Preparation method and application of pellet adhesive

Abstract

The invention discloses a preparation method and application of a pellet adhesive, and belongs to the technical field of solid waste resource utilization. Industrial solid waste is dried and ground and then is uniformly mixed with an organic additive to prepare an adhesive, the adhesive is mixed and stirred with dried carbonaceous powder during application, and a pellet finished product is obtained through compaction treatment; the solid waste is converted into the pellet adhesive with proper viscosity and water absorption through the simple preparation method, resource utilization is achieved, a new thought is provided for solid waste resource utilization, the adhesive prepared through the method has better adhesive performance and high pelletizing rate and pellet compressive strength, and the service life of the pellet adhesive is prolonged. The industrial production cost can be greatly reduced, clean production is achieved, energy conservation and emission reduction are achieved, and remarkable economic benefits and social benefits are achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of solid waste resource utilization, and specifically relates to a preparation method and application of a pellet binder. Background Art

[0002] Pelletizing is one of the important methods of powder ore agglomeration. It is to mix the ore powder and the binder with appropriate amount of water and put them in the pelletizing equipment to form spherical agglomerates of a certain size through friction and collision between the rolling mineral particles. After the pellets are dried, they are preheated and roasted. After the solid phase reaction inside the pellets, they can reach the blast furnace charge with the quality that meets the production process requirements. The industrial production of pellets has become an indispensable and important part of the world's steel industry today.

[0003] Most of the adhesives used in pellet production are bentonite, but a high proportion of bentonite will affect the grade of pellet ore, resulting in increased blast furnace coke ratio, increased carbon emissions, and increased smelting costs. The increase in coke ratio will significantly increase the production cost per ton of iron. At the same time, as the reserves of high-quality bentonite resources are decreasing, it is necessary to continuously find new adhesive materials to solve the adverse effects of bentonite quality deterioration on pellet performance.

[0004] At present, the comprehensive utilization level of industrial solid waste is low, and long-term storage can easily cause direct environmental pollution and lead to major environmental problems. Therefore, it is urgent to improve the resource utilization of industrial solid waste.

[0005] A large amount of solid waste such as lime powder, coke powder and carbon drying ash is generated in the process of calcium carbide production. These solid wastes not only cause environmental pollution, but also directly increase the production cost of products. Taking the production index data of a 100,000 tons / year calcium carbide device as an example, every ton of calcium carbide produced produces 0.08 tons of coke powder and 0.03 tons of drying dust ash. Every year, 8,000 tons of coke powder and 3,000 tons of carbon drying ash cannot enter the calcium carbide production system for effective utilization. Industrial solid wastes such as red mud, fly ash, and blast furnace slag also contain a large amount of substances such as silicon dioxide and aluminum oxide, and have large particle size and large specific surface area, and have good adhesion, so they can be used as alternative materials. From the perspective of industrial practice, finding low-cost and economically efficient adhesive materials is an important measure to reduce industrial production costs. Summary of the invention

[0006] The present invention provides a preparation method and application of a pelletizing adhesive. Industrial solid waste is dried and ground and then evenly mixed with an organic additive in a certain proportion to obtain an adhesive for use. The present invention converts solid waste into a material with suitable viscosity and water absorption through a simple method, thereby realizing resource utilization and providing a new idea for solid waste resource utilization.

[0007] The specific technical solutions of the present invention are as follows:

[0008] A method for preparing a pellet binder, the specific steps are as follows:

[0009] (1) drying the industrial solid waste at 100-120° C. to constant weight, grinding it and passing it through a 200-mesh sieve to obtain a powder for later use;

[0010] (2) Mixing the powder of step (1) with additives in a certain proportion to obtain an adhesive.

[0011] In step (1), the industrial solid waste is any one or more of red mud, fly ash, blast furnace slag, etc.

[0012] The additive in step (2) is any one or more of starch, sodium carboxymethyl cellulose, guar gum, etc.

[0013] In step (2), the mass ratio of powder to additive is 1.0-3.0:0.5-1.0.

[0014] The present invention also provides the application of the pelletizing binder prepared by the above preparation method, which is mainly used as a pelletizing binder in pelletizing carbonaceous powder produced in the process of calcium carbide production.

[0015] The carbonaceous powder is pretreated before pelletizing, and the pretreatment process includes drying at 100-115° C. to constant weight, grinding and passing through a 60-mesh sieve.

[0016] The amount of the binder added during the carbonaceous powder pelletizing process is 2.0-4.0% of the mass of the carbonaceous powder.

[0017] Water is also added during the ball making process, and the amount of water added is 5.0-9.0% of the mass of the carbonaceous powder.

[0018] The pressure during the ball making process is 10-50MPa; after the ball making, the ball is dried at a temperature of 150-300°C for 0.5h.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] The present invention utilizes solid waste containing silicon, aluminum and other substances as raw materials to prepare adhesives, thereby realizing resource processing of solid wastes; at the same time, substances such as SiO2 and Al2O3 contained in the solid wastes have excellent surface adsorption and water absorption properties, forming a balanced combination of the two, which can maintain the strength of liquid bridges between pellet particles; in addition, the use of organic additives rich in hydroxyl and carboxyl groups provides good support for the pellets.

[0021] The pellet forming rate of the pelletizing adhesive prepared by the invention is above 90%, the cold strength of the pellets after drying is greater than 150N, and the hot strength in the furnace reaches 1650°C without bursting, the price is low, and the economic benefit is high. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is the flow chart of binder preparation and pellet production;

[0023] Figure 2 The XRD diagram of the binder, carbonaceous powder and pelletized product in Example 3;

[0024] Figure 3 The compressive strength diagram of Examples 1-5 and Comparative Examples 1-3;

[0025] Figure 4 The graphs are drop strength and burst temperature of Examples 1-5 and Comparative Examples 1-3. DETAILED DESCRIPTION

[0026] In order to better illustrate the purpose, technical solutions and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.

[0027] Example 1

[0028] A pellet binder and a pellet preparation method, according to Figure 1 The process shown in the figure has the following specific steps:

[0029] (1) Dry the red mud in an electric constant temperature air drying oven at 100° C. for 24 h to constant weight, grind it with an agate mortar, and pass it through a 200-mesh sieve to obtain red mud powder for later use;

[0030] (2) mixing red mud powder and starch in a mass ratio of 1.0:1.0 to obtain an adhesive for later use;

[0031] (3) placing the carbonaceous powder formed in the production process of calcium carbide in a hot constant temperature air drying oven at 100° C. and drying for 24 h to constant weight, grinding it with an agate mortar and passing it through a 60-mesh sieve, adding 2.0% of the mass of the carbonaceous powder The binder prepared in step (2) is added, and then adding 9.0% of the mass of the carbonaceous powder Water is added and fully stirred;

[0032] (4) The mixed material after stirring in step (3) is placed in a pelletizing machine, compacted and pelletized by cold pressing technology at 10 MPa, and then placed in an electric constant temperature blast drying oven and dried at 150° C. for 0.5 h to obtain pellets.

[0033] Example 2

[0034] A pellet binder and a pellet preparation method, the specific steps are as follows:

[0035] (1) Dry the red mud in an electric constant temperature air drying oven at 105° C. for 24 h to constant weight, grind it with an agate mortar, and pass it through a 200-mesh sieve to obtain red mud powder for later use;

[0036] (2) mixing red mud powder and starch in a mass ratio of 1.5:0.9 to obtain an adhesive for later use;

[0037] (3) placing the carbonaceous powder formed in the production process of calcium carbide in a hot constant temperature forced air drying oven at 105° C. and drying for 24 h to constant weight, grinding it with an agate mortar and passing it through a 60-mesh sieve, adding 2.5% of the mass of the carbonaceous powder, and the binder prepared in step (2), and then adding 8.0% of the mass of the carbonaceous powder, and stirring them thoroughly;

[0038] (4) The mixed material after stirring in step (3) is placed in a pelletizing machine, compacted and pelletized by cold pressing technology at 20 MPa, and then placed in an electric constant temperature blast drying oven and dried at 175° C. for 0.5 h to obtain pellets.

[0039] Example 3

[0040] A pellet binder and a pellet preparation method, the specific steps are as follows:

[0041] (1) Dry the red mud in an electric constant temperature air drying oven at 110° C. for 24 h to constant weight, grind it with an agate mortar, and pass it through a 200-mesh sieve to obtain red mud powder for later use;

[0042] (2) mixing red mud powder and starch in a mass ratio of 2.0:0.8 to obtain an adhesive for later use;

[0043] (3) placing the carbonaceous powder formed in the production process of calcium carbide in a hot constant temperature forced air drying oven at 110° C. and drying for 24 h to constant weight, grinding it with an agate mortar and passing it through a 60-mesh sieve, adding 3.0% of the mass of the carbonaceous powder The binder prepared in step (2) is added, and then adding 7.0% of the mass of the carbonaceous powder Water is added and fully stirred;

[0044] (4) The mixed material after stirring in step (3) is placed in a pelletizing machine, compacted and pelletized at 30 MPa by cold pressing technology, and then placed in an electric constant temperature blast drying oven and dried at 250° C. for 0.5 h to obtain pellets.

[0045] The binder, carbon powder and pellets were XRD( Figure 2 ) and XRF (Table 1) analysis shows that the binder is mainly composed of SiO2 and Al2O3, which swell when exposed to water during the preparation of pellets and have strong adsorption capacity, which can improve the pelletizing performance and increase the capillary force between the pellet particles.

[0046] Table 1

[0047]

[0048] Example 4

[0049] A pellet binder and a pellet preparation method, the specific steps are as follows:

[0050] (1) Dry the red mud in an electric constant temperature air drying oven at 115° C. for 24 h to constant weight, grind it with an agate mortar, and pass it through a 200-mesh sieve to obtain red mud powder for later use;

[0051] (2) mixing red mud powder and starch in a mass ratio of 2.5:0.7 to obtain an adhesive for later use;

[0052] (3) placing the carbonaceous powder formed in the production process of calcium carbide in a hot constant temperature forced air drying oven at 110° C. and drying for 24 h to constant weight, grinding it with an agate mortar and passing it through a 60-mesh sieve, adding 3.5% of the mass of the carbonaceous powder The binder prepared in step (2) is added, and then adding 6.0% of the mass of the carbonaceous powder Water is added and fully stirred;

[0053] (4) The mixed material after stirring in step (3) is placed in a pelletizing machine, compacted and pelletized by cold pressing technology at 40 MPa, and then placed in an electric constant temperature blast drying oven and dried at 225° C. for 0.5 h to obtain pellets.

[0054] Example 5

[0055] A pellet binder and a pellet preparation method, the specific steps are as follows:

[0056] (1) Dry the red mud in an electric constant temperature air drying oven at 120° C. for 24 h to constant weight, grind it with an agate mortar, and pass it through a 200-mesh sieve to obtain red mud powder for later use;

[0057] (2) mixing red mud powder and starch in a mass ratio of 3.0:0.5 to obtain an adhesive for later use;

[0058] (3) placing the carbonaceous powder formed in the production process of calcium carbide in a hot constant temperature air drying oven at 115° C. and drying for 24 h to constant weight, grinding it with an agate mortar and passing it through a 60-mesh sieve, adding 4.0% of the mass of the carbonaceous powder The binder prepared in step (2) is added, and then adding 5.0% of the mass of the carbonaceous powder Water is added and fully stirred;

[0059] (4) The mixed material after stirring in step (3) is placed in a pelletizing machine, compacted and pelletized at 50 MPa by cold pressing technology, and then placed in an electric constant temperature blast drying oven and dried at 200° C. for 0.5 h to obtain pellets.

[0060] Comparative Example 1

[0061] The difference between this comparative example and Example 3 is that only industrial solid waste red mud is used as a binder, and the following steps are included:

[0062] (1) Dry the red mud in an electric constant temperature air drying oven at 110° C. for 24 h to constant weight, grind it with an agate mortar, and pass it through a 200-mesh sieve to obtain red mud powder for later use;

[0063] (2) The carbonaceous powder formed in the production process of calcium carbide is placed in a hot constant temperature air drying oven at 110° C. and dried for 24 hours to constant weight, ground with an agate mortar and passed through a 60-mesh sieve, red mud powder accounting for 3.0% of the mass of the carbonaceous powder is added, and water accounting for 7.0% of the mass of the carbonaceous powder is added and stirred thoroughly;

[0064] (3) The mixed material after stirring in step (2) is placed in a pelletizing machine, compacted and pelletized at 30 MPa by cold pressing technology, and then placed in an electric constant temperature blast drying oven and dried at 250° C. for 0.5 h to obtain pellets.

[0065] Comparative Example 2

[0066] The difference between this comparative example and Example 3 is that only starch is used as a binder, and the following steps are included:

[0067] (1) The carbonaceous powder formed in the production process of calcium carbide is placed in a hot constant temperature air drying oven at 110° C. and dried for 24 hours to constant weight, ground with an agate mortar and passed through a 60-mesh sieve, and 3.0% starch by weight of the carbonaceous powder is added, and then 7.0% water by weight of the carbonaceous powder is added and stirred thoroughly;

[0068] (2) The mixed material after stirring in step (2) is placed in a pelletizing machine, compacted and pelletized at 30 MPa by cold pressing technology, and then placed in an electric constant temperature blast drying oven and dried at 250° C. for 0.5 h to obtain pellets.

[0069] Comparative Example 3

[0070] The difference between this comparative example and Example 3 is that only bentonite is used as a binder, and the following steps are included:

[0071] (1) The carbonaceous powder formed in the production process of calcium carbide is placed in a hot constant temperature air drying oven at 110° C. and dried for 24 hours to constant weight, ground with an agate mortar and passed through a 60-mesh sieve, and 3.0% of bentonite by weight of the carbonaceous powder is added, and then 7.0% of water by weight of the carbonaceous powder is added and stirred thoroughly;

[0072] (2) The mixed material after stirring in step (1) is placed in a pelletizing machine, compacted and pelletized at 30 MPa by cold pressing technology, and then placed in an electric constant temperature blast drying oven and dried at 250° C. for 0.5 h to obtain pellets.

[0073] The pellets prepared in Examples 1-5 and Comparative Examples 1-3 were tested based on relative performance indicators:

[0074] Ten qualified pellets were selected and placed on a specified compressive strength test machine at room temperature. The test machine applied pressure to the pellets at a uniform speed until the pellets broke. The maximum value of the pressure on the test machine was the compressive strength of the pellets (N / P). The data are shown in Table 2 and Figure 3 shown.

[0075] Table 2

[0076]

[0077] 50 pellets were drawn and put into the test cup, and placed in a vertical tube furnace with a wind speed of 1.5m / s for 5 minutes. The highest temperature that 4% of the green balls can withstand when they break was taken as the bursting temperature of the green balls. Finally, 10 qualified pellets were selected and the pellets were freely dropped from a height of 0.5 meters onto an iron plate. The drops were repeated until cracks appeared on the surface of the pellets. The total number of drops of each ball was recorded, and the number of drops was subtracted by one as the drop strength of a single pellet. The average value of the test results of 10 pellets was calculated as the drop strength of the green balls. The test data are shown in Table 3 and Figure 4 shown.

[0078] Table 3

[0079]

[0080] From Table 2 and Table 3 Figure 3 and Figure 4 It can be seen that there are many factors affecting the pellet processing, which will directly affect the molding due to the adjustment and fluctuation of some parameters. Among them, water plays a promoting role in the pellet, and the water film formed enhances the capillary force of the pellet. If the amount of water added is small, the raw material cannot be infiltrated, which further affects the hardness of the pellet. On the contrary, too high water content will cause the water to evaporate when the temperature rises and then fail to diffuse in time, resulting in excessive internal pressure of the pellet, and the burst temperature drops. When the water content is too high, the pelletizing disk will stick to the material, affecting the test. At the same time, the adhesive can increase the capillary force between the pellet particles, make the particles closer, and enhance the falling strength and compressive strength of the pellet. However, when the adhesive is added in too high a proportion, the pores between the particles are reduced. When the temperature is too high, the internal water cannot be quickly discharged from the pores after evaporation, and the internal pressure of the pellet increases, making it easy to break. In addition, the pelletizing pressure is also an important factor, which is directly related to the quality and strength of the pellet. Appropriate pressure can make the pellet less pore and enhance the adhesive effect, but too much pressure will squeeze out the water in the material to form a water film, and too small a pellet will not form and be easy to crush.

[0081] Compared with Example 3, the performance of the pellets prepared in Comparative Examples 1, 2 and 3 is significantly different. The reason is that although the inorganic binder alone can improve the density and strength of the pellets, some harmful elements will be present during use. In addition, the organic binder starch has poor thermal stability and has a smaller effect on the performance and burst temperature of the pellets. After adding the organic binder, the volatilization of organic matter will have a certain impact on the structure and strength of the pellets.

[0082] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A method for preparing a pellet binder, characterized in that: The specific steps are as follows: (1) drying the industrial solid waste at 100-120° C. to constant weight, grinding and passing through a 200-mesh sieve to obtain a powder; (2) Mixing the powder obtained in step (1) with an additive to obtain an adhesive.

2. The method for preparing the pellet binder according to claim 1, characterized in that: In step (1), the industrial solid waste is any one or more of red mud, fly ash and blast furnace slag.

3. The method for preparing the pellet binder according to claim 1, characterized in that: The additive in step (2) is any one or more of starch, sodium carboxymethyl cellulose and guar gum.

4. The method for preparing the pellet binder according to claim 1, characterized in that: In step (2), the mass ratio of powder to additive is 1.0-3.0:0.5-1.

0.

5. Application of the pelletizing binder prepared by the preparation method according to claim 1 in the pelletizing process of carbonaceous powder produced in the production process of calcium carbide.

6. The use according to claim 5, characterized in that: The carbonaceous powder is pretreated before pelletizing, and the pretreatment process includes drying at 100-115° C. to constant weight, grinding and passing through a 60-mesh sieve.

7. The use according to claim 5, characterized in that: The amount of the binder added during the carbonaceous powder pelletizing process is 2.0-4.0% of the mass of the carbonaceous powder.

8. The use according to claim 5, characterized in that: Water is also added during the pelletizing process, and the amount of water added is 5.0-9.0% of the mass of the carbonaceous powder.

9. The use according to claim 5, characterized in that: The pressure during the ball making process is 10-50MPa, and the balls are dried after being made. The drying temperature is 150-300°C and the time is 0.5h.

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