C. Methods and contents of flood calculations The calculation of tailings floods includes designing storms, designing flood peak flows, designing flood process lines and total floods, and performing flood control calculations to determine the maximum discharge flow of flood discharge structures through flood control calculations. This determines the type and size of the flood drainage structure.
The tailings field is a small catchment area with no measured runoff data. The design flood can only be calculated using the rainstorm data. Flood calculations should use a variety of methods and compare them through flood surveys, using calculations close to flood surveys. The hydrological calculation data and hydrographs compiled by the hydrological departments of various provinces and regions are important reference materials for hydrological calculation.
(4) Drainage structures
The drainage structure is an engineering measure to reduce the saturation line of the tailings. Its function is to reduce the wetting line of the stacked dam, so as to prevent the immersion line from escaping on the accumulation slope, minimize the saturation area of ​​the dam slope, enlarge the drainage area, and promote the drainage consolidation of the tailings, thereby improving the stability of the accumulation dam; The tailings within a certain range under the dam slope are drained, which can effectively prevent the liquefaction of the tailings sand and improve the dynamic stability of the piled slope. It can be seen that the drainage structure is an important engineering facility of the tailings field, especially the large and medium-sized tailings mine and the indispensable facilities of the tailing field of the strong earthquake zone.
The design of the drainage facility shall be based on the seepage control conditions required for seepage stability and dynamic stability.
Types and selection of A-drainage structures The drainage of tailings has only been widely adopted in recent decades, and its structural type is still developing and improving. At present, there are roughly two types: horizontal drainage and vertical drainage.
The horizontal drainage is the use of a near-level drainage channel or a horizontal drainage layer, which collects the water seepage and concentrates it out of the dam to achieve the purpose of reducing the saturation line. As shown in which the presence or absence of concrete with structure type tube 10, perforated pipes of reinforced concrete (or cast iron pipe) outer layer filtration, as well as use of filtration rockfill outer layer. Practice has proved that the horizontal drainage infiltration ditch has a good effect in coarse-grain tailings. Under the condition of fine-grain tailings or horizontal fine tailings, the filter layer is easily blocked and it is difficult to reduce the level of fine tailings. The suspended water layer is generally ineffective. [next]
The vertical drainage is to collect the seepage water from the vertical seepage well and discharge it out of the dam. The types of seepage wells are sand-free concrete pipe wells, assembled-type perforated reinforced concrete wellhead outsourcing filter layers, and seepage wells using rockfill outsourcing filter layers. Under the condition that it cannot flow. Some use submersible pumps to pump water. Because the pumping capacity of the pump is consistent with the seepage volume of the well, it is difficult to control. The Dashihe tailings mine uses an inverted siphon to pump water with good results. The Maanshangou tailings mine uses light well point precipitation and has good results.
Regardless of horizontal drainage or vertical drainage, the water seepage that needs to be concentrated needs to be led out of the dam by the drain pipe, and sometimes it may pass through the shallow water zone above the saturation line to prevent the water flow from seeping back into the tailings. .
B Plane layout of the drainage facility The layout of the drainage facility is determined by seepage calculation or seepage electrical simulation test according to the topographic conditions of the tailings, the permeability characteristics of the tailings and the stacking height of the tailings. Generally, the scheme is initially planned according to the general principle, and then calculation or test is performed until the seepage control requirements are met. The general principles for the layout of drainage facilities are:
(1) The drainage facility generally has a drainage effect together with the initial permeable dam. The drainage facility starts from the influence radius of the tailings sand about 1 times of the initial dam dam, and the dam abutment or the dam abutment that does not affect the initial permeable dam The accumulation dam in front of the impervious dam should be arranged at about 0.5 times the radius of influence of the tailings from the initial dam.
(2) The immersion line of the stacking dam generally escapes from the stacking height range of 1/2 to 2/3 (excluding the escape point of the suspended water), so the drainage facility only needs to be arranged within this range, and the tailings are fine-grained. The value of the tailings is large, and the size of the tailings is coarse.
(3) The spacing of the drainage structures is related to the influence radius of the tailings sand, the size of the drainage structure and the depth of precipitation, and generally may be less than 1 times the influence radius.
(4) The intersection of the tailings deposit and the topography, due to the small permeability of the original ground, the seepage is high under this condition. In the area where the drainage facilities are not affected, the abutment of the abutment should be set.
C Design and construction of the filter layer The design of the filter layer should generally be determined by testing and then designed. In the absence of test data, engineering analogy is generally used for design.
a Conditions that must be met by the filter layer (1) The filter material of any layer should not pass through the pores with a thicker layer;
(2) The particles in each layer should not move;
(3) The particles of the protected soil layer should not be carried by the water-repellent layer, but the particularly fine soil particles are allowed to be carried away by the water;
(4) The filter layer should not be fouled, that is, the finely divided soil particles can pass through the pores of the filter layer.
b Filter layer design control method To meet the above conditions, it is recommended to use the following methods to control:
Wherein D 15 is the particle size of the filter material, and the soil smaller than the particle size accounts for 15% of the total soil weight;
d 85 ———the particle size of the protected soil, the soil smaller than the particle size accounts for 85% of the total soil weight;
d 15 ———The particle size of the protected soil, less than 15% of the total soil weight of the soil. [next]
For the following cases, it is recommended to use some of the above methods to initially select the filter material and then determine by experiment.
(1) For the protected soil with a large unevenness coefficient, d 85 and d 15 of the fine fraction of η ≤ 5 to 8 may be taken as the calculated particle diameter.
For the soil with discontinuous gradation, d 15 and d 85 of the granules below the grading curve (usually 1 to 5 mm or less) should be taken as the calculated particle size.
(2) When the sand gravel having the unevenness coefficient η>5-8 is used as the first layer of the filter material 1) D15 of the fine particle portion of less than 5 mm is selected as the calculated particle diameter;
2) The gravel content greater than 5 mm should be ≤60%.
(3) The filter material that cannot be determined by the above method shall be determined by experiment.
The construction of the anti-filter layer is a meticulous work. One is small in thickness and is not convenient for large-scale machinery construction. The other is strict quality requirements, which must be carefully constructed to meet the requirements. Firstly, the appropriate material yard should be selected according to the design requirements, and the required particle size, gradation, uneven coefficient, mud content, etc. should be carefully prepared. At the same time, the basic treatment of the filter layer should be carried out according to relevant specifications and design requirements. Preparation for filling the filter layer. Then, the filter layer is laid and the thickness must be strictly controlled during the filling. Generally, a sample should be set every 10 meters and checked frequently. Sand and gravel should be properly sprinkled, and the adjacent layers must be flattened to ensure that the layers are clear and not mixed. After the filter layer is laid, the protective layer should be filled. During the construction process, the filter material should be kept wet when handling the filter material to avoid particle separation and prevent the inclusion of impurities or materials of different specifications. The paving filter layer shall be carried upwards from the bottom and shall not be poured downward from the slope. When the paving is carried out in sections, the joints between the layers at the joints must be made, and the seams are required to be clear, and no misalignment, breakage or mixing between the layers is allowed. The construction of the anti-filter layer shall be carried out in accordance with the relevant construction technical specifications. After each process has passed the acceptance test, the construction of the next process can be carried out.
The chemical fiber filter cloth is a good substitute material for the filter layer. It is convenient to construct and economical. Now there are a lot of applications in the tailings field design. In the future, the experimental research should be further strengthened to make it more suitable for the tailings filter layer. Design requirements. At present, the application of the filter cloth should pay attention to the water permeability of the filter cloth and the water permeability of the tailings, especially in accordance with the water permeability under high pressure.
(E) the return of many structures tailings beneficiation plant tailings backwater field instead of using the water supply, and achieved good economic benefits, saving energy, avoiding competition for water and farmers, but also reduce the pollution downstream.
Deciding whether the tailings will return water is mainly determined according to the technical and economic comparison, and sometimes it is decided to return to the water according to environmental protection requirements.
The amount of return water from the tailings backwater should be determined by the water balance calculation based on the amount of water, water consumption and water loss.
The backwater of the tailings often contradicts the safety of the stacked dam. The stability of the accumulation dam requires a certain length of sedimentation beach, that is, there is a certain requirement for the height difference between the pool water level of the tailings pond and the top of the pile dam. In order to return more water, it is hoped that the height difference is small, so as to save more water. At this time, the stability of the accumulation dam is the main one, and the return water should obey the requirements of the stability of the dam.
There are different water intake structures depending on the way the water is taken.
(6) Drainage Ditch In order to ensure the safety of the tailings mine and to facilitate the management of the tailings mine, the following drainage ditch should be provided as needed.
A Abutment Drainage Ditch To prevent flooding of the dam slope on the slope above the dam abutment, it is necessary to construct a masonry or concrete drainage ditch on the solid foundation of the dam abutment. The section size should generally be determined by flood calculation and hydraulic calculation.
B dam slope drainage ditch In order to prevent storm runoff from scouring the slope of the tailings field, not only slope protection measures but also dam slope drainage ditch should be set up. Generally, a horizontal drainage ditch is set every 10 to 15 meters high, and flows into the abutment drainage ditch to the two abutments; when the axis of the accumulation dam is long, a herringbone drainage ditch should be provided.
(VII) Management facilities of the tailings mine A Observation facility In order to monitor the operation of the tailings mine, long-term observation facilities are required. Projects of observation facilities include: displacement observation, water seepage and water quality observation, water level observation, saturation line observation and pore water pressure observation. Large-scale tailings should be equipped with more comprehensive observation facilities; other tailings should also set up necessary observation facilities as appropriate.
B Management Facilities To facilitate the maintenance and management of the tailings mine, the following facilities should be properly equipped:
(1) Duty room: including duty room, tool room, equipment room, meeting room, etc.
(2) Machine tools: mainly damming equipment, such as bulldozers, loading equipment and water transportation. Simple maintenance facilities are available when necessary.
(3) Other ancillary facilities: such as roads, lighting, and communication facilities.
For tailings away from the plant, life welfare facilities should be provided when necessary.
Belt Conveyors
Established in 1976 in China, JUXIN, are considered as the first Conveyor and components: roller, frame, pulley manufacturer in Hengshui, China. The rapid growth of the business in China soon created the need for a distribution depot, therefore in 2007 a new branch was put in place in Tianjin City The modern day JUXIN now manufactures conveyor products to suit all supplies of mining, steel plant, cement plant, quarry, crushing and screening equipment. Our expertise and knowledge allows us to deliver fully on our promises of providing quick answers to your enquiries, rapid service, high quality products and above all, we are fully committed to be the best at what we do Service Agents are also located in: UK, South Africa, Kenya, Indonesia, Thailand, Kazakhstan All products are underpinned by unmatched customer service and prompt, reliable delivery. Our internal quality systems are designed to ensure that all orders are handled quickly and are manufactured to the ultimate quality standards. Several checking processes are in place prior to orders being released from the factory. Many tightly controlled inspections occur during the production processed.
Belt Conveyors,Mining Belt Conveyor,Overland Belt Conveyor,Troughed Mining Belt Conveyor
Hebei Juxin Conveyor Engineering Co., Ltd , https://www.jxconveyor.com