Q 1. Two sample pits A and B, 25 m apart were drilled to recover samples of an antimony deposit with each pit having an area of influence of 1,250 m2 (with 12.5 m to each side and are located are at a distance of 50m apart on the line of pits – i.e. into the page). Two different types of ore with dissimilar densities were encountered in the pits (see fig): the stibnite (Sb2S3) rich breccia has an in situ density of 2.9 g/cm3, the valentinite (Sb2O3) has an in situ density of 5.6 g/cm3. Calculate the antimony grade and tonnage for this deposit. [10 marks]
Q2. You are required to evaluate a mineral deposit for undertaking mining based on the following information:
- recovery of metal from the ore after processing, smelting, and refining: 92%;
- selling price of the refined metal: $0.95/lb;
- average ore grade: 0.85%;
- all inclusive costs expressed in terms of dollars per tonne of ore: $9.50.
What is your recommendation about this ore prospect? [8 marks]
Q3. In an irregularly spaced chip sampling of a vein the following data are obtained. Calculate the average width and assay value of the deposit. [10 marks]
| Position of sample (m) | 2 | 8 | 10 | 15 | 20 | 30 | 32 |
| Width (cm, into the page) | 75 | 80 | 70 | 105 | 92 | 85 | 50 |
| Assay (g/t) | 15 | 17 | 8 | 11 | 20 | 28 | 12 |
Note: the position is between two successive chips sampling locations, e.g., the first chip sampling was obtained at 2m from the origin and the next one after 8m from the first and so on.
Q4. Estimate the grade of point (inside the square) of a copper deposit using IDW method given the assay values and distances indicated on the figure. Assume r as 2. [5 marks]
Q5. Table below provides U3O8 data (%) for contiguous samples from eight drill holes. Construct a grade profile for any four consecutive drill holes and comment on the continuity of both low and high grades. Assume that individual values are for 2 m samples and that the drill holes are vertical, collared on a flat surface, spaced at 23 m intervals, and numbered consecutively across a mineralized field of flatly dipping sandstone beds. [10 marks]
| No 1 | No 2 | No 3 | No 4 | No 5 | No 6 | No 7 | No 8 |
| 0.79 | 0.09 | 0.1 | 0.62 | 1.13 | 0.08 | 0.12 | 0.16 |
| 0.19 | 0.09 | 0.94 | 0.52 | 1.32 | 0.08 | 0.12 | 0.16 |
| 0.51 | 0.09 | 0.1 | 0.27 | 2.13 | 0 | 1.52 | 0.16 |
| 0.56 | 0.83 | 0.53 | 0.35 | 2.82 | 0.08 | 0.62 | 0.18 |
| 1.26 | 0.16 | 0.1 | 0.28 | 0.62 | 0.08 | 0.12 | 0.42 |
| 1.14 | 0.09 | 0.1 | 0.3 | 2.35 | 0.08 | 0.12 | 0.16 |
| 2.47 | 0.09 | 0.97 | 5.46 | 19.17 | 0.06 | 0.12 | 0.1 |
| 5.86 | 0.82 | 0.45 | 25.47 | 1.81 | 0.08 | 0.12 | 0.45 |
| 26.89 | 1.14 | 3.16 | 0.15 | 9.06 | 0.08 | 0.12 | 0.16 |
| 24.07 | 6.52 | 5.41 | 0.15 | 10.98 | 0.08 | 0.12 | 0.16 |
| 20.59 | 0.24 | 50.43 | 0.15 | 12.05 | 0.08 | 0.12 | 0.16 |
| 10.3 | 0.09 | 11.17 | 0.15 | 3.66 | 2.1 | 0.12 | 0.16 |
| 5.31 | 0.2 | 0.23 | 0.88 | 6.76 | 0.98 | 0.12 | 0.16 |
| 57.94 | 0.09 | 0.2 | 0.99 | 3.37 | 3.53 | 0.12 | 0.16 |
| 26.04 | 0.09 | 0.33 | 0.15 | 0.23 | 9.63 | 0.12 | 0.16 |
| 22.34 | 1.82 | 0.1 | 0.56 | 1.74 | 20.33 | 0.12 | 0.16 |
| 11.52 | 0.09 | 0.19 | 0.53 | 0.21 | 12.11 | 0.12 | 0.16 |
| 42.79 | 0.09 | 0.22 | 4.51 | 0.17 | 4.17 | 0.12 | 0.16 |
| 1.5 | 18.07 | 0.2 | 0.25 | 2.57 | 1.25 | 0.12 | 2.17 |
| 9.89 | 38.72 | 1.14 | 0.15 | 2.68 | 0.08 | 0.12 | 0.23 |
| 2.33 | 27.98 | 1.04 | 0.15 | 0.92 | 0.69 | 0.94 | 0.16 |
| 0.67 | 3.93 | 0.1 | 5 | 1.94 | 0.08 | 5.6 | 0.16 |
| 1.48 | 5.81 | 0.1 | 4.54 | 0.17 | 0.08 | 0.82 | 0.16 |
| 0.15 | 0.65 | 0.1 | 1.64 | 0.17 | 0.19 | 1.4 | 0.16 |
| 0.42 | 0.09 | 0.1 | 0.15 | 0.17 | 0.08 | 6.77 | 0.26 |
| 0.82 | 0.09 | 0.1 | 0.15 | 0.17 | 0.2 | 18.26 | 3.36 |
| 1.48 | 0.09 | 0.1 | 0.15 | 0.17 | 0.3 | 11.14 | 1.43 |
| 4.72 | 0.09 | 0.1 | 0.15 | 0.17 | 0.56 | 4.82 | 5 |
| 6.57 | 0.09 | 0.1 | 0.15 | 0.17 | 0.69 | 3.98 | 17.88 |
| 3.31 | 0.09 | 0.1 | 0.15 | 0.17 | 0.08 | 1.67 | 1.79 |
| 4.13 | 1.43 | 0.25 | 3.04 | 0.17 | 0.08 | 1.42 | 1.36 |
| 11.31 | 0.32 | 0.1 | 9.57 | 0.17 | 0.08 | 0.23 | 11.84 |
| 12.48 | 0.09 | 0.1 | 6.67 | 0.17 | 0.08 | 1.61 | 1.73 |
| 7.68 | 5.19 | 0.1 | 5.95 | 0.17 | 0.08 | 1.58 | 0.23 |
| 12.17 | 1.74 | 0.1 | 0.96 | 0.17 | 0.08 | 1.96 | 0.53 |
| 0.59 | 0.09 | 0.1 | 5.66 | 0.17 | 0.08 | 3.72 | 0.16 |
| 0.15 | 1.52 | 0.57 | 0.58 | 0.17 | 0.08 | 9.16 | 0.16 |
Q6. Calculate the ore reserve estimate of tonnage and grade from the sectional and drill hole analyses (given in the figures below) for an open pit iron ore mine. In the figure below drill hole-log data (in foot) is provided to the left of the drill hole and %Fe to the right. In the sectional view of the figure, the numbers in circles represent the areas in square inches for soil, rock and ore. Use a tonnage factor of 14 ft3/long ton. Express grade values to three significant figures, and record drillhole, section and mine averages. You may assume the scale of diagrams in the cross sections is 1 inch = 50 foot and any other data as you feel necessary to complete the calculation. [20 marks]
Q7. Calculate the values of 10 m composites for each of the following two diamond drill holes (DDH): [10 marks]
| DDH # 1 | Grade (% Cu) | DDH # 2 | Grade (% Cu) | ||
| from | to | from | to | ||
| 27 | 28.5 | 0.74 | 157 | 159 | 1.3 |
| 28.5 | 31.5 | 0.6 | 159 | 161 | 3.3 |
| 31.5 | 41.3 | 0.11 | 161 | 163 | 2.2 |
| 41.3 | 43 | 0.44 | 163 | 165 | 4 |
| 43 | 45 | 0.16 | 165 | 167 | 4.9 |
| 45 | 47 | 0.51 | 167 | 169 | 1.7 |
| 47 | 49.5 | 0.46 | 169 | 171 | 5.9 |
| 49.5 | 53 | 0.23 | 171 | 173 | 1.5 |
