Calculate borehole composites- Example 2

This example describes how borehole composites are calculated using average weighting for gold.

This page discusses:

Data given:

The following data is given:

Table 1. Input for compositing
Depth from Depth to gold recovery sg
0.0 1.0 1.00 50 1
1.0 2.5 2.00 -1 -1
2.5 5.0 3.00 20 3
5.0 9.0 4.00 100 2
9.0 12.0 5.00 60 2
12.0 13.0 -1.00 -1 -1
13.0 15.0 7.00 100 2

Calculating composites from 0 to 2

Since Recovery and SG are < 0.0 for the interval from 1 to 2.5, the "default values" of 100 for Recovery and 1.00 for SG are used.

Table 2. Weights
Depth from Depth to Sample length × recovery × sg Weight
0 1 1 × 50 × 1 50
1 2 1 × 100 × 1 100
Composite value: 150

Table 3. Grade
Depth from Depth to Sample value × weight proportion Weight
0 1 1.00 × (50/150) 0.333
1 2 2.00 × (100/150) 1.333
Composite value: 1.666

Table 4. Recovery
Depth from Depth to Sample value × weight proportion Weight
0 1 50 × (1/2) 25
1 2 100 × (1/2) 50
Composite value: 75

Although 100% of the composite interval is represented, the composite is not saved because the Average recovery is 75%, which is less than the limit of 80%.

Calculating composites from 2 to 4

Since Recovery and SG are < 0.0 for the interval from 1 to 2.5, the "default values" of 100 for Recovery and 1.00 for SG are used.

Table 5. Weights
Depth from Depth to Sample length × recovery × sg Weight
2.0 2.5 0.5 × 100 × 1 50
2.5 4.0 1.5 × 20 × 3 90
Composite value: 140

Table 6. Grade
Depth from Depth to Sample value × Interval proportion Weighted value
2.0 2.5 2.00 × (50/140) 0.714
2.5 4.0 3.00 × (90/140) 1.929
Composite value 2.643

Table 7. Recovery
Depth from Depth to Sample value × weight proportion Weight
2.0 2.5 100 × (0.5/2) 25
2.5 4.0 20 × (1.5/2) 15
Composite value: 40

Although 100% of the composite interval is represented, the composite is not saved because the Average recovery is 40%, which is less than the limit of 80%.

Calculating composites from 4 to 6

Since Recovery and SG are < 0.0 for the interval from 1 to 2.5, the "default values" of 100 for Recovery and 1.00 for SG are used.

Table 8. Weights
Depth from Depth to Sample length × recovery × sg Weight
4.0 5.0 1 × 20 × 3 60
5.0 6.0 1 × 100 × 2 200
Composite value: 260

Table 9. Grade
Depth from Depth to Sample value × Interval proportion Weighted value
4.0 5.0 3.00 × (60/260) 0.692
5.0 6.0 4.00 × (200/260) 3.077
Composite value 3.769

Table 10. Recovery
Depth from Depth to Sample value × weight proportion Weight
4.0 5.0 20 × (1/2) 10
5.0 6.0 100 × (1/2) 50
Composite value: 60

Although 100% of the composite interval is represented, the composite is not saved because the Average recovery is 60%, which is less than the limit of 80%.

Calculating composites from 6 to 8

Table 11. Weights
Depth from Depth to Sample length × recovery × sg Weight
6.0 8.0 2 × 100 × 1 200
Composite value: 200

Table 12. Grade
Depth from Depth to Sample value × Interval proportion Weighted value
6.0 8.0 4.00 × (200/200) 4.000
Composite value 4.000

Table 13. Recovery
Depth from Depth to Sample value × weight proportion Weight
6.0 8.0 100 × (2/2) 100
Composite value: 100

Since 100% of the composite interval is represented, and the recovery is 100% (greater than the Include limit of 80%), the composite is saved.

Calculating composites from 8 to 10

Table 14. Weights
Depth from Depth to Sample length × recovery × sg Weight
8.0 9.0 1 × 100 × 2 200
9.0 10.0 1 × 60 × 2 120
Composite value: 320

Table 15. Grade
Depth from Depth to Sample value × Interval proportion Weighted value
8.0 9.0 4.00 × (200/320) 2.50
9.0 10.0 5.00 × (120/320) 1.875
Composite value 4.375

Table 16. Recovery
Depth from Depth to Sample value × weight proportion Weight
8.0 9.0 100 × (1/2) 50
9.0 10.0 60 × (1/2) 30
Composite value: 80

Since 100% of the sample interval is represented, and the recovery is 80% (equal to the Include limit of 80%), the composite is saved.

Calculating composites from 10 to 12

Table 17. Weights
Depth from Depth to Sample length × recovery × sg Weight
10.0 12.0 2 × 60 × 2 120
Composite value: 120

Table 18. Grade
Depth from Depth to Sample value × Interval proportion Weighted value
10.0 12.0 5.00 × (120/120) 5.000
Composite value 5.000

Table 19. Recovery
Depth from Depth to Sample value × weight proportion Weight
10.0 12.0 60 × (2/2) 60
Composite value: 60

Although 100% of the composite interval is represented, the composite is not saved because the Average recovery is 60%, which is less than the limit of 80%.

Calculating composites from 12 to 14

Since Treat negative values as zero is cleared, the missing interval from 12 to 13 (gold = -1) is not included in the calculation. If Treat negative values as zero was selected, the interval from 12 to 13 would have been included, and the sample value would have been 0 (zero).

Since recovery = -1 and sg = -1 for the interval from 12 to 13, the Default values of 100 for recovery and 1.00 for sg are used.

Table 20. Weights
Depth from Depth to Sample length × recovery × sg Weight
12.0 13.0 0 × 100 × 1 0
13.0 14.0 1 × 100 × 2 200
Composite value: 200

Table 21. Grade
Depth from Depth to Sample value × Interval proportion Weighted value
12.0 13.0 -1.00 × (0/200) 0.00
13.0 14.0 7.00 × (200/200) 7.00
Composite value 7.00

Table 22. Recovery
Depth from Depth to Sample value × weight proportion Weight
12.0 13.0 100 × (1/2) 50
13.0 14.0 100 × (1/2) 50
Composite value: 100

Although the average recovery is 100%, only 50% of the composite interval is represented, which is less than the value of Minimum percentage of sample to be included (75%), so the composite is not saved.

Calculating composites from 14 to 16

Since the end of the borehole is 15, the missing interval from 15 to 16 is not included in the calculation, regardless of whether Treat negative values as zero is selected or not.

Table 23. Weights
Depth from Depth to Sample length × recovery × sg Weight
14.0 15.0 1 × 100 × 2 200
15.0 16.0 Interval not included in calculation 0
Composite value: 200

Table 24. Grade
Depth from Depth to Sample value × Interval proportion Weighted value
14.0 15.0 7.00 × (200/200) 7.00
15.0 16.0 Interval not included in calculation 0.00
Composite value 7.00

Table 25. Recovery
Depth from Depth to Sample value × weight proportion Weight
14.0 15.0 100 × (1/2) 50
15.0 16.0 100 × (1/2) 50
Average recovery: 100

Although the average recovery is 100%, only 50% of the composite interval is represented, which is less than the value of Minimum percentage of sample to be included (75%), so the composite is not saved.

Table 26. Values after compositing
Depth from Depth to Composited gold
6 8 4.00
8 10 4.38