When a gold recovery process will produce a gold concentrate, the economical analysis of the profit generated by the concentrate is practiced. A more complete analysis of plant performance may indicate the detailed reasons why the economic recovery is inevitable less than 100% and what aspects of the operation are making the major contributions to the efficiency. Such analysis is lengthy and complex, but handled quickly by an experienced metallurgist. Basically, the planning decisions are influenced by the economic awareness of decision participants and timely financial analysis provides pertinent information of the operation.
The basic calculation is performed in several stages using the usual mill returns as input data. The first stage calculates the product of a perfect separation and concentration and the financial return therefrom. The second stage determines a mass balance for the actual separation. This in self can present problems depending on the input data available. The accuracy obviously is influence by the assays and tonnages. Basically, it is common to use the two products formula (concentrate, and tails). In Mexico and Peru, some polymetallic operations content gold and silver and it is common to produce more than one concentrate. In this case, the three or four products formula is used to determine the recovery of precious metals and base metals. The third stage determines the financial return for the actual separation and the economic recovery for the overall process.
The fourth stage breaks the calculation down into the returns and losses attributable to each constituent of the gold concentrate. Each element or constituent is made to bear its rightful proportion of the freight and treatment charges and is given a credit for its proportion of payments made. Some constituents add to freight and treatment costs, yet command no payment. For example, gold and silver make a positive contribution while gangue and moisture in the same concentrate make a negative contribution. Each concentrate may be analyzed completely in this way.
The fifth stage classified the results in terms of individual elements. For example, the return for gold and silver in the concentrate and tailings. The last stage compare the actual return for element in each product with what the return would have been if the same amount of valuable mineral had been recovered in the concentrate. The difference between the ideal return and the actual return is considered a loss, the extent by which the actual operation falls short of the perfect operation, the losses are added up. These final considerations indicate clearly where the gold operation is being successful and where serous losses are being made.