Preparation process of dead-burnt magnesia

Abstract

The invention relates to a dead-burnt magnesia preparation process which comprises the following steps: 1) crushing microcrystalline magnesite in a crusher to prepare a raw material of which the particle size is more than 20mm and less than or equal to 60mm; (2) the raw materials are subjected to primary calcination, the calcination temperature ranges from 1000 DEG C to 1200 DEG C, and the calcination time ranges from 5 min to 15 min; (3) cooling the raw materials subjected to primary section firing to room temperature, and then finely grinding and screening to obtain fine powder; 4) pressing the fine powder into balls through a high-pressure ball press machine; 5) drying the ball material at the drying temperature of 100-120 DEG C for 15-20 hours; and (6) after drying, carrying out secondary calcination at the calcination temperature of 1550-1800 DEG C for 5-6 hours. The process provided by the invention can be used for preparing high-purity and high-density dead-burnt magnesia.

Description

Technical Field

[0001] The invention relates to the field of refractory materials, and in particular to a process for preparing dead-burned magnesia. Background Art

[0002] Dead-burned magnesia is an important refractory material. It has the advantages of alkali resistance, chemical corrosion resistance, and good thermal stability. It is widely used in steel, cement, glass and other industries.

[0003] The MgO content in the dead-burned magnesia prepared by the existing dead-burned magnesia preparation method is 92%, which is low and wastes ore resources. In addition, the density of the magnesia is low. Magnesite is preheated and decomposed in the kiln to release CO2 to become light-burned MgO, but its MgCO3 "mother salt illusion" still exists, which is not conducive to the further densification of the magnesia. The volume density of the sintered magnesia is only between 3.0 grams and 3.1 grams per cubic centimeter.

[0004] In view of this, it is urgent to propose a dead-burned magnesia preparation process to make full use of mineral resources to prepare dead-burned magnesia with high purity, high bulk density and few impurities. Summary of the invention

[0005] In order to overcome the defects of the prior art, the technical problem solved by the present invention is to provide a process for preparing dead-burned magnesia, which can prepare high-purity and high-density dead-burned magnesia.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A process for preparing dead-burned magnesia comprises the following steps:

[0008] 1) crushing the microcrystalline magnesite in a crusher to produce a raw material with a particle size of 20 mm < ≤ 60 mm;

[0009] 2) calcining the above raw materials at a temperature of 1000-1200° C. for 5-15 min;

[0010] 3) The raw material after the primary sintering is cooled to room temperature, and then finely ground and sieved to obtain fine powder;

[0011] 4) The fine powder is passed through a high-pressure ball press to be pressed into balls;

[0012] 5) Dry the ball material at a temperature of 100 to 120°C for 15 to 20 hours;

[0013] 6) After drying, secondary calcination is carried out at a temperature of 1550-1800° C. for 5-6 hours.

[0014] The MgO content in the microcrystalline magnesite is greater than or equal to 47%.

[0015] The particle size of the fine powder is between 0.45 and 0.88 mm.

[0016] The pressing pressure is 200-350 MPa.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] 1) In the present invention, fine grinding of the raw material after the primary calcination is helpful to destroy the magnesium oxide pseudocrystal and improve the density of the magnesia sand, and then pressing and molding is performed to increase the density of the dead-burned magnesia sand.

[0019] 2) By adopting the preparation process of the present invention, high-purity dead-burned magnesia with a MgO content of more than 98% and a bulk density greater than 3.3 g·cm-3 can be prepared. DETAILED DESCRIPTION

[0020] The specific embodiments of the present invention are further described below:

[0021] Example 1

[0022] The present invention provides a process for preparing dead-burned magnesia, comprising the following steps:

[0023] 1) crushing the microcrystalline magnesite in a crusher to produce a raw material with a particle size of 20 mm < ≤ 60 mm;

[0024] 2) calcining the above raw materials at a temperature of 1100° C. for 10 min;

[0025] 3) The raw material after the primary sintering is cooled to room temperature, and then finely ground and sieved to obtain fine powder;

[0026] 4) The fine powder is passed through a high-pressure ball press to be pressed into balls;

[0027] 5) Dry the ball material at 110°C for 17 hours;

[0028] 6) After drying, secondary calcination is carried out at a temperature of 1600° C. for 5 hours.

[0029] The MgO content in the microcrystalline magnesite is greater than or equal to 47%.

[0030] The particle size of the fine powder is between 0.45 and 0.88 mm.

[0031] The pressure is 300 MPa.

[0032] The obtained dead-burned magnesia has a MgO content of 98.36% and a bulk density of 3.43 g·cm-3.

[0033] Example 2

[0034] The present invention provides a process for preparing dead-burned magnesia, comprising the following steps:

[0035] 1) crushing the microcrystalline magnesite in a crusher to produce a raw material with a particle size of 20 mm < ≤ 60 mm;

[0036] 2) calcining the above raw materials at a temperature of 1200° C. for 8 min;

[0037] 3) The raw material after the primary sintering is cooled to room temperature, and then finely ground and sieved to obtain fine powder;

[0038] 4) The fine powder is passed through a high-pressure ball press to be pressed into balls;

[0039] 5) Dry the ball material at 120°C for 15 hours;

[0040] 6) After drying, secondary calcination is carried out at a temperature of 1700° C. for 6 hours.

[0041] The MgO content in the magnesite is greater than or equal to 47%.

[0042] The particle size of the fine powder is between 0.45 and 0.88 mm.

[0043] The pressure is 350 MPa.

[0044] The obtained dead-burned magnesia has a MgO content of 97.8% and a bulk density of 3.4 g·cm-3.

[0045] 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 process for preparing dead-burned magnesia, characterized in that: The steps include: 1) crushing the microcrystalline magnesite in a crusher to produce a raw material with a particle size of 20 mm < ≤ 60 mm; 2) calcining the above raw materials at a temperature of 1000-1200° C. for 5-15 min; 3) The raw material after the primary sintering is cooled to room temperature, and then finely ground and sieved to obtain fine powder; 4) The fine powder is passed through a high-pressure ball press to be pressed into balls; 5) Dry the ball material at a temperature of 100 to 120°C for 15 to 20 hours; 6) After drying, secondary calcination is carried out at a temperature of 1550-1800° C. for 5-6 hours.

2. A process for preparing dead-burned magnesia according to claim 1, characterized in that: The MgO content in the microcrystalline magnesite is greater than or equal to 47%.

3. A process for preparing dead-burned magnesia according to claim 1, characterized in that: The particle size of the fine powder is between 0.45 and 0.88 mm.

4. A process for preparing dead-burned magnesia according to claim 1, characterized in that: The pressing pressure is 200-350 MPa.