Purification process of high-purity magnesia

Abstract

The invention discloses a purification process of high-purity magnesia, which is characterized by comprising the following steps: (1) raw material selection: firstly selecting magnesite as a raw material, and then putting the magnesite raw material into a grinding machine for grinding to obtain mineral powder; by adopting the purification process designed by the invention, high-purity magnesite can be obtained, and in the grinding and ball pressing process, the magnesium oxide material is ground until the granularity is greater than or equal to 90% in 12 microns and greater than or equal to 50% in 5 microns, the illusion crystal lattice of light-burned magnesite is destroyed, and the influence of the illusion of mother salt is eliminated, so that the ball pressing material is more compact and stable, which is of great significance to the production of high-purity magnesite. Meanwhile, during ball pressing, when the balling pressure excitation is larger than 300 MPa, part of pseudocrystals are damaged, sintering is promoted, the closed porosity is obviously reduced, high-purity magnesia can be obtained, and the balling rate and the volume density of balls can be greatly improved by adopting the secondary ball pressing process.

Description

Technical Field

[0001] The invention relates to the technical field of high-purity magnesia, in particular to a purification process of high-purity magnesia. Background Art

[0002] The main raw material for the production of magnesia refractory materials is magnesia. Relying on the unique high-quality natural magnesite resources, my country adopts one-step and two-step calcination methods to produce ordinary, medium and high-grade magnesia. With the rapid development of my country's economy, the metallurgical and building materials industries have developed rapidly. It has become the world's largest steel-producing country. The demand for magnesia refractory materials has increased year by year. With the promotion and use of new processes, new technologies and new kilns, magnesia refractory materials are required to have high purity, long life and low consumption. Therefore, the demand for high-purity and high-density magnesia, a refractory raw material, is increasing. The annual production of several million tons in southern Liaoning alone is still in short supply. In particular, due to years of mining, high-grade magnesia ore has decreased year by year, causing the grade of high-purity magnesia to decline, which has seriously affected the production of the industry. Therefore, the comprehensive utilization of low-grade magnesia ore and the adoption of various effective purification production processes in the production process are very necessary. , which is also a major problem that needs to be solved urgently. At the same time, the high impurity content and the large number of low-melting-point minerals bring a series of difficulties to the production of high-purity magnesia, resulting in many faults in the production process of the oil shaft kiln, easy to stick to the kiln shed material, and cannot be produced continuously. The sintering temperature is low and the product volume density is low. Only products with a volume density of 3.20g / cm3 and 25g / cm3 can be produced. To increase the volume density, the sintering temperature must be increased. Due to the sticking of the kiln, the kiln temperature drops and production is stopped. The shed material failure is handled repeatedly, and the refractory materials of the kiln body are severely damaged, which reduces the repair cycle of the shaft kiln. The overhaul that should have been carried out for more than two years has become an overhaul within one year, and the life of the kiln body is reduced by about 50%, which seriously affects the production of the enterprise, increases costs, reduces product quality, affects the benefits of the enterprise, and has a great impact on the quality of refractory products. The user's use effect is not good. Therefore, it is urgent to improve the purity of raw materials;

[0003] The indicators of high-purity magnesia produced from natural magnesite ore are as follows: the MgO content of first-grade magnesia is 97.5%, the volume density is 3.30g / cm3, and the ore used is special grade A; the MgO content of second-grade magnesia is 97%, the volume density is 3.25g / cm3, and special grade B ore is required; the MgO content of third-grade magnesia is 96.5%, the volume density is 3.20-3.25g / cm3, and special grade C ore is required;

[0004] The current situation is that the special A-grade ore has been exhausted, the special B-grade ore is very rare, accounting for only about 10% of the mining volume, and the special C-grade ore accounts for 20-30%. A large amount of ore is primary and secondary ore, and high-purity magnesia cannot be produced without mineral processing;

[0005] There are three methods for purifying natural magnesite: flotation, thermal separation, and chemical separation. Thermal separation and air separation are also used in the production and processing process. The flotation method requires large investment, occupies a large area, and has high costs. Currently, there are only two domestic producers, and the scale is relatively small. The thermal separation method has not been ideal and has not formed production capacity. The chemical method has high costs and low output, and is not suitable for the production of magnesium refractory materials industry. Therefore, a purification method with low investment, low cost and effective effect is an important issue that the magnesium refractory materials industry urgently needs to solve and promote. Summary of the invention

[0006] The purpose of the present invention is to provide a purification process for high-purity magnesia, which has the advantages of low investment and low cost, and solves the problems raised by the above-mentioned background technology.

[0007] To achieve the above object, the present invention provides the following technical solution: a purification process of high-purity magnesia, characterized in that it comprises the following steps:

[0008] (I) Raw material selection:

[0009] Firstly, magnesite is selected as the raw material, and then the magnesite raw material is put into a grinder for grinding, and then the mineral powder is obtained;

[0010] (II) Filtration and purification:

[0011] a. First, sodium chlorate is selected as the solvent, and it needs to be purified before use to remove Fe 2+ 、Na + , Ca 2+ 、SO4 2- etc. impurity ions;

[0012] b. Then, the ore powder obtained in step 1 is put into the sodium chloride solution purified in the above step, and then a precipitant is added to obtain basic magnesium carbonate;

[0013] (3) Light burning:

[0014] The basic magnesium carbonate obtained in the above step is put into a calcining furnace for calcining at a temperature of about 1000-1300° C. to generate light-burned magnesium oxide powder;

[0015] (IV) Fine grinding and ball pressing:

[0016] a. Grinding the light-burned magnesium oxide powder obtained in the above step using a fine grinding process;

[0017] b. First, the ground material in the feeding bin of the ball press is fed into the ball press by the feeding screw for ball pressing. After being lifted by the elevator, it is screened by the vibrating screen. The screened material is crushed and discharged into the intermediate bin as secondary ball pressing aggregate. The screened material enters the fine powder bin, and then the fine powder bin and the intermediate bin aggregate are mixed in a certain proportion and enter the ball press for secondary ball pressing. The balls from the ball press enter the dividing chute through the elevator. Under normal circumstances, the ball materials are screened by the vibrating screen in the dividing chute. The screened material enters the high-temperature vertical kiln for calcination. The screened material is crushed by the hammer crusher and returned to the feeding bin of the ball press through the screw conveyor. After being mixed as aggregate and fine powder, it can greatly improve the ball formation rate and the volume density of the balls.

[0018] (V) Secondary sintering:

[0019] The spheres obtained in the above steps are sent to a high-temperature furnace for high-temperature sintering, and the furnace temperature is controlled at about 1600°C-2000°C to obtain high-purity magnesia.

[0020] Preferably, the particle size of the mineral powder in step 1 is controlled between 10-12 mm and needs to be screened.

[0021] Preferably, coconut shell activated carbon can be added as a second phase additive during precipitation in step 2.

[0022] Preferably, in step three, the temperature is controlled at 1150° C. during the light calcination, and after calcination, the sintered product is cooled to below 100° C. and then sent to a grinder for fine grinding.

[0023] Preferably, during the fine grinding in step 4, the magnesium oxide material is ground to a particle size of 12 μm ≥ 90%, and 5 μm ≥ 50%.

[0024] Preferably, in the step 4, during the secondary ball pressing, the ratio of fine powder to aggregate is (7:3)-(7.5:2.5).

[0025] Preferably, in the step 4, the ball forming pressure is greater than 300 MPa when the ball is pressed.

[0026] Preferably, the temperature in step five is controlled at 1800° C. during high-temperature re-firing.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] By adopting the purification process designed by the present invention, high-purity magnesia can be obtained, and in the grinding and ball pressing process, the particle size of the magnesium oxide material is ground to 12μm≥90% and 5μm≥50%, the pseudo lattice of the light-burned magnesia is destroyed, and the influence of the mother salt pseudo is eliminated, so that the ball pressing material can be made denser and more stable, which is of great significance for the production of high-purity magnesia. At the same time, during the ball pressing, when the ball forming pressure is greater than 300MPa, part of the pseudocrystal is destroyed, sintering is promoted, and the closed porosity is significantly reduced, so high-purity magnesia can be obtained, and by adopting the secondary ball pressing process, the ball forming rate and the volume density of the ball can be greatly improved. DETAILED DESCRIPTION

[0029] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0030] The present invention provides a technical solution:

[0031] A purification process for high-purity magnesia comprises the following steps:

[0032] (I) Raw material selection:

[0033] Firstly, magnesite is selected as the raw material, and then the magnesite raw material is put into a grinder for grinding, and then the mineral powder is obtained;

[0034] (II) Filtration and purification:

[0035] a. First, sodium chlorate is selected as the solvent, and it needs to be purified before use to remove Fe 2+ 、Na + , Ca 2+ 、SO4 2- etc. impurity ions;

[0036] b. Then, the ore powder obtained in step 1 is put into the sodium chloride solution purified in the above step, and then a precipitant is added to obtain basic magnesium carbonate;

[0037] (3) Light burning:

[0038] The basic magnesium carbonate obtained in the above step is put into a calcining furnace for calcining at a temperature of about 1000-1300° C. to generate light-burned magnesium oxide powder;

[0039] (IV) Fine grinding and ball pressing:

[0040] a. Grinding the light-burned magnesium oxide powder obtained in the above step using a fine grinding process;

[0041] b. First, the ground material in the feeding bin of the ball press is fed into the ball press by the feeding screw for ball pressing. After being lifted by the elevator, it is screened by the vibrating screen. The screened material is crushed and discharged into the intermediate bin as secondary ball pressing aggregate. The screened material enters the fine powder bin, and then the fine powder bin and the intermediate bin aggregate are mixed in a certain proportion and enter the ball press for secondary ball pressing. The balls from the ball press enter the dividing chute through the elevator. Under normal circumstances, the ball materials are screened by the vibrating screen in the dividing chute. The screened material enters the high-temperature vertical kiln for calcination. The screened material is crushed by the hammer crusher and returned to the feeding bin of the ball press through the screw conveyor. After being mixed as aggregate and fine powder, it can greatly improve the ball formation rate and the volume density of the balls.

[0042] (V) Secondary sintering:

[0043] The spheres obtained in the above steps are sent to a high-temperature furnace for high-temperature sintering, and the furnace temperature is controlled at about 1600°C-2000°C to obtain high-purity magnesia.

[0044] Embodiment 1:

[0045] (I) Raw material selection:

[0046] Firstly, magnesite is selected as the raw material, and then the magnesite raw material is put into a grinder for grinding, and then the mineral powder is obtained;

[0047] (II) Filtration and purification:

[0048] a. First, sodium chlorate is selected as the solvent, and it needs to be purified before use to remove Fe 2+ 、Na + , Ca 2+ 、SO4 2- etc. impurity ions;

[0049] b. Then, the ore powder obtained in step 1 is put into the sodium chloride solution purified in the above step, and then a precipitant is added to obtain basic magnesium carbonate;

[0050] (3) Light burning:

[0051] The basic magnesium carbonate obtained in the above step is put into a calcining furnace for calcining at a temperature of about 1000-1300° C. to generate light-burned magnesium oxide powder;

[0052] (IV) Fine grinding and ball pressing:

[0053] a. Grinding the light-burned magnesium oxide powder obtained in the above step using a fine grinding process;

[0054] b. First, the ground material in the feeding bin of the ball press is fed into the ball press by the feeding screw for ball pressing. After being lifted by the elevator, it is screened by the vibrating screen. The screened material is crushed and discharged into the intermediate bin as secondary ball pressing aggregate. The screened material enters the fine powder bin, and then the fine powder bin and the intermediate bin aggregate are mixed in a certain proportion and enter the ball press for secondary ball pressing. The balls from the ball press enter the dividing chute through the elevator. Under normal circumstances, the ball materials are screened by the vibrating screen in the dividing chute. The screened material enters the high-temperature vertical kiln for calcination. The screened material is crushed by the hammer crusher and returned to the feeding bin of the ball press through the screw conveyor. After being mixed as aggregate and fine powder, it can greatly improve the ball formation rate and the volume density of the balls.

[0055] (V) Secondary sintering:

[0056] The spheres obtained in the above steps are sent to a high-temperature furnace for high-temperature sintering, and the furnace temperature is controlled at about 1600°C-2000°C to obtain high-purity magnesia.

[0057] Embodiment 2:

[0058] In the first embodiment, the following steps are added:

[0059] The particle size of the mineral powder in step 1 is controlled between 10-12mm and needs to be screened.

[0060] (I) Raw material selection:

[0061] Firstly, magnesite is selected as the raw material, and then the magnesite raw material is put into a grinder for grinding, and then the mineral powder is obtained;

[0062] (II) Filtration and purification:

[0063] a. First, sodium chlorate is selected as the solvent, and it needs to be purified before use to remove Fe 2+ 、Na + , Ca 2+ 、SO4 2- etc. impurity ions;

[0064] b. Then, the ore powder obtained in step 1 is put into the sodium chloride solution purified in the above step, and then a precipitant is added to obtain basic magnesium carbonate;

[0065] (3) Light burning:

[0066] The basic magnesium carbonate obtained in the above step is put into a calcining furnace for calcining at a temperature of about 1000-1300° C. to generate light-burned magnesium oxide powder;

[0067] (IV) Fine grinding and ball pressing:

[0068] a. Grinding the light-burned magnesium oxide powder obtained in the above step using a fine grinding process;

[0069] b. First, the ground material in the feeding bin of the ball press is fed into the ball press by the feeding screw for ball pressing. After being lifted by the elevator, it is screened by the vibrating screen. The screened material is crushed and discharged into the intermediate bin as secondary ball pressing aggregate. The screened material enters the fine powder bin, and then the fine powder bin and the intermediate bin aggregate are mixed in a certain proportion and enter the ball press for secondary ball pressing. The balls from the ball press enter the dividing chute through the elevator. Under normal circumstances, the ball materials are screened by the vibrating screen in the dividing chute. The screened material enters the high-temperature vertical kiln for calcination. The screened material is crushed by the hammer crusher and returned to the feeding bin of the ball press through the screw conveyor. After being mixed as aggregate and fine powder, it can greatly improve the ball formation rate and the volume density of the balls.

[0070] (V) Secondary sintering:

[0071] The spheres obtained in the above steps are sent to a high-temperature furnace for high-temperature sintering, and the furnace temperature is controlled at about 1600°C-2000°C to obtain high-purity magnesia.

[0072] Embodiment three:

[0073] In the second embodiment, the following steps are added:

[0074] In step 2, coconut shell activated carbon can be added as a second phase additive during precipitation.

[0075] (I) Raw material selection:

[0076] Firstly, magnesite is selected as the raw material, and then the magnesite raw material is put into a grinder for grinding, and then the mineral powder is obtained;

[0077] (II) Filtration and purification:

[0078] a. First, sodium chlorate is selected as the solvent, and it needs to be purified before use to remove Fe 2+ 、Na + , Ca 2+ 、SO4 2- etc. impurity ions;

[0079] b. Then, the ore powder obtained in step 1 is put into the sodium chloride solution purified in the above step, and then a precipitant is added to obtain basic magnesium carbonate;

[0080] (3) Light burning:

[0081] The basic magnesium carbonate obtained in the above step is put into a calcining furnace for calcining at a temperature of about 1000-1300° C. to generate light-burned magnesium oxide powder;

[0082] (IV) Fine grinding and ball pressing:

[0083] a. Grinding the light-burned magnesium oxide powder obtained in the above step using a fine grinding process;

[0084] b. First, the ground material in the feeding bin of the ball press is fed into the ball press by the feeding screw for ball pressing. After being lifted by the elevator, it is screened by the vibrating screen. The screened material is crushed and discharged into the intermediate bin as secondary ball pressing aggregate. The screened material enters the fine powder bin, and then the fine powder bin and the intermediate bin aggregate are mixed in a certain proportion and enter the ball press for secondary ball pressing. The balls from the ball press enter the dividing chute through the elevator. Under normal circumstances, the ball materials are screened by the vibrating screen in the dividing chute. The screened material enters the high-temperature vertical kiln for calcination. The screened material is crushed by the hammer crusher and returned to the feeding bin of the ball press through the screw conveyor. After being mixed as aggregate and fine powder, it can greatly improve the ball formation rate and the volume density of the balls.

[0085] (V) Secondary sintering:

[0086] The spheres obtained in the above steps are sent to a high-temperature furnace for high-temperature sintering, and the furnace temperature is controlled at about 1600°C-2000°C to obtain high-purity magnesia.

[0087] Embodiment 4:

[0088] In the third embodiment, the following steps are added:

[0089] In step 3, the temperature is controlled at 1150°C during light calcination, and after calcination, it is cooled to below 100°C and then sent to a grinder for fine grinding.

[0090] (I) Raw material selection:

[0091] Firstly, magnesite is selected as the raw material, and then the magnesite raw material is put into a grinder for grinding, and then the mineral powder is obtained;

[0092] (II) Filtration and purification:

[0093] a. First, sodium chlorate is selected as the solvent, and it needs to be purified before use to remove Fe 2+ 、Na + , Ca 2+ 、SO4 2- etc. impurity ions;

[0094] b. Then, the ore powder obtained in step 1 is put into the sodium chloride solution purified in the above step, and then a precipitant is added to obtain basic magnesium carbonate;

[0095] (3) Light burning:

[0096] The basic magnesium carbonate obtained in the above step is put into a calcining furnace for calcining at a temperature of about 1000-1300° C. to generate light-burned magnesium oxide powder;

[0097] (IV) Fine grinding and ball pressing:

[0098] a. Grinding the light-burned magnesium oxide powder obtained in the above step using a fine grinding process;

[0099] b. First, the ground material in the feeding bin of the ball press is fed into the ball press by the feeding screw for ball pressing. After being lifted by the elevator, it is screened by the vibrating screen. The screened material is crushed and discharged into the intermediate bin as secondary ball pressing aggregate. The screened material enters the fine powder bin, and then the fine powder bin and the intermediate bin aggregate are mixed in a certain proportion and enter the ball press for secondary ball pressing. The balls from the ball press enter the dividing chute through the elevator. Under normal circumstances, the ball materials are screened by the vibrating screen in the dividing chute. The screened material enters the high-temperature vertical kiln for calcination. The screened material is crushed by the hammer crusher and returned to the feeding bin of the ball press through the screw conveyor. After being mixed as aggregate and fine powder, it can greatly improve the ball formation rate and the volume density of the balls.

[0100] (V) Secondary sintering:

[0101] The spheres obtained in the above steps are sent to a high-temperature furnace for high-temperature sintering, and the furnace temperature is controlled at about 1600°C-2000°C to obtain high-purity magnesia.

[0102] Embodiment five:

[0103] In the fourth embodiment, the following steps are added:

[0104] In step 4, during fine grinding, the magnesium oxide material is ground to a particle size of 12 μm ≥ 90%, 5 μm ≥ 50%.

[0105] (I) Raw material selection:

[0106] Firstly, magnesite is selected as the raw material, and then the magnesite raw material is put into a grinder for grinding, and then the mineral powder is obtained;

[0107] (II) Filtration and purification:

[0108] a. First, sodium chlorate is selected as the solvent, and it needs to be purified before use to remove Fe 2+ 、Na + , Ca 2+ 、SO4 2- etc. impurity ions;

[0109] b. Then, the ore powder obtained in step 1 is put into the sodium chloride solution purified in the above step, and then a precipitant is added to obtain basic magnesium carbonate;

[0110] (3) Light burning:

[0111] The basic magnesium carbonate obtained in the above step is put into a calcining furnace for calcining at a temperature of about 1000-1300° C. to generate light-burned magnesium oxide powder;

[0112] (IV) Fine grinding and ball pressing:

[0113] a. Grinding the light-burned magnesium oxide powder obtained in the above step using a fine grinding process;

[0114] b. First, the ground material in the feeding bin of the ball press is fed into the ball press by the feeding screw for ball pressing. After being lifted by the elevator, it is screened by the vibrating screen. The screened material is crushed and discharged into the intermediate bin as secondary ball pressing aggregate. The screened material enters the fine powder bin, and then the fine powder bin and the intermediate bin aggregate are mixed in a certain proportion and enter the ball press for secondary ball pressing. The balls from the ball press enter the dividing chute through the elevator. Under normal circumstances, the ball materials are screened by the vibrating screen in the dividing chute. The screened material enters the high-temperature vertical kiln for calcination. The screened material is crushed by the hammer crusher and returned to the feeding bin of the ball press through the screw conveyor. After being mixed as aggregate and fine powder, it can greatly improve the ball formation rate and the volume density of the balls.

[0115] (V) Secondary sintering:

[0116] The spheres obtained in the above steps are sent to a high-temperature furnace for high-temperature sintering, and the furnace temperature is controlled at about 1600°C-2000°C to obtain high-purity magnesia.

[0117] Embodiment six:

[0118] In the fifth embodiment, the following steps are added:

[0119] In step 4, during the secondary ball pressing, the ratio of fine powder to aggregate is (7:3) - (7.5:2.5).

[0120] (I) Raw material selection:

[0121] Firstly, magnesite is selected as the raw material, and then the magnesite raw material is put into a grinder for grinding, and then the mineral powder is obtained;

[0122] (II) Filtration and purification:

[0123] a. First, sodium chlorate is selected as the solvent, and it needs to be purified before use to remove Fe 2+ 、Na + , Ca 2+ 、SO4 2- etc. impurity ions;

[0124] b. Then, the ore powder obtained in step 1 is put into the sodium chloride solution purified in the above step, and then a precipitant is added to obtain basic magnesium carbonate;

[0125] (3) Light burning:

[0126] The basic magnesium carbonate obtained in the above step is put into a calcining furnace for calcining at a temperature of about 1000-1300° C. to generate light-burned magnesium oxide powder;

[0127] (IV) Fine grinding and ball pressing:

[0128] a. Grinding the light-burned magnesium oxide powder obtained in the above step using a fine grinding process;

[0129] b. First, the ground material in the feeding bin of the ball press is fed into the ball press by the feeding screw for ball pressing. After being lifted by the elevator, it is screened by the vibrating screen. The screened material is crushed and discharged into the intermediate bin as secondary ball pressing aggregate. The screened material enters the fine powder bin, and then the fine powder bin and the intermediate bin aggregate are mixed in a certain proportion and enter the ball press for secondary ball pressing. The balls from the ball press enter the dividing chute through the elevator. Under normal circumstances, the ball materials are screened by the vibrating screen in the dividing chute. The screened material enters the high-temperature vertical kiln for calcination. The screened material is crushed by the hammer crusher and returned to the feeding bin of the ball press through the screw conveyor. After being mixed as aggregate and fine powder, it can greatly improve the ball formation rate and the volume density of the balls.

[0130] (V) Secondary sintering:

[0131] The spheres obtained in the above steps are sent to a high-temperature furnace for high-temperature sintering, and the furnace temperature is controlled at about 1600°C-2000°C to obtain high-purity magnesia.

[0132] Embodiment seven:

[0133] In the sixth embodiment, the following steps are added:

[0134] In step 4, the ball forming pressure is greater than 300 MPa when pressing the ball.

[0135] (I) Raw material selection:

[0136] Firstly, magnesite is selected as the raw material, and then the magnesite raw material is put into a grinder for grinding, and then the mineral powder is obtained;

[0137] (II) Filtration and purification:

[0138] a. First, sodium chlorate is selected as the solvent, and it needs to be purified before use to remove Fe 2+ 、Na + , Ca 2+ 、SO4 2- etc. impurity ions;

[0139] b. Then, the ore powder obtained in step 1 is put into the sodium chloride solution purified in the above step, and then a precipitant is added to obtain basic magnesium carbonate;

[0140] (3) Light burning:

[0141] The basic magnesium carbonate obtained in the above step is put into a calcining furnace for calcining at a temperature of about 1000-1300° C. to generate light-burned magnesium oxide powder;

[0142] (IV) Fine grinding and ball pressing:

[0143] a. Grinding the light-burned magnesium oxide powder obtained in the above step using a fine grinding process;

[0144] b. First, the ground material in the feeding bin of the ball press is fed into the ball press by the feeding screw for ball pressing. After being lifted by the elevator, it is screened by the vibrating screen. The screened material is crushed and discharged into the intermediate bin as secondary ball pressing aggregate. The screened material enters the fine powder bin, and then the fine powder bin and the intermediate bin aggregate are mixed in a certain proportion and enter the ball press for secondary ball pressing. The balls from the ball press enter the dividing chute through the elevator. Under normal circumstances, the ball materials are screened by the vibrating screen in the dividing chute. The screened material enters the high-temperature vertical kiln for calcination. The screened material is crushed by the hammer crusher and returned to the feeding bin of the ball press through the screw conveyor. After being mixed as aggregate and fine powder, it can greatly improve the ball formation rate and the volume density of the balls.

[0145] (V) Secondary sintering:

[0146] The spheres obtained in the above steps are sent to a high-temperature furnace for high-temperature sintering, and the furnace temperature is controlled at about 1600°C-2000°C to obtain high-purity magnesia.

[0147] Embodiment eight:

[0148] In the seventh embodiment, the following steps are added:

[0149] Step 5: During high temperature re-firing, the temperature is controlled at 1800°C.

[0150] (I) Raw material selection:

[0151] Firstly, magnesite is selected as the raw material, and then the magnesite raw material is put into a grinder for grinding, and then the mineral powder is obtained;

[0152] (II) Filtration and purification:

[0153] a. First, sodium chlorate is selected as the solvent, and it needs to be purified before use to remove Fe 2+ 、Na + , Ca 2+ 、SO4 2- etc. impurity ions;

[0154] b. Then, the ore powder obtained in step 1 is put into the sodium chloride solution purified in the above step, and then a precipitant is added to obtain basic magnesium carbonate;

[0155] (3) Light burning:

[0156] The basic magnesium carbonate obtained in the above step is put into a calcining furnace for calcining at a temperature of about 1000-1300° C. to generate light-burned magnesium oxide powder;

[0157] (IV) Fine grinding and ball pressing:

[0158] a. Grinding the light-burned magnesium oxide powder obtained in the above step using a fine grinding process;

[0159] b. First, the ground material in the feeding bin of the ball press is fed into the ball press by the feeding screw for ball pressing. After being lifted by the elevator, it is screened by the vibrating screen. The screened material is crushed and discharged into the intermediate bin as secondary ball pressing aggregate. The screened material enters the fine powder bin, and then the fine powder bin and the intermediate bin aggregate are mixed in a certain proportion and enter the ball press for secondary ball pressing. The balls from the ball press enter the dividing chute through the elevator. Under normal circumstances, the ball materials are screened by the vibrating screen in the dividing chute. The screened material enters the high-temperature vertical kiln for calcination. The screened material is crushed by the hammer crusher and returned to the feeding bin of the ball press through the screw conveyor. After being mixed as aggregate and fine powder, it can greatly improve the ball formation rate and the volume density of the balls.

[0160] (V) Secondary sintering:

[0161] The spheres obtained in the above steps are sent to a high-temperature furnace for high-temperature sintering, and the furnace temperature is controlled at about 1600°C-2000°C to obtain high-purity magnesia.

[0162] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A purification process for high-purity magnesia, characterized in that: The steps include: (I) Raw material selection: Firstly, magnesite is selected as the raw material, and then the magnesite raw material is put into a grinder for grinding, and then the mineral powder is obtained; (II) Filtration and purification: a. First, sodium chlorate is selected as the solvent, and it needs to be purified before use to remove Fe 2+ 、Na + , Ca 2+ 、SO4 2- etc. impurity ions; b. Then, the ore powder obtained in step 1 is put into the sodium chloride solution purified in the above step, and then a precipitant is added to obtain basic magnesium carbonate; (3) Light burning: The basic magnesium carbonate obtained in the above step is put into a calcining furnace for calcining at a temperature of about 1000-1300° C. to generate light-burned magnesium oxide powder; (IV) Fine grinding and ball pressing: a. Grinding the light-burned magnesium oxide powder obtained in the above step using a fine grinding process; b. First, the ground material in the feeding bin of the ball press is fed into the ball press by the feeding screw for ball pressing. After being lifted by the elevator, it is screened by the vibrating screen. The screened material is crushed and discharged into the intermediate bin as secondary ball pressing aggregate. The screened material enters the fine powder bin, and then the fine powder bin and the intermediate bin aggregate are mixed in a certain proportion and enter the ball press for secondary ball pressing. The balls from the ball press enter the dividing chute through the elevator. Under normal circumstances, the ball materials are screened by the vibrating screen in the dividing chute. The screened material enters the high-temperature vertical kiln for calcination. The screened material is crushed by the hammer crusher and returned to the feeding bin of the ball press through the screw conveyor. After being mixed as aggregate and fine powder, it can greatly improve the ball formation rate and the volume density of the balls. (V) Secondary sintering: The spheres obtained in the above steps are sent to a high-temperature furnace for high-temperature sintering, and the furnace temperature is controlled at about 1600°C-2000°C to obtain high-purity magnesia.

2. A purification process for high-purity magnesia according to claim 1, characterized in that: The particle size of the mineral powder in step 1 is controlled between 10-12 mm and needs to be screened.

3. A purification process for high-purity magnesia according to claim 1, characterized in that: In the step 2, coconut shell activated carbon can be added as a second phase additive during precipitation.

4. A purification process for high-purity magnesia according to claim 1, characterized in that: In the step 3, the temperature is controlled at 1150° C. during the light calcination, and after the calcination, the sintered product is cooled to below 100° C. and then sent to a grinder for fine grinding.

5. A purification process for high-purity magnesia according to claim 1, characterized in that: During the fine grinding in step 4, the particle size of the magnesium oxide material is ground to 12 μm ≥ 90%, and 5 μm ≥ 50%.

6. A purification process for high-purity magnesia according to claim 1, characterized in that: In the step 4, during the secondary ball pressing, the ratio of fine powder to aggregate is (7:3)-(7.5:2.5).

7. A purification process for high-purity magnesia according to claim 1, characterized in that: In the step 4, the ball forming pressure is greater than 300 MPa when the ball is pressed.

8. A purification process for high-purity magnesia according to claim 1, characterized in that: In step 5, the temperature is controlled at 1800° C. during high-temperature re-firing.