CN113883898A - Suspension calcining device and process suitable for high-iron-content kaolin raw material - Google Patents

Suspension calcining device and process suitable for high-iron-content kaolin raw material Download PDF

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Publication number
CN113883898A
CN113883898A CN202111202559.9A CN202111202559A CN113883898A CN 113883898 A CN113883898 A CN 113883898A CN 202111202559 A CN202111202559 A CN 202111202559A CN 113883898 A CN113883898 A CN 113883898A
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furnace
cyclone separator
oxidation
raw material
preheating
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王彬
隋同波
彭学平
代中元
武晓萍
陈昌华
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Tianjin Cement Industry Design and Research Institute Co Ltd
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Tianjin Cement Industry Design and Research Institute Co Ltd
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    • 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
    • F27B19/00—Combinations of furnaces of kinds not covered by a single preceding main group
    • F27B19/04—Combinations of furnaces of kinds not covered by a single preceding main group arranged for associated working
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B33/00—Silicon; Compounds thereof
    • C01B33/20—Silicates
    • C01B33/36—Silicates having base-exchange properties but not having molecular sieve properties
    • C01B33/38—Layered base-exchange silicates, e.g. clays, micas or alkali metal silicates of kenyaite or magadiite type
    • C01B33/40—Clays
    • 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
    • F27D17/008—Arrangements for using waste heat; Arrangements for using, or disposing of, waste gases cleaning gases
    • 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
    • F27D3/00—Charging; Discharging; Manipulation of charge
    • F27D3/0033—Charging; Discharging; Manipulation of charge charging of particulate material
    • 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
    • F27D7/00—Forming, maintaining, or circulating atmospheres in heating chambers
    • F27D7/06—Forming or maintaining special atmospheres or vacuum within heating chambers
    • 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
    • F27D9/00—Cooling of furnaces or of charges therein
    • 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
    • F27D99/00—Subject matter not provided for in other groups of this subclass
    • F27D99/0001—Heating elements or systems
    • F27D99/0033—Heating elements or systems using burners
    • 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
    • F27D7/00—Forming, maintaining, or circulating atmospheres in heating chambers
    • F27D7/06—Forming or maintaining special atmospheres or vacuum within heating chambers
    • F27D2007/063—Special atmospheres, e.g. high pressure atmospheres
    • 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
    • F27D2017/009—Cyclone for separating fines from gas
    • 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

Abstract

The invention discloses a suspension calcining device and a process suitable for a kaolin raw material with high iron content, which comprise a first cyclone separator, an oxidation furnace, a second cyclone separator and a calcining furnace system, wherein the calcining furnace system comprises a preheating furnace and a modification furnace, a discharge port of the first cyclone separator is respectively connected with a raw material feeding port of the preheating furnace and a raw material feeding port of the modification furnace, the bottom of the preheating furnace is a combustion-supporting air inlet, a top outlet of the preheating furnace is connected with an inlet at the bottom of the modification furnace, a top outlet of the modification furnace is connected with an inlet of the second cyclone separator, and a reduction zone is arranged in the modification furnace; the oxidation furnace is arranged between the air outlet of the second cyclone separator and the inlet of the first cyclone separator, a fuel feeding port and a combustion-supporting air inlet are arranged on the oxidation furnace, and an oxidation zone is arranged in the oxidation furnace; the discharge port of the second cyclone separator is connected with a cooling system. The invention can produce metakaolin meeting the color control requirement, and solves the problems of high energy consumption, small processing capacity, difficult control of product quality and the like of the high-iron content kaolin raw material during calcination.

Description

Suspension calcining device and process suitable for high-iron-content kaolin raw material
Technical Field
The invention relates to the technical field of kaolin, in particular to a suspension calcining device and a process suitable for a kaolin raw material with high iron content.
Background
Kaolin (Al)2O3·2SiO2·2H2O，AS2H2) The metakaolin is common mineral in natural clay or clayey tailings, and metakaolin (MK for short) can be generated through dehydration at a proper temperature (600-900 ℃). Kaolin belongs to a layered silicate structure, and layers are bonded by van der waals bonds, in which OH-hydroxyl groups are bonded more strongly. When the kaolin is heated in the air, a plurality of structural changes occur, and when the kaolin is heated to about 600 ℃, the layered structure of the kaolin is destroyed because of the removal of hydroxyl groups, and amorphous transition phase metakaolin is formed. The metakaolin has irregular molecular arrangement, is in a thermodynamic metastable state and has gelation property under alkali excitation. Metakaolin is a highly active artificial pozzolanic material, which can be blended with calcium hydroxide (Ca (OH)2CH) and water to generate a volcanic ash reaction to generate a hydration product similar to cement.
By utilizing the characteristic, the kaolin containing kaolinite and aluminum-silicon minerals with similar structures is calcined to prepare a mixed material, and then the mixed material is compounded with gypsum, portland cement clinker or limestone to prepare the calcined kaolin-based composite cement, which becomes a research hotspot of the international cement and concrete industries in recent years. The metakaolin with higher activity is adopted to replace clinker, so that the clinker dosage of the cement can be reduced from 75% to 45% -50%, the compressive strength is not reduced after 28 days, the flexural strength can be improved by more than 20%, and the technical goals of low clinker coefficient, low carbon emission and high strength are realized. Meanwhile, research shows that based on the difference of hydration reaction products, compared with Portland cement and common Portland cement doped with fly ash or ground mineral powder, the hardened cement stone has lower porosity and high compactness, so that the cement stone has excellent sulfate corrosion resistance and chloride ion permeability, and is particularly suitable for being used in severe environments such as maritime work, saline alkali and the like.
Since the preparation cost of calcined kaolin is lower than that of clinker, CO in the preparation process of calcined kaolin2The discharge amount is lower than that of CO in the clinker preparation process2The emission and the source of kaolin raw materials are very wide, and the metakaolin is used for replacing clinker in the concrete and cement industries in a large mixing amount under the background that the concrete and cement industries actively promote carbon emission reduction.
At present, the existing metakaolin preparation methods mainly include a fixed bed type, a semi-fixed bed type, a fluidized bed type and the like. The method for preparing metakaolin by adopting rotary kiln calcination is a commonly adopted method, but when the rotary kiln calcination is adopted, the problems of high system heat consumption, easy overburning and inactivation of products, difficult quality control and the like exist. Kaolin raw materials usually contain a certain amount of iron, which mainly exists in the forms of goethite, hematite, siderite and the like, and iron phases are oxidized during the kaolin calcination process and finally exist in the form of red hematite. It has been shown that when the kaolin raw material contains iron (mainly Fe)2O3Characterized) is over a certain range (for example, Fe in kaolin raw material)2O3The mass fraction is more than or equal to 2 percent), and the metakaolin product prepared by calcining the kaolin raw material can show obvious red. The direct use of red metakaolin to prepare cement can affect the color of the finished cement product, and is easily mistaken by the market as poor-quality cement to affect the sale. Analyzed in principle, hematite (Fe)2O3) Reddish brown, magnetite (Fe)3O4) And wustite (FeO) is grayish black and thus containsThe color of the finished product of the iron metakaolin is mainly determined by the existence form of an iron phase in the finished product, and the color of the finished product of the metakaolin can be effectively changed by reducing the content of hematite in the finished product of the metakaolin. Based on the above analysis, a reducing atmosphere was created during metakaolin preparation to introduce Fe3+Reduction to Fe2+Is used for reducing Fe in metakaolin finished product3+And further to prepare an effective means of metakaolin meeting the requirements of the concrete and cement industry. The reasonable process technology is adopted to produce the metakaolin with high activity and consistent color with the cement clinker with lower energy consumption and higher efficiency, which becomes the key of the large-scale production and wide application of the metakaolin and the metakaolin-limestone composite cement.
In conclusion, based on market needs and key technical problems, the suspension calcination process and device suitable for the kaolin raw material with high iron content have important practical significance.
Disclosure of Invention
In order to solve the problems in the prior art, the invention provides a suspension calcining device and a process suitable for a kaolin raw material with high iron content, wherein the suspension calcining device and the process can fully consider the control requirements of the concrete and cement industries on the color of a metakaolin finished product to produce the metakaolin meeting the color control requirements, and simultaneously solve the problems of high energy consumption, small processing capacity, difficult control of product quality and the like in the calcining of the kaolin raw material with high iron content.
The invention is realized in such a way, the suspension calcining device suitable for the kaolin raw material with high iron content comprises a first cyclone separator, an oxidation furnace, a second cyclone separator and a calcining furnace system, wherein the calcining furnace system comprises a preheating furnace and a modification furnace, a fuel feeding port and a raw material feeding port are respectively arranged on the preheating furnace and the modification furnace, a discharge port of the first cyclone separator is respectively connected with the raw material feeding port of the preheating furnace and the raw material feeding port of the modification furnace, the bottom of the preheating furnace is a combustion-supporting air inlet, a top outlet of the preheating furnace is connected with a bottom inlet of the modification furnace, a top outlet of the modification furnace is connected with an inlet of the second cyclone separator, and a reduction zone is arranged in the modification furnace;
the oxidation furnace is arranged between the air outlet of the second cyclone separator and the inlet of the first cyclone separator, the bottom inlet of the oxidation furnace is connected with the air outlet of the second cyclone separator, the top outlet of the oxidation furnace is connected with the inlet of the first cyclone separator, the oxidation furnace is provided with a fuel feeding port and a combustion-supporting air inlet, and the oxidation furnace is internally provided with an oxidation zone;
and the discharge hole of the second cyclone separator is connected with a cooling system.
Preferably, the second cyclone separator is a high separation efficiency type cyclone separator, and the separation efficiency of the high separation efficiency type cyclone separator is greater than or equal to 96%.
Preferably, the preheating furnace consists of a preheating furnace cone, a preheating furnace cylinder and a preheating furnace throat from bottom to top in sequence, wherein a fuel feeding port of the preheating furnace is positioned on the preheating furnace cone, and a raw material feeding port of the preheating furnace is positioned on the preheating furnace cylinder;
the modifying furnace sequentially comprises a modifying furnace cone and a modifying furnace cylinder from bottom to top, wherein a fuel feeding port of the modifying furnace is positioned on the middle parts of the modifying furnace cone and the modifying furnace cylinder, and a raw material feeding port of the modifying furnace is respectively positioned at the bottom and the middle part of the modifying furnace cylinder;
the oxidation furnace is sequentially composed of an oxidation furnace cone and an oxidation furnace cylinder from bottom to top, a fuel feeding port of the oxidation furnace is positioned on the middle parts of the oxidation furnace cone and the oxidation furnace cylinder, and a combustion-supporting air inlet of the oxidation furnace is positioned on the oxidation furnace cylinder.
The device is adopted to carry out a suspension calcination process suitable for the kaolin raw material with high iron content, and the process is that the raw material enters a calciner system after being subjected to full heat exchange through high-temperature flue gas at the outlet of an oxidation furnace and gas-solid separation through a first cyclone separator, a combustion environment of reducing atmosphere is formed in the calciner system, and a combustion environment of oxidizing atmosphere is formed in the oxidation furnace; the calcining temperature in the calcining furnace system is 650-1000 ℃, the flue gas formed by incomplete combustion of fuel and decomposition of kaolin in the calcining furnace system enters the second cyclone separator along with decomposed materials, the flue gas enters the oxidation furnace after gas-solid separation in the second cyclone separator, the unburnt fuel in the flue gas is fully burnt out in the oxidation furnace, meanwhile, the flue gas fully reacts with CO, and the separated materials enter the cooling system.
Preferably, the excess air coefficient in the calcining furnace system is less than 1.0, and preferably 0.5-1.0.
Preferably, the excess air coefficient in the oxidation furnace is more than 1.0, and preferably 1.0-1.2.
Preferably, the retention time of the gas in the calciner system is 2-10 s.
The specific principle of the invention is as follows:
the key to controlling the color of the metakaolin finished product is the control of reduction calcination and cooling. Within the preferable calcining temperature of the calcining furnace system, the kaolin can be fully decomposed to form metakaolin, and the metakaolin can be prevented from being crystallized, separated and inactivated. In order to control the color of a metakaolin finished product, in the process of decomposing the metakaolin to form the metakaolin, the combustion-supporting air quantity and the fuel consumption of a calcining furnace system are reasonably designed, so that the fuel in the calcining furnace system is incompletely combusted to form a reducing atmosphere, the whole calcining furnace system is an oxygen-deficient combustion area (the excess air coefficient in the calcining furnace system is preferably controlled to be 0.5-1.0), and further the Fe in the raw materials is controlled3+Reduction to Fe2+And finally exists in the form of magnetite, so that the metakaolin finished product presents a gray black color. The flue gas formed by incomplete combustion of fuel and decomposition of kaolin in the calciner system leaves the calciner system and enters a second cyclone separator, then enters an oxidation furnace, and a second path of combustion-supporting air enters the oxidation furnace and fully reacts with unburned fuel and CO in the flue gas, so that full combustion of the fuel and full release of heat energy are ensured, and the heat consumption of the system is reduced to the maximum extent. Meanwhile, the second cyclone separator connected with the outlet of the calcining furnace system is designed in a key way, so that the second cyclone separator is a high-separation-efficiency cyclone separator, the high-efficiency gas-solid separation can be realized, and the proportion of internal circulation of materials in the suspension calcining system is reduced.
Kaolin raw material powder meeting production requirements is fed into an outlet pipeline of the oxidation furnace through a feeding device. Kaolin raw material powder and high-temperature flue gas at the outlet of the oxidation furnace are subjected to full heat exchange, then subjected to gas-solid separation by a first cyclone separator, and finally calcinedA furnace system. The calcining furnace system comprises a high-efficiency material scattering device, a hot air inlet pipeline, a preheating furnace, a first combustor arranged on the cone part of the preheating furnace, a modifying furnace, a second combustor arranged on the cone part of the modifying furnace, a third combustor arranged in the middle of the modifying furnace, a flue gas outlet pipeline and the like. The temperature distribution in the preheating furnace and the modifying furnace is monitored in real time by arranging a plurality of temperature measuring points in a layering manner in the height direction of the preheating furnace and the modifying furnace, and the temperature distribution in the preheating furnace and the modifying furnace is controlled within a reasonable range by adjusting the amount of fuel and the amount of material fed into the preheating furnace and the modifying furnace, so that the reasonable temperature distribution in the preheating furnace and the modifying furnace can ensure the full decomposition of kaolin and simultaneously ensure that the kaolin is not over-burnt, and the activity of the finished metakaolin meets the requirements of subsequent production. And a large amount of heat is released by the combustion of the fuel in the calciner system for the decomposition of the kaolin, the decomposed hot materials leave the calciner system, and then the hot materials and hot flue gas are subjected to gas-solid separation in a second cyclone separator and then enter a cooling system. The second cyclone separator is a high separation efficiency type cyclone separator, can realize high-efficiency gas-solid separation, and reduces the proportion of internal circulation of materials in the suspension calcining system. The combustion air is divided into two paths: the first path of combustion-supporting air enters the calcining furnace system through the bottom of the preheating furnace, and the second path of combustion-supporting air enters the oxidizing furnace. The method has the advantages that the amount of combustion-supporting air and the amount of fuel entering the calciner system are reasonably controlled, so that the fuel in the calciner system is incompletely combusted to form a reducing atmosphere, an oxygen-deficient combustion area is formed in the calciner system, and Fe in the raw materials is further processed3+Reduction to Fe2+And finally exists in the form of magnetite, so that the metakaolin finished product presents a gray black color. Flue gas formed by incomplete combustion of fuel and decomposition of kaolin in the calciner system leaves the calciner system, enters a second cyclone separator and then enters the oxidation furnace; and the second path of combustion-supporting air enters the oxidation furnace and fully reacts with unburned fuel and CO in the flue gas, so that the full burn-off of the fuel and the full release of heat energy are ensured, and then the kaolin raw material powder is preheated and subjected to gas-solid separation, and finally leaves the suspension calcination system.
The invention has the following advantages and beneficial effects:
1) the calcining furnace system provided by the invention can improve the combustion-supporting air quantity and fuelThe dosage is reasonably designed, so that the fuel in the calcining furnace system is incompletely combusted, the calcining furnace system is an oxygen-deficient combustion area, and the Fe in the raw materials is further reduced3+Reduction to Fe2+The content of hematite in the metakaolin is greatly reduced from the source, and the difficulty of controlling the color of the metakaolin finished product is effectively reduced.
2) The calcining furnace system provided by the invention is connected with the oxidizing furnace through the cyclone separator, and Fe in the raw material3+Is reduced to Fe in a calciner system2+And finally exists in the form of magnetite, so that the metakaolin finished product presents a gray black color. The prepared metakaolin enters a cooling system after gas-solid separation by a high separation efficiency type cyclone separator, the proportion of internal circulation of materials in a suspension calcining system is reduced, and the reliability of color control of a metakaolin finished product is ensured.
3) The oxidation furnace provided by the invention fully utilizes the second path of combustion-supporting air to fully react with the unburned fuel and CO in the flue gas entering the oxidation furnace, so that the full burn-off of the fuel and the full release of heat energy are ensured while the environment pollution caused by the emission of CO is avoided, and the operation cost of the system is reduced.
Drawings
FIG. 1 is a flow diagram of a suspension calcination apparatus suitable for use with high iron content kaolin materials, according to an embodiment of the present invention.
In the figure: 1. a first cyclone separator; 2. an oxidation furnace; 3. a second cyclone separator; 4. a calciner system; 4-1, preheating a furnace; 4-2, a modification furnace.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
In the description of the present invention, it should be noted that the terms "upper", "lower", "top", "bottom", "inner", "outer", and the like indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience of description and simplicity of description, but do not indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and thus, should not be construed as limiting the present invention. In the description of the present invention, "a plurality" means two or more unless specifically defined otherwise.
In the description of the present invention, it is to be noted that, unless otherwise explicitly specified or limited, the terms "connected" and "connected" are to be interpreted broadly, e.g., as being fixed or detachable or integrally connected; may be a mechanical connection; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.
Examples
Referring to fig. 1, the present embodiment provides a suspension calcining apparatus suitable for high-iron content kaolin raw material, including a first cyclone 1, an oxidation furnace 2, a second cyclone 3 and a calciner system 4, where the calciner system 4 includes a high-efficiency material scattering device, a combustion-supporting air inlet pipeline, a preheating furnace 4-1, a first burner disposed on a cone of the preheating furnace 4-1, a modification furnace 4-2, a second burner disposed on a cone of the modification furnace 4-2, a third burner disposed on a middle portion of the modification furnace 4-2, and a flue gas outlet pipeline; a fuel feeding port and a raw material feeding port are respectively arranged on the preheating furnace 4-1 and the modification furnace 4-2, a discharge port of the first cyclone separator 1 is respectively connected with the raw material feeding port of the preheating furnace 4-1 and the raw material feeding port of the modification furnace 4-2, a combustion-supporting air inlet is arranged at the bottom of the preheating furnace 4-1, the preheating furnace 4-1 sequentially consists of a preheating furnace 4-1 cone, a preheating furnace 4-1 cylinder and a preheating furnace 4-1 necking from bottom to top, the fuel feeding port of the preheating furnace 4-1 is positioned on the preheating furnace 4-1 cone, and the raw material feeding port of the preheating furnace 4-1 is positioned on the preheating furnace 4-1 cylinder; the modification furnace 4-2 sequentially comprises a modification furnace 4-2 cone and a modification furnace 4-2 cylinder from bottom to top, a fuel feeding port of the modification furnace 4-2 is positioned on the middle parts of the modification furnace 4-2 cone and the modification furnace 4-2 cylinder, a raw material feeding port of the modification furnace 4-2 is respectively positioned at the bottom and the middle part of the modification furnace 4-2 cylinder, a top outlet of the preheating furnace 4-1 is connected with a bottom inlet of the modification furnace 4-2, a top outlet of the modification furnace 4-2 is connected with an inlet of the second cyclone separator 3, and a reduction zone is arranged in the modification furnace 4-2;
the oxidation furnace 2 is arranged between the air outlet of the second cyclone separator 3 and the inlet of the first cyclone separator 1, and the oxidation furnace 2 comprises a hot air inlet pipeline, a furnace body, a fourth combustor arranged on the cone part of the oxidation furnace 2, a fifth combustor arranged in the middle of the oxidation furnace 2, a flue gas outlet pipeline and the like. The bottom inlet of the oxidation furnace 2 is connected with the air outlet of the second cyclone separator 3, the top outlet of the oxidation furnace 2 is connected with the inlet of the first cyclone separator 1, at the moment, raw materials enter a connecting pipeline between the outlet of the oxidation furnace 2 and the inlet of the first cyclone separator 1, a fuel feeding port and a combustion-supporting air inlet are arranged on the oxidation furnace 2, the oxidation furnace 2 sequentially consists of an oxidation furnace 2 cone and an oxidation furnace 2 cylinder from bottom to top, the fuel feeding port of the oxidation furnace 2 is positioned in the middle of the oxidation furnace 2 cone and the oxidation furnace 2 cylinder, the combustion-supporting air inlet of the oxidation furnace 2 is positioned on the oxidation furnace 2 cylinder, and an oxidation area is arranged in the oxidation furnace 2;
and a discharge hole of the second cyclone separator 3 is connected with a cooling system.
The suspension calcination process suitable for the kaolin raw material with high iron content comprises the following steps:
kaolin raw material powder meeting production requirements is fed into an outlet pipeline of an oxidation furnace 2 through a feeding device, the kaolin raw material powder and high-temperature flue gas at the outlet of the oxidation furnace 2 are subjected to full heat exchange, then the kaolin raw material powder is subjected to gas-solid separation through a first cyclone separator 1 and then enters a calcining furnace system 4, one path of combustion-supporting air enters the calcining furnace system 4 through the bottom of a preheating furnace 4-1, the calcining temperature in the preheating furnace 4-1 and a modification furnace 4-2 is controlled to be 650-1000 ℃ through adjusting the amount of air, the amount of fuel and the amount of materials fed into the preheating furnace 4-1 and the modification furnace 4-2, and the fuel in the calcining furnace system 4 is incompletely combusted to form a combustion environment of a reducing atmosphere (the excess air coefficient in the calcining furnace is preferably 0.5-1.0), so that an oxygen-poor combustion area is formed in the calcining furnace system 4, the kaolin is fully decomposed, and Fe in the raw material is fully decomposed3+Reduction to Fe2 +Finally existing in the form of magnetite so that the metakaolin finished product is in the form ofAnd is gray black. Meanwhile, the kaolin is not over-burnt, so that the activity of the metakaolin finished product meets the requirement of subsequent production. The retention time of the gas in the calciner system 4 is 2-10 s.
The fuel in the calciner system 4 is burnt to release a large amount of heat for the decomposition of the kaolin, the decomposed hot materials leave the calciner system 4, and then the hot materials and hot flue gas are separated in the second cyclone separator 3 and enter a cooling system. The second cyclone separator 3 is a high separation efficiency type cyclone separator, the separation efficiency of the high separation efficiency type cyclone separator is more than or equal to 96 percent, the gas-solid high-efficiency separation can be realized, and the proportion of internal circulation of materials in the suspension calcining system is reduced. It is noted that higher separation efficiency often means high resistance, and thus a balance between separation efficiency and resistance is needed for practical operation.
The method comprises the following steps that hot flue gas formed by incomplete combustion of fuel and decomposition of kaolin enters an oxidation furnace 2 (the excess air coefficient in the oxidation furnace 2 is more than 1.0, preferably 1.0-1.2), a combustion environment of an oxidation atmosphere is formed in the oxidation furnace 2 by adjusting the amount of air and the amount of fuel fed into the oxidation furnace 2, unburnt fuel in the hot flue gas is fully burnt out and fully reacts with CO, full burning of the fuel and full release of heat energy are guaranteed, then the hot flue gas continuously moves upwards to preheat and separate a kaolin raw material from gas and solid, and finally the kaolin raw material leaves the suspension calcination system.
Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: it is to be understood that modifications may be made to the technical solutions described in the foregoing embodiments, or some or all of the technical features may be equivalently replaced, and the modifications or the replacements may not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.

Claims (7)

1. A suspension calcining device suitable for a kaolin raw material with high iron content is characterized by comprising a first cyclone separator, an oxidation furnace, a second cyclone separator and a calcining furnace system, wherein the calcining furnace system comprises a preheating furnace and a modification furnace, a fuel feeding port and a raw material feeding port are respectively arranged on the preheating furnace and the modification furnace, a discharge port of the first cyclone separator is respectively connected with the raw material feeding port of the preheating furnace and the raw material feeding port of the modification furnace, a combustion-supporting air inlet is arranged at the bottom of the preheating furnace, a top outlet of the preheating furnace is connected with a bottom inlet of the modification furnace, a top outlet of the modification furnace is connected with an inlet of the second cyclone separator, and a reduction zone is arranged in the modification furnace;
the oxidation furnace is arranged between the air outlet of the second cyclone separator and the inlet of the first cyclone separator, the bottom inlet of the oxidation furnace is connected with the air outlet of the second cyclone separator, the top outlet of the oxidation furnace is connected with the inlet of the first cyclone separator, the oxidation furnace is provided with a fuel feeding port and a combustion-supporting air inlet, and the oxidation furnace is internally provided with an oxidation zone;
and the discharge hole of the second cyclone separator is connected with a cooling system.
2. The suspension calcination device for kaolin raw material with high iron content as claimed in claim 1, wherein the second cyclone is a high separation efficiency type cyclone, and the separation efficiency of the high separation efficiency type cyclone is greater than or equal to 96%.
3. The suspension calcination device for kaolin materials with high iron content as claimed in claim 1, wherein the preheating furnace is composed of a preheating furnace cone, a preheating furnace cylinder and a preheating furnace throat from bottom to top in sequence, the fuel feeding port of the preheating furnace is positioned on the preheating furnace cone, and the raw material feeding port of the preheating furnace is positioned on the preheating furnace cylinder;
the modifying furnace sequentially comprises a modifying furnace cone and a modifying furnace cylinder from bottom to top, wherein a fuel feeding port of the modifying furnace is positioned on the middle parts of the modifying furnace cone and the modifying furnace cylinder, and a raw material feeding port of the modifying furnace is respectively positioned at the bottom and the middle part of the modifying furnace cylinder;
the oxidation furnace is sequentially composed of an oxidation furnace cone and an oxidation furnace cylinder from bottom to top, a fuel feeding port of the oxidation furnace is positioned on the middle parts of the oxidation furnace cone and the oxidation furnace cylinder, and a combustion-supporting air inlet of the oxidation furnace is positioned on the oxidation furnace cylinder.
4. A suspension calcination process for kaolin raw materials with high iron content, which is carried out by the device according to any one of claims 1 to 3, is characterized in that the process comprises the steps of enabling the raw materials to enter a calciner system after being subjected to full heat exchange through high-temperature flue gas at the outlet of an oxidation furnace and then being subjected to gas-solid separation through a first cyclone separator, forming a combustion environment of reducing atmosphere in the calciner system and forming a combustion environment of oxidizing atmosphere in the oxidation furnace; the calcining temperature in the calcining furnace system is 650-1000 ℃, the flue gas formed by incomplete combustion of fuel and decomposition of kaolin in the calcining furnace system enters the second cyclone separator along with decomposed materials, the flue gas enters the oxidation furnace after gas-solid separation in the second cyclone separator, the unburnt fuel in the flue gas is fully burnt out in the oxidation furnace, meanwhile, the flue gas fully reacts with CO, and the separated materials enter the cooling system.
5. The suspension calcination process for kaolin raw material with high iron content as claimed in claim 4, wherein the excess air coefficient in the calciner system is 0.5-1.0.
6. The process of claim 4, wherein the excess air factor in the oxidizer is greater than 1.0.
7. The suspension calcination process for kaolin materials with high iron content according to claim 4, wherein the residence time of the gas in the calciner system is 2-10 s.
CN202111202559.9A 2021-10-15 2021-10-15 Suspension calcining device and process suitable for high-iron-content kaolin raw material Pending CN113883898A (en)

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US5132102A (en) * 1989-12-21 1992-07-21 Fuller Company Method for heat treatment of fines with atmosphere control
US20120145042A1 (en) * 2010-12-13 2012-06-14 Flsmidth A/S Process for the Calcination and Manufacture of Synthetic Pozzolan
CN111981471A (en) * 2020-09-01 2020-11-24 中国科学院工程热物理研究所 Combustion device and method for preventing tail heating surface of high-alkali coal boiler from being contaminated
CN112939002A (en) * 2021-01-28 2021-06-11 天津水泥工业设计研究院有限公司 Flexibly-adjustable high-activity metakaolin preparation system and preparation method
DE102020200186A1 (en) * 2020-01-09 2021-07-15 Thyssenkrupp Ag Process for heat treatment and color optimization of natural clays

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5132102A (en) * 1989-12-21 1992-07-21 Fuller Company Method for heat treatment of fines with atmosphere control
US20120145042A1 (en) * 2010-12-13 2012-06-14 Flsmidth A/S Process for the Calcination and Manufacture of Synthetic Pozzolan
DE102020200186A1 (en) * 2020-01-09 2021-07-15 Thyssenkrupp Ag Process for heat treatment and color optimization of natural clays
CN111981471A (en) * 2020-09-01 2020-11-24 中国科学院工程热物理研究所 Combustion device and method for preventing tail heating surface of high-alkali coal boiler from being contaminated
CN112939002A (en) * 2021-01-28 2021-06-11 天津水泥工业设计研究院有限公司 Flexibly-adjustable high-activity metakaolin preparation system and preparation method

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