Stock yard and material pile related parameters

1. Determination of the capacity of the stockyard equipment Mainly determine the capacity of the stocker and the reclaimer A The daily usage of ore Q ₁ =Q/365 _η (1-1)
Q-ore annual demand, t/a;
Q ₁ — daily ore usage, t/d;
η- between beneficiation plant or crushing rate.
B Equipment hourly average capacity Q ₂ =Q1/24η ₁ (1-2)
Where Q ₂ -- equipment hourly average capacity, t / h;
η ₁ — Equipment operating rate, stacker and reclaimer operating rate is generally 0.85.
C Equipment nominal capacity Q ₃ =1.1 × Q ₂ (1-3)
Where Q ₃ — the nominal capacity of the equipment, t/h.
2. Storage time of stockyard storage time, because the specific conditions of each concentrator and mine are different, such as the distance between the concentrator and the mine, the type of ore, the transportation conditions, etc., so the storage time of the stockyard is also different. There are differences and need to be considered according to specific conditions.
3. Cross-section shape of the pile The pile shape of the pile can be piled in adult shape or trapezoidal shape. When determining the section of the pile, it should be considered together with the factors such as pile height, pile width and material angle of repose, and the stockyard of the bridge type reclaimer is used. The following sections can be considered for the cross section of the pile, as shown in Figure 1.

Figure 1 Cross-sectional shape of the pile 1. Bridge type reclaimer; 2. Discharge belt conveyor; 3. Material pile [next]

(1) The bottom edge of the pile section is at the same level as the material floor. The advantage is that the construction work is small, but the cross-sectional area of ​​the material pile is small. See Figure 1a
(2) The bottom edge of the pile section is lower than the material yard ground. The advantage is that the storage capacity can be increased, but the engineering quantity is increased. See Figure 1b.
(3) Add a retaining wall on both sides of the pile, and the height of the retaining wall is related to the reclaiming equipment. This form can increase the storage. See Figure 1c.
4. Determination of material height The height of the pile is related to the width of the pile, the length of the stacker arm selected, the pitch angle, and the angle of repose of the ore. In addition, it is also affected by the endurance. When the endurance is not enough, the ground can be treated or piled up to the required height. For example, the Baosteel raw material yard is built in the lower reaches of the Yangtze River, and within 60 meters below the ground is clay or Asian. clay silt layer, a high moisture content, only 8 to 10 tons of natural endurance / m 2, so that in addition to coal yard, are used sand pile. In order to reduce the initial impact load, the method of gradually increasing the height of the pile is adopted. For example, the height of the pile at the initial stage of the coal yard is 12 meters, and it is used for a period of time. After two months, it is piled up to a design height of 16.8 meters. The initial height of the ore yard is 6 meters. After half a year, the pile height is increased to 9 meters. Only one year later, the pile height is allowed to reach 3 meters or 12.4 meters.
5. Calculation of material pile length The pile length is calculated according to conditions such as ore storage time and storage capacity.
The calculation method is as follows:
Necessary storage capacity of ore (wet weight) Q ₄ :

Where Q ₄ - ore storage (wet weight), t;
Q ₁ —the average amount of ore (dry weight), t/d;
T — storage days, d;
W—the average water content of the ore, %.
Ore storage volume V=Q ₄ / γ (1-5)
Where V is the storage volume of ore, m ³
γ - ore loose density, t / m ³
Assuming there are N stockpiles, the volume of one stockpile is:
V ₁ =V/ N Ñ„ (1-6)
Where V ₁ is the volume of a pile, m ³ ;
N—the number of piles;
Ф—The operating factor at the time of stocking is generally 0.75~1.
One pile length

Where L ₁ - the length of a pile, m;
V _R - the volume of the end stock, m ³ ;
S ₁ — the cross-sectional area of ​​the pile, m ² ;
R—end stack radius, ,m
Total length of ore pile L _n =∑L ₁ (1-8)
Where L _n — the total length of the N piles, m
For a pile with a triangular cross section, one pile length calculation can be performed as follows

In the formula ф — the operating factor when stocking, related to the form of the pile, ф=1.0 for the ore and mixing pile; [next]

B — the pile width, m;

a — ore angle of repose, (°);
H — pile height, m;
The rest of the symbols are the same as before.
6. Calculation of parameters related to herringbone stock pile The relevant parameters of the herringbone stock pile are calculated as follows:
(1) Material storage (excluding end material)

(2) Number of layers in the pile

Substituting Q ₅ into (1-12)

Therefore

(3) Thickness of materials in each layer in the vertical direction

[next]

Figure 2 Basic parameters of the herringbone pile

(5) The height of the apex of each layer is from the ground

Where Q ₅ - stockpile storage (excluding end material), t;
Q ₆ — the amount of conveyor belt conveyor, t/h;
Q _R - end material amount, t;
q — the amount of material per unit length per unit, t/layer • m;
L ₁ — length of stock pile (excluding end material), m
B — pile width, m
H — pile height, m
γ - ore loose density, t / m ³ ;
υ — stacker walking speed, m / s;
n — the number of layers of material;
h _n — the height of the nth layer of the pile to the ground, m;
δ _hn — thickness of each layer in the vertical direction, m;
a — ore angle of repose, (°);
R — the radius of the end material, , m.
Some of the conditions are assumed in the above calculations, such as the stacker operating within the length of the pile, which runs at a constant speed in either the forward or reverse direction. The stacker stacks the material in constant stacking time per unit time during the stacking process.

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