The idea that pilot plant tests indicates increased reliability on gold recovery predictions derived from laboratory testing program is not necessarily true. For example, in reality flotation locked cycle tests that are cheaper and easier to control, generate more statistically useful data considering the response of multiple gold ore samples to a wide range of treatment parameters. At best, a well run pilot plant only match results of a series of locked cycle tests.
It has been noted in several gold projects that poorly designed development programs, pilot plant tests may be performed on quite different sample from those employed to develop the processing flowsheet. In this way a large part of the pilot plant budget is employed to carry out poorly executed and expensive, flowsheet development studies. Basically, the operation of pilot scale circuits present special control problems that are more severe than those faced in the laboratory testing program. It is possible to find distortions of processing parameters and to solve these problems need numerous subtle manipulations to obtain useful results- then, a pilot plant test may confuse the design process by producing results that are quite different from batch cyanidation tests or flotation locked cycle tests.
The basic consideration for performing a pilot plant test is to duplicate the results of process simulations that were obtained by several laboratory cycle test procedures on the same composite. It is often claimed that a pilot plant test will render a project bankable and is therefore a critical aspect of the feasibility study. Nevertheless, some gold ore processing plants are designed, financed and built without a pilot plant tests provided that the overall quality and quantity of the laboratory test results are sufficient. For example, assessment of flotation capacity is not based on the observed residence times in the laboratory or pilot plant, but on the ability of the flotation cell to transfer gold-bearing minerals froth to the cell launder. Laboratory kinetic testwork or down bank data provide the critical flotation rate data for flotation circuit design purposes. A design engineer acquires and uses comparative solid mass flow and residence time data from similar operations to determine the requirement for installed cell capacity.