Preparation method of macrocrystalline fused magnesite

Abstract

The invention relates to the technical field of preparation of fused magnesite, in particular to a preparation method of macrocrystalline fused magnesite, which comprises the following steps: 1) preparing magnesite with MgO content of more than 45%, and grinding the magnesite to prepare a material with granularity of less than or equal to 3mm; (2) feeding the materials in the step (1) into a light burning kiln to be calcined, and controlling the temperature to be 800-1000 DEG C and the time to be 3-5 hours; after the calcination is finished, crushing and grinding the obtained product to 200-300 meshes to obtain high-activity MgO powder; and (3) adding graphite powder into the high-activity MgO powder as a reducing agent, uniformly stirring, pressing into balls, continuously electrifying and smelting for 5-8 hours in an all 3500 KVA electric melting electric arc furnace at the temperature of 3000-3500 DEG C, and slowly cooling after the reaction is completed to obtain the oversized crystallized magnesia. According to the method, the graphite powder is added as a reducing agent, and the high-power electric smelting arc furnace is combined for high-temperature smelting, so that the energy consumption is reduced, and meanwhile, the high-quality macrocrystalline fused magnesite is obtained.

Description

Technical Field

[0001] The invention relates to the technical field of preparing fused magnesia, in particular to a method for preparing large-crystal fused magnesia. Background Art

[0002] Magnesia raw materials are widely used in alkaline refractory materials because of their good resistance to alkaline slag erosion. The main processes for producing magnesia are sintering and electrofusion. Ordinary magnesia, mid-range magnesia and high-purity magnesia can be prepared by sintering, and ordinary fused magnesia and large-crystal fused magnesia can be obtained by electrofusion. Among them, large-crystal fused magnesia has high purity, large crystal grains, dense structure, strong slag resistance, and good thermal shock stability. It is a high-end product and is widely used in metallurgy, chemical industry, national defense, scientific research, aerospace and other fields.

[0003] In order to obtain large-crystal fused magnesia with higher purity and larger grain size, the existing process simply continuously increases the fusion time and extends the insulation time. This approach consumes more electricity, and long-term smelting will produce more CO2 and dust to pollute the environment. Summary of the invention

[0004] In order to overcome the defects of the prior art, the present invention provides a method for preparing large-crystal fused magnesia. The method adds graphite powder as a reducing agent and combines a high-power electric melting arc furnace for high-temperature smelting to reduce energy consumption while obtaining high-quality large-crystal fused magnesia.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A method for preparing large-crystal fused magnesia comprises the following steps:

[0007] 1) preparing magnesite with a MgO content exceeding 45%, and grinding the magnesite ore to produce a material with a particle size of ≤3 mm;

[0008] 2) feeding the material of step 1) into a light calcining kiln for calcination at a temperature of 800-1000° C. for 3-5 hours; after calcination, grinding the obtained product to 200-300 mesh to obtain a high-activity MgO powder;

[0009] 3) adding graphite powder as a reducing agent to the high-activity MgO powder, stirring evenly and pressing into balls, placing in a 3500KVA electric melting arc furnace and continuously smelting at 3000-3500°C for 5-8 hours, and slowly cooling after the reaction is complete to obtain super-large crystalline magnesia.

[0010] In the step 2), during the heating process of the material in the light-firing kiln, a sodium carbonate solution is evenly added, the concentration of the sodium carbonate solution is 12-15%, and the amount added is 6-8% of the weight of the material.

[0011] The graphite powder has a particle size of 200 meshes and an addition amount of 2-4% of the weight of the high-activity MgO powder.

[0012] Compared with the prior art, the present invention has the following beneficial effects:

[0013] The present invention uses graphite powder as a reducing agent, which can promote uniform heating of raw materials during the smelting process, reduce temperature gradients, thereby improving the smelting effect, and oxidize during the heating process to protect the surface of the material from damage, thereby ensuring the purity and quality of large-crystal fused magnesia. In addition, the present invention uses a high-power electric melting arc furnace to carry out high-temperature smelting of high-activity MgO powder, which can effectively remove impurities in the MgO powder and improve its purity, and can also shorten the smelting time and reduce energy consumption. DETAILED DESCRIPTION

[0014] The specific embodiments of the present invention are further described below:

[0015] Example 1

[0016] The present invention provides a method for preparing large-crystal fused magnesia, comprising the following steps:

[0017] 1) preparing magnesite with a MgO content exceeding 45%, and grinding the magnesite ore to produce a material with a particle size of ≤3 mm;

[0018] 2) The material of step 1) is sent to a light calcining kiln for calcination at a temperature of 850° C. for 5 hours; after the calcination, the obtained product is crushed and ground into 200-300 meshes to obtain a highly active MgO powder;

[0019] 3) adding graphite powder as a reducing agent to the high-activity MgO powder, stirring evenly and pressing into balls, placing in a 3500KVA electric melting arc furnace and continuously energizing for 6 hours at 3200°C, and slowly cooling after the reaction is complete to obtain super-large crystalline magnesia.

[0020] In the step 2), while the material is being heated in the light-firing kiln, a sodium carbonate solution is evenly added, wherein the concentration of the sodium carbonate solution is 12% and the amount added is 6% of the weight of the material.

[0021] The graphite powder has a particle size of 200 meshes and is added in an amount of 2% by weight of the high-activity MgO powder.

[0022] Example 2

[0023] The present invention provides a method for preparing large-crystal fused magnesia, comprising the following steps:

[0024] 1) preparing magnesite with a MgO content exceeding 45%, and grinding the magnesite ore to produce a material with a particle size of ≤3 mm;

[0025] 2) The material of step 1) is sent to a light calcining kiln for calcination at a temperature of 900° C. for 4 hours; after the calcination, the obtained product is crushed and ground to 200-300 meshes to obtain a highly active MgO powder;

[0026] 3) adding graphite powder as a reducing agent to the high-activity MgO powder, stirring evenly and pressing into balls, placing in a 3500KVA electric melting arc furnace and continuously energizing for 5 hours at 3500°C, and slowly cooling after the reaction is complete to obtain super-large crystalline magnesia.

[0027] In the step 2), while the material is being heated in the light-firing kiln, a sodium carbonate solution is evenly added, wherein the concentration of the sodium carbonate solution is 13% and the amount added is 7% of the weight of the material.

[0028] The graphite powder has a particle size of 200 meshes and is added in an amount of 3% by weight of the high-activity MgO powder.

[0029] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, and these simple modifications all belong to the protection scope of the present invention. It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations. In addition, the various different embodiments of the present invention can also be arbitrarily combined, as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A method for preparing large crystal fused magnesia, characterized in that: The steps include: 1) preparing magnesite with a MgO content exceeding 45%, and grinding the magnesite ore to produce a material with a particle size of ≤3 mm; 2) feeding the material of step 1) into a light calcining kiln for calcination at a temperature of 800-1000° C. for 3-5 hours; after calcination, grinding the obtained product to 200-300 mesh to obtain a high-activity MgO powder; 3) adding graphite powder as a reducing agent to the high-activity MgO powder, stirring evenly and pressing into balls, placing in a 3500KVA electric melting arc furnace and continuously smelting at 3000-3500°C for 5-8 hours, and slowly cooling after the reaction is complete to obtain super-large crystalline magnesia.

2. The method for preparing large crystal fused magnesia according to claim 1, characterized in that: In the step 2), during the heating process of the material in the light-firing kiln, a sodium carbonate solution is evenly added, the concentration of the sodium carbonate solution is 12-15%, and the amount added is 6-8% of the weight of the material.

3. The method for preparing large crystal fused magnesia according to claim 1, characterized in that: The graphite powder has a particle size of 200 meshes and an addition amount of 2-4% of the weight of the high-activity MgO powder.