In this study, the microencapsulation-hybrid jig separation technique was developed to improve the separation efficiency of pyrite and coal in the particle size range of 1–4 mm where conventional jig separation becomes inefficient. A hybrid jig is a gravity concentrator combining the concepts of jig separation and flotation to stratify particles based on their apparent specific gravity. Meanwhile, microencapsulation—a technique that encapsulates target materials with a protective coating—was applied to render pyrite hydrophilic and improve its separation from hydrophobic coal. The results showed that the required time for separation in the hybrid jig (0.5 min) was shorter than in conventional jig (2 min). Moreover, the effects of particle size on separation efficiency were reduced when a hybrid jig is used. However, the separation efficiency of hybrid jig separation was lower than that of the conventional jig because attachment of bubbles occurred to both pyrite and coal, which are hydrophobic. Using the microencapsulation-hybrid jig separation technique, the separation of coal and pyrite was significantly improved (~100%) because of the formation of hydrophilic iron phosphate coatings on pyrite that limited bubble attachment. This means that microencapsulation-hybrid jig separation is a promising clean coal technology that not only enhances the separation efficiency of the hybrid jig but also passivates pyrite and limits AMD formation in the tailings/rejects.

Gold is one of the precious metals used all over the world. It is used in various ways, such as in electrical and electronic equipment, as well as in jewelry. Gold is constantly depleted, so recycling is a very important process for recovering valuable materials as secondary raw materials. In this study, the residue from a jewelry waste recycling process was used. Shaking table separation and flotation as the pre-treatment before the hydrometallurgical processes were investigated. For shaking table experiments, the effects of table angle and water flow rate were investigated and a batch-type mechanical flotation was used for the flotation experiment. The results showed that for the shaking table separation, gold recoveries were high, while the purity of gold was higher, with lower recovery.