System for reducing hydrolysis loss of sodium aluminate in aluminum oxide production

Abstract

The invention relates to the technical field of aluminum oxide production, and particularly discloses a system for reducing hydrolysis loss of sodium aluminate in aluminum oxide production, which comprises a rear tank, a mixing box, a mixing device, a precipitation tank and a washing tank which are connected in sequence, the precipitation tank is communicated with the washing tank through an underflow pipe, and the washing tank is connected with the mixing box through a washing liquid pipe. According to the system for reducing the hydrolysis loss of the sodium aluminate in the production of the aluminum oxide, the retention time of ore pulp before settling separation can be effectively shortened, the hydrolysis damage of the sodium aluminate is reduced, and the yield of the aluminum oxide is increased.

Description

Technical Field

[0001] The present invention relates to the technical field of alumina production, and more particularly, to a system for reducing the hydrolysis loss of sodium aluminate in alumina production. Background Art

[0002] In the process of alumina production, after digestion, the pulp enters the back tank. After the washing liquid generated by the first sedimentation washing tank is sent to the dilution tank, it is then sent to the back tank by a transfer pump to be mixed with the digested pulp to obtain diluted pulp, and then the diluted pulp is sent to the separation sedimentation tank for sedimentation separation. The overflow (crude liquid) after separation is filtered under pressure by adding lime milk as a filter aid and a vertical leaf filter to obtain semen.

[0003] The semen contains sodium aluminate, and the content of sodium aluminate will affect the output of the final alumina product. In actual production, it is found that the pulp will stay for a long time before entering the sedimentation tank. For example, after staying in the back tank and then being sent to the dilution tank to be mixed and diluted with the washing liquid, it will also stay in the dilution tank for a long time. Moreover, the long stay will significantly reduce the temperature of the pulp itself. The longer the residence time of the pulp, the lower the temperature, and the higher the hydrolysis degree of sodium aluminate, resulting in a lower output of the final alumina. Therefore, it is necessary to design a sedimentation system that can effectively reduce the residence time of the pulp. Summary of the Invention

[0004] The purpose of the present invention is to provide a system for reducing the hydrolysis loss of sodium aluminate in alumina production, which can effectively reduce the residence time of the pulp before sedimentation separation, reduce the hydrolysis damage of sodium aluminate, and improve the output of alumina.

[0005] The present invention is achieved through the following technical solutions: The system for reducing the hydrolysis loss of sodium aluminate in alumina production of the present invention includes a back tank, a mixing box, a mixing device, a sedimentation tank, and a washing tank connected in sequence; the sedimentation tank is communicated with the washing tank through a bottom flow pipe, and the washing tank is connected to the mixing box through a washing liquid pipe.

[0006] Furthermore, the mixing device includes a plurality of static mixers arranged vertically, a mixing pipe provided at the lower end of the static mixer, a water inlet pipe connected to one end of the mixing pipe, a feed chute connected to the other end of the mixing pipe, and a negative pressure device connected to the feed chute; the upper ends of the plurality of static mixers are all communicated with the lower end wall of the mixing box, and the lower ends of the plurality of static mixers are all communicated with the mixing pipe; the end of the feed chute away from the mixing pipe is connected to the sedimentation tank.

[0007] Furthermore, the end of the water inlet pipe away from the mixing pipe is arranged in the sedimentation tank.

[0008] Furthermore, a water pump is connected to the end of the water inlet pipe away from the mixing pipe.

[0009] Further, one end of the water inlet pipe away from the water pump is arranged inside the mixing pipe; a plurality of water inlet holes are formed in the side wall of the part of the water inlet pipe arranged inside the mixing pipe, and the plurality of water inlet holes are respectively arranged directly below the plurality of static mixers.

[0010] Further, the static mixer includes a vertically arranged sleeve, and a plurality of baffles staggered in the sleeve; the plurality of baffles are evenly distributed in the vertical direction.

[0011] Further, the lower end of the sleeve is arranged inside the mixing pipe, and a plurality of sleeves are arranged inside the mixing pipe; the plurality of sleeves are all sleeved on the water inlet pipe, the plurality of sleeves are evenly distributed along the length direction of the water inlet pipe, the water inlet holes are arranged inside the sleeves, and the lower end of one sleeve communicates with the side wall of one sleeve.

[0012] Further, the axis of the sleeve is parallel to the axis of the sleeve, one end of the sleeve facing the feed chute is an open end, and one end of the sleeve away from the feed chute is a sealed end.

[0013] Further, the mixing pipe is inclined, and the height of the mixing pipe near the feed chute is lower than the height of the other end.

[0014] The technical solution of the present invention has at least the following advantages and beneficial effects: In the system for reducing the hydrolysis loss of sodium aluminate in alumina production of the present invention, the slurry discharged during the production process enters the back tank, and the slurry in the back tank is sent to the mixing tank through a delivery pump. At this time, the washing liquid discharged from the washing tank is sent to the mixing tank through the washing liquid pipe to be mixed with the slurry, diluting the slurry. The diluted slurry enters the mixing device, and according to the solid content of the slurry, an appropriate amount of water is sent into the mixing device to be mixed and diluted with the slurry. Then the diluted slurry is sent to the precipitation tank for precipitation. The precipitated solid is sent to the washing tank through the underflow pipe for washing. After the washing is completed in the washing tank, the washing liquid is discharged into the mixing tank through the washing liquid pipe to dilute the slurry. The solid discharged from the washing tank is sent to the subsequent washing device for continuous washing operation. During this process, the mixing device can fully mix the slurry and water, ensure the uniform distribution of solids in the slurry, ensure the normal transportation of the slurry, avoid blockage, and improve the subsequent sedimentation effect. In this way, this system cancels the conventional dilution tank, can effectively reduce the residence time of the slurry, and the washing liquid discharged from the washing tank is directly sent to the mixing tank, which can also reduce the residence time. After the slurry enters the back tank, it is directly sent to the mixing tank by the delivery pump, reducing the residence time of the washing liquid in the back tank (in the traditional process, the washing liquid needs to be sent into the back tank to be mixed with the slurry). Therefore, it can effectively reduce the residence time of the washing liquid and the slurry, reduce the hydrolysis loss of the sodium aluminate solution, and can effectively reduce the overall load of the system and reduce energy consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 FIG. is a schematic structural diagram of the system for reducing the hydrolysis loss of sodium aluminate in alumina production provided by an embodiment of the present invention;

[0016] Figure 2 FIG. is a schematic structural diagram of a part of the mixing device provided by an embodiment of the present invention;

[0017] Figure 3 FIG. is a schematic structural diagram inside the mixing device provided by an embodiment of the present invention;

[0018] Figure 4 FIG. is a schematic structural diagram of a part of the water inlet pipe provided by an embodiment of the present invention.

[0019] Reference numerals: 10 - back tank, 20 - mixing tank, 30 - mixing device, 31 - static mixer, 311 - sleeve, 312 - baffle, 32 - mixing pipe, 33 - water inlet pipe, 34 - feed chute, 35 - negative pressure pipe, 36 - water pump, 37 - water inlet hole, 38 - sleeve, 40 - precipitation tank, 50 - washing tank, 60 - underflow pipe, 70 - washing liquid pipe. DETAILED DESCRIPTION OF THE INVENTION

[0020] Embodiment

[0021] The following will be further described in conjunction with specific embodiments. As shown in the attached Figure 1 - attached Figure 4 As shown, the system for reducing the hydrolysis loss of sodium aluminate in alumina production in this embodiment includes a subsequent tank 10, a mixing tank 20, a mixing device 30, a precipitation tank 40, and a washing tank 50 connected in sequence; the precipitation tank 40 is communicated with the washing tank 50 through an underflow pipe 60, and the washing tank 50 is connected to the mixing tank 20 through a washing liquid pipe 70. Specifically, during the production process, the digested pulp enters the subsequent tank 10, and the pulp in the subsequent tank 10 is sent into the mixing tank 20 through a delivery pump. At this time, the washing liquid discharged from the washing tank 50 is sent into the mixing tank 20 through the washing liquid pipe 70 to be mixed with the pulp, diluting the pulp. The diluted pulp enters the mixing device 30, and according to the solid content of the pulp, an appropriate amount of water is sent into the mixing device 30 to be mixed and diluted with the pulp. Then the diluted pulp is sent into the precipitation tank 40 for precipitation, and the precipitated solid is sent into the washing tank 50 through the underflow pipe 60 for washing. After the washing is completed in the washing tank 50, the washing liquid is discharged into the mixing tank 20 through the washing liquid pipe 70 to dilute the pulp. The solid discharged from the washing tank 50 is sent into a subsequent washing device for continuous washing operations. During this process, the mixing device 30 can fully mix the pulp and water, ensure uniform distribution of solids in the pulp, ensure normal transportation of the pulp, avoid blockage, and improve the subsequent sedimentation effect. In this way, this system cancels the conventional dilution tank, can effectively reduce the residence time of the pulp, and the washing liquid discharged from the washing tank 50 is directly sent into the mixing tank 20, which can also reduce the residence time. After the pulp enters the subsequent tank 10, it is directly sent into the mixing tank 20 by the delivery pump, reducing the residence time of the washing liquid in the subsequent tank 10 (in the traditional process, the washing liquid needs to be sent into the subsequent tank 10 to be mixed with the pulp). Therefore, it can effectively reduce the residence time of the washing liquid and the pulp, reduce the hydrolysis loss of the sodium aluminate solution. And it can effectively reduce the overall load of the system and reduce energy consumption.

[0022] The mixing device 30 in this embodiment includes a plurality of vertically arranged static mixers 31, a mixing pipe 32 provided at the lower end of the static mixer 31, a water inlet pipe 33 connected to one end of the mixing pipe 32, a feed chute 34 connected to the other end of the mixing pipe 32, and a negative pressure device connected to the feed chute 34; the upper ends of the plurality of static mixers 31 are all communicated with the lower end wall of the mixing tank 20, and the lower ends of the plurality of static mixers 31 are all communicated with the mixing pipe 32; one end of the feed chute 34 far from the mixing pipe 32 is connected to the sedimentation tank 40. One end of the water inlet pipe 33 far from the mixing pipe 32 is arranged in the sedimentation tank 40. Specifically, since the traditional dilution tank is cancelled in this system, the mixing device 30 needs to be used to ensure the mixing effect of the pulp and water. The pulp in the mixing tank 20 directly enters the static mixer 31, and the pulp and washing water are preliminarily mixed in the static mixer 31, and then discharged into the lower mixing pipe 32, where further mixing is carried out. The best sedimentation effect of the pulp can be judged by detecting the solid content of the pulp (too high solid content in the pulp is not conducive to the sedimentation process). Therefore, part of the water can be sent into the mixing pipe 32 through the water inlet pipe 33 to further dilute and mix the pulp. The negative pressure machine and the negative pressure pipe 35 in the negative pressure device generate negative pressure in the feed chute 34. Since one end of the feed chute 34 close to the sedimentation tank 40 is filled with pulp, the negative pressure will act on the mixing pipe 32. Since the static mixer 31 is filled with pulp, the negative pressure will make the flow rate of the pulp in the static mixer 31 faster. In addition, the negative pressure will also act on the water inlet pipe 33, generating negative pressure in the water inlet pipe 33, absorbing the supernatant in the sedimentation tank 40, and sucking the supernatant into the mixing pipe 32 to be mixed and diluted with the pulp.

[0023] One end of the water inlet pipe 33 far from the mixing pipe 32 in this embodiment is connected with a water pump 36. Specifically, the negative pressure generated by the negative pressure device is limited, and too strong negative pressure will instead affect the flow of the pulp into the sedimentation tank 40. Therefore, when a large amount of water is needed to dilute the pulp in the mixing pipe 32, the supernatant in the sedimentation tank 40 can be directly pumped out by the water pump 36 and then directly pumped into the mixing pipe 32.

[0024] One end of the water inlet pipe 33 far from the water pump 36 in this embodiment is arranged inside the mixing pipe 32; a plurality of water inlet holes 37 are opened on the side wall of the part of the water inlet pipe 33 arranged inside the mixing pipe 32, and the plurality of water inlet holes 37 are respectively arranged directly below the plurality of static mixers 31. Specifically, by extending the length of the water inlet pipe 33 inside the mixing pipe 32 and opening a plurality of water inlet holes 37 on the side wall of the water inlet pipe 33, the water discharged from the water inlet holes 37 of the water inlet pipe 33 into the mixing pipe 32 can penetrate into the pulp more fully and evenly, improving the mixing and dilution effect of the water on the pulp.

[0025] The static mixer 31 in this embodiment includes a vertically arranged sleeve 311 and a plurality of baffles 312 staggered in the sleeve 311; the plurality of baffles 312 are evenly distributed in the vertical direction. The lower end of the sleeve 311 is arranged in the mixing pipe 32, and a plurality of sleeves 38 are arranged in the mixing pipe 32; the plurality of sleeves 38 are all sleeved on the water inlet pipe 33, and the plurality of sleeves 38 are evenly distributed along the length direction of the water inlet pipe 33. The water inlet holes 37 are arranged in the sleeves 38, and the lower end of one sleeve 311 communicates with the side wall of one sleeve 38. The axis of the sleeve 38 is parallel to the axis of the sleeve 311. One end of the sleeve 38 facing the feed chute 34 is an open end, and one end of the sleeve 38 away from the feed chute 34 is a sealed end. Specifically, the water sprayed out from the water inlet holes 37 of the water inlet pipe 33 can directly mix with the pulp flowing out from the lower end of the sleeve 311. The mixed pulp flows into the inside of the mixing pipe 32 through the open side of the sleeve 38 and is secondarily mixed with other pulp discharged from the mixing pipe 32, and finally discharged into the feed chute 34. This can effectively ensure the dilution effect of water on the pulp and improve the flow efficiency and sedimentation efficiency of the pulp.

[0026] The mixing pipe 32 in this embodiment is inclined, and the height of the mixing pipe 32 near the feed chute 34 is lower than that of the other end. Specifically, the inclined mixing pipe 32 can enable the pulp therein to flow quickly under the action of gravity and can also prevent the solid part in the pulp from remaining in the mixing pipe 32.

[0027] In summary, for the system for reducing the hydrolysis loss of sodium aluminate in alumina production according to this embodiment, the pulp discharged during the production process enters the back tank 10, and the pulp in the back tank 10 is sent to the mixing tank 20 by a transfer pump. At this time, the washing liquid discharged from the washing tank 50 is sent to the mixing tank 20 through the washing liquid pipe 70 to be mixed with the pulp, diluting the pulp. The diluted pulp enters the mixing device 30, and according to the solid content of the pulp, an appropriate amount of water is sent into the mixing device 30 to be mixed and diluted with the pulp. Then the diluted pulp is sent to the sedimentation tank 40 for sedimentation. The solid after sedimentation is sent to the washing tank 50 through the underflow pipe 60 for washing. After the washing is completed in the washing tank 50, the washing liquid is discharged into the mixing tank 20 through the washing liquid pipe 70 to dilute the pulp. The solid discharged from the washing tank 50 is sent to the subsequent washing device for continuous washing operation. During this process, the mixing device 30 can fully mix the pulp and water, ensure the uniform distribution of solids in the pulp, ensure the normal transportation of the pulp, avoid blockage, and improve the subsequent sedimentation effect. In this way, this system cancels the conventional dilution tank, can effectively reduce the residence time of the pulp, and the washing liquid discharged from the washing tank 50 is directly sent to the mixing tank 20, which can also reduce the residence time. After the pulp enters the back tank 10, it is directly sent to the mixing tank 20 by a transfer pump, reducing the residence time of the washing liquid in the back tank 10 (in the traditional process, the washing liquid needs to be sent into the back tank 10 to be mixed with the pulp). Therefore, it can effectively reduce the residence time of the washing liquid and the pulp, reduce the hydrolysis loss of the sodium aluminate solution. And it can effectively reduce the overall load of the system and reduce energy consumption.

[0028] 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, the present invention can have various modifications and changes. Any modifications, equivalent replacements, improvements, 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 system for reducing the hydrolysis loss of sodium aluminate in alumina production, characterized in that: It comprises a rear tank (10), a mixing box (20), a mixing device (30), a precipitation tank (40), and a washing tank (50) which are connected in sequence; The sedimentation tank (40) is connected to the washing tank (50) through an underflow pipe (60), and the washing tank (50) is connected to the mixing box (20) through a washing liquid pipe (70).

2. The system for reducing the hydrolysis loss of sodium aluminate in alumina production according to claim 1, characterized in that: The mixing device (30) includes a plurality of vertically arranged static mixers (31), a mixing pipe (32) provided at the lower end of the static mixer (31), a water inlet pipe (33) connected to one end of the mixing pipe (32), a feed chute (34) connected to the other end of the mixing pipe (32), and a negative pressure device connected to the feed chute (34); The upper ends of the plurality of static mixers (31) are connected to the lower end wall of the mixing box (20), and the lower ends of the plurality of static mixers (31) are connected to the mixing pipe (32); the end of the feed chute (34) away from the mixing pipe (32) is connected to the sedimentation tank (40).

3. The system for reducing the hydrolysis loss of sodium aluminate in alumina production according to claim 2, wherein: One end of the water inlet pipe (33) away from the mixing pipe (32) is arranged in the sedimentation tank (40).

4. The system for reducing the hydrolysis loss of sodium aluminate in alumina production according to claim 3, characterized in that: One end of the water inlet pipe (33) away from the mixing pipe (32) is connected to a water pump (36).

5. The system for reducing the hydrolysis loss of sodium aluminate in alumina production according to claim 4, characterized in that: One end of the water inlet pipe (33) away from the water pump (36) is arranged inside the mixing pipe (32); The water inlet pipe (33) is provided on a side wall inside the mixing pipe (32) and is provided with a plurality of water inlet holes (37). The plurality of water inlet holes (37) are respectively provided directly below the plurality of static mixers (31).

6. The system for reducing the hydrolysis loss of sodium aluminate in alumina production according to claim 5, characterized in that: The static mixer (31) comprises a vertically arranged sleeve (311) and a plurality of baffles (312) staggered in the sleeve (311); the plurality of baffles (312) are evenly distributed along the vertical direction.

7. The system for reducing the hydrolysis loss of sodium aluminate in alumina production according to claim 6, characterized in that: The lower end of the sleeve (311) is arranged in the mixing tube (32), and a plurality of sleeves (38) are arranged in the mixing tube (32); The plurality of sleeves (38) are sleeved on the water inlet pipe (33), and the plurality of sleeves (38) are evenly distributed along the length direction of the water inlet pipe (33). The water inlet hole (37) is provided in the sleeve (38), and the lower end of one sleeve (311) is communicated with the side wall of one sleeve (38).

8. The system for reducing the hydrolysis loss of sodium aluminate in alumina production according to claim 7, characterized in that: The axis of the sleeve (38) is parallel to the axis of the sleeve (311), the end of the sleeve (38) facing the feed chute (34) is an open end, and the end of the sleeve (38) away from the feed chute (34) is a closed end.

9. The system for reducing the hydrolysis loss of sodium aluminate in alumina production according to claim 8, wherein: The mixing tube (32) is arranged to be inclined, and the height of one end of the mixing tube (32) close to the feed chute (34) is lower than the height of the other end.

Images