Overview of Bowl Centrifuge
Bowl centrifuge is a dewatering instrument which is used for coal water treatment. Under the centrifugal force, coal slurry gradually dehydrated in the rotating box. It is widely used in light manufacturing, chemical industry, food industry, pharmaceuticals industry, coal processing, metallurgy, petrochemical engineering and other fields. For some readily releasable materials, there is no need to add flocculating agents to make high-quality products. Therefore, the bowl centrifuge is very economical.
Working Principle of Bowl Centrifuge
Generally, it is very difficult for fine particles to dehydrate. Common dewatering equipment include bowl centrifuge, vacuum filter, pressure filter etc. The bowl centrifuge adopts centrifugal force to make wet solids gradually harden and deposit on the wall of rotating bowl. Then its spiral scraper is used to make products drop. The bowl centrifuge in mainly used in dewatering of solid minerals containing amounts of moisture. It perform well when the particle size is 1-3mm, however, it also can expand that working range to 13mm sometimes.
Mineral mixtures enter the central feed pipe (No.5), after a preliminary acceleration in the bearing box, and then come into the rotating bowl through the rotor (No. 2) and feed nozzle (No.6). Under the centrifugal force, materials are thrown to the wall of rotating bowl, forming an annular settling bed. The rotor carries those settled materials to the drying zone, after a further process of compression and dewatering, products are discharged from the sediment exit (No.3). During the generating process of sediment, the liquid in the outer rotating bowl (No.1) constantly are cleared and flowing towards the overflow port. Finally, the liquid pours from the overflow port and separate from the solid. The dewatering process of mineral material is divided into two stages. The first stage is that solid particles become a settling bed under the centrifugal force. The second stage is dewatering under the squish action of spiral rotor. In addition, the first stage plays a more important role.
Technological Process of Bowl Centrifuge
Zenith’s innovative recovery process of separation which is especially applicable for the dehydration of coal slime. It adopts heavy-medium cyclone. Tailings of magnetic separator are classified by the sieve band, and backwater is dealt by the floatation process. Coal slurry and floatation froth are carried by bowl centrifuge to recycle fine particles of 0.045mm. Coal slime whose size is under 0.045mm is recycled by pressure filter, while the filtering medium of centrifuge flows into the filter. The particle size makes a big difference to the performance of screen bowl centrifuge. Manufacturers at home and aboard reach an agreement that operators should control the proportion of fine particles under 40% in the mixture. If not, it easily causes products to block the discharge gate and affect its performance. So operators should mix the coal slime on the sieve bend with the floatation froth. Two advantages of that method are as follows: ? it can improve the performance of LWZ series centrifuge obviously;? you need not to use a centrifuge which is specially for the dewatering of coal slurry, simplifying the technological process and saving investment.
Effects of Bowl Centrifuge
1. The moisture of final products is very low, less than 15.24%.The miscellany rate of liquid is only 5.39%, that is, 94.61% of liquid in the slurry has been discharged.
2. The recovery rate of solid can achieve to 86.91%, which is a satisfactory index.
3. Dehydration equipment in coal-separation plants belongs to the scope of solid-liquid separator. Its technological effect should be evaluated from two aspects: the rate of recovery of solid products and the miscellany rate of liquid. When looking at the dewatering efficiency of bowl centrifuge, we should take the two indexes together. Experiments have improved that the dewatering efficiency of our machine has achieved to 81.52%. We are proud of its excellent efficiency for dewatering coal slurry whose size exceeds 0.045mm.