Treatment method of bauxite waste red mud

Abstract

The invention relates to the technical field of industrial waste treatment, in particular to a bauxite waste red mud treatment method which comprises the following steps: primarily mixing red mud and phosphogypsum solid waste to obtain a mixture, naturally stacking the mixture, conveying the naturally stacked mixture into a beater for scattering and dispersing, and then drying the scattered and dispersed mixture to obtain red mud powder; the method comprises the following steps: drying the mixture by using a drying machine, continuously dispersing the mixture while drying by using the rotation of the drying machine, conveying the dried mixture into a dry-method flour mill, and milling to obtain a powdery material with the pH value of 6-9. According to the method, an acid-base neutralization mechanism is taken as a main line, the strongly-alkaline red mud is directly mixed with strongly-acidic phosphogypsum solid waste, and the processes of staged processing and multi-stage neutralization reaction are performed, so that the alkalinity of the material is reduced step by step for multiple times, and meanwhile, powder materials with different pH values are obtained by adjusting the weight ratio of the red mud to the phosphogypsum solid waste; the method is suitable for production and application in multiple industries, and industrial utilization of industrial waste is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of industrial waste treatment, in particular to a method for treating bauxite waste red mud. Background Art

[0002] After aluminum enterprises smelt bauxite into aluminum billets, the industrial waste generated is collectively called red mud. The main components of red mud are oxides of iron, titanium, calcium, aluminum, manganese, sodium, and silicon. Because caustic soda is added during the smelting process, the red mud is strongly alkaline, with a pH value of more than 12. At present, the treatment method for red mud is to inject water to turn the red mud into mud, and then use a conveying pump to transport it to the dehydration workshop for dehydration. The dehydrated red mud is transported to the open-air landfill by a conveyor belt for stacking. The moisture content of the stacked red mud is ≤30%.

[0003] These red mud dumps in the open air have caused serious impacts on the surrounding ecological environment. If they are not effectively treated, the surrounding environment will not improve over time, but will become worse and worse. Therefore, how to effectively recycle red mud and turn it into resources is one of the problems that aluminum companies need to solve urgently.

[0004] As for the treatment technology of red mud, the current production is mainly based on water washing and calcination processes, which require huge overall investment and high product costs, which is not conducive to market promotion, nor to the consumption and development and utilization of red mud.

[0005] A large amount of phosphogypsum solid waste (phosphogypsum solid waste) is generated during the production and processing of phosphate mining enterprises. These phosphogypsum solid wastes are highly acidic, with a pH value of about 2, complex composition, and no direct utilization value. The current treatment method is to directly transport them to open-air dumping sites for stacking. The moisture content of the stacked phosphogypsum solid waste is ≤30%. Summary of the invention

[0006] The purpose of the present invention is to provide a method for treating bauxite waste red mud in view of the deficiencies in the prior art. The method takes the acid-base neutralization mechanism as the main line, directly mixes the strongly alkaline red mud with the strongly acidic phosphogypsum solid waste, processes the mixture in stages, and adopts a multi-stage neutralization reaction process to reduce the alkalinity of the material step by step for multiple times. At the same time, by adjusting the weight ratio between the red mud and the phosphogypsum solid waste, powdery materials with different pH values ​​suitable for production and application in multiple industries are obtained, thereby realizing the industrial utilization of industrial waste, providing a sustainable treatment method for waste in the aluminum mining industry, improving the development value of red mud and broadening its application scope.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions:

[0008] A method for treating bauxite waste red mud comprises the following steps: preliminarily mixing red mud with phosphogypsum solid waste to obtain a mixture, naturally stacking the mixture, conveying the naturally stacked mixture to a disperser for dispersion, then drying the dispersed mixture, and continuously dispersing the mixture while drying through the rotation of the dryer itself, and then conveying the dried mixture to a grinding machine for grinding to obtain a powdery material with a pH value of 6 to 9.

[0009] Furthermore, the mixture, by weight, has a ratio of red mud to phosphogypsum solid waste of 7 to 15:1.

[0010] Furthermore, the natural stacking time of the mixture is 24h to 48h.

[0011] Furthermore, the moisture content of the mixture after natural stacking is ≤30%.

[0012] Furthermore, the particle size of the mixed material after being dispersed is ≤20 mm.

[0013] Furthermore, the moisture content of the mixed material after drying is ≤6%.

[0014] Furthermore, the powdery material has a fineness of 100 mesh to 400 mesh.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] 1. The present invention takes the acid-base neutralization mechanism as the main line, and directly mixes the strongly alkaline red mud with the strongly acidic phosphogypsum solid waste continuously, that is, the red mud and the phosphogypsum solid waste are sequentially processed in stages of initial mixing, natural stacking, breaking up and dispersing, drying, and grinding to obtain a multi-stage neutralization reaction, gradually reduce the alkalinity of the mixture, and finally obtain a powdery material with a suitable pH value.

[0017] 2. The present invention mixes red mud and phosphogypsum solid waste in different weight ratios to obtain powders with various pH values, which are suitable for production and application in multiple industries. The pH value of the powders obtained by staged treatment is more uniform, which lays the foundation for subsequent production and application and greatly promotes the industrial utilization of red mud.

[0018] 3. The present invention uses one industrial waste to treat another industrial waste, which greatly simplifies the process flow of treating the two industrial wastes, significantly reduces production and equipment costs, and maximizes the utilization of industrial waste resources at the lowest cost, providing an effective way to effectively treat red mud and improve utilization. DETAILED DESCRIPTION

[0019] In order to enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0020] Considering that red mud is an industrial waste generated by aluminum enterprises after smelting aluminum billets, which contains aluminum oxide, silicon dioxide, iron oxide, calcium oxide and other impurities, phosphogypsum solid waste is a solid waste generated in the production of phosphate ore processing enterprises, which contains anhydrous gypsum, hemihydrate gypsum and dihydrate gypsum and other impurities. Due to different places, there will be some differences in material properties, such as acid-base properties, impurity components, etc. The raw material red mud in the following embodiments is provided by an aluminum company in Pingguo City, Guangxi, and the phosphogypsum solid waste is provided by a phosphate ore enterprise in Chongzuo City, Guangxi.

[0021] The disintegrator and straight-drum dryer used in the embodiment of the present invention are straight-drum dryer equipment produced by Henan Jinhai Heavy Industry Machinery Manufacturing Co., Ltd., and the dry-process grinding mill is the HC pendulum series grinding mill produced by Guangxi Guilin Hongcheng Mining Equipment Manufacturing Co., Ltd.

[0022] Example 1

[0023] 10 parts of red mud and 1 part of phosphogypsum solid waste are selected by weight from an open-air dump, and the red mud and phosphogypsum solid waste are initially stirred and mixed with a large forklift to obtain a mixture, which is then piled in one place after repeated stirring and naturally left to stand for 24 to 48 hours to allow the red mud and phosphogypsum solid waste to fully undergo an acid-base neutralization reaction. During the standing process, the water generated by the first neutralization reaction is collected, and the moisture content of the mixture after standing is ≤30%. The mixture after standing is then transported to a disperser by a forklift and a conveyor belt, and the mixture is dispersed and dispersed, so that the mixture is further evenly mixed, and the mixture undergoes a second acid-base neutralization reaction, and similarly, the water generated by the second neutralization reaction is collected. The dispersed mixture is transported to the straight-drum dryer through the discharging port of the disperser for drying. The mixture is further dispersed and evenly mixed by the heating heat of the combustion furnace and the rotation of the drying drum. The mixture undergoes a third acid-base neutralization reaction. The particle size of the mixture after drying in the straight-drum dryer is ≤20mm, and the moisture content is ≤6%. The dried mixture is packaged in ton bags for later use. The dried mixture is fed into a dry mill to grind into powder. The mixture is further evenly mixed and undergoes a fourth acid-base neutralization reaction. The fineness of the final powder is 400 mesh.

[0024] The pH values ​​of red mud, the mixture left to stand after initial mixing, the mixture after being dispersed, the mixture after drying, and the powdered material after grinding were sampled and tested respectively. The test data verified that the powdered material was neutral. The specific test data are shown in Table 1 below.

[0025] The powdered material was used by a new building materials company in Hezhou, Guangxi to produce 600mm wide and 10mm thick extruded stone-plastic prefabricated wall panels. The produced wall panel samples were inspected for quality and environmental protection. The inspection results were in line with the relevant national indicators. The specific inspection data are shown in Tables 2 and 3 below.

[0026] Example 2

[0027] 15 parts of red mud and 1 part of phosphogypsum solid waste are selected by weight from an open-air dump, and the red mud and phosphogypsum solid waste are initially stirred and mixed with a large forklift to obtain a mixture, which is then piled in one place after repeated stirring and naturally left to stand for 24 to 48 hours to allow the red mud and phosphogypsum solid waste to fully undergo an acid-base neutralization reaction. During the standing process, the water generated by the first neutralization reaction is collected, and the moisture content of the mixture after standing is ≤30%. Afterwards, the mixture after standing is transported to a disperser by the cooperation of a forklift and a conveyor belt, and the mixture is dispersed and dispersed, so that the mixture is further evenly mixed, and the mixture undergoes a second acid-base neutralization reaction, and similarly, the water generated by the second neutralization reaction is collected. The dispersed mixture is transported to the straight-drum dryer through the discharging port of the disperser for drying. The mixture is further dispersed and evenly mixed by the heating heat of the combustion furnace and the rotation of the drying drum. The mixture undergoes the third acid-base neutralization reaction. The particle size of the mixture after drying in the straight-drum dryer is ≤20mm, and the moisture content is ≤6%. The dried mixture is packaged in ton bags for later use. The dried mixture is fed into the dry mill to be ground into powder. The mixture is further evenly mixed and undergoes the fourth acid-base neutralization reaction. The fineness of the final powder is 260 mesh.

[0028] The pH values ​​of red mud, the mixture left to stand after initial mixing, the mixture after being dispersed, the mixture after drying, and the powdered material after grinding were sampled and tested respectively. The test data verified that the powdered material was weakly alkaline. The specific test data are shown in Table 1 below.

[0029] The powdered material was used by a manufacturing enterprise in Baise, Guangxi to produce 210mm wide and 25mm thick PE co-extruded garden flooring. The produced board samples were inspected for quality and environmental protection. The inspection results were in line with the relevant national indicators. The specific inspection data are shown in Tables 2 and 3 below.

[0030] Example 3

[0031] 12 parts of red mud and 1 part of phosphogypsum solid waste are selected by weight from an open-air dump, and the red mud and phosphogypsum solid waste are initially stirred and mixed with a large forklift to obtain a mixture, which is then piled in one place after repeated stirring and naturally left to stand for 24 to 48 hours to allow the red mud and phosphogypsum solid waste to fully undergo an acid-base neutralization reaction. During the standing process, the water generated by the first neutralization reaction is collected, and the moisture content of the mixture after standing is ≤30%. Afterwards, the mixture after standing is transported to a disperser by the cooperation of a forklift and a conveyor belt, and the mixture is dispersed and dispersed, so that the mixture is further evenly mixed, and the mixture undergoes a second acid-base neutralization reaction, and similarly, the water generated by the second neutralization reaction is collected. The dispersed mixture is transported to the straight-cylinder dryer through the discharging port of the disperser for drying. The mixture is further dispersed and evenly mixed by the heating heat of the combustion furnace and the rotation of the drying cylinder. The mixture undergoes a third acid-base neutralization reaction. The particle size of the mixture after drying in the straight-cylinder dryer is ≤20mm, and the moisture content is ≤6%. The dried mixture is packaged in ton bags for later use. The dried mixture is fed into a dry mill to grind into powder. The mixture is further evenly mixed and undergoes a fourth acid-base neutralization reaction. The fineness of the final powder is 100 mesh.

[0032] The pH values ​​of red mud, the mixture left to stand after initial mixing, the mixture after being dispersed, the mixture after drying, and the powdered material after grinding were sampled and tested respectively. The test data verified that the powdered material was weakly alkaline. The specific test data are shown in Table 1 below.

[0033] The powdered material was used by a new building materials company in Nanning, Guangxi to produce polymer waterproof mortar, and the polymer waterproof mortar samples produced were inspected for quality and environmental protection. The inspection results were in line with the relevant national indicators. The specific inspection data are shown in Table 4 below.

[0034] Example 4

[0035] 7 parts of red mud and 1 part of phosphogypsum solid waste are selected by weight from an open-air dump, and the red mud and phosphogypsum solid waste are initially stirred and mixed with a large forklift to obtain a mixture, which is then piled in one place after repeated stirring and naturally left to stand for 24 to 48 hours to allow the red mud and phosphogypsum solid waste to fully undergo an acid-base neutralization reaction. During the standing process, the water generated by the first neutralization reaction is collected, and the moisture content of the mixture after standing is ≤30%. Afterwards, the mixture after standing is transported to a disperser by the cooperation of a forklift and a conveyor belt, and the mixture is dispersed and dispersed, so that the mixture is further evenly mixed, and the mixture undergoes a second acid-base neutralization reaction, and similarly, the water generated by the second neutralization reaction is collected. The dispersed mixture is transported to the straight-drum dryer through the discharging port of the disperser for drying. The mixture is further dispersed and evenly mixed by the heating heat of the combustion furnace and the rotation of the drying drum. The mixture undergoes a third acid-base neutralization reaction. The particle size of the mixture after drying in the straight-drum dryer is ≤20mm, and the moisture content is ≤6%. The dried mixture is packaged in ton bags for later use. The dried mixture is fed into a dry mill to grind into powder. The mixture is further evenly mixed and undergoes a fourth acid-base neutralization reaction. The fineness of the final powder is 150 mesh.

[0036] The pH values ​​of red mud, the mixture left to stand after initial mixing, the mixture after being dispersed, the mixture after drying, and the powdered material after grinding were sampled and tested respectively. The test data verified that the powdered material was weakly acidic. The specific test data are shown in Table 1 below.

[0037] The powdered material was used by a new building materials company in Nanning, Guangxi to produce cement-based self-leveling mortar. The cement-based self-leveling mortar samples were tested for quality and environmental protection. The test results were in line with the relevant national indicators. The specific test data are shown in Table 5 below.

[0038] Table 1 pH value test data of red mud, initial mixed and static mixture, dispersed mixture, dried mixture and powdered material in Examples 1 to 4

[0039]

[0040] Table 2 Quality inspection data of the wallboard samples in Example 1 and the floor samples in Example 2

[0041]

[0042]

[0043] Table 3 Environmental testing data of the wallboard samples in Example 1 and the floor samples in Example 2

[0044]

[0045] Table 4 Quality and environmental inspection data of polymer waterproof mortar in Example 3

[0046]

[0047]

[0048] Table 5 Quality and environmental inspection data of self-leveling mortar in Example 4

[0049]

[0050] In summary, the present application adopts a mode of mixing red mud and phosphogypsum solid waste in stages for multiple neutralization reactions, which effectively reduces the alkalinity of red mud without washing and calcining the red mud and phosphogypsum solid waste, and produces a powder material with a pH value between 6 and 9 according to different weight proportions. After quality and environmental protection inspections, it is suitable for production and utilization in multiple industries, simplifies the treatment, production and utilization processes of red mud, and improves the utilization rate of red mud. It is a new concept of red mud treatment method, which lays the foundation for the industrial utilization of red mud and increases added value.

[0051] Although the present invention has been described using the above preferred embodiments, it is not intended to limit the scope of protection of the present invention. Any person skilled in the art who makes various changes and modifications to the above embodiments without departing from the spirit and scope of the present invention still fall within the scope of protection of the present invention.

Claims

1. A method for treating bauxite waste red mud, characterized in that: The red mud and the phosphogypsum solid waste are initially mixed to obtain a mixture, which is naturally piled up, and the mixture after natural stacking is conveyed to a disperser for dispersion, and then the dispersed mixture is dried, and then the dried mixture is conveyed to a grinder for grinding to obtain a powdery material with a pH value of 6 to 9.

2. The method for treating bauxite waste red mud according to claim 1, characterized in that: In the mixture, the ratio of red mud to phosphogypsum solid waste is 7 to 15:1 by weight.

3. The method for treating bauxite waste red mud according to claim 1, characterized in that: The natural stacking time of the mixture is 24h to 48h.

4. The method for treating bauxite waste red mud according to claim 1 or 3, characterized in that: The moisture content of the mixture after natural stacking is ≤30%.

5. The method for treating bauxite waste red mud according to claim 1, characterized in that: The particle size of the mixed material after being dispersed is ≤20mm.

6. The method for treating bauxite waste red mud according to claim 1, characterized in that: The moisture content of the mixed material after drying is ≤6%.

7. The method for treating bauxite waste red mud according to claim 1, characterized in that: The fineness of the powder material is 100-400 meshes.

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