重介旋流选矿.ppt

1、重介旋流选矿,重介旋流器,一、离心场物料按密度分选原理,1 物料所受的离心力 2 悬浮液给与物料的向心力（向心浮力） 3 物料在悬浮液中受到的离心力（设物料与悬浮液具有相同的切向速度）,二、重介旋流器的一般结构及工作,1 DSM型的基本构造 圆筒、圆锥、溢流管、底流管、入料管 2 旋流器内液体流动形式 沿旋流器圆柱体及圆锥体内壁形成的一个向下的外螺旋流 围绕旋流器轴心形成的一个向上的内螺旋流 短路流 循环流 空气柱,三、液体在旋流器内部的流速分布和压力分布,（一）流速分布 1 切向速度Vt 2 径向速度Vr 3 轴向速度Va (二）压力分布,旋流器内部液流速度分布,切向分布,径向分布,轴向分布

2、,（三）旋流器内部液体密度分布 三、旋流器内部物料运动状况 物料的受力 器壁处：合力向下、向外 轴心处：合力向上、向内 液体阻力、颗粒重力 二次分选概念 轴向零速包络面的概念 物料、悬浮液速度差对分选的影响 当物料速度落后于悬浮液切向速度时，相当于悬浮液的密度增加，低密度颗粒受到更大的向心力作用，高密度颗粒所受离心力减小,四、重介旋流器结构参数及使用,（一）结构参数 1 锥角 锥角大，浓缩作用强，分选密度变大 悬浮液密度分布不均，分选效果下降 1530度，一般为20度 2 溢流口直径 直径扩大，零速包络面外扩，分选密度变大 溢流量增加，精煤产率增加，但灰分也增加 一般 d溢=（0.30.4）D

3、 3 底流口直径 底流口减小相当于溢流口增大，矸石易混入精煤中 一般 d底=（0.240.3）D,4 锥比d底/d溢 锥比大，可以获得较纯的精煤 锥比小，可以获得较纯的矸石 一般为0.70.8 入料口尺寸 入料口主要限制入料尺寸 入料口过大，入料切线速度减小 一般d入=（0.20.25）D d入：d溢：d底=0.2：0.4：0.3 溢流管插入深度h H=320400mm,(二）使用 1 入料压力 压力大 一方面，切线速度大，离心力强，分选速度快，分选效果好。 另一方面，悬浮液浓缩作用增强，分离密度提高，分选效果会降低。 磨损加快，动力消耗增加 P=0.040.1MPa 2 固液比（体积比） 固

4、液比提高 处理量增加 分选过程减慢 分选效果变坏 一般为1：41：6 极难选煤：可降至1：8,3 给料方式 泵给入 入料煤粉碎加重，设备磨损严重 定压箱（5米以上高差） 压力稳定，煤的粉碎减少 无压给料 悬浮液用泵以切线方向给入圆筒旋流器下部，物料靠自重由圆筒顶部给入。 4 安装 一般倾斜安装，入料压力较大时，倾角可大些,五、其它类型重介旋流器,（一）CWC复锥水介质旋流器 当物料以一定压力给入旋流器后，由于锥角较大，颗粒在第I锥体部分形成干扰沉降床层，粗而重的矸石和中煤及充填床层间隙中的细粒阻碍低密度粗粒进入床层内部，并使其转而向上运动，其余部分被新的入料驱赶至第II锥体部分，在较强的上升液

5、流作用下，中等粒度的低密度矿粒被带入溢流中，而一些同时向上流动的高密度矿粒受到较大离心力作用而被甩到周边进入底流。在第III锥体部分，上升的液流速度较弱，只有细粒低密度矿粒被带入上升流，高密度矿粒向下运动由底流口排出。,（二）涡流旋流器,The swirl cyclone is similar in shape of the DSM cyclone, but its position is inverted, the unit being used vertical, with the apex discharge at the top and the overflow at the base

6、. The vortex is stabilised by the introduction of an air-pipe into the vortex, which is open to the atmosphere. The height of this vent can be varied, as can the vortex, to act as a control parameter.,（三）麦克纳利重介旋流器,（四）圆筒重介旋流器,The Vorsyl Separator is used in many coal-preparation plants for the treatm

7、ent of small coal sizes up to about 30 mm at feed rates of up to 50t/h. The feed to the separator, consisting of deslimed raw coal, together with the separating medium of megnetite, is introduced tangentially at the top of the 60cm diameter separating chamber under pressure. Material of specific gra

8、vity less than that of the medium passes into the clean coal outlet via the vortex finder, while the near gravity material and the heavier shale particles move to the wall of the vessel due to the centrifugal acceleration induced.,The particles move in a spiral path down the chamber towards the base

9、 of the vessel where the drag caused by the proximity of the orifice plate reduces the tangential velocity and creates a strong inward flow towards the throat. This carries the shale, and near gravity material, through zones of high centrifugal force, where a final precise separation is achieved. Th

10、e shale, and aproportion of the medium, discharge through the throat into the shallow shale chamber, which is provided with a tangential outlet, and is connected by a short duct to a second shallow chamber known as the vortextractor.,This is also a cylindrical vessel with a tangential inlet for the

11、medium and reject and an axial outlet. An inward spiral flow to the outlet is induced, which dissipates the inlet pressure energy and permits the use of large diameter outlet nozzle without the passing of an excessive quantity of medium.,（五）W.S.P 重介旋流器,The Dyna Whurlpool separator is now widely used

12、 for the treatment of fine coal and ores in the range 300.5 mm. It consists of a cylinder of predetermined length, having identical tangential inlet and outlet sections at either end. The unit is operated in an inclined position and medium of the required density is pumped into the lower outlet. The

13、 rotating medium creates a vortex throughout the length of the unit and leaves via the upper tangential discharge and the lower vortex outlet tube.,Raw feed entering the upper vortex tube is sluiced into the unit by a small quantity of medium and a rotational motion is quickly imparted by the open vortex. Float material passes down the vortex and does not contact the outer wall of the unit, thus greatly reducing wear. The floats are discharged from the lower