Circular use of fine-grained tailings to underground mine wind walls

Abstract

Mining activities tend to generate various waste including tailings, waste water and waste rock. Efficient management and disposal of these waste materials are critical to minimize their environmental impact and ensure the sustainable operation of mining activities. A huge number of tailings are produced all around the world each year. Generally, part of the tailings is used for underground backfilling and another part is discharged to the tailings dam. The former can provide underground support while the latter tends to cause some environmental problems because the tailings are generally mixed with some chemicals. Regarding this, enhancing the circular use of tailings is crucial to guarantee the sustainable mining engineering. In this study, the feasibility of using fine-grained tailings to make non-burning hollow bricks for underground windbreaks is investigated. A two-stage experiment was implemented where the first stage experiment indicated the threshold of water content, the ratio of cement and tailings and the ratio of fine-grained and rod-mill tailings. In addition, it can be indicated that the addition of polyethylene fibers would increase the compressive strength of hollow bricks in some extent. The second-stage experiment was conducted with no rod-mill tailing added and it can be found that when the ratio of cement and tailings is equal or higher than 1:6, fiber content is more significant in improving brick strength but when this value is lower, the ratio of cement is more important than fiber factors. When the ratio of cement and fine-grained tailings is 1:8 with 0.5 g/kg and 12 mm polypropylene fiber added, the hollow brick is capable of achieving strength of 1.4 MPa for 28 days curation with the price of 0.50 RMB/block. This proportioning scheme is the least expensive while meeting the strength of the windbreak wall for the Fan Kou lead–zinc mine. Finally, it can be indicated that the usage of fine-grained tailings to make underground windbreak wall is feasible and thus provide a new scenario to circular usage of tailings. In addition, other proportioning schemes proposed in this study perhaps can meet more engineering requirements so as to provide more alternatives for circular use of tailings.