Coal Preparation Equipment Classification
Equipment to get more quickly developing: dense medium cyclone, dry separator, jigging screen jig, micro-bubble column flotator (flotator), dense medium scrape separator etc.
Equipment to get slowly developing: jig, flotator, dense medium drewboy both separator, spiral separator etc.
Equipment not to get development: spiral drum separator, water medium cyclone, shaking table etc.
Dense medium cyclone
Conventional DSM dense medium cyclone has the advantage of separation precision. It commonly is used to separate fine coal of difficultly separation. In recent years, its development is faster, its techniques gradually mature, and its application is more and more. Big diameter (l 000 mm) dense medium cyclone, no-pressure feeder dense medium cyclone (LARCODEMS), three-product dense medium cyclone are noticed by the plants.
The development of dense medium cyclone mainly shows in four aspects: big diameter, unclassified washing.
No-pressure feeder, reducing second slime.
Three-product, circuit simplification.
Long life-time, decreasing maintaining cost.
Biggest diameter of two-product dense medium cyclone made in China is 1 300 mm, its capacity is about 550 t/h. There are two kinds of pressure feed cyclone and no-pressure feed cyclone. Now, diameter of two-product dense medium cyclone to be applied widely in domestic plants is between 660 mm to 1 000 mm. Biggest diameter of import dense medium cyclone is 1 500 mm, its capacity is about 800 t/h.
Three-product dense medium cyclone gets widely development in China. Development and application of three-product dense medium cyclone in China locates on top of world development, especially no-pressure three-product big diameter dense medium cyclone. Diameter of pressure feed three-product dense medium cyclone is 1 400/1 000 mm, design capacity is 550 t/h. Biggest diameter of no-pressure feeder three-product dense medium cyclone is 1 400/1 000 mm (Panjiang Laowuji coal preparation plant), design capacity is 500 t/h. It makes circuit simplification, and promotes application of dense medium separation circuit in China.
Basket screen jig
Basket screen jig is used to removal gangue from block coal. It has shown its advantage in condition of 300~50 mm raw coal as following: quantity of removal gangue is big, consumption water is little, system is simple, malfunction rate is reduced. Basket screen jig is a necessarily assemblage facility in course of block coal removal gangue in every mine of Yanzhou district. Now, there are many mine areas to concern using basket screen jig to removal gangue, the development trend is rapid.
Basket screen jig made by Germany KHD company adopted hydraulic drive, biggest area is 4 m2 , capacity is 300 t/h. Yanzhou Xinglongzhuang coal preparation plant used two ROMJIG20500808 types basket screen jigs to treat with 300~500 mm block coal, I value is 0. 097, its capacity is 70 t/m2 • h, gangue ash is above 80%.
Basket screen jig by domestic production has two types of hydraulic drive and machine drive. Biggest area is 3. 6 m2. The capacity is 200 t/h. Effect of hydraulic drive jig is better, but the jig is easy to bring about faults. The hydraulic drive system also needs to be import. Structure of machine drive system is simple and credible, fits to Chinese operation level and managing level, is more welcome by coal preparation plants. But it has some disadvantages of more loudness and not easy to adjust on line. The price of basket screen jig by domestic production is less than one of import jig.
Dry separator is used to separate easy or middle processability coal, and to remove gangue from power coal, to enhance quality of inferior coal, to desulfate for coal gangue, to separate coal of cold district and easy to slime etc. From early wind shaking table and wind jig to recent air dense medium separation and compound dry separation, their application techniques gradually mature. Now, there are two kinds of compound dry separator and air dense medium dry separator to be used in China.
Air dense medium dry separation utilizes the characteristic of air and solid fluidization state being seem as fluid. The fluidization state has stationary suspension substance of air and solid to have definite density, makes light material float, heavy material sink, lower limit size is 6mm, and request exterior moisture of coal less than 4%. Air dense medium fluidization separation locates in advanced level, but the result of practice application is not well. Main reasons: moisture of coal from machine mining is high, and difficult to reach request of moisture less than 4%, raw coal difficultly classification at size 6 mm; it requests narrow medium size, content of 0. 3 ~ 0. 15 mm material is more and more well.
Content of below 0.074mm material is less and less well. The medium with size distribution is difficultly prepared. Otherwise, reliability of separator must be enhanced as well. Due to above reasons, the device is not largely applied in China, still locates in research stage.
FGX series compound dry separators and FX series wind dry separators get largely application in China. The two kinds of devices utilize the advantages of shaking table and wind separation, have great practicability, and need less invest, invest every ton coal is 3~6 Yuan; cost of coal processing is less, processing cost every ton coal is 2~3 Yuan; size of feed coal is 6~75 mm, moisture of feed coal is less than 7%. Ash of clean coal reduces less about 5%~10% than one of raw coal. Though coal below 6mm can hardly separates in separator, some information has shown there is some fine coal in feed coal to improve separation effect of rough size coal. When content of below 6mm coal is about 20%, ash of above 6mm coal is reduced to lowest. Because of this feature, 80 ~0 mm raw coal may not classify separation, so that makes circuit simplification.
Disadvantages of dry separator:
- Low separation precision, Ep value is 0. 2~0. 23, caloric of coal can be enhanced about 0. 837 – 67 MJ/kg, dry separator is suitable to material with more heavy separation density or used to remove gangue, but there is much coal in gangue. It is not suitable to difficultly separation coal or low separation density coal.
- Exterior moisture of coal below 7%, otherwise, separation effect will become worse. If exterior moisture of coal is above 9% , it may be not used.
- Capacity of every hour is less, at present, maximal capacity is 10 t/m2 • h, maximal separation area of dry separator is 12 m2.
FGX and FX series dry separators have been generalized in China when it is as a complementary method of wet separation. The dry separator has well foreground of application for water shorten and enterprises to request low quality coal.
Micro-bubble flotator (column flotator)
Flotator has been using to treat with below 0.5 mm fine coal. Large flotator was born in 70 generations 20 century. Recent years, development and application of flotator slowly become, flotators used in domestic plants all are flotators to be born in the period of 90 generation or before, for example, XJX, XJZ, XJQ, XJN, XJM-S and XPM series. At present, coal preparation plants mainly use agitation flotators, and its volume has become large, maximal volume is 16 m3.
Micro-bubble flotation is a trend of development in future. Recent years, micro-bubble flotator introduced from Germany KHD company has the capacity of 400 m3/h (slurry). Pingdingshan coal preparation plant and zhuzhou coal preparation plant corporately developed and manufactured Ф3 m and Ф2 m micro-bubble flotators. The flotator adopts the way of absorbing air to combine press air with jet air, strengthen micro-bubble mineralization. Ф3 m micro-bubble flotator capacity of single trough is 200 ~250 m3/h, dry slime capacity is 15~20 t/h, ash of clean coal is less than one of agitation flotator, ratio of performance and price is higher than the same import devices and other types of flotators. The flotator has widely application foreground.
Column flotator is used to treat with fine coal. In recent years, it has largely development. Column height is largely fallen by gradually improving. Selectivity of the flotator to fine coal is well, for instance, addition spraying water in flotation froth layer. Ash of clean coal is less 1~1. 5 percent points than one of flotator. At present, coal preparation plants mainly use FXZ series static column flotator and FCSMC series circle-static micro-bubble column flotator in China.
Diameter of FXZ series static column flotator is 1~3 m, height is 6~9 m. FCSMC series circle- static micro-bubble column flotator has two series of column flotator and flotation bed, column height is 5. 5~6 m. When capacity is same, flotation bed needs less area.
Disadvantages of column flotator as following:
- Selectivity for rougher slime is not well, when content of rough size material is higher, there is phenomena of rough coal lost in gangue;
- Consumption of reagents is more than one of normal flotator;
- When spraying water in froth layer, because of concentration of clean coal becomes little, particle of coal becomes fine, dewatering of clean coal becomes difficult. At present, there are ten column flotators to be used in coal preparation plants in china.
Dense medium separator
The coal preparation plants mainly use dense medium separators to treat with block coal in china, for example, Drewboy separator and vertical lifting wheel separator in 80~90 generations 20 century in china. Pingshuo Antaibao coal preparation plant first introduced dense medium scrape separator from the America in 90 generations 20century, used it to separate 150~13 mm block coal. Because the separator has some advantages of simply operation, easy to maintain, low invest and high efficiency etc, it is
quickly received in China. With development of homemade parts and whole devices, it is gradually popularized and applied, and may take replace drewboy separator and vertical lifting wheel separator. At present, coal preparation plants mostly adopts dense medium scrape separator and basket screen jig to separate block coal in new coal preparation plants in China. Dense medium scrape separator is prior to basket screen jig in price and separation precision. It also is prior to block jig in separation precision, low over—break rate and less coal in gangue.
At present, most coal preparation plants in China use dense medium bath separator made by the America BERDSI company. Quantity of removal gangue is 250~300 t/h, width of bath is 2~7 m. At present, there are a few homemade dense medium bath separators to be used in china, but technical parameters are almost same with ones of oversea device.
Jig has been using in Chinese coal preparation plants. The application of jig have gone through courses of development, improvement and mature from concrete frame jig to under-screen air jigs with magnetic-electric valve, automation removal gangue system, ultrasonic bed measure and brainpower electric control system. At present, with the popularization of dense medium separation techniques, application proportion of jig separation is gradually reduced, development and innovation of jig also becomes slow. Now, main development trend of jig has a few aspects as follow.* large, brainpower, and to enhance capacity, separation precision, sensitivity and veracity of control device, precision of measure device and reliability of jig. At present, there are homemade X series jigs and SKT series jigs to be mostly used in China, there are a few CT series jigs, LTG series jigs and BM series jigs. Jigging area of X series jig is 4 ~ 45 m2 , jigging area of SKT series is 6 ~ 24 m2. There are BATAC jigs from the Germany. The jig is prior to homemade jigs in performance and reliability, but its price is higher than homemade jig, now the jig is hardly used in China.