The Experimental Research On Separation And Classification Performance Of Gravity&Flotation Consecutive Experimental System

As an important part of the coal slurry water treatment, flotation guarantees the washing water closed-circuit circulation of coal preparation plant and recycles fine clean coal at the same time. While in the process of flotation, coarse particle losing is a common phenomenon, which caused economic losses. Most coal enterprises recycle these coarse particle clean coal which losing in flotation tailings by using equipments of screen-bowl centrifuge and oscillating screen; there is also some scholars using methods of multistage flotation, classification&flotation and various combinations of flotation equipments to improve the flotation process and the recovery rate of coarse clean coal.On the basis of gravity&flotation separation theory and processing study in laboratory by Yang Hong-li, this article builds a gravity&flotation consecutive experimental system (GFS). Using flotation and gravity separation to discharge fine and coarse grain of high ash tailings respectively provides a new method for the fine coal separation. The system has a great significance to improve the overall separation efficiency and shorten the handling process of flotation tailings.Conducting a experimental research on separation performance of the Cyclonic Separation and Aerator (CSA), the results show that the addition of mixing blades makes separation performance of the CSA have a great promoting compared with the coal slime hydro-cyclone gravity separation column. The insertion depth of overflow tube has a greater influence to separation performance of the CSA. The total ash of underflow can reach above60%which achieves an ideal separation result when the insertion depth of overflow tube is65mm.To proceed an experimental study on classification performance of graded device, which shows that the graded device don’t exist the phenomenon of coarse grain losing to graded overflow. The classification device can discharge1/2～1/3of-0.074mm slimes of high ash on the appropriate condition of diversion ratio. The graded underflow diversion ratio directly determines the underflow distribution rate of-0.074mm; it also means that the greater underflow diversion ratio, the more amount of-0.074mm in graded underflow. The results also show that the partition size increases with the increasing of feeding rate. The experimental results of vertical distribution on particle sizing device in the classification device agree with the conclusion achieved by Yang Hong-li through simulation of the flow field. Having carried on the experimental study on the flotation performance of flotation column, the results show that the jet device can completely satisfy the requirement of1:1best gas liquid ratio with the appropriate structure parameters and test conditions. Under the same feeding pressure, the jet device with conical nozzle have greater inspirational capacity than orifice nozzle, while the inspirational capacity of jet device with orifice nozzle is2-3times of the conical under the same pulp flow. The ash of flotation tailings increases with the increasing of foaming agent. When the installation height of diversion barrel is300mm, the flotation column can achieve better results, ash of clean coal and flotation tailings creases with the installation location of diversion barrel.Studying the separation and classification performance of gravity&flotation consecutive experimental system, it shows that the increasing of middling circulation has little effects on the yield and ash of clean coal and graded overflow, while it has significant influence to the yield and ash in underflow of CSA. The study of stability of system operation shows that each graded ash of product is relatively stable, but the yield of production has a great change. In general, the yield and ash of classification overflow is most stable.