Fall Mamadou - Paste Tailings Management

Springer International Publishing Switzerland 2017

Erol Yilmaz 1 and Mamadou Fall 2

This book focuses on efficient management of large volumes of sulfide-rich tailings created during the mining and milling operations. These tailings consist of coarse and fine fractions that are either reactive (acid or leachate generating) or nonreactive, and can be risky on the environment if they do not need to be managed appropriately at mine sites. On the whole, the coarse fraction of the tailings is used for underground backfilling while the remaining fines are usually deposited on the surface into tailings dams. However, it is witnessed that these structures are subjected to some risks of failure as a result of leakage, instability, liquefaction, erosion, and poor design. Therefore, the effective, economic, and environmental management of the tailings has become a major issue for all mining operations around the world. There is an apparent necessity for sulfidic tailings management methods that are technically suitable, economically viable, environmentally sustainable, and socially responsible. Paste technology is widely considered as an emerging technique to assess mining wastes in an environmentally sound way. Sulfidic tailings mixed with cements and water are often defined as paste backfill and used to refill mined stopes, resulting in a maximum extraction rate from an underground ore deposit. In addition, surface paste disposal promises an attractive technology and viable solutions for tailings treatment. The water coming from sulfidic tailings is recovered and can be used repeatedly while the requirement of constructing the big tailings dams at surface can be minimized using paste technology.

This book endeavors to collect an operational knowledge on management and treatment of sulfidic paste tailings generated at most modern underground mine sites. In reality, there are several types of wastes including sulfidic tailings, waste rocks, effluents, sludges, leachates, slags, smelter wastes, and chimney dusts. Most of these different wastes are generated from the other sources instead of producing at mine sites. Thus, this book essentially addresses on sulfidic tailings which are inert and generated after processing of pyrite and pyritic ores. This book deals only with paste-integrated solutions being used right now at modern mines including cemented paste backfill (CPB) and surface paste disposal (SPD). These new techniques have been explained in detail from the industrial application point of view. CPB is an engineered mix that consists of total tailings without removing the fines, or desliming (7085 wt% solids), and single, binary, or ternary binders (37 wt%) in order to meet stability requirements and combined with mix water (2025 wt%). CPB provides an efficient and environmentally nondestructive tailings management technique due to its technical, operational, and environmental advantages over other types of backfilling such as hydraulic and rock fills. The most attractive features of CPB are that it allows mine operators to use the total tailings without desliming for paste production; it significantly reduces surface tailings disposal by placing them safely in underground stopes, eliminating the damages due to environmentally harmful sulfidic tailings in the form of acidic mine water or leachates; and it reduces post-mining rehabilitation costs. SPD is a new technique used by the mining industry for safe disposal of sulfidic paste tailings on the surface, since it allows for a smaller tailings dam area, increased water management capabilities, and less environmental impact. SPD consists in the deposition of tailings at a solid concentration of 70 wt% in relatively thin layers that are allowed to drain and dry before the next layer is put in place. The term paste typically signifies that the tailings do not result in segregation of fine and coarse particles during the transport and exhibit minimal bleeding after the final placement of sulfidic paste tailings. When comparing with conventional tailings disposal, SPD could offer operational and environmental advantages, such as a better water management, no need for complex retaining tailings dams, a reduced footprint of the tailings disposal area, and the possibility to use progressive reclamation.

This book has been organized into 12 chapters which document the different aspects of paste tailings management, based on underground paste backfill and surface paste disposal applications. Chapter presents case studies related to paste backfill plants.