Biomass-based binder as well as preparation method and application thereof

Abstract

The invention provides a biomass-based binder as well as a preparation method and application thereof. The provided biomass-based binder comprises activated agricultural and sideline products and puffed corn starch, and the mass ratio of the activated agricultural and sideline products to the puffed corn starch is (1: 10)-(10: 10); the activated agricultural and sideline products are obtained by activating agricultural product primary processing byproducts through an alkaline solution. The biomass-based binder provided by the invention can be used for cold-pressed pellet molding of the iron and steel dust, and is low in cost and green and environment-friendly.

Description

Technical Field

[0001] The present invention relates to the field of steel, and in particular to a biomass-based binder and a preparation method and application thereof, and in particular to the use of the biomass-based binder in the field of steel dust and mud. Background Art

[0002] Steel is the most important basic structural material. my country is a major steel producer, accounting for nearly 50% of the world's total output. Correspondingly, about 80 million tons of solid waste dust are generated each year. Our company has established a solid working foundation in the long-term cooperative development of solid waste resource recycling technology. Our cooperative unit, Nankai University, has many years of research and development foundation in the field of solid waste recycling. It has undertaken a number of research projects such as the National 863 Project, the Ministry of Science and Technology's key projects, and Tianjin Science and Technology Support Projects. Relying on the Tianjin Collaborative Innovation Center for Chemistry and Chemical Engineering and the National Institute of New Materials, it has all the necessary experimental equipment and testing instruments in the process of this technology research and development, providing hardware and software guarantees for the achievement and smooth implementation of technological achievements.

[0003] Steel dust is an important component of solid waste in the steel industry, mainly derived from dust removal and wastewater treatment processes in various processes such as sintering, pelletizing, blast furnace, converter and rolling. It contains valuable elements such as iron, carbon, zinc, potassium, sodium, etc., but the chemical composition of different dusts varies greatly. For example, the total iron mass fraction of sintering machine head ash fluctuates greatly, generally about 20%, which belongs to low-iron iron-containing dust; while blast furnace bag ash and blast furnace gas mud belong to medium-iron iron-containing dust. The diversity and instability of this composition make it difficult to unify standards during preparation and utilization, increasing the difficulty of process control. The dust removal ash of steel enterprises refers to the dust collected by dust removal equipment in various processes from sintering to steel rolling. The particle size of dust removal ash is generally fine, such as the average particle size of sintering machine head ash is about 100μm, the average particle size of blast furnace bag ash is about 130μm, and the average particle size of converter ash is about 120μm. This fine particle size makes the dust ash lighter and easier to fly, which makes it very difficult to handle and utilize. In addition, the adsorption of steel dust and adhesives is poor and difficult to form. Traditional adhesives such as bentonite and water glass, although they have a certain bonding effect, often increase the harmful elements in the dust ash and deteriorate the metallurgical properties of the pellets. Organic adhesives such as starch and cellulose, although beneficial to the grade of iron, are expensive, have poor temperature resistance, and are easy to explode in blast furnaces, affecting smelting efficiency (Zheng Xihan, Chen Tiejun, Wan Junying, et al. Analysis of the causes of carbon-containing pellet pulverization in the production of zinc-containing dust in rotary hearth furnaces in China [J]. Journal of Iron and Steel Research, 2024, 36(05): 560-567.). Therefore, it is particularly important to develop an adhesive that can not only combine well with steel dust but also maintain its metallurgical properties.

[0004] In response to the above problems, domestic and foreign scholars and enterprises have conducted a lot of research. For example, Mao Rui (Mao Rui, Wang Fei, Jin Hai, et al. Key technology for treating iron-containing dust and mud in rotary hearth furnace process [J]. Steel, 2020, 55(08): 199-205.) et al. proposed a composite binder composed of bentonite and organic binder, which showed good bonding performance, but had certain requirements for equipment. Summary of the invention

[0005] The present invention aims to solve at least one of the technical problems in the related art to a certain extent. The steel dust sludge has the defects of large fluctuation range of composition, fine dust ash particle size, light texture, poor adsorption with adhesive, difficult molding, and high cost of the original technology. In the existing process, the binder is the key factor in the molding of steel dust sludge. The use of inorganic binders will reduce the grade of raw materials and increase the ash content of the product. Although organic binders can avoid this problem, they are expensive and have low thermal stability. The pelletization rate of metallized pellet products decreases. Moreover, if the amount of binder is too large, the hydrogen content in the flue gas will increase after the recycled charge enters the furnace, making the blast furnace electrostatic precipitator system prone to explosion. If the amount of binder is too small, it is easy to cause the powder rate of the charge to increase, which is easy to cause smoke after entering the furnace.

[0006] A large amount of waste from the primary processing of agricultural products is prone to breed a large amount of aflatoxin when piled up for a long time, polluting the environment and seriously endangering public health. At the same time, the waste from the primary processing of agricultural products contains a large amount of lignin, cellulose, pectin and other components, which is an ideal potential raw material for preparing adhesives. However, the commercially available puffed waste residues of primary processing of agricultural products have insufficient hydrolysis of lignin and cellulose and insufficient viscosity. The present invention further activates the residue to enhance its viscosity, mixes it with puffed corn starch, greatly reduces the cost of existing adhesives, improves the molding performance, and also provides a new way for the green and environmentally friendly recycling of agricultural and forestry wastes.

[0007] Specifically, the present invention provides the following technical solutions:

[0008] A first aspect of the present invention provides a biomass-based binder, comprising: activated agricultural byproducts and puffed corn starch;

[0009] The mass ratio of the activated agricultural and sideline products to the puffed corn starch is 1:10 to 10:10;

[0010] The activated agricultural and sideline products are obtained by activating by-products of primary processing of agricultural products through alkaline solution.

[0011] The second aspect of the present invention provides a method for preparing the biomass-based binder according to the first aspect, comprising:

[0012] (1) Activating byproducts of primary processing of agricultural products by means of an alkaline solution to obtain activated agricultural and sideline products;

[0013] (2) The activated agricultural and sideline products and puffed corn starch are mixed in a predetermined mass ratio to obtain the biomass-based binder, wherein the predetermined mass ratio is 1:10 to 10:10.

[0014] According to an embodiment of the present invention, step (1) comprises:

[0015] The byproducts of primary processing of agricultural products are mixed with a sodium hydroxide solution with a concentration of 0.5-2 wt%, and activated at 40-80 DEG C for 0.5-4 hours to obtain activated agricultural and sideline products.

[0016] The third aspect of the present invention provides an organic binder, comprising the biomatrix binder of the first aspect and a polymer material, wherein the polymer material accounts for 0.5 to 3% of the mass of the biomatrix binder;

[0017] Optionally, the polymer material is selected from at least one of polyacrylonitrile and polyacrylonitrile.

[0018] The fourth aspect of the present invention provides an organic-inorganic composite binder, comprising: the biomatrix binder described in the first aspect, a polymer material and an inorganic binder;

[0019] The polymer material accounts for 0.5 to 3% of the mass of the biomatrix binder;

[0020] The inorganic binder accounts for 0.5 to 5% of the mass of the biomass-based binder;

[0021] Optionally, the inorganic binder is selected from at least one of polyaluminum powder and bentonite.

[0022] A fifth aspect of the present invention provides a method for cold pressing steel dust into agglomerates, comprising:

[0023] Mixing steel dust, the biomass-based binder described in the first aspect, the organic binder described in the third aspect, or the organic-inorganic composite binder described in the fourth aspect, and water in a predetermined mass ratio to form a mixture;

[0024] cold pressing the mixture into agglomerates under a predetermined pressure to obtain wet pellets;

[0025] The wet pellets may be optionally dried to obtain dry pellets.

[0026] According to an embodiment of the present invention, the drying is performed at 120 to 180 degrees Celsius for 2 to 4 hours.

[0027] According to an embodiment of the present invention, the predetermined mass ratio is (90-99):(1-10):(5-15).

[0028] According to an embodiment of the present invention, the predetermined pressure is 10-50 MPa. According to a preferred embodiment, the predetermined pressure is 2-30 MPa.

[0029] According to an embodiment of the present invention, the steel dust sludge includes at least one of steelmaking sludge, steelmaking LT ash or bag ash.

[0030] According to an embodiment of the present invention, the strength of the wet pellets prepared from steelmaking sludge is 196N-305N, and the strength of the dry pellets is 980N-1500N.

[0031] According to an embodiment of the present invention, the strength of the wet pellets prepared by steelmaking LT ash is 98N-170N, and the strength of the dry pellets is 340N-490N.

[0032] According to an embodiment of the present invention, the strength of the wet pellets prepared by bag ash is 98N-175N, and the strength of the dry pellets is 1980N-1500N. The unit of strength mentioned here is Newton (N).

[0033] The sixth aspect of the present invention discloses the use of the biomass-based binder described in the first aspect, the organic binder described in the third aspect, or the organic-inorganic composite binder described in the fourth aspect in steel dust.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] Steel dust sludge is the largest amount of waste generated during the steelmaking process in steel mills. The cold-pressed pelletizing technology can produce furnace charges with suitable block size and good air permeability, which can be directly recycled and applied to large and medium-sized converters to ensure the normal operation of the equipment. The cold-pressed pelletizing process technology and equipment are simple, low-cost, and have a wide range of applications, but the performance requirements of the binder are extremely high. The cold and hot strengths of most current binders, especially the hot strength, make it difficult to achieve effective molding and resource utilization of steel dust sludge. The present invention proposes a new biomass-based binder that can be applied to the current cold-pressed pelletizing process without the need to develop molding equipment separately; secondly, in terms of binders, the efficient and low-cost biomass-based binder suitable for steel dust sludge proposed by the present invention is derived from waste by-products of primary processing of agricultural products, and has the advantages of low cost and green environmental protection. DETAILED DESCRIPTION

[0036] Embodiments of the present invention are described in detail below. The embodiments are exemplary and intended to be used to explain the present invention, but should not be construed as limiting the present invention.

[0037] In view of the characteristics of steel dust sludge, such as large fluctuation range of composition, fine dust ash particle size, light texture, poor adsorption with adhesives and difficulty in molding, this application has developed a new biomass-based binder, which is suitable for the cold-pressed pellet molding process of steel dust sludge. The pellets have high hot and cold strength, simple molding process and wide range of applicability.

[0038] In view of the large fluctuation range of steel dust composition, fine dust particle size, light texture, poor adsorption with adhesives, and difficult molding, a cold-pressed pellet molding process based on biomass binder is developed, and a high-efficiency, low-cost biomass-based binder suitable for steel dust is developed. Under appropriate raw material ratios and optimized process parameters, the balling rate of raw balls is ≥80%, the wet ball drop strength is ≥4 times / 1m, the dry ball drop strength is ≥5 times / 1m, and the dry ball strength can reach 1500N / piece. The manufacturing cost of the new binder is 5% lower than that of the existing binders on site.

[0039] The present invention provides a high-efficiency and low-cost biomass-based binder suitable for a general steel dust sludge forming process. The biomass-based binder comprises activated agricultural and sideline products and puffed corn starch, wherein the activated agricultural and sideline products are obtained by activating agricultural product primary processing byproducts through an alkaline solution, and the mass ratio of the activated agricultural and sideline products to the puffed corn starch is (1-10):10.

[0040] The biomass-based binder mentioned above can be used for the molding of steel dust sludge, which can weaken the composition characteristics of steel dust sludge and the defects of its interface interaction with the binder, and has low cost, high viscosity and high adhesion.

[0041] In this article, the biomass-based adhesive mentioned is a material formed by chemical reaction or physical action using biomass as raw material, and has certain bonding properties and strength.

[0042] The biomass-based binder is prepared by the following method: (1) activating byproducts of primary processing of agricultural products by means of an alkaline solution to obtain activated agricultural byproducts;

[0043] (2) The activated agricultural and sideline products and puffed corn starch are mixed in a predetermined mass ratio to obtain the biomass-based binder, wherein the predetermined mass ratio is 1:10 to 10:10.

[0044] After the activation treatment, lignin and cellulose can be further hydrolyzed, and the viscosity of the activated agricultural and sideline products can be increased. When the agricultural and sideline products are activated, the agricultural and sideline products can be mixed with a sodium hydroxide solution with a concentration of 0.5-2wt%, and activated at 40-80°C for 0.5-4 hours to obtain activated agricultural and sideline products.

[0045] The by-products of primary processing of agricultural products mentioned above can be purchased commercially, for example, they can be some commercially available waste residues of by-products of primary processing of puffed agricultural products. They can also be prepared by themselves. For example, they include: 1. Collection and classification: First, collect the by-product waste residues generated during the primary processing of agricultural products, such as bean dregs, corn cob residues, rice husks, etc. These wastes usually contain certain nutrients and usable values. 2. Cleaning and drying: Clean the collected waste residues to remove impurities and pollutants. After cleaning, dry the raw materials to reduce the water content of the raw materials for subsequent puffing. The degree of drying needs to be determined according to the requirements of the specific raw materials and puffing equipment. 3. Crushing and mixing: Crush the dried waste residues to a particle size suitable for puffing.

[0046] Before the activated agricultural and sideline products are mixed with the puffed corn starch, the activated agricultural and sideline products can be fully dried and ground. After the activated agricultural and sideline products are mixed with the puffed corn starch, they can be fully stirred and mixed evenly.

[0047] On this basis, polymer materials are continuously added and mixed thoroughly to obtain an organic binder. The mass proportion of the polymer materials mentioned is 0.5-3% of the mass of the biomass-based binder. According to a specific embodiment, the polymer materials mentioned include but are not limited to polyacrylonitrile and polypropylene alcohol.

[0048] In addition, an inorganic binder is added and mixed thoroughly to obtain an organic-inorganic composite binder. The inorganic binder mentioned accounts for 0.5% to 5% of the mass of the biomass-based binder. According to a specific embodiment, the inorganic binder mentioned includes but is not limited to polyaluminum powder and bentonite.

[0049] The biomass-based binder, organic binder, and organic-inorganic composite binder mentioned above can all be applied to steel dust. The steel dust mentioned above includes but is not limited to some industrial waste steelmaking sludge, steelmaking LT ash, bag ash, etc. The addition mass ratio of these steel dusts is about 1 to 10%, for example, about 2 to 8%, and according to a preferred embodiment, it is 2 to 5%, for example, 3%.

[0050] In addition, during the mixing process, it is necessary to add an appropriate amount of water (8%-14%) and stir so that the binder can fully wet and cover the dust and mud particles to form a stable mixture.

[0051] The mixed raw materials are sent to a pelletizing machine for molding. Pellets can be obtained by adjusting the pressure of the equipment to 10-50 MPa (20 MPa, 30 MPa according to the preferred embodiment) and the rotation speed and other parameters.

[0052] The pellets after forming are wet pellets, and the wet pellets are dried to obtain dry pellets. The drying process mentioned is drying at 150 degrees Celsius for 2 hours.

[0053] The technical scheme of the present invention is described below by specific examples. It should be noted that these examples are only used to facilitate the understanding of those skilled in the art and should not be regarded as limiting the scope of protection of the present invention. Unless otherwise specified, the reagents used in the examples can be obtained commercially.

[0054] Example 1

[0055] In Example 1, a biomass-based binder, an organic binder, and an organic-inorganic binder were prepared respectively.

[0056] Experimental Group 1: First, commercially available puffed agricultural product primary processing by-product waste residues were added to a 1wt% NaOH solution and activated at 60°C for 2 hours to further hydrolyze lignin and cellulose and increase their viscosity; then they were fully dried and ground, and the residues were fully mixed at a mass ratio of 2:5 of agricultural product primary processing by-product waste residues: puffed corn starch to obtain a biomass-based binder.

[0057] Experimental group 2: 1 wt % of polyacrylonitrile (the mass percentage mentioned is the mass percentage of the biomass-based binder) was added to the experimental group 1 and mixed thoroughly to obtain an organic binder.

[0058] Experimental Group 3: Based on the biomass-based binder of Experimental Group 1, 1wt% of polyacrylonitrile (the mass percentage mentioned is the mass percentage of the biomass-based binder) and 0.5wt% of polyaluminum powder (the mass percentage mentioned is the mass percentage of the biomass-based binder) are added thereto to obtain an organic-inorganic binder.

[0059] Example 2

[0060] Taking industrial waste steelmaking sludge as an example, using the organic binder of experimental group 2, 3wt% of organic binder and 14wt% of water were added to the industrial waste steelmaking sludge and stirred so that the binder could fully wet and cover the dust and mud particles to form a stable mixture; the mixture was put into a ball press under a pressure of 20Mpa to obtain a single ball of 130g wet pellets, and the obtained wet pellets were dried at 150 degrees Celsius for 2h to obtain dry pellets.

[0061] The strength of the prepared wet pellets and dry pellets were tested respectively.

[0062] Example 3

[0063] Taking industrial waste steelmaking LT ash as an example, using the organic binder of experimental group 2, 3wt% of organic binder and 12wt% of water were added to the industrial waste steelmaking LT ash and stirred so that the binder could fully wet and cover the dust and mud particles to form a stable mixture; the mixture was put into a ball press under a pressure of 20Mpa to obtain a single ball of 130g wet pellets, and the obtained wet pellets were dried at 150 degrees Celsius for 2h to obtain dry pellets.

[0064] The strength of the prepared wet pellets and dry pellets were tested respectively.

[0065] Example 4

[0066] Taking industrial waste bag ash as an example, using the organic binder of experimental group 2, 3wt% of the organic binder and 8wt% of water were added to the industrial waste bag ash and stirred so that the binder could fully wet and cover the dust and mud particles to form a stable mixture; the mixture was put into a ball press under a pressure of 20Mpa to obtain a single ball of 130g wet pellets, and the obtained wet pellets were dried at 150 degrees Celsius for 2h to obtain dry pellets.

[0067] The strength of the prepared wet pellets and dry pellets were tested respectively.

[0068] Example 5

[0069] Taking industrial waste steelmaking sludge as an example, the organic-inorganic composite binder of experimental group 3 was used to add 3wt% of organic-inorganic binder and 14wt% of water to the industrial waste steelmaking sludge and stir the mixture so that the binder can fully wet and cover the dust and mud particles to form a stable mixture; the mixture was put into a ball press under a pressure of 20Mpa to obtain a single ball of 130g wet pellets, and the obtained wet pellets were dried at 150 degrees Celsius for 2h to obtain dry pellets.

[0070] The strength of the prepared wet pellets and dry pellets were tested respectively.

[0071] Example 6

[0072] Taking industrial waste steelmaking LT ash as an example, using the organic-inorganic composite binder of experimental group 3, 3wt% of organic-inorganic binder and 12wt% of water were added to the industrial waste steelmaking LT ash and stirred so that the binder could fully wet and cover the dust and mud particles to form a stable mixture; the mixture was put into a ball press under a pressure of 20Mpa to obtain a single ball of 130g wet pellets, and the obtained wet pellets were dried at 150 degrees Celsius for 2h to obtain dry pellets.

[0073] The strength of the prepared wet pellets and dry pellets were tested respectively.

[0074] Example 7

[0075] Taking industrial waste bag ash as an example, the organic-inorganic composite binder of experimental group 3 was used to add 3wt% of organic-inorganic binder and 8wt% of water to the industrial waste bag ash and stir them so that the binder can fully wet and cover the dust and mud particles to form a stable mixture; the mixture was put into a ball press under a pressure of 20Mpa to obtain a wet pellet of 130g per ball, and the obtained wet pellet was dried at 150 degrees Celsius for 2h to obtain a dry pellet.

[0076] The strength of the prepared wet pellets and dry pellets were tested respectively.

[0077] Example 8

[0078] Example 8 Taking commercially available binders as examples, steelmaking sludge, steelmaking LT ash and bag ash were used as raw materials, and wet pellets and dry pellets were prepared respectively by referring to the above-mentioned methods.

[0079] The steel raw materials, commercially available adhesives and water are stirred so that the adhesive can fully wet and cover the dust and mud particles to form a stable mixture; the mixture is put into a ball press to obtain a wet pellet of 130g per ball under a pressure of 20Mpa, and the obtained wet pellet is dried at 150 degrees Celsius for 2 hours to obtain a dry pellet.

[0080] The wet pellets and dry pellets provided in Experimental Example 2-8 were subjected to strength tests. The strength test method is as follows: In this experiment, a pellet press of model LD-YB-2 was used to measure the compressive strength of the homemade pellets. During the measurement, the sample was crushed by the testing machine, and the maximum force that the sample could withstand was recorded, which was the compressive strength of the activated coke. The obtained strength data are shown in Tables 1, 2, and 3.

[0081] The performance test is as follows:

[0082] Table 1 Dry and wet strength indexes of pellets prepared by organic binder of the present invention

[0083]

[0084] Table 2 Dry and wet strength indexes of pellets prepared by the organic-inorganic composite binder of the present invention

[0085]

[0086] Table 3 Dry and wet strength indexes of pellets prepared with commercially available binders

[0087]

[0088] Based on the above experimental results, it can be concluded that the steelmaking sludge has good molding performance and each binder can obtain good dry and wet strength.

[0089] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A biomass-based binder, characterized in that: include: Activated agricultural byproducts and expanded corn starch; The mass ratio of the activated agricultural and sideline products to the puffed corn starch is 1:10 to 10:10; The activated agricultural and sideline products are obtained by activating by-products of primary processing of agricultural products through alkaline solution.

2. The method for preparing the biomass-based binder according to claim 1, characterized in that: include: (1) Activating byproducts of primary processing of agricultural products by means of an alkaline solution to obtain activated agricultural and sideline products; (2) The activated agricultural and sideline products and puffed corn starch are mixed in a predetermined mass ratio to obtain the biomass-based binder, wherein the predetermined mass ratio is 1:10 to 10:

10.

3. The method for preparing a biomass-based binder according to claim 1, characterized in that: Step (1) comprises: The byproducts of primary processing of agricultural products are mixed with a sodium hydroxide solution with a concentration of 0.5-2 wt%, and activated at 40-80 DEG C for 0.5-4 hours to obtain activated agricultural and sideline products.

4. An organic binder, characterized in that The method comprises the biomatrix binder according to claim 1 and a polymer material, wherein the polymer material accounts for 0.5 to 3% of the mass of the biomatrix binder; Optionally, the polymer material is selected from at least one of polyacrylonitrile and polyacrylonitrile.

5. An organic-inorganic composite binder, characterized in that: include: The biomatrix binder, polymer material and inorganic binder according to claim 1; The polymer material accounts for 0.5 to 3% of the mass of the biomatrix binder; The inorganic binder accounts for 0.5 to 5% of the mass of the biomass-based binder; Optionally, the inorganic binder is selected from at least one of polyaluminum powder and bentonite.

6. A method for cold pressing steel dust into agglomerates, characterized in that: include: Mixing steel dust, the biomass-based binder according to claim 1, the organic binder according to claim 4, the organic-inorganic composite binder according to claim 5, and water in a predetermined mass ratio to form a mixture; cold pressing the mixture into agglomerates under a predetermined pressure to obtain wet pellets; The wet pellets may be optionally dried to obtain dry pellets; Optionally, the drying is performed at 120 to 180 degrees Celsius for 2 to 4 hours.

7. The method according to claim 6, characterized in that The predetermined mass ratio is (90-99):(1-10):(5-15).

8. The method according to claim 6, characterized in that The predetermined pressure is 2-30 MPa.

9. The method according to claim 6, characterized in that The steel dust mud comprises: at least one of steelmaking sludge, steelmaking LT ash or bag ash; Optionally, the strength of the wet pellets prepared from the steelmaking sludge is 196N-305N, and the strength of the dry pellets is 980N-1500N; Optionally, the strength of the wet pellets prepared by the steelmaking LT ash is 98N-170N, and the strength of the dry pellets is 340N-490N; Optionally, the strength of the wet pellets prepared by the bag ash is 98N-175N, and the strength of the dry pellets is 980N-1500N.

10. Use of the biomass-based binder according to claim 1, the organic binder according to claim 4, or the organic-inorganic composite binder according to claim 5 in steel dust.

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