The static, dynamic and industrial experiments showed that ideal results could be achieved when a kind of complicated, extremely fine flotation tailing slurry was thickened by using a compound flocculant named Xn in a vertical sand tank.

The mass concentration of overflow was very high and tailing utilization was low, because of the high ratio of fine tailings with the development of beneficiation machines, based on engineering fluid dynamics and computational fluid dynamics, and the current unclassified tailings cackfillmg technology, some key technologies of vertical sand tank mud making and overflowing were proposed.