金屬礦物典型重選工藝 -鎢礦石的重選生產

    在金屬礦選礦設備生產中，重選的應用大概有如下幾方面： 
    （1） 進行礦石的預選。在粗、中粒以至細粒條件下提早選出部分終尾礦，以減少細磨深選的礦量，降低生產費用； 
    （2） 處理含高密度礦物的礦石。重選一直是選別黑鎢礦、錫石傳統的方法，并且也是分選含稀有金屬（鈮、鉭、鈦、鋯）和貴金屬（金、鉑）礦石的基本方法，在處理弱磁性的鐵、錳礦石中也較多應用；

     （3） 與其它選礦方法如浮選、磁選組成聯合流程，進行粗、細粒級分選綜合回收有用成分； 
    （4） 作為其它選礦工藝的補充作業，回收伴生的重礦物或對主要成分進行補充回收。 
一、處理粗、細不均勻嵌布黑鎢礦石的重選生產 
     我國的鎢礦生產世界馳名，鎢的總儲量占世界一半以上，具有工業價值的是黑鎢礦（鎢錳鐵礦）和白鎢礦（鎢酸鈣礦）。白鎢礦以浮選或浮— 重聯合方法處理為主，黑鎢礦則主要用重選法回收。在我國的鎢精礦產量中，后者占較大比例。 
     黑鎢礦礦物密度為7200~7500kg/m3, 礦物呈板狀、粒狀晶體產于石英脈中，結晶粒度大達25~10mm, 小者0.5~0.1mm, 嵌布很不均勻。礦物性脆易碎，不少的黑鎢礦物與伴生金屬礦物組成集合體，嵌布在非金屬礦物基質中，在采出的礦石內，中、細粒級含礦較多。 
      我國的鎢礦選廠分布在江西、湖南、廣東等省，經過多年的生產摸索，流程已基本定型。全流程主要由預選段（粗選段）、重選段和細泥分選段組成。在大型選廠還有精選段，在那里對重選混合精礦進行終分離。 我國鎢礦選廠通用二段選別流程。由預選段送來的合格礦石選用雙層振動篩篩分成3 個粒級。粗、中粒級送跳汰選別，細粒級經水力分級后給搖床處理。第1 段跳汰尾礦送棒磨機磨碎后給第2 段跳汰機。該機產出的尾礦從細粒搖床中礦返回至第1 段給礦，故該流程又稱“ 二段大閉路” 流程。它既可在粗粒條件下回收部分塊鎢，又可避免流程過分復雜化。 
       大型選礦廠則可在上述流程基礎上予以擴大，例如將第1 段粗粒級的跳汰尾礦單獨破碎、跳汰選別，構成第2 選別段。選后的尾礦再與中粒級跳汰尾礦合并磨礦，這樣便構成了三段選別流程。對于細粒級的搖床中礦亦可單獨再磨再選，不再返回初給礦，鴯實行貧富分選。 重選工藝流程作這樣的擴展將更有利于降低尾礦品位，提高綜合選礦指標，但基本未脫離“ 破碎— 跳汰” 、“ 磨礦— 搖床” 這一階選別模式，適合于早收、多收、減少過粉碎的原則要求。

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.