In-Plant Testing of the Hydrofloat Separator for Coarse Phospahte Recovery

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Date
2007-08-29
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Virginia Tech
Abstract

The HydroFloat technology was specifically developed to upgrade phosphate sands that are too coarse to be efficiently recovered by conventional flotation methods. In this novel process, classified feed is suspended in a fluidized-bed and then aerated. The reagentized phosphate particles become buoyant and report to the product launder after encountering and attaching to the rising air bubbles. Simultaneously, the hydrophilic particles are rejected as a high solids content (65-70%) underflow. The fluidized bed acts as a "resistant" layer through which no bubble/particle aggregates can penetrate. As a result, the HydroFloat also acts as a density separator that is capable of treating much coarser particles as compared to traditional flotation processes. In addition, the high solids content of the teeter bed promotes bubble-particle attachment and reduces the cell volume required to achieve a given capacity. To fully evaluate the potential advantages of the HydroFloat technology, a 5-tph test circuit was installed and evaluated in an industrial phosphate beneficiation plant. Feed to the test circuit was continuously classified, conditioned and upgraded using the HydroFloat technology. The test results indicated that the HydroFloat could produce a high-grade phosphate product in a single stage of separation. Product quality ranged between 70-72% BPL (bone phosphate of lime = 2.185 x %P2O5) and 5-10% insols (acid insoluble solids). BPL recoveries exceeded 98% at feed rates greater than 2.0 tph per ft^2 of separator cross-sectional area. These results were superior to traditional column flotation, which recovered less than 90% of the valuable product at a capacity of less than 1 tph per ft^2.

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Keywords
fluidized bed, coarse particle flotation, phosphate
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