Dealkalized red mud washing device

Abstract

The invention relates to the technical field of cleaning devices, and particularly discloses a dealkalized red mud washing device which comprises a pair of oppositely arranged storage tanks, water spraying devices arranged in the storage tanks, a connecting pipe used for communicating the pair of storage tanks, a negative pressure pipe arranged on the side wall of the connecting pipe, a negative pressure machine connected with the negative pressure pipe and a first driving device. The filtering holes are formed in the side wall of the connecting pipe; one storage tank is arranged above the other storage tank, the first driving device is used for driving the pair of storage tanks to rotate on the vertical plane with the connecting pipe as the circle center, and the multiple filtering holes are all formed in the negative pressure pipe. According to the dealkalized red mud washing device, on the premise that the water consumption is reduced, red mud can be fully washed, and residual alkali in the red mud can be fully recycled.

Description

Technical Field

[0001] The present invention relates to the technical field of cleaning devices, and more particularly, to a red mud washing device after dealkalization. Background Art

[0002] Red mud is an industrial solid waste discharged during the extraction of alumina in the aluminum industry. Due to its large iron oxide content and appearance similar to red soil, it is called red mud. Depending on the ore grade, production method, and technical level, approximately 1.0 - 1.8 tons of red mud are discharged for every 1 ton of alumina produced. As the stockpile of red mud increases and the environmental pollution becomes more serious, it is urgent to maximize the resource utilization of red mud.

[0003] Red mud is a porous solid particle with a high specific surface area, and a large amount of alkali-containing liquid phase (such as NaOH, NaAl(OH) 4 etc.) will be adsorbed or wrapped on its surface and pores. Therefore, after a complex dealkalization process for red mud, when directly pressure-filtered, only part of the free liquid phase can be removed by mechanical pressure, and the alkali adsorbed on the particle surface or in the pores is difficult to be completely removed. At this time, the alkali remaining in the solid phase of red mud (Nt 20 - 25g / L) will be discharged with the red mud, resulting in the loss of alkali resources (increased attached loss). Therefore, red mud can be fully washed before pressure filtration to extract the remaining alkali in the red mud, and then purified and reused later. However, washing out the remaining alkali in the red mud also consumes a large amount of water, and the water in the red mud cannot be completely filtered out during the filtration process, which will also cause some alkali residues. This will not only increase costs but also result in low benefits. Therefore, a more efficient and water-saving red mud cleaning device can be designed. Summary of the Invention

[0004] The purpose of the present invention is to provide a red mud washing device after dealkalization, which can fully wash the red mud and fully recover the remaining alkali in the red mud on the premise of reducing water consumption.

[0005] The present invention is achieved through the following technical solutions: The red mud washing device after dealkalization of the present invention includes a pair of oppositely arranged storage tanks, a water spraying device provided in the storage tanks, a connecting pipe for connecting the pair of storage tanks, a negative pressure pipe provided on the side wall of the connecting pipe, a negative pressure machine connected to the negative pressure pipe, a first driving device, and a filtering hole opened on the side wall of the connecting pipe; one of the storage tanks is arranged above the other, the first driving device is used to drive the pair of storage tanks to rotate in a vertical plane with the connecting pipe as the center, and a plurality of the filtering holes are all provided in the negative pressure pipe.

[0006] Furthermore, one side of the connecting pipe is covered with a filter cloth; the filter cloth is used to cover the filtering hole.

[0007] Further, the water spraying device includes a water spraying pipe horizontally arranged at one end of the storage tank close to the connecting pipe, water spraying holes opened on the side wall of the water spraying pipe, and a water source connected to the end of the water spraying pipe arranged outside the storage tank. A valve is arranged at the end of the water spraying pipe arranged outside the storage tank.

[0008] Further, the water spraying holes are arranged towards the inner wall of the storage tank.

[0009] Further, the first driving device includes a base, an annular slide rail vertically arranged on the base, an annular sliding ring slidably arranged in the slide rail, an internal gear arranged on the inner wall of the sliding ring, a first motor fixedly connected to the base, and a driving gear arranged on the output shaft of the first motor; the driving gear meshes with the internal gear; the outer wall of the storage tank is connected to the sliding ring through a connecting rod.

[0010] Further, it also includes an ultrasonic generator fixedly connected to the sliding ring, and a pair of amplitude transformers connected to the ultrasonic generator; the pair of amplitude transformers pass through the side wall of the connecting pipe and are arranged in the connecting pipe; the pair of amplitude transformers are respectively arranged at both ends of the connecting pipe, and the filtering holes are arranged between the pair of amplitude transformers.

[0011] Further, the cross-section of the connecting pipe is square; it also includes an anti-flushing device arranged on the connecting pipe; the anti-flushing device includes a hollow anti-flushing plate arranged in the negative pressure pipe, flushing holes opened on the side of the anti-flushing plate close to the connecting pipe, a conduit communicated with the side of the anti-flushing plate close to the connecting pipe, water inlet holes opened on the side wall of the conduit, a sleeve arranged on the outer wall of the connecting pipe far from the negative pressure pipe, a water supply pipe communicated with the side wall of the sleeve, and a second driving device arranged at the end of the sleeve far from the connecting pipe; the anti-flushing plate is used to cover the filtering holes, and the end of the conduit far from the anti-flushing plate is a sealed end; the conduit passes through the two side walls of the connecting pipe and is slidably arranged in the sleeve; when the anti-flushing plate is attached to the outer wall of the connecting pipe, the water supply pipe is communicated with the water inlet holes; the second driving device is used to drive the conduit to reciprocate in the sleeve.

[0012] Further, the anti-flushing device also includes a water pump connected to the water supply pipe.

[0013] Further, the second driving device includes a first connecting rod connected to the end of the conduit, a second connecting rod hinged to the first connecting rod, a housing connected to the side wall of the connecting pipe, a second motor arranged in the housing, and a turntable arranged on the output shaft of the second motor; the second connecting rod is hinged to the edge of the turntable.

[0014] Further, a feeding port is provided at one end of the storage tank away from the connecting pipe, and a sealing plate is detachably provided at the feeding port.

[0015] The technical solution of the present invention has at least the following advantages and beneficial effects: When the post-desilication red mud washing device of the present invention is in use, the post-desilication red mud in slurry form is put into one of the storage tanks (at this time, a pair of storage tanks are at the same height), and then the first driving device is used to drive the pair of storage tanks to rotate, so that the height of the storage tank containing red mud rises to make the connecting pipe in an inclined state (the negative pressure pipe is on the lower side). Then, the water spraying device (only the water spraying device in the upper storage tank is turned on) and the negative pressure machine are turned on. The water spraying device promotes the red mud to flow into the connecting pipe by supplying water to the storage tank, and makes the alkali in the red mud fully disperse into the water. When the red mud slurry flowing into the connecting pipe passes through the filtering holes, most of the water in the red mud slurry is directly sucked into the negative pressure pipe and discharged, and the remaining red mud flows along the connecting pipe into the lower storage tank. When all the red mud in the upper storage tank has flowed into the lower storage tank, the driving device is used to drive the storage tank to rotate 90 degrees, so that the storage tank containing red mud moves above the empty storage tank (the negative pressure pipe is still on the lower side), and then the above operation is repeated. After repeating this several times, the remaining alkali in the red mud can be fully removed and collected. Moreover, in this way, a stirring device is not needed, the amount of water used is less, the efficiency is better, the alkali concentration in the finally obtained alkali solution is higher, and the subsequent extraction efficiency of the alkali is higher. Description of the Drawings

[0016] Figure 1 It is a schematic structural diagram of one perspective of the post-desilication red mud washing device provided by an embodiment of the present invention;

[0017] Figure 2 It is a schematic structural diagram of another perspective of the post-desilication red mud washing device provided by an embodiment of the present invention;

[0018] Figure 3 It is a schematic structural diagram of the storage tank part provided by an embodiment of the present invention;

[0019] Figure 4 It is a schematic structural diagram of a state when the post-desilication red mud washing device provided by an embodiment of the present invention is running;

[0020] Figure 5 It is a schematic structural diagram of another state when the post-desilication red mud washing device provided by an embodiment of the present invention is running;

[0021] Figure 6 It is a schematic structural diagram of the inside of the connecting pipe provided by an embodiment of the present invention;

[0022] Figure 7 It is a schematic structural diagram of the backwashing device part provided by an embodiment of the present invention.

[0023] Icons: 11 - storage tank, 12 - connecting pipe, 13 - negative pressure pipe, 14 - filtering holes, 15 - water spraying device, 151 - water spraying pipe, 152 - valve, 16 - ultrasonic generator, 17 - horn, 18 - sealing plate, 20 - first driving device, 21 - base, 22 - slide rail, 23 - slip ring, 24 - driving gear, 25 - motor, 30 - backwashing device, 31 - backwashing plate, 32 - flushing holes, 33 - conduit, 34 - water inlet hole, 35 - sleeve, 36 - water supply pipe, 37 - second driving device, 371 - first connecting rod. Detailed implementation mode

[0024] Embodiment

[0025] The following is further described in combination with specific embodiments. As shown in the attached Figure 1 - attached Figure 7 As shown, the post - desalination red mud washing device of this embodiment includes a pair of oppositely arranged storage tanks 11, a water spraying device 15 arranged in the storage tank 11, a connecting pipe 12 used to connect the pair of storage tanks 11, a negative pressure pipe 13 arranged on the side wall of the connecting pipe 12, a negative pressure machine connected to the negative pressure pipe 13, a first driving device 20, and filtering holes 14 opened on the side wall of the connecting pipe 12; one storage tank 11 is arranged above the other storage tank 11, and the first driving device 20 is used to drive the pair of storage tanks 11 to rotate in a vertical plane with the connecting pipe 12 as the center of the circle, and multiple filtering holes 14 are all arranged in the negative pressure pipe 13. Specifically, when in use, the post - desalination red mud in slurry form is put into one of the storage tanks 11 (at this time, the pair of storage tanks 11 are at the same height), and then the first driving device 20 is used to drive the pair of storage tanks 11 to rotate, so that the height of the storage tank 11 containing red mud rises until the connecting pipe 12 is in an inclined state (as shown in the attached Figure 4 figure, the negative pressure pipe 13 is on the lower side), then the water spraying device 15 (only the water spraying device 15 in the upper storage tank 11 is turned on) and the negative pressure machine are turned on. The water spraying device 15 promotes the red mud to flow into the connecting pipe 12 by supplying water to the storage tank 11, and makes the alkali in the red mud fully disperse into the water. When the red mud slurry flowing into the connecting pipe 12 passes through the filtering holes 14, most of the water in the red mud slurry is directly sucked into the negative pressure pipe 13 and discharged, and the remaining red mud flows along the connecting pipe 12 into the lower storage tank 11. After all the red mud in the upper storage tank 11 has flowed into the lower storage tank 11, the driving device is used to drive the storage tank 11 to rotate 90 degrees, so that the storage tank 11 containing red mud moves above the empty storage tank 11 (as shown in the attached Figure 5 figure, the negative pressure pipe 13 is still on the lower side), and then the above - mentioned operations are repeated. After doing this back and forth many times, the remaining alkali in the red mud can be fully removed and collected. And in this way, there is no need to use a stirring device, the amount of water used is less, the efficiency is better, the alkali concentration in the final alkali solution is higher, and the subsequent extraction efficiency of the alkali is higher.

[0026] One side of the connecting pipe 12 in this embodiment is covered with a filter cloth; the filter cloth is used to cover the filter holes 14. Specifically, the aperture of the filter cloth is smaller, which can prevent the filter holes 14 from being blocked.

[0027] The water spraying device 15 in this embodiment includes a water spraying pipe 151 horizontally arranged at one end of the storage tank 11 close to the connecting pipe 12, water spraying holes opened on the side wall of the water spraying pipe 151, and a water source connected to the end of the water spraying pipe 151 arranged outside the storage tank 11. A valve 152 is arranged at the end of the water spraying pipe 151 arranged outside the storage tank 11. Specifically, the functions of the water spraying pipe 151 are, firstly, to promote the flow of the red mud slurry, and secondly, to dilute the red mud slurry so that the alkali in the red mud dissolves into the water. It should be noted that the water in the water source does not need to be sent into the water spraying pipe 151 by a pump body. Since both the storage tank 11 and the connecting pipe 12 are closed structures, when a negative pressure is generated in the connecting pipe 12 and the storage tank 11 through the negative pressure pipe 13, the water in the water source can be directly sucked into the water spraying pipe 151 by the negative pressure and sprayed out from the water spraying holes, and the water suction flow rate of the negative pressure device is almost the same as the water spraying flow rate of the water spraying pipe 151.

[0028] The water spraying holes in this embodiment are arranged towards the inner wall of the storage tank 11.

[0029] The first driving device 20 in this embodiment includes a base 21, an annular slide rail 22 vertically arranged on the base 21, an annular sliding ring 23 slidably arranged in the slide rail 22, an internal gear arranged on the inner wall of the sliding ring 23, a first motor 25 fixedly connected to the base 21, and a driving gear 24 arranged on the output shaft of the first motor 25; the driving gear 24 meshes with the internal gear; the outer wall of the storage tank 11 is connected to the sliding ring 23 through a connecting rod. Specifically, the first motor 25 drives the internal gear to rotate through the driving gear 24, and then drives the sliding ring 23 to rotate in the slide rail 22. The so-called rotation actually means swinging back and forth within a certain range, which is more conducive to wiring operations such as pipes and cables. A driving method such as a sprocket and chain can also be adopted.

[0030] In this embodiment, it also includes an ultrasonic generator 16 fixedly connected to the sliding ring 23, and a pair of amplitude transformers 17 connected to the ultrasonic generator 16; the pair of amplitude transformers 17 pass through the side wall of the connecting pipe 12 and are arranged in the connecting pipe 12; the pair of amplitude transformers 17 are respectively arranged at both ends of the connecting pipe 12, and the filter holes 14 are arranged between the pair of amplitude transformers 17. Specifically, the ultrasonic generator 16 transmits ultrasonic vibrations to the red mud slurry inside the connecting pipe 12 through the amplitude transformers 17. When the red mud slurry passes through the amplitude transformers 17, the red mud slurry generates a cavitation effect under the action of ultrasonic waves, destroying the alkali film on the surface of the red mud particles. This can not only slow down the flow rate of the red mud in the connecting pipe 12, but also play a role in stirring the red mud slurry, so that the alkali on the surface of the red mud is fully dissolved into the water.

[0031] In this embodiment, the cross-section of the connecting pipe 12 is square; it further includes an anti-flushing device 30 provided on the connecting pipe 12; the anti-flushing device 30 includes a hollow anti-flushing plate 31 provided in the negative pressure pipe 13, a flushing hole 32 opened on the side of the anti-flushing plate 31 close to the connecting pipe 12, a conduit 33 communicating with the side of the anti-flushing plate 31 close to the connecting pipe 12, a water inlet hole 34 opened on the side wall of the conduit 33, a sleeve 35 provided on the outer wall of the connecting pipe 12 away from the negative pressure pipe 13, a water supply pipe 36 communicating with the side wall of the sleeve 35, and a second driving device 37 provided at one end of the sleeve 35 away from the connecting pipe 12; the anti-flushing plate 31 is used to cover the filtering holes 14, and one end of the conduit 33 away from the anti-flushing plate 31 is a sealed end; the conduit 33 passes through the two side walls of the connecting pipe 12 and then slides in the sleeve 35; when the anti-flushing plate 31 is attached to the outer wall of the connecting pipe 12, the water supply pipe 36 is communicated with the water inlet hole 34; the second driving device 37 is used to drive the conduit 33 to reciprocate in the sleeve 35. Specifically, after the red mud is absorbed by the negative pressure pipe 13, the water content in the red mud is significantly reduced. At this time, it may adhere to the inner wall of the connecting pipe 12 (mainly accumulated at the filtering holes 14), resulting in a decrease in the flow rate of the red mud in the connecting pipe 12 or even blockage. Therefore, the anti-flushing device 30 can be used periodically to perform an anti-flushing operation on the red mud at the filtering holes 14. The principle is that when the second driving device 37 pushes the conduit 33 and the anti-flushing plate 31 away from the connecting pipe 12, at this time, the water inlet hole 34 is misaligned with the water supply pipe 36, and the water in the water supply pipe 36 cannot enter the conduit 33 and the anti-flushing plate 31. And because there is a gap between the anti-flushing plate 31 and the connecting pipe 12, the negative pressure device can absorb water through the filtering holes 14 on the connecting pipe 12 (at this time, the valve 152 on the water spraying pipe 151 is opened); when the second driving device 37 pulls the conduit 33 and the anti-flushing plate 31 close to the connecting pipe 12 and the anti-flushing plate 31 is attached to the connecting pipe 12, the water inlet hole 34 and the water supply pipe 36 are conducted, and at this time, the water in the water supply pipe 36 can enter the conduit 33, flow into the anti-flushing plate 31 through the conduit 33, and then rush out through the flushing holes 32 on the anti-flushing plate 31, and backflush into the filtering holes 14 to wash away the red mud adhering to the filtering holes 14. During this process, the valve 152 on the water spraying pipe 151 is closed, and at this time, the water spraying pipe 151 cannot intake water. Therefore, the negative pressure device will directly suck the water in the water supply pipe 36 into the conduit 33 and the anti-flushing plate 31 and rush out through the flushing holes 32 to achieve the purpose of anti-flushing. And the amount of water entering the conduit 33 through the water supply pipe 36 is related to the negative pressure of the negative pressure device. Therefore, too much water will not enter the connecting pipe 12 and the storage tank 11 during this anti-flushing process.

[0032] The backwashing device 30 in this embodiment further includes a water pump connected to the water supply pipe 36. Specifically, when a large amount of red mud clogs the filter holes 14 and the backwashing plate 31 fits against the side wall of the connecting pipe 12, the efficiency of sucking water from the water supply pipe 36 by negative pressure may be insufficient at this time, resulting in a poor flushing effect. Therefore, the water pump can be used to assist in supplying water for backwashing.

[0033] The second driving device 37 in this embodiment includes a first connecting rod 371 connected to the end of the conduit 33, a second connecting rod hinged to the first connecting rod 371, a housing connected to the side wall of the connecting pipe 12, a second motor 25 disposed inside the housing, and a turntable disposed on the output shaft of the second motor 25; the second connecting rod is hinged to the edge of the turntable. Specifically, the movement of the conduit 33 is essentially a conventional structure that converts circular motion into linear motion, so it will not be described in detail in this embodiment.

[0034] One end of the storage tank 11 in this embodiment, which is far from the connecting pipe 12, is provided with a feeding port, and a sealing plate 18 is detachably provided at the feeding port. Specifically, feeding and discharging can be carried out through the feeding port. When the connecting pipe 12 is vertical, the red mud in the lower storage tank 11 can be discharged more efficiently.

[0035] In summary, for the washed red mud device after dealkalization in this embodiment, when in use, the red mud in a slurry state after dealkalization is put into one of the storage tanks 11 (at this time, a pair of storage tanks 11 are at the same height), and then the first driving device 20 is used to drive the pair of storage tanks 11 to rotate, so that the height of the storage tank 11 filled with red mud rises until the connecting pipe 12 is in an inclined state (the negative pressure pipe 13 is on the lower side). Then, the water spraying device 15 (only the water spraying device 15 in the upper storage tank 11 is turned on) and the negative pressure machine are turned on. The water spraying device 15 promotes the red mud to flow into the connecting pipe 12 by supplying water to the storage tank 11, and makes the alkali in the red mud fully disperse into the water. When the red mud slurry flowing into the connecting pipe 12 passes through the filter holes 14, most of the water in the red mud slurry is directly sucked into the negative pressure pipe 13 and discharged, and the remaining red mud flows along the connecting pipe 12 into the lower storage tank 11. After all the red mud in the upper storage tank 11 has flowed into the lower storage tank 11, the driving device is used to drive the storage tank 11 to rotate 90 degrees, so that the storage tank 11 filled with red mud moves above the empty storage tank 11 (the negative pressure pipe 13 is still on the lower side), and then the above operations are repeated. After doing this back and forth many times, the alkali remaining in the red mud can be fully removed and collected. And in this way, a stirring device does not need to be used, the amount of water used is less, the efficiency is better, the alkali concentration in the final obtained alkali solution is higher, and the subsequent extraction efficiency of the alkali is higher.

[0036] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, various modifications and variations can be made to the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A red mud washing device after dealkalization, characterized in that: The invention comprises a pair of storage tanks (11) arranged opposite to each other, a water spraying device (15) arranged in the storage tanks (11), a connecting pipe (12) for connecting the pair of storage tanks (11), a negative pressure pipe (13) arranged on the side wall of the connecting pipe (12), a negative pressure machine connected to the negative pressure pipe (13), a first driving device (20), and a filtering hole (14) opened on the side wall of the connecting pipe (12); One storage tank (11) is arranged above another storage tank (11), the first driving device (20) is used to drive the pair of storage tanks (11) to rotate on a vertical plane with the connecting pipe (12) as the center, and the plurality of filter holes (14) are all arranged in the negative pressure pipe (13).

2. The device for washing red mud after dealkalization according to claim 1, characterized in that: One side of the connecting pipe (12) is covered with a filter cloth; the filter cloth is used to cover the filter hole (14).

3. The device for washing red mud after dealkalization according to claim 1, characterized in that: The water spray device (15) comprises a water spray pipe (151) horizontally arranged at one end of the storage tank (11) close to the connecting pipe (12), a water spray hole provided on the side wall of the water spray pipe (151), and a water source connected to one end of the water spray pipe (151) arranged outside the storage tank (11); and a valve (152) is provided at one end of the water spray pipe (151) arranged outside the storage tank (11).

4. The device for washing red mud after dealkalization according to claim 3, characterized in that: The water spray hole is arranged toward the inner wall of the storage tank (11).

5. The device for washing red mud after dealkalization according to claim 1, characterized in that: The first driving device (20) comprises a base (21), an annular slide rail (22) vertically arranged on the base (21), an annular slip ring (23) slidably arranged in the slide rail (22), an internal gear arranged on the inner wall of the slip ring (23), a first motor (25) fixedly connected to the base (21), and a driving gear (24) arranged on the output shaft of the first motor (25); the driving gear (24) is meshed with the internal gear; The outer wall of the storage tank (11) and the slip ring (23) are connected via a connecting rod.

6. The device for washing red mud after dealkalization according to claim 5, characterized in that: It also includes an ultrasonic generator (16) fixedly connected to the slip ring (23), and a pair of horn rods (17) connected to the ultrasonic generator (16); the pair of horn rods (17) are arranged in the connecting tube (12) after passing through the side wall of the connecting tube (12); A pair of amplitude change rods (17) are respectively arranged at two ends of the connecting pipe (12), and the filtering hole (14) is arranged between the pair of amplitude change rods (17).

7. The device for washing red mud after dealkalization according to claim 1, characterized in that: The cross section of the connecting pipe (12) is square; It also includes a backwashing device (30) arranged on the connecting pipe (12); the backwashing device (30) includes a hollow backwashing plate (31) arranged in the negative pressure pipe (13), a flushing hole (32) provided on the side of the backwashing plate (31) close to the connecting pipe (12), a conduit (33) connected to the side of the backwashing plate (31) close to the connecting pipe (12), a water inlet hole (34) provided on the side wall of the conduit (33), a sleeve (35) provided on the outer wall of the connecting pipe (12) away from the negative pressure pipe (13), a water supply pipe (36) connected to the side wall of the sleeve (35), and a second driving device (37) provided at the end of the sleeve (35) away from the connecting pipe (12); The recoil plate (31) is used to cover the filter hole (14); the end of the conduit (33) away from the recoil plate (31) is a sealed end; the conduit (33) passes through the two side walls of the connecting pipe (12) and is slidably arranged in the sleeve (35); when the recoil plate (31) is attached to the outer wall of the connecting pipe (12), the water supply pipe (36) is connected to the water inlet hole (34); The second driving device (37) is used to drive the catheter (33) to reciprocate in the sleeve (35).

8. The device for washing red mud after dealkalization according to claim 7, characterized in that: The backwashing device (30) further comprises a water pump connected to the water supply pipe (36).

9. The device for washing red mud after dealkalization according to claim 7, characterized in that: The second driving device (37) includes a first connecting rod (371) connected to the end of the conduit (33), a second connecting rod hinged to the first connecting rod (371), a shell connected to the side wall of the connecting tube (12), a second motor (25) arranged in the shell, and a turntable arranged on the output shaft of the second motor (25); the second connecting rod is hinged to the edge of the turntable.

10. The device for washing red mud after dealkalization according to claim 1, characterized in that: A feeding port is provided at one end of the storage tank (11) away from the connecting pipe (12), and a sealing plate (18) is detachably provided at the feeding port.

Images