Calculation and Model Selection of High-efficiency Thickeners

High efficiency thickeners consist of concentration tanks and sludge scrapers. What makes high-efficiency thickeners different from the ordinary thickeners lies in their addition and mixture device for flocculants and sometimes skew plates inside the tanks with the aim of increasing the desalting area. This kind of high-efficiency thickeners has high deposition efficiency, large deposition area and great capacity per unit and other characteristics. In general, per unit area capacity of high-efficiency thickeners can reach to 7 to 8 tons per day. There are three computing methods for high-efficiency thickeners calculation and model selection, namely, calculating according to an index of capacity per unit area, settling velocity of the biggest overflow particle and sedimentation experiment results. Now we will give a brief introduction about the first method.Speaking of a calculating method according to an index of capacity per unit area for high-efficiency thickeners, the concrete processes are as follow. First, we need to figure out the necessary area of sedimentation on the basis of the designed capacity with the following formula.

A=q/ q0

Here, A- the total necessary area for sedimentation, m2;

q- the solid amounts fed into thickeners, t/d;

q0- the capacity per unit area, t/( m2·d). q0 can be obtained through industrial experiment or can be obtained with reference to similar dressing plants production index in case of no industrial experiment.

Having worked out the necessary area of sedimentation, we can determine high-efficiency thickeners specification and set number based on the book Ore Dressing Equipment Manual. It is a rather simple way of model selection, but the result is not precise enough and has a relatively large error with actual demand. Consequently, it is advisable to use it in the preliminary design for dressing plants.

Actually, the materials sedimentation velocity in water also needs to be taken into consideration to achieve reasonable calculation and model selection of high-efficiency thickeners. Therefore, it is necessary to pay attention to the factors that influence materials settling speed when choosing high-efficiency thickeners. The impact factors are varied, including a liquid-solid ratio of feeding and discharging materials, size composition of feedstock, a viscosity of slurry and froth, types of flotation reagents and flocculants, and slurry temperature, etc.

Calculation and model selection of thickeners are a relatively important process for dressing plants design. In foreign countries, they are usually conducted by thickeners manufacturers; while in China, they are often made in accordance with the requirement of dressing plants or design organizations. Therefore, it is quite vital to contact thickeners manufacturers to get more detailed information when choosing high-efficiency thickeners.