Preparation method of high-strength titanium-containing cold-solidified pellets

Abstract

This invention discloses a method for preparing high-strength titanium-containing cold-cured pellets, belonging to the field of metallurgical resource recovery and pellet preparation technology. The pellets prepared by this invention use ilmenite as the main raw material, combined with coal gangue, lime, and water as a composite raw material system. The preparation process is achieved through a process of "composite binder preparation - uniform material mixing - cold pressing and densification - room temperature curing". This invention innovatively uses coal gangue as an endogenous reducing agent and the core component of the binder, realizing the resource utilization of solid waste. The pellets prepared by this invention have a compressive strength of 4500-6000 N / pellet, a TFe content of 29-32%, and a TiO2 content of 34-44%. This invention eliminates the need for high-temperature roasting, effectively solving the problems of insufficient strength, high cost, and serious pollution associated with existing titanium-containing pellets. The solution of this invention is suitable for the efficient utilization of titanium resources in the metallurgical industry and is easy to promote industrially.

Description

Technical Field

[0001] This invention relates to the field of metallurgical resource recycling and pellet preparation technology, specifically to a method for preparing high-strength titanium-containing cold-solidified pellets. Background Technology

[0002] Titanium pellets, as a key raw material for the comprehensive utilization of titanium resources and steel smelting, are widely used in metallurgical fields such as titanium material preparation, high-strength alloy smelting, and blast furnace ironmaking. Their performance directly affects subsequent smelting efficiency, product quality, blast furnace life, and production costs. Currently, the preparation technology of titanium-containing pellets is mainly divided into two categories: high-temperature roasting and cold solidification forming, but both have significant technical bottlenecks. The high-temperature roasting method, which sinters the raw materials at a high temperature of 1200-1350 ℃, can ensure a certain strength of the pellets, but it has three major problems: ① Huge energy consumption, requiring a large amount of coal powder, natural gas, and other fuels, resulting in high production costs; ② Significant environmental pressure, as the roasting process generates a large amount of harmful gases such as CO2 and SO2, as well as dust, which contradicts the concept of green metallurgy development; ③ High equipment investment and maintenance costs, and long production cycles, making it difficult to adapt to the needs of rapid industrial production. Cold-forming methods have gradually gained attention due to their low energy consumption and simple process, but existing technologies still have some shortcomings that are difficult to overcome: ① Insufficient strength: The compressive strength of existing cold-formed titanium pellets is generally lower than 2000N / piece, making them prone to breakage and pulverization during storage, transportation, and smelting, which seriously affects utilization efficiency; ② Poor binder compatibility: Cold-formed titanium pellets mostly use polymers or bentonite as binders, which are costly and easily introduce impurities such as silicon and aluminum, affecting the purity of titanium smelting; ③ Low titanium reduction efficiency: Relying on the addition of additional reducing agents such as coke, which increases costs and introduces new impurities; ④ Low resource utilization rate: Industrial waste is not effectively utilized, which is not in line with the trend of resource recycling; ⑤ Poor process stability: Sensitive to parameters such as raw material particle size and moisture content, resulting in large fluctuations in product quality.

[0003] Given that existing high-titanium pellet preparation technologies cannot simultaneously optimize strength performance, environmental protection requirements, and production costs, there is an urgent need to develop a high-strength titanium-containing cold-solidified pellet to solve these problems. Summary of the Invention

[0004] In view of this, the present invention aims to overcome the defects of existing high-titanium pellet preparation technology, such as insufficient strength, high cost, serious pollution and low resource utilization, and provides a method for preparing high-strength titanium-containing cold-solidified pellets, realizing the three-in-one technical goal of "high-strength molding - solid waste resource utilization - low-temperature and low-consumption preparation", and providing the metallurgical industry with environmentally friendly, economical and high-performance titanium-containing smelting raw materials.

[0005] To achieve the above-mentioned objectives, the present invention adopts the following technical solution: A method for preparing high-strength titanium-containing cold-solidified pellets includes the following steps: (1) Raw material pretreatment: Weigh out ilmenite, coal gangue and lime, grind them separately, and then take water for later use; (2) Preparation of composite binder: Coal gangue and lime are put into a mixing device, and water is added while stirring to make a binder; (3) Material mixing: Mix the binder with ilmenite and stir until homogeneous; (4) Cold pressing: The mixture is placed in a mold and cold pressed to obtain shaped pellets; (5) Room temperature curing: The formed pellets are cured to obtain high-strength titanium-containing cold-cured pellets.

[0006] Furthermore, the high-strength titanium-containing cold-set pellets described in this invention are composed of the following raw materials by mass fraction: 60-80 wt% ilmenite, 10-25 wt% coal gangue, and 5-15 wt% lime. The amount of water used is 5-15 wt% of the total mass of ilmenite, coal gangue, and lime. The water is industrial soft water or deionized water.

[0007] The industrial soft water conforms to the national standard GB / T1576-2008.

[0008] The ilmenite selected in this invention has a TiO2 content ≥ 45 wt% and an Fe content ≥ 35 wt%; the selected coal gangue has a loss on ignition of 8-12 wt%, a SiO2 content ≥ 53 wt%, and an Al2O3 content ≥ 18 wt%; and the selected lime has an effective calcium oxide content ≥ 90 wt%.

[0009] The use of industrial soft water in this invention is primarily because industrial hard water, with its higher Ca and Mg ion content, introduces additional impurities that negatively impact the bonding effect. Meanwhile, industrial pure water is prohibitively expensive, contradicting the purpose of this invention. Industrial soft water, on the other hand, is generally more economical and does not compromise the performance of the composite adhesive.

[0010] The reaction principle of this invention: (1) High-strength molding mechanism: The present invention achieves high strength of pellets through the synergistic effect of "chemical cementation + physical densification". Lime reacts with water to generate Ca(OH)2, which then undergoes a hydration reaction with SiO2 and Al2O3 in coal gangue to generate cementing substances such as hydrated calcium silicate (CSH) and hydrated calcium aluminate (CAH), forming a three-dimensional network structure that firmly binds the ilmenite particles.

[0011] (2) High-efficiency titanium reduction mechanism: The 8-12 wt% loss on ignition in coal gangue mainly comes from its carbonaceous components, which act as endogenous reducing agents and preferentially react with titanium oxides during the smelting process (TiO2+C→Ti+CO2↑), avoiding the introduction of impurities by adding additional reducing agents. At the same time, the cementitious structure formed by SiO2, Al2O3 and lime hydration products in coal gangue can reduce the oxidation loss of titanium during the smelting process, further improving the titanium reduction efficiency.

[0012] Furthermore, in step (1), the proportion of ilmenite ground to pass through a 200-mesh sieve is not less than 80%, the proportion of coal gangue ground to pass through a 200-mesh sieve is not less than 70%, and the lime is ground to pass through a 150-mesh sieve. The moisture content of the ilmenite, coal gangue, and lime is controlled to be ≤2%.

[0013] Furthermore, the stirring speed in step (2) is 100-200 r / min, and the stirring time is 10-20 min; The water is added at a rate of 4-6 mL / min.

[0014] Furthermore, the room temperature viscosity of the adhesive described in step (2) is 6000-8000 mPa·s.

[0015] Furthermore, the stirring speed in step (3) is 100-150 r / min, the stirring time is 15-25 min, and the mixing uniformity is ≥90%.

[0016] Preferably, the stirring speed is 120-130 r / min and the stirring time is 20 min.

[0017] Furthermore, the mold mentioned in step (4) is a custom-made spherical mold with a diameter of φ45-55 mm; The cold pressing is a process of applying 20-30 MPa pressure to cold press and holding the pressure for 20-30 seconds; The molding density of the shaped pellets is ≥2.8 g / cm³.

[0018] Preferably, the molding pressure is 22-26 MPa and the holding time is 25 seconds.

[0019] Furthermore, the curing described in step (5) is to cure in an environment of 20-30℃ and 60-80% relative humidity for 4-7 days.

[0020] Preferably, the curing temperature is 25°C, the relative humidity is 70%, and the curing time is 5 days.

[0021] Compared with the prior art, the present invention has the following outstanding advantages: (1) Excellent strength performance: The compressive strength of the pellets prepared by this invention reaches 4500-6000 N / piece, which is significantly higher than the compressive strength of titanium-containing pellets in the prior art. At the same time, the pellets prepared by this invention can meet the mechanical performance requirements during storage, transportation and smelting processes, with a breakage rate of less than 3%.

[0022] (2) Significant environmental protection and energy saving effects: This invention uses coal gangue as the core raw material to realize the high-value utilization of industrial solid waste and reduce the pollution of solid waste storage; no high-temperature roasting is required, energy consumption and CO2 emissions are reduced, and no harmful substances such as SO2 and dust are generated; no wastewater or waste residue is discharged in the process, which is in line with the development trend of green metallurgy.

[0023] (3) Significant cost advantage: The coal gangue used in this invention is widely available and inexpensive, which greatly reduces the cost of raw materials; no high-temperature roasting equipment is required, the process is simple, and the investment and operating costs of equipment can be effectively reduced, resulting in significant market competitiveness. Attached Figure Description

[0024] Figure 1 This is a flow chart of the preparation process of the high-strength, high-titanium cold-solidified pellets of the present invention. Detailed Implementation

[0025] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Example 1

[0026] The high-strength titanium-containing cold-set pellets of this embodiment have raw material ratios and various indicators that strictly meet the requirements of the invention, as detailed below: The amount of ilmenite added is 70 wt%, the particle size is -200 mesh accounting for 85%, the TiO2 content is 45 wt%, the Fe content is 37 wt%, the raw material is free of impurities and agglomerates, and the test results meet the industrial grade use standards; The coal gangue content is 20 wt%, the particle size is -200 mesh (75%), the loss on ignition is 8 wt%, the SiO2 content is 55 wt%, and the Al2O3 content is 20 wt%. The amount of lime added is 10 wt%, the effective calcium oxide content is 92 wt%, there is no obvious clumping, the color is uniform, and after grinding, all of it passes through a 150-mesh sieve. The amount of water added is 10 wt% of the total mass of ilmenite, coal gangue and lime. Industrial soft water is used, which is free of impurities and corrosive, and the water quality meets industrial standards.

[0027] Its preparation method is as follows (1) Raw material pretreatment: Weigh ilmenite, coal gangue, and lime, and coarsely crush them to a particle size ≤10mm using a jaw crusher, and then grind them to the specified particle size using a ball mill. Ilmenite -200 mesh accounts for 85%, coal gangue -200 mesh accounts for 75%, and all lime passes through a 150 mesh sieve; hot air drying is used as an auxiliary process during grinding to control the moisture content of the three raw materials to ≤1.5%; (2) Preparation of composite binder: The pretreated coal gangue and lime were put into a double helix mixer. The mixer was started and stirred at a speed of 150 r / min. While stirring, metered industrial soft water was added at a rate of 5 mL / min to avoid clumping caused by adding water too quickly. Stirring was continued for 15 min to ensure that the coal gangue and lime fully hydrated and formed a uniform and viscous composite binder. The viscosity of the binder was measured to be 6500 mPa·s using a rotational viscometer (25℃). It was then put into use. (3) Uniform mixing of materials: Add the prepared composite binder to the pretreated ilmenite, adjust the speed of the double helix mixer to 120 r / min, and continue mixing for 20 min; during the mixing process, check the uniformity of mixing to ensure that the ilmenite particles in the material are completely coated by the binder, and finally the uniformity of mixing reaches 92%. After the mixing is qualified, the material is discharged. (4) Cold pressing and densification: The uniformly mixed material is fed into a hydraulic briquetting machine, placed into a φ50 mm spherical custom mold, and subjected to a pressure of 20 MPa for cold pressing and holding for 25 seconds; after molding, the briquetting pellets are taken out and the molding density is tested to be 2.9 g / cm³. The surface has no cracks or slag, and the molding is qualified. (5) Room temperature curing: The formed pellets are neatly stacked in the curing room with a spacing of 5 cm to avoid mutual compression; the curing environment temperature is controlled at 25 ℃ and the relative humidity is 70% for 5 days; the pellets are turned over once a day during the curing process to ensure uniform curing; the compressive strength of the pellets is tested on the 5th day of curing, and they can be shipped out after meeting the standard.

[0028] The high-strength titanium-containing cold-set pellets prepared in Example 1 were subjected to performance testing. The testing methods conformed to industrial standards, and the results are as follows: pellet compressive strength: 5126 N / pellet; TiO2 content: 39.5%; TFe content: 32.4%; breakage rate: less than 2.1% (measured according to international standard ISO 4700:1996 EN); pellet moisture content: less than 1.2%. Example 2

[0029] The high-strength titanium-containing cold-set pellets of this embodiment have raw material ratios and various indicators that strictly meet the requirements of the invention, as detailed below: The amount of ilmenite added is 60 wt%, the particle size is -200 mesh accounting for 82%, the TiO2 content is 47 wt%, the Fe content is 36 wt%, the raw material particles are uniform and there are no obvious impurities; The coal gangue content is 25 wt%, the particle size is -200 mesh (72%), the loss on ignition is 10 wt%, the SiO2 content is 58 wt%, and the Al2O3 content is 22 wt%. The amount of lime added is 15 wt%, the effective calcium oxide content is 90 wt%, there is no obvious clumping, and after grinding, all of it passes through a 150-mesh sieve. The amount of water added is 15 wt% of the total mass of ilmenite, coal gangue and lime. Deionized water is used, which is highly pure, free of impurities, and meets industrial production standards.

[0030] Its preparation method is as follows: (1) Raw material pretreatment: Weigh ilmenite, coal gangue, and lime, and coarsely crush them to a particle size ≤8mm using a jaw crusher, and then grind them to the specified particle size using a ball mill. Ilmenite -200 mesh accounts for 82%, coal gangue -200 mesh accounts for 72%, and all lime passes through a 150 mesh sieve; during the grinding process, control the moisture content of the three raw materials to ≤2% to avoid clumping, and seal and store them after grinding to prevent moisture absorption and deterioration; (2) Preparation of composite binder: The pretreated coal gangue and lime were put into a double helix mixer. The mixer was started and stirred at a speed of 200 r / min. Deionized water was added while stirring, and the addition speed was controlled at 6 mL / min. Stirring was continued for 10 min to ensure that the coal gangue and lime were fully hydrated and reacted to form a uniform and viscous composite binder. The viscosity of the binder was measured to be 7200 mPa·s using a rotational viscometer (25℃). It was then put into use. (3) Uniform mixing of materials: Add the prepared composite binder to the pretreated ilmenite, adjust the stirring speed to 150 r / min, and continue stirring for 15 min; take online samples to detect the uniformity of mixing during the stirring process to ensure that the ilmenite particles are completely coated by the binder, and finally achieve a uniformity of 91%. After the mixture is qualified, discharge the material. (4) Cold pressing and densification: The uniformly mixed material is fed into a hydraulic briquetting machine, placed into a φ45 mm spherical custom mold, and subjected to a pressure of 25 MPa for cold pressing and holding for 20 seconds; after molding, the briquetting pellets are taken out and the molding density is tested to be 3.0 g / cm³, the surface is smooth and without defects, and the molding is qualified; (5) Room temperature curing: The formed pellets are neatly stacked in the curing room with a spacing of 6 cm between them; the curing environment temperature is controlled at 20 ℃ and the relative humidity at 65% for 7 days; the pellets are turned over once a day during the curing process to ensure uniform curing. The compressive strength of the pellets is tested on the 7th day of curing. Once the standard is met, the pellets can be shipped out.

[0031] The high-strength titanium-containing cold-set pellets prepared in Example 2 were subjected to performance testing. The testing methods conformed to industrial standards, and the results are as follows: pellet compressive strength: 6018 N / pellet; TiO2 content: 34.9%; TFe content: 29.1%; breakage rate: less than 1.8% (measured according to international standard ISO 4700:1996 EN); pellet moisture content: less than 1.0%. Example 3

[0032] The high-strength titanium-containing cold-set pellets of this embodiment have raw material ratios and various indicators that strictly meet the requirements of the invention, as detailed below: The amount of ilmenite added is 80 wt%, the particle size is -200 mesh, accounting for 88%, of which TiO2 content is 49 wt% and Fe content is 35 wt%. The raw material particles are uniform and there are no obvious impurities. The coal gangue content is 10 wt%, the particle size is -200 mesh (78%), the loss on ignition is 12 wt%, the SiO2 content is 53 wt%, and the Al2O3 content is 18 wt%. The amount of lime added is 5 wt%, the effective calcium oxide content is 93%, there is no obvious clumping, and after grinding, all of it passes through a 150-mesh sieve. The water added is 5 wt% of the total mass of ilmenite, coal gangue and lime. Industrial soft water is used, which is free of impurities and corrosive, and the water quality meets industrial production standards.

[0033] Its preparation method is as follows: (1) Raw material pretreatment: Weigh ilmenite, coal gangue, and lime, and coarsely crush them to a particle size ≤10mm using a jaw crusher, and then grind them to the specified particle size using a ball mill. Ilmenite -200 mesh accounts for 88%, coal gangue -200 mesh accounts for 78%, and lime all passes through a 150 mesh sieve; during the grinding process, control the moisture content of the three raw materials to ≤1.8% to avoid agglomeration, and seal them after grinding to prevent moisture absorption; (2) Preparation of composite binder: The pretreated coal gangue and lime were put into a double helix mixer. The mixer was started and stirred at a speed of 100 r / min. While stirring, metered industrial soft water was added at a rate of 4 mL / min. Stirring was continued for 20 min to ensure that the coal gangue and lime were fully hydrated and reacted to form a uniform and viscous composite binder. The viscosity of the binder was measured to be 6000 mPa·s using a rotational viscometer (25 ℃). The binder was then ready for use. (3) Uniform mixing of materials: Add the prepared composite binder to the pretreated ilmenite, adjust the stirring speed to 100 r / min, and continue stirring for 25 min; take online samples to detect the uniformity of mixing during the stirring process to ensure that the ilmenite particles are completely coated by the binder, and finally achieve a uniformity of 93%. After the mixture is qualified, discharge the material. (4) Cold pressing and densification: The uniformly mixed material is fed into a hydraulic briquetting machine, placed into a φ55 mm spherical custom mold, and cold-pressed at 30 MPa for 30 seconds; after molding, the briquetting pellets are taken out and the molding density is tested to be 2.8 g / cm³. The surface is free of cracks and powdering, and the molding is qualified. (5) Room temperature curing: The formed pellets are neatly stacked in the curing room with a spacing of 5 cm between them; the curing environment temperature is controlled at 30 ℃ and the relative humidity is 75% for 4 days; the pellets are turned over once a day during the curing process to ensure uniform curing. The compressive strength of the pellets is tested on the 4th day of curing. Once the standard is met, the pellets can be shipped out.

[0034] The high-strength titanium-containing cold-set pellets prepared in Example 3 were subjected to performance testing. The testing methods conformed to industrial standards, and the results are as follows: pellet compressive strength: 4062 N / pellet; TiO2 content: 44.2%; TFe content: 31.6%; breakage rate: less than 2.5% (measured according to international standard ISO 4700:1996 EN); pellet moisture content: less than 1.1%. Test case

[0035] Titanium-containing pellets were prepared using the schemes published in existing technologies CN 105714109 B and CN 110055406 A, and their strength, compressive strength, and TiO2 content were measured. The results are shown in Table 1.

[0036] Table 1

[0037] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for producing high-strength cold-bonded pellets containing titanium, characterized by, Includes the following steps: (1) Raw material pretreatment: Weigh out ilmenite, coal gangue and lime, grind them separately, and then take water for later use; (2) Preparation of composite binder: Coal gangue and lime are put into a mixing device, and water is added while stirring to make a binder; (3) Material mixing: Mix the binder with ilmenite and stir until homogeneous; (4) Cold pressing: The mixture is placed in a mold and cold pressed to obtain shaped pellets; (5) Room temperature curing: The formed pellets are cured to obtain high-strength titanium-containing cold-cured pellets.

2. The method of claim 1, wherein the high-strength cold-bonded titanium-containing pellets are prepared by the steps of: mixing a titanium-containing material with a binder to form a mixture; and forming the mixture into pellets. The high-strength titanium-containing cold-cured pellets are composed of the following raw materials by mass fraction: 60-80 wt% ilmenite, 10-25 wt% coal gangue, and 5-15 wt% lime; The amount of water used is 5-15 wt% of the total mass of ilmenite, coal gangue, and lime. The water is industrial soft water or deionized water; The industrial soft water conforms to the national standard GB / T1576-2008.

3. The method of claim 1, wherein the high-strength cold-bound pellets containing titanium are prepared by the steps of: In step (1), the proportion of ilmenite ground to pass through a 200-mesh sieve is not less than 80%, the proportion of coal gangue ground to pass through a 200-mesh sieve is not less than 70%, and the lime is ground to pass through a 150-mesh sieve. ​ The moisture content of the ilmenite, coal gangue, and lime is controlled to be ≤2%.

4. The method for preparing high-strength titanium-containing cold-solidified pellets according to claim 1, characterized in that, The stirring speed in step (2) is 100-200 r / min, and the stirring time is 10-20 min; The water is added at a rate of 4-6 mL / min.

5. A method for preparing high-strength titanium-containing cold-solidified pellets according to claim 1 or 4, characterized in that, The room temperature viscosity of the adhesive mentioned in step (2) is 6000-8000 mPa·s.

6. The method for preparing high-strength titanium-containing cold-solidified pellets according to claim 1, characterized in that, The stirring speed in step (3) is 100-150 r / min, the stirring time is 15-25 min, and the mixing uniformity is ≥90%.

7. The method for preparing high-strength titanium-containing cold-solidified pellets according to claim 1, characterized in that, The mold mentioned in step (4) is a custom-made spherical mold with a diameter of φ45-55 mm; The cold pressing is a process of applying 20-30 MPa pressure to cold press and holding the pressure for 20-30 seconds; The molding density of the shaped pellets is ≥2.8 g / cm³.

8. The method for preparing high-strength titanium-containing cold-solidified pellets according to claim 1, characterized in that, The curing process described in step (5) involves curing for 4-7 days in an environment with a temperature of 20-30℃ and a relative humidity of 60-80%.

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