Mineral powder cold-pressed pellet adhesive and preparation method thereof

Abstract

The invention relates to the technical field of pellet adhesives, in particular to a mineral powder cold-pressed pellet adhesive and a preparation method thereof. The preparation raw materials comprise 8-16% of humic acid, 3-8% of an acrylic polymer, 10-25% of lignin, 2-6% of pentosan, 30-45% of kaolin, 2-6% of dispersible latex powder and 5-10% of aluminum oxide. The kaolin adopts high-molecular-weight kaolin as a filler, so that a stronger bonding network can be formed, and the bonding strength and durability of the adhesive are remarkably improved; and the dispersible latex powder is uniformly mixed with other materials due to the dispersity of the dispersible latex powder, so that the defect of agglomeration caused by poor dispersity due to the adoption of high-molecular kaolin is overcome. The proportion of humic acid and lignin is smaller than that of inorganic materials such as kaolin, so that the influence of carbonization of humic acid and lignin on the mechanical properties of pellets can be weakened. And the acrylic polymer and the latex powder in the ingredients cooperate with each other, so that the problem that the viscosity of the adhesive is reduced due to the reduction of the proportions of the humic acid and the lignin is well solved.

Description

Technical Field

[0001] The present invention relates to the technical field of pellet binders, and particularly relates to a cold-pressed pellet binder for ore powder and a preparation method thereof. Background Art

[0002] Cold-pressed pellets are formed by fine grinding materials under the action of mechanical force and capillary force into green balls of a certain particle size. The quality of the green balls is affected by factors such as the type of raw materials, physical and chemical properties, type and dosage of the binder, process parameters and operation of the pelletizing equipment. During the pelletizing process of the materials, the role of the pellet binder is to improve the pelletizing property of the materials, increase the molecular bonding force between the particles in the green balls, and then improve the strength of the green balls. For example, when the cold-pressed pellet binder dissolves in water, it forms a viscous solution that wraps around the particle surface. When the material particles come into contact, they form a "thin film-like" connection bond, thus making the green balls have a relatively high strength.

[0003] Due to the different physical properties of the raw materials, the binders generally used for pellets are divided into organic binders, inorganic binders and composite binders. Organic binders, such as gelatinized starch binders, phenolic resins, etc., can still be used normally at room temperature, but when the temperature gradually rises (>500 °C), they gradually decompose, resulting in a decrease in the strength of the pellets, easy breakage and pulverization in the furnace, and the pellets cannot be reduced and become ineffective. Most inorganic binders use bentonite. Although it overcomes the problem of high-temperature decomposition of organic binders, the impurity content of the pellets will increase.

[0004] After some ore powders are formed into pellets using a binder, when the internal moisture evaporates during drying or use in the furnace, if the evaporation is too fast or the pellet permeability is poor, the pellets will explode and become ineffective.

[0005] Therefore, the present invention provides a cold-pressed pellet binder for ore powder and a preparation method thereof to solve the problem that the current pellet binder is prone to failure at high temperatures. Summary of the Invention

[0006] The purpose of the present invention is to solve the problem in the prior art that the current pellet binder is prone to failure at high temperatures, and to propose a cold-pressed pellet binder for ore powder and a preparation method thereof, so that the binder can be applicable to a wider working environment temperature through the proportioning of components.

[0007] To achieve the above purpose, the present invention adopts the following technical scheme: A cold-pressed pellet binder for ore powder, the preparation raw materials of which include: 8-16% of humic acid, 3-8% of acrylic polymer, 10-25% of lignin, 2-6% of pentosan, 30-45% of kaolin, 2-6% of redispersible latex powder, 5-10% of alumina.

[0008] Preferably, the molecular weight of the acrylic polymer is between 5000 and 7000 Daltons.

[0009] Preferably, the lignin is physically modified.

[0010] A preparation method of a cold-pressed pellet binder for ore powder includes the following steps: S1: Weigh humic acid, acrylic polymer, lignin, pentosan, kaolin, and redispersible latex powder in proportion; S2: Put the humic acid, lignin, and pentosan into a mixer and stir for 5 - 10 minutes; S3: Slowly add the acrylic polymer and then stir for 10 - 15 minutes; S4: Add kaolin and alumina and stir for 15 - 20 minutes; S5: Add redispersible latex powder and stir for 5 - 10 minutes; S6: Cure for 1 - 2 hours; S7: Stir again for 5 - 10 minutes after curing.

[0011] A pellet prepared using a binder, where the binder and water are mixed in a ratio of 1:(0.7 - 0.9) to prepare a binder slurry; Mix the slurry and ore powder evenly in a ratio of (5 - 10):100.

[0012] Preferably, ore powder with a particle size of 150 - 250 mesh and ore powder with a particle size of 70 - 150 mesh are mixed in a ratio of (60 - 80%:20 - 40%).

[0013] A method for making pellets, S1: Weigh the binder, water, and ore powder in proportion; S2: Put the binder and water into a mixer to make a binder slurry; S3: Put the binder slurry and ore powder into a mixer and stir for 10 - 15 minutes; S4: Feed the mixture into a cold press to press into pellets.

[0014] S5: Dry the pellets at 50 - 70 °C for 1 - 2 hours.

[0015] Preferably, the moisture content of the ore powder is ≤5%, and it is pre-dried to a moisture content of ≤2%.

[0016] Compared with the prior art, the present invention provides a cold-pressed pellet binder for ore powder and a preparation method, having the following beneficial effects: 1. The binder of the present invention is made of 8-16% humic acid, 3-8% acrylic polymer, 10-25% lignin, 2-6% pentosan, 30-45% kaolin, 2-6% redispersible latex powder, and 5-10% alumina. Among them, humic acid, lignin, and kaolin are all low-cost and easily obtainable materials, which can reduce the production cost of the binder; they are also degradable, reducing the use pollution.

[0017] 2. In this solution, high molecular weight kaolin is used as the filler for kaolin, which can form a stronger bonding network, significantly improving the bonding strength and durability of the binder; the high molecular kaolin and the redispersible latex powder are used in synergy, and the redispersible latex powder is used to evenly mix with other materials due to its own redispersibility, so as to offset the defect of poor dispersibility and agglomeration caused by using high molecular kaolin.

[0018] 3. In this solution, ore powder with a particle size of 150-250 mesh and ore powder with a particle size of 70-150 mesh are selected and mixed in a ratio of (20-40%: 60-80%). The larger ore powder particles form larger voids inside the pellets, providing channels for the diffusion of water vapor, improving the diffusion and shrinkage uniformity of steam, and thus reducing cracks caused by different internal and external pressures.

[0019] 4. In this solution, the proportion of humic acid and lignin is relatively small compared to inorganic materials such as kaolin. Kaolin, especially modified kaolin, has good thermal stability, enabling the pellets to maintain their complete shape and not powder at high temperatures, thus weakening the impact of the carbonization of humic acid and lignin on the mechanical properties of pelletizing. The acrylic polymer and latex powder in the formulation work in synergy to well solve the problem of the reduced viscosity of the binder caused by reducing the proportion of humic acid and lignin.

[0020] The composite binder III provided by the present invention has a low dosage, low price, and excellent performance. Compared with the inorganic binder bentonite, it can significantly improve the TFe grade of the finished pellet ore, and solve the problems of poor thermal stability and low strength of the pellets prepared with organic binders. It can be used alone or partially replace bentonite, improving the compressive strength of the green pellets and the finished pellets, achieving the purpose of increasing the output of the blast furnace, saving coke, reducing environmental pollution, and improving economic benefits.

[0021] Compared with the prior art, the cold-pressed pellet composite binder provided by the present invention and its preparation method have active groups contained in the binder, which determine its high specific surface area, extremely strong hygroscopicity and adhesiveness, and strong performance of adsorbing heavy metal ions. A firm three-dimensional structure of net-on-net is formed inside the pellets. At the same time, a network with specific water vapor permeability is formed by multiple active functional groups and water-soluble polymers, which is conducive to the diffusion of water vapor from the inside of the pellets to the surface of the pellets, reducing the vapor pressure inside the pellets, increasing the green pellet bursting temperature, significantly reducing the return fines, increasing the output, and the finished pellets having a large compressive strength. The cold-pressed pellet composite binder provided by the present invention can be used alone or in combination with bentonite, which increases the compressive strength of the pellets and the finished pellets. It not only increases the iron grade of the pellet ore, but also solves the problems of poor thermal stability and low strength of the pellets prepared with organic binders, reduces the fuel consumption, decreases the slag discharge, and has obvious economic benefits of energy saving and output increase. Other advantages, objects and features of the present invention will be set forth to some extent in the following description; and to some extent, will be obvious to those skilled in the art based on the study of the following text; or can be learned from the practice of the present invention. Detailed implementation manners

[0022] The technical solutions in the embodiments of the present invention will be described clearly and completely below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments.

[0023] Embodiment 1, preparation method of the binder: S1: Use an electronic balance (accuracy 0.01 g) to weigh humic acid, acrylic polymer, lignin, pentosan, kaolin, and redispersible latex powder in proportion. Powdery materials such as humic acid, lignin, and pentosan are pre-screened through a sieve (100 mesh) by a screening machine to ensure no lumping.

[0024] The weight allocation of the above materials is: humic acid 8 - 16%, acrylic polymer 3 - 8%, lignin 10 - 25%, pentosan 2 - 6%, kaolin 30 - 45%, redispersible latex powder 2 - 6%, alumina 5 - 10%.

[0025] The kaolin, as a filler, has a relatively low price, which can reduce the production cost of the binder. Moreover, according to the characteristics of kaolin, it can improve the hardness, wear resistance and impact resistance of the binder. The molecular weight of kaolin is 9000±500 daltons. The kaolin with a high molecular weight has larger particles, which can form a stronger bonding network, significantly improving the bonding strength and durability of the binder. However, due to the greater bonding strength, it is easy to cause agglomeration in the binder, thus affecting the effect of the binder and resulting in poor dispersibility of the binder. Therefore, in this solution, the high-molecular kaolin is used in combination with the redispersible latex powder. The redispersible latex powder is uniformly mixed with other materials by virtue of its own dispersibility to offset the defect of poor dispersibility caused by the use of high-molecular kaolin, which leads to agglomeration. Preheating the kaolin by calcination can change the crystal structure (forming mullite or cristobalite), improve the thermal stability of the binder, and then improve the high-temperature resistance of the pellets.

[0026] The humic acid is natural humic acid extracted from lignite or humus soil, with a pH value of 5.5 - 7.0. The raw materials are extensive and the cost is low. It is a powder, which is convenient for storage and addition. The humic acid has a certain hydrophobicity, which can improve the stability of the pellets in a humid environment.

[0027] After the lignin is modified, its dispersibility is enhanced, further correcting the agglomeration defect of the high-molecular kaolin. At the same time, the modified lignin has excellent bonding properties and can form a firm bond with the powdery materials through its aromatic structure and functional groups (such as phenolic hydroxyl groups, alcoholic hydroxyl groups, etc.). The humic acid contains rich functional groups such as carboxyl groups and phenolic hydroxyl groups, which can enhance the bonding effect through ion exchange and hydrogen bond interaction. The humic acid and lignin can play a synergistic effect when producing the binder. When the two are combined, a more complex bonding network is formed, significantly improving the bonding strength of the binder, and then increasing the pelletization rate. Moreover, both lignin and humic acid are biodegradable, reducing environmental pollution and meeting the requirements of green production.

[0028] The molecular weight of the acrylic polymer is between 5000 and 7000 daltons, which can form a firm bond with the material surface. By adjusting the molecular weight, the viscosity, strength and flexibility of the binder can be changed. When agglomerating, the pellets can withstand a certain deformation without cracking.

[0029] The pentosan can adjust the viscosity of the binder, improve the storage stability of the binder, and prevent the binder from delaminating or precipitating. The pentosan molecules can form a hydration layer in water, and their long molecular chains are entangled with each other in water, further increasing the viscosity to achieve the thickening of the binder. And it can be compatible with other components without affecting the performance of other materials.

[0030] The alumina is doped in the binder. The high hardness of the alumina can improve the wear resistance and scratch resistance of the binder, facilitating the storage after pellet forming; while the high melting point of the alumina can improve the thermal stability of the binder, enabling the binder to still be used normally in a high-temperature environment (>500 °C).

[0031] S2: Put humic acid, lignin, and polyxylan into a double-shaft mixer (model: SHR-500, rotation speed range: 10 - 50 rpm). The input shaft is equipped with a reduction motor, and stir at a low speed of 40 rpm at normal temperature (20 - 25 °C) for 5 - 10 minutes to pre-mix the powdery materials and form a basic mixture. The active groups (such as carboxyl groups and hydroxyl groups) in humic acid and lignin start to interact with each other to form a preliminary hydrogen bond network.

[0032] S3: Slowly add the acrylic polymer and stir at a low speed of 30 rpm at normal temperature (20 - 25 °C) for 10 - 15 minutes to ensure uniform mixing of the acrylic polymer and the basic mixture. The carboxyl groups in the acrylic polymer form hydrogen bond interactions with the hydroxyl groups in humic acid and lignin, which can enhance the viscosity of the finished binder.

[0033] S4: Add kaolin and alumina and stir at a low speed of 30 rpm at normal temperature (20 - 25 °C) for 15 - 20 minutes to make the kaolin and alumina uniformly dispersed in the mixture. Kaolin and alumina, as inorganic fillers, are filled between the organic components to enhance the mechanical strength and high-temperature resistance of the binder.

[0034] S5: Add redispersible latex powder and stir at a low speed of 30 rpm at normal temperature (20 - 25 °C) for 5 - 10 minutes to make the redispersible latex powder uniformly dispersed and avoid caking. The polymer particles in the latex powder are dispersed under the stirring action, and at the same time, part of the water is released to form a uniform emulsion, which not only helps the uniform dispersion of the mixture but also further enhances the adhesion and flexibility of the binder.

[0035] S6: Transfer the mixture to a curing tank (with temperature control function, volume: 500 L), set the curing temperature to 20 - 30 °C, and let it stand for curing at normal temperature for 1 - 2 hours to enable the components to fully react and form a stable binder system. Among them: The active groups (such as carboxyl groups and hydroxyl groups) in humic acid, lignin, and polyxylan are further cross-linked to form a more stable hydrogen bond network.

[0036] The polymer chains in the acrylic polymer and the latex powder undergo physical adsorption with the inorganic fillers (kaolin, alumina) to enhance the mechanical properties of the binder.

[0037] The polymer particles in the latex powder gradually fuse during the curing process to form a continuous adhesive film.

[0038] S7: After ripening, put the preliminarily formed adhesive mixture into a double-shaft mixer and stir it at a low speed of 30 rpm and normal temperature (20 - 25 °C) for 5 - 10 minutes to ensure the uniformity of the mixture and avoid possible local non-uniformity during the ripening process.

[0039] The above-mentioned adhesive is in powder form after preparation, which is convenient for storage and transportation. Then, random sampling is carried out for quality inspection. After passing the monitoring, it is sent to an automatic packaging machine for automatic sub-packaging.

[0040] The order of feeding materials in the above process is organic materials (humic acid, lignin, polyxylan) - acrylic polymer - inorganic material actinium (kaolin and alumina) - latex powder. The purpose is as follows: First, the organic materials are mixed. Utilizing the viscosity and adsorbability of the materials themselves, a basic viscous mixture is formed. Then, the acrylic polymer is added. The acrylic polymer undergoes hydrogen bonding with organic components such as humic acid and lignin, enhancing the initial viscosity and film-forming property of the adhesive. Adding the acrylic polymer after the organic components also avoids too high a local concentration of the acrylic polymer during the initial mixing, which may cause excessive local viscosity and uneven mixing. Then, adding the inorganic materials later also aims to prevent the organic materials from caking during mixing. Finally, adding the latex powder is to avoid premature addition and dissolution during the initial mixing. This order not only ensures the uniformity of the mixture among various components but also fully exerts the functions of each component and avoids interference among components.

[0041] It should be noted that if raw materials such as humic acid and lignin are too dry, it is difficult to form a uniform viscous mixture during mixing, which will affect the performance of the adhesive. At this time, an appropriate amount of water can be added to improve fluidity. The amount of water added is usually 1 - 3% of the total mass (specifically adjusted according to the humidity of the on-site materials), and during the stirring process, atomized water vapor is slowly and intermittently sprayed through a sprayer (such as an atomizing nozzle) to avoid local over-wetting. After the water is added, stirring still needs to continue for at least 10 minutes to ensure the uniform dispersion of the water. And these waters will also fully react with each component within 1 - 2 hours of ripening. For the production process that requires adding water, after ripening, drying treatment is also required to remove the excess water.

[0042] The adhesive in the above solution has good adhesiveness due to the synergy of humic acid, lignin, and polyxylan. Using kaolin and alumina as fillers, it not only has good physical adsorption properties, improving the storage stability of the adhesive, but also has good thermal stability and mechanical properties. The dispersible latex powder synergizes with other materials to overcome the defect of easy agglomeration brought by closed high-molecular-weight kaolin. The acrylic polymer can also form a waterproof film with the dispersible latex powder, enhancing the water resistance of the adhesive. And most components, such as humic acid, lignin, and polyxylan, are renewable resources, easy to obtain and degradable, which reduces the production cost and also reduces the use pollution.

[0043] Example 2, a preparation method for cold-compressed pellets of ore powder using the binder of Example 1: S1: Weigh the binder, water, and ore powder in proportion; and use a screening machine to screen the ore powder to ensure uniform particle size.

[0044] S2: Put the binder into a mixer, gradually add water while stirring, and stir for 10 - 15 minutes. After the binder contacts water, it partially dissolves to form a viscous liquid, thus making a binder slurry.

[0045] S3: Put the binder slurry and the ore powder into a mixer, and uniformly mix the slurry and the ore powder according to the ratio of (5 - 10):100. Mix and stir for 10 - 15 minutes. The binder slurry wraps the ore powder particles, and under the action of stirring, ensure that the surface of the ore powder particles is uniformly covered with the binder, providing a basis for pellet formation.

[0046] S4: Feed the uniformly mixed wet material into a cold press (disc pelletizer or drum pelletizer) for rolling the wet material into pellets.

[0047] Use a disc pelletizer with a rotation speed of 20 - 30 rpm and an inclination angle of 45 - 55°. Use a drum pelletizer with a rotation speed of 10 - 20 rpm. During the rolling process, small ball nuclei gradually form in the wet material. The small ball nuclei adhere to more wet material through rolling and gradually grow until pellets of the required size (usually 10 - 15 mm) are formed. During the rolling process, the surface of the pellets gradually becomes smooth and dense.

[0048] S5: Feed the formed pellets into a drying device and dry them at 50 - 70°C for 1 - 2 hours; or dry them at 100 - 150°C for 20 - 30 minutes. The free water in the pellets gradually evaporates until the water content of the pellets drops to 2 - 3%, enabling the binder to further cure during the drying process and enhancing the structural stability of the pellets.

[0049] The dried pellets can also be fed into a roasting device (rotary kiln or shaft furnace) for high-temperature roasting (800 - 1200°C) for 30 - 60 minutes. The ore powder particles and the kaolin in the binder partially melt at high temperature to form a firm crystal structure, while the lignin and humic acid are carbonized at high temperature, further enhancing the pellet strength.

[0050] S6: Feed the dried or roasted pellets into a cooler (either air-cooling or water-cooling equipment) and cool them for 10 - 20 minutes to room temperature. The pellets are further cured during the cooling process, stabilizing the structure.

[0051] S7: Screen the cooled pellets again, retain the finished products with a particle size of 10 - 15 mm, and remove unqualified pellets and debris to ensure product consistency.

[0052] S8: Finally, pack the finished pellets. The packing specifications are set according to customer requirements, specifying how many pounds per bag or per box.

[0053] It should be noted that before screening and weighing the raw materials, the ore powder needs to be pretreated. If the moisture content of the ore powder is ≤5%, the ore powder needs to be pre-dried to a moisture content of ≤2% (preferably 1-2%). This is to prevent the ore powder from being too wet and easily adhering to the mold, resulting in difficult demolding; and if the moisture content is too high, it will hinder the close contact between particles, reduce the mechanical strength of the pellets, make the pellets prone to deformation, and increase the rejection rate. At the same time, reducing the moisture content of the ore powder reduces the amount of water evaporation during the pellet drying process, avoiding cracks in the pellets due to rapid water loss.

[0054] Water content Formability Pellet strength Too high (>2%) Easily deformed, sticking to the mold Low, easily cracked Optimal (1-2%) Easily formed High, uniform strength Too low (<1%) Difficult to form Low, fragile In addition, during the drying process of green pellets, it may be due to the untimely evaporation and dissipation of moisture inside the green pellets, resulting in an increase in internal pressure of the pellets and causing the pellets to crack, thereby affecting the yield. Therefore, the ore powder selected is a mixture of ore powder with a particle size of 150-250 mesh and ore powder with a particle size of 70-150 mesh in a ratio of (20-40%: 60-80%). Larger-sized ore powder particles form larger voids inside the pellets, providing a channel for the diffusion of water vapor, improving the uniformity of steam diffusion and shrinkage, and thus reducing cracks caused by different internal and external pressures.

[0055] In the binder ratio, components such as humic acid and lignin will undergo carbonization during metallurgy, forming carbonaceous materials and inorganic ash, which may cause microcracks. Therefore, in this solution, the proportion of humic acid and lignin relative to inorganic materials such as kaolin is relatively small. Kaolin, especially modified kaolin, has good thermal stability, which can weaken the impact of the carbonization of humic acid and lignin on pellet formation. The acrylic polymer and latex powder in the formulation work together to well solve the problem of the reduced viscosity of the binder caused by reducing the proportion of humic acid and lignin.

[0056] Example 3, pellets prepared with binders of different component ratios.

[0057] Formula 1, the proportion of each component: Prepare binder powder by mixing 12% humic acid, 6% acrylic polymer, 21% lignin, 5% pentosan, 42% kaolin, 5% redispersible latex powder, and 9% alumina.

[0058] Mix the binder powder and water in a ratio of 1:0.8 to prepare a binder slurry; Mix the slurry and ore powder evenly in a ratio of 7:100.

[0059] The qualified pellets finally made according to the above ratios have a compressive strength of 12.5 MPa, an agglomeration rate of 95%, and after being heated at 600 °C for 1 hour, the pellets remain intact without obvious pulverization.

[0060] Formula II. Proportions of each component: Prepare the binder powder according to the proportions of 10% humic acid, 4% acrylic polymer, 22% lignin, 4% pentosan, 45% kaolin, 5% redispersible latex powder, and 10% alumina.

[0061] Mix the binder powder and water in a ratio of 1:0.7 to prepare the binder slurry; Mix the slurry and ore powder evenly in a ratio of 8:100.

[0062] The qualified pellets finally made according to the above ratios have a compressive strength of 14.0 MPa, an agglomeration rate of 97%, and after being heated at 600 °C for 1 hour, the pellets remain intact without obvious pulverization.

[0063] Formula III. Proportions of each component: Prepare the binder powder according to the proportions of 19% humic acid, 8% acrylic polymer, 25% lignin, 6% pentosan, 30% kaolin, 6% redispersible latex powder, and 6% alumina.

[0064] Mix the binder powder and water in a ratio of 1:0.9 to prepare the binder slurry; Mix the slurry and ore powder evenly in a ratio of 6:100.

[0065] The qualified pellets finally made according to the above ratios have a compressive strength of 11.0 MPa, an agglomeration rate of 93%, and after being heated at 600 °C for 1 hour, the surface of the pellets is slightly pulverized.

[0066] Formula IV. Proportions of each component: Prepare the binder powder according to the proportions of 12% humic acid, 7% acrylic polymer, 16% lignin, 6% pentosan, 45% kaolin, 6% redispersible latex powder, and 8% alumina.

[0067] Mix the binder powder and water in a ratio of 1:0.8 to prepare the binder slurry; Mix the slurry and ore powder evenly in a ratio of 7:100.

[0068] The qualified pellets finally made according to the above ratios have a compressive strength of 13.0 MPa, an agglomeration rate of 96%, and after being heated at 600 °C for 1 hour, the pellets remain intact without obvious pulverization.

[0069] Formula V. Proportions of each component: Prepare the binder powder according to the ratio of 14% humic acid, 5% acrylic polymer, 22% lignin, 4% pentosan, 40% kaolin, 5% redispersible latex powder, and 10% alumina.

[0070] Mix the binder powder and water in a ratio of 1:0.8 to prepare the binder slurry; Mix the slurry and ore powder evenly in a ratio of 7:100.

[0071] The qualified pellets finally made according to the above ratio have a compressive strength of 13.5 MPa, a pelletization rate of 97%, and after heating at 600 °C for 1 hour, the pellets remain intact and there is no obvious pulverization.

[0072] Formula VI, proportions of each component: Prepare the binder powder according to 10% humic acid, 6% acrylic polymer, 21% lignin, 5% pentosan, 44% kaolin, 5% redispersible latex powder, and 9% alumina.

[0073] Mix the binder powder and water in a ratio of 1:0.8 to prepare the binder slurry; Mix the slurry and ore powder evenly in a ratio of 7:100.

[0074] The qualified pellets finally made according to the above ratio have a compressive strength of 13.0 MPa, a pelletization rate of 96%, and after heating at 600 °C for 1 hour, the pellets remain intact and there is no obvious pulverization.

[0075] Formula VII, proportions of each component: Prepare the binder powder according to 14% humic acid, 6% acrylic polymer, 21% lignin, 5% pentosan, 40% kaolin, 5% redispersible latex powder, and 9% alumina.

[0076] Mix the binder powder and water in a ratio of 1:0.8 to prepare the binder slurry; Mix the slurry and ore powder evenly in a ratio of 7:100.

[0077] The qualified pellets finally made according to the above ratio have a compressive strength of 12.0 MPa, a pelletization rate of 94%, and after heating at 600 °C for 1 hour, the surface of the pellets is slightly pulverized.

[0078] Formula VIII, proportions of each component: Prepare the binder powder according to 12% humic acid, 6% acrylic polymer, 18% lignin, 5% pentosan, 45% kaolin, 5% redispersible latex powder, and 9% alumina.

[0079] Mix the binder powder and water in a ratio of 1:0.8 to prepare the binder slurry; Mix the slurry and ore powder evenly at a ratio of 7:100.

[0080] The qualified pellets finally made according to the above ratio have a compressive strength of 14.5 MPa, a pelletization rate of 97%. When heated at 600 °C for 1 hour, the pellets remain intact and there is no obvious pulverization.

[0081] Formula Nine, proportions of each component: Prepare the binder powder by mixing humic acid 12%, acrylic polymer 6%, lignin 25%, pentosan 5%, kaolin 38%, redispersible latex powder 5%, and alumina 9%.

[0082] Mix the binder powder and water in a ratio of 1:0.8 to prepare the binder slurry; Mix the slurry and ore powder evenly at a ratio of 7:100.

[0083] The qualified pellets finally made according to the above ratio have a compressive strength of 11.5 MPa, a pelletization rate of 93%. When heated at 600 °C for 1 hour, the surface of the pellets is slightly pulverized.

[0084] Comparative Example 1: Prepare the binder slurry with bentonite binder (single binder) and water in a ratio of 1:1.0, and then mix the slurry and ore powder in a ratio of 7:100. The compressive strength of the pellet product is 9.5 MPa, the pelletization rate is 90%. When heated at 600 °C for 1 hour, obvious cracks appear on the surface of the pellets and part of the pellets are pulverized.

[0085] Comparative Example 2: Prepare the binder slurry with gelatinized starch binder (single binder) and water in a ratio of 1:1.2, and then mix the slurry and ore powder in a ratio of 7:100. The compressive strength of the pellet product is 8.0 MPa, the pelletization rate is 88%. When heated at 600 °C for 1 hour, the gelatinized starch is completely carbonized, causing the pellets to be completely pulverized.

[0086] Comparison table of ingredients and properties of Formula One to Formula Nine The first five examples: By adjusting the proportions of each component, it is found that the increase in the content of kaolin significantly improves the compressive strength and pelletization rate; while the increase in the content of humic acid and lignin may lead to a decrease in performance. And the more ash content after carbonization, the higher the probability of pellet pulverization and cracking.

[0087] The last four examples compared with Example 1: By separately adjusting the contents of humic acid, lignin and kaolin, the positive effect of kaolin on performance and the potential negative effects of humic acid and lignin on performance are further verified.

[0088] As described above, it is only the preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, making equivalent substitutions or changes should be covered within the protection scope of the present invention.

[0089] In the description of this specification, the description referring to terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0090] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

Claims

1. A cold-pressed pellet binder for ore powder, characterized in that, Its preparation raw materials include: 8-16% of humic acid, 3-8% of acrylic polymer, 10-25% of lignin, 2-6% of pentosan, 30-45% of kaolin, 2-6% of redispersible latex powder, and 5-10% of alumina.

2. The binder for cold-pressed pellets of ore powder according to claim 1, characterized in that, The molecular weight of the acrylic polymer is between 5000 and 7000 Daltons.

3. The binder for cold-pressed pellets of ore powder according to claim 1, characterized in that, The lignin is physically modified.

4. The preparation method of a cold-pressed pellet binder for mineral powder according to claim 1, comprising the following steps: S1: Weigh humic acid, acrylic polymer, lignin, pentosan, kaolin, and redispersible latex powder in proportion. S2: Put humic acid, lignin, and pentosan into a mixer and stir for 5-10 minutes. S3: Slowly add the acrylic polymer and then stir for 10-15 minutes. S4: Add kaolin and alumina and stir for 15-20 minutes. S5: Add redispersible latex powder and stir for 5-10 minutes. S6: Cure for 1-2 hours. S7: Stir again for 5-10 minutes after curing.

5. A pellet prepared using the binder according to claim 1, characterized in that, The binder and water are mixed in a ratio of 1:(0.7-0.9) to prepare a binder slurry. The slurry and mineral powder are uniformly mixed in a ratio of (5-10):

100.

6. A pellet according to claim 5, wherein, Mineral powder with a particle size of 150-250 mesh and mineral powder with a particle size of 70-150 mesh are mixed in a ratio of (60-80%:20-40%).

7. A method for making the pellets according to claim 6, characterized in that S1: Weigh the binder, water, and mineral powder in proportion. S2: Put the binder and water into a mixer to make a binder slurry. S3: Put the binder slurry and mineral powder into a mixer and stir for 10-15 minutes. S4: Feed the mixture into a cold press to press into pellets. S5: Dry the pellets at 50-70 °C for 1-2 hours.

8. A method for making pellets according to claim 7, characterized in that, The moisture content of the mineral powder is ≤5%, and it is pre-dried to a moisture content of ≤2%.

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