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# Another frequently used unit of measurement for ore grades is "parts per million" or ppm.

Another frequently used unit of measurement for ore grades is "parts per million" or ppm. Instead of finding the concentration per 100 parts, like the percentage, ppm finds concentration out of one million parts. This unit is used to represent metals that often occur in smaller concentrations. A gold ore with a 2 ppm ore grade would have 2 pounds of gold for every 1,000,000 pounds of ore. An equivalent unit is grams/ton (since there are 1,000,000 grams, or 10 6 grams, in a metric ton). Thus a 2 ppm grade gold ore would also have 2 grams of gold for every ton of ore.

1) A gold coin called a Krugerrand has approximately 31.1035 grams of gold in it.

a. How many metric tons of 15 ppm grade gold ore need to be mined in order to get enough gold for a single Krugerrand? Show your work here. Remember that 1 metric ton = 1x10 6grams.

b. How much waste product (in metric tons) is created? Show your work here.

a) 15 ppm grade of gold ore would have 15g in 10^6g or 15g in a ton. Then... View the full answer

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