1. Settling equipment

Settling tanks (pools) are devices that effectively separate condensed hydroxide sludge from water. When sedimenting at the same rate, the precipitation removal rate is determined by the amount of water and the water area Q/A (Q is the amount of water and A is the area). The smaller the value, the higher the separation effect.

The shape of sedimentation is rectangular, square, and circular. The bottom has a flat bottom, a sloping bottom, a funnel bottom and so on. According to the flow of water, it can be divided into parallel flow, radial flow, vertical flow and so on. Parallel flow is mainly used for rectangular and square slots; radial flow, vertical flow squares, and circular slots. Different shapes have their own advantages and disadvantages. From the ground point of view, rectangles, squares, and circles are better. The circle does not prevent the sludge scraping operation, and the rectangle is conducive to the uniform flow of water. In addition, according to the specific circumstances, intermittent settling devices, inclined plate settlement tanks or air-flotation solid-liquid separation devices.

2. Coagulation device

The aggregating device should use the surface charge of the solid particles to neutralize and collide with each other by the flocculating agent so that the fine agglomerates grow into large agglomerates. Aggregate growth time is generally 10-40min.

The condensing device has a water stirring type and a mechanical stirring type. The most widely used at present is the mechanical stirring type.

Mechanical stirrer is equipped with a stirrer in the tank, and the aggregates are grown by dynamic stirring. The stirring speed must make the small aggregates easy to collide, and the grown aggregates will not be destroyed. The linear velocity is less than 9cm/s, the aggregation body will settle, the linear velocity is greater than 75cm/s, and the agglomerates will be destroyed. Therefore, the linear velocity is preferably 15-60cm/s.

Aggregates are easy to split and can easily be destroyed during the introduction into the sedimentation tank from the agglomerating tank. Therefore, it is better to shorten the water path as much as possible, and the flow rate should be less than 30cm/s. It is better to avoid intensive agitation or pump water.

      3. Slurry dewatering equipment

There are three kinds of vacuum suction filtration, compression and centrifugation. Now introduce the commonly used pressure filtration method and centrifugal dehydration method.

(1) Pressure filtration. Commonly used equipment for the frame filter press, which is arranged by the phase of the filter plate, filter frame components. Set the filter cloth between the frame and compress it with the compression device. The waste liquid with slurry is pumped into the slurry pump, enters into the frame of the filter press through the passage formed by the small holes in the same part of the upper part of the plate frame, and is separated by solids and liquids through the filter cloth. The filtrate is discharged from the hole in the lower part of the filter plate, the filter mud is taken into a filter cake in the filter frame, the pressing device is loosened, and the filter plate and the filter frame are disassembled. The filter cake falls from the filter cloth.

        Frame filter presses have two types, manual operation and automatic operation. Artificial frame filter press, labor intensity, low efficiency; automatic frame filter press unloading and assembly are automatic, commonly used hydraulic pressure, the maximum pressure 14MPa, and automatic pressure gauge with electrical contact pressure The efficiency is higher. Some filter presses use reinforced polypropylene filter plates, filter frames, high strength, light weight, corrosion resistance, acid and alkali resistance, non-toxic and tasteless; the maximum filtration pressure is 0.5 MPa, which ensures the best conditions for the formation of filter cakes. Pressure filtration.