A method and device for selecting iron from red mud produced by alumina industry
By stirring and cyclone grading of red mud in alumina production, the refined iron ore is screened out, and the problems of narrow sintering range and low alumina recovery rate caused by high iron content of red mud are solved, and efficient resource recovery and Environmental protection.
Patent Information
- Application Number
- CN202111133233.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2021-09-27
- Publication Date
- 2024-12-24
- Estimated Expiration
- 2041-09-27
AI Technical Summary
During the alumina production process, the high iron content of Bayer method red mud leads to a narrow sintering range, low alumina recovery rate, and large red mud emissions, resulting in high production costs, large land occupation, and unenvironmental problems.
By stirring and cyclone grading of red mud, fine iron ore can be screened out to reduce the iron content of red mud, and multiple cyclone grading and filtration technologies can be used to reduce the iron content of red mud, improve sintering stability and resource recycling and utilization .
It effectively reduces the iron content of red mud in the sintering ingredients, improves the stability of the sintering method and the recovery rate of alumina, reduces the emission and production costs of red mud, extends the service life of the red mud yard, and reduces the Environmental pollution.
Smart Images
Figure CN115872425B_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of alumina production, and in particular to an iron separation method and device for red mud in the production of alumina industry. Background Art
[0002] Red mud is the solid residue after alumina is extracted from bauxite with alkali. It is one of the main factors that cause environmental pollution in the production of alumina. Therefore, the discharge of red mud should be minimized and the recycling and reuse of red mud should be done well. The concept of "Bayer red mud entering sintering for iron selection" originated from the process route developed by Shanxi Aluminum Co., Ltd. in the comprehensive utilization of red mud. Considering the recycling and reuse of Bayer red mud, the process design adopted the Bayer red mud entering the sintering process to form a series process. In order to further improve the value of the comprehensive utilization of red mud, the low-temperature Bayer red mud entering the sintering process is used to form a series process for the production of alumina. The series process for producing alumina uses pure Bayer red mud for batching without adding bauxite. On the one hand, it saves the input of raw materials, and on the other hand, it also improves the recycling value of red mud and saves a lot of production costs.
[0003] However, some bauxites used to produce alumina have a high iron content. The iron content of red mud treated by the Bayer process is generally above 15%, and sometimes even as high as 20%. After the red mud with high iron content and low alumina content is configured into raw material slurry, the positive sintering range is narrow during clinker sintering, and the liquid phase is easy to appear in advance. The clinker kiln skin grows fast and is loose. In production practice, the kiln skin is difficult to control and falls off frequently, and the clinker is very easy to ball. Therefore, the sintering of low aluminum silicon ratio and high iron materials is more difficult, which to a certain extent restricts the production and continuous operation stability of the sintering method clinker kiln. In addition, the high hardness and poor grindability of low aluminum silicon ratio and high iron clinker also restrict the production and operation of the sintering method dissolution mill.
[0004] Therefore, the high iron content of red mud in the Bayer process of cascade production of alumina leads to a narrow sintering range and low alumina recovery rate, and the large red mud emissions lead to high production costs, large land occupation, and environmental pollution in the construction and maintenance of red mud yards. These are technical problems that need to be urgently solved in the current process of cascade production of alumina using low-temperature Bayer red mud as a sintering component. Summary of the invention
[0005] The purpose of the present invention is to reduce the iron content of Bayer red mud in the process of producing alumina by the tandem method, and effectively solve the problem of narrow sintering range of the sintering method; in addition, it can also promote resource recycling, while reducing the discharge of red mud, reducing land occupation, reducing pollution to the environment, reducing red mud yard construction investment and maintenance costs, and extending the service life of the red mud yard.
[0006] The invention provides an iron separation method and device for red mud in the production of alumina industry, which can effectively reduce the iron content of the red mud in sintering ingredients.
[0007] According to a first aspect of the present invention, there is provided a method for iron selection from red mud produced in the alumina industry, the method comprising: stirring the red mud to obtain a raw slurry; subjecting the raw slurry to at least one cyclone classification to obtain a classified underflow, wherein the underflow is a solid iron-containing residue after red mud classification; and filtering the underflow to screen out the iron concentrate.
[0008] Based on the above technical solution, the present invention can also be improved as follows.
[0009] Furthermore, the red mud is stirred to obtain a raw slurry, and the process also includes: adding a dispersant to the red mud and stirring until the mixture is fully mixed.
[0010] Furthermore, the raw material slurry is subjected to at least one cyclone classification to obtain the classified underflow and overflow, wherein the overflow is the liquid waste after red mud classification, and the overflow includes at least: a primary overflow; the primary overflow is transported to a four-wash sedimentation tank, and the four-wash overflow is obtained after sedimentation.
[0011] Furthermore, the raw material slurry is subjected to at least one cyclone classification to obtain a classified bottom flow, wherein the bottom flow is iron-containing solid residue, and also includes: subjecting the raw material slurry to multiple cyclone classifications to obtain a multi-stage bottom flow; stirring the multi-stage bottom flow to obtain a multi-stage raw material slurry; and continuing to subject the multi-stage raw material slurry to cyclone classification to finally obtain a classified bottom flow.
[0012] Furthermore, the raw material slurry is subjected to multiple cyclone classifications to obtain multiple levels of underflow and overflow, and the multiple levels of overflow are mixed with the underflow obtained from the first two levels.
[0013] Furthermore, part of the fourth wash overflow is mixed with the secondary underflow, wherein the secondary underflow is the iron-containing solid residue obtained after the second cyclone classification.
[0014] Furthermore, the underflow is filtered to screen out the iron ore concentrate and obtain a filtrate, which is mixed with the secondary underflow.
[0015] According to the second aspect of the present invention, the present invention also provides an iron selection device for red mud produced by the alumina industry, comprising: at least one mixer for mixing red mud; at least one cyclone for separating and grading red mud; a buffer tank for storing the underflow obtained after the final grading; a filter press for filtering the underflow; the number of mixers is the same as that of cyclones, wherein the mixers and cyclones are arranged at intervals and the mixers and cyclones are connected in series in sequence; the buffer tank is connected to the last cyclone, and the filter press is connected to the buffer tank.
[0016] Furthermore, it also includes a self-circulating pump, which is arranged in the first mixer.
[0017] Furthermore, it also includes a plurality of pumps, which are respectively arranged between the mixer and the cyclone, between the last cyclone and the buffer tank, and between the filter press and the last mixer.
[0018] The present invention provides a method and device for selecting iron from red mud in the production of alumina industry, the method comprising: stirring the red mud to obtain a raw material slurry; subjecting the raw material slurry to at least one cyclone classification to obtain a classified underflow, wherein the underflow is a solid iron residue after the red mud is classified; filtering the underflow to screen out the iron ore concentrate. The present invention solves the technical problem that in the existing tandem method for producing alumina, after the red mud with high iron content and low alumina content is configured into a raw material slurry in the sintering batch, the positive sintering range is narrow during the clinker sintering, and the alumina recovery rate is low; at the same time, the screened iron ore concentrate is used for recycling and smelting, which also solves the technical problems of high production costs, large land occupation, and environmental pollution caused by the construction and maintenance of red mud yards due to large red mud emissions. BRIEF DESCRIPTION OF THE DRAWINGS
[0019] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.
[0020] Figure 1 A schematic flow chart of a method for iron separation from red mud in the production of aluminum oxide provided by the present invention;
[0021] Figure 2 A flow chart of an iron separation process for red mud produced in the aluminum oxide industry provided by the present invention;
[0022] Figure 3 The present invention provides a schematic structural diagram of an iron separation device for producing red mud in the alumina industry. DETAILED DESCRIPTION
[0023] In order to make the above and other features and advantages of the present invention more clear, the present invention is further described below in conjunction with the accompanying drawings. It should be understood that the specific embodiments given herein are for the purpose of explaining to those skilled in the art and are only exemplary and not restrictive.
[0024] In the following description, many specific details are set forth to provide a thorough understanding of the present invention. However, it will be apparent to one of ordinary skill in the art that specific details are not required to practice the present invention. In other cases, well-known steps or operations are not described in detail to avoid obscuring the present invention.
[0025] Embodiment 1
[0026] The present invention provides a method for selecting iron from red mud produced by aluminum oxide industry, such as Figure 1 As shown, the method includes:
[0027] Step S10, stirring the red mud to obtain a raw slurry;
[0028] Specifically, the red mud used in the process of producing alumina by the series method of sintering low-temperature Bayer process red mud into a sintering composition is triple-washed underflow red mud (red mud washed three times). The triple-washed underflow red mud with a solid residue ratio of 10% after sedimentation is transported to the first mixer for stirring. After uniform stirring, the raw slurry to be subjected to cyclone classification is obtained.
[0029] Step S20, subjecting the raw material slurry to at least one cyclone classification to obtain a classified underflow, wherein the underflow is a solid residue containing iron after red mud classification;
[0030] In this scheme, the raw material slurry in step S10 is subjected to at least one cyclone classification. Specifically, the raw material slurry is tangentially injected into the cyclone (the cyclone is a cone) at a certain pressure. Under the action of the high-speed rotating flow field in the cyclone, the component with high density in the raw material slurry moves axially downward and radially outward at the same time, reaches the side wall of the cone and moves downward along the side wall of the cone, forming an outer vortex flow field that moves downward, and the component with high density in the raw material slurry is discharged from the bottom flow port at the bottom of the cyclone, which is called bottom flow. Correspondingly, the component with low density in the raw material slurry moves axially upward under the action of the high-speed rotating flow field in the cyclone, forming an inner vortex that moves upward, and then is discharged from the overflow port, which is called overflow. Therefore, the purpose of two-phase separation is achieved by the above-mentioned cyclone classification method, and the bottom flow is continuously subjected to multiple cyclone classifications to discharge the iron-containing solid residue and obtain red mud that meets the requirements of this process.
[0031] Step S30, filtering the bottom flow to screen out the iron ore concentrate.
[0032] Specifically, in this solution, a plate-frame filter press or a belt filter press is preferably used to filter the solid residue discharged in step S20 to obtain the refined iron ore. It should be noted that the screened refined iron ore can be used in steelmaking and other process links.
[0033] The beneficial effect of this scheme is that it can effectively reduce the iron content of red mud in the sintering ingredients of alumina produced by the series process, so that after the red mud entering the sintering ingredients is configured into raw material slurry, it is not easy to appear liquid phase prematurely when the clinker is burned. In production practice, the clinker kiln is not easy to produce kiln skin, and the clinker is not easy to ball, and the sintering difficulty is small. Therefore, the stability of the sintering clinker kiln in reaching full capacity and continuous operation is increased. In addition, since the raw material slurry entering the sintering ingredients has less iron content, low hardness and good grindability, it also meets the conditions for the sintering method dissolution mill to reach full capacity.
[0034] Optionally, step S10, stirring the red mud to obtain raw slurry, further comprises:
[0035] Step S101: adding a dispersant to the red mud and stirring until it is fully mixed.
[0036] Specifically, in this solution, since the dispersant can promote the uniform dispersion of material particles in the medium, adding the dispersant to the red mud can make the red mud solid particles uniformly dispersed in the liquid, and stirring until fully mixed is more conducive to the cyclone classification of the raw material slurry.
[0037] The beneficial effect of this solution is that adding a dispersant to the red mud makes the solid particles of the red mud more evenly dispersed in the medium, which is beneficial to cyclone classification.
[0038] Optionally, in step S20, the raw material slurry is subjected to at least one cyclone classification to obtain an overflow while obtaining the classified underflow, wherein the overflow is liquid waste after red mud classification, and the overflow includes at least a primary overflow; the step further includes:
[0039] Step S21, transporting the primary overflow to the fourth-wash sedimentation tank, and obtaining the fourth-wash overflow after sedimentation.
[0040] Specifically, in this scheme, the primary overflow is the overflow obtained after the first cyclone classification. The primary overflow is transported to the fourth wash sedimentation tank for sedimentation to obtain the fourth wash overflow. It should be noted that the fourth wash overflow can be returned to the mixer and mixed with the bottom flow, and then cyclone classification is performed after mixing.
[0041] Optionally, step S20, subjecting the raw slurry to at least one cyclone classification to obtain a classified underflow, wherein the underflow is a solid residue containing iron, further comprising:
[0042] Step S201, subjecting the raw material slurry to multiple cyclone classifications to obtain a multi-stage underflow;
[0043] Step S203, stirring the multi-stage underflow to obtain a multi-stage raw slurry;
[0044] Step S205, further subjecting the multi-stage raw material slurry to cyclone classification, and finally obtaining a classified underflow.
[0045] like Figure 2 As shown, specifically, in this scheme, the purpose of performing multiple cyclone classification on the raw slurry is an effective method to reduce the iron content in red mud. This scheme preferably performs three cyclone classification on the raw slurry. First, the three-wash bottom flow red mud is transported to the first mixer for stirring to obtain raw slurry, and the raw slurry is injected into the first cyclone for the first cyclone classification to obtain a first-level bottom flow. The first-level bottom flow is transported to the second mixer for stirring to obtain a first-level raw slurry, and then the first-level raw slurry is injected into the second cyclone for the second cyclone classification to obtain a second-level bottom flow. The second-level bottom flow is transported to the third mixer for stirring to obtain a second-level raw slurry, and then the second-level raw slurry is injected into the third cyclone for the third cyclone classification to obtain a third-level bottom flow. It should be noted that in other optional embodiments, more cyclone classifications can be performed to achieve the purpose of reducing the iron content.
[0046] It should be noted that in another optional embodiment, the raw slurry is subjected to two cyclone classifications. First, the three-wash bottom flow red mud is transported to the first mixer for stirring to obtain raw slurry, and the raw slurry is injected into the first cyclone for the first cyclone classification to obtain a primary bottom flow, and the primary bottom flow is transported to the second mixer for stirring to obtain a primary raw slurry, and then the primary raw slurry is injected into the second cyclone for the second cyclone classification to obtain a secondary bottom flow. In other optional embodiments, the raw slurry can also be subjected to four or more cyclone classifications to achieve the standard requirement of reducing the iron content to a lower level.
[0047] The beneficial effect of this solution is that multiple cyclone classifications can further reduce the iron content in the red mud entering the sintering ingredients to meet the process requirements.
[0048] Optionally, in step S201, the raw material slurry is subjected to multiple cyclone classifications to obtain multiple levels of underflow and overflow, and the multiple levels of overflow are mixed with the underflow obtained from the first two levels.
[0049] Specifically, in the present scheme, the overflow obtained by cyclone classification can also be recycled. For example, in multiple (more than three) cyclone classification processes, the third-level overflow can be mixed with the first-level underflow, and the first-level raw slurry can be obtained after stirring; the second-level overflow can be mixed with the third-wash underflow red mud, and the raw slurry can be obtained after stirring.
[0050] The beneficial effect of this solution is that the overflow obtained by multi-stage cyclone classification is fully recycled and returned to the mixer to be mixed with the underflow, which plays a role in diluting the underflow and makes the material particles evenly dispersed, which is conducive to further cyclone classification. In this process, no additional water is needed to dilute the underflow and disperse the particles, which saves a lot of water resources on the one hand and reduces costs on the other.
[0051] Optionally, part of the fourth wash overflow is mixed with the secondary underflow, wherein the secondary underflow is the iron-containing solid residue obtained after the second cyclone classification.
[0052] In this scheme, in step S21, the primary overflow is transported to the fourth-wash sedimentation tank, and after sedimentation, the fourth-wash overflow is obtained, and the following steps are also included:
[0053] Step S211, part of the fourth wash overflow is mixed with the secondary underflow.
[0054] Specifically, the fourth wash overflow obtained after the first overflow is settled can be returned to the multi-stage cyclone classification process according to actual needs. Preferably, part of the fourth wash overflow is returned and mixed with the second underflow to dilute the second underflow, maintain liquid phase equilibrium, and evenly disperse the material particles after stirring.
[0055] The beneficial effect of this scheme is that the fourth wash overflow obtained after the first overflow is settled is fully recycled and utilized, part of the fourth wash overflow is returned to mix with the second underflow, which dilutes the second underflow, and the material particles are evenly dispersed after stirring, which is conducive to further cyclone classification. No additional water needs to be added in this process, which saves water resources and reduces production costs.
[0056] Optionally, in step S30, the underflow is filtered to screen out the iron ore concentrate and obtain a filtrate, and the steps further include:
[0057] S301, mixing the filtrate with the secondary underflow.
[0058] Specifically, in this solution, the solid residue discharged in step S20 is filtered by a plate and frame filter press or a belt filter press, and the filtrate obtained after filtration is mixed with the secondary underflow, and the secondary underflow is diluted to maintain liquid phase equilibrium.
[0059] The beneficial effect of this solution is that the filtrate is recycled and mixed with the secondary underflow to dilute the secondary underflow, maintain liquid phase equilibrium, and evenly disperse the material particles after stirring, which is beneficial to further cyclone classification. No additional water is required in this process, which can save water resources and reduce production costs while reducing the discharge of waste liquid, which is beneficial to environmental protection.
[0060] Embodiment 2
[0061] According to another aspect of the present invention, there is provided an iron separation device for red mud produced in the alumina industry, comprising: at least one mixer for mixing the red mud; at least one cyclone for separating and grading the red mud; a buffer tank for storing the underflow obtained after the final grading; a filter press for filtering the underflow; the number of mixers is the same as that of cyclones, wherein the mixers and cyclones are arranged at intervals and are connected in series in sequence; the buffer tank is connected to the last cyclone, and the filter press is connected to the buffer tank.
[0062] Specifically, Figure 3 As shown, the preferred iron selection device of this scheme includes: a first mixer 31, a first cyclone 32, a second mixer 33, a second cyclone 34, a third mixer 35, a third cyclone 36, a buffer tank 37 and a filter press 38, and the components are connected in series in the order of the above components. Among them, the three-wash bottom flow red mud can be transported to the first mixer 31 by a pump for stirring to obtain raw material slurry, the raw material slurry is transported to the first cyclone 32 for cyclone classification to obtain a primary bottom flow, and then the primary bottom flow is transported to the second mixer 33 for stirring to obtain a first raw material slurry, the first raw material slurry is transported to the second cyclone 34 for cyclone classification to obtain a secondary bottom flow, and then the secondary bottom flow is transported to the third mixer 35 for stirring to obtain a second raw material slurry, the second raw material slurry is transported to the third cyclone 36 for cyclone classification to obtain a tertiary bottom flow, and then the tertiary bottom flow is transported to the buffer tank 37, and the tertiary bottom flow is transported from the buffer tank 37 to the filter press 38 for filtration to screen out the fine iron ore.
[0063] In a further optional embodiment, the iron selection device further includes a self-circulating pump, and the self-circulating pump is disposed in the first mixer (ie, the first mixer 31).
[0064] Specifically, in the present embodiment, in order to ensure that the red mud is fully mixed and evenly dispersed in the medium, a self-circulating pump is also provided in the first mixer 31 to enhance stirring. It should be noted that a certain amount of dispersant can be added as needed. The dispersant can cause the material particles to be evenly dispersed in the medium. Therefore, adding a dispersant to the red mud can make the red mud solid particles evenly dispersed in the liquid. Stirring until fully mixed is more conducive to the cyclone classification of the raw slurry.
[0065] In a further optional embodiment, the iron selection device further comprises a plurality of pumps, which are respectively arranged between the mixer and the cyclone, between the last cyclone and the buffer tank 37, and between the filter press 38 and the last mixer.
[0066] Specifically, in the present embodiment, the pump is used for conveying the underflow or raw slurry or filtrate. Preferably, a pump is provided between the first mixer 31 and the first cyclone 32, between the first cyclone 32 and the second mixer 33, between the second mixer 33 and the second cyclone 34, between the second cyclone 34 and the third mixer 35, between the third mixer 35 and the third cyclone 36, between the third cyclone 36 and the buffer tank 37, and between the filter press 38 and the third mixer 35.
[0067] It should be noted that the pump is also used for conveying overflow at each level. Preferably, it also includes a four-wash sedimentation tank. Pumps are also provided between the first cyclone 32 and the four-wash sedimentation tank, between the second cyclone 34 and the first mixer 31, between the third cyclone 36 and the second mixer 33, and between the third mixer 35 and the four-wash sedimentation tank.
[0068] The various technical features described above can be combined arbitrarily. Although all possible combinations of these technical features are not described, any combination of these technical features should be considered to be covered by this specification as long as there is no contradiction in such combination.
[0069] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. However, these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.
Claims
1. A method for selecting iron from red mud in the production of aluminum oxide, characterized in that: The method comprises: The red mud is stirred to obtain a raw slurry; The raw material slurry is subjected to multiple cyclone classification to obtain a multi-level underflow; the multi-level underflow is stirred to obtain a multi-level raw material slurry; the multi-level raw material slurry is further subjected to cyclone classification to finally obtain a classified underflow; wherein the underflow is an iron-containing solid residue after red mud classification; The raw material slurry is subjected to multiple cyclone classifications to obtain multiple levels of underflow and overflow; the overflow is liquid waste after red mud classification, and the overflow includes at least: primary overflow; the primary overflow is transported to the fourth wash sedimentation tank, and the fourth wash overflow is obtained after sedimentation; part of the fourth wash overflow is mixed with the secondary underflow, wherein the secondary underflow is the iron-containing solid residue obtained after the second cyclone classification; The bottom flow is filtered to screen out the iron ore concentrate.
2. The method according to claim 1, characterized in that The red mud is stirred to obtain raw slurry, and further comprises: Add dispersant to the red mud and stir until fully mixed.
3. The method according to claim 1, characterized in that The underflow is filtered to screen out the iron ore concentrate and obtain a filtrate, which is then mixed with the secondary underflow.
4. An iron separation device for red mud in the production of aluminum oxide industry according to the method of claim 1, characterized in that: include: at least one mixer for mixing red mud; At least one cyclone for separating and classifying red mud; Buffer tanks for storing the underflow obtained after final classification; A filter press, for filtering the underflow; The number of the mixers is the same as that of the cyclones, wherein the mixers and the cyclones are arranged at intervals and are connected in series in sequence; The buffer tank is connected to the last cyclone, and the filter press is connected to the buffer tank.
5. The device according to claim 4, characterized in that It also includes a self-circulating pump, which is arranged in the first mixer.
6. The device according to claim 4, characterized in that It also includes a plurality of pumps, which are respectively arranged between the mixer and the cyclone, between the last cyclone and the buffer tank, and between the filter press and the last mixer.