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The tailings dam is the main building of the tailings field and consists of initial dams and stacking dams, in addition to other structures.
(1) The initial dam of the tailings dam is the basic structure of the tailings field. It can not only store the initial tailings, but also give the management personnel the necessary preparation time for the late dams. It is also the support of the tailings field. The structure is the foundation of the stacked dam and works together with the accumulation dam to achieve the purpose of blocking the tailings. The dam should adopt a permeable dam to facilitate the drainage consolidation of the tailings and reduce the immersion line of the dam, thus improving the stability of the dam (including seepage stability and dynamic stability).
A. Determination of initial dam height
The primary factor determining the initial dam height (Fig. 1) is the initial tailings volume. Generally the initial beneficiation plant tailings six months to a year for the amount of the initial amount of tailings fill dam, as initial dam crest elevation also be checked three conditions apply:
(1) Meet the requirements of water return water depth, flood depth and safety:
(H 1 -H K )≥(h j +h t +e) (1)
Where H1—the initial height of the initial dam dam, m;
(H m -H K )≥(h j +h t +e) (2)
The rest of the symbols have the same meaning as the formula (2)
L K ≥(L+L 3 ) (3)
(2) Meet the requirements of tailing water clarification distance. Calculated according to formula (3).
(3) Meet the requirements of seepage control of stacked dams. In some tailings mines, the requirements for increasing the length of sedimentary beaches to achieve seepage control are limited, or the drainage facilities are not economical, and the height of the initial dams can only be increased to achieve seepage control. At this time, the initial height of the initial dams should meet this requirement.
If the above three conditions can be satisfied, the initial elevation of the initial dam dam as determined by the storage capacity curve is the elevation to be determined. Otherwise, the initial elevation of the initial dam dam should be raised until the requirements are met.
The initial elevation of the initial dam dam height H1 minus the initial dam dam axis is the height of the initial dam.
(4) In addition, for the tailings field where the dam arrow has a water accumulation area (such as the tailings field after the dam is released), the formula (1) should also consider the wind and wave climbing h BB :
(H 1 -H K ) ≥(h j +h t +e+h BB ) (4)
Where h BB —— wind and wave climb, related to the upstream slope of the dam, the length of the water surface and the wind level. For the calculation, refer to the dam professional books.
The tailings of the downstream method and the mid-stream method dam, the initial tailings amount is determined by the sum of the tailings amount in the overflow section of the cyclone at the initial stage of production and the total tailings amount of the cyclone non-working time. The main basis for high. In this case, the initial dam height should only be checked by formula (3) and formula (1), and the downstream filter dam should meet the seepage control requirements of the stack dam. [next]
B. Initial dam structure and damming materials The initial dam structure can be divided into two categories: permeable and impervious.
The permeable dam is generally a rockfill dam (Fig. 2). If possible, the mine can be used to strip the waste rock and dam (Fig. 3). Since the permeable dam has the function of sand filtration, it can reduce the wetting line of the dam and the tail. The stability of the mine (including dynamic stability) is favorable, so most of the large and medium tailings and tailings in the seismic zone use this type of dam. In some areas lacking stone, but also the completion of filtration of formula dam upstream slope slope (FIG. 4), such as a copper mine tailings Mouding, designed as a slope of the upstream slope type filtration, the concentrated water seepage It is good to use the water collecting pipes at the foot of the dam slope to be collected and discharged outside the dam. [next]
Impervious dams are mostly earth dams, and a few are stone masonry dams or concrete dams. Because the earth dam can be taken locally, the construction is convenient, and the dam construction process is simple, it has been widely used. However, since the dam body cannot function as a drainage water, the immersion line of the accumulation dam is high, which is unfavorable for its stability. Therefore, it is only suitable for small tailings fields, or a large number of drainage facilities need to be installed in the accumulation dam to reduce the immersion line. Practice has proved that after the height of the dam of the dam at the initial stage of imperviousness, the height of the dam exceeds 20 to 30 meters, and the immersion line will escape from the accumulation dam above the initial dam. Therefore, when using this type of dam, it is generally necessary to take some measures to reduce the immersion line to facilitate the stability of the dam.
The tailings of the mid-stream dam and the downstream method dam are divided into two parts: the upstream dam (called the initial dam) and the downstream filter dam. The initial dams are located at the lower part of the axis of the final stacked dam and the foot of the upstream slope of the stacking dam, and an impervious dam can be built. The filter dam is always located at the foot of the slope of the downstream slope of the final accumulation slope, and the permeable dam must be used (Fig. 5 and Fig. 6).
The dam material of the initial dam may be used as long as it meets the requirements for damming soil or stone materials, and any material may be used, but it must pass through the dam material design. First of all, the dam material should be a material with stable seepage; in addition, different dam materials should be piled up in different parts, such as the soil material of the impervious dam, the water permeability is small and placed on the upstream slope, and the water permeability is large. Downstream of the axis, and avoiding the mixing and stratification of the two kinds of soil materials; for the stone of the permeable dam, the water-passing part should be slightly weathered or unweathered stone, but the water part can be any material. For dam materials that may cause seepage damage, measures to prevent seepage damage must be taken. This should also be the case for dam foundation soils.
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