Introduction of coarse slime screening process and equipment Henan Hongxing


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Introduction of coarse slime screening process and equipment

Screening process is an important processing link in screening plant and coal preparation plant, mainly for coal particle size classification, dehydration, desliming and demineralization. Through screening, the water content of coal preparation products can be removed and reduced, and water resources can be recycled; fine slime can also be removed to reduce the pollution of coal slime to the medium system, and the pollution of high ash fine mud to clean coal products; the viscosity of washing water of subsequent washing equipment can be reduced, which is conducive to the separation of fine coal, so as to improve the separation efficiency.

At present, the main equipments used for coarse slime dewatering and classification in coal preparation plant are as follows Roller screen The drum screen is not easy to block, and easy to install cleaning screen; stable operation, can be closed, low noise, no splash, good working environment; simple structure, convenient maintenance, low power consumption.

 Roller screen

1、 How it works

The drum screen mainly adopts the principle of cross flow filtration. The material is fed into the rotating screen cylinder through the feeding device, and the coarse particles rapidly settle on the inner wall of the drum screen. Due to the rotation of the screen barrel, the material layer settled down on the inner wall moves upward and rolls up, which makes the resistance of the upper suspension significantly reduced and the screen is quickly penetrated. The solid particles that are not screened are guided by gravity and spiral In this way, the filtrate will flow down the screen slot and the material layer will be led out axially by the spiral blade.

2、 Screening system

The main working device of coarse slime dewatering is a drum screen with a diameter of 30m and a length of 50m. The screen gap is 0.125cm, the allowable error is 20 ~ 30 μ m, the screen wire is 2mm × 3mm stainless steel wedge wire, and the screen cylinder is equipped with spiral guide vane.

The screening system is mainly composed of mixing bucket, slurry pump, flowmeter, feeding device and drum screen. The slurry pump will feed the slurry in the mixing drum into the drum screen through the feeding device. The products on and under the screen screened out by the drum screen flow back to the mixing drum for mixing, so as to ensure the continuous process.

3、 Screening content

The screening content mainly includes the following three aspects:

(1) Research on the influence of rotary speed and feed flow rate on drum screen dewatering and classification. Keep the feed concentration (10%) and feed particle size basically stable, and adjust the rotating speed (35, 40, 45, 50, 55 R / min) of the drum screen under different feed flow rates (5, 10, 15 m3 / h), and the ratio n / nmax to the limit speed (55 R / min) of the drum screen is 0.64, 0.73, 0.82, 0.91 and 1 [9], respectively;

(2) Study on the influence of feed concentration on drum screen dewatering and classification. Under the basic conditions of keeping feed flow rate (10m3 / h), feed particle size and drum screen speed (45r / min, N / nmax = 0.82), gradually increase the feed concentration (10%, 20%, 30%, 40%, 50%), and explore the influence of feed concentration on dewatering classification;

(3) Study on the influence of feed size characteristics on drum screen dewatering classification. Under the basic condition of keeping the feed concentration (10%) and adjusting the feed flow rate and rotary speed of the drum screen respectively under different feed particle sizes, the influence of feed particle size characteristics on drum screen dewatering classification was explored.

The dehydration performance of the screening equipment mainly adopts the moisture content of the products on the screen. The lower the moisture content of the products on the screen, the better the dehydration. The classification mainly includes screening efficiency and fine particle content (- 0.125mm fraction). Screening efficiency is a comprehensive index, the higher the better; the fine content of products on the screen is a single index, the smaller the better. This shows the importance of the screening process.

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