A red mud dealkalization device and method

Abstract

The present application relates to a kind of red mud dealkalization device and method, belong to red mud dealkalization technical field.Red mud dealkalization device, comprising: base, hollow cylindrical mixer, feed unit and discharge unit;The mixer is installed on base, mixer is divided into continuous three parts from top to bottom: feed zone, stirring zone and discharge zone;The top end of feed zone is provided with red mud inlet, there are multiple water inlets on the sidewall of feed zone, the direction of water inlet is set along the tangential direction of mixer sidewall, all are left-handed or all are right-handed;The inside of stirring zone is straight cylinder type with same inside diameter from top to bottom;The bottom center of discharge zone is provided with discharge port;The discharge zone inside mixer is provided with reflux plate above it.In the present application, water enters mixer, forms rotating flow state, red mud powder is thrown into rotating flow water from container top, realizes preliminary mixing;Reflux plate forces alkali liquor to flow from around reflux plate, ensures that red mud powder is mixed with water sufficiently, improves mixing efficiency.Due to not using stirring blade, repeated disassembly transmission device is avoided.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of red mud dealkalization, and particularly relates to a red mud dealkalization device and method. BACKGROUND

[0002] The information disclosed in this Background section is for the purpose of generally presenting the context of the application. The information disclosed in this Background section is not to be taken as an acknowledgement or any form of suggestion that this information forms prior art.

[0003] Red mud, also known as Bayer process red mud, is a strong alkaline solid waste produced in the production of alumina. It contains mineral components such as hematite, calcite, calcium melilite, tricalcium aluminate, hydrated garnet, and hydrated sodium aluminosilicate. Due to the small particle size and poor agglomeration of red mud, it is easy to weather and produce dust in the open-air storage yard, polluting the atmospheric environment. When it is recycled and utilized, it needs to be dealkalized. Common treatment methods include water washing, acid leaching, lime method, and salt leaching.

[0004] Water washing is the simplest physical dealkalization treatment method. Water can directly leach the free alkali in red mud, reducing the content of sodium ions and other soluble salts. Water washing requires the water used as a diluent to be in full contact with the red mud. To improve the leaching speed, the red mud needs to be mixed with water in a stirring tank. Due to the presence of a large amount of mineral components in the red mud, it will cause serious wear to the blades of the stirring device, greatly affecting the service life of the equipment; the mineral components will also accumulate in the positions where stirring is insufficient, causing blockage inside the equipment; and frequent replacement of worn parts will also seriously affect the treatment efficiency of the red mud. SUMMARY

[0005] In view of the deficiencies of the prior art, the purpose of the present application is to provide a red mud dealkalization device and method, which sends the material in the tangential direction of the stirring device to produce a stirring effect, without using mechanical devices to stir the red mud slurry, thereby avoiding frequent replacement of stirring blades.

[0006] To achieve the above-mentioned purposes, the technical solution of the present application is as follows:

[0007] In a first aspect, a red mud dealkalization device comprises a base, a hollow cylindrical mixer, a feed unit, and a discharge unit.

[0008] The mixer is installed on a base, and the mixer is divided into three continuous parts from top to bottom: a feeding area, a stirring area and a discharging area; the feeding area is provided with a red mud inlet at the top end, and a plurality of water inlets are arranged on the side wall of the feeding area, and the directions of the water inlets are arranged along the tangential direction of the side wall of the mixer, and the directions are all left-handed or all right-handed; the stirring area is a straight cylinder with the same inner diameter from top to bottom; the discharging area is provided with a discharging port at the center of the bottom; and a reflux plate is arranged above the discharging area in the mixer;

[0009] The feeding unit comprises a red mud input pipe and a water feeding pipe; the red mud input pipe is communicated with the red mud inlet, and the water feeding pipe is communicated with the water inlet;

[0010] The discharging unit comprises a discharging pipe, and the discharging pipe is communicated with the discharging port.

[0011] In a second aspect, a red mud dealkalization method using the red mud dealkalization device is provided, and the method comprises the following steps:

[0012] S1, according to the components of red mud and the target pH value of alkali liquor, the amount of red mud to be input and the amount of water for dilution are obtained;

[0013] S2, according to the amount of water obtained in S1, water is input into the mixer through the feeding unit, and after a rotating flow state is formed in the stirring area, according to the amount of red mud obtained in S1, red mud is input into the mixer through the feeding unit;

[0014] S3, in the mixer, the red mud falls into the rotating flow of water, and mixing and stirring form alkali liquor, which enters the discharging area outside the reflux plate and flows out through the discharging port;

[0015] S4, according to the pH value and the viscosity of the alkali liquor measured by the position of the discharging pipe, the amount of water and the amount of red mud in S2 are adjusted, and if the pH value is consistent with the target pH value of the alkali liquor in S1, the alkali liquor product is obtained.

[0016] The beneficial effects of the present application are:

[0017] 1. In the present application, water enters the mixer in a tangential manner from the periphery of the container, forming a rotating flow state, and red mud powder is thrown into the rotating flow of water from the top of the container, realizing the preliminary mixing of red mud powder and water in the mixer; the reflux plate is arranged in the stirrer, and the reflux plate is fixed in the mixer, forcing the alkali liquor to flow out from the periphery of the reflux plate, and in the area above the reflux plate, the tendency of red mud powder to gradually converge to the center is destroyed, ensuring that the red mud powder and water are fully mixed, and improving the mixing efficiency.

[0018] 2. The present invention does not use stirring blades, thus avoiding wear on the stirring blades caused by the minerals in the red mud powder. At the same time, since there are no stirring blades or other transmission devices in the mixer, the inconvenience of operation caused by repeated disassembly and assembly of transmission devices and the equipment damage caused by wear of transmission devices are avoided. This ensures that the red mud powder and water are fully mixed, thereby improving the mixing efficiency.

[0019] 3. The device of the present invention has important functions such as adjusting valve opening, detecting pH value and viscosity. It can achieve precise control of red mud alkali output and solution pH value during the dealkali process, which greatly improves the flexibility and controllability of the production process, makes the output alkali solution stable and controllable, can adapt to red mud raw materials with different properties, and has high process stability. Attached Figure Description

[0020] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0021] Figure 1 This is a schematic diagram of the red mud dealkali removal device in Example 1.

[0022] Figure 2 This is a schematic diagram of the red mud dealkali removal method in Example 2.

[0023] Among them, 1. Mixer; 11. Red mud inlet; 12. Water inlet; 13. Discharge outlet; 2. Return plate; 21. Support rod; 3. Red mud input pipe; 4. Water supply pipe; 5. Discharge pipe; 6. Return pipe. Detailed Implementation

[0024] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0025] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0026] Example 1

[0027] A red mud dealkali removal device, such as Figure 1 As shown, it includes: a base, a hollow cylindrical mixer 1, a feeding unit, and a discharging unit;

[0028] The mixer 1 is installed on the base and is divided into three continuous parts from top to bottom: a feeding zone, a stirring zone and a discharging zone; the top end of the feeding zone is provided with a red mud inlet 11, and the sidewall of the feeding zone is provided with a plurality of water inlets 12, which are arranged in the tangential direction of the sidewall of the mixer 1 and are all left-handed or all right-handed; the stirring zone is a straight cylinder with the same inner diameter from top to bottom; the bottom center of the discharging zone is provided with a discharge outlet 13; the upper part of the discharging zone in the mixer 1 is provided with a reflux plate 2.

[0029] The feeding unit includes a red mud input pipe 3 and a water supply pipe 4; the red mud input pipe 3 is communicated with the red mud inlet 11 at the top end of the mixer 1, and the water supply pipe 4 is communicated with the water inlets 12 on the sidewall of the mixer 1.

[0030] The discharging unit includes a discharging pipe 5, which is communicated with the discharge outlet 13 of the mixer 1.

[0031] Through the above arrangement, water enters the mixer in a tangential manner from the periphery of the container, forming a rotating flow state, without the need for a stirring device, and red mud powder is thrown into the rotating flow of water from the top of the container with the flowing air, realizing the preliminary mixing of red mud powder and water in the mixer; during the stirring process, the dispersed red mud powder gradually moves downward in a vortex shape in the water and gradually converges towards the center, until it encounters the reflux plate 2, the trend of the red mud powder converging towards the center is destroyed, and the red mud powder enters the discharging zone from the periphery of the reflux plate 2. In the process of uniform mixing, the free alkali in the red mud and other soluble salts are leached into the water as a diluent, and after the alkali liquor output from the discharge outlet 13 is filtered or separated by other solid-liquid separation methods, the dealkalized red mud can be obtained.

[0032] In the mixer 1, the inner diameter of the stirring zone gradually decreases towards the discharge outlet 13, and the discharging zone is between the stirring zone and the discharge outlet 13; since the rotating flow stirring state of the stirring zone is separated by the reflux plate 2, the gradually decreasing inner diameter can increase the flow rate and prevent the deposition of mineral powder at this point.

[0033] The plurality of water inlets 12 are uniformly distributed along the same height, and the number of water inlets 12 is 2-6, preferably 4, and the angle between adjacent water inlets on the sidewall is 90°.

[0034] The up-down inclination angle of the water inlet 12 can be adjusted; since the water inflow is not fixed, the rotating power of the liquid in the stirring zone comes from the water flow of the water inlet 12, so when the water inflow is small, the up-down inclination angle of the water inlet 12 needs to be adjusted to improve the stirring effect of the water flow.

[0035] The reflux plate 2 is installed on the inner wall of the discharging zone through a support rod 21 to avoid disturbing the stirring zone above.

[0036] The reflux plate 2 is perpendicular to the side wall of the mixer 1, and the reflux plate 2 is a circular plate with a diameter smaller than the inner diameter of the mixer 1, and the upper surface of the circular plate is provided with a wear-resistant layer on the side wall. The device in the embodiment cancels the power device such as the stirring blade, but since the reflux plate 2 is located in the center of the rotating flow of the lye, it will be worn by the mineral powder in the lye. The reflux plate 2 is the only device in the device that is easily worn by the mineral powder, and the wear-resistant layer is provided on the upper surface of the reflux plate 2 and the side wall, which can reduce the degree of wear and prolong the replacement cycle of the reflux plate 2.

[0037] A fan is installed on the red mud input pipe 3, and the flowing air transported by the fan drives the red mud powder into the red mud inlet 11 to be poured into the rotating water from above, which is beneficial to uniform mixing.

[0038] The water supply amount of the water supply pipe 4 is adjustable, and the air speed of the fan of the red mud input pipe 3 is adjustable, which can adjust the proportion of red mud and water according to the composition of the treated red mud, and adjust the water level of the stirring area according to the amount of the treated red mud.

[0039] The pH detection device and the viscosity detection device are arranged in the discharge pipe 5, which are used to detect the pH value and the viscosity of the lye output from the discharge port 13, so as to further adjust the water input amount and the red mud input amount.

[0040] The discharge pipe 5 is connected to the stirring area of the mixer 1 through the return pipe 6, and a one-way valve is arranged at the opening end of the return pipe 6 in the stirring area, which prevents the liquid in the stirring area from entering the discharge pipe 5 through the return pipe 6. Preferably, a delivery pump is arranged on the return pipe 6 to provide power for lifting the material in the pipe.

[0041] The viscosity is measured by using an NDJ-4 pointer type online viscometer;

[0042] The liquid flow is measured by using a LUGB-SUP-J medium temperature type liquid flowmeter;

[0043] The red mud feeding air speed flow is measured by using a TMF-I type ball valve plug-in type hot gas mass flowmeter.

[0044] Example 2

[0045] The red mud dealkalization method using the red mud dealkalization device in Example 1, as shown, includes the following steps: Figure 2

[0046] S1, according to the composition of the red mud and the target lye pH value, the amount of red mud to be input and the amount of water for dilution are obtained;

[0047] S2, according to the water amount obtained in S1, the water amount is input to the mixing device through the feeding unit; Figure 1 ​Water is inputted into the mixer 1, and after the water forms a rotating flow state in the stirring area, the amount of red mud obtained in S1 is inputted into the mixer through the feeding unit according to the amount of red mud obtained in S1;

[0048] S3, the red mud falls into the rotating water in the mixer, and the alkali solution is formed by mixing and stirring, and enters the discharge area outside the reflux plate 2, and flows out through the discharge port 13;

[0049] S4, the pH value and the viscosity of the alkali solution obtained according to the position of the discharge pipe 5 are adjusted according to the amount of water and the amount of red mud in S2, and if the pH value is consistent with the target alkali solution pH value in S1, the alkali solution product is obtained.

[0050] Through the above setting, the red mud alkali solution yield and the solution pH value can be accurately controlled, the flexibility and controllability of the production process are greatly improved, the output alkali solution is stable and controllable, and different properties of red mud raw materials can be adapted.

[0051] In the above process, a minimum flow rate is obtained through experiments to ensure sufficient stirring, and the minimum flow rate can maintain the water body in the mixer in a rotational flow state to ensure sufficient stirring; when adjusting the flow rate, the actual flow rate is not less than the minimum flow rate, which can meet the subsequent process requirements;

[0052] Specifically, the minimum flow rate is related to the water level, the up-down inclination angle of the water inlet 12, the specific gravity of the red mud slurry and other factors. The minimum flow rate is an empirical value obtained through experiments, and the mixing degree of red mud and water is measured after the flow rate is changed several times, so as to find the minimum value.

[0053] In S1, the target alkali solution refers to the red mud slurry obtained by mixing red mud and water at the discharge port.

[0054] In S4, the alkali solution refers to the red mud slurry obtained by mixing red mud and water at the discharge port.

[0055] In S2, the input red mud is dry red mud, and the powder particle size range is 100-500 μm, preferably 250 μm, to ensure that the red mud can be thrown into the mixer by the flowing air in the red mud input pipe of the feeding unit.

[0056] In S2, after the water amount in the stirring area reaches the set water level, the red mud is thrown into the mixer through the feeding unit; preferably, the water level of the stirring area is lower than the position of the water inlet 12 and higher than the position of the reflux plate 2, to form a stable rotating water body.

[0057] In S4, if the measured pH value is greater than the target pH value of the lye, continue to detect the viscosity of the lye; if the viscosity of the lye is less than the optimal value, detect the composition of the red mud, adjust the amount of red mud and the amount of water for dilution required to be input in S1, and then continue to measure the pH value of the lye product; if the viscosity of the lye is greater than the optimal value, calculate the amount of water that should continue to be added, correct the amount of water in S2, and then continue to measure the pH value of the lye product.

[0058] In S4, if the measured pH value is less than the target pH value of the lye, continue to detect the viscosity of the lye; if the viscosity of the lye is greater than the optimal value, detect the composition of the red mud, adjust the amount of red mud and the amount of water for dilution required to be input in S1, and then continue to measure the pH value of the lye product; if the viscosity of the lye is greater than the optimal value, calculate the amount of red mud that should continue to be added, correct the amount of red mud input in S2, and then continue to measure the pH value of the lye product.

[0059] The viscosity is detected because the viscosity will change with the different ratios of red mud and incoming water. The viscosity is detected because the subsequent experiments require a certain pH value, and the pH value is adjusted by adjusting the amount of water or the amount of red mud. The specific amount to be adjusted is determined by the viscosity: if the viscosity is too large, only the amount of red mud powder entering can be reduced to lower the pH, or the amount of water entering can be increased to lower the pH. If the viscosity is small, the amount of red mud powder entering or the amount of water entering can be increased to adjust the pH.

[0060] The lye output in S4 needs to be returned to the mixer 1 through the return pipeline 6 for further processing if it is unqualified.

[0061] The existing red mud dealkalization method usually requires multiple water washing of a batch of red mud: the red mud is mixed with water, and after enough sodium ions are dissolved in the water, the dilution water is discharged, the treated red mud is mixed with pure water again, and after enough sodium ions are dissolved in the water, the dilution water is discharged, and the process is repeated multiple times to obtain dealkalized red mud. This is because in the process of constantly replacing the dilution water, the originally undissolved sodium ions in the red mud will continue to dissolve into the dilution water, and after multiple times, it can be stabilized to the equilibrium state. The water washing dealkalization method of the present application benefits from the high efficiency of red mud dispersion, the full stirring action of red mud particles and water during dispersion, and the effect of the reflux plate on prolonging the time of red mud staying in the solution. The reaction is more complete, and compared with the mechanical stirring method using stirring blades, the number of water washing can be reduced. The water washing method of the present application has been experimentally verified, and the specific reduction in the number of water washing varies depending on the type of red mud. Generally, the number of water washing can be reduced by about 25%.

[0062] The above merely provides the preferred embodiments of the present application, and is not used to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modifications, equivalent replacements, improvements, etc. made within the principles and technical scope of the present application shall fall into the scope of the present application.

Claims

1. A red mud dealkali removal device, characterized in that, The system includes a base, a hollow cylindrical mixer, a feeding unit, and a discharging unit. The mixer is mounted on a base and is divided into three continuous sections from top to bottom: a feeding zone, a stirring zone, and a discharging zone. The feeding zone has a red mud inlet at its top and multiple water inlets on its sidewalls, all oriented tangentially to the sidewalls of the mixer, either left-handed or right-handed. The stirring zone is a straight cylindrical section with the same inner diameter at both the top and bottom. The discharging zone has a discharge port at its bottom center. A reflux plate is positioned above the discharging zone inside the mixer, perpendicular to the sidewalls of the mixer. The reflux plate is a circular plate with a diameter smaller than the inner diameter of the mixer, and its upper surface and sidewalls are covered with a wear-resistant layer. The feeding unit includes a red mud input pipe and a water supply pipe; the red mud input pipe is connected to the red mud inlet at the top of the mixer, and the water supply pipe is connected to the water inlet on the side wall of the mixer. The discharge unit includes a discharge pipe, which is connected to the discharge port of the mixer. The inlet's vertical tilt angle is adjustable; the outlet pipe is equipped with a pH value detection device and a viscosity detection device.

2. The red mud dealkali removal device as described in claim 1, characterized in that, In the mixer, the inner diameter of the mixing zone gradually decreases towards the discharge port.

3. The red mud dealkali removal device as described in claim 1, characterized in that, Multiple water inlets are evenly distributed at the same height, with the number of inlets ranging from 2 to 6.

4. The red mud dealkali removal device as described in claim 3, characterized in that, There are 4 water inlets, and the angle between adjacent water inlets on the side wall is 90°.

5. The red mud dealkali removal device as described in claim 1, characterized in that, The return plate is installed on the inner wall of the discharge zone via support rods.

6. The red mud dealkali removal device as described in claim 1, characterized in that, A fan is installed on the red mud input pipe.

7. The red mud dealkali removal device as described in claim 6, characterized in that, The water delivery volume in the water delivery pipe is adjustable, and the fan speed in the red mud input pipe is adjustable.

8. A method for red mud dealkali removal using the red mud dealkali removal device as described in any one of claims 1-7, characterized in that, Includes the following steps: S1. Based on the red mud composition and the target alkaline solution pH value, obtain the amount of red mud to be input and the amount of water to be used for dilution; S2. Based on the amount of water obtained in S1, input water into the mixer through the feeding unit. After forming a rotating flow state in the stirring zone, input red mud into the mixer through the feeding unit based on the amount of red mud obtained in S1. S3. In the mixer, red mud falls into the rotating flowing water, mixes and stirs to form an alkaline solution, and enters the discharge zone on the outside of the reflux plate and flows out through the discharge port. S4. Adjust the amount of water and red mud in S2 according to the pH value and viscosity of the alkaline solution measured at the outlet pipe position. If the pH value is consistent with the target pH value of the alkaline solution in S1, the alkaline solution product is obtained.

9. The red mud dealkali removal method as described in claim 8, characterized in that, In S2, the input red mud is dry red mud with a powder particle size range of 100–500 μm.

10. The red mud dealkali removal method as described in claim 9, characterized in that, The powder particle size is 250μm.

11. The red mud dealkali removal method as described in claim 8, characterized in that, In S2, after the water volume in the mixing zone reaches the set water level, red mud is thrown into the mixer through the feeding unit.

12. The red mud dealkali removal method as described in claim 11, characterized in that, The water level in the mixing zone is lower than that at the inlet but higher than that at the return plate.

13. The red mud dealkali removal method as described in claim 8, characterized in that, In S4, if the measured pH value is greater than the target pH value of the alkali solution, continue to measure the viscosity of the alkali solution; if the viscosity of the alkali solution is less than the optimal value, then measure the red mud composition, adjust the amount of red mud to be input in S1 and the amount of water used for dilution, and then continue to measure the pH value of the alkali solution product; if the viscosity of the alkali solution is greater than the optimal value, then calculate the amount of water to be added, correct the amount of water in S2, and then continue to measure the pH value of the alkali solution product.

14. The red mud dealkali removal method as described in claim 8, characterized in that, In S4, if the measured pH value is less than the target pH value of the alkali solution, continue to measure the viscosity of the alkali solution; if the viscosity of the alkali solution is greater than the optimal value, then measure the red mud component, adjust the amount of red mud to be input in S1 and the amount of water used for dilution, and then continue to measure the pH value of the alkali solution product; if the viscosity of the alkali solution is greater than the optimal value, then calculate the amount of red mud to be added, correct the amount of red mud input in S2, and then continue to measure the pH value of the alkali solution product.

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