Preparation method of ferrotitanium nitride for microalloying technology

Abstract

The invention relates to the technical field of ferrotitanium nitride, and discloses a preparation method of ferrotitanium nitride for a microalloying technology, which comprises the following steps: preparing a titanium-containing raw material, an iron-containing raw material and a carbonaceous raw material for grinding according to the molar ratio of Ti: Fe = (0.2-6): 1 and the molar ratio of C: O = 1: (1-2); adding a binder into the ground raw materials, mixing, and pressing into raw material balls; the raw material balls are placed in a graphite crucible and fired in multiple temperature zones in a pushed slab kiln in sequence to obtain the ferrotitanium nitride, and the temperatures of the multiple temperature zones are sequentially increased and then decreased. The iron element with a large proportion is introduced, the iron element has a very good catalytic effect, and combination of nitrogen and titanium can be accelerated, so that the nitriding time is remarkably shortened, the reaction temperature is reduced, and the alloy density is improved.

Description

Technical Field

[0001] The invention relates to the technical field of titanium ferronitride, and in particular to a preparation method of titanium ferronitride used in microalloying technology. Background Art

[0002] Microalloying technology is an effective technical means to produce high-strength steel, earthquake-resistant steel, and corrosion-resistant steel. Ti is one of the commonly used microalloying elements. Adding titanium nitride alloys to molten steel can form fine dispersed titanium nitride (TiN) particles. These particles play a role in pinning grain boundaries in steel, which can effectively inhibit the growth of grains, refine the grain structure of steel, increase the grain boundary area, and improve the strength and toughness of steel. At present, the preparation methods of titanium nitride alloys include carbon thermal reduction nitriding, mechanical ball milling, high-temperature self-propagating method, microwave synthesis method, etc. Among them, although the carbon thermal reduction nitriding method can achieve large-scale preparation, the reaction temperature is high (1200-1500℃) and the reaction time is long 5-20h, resulting in high production cost of titanium nitride. Mechanical ball milling, high-temperature self-propagating method, microwave synthesis method and other methods cannot achieve large-scale preparation and are difficult to apply industrially. Microalloying technology requires that the density of the alloy is as high as possible, which is conducive to the alloy sinking into the molten steel and avoiding the waste of microalloying elements due to oxidation. Titanium nitride has low density (apparent density is less than 3.1g / cm 3 ), therefore increasing the density of titanium nitride series alloys is helpful for their application in the field of microalloying technology.

[0003] Therefore, there is a need in the prior art for an improved method for preparing titanium ferronitride for microalloying technology. Summary of the invention

[0004] In view of this, the purpose of an embodiment of the present invention is to propose a preparation method of titanium iron nitride for microalloying technology, by introducing a larger proportion of iron-containing raw materials into the raw materials, by adjusting the proportion of iron-containing raw materials, reducing the nitriding time, lowering the reaction temperature and improving the density of the alloy.

[0005] Based on the above purpose, an embodiment of the present invention provides a method for preparing titanium ferronitride for microalloying technology, comprising the following steps: Prepare titanium-containing raw materials, iron-containing raw materials, and carbonaceous raw materials for grinding. In terms of molar ratio, the raw material ratio is Ti:Fe=(0.2~6):1, C:O=1:(1~2); Adding a binder to the ground raw materials, mixing them and pressing them into raw material balls; The raw material ball is placed in a graphite crucible and fired in a plurality of temperature zones in a push plate kiln in sequence to obtain titanium nitride, and the temperatures in the plurality of temperature zones are changed in sequence to first increase and then decrease.

[0006] In some embodiments, the titanium-containing raw material includes one of titanium dioxide, high-titanium slag, titanium concentrate, 40 ferrotitanium, 70 ferrotitanium, and sponge titanium; the iron-containing raw material includes one of iron powder, ferrous oxide, and ferric oxide; and the carbonaceous raw material includes one of graphite and carbon black.

[0007] In some embodiments, the raw material is ground to -200 mesh during pulverization.

[0008] In some embodiments, the amount of binder added is 7% to 12% of the total amount of the titanium-containing raw material, the iron-containing raw material, and the carbonaceous raw material.

[0009] In some embodiments, the binder includes any one of water, a mixed slurry of water and starch, and a mixed slurry of water and glucose.

[0010] In some embodiments, the ground raw materials are mixed with the binder in a wet mixer for 2 to 3 hours.

[0011] In some embodiments, the push plate kiln includes three temperature zones, the temperature range of the first temperature zone is 100-800°C, the maximum temperature of the second temperature zone is 1200-1400°C, and the temperature of the third temperature zone drops from the maximum temperature to room temperature.

[0012] In some embodiments, the heating time in the first temperature zone is 1 to 5 hours, the heating time in the second temperature zone is 3 to 10 hours, and the cooling time in the third temperature zone is 2 to 5 hours.

[0013] In some embodiments, the nitrogen pressure in the push plate kiln is 20-150 Pa, and the nitrogen flow rate is 1.5 L / min-15 L / min.

[0014] On the other hand, the present invention also provides a titanium ferronitride. Using the method as described above, in the titanium ferronitride, the mass fraction ratio of nitrogen to titanium is 0.18-0.27, the mass percentage of C and O is less than 1%, the mass percentage of S and P is less than 0.04%, and the density of the alloy is 3.8-5.7 g / cm 3 .

[0015] The present invention has at least the following beneficial technical effects: The present invention provides a method for preparing titanium ferronitride for microalloying technology. In the traditional preparation process of titanium ferronitride, the nitriding step often takes a long time to ensure that the nitrogen element fully penetrates and reacts with the titanium element. By introducing a large proportion of iron-containing raw materials and accurately controlling the proportion, the diffusion rate of nitrogen in the alloy can be accelerated. The iron element has a good catalytic effect and can accelerate the combination of nitrogen and titanium, thereby significantly shortening the nitriding time, which not only improves production efficiency but also reduces energy consumption.

[0016] In addition, due to the introduction of iron-containing raw materials and the proportion control, the reaction kinetics inside the alloy is optimized. At a lower temperature, the iron element acts as a catalyst to promote the reaction of nitrogen and titanium, so that the entire nitriding process can be carried out at a lower temperature. The method of the present invention reduces the requirements for production equipment, reduces the safety hazards caused by high-temperature operation, and also reduces energy consumption and production costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention. For ordinary technicians in this field, other embodiments can be obtained based on these drawings without paying creative work.

[0018] Figure 1 This is a schematic diagram of an embodiment of a method for preparing titanium ferronitride for microalloying technology provided by the present invention. DETAILED DESCRIPTION

[0019] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the embodiments of the present invention are further described in detail below in combination with specific embodiments and with reference to the accompanying drawings.

[0020] The terms "including" and "having" and any variations thereof in the specification and claims of the present invention and the above-mentioned drawings are intended to cover non-exclusive inclusions; the terms "first", "second", etc. in the specification and claims of the present invention or the above-mentioned drawings are used to distinguish different objects rather than to describe a specific order. "Multiple" means two or more, unless otherwise clearly and specifically defined.

[0021] In addition, reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present invention. The appearance of the phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0022] like Figure 1 The method for preparing titanium ferronitride for microalloying technology provided by the present invention comprises the following steps: S1 prepares titanium-containing raw materials, iron-containing raw materials, and carbonaceous raw materials for grinding. In terms of molar ratio, the raw material ratio is Ti:Fe=(0.2~6):1, C:O=1:(1~2); S2: adding a binder to the ground raw material, mixing and pressing into raw material balls; S3: placing the raw material ball in a graphite crucible and firing it in a plurality of temperature zones in a push plate kiln in sequence to obtain titanium nitride, wherein the temperatures in the plurality of temperature zones are changed in sequence to first increase and then decrease.

[0023] Further, in S1, the titanium-containing raw material includes one of titanium dioxide, high-titanium slag, titanium concentrate, 40 ferrotitanium, 70 ferrotitanium, and sponge titanium; the iron-containing raw material includes one of iron powder, ferrous oxide, and ferric oxide; and the carbonaceous raw material includes one of graphite and carbon black.

[0024] Furthermore, in S2, the raw material is ground to -200 mesh during grinding, and the ground material can significantly increase the surface area of ​​the raw material, making the raw material particles finer and more uniform. This is conducive to the full contact and mixing of the raw materials in the subsequent reaction process, thereby improving the reaction efficiency.

[0025] Furthermore, the ground raw materials are mixed with a binder in a wet mixer for 2 to 3 hours. The wet mixing method can enable better contact and mixing between the raw material particles, thereby improving the mixing uniformity, and uniformly mixing a variety of raw materials together to avoid the situation where the local raw material concentration is too high or too low during the reaction, thereby ensuring the consistency and stability of the reaction.

[0026] In some embodiments, the amount of the binder added is 7% to 12% of the total amount of the titanium-containing raw material, the iron-containing raw material, and the carbonaceous raw material. The binder includes any one of water, a mixed slurry of water and starch, and a mixed slurry of water and glucose.

[0027] Furthermore, in S2, the mixed material is pressed in a ball press to obtain raw material balls. By ball pressing, the loose wet mixed raw materials can be compressed into dense spheres, thereby significantly improving the packing density of the raw materials. This is conducive to the raw materials being able to be more closely packed together in the subsequent firing process, reducing gaps and improving reaction efficiency. The formation of raw material balls makes the contact area between the reactants relatively concentrated, which is conducive to the transfer of heat and substances.

[0028] Furthermore, in S3, the push plate kiln includes three temperature zones, the first temperature zone is a low temperature drying zone, the second temperature zone is a high temperature nitriding zone, and the third temperature zone is a low temperature cooling zone. In the low temperature drying zone, the raw material ball is slowly heated to remove internal moisture, reducing cracks or deformation caused by too fast evaporation of water, thereby improving the stability of the raw material ball. The high temperature nitriding zone provides a sufficient temperature environment to allow certain elements in the raw material ball to react with nitrogen to form the required nitride. The raw material ball quickly enters the low temperature cooling zone after the high temperature nitriding zone, which can effectively reduce the temperature gradient, reduce the thermal stress caused by rapid cooling, and avoid product cracking or deformation.

[0029] Among them, the temperature range of the first temperature zone is 100~800℃, the maximum temperature of the second temperature zone is 1200~1400℃, and in some embodiments, the maximum temperature of the second temperature zone can be 1200, 1250, 1300, 1400℃. The temperature of the third temperature zone is reduced from the highest temperature obtained in the second temperature zone to room temperature. Specifically, the heating time in the first temperature zone is 1~5h, the heating time in the second temperature zone is 3~10h, and the cooling time in the third temperature zone is 2~5h. The nitrogen pressure in the push plate kiln is 20~150Pa, and the nitrogen flow rate is 1.5L / min~15L / min.

[0030] The present invention also provides titanium ferronitride prepared by the above method, wherein the mass fraction ratio of nitrogen to titanium is 0.18-0.27, the mass percentage of C and O is less than 1%, the mass percentage of S and P is less than 0.04%, and the density of the alloy is 3.8-5.7 g / cm 3 .

[0031] The present invention will be further explained below in conjunction with specific embodiments.

[0032] Example 1 120 kg of titanium dioxide, 30 kg of iron powder and 45 kg of graphite powder were mixed and ground to -200 mesh. 16 kg of water was added as a binder and wet mixed for 2 hours. After being pressed by a ball press under a pressure of 8 MPa, the prepared ball was a biconical structure with thin sides and thick middle, of which the thickest part was 26 mm thick, 44 mm long and 36 mm wide. The ball was loaded into a graphite crucible and sent to a push plate kiln for firing. The push plate kiln was mainly divided into three temperature zones. Zone 1 was a low-temperature preheating zone with a temperature of 100-800 ° C and a reaction time of 3 hours. Zone 2 was a high-temperature nitriding zone with a maximum temperature of 1200 ° C and a reaction time of 10 hours. Zone 3 was a low-temperature cooling zone, cooled to room temperature, and the cooling time was 2 hours. A nitrogen atmosphere was introduced into the push plate kiln with a nitrogen flow rate of 10 L / min. Titanium ferronitride was obtained by reaction. The product after the reaction is calculated by mass percentage, wherein Ti is 59%, Fe is 23%, N is 15%, C is 0.8%, O is 0.9%, S and P are less than 0.04%, and the rest are impurities.

[0033] Example 2 120 kg of high titanium slag, 19 kg of ferrous oxide, and 40 kg of graphite powder were mixed and ground to -200 mesh. 13 kg of water and starch mixture were added as a binder and wet mixed for 2 hours. After being pressed by a ball press under a pressure of 8 MPa, the prepared ball is a biconical structure with thin sides and thick middle, of which the thickest part is 26 mm thick, 44 mm long, and 36 mm wide. The ball was loaded into a graphite crucible and sent to a push plate kiln for firing. The push plate kiln is mainly divided into three areas. Area 1 is a low-temperature preheating area with a temperature of 100-800 ° C and a reaction time of 3 hours. Area 2 is a high-temperature nitriding area with a maximum temperature of 1400 ° C and a reaction time of 5 hours. Area 3 is a low-temperature cooling area, cooled to room temperature, and the cooling time is 3 hours. A nitrogen atmosphere is introduced into the push plate kiln, and the nitrogen flow rate is 8 L / min. Titanium ferronitride is obtained by reaction. The product after the reaction is calculated by mass percentage, wherein Ti is 56%, Fe is 24%, N is 16%, C is 0.9%, O is 0.88%, S and P are less than 0.04%, and the rest are impurities.

[0034] Example 3 120 kg of titanium concentrate and 35 kg of graphite powder were mixed and ground to -200 mesh. 13 kg of water and starch mixture was added as a binder and wet mixed for 2 hours. After being pressed by a ball press under a pressure of 8 MPa, the prepared ball was a biconical structure with thin sides and thick middle, of which the thickest part was 26 mm thick, 44 mm long and 36 mm wide. The ball was loaded into a graphite crucible and sent to a push plate kiln for firing. The push plate kiln was mainly divided into three areas. Area 1 was a low-temperature preheating area with a temperature of 100-800 ° C and a reaction time of 3 hours. Area 2 was a high-temperature nitriding area with a maximum temperature of 1300 ° C and a reaction time of 8 hours. Area 3 was a low-temperature cooling area, cooled to room temperature, and the cooling time was 2.5 hours. A nitrogen atmosphere was introduced into the push plate kiln with a nitrogen flow rate of 8 L / min. Titanium ferronitride was obtained by reaction. The product after the reaction is calculated by mass percentage, wherein Ti is 40%, Fe is 46%, N is 10.5%, C is 0.9%, O is 0.88%, S and P are less than 0.04%, and the rest are impurities.

[0035] It is proved in the examples that the introduction of iron has a significant effect on improving the nitriding efficiency of titanium-iron nitride at a relatively low temperature stage of 1200-1350°C. Under the same temperature, reaction time and N2 flow conditions, the nitrogen content of the alloy containing iron raw materials is about twice that of the alloy without iron. There is almost no effect on the nitriding efficiency at a high temperature of 1400-1550°C. This shows that the introduction of iron-containing raw materials helps to lower the reaction temperature and shorten the reaction time. Carbonaceous raw materials have a greater impact on the residual carbon of titanium-iron nitride. If the carbon content is ≥30%, the free carbon content in the product will increase; if the carbon content is <23%, the residual oxygen in the product will be high.

[0036] The present invention provides a preparation method of titanium ferronitride for microalloying technology, by introducing a large proportion of Fe element, regulating the proportion of iron-containing raw materials, reducing nitriding time, reducing reaction temperature and improving alloy density. In the preparation process of traditional titanium ferronitride, the nitriding step often takes a long time to ensure that the nitrogen element fully penetrates and reacts with the titanium element. By introducing a large proportion of iron-containing raw materials and accurately regulating their proportions, the diffusion rate of nitrogen in the alloy can be accelerated. The iron element has a good catalytic effect and can accelerate the combination of nitrogen and titanium, thereby significantly shortening the nitriding time. This not only improves production efficiency, but also reduces energy consumption. Due to the introduction of iron-containing raw materials and proportion regulation, the reaction kinetics inside the alloy is optimized. At a lower temperature, the iron element, as a catalyst, promotes the reaction of nitrogen and titanium, so that the entire nitriding process can be carried out at a lower temperature. This reduces the requirements for production equipment, reduces the safety hazards caused by high-temperature operation, and also reduces energy consumption and production costs.

[0037] The above are exemplary embodiments disclosed in the present invention, but it should be noted that various changes and modifications may be made without departing from the scope disclosed in the embodiments of the present invention as defined in the claims. The functions, steps and / or actions of the method claims according to the disclosed embodiments described herein do not need to be performed in any particular order. In addition, although the elements disclosed in the embodiments of the present invention may be described or required in individual form, they may also be understood as multiple unless explicitly limited to the singular.

[0038] It should be understood that, as used herein, the singular forms "a", "an" are intended to include the plural forms as well, unless the context clearly supports an exception. It should also be understood that, as used herein, "and / or" refers to any and all possible combinations including one or more of the associated listed items.

[0039] The serial numbers of the embodiments disclosed in the above embodiments of the present invention are only for description and do not represent the advantages or disadvantages of the embodiments.

[0040] A person skilled in the art should understand that the discussion of any of the above embodiments is only exemplary and is not intended to imply that the scope of the disclosure of the embodiments of the present invention (including the claims) is limited to these examples; under the concept of the embodiments of the present invention, the technical features in the above embodiments or different embodiments can also be combined, and there are many other changes in different aspects of the above embodiments of the present invention, which are not provided in detail for the sake of simplicity. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the embodiments of the present invention should be included in the protection scope of the embodiments of the present invention.

Claims

1. A method for preparing titanium ferronitride for microalloying technology, characterized in that: include: Prepare titanium-containing raw materials, iron-containing raw materials, and carbonaceous raw materials for grinding. In terms of molar ratio, the raw material ratio is Ti:Fe=(0.2~6):1, C:O=1:(1~2); Adding a binder to the ground raw materials, mixing them and pressing them into raw material balls; The raw material balls are placed in a graphite crucible and fired in a plurality of temperature zones in a push plate kiln in sequence to obtain titanium iron nitride, wherein the temperatures of the plurality of temperature zones are sequentially changed to first increase and then decrease.

2. The method for preparing titanium ferronitride for microalloying technology according to claim 1, characterized in that: The titanium-containing raw material includes one of titanium dioxide, high-titanium slag, titanium concentrate, 40 ferrotitanium, 70 ferrotitanium, and sponge titanium; the iron-containing raw material includes one of iron powder, ferrous oxide, and ferric oxide; and the carbonaceous raw material includes one of graphite and carbon black.

3. The method for preparing titanium ferronitride for microalloying technology according to claim 1, characterized in that: When grinding, grind the raw material to -200 mesh.

4. The method for preparing titanium ferronitride for microalloying technology according to claim 1, characterized in that: The added amount of the binder is 7% to 12% of the total amount of the titanium-containing raw material, the iron-containing raw material, and the carbonaceous raw material.

5. The method for preparing titanium ferronitride for microalloying technology according to claim 1, characterized in that: The binder includes any one of water, a mixture of water and starch, and a mixture of water and glucose.

6. The method for preparing titanium ferronitride for microalloying technology according to claim 1, characterized in that: The ground raw materials and the binder are mixed in a wet mixer for 2h~3h.

7. The method for preparing titanium ferronitride for microalloying technology according to claim 1, characterized in that: The push plate kiln comprises three temperature zones, the temperature range of the first temperature zone is 100-800° C., the highest temperature of the second temperature zone is 1200-1400° C., and the temperature of the third temperature zone drops from the highest temperature to room temperature.

8. The method for efficiently preparing titanium ferronitride by carbothermal reduction according to claim 7, characterized in that: The heating time in the first temperature zone is 1 to 5 hours, the heating time in the second temperature zone is 3 to 10 hours, and the cooling time in the third temperature zone is 2 to 5 hours.

9. The method for efficiently preparing titanium ferronitride by carbothermal reduction according to claim 1, characterized in that: The nitrogen pressure in the push plate kiln is 20-150 Pa, and the nitrogen flow rate is 1.5 L / min-15 L / min.

10. Titanium ferronitride, prepared by the method according to any one of claims 1 to 9, characterized in that: In titanium ferronitride, the mass fraction ratio of nitrogen to titanium is 0.18~0.27, the mass percentage of C and O is less than 1%, the mass percentage of S and P is less than 0.04%, and the density of the alloy is 3.8~5.7g / cm 3 .

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