Lesson Two JigsJigging is one of th

Lesson Two JigsJigging is one of the oldest methods of gravity concentration, yet even today the basicprinciples are not completely understood・ The jig is normally used to concentrate relativelycoarse material and* if the feed is fairly closed sized (e. g. 3〜10mm), it is not difficult toachieve good separation of a fairly narrow specific gravity range in minerals in the feed (e・g・ fluorite, specific gravity 3・2, from quartz, specific gravity 2. 7). When the specific gravi-ty difference is large, good concentration is possible w让h a wider size range. Many large jigcircuits are still operated in the coal, cassiterite♦ tungsten» gold, barites, and iron-ore in-dustries. They have a relatively high unit capacity on classifier feed and can achieve good re-covery of values down to 150^m and acceptable recoveries often down to 75pm. High propor-tions of fine sand and slime interfere with performance and the fines content should be con-trolled to provide optimum bed conditions.