Thick gently inclined ore in a large proportion of phosphorus ore mine, iron ore, the ore body such thickness 4 ~ 15m, tilt angle 5 ° ~ 30 °, due to the presence stope haulage and tall empty field Management and other problems, such mining bodies are difficult to mine and have high transportation costs, especially when the angle of inclination is small and the thickness is small. It is difficult to transport ore by gravity, which increases transportation costs [1-2]. The mines in this type of mine are divided into two parts: mining and mining and pit mining. Excavation and mining are generally carried out by electric shovel, scraper, and loader. With the development of mining industry and the promotion of trackless self-equipment, more and more mines adopt scraper. The mines in the pits are generally transported by truck or rail. The ore-free equipment such as mining trucks has good maneuverability and convenient operation, but the mining cost is high, the rail transportation capacity is large, and the transportation cost is low. It is suitable for long distances. Transportation [3]. The mining of the stope and the mining in the pit are connected by the chute. Therefore, the location of the chute will affect the transportation distance of the two parts, which will affect the total transportation cost.
1 Project Overview
1.1 Geological overview
The eastern section of the Jiaoshuihe Phosphorus Mine is located in the northwest direction of Yichang City, and is about 85km away from the northern edge of the Yichang Phosphorus Mine. It is a gently inclined medium-thick ore body. The main industrial phosphate rock layer (Ph2) is 1.60~14.72m thick. The average thickness is 4.61 m and the thickness variation coefficient is 87%. The overall trend of the ore layer is northeast, the dip angle is 4°~7°, the northwest trend is 3000~5070m, the northeast tendency is 2470~3400m, the surviving elevation is 660~920m, and the buried depth is 81.67～383.99m. The mining section is divided into East I and East II by the Water River and Highway Security Pillars, with a production scale of 1 million t/a. Limited to the terrain, the industrial site is located in the southwest of 1.5km from the mining area.
1.2 Transportation plan
The mining area is developed by Pingshuo slope road, strip filling method, and mining in East I and East II areas. The panel is arranged along the strike, with a width of 200m, a tendency of 100m, and a 20m wide panel of pillars. The stope is mined by a scraper. There is no separate chute in the panel. The ore is loaded by the scraper to the transport truck and transported to the centralized chute. All the ore is unloaded to the motor car through the centralized chute and transported to the motor vehicle by the motor. Industrial site. This joint transportation scheme not only reduces the cost of building a slippery well, but also fully exploits the advantages of mining trucks and electric vehicles.
However, its concentrated chute is located in the southernmost part of the mining area (Fig. 1). This slipping scheme will increase the average transport distance of underground trucks, which is not conducive to cost control. Therefore, it is necessary to optimize the location of the concentrated chute.
2 transportation cost model
The slow-sloping medium-thickness ore body arrangement is different from the usual way of sloping wells. The function of the sloping well in the inclined body with high inclination and high thickness is to slid the ore collected in several stages above the mining level to the mining level and load it out. The chute is the channel for carrying ore by gravity; while the gently inclined thin or medium-thick ore body cannot carry the ore by gravity, and the chute mainly acts as a concentrated ore [4-5]. The trackless transportation distance of the combined transportation and the transportation distance of the electric motor vehicle will change greatly due to the change of the centralized sliding well position, which has a great impact on the total transportation cost.
The ore from each stop is transported to the chute through trackless equipment and then transported by motor to the industrial site. The process is similar to the logistics distribution process, where all products are shipped from the factory to the distribution center and distributed to each customer via the distribution center. Therefore, it can be used to analyze the location problem of the logistics distribution center and determine the location of the concentrated inclined mine body.
2.1 Distribution Center Location Problem
The research on the location of logistics distribution centers has achieved a lot of research results. At present, the problem of location of a single distribution center in continuous space is widely used by differential method [6-7]. The differential method is based on the center of gravity method and obtains a more accurate solution through iteration.
For the distribution center location problem, assuming that the distribution center coordinates are (x0, y0) and the n distribution point coordinates are (xi, yi), the delivery cost H is
Where, ai is the transportation cost from the distribution center to the delivery point i unit mass unit, yuan / (t·km); wi is the transportation volume to the delivery point i, t; di is the linear distance from the distribution center to the delivery point i, Di=
In order to obtain Hmin, seek partial guidance on H,
and so
In equations (4) and (5), the di term still contains x0 and y0. The initial value is first calculated during the calculation, and it is iteratively calculated to the distribution center position coordinate within the accuracy range [8].
2.2 Model establishment
For the location of the well, there are 2 points that are different from the location of the distribution center:
(1) The distribution point is a finite number of scatter points, and the ore body exists in several consecutive spatial intervals.
(2) The distribution route is simplified to a straight line from the distribution center to the delivery point, and the underground transportation route is limited by the roadway, usually a broken line.
Since the engineering drawing adopts the 1980 Xi'an coordinate system, it is not convenient to calculate. A new coordinate system is established with the motor vehicle transportation end point (37509178, 3475300) as the origin. The coordinates of the chute are (x0, y0), and the ore Di ore is transported to the chute. The cost Hi is
In the formula, ai is the unit transportation cost of the Di unit mass ore unit, Yuan/(t·km); Ï is the ore density, kg/m3; h is the thickness of the ore layer, km; d is the shortest amount of ore to the well in the stope Distance, in this case, the ore is transported through a roadway parallel to the coordinate axis, d=x-x0+y-y0,km. The cost of transporting all ore in the mining area to the chute is nΣi=1Hi, and the cost of transporting the ore from the chute to the industrial site is the transportation cost of the electric motor.
In the formula, ad is the unit transportation cost of the unit mass ore of the motor vehicle, yuan/(t·km); W is the total mass of the ore, t; dd is the distance from the well to the crushing station,
Therefore, the total transportation cost is
3 chute optimal position solution
For equation (6), assuming that the centroid coordinate of the stop Di is (xi, yi), then
Where, si is the area of ​​the mining area Di, m2. Therefore
Since such problems are NP-hard problems, it is impossible to directly solve the coordinate value with the smallest cost value [9]. The candidate points can be selected according to the actual situation, and the transportation cost of the alternative points is calculated according to formula (8) to obtain the total cost H. By comparison, the optimal chute position can be selected among the alternative points, and the problem can be appropriately simplified, and the coordinate value with the smallest precision cost value can be obtained by the algorithm.
It is assumed that the transportation cost is linearly related to the transportation distance, that is, ai=a. In order to obtain the position of the well with the smallest total transportation cost, the differential method for solving the problem of the location of the logistics distribution center is used to obtain partial deviation for H and make the value 0. , then the coordinate value at this time is the coordinate of the theoretical cost minimum, ie
Where S is the total area of ​​the ore body, S = Σni = 1si, in this example S = 1.939 × 106m2; k is the ratio of transportation cost of the motor vehicle to the trackless transport unit, k = ad / a, according to the water The actual situation of the mine, a = 2.2 yuan / (t · km), ad = 0.25 yuan / (t · km), k = 0.1136.
The equation can not be solved directly. The iterative equation can be constructed to find a solution that satisfies a certain precision. To determine the initial iteration value and reduce the number of iterations, each stop center centroid can be used as an alternative point, and each preparation can be calculated by equation (8). The total transportation cost value of the selected point, the coordinates of the center of mass of the stope, the area of ​​the stope, etc. can be calculated from the layout plan of the stope, due to the number
According to more, some data are listed in Table 1.
See Table 2 for the order of the total cost of the alternate point transportation after the calculation.
Construct an iterative equation using the secant method:
The two candidate points 1# and 2# with the lowest cost in Table 2 are selected as the initial values ​​of the iteration, and the iteration results are shown in Table 3.
When the iteration reaches k=5, the values ​​of u and v are already small enough, and the point (1883, 1346) is considered to be the minimum point of total transportation cost of the mining area. Since the point is not on the transportation lane, the actual established well position should be in the roadway. Side, so the point on the nearest roadway from the point is the most advantageous. From the stope layout map, the vertical line of the nearest roadway is used. The foot is the most advantageous. The coordinates are (1883, 1340), see Figure 2. . According to the calculation of formula (8), the total transportation cost after optimization of the chute location is 68.118 million yuan, which is the minimum cost of joint transportation, and the initial well location of the eastern section of the Jiaoshuihe phosphate mine is (2109, 707). The transportation cost of the scheme is 8,914,200 yuan, and the optimization plan can save transportation costs of 13.82 million yuan.
4 Conclusion
(1) By analyzing the joint transportation form of the picking river phosphate mine and referring to the solution method of the location problem of the logistics distribution center, the transportation cost model related to the position of the slipping well is established, and the total transportation cost of the alternative point can be calculated by the model.
(2) Solving the coordinate value of the point with the smallest total transportation cost by using the differential method and constructing the iterative equation. Based on the point, the optimal position of the well is selected according to the actual situation, so that the combined transportation can fully exert the advantages of each part and reduce the gentle inclination. The underground transportation cost of medium-thick ore mines provides an idea for similar mine transportation optimization.
references
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Article source: "Modern Mines"; 2016.4;
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