The factors to consider and how to use them to select the flotation cell are very important during the feasibility study of the project or when the plant will be expanded. It has been noted for several year that flotation cell manufacturers tend to offer their machines on the basis of superiority in some of the following areas, capital cost, maintenance cost, power consumption, sanding problems, particles suspension and metallurgical performance. The latter factor is related to gold recovery and concentrate grade, and is very important due to even in a small flotation plant, minuscule improvements in gold recovery, allows getting equilibrium between expenditures and incomes.
Many times, it is difficult to detect the influence of the metallurgical performance on the operation and small changes could not be important in one day, but when the improvement is considered over a period of several months, the positive impact is valuable. When the power cost takes high levels, the power consumption is a key factor in the flotation circuit design and the cell design. For this reason, it is important to consider large flotation cells according to the plant capacity. Basically, lower power consumptions remains a major selling point and some project metallurgist are not able to realize the importance of this aspect. For example, rougher flotation performed on coarse particles needs more power than fine grinds to maintain suspension. Paying much attention to low power consumption could reduce the recovery of gold in coarser fractions.
When it is important to optimize processing rate, an increased throughput usually needs some changes in particle size and the resultant recovery drop may be unacceptable. For some guys, all flotation cells yield satisfactory recoveries, but all give variable recoveries at the fine and coarse ends of the size range. Experienced operators know that some flotation machines give better gold recovery of fines and other of coarse sizes, but this aspect is relate to the mineralogy and design of the flotation cell. The reason for these variable recoveries of fine and coarse particles is related to the hydrodynamic conditions required to operate successfully the flotation cell. For this reason manufacturers study and resign the geometry of the cell trying to optimize the design. If the recovery of fine and coarse particles is problematic, some designs include separation of fine and coarse particles and each stream feeds a particular flotation cell or any particular part of the flotation circuit. There is not a perfect cell and for many gold operations, the reward for gold recovery increase of 0.5% to 5% is very important for the economy of the project or operation.