For the burning active lime, the rotary kiln has the following features and advantages compared with other forms of rotary kiln.
(1) In the course of the burning, the temperature of combustion apparatus is easy to control. So the quality of calcining is good, and the activity degree of lime could reach 350-400ml with low pollution. (2) The rotary kiln could calcine the materials with smaller grain size(over 5mm), increasing the use ratio of the materials. The products could be used in converter steelmaking without the crushing process because of small size of materials (generally 20-50mm). (3) The mechanization degree of rotary kiln is high, and the operation process is easy to control. The productivity is large, which is suitable for the requirements for the metallurgy, smelt and other large-scale industries. (4) The rotary kiln system has many machines with large weight. So the steel dosage is large and the investment cost is much. (5) The materials wear greatly in the rotary kiln. And the products have much powder, so there is certain requirements for the strength of raw materials. For the EPC companies, they would choose the suitable mining equipment to complete the project in shortest time. And the rotary kiln is also the common equipment for the EPC companies.
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The scraper conveyor is a large-scale conveyor device, using scraper chain traction to convey materials. It is a kind of mining equipment. Sometimes, the screw conveyor would coordinate with scraper conveyor. The scraper conveyor consists of hand piece, middle part, drive end unit. The scraper conveyor could be applied in horizontal transportation, also inclined transportation. If the scraper conveyor conveying the materials in upward direction, the coal bed pitch could not be over 25 degrees. If the scraper conveyor conveying the materials in downward direction, the coal bed pitch could not be over 20 degrees. If the coal bed pitch is very large, the anti-skid device should be installed. The principle of scraper conveyor is that the chute is the support of the materials and the scraper is regarded as the driving component. When the scraper conveyor is started, the chain wheel is driven to rotate. The main conveyor components of scraper conveyor includes scraper, chain wheel, middle trough, dumbbell, clapper, chain stripper, reducer, sprocket assembly, back plate, belt pulley, guide block and etc. The pipe conveyor is the special belt conveyor developed from troughed belt conveyor. It is developed through compelling force on idler sets to the pipe form, in which the materials are sealed in the pipe. In this way, the materials could be protected in the pipe and this pipe conveyor reduces the pollution to the environment. In general, pipe conveyor coordinates with the screw conveyor. The pipe conveyor has the following features: (1) The pipe conveyor is similar to the normal belt conveyor. It is easier to be accepted to the most users. (2) The pipe conveyor could prevent the other things sneaking into the materials. According to its principle, the pipe conveyor could realize the sealing conveying, avoiding the materials escape in the course of transportation. (3) The pipe conveyor could be set in flexible way, realizing the space turning. In this way, some investment costs could be reduced. (4) The large inclination conveying could be realized if using the pipe conveyor. The maximum degree of normal belt conveyor could reach 18 degrees, while the inclination degree of pipe conveyor could be larger than 18 degrees. This is because the friction force between materials and belt conveyor becomes large. (5) The pipe conveyor could realize conveying materials in two ways. (6) The frame of pipe conveyor has small width. However, the conveying area of pipe conveyor is almost same as that of normal belt conveyor. In this way, some cost of rolled steel could be saved. 1. The purpose and significance
The belt conveyor is the main equipment handling the bulk materials. Belt conveyor is widely used in metallurgy, chemical industry, mining, power plant, ports and other industrial fields. With the development of economy and technology, the belt conveyor develops in the direction of long distance, large volume, high speed. Especially in the mining equipment field, more and more belt conveyors are applying in conveying materials. To reduce the investment cost of forwarding station, the belt conveyor with horizontal curves is designed and manufactured. 2. The development situation of belt conveyor with horizontal curves According to some statistics, a belt conveyor with horizontal curves was launched to working in Algeria iron mine site in 1970, with length of 2385m, lifting height of 121m, conveying volume of 1000tons per hour. A coal belt conveyor with horizontal curves was launched to working in South Africa in 1978 with length of 3.5 km. After that, France, Austria, Germany, America and other western countries took part in the research and experiment. Especially for France, Germany, they successfully designed many belt conveyor with horizontal curves, receiving good economic benefit. 3. The calculation key point of belt conveyor with horizontal curves The running resistance coefficient adopts 0.030~0.045. For the present situation of domestic industry, the 0.035~0.040 is suitable. The driver element, tension element, the feeding part must be located in the straightway of belt conveyor. And the calculation of turn radius could adopt the following method. R≥〔T1e(α/β)Φ〕/β (m) 4. Some measures of realizing the horizontal curves of belt conveyor The conveyor roller should be lifted by fixed angle. This angle is calculated out according to the theoretical formula. However, in the practice, this calculated angle is inaccurate. So we could set the adjustable device to help us adjust the angle in the fixed range. The better device is bayonet type. The screw conveyor is a kind of conveyor equipment without flexible components. The screw conveyor conveys the materials through the screw blades in a certain direction. The screw conveyor has features of simple structure, small cross-sectional area, good sealing property, safe operating and flexible processing set-up. The screw conveyor is usually used in machine tool, construction materials, chemical and grain fields. The drawing technology of screw conveyor will be introduced below in detail. 1. The external diameter of screw, screw pitch, blade sickness, the diameter of hollow axle will be confirmed. Then the blank dimension of the bade will be figured out. 2. Then the blades will be welded together. When a set of blades are compacted, the inner hole of the blade is located with a dabber, avoiding the dislocation among blades. 3. According to the unfolding dimension of welded blades, the inner bore and top circle are processed. When processing the top circle, the spot welding should be removed. Otherwise, the blade could not form itself in drawing machine. 4. The first blade and end blade are separately fixed in the drawing machine. Starting the drawing machine, the blade could be drawn to form the shape. The above is about the process of screw conveyor blade. In the following blogs, there will be more introduction about stacker reclaimer, belt conveyor, apron feeder and other conveyor components. With the development of coal mine production mechanization, the belt conveyor is more and more widely used in the coal mine. Then let us discuss some problems of belt conveyor design and some reformations. The site environment of coal mine is complicated. Some large inclination conveying and other problems are inevitable. So small radius of curvature should be solved through adopting related measures. If belt conveyor transport materials in large inclination, some materials would fall down and sometimes may hit the workers. Besides the materials escape situation is serious, and this increases much work to the workers. After detailed study and many times' practice, material escape protection has been created with waste steel plates, box iron, steel tube. Belt damping device and other conveyor components have been created to solve this problem. These device is installed in the place of the large inclination, effectively controlling materials escape and reducing the risk of hitting people. This belt conveyor design is widely applied in users scheme of our company. In general, belt conveyor coordinates with the stacker reclaimer to complete the handling process and pipe conveyor. In fact, the pipe conveyor is a kind of belt conveyor. The improvement on technology of these machines is a big challenge for the designer. As we all know, as one of the mining equipment, the belt conveyor has many ways of prolonging the service life. And a good belt conveyor design counts a lot. Usually the belt conveyor coordinates with the stacker reclaimer. There are keys to successful preventive maintenance that can be summed up in two words, “Good Housekeeping”. Good belt conveyor and idler maintenance begins with “Good Housekeeping”, the master key to getting the highest return on your conveyor dollar. We have found the following procedures play a prominent part at almost every installation where high standards of maintenance are achieved. They provide excellent guidelines for any operator. 1. inspection – The key is timing and who does it. It should be done daily and ideally performed by the Maintenance Superintendent or the Foreman. 2. prompt repairs – Repairs should be made as soon as possible after reported – daily if possible. 3. conveyor records – keep a brief outline history of each conveyor noting such things as the original idler and belt specifications, tonnage records and major repairs or changes. This information is invaluable when reordering components. Problem areas can be readily identified and equipment manufacturers can be consulted about desirable changes in specifications when replacements are needed. In addition to the general tips provided above, we will treat the major areas of conveyor idler maintenance in detail. 辑. The pipe conveyor(tubular conveyor) is the special belt conveyor developed from troughed belt conveyor. It is developed through compelling force on idler sets to the pipe form, in which the materials are sealed in the pipe. In this way, the materials could be protected in the pipe and this pipe conveyor reduces the pollution to the environment. However, the pipe conveyor has some disadvantages. (1) The pipe conveyor should be equipped with conveyor belt through special manufacturing. The edge of conveyor belt is different from the general belt conveyor. So this feature must be considered in the designing and manufacturing. (2) The materials are conveyed in the pipe, which increases the extrusion force between materials and conveyor belt. So the resistance coefficient of conveyor belt is larger than that of general belt conveyor. (3) The conveying value is smaller than that of general belt conveyor (4) The design calculation is complicated. Because the structure of pipe conveyor is more complicated than that of general belt conveyor, the designer faces the challenge of design calculation. (5) The pipe conveyor will not be off tracking, compared with the general belt conveyor. However, the belt twisting problem will occur in the pipe conveyor. Although there are above disadvantages in the pipe conveyor, the pipe conveyor has many outstanding advantages such as conveying materials in sealing condition, easy space curve, small space usage. The pipe conveyor has been widely used in cement, steel, chemical, grain and other fields. At the same time, pipe conveyor is usually connected with stacker reclaimer to complete the process of conveying materials to the other places. With the development of coal mine production mechanization, the belt conveyor is more and more widely used in the coal power plant. Then let us discuss some problems of belt conveyor design and some reformations. In the mine excavation, how to solve the non-interaction of conveyor and track conveying, reduce the cost of equipment? The good belt conveyor design is necessary. Because of the complex geological structures, there would be crossed roadways in the coal mine. Then the belt conveyor design should solve the difficulty of crossed lapping technique. There are two ways advised. The headstock of belt conveyor is transformed. Prolonging the roller support frame and increasing the height of headstock foundation realizes the control of height of conveyor belt and baseboard, achieving the purpose of no interference among conveying materials in rail and conveying materials by conveyor belt. The second way is on the basis of the first way failure. The end of belt conveyor would be lower through dinting, making the conveyor belt pass under the rail to achieve the purpose. In this way, the belt conveyor design could solve this problem. And in the following blog, there will be more introduction about the improvement on pipe conveyor. The magnetic separator is one of the mining equipment. It is the main equipment in the production line of magnetic separation. The efficiency of magnetic separation is the hot issue for manufacturers and users. How to increase the efficiency is very important technological problem. There is some advice from NHI. 1. The usage of machine for blending material The magnetic separator completes the magnetic separation through the magnetic force. If the material layer is thick, the effect of magnetic separation will be bad. So the users could increase the magnetic separation efficiency through the machine for blending materials. 2. The height adjustment of material distribution board The height of material distribution board influences the effect of magnetic separation. When the height of material distribution board is low, the lean magnetite could not recycled better, reducing the use ratio of ore resources. When the height of material distribution board is high, the gangue mineral could not be fully casted, influencing the effect of magnetic separation. So the users should adjust the height of material distribution board to the best location, getting the best magnetic separation efficiency. 3. Adjusting the distance between material distribution board and magnetism barrel Experiments have shown that smaller distance between material distribution board and magnetism barrel result in lower recovery rate of lean magnetite, greatly reducing the use ratio of ore resources. The distance adjustment could help the gangue be fully casted, ensuring the recovery rate of dry separation. |