Abstract:The relationship between the characteristics and the sediment curve in a batch sedimentation has been discussed, and the origination of characteristics has been analysed by two phases flow wave theory. According to the sedimentation theory and experimental data, two mathematical equations for calculating underflow concentrations and unit area of a continuous thickener were derived. And a new procedure to design a continuous thickener was developed. The procedure is reasonable and valid to calculate underflow concentration and unit area of a continuous thickener.

Key words: batch sedimentation curve　thickener　unit area　underflow concentration