Function of ore washing sedimentation tank

1.

The sedimentation tank adopts the principle of gravity separation. Under the action of gravity, the density of part of the feces is greater than 1 × 103 kg / m3 (density of water) of suspended solids is separated from the feces by natural sedimentation

According to the flow direction of sewage in the tank, the sedimentation tank can be divided into horizontal flow type, vertical flow type, radial flow type and other basic forms. The structure of horizontal flow sedimentation tank is simple and the construction is convenient, but it covers a large area and the water distribution is uneven; The structure of vertical flow sedimentation tank is round, which occupies a small area, and it is inconvenient to discharge sludge; The radial flow sedimentation tank has a set type of sludge discharge machinery, which has good operation effect, but it requires higher construction quality and management level

generally, the retention time of feces in gravity sedimentation tank is 1-3 hours, and more than 50% of solids can be removed. The investment and operation cost of sedimentation tank are low, but the water content of solid separated from sedimentation tank is high

2. Whether it is sand washing or mineral processing, wastewater treatment is an essential link, especially in the current increasingly stringent environmental protection. Friends who know about these two kinds of operations must be familiar with the sedimentation tank. It is a device to remove suspended solids in wastewater and purify water quality by sedimentation. According to the shape and flow characteristics of the primary sedimentation tank, the primary sedimentation tank is usually divided into four types: horizontal flow type, vertical flow type, amplitude flow type and inclined plate tube type
1. Horizontal flow sedimentation tank
the tank type of horizontal flow sedimentation tank is rectangular, wastewater flows in from one end of the tank, flows horizontally through the tank, and flows out from the other end of the tank. A mud hopper is set at the bottom of the inlet of the tank, and there is a slope at the bottom of other parts of the tank, which is inclined to the mud hopper< 2. Vertical flow sedimentation tank
most of the tanks are round or square or polygonal in shape. The waste water enters from the central pipe in the center of the tank and is evenly and slowly distributed on the cross section of the tank after passing through the reflecting plate from the lower end of the central pipe. Since the water outlet is set on the surface of the tank or around the tank wall, the water flow direction is basically from bottom to top. Sludge is stored in a sludge hopper at the bottom
3. Radial flow sedimentation tank
radial flow sedimentation tank is a kind of large sedimentation tank, which is round in shape, and sometimes square or polygonal in shape. The layout of the inlet and outlet of the pool is basically the same as that of the vertical flow pool, with the inlet in the center and the outlet around. However, the ratio of pool diameter to pool depth in radial flow pool is many times larger than that in vertical flow pool. The sludge hopper is set in the center of the tank, and the bottom of the tank is inclined to the center. Sludge is usually removed by scraping (or suction) machinery< 4. Inclined plate tube sedimentation tank
according to the shallow tank theory, the inclined plate or inclined tube is added in the sedimentation area of the sedimentation tank. It consists of inclined plate (pipe) sedimentation zone, inlet water distribution zone, clear water outlet zone, buffer zone and sludge zone.

3. ——Sedimentation tank, water purification equipment. It is a kind of structure to remove suspended solids in water by gravity precipitation. It is composed of water inlet, water outlet, water flow part and sludge hopper. In order to improve the sedimentation effect and rece land occupation, accelerated clarifier, pulse clarifier and honeycomb inclined tube counter flow sedimentation tank are widely used.

4.

The grit chamber is mainly used to remove the sand particles with particle size greater than 0.2mm and density greater than 2.65t/m3 in the sewage, so as to protect the pipelines, valves and other facilities from abrasion and blockage. Its working principle is based on gravity separation, so the inflow velocity of grit chamber should be controlled to make heavy inorganic particles sink, while organic suspended particles can be carried away with the flow

the sedimentation is to remove the suspended matter and purify the water. The suspended solids in water can be removed by natural precipitation or coagulation precipitation. The sedimentation tank is divided into horizontal sedimentation tank and vertical sedimentation tank according to the flow direction. The sedimentation effect depends on the flow rate of water in the sedimentation tank and the residence time of water in the tank. In order to improve the sedimentation effect and rece the land area, honeycomb inclined tube counter flow sedimentation tank, accelerated clarifier and pulse clarifier are often used. Sedimentation tank is widely used in wastewater treatment

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in the design of grit chamber, the following principles must be followed:

1. Generally, grit chamber should be set in municipal wastewater treatment plant, and the number of seats or grids should not be less than 2 (grids), and the parallel operation principle should be considered

2. The design flow should be considered by stages:

when the sewage flows in by itself, it should be calculated according to the maximum design flow of each phase; When the sewage is delivered by lift pump, it should be calculated according to the maximum combined flow of each phase of the working pump; In the combined system, it should be calculated according to the design flow ring rainfall

3. The sand impurities removed by grit chamber are mainly particles with specific gravity of 2.65 T / m3 and particle size of more than 0.2 mm

4. The sand settling volume of urban sewage can be calculated as 30 cubic meters per 100000 cubic meters of sewage, with a water content of 60% and a capacity of 1500 kg / cubic meters

5. The volume of sand storage bucket should be calculated according to the two-day settling volume, and the inclination angle between the wall of sand storage bucket and the horizontal plane should not be less than 55 ° The diameter of sand discharge pipe shall not be less than 0.3m

The superelevation of grit chamber should not be less than 0.3m

In general, mechanical method should be used for sand removal. When gravity sand discharge is adopted, the grit chamber and sand drying plant should be close to each other as far as possible to shorten the length of sand discharge pipe

the plane of the sedimentation tank body is rectangular, and the inlet is set at one end of the tank length. Generally, the submerged inlet hole is used. Water flows into the tank body through the uniformly distributed inlet hole through the inlet channel, and a baffle is set behind the inlet hole to make the water flow evenly distributed in the cross section of the whole tank width. The outlet of the sedimentation tank is set at the other end of the tank length, and overflow weir is often used to ensure that the clarified water after sedimentation can flow into the outlet channel evenly along the width of the tank

scum trough and baffle are set in front of weir to intercept scum. The flow part is the main body of the pool. The width and depth of the pool should ensure that the water flow is evenly distributed along the flow section of the pool and flows slowly and stably according to the design flow rate. The length width ratio of the pool is generally not less than 4, and the effective depth of the pool is generally not more than 3 meters. The sludge hopper is used to accumulate the settled sludge, which is mostly set below the bottom of the tank in front of the tank. There is a sludge discharge pipe at the bottom of the hopper to discharge sludge regularly

5. The horizontal flow sedimentation tank has been used for the treatment of gas washing water of 225m3, 350m3 and 310m3 blast furnaces in the ironmaking plant of Xinjiang iron and Steel Group Co., Ltd. The pool is divided into four cells, each 20 meters × m. The total precipitation area is 640m2. The practice shows that: after the expansion of proction scale, the horizontal flow sedimentation tank can not meet the needs of proction process and environmental protection. The main problems of the horizontal flow sedimentation tank system are as follows: 1) the average removal rate of suspended matter in the system is only 50%, which not only pollutes the environment by flowing water, but also has low utilization rate of circulating water, and about 3000m3 of fresh water needs to be added every day, This is a prominent contradiction with the shortage of water resources in Xingang area; ② After the expansion and construction, the required sedimentation area is 158m3, while the original horizontal sedimentation tank area is only 640m3, which is far from meeting the process requirements. The cleaning cycle has to be shortened (one tank per month). In winter, it is very cold, and the cleaning equipment is very backward, the labor intensity of workers is high, and the environmental pollution is serious; ③ The removal rate of suspended solids in the system is low, the quality of cleaning gas is poor, and the nozzle of the washing tower is often blocked, resulting in "overflow tower" The blast furnace was forced to shut down and the proction was affected. In consideration of the above factors, Xingang decided to build a new blast furnace gas washing water treatment project (referred to as turbid cycle 3) when building a new 380m3 Blast Furnace

6. The main functions of the primary sedimentation tank are as follows:

1. To remove the precipitable or floating materials and rece the load of the subsequent treatment facilities

2. The fine solid can be flocculated into larger particles to enhance the effect of solid-liquid separation

3. It can adsorb and remove colloidal substances to a certain extent,

4. To a certain extent, the primary sedimentation tank can play the role of regulating tank and homogenizing the water quality to a certain extent

5. Some wastewater treatment systems return part of the sludge from the secondary sedimentation tank to the primary sedimentation tank to play the biological flocculation role of the sludge from the secondary sedimentation tank, which can absorb more dissolved and colloidal organic matter and improve the removal efficiency of the primary sedimentation tank< In addition, iron containing coagulant can be added in front of the primary sedimentation tank to enhance the effect of phosphorus removal.

7. The function of the sedimentation tank is to let the large particles in the water settle first and rece the burden of the physical filtration system. If the burden of the physical filtration is too large, it will increase the burden of the biochemical filtration system. If you think the filtration is troublesome, you can use Xipu fish pond filtration to purify

8. In the primary sedimentation tank, the structure of the first sedimentation is mainly used to rece the concentration of suspended solids in the wastewater.
the secondary sedimentation tank receives the effluent from the secondary treatment of wastewater to remove the biological suspended solids. In the activated sludge process, the mixture from the aeration tank is separated and concentrated in the secondary sedimentation tank, In the biofilm process, the falling biofilm is separated with the filter effluent in the secondary sedimentation tank

9.

The sedimentation tank is based on the principle that the suspended impurity particles in the water flow can be separated from the water flow when the downward sedimentation speed is greater than the flow speed, or the downward sedimentation time is less than the flow out of the sedimentation tank

the suspended solids in water can be removed by natural precipitation or coagulation precipitation. The sedimentation tank is divided into horizontal sedimentation tank and vertical sedimentation tank according to the flow direction

the sedimentation effect depends on the flow rate of water in the sedimentation tank and the residence time of water in the tank. In order to improve the sedimentation effect and rece the land area, honeycomb inclined tube counter flow sedimentation tank, accelerated clarifier and pulse clarifier are often used. Sedimentation tank is widely used in wastewater treatment

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precautions:

in order to avoid short flow, some measures should be taken as far as possible in the design, such as using appropriate inlet water distribution device to eliminate the inlet jet, making the flow evenly distributed on the cross section of sedimentation tank, recing turbulence and preventing excessive flow velocity near the sludge area, Finger flume is used to extend the length of weir

the sedimentation tank should be covered or partition wall should be set to rece the influence of wind and light heating; The high concentration water is pre settled to rece the density current caused by the high concentration of suspended solids

The second is to strengthen the operation management, strictly check whether the outlet weir is straight before the sedimentation tank is put into operation, and timely repair if any problem is found. In operation, scum may block part of the overflow weir, resulting in different overflow per unit length of the whole weir, resulting in water pumping. The operator should clean up the scum on the weir in time

10. Primary sedimentation tank is the first sedimentation structure in wastewater treatment, which is mainly used to rece the concentration of suspended solids in wastewater
the secondary sedimentation tank is a sedimentation tank that receives the effluent from secondary treatment of wastewater to remove biological suspended solids. In the activated sludge process, the mixed liquid from the aeration tank is separated and concentrated in the secondary sedimentation tank. The clarified effluent overflows and is discharged. Part of the concentrated activated sludge flows back to the aeration tank, and the rest is discharged as excess sludge. In the biofilm process, the falling biofilm is separated with the filter effluent in the secondary sedimentation tank