Example of Gold Process Design and Selection

The example is about a plant that will treat a gold ore at the rate of 200 tpd with a grade of 12 g/t gold. We consider a gold price of U.S $ 400 per ounce. After evaluating the results obtained in the tests there are three options:

A. Cyanidation and Merryl Crowe process.

B. Cyanidation and Carbon-in-pulp process.

C. Cyanidation, Merryl-Crowe, and Retretament of cyanidation tails.

After analyzing the results from the tests and economic evaluation, there is the following information.

Option	Total Cost	Recovery (%)	Operative Cost (U.S.$/t)	Annual sells (U.S.$/t)	Operative Cost
A	2,600,000	91	25	9,090,000	1,825,000
B	1,600,000	87	27	8,685,000	1,971,000
C	3,200,000	93	25	9,200,000	1,825,000

- Comparing A and B.

• Investment. A > B in 1,000,000.
• Sells. A > B in 405,000.
• Operative cost. A < B in 146,000.
• Total benefits for A: 551,000.

The difference in the capital invested can be recovered can be recovered in almost two years because option A has better recovery and lower operative cost.

- Comparing A and C.

• Investment. A < C in 600,000.
• Sells. A < C in 110,000.
• Operative cost. A = C.
• Total benefits for C: 110,000.

The capital invested can be recovered in almost three years. Better recovery and major sells will generate better revenues for option C.

The above comparisons are simples, but give an idea approximated about what could happen obviously considering the market trends and financial studies on the gold market. After all these considerations, owners of the mine will take a final decision and will start the development of the project.