技术报告-尾矿库设计及评估 (英文)

Design and Evaluation of Tailings Dams

More recently, concerns have been raised about the stability and environmental performance of tailings dams

and impoundments. Stability concerns are raised in part by the use of tailings material in tailings

dams/embankments; to mitigate these concerns, such embankments often rely on a certain amount of

controlled seepage to enhance stability, which in turn affects environmental performance. Ritcey (1989) has

speculated that the need for sound impoundments in the uranium industry "probably" accounts for much of

the recent attention paid to impoundment design in other types of facilities. Perhaps triggered by the initial

attention to uranium impoundments, the increasing concern for environmental performance has led to better

engineering design of tailings dams in other mining industry sectors, for both stability and environmental

performance. For instance, experience gained with leach pad liners is being transferred to linings for tailings

ponds, and the use of synthetic lining materials is growing (although use of liners is still far from being the

industry norm). In addition, the use of cyanide and other toxic reagents in mill processes has raised special

concerns for some tailings and is leading to increased treatment prior to disposal as well as increased

attention to containment. Finally, continuing concerns over acid mine drainage is resulting in a growing body

of research and emerging concepts of long-term control or mitigation.

Inactive tailings impoundments also are receiving more attention due to the long-term effects of windblown

dispersal, ground water contamination, and acid drainage. In many cases, the costs of remediation can be

considerable, exceeding the costs of original design and operation of the tailings impoundment.

While this report discusses general features of tailings dams and impoundments, actual designs for tailings

disposal are highly site-specific. Design depends on the quantity and the individual characteristics of the

tailings produced by the mining and milling operation, as well as the climatic, topographic, geologic,

hydrogeologic and geotechnical characteristics of the disposal site, and on regulatory requirements related to

dam safety and to environmental performance. What may work for one type of tailings may not work for

another type, and may not work for the same tailings at different sites. Hence each situation requires its own

design process. The estimated quantity of tailings to be disposed of is particularly important given the

evolving nature of most mining projects. Tailings quantity estimates are based on estimated reserves that

change continuously as mine development progresses. Accordingly, the final size and design of tailings

impoundments can differ substantially from initial projections. This presents major challenges to Federal

land managers and State permit writers, who are faced with reviewing and overseeing tailings impoundment

planning, design, and performance, and to the general public, who may ultimately pay for miscalculations

resulting in environmental damages.

The purpose of this report is to provide an introduction for Federal land managers, permit writers, and the

general public to the subject of tailings dams and impoundments, particularly with regard to their engineering

features and their ability to mitigate or minimize adverse effects to the environment. The report is based on

the current literature on tailings impoundment engineering. While broad in scope, the report is necessarily

limited in depth: a comprehensive guide to the design and evaluation of tailings impoundments would

incorporate most of the materials in a number of examinations of tailings dam engineering and environmental

performance, including those in texts by Vick (1990), Ritcey (1989), and CANMET (1977), among others.