Coal Preparation Accessorial devices
Quickly development devices: screener, dewatering devices for slime ( adding pressure filter, diaphragm pressure filter) etc.
Slowly development devices: dewatering centrifuge for fine coal, breaker etc.
No development devices: dreg slurry pump etc.
The coal preparation plants normally use various screeners to complete courses of classification, dewatering and medium drainage screen. Circular vibrating screen is mostly used to screen above 50 mm raw coal. Linear vibrating screen, banana screen, bar screen and probability screen are mostly used to screen 50~13 mm coal. Bar screen, string screen and relax-close screen are mostly used to screen 6 mm or more fine coal and exterior water high coal.
Dewatering and medium drainage of coal preparation products mostly use linear vibrating screen. Chinese coal preparation plants often use the way of camber screen + linear vibrating screen to remove medium. In recent years, high frequency screen is largely used for dewatering of coarse coal slime, banana screen is largely used for medium drainage of coal preparation products.
Now, research trend of screener mainly has three aspects:
- Adding screen area, enhancing capacity.
- Enhancing reliability of screen operation.
- Increasing screening efficiency.
YA series circular vibrating screen and ZKX series linear vibrating screen made Chinese screening techniques stride new stage through introduction screen manufacture techniques from the America RS company in 80 generations 20 century. Due to introduction manufactory techniques of USK series-circular vibrating screen, USL series linear vibrating screen, YK/YKR series circular vibrating and ZK/ ZKR series linear vibrating screen from the Germany, it makes Chinese screeners add some new sorts in 90 generations 20 century. At present, they are still main screeners in Chinese coal preparation plants. In recent years, reliability of homemade 3m screener and other screeners has been enhanced. Beijing Huayu Engineering Company manufactures successfully 2ZKP3660, ZKZ3660 vibrating screens (width of screen 3. 6 m) on bases of completing the project of “study on reliability of large linear vibrating screen”. These screeners have been applied in Pingdingshan coal preparation plant and Yanzhou Dongtan coal preparation plant for three years. They have almost same potential than oversea screeners.
Because of screening of fine coal being difficult, researchers take a lot of research work on screener of coal deeply screening. There are banana screener, postgraduated screen, string screen, relax-close screen, bar screen, multi-free spring vibrating screen etc. Bar screen, postgraduated screen and banana screen get quickly developing. Postgraduated screen is largely applied in plants in recent years, practice dates from Shanxi Daning mine and Huainan Sheqiao mine demonstrated that the screener has higher capacity and screening efficiency for 6 mm(8 mm) coal.
Trend of banana screen to be used medium drainage is increasing, after Zichenghzhuang and Majiliang coal preparation plants introduced oversea whole screeners. Banana screener has some advantages of high capacity of drainage medium, less quantity of devices, which is propitious to simplify circuits of large coal preparation plants. But there is some problem, for example, some designated medium of first stage into dilute medium of second stage, so that results in unsteadiness of medium circulating system. Banana screeners of width 3 m and above 3 m used in practice production all are imported from oversea. Homemade large banana screeners still are in stage of development and improvement. Banana screeners with 3 m or 3. 6m width will become main products in market.
Using high frequency vibrating screen to take primary dewatering for 1. 5~0. 2 mm material, than material of mixing with 13~1. 5 mm fine coal enters into centrifuges, the techniques is one of methods of coarse slime dewatering of application in coal preparation plants in recent years. Therefore, high frequency vibrating screener gets recognition and development. Reliability and capacity of homemade high frequency vibrating screener are inferior to same kinds of oversea products, but it is prior to import products in price.
Vertical centrifuge and horizontal centrifuge are widely used in fine coal dewatering. Many plant improved the centrifuges. The development trend of centrifuge is to increase diameter and capacity, to reduce moisture of products. Since long time, horizontal centrifuge is slowly popularized. Innovation of vertical scraper centrifuge is made less.
VM series horizontal centrifuge made by CMI company, FC series slime centrifuge made by Ludowici company, HSG series horizontal centrifuge made by TEMA company and H series slime centrifuge have gradually been recognized in Chinese coal preparation plants. Homemade horizontal also get quickly developing. WZT1400 horizontal centrifuge manufactured by Beijing Huayu engineering company has been applied in Yanzhou Dontan coal preparation plant. Application effect of homemade LLL series coal slime centrifuge is well, rate of performance to price is prior to same oversea centrifuge.
Screen-bowl centrifuge has disadvantages of high balance, a great of maintain, big area and high power consumption, so that its application is gradually reducing in China.
Adding pressure filter and diaphragm pressure filter
Screen-type coal slime dewatering devices have large progress with impelling of import devices. Since 90 generation 20 century, Daliuta coal preparation plant and Tianzhuang coal preparation plant introduced adding pressure filter from the Austria Andritz company, due to advantages of a great lot of capacity, low moisture of products and relax easy to mixture, the device gets popularization in China. After homemade adding pressure filter is successfully manufactured and put into application, through gradually improving, its performance is the same as import devices, and some techniques is prior to import device. Quantity of using adding pressure filters in China is most. At present, adding pressure filter has become series products, and go forward to development of reducing cost and increasing reliability.
Fast diaphragm filter also got quickly developing in recent years, due to having advantages of shorten circular period, high capacity and low moisture of products, is recognized. Plate-and-frame filter still is largely used to recovery slime in coal preparation plants.
There are many kinds of breaker in common use in Chinese coal preparation plants. Difference types of breaker have their respective application scope. With large-scale of coal preparation plants, breakers also go forward to large-scale development. High capacity, simple assembling, reducing height and increasing reliability of operation are targets of researching breakers. Breakers are mostly used from the America, the Australia, the Germany and UK in domestic plants. Homemade FP, 2PGL series classification breakers or intensity breakers have gradually become main devices.
FP series breakers have the advantages of high breaking strength, large capacity, over size, little over-breaker and having ability to treat with wet and clay material, and with automation control device, easy to bring into central control, high reliability. FP 500 classification breaker is mainly used in raw coal and clean coal breaking in plants, also may be used in raw coal of mine breaking and stone material breaking. Upper size of feed material is 400 mm, little material to 500 mm. Discharge size are 40, 50, 80, 120, 150, 200 mm. It may break coal stone and middle strengthen stone. If system adopts some measures of removal iron and timber, raw coal does not need pre-screening and hand separation, so that simplify circuits, fall workshop heighten, reduce construction invest and production cost of coal preparation plants.
Dreg slurry pump
Dreg slurry pump is used most in coal preparation plants, used to transfer various of slime water and medium, maximal size of transferring material is 50 mm (dense medium cyclone feed pump), content of solid may reach to 1 900 kg/m3 (designated medium). Dreg slurry pump is one of key devices to effect on separation for dense medium coal preparation plants.
Woman pump of production by introducing techniques from the Australia and homemade dreg slurry pump of design on bases of two fluids theory are most products in domestic coal preparation market. Woman pump has advantages of wider via size, be able to transfer big size material, well wearable performance, long use period etc. but the pump has mass weight, and a little low efficiency. The series pump design on bases of fluid theory has advantages of small volume, high efficiency and long use period due to adopting high chrome wearable material.
Evaluating pump performances has a few key indexes, for example, wear, seal, operation point stationary, efficiency and malfunction. In recent years, homemade dreg slurry pump has large progress in above aspects. Long practice demonstrated that performance index of homemade dreg slurry pumps has reached to or over international advanced level. Therefore, in recent years, Chinese coal preparation plants hardly import pumps.