金属矿物典型重选工艺 -钨矿石的重选生产

    在金属矿选矿设备生产中，重选的应用大概有如下几方面： 
    （1） 进行矿石的预选。在粗、中粒以至细粒条件下提早选出部分终尾矿，以减少细磨深选的矿量，降低生产费用； 
    （2） 处理含高密度矿物的矿石。重选一直是选别黑钨矿、锡石传统的方法，并且也是分选含稀有金属（铌、钽、钛、锆）和贵金属（金、铂）矿石的基本方法，在处理弱磁性的铁、锰矿石中也较多应用；

     （3） 与其它选矿方法如浮选、磁选组成联合流程，进行粗、细粒级分选综合回收有用成分； 
    （4） 作为其它选矿工艺的补充作业，回收伴生的重矿物或对主要成分进行补充回收。 
一、处理粗、细不均匀嵌布黑钨矿石的重选生产 
     我国的钨矿生产世界驰名，钨的总储量占世界一半以上，具有工业价值的是黑钨矿（钨锰铁矿）和白钨矿（钨酸钙矿）。白钨矿以浮选或浮— 重联合方法处理为主，黑钨矿则主要用重选法回收。在我国的钨精矿产量中，后者占较大比例。 
     黑钨矿矿物密度为7200~7500kg/m3, 矿物呈板状、粒状晶体产于石英脉中，结晶粒度大达25~10mm, 小者0.5~0.1mm, 嵌布很不均匀。矿物性脆易碎，不少的黑钨矿物与伴生金属矿物组成集合体，嵌布在非金属矿物基质中，在采出的矿石内，中、细粒级含矿较多。 
      我国的钨矿选厂分布在江西、湖南、广东等省，经过多年的生产摸索，流程已基本定型。全流程主要由预选段（粗选段）、重选段和细泥分选段组成。在大型选厂还有精选段，在那里对重选混合精矿进行终分离。 我国钨矿选厂通用二段选别流程。由预选段送来的合格矿石选用双层振动筛筛分成3 个粒级。粗、中粒级送跳汰选别，细粒级经水力分级后给摇床处理。第1 段跳汰尾矿送棒磨机磨碎后给第2 段跳汰机。该机产出的尾矿从细粒摇床中矿返回至第1 段给矿，故该流程又称“ 二段大闭路” 流程。它既可在粗粒条件下回收部分块钨，又可避免流程过分复杂化。 
       大型选矿厂则可在上述流程基础上予以扩大，例如将第1 段粗粒级的跳汰尾矿单独破碎、跳汰选别，构成第2 选别段。选后的尾矿再与中粒级跳汰尾矿合并磨矿，这样便构成了三段选别流程。对于细粒级的摇床中矿亦可单独再磨再选，不再返回初给矿，鸸实行贫富分选。 重选工艺流程作这样的扩展将更有利于降低尾矿品位，提高综合选矿指标，但基本未脱离“ 破碎— 跳汰” 、“ 磨矿— 摇床” 这一阶选别模式，适合于早收、多收、减少过粉碎的原则要求。

In the metal ore dressing production, the application of reelection is probably as follows:
(1) preselection of ore. Some final tailings are selected early in the coarse, medium grain and even fine grain conditions to reduce the amount of fine grinding and deep selection and reduce the cost of production.
(2) to deal with ore containing high density minerals. Gravity is always method separating wolframite and cassiterite tradition, and sorting includingmetals (Nb, Ta, Ti, Zr) and precious metals (gold, platinum) method of ore, also widely used in iron and manganese ore in weak magnetic treatment;

(3) in combination with other mineral processing methods such as flotation and magnetic separation, a comprehensive recovery of useful components for coarse and fine grain classification is carried out.
(4) reclaim the associated heavy minerals or reclaim the main components as supplementary operations for other beneficiation processes.
First, the heavy, fine and uneven distribution of the tungsten tungsten ore
China's tungsten production is well known in the world, the total reserves of tungsten accounted for more than half of the world, with industrial value is wolframite (wolframite and scheelite) (scheelite). Based on Scheelite Flotation or flotation combined process, mainly by gravity method. The recovery of wolframite. In China's tungsten concentrate production, the latter accounts for a large proportion.
Wolframite mineral density is 7200~7500kg/m3, mineral slaty and granular crystals produced in the quartz vein, the maximum grain size of 25~10mm, small 0.5~0.1mm, inlay is not uniform. The mineral is brittle and fragile. There are many aggregates of wolframite and associated metal minerals, which are embedded in non-metallic mineral matrix. In the ore produced, there are more middle and fine grained ores.
The tungsten ore selection plant in China is distributed in Jiangxi, Hunan, Guangdong and other provinces. After many years of production and exploration, the process has been basically fixed. The whole process is mainly composed of a pre selection (roughing), heavy selections and slime separation zone. There are also selected sections in the large selection plant, where the mixed concentrate is finally separated. The general two section selection process of tungsten ore selection in China. From the pre qualified ore sent by adopting double-layer vibration sieve into 3 fractions. The coarse and medium grain grade feeding jig is selected, and the fine grain grade is treated by the hydraulic grading after the hydraulic grading. The first jig tailings feed rod mill is ground to the second jig. The output from the tailing machine slimer middling return to paragraph first to mine, so the process is also called "two big closed" process. It can not only recover some of the tungsten under the coarse grain condition, but also avoid the excessive complexity of the process.
Large scale beneficiation plants can be expanded on the basis of the above process, for example, the first most coarse grain jigging tailings are separately broken and jigging and sorting, which constitute second selected sections. The selected tailings are then combined with the medium grain jig tailings, so that the three section of the separation process is formed. For the fine level table can be separately and regrinding, not to return to the initial implementation of the separation of ore, emu.

The expansion of the process will be more conducive to reducing tailings grade and improving comprehensive mineral processing index, but it is basically not divorced from the sorting mode of "fragmentation jigging" and "grinding rocking bed", which is suitable for the principle of early harvest, multi harvest and reduction of over crushing.