FLEET

FLEET (flotation economic evaluation tool) is a software tool that factors the variability of flotation response within an ore-body and considers the related difficulties that arise from the scaling-up of laboratory tests.  The use of FLEET to address these flotation model problems improves design, optimization and production planning in flotation plants. The FLEET output provides detailed process and economic information to the design or production planning team.

FLEET is used for:

• flotation circuit design, scale-up and optimization from lab flotation data
• recovery and final concentrate grade predictions throughout the mine resource model for any given circuit design

FLEET can:

• Manage risk by designing flotation circuits that ensure recovery and grade targets are achieved
• Improve production planning by populating the resource block model with metallurgical grade and recovery data
• Assign a more accurate dollar value to each mining block (a product of metal content and improved forecasting of throughput, recovery and grade)
• Predict changes in plant recovery based on changes in plant grind
• Identify the most effective equipment configurations or circuit design
• Provide credible design and cost criteria

TECHNICAL COMPONENTS OF FLEET

The Need for FLEET
The need for FLEET is attributed to:

• variability of flotation response throughout an ore-body
• related difficulties scaling-up from laboratory tests.

For a given block of ore it is unlikely that the plant grind size distribution that will feed the froth flotation circuit or the flotation residence time will be known at the time of laboratory testing. Hence, the grind size distribution used in the laboratory test is not likely to be that which actually occurs once the ore is processed. As well, the laboratory retention time may not represent the actual plant conditions.

The approach that SGS Minerals Services has taken to address this is to determine key model parameters from grinding and flotation laboratory test work on a large suite of samples from across the ore-body. This data is then modeled to predict plant performance. The model also incorporates a comprehensive database of equipment specifications, circuit designs, costs, and metallurgical considerations. The laboratory measurements used in FLEET are the maximum recoveries and the rate constants for different minerals and different size fractions.

FLEET ADDRESSES FLOTATION MODEL PROBLEMS
Previous flotation models have not accurately forecasted recovery through and across ore types. FLEET addresses five of these issues:

Issue 1: Plant feed not representative of the samples used for flotation test work.
Solution: FLEET, along with the streamlined SGS Minerals Services flotation test (MFT) allows parameters such as rate constants, RMAX and grind/recovery to be modeled using a block distribution approach. The kinetic parameters of the MFT are independent of feed-grade which eliminates the need for the lab sample to have the same grade of the plant feed.

Issue 2: Insufficient understanding of machine surface area, froth transport, froth drop-back effects, and entrainment issues on full scale mechanical and column cells.
Solution: As a result of extensive flotation scale-up, auditing and commissioning work over the past 12 years, SGS Minerals Services now has a thorough understanding of flotation surface area effects, entrainment effects, froth transport and drop-back issues on both column and mechanical cells. The SGS Minerals Services FLEET models incorporate this knowledge and eliminate the errors arising from these issues.

Issue 3: Changes in flotation feed size distributions not matching lab grind distributions
Solution: CEET (Comminution Economic Evaluation Tool) output can be received by FLEET to take this problem into account and correct for it.

Issue 4: Insufficient understanding of residual kinetic effects and rate constant distributions and how to account for these factors in circulating loads.
Solution: FLEET includes specific equipment models that have been developed by SGS Minerals Services for tank cells, column cells, standard mechanical cells and contact cells. The models utilize mineral rate constants, mineralogical analysis and scale-up formulae. Primary and residual rate constants and rate constant distributions are used to adjust circuit responses for varying circulating loads.

Issue 5: Insufficient field calibration.
Solution: Rougher circuit configurations can be changed, with flotation cells added or taken away, and the effect on concentrate grade and recovery can be calculated throughout the life of the mine and shown in both graphical and tabular form. Costing data and formulas for flotation cells, pumps and associated equipment configurations are included for cost comparisons of the different circuits. Comprehensive ongoing FLEET benchmarking continues to reduce this problem.

Both FLEET and CEET (Comminution Economic Evaluation Tool) can be used for either design of a new mill facility or for production planning within an existing operation.