Selection and calculation of tailings (1)

(I) Types of tailings and their selection A Type of tailings According to the topography, there are three types: valley type, hillside type and flat type.
According to the way of damming, there are two types of dam type (including waste rock dam) and tailing pile dam type.
B. Principles for site selection of tailings site (1) The tailings field should be selected as follows in the downstream of industrial enterprises, residential areas and scenic areas and the dominant wind direction;
(2) Minimize or slow down the farmland, and do not demolish or less demolish residential houses;
(3) the distance from the dressing plant from near to far, strive gravity tailings conveying and shorter transport distance;
(4) There is enough storage capacity. When several tailings fields need to be selected to meet the service life requirements of the concentrator, the connection time and production connection and economic rationality of each tailings should be considered.
(5) From the type of tailings field, the priority valley type and the second type are hillside type, and the flat type is selected only when it is unavoidable;
(6) Strive for a small catchment area;
(7) The engineering geological and hydrogeological conditions of the site are good;
(8) There are enough building materials available nearby.
(II) Determining whether the tailings can be piled up depends on the nature of the tailings. Generally speaking, the tailings have a coarser grain size and a tailing mine with good water permeability. The coarser part of the dam can be used. If the tailings are too fine, the dam is difficult because of the slow consolidation during the filling and sedimentation. Dam the dam or class it with a cyclone and dam it with its coarse particles. Whether the tailings can be piled up with dams, there is no accurate criterion, and the tailings characteristics are generally compared with the tailings of similar mines to determine whether the dam can be stacked and the height of the dam is high. As for the high energy pile, the physics of the tailings should be obtained. The mechanical properties are determined by stable analysis.
Priority should be given to the use of tailings dams. A dam or waste rock dam is used only when the tailings itself cannot be dammed or the tailings dam is uneconomical and unsafe.
(C) dividing the tailings field level (1) when the downstream tailings field will crash important towns, industrial and mining enterprises and rail trunk who suffered severe disasters;
(2) When the engineering geological and hydrogeological conditions are particularly complicated, it is considered to be incomplete after the foundation treatment (the flood standard is not improved). [next]
(4) Calculation of tailings
Only storage capacity calculations, clarification distance calculations, and final stacked elevation calculations are discussed here.
A storage calculation For the sake of clarity, the meaning of various storage names is explained first. It can be seen from Figure 1:

The geometric storage capacity refers to the volume formed by the closure of the initial dam, the stacked dam slope and the topography contour.
The total storage capacity is the geometric storage capacity corresponding to the final accumulation level of the tailings field determined by the total tailings volume, flood control, slurry water clarification and seepage control conditions.
Effective storage capacity refers to the actual volume occupied by tailings in the tailings field, expressed as V _r .
Backwater reservoir capacity refers to the volume of water between the normal high water level and the controlled water level, expressed as V _x .
The flood storage capacity refers to the volume of water between the highest flood level and the normal high water level, expressed as V _T .
Dead storage capacity refers to the volume occupied by water below the water level, expressed as V ₀ .
The free storage capacity refers to the volume between the final stacked elevation and the highest flood level that is not filled with tailings, expressed as V _k . The corresponding height of V _{k of} all tailings should meet the safety requirements.
The storage capacity of the above tailings is constantly changing. [next]
a Calculation of geometric storage capacity The initial dam slope and the pile dam slope are drawn on the topographic map, and the area of ​​each closed contour line is measured by the accumulator, calculated according to formula (1):

In the formula V———the geometric storage capacity, m ³ ;
i———i=0, 1, 2, 3...n, the elevation line number;
j———Close the contour line three times with the amount of the accumulated instrument, and each time the number of the product is read;
k———the area factor of the accumulator, which is related to the scale of the topographic map, given in the specification of the accumulator;
x _ij ——— the i-th elevation jth quadrature instrument reading;
H _i ——— the elevation of the jth contour, m.
b Calculation of the required storage capacity of the tailings mine The storage capacity of the tailings mine should meet the requirements of the service life of the concentrator. The required storage capacity is related to the amount of tailings discharged from the concentrator each year and the service life, which can be calculated according to formula (2):

Where V _z ——— the storage capacity of the tailings required by the concentrator during the production service period, m ³ ;
W———the amount of tailings discharged into the tailings mine each year by the concentrator, t/a;
γ _d ———the loose density of the tailings (ie the average stacking weight), t/m ³ ;
N————The service life of the concentrator, a;
η _z ———The capacity of the tailings storage capacity.
The determination of γ _d is generally determined by reference to the survey data of the tailings or the test data of the laboratory.
The determination of the value of η _z should generally be based on the actual slope of the tailings accumulation, the water on the tailings sedimentation beach, and the underwater alluvial vertical slope. The tailings stacking plan is drawn to calculate the actual accumulation volume of the tailings (the tailings field Effective storage capacity, calculate the tailing capacity of the tailings according to the following formula:

According to the calculation result of formula (2), the storage capacity curve can obtain the stacking elevation required for the tailings.

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