阅读说明：本技术 一种以氢氧化镁为原料生产电熔镁砂的工艺及系统 (Process and system for producing fused magnesia by taking magnesium hydroxide as raw material ) 是由 刘杰 洪艳萍 杨梦� 于 2019-11-01 设计创作，主要内容包括：本发明涉及一种以氢氧化镁为原料生产电熔镁砂的工艺及系统,所述系统包括滤饼贮仓、箱式给料机、锤式破碎干燥机、悬浮焙烧装置、高温高压压球系统、斗式提升机、电炉供料仓及电炉熔炼系统；将海水或卤水制得的氢氧化镁滤饼,经箱式给料机送入锤式破碎干燥机中进行粉碎、干燥,粉碎、干燥后的氢氧化镁粉料随干燥风一起进入悬浮焙烧装置进行预热、焙烧,得到的氧化镁送入高温高压压球系统中进行循环热压,得到的氧化镁球通过斗式提升机存入电炉供料仓,之后送入电炉熔炼系统内熔炼,制得电熔镁砂产品。本发明工艺流程短、生产成本低,并且节能环保。(The invention relates to a process and a system for producing fused magnesia by taking magnesium hydroxide as a raw material, wherein the system comprises a filter cake storage bin, a box-type feeder, a hammer type crushing dryer, a suspension roasting device, a high-temperature high-pressure ball pressing system, a bucket elevator, an electric furnace feeding bin and an electric furnace smelting system; and feeding magnesium hydroxide filter cakes prepared from seawater or brine into a hammer type crushing dryer through a box feeder for crushing and drying, feeding crushed and dried magnesium hydroxide powder into a suspension roasting device along with drying air for preheating and roasting, feeding the obtained magnesium oxide into a high-temperature high-pressure ball pressing system for circulating hot pressing, storing the obtained magnesium oxide balls into an electric furnace feeding bin through a bucket elevator, and then feeding the magnesium oxide balls into an electric furnace smelting system for smelting to prepare the fused magnesia product. The invention has the advantages of short process flow, low production cost, energy saving and environmental protection.)

1. A process for preparing electrically fused magnesite from magnesium hydroxide includes such steps as preparing magnesium hydroxide cake from seawater or bittern, loading it in hammer crusher, crushing, drying, preheating, calcining in suspension calcining apparatus, hot pressing in high-temp and-pressure ball pressing system, loading the magnesium oxide balls in electric furnace, and smelting in electric furnace smelting system.

2. The process for producing fused magnesia by using magnesium hydroxide as a raw material according to claim 1, wherein the hammer mill drier dries the material by using the waste heat of the flue gas of the suspension roasting device, and then the drying air returns to the suspension roasting device again; the water content of the dried magnesium hydroxide fine powder is less than or equal to 5 percent.

3. The process for producing fused magnesia using magnesium hydroxide as a raw material according to claim 1, wherein the suspension roasting device has a totally enclosed structure, 3 to 6 cyclones, a preheating section and a roasting section, wherein the roasting temperature is 500 to 650 ℃, and the discharge temperature is 300 to 450 ℃.

4. The process for producing fused magnesia by using magnesium hydroxide as a raw material according to claim 1, wherein a heat source of the suspension roasting device is mainly from waste heat of flue gas of an electric furnace, the suspension roasting device is provided with a fuel system, and the fuel system is used for adjusting the temperature during roasting; and a part of the flue gas discharged by the suspension roasting device is used as a drying heat source of the hammer type crushing dryer, and the residual flue gas is discharged after being treated to reach the standard.

5. The process for producing fused magnesia by using magnesium hydroxide as a raw material according to claim 1, wherein magnesium oxide obtained by roasting in the suspension roasting device directly enters a high-temperature and high-pressure ball pressing system without cooling, and is subjected to circulating hot pressing at 400-600 ℃; the high-temperature high-pressure ball pressing system comprises a prepressing device and a high-pressure device, the linear pressure of the ball pressing machine is 80-110 kN/cm, a ball groove is almond-shaped or peach-core-shaped, and the capacity is 10-20 cm³。

6. The process for producing fused magnesia by using magnesium hydroxide as a raw material according to claim 1, wherein an electric furnace smelting system is provided with a transformer above 4000kVA and an automatic electrode lifting device, the smelting temperature is above 3000 ℃, the electric furnace charging and electrode lifting operations are automatically controlled, and the position of a furnace opening is integrally closed.

7. The process for producing fused magnesia using magnesium hydroxide as raw material according to claim 1, wherein the fused magnesia produced has MgO contentNot less than 99 percent and volume density not less than 3.55g/cm³。

8. The system for producing the fused magnesia by taking the magnesium hydroxide as the raw material for realizing the process of any one of claims 1 to 7 is characterized by comprising a filter cake storage bin, a box-type feeder, a hammer type crushing dryer, a suspension roasting device, a high-temperature high-pressure ball pressing system, a bucket elevator, an electric furnace feeding bin and an electric furnace smelting system; the discharge gate of filter cake storehouse links to each other with the feed inlet of box batcher, the feed inlet of hammer crushing dryer is connected to the discharge gate of box batcher, the feed inlet of suspension roasting device is connected to the discharge gate of hammer crushing dryer, the feed inlet of high temperature high pressure ball pressing system is connected to the discharge gate of suspension roasting device, the material loading end of bucket elevator is connected to the discharge gate of high temperature high pressure ball pressing system, the feed inlet in electric stove feed storehouse is connected to the discharge end of bucket elevator, the feed inlet of electric stove system of smelting is connected to the discharge gate in electric stove feed storehouse.

9. The system for producing fused magnesia by using magnesium hydroxide as a raw material according to claim 8, wherein the suspension roasting device is provided with a flue gas outlet connected with a flue gas main pipe, the flue gas main pipe is connected with a drying air inlet of the hammer crusher dryer through a flue gas conveying pipeline I, the flue gas main pipe is connected with a flue gas inlet of a flue gas purification system through a flue gas conveying pipeline II, and a clean flue gas outlet of the flue gas purification system is connected with a chimney; the flue gas main pipe is provided with a fan, and the first flue gas conveying pipeline and the second flue gas conveying pipeline are respectively provided with an adjusting valve; and a cold air inlet is also formed in the first flue gas conveying pipeline and is connected with a cold air pipeline, and an adjusting valve is also arranged on the cold air pipeline.

10. The system for producing fused magnesia by using magnesium hydroxide as a raw material according to claim 8, wherein the electric furnace smelting system is provided with a flue gas outlet which is connected with a heat source inlet of the suspension roasting device through a flue gas pipeline.

Technical Field

The invention relates to the technical field of magnesium material production, in particular to a process and a system for producing fused magnesia by taking magnesium hydroxide as a raw material.

Background

Sintering and electric melting are two main processes for preparing magnesia, wherein the sintering process is to calcine natural gas, heavy oil and the like serving as fuels in a refractory kiln at the temperature of 1500-2300 ℃ to produce magnesia; the electric smelting process is to melt the magnesia raw material to more than 3000 ℃ in an electric arc furnace by utilizing electric energy to prepare the electric smelting magnesia product. The main crystal phase periclase crystal grains in the fused magnesia product are coarser, the structure is more compact, the fused magnesia product can still keep stable at the temperature of more than 2300 ℃, the high-temperature strength, the slag resistance, the scouring resistance and the hydration resistance of the fused magnesia product are all superior to those of sintered magnesia, and the large-crystal magnesia product also has special optical performance. The fused magnesium product can be used as a high-quality refractory material in industries such as metallurgy, building materials, glass, cement and the like, and can also be used as a high-end raw material in the fields of electric power, aerospace, national defense, nuclear industry and the like.

At present, the raw materials for producing magnesite in the world mainly comprise natural magnesite and magnesium-rich raw materials extracted from seawater and brine. The Liaoning area of China has high-quality magnesite resources, which become main production bases and export bases of the global magnesite market from the 90 th century, and disordered and extensive mining for a long time leads to ore quality reduction, resource waste, ecological damage and serious environmental pollution. Meanwhile, the seawater and brine resources in China are rich, thousands of tons of magnesium-rich concentrated seawater and brine can be generated every year, and the magnesium hydroxide chemically treated by the seawater and the brine is used as the raw material to prepare the magnesium hydroxide with the purity of more than 98 percent and the volume density of 3.45g/cm³The magnesite product. The prior art for preparing magnesia by taking magnesium hydroxide as a raw material is mainly sintering process, has long process flow and high production cost, and has few domestic related production enterprises.

In recent years, the treatment requirement of furnace flue gas is gradually increased, sulfur dioxide and nitrogen oxides are required to be treated besides dust, and particularly, the nitrogen oxides in a high-temperature furnace adopting a sintering process have high concentration and high treatment cost, so that the production cost of enterprises is greatly increased. The flue gas in the electric furnace production mainly contains dust, and basically has no sulfur dioxide and nitric oxide, meanwhile, the construction of power generation and supply facilities in China is gradually complete, and the price of industrial electricity is gradually reduced, so that the price advantage of the magnesia produced by the electric smelting process is increasingly prominent.

Aiming at the problems of magnesite resource shortage, ecological environment pollution and the like, the invention combines a high-quality magnesium-rich raw material prepared from seawater or brine with an electric melting process to develop a process and a system for producing electric melting magnesia by taking magnesium hydroxide as a raw material, which are beneficial to shortening process flow, improving product quality, popularizing an energy-saving technology and reducing production cost, and have very important significance for promoting sustainable development of magnesium resources and energy conservation and environmental protection.

Disclosure of Invention

The invention provides a process and a system for producing fused magnesia by taking magnesium hydroxide as a raw material, wherein the magnesium hydroxide prepared from seawater or brine is used as the raw material, and a novel high-efficiency and energy-saving fused process is adopted to prepare a fused magnesia product with high purity, high density and high added value.

In order to achieve the purpose, the invention adopts the following technical scheme:

a process for preparing electrically fused magnesite from magnesium hydroxide includes such steps as preparing magnesium hydroxide cake from seawater or bittern, loading it in hammer-type breaking-drying machine, breaking, drying, preheating, calcining in suspension calcining apparatus, loading the magnesium oxide in high-temp high-pressure ball pressing system, cyclic hot pressing, loading the magnesium oxide balls in electric furnace, smelting in electric furnace smelting system, and loading the balls in electric furnace.

The hammer type crushing dryer dries the material by using the waste heat of the flue gas of the suspension roasting device, and then the drying air returns to the suspension roasting device again; the water content of the dried magnesium hydroxide fine powder is less than or equal to 5 percent.

The suspension roasting device is of a totally enclosed structure, is provided with 3-6 cyclones, and is provided with a preheating section and a roasting section, wherein the roasting temperature is 500-650 ℃, and the discharge temperature is 300-450 ℃.

The heat source of the suspension roasting device mainly comes from the waste heat of the flue gas of the electric furnace, the suspension roasting device is provided with a set of fuel system, and the combustion system is used for adjusting the temperature during roasting; and a part of the flue gas discharged by the suspension roasting device is used as a drying heat source of the hammer type crushing dryer, and the residual flue gas is discharged after being treated to reach the standard.

The magnesium oxide obtained by roasting the suspension roasting device directly enters a high-temperature high-pressure ball pressing system without cooling, and is subjected to circulating hot pressing at 400-600 ℃; the high-temperature high-pressure ball pressing system comprises a prepressing device and a high-pressure device, the linear pressure of the ball pressing machine is 80-110 kN/cm, a ball groove is almond-shaped or peach-core-shaped, and the capacity is 10-20 cm³。

The electric furnace smelting system is provided with a transformer above 4000kVA and an automatic electrode lifting device, the smelting temperature is above 3000 ℃, the electric furnace feeding and electrode lifting operations are automatically controlled, and the position of a furnace mouth is integrally sealed.

The MgO content of the produced fused magnesia is more than or equal to 99 percent, and the volume density is more than or equal to 3.55g/cm³。

The system for producing the fused magnesia by taking the magnesium hydroxide as the raw material comprises a filter cake storage bin, a box-type feeder, a hammer type crushing dryer, a suspension roasting device, a high-temperature high-pressure ball pressing system, a bucket elevator, an electric furnace feeding bin and an electric furnace smelting system; the discharge gate of filter cake storehouse links to each other with the feed inlet of box batcher, the feed inlet of hammer crushing dryer is connected to the discharge gate of box batcher, the feed inlet of suspension roasting device is connected to the discharge gate of hammer crushing dryer, the feed inlet of high temperature high pressure ball pressing system is connected to the discharge gate of suspension roasting device, the material loading end of bucket elevator is connected to the discharge gate of high temperature high pressure ball pressing system, the feed inlet in electric stove feed storehouse is connected to the discharge end of bucket elevator, the feed inlet of electric stove system of smelting is connected to the discharge gate in electric stove feed storehouse.

The suspension roasting device is provided with a flue gas outlet connected with a flue gas main pipe, the flue gas main pipe is connected with a drying air inlet of the hammer type crushing dryer through a flue gas conveying pipeline I, and is connected with a flue gas inlet of a flue gas purification system through a flue gas conveying pipeline II, and a clean flue gas outlet of the flue gas purification system is connected with a chimney; the flue gas main pipe is provided with a fan, and the first flue gas conveying pipeline and the second flue gas conveying pipeline are respectively provided with an adjusting valve; and a cold air inlet is also formed in the first flue gas conveying pipeline and is connected with a cold air pipeline, and an adjusting valve is also arranged on the cold air pipeline.

The electric furnace smelting system is provided with a flue gas outlet which is connected with a heat source inlet of the suspension roasting device through a flue gas pipeline.

Compared with the prior art, the invention has the beneficial effects that:

1) the invention combines the high-quality magnesium-rich raw material prepared from seawater or brine with the electric smelting process, compared with the traditional sintered magnesia or electric fused magnesia production process, the advantages of resources and processes are fully exerted, the magnesium hydroxide raw material is subjected to the process of drying, roasting to remove bound water, high-temperature ball pressing, electric furnace smelting and the like to prepare the high-quality electric fused magnesia product with high added value, the process is simple, the flow is short, the waste heat of flue gas is fully utilized, the device has good continuity and sealing property, the environmental pollution is small, and the energy-saving and environment-friendly benefits are obvious;

2) the box-type feeder can realize uniform and quantitative feeding by adjusting the height of the flashboard and the speed of the conveyer belt, and is suitable for feeding filter cakes with high viscosity and high humidity;

3) the hammer type crushing dryer integrates crushing and drying functions, and utilizes the waste heat of the flue gas of the suspension roasting device, thereby improving the subsequent suspension roasting efficiency and reducing the energy consumption;

4) the method adopts a suspension roasting device to remove the bound water of the magnesium hydroxide at the temperature of 500-650 ℃, and the lower the roasting temperature is, the smaller the size of the magnesium oxide grains obtained by decomposition is, and the better the high-temperature sintering performance after ball pressing is; the traditional magnesite two-step calcining method for producing magnesite products can produce active magnesium oxide only by light burning at about 900 ℃, magnesium hydroxide begins to decompose and dehydrate at about 300 ℃, and double vacancies can be produced after the dehydration of the hydrated magnesium hydroxide, so that the structure is loose, the defects are increased, and the magnesite products are beneficial to further smelting at high temperature;

5) the suspension roasting device is divided into two sections of preheating and roasting, so that the number of cyclones is reduced, and the suspension roasting device is simple in structure and convenient to operate; the heat source of the suspension roasting device is mainly from the waste heat of the flue gas of the electric furnace, and the flue gas discharged by the suspension roasting device can be used for the second time by the hammer type crushing dryer, so that the production cost and the energy consumption are reduced, and the energy conservation and consumption reduction are realized;

6) the suspension roasting device is not provided with a cooling cylinder and is roastedThe burnt magnesia is directly hot-pressed without cooling, the volume shrinkage of the cooled magnesia can be avoided, and the volume density of the formed ball can be improved by 0.1 to 0.3g/cm compared with the prior art³(ii) a A circulating ball pressing process (the crushed materials after being screened return to a system to press balls again) is adopted, so that the problem that the powder materials are difficult to form balls is solved, and the ball forming rate is improved;

7) the electric furnace smelting system adopts a special electric smelting magnesium transformer above 4000kVA and a novel energy-saving automatic electrode lifting device, so that the electric furnace smelting system has low power consumption, good operating environment and high automation degree in the smelting process;

8) the fused magnesia prepared by the process has high purity, good quality and volume density reaching 3.55g/cm³The sintered magnesite and seawater magnesite are superior to those sold in the market at present.

Drawings

Fig. 1 is a schematic structural diagram of a system for producing fused magnesia by using magnesium hydroxide as a raw material according to the present invention.

FIG. 2 is a process flow chart of the present invention for producing fused magnesia using magnesium hydroxide as a raw material.

In the figure: 1. filter cake storage bin 2, box feeder 3, hammer type crushing drier 4, suspension roasting device 5, high-temperature high-pressure ball pressing system 6, bucket elevator 7, electric furnace feeding bin 8, electric furnace smelting system 9, fan 10, regulating valve 11, flue gas purification system 12 and chimney

Detailed Description

The following further describes embodiments of the present invention with reference to the accompanying drawings:

as shown in figures 1 and 2, the process for producing fused magnesia by using magnesium hydroxide as a raw material comprises the steps of conveying a magnesium hydroxide filter cake prepared from seawater or brine into a hammer type crushing dryer 3 through a box feeder 2 for crushing and drying, conveying crushed and dried magnesium hydroxide powder into a suspension roasting device 4 along with drying air for preheating and roasting, conveying obtained magnesium oxide into a high-temperature high-pressure ball pressing system 5 for circulating hot pressing, storing obtained magnesium oxide balls into an electric furnace feeding bin 7 through a bucket elevator 6, and then conveying the magnesium oxide balls into an electric furnace smelting system 8 for smelting to prepare a fused magnesia product.

The hammer type crushing dryer 3 dries the material by using the waste heat of the flue gas of the suspension roasting device 4, and then the drying air returns to the suspension roasting device 4 again; the water content of the dried magnesium hydroxide fine powder is less than or equal to 5 percent.

The suspension roasting device 4 is of a totally enclosed structure and is provided with 3-6 cyclones, a preheating section and a roasting section, wherein the roasting temperature is 500-650 ℃, and the discharge temperature is 300-450 ℃.

The heat source of the suspension roasting device 4 mainly comes from the waste heat of the flue gas of the electric furnace, and the suspension roasting device 4 is provided with a set of fuel system which is used for adjusting the temperature during roasting; and a part of the flue gas discharged by the suspension roasting device 4 is used as a drying heat source of the hammer type crushing dryer 3, and the residual flue gas is discharged after being treated to reach the standard.

The magnesium oxide obtained by roasting in the suspension roasting device 4 directly enters a high-temperature high-pressure ball pressing system 5 without cooling, and is subjected to circulating hot pressing at 400-600 ℃; the high-temperature high-pressure ball pressing system 5 comprises a pre-pressing device and a high-pressure device, the linear pressure of the ball pressing machine is 80-110 kN/cm, a ball groove is almond-shaped or peach-core-shaped, and the capacity is 10-20 cm 3.

The electric furnace smelting system 8 is provided with a transformer above 4000kVA and an automatic electrode lifting device, the smelting temperature is above 3000 ℃, the electric furnace charging and electrode lifting operations are automatically controlled, and the position of a furnace mouth is integrally sealed.

The MgO content of the produced fused magnesia is more than or equal to 99 percent, and the volume density is more than or equal to 3.55g/cm 3.

As shown in fig. 1, the system for producing fused magnesia by using magnesium hydroxide as a raw material comprises a filter cake storage bin 1, a box-type feeder 2, a hammer type crushing dryer 3, a suspension roasting device 4, a high-temperature high-pressure ball pressing system 5, a bucket elevator 6, an electric furnace feeding bin 7 and an electric furnace smelting system 8; the discharge gate of filter cake silo 1 links to each other with box feeder 2's feed inlet, the feed inlet of hammer crushing dryer 3 is connected to box feeder 2's discharge gate, suspension roasting device 4's feed inlet is connected to hammer crushing dryer 3's discharge gate, high temperature high pressure ball pressing system 5's feed inlet is connected to suspension roasting device 4's discharge gate, bucket elevator 6's material loading end is connected to high temperature high pressure ball pressing system 5's discharge gate, electric stove feed bin 7's feed inlet is connected to bucket elevator 6's discharge end, electric stove melting system 8's feed inlet is connected to electric stove feed bin 7's discharge gate.

The suspension roasting device 4 is provided with a flue gas outlet connected with a flue gas main pipe, the flue gas main pipe is connected with a drying air inlet of the hammer type crushing dryer 3 through a flue gas conveying pipeline I, and is connected with a flue gas inlet of a flue gas purification system 11 through a flue gas conveying pipeline II, and a clean flue gas outlet of the flue gas purification system 11 is connected with a chimney 12; a fan 9 is arranged on the flue gas main pipe, and regulating valves 10 are respectively arranged on the first flue gas conveying pipeline and the second flue gas conveying pipeline; and a cold air inlet is also formed in the first flue gas conveying pipeline and connected with a cold air pipeline, and an adjusting valve 10 is also arranged on the cold air pipeline.

The electric furnace smelting system 8 is provided with a flue gas outlet and is connected with a heat source inlet of the suspension roasting device 4 through a flue gas pipeline.

In the invention, the box-type feeder 2 is suitable for conveying the magnesium hydroxide filter cake with high water content, and can automatically control and adjust the conveying amount. The hammer type crushing dryer 3 is provided with a wear-resistant and high-temperature-resistant hammer head, and can simultaneously crush and dry the magnesium hydroxide filter cake.

The flue gas discharged by the electric furnace smelting system 8 completely enters the suspension roasting device 4 to be used as a main heat source, the suspension roasting device 4 is provided with a set of combustion system, the flue gas of the suspension roasting device 4 is discharged by a fan 9 and then is adjusted by matching of adjusting valves 10 arranged on a first flue gas conveying pipeline and a second flue gas conveying pipeline, one part of the flue gas enters the hammer type crushing dryer 3, and the other part of the flue gas is treated by a flue gas purification system 11 and then is discharged from a chimney 12.

The process for producing the fused magnesia by using the magnesium hydroxide as the raw material comprises the following specific steps:

1) magnesium hydroxide filter cakes prepared from seawater or brine and stored in the filter cake storage bin 1 are fed and conveyed by a box-type feeder 2, and the feeding amount is adjustable;

2) feeding the magnesium hydroxide filter cake into a hammer type crushing dryer 3 for crushing and drying, wherein the drying temperature is 300-450 ℃, and mixing cold air into an adjusting valve 10 arranged on a cold air pipeline to adjust the temperature in the drying process to finally obtain magnesium hydroxide fine powder with the water content of less than or equal to 5%;

3) the fine magnesium hydroxide powder enters a suspension roasting device 4 along with drying air, the suspension roasting device 4 mainly utilizes the waste heat of flue gas of an electric furnace smelting system 8, and the roasting temperature is adjusted through a combustion system arranged on the suspension roasting device to ensure that the roasting temperature is 500-650 ℃;

4) the roasted magnesium oxide is collected and then directly sent into a closed high-temperature high-pressure ball pressing system 5 for cyclic hot pressing, after prepressing and high-pressure pressing, ball materials are sent into an electric furnace feeding bin 7 through a bucket elevator 6, and crushed materials return to the high-temperature high-pressure ball pressing system 5 to participate in pressing again. Fig. 1 shows a schematic of the circulating ball pressing mode, and the actual production process is not limited to this mode.

5) And feeding the ball material in the electric furnace feeding bin 7 into an electric furnace smelting system 8, and smelting, cooling and sorting to obtain an electric smelting magnesia product.

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be considered to be within the technical scope of the present invention, and the technical solutions and the inventive concepts thereof according to the present invention should be equivalent or changed within the scope of the present invention.