Abstract: The article discuss the relationship between the volume concentration of solid phase in suspension and heavy-medium consumption, in dense medium coal cleaning process. The result indicates that products entrain dense medium is poor fluidity of dense medium suspensions caused by excessive volume concentration of solid phase in the suspensions, in essence, excessive conglutination, too much of coal slime in it, unseemliness of by-pass flow rate, etc. It is very important to make sure of volume concentration of solid phase which is the basis to determine the fluidity and by-pass flow of dense medium.