CN111348844B - System and process for preparing light-burned magnesia powder by using low-grade high-calcium magnesite - Google Patents

System and process for preparing light-burned magnesia powder by using low-grade high-calcium magnesite Download PDF

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CN111348844B
CN111348844B CN202010171513.4A CN202010171513A CN111348844B CN 111348844 B CN111348844 B CN 111348844B CN 202010171513 A CN202010171513 A CN 202010171513A CN 111348844 B CN111348844 B CN 111348844B
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ore
section
calcining
recovery device
spraying
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CN111348844A (en
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毕万利
胡智淇
关岩
赵九野
孙美硕
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Liaoning Keda Zhongchi Magnesium Building Material Technology Co ltd
University of Science and Technology Liaoning USTL
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Liaoning Keda Zhongchi Magnesium Building Material Technology Co ltd
University of Science and Technology Liaoning USTL
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    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2/00—Lime, magnesia or dolomite
    • C04B2/10—Preheating, burning calcining or cooling
    • C04B2/102—Preheating, burning calcining or cooling of magnesia, e.g. dead burning
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B32/00—Carbon; Compounds thereof
    • C01B32/50—Carbon dioxide
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B7/00—Halogens; Halogen acids
    • C01B7/01—Chlorine; Hydrogen chloride
    • C01B7/03—Preparation from chlorides
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B7/00—Halogens; Halogen acids
    • C01B7/01—Chlorine; Hydrogen chloride
    • C01B7/07—Purification ; Separation
    • C01B7/0743—Purification ; Separation of gaseous or dissolved chlorine
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2/00—Lime, magnesia or dolomite
    • C04B2/10—Preheating, burning calcining or cooling
    • C04B2/104—Ingredients added before or during the burning process
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27B—FURNACES, KILNS, OVENS, OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
    • F27B7/00—Rotary-drum furnaces, i.e. horizontal or slightly inclined
    • F27B7/02—Rotary-drum furnaces, i.e. horizontal or slightly inclined of multiple-chamber or multiple-drum type
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
    • F27D13/00—Apparatus for preheating charges; Arrangements for preheating charges
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
    • F27D17/00—Arrangements for using waste heat; Arrangements for using, or disposing of, waste gases
    • F27D17/004—Systems for reclaiming waste heat
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
    • F27D13/00—Apparatus for preheating charges; Arrangements for preheating charges
    • F27D2013/007—Apparatus for preheating charges; Arrangements for preheating charges using a rotary furnace
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00—Technologies related to metal processing
    • Y02P10/25—Process efficiency
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P20/00—Technologies relating to chemical industry
    • Y02P20/10—Process efficiency
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P20/00—Technologies relating to chemical industry
    • Y02P20/10—Process efficiency
    • Y02P20/129—Energy recovery, e.g. by cogeneration, H2recovery or pressure recovery turbines

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Organic Chemistry (AREA)
  • Ceramic Engineering (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Inorganic Chemistry (AREA)
  • Structural Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Materials Engineering (AREA)
  • Environmental & Geological Engineering (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Manufacture And Refinement Of Metals (AREA)
  • Compounds Of Alkaline-Earth Elements, Aluminum Or Rare-Earth Metals (AREA)
  • Furnace Details (AREA)

Abstract

The invention belongs to the technical field of magnesite development, and provides a system and a process for preparing light-burned magnesia powder by using low-grade high-calcium magnesite, wherein the system comprises an ore homogenizing pretreatment system, a two-section rotary kiln, a cooling waste heat recovery device, a hoister and a storage and packaging device which are sequentially connected: the ore homogenization pretreatment system carries out acid softening treatment to the ore, and two segmentation rotary kilns divide into the preheating section and calcine the section, calcine section top exhanst gas outlet and connect the preheating section feed inlet, make and calcine section high temperature flue gas heat and return and be used for preheating the feeding, and the heating ventilation pipe front end of preheating section still includes the device that sprays the ore modification. The invention utilizes two pretreatment processes to reduce the decomposition temperature of magnesium carbonate, effectively improve the conversion rate of magnesium oxide and reduce the content of free calcium oxide, simultaneously uses hot gas generated by high-temperature calcination and decomposition of ore for preheating treatment before ore calcination, reduces energy consumption and production cost, and reduces greenhouse effect through a carbon dioxide recovery device.

Description

System and process for preparing light-burned magnesia powder by using low-grade high-calcium magnesite
Technical Field
The invention relates to the technical field of magnesite development and utilization, in particular to a system and a process for preparing light-burned magnesia powder by using low-grade high-calcium magnesite.
Background
In recent years, the number of high-grade magnesite ores that can be directly used in the Liaoning area is gradually reduced, and due to economic reasons and lack of a proper mineral separation technology, a lot of mines directly discard low-grade magnesite in the mining process, so that a great deal of waste of ore resources is caused. It is understood that the price of magnesite ore containing more than 46% is 600 yuan/ton (2019), while magnesite ore containing less than 45% also has 60 yuan/ton, and a large amount of ore containing about 40% is treated as waste ore, while the low-grade ore accounts for more than 70% of the total reserves. At present, tailings are mainly treated by stacking greening, so that not only is resource waste caused, but also the environment is influenced, and building material utilization is a reasonable solution at present. However, the calcium content of tailings in the bridge region is high, and some tailings even reach more than 5%, free calcium oxide is generated after calcination, and when the calcium oxide is added into a magnesium cementing material system, the pH value is increased, gypsum is formed, the total hydration heat release amount is increased, the 517 phase is not favorably formed, and the strength is reduced. Therefore, the content of free calcium oxide in the magnesium gel material is strictly limited, and according to JC/T443-2000, the content of free calcium oxide in qualified products is less than 2.0 wt.%.
At present, the existing technical means for treating the high-calcium baume tailings has complex process and higher cost, wherein most of the high-calcium baume tailings are decalcified by adopting a flotation mode, CN104437883A adopts a digestion-desliming-reverse flotation method to treat magnesite, and the method needs to calcine, digest and then reverse flotation; CN110124851A adopts EDDHA to perform reverse flotation decalcification.
The reverse flotation mode for treating the tailings needs multiple times of flotation, has low efficiency and high cost, and is difficult to meet the requirement of treating a large amount of high-calcium tailings.
Disclosure of Invention
The invention aims to provide a system and a process for preparing light-burned magnesia powder from low-grade high-calcium magnesite without a reverse flotation process, wherein an ore homogenization pretreatment system and a spraying device designed by the system process the ore, the homogenization pretreatment system separately stores different batches of ore, and unloads the ore in proportion by unloaders in different homogenization grading boxes before calcination, so that the ore in different batches is uniformly proportioned, and the product composition is stable; the first spraying in the pretreatment system and the second spraying in the second-stage rotary kiln enable the magnesium carbonate to be easily decomposed in the subsequent calcining process, the magnesium carbonate decomposition temperature is effectively reduced, the magnesium oxide conversion rate is improved, the content of free calcium oxide is reduced, the calcining decomposition gas and the preheating treatment are combined, the energy consumption and the production cost are reduced, and the greenhouse effect is reduced through the carbon dioxide recovery device, so that the economic benefit is increased.
The invention has the technical scheme that a system for preparing light-burned magnesia powder by using low-grade high-calcium magnesite comprises an ore homogenization pretreatment system, a two-section rotary kiln, a cooling waste heat recovery device, a hoister and a storage packaging device; the ore homogenization pretreatment system is used for carrying out component homogenization, classification and softening treatment on low-grade high-calcium magnesite; the two-section rotary kiln is connected with the ore homogenization pretreatment system and is used for receiving the ores after the ore homogenization pretreatment system and calcining the modified ores; the cooling waste heat recovery device is connected with the two-section rotary kiln and is used for carrying out waste heat recovery treatment on the cold calcined ore; the hoister is used for conveying the ore treated by the cooling waste heat recovery device to the storage and packaging device; the two-section rotary kiln comprises a preheating section close to the feeding end and a calcining section connected with the preheating section, a flue heating ventilation pipe is arranged at the feeding front end of the preheating section, and a hot gas recovery device is arranged at the top of the discharging end of the calcining section: the export of dust recovery device and the discharge port of calcining section are connected to cooling waste heat recovery device feed inlet jointly.
The system provided by the invention integrates the pretreatment device, the calcining device, the cooling device and the material receiving device, avoids the flotation and reverse flotation processes with complex and low efficiency in the prior art, the designed calcining device is designed for a two-end kiln, a front preheating section close to the feeding uses hot flue gas generated by a rear high-temperature calcining section to preheat, so that heat is fully recovered and utilized, meanwhile, the ore is subjected to flue gas preheating treatment, the calcining time is shortened, and a one-time calcining method is adopted, so that the system is simple in process, high in efficiency, energy-saving, environment-friendly and energy-saving.
Further, the ore homogenization pretreatment system comprises a liquid storage tank, a first spraying device, a homogenization grading box, a discharge valve and a conveying belt; the liquid storage tank is connected with the first spraying device and used for containing liquid for softening low-grade high-calcium magnesite and spraying ores through the first spraying device; the homogenizing and grading box is positioned below the first spraying device and is used for separately storing and jointly discharging the crushed ores of different batches to achieve the effect of homogenizing the ores, wherein the stored ores receive the softening liquid sprayed by the first spraying device, and the fluctuation of the ingredients of the ores of different batches is large, so that the homogenization is needed for product stability; the discharge valve is located the homogenization classifying box bottom, and the conveyer belt is located the discharge valve below, and the ore is discharged to the conveyer belt through the discharge valve, then sends to two segmentation rotary kilns.
The ore homogenizing pretreatment system is arranged for pretreating low-grade high-calcium magnesite by acid and the like, softening the ore, and falling off the surface layer in the calcining process of the rotary kiln so as to improve the specific surface area of the reaction, reduce the time consumption in the heat transfer process and improve the calcining efficiency, thereby effectively improving the yield of magnesium oxide in the calcining process of the magnesite, improving the yield and reducing the energy consumption
Furthermore, the two-section rotary kiln is also provided with a storage bin, an ore discharger, a second spraying device, a spraying head, a tail gas dechlorination device, a carbon dioxide recovery device and a sealing heat insulation connecting device; the storage bin is used for containing ores conveyed by the ore homogenization pretreatment system; the ore discharger is arranged at the bottom of the storage bin and used for discharging the ores stored in the storage bin to the preheating section of the rotary kiln; the second spraying device and a spraying head connected with the second spraying device are arranged at the top of the kiln between the ore discharger and the flue heating ventilation pipe and are used for carrying out spraying modification treatment on the feeding materials; the sealing heat-insulating connecting device is arranged at the joint of the preheating section and the calcining section and comprises a spiral lifting device and a breathable isolating plate; the spiral lifting device is fixed with the calcining section and rotates along with the calcining section in the calcining process, and the preheating section and the calcining section are sealed and isolated from each other when the spiral lifting device descends; the gas-permeable isolation plate is arranged at the top of the spiral lifting device, one side of the preheating section is communicated with the tail gas dechlorination device, and the carbon dioxide recovery device is connected with the tail gas dechlorination device so as to respectively remove chlorine and carbon dioxide generated by calcination; one side of the calcining section is communicated with a blast aeration device to feed air and combustion gas into the calcining section.
The secondary spraying device is used for further modifying the ore so as to effectively reduce the decomposition temperature of magnesium carbonate and improve the yield of magnesium oxide. The tail gas dechlorination device and the carbon dioxide recovery device arranged on the top of the calcining furnace can recover carbon dioxide and chlorine to be used as chemical raw materials; the blast ventilation device feeds fuel gas and air required by combustion into the kiln body so as to enable the kiln body to reach the required temperature by combustion.
The addition of the chloride salt allows the magnesium carbonate to form Mg (OH) Cl at a lower temperature, with lower
Further, the cooling waste heat recovery device comprises a conveying pipeline, a conveying crawler belt, a water cooling device and waste heat recovery equipment; the conveying crawler is arranged in the conveying pipeline and used for receiving calcined ore discharged by the two-section rotary kiln and transferring the calcined ore to the elevator through the conveying pipeline, the water cooling device is arranged on the periphery of the conveying pipeline and used for cooling the calcined ore in the conveying pipeline, and the waste heat recovery equipment is used for recovering heat in the water cooling device; the elevator is provided with an elevating tank car; the storage and packaging device is provided with a finished product bin and a sealing packaging machine, the lifting tank car receives calcined ore transferred by the conveying crawler belt and then unloads the calcined ore to the finished product bin, and the sealing packaging machine carries out sealing packaging on the finished product bin.
The calcined ore falls back to the conveying crawler belt of the cooling waste heat recovery device under the action of gravity, and the design saves equipment and parts required by conveying between the devices.
The invention also provides a process for preparing light-burned magnesia powder from low-grade high-calcium magnesite by using the system, which comprises the following process steps:
1) ore pretreatment: crushing low-grade high-calcium magnesite into particles, then putting the particles into an ore homogenization pretreatment system, spraying the surfaces of the ore, standing for a period of time, and conveying the ore into a two-section rotary kiln;
2) the ore is fed into the kiln in a two-section rotary kiln, passes through a preheating section and reaches a calcining section through a middle sealing heat-insulation connecting device to be calcined;
3) the light-burned magnesia powder produced after the calcination of the calcination section of the two-section rotary kiln is transmitted to a cooling waste heat recovery device by gravity for cooling;
4) and the cooled light-burned magnesia powder is transmitted to a storage and packaging device through a lifter to be packaged.
Further, in the step 1), softening liquid in a liquid storage tank is sprayed to the surface of the ore in the homogenization and classification box through a first spraying device, wherein the softening liquid is malic acid or an acid solution with the pH value of less than 4, the concentration of the softening liquid is 1-5 wt.%, and the spraying amount is 1-3 wt.% of the mass of the ore; the low-grade high-calcium magnesite is raw ore with CaO content of 1-15 wt.% and MgO content of 38-45 wt.%; the size of the crushed ore is 1-20 mm.
Further, the step S2 includes the following steps:
s21: the storage bin receives the softened ore transferred by the conveyor belt, the softened ore is discharged to the opening of the kiln body through the ore discharger, and the second spraying device sprays the loaded magnesium chloride solution and/or ammonium chloride solution to the surface of the ore through the spraying head;
s22: the ore enters a calcining section through a preheating section to be calcined, hot gas generated in the calcining section enters a hot gas recovery device through negative pressure, dust sinks into a dust recovery device through gravity after being separated by the hot gas recovery device, and the hot gas is transmitted to a heating ventilation pipe communicated with a flue along a pipeline to preheat subsequent fed ore;
s23: after heat exchange is carried out between hot gas and fed ore, the cooled chlorine and carbon dioxide are discharged from an opening at the top of the kiln body and sequentially enter a tail gas dechlorinating device and a carbon dioxide recovery device so as to recover the chlorine and the carbon dioxide generated by calcination;
and S24, feeding the ore generated in the calcining section into a cooling waste heat recovery device through a connecting pipeline under the action of gravity.
Further, in the step S21, the concentration of the magnesium chloride/ammonium chloride solution is 1 to 5 wt.%, and the spraying amount is 1 to 3 wt.% of the mass of the ore; in the step 22, the calcination temperature in the calcination section of the two-section rotary kiln is 650-1200 ℃, and the calcination time of the ore in the calcination section is 1-3 hours.
Further, the heat exchange time of the feeding ore and the hot gas in the preheating section in the step S23 is 0.5-1 hour, and the temperature of the feeding ore and the hot gas after the heat exchange is at 200-300 ℃; the tail gas dechlorination device (16) adopts sodium thiosulfate particles or saturated solution to remove chlorine.
The process of the invention adopts malic acid to pretreat low-grade high-calcium magnesite, softens the ore, and leads the surface layer to fall off in the calcining process of the rotary kiln, thereby improving the specific surface area of the reaction, reducing the time consumption in the heat transfer process and improving the calcining efficiency. And the calcination process is controlled to obtain active magnesium oxide and less calcium oxide as much as possible. The initial decomposition temperature of magnesium carbonate is about 400 ℃, the severe decomposition temperature is about 640 ℃, the initial decomposition temperature of calcium carbonate is about 530 ℃, the severe decomposition temperature is about 910 ℃, but 850-900 ℃ is needed when magnesite is calcined. Meanwhile, the addition of the chlorine salt can enable the magnesium carbonate to form Mg (OH) Cl at a lower temperature, has a lower decomposition temperature, can effectively reduce the decomposition temperature of the magnesium carbonate and improve the yield of the magnesium oxide. The one-time calcination method is adopted, the process is simple, the efficiency is high, meanwhile, the energy is saved, the environment is protected, and the energy consumption is reduced.
Compared with the prior art, the invention has the beneficial effects that:
1) according to the invention, a pretreatment process is utilized, a small amount of weak acid is used for softening the ore, so that the ore is conveniently accelerated to transfer heat and decompose in the calcining process, and then the chloride is added to form an intermediate product with a low decomposition temperature, so that the decomposition temperature of magnesium carbonate is effectively reduced, the conversion rate of magnesium oxide can be effectively increased, and the content of free calcium oxide can be reduced;
2) the invention uses the high-heat gas generated by the decomposition of the calcining section for preheating the feed ore, reduces the energy consumption and the production cost, reduces the greenhouse effect by the carbon dioxide recovery device, and increases the economic benefit.
Drawings
These and/or other aspects and advantages of the present invention will become more apparent and more readily appreciated from the following detailed description of the embodiments of the invention, taken in conjunction with the accompanying drawings of which:
FIG. 1 is a schematic structural diagram of an ore homogenization pretreatment system for preparing light-burned magnesia powder from low-grade high-calcium magnesite according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of the system components and process flow for preparing light-burned magnesia powder from low-grade high-calcium magnesite according to an embodiment of the present invention;
FIG. 3 is a schematic structural view of a sealing and heat-insulating connecting device in an embodiment of the invention;
wherein:
a1-liquid storage tank, A2-spray device, A3-homogenizing classification box, A4-discharge valve, A5-conveyor belt, 1-two-section rotary kiln, 2-cooling waste heat recovery device, 3-elevator, 4-storage packing device, 11-storage bin, 12-ore discharger, 13-spray device, 14-spray head, 15-flue heating ventilation pipe, 16-tail gas dechlorination device, 17-carbon dioxide recovery device, 18-hot gas recovery device, 19-dust recovery device, 110-blast ventilation device, 111-sealing heat insulation connecting device, 112-spiral lifting device, 113-ventilation isolation plate, 21-conveying crawler belt, 22-water cooling system, 23-waste heat recovery device, 31-lifting tanker, tank car, 41-finished product bin and 42-sealing packaging machine.
Detailed Description
In order that those skilled in the art will better understand the present invention, the following detailed description of the invention is provided in conjunction with the accompanying drawings and the detailed description of the invention.
Example 1
A system for preparing light-burned magnesia powder by using low-grade high-calcium magnesite has a structure shown in figure 2, and comprises an ore homogenization pretreatment system A, a two-section rotary kiln 1, a cooling waste heat recovery device 2, a hoister 3 and a storage and packaging device 4; the specific structure and function of each part are as follows.
The ore homogenizing pretreatment system A is used for carrying out granularity homogenizing, grading and softening treatment on low-grade high-calcium magnesite, and is structurally shown as figure 1, and comprises a liquid storage tank A1, a first spraying device A2, a homogenizing and grading tank A3, a discharge valve A4 and a conveyor belt A5; the liquid storage tank A1 is connected with the first spraying device A2, and the liquid storage tank A1 is used for containing liquid for softening low-grade high-calcium magnesite and spraying the low-grade high-calcium magnesite through the first spraying device A2; the homogenizing and grading box A3 is positioned below the first spraying device A2, is used for homogenizing, grading and storing the crushed ore according to the granularity and receiving the softening liquid sprayed by the first spraying device A2; the discharge valve a4 is located at the bottom of the homogenising and classifying tank A3 and the conveyor belt a5 is located below the discharge valve a4, and the ore is discharged through the discharge valve a4 to the conveyor belt a5 and then to the two-stage rotary kiln 1.
The two-section rotary kiln 1 is connected with the ore homogenization pretreatment system A and is used for receiving the ores after the ore homogenization pretreatment system A and calcining the modified ores; the device comprises a storage bin 11, an ore discharger 12, a second spraying device 13, a spraying head 14, a flue heating ventilation pipe 15, a tail gas dechlorination device 16, a carbon dioxide recovery device 17, a hot gas recovery device 18, a connected dust recovery device 19, a sealing heat-insulating connecting device 111, a spiral lifting device 112 and a ventilating isolation plate 113. Wherein the bin 11 is arranged below the conveying path of the conveyor belt A5 and is used for containing ores conveyed by the ore homogenizing pretreatment system A; the ore discharger 12 is arranged at the bottom of the bin 11 and used for discharging ores contained in the bin 11 to a feeding opening of the rotary kiln, the two-section rotary kiln 1 is integrally divided into a preheating section close to a feeding end and a calcining section connected with the preheating section, and the second spraying device 13 and a spraying head 14 connected with the second spraying device are arranged at the top of the kiln at the rear end of the ore discharger 12 along the feeding direction and used for spraying and modifying the fed materials; the flue heating ventilation pipe 15 is arranged at the kiln top part at the rear end of the second spraying device 13 and the spraying head 14 connected with the second spraying device; the front end of the feed of the preheating section is provided with a flue heating ventilation pipe 15, the structural schematic diagram of a sealing heat-insulating connecting device 111 is shown as 2, the sealing heat-insulating connecting device is arranged at the connecting part of the preheating section and the calcining section and comprises a spiral lifting device 112 and a breathable isolating plate 113; the spiral lifting device 112 is fixed with the calcining section and rotates along with the calcining section in the calcining process, and seals and separates the preheating section and the calcining section when the spiral lifting device descends; the gas-permeable partition board 113 is arranged at the top of the spiral lifting device 112 and is communicated with the tail gas dechlorination device 16 at one side of the preheating section, and the carbon dioxide recovery device 17 is connected with the tail gas dechlorination device 16 so as to respectively remove chlorine and carbon dioxide generated by calcination; one side of the calcining section is communicated with a blast aeration device (110) to feed air and combustion gas into the calcining section; the top opening of the discharge end of the calcining section in the kiln is connected with the inlet of a hot gas recovery device 18, the outlet of the hot gas recovery device 18 is respectively connected with a dust recovery device 19 and a communicated flue heating ventilation pipe 15, and the outlet of the dust recovery device 19 and the discharge port of the calcining section are jointly connected to the feed inlet of a cooling waste heat recovery device 2.
The cooling waste heat recovery device 2 is connected with a solid discharge port at the calcining section of the two-section rotary kiln 1 and is used for carrying out waste heat recovery treatment on the cold calcined ore; comprises a conveying pipeline, a conveying crawler 21, a water cooling device 22 and a waste heat recovery device 23; the conveying crawler 21 is arranged in the conveying pipeline and used for receiving calcined ore discharged by the two-section rotary kiln 1 and transferring the calcined ore to the elevator through the conveying pipeline, the water cooling device 22 is arranged on the periphery of the conveying pipeline and used for cooling the calcined ore in the conveying pipeline, and the waste heat recovery device 23 is used for recovering heat in the water cooling device 22.
The elevator 3 is used for conveying the ore processed by the cooling waste heat recovery device 2 into the storage and packaging device 4 and is provided with an elevator tank car 31; the storage and packaging device 4 is provided with a finished product bin 41 and a sealing and packaging machine 42, the lifting tank car 31 receives the calcined ore transferred by the conveying crawler 21 and then discharges the calcined ore to the finished product bin 41, and the sealing and packaging machine 42 performs sealing and packaging on the finished product bin 41.
By utilizing the device, the process for preparing the light-burned magnesia powder from the low-grade high-calcium magnesite is implemented, and the low-grade high-calcium magnesite comprises the following components:
Figure BDA0002409351640000081
the method comprises the following steps:
1) and ore pretreatment: crushing low-grade high-calcium magnesite into particles with the size of 5mm, then putting the particles into an ore homogenization pretreatment system A, spraying malic acid with the concentration of 1 wt.% on the surface of the ore, wherein the spraying amount is 1 wt.% of the mass of the ore, standing for 24 hours, and then conveying the ore into a two-section rotary kiln;
2) and two-section rotary kiln treatment:
s21: after receiving the softened ore transferred by the conveyor belt A5, the storage bin 11 discharges the softened ore to the opening of the kiln body through the ore discharger 12, and the second spraying device 13 sprays the loaded magnesium chloride solution with the concentration of 5 wt.% onto the surface of the ore through the spraying head 14, wherein the weight of the magnesium chloride solution is 1 wt.% of the weight of the ore;
s22: the ore enters a calcining section from a preheating section through a sealing heat insulation connecting device 111 to be calcined, the calcining temperature is 850 ℃, the calcining time is 3 hours, flue gas generated by the calcining section is transmitted to the rear end of a kiln body along the kiln body, enters a hot gas recovery device 18 from an opening at the top of the kiln body through negative pressure, dust sinks into a dust recovery device 19 due to gravity after being separated by the hot gas recovery device 18 through the negative pressure, and hot gas is transmitted to a heating ventilation pipe 15 communicated with a flue along a pipeline to preheat subsequent feeding ore;
s23: the hot gas exchanges heat with the fed ore for 1 hour, the temperature of the preheated ore is 200 ℃, and then the preheated ore enters a calcining section through a sealing heat insulation connecting device to be calcined; the chlorine and the carbon dioxide after temperature reduction are discharged from an opening at the top of the kiln body and enter a tail gas dechlorinating device 16 and a carbon dioxide recovery device 17 in sequence so as to recover the chlorine and the carbon dioxide generated by calcination;
3) the light-burned magnesia powder produced after the calcination in the calcination section of the two-section rotary kiln and the dust in the dust recovery device 19 are transmitted to the cooling waste heat recovery device 2 by gravity for cooling;
4) and the cooled light-burned magnesia powder is transmitted to a storage and packaging device 4 through a lifter 3 to be packaged.
The properties of the prepared light-burned magnesia powder are as follows:
Figure BDA0002409351640000082
example 2
A process for preparing light-burned magnesia powder by using low-grade high-calcium magnesite, which utilizes the system in the embodiment 1, and the low-grade high-calcium magnesite comprises the following components:
Figure BDA0002409351640000091
the process flow is shown in fig. 2, and comprises the following process steps:
1) and ore pretreatment: crushing low-grade high-calcium magnesite into particles with the size of 5mm, then putting the particles into an ore homogenization pretreatment system A, spraying malic acid with the concentration of 1 wt.% on the surface of the ore, wherein the spraying amount is 1 wt.% of the mass of the ore, standing for 24 hours, and then conveying the ore into a two-section rotary kiln;
2) and two-section rotary kiln treatment:
s21: after receiving the softened ore transferred by the conveyor belt A5, the storage bin 11 discharges the softened ore to the opening of the kiln body through the ore discharger 12, and the second spraying device 13 sprays the loaded magnesium chloride solution with the concentration of 5 wt.% onto the surface of the ore through the spraying head 14, wherein the weight of the magnesium chloride solution is 1 wt.% of the weight of the ore;
s22: the ore enters a calcining section from a preheating section through a sealed heat insulation connecting device to be calcined, the calcining temperature is 1000 ℃, the calcining time is 3 hours, flue gas generated by the calcining section is transmitted to the rear end of a kiln body along the kiln body, enters a hot gas recovery device 18 from an opening at the top of the kiln body through negative pressure, dust sinks into a dust recovery device 19 due to gravity after being separated by the hot gas recovery device 18 through the negative pressure, and hot gas is transmitted to a heating ventilation pipe 15 communicated with a flue along a pipeline to preheat subsequent feeding ore;
s23: the hot gas exchanges heat with the fed ore, the heat exchange time is 1 hour, the ore is heated to 200 ℃ and then enters a calcining section through a sealing heat insulation connecting device to be calcined, and the cooled chlorine and carbon dioxide are discharged through an opening at the top of the kiln body and sequentially enter a tail gas dechlorinating device 16 and a carbon dioxide recovery device 17 so as to recover the chlorine and the carbon dioxide generated by calcining.
3) The light-burned magnesia powder produced after the calcination in the calcination section of the two-section rotary kiln and the dust in the dust recovery device 19 are transmitted to the cooling waste heat recovery device 2 by gravity for cooling;
4) and the cooled light-burned magnesia powder is transmitted to a storage and packaging device 4 through a lifter 3 to be packaged.
The properties of the prepared light-burned magnesia powder are as follows:
Figure BDA0002409351640000101
example 3
A process for preparing light-burned magnesia powder by using low-grade high-calcium magnesite, which utilizes the system in the embodiment 1, and the low-grade high-calcium magnesite comprises the following components:
Figure BDA0002409351640000102
the process flow is shown in fig. 2, and comprises the following process steps:
1) and ore pretreatment: crushing low-grade high-calcium magnesite into particles with the size of 5mm, then putting the particles into an ore homogenization pretreatment system A, spraying malic acid with the concentration of 1 wt.% on the surface of the ore, wherein the spraying amount is 1 wt.% of the mass of the ore, standing for 24 hours, and then conveying the ore into a two-section rotary kiln;
2) and two-section rotary kiln treatment:
s21: after receiving the softened ore transferred by the conveyor belt A5, the storage bin 11 discharges the softened ore to the opening of the kiln body through the ore discharger 12, and the second spraying device 13 sprays the loaded magnesium chloride solution with the concentration of 5 wt.% onto the surface of the ore through the spraying head 14, wherein the weight of the magnesium chloride solution is 1 wt.% of the weight of the ore;
s22: the ore enters a calcining section from the preheating section through a sealed heat insulation connecting device to be calcined, wherein the calcining temperature is 750 ℃, and the calcining time is 2 hours; flue gas generated in the calcining section is transmitted to the rear end of the kiln body along the kiln body, enters a hot gas recovery device 18 from an opening at the top of the kiln body through negative pressure, is separated by the hot gas recovery device 18 through the negative pressure, dust sinks into a dust recovery device 19 due to gravity, and the hot gas is transmitted to a heating ventilation pipe 15 communicated with a flue along a pipeline for preheating subsequent feeding ore;
s23: the hot gas exchanges heat with the feeding ore in the preheating section, the heat exchange time is 1 hour, the ore enters the calcining section through a sealing heat insulation connecting device after the temperature reaches 300 ℃, and is calcined, and the chlorine and the carbon dioxide after being cooled are discharged from the opening at the top of the kiln body and sequentially enter a tail gas dechlorinating device 16 and a carbon dioxide recovery device 17 so as to recover the chlorine and the carbon dioxide generated by calcining;
3) the light-burned magnesia powder produced after the calcination in the calcination section of the two-section rotary kiln and the dust in the dust recovery device 19 are transmitted to the cooling waste heat recovery device 2 by gravity for cooling;
4) and the cooled light-burned magnesia powder is transmitted to a storage and packaging device 4 through a lifter 3 to be packaged.
The properties of the prepared light-burned magnesia powder are as follows:
Figure BDA0002409351640000111
example 4
A process for preparing light-burned magnesia powder by using low-grade high-calcium magnesite, which utilizes the system in the embodiment 1, and the low-grade high-calcium magnesite comprises the following components:
Figure BDA0002409351640000112
the process flow is shown in fig. 2, and comprises the following process steps:
1) and ore pretreatment: crushing low-grade high-calcium magnesite into particles with the size of 5mm, then putting the particles into an ore homogenization pretreatment system A, spraying malic acid with the concentration of 1 wt.% on the surface of the ore, wherein the spraying amount is 1 wt.% of the mass of the ore, standing for 24 hours, and then conveying the ore into a two-section rotary kiln;
2) and two-section rotary kiln treatment:
s21: after receiving the softened ore transferred by the conveyor belt A5, the storage bin 11 discharges the softened ore to the opening of the kiln body through the ore discharger 12, and the second spraying device 13 sprays the loaded magnesium chloride solution with the concentration of 5 wt.% onto the surface of the ore through the spraying head 14, wherein the weight of the magnesium chloride solution is 1 wt.% of the weight of the ore;
s22: the ore enters a calcining section from a preheating section through a sealing heat insulation connecting device to be calcined, the calcining temperature is 850 ℃, the calcining time is 2 hours, flue gas generated by the calcining section is transmitted to the rear end of a kiln body along the kiln body, enters a hot gas recovery device 18 from an opening at the top of the kiln body through negative pressure, dust sinks into a dust recovery device 19 due to gravity after being separated by the hot gas recovery device 18 through the negative pressure, and hot gas is transmitted to a heating ventilation pipe 15 communicated with a flue along a pipeline to preheat subsequent feeding ore;
s23: the heat exchange between hot gas and the fed ore is carried out for 1 hour, the ore is preheated to 300 ℃, the ore enters a calcining section through a sealing heat insulation connecting device to be calcined, and the cooled chlorine and carbon dioxide are discharged from an opening at the top of a kiln body and sequentially enter a tail gas dechlorinating device 16 and a carbon dioxide recovery device 17 so as to recover the chlorine and the carbon dioxide generated by calcining
3) The light-burned magnesia powder produced after the calcination in the calcination section of the two-section rotary kiln and the dust in the dust recovery device 19 are transmitted to the cooling waste heat recovery device 2 by gravity for cooling;
4) and the cooled light-burned magnesia powder is transmitted to a storage and packaging device 4 through a lifter 3 to be packaged.
The properties of the prepared light-burned magnesia powder are as follows:
Figure BDA0002409351640000121
example 5
A process for preparing light-burned magnesia powder by using low-grade high-calcium magnesite, which utilizes the system in the embodiment 1, and the low-grade high-calcium magnesite comprises the following components:
Figure BDA0002409351640000122
the process flow is shown in fig. 2, and comprises the following process steps:
1) and ore pretreatment: crushing low-grade high-calcium magnesite into particles with the size of 5mm, then putting the particles into an ore homogenization pretreatment system A, spraying malic acid with the concentration of 1 wt.% on the surface of the ore, wherein the spraying amount is 1 wt.% of the mass of the ore, standing for 24 hours, and then conveying the ore into a two-section rotary kiln;
2) and two-section rotary kiln treatment:
s21: after receiving the softened ore transferred by the conveyor belt A5, the storage bin 11 discharges the softened ore to the opening of the kiln body through the ore discharger 12, and the second spraying device 13 sprays the loaded magnesium chloride solution with the concentration of 5 wt.% onto the surface of the ore through the spraying head 14, wherein the weight of the magnesium chloride solution is 1 wt.% of the weight of the ore;
s22: the ore enters a calcining section from a preheating section through a sealing heat insulation connecting device to be calcined, the calcining temperature is 650 ℃, the calcining time is 2 hours, flue gas generated by the calcining section is transmitted to the rear end of a kiln body along the kiln body, enters a hot gas recovery device 18 from an opening at the top of the kiln body through negative pressure, dust sinks into a dust recovery device 19 due to gravity after being separated by the hot gas recovery device 18 through the negative pressure, and hot gas is transmitted to a heating ventilation pipe 15 communicated with a flue along a pipeline to preheat subsequent feeding ore;
s23: the hot gas exchanges heat with the fed ore, the heat exchange time is 1 hour, the ore enters a calcining section through a sealing heat insulation connecting device after reaching 300 ℃ and is calcined, and the cooled chlorine and carbon dioxide are discharged through an opening at the top of the kiln body and sequentially enter a tail gas dechlorinating device 16 and a carbon dioxide recovery device 17 so as to recover the chlorine and the carbon dioxide generated by calcining;
3) the light-burned magnesia powder produced after the calcination in the calcination section of the two-section rotary kiln and the dust in the dust recovery device 19 are transmitted to the cooling waste heat recovery device 2 by gravity for cooling;
4) and the cooled light-burned magnesia powder is transmitted to a storage and packaging device 4 through a lifter 3 to be packaged.
The properties of the prepared light-burned magnesia powder are as follows:
Figure BDA0002409351640000131
example 6
A process for preparing light-burned magnesia powder by using low-grade high-calcium magnesite, which utilizes the system in the embodiment 1, and the low-grade high-calcium magnesite comprises the following components:
Figure BDA0002409351640000132
the process flow is shown in fig. 2, and comprises the following process steps:
1) and ore pretreatment: crushing low-grade high-calcium magnesite into particles with the size of 5mm, then putting the particles into an ore homogenization pretreatment system A, spraying malic acid with the concentration of 1 wt.% on the surface of the ore, wherein the spraying amount is 1 wt.% of the mass of the ore, standing for 24 hours, and then conveying the ore into a two-section rotary kiln;
2) and two-section rotary kiln treatment:
s21: after receiving the softened ore transferred by the conveyor belt A5, the storage bin 11 discharges the softened ore to the opening of the kiln body through the ore discharger 12, and the second spraying device 13 sprays the loaded magnesium chloride solution with the concentration of 5 wt.% onto the surface of the ore through the spraying head 14, wherein the weight of the magnesium chloride solution is 1 wt.% of the weight of the ore;
s22: the ore enters a calcining section from a preheating section through a sealing heat insulation connecting device to be calcined, the calcining temperature is 650 ℃, the calcining time is 3 hours, flue gas generated by the calcining section is transmitted to the rear end of a kiln body along the kiln body, enters a hot gas recovery device 18 from an opening at the top of the kiln body through negative pressure, dust sinks into a dust recovery device 19 due to gravity after being separated by the hot gas recovery device 18 through the negative pressure, and hot gas is transmitted to a heating ventilation pipe 15 communicated with a flue along a pipeline to preheat subsequent feeding ore;
s23: the hot gas exchanges heat with the feeding ore, the ore reaches 300 ℃ after being preheated for 1 hour, the ore continues to enter a calcining section through a sealing heat insulation connecting device to be calcined, and the chlorine gas and the carbon dioxide after being cooled are discharged from an opening at the top of the kiln body and sequentially enter a tail gas dechlorinating device 16 and a carbon dioxide recovery device 17 so as to recover the chlorine gas and the carbon dioxide generated by calcining;
3) the light-burned magnesia powder produced after the calcination in the calcination section of the two-section rotary kiln and the dust in the dust recovery device 19 are transmitted to the cooling waste heat recovery device 2 by gravity for cooling;
4) and the cooled light-burned magnesia powder is transmitted to a storage and packaging device 4 through a lifter 3 to be packaged.
The properties of the prepared light-burned magnesia powder are as follows:
Figure BDA0002409351640000141
example 7
The low-grade high-calcium magnesite comprises the following components:
Figure BDA0002409351640000142
a process for preparing light-burned magnesia powder by using low-grade high-calcium magnesite by using the system in the embodiment 1, wherein the process flow is shown as a figure 2, and the process comprises the following process steps:
1) and ore pretreatment: crushing low-grade high-calcium magnesite into particles with the size of 5mm, then putting the particles into an ore homogenization pretreatment system A, spraying malic acid with the concentration of 1 wt.% on the surface of the ore, wherein the spraying amount is 1 wt.% of the mass of the ore, standing for 24 hours, and then conveying the ore into a two-section rotary kiln;
2) and two-section rotary kiln treatment:
s21: after receiving the softened ore transferred by the conveyor belt A5, the storage bin 11 discharges the softened ore to the opening of the kiln body through the ore discharger 12, and the second spraying device 13 sprays the loaded magnesium chloride solution with the concentration of 5 wt.% onto the surface of the ore through the spraying head 14, wherein the weight of the magnesium chloride solution is 1 wt.% of the weight of the ore;
s22: the ore enters a calcining section through a preheating section to be calcined, the calcining temperature is 850 ℃, and the calcining time is 1 hour; flue gas generated in the calcining section is transmitted to the rear end of the kiln body along the kiln body, enters a hot gas recovery device 18 from an opening at the top of the kiln body through negative pressure, is separated by the hot gas recovery device 18 through the negative pressure, dust sinks into a dust recovery device 19 due to gravity, and the hot gas is transmitted to a heating ventilation pipe 15 communicated with a flue along a pipeline for preheating subsequent feeding ore;
s23: the hot gas exchanges heat with the fed ore, the heat exchange time is 1 hour, the temperature of the ore is raised to 300 ℃, and the cooled chlorine and carbon dioxide are discharged from the opening at the top of the kiln body and enter a tail gas dechlorinating device 16 and a carbon dioxide recovery device 17 in sequence so as to recover the chlorine and carbon dioxide generated by calcination;
3) the light-burned magnesia powder produced after the calcination in the calcination section of the two-section rotary kiln is transmitted to a cooling waste heat recovery device 2 for cooling through gravity;
4) and the cooled light-burned magnesia powder is transmitted to a storage and packaging device 4 through a lifter 3 to be packaged.
The properties of the prepared light-burned magnesia powder are as follows:
Figure BDA0002409351640000151
example 8
The low-grade high-calcium magnesite comprises the following components:
Figure BDA0002409351640000152
a process for preparing light-burned magnesia powder by using low-grade high-calcium magnesite by using the system in the embodiment 1, wherein the process flow is shown as a figure 2, and the process comprises the following process steps:
1) and ore pretreatment: crushing low-grade high-calcium magnesite into particles with the size of 5mm, then putting the particles into an ore homogenization pretreatment system A, spraying malic acid with the concentration of 1 wt.% on the surface of the ore, wherein the spraying amount is 1 wt.% of the mass of the ore, standing for 24 hours, and then conveying the ore into a two-section rotary kiln;
2) and treating in a two-section rotary kiln:
s21: after receiving the softened ore transferred by the conveyor belt A5, the storage bin 11 discharges the softened ore to the opening of the kiln body through the ore discharger 12, and the second spraying device 13 sprays the loaded magnesium chloride solution with the concentration of 5 wt.% onto the surface of the ore through the spraying head 14, wherein the weight of the magnesium chloride solution is 1 wt.% of the weight of the ore;
s22: the ore enters a calcining section through a preheating section to be calcined, the calcining temperature is 1200 ℃, the calcining time is 1 hour, flue gas generated by the calcining section is transmitted to the rear end of a kiln body along the kiln body, enters a hot gas recovery device 18 from an opening at the top of the kiln body through negative pressure, dust sinks to enter a dust recovery device 19 through gravity after being separated by the hot gas recovery device 18 through the negative pressure, and the hot gas is transmitted to a heating ventilation pipe 15 communicated with a flue along a pipeline to be used for preheating the subsequent feeding ore;
s23: the heat exchange between the hot gas and the fed ore is carried out for 1 hour, the ore is heated to 300 ℃, and the cooled chlorine and carbon dioxide are discharged from the opening at the top of the kiln body and enter a tail gas dechlorinating device 16 and a carbon dioxide recovery device 17 in sequence to recover the chlorine and carbon dioxide generated by calcination;
3) the light-burned magnesia powder produced after the calcination in the calcination section of the two-section rotary kiln is transmitted to a cooling waste heat recovery device 2 for cooling through gravity;
4) and the cooled light-burned magnesia powder is transmitted to a storage and packaging device 4 through a lifter 3 to be packaged.
The properties of the prepared light-burned magnesia powder are as follows:
Figure BDA0002409351640000161
example 9
The low-grade high-calcium magnesite comprises the following components:
Figure BDA0002409351640000162
a process for preparing light-burned magnesia powder by using low-grade high-calcium magnesite by using the system in the embodiment 1, wherein the process flow is shown as a figure 2, and the process comprises the following process steps:
1) and ore pretreatment: crushing low-grade high-calcium magnesite into particles with the size of 5mm, then putting the particles into an ore homogenization pretreatment system A, spraying malic acid with the concentration of 1 wt.% on the surface of the ore, wherein the spraying amount is 1 wt.% of the mass of the ore, standing for 24 hours, and then conveying the ore into a two-section rotary kiln;
2) and two-section rotary kiln treatment:
s21: the storage bin 11 receives the softened ore transferred by the conveyor belt A5, and then the softened ore is discharged to the opening of the kiln body through the ore discharger 12;
s22: the ore enters a calcining section through a preheating section to be calcined, the calcining temperature is 650 ℃, the calcining time is 3 hours, flue gas generated by the calcining section is transmitted to the rear end of a kiln body along the kiln body, enters a hot gas recovery device 18 from an opening at the top of the kiln body through negative pressure, dust sinks to enter a dust recovery device 19 through gravity after being separated by the hot gas recovery device 18 through the negative pressure, and the hot gas is transmitted to a heating ventilation pipe 15 communicated with a flue along a pipeline to be used for preheating the subsequent feeding ore;
s23: the hot gas exchanges heat with the fed ore, the heat exchange time is 1 hour, the temperature of the ore is raised to 300 ℃, and the cooled chlorine and carbon dioxide are discharged from the opening at the top of the kiln body and enter a tail gas dechlorinating device 16 and a carbon dioxide recovery device 17 in sequence so as to recover the chlorine and carbon dioxide generated by calcination;
3) the light-burned magnesia powder produced after the calcination in the calcination section of the two-section rotary kiln is transmitted to a cooling waste heat recovery device 2 for cooling through gravity;
4) and the cooled light-burned magnesia powder is transmitted to a storage and packaging device 4 through a lifter 3 to be packaged.
The properties of the prepared light-burned magnesia powder are as follows:
Figure BDA0002409351640000171
example 10
The low-grade high-calcium magnesite comprises the following components:
Figure BDA0002409351640000172
a process for preparing light-burned magnesia powder by using low-grade high-calcium magnesite by using the system in the embodiment 1, wherein the process flow is shown as a figure 2, and the process comprises the following process steps:
1) and ore pretreatment: crushing low-grade high-calcium magnesite into particles with the size of 5mm, then putting the particles into an ore homogenization pretreatment system A, and conveying the particles into a two-section rotary kiln;
2) and two-section rotary kiln treatment:
s21: after receiving the softened ore transferred by the conveyor belt A5, the storage bin 11 discharges the softened ore to the opening of the kiln body through the ore discharger 12, and the second spraying device 13 sprays the loaded magnesium chloride solution with the concentration of 5 wt.% onto the surface of the ore through the spraying head 14, wherein the weight of the magnesium chloride solution is 1 wt.% of the weight of the ore;
s22: the ore enters a calcining section through a preheating section to be calcined, wherein the calcining temperature is 650 ℃, and the calcining time is 3 hours; flue gas generated in the calcining section is transmitted to the rear end of the kiln body along the kiln body, enters a hot gas recovery device 18 from an opening at the top of the kiln body through negative pressure, is separated by the hot gas recovery device 18 through the negative pressure, dust sinks into a dust recovery device 19 due to gravity, and the hot gas is transmitted to a heating ventilation pipe 15 communicated with a flue along a pipeline for preheating subsequent feeding ore;
s23: the temperature of the ore is raised to 300 ℃ after heat exchange between hot gas and the fed ore for 1 hour, and chlorine and carbon dioxide after temperature reduction are discharged from an opening at the top of the kiln body and enter a tail gas dechlorinating device 16 and a carbon dioxide recovery device 17 in sequence to recover the chlorine and the carbon dioxide generated by calcination;
3) the light-burned magnesia powder produced after the calcination in the calcination section of the two-section rotary kiln is transmitted to a cooling waste heat recovery device 2 for cooling through gravity;
4) and the cooled light-burned magnesia powder is transmitted to a storage and packaging device 4 through a lifter 3 to be packaged.
The properties of the prepared light-burned magnesia powder are as follows:
Figure BDA0002409351640000181
example 11
The low-grade high-calcium magnesite comprises the following components:
Figure BDA0002409351640000182
a process for preparing light-burned magnesia powder by using low-grade high-calcium magnesite by using the system in the embodiment 1, wherein the process flow is shown as a figure 2, and the process comprises the following process steps:
1) and ore pretreatment: crushing low-grade high-calcium magnesite into particles with the size of 5mm, then putting the particles into an ore homogenization pretreatment system A, and conveying the particles into a two-section rotary kiln;
2) and two-section rotary kiln treatment:
s21: the storage bin 11 receives the softened ore transferred by the conveyor belt A5, and then the softened ore is discharged to the opening of the kiln body through the ore discharger 12;
s22: the ore enters a calcining section through a preheating section to be calcined, wherein the calcining temperature is 650 ℃, and the calcining time is 1 hour; flue gas generated in the calcining section is transmitted to the rear end of the kiln body along the kiln body, enters a hot gas recovery device 18 from an opening at the top of the kiln body through negative pressure, is separated by the hot gas recovery device 18 through the negative pressure, dust sinks into a dust recovery device 19 due to gravity, and the hot gas is transmitted to a heating ventilation pipe 15 communicated with a flue along a pipeline for preheating subsequent feeding ore;
s23: the ore reaches 300 ℃ after heat exchange is carried out on hot gas and feeding ore for 1 hour, and chlorine and carbon dioxide after temperature reduction are discharged from an opening at the top of the kiln body and enter a tail gas dechlorinating device 16 and a carbon dioxide recovery device 17 in sequence so as to recover the chlorine and the carbon dioxide generated by calcination;
3) the light-burned magnesia powder produced after the calcination in the calcination section of the two-section rotary kiln is transmitted to a cooling waste heat recovery device 2 for cooling through gravity;
4) and the cooled light-burned magnesia powder is transmitted to a storage and packaging device 4 through a lifter 3 to be packaged.
The properties of the prepared light-burned magnesia powder are as follows:
Figure BDA0002409351640000191
comparative example 1
The low-grade high-calcium magnesite comprises the following components:
Figure BDA0002409351640000192
the method is characterized in that the shaft kiln in the prior art is used for calcining the material, and comprises the following process steps:
1) placing the ore raw material with the particle size of 50mm into a shaft kiln;
2) calcining at 850-900 deg.c for 4 hr;
3) discharging the light-burned magnesium oxide in the shaft kiln through a discharge opening, and naturally cooling;
4) cooling, sealing and packaging.
The properties of the prepared light-burned magnesia powder are as follows:
Figure BDA0002409351640000193
comparative example 2
The low-grade high-calcium magnesite comprises the following components:
Figure BDA0002409351640000201
the method is characterized in that the shaft kiln in the prior art is used for calcining the material, and comprises the following process steps:
1) placing the ore raw material with the particle size of 50mm into a shaft kiln;
2) calcining at 1050 ℃ for 4 hours at 1000-;
3) discharging the light-burned magnesium oxide in the shaft kiln through a discharge opening, and naturally cooling;
4) cooling, sealing and packaging.
The properties of the prepared light-burned magnesia powder are as follows:
Figure BDA0002409351640000202
the important process parameters and the properties of the products obtained in examples 1 to 11 according to the invention and comparative examples 1 to 2 are shown in table 1 below:
TABLE 1 Processes and product Properties of examples 1-11 and comparative examples
Figure BDA0002409351640000211
In the above table, as can be seen from the comparison between examples 1 to 8 and examples 9 to 11, the yield of magnesium oxide in the magnesite calcining process can be effectively improved by two pretreatment processes, so that the calcining efficiency is greatly improved, the yield is improved, and the energy consumption is reduced.
As can be seen from the comparison between examples 1-8 and comparative examples 1-2, the calcination method provided by the invention has the advantages that compared with light-calcined magnesia produced by the traditional calcination process, the calcination time at the same temperature is shorter, the temperature for obtaining the magnesia with the same activity is lower, the calcination efficiency is higher, the yield is improved, and the energy consumption is reduced.
Having described embodiments of the present invention, the foregoing description is intended to be exemplary, not exhaustive, and not limited to the embodiments disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims (7)

1. A system for preparing light-burned magnesia powder by using low-grade high-calcium magnesite is characterized by comprising an ore homogenizing pretreatment system (A), a two-section rotary kiln (1), a cooling waste heat recovery device (2), a hoister (3) and a storage packing device (4);
the ore homogenization pretreatment system (A) is used for carrying out component homogenization and softening treatment on low-grade high-calcium magnesite;
the two-section rotary kiln (1) is connected with the ore homogenization pretreatment system (A) and is used for receiving the ores after the ore homogenization pretreatment system (A), and preheating and calcining the modified ores;
the cooling waste heat recovery device (2) is connected with the two-section rotary kiln (1) and is used for carrying out waste heat recovery treatment on the calcined ore;
the hoister (3) is used for conveying the ore treated by the cooling waste heat recovery device (2) into the storage and packing device (4);
the two-section rotary kiln (1) comprises a preheating section close to a feeding end and a calcining section connected with the preheating section, a flue heating ventilation pipe (15) is arranged at the feeding front end of the preheating section, and a hot gas recovery device (18) is arranged at the top of a discharging end of the calcining section: the top of the discharge end is connected with an inlet of a hot gas recovery device (18), an outlet of the hot gas recovery device (18) is respectively connected with a dust recovery device (19) and a communicated flue heating ventilation pipe (15), and an outlet of the dust recovery device (19) and a discharge port of the calcining section are jointly connected to a feed inlet of a cooling waste heat recovery device (2);
the ore homogenization pretreatment system (A) comprises a liquid storage tank (A1), a first spraying device (A2), a homogenization and classification box (A3), a discharge valve (A4) and a conveyor belt (A5);
the liquid storage tank (A1) is connected with the first spraying device (A2), the liquid storage tank (A1) is used for containing liquid for softening low-grade high-calcium magnesite, and the ore is sprayed by the first spraying device (A2);
the homogenizing and grading box (A3) is positioned below the first spraying device (A2) and is used for separately storing and jointly discharging different batches of ores so as to achieve the effect of homogenizing the components of the ores, and the ores in the homogenizing and grading box (A3) receive the softening liquid sprayed by the first spraying device (A2);
the discharge valve (A4) is positioned at the bottom of the homogenizing and grading box (A3), the conveyor belt (A5) is positioned below the discharge valve (A4), and the ore is discharged to the conveyor belt (A5) through the discharge valve (A4) and then is sent to the two-section rotary kiln (1);
the two-section rotary kiln (1) also comprises a storage bin (11), an ore discharger (12), a second spraying device (13), a spraying head (14), a tail gas dechlorination device (16), a carbon dioxide recovery device (17) and a sealing heat insulation connecting device (111);
the bin (11) is used for containing ores conveyed by the ore homogenization pretreatment system (A); the ore discharger (12) is arranged at the bottom of the storage bin (11) and is used for discharging the ore contained in the storage bin (11) to the preheating section of the rotary kiln;
the second spraying device (13) and a spraying head (14) connected with the second spraying device are arranged at the top of the kiln between the ore discharger (12) and the flue heating ventilation pipe (15) and are used for carrying out spraying modification treatment on the feeding materials;
the sealing and heat-insulating connecting device (111) is arranged at the joint of the preheating section and the calcining section and comprises a spiral lifting device (112) and a gas-permeable isolating plate (113);
the spiral lifting device (112) is fixed with the calcining section and rotates along with the calcining section in the calcining process, and the preheating section and the calcining section realize mutual air sealing and heat sealing separation through feeding;
the gas-permeable isolation plates (113) are arranged on two sides of the top of the spiral lifting device (112), and are communicated with the tail gas dechlorination device (16) on one side of the preheating section, and the carbon dioxide recovery device (17) is connected with the tail gas dechlorination device (16) to respectively remove chlorine and carbon dioxide generated by calcination; the air-permeable partition plate (113) is communicated with the air-blowing and ventilating device (110) at one side of the calcining section so as to feed air and combustion gas into the calcining section;
the liquid for softening the low-grade high-calcium magnesite stored in the liquid storage tank (A1) is softening liquid, and the softening liquid is malic acid or an acid solution with the pH value less than 4;
the solution loaded by the second spraying device (13) is a magnesium chloride solution and/or an ammonium chloride solution.
2. The system for preparing light-burned magnesia powder by using low-grade high-calcium magnesite according to claim 1,
the cooling waste heat recovery device (2) comprises a conveying pipeline, a conveying crawler belt (21), a water cooling device (22) and waste heat recovery equipment (23); the conveying crawler belt (21) is arranged in the conveying pipeline and used for receiving calcined ore discharged by the two-section rotary kiln (1) and transferring the calcined ore to the elevator through the conveying pipeline, the water cooling device (22) is arranged on the periphery of the conveying pipeline and used for cooling the calcined ore in the conveying pipeline, and the waste heat recovery equipment (23) is used for recovering heat in the water cooling device (22);
the lifting machine (3) is provided with a lifting tanker (31); the storage and packaging device (4) is provided with a finished product bin (41) and a sealing packaging machine (42), the lifting tank car (31) receives calcined ore transferred by the conveying crawler (21), then the calcined ore is discharged to the finished product bin (41), and the sealing packaging machine (42) carries out sealing packaging on the finished product bin (41).
3. A process for preparing light-burned magnesia powder by using low-grade high-calcium magnesite, which is characterized in that the system for preparing light-burned magnesia powder by using low-grade high-calcium magnesite as claimed in any one of claims 1-2 comprises the following process steps:
1) ore pretreatment: crushing low-grade high-calcium magnesite into particles, then putting the particles into an ore homogenization pretreatment system (A), spraying the surfaces of the ore, standing for a period of time, and conveying the ore into a two-section rotary kiln;
2) in the two-section rotary kiln, ores are fed into the kiln, are sprayed by the modifying liquid when passing through the second spraying device (13), then reach the calcining section through the sealing and heat-insulating connecting device of the preheating section for calcining, and after the ores enter the calcining section to reach a certain height, the upper part of the spiral lifting device (112) is contacted with the ores in the kiln, so that air sealing and heat insulation are formed between the preheating section and the calcining section;
3) the light-burned magnesia powder produced after the calcination in the calcination section of the two-section rotary kiln is transmitted to a cooling waste heat recovery device (2) for cooling through gravity;
4) and the cooled light-burned magnesia powder is transmitted to a storage and packaging device (4) through a lifter (3) for packaging.
4. The process for preparing light-burned magnesia powder by using low-grade high-calcium magnesite according to claim 3,
in the step 1), softening liquid in a liquid storage tank (A1) is sprayed to the surface of ore in a homogenization and classification tank (A3) through a first spraying device (A2), wherein the concentration of the softening liquid is 1-5 wt%, and the spraying amount is 1-3 wt% of the mass of the ore;
the low-grade high-calcium magnesite is raw ore with CaO content of 1-15 wt.% and MgO content of 38-45 wt.%;
the size of the crushed ore is 1-20 mm.
5. The process for preparing light-burned magnesia powder by using low-grade high-calcium magnesite according to claim 3, wherein the process comprises the following steps:
the step 2) comprises the following steps:
s21: the storage bin (11) receives the softened ore transferred by the conveyor belt (A5), and then the softened ore is discharged to the opening of the kiln body through the ore discharger (12), and the second spraying device (13) sprays the loaded magnesium chloride solution and/or ammonium chloride solution to the surface of the ore through the spraying head (14);
s22: the ore enters a calcining section through a preheating section to be calcined, hot gas generated in the calcining section enters a hot gas recovery device (18) through negative pressure, after being separated by the hot gas recovery device (18), dust sinks into a dust recovery device (19) through gravity, and the hot gas is transmitted to a heating ventilation pipe (15) communicated with a flue along a pipeline to preheat the ore fed subsequently;
s23: after heat exchange is carried out between hot gas and fed ore, the hot gas cools the ore and heats up, and chlorine and carbon dioxide after cooling are discharged through a breathable isolation plate (113) at the top of the kiln body and sequentially enter a tail gas dechlorinating device (16) and a carbon dioxide recovery device (17) so as to recover the chlorine and the carbon dioxide generated by calcination;
s24, feeding the ore generated in the calcining section into a cooling waste heat recovery device (2) through a connecting pipeline under the action of gravity.
6. The process for preparing light-burned magnesia powder by using low-grade high-calcium magnesite according to claim 5, wherein the process comprises the following steps:
in the step S21, the concentration of the magnesium chloride/ammonium chloride solution is 1-5 wt.%, and the spraying amount is 1-3 wt.% of the mass of the ore; in step S22, the calcination temperature in the calcination section of the two-section rotary kiln is 650-1200 ℃, and the calcination time of the ore in the calcination section is 1-3 hours.
7. The process for preparing light-burned magnesia powder by using low-grade high-calcium magnesite according to claim 5, wherein the process comprises the following steps: in the step S23, the heat exchange time of the feeding ore and the hot gas in the preheating section is 0.5-1 hour, and the temperature of the feeding ore after the heat exchange with the hot gas is 200-300 ℃; the tail gas dechlorination device (16) adopts sodium thiosulfate particles or saturated solution to remove chlorine.
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