Question

15,600 tpd. Reserves stand at 7.2
million ounces grading 5 700 000 000 nanogram per tonne gold (DoM., 2005). What is the gold grade in;
i) grams per tonne (g/t)? (2mks)
ii) parts per million (ppm)? (2mk

Answer 1

To convert the gold grade from nanograms per tonne to grams per tonne and parts per million, let's follow these calculations step by step.

### i) Convert to grams per tonne (g/t)

1. We have the gold grade as 5,700,000,000 nanograms per tonne.
2. To convert nanograms to grams, we use the fact that \( 1 \, \text{gram} = 1,000,000,000 \, \text{nanograms} \).
3. Therefore, we can convert the gold grade as follows:

\[
\text{Gold grade in g/t} = \frac{5,700,000,000 \, \text{nanograms}}{1,000,000,000 \, \text{nanograms/gram}} = 5.7 \, \text{g/t}
\]

### ii) Convert to parts per million (ppm)

1. The definition of parts per million (ppm) is the same as grams per tonne (g/t) when dealing with solids, as there are 1,000,000 grams in a tonne.
2. Because of this, the gold grade in g/t will also be the same numeric value in ppm.

Thus, the gold grade is:

\[
\text{Gold grade in ppm} = 5.7 \, \text{ppm}
\]

### Summary:
- **Gold Grade in grams per tonne (g/t):** 5.7 g/t
- **Gold Grade in parts per million (ppm):** 5.7 ppm