Composite modified bentonite, preparation method and mixing mill

Abstract

The invention discloses composite modified bentonite, a preparation method and a mixing mill, the preparation method comprises the steps of bentonite impurity removal, primary modification by a modifier, aging, drying, mixing modification and grinding, the bentonite, an inorganic modifier and an organic modifier are mixed according to the proportion, mixing modification is performed by the mixing mill, and grinding is performed to finally obtain the composite modified bentonite. The method is simple in process, easy to operate and low in modification cost, the quality of the bentonite can be effectively improved, efficiency is considered while the quality of the bentonite is guaranteed, the bentonite is compounded and modified by adopting the inorganic modifier and the organic modifier, and the problems that most domestic bentonite is calcium bentonite, and the calcium bentonite is low in expansion index, low in water absorption rate and poor in water absorption rate are solved. When the additive is used in the pellets, the grade of the pellets can be reduced due to high addition amount; the use amount of the composite modified bentonite in the pellets can be effectively reduced, and the grade of the pellets is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of refractory materials, and in particular relates to a composite modified bentonite, a preparation method and a mixer. Background Art

[0002] Bentonite, also known as bentonite, is a non-metallic mineral with montmorillonite as the main mineral component. It is widely used in various industrial fields due to its special chemical properties, such as adsorption, adhesion and cation exchange. In metallurgical industry applications, in order to optimize the hydration properties of bentonite, it is necessary to perform sodium modification on bentonite to improve the physical and chemical properties and process performance of bentonite.

[0003] At present, most bentonites on the market are calcium-based bentonites, which have many impurities and poor quality. The proportion used in production is as high as 3%, which seriously reduces the iron grade of pellets. Therefore, improving the quality of bentonite has become a new goal for researchers, but most of the current research on improving the quality of bentonite and applying it to pellets has the problems of complicated processes, high costs, and relatively simple quality improvement and modification, and it is impossible to ensure the quality of bentonite while taking into account efficiency.

[0004] Therefore, developing a bentonite modification process to solve the above problems is the key to solving the problem. Summary of the invention

[0005] The first object of the present invention is to provide a composite modified bentonite, the second object is to provide a method for preparing the composite modified bentonite, and the third object is to provide a composite modified bentonite mixer.

[0006] The first object of the present invention is achieved as follows: by weight percentage, it includes: 95% to 99% bentonite, 1% to 5% inorganic modifier, and 1% to 5% organic modifier; wherein the inorganic modifier includes one or more of Na2CO3, NaOH, NaCL, Li2CO3, LiOH, and LiCL; and the organic modifier includes one or more of carboxymethyl cellulose, carboxymethyl starch, dextrin, chitosan, sodium polyacrylate, and humic acid.

[0007] The second object of the present invention is achieved by the following specific steps: S1. Bentonite impurity removal, removing large-volume sand and gravel impurities in the bentonite ore, then adding a certain amount of water to slurry, secondary filtration to remove impurities, and obtain bentonite slurry; S2. Modification and aging of the modifier: add 1% to 5% of inorganic modifier to the bentonite slurry, stir evenly, and let it stand for a certain period of time for aging, the aging time is not less than 7 days, and a compacted bentonite block is obtained; S3, drying, breaking up the aged bentonite blocks, and then sending them into the drying equipment for baking, baking the moisture content to 13%~16%; S4, mixing and modifying, the bentonite prepared in step S3 and 1% to 5% of the organic modifier are mixed in a mixer for mixing for 25 to 40 minutes, so that the organic modifier and the bentonite are fully combined to complete the organic modification; S5, grinding, grinding the bentonite obtained in step S4, requiring the particle size to be ≤ 200 mesh, to obtain composite modified bentonite.

[0008] The third object of the present invention is achieved as follows: it includes a frame assembly, a mixing box, a mixing cover, mixing rollers, a mixing motor and a feeding mechanism, the mixing box is a trough-shaped structure with an open top, and a plurality of mixing rollers perpendicular to the axis line are arranged in the mixing box, and the two ends of the mixing rollers are respectively connected and fixed to the side walls of the mixing box through bearings, and any end of each mixing roller is respectively connected to the mixing motor by transmission, and a mixing cover is detachably arranged on the top of the mixing box, the mixing box is obliquely arranged on the frame assembly, and a feeding mechanism is arranged at the upper end of the mixing box.

[0009] The beneficial effects of the present invention are as follows: 1. By using an inorganic modifier and an organic modifier to compositely modify bentonite, the problem that most domestic bentonites are calcium-based bentonite, which has a low expansion index and low water absorption rate, and a high amount of calcium-based bentonite added when used in pellets will reduce the pellet grade is solved; the composite modified bentonite can effectively reduce the amount used in pellets and improve the pellet grade; 2. The oxygen-containing functional groups such as hydroxyl and carboxyl contained in the organic modifier are adsorbed on the surface of bentonite. When preparing iron ore pellets, the connection between the organic modified bentonite and the iron concentrate is strengthened, and the hydrophilicity of the surface of the iron concentrate is increased, thereby achieving the effect of improving the strength of the green ball, reducing the amount of bentonite used, and reducing costs; 3. The process is simple, easy to operate, and has low modification cost. It can effectively improve the quality of bentonite, while ensuring the quality of bentonite and taking efficiency into consideration. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 It is a structural schematic diagram of the present invention; Figure 2 It is a schematic diagram of the three-dimensional structure of the present invention; Figure 3 It is a schematic diagram of the structure of the mixing box and the mixing roller; Figure 4 It is a structural schematic diagram of a mixing box; Figure 5 It is a schematic diagram of the structure of the mixed rolling cover plate when viewed from above; Figure 6 It is a schematic diagram of the top view of the feeding mechanism; Numbers in the figure: 1~ frame assembly, 2~ mixing box, 3~ mixing and grinding cover, 4~ mixing and grinding roller, 5~ mixing and grinding motor, 6~ feeding mechanism, 7~ scraper, 8~ transmission, 9~ discharge port. DETAILED DESCRIPTION

[0011] In order to enable those skilled in the art to better understand the technical solution of the present invention, its specific implementation method is described in detail below with reference to the accompanying drawings.

[0012] A composite modified bentonite, comprising, by weight percentage: 95% to 99% bentonite, 1% to 5% inorganic modifier, and 1% to 5% organic modifier; wherein: The inorganic modifier includes one or more of Na2CO3, NaOH, NaCL, Li2CO3, LiOH, and LiCL; The organic modifier includes one or more of carboxymethyl cellulose, carboxymethyl starch, dextrin, chitosan, sodium polyacrylate and humic acid.

[0013] A method for preparing a composite modified bentonite, the specific steps are as follows: S1. Bentonite impurity removal, removing large-volume sand and gravel impurities in the bentonite ore, then adding a certain amount of water to slurry, secondary filtration to remove impurities, and obtain bentonite slurry; S2. Modification and aging of the modifier: add 1% to 5% of inorganic modifier to the bentonite slurry, stir evenly, and let it stand for a certain period of time for aging, the aging time is not less than 7 days, and a compacted bentonite block is obtained; S3, drying, breaking up the aged bentonite blocks, and then sending them into the drying equipment for baking, baking the moisture content to 13%~16%; S4, mixing and modifying, the bentonite prepared in step S3 and 1% to 5% of the organic modifier are mixed in a mixer for mixing for 25 to 40 minutes, so that the organic modifier and the bentonite are fully combined to complete the organic modification; S5, grinding, grinding the bentonite obtained in step S4, requiring the particle size to be ≤ 200 mesh, to obtain composite modified bentonite.

[0014] like Figures 1 to 6The composite modified bentonite mixer shown in the figure includes a frame assembly 1, a mixing box 2, a mixing cover 3, a mixing roller 4, a mixing motor 5 and a feeding mechanism 6. The mixing box 2 is a trough-shaped structure with an open top. A plurality of mixing rollers 4 are arranged in the mixing box 2 perpendicular to the axis thereof. The gap distance between the mixing rollers 4 and the inner bottom plate of the mixing box 2 is 0.5-5 cm. The two ends of the mixing rollers 4 are respectively connected and fixed to the side walls of the mixing box 2 through a rotating shaft and a bearing. In order to ensure the mixing effect , to prevent bentonite from leaking from both ends, the distance between the two end surfaces of the mixing roller 4 and the side wall of the mixing box 2 is 0.5~1cm, and a driving wheel is respectively arranged at either end of each mixing roller 4 to connect the mixing motor 5 through a belt or chain transmission. In order to control the speed difference of the mixing roller 4 and improve the mixing effect, a transmission 8 is arranged at the rotating shaft at one end where the mixing roller 4 is connected to the mixing motor 5, or at the output end of the mixing motor 5 to control the speed of each mixing roller 4, thereby extending the rolling and mixing time, and a driving wheel is also arranged at the output end of the transmission 8; A mixing and grinding cover plate 3 is detachably arranged on the top of the mixing box 2, and a plurality of scrapers 7 obliquely downward are arranged on the lower surface of the mixing and grinding cover plate 3, and the angle β between the scrapers 7 and the mixing and grinding cover plate 3 is an acute angle. The number of scrapers 7 is consistent with the number of mixing and grinding rollers 4, and the scrapers 7 are located above the mixing and grinding rollers 4, and the gap distance between the scrapers 7 and the mixing and grinding rollers 4 is 1-3 cm; the mixing box 2 is obliquely arranged on the frame assembly 1, and the inclination angle between the mixing box 2 and the horizontal plane is 15°-20°, that is, the upper end of the mixing box 2 is a feed port and the lower end is a discharge port 9, and a feeding mechanism 6 is arranged at the upper end of the mixing box 2, and the feeding mechanism 6 is a screw feeder, and its bottom is connected to the upper end of the mixing box 2.

[0015] The process of the present invention is specifically described below in conjunction with embodiments.

[0016] Example 1

[0017] A method for preparing a composite modified bentonite, the specific steps are as follows: S1, bentonite impurity removal, remove the bulk sand and gravel impurities in the bentonite ore, then take 95% of the bentonite by weight and add a certain amount of water to slurry, filter twice to remove impurities, and obtain bentonite slurry; S2, the modifier is modified and aged once, 1% inorganic modifier is added to the bentonite slurry and stirred evenly, the inorganic modifier includes one or more of Na2CO3, NaOH, NaCL, Li2CO3, LiOH, LiCL, and the slurry is left to stand for a certain period of time for aging, and the standing aging time is not less than 7 days to obtain a compacted bentonite block; S3, drying, breaking up the aged bentonite blocks, and then sending them into the drying equipment for baking, baking the moisture content to 13%~16%; S4, mixing and modifying, the bentonite prepared in step S3 and 1% of the organic modifier are mixed and put into the mixer described in the present application for mixing, and the mixing time is 25 to 40 minutes. The organic modifier includes one or more of carboxymethyl cellulose, carboxymethyl starch, dextrin, chitosan, sodium polyacrylate, and humic acid, so that the organic modifier is fully combined with the bentonite to complete the organic modification; S5, grinding, grinding the bentonite obtained in step S4, requiring the particle size to be ≤200 mesh, to obtain composite modified bentonite; S6, the mixing working mode of the mixer in step S4: start the feeding mechanism 6, the mixing and rolling motor 5, and put the bentonite obtained in step S3 and 1% organic modifier into the feeding mechanism 6 of the mixing and rolling mud extruder described in the present application at the same time, and after being mixed by the feeding mechanism 6, send it into the mixing box 2 for mixing for 25-40 minutes, and each mixing and rolling roller 4 rotates clockwise to roll the bentonite and the organic modifier in turn, so that the bentonite and the organic modifier are fully combined, the purpose is to promote the mixing of the bentonite and the modifier through repeated rolling, and at the same time, it can also avoid the formation of a water-proof film on the surface of the bentonite and affect the reaction of the bentonite and sodium carbonate inside; finally, it is discharged from the discharge port 9 at the lower end of the mixing box 2. In the process of rolling the bentonite and the organic modifier, the bentonite attached to the mixing and rolling roller 4 will be scraped off by the scraper 7, and continue to participate in rolling and mixing until it is discharged, that is, the composite modified bentonite is obtained.

[0018] Example 2

[0019] A method for preparing a composite modified bentonite, the specific steps are as follows: S1, bentonite impurity removal, remove the bulk sand and gravel impurities in the bentonite ore, then take 97% of the bentonite by weight and add a certain amount of water to slurry, filter twice to remove impurities, and obtain bentonite slurry; S2, the modifier is modified and aged once, 3% of the inorganic modifier is added to the bentonite slurry and stirred evenly, the inorganic modifier includes one or more of Na2CO3, NaOH, NaCL, Li2CO3, LiOH, LiCL, and the slurry is left to stand for a certain period of time for aging, and the standing aging time is not less than 7 days to obtain a compacted bentonite block; S3, drying, breaking up the aged bentonite blocks, and then sending them into the drying equipment for baking, baking the moisture content to 13%~16%; S4, mixing and modifying, the bentonite prepared in step S3 and 3% of the organic modifier are mixed and put into the mixer described in the present application for mixing, and the mixing time is 25 to 40 minutes. The organic modifier includes one or more of carboxymethyl cellulose, carboxymethyl starch, dextrin, chitosan, sodium polyacrylate, and humic acid, so that the organic modifier is fully combined with the bentonite to complete the organic modification; S5, grinding, grinding the bentonite obtained in step S4, requiring the particle size to be ≤200 mesh, to obtain composite modified bentonite; S6, step S4, the mixing working mode of the mixer in step S4: start the feeding mechanism 6, the mixing and grinding motor 5, and put the bentonite prepared in step S3 and 3% organic modifier into the feeding mechanism 6 of the mixing and grinding mud extruder described in the present application at the same time, and after being mixed by the feeding mechanism 6, send it into the mixing box 2 for mixing for 25-40 minutes, and each mixing and grinding roller 4 rotates clockwise to roll the bentonite and the organic modifier in turn, so that the bentonite and the organic modifier are fully combined, the purpose is to promote the mixing of the bentonite and the modifier through repeated rolling, and at the same time, it can also avoid the formation of a water-proof film on the surface of the bentonite and affect the reaction of the bentonite and sodium carbonate inside; finally, it is discharged from the discharge port 9 at the lower end of the mixing box 2. In the process of rolling the bentonite and the organic modifier, the bentonite attached to the mixing and grinding roller 4 will be scraped off by the scraper 7, and continue to participate in rolling and mixing until it is discharged, that is, the composite modified bentonite is obtained.

[0020] Example 3

[0021] A method for preparing a composite modified bentonite, the specific steps are as follows: S1, bentonite impurity removal, remove the bulk sand and gravel impurities in the bentonite ore, then take 99% of the bentonite by weight and add a certain amount of water to slurry, filter twice to remove impurities, and obtain bentonite slurry; S2, the modifier is modified and aged once, 5% of the inorganic modifier is added to the bentonite slurry and stirred evenly, the inorganic modifier includes one or more of Na2CO3, NaOH, NaCL, Li2CO3, LiOH, LiCL, and the slurry is left to stand for a certain period of time for aging, and the standing aging time is not less than 7 days to obtain a compacted bentonite block; S3, drying, breaking up the aged bentonite blocks, and then sending them into the drying equipment for baking, baking the moisture content to 13%~16%; S4, mixing and modifying, the bentonite prepared in step S3 and 5% of the organic modifier are mixed and put into the mixer described in the present application for mixing, and the mixing time is 25 to 40 minutes. The organic modifier includes one or more of carboxymethyl cellulose, carboxymethyl starch, dextrin, chitosan, sodium polyacrylate, and humic acid, so that the organic modifier is fully combined with the bentonite to complete the organic modification; S5, grinding, grinding the bentonite obtained in step S4, requiring the particle size to be ≤200 mesh, to obtain composite modified bentonite; S6, the mixing working mode of the mixer in step S4: start the feeding mechanism 6, the mixing and rolling motor 5, and put the bentonite prepared in step S3 and 5% organic modifier into the feeding mechanism 6 of the mixing and rolling mud extruder described in the present application at the same time, and after being mixed by the feeding mechanism 6, send it into the mixing box 2 for mixing for 25 to 40 minutes, and each mixing and rolling roller 4 rotates clockwise to roll the bentonite and the organic modifier in turn, so that the bentonite and the organic modifier are fully combined, and finally discharged from the discharge port 9 at the lower end of the mixing box 2. In the process of rolling the bentonite and the organic modifier by each mixing and rolling roller 4, the bentonite attached to the mixing and rolling roller 4 will be scraped off by the scraper 7, and continue to participate in rolling and mixing until it is discharged, that is, the composite modified bentonite is obtained.

[0022] Example 4

[0023] A method for preparing a composite modified bentonite, the specific steps are as follows: S1, bentonite impurity removal, remove the bulk sand and gravel impurities in the bentonite ore, then take 99% of the bentonite by weight and add a certain amount of water to slurry, filter twice to remove impurities, and obtain bentonite slurry; S2, the modifier is modified and aged once, 4% of an inorganic modifier is added to the bentonite slurry and stirred evenly, the inorganic modifier includes one or more of Na2CO3, NaOH, NaCL, Li2CO3, LiOH, and LiCL, and the slurry is left to stand for a certain period of time for aging, and the standing aging time is not less than 7 days to obtain a compacted bentonite block; S3, drying, breaking up the aged bentonite blocks, and then sending them into the drying equipment for baking, baking the moisture content to 13%~16%; S4, mixing and modifying, the bentonite prepared in step S3 and 3% of the organic modifier are mixed and put into the mixer described in the present application for mixing, the organic modifier includes one or more of carboxymethyl cellulose, carboxymethyl starch, dextrin, chitosan, sodium polyacrylate, and humic acid, so that the organic modifier is fully combined with the bentonite to complete the organic modification; S5, grinding, grinding the bentonite obtained in step S4, requiring the particle size to be ≤200 mesh, to obtain composite modified bentonite; S6, the mixing working mode of the mixer in step S4: start the feeding mechanism 6, the mixing and rolling motor 5, and put the bentonite prepared in step S3 and 3% organic modifier into the feeding mechanism 6 of the mixing and rolling mud extruder described in the present application at the same time, and after being mixed by the feeding mechanism 6, send it into the mixing box 2 for mixing for 25 to 40 minutes, and each mixing and rolling roller 4 rotates clockwise to roll the bentonite and the organic modifier in turn, so that the bentonite and the organic modifier are fully combined, and finally discharged from the discharge port 9 at the lower end of the mixing box 2. In the process of rolling the bentonite and the organic modifier by each mixing and rolling roller 4, the bentonite attached to the mixing and rolling roller 4 will be scraped off by the scraper 7, and continue to participate in rolling and mixing until it is discharged, that is, the composite modified bentonite is obtained.

[0024] Experimental Example According to the above scheme, a composite modified bentonite sample was prepared and pelletized with ordinary sodium bentonite for relevant physical property testing. The amount of iron ore used in the preparation was the same, and the performance of the prepared pellets was compared. The comparison results are shown in the following table. It can be seen from the above table that the basic indicators and performance indicators of the modified bentonite prepared by this method are greatly improved compared with ordinary sodium bentonite, especially in terms of blue absorption, expansion capacity, compressive strength, etc. The performance improvement exceeds 10%, and the bentonite consumption in a single unit is significantly reduced, which is only 65-70% of the consumption of ordinary sodium bentonite; therefore, the composite modified bentonite prepared by this method can completely replace the existing ordinary sodium bentonite and be used in the metallurgical industry, and has a significant effect on improving the grade of iron ore pellets.

Claims

1. A composite modified bentonite, characterized in that: Calculated by weight percentage, it includes: 95% to 99% bentonite, 1% to 5% inorganic modifier, and 1% to 5% organic modifier.

2. The composite modified bentonite according to claim 1, characterized in that: The inorganic modifier includes one or more of Na2CO3, NaOH, NaCL, Li2CO3, LiOH, and LiCL.

3. The composite modified bentonite according to claim 1, characterized in that: The organic modifier includes one or more of carboxymethyl cellulose, carboxymethyl starch, dextrin, chitosan, sodium polyacrylate and humic acid.

4. A method for preparing the composite modified bentonite according to any one of claims 1 to 3, characterized in that: The specific steps are as follows: S1. Bentonite impurity removal, removing large-volume sand and gravel impurities in the bentonite ore, then adding a certain amount of water to slurry, secondary filtration to remove impurities, and obtain bentonite slurry; S2. Modification and aging of the modifier: add 1% to 5% of inorganic modifier to the bentonite slurry, stir evenly, and let it stand for a certain period of time for aging, the aging time is not less than 7 days, and a compacted bentonite block is obtained; S3, drying, breaking up the aged bentonite blocks, and then sending them into the drying equipment for baking, baking the moisture content to 13%~16%; S4, mixing and modifying, the bentonite prepared in step S3 and 1% to 5% of the organic modifier are mixed in a mixer for mixing for 25 to 40 minutes, so that the organic modifier and the bentonite are fully combined to complete the organic modification; S5, grinding, grinding the bentonite obtained in step S4, requiring the particle size to be ≤ 200 mesh, to obtain composite modified bentonite.

5. A composite modified bentonite mixer for use in any one of claims 1 to 4, characterized in that: The invention comprises a frame assembly (1), a mixing box (2), a mixing cover plate (3), mixing rollers (4), a mixing motor (5) and a feeding mechanism (6). The mixing box (2) is a trough-shaped structure with an open top. A plurality of mixing rollers (4) perpendicular to the axis of the mixing box (2) are arranged in the mixing box (2). The two ends of the mixing rollers (4) are respectively connected and fixed to the side wall of the mixing box (2) through bearings, and any end of each mixing roller (4) is respectively connected to the mixing motor (5). The mixing cover plate (3) is detachably arranged on the top of the mixing box (2). The mixing box (2) is obliquely arranged on the frame assembly (1), and the feeding mechanism (6) is arranged at the upper end of the mixing box (2).

6. The composite modified bentonite mixer according to claim 5, characterized in that: The lower surface of the mixing and grinding cover plate (3) is provided with a plurality of scrapers (7) inclined downward, and the angle β between the scrapers (7) and the mixing and grinding cover plate (3) is an acute angle.

7. The composite modified bentonite mixer according to claim 5, characterized in that: The scraper (7) is located above the mixing roller (4), the number of the scraper (7) corresponds to the number of the mixing roller (4), and the gap distance between the two is 1 to 3 cm.

8. The composite modified bentonite mixer according to claim 5, characterized in that: The gap distance between the mixing roller (4) and the inner bottom plate of the mixing box (2) is 0.5 to 5 cm.

9. The composite modified bentonite mixer according to claim 5, characterized in that: The mixing box (2) has an inclination angle of 15° to 20° with respect to the horizontal plane.

10. The composite modified bentonite mixer according to claim 5, characterized in that: The feeding mechanism (6) is a screw feeder, the bottom of which is connected to the upper end of the mixing box (2).

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