The Effect of Washwater

Clean water can be applied to the top of the froth, to flush entrained material downwards, preventing it from flowing out with the flotation product. There are two measures which are used to measure and control washwater addition: the bias and the wash-water ratio.

Bias is the absolute excess of the washwater applied to the froth, over the quantity of water being recovered in the concentrate, expressed as a superficial velocity Jb (cms-1): Jb = (Qww - Qwc)/Ac, where QWW, QWC are the volumetric flow rates of wash-water and water in concentrate, and AC is the cross-sectional area of the column.

The washwater ratio is defined as the ratio of the washwater addition rate, to the flow rate of water in the concentrate: W = QWW/QWC. The washwater ratio is a relative measure of the amount of washwater applied. If no washwater is used, the washwater ratio is zero and the bias is negative. When Jb = 0, W = 1.

A positive bias corresponds to washwater ratios greater than unity.

Although the bias does give an indication of the absolute amount of washwater being added, its use can be misleading because it does not take into account the wide variation in the absolute values of the rate of water entrainment in the concentrate. It is preferable to use the washwater ratio, which is a relative figure. In practice, it has been found that best performance is achieved when the washwater ratio is greater than 1.

Solar Panel Basics

Solar Panel Basics

Global warming is a huge problem which will significantly affect every country in the world. Many people all over the world are trying to do whatever they can to help combat the effects of global warming. One of the ways that people can fight global warming is to reduce their dependence on non-renewable energy sources like oil and petroleum based products.

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