Method for preparing iron ore pellet additive from boric sludge and application of iron ore pellet additive

Abstract

The invention discloses a method for preparing an iron ore pellet additive from boric sludge and application of the iron ore pellet additive. The method for preparing the iron ore pellet additive from the boric sludge comprises the following steps: drying and finely grinding the boric sludge, uniformly mixing the finely ground boric sludge and an auxiliary agent according to the mass percent, mechanically activating, drying and grinding to obtain the iron ore pellet additive. In iron ore pellet production, the iron ore pellet additive can replace bentonite to make iron ore concentrate pelletized into pellets, and the pellet strength and quality meet the production requirements. According to the method for preparing the iron ore pellet additive from the boric sludge and the application of the iron ore pellet additive, the method for preparing the iron ore pellet additive from the boric sludge is short in process, easy to operate and low in cost, the prepared additive can replace a bentonite binder commonly used in pellet production, land damage and ecosystem unbalance caused by bentonite mining are avoided, and the service life of the additive is prolonged. And the boron mud can be recycled at low cost, and green value-added utilization of the boron mud solid waste is realized.

Description

Technical Field

[0001] The invention relates to the technical field of iron and steel metallurgy, and in particular to a method for preparing an iron ore pellet additive from boron mud and application thereof. Background Art

[0002] Binder is the key to prepare iron concentrate into qualified pellets. With the rapid development of the steel industry, the production and quality requirements of binders are getting higher and higher, and the role of binders in the production of steel raw materials is becoming more and more important. After a long period of development, pellet binders have gradually formed inorganic binders, organic binders and composite binders. Inorganic binders are mainly bentonite. According to production experience, for every 1wt% of bentonite added in the pelletizing process, the iron grade of the pellet will be reduced by about 0.6wt%, and the iron content will be reduced by about 7kg / t. Therefore, achieving partial or complete replacement of bentonite is an important development direction for metallurgical pellet binders. Studies have shown that some industrial solid wastes have similar physical and chemical properties to bentonite, and their SiO2 content may be much lower than that of bentonite, but they also contain a large amount of Fe2O3, Al2O3, MgO, B2O3 and other components that are beneficial to the quality of pellets. It can be seen that the application of industrial solid waste in pelletizing additives can partially or completely replace bentonite binders. Common modified industrial solid waste additives mainly include iron tailings, bauxite tailings, fly ash, red mud, boron mud, etc. The application of industrial solid waste in pellet binders can partially or completely replace bentonite binders, which can not only improve the quality of pellets, but also reduce costs, save energy, reduce pollution, and have significant economic benefits.

[0003] Boron mud is an industrial solid waste produced in the process of producing borax by the carbon-alkali method using boron-magnesium ore or boron-magnesium iron ore. Generally, 4 to 5 tons of boron mud will be produced for every ton of borax produced. Most of the boron mud is discharged and piled up without treatment, occupying a large amount of land resources. The waste of resources caused by the large accumulation of boron mud is a problem that needs to be solved urgently. Patent No. CN201310404554.3: A pellet binder is disclosed, in which boron mud and red mud are dried and ground, and then mixed with corn starch in proportion, and then the mixture is finely ground to obtain a pellet binder, but a higher red mud needs to be added to ensure the strength of the pellets. The addition of red mud leads to a higher Al2O3 content, and the fluidity of blast furnace slag is reduced, which is not conducive to blast furnace ironmaking. Application No. CN201510281250.1: discloses a boron mud pellet binder / ironmaking aid and a preparation method thereof, wherein boron mud, boron ore powder and light-burned magnesia are mixed, and then dispersible rubber powder, polyacrylamide and a wetting agent are mixed in a certain proportion to obtain a high-strength binder, and finally the boron mud mixture and the high-strength binder are mixed and ball-milled to obtain a boron mud pellet binder, but the addition of light-burned magnesia causes the MgO content to be too high, which affects the performance of the pellets, and the compressive strength of the pellets cannot meet the production requirements. Application No. CN201911028015.8: discloses a magnesium-containing flux pellet binder and a preparation method thereof, wherein slaked lime and corn starch are mixed vigorously in proportion and then ground, and then the finely ground boron mud is mixed vigorously with the slaked lime and corn starch mixture in proportion to obtain a magnesium-containing flux pellet binder, but the addition of a relatively high slaked lime causes the CaO content to be too high, resulting in a high reduction expansion rate of the pellets, which affects the stable operation of the blast furnace. Summary of the invention

[0004] The purpose of the present invention is to provide a method for preparing an iron ore pellet additive from boron mud with a short process, simple operation and low cost. The prepared iron ore pellet additive can replace the bentonite binder commonly used in pellet production, avoid land damage and ecosystem imbalance caused by bentonite mining, and realize the value-added utilization of boron mud, recycle boron mud at low cost, and solve the problems of large-scale accumulation of boron mud, high energy consumption and high cost of comprehensive utilization.

[0005] Another object of the present invention is to provide an application of the iron ore pellet additive prepared by the preparation method. In the production of iron ore pellets, the iron ore pellet additive can replace bentonite to granulate iron ore concentrate into balls, and the strength and quality of the pellets meet the production requirements.

[0006] The invention provides a method for preparing an iron ore pellet additive from boron mud. The preparation method comprises the following steps: first drying and fine grinding the boron mud, then mixing the finely ground boron mud with an additive in an appropriate mass percentage, and then mechanically activating the mixture, drying and grinding the mixture to obtain the iron ore pellet additive.

[0007] In a preferred embodiment of the method for preparing an iron ore pellet additive from boron mud provided by the present invention, the drying and fine grinding treatment is: drying the boron mud at 105°C for at least 3 hours to completely remove moisture from the boron mud, and then grinding the dried boron mud to a fine grinding particle size of -0.074mm and a particle size content of 90% to 95%.

[0008] In a preferred embodiment of the method for preparing an iron ore pellet additive from boron mud provided by the present invention, the auxiliary agent is one of carboxymethyl cellulose (CMC), pregelatinized starch, and polyacrylamide (PAM).

[0009] In a preferred embodiment of the method for preparing an iron ore pellet additive from boron mud provided by the present invention, the mass percentage of the boron mud is 94% to 99%, and the mass percentage of the auxiliary agent is 1% to 6%.

[0010] In a preferred embodiment of the method for preparing an iron ore pellet additive from boron mud provided by the present invention, the mechanical activation is as follows: the finely ground boron mud and the additive are mixed in appropriate mass percentages, then moistened with water, and then ball milled or stirred. The moistening water accounts for 5% to 12% of the mass percentage of the boron mud and the additive, and the mechanical activation time is 30 to 60 minutes.

[0011] In a preferred embodiment of the method for preparing an iron ore pellet additive from boron mud provided by the present invention, the drying and grinding is as follows: placing the mixture of the mechanically activated boron mud and the additive at 105°C and drying for at least 3 hours until the moisture is completely removed, and then grinding and grinding until the content of particles with a particle size of -0.074 mm is not less than 95%.

[0012] The present invention also provides an application of the iron ore pellet additive prepared by the preparation method. In the production of iron ore pellets, the iron ore pellet additive can replace bentonite to granulate iron ore concentrate into balls, and the strength and quality of the pellets meet the production requirements.

[0013] In a preferred embodiment of the application of the boron mud in preparing the iron ore pellet additive provided by the present invention, the amount of the iron ore pellet additive added to the iron ore concentrate is 1-6% of the mass of the iron ore concentrate.

[0014] The auxiliary agent selected by the present invention is one of carboxymethyl cellulose (CMC), pregelatinized starch and polyacrylamide (PAM). A small amount of auxiliary agent is added to the boron mud iron ore pellet additive in order to improve the metallurgical properties of the pellets. Carboxymethyl cellulose (CMC), pregelatinized starch, polyacrylamide (PAM) and other organic substances are used as auxiliary agent components. On the one hand, they have wide sources, low prices and obvious effects, and on the other hand, they have little effect on the pellet components.

[0015] The present invention develops and prepares a boron-containing iron ore pellet additive by compounding boron mud with auxiliary agents such as carboxymethyl cellulose (CMC), pregelatinized starch, polyacrylamide (PAM) in a certain ratio and subjecting them to treatments such as mechanical activation, thereby improving the pellet strength and recycling the boron mud at a low cost, solving the problems of large-scale accumulation of boron mud and high energy consumption and cost for comprehensive utilization, and realizing green value-added utilization of boron mud solid waste.

[0016] Compared with the prior art, the method for preparing an iron ore pellet additive from boron mud provided by the present invention has the following beneficial effects:

[0017] 1. The method for preparing an iron ore pellet additive from boron mud provided by the present invention has a short process, simple operation, and low cost, and the prepared additive can replace the bentonite binder commonly used in pellet production, thereby avoiding land damage and ecosystem imbalance caused by bentonite mining.

[0018] 2. In the pelletizing process of iron ore pelletizing technology, the iron ore pelletizing additive prepared by the present invention is added to the iron concentrate to improve the quality of green balls and the strength of finished pellets, wherein the falling strength of green balls can reach more than 5.0 times / 0.5m, the preheated ball strength can reach more than 600N / P, and the roasted ball strength can reach more than 2500N / P.

[0019] 3. In the iron ore pellet additive prepared by the present invention, the boron mud ratio is more than 90%, so the boron mud can be recycled at low cost, solving the problems of large-scale accumulation of boron mud and high comprehensive utilization cost, and realizing the green value-added utilization of boron mud solid waste. DETAILED DESCRIPTION

[0020] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0021] In the comparative examples and embodiments of the present invention, the preheating and calcining conditions are as follows: the preheating temperature is 1010° C., the preheating time is 10 min, the calcining temperature is 1250° C., and the calcining time is 10 min.

[0022] Comparative Example 1

[0023] Add 1.5wt% bentonite binder to the iron ore powder, mix well, sieve the material to less than 1mm, and use a disc ball making machine to make balls. The resulting green balls have a drop strength of 5.2 times / 0.5m, a compressive strength of 12.7N / P, and a burst temperature of 390℃; the compressive strength of the preheated balls is 499N / P, and the compressive strength of the roasted balls is 2509N / P.

[0024] Comparative Example 2

[0025] Add 2.0wt% of boron mud to the iron ore powder, mix well and use a disc ball making machine to make balls. The resulting green balls have a drop strength of 1.8 times / 0.5m, a compressive strength of 15.9N / P, and a burst temperature of 350℃; the compressive strength of the preheated balls is 446N / P, and the compressive strength of the roasted balls is 2153N / P.

[0026] Comparative Example 3

[0027] Add 4wt% of boron mud to the iron ore powder, mix well and use a disc ball making machine to make balls. The resulting green balls have a drop strength of 2.4 times / 0.5m, a compressive strength of 12.5N / P and a burst temperature of 350℃; the compressive strength of the preheated balls is 469N / P, and the compressive strength of the roasted balls is 2265N / P.

[0028] Comparative Example 4

[0029] Add 6wt% of boron mud to the iron ore powder, mix well and use a disc ball making machine to make balls. The resulting green balls have a drop strength of 2.6 times / 0.5m, a compressive strength of 11.2N / P and a burst temperature of 360℃; the compressive strength of the preheated balls is 484N / P, and the compressive strength of the roasted balls is 2386N / P.

[0030] Example 1

[0031] First, the boron mud is dried at 105°C for at least 3 hours to completely remove the moisture from the boron mud, and then the dried boron mud is ground to a fine particle size of -0.074mm and a content of 90% to 95%. Then, 2wt% of the boron mud by weight of the iron ore concentrate powder is mixed with 0.1wt% of carboxymethyl cellulose (CMC), and 8wt% of water by weight of the boron mud and the carboxymethyl cellulose is added for wetting. Finally, after mechanical activation for 35 minutes, the boron mud is dried and ground to a particle content of -0.074mm of not less than 95%, thereby obtaining an iron ore pellet additive. The iron ore pellet additive is then added to the iron ore concentrate powder and fully mixed, and a disc pelletizer is used for pelletizing. The obtained green balls have a drop strength of 4.2 times / 0.5m, a compressive strength of 10.9N / P, and a burst temperature greater than 550°C; the compressive strength of the preheated balls is 626N / P, and the compressive strength of the roasted balls is 2507N / P.

[0032] Example 2

[0033] First, the boron mud is dried at 105°C for at least 3 hours to completely remove the moisture from the boron mud, and then the dried boron mud is ground to a fine particle size of -0.074mm and a particle size content of 90% to 95%. Then, 4wt% of the boron mud by weight of the iron ore concentrate powder is mixed with 0.1wt% of carboxymethyl cellulose (CMC), and 8wt% of water by weight of the boron mud and the carboxymethyl cellulose is added for wetting. Finally, after mechanical activation for 50 minutes, the boron mud is dried and ground to a particle content of -0.074mm of not less than 95%, thereby obtaining an iron ore pellet additive. The iron ore pellet additive is then added to the iron ore concentrate powder and fully mixed, and a disc pelletizer is used for pelletizing. The obtained green balls have a drop strength of 6.3 times / 0.5m, a compressive strength of 11.2N / P, and a burst temperature greater than 550°C; the compressive strength of the preheated balls is 978N / P; and the compressive strength of the roasted balls is 2595N / P.

[0034] Example 3

[0035] First, the boron mud is dried at 105°C for at least 3 hours to completely remove the moisture from the boron mud, and then the dried boron mud is ground to a fine particle size of -0.074mm and a particle size content of 90% to 95%, and then the boron mud accounting for 4wt% of the mass of the iron ore concentrate powder is mixed with 0.1wt% of pregelatinized starch, and water accounting for 8wt% of the mass of the boron mud and the pregelatinized starch is added for wetting, and finally mechanical activation is performed for 50 minutes and then dried and ground to a particle content of -0.074mm particles not less than 95%, thereby obtaining an iron ore pellet additive, and then the iron ore pellet additive is added to the iron ore concentrate powder and fully mixed, and a disc pelletizer is used for pelletizing, and the obtained green balls have a drop strength of 5.5 times / 0.5m, a compressive strength of 11.1N / P, and a burst temperature of 450°C; the compressive strength of the preheated balls is 994N / P; and the compressive strength of the roasted balls is 3555N / P.

[0036] Example 4

[0037] First, the boron mud is dried at 105°C for at least 3 hours to completely remove the moisture from the boron mud, and then the dried boron mud is ground to a fine particle size of -0.074mm and a particle size content of 90% to 95%. Then, 4wt% of the boron mud by weight of the iron ore powder is mixed with 0.1wt% polyacrylamide (PAM), and 8wt% of water by weight of the boron mud and the polyacrylamide is added for wetting. Finally, after mechanical activation for 50 minutes, the mixture is dried and ground to a particle content of -0.074mm of not less than 95%, thereby obtaining an iron ore pellet additive. The iron ore pellet additive is then added to the iron ore concentrate and fully mixed, and a disc pelletizer is used for pelletizing. The obtained green balls have a drop strength of 4.8 times / 0.5m and a compressive strength of 10.9N / P; the burst temperature is 390°C; the compressive strength of the preheated balls is 755N / P; and the compressive strength of the roasted balls is 2508N / P.

[0038] Example 5

[0039] First, the boron mud is dried at 105°C for at least 3 hours to completely remove the moisture from the boron mud, and then the dried boron mud is ground to a fine particle size of -0.074mm and a content of 90% to 95%. Then, 6wt% of the boron mud by weight of the iron ore powder is mixed with 0.1wt% of carboxymethyl cellulose (CMC), and 8wt% of water by weight of the boron mud and the carboxymethyl cellulose is added for wetting. Finally, after mechanical activation for 60 minutes, the boron mud is dried and ground to a particle content of -0.074mm of not less than 95%, thereby obtaining an iron ore pellet additive. The iron ore pellet additive is then added to the iron concentrate and fully mixed, and a disc pelletizer is used for pelletizing. The obtained green balls have a drop strength of 6.5 times / 0.5m and a compressive strength of 11.7N / P; the burst temperature is 550°C; the compressive strength of the preheated balls is 989N / P; and the compressive strength of the roasted balls is 2831N / P.

[0040] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A method for preparing an iron ore pellet additive from boron mud, characterized in that: The boron mud is first dried and finely ground, and then the finely ground boron mud is mixed with an additive in an appropriate mass percentage, and then mechanically activated, dried and ground to obtain an iron ore pellet additive.

2. The method for preparing an iron ore pellet additive from boron mud according to claim 1, characterized in that: The drying and fine grinding treatment comprises: drying the boron mud at 105° C. for at least 3 hours until the water content of the boron mud is completely removed, and then grinding the dried boron mud to obtain a fine grinding particle size of -0.074 mm and a particle content of 90% to 95%.

3. The method for preparing an iron ore pellet additive from boron mud according to claim 1, characterized in that: The auxiliary agent is one of carboxymethyl cellulose (CMC), pregelatinized starch and polyacrylamide (PAM).

4. The method for preparing an iron ore pellet additive from boron mud according to claim 1, characterized in that: The mass percentage of the boron mud is 94% to 99%, and the mass percentage of the auxiliary agent is 1% to 6%.

5. The method for preparing an iron ore pellet additive from boron mud according to claim 1, characterized in that: The mechanical activation comprises: mixing the finely ground boron mud and the auxiliary agent in appropriate mass percentage, adding water to wet the mixture, and then ball milling or stirring the mixture, wherein the wet water accounts for 5% to 12% of the mass percentage of the boron mud and the auxiliary agent, and the mechanical activation time is 30 to 60 minutes.

6. The method for preparing an iron ore pellet additive from boron mud according to claim 1, characterized in that: The drying and grinding is as follows: placing the mixture of mechanically activated boron mud and additives at 105° C. and drying for at least 3 hours until the moisture is completely removed, and then grinding and grinding until the content of particles with a particle size of -0.074 mm is not less than 95%.

7. An application of an iron ore pellet additive prepared by the preparation method according to any one of claims 1 to 6, characterized in that: In the production of iron ore pellets, the iron ore pelletizing additive can replace bentonite to granulate iron ore concentrate into balls, and the strength and quality of the pellets meet the production requirements.

8. The use according to claim 7, characterized in that: The amount of the iron ore pellet additive added to the iron ore concentrate is 1-6% of the mass of the iron ore concentrate.