Water-resistant desulfurizer and preparation method thereof

Abstract

The invention discloses a water-resistant desulfurizer and a preparation method thereof, and belongs to the technical field of molten steel smelting, the water-resistant desulfurizer comprises Mg3N2 and modified CaCO3; the modified CaCO3 is prepared by the following steps: preparing a Tris buffer solution, then adding a dopamine hydrochloride aqueous solution with a mass fraction of 1-2%, stirring at a constant speed of 150-200 r / min at room temperature for 2 h, then adding calcium carbonate powder, and dipping for 2 h to prepare the modified CaCO3. According to the invention, Mg3N2 is taken as a main material, Al2O3 and SiO2 are taken as auxiliary materials, modified CaCO3 is taken as a binder, pellets are prepared by adopting a pressing and pelletizing mode, the desulfurizer can be endowed with excellent moisture-proof and water-resistant performance, and when the desulfurizer is used, Mg3N2 is used for decomposing magnesium metal, so that the desulfurizer has extremely strong desulfurization capacity; the calcium carbonate is decomposed into calcium oxide at high temperature to promote magnesium desulfurization, so that the prepared desulfurizer has excellent desulfurization performance.

Description

Technical Field

[0001] The invention relates to the technical field of steel smelting, and in particular to a water-resistant desulfurizing agent and a preparation method thereof. Background Art

[0002] Sulfur in steel is generally considered to be a harmful inclusion, among which the sulfur content has a great impact on the ferromagnetism of silicon steel products. Therefore, developing silicon steel with a lower sulfur content to improve its magnetic conductivity and reduce iron loss is an important direction for optimizing silicon steel products. The silicon steel production process commonly used at this stage is: converter-RH furnace-continuous casting, among which the desulfurization process is carried out in the middle and later stages of the RH furnace. In the current desulfurization process, due to the limitations of the performance of conventional desulfurizers themselves, there are usually problems such as a large amount of desulfurizer added, a long desulfurization time required, and a large temperature drop, making the desulfurization process a restrictive link in silicon steel production and technology. Therefore, it is necessary to develop a more effective RH furnace desulfurizer to solve the above problems. Summary of the invention

[0003] In order to solve the above technical problems, the present invention provides a water-resistant desulfurizer and a preparation method thereof.

[0004] The purpose of the present invention can be achieved through the following technical solutions: A water-resistant desulfurizer comprising Mg3N2 and modified CaCO3; The modified CaCO3 is prepared by the following steps: Add Tris particles into deionized water, stir uniformly for 15 minutes, then adjust the pH of the system to 8.5 to prepare Tris buffer, then add 1-2% dopamine hydrochloride aqueous solution, stir uniformly at 150-200r / min for 2 hours at room temperature, then add calcium carbonate powder, soak for 2 hours to prepare modified CaCO3, and control the usage ratio of Tris buffer, dopamine hydrochloride aqueous solution, calcium carbonate powder and deionized water to 4-6g:300-500mL:1-1.2g:500mL.

[0005] Tris buffer is used as a buffer and calcium carbonate powder is added. Dopamine hydrochloride can copolymerize on the surface of calcium carbonate to form polydopamine, which has a certain adhesion effect.

[0006] Furthermore, it also includes SiO2 and Al2O3.

[0007] Furthermore, the desulfurizing agent can be applied to a vacuum induction furnace, a RH refining furnace and a LF refining furnace.

[0008] Furthermore, when the desulfurizer is used to desulfurize the molten steel, the amount of the desulfurizer added is 5-10 kg / ton of molten metal, and the desulfurization stage time is 10-25 minutes.

[0009] A method for preparing a water-resistant desulfurizer comprises the following steps: The first step is to add 5-8 parts of Mg3N2, 1-5 parts of SiO2, 20-30 parts of Al2O3 and 30-50 parts of modified CaCO3 by weight into a crusher for crushing until the particle size is less than 0.1 mm, and then use a double-roll ball press to press into pellets; The second step is to dry, package and set aside the pressed pellets.

[0010] Furthermore, the pressure of the roller ball press is ≥500kg / cm 2 The particle size of the pressed ball is 10-30mm.

[0011] Furthermore, in the second step, the drying temperature is 130-150° C., and the drying time is 2-4 hours.

[0012] Beneficial effects of the present invention: The present invention prepares a desulfurizer for a refining furnace, which uses Mg3N2 as a raw material, Al2O3 and SiO2 as auxiliary materials, and modified CaCO3 as a binder. The pellets are made by pressing into balls, which can give the desulfurizer excellent moisture-proof and water-resistant properties. The modified CaCO3 has a certain adhesion effect through polydopamine formed by copolymerization on the surface, which can facilitate agglomeration and better protect Mg3N2. When the desulfurizer is used, Mg3N2 decomposes metal magnesium to have a strong desulfurization ability. The nitrogen generated by the decomposition can increase the desulfurization reaction interface and improve the desulfurization ability of magnesium. Calcium carbonate decomposes into calcium oxide at high temperature to promote magnesium desulfurization. In addition, the problem of calcium oxide being easy to get wet can be prevented by not directly using calcium oxide. The formed polydopamine can be decomposed into carbon and nitrogen elements in molten steel, which has no effect on the molten steel. Therefore, the desulfurizer prepared by the present application has excellent desulfurization performance. DETAILED DESCRIPTION

[0013] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0014] Example 1 A water-resistant desulfurizer, comprising Mg3N2 and modified CaCO3, and further comprising SiO2 and Al2O3; The modified CaCO3 is prepared by the following steps: Add Tris particles into deionized water, stir uniformly for 15 minutes, then adjust the pH of the system to 8.5 to prepare Tris buffer, then add 1-2% dopamine hydrochloride aqueous solution, stir uniformly at 150r / min at room temperature for 2 hours, then add calcium carbonate powder, soak for 2 hours to prepare modified CaCO3, and control the dosage ratio of Tris buffer, dopamine hydrochloride aqueous solution, calcium carbonate powder and deionized water to 4g:300-500mL:1g:500mL.

[0015] The desulfurizing agent can be applied to a vacuum induction furnace, a RH refining furnace and a LF refining furnace.

[0016] When the desulfurizer is used to desulfurize the molten steel, the amount of the desulfurizer added is 5 kg / ton of molten metal, and the desulfurization stage time is 10 minutes.

[0017] A method for preparing a water-resistant desulfurizer comprises the following steps: The first step is to add 5 parts of Mg3N2, 1 part of SiO2, 20 parts of Al2O3 and 30 parts of modified CaCO3 by weight into a crusher for crushing until the particle size is less than 0.1 mm, and then use a roller press to press it into pellets; The second step is to dry, package and set aside the pressed pellets.

[0018] The pressure of the roller ball press is ≥500kg / cm 2 The pellet size is 10mm.

[0019] In the second step, the drying temperature is 130°C and the drying time is 2h.

[0020] Example 2 A water-resistant desulfurizer, comprising Mg3N2 and modified CaCO3, and further comprising SiO2 and Al2O3; The modified CaCO3 is prepared by the following steps: Add Tris particles into deionized water, stir uniformly for 15 minutes, then adjust the pH of the system to 8.5 to prepare Tris buffer, then add 1-2% by mass dopamine hydrochloride aqueous solution, stir uniformly at 150r / min at room temperature for 2 hours, then add calcium carbonate powder, soak for 2 hours to prepare modified CaCO3, and control the usage ratio of Tris buffer, dopamine hydrochloride aqueous solution, calcium carbonate powder and deionized water to 5g:400mL:1g:500mL.

[0021] The desulfurizing agent can be applied to a vacuum induction furnace, a RH refining furnace and a LF refining furnace.

[0022] When the desulfurizer is used to desulfurize the molten steel, the amount of the desulfurizer added is 6 kg / ton of molten metal, and the desulfurization stage time is 115 minutes.

[0023] A method for preparing a water-resistant desulfurizer comprises the following steps: The first step is to add 6 parts of Mg3N2, 3 parts of SiO2, 25 parts of Al2O3 and 40 parts of modified CaCO3 by weight into a crusher for crushing until the particle size is less than 0.1 mm, and then use a double-roll ball press to press into pellets; The second step is to dry, package and set aside the pressed pellets.

[0024] The pressure of the roller ball press is ≥500kg / cm 2 The particle size of the pressed ball is 20mm.

[0025] In the second step, the drying temperature is 140°C and the drying time is 3 h.

[0026] Example 3 A water-resistant desulfurizer, comprising Mg3N2 and modified CaCO3, and further comprising SiO2 and Al2O3; The modified CaCO3 is prepared by the following steps: Add Tris particles into deionized water, stir uniformly for 15 minutes, then adjust the pH of the system to 8.5 to prepare Tris buffer, then add 1-2% by mass dopamine hydrochloride aqueous solution, stir uniformly at 180r / min at room temperature for 2 hours, then add calcium carbonate powder, soak for 2 hours to prepare modified CaCO3, and control the usage ratio of Tris buffer, dopamine hydrochloride aqueous solution, calcium carbonate powder and deionized water to 5g:400mL:1.2g:500mL.

[0027] The desulfurizing agent can be applied to a vacuum induction furnace, a RH refining furnace and a LF refining furnace.

[0028] When the desulfurizer is used to desulfurize the molten steel, the amount of the desulfurizer added is 8 kg / ton of molten metal, and the desulfurization stage time is 20 minutes.

[0029] A method for preparing a water-resistant desulfurizer comprises the following steps: The first step is to add 7 parts of Mg3N2, 4 parts of SiO2, 28 parts of Al2O3 and 45 parts of modified CaCO3 by weight into a crusher for crushing until the particle size is less than 0.1 mm, and then use a roller press to press it into pellets; The second step is to dry, package and set aside the pressed pellets.

[0030] The pressure of the roller ball press is ≥500kg / cm 2 The pellet size is 30mm.

[0031] In the second step, the drying temperature is 1150°C and the drying time is 4 hours.

[0032] Example 4 A water-resistant desulfurizer, comprising Mg3N2 and modified CaCO3, and further comprising SiO2 and Al2O3; The modified CaCO3 is prepared by the following steps: Add Tris particles into deionized water, stir uniformly for 15 minutes, then adjust the pH of the system to 8.5 to prepare Tris buffer, then add 2% by mass dopamine hydrochloride aqueous solution, stir uniformly at 150-200r / min at room temperature for 2 hours, then add calcium carbonate powder, soak for 2 hours to prepare modified CaCO3, and control the usage ratio of Tris buffer, dopamine hydrochloride aqueous solution, calcium carbonate powder and deionized water to 6g:500mL:1.2g:500mL.

[0033] The desulfurizing agent can be applied to a vacuum induction furnace, a RH refining furnace and a LF refining furnace.

[0034] When the desulfurizer is used to desulfurize the molten steel, the amount of the desulfurizer added is 10 kg / ton of molten metal, and the desulfurization stage time is 25 minutes.

[0035] A method for preparing a water-resistant desulfurizer comprises the following steps: The first step is to add 8 parts of Mg3N2, 5 parts of SiO2, 30 parts of Al2O3 and 50 parts of modified CaCO3 by weight into a crusher for crushing until the particle size is less than 0.1 mm, and then use a roller press to press it into pellets; The second step is to dry, package and set aside the pressed pellets.

[0036] The pressure of the roller ball press is ≥500kg / cm 2 The pellet size is 30mm.

[0037] In the second step, the drying temperature is 150°C and the drying time is 4 hours.

[0038] Comparative Example 1 This comparative example is an existing desulfurizer, a desulfurizer for RH furnace, including 12CaO·7Al2O3 phase and 11CaO·7Al2O3·CaF2 phase. In the RH furnace desulfurizer, the sum of the mass percentages of the 12CaO·7Al2O3 phase and the 11CaO·7Al2O3·CaF2 phase is more than 30%.

[0039] Comparative Example 2 The preparation method of the desulfurizing agent in this comparative example is as follows: (1) Take 80 parts of CaO and perform passivation treatment. The process is as follows: a. Spraying: Mix 80 parts of water and 80 parts of CaO in a container, then spray the additive (5 parts of cyclodimethyl silicone oil, hydraulic oil, and soybean oil) on the surface of the lime, and spray and mix evenly by rotating at the same time; The raw material parameters are as follows: lime containing CaO≥70-88%, S≤0.05%, activity≥250ml / 4N (HCl), loss on ignition<0.5%, angle of repose<35, passivation treatment, and particle size of 0.01-0.1mm.

[0040] b. Insulation: Insulate at 100-1050℃ for 4 minutes to allow the additive to boil and completely volatilize and be adsorbed by slaked lime to form a protective film; (2) Mix the following ingredients with the material prepared in step (1) and perform drying pretreatment: C 5 copies Mg 5 parts Zn 5 parts Calcium aluminate 5 parts 5 parts of soda ash.

[0041] Then pour the passivation solution into the above materials, stir until the materials are dry, cool naturally, grind to make a powdery product. The passivation solution is magnesium chloride, the weight is 0.6 parts, and the concentration of magnesium chloride solution is 65g / L.

[0042] The raw materials used are: charcoal containing C≥90%; passivated magnesium powder containing TMg≥85% with a particle size of 0.1-0.5mm; sodium carbonate with a particle size of 0.01mm.

[0043] (3) Place in a moisture-proof container or bag and seal for later use.

[0044] The performance of the desulfurizers prepared in Examples 1-4 and Comparative Examples 1-2 was tested, and the results are shown in Table 1 below: ; It can be seen from Table 1 above that the desulfurizers prepared in Examples 1-4 of the present invention have excellent desulfurization performance.

[0045] The above contents are merely examples and explanations of the concept of the present invention. The technicians in this technical field may make various modifications or additions to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the concept of the invention or exceed the scope defined by the claims, they should all fall within the protection scope of the present invention.

Claims

1. A water-resistant desulfurizer, characterized in that: Includes Mg3N2 and modified CaCO3; The modified CaCO3 is prepared by the following steps: Tris particles were added into deionized water, and the pH of the system was adjusted to 8.5 after being stirred at a constant speed for 15 minutes to prepare Tris buffer. Then, a 1-2% by mass aqueous solution of dopamine hydrochloride was added, and the mixture was stirred at a constant speed of 150-200 r / min at room temperature for 2 hours. Then, calcium carbonate powder was added and immersed for 2 hours to prepare modified CaCO3.

2. A water-resistant desulfurizer according to claim 1, characterized in that: The dosage ratio of Tris buffer, dopamine hydrochloride aqueous solution, calcium carbonate powder and deionized water is controlled to be 4-6 g: 300-500 mL: 1-1.2 g: 500 mL.

3. A water-resistant desulfurizer according to claim 1, characterized in that: Also includes SiO2 and Al2O3.

4. A water-resistant desulfurizer according to claim 1, characterized in that: The desulfurizing agent can be applied to a vacuum induction furnace, a RH refining furnace and a LF refining furnace.

5. A water-resistant desulfurizer according to claim 1, characterized in that: When the desulfurizing agent is used to desulfurize the molten steel, the amount of the desulfurizing agent added is 5-10 kg / ton of molten metal, and the desulfurization stage time is 10-25 minutes.

6. The method for preparing a water-resistant desulfurizer according to claim 3, characterized in that: The steps include: The first step is to add 5-8 parts of Mg3N2, 1-5 parts of SiO2, 20-30 parts of Al2O3 and 30-50 parts of modified CaCO3 by weight into a crusher for crushing until the particle size is less than 0.1 mm, and then use a double-roll ball press to press into pellets; The second step is to dry, package and set aside the pressed pellets.

7. The method for preparing a water-resistant desulfurizer according to claim 6, characterized in that: The pressure of the roller ball press is ≥500kg / cm 2 The particle size of the pressed ball is 10-30mm.

8. The method for preparing a water-resistant desulfurizer according to claim 6, characterized in that: In the second step, the drying temperature is 130-150°C and the drying time is 2-4h.