Because the disc gap is very small, the disc separator forms thin layer separation, and the horizontal settlement distance of fine particles between disc channels is very short, so the separation effect is good, and particles as small as 0.5μm can be separated from light liquid. Therefore, the disc separator can be used to clarify a small amount of fine particles in suspension to obtain clean liquid, and can also be used to separate light and heavy phases in emulsion, mainly used to separate suspension in non-metallic mineral processing.

I. Structure and working principle

The appearance of the disc separator is shown in Figure 5- 15, and the schematic diagram is shown in Figure 5- 16.

There are many inverted conical discs on the drum of the disc separator. The suspension enters the drum from the central feed pipe, enters the disc gap from the outer edge of the disc and flows to the inner edge of the disc. Solid particles settle on the inner surface of the disk, slide to the outer edge of the disk under the action of centrifugal force, and finally settle on the cylinder wall. Clear liquid is discharged through overflow or centripetal pump.

Generally, the number of discs in a disc separator is 50 ~ 180, depending on the size of the machine, the disc gap is often 0.5 ~ 1.5 mm, depending on the nature of the treated material, the rotating speed of the drum can reach 4700 ~ 8500 r/min, and the separation coefficient is relatively high, reaching 3000 ~1.

Generally, there are disc separators with manual slag discharge, nozzle slag discharge and piston slag discharge.

Fig. 5- 15 external schematic diagram of disc separator

Figure 5- 16 Inverted Cone Liquid Separator

1- emulsion inlet; 2- inverted cone disk; 3- heavy liquid outlet; 4- light liquid outlet; 5- Gasket

Second, the nozzle slag tray separator

The disc separator with nozzle slag discharge is a kind of continuous disc separator. The roller is biconical, as shown in Figure 5- 17.

The annular slag storage space of double cone tube and double cone joint not only compresses and concentrates the slag, but also has good slag discharge conditions. There are 2 ~ 24 slag discharge nozzles evenly distributed around the drum, and the nozzle aperture is 0.5 ~ 3.2 mm The number and aperture of nozzles depend on the size of the machine, the nature of the suspension, the handling capacity and the concentration degree. The general concentration is 5-20 times. For a certain model and material, the clarity of separation liquid will decrease with the increase of feed flow rate and feed concentration. For the disc separator with nozzle slag discharge, the feed flow has two limits, the lowest limit is equal to the discharge of the nozzle, and there is no overflow at this time, and the highest limit is the overflow flow. At this time, the feed suspension is discharged from the overflow without separation, and the solid content of the separated liquid is almost the same as the feed concentration. Therefore, it is necessary to control the feed quantity and feed concentration during operation. The maximum drum diameter of the separator can reach 900mm, and the treatment capacity can reach 300m3/h, which is suitable for treating suspension with solid particle size of 0. 1 ~ 100 micron and solid volume concentration less than 25%.

Three, piston (ring valve) slag disc separator

Piston-type deslagging disc separator uses the up-and-down action of annular valve to open and close the deslagging port for intermittent deslagging, so it is also called automatic deslagging disc separator. Fig. 5- 18 shows the schematic diagram of the rotating drum of the separator. The annular plate valve at the bottom of the drum can move up and down under the control of working water. When the position is upward, close the slag discharge port to stop slag discharge, and when the position is downward, open the slag discharge port to discharge slag. When slag is discharged, the sediment in the slag storage space of the drum can be discharged without stopping the machine. The automatic control methods of slag discharge are as follows: ① according to the predetermined operation cycle, the slag discharge is controlled by time relay; (2) monitoring the clarity of the separated liquid with a photoelectric tube to control the slag discharge; (3) According to the deposit accumulation degree of the drum, the slag discharge is controlled by the pressure signal or the liquid level signal. The slag discharge time is generally 1 ~ 2 seconds. In order to avoid discharging unseparated suspension during slag discharge, feeding must be stopped during slag discharge. In order to overcome this shortcoming, a disc separator with a partial slag discharge drum can be used, and the slag discharge time can be controlled within a very short time of 0. 1 ~ 0.5 seconds, and only part of the accumulated slag in the slag storage space is discharged at a time, and the non-separated suspended solids are not discharged. When discharging slag, it is not necessary to stop feeding and continuously separate, thus improving the treatment capacity and the concentration of sediment. The separation factor of the disc separator ranges from 5,000 to 9,000, and the maximum treatment capacity can reach 40m3/h, which is suitable for treating suspensions with solid particle size of 0. 1 ~ 500μ m, solid-liquid density difference greater than 0.0 1g/cm3 and solid concentration less than 10%.

Figure 5- 17 Disc separator drum with nozzle slag discharge

Fig. 5- 18 schematic diagram of drum of disc separator with annular slag discharge valve.

Fourth, the performance of the disc separator

See table 5- 13 for the performance and technical parameters of the disc separator.

Table 5- 13 Performance of Disk Separator