Six dewatering methods and equipments in sand washing plant

In the sand washing plant and silica sand processing plant, sand tailings and concentrates need to be dehydrated. In order to avoid environmental pollution caused by sewage discharge, on the other hand, production water is recycled to reduce production costs. Dewatering of quartz sand concentrate is also to reduce the water content of quartz sand concentrate and meet the water content requirements of quartz sand products.
The process design and equipment selection are very important to meet the requirements of specified recovery rate, water quality recovery or muddy water discharge standards, and the principle of advanced technology, technical feasibility, reliable operation and investment saving.
Widely used equipment in the sand washing plant for muddy water treatment and dewatering process mainly includes: dewatering screen, spiral classifier, hydrocyclone,  filter press, ceramic filter, desliming cone and so on.

1.Dewatering screen

High frequency dewatering screen is a kind of vibrating screen with high frequency and high vibration intensity. It is mainly suitable for the wet classification and solid-liquid separation of fine material below 0.5mm. Widely used in filtration and dewatering equipment industry such as beneficiation, environmental protection, tailings dry row, concentrate dewatering, slurry concentration, removal of debris, carbon slurry separation etc. This machine is particularly suitable for processing fine minerals. In addition, it can combine with hydrocyclone to be more efficient.



High frequency dewatering screen adopts double vibration motor as power supply. The two motors that rotate synchronously and reversely and centrifugal force is produced by two groups of eccentric block. This makes the screen body periodical to-and-fro moving along the direction of straight line, which is for the purpose of dehydration. The screen frame is connected by the high-intensity bolts, so the structure is stable and durable.

2.Spiral classifier

Spiral classifier（spiral sand washing machine） combines sand washing, grading and dewatering. And according to the relative height of overflow weir, spiral classifier can be divided into three types: high weir type (overflow weir higher than lower bearing), sunken type (overflow water surface submerged spiral) and low weir type (overflow weir lower than lower bearing). Additional, according to the number of its spiral shaft can be divided into single spiral, double spiral classifier.



Enerally, spiral classifiers have a low rotation speed, and the lower end is equipped with stirring blade paddle, wide overflow port and long body to facilitate dehydration.
When spiral classifiers for sand washing and dewatering, the production capacity is generally calculated according to the amount of sand returned, and the control particle size and allowable feed flow rate are checked according to the overflow speed.

3.Hydrocyclone

Hydrocyclone is a type of classifier that is for the fines classification and dewatering by centrifugal force. The overflow particle is generally used for concentrated slurry and recovered fine sand, and the moisture content of sand after dehydration by hydrocyclone is about 20-26%.



The hydrocyclone specifications are determined by the production capacity and overflow particle size. When the production capacity is large and the overflow particle size is coarse, a large cyclone should be used. If the production capacity is large and the overflow particle size is small, a small cyclone group can be used. The classification efficiency of hydrocyclone is about 30~50%.

4.Filter press

Filter press is generally used as the end mechanical treatment mode for solid-liquid separation in the waste water treatment of sand and gravel system. The material is filtered by pressure, especially for the separation of slime, which has its unique superiority. Filter press can be divided into three types: plate ans frame filter press, chamber filter press and belt filter press.
Basic principle: filter press is a filter that combines a plurality of filter plates and filter frames to form filter chambers and uses pressure as a filter driving force. The mixed liquid flows through filter medium (filter cloth), the solid stays on filter cloth, and gradually builds up on the filter cloth to form filter cake. And filtrate portion was permeated through the filter cloth to become a solid-free supernatant.



Compared with other solid-liquid separation equipment, filter press can carry out the final dewatering treatment of sludge and stone powder to meet the requirements of loading and transportation, and separate it. The water can be directly discharged or recycled, and the filter cake filtered by filter press has higher solid content and lower water content.

5.Ceramic filter

Ceramic filter is also the end mechanical treatment equipment for sludge and stone powder in waste water treatment. This type of equipment can not only carry out the final dewatering treatment of sludge and stone powder to meet the requirements of loading and transportation. At the same time, filter water can also be directly discharged or recycled. Moreover, ceramic filters have the advantages of large processing capacity, simple operation, and continuous operation.



6.Desliming cone

Desliming cone is a simple classification, desliming and concentration equipment. In the production line of quartz sand, it is generally used for the classification and dewatering of quartz sand slurry, and the separation of slime and fine-grained materials to achieve the purpose of purifying quartz sand.



The desliming cone is an inverted cone. A feeding pipe is arranged in the center of the liquid level, and the bottom edge of the cone is submerged in certain depth below the liquid level. The slurry is fed into the central pipe along the tangential direction and flows out from the bottom edge after buffering. The effluent slurry flows out radially along the peripheral overflow weir. In this process, the coarse particle materials with the sedimentation velocity greater than the rising velocity of liquid flow are deposited in the cone and discharged through the bottom. Fine particles with the slurry enter into the overflow tank and are discharged.