WO2020220499A1 - 一种制备轻质氧化镁和氧化钙的方法及其用于制备钙镁复合膨胀剂的应用 - Google Patents

一种制备轻质氧化镁和氧化钙的方法及其用于制备钙镁复合膨胀剂的应用 Download PDF

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WO2020220499A1
WO2020220499A1 PCT/CN2019/099571 CN2019099571W WO2020220499A1 WO 2020220499 A1 WO2020220499 A1 WO 2020220499A1 CN 2019099571 W CN2019099571 W CN 2019099571W WO 2020220499 A1 WO2020220499 A1 WO 2020220499A1
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calcium
oxide
magnesium
magnesium oxide
dolomite
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PCT/CN2019/099571
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English (en)
French (fr)
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刘加平
张守治
张勇
王育江
王瑞
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镇江苏博特新材料有限公司
江苏苏博特新材料股份有限公司
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Priority to US17/044,298 priority Critical patent/US11548818B2/en
Publication of WO2020220499A1 publication Critical patent/WO2020220499A1/zh

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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
    • 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
    • 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
    • C04B18/00—Use of agglomerated or waste materials or refuse as fillers for mortars, concrete or artificial stone; Treatment of agglomerated or waste materials or refuse, specially adapted to enhance their filling properties in mortars, concrete or artificial stone
    • C04B18/02—Agglomerated materials, e.g. artificial aggregates
    • C04B18/027—Lightweight materials
    • 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
    • C04B2/106—Preheating, burning calcining or cooling in fluidised bed furnaces
    • 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
    • C04B38/00—Porous mortars, concrete, artificial stone or ceramic ware; Preparation thereof
    • C04B38/02—Porous mortars, concrete, artificial stone or ceramic ware; Preparation thereof by adding chemical blowing agents
    • 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
    • C04B40/00—Processes, in general, for influencing or modifying the properties of mortars, concrete or artificial stone compositions, e.g. their setting or hardening ability
    • C04B40/0028—Aspects relating to the mixing step of the mortar preparation
    • C04B40/0039—Premixtures of ingredients
    • C04B40/0042—Powdery mixtures
    • 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
    • C04B40/00—Processes, in general, for influencing or modifying the properties of mortars, concrete or artificial stone compositions, e.g. their setting or hardening ability
    • C04B40/0028—Aspects relating to the mixing step of the mortar preparation
    • C04B40/0039—Premixtures of ingredients
    • C04B40/0046—Premixtures of ingredients characterised by their processing, e.g. sequence of mixing the ingredients when preparing the premixtures
    • 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
    • C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
    • C04B2111/40—Porous or lightweight materials
    • 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
    • Y02P40/00—Technologies relating to the processing of minerals
    • Y02P40/40—Production or processing of lime, e.g. limestone regeneration of lime in pulp and sugar mills

Definitions

  • the invention relates to a calcining decomposition technology of dolomite, in particular to a method for separately preparing light magnesium oxide and calcium oxide by using dolomite and its application for preparing calcium-magnesium composite expansion agent.
  • Dolomite is a compound salt of magnesium carbonate and calcium carbonate.
  • the molecular formula is CaMg(CO 3 ) 2.
  • the main components are magnesium oxide, calcium oxide, SiO 2 , Fe 2 O 3 , and the average content is 21.29%, 30.42%, and 0.78% respectively. , 0.13%.
  • my country’s dolomite resources are widely distributed, with reserves of 8.22 billion tons. The production areas are all over the country. There are large white clouds in Liaoning, Inner Mongolia, Shanxi, Henan, Hebei, Jiangsu, Anhui, Hunan, Hubei, Sichuan, Chongqing, Fujian, Zhejiang and other places. Stone deposits.
  • dolomite is mainly used to produce light magnesium oxide and calcium salt.
  • Light magnesia is a product in the field of inorganic chemicals, mainly used in metallurgy, smelting, high-grade magnesia bricks, refractory materials and moisturizing materials. It is also widely used in rubber, rubber sheet, rubber products, pharmaceutical industry, food industry, plastic sheet promotion Agent, plasticizer of glass fiber reinforced plastic and surface coating paint of silicon steel sheet, paper production, steel ball polishing, leather treatment, insulating material, grease, dye, ceramic, desiccant, resin, flame retardant, etc.
  • Calcium salt as a by-product of dolomite production of light magnesium oxide, mainly includes calcium carbonate, calcium sulfate and calcium chloride according to different production processes.
  • Calcium carbonate can be used in fields such as cement production, flue gas desulfurization and construction; calcium sulfate can be used in the field of construction gypsum, and calcium chloride can be used in fields such as mining, petroleum exploration, and environmental protection.
  • the method is to first calcinate dolomite (Ca magnesium oxide (CO 3 ) 2 ) into magnesium oxide and calcium oxide, and then add water to digest Mg(OH) 2 and Ca(OH) 2 are prepared , and then carbonized with carbon dioxide to obtain magnesium bicarbonate and calcium carbonate. After removing calcium carbonate, the mother liquor is pyrolyzed to obtain basic magnesium carbonate, which is then calcined at 850°C-900°C. Obtain light magnesium oxide.
  • This method has a long process flow, huge equipment, long dehydration time, high energy consumption, small production capacity, difficult process operation control, and low utilization value of the by-product calcium carbonate. If this by-product calcium carbonate is calcined to prepare light calcium oxide, it will consume a lot of energy and is not economically reasonable.
  • the invention overcomes the disadvantages of complex process, high energy consumption and low economic value of by-products in the process of calcium and magnesium separation in the process of preparing light magnesium oxide by decomposition of dolomite in the prior art, and provides a simple process and low production energy consumption , A method of using dolomite to prepare light magnesium oxide and calcium oxide with high economic value. And on the basis of this method, a calcium-magnesium composite expansion agent is further prepared.
  • the method of the present invention for preparing light magnesium oxide and calcium oxide by decomposition of dolomite utilizes the difference in the decomposition temperature of magnesium carbonate and calcium carbonate during the calcination and decomposition process of dolomite and the difference in the weight of the material after decomposition, which is used in the suspension reaction tower According to the principle of negative pressure air separation, the effective separation of magnesium oxide and calcium oxide can be realized in one step, and light magnesium oxide and light calcium oxide can be prepared separately, which simplifies the process flow, significantly reduces production energy consumption, and saves production costs. Improve the market competitiveness of light magnesium oxide and light calcium oxide, and expand the direction for the comprehensive application of dolomite.
  • the suspension reaction tower of the present invention is composed of two upper and lower calcining belts, and an air flow separator is arranged in the middle to separate.
  • the airflow separator for the suspension reaction tower of the present invention refers to a specific gravity air separation device that is placed inside the suspension reaction tower and consists of a cyclone system, a frequency conversion system, a separation wheel and the like.
  • the principle of the invention is: the calcining and decomposition process of dolomite is divided into two stages, with The invention utilizes the difference in the decomposition temperature and the quality of the decomposition product during the calcining and decomposition process of dolomite, and provides two layers of calcination reaction zones in the suspension reaction tower, and the calcination temperature of the upper layer of the suspension reaction tower is controlled at 550°C to 650°C, which can calcinate dolomite It is decomposed into magnesium oxide, calcium carbonate and carbon dioxide. Because the molecular weight of calcium carbonate is 2.5 times that of magnesium oxide, the effective separation of magnesium oxide and calcium carbonate is realized by specific gravity air separation equipment. After the separated magnesium oxide is collected, the invention can be obtained.
  • One of the products required is light magnesium oxide.
  • the undecomposed calcium carbonate is continuously decomposed into calcium oxide and carbon dioxide at the calcination temperature of 900°C ⁇ 1000°C in the lower layer of the suspension reaction tower. After collection, one of the products required by the present invention is obtained. .
  • the method for preparing light magnesium oxide and calcium oxide by decomposition of dolomite according to the present invention adopts the following process steps:
  • Magnesium oxide preparation firstly grind dolomite powder into dolomite raw meal powder with a fineness of 80um sieve remaining about 5%, and put the dolomite raw meal powder into the suspension reaction tower, and control the calcination temperature of the upper layer of the suspension reaction tower at 550°C- At around 650°C, raw dolomite powder absorbs heat and decomposes to produce magnesium oxide, carbon dioxide and calcium carbonate during the descending process. Due to the difference in material weight, the magnesium oxide and carbon dioxide produced by the decomposition are processed by the airflow separator of the suspension reaction tower together under the action of the cyclone negative pressure, and discharged from the first-level outlet of the suspension reaction tower, and processed in the magnesium oxide dust collector. After gas-solid separation treatment, light magnesium oxide, one of the desired products, is collected.
  • step (1) the undecomposed calcium carbonate continues to sink in the suspension reaction tower by gravity, and the calcination temperature of the lower layer of the suspension reaction tower is controlled to be around 900°C-1000°C. During the descending process, it absorbs heat and decomposes to produce calcium oxide and carbon dioxide.
  • the calcium oxide and carbon dioxide produced by the decomposition are discharged from the secondary outlet of the suspension reaction tower under the action of the cyclone negative pressure, and are collected after gas-solid separation treatment in the calcium oxide dust collector
  • One of the desired products is light calcium oxide.
  • magnesium oxide and calcium oxide from dolomite are firstly calcining and decomposing dolomite into a mixture of magnesium oxide and calcium oxide, and then digesting with water to obtain Mg(OH) 2 and Ca(OH) 2 . Magnesium and calcium are separated and finally heated and calcined to prepare magnesium oxide and calcium oxide products respectively.
  • the invention utilizes the difference in the decomposition temperature of magnesium carbonate and calcium carbonate during the calcining and decomposition process of dolomite and the difference in the weight of the material after decomposition, and the one-step method is sufficient in the suspension reaction tower according to the principle of negative pressure air separation Realize the effective separation of magnesium oxide and calcium oxide, respectively prepare light magnesium oxide and light calcium oxide, simplify the process, significantly reduce production energy consumption, save production costs, and increase light magnesium oxide and light calcium oxide Its market competitiveness expands the direction for the comprehensive application of dolomite.
  • the calcium-magnesium composite expansion agent is composed of a calcium-based expansion component and a magnesium-based expansion component, wherein the calcium-based expansion component is calcium oxide expanded clinker, the magnesium-based expansion component is light magnesium oxide, and the calcium-based expansion group
  • the mass ratio of the magnesia swelling component is 1:1.
  • the calcium swelling component is carbonated modified calcium oxide swelled clinker, and activated calcium oxide generated by calcining and decomposing dolomite is obtained by carbonation modification in a carbonization reactor.
  • the magnesia expansion component is light magnesia, which is prepared by calcining and decomposing dolomite.
  • the method for preparing the calcium-magnesium composite expansion agent is obtained by using the aforementioned dolomite decomposition process to prepare light magnesium oxide and calcium oxide, respectively, plus a calcium oxide carbonation process, and the carbon dioxide generated in the magnesium oxide production process is sent to
  • the carbonization reactor carbonizes calcium oxide, the obtained calcium expansion component, and the aforementioned magnesium expansion component are prepared to obtain the calcium-magnesium composite expansion agent, which optimizes the expansion process of the direct calcination of dolomite to produce the calcium-magnesium composite expansion agent, and opens up A new way to prepare calcium-magnesium composite expansion agent, which reduces the production cost of calcium-magnesium composite expansion agent, improves the application effect of calcium-magnesium composite expansion agent in practical engineering, and provides market competition for the promotion and application of calcium-magnesium composite expansion agent It has significant social and economic benefits.
  • the preparation method of the calcium-magnesium composite expansion agent specifically adopts the following process steps:
  • magnesium swelling component In the process of preparing light magnesium oxide and calcium oxide by decomposition of the aforementioned dolomite, magnesium oxide and carbon dioxide are separated in the magnesium oxide dust collector to achieve gas-solid separation, and the dust will be removed and purified by the dust collector.
  • the carbon dioxide content in the hot flue gas is about 8-12% (volume fraction), which is passed into the carbonization reactor for standby, and the sinking light burnt magnesia is discharged from the discharge valve at the lower end of the magnesia dust collector to obtain the required magnesia
  • the expansion component is lightly burned magnesia.
  • Preparation of active calcium oxide it is the step of obtaining calcium oxide in the preparation of light magnesium oxide and calcium oxide by decomposition of the aforementioned dolomite.
  • Carbonation modification The hot flue gas introduced into the carbonization reactor is pressurized and concentrated into a reaction gas with a reaction pressure of 0.5 MPa and a carbon dioxide concentration of 24% to 26% (volume fraction), and then the step (2 )
  • the active calcium oxide is fed into the carbonization reactor by the screw feeder for carbonation reaction.
  • the reaction temperature in the carbonization reactor is controlled to be 180°C-250°C, and the reaction time is 20min-40min.
  • the calcium swelling component is carbonated modified calcium oxide swelling clinker.
  • the reaction of calcium oxide and carbon dioxide to form calcium carbonate is a well-known technology.
  • the Chinese patent document published No. CN104671688A (a modified calcium oxide expanded clinker, its preparation method and its application) and the Chinese patent document published No. CN102459116A (expanded Materials and its manufacturing methods) all disclose the use of calcium oxide and carbon dioxide to carry out carbonation reaction to delay the hydration rate of calcium oxide clinker. Either choose to carry out carbonation treatment at a high temperature of 200°C-800°C, or choose to use water
  • the catalysis of gas conducts carbonation treatment under low temperature conditions of less than 200°C. In summary, these technical routes all conduct carbonation reaction under normal pressure conditions.
  • the present invention utilizes the carbon dioxide generated during the calcination and decomposition process of dolomite in the suspension reaction tower, and then enters the carbonization reactor after filtering and dust removal, and then enters the carbonization reactor for pressure concentration and active calcium oxide for carbonation reaction, preferably carbonation
  • the reaction pressure is 0.5 MPa
  • the carbonation reaction temperature is 180° C. to 250° C.
  • the carbon dioxide reaction concentration is 24% to 26% (volume fraction).
  • the present invention uses dolomite with abundant reserves as raw materials, and prepares the magnesium expansion components of the calcium-magnesium composite expansion agent through the suspension reaction tower and the carbonization reaction kettle, respectively, light magnesium oxide and calcium Expansion component carbonated modified calcium oxide swelling clinker, under the premise of ensuring the reactivity of the magnesium swelling component light magnesia, the calcium carbonate generated by the carbonation modification is used to wrap the free calcium oxide of the calcium swelling component, Reduce the reaction activity of the calcium swelling component and regulate the swelling rate of the calcium swelling component.
  • it solves the problem of the limitation of the production area of the light magnesium oxide raw material of the magnesium expansion component in the calcium-magnesium composite expansion agent.
  • the problem of low effective expansion efficiency optimizes the expansion process of dolomite direct calcination to produce calcium-magnesium composite expansion agent, opens up a new way to prepare calcium-magnesium composite expansion agent, reduces the production cost of calcium-magnesium composite expansion agent, and increases
  • the application effect of the calcium-magnesium composite expansion agent in actual projects provides market competitiveness for the promotion and application of the calcium-magnesium composite expansion agent, and has significant social and economic benefits.
  • Figure 1 shows the process flow chart of the preparation of light magnesium oxide and calcium oxide using dolomite.
  • Figure 2 is a process flow diagram of the preparation of calcium-magnesium composite expansion agent.
  • Figure 3 is a graph of the test temperature change curve that simulates the temperature change of the super-long and super-thick structure concrete.
  • Figure 4 is a reference concrete blank sample without expansion agent, 7% application example 1, 7% application example 2 concrete, 7% application example 3 concrete, and 7% application example The autogenous volume deformation curve of the concrete of Comparative Example 1 under variable temperature curing conditions.
  • the anhydrite dolomite used in the embodiment of the present invention comes from the Anhui dolomite mine, and its main components are 21.10% magnesium oxide, 30.28% calcium oxide, SiO 2 0.92%, Fe 2 O 3 0.37%, Al 2 O 3 0.39%, loss on ignition 46.51%.
  • a method for separately preparing light magnesium oxide and calcium oxide using dolomite including the following two steps:
  • Magnesium oxide preparation firstly grind the dolomite powder into dolomite raw meal powder with a fineness of 80um and 4% of the remaining sieve. Put the dolomite raw meal powder into the suspension reaction tower, and control the calcination temperature of the upper layer of the suspension reaction tower at 550°C. The stone raw meal powder absorbs heat and decomposes to produce magnesium oxide, carbon dioxide and calcium carbonate during the descending process. Due to the difference in material weight, the magnesium oxide and carbon dioxide produced by the decomposition are processed by the airflow separator of the suspension reaction tower together under the action of the cyclone negative pressure, and discharged from the first-level outlet of the suspension reaction tower, and processed in the magnesium oxide dust collector.
  • light magnesium oxide one of the products of the present invention
  • the chemical composition of the light magnesium oxide prepared by the present invention was tested with reference to the method specified in the current ferrous metallurgical industry standard YB/T5206-2004 "Light Burned Magnesium Oxide", and the results are shown in Table 1. It can be seen from the data in Table 1 that the light magnesium oxide prepared by the present invention meets the requirements of CBM85.
  • step (1) the undecomposed calcium carbonate continues to sink in the suspension reaction tower by gravity, and the calcination temperature of the lower layer of the suspension reaction tower is controlled at 900°C.
  • the undecomposed calcium carbonate is absorbed during the descending process.
  • the heat is decomposed to generate calcium oxide and carbon dioxide.
  • the calcium oxide and carbon dioxide produced by the decomposition are discharged from the secondary outlet of the suspension reaction tower under the action of the cyclone negative pressure, and after gas-solid separation treatment in the calcium oxide dust collector, the invention is obtained by collecting One of the products is light calcium oxide.
  • the chemical composition of the light calcium oxide prepared by the present invention was tested with reference to the method specified in the current chemical industry standard HG/T 4205-2011 "Industrial Calcium Oxide", and the results are shown in Table 2. It can be seen from the data in Table 2 that the light calcium oxide prepared by the present invention meets the requirements of category III products of the chemical industry standard "Industrial Calcium Oxide", and can be used in industries such as plastic rubber manufacturing and flue gas desulfurization.
  • a method for separately preparing light magnesium oxide and calcium oxide using dolomite including the following two steps:
  • Magnesium oxide preparation first grind the dolomite powder into dolomite raw meal powder with a fineness of 80um and 5% of the sieve, and put the dolomite raw meal powder into the suspension reaction tower, and control the calcination temperature of the upper layer of the suspension reaction tower at 600°C.
  • the stone raw meal powder absorbs heat and decomposes to produce magnesium oxide, carbon dioxide and calcium carbonate during the descending process. Due to the difference in material weight, the magnesium oxide and carbon dioxide produced by the decomposition are processed by the airflow separator of the suspension reaction tower together under the action of the cyclone negative pressure, and discharged from the first-level outlet of the suspension reaction tower, and processed in the magnesium oxide dust collector.
  • light magnesium oxide one of the products of the present invention
  • the chemical composition of the light magnesium oxide prepared by the present invention was tested with reference to the method specified in the current ferrous metallurgy industry standard YB/T5206-2004 "Light Burned Magnesium Oxide", and the results are shown in Table 3. It can be seen from the data in Table 3 that the light magnesium oxide prepared by the present invention meets the requirements of CBM85.
  • step (1) the undecomposed calcium carbonate continues to sink in the suspension reaction tower by gravity, and the lower calcination temperature of the suspension reaction tower is controlled at 950°C.
  • the undecomposed calcium carbonate is absorbed during the descending process.
  • the heat is decomposed to generate calcium oxide and carbon dioxide.
  • the calcium oxide and carbon dioxide produced by the decomposition are discharged from the secondary outlet of the suspension reaction tower under the action of the cyclone negative pressure, and after gas-solid separation treatment in the calcium oxide dust collector, the invention is obtained by collecting One of the products is light calcium oxide.
  • the chemical composition of the light calcium oxide prepared by the present invention was tested with reference to the method specified in the current chemical industry standard HG/T 4205-2011 "Industrial Calcium Oxide", and the results are shown in Table 4. It can be seen from the data in Table 4 that the light calcium oxide prepared by the present invention meets the requirements of class III products in the chemical industry standard "Industrial Calcium Oxide", and can be used in industries such as plastic rubber manufacturing and flue gas desulfurization.
  • a method for separately preparing light magnesium oxide and calcium oxide using dolomite including the following two steps:
  • Magnesium oxide preparation first grind the dolomite powder into dolomite raw meal powder with a fineness of 80um and 6% over the sieve, and put the dolomite raw meal powder into the suspension reaction tower, and control the calcination temperature of the upper layer of the suspension reaction tower at 650°C.
  • the stone raw meal powder absorbs heat and decomposes to produce magnesium oxide, carbon dioxide and calcium carbonate during the descending process. Due to the difference in material weight, the magnesium oxide and carbon dioxide produced by the decomposition are processed by the airflow separator of the suspension reaction tower together under the action of the cyclone negative pressure, and discharged from the first-level outlet of the suspension reaction tower, and processed in the magnesium oxide dust collector.
  • light magnesium oxide one of the products of the present invention
  • the chemical composition of the light magnesium oxide prepared by the present invention was tested with reference to the method specified in the current ferrous metallurgy industry standard YB/T5206-2004 "Light Burned Magnesium Oxide", and the results are shown in Table 5. It can be seen from the data in Table 5 that the light magnesium oxide prepared by the present invention meets the requirements of CBM85.
  • step (1) the undecomposed calcium carbonate continues to sink in the suspension reaction tower by gravity, and the lower calcination temperature of the suspension reaction tower is controlled at 1000°C.
  • the undecomposed calcium carbonate is absorbed during the descending process.
  • the heat is decomposed to generate calcium oxide and carbon dioxide.
  • the calcium oxide and carbon dioxide produced by the decomposition are discharged from the secondary outlet of the suspension reaction tower under the action of the cyclone negative pressure, and after gas-solid separation treatment in the calcium oxide dust collector, the invention is obtained by collecting One of the products is light calcium oxide.
  • the chemical composition of the light calcium oxide prepared by the present invention was tested with reference to the method specified in the current chemical industry standard HG/T 4205-2011 "Industrial Calcium Oxide", and the results are shown in Table 6. It can be seen from the data in Table 6 that the light calcium oxide prepared by the present invention meets the requirements of category III products of the chemical industry standard "Industrial Calcium Oxide", and can be used in industries such as plastic rubber manufacturing and flue gas desulfurization
  • a preparation method of calcium-magnesium composite expansion agent, and its production process is carried out as follows:
  • (1) Preparation of magnesia swelling component first grind dolomite powder into dolomite raw meal powder with a fineness of 80um sieve remaining 5%, and then put the dolomite raw meal powder into the suspension reaction tower to control the calcination temperature of the upper layer of the suspension reaction tower At 600°C, dolomite raw meal powder absorbs heat and decomposes to produce magnesium oxide, carbon dioxide and calcium carbonate during the descending process. Due to the difference in material weight, the magnesium oxide and carbon dioxide produced by the decomposition are processed by the airflow separator of the suspension tower under the action of the cyclone negative pressure, and discharged from the first level outlet of the suspension tower, and enters the magnesium oxide dust collector.
  • Magnesium oxide and carbon dioxide are separated from the gas and solid in the magnesium oxide dust collector.
  • the carbon dioxide content in the hot flue gas after dust removal and purification by the dust collector is about 12% (volume fraction), which is passed into the carbonization reactor for standby and sinking oxidation
  • the magnesium is discharged from the discharge valve at the lower end of the magnesium oxide dust collector to obtain the desired magnesium expansion component light magnesium oxide.
  • step (1) the undecomposed calcium carbonate continues to sink in the suspension tower by gravity, and the calcination temperature of the lower layer of the suspension reaction tower is controlled to 1050°C.
  • the undecomposed calcium carbonate is in the process of falling It absorbs heat and decomposes to generate activated calcium oxide and carbon dioxide.
  • the activated calcium oxide and carbon dioxide produced by the decomposition are discharged from the secondary outlet of the suspension tower under the action of the cyclone negative pressure and enter the calcium oxide dust collector. Calcium oxide and carbon dioxide realize gas-solid separation in the calcium oxide dust collector.
  • the carbon dioxide content in the hot flue gas after dust removal and purification by the dust collector is about 12% (volume fraction), which is passed into the carbonization reactor for standby, and sinks
  • the calcium oxide is discharged from the discharge valve at the lower end of the calcium oxide dust collector to obtain activated calcium oxide.
  • Carbonation modification The hot flue gas passed into the carbonization reactor is pressurized and concentrated into a reaction gas with a reaction pressure of 0.5 MPa and a carbon dioxide concentration of 25% (volume fraction), and then the activity in step (2) Calcium oxide is fed into the carbonization reactor by the screw feeder for carbonation reaction.
  • the reaction temperature in the carbonization reactor is controlled to 220°C and the reaction time is 30 minutes to obtain the carbonation modification of the calcium expansion component required by the present invention. Expansive calcium oxide clinker.
  • a preparation method of calcium-magnesium composite expansion agent, and its production process is carried out as follows:
  • (1) Preparation of magnesia swelling component first grind dolomite powder into dolomite raw meal powder with a fineness of 80um sieve remaining 5%, and then put the dolomite raw meal powder into the suspension reaction tower to control the calcination temperature of the upper layer of the suspension reaction tower At 550°C, dolomite raw meal powder absorbs heat and decomposes to produce magnesium oxide, carbon dioxide and calcium carbonate during the descending process. Due to the difference in material weight, the magnesium oxide and carbon dioxide produced by the decomposition are processed by the airflow separator of the suspension tower under the action of the cyclone negative pressure, and discharged from the first level outlet of the suspension tower, and enters the magnesium oxide dust collector.
  • Magnesium oxide and carbon dioxide are separated from the gas and solid in the magnesium oxide dust collector.
  • the carbon dioxide content in the hot flue gas after dust removal and purification by the dust collector is about 8% (volume fraction), which is passed into the carbonization reactor for standby and sinking oxidation
  • the magnesium is discharged from the discharge valve at the lower end of the magnesium oxide dust collector to obtain the desired magnesium expansion component light magnesium oxide.
  • step (1) the undecomposed calcium carbonate continues to sink in the suspension tower by gravity, and the calcination temperature of the lower layer of the suspension reaction tower is controlled to 950°C.
  • the undecomposed calcium carbonate is in the process of descending It absorbs heat and decomposes to generate activated calcium oxide and carbon dioxide.
  • the activated calcium oxide and carbon dioxide produced by the decomposition are discharged from the secondary outlet of the suspension tower under the action of the cyclone negative pressure and enter the calcium oxide dust collector. Calcium oxide and carbon dioxide realize gas-solid separation in the calcium oxide dust collector.
  • the carbon dioxide content in the hot flue gas after dust removal and purification by the dust collector is about 8% (volume fraction), which is passed into the carbonization reactor for standby, sinking
  • the calcium oxide is discharged from the discharge valve at the lower end of the calcium oxide dust collector to obtain activated calcium oxide.
  • Carbonation modification The hot flue gas passed into the carbonization reactor is pressurized and concentrated into a reaction gas with a reaction pressure of 0.5 MPa and a carbon dioxide concentration of 25% (volume fraction), and then the activity in step (2) Calcium oxide is fed into the carbonization reactor by the screw feeder for carbonation reaction.
  • the reaction temperature in the carbonization reactor is controlled to 180°C and the reaction time is 40 minutes.
  • the carbonation modification of the calcium expansion component required by the present invention can be obtained. Expansive calcium oxide clinker.
  • a preparation method of calcium-magnesium composite expansion agent, and its production process is carried out as follows:
  • (1) Preparation of magnesia swelling component first grind dolomite powder into dolomite raw meal powder with a fineness of 80um sieve remaining 5%, and then put the dolomite raw meal powder into the suspension reaction tower to control the calcination temperature of the upper layer of the suspension reaction tower At 650°C, dolomite raw meal powder absorbs heat and decomposes to produce magnesium oxide, carbon dioxide and calcium carbonate during the descending process. Due to the difference in material weight, the magnesium oxide and carbon dioxide produced by the decomposition are processed by the airflow separator of the suspension tower under the action of the cyclone negative pressure, and discharged from the first level outlet of the suspension tower, and enters the magnesium oxide dust collector.
  • Magnesium oxide and carbon dioxide are separated from the gas and solid in the magnesium oxide dust collector.
  • the carbon dioxide content in the hot flue gas after dust removal and purification by the dust collector is about 10% (volume fraction), which is passed into the carbonization reactor for standby and sinking oxidation
  • the magnesium is discharged from the discharge valve at the lower end of the magnesium oxide dust collector to obtain the desired magnesium expansion component light magnesium oxide.
  • step (1) the undecomposed calcium carbonate continues to sink in the suspension tower by gravity, and the calcination temperature of the lower layer of the suspension reaction tower is controlled to 1100°C.
  • the undecomposed calcium carbonate is in the process of falling It absorbs heat and decomposes to generate activated calcium oxide and carbon dioxide.
  • the activated calcium oxide and carbon dioxide produced by the decomposition are discharged from the secondary outlet of the suspension tower under the action of the cyclone negative pressure and enter the calcium oxide dust collector. Calcium oxide and carbon dioxide are separated from the gas and solid in the calcium oxide dust collector.
  • the carbon dioxide content in the hot flue gas after dust removal and purification by the dust collector is about 10% (volume fraction), which is passed into the carbonization reactor for standby, sinking
  • the calcium oxide is discharged from the discharge valve at the lower end of the calcium oxide dust collector to obtain activated calcium oxide.
  • Carbonation modification The hot flue gas passed into the carbonization reactor is pressurized and concentrated into a reaction gas with a reaction pressure of 0.5 MPa and a carbon dioxide concentration of 25% (volume fraction), and then the activity in step (2) Calcium oxide is fed into the carbonization reactor by a screw feeder for carbonation reaction.
  • the reaction temperature in the carbonization reactor is controlled to 220°C and the reaction time is 20 minutes.
  • the carbonation modification of the calcium expansion component required by the present invention can be obtained. Expansive calcium oxide clinker.
  • the dolomite raw materials used in the comparative example of this application are the same as those in application examples 1-3.
  • the dolomite powder is firstly ground into dolomite raw meal powder with a fineness of 80um sieve remaining 5%, and then the dolomite is raw
  • the material powder is calcined at 1100°C for 90 minutes to prepare a calcium-magnesium composite expansion agent composed of a mixture of magnesium oxide and calcium oxide.
  • the concrete mixed with and without expansion agent will produce obvious autogenous volume expansion deformation with the increase of temperature.
  • the concrete mixed with application example 1, application example 2 and application example 3 of the present invention is at temperature.
  • the autogenous volume expansion deformation produced in the rising stage is relatively small, while the autogenous volume expansion deformation of the concrete mixed with Comparative Example 1 is relatively large in the temperature rise stage; in the cooling stage, the reference concrete blank sample without expansion agent and the mixed application
  • the autogenous volume deformation of the concrete in proportion 1 all shrink and deform with the decrease in temperature, and the autogenous volume deformation of the concrete mixed with the application examples of the present invention still shows a certain continuous expansion and deformation at the initial stage of the curing temperature drop.
  • the application example of the present invention has continuous expansion performance in concrete, especially showing obvious expansion during the temperature drop stage, and has better temperature shrinkage of ultra-long and ultra-thick structure concrete. The compensation effect.

Abstract

一种利用白云石制备轻质氧化镁和氧化钙的方法及其用于制备钙镁复合膨胀剂的应用。利用白云石煅烧分解过程中碳酸镁和碳酸钙分解温度差异性以及分解后物料重量的差异性，一步法实现氧化镁和氧化钙有效分离。使用轻质氧化镁和氧化钙制备获得钙镁复合膨胀剂，解决了钙镁复合膨胀剂中镁质膨胀组分轻质氧化镁原料产地限制问题，及钙镁复合膨胀剂中钙质膨胀组分游离氧化钙水化反应速率太快、有效膨胀效能偏小的问题，优化了白云石直接煅烧生产钙镁复合膨胀剂的膨胀历程。

Description

一种制备轻质氧化镁和氧化钙的方法及其用于制备钙镁复合膨胀剂的应用 技术领域
本发明涉及白云石煅烧分解技术，特别涉及一种利用白云石分别制备轻质氧化镁和氧化钙的方法及其用于制备钙镁复合膨胀剂的应用。
背景技术
白云石是碳酸镁和碳酸钙的复盐，分子式为CaMg(CO 3) 2，主要成分为氧化镁、氧化钙、SiO 2、Fe 2O 3，平均含量分别为21.29％、30.42％、0.78％、0.13％。我国白云石资源分布广泛，保有储量为82.2亿吨，产地遍布全国各地，辽宁、内蒙古、山西、河南、河北、江苏、安徽、湖南、湖北、四川、重庆、福建、浙江等地都有大型白云石矿床。
目前白云石主要用来生产轻质氧化镁和钙盐。
轻质氧化镁为无机化工领域产品，主要用于冶金、冶炼、高级镁砖、耐火材料及保湿材料的制造，还广泛用于橡胶、橡胶板、橡胶制品、医药行业、食品行业、塑料板材促进剂、玻璃钢的增塑剂及硅钢片的表面涂层油漆、纸张生产、钢球磨光、皮革处理、绝缘材料、油脂、染料、陶瓷、干燥剂、树脂、阻燃剂等。
钙盐作为白云石生产轻质氧化镁的副产物，根据生产工艺的不同，主要有碳酸钙、硫酸钙以及氯化钙等。碳酸钙可用于水泥生产、烟气脱硫和建筑施工等领域；硫酸钙可用于建筑石膏领域，氯化钙可用于采矿、石油勘探、环境保护等领域。
现有的利用白云石制备轻质氧化镁的方法多是白云石碳酸化法，其方法是先将白云石(Ca氧化镁(CO 3) 2)煅烧分解成氧化镁和氧化钙，然后加水消化制得Mg(OH) 2及Ca(OH) 2，然后用二氧化碳碳酸化得到碳酸氢镁和碳酸钙，除去碳酸钙后母液经热解得到碱式碳酸镁，再经850℃-900℃煅烧，制得轻质氧化镁。这种方法工艺流程长，设备庞大，脱水时间长，能耗高，生产能力小，工艺操作控制难度大，副产品碳酸钙利用价值低。若将此副产物碳酸钙煅烧制备轻质氧化钙， 必将耗费大量的能源，不具备经济合理性。
随着我国工业技术的发展创新和人们环保意识的增强，对矿产资源的有效地开发和利用越来越加重视。市场对高品质镁化合物的需求将会逐年增大，而我国的菱镁矿，及卤水资源分布区域有限，但白云石的分布区域广，蕴藏量丰富，白云石的综合利用对我国的镁资源开发有着重要的现实意义。在利用白云石中镁资源的同时，如何有效利用白云石中的钙资源，是白云石综合利用的重要研究方向。
发明内容
本发明克服现有技术中白云石分解制备轻质氧化镁过程中钙镁分离过中存在的工艺复杂、能耗高、副产品经济价值低的不足之处，提供一种工艺简单、生产能耗低、产品经济价值高的一种利用白云石分别制备轻质氧化镁和氧化钙的方法。并在此方法的基础上进一步制备成钙镁复合膨胀剂。
本发明所述利用白云石分解制备轻质氧化镁和氧化钙的方法，是利用白云石煅烧分解过程中碳酸镁和碳酸钙分解温度差异性以及分解后物料重量的差异性，在悬浮反应塔内根据负压风选原理，一步法即可实现氧化镁和氧化钙有效分离，分别制备得到轻质氧化镁和轻质氧化钙，简化了工艺流程，显著降低了生产能耗，节省了生产成本，提高了轻质氧化镁和轻质氧化钙的市场竞争力，为白云石的综合应用扩展了方向。
本发明所述悬浮反应塔由上下两层煅烧带组成，中间设有气流分选机隔开。
本发明所述的悬浮反应塔气流分选机是指置于悬浮反应塔内部，由旋风系统、变频系统和分隔轮等组成的比重风选分离设备。
本发明的原理为：白云石的煅烧分解过程分为两阶段，
Figure PCTCN2019099571-appb-000001
和
Figure PCTCN2019099571-appb-000002
本发明利用白云石煅烧分解过程中分解温度和分解产物质量的差异性，在悬浮反应塔内设置两层煅烧反应区，悬浮反应塔上层煅烧温度控制在550℃～650℃，可将白云石煅烧分解成氧化镁、碳酸钙和二氧化碳，由于碳酸钙的分子量是氧化镁的2.5倍，通过比重风选分离设备实现氧化镁和碳酸钙的有效分离，分离出的氧化镁收集后即得到本发明所需产品之一轻质氧化镁，未分解的碳酸钙在悬浮反应塔下层900℃～1000℃煅烧温度内继续分解成氧化钙和二氧化碳，收集后即得到本发明所需产品之一轻质氧化钙。
本发明所述利用白云石分解制备轻质氧化镁和氧化钙的方法采用如下工艺步骤：
(1)氧化镁制备：先将白云石粉磨制成细度为80um筛余5％左右的白云石生料粉，将白云石生料粉投入悬浮反应塔，控制悬浮反应塔上层煅烧温度在550℃-650℃左右，白云石生料粉在下降过程中吸收热量分解生成氧化镁、二氧化碳和碳酸钙。由于物料重量的差异性，分解产生的氧化镁和二氧化碳一起在旋风负压的作用下，经悬浮反应塔气流分选机处理，从悬浮反应塔一级出口排出，经氧化镁收尘器中进行气固分离处理后，收集即得到所需产品之一轻质氧化镁。
(2)氧化钙制备：步骤(1)中未分解的碳酸钙受重力作用在悬浮反应塔中继续下沉，控制悬浮反应塔下层煅烧温度在900℃-1000℃左右，未分解的碳酸钙在下降过程中吸收热量分解生成氧化钙和二氧化碳，分解产生的氧化钙和二氧化碳在旋风负压的作用下从悬浮反应塔二级出口排出，经氧化钙收尘器中进行气固分离处理后，收集即得到所需产品之一轻质氧化钙。
现有白云石分别制备氧化镁和氧化钙的方法中大多是先将白云石煅烧分解成氧化镁和氧化钙的混合物，然后加水消化制得Mg(OH) 2和Ca(OH) 2，来实现镁元素和钙元素的分离，最后再加热煅烧才能分别制备得到氧化镁和氧化钙产品。本发明与现有技术相比，利用白云石煅烧分解过程中碳酸镁和碳酸钙分解温度差异性以及分解后物料重量的差异性，在悬浮反应塔内根据负压风选原理，一步法即可实现氧化镁和氧化钙有效分离，分别制备得到轻质氧化镁和轻质氧化钙，简化了工艺流程，显著降低了生产能耗，节省了生产成本，提高了轻质氧化镁和轻质氧化钙的市场竞争力，为白云石的综合应用扩展了方向。
作为前述白云石分解分别制备轻质氧化镁和氧化钙的方法的应用，是用于制备钙镁复合膨胀剂。
所述钙镁复合膨胀剂，由钙质膨胀组分和镁质膨胀组分构成，其中钙质膨胀组分为氧化钙膨胀熟料，镁质膨胀组分为轻质氧化镁，钙质膨胀组分与镁质膨胀组分的质量比为1:1。
所述的钙质膨胀组分为碳酸化改性后的氧化钙膨胀熟料，由白云石煅烧分解生成的活性氧化钙在碳化反应釜中碳酸化改性得到。
所述的镁质膨胀组份为轻质氧化镁，由白云石煅烧分解制备得到。
所述钙镁复合膨胀剂的制备方法，使用前述白云石分解分别制备轻质氧化镁和氧化钙的工艺流程加氧化钙的碳酸化工艺流程获得，利用氧化镁生产过程中产生的二氧化碳，送入碳化反应釜使氧化钙碳酸化，获得的钙质膨胀组分，和前述镁质膨胀组分制备获得钙镁复合膨胀剂，优化了白云石直接煅烧生产钙镁复合膨胀剂的膨胀历程，开辟了一条制备钙镁复合膨胀剂的新途径，降低了钙镁复合膨胀剂的生产成本，提高了钙镁复合膨胀剂的在实际工程中的应用效果，为钙镁复合膨胀剂的推广应用提供市场竞争力，具有显著的社会经济效益。
所述钙镁复合膨胀剂的制备方法，具体采用如下工艺步骤：
(1)镁质膨胀组分制备：前述白云石分解分别制备轻质氧化镁和氧化钙的过程中，氧化镁和二氧化碳在氧化镁收尘器中实现气固分离，经收尘器除尘净化后的热烟气中二氧化碳含量约为8-12％(体积分数)，通入碳化反应釜备用，下沉的轻烧氧化镁由氧化镁收尘器下端的卸料阀排出即得到所需镁质膨胀组分轻烧氧化镁。
(2)活性氧化钙制备：即为前述白云石分解分别制备轻质氧化镁和氧化钙中获得氧化钙的步骤。
(3)碳酸化改性：将通入碳化反应釜中的热烟气加压浓缩成反应压力为0.5MPa，二氧化碳浓度为24％～26％(体积分数)的反应气体，然后将步骤(2)中活性氧化钙由螺旋给料机喂入碳化反应釜中进行碳酸化反应，控制碳化反应釜中的反应温度为180℃-250℃，反应时间为20min-40min，可制得本发明所需钙质膨胀组分碳酸化改性的氧化钙膨胀熟料。
(4)复配组合：将步骤(1)制得的镁质膨胀组分和步骤(3)制得的钙质膨胀组分按质量比为1:1投入搅拌机内搅拌2min、充分混合均匀后即得到本发明产品：一种新型钙镁复合膨胀剂。
氧化钙与二氧化碳反应生成碳酸钙是一种公知技术，公开号CN104671688A的中国专利文献(一种改性氧化钙类膨胀熟料、其制备方法及其应用)和公开号CN102459116A的中国专利文献(膨胀材料及其制造方法)均公开了利用氧化钙与二氧化碳进行碳酸化反应来延缓氧化钙熟料水化速率的方法，要么选择在200℃-800℃高温条件下进行碳酸化处理，要么选择利用水气的催化作用在小于200℃低温条件下进行碳酸化处理，归结起来这些技术路线均在常压条件下进行碳酸化反应。本发明根据生产设备的自身特点，利用白云石在悬浮反应塔中煅烧 分解过程中产生的二氧化碳，经过滤除尘净化后进入碳化反应釜加压浓缩与活性氧化钙进行碳酸化反应，优选的碳酸化反应压力为0.5MPa，碳酸化反应温度为180℃-250℃，二氧化碳反应浓度为24％～26％(体积分数)。
本发明与现有产品相比，本发明以储量丰富的白云石为原料，通过悬浮反应塔和碳化反应釜，分别制备钙镁复合膨胀剂中的镁质膨胀组分轻质氧化镁和钙质膨胀组分碳酸化改性的氧化钙膨胀熟料，在确保镁质膨胀组分轻质氧化镁反应活性的前提下，利用碳酸化改性生成的碳酸钙包裹钙质膨胀组分游离氧化钙，降低钙质膨胀组分的反应活性，调控钙质膨胀组分的膨胀速率。一方面解决了钙镁复合膨胀剂中镁质膨胀组分轻质氧化镁原料产地限制问题，另一方面解决了钙镁复合膨胀剂中钙质膨胀组分游离氧化钙水化反应速率太快、有效膨胀效能偏小的问题，优化了白云石直接煅烧生产钙镁复合膨胀剂的膨胀历程，开辟了一条制备钙镁复合膨胀剂的新途径，降低了钙镁复合膨胀剂的生产成本，提高了钙镁复合膨胀剂的在实际工程中的应用效果，为钙镁复合膨胀剂的推广应用提供市场竞争力，具有显著的社会经济效益。
附图说明
图1所示为利用白云石分别制备轻质氧化镁和氧化钙的制备工艺流程图。
图2为钙镁复合膨胀剂的制备工艺流程图。
图3为模拟超长超厚结构混凝土温度变化的测试温度变化曲线图。
图4为未掺膨胀剂的基准混凝土空白样、掺7％本发明应用实施例1、掺7％本发明应用实施例2的混凝土、掺7％本发明应用实施例3的混凝土以及掺7％应用对比例1的混凝土在变温养护条件下的自生体积变形曲线图。
具体实施方式
为了更好的理解本发明，下面结合具体实施例进一步阐明本发明的内容，但本发明的内容不仅仅局限于下面的实施例。本发明实施例中所使用的硬石膏白云石来自安徽白云石矿矿区，主要成分按重量百分比为氧化镁21.10％、氧化钙30.28％、SiO 2 0.92％、Fe 2O 3 0.37％、Al 2O 3 0.39％、烧失量46.51％。
(一)利用白云石分解分别制备轻质氧化镁和氧化钙
实施例1
一种利用白云石分别制备轻质氧化镁和氧化钙的方法，包括以下两个步骤：
(1)氧化镁制备：先将白云石粉磨制成细度为80um筛余4％的白云石生料粉，将白云石生料粉投入悬浮反应塔，控制悬浮反应塔上层煅烧温度在550℃，白云石生料粉在下降过程中吸收热量分解生成氧化镁、二氧化碳和碳酸钙。由于物料重量的差异性，分解产生的氧化镁和二氧化碳一起在旋风负压的作用下，经悬浮反应塔气流分选机处理，从悬浮反应塔一级出口排出，经氧化镁收尘器中进行气固分离处理后，收集即得到本发明产品之一轻质氧化镁。参照现行黑色冶金行业标准YB/T5206-2004《轻烧氧化镁》规定的方法测试本发明制备得到的轻质氧化镁化学成分，结果见表1所示。由表1中数据可以看出，本发明制备的轻质氧化镁满足CBM85的要求。
表1
Figure PCTCN2019099571-appb-000003
(2)氧化钙制备：步骤(1)中未分解的碳酸钙受重力作用在悬浮反应塔中继续下沉，控制悬浮反应塔下层煅烧温度在900℃，未分解的碳酸钙在下降过程中吸收热量分解生成氧化钙和二氧化碳，分解产生的氧化钙和二氧化碳在旋风负压的作用下从悬浮反应塔二级出口排出，经氧化钙收尘器中进行气固分离处理后，收集即得到本发明产品之一轻质氧化钙。参照现行化工行业标准HG/T 4205-2011《工业氧化钙》规定的方法测试本发明制备得到的轻质氧化钙化学成分，结果见表2所示。由表2中数据可以看出，本发明制备的轻质氧化钙满足化工行业标准《工业氧化钙》Ⅲ类产品的要求，可用于塑料橡胶制造以及烟气脱硫等行业。
表2
Figure PCTCN2019099571-appb-000004
实施例2
一种利用白云石分别制备轻质氧化镁和氧化钙的方法，包括以下两个步骤：
(1)氧化镁制备：先将白云石粉磨制成细度为80um筛余5％的白云石生料粉，将白云石生料粉投入悬浮反应塔，控制悬浮反应塔上层煅烧温度在600℃，白云石生料粉在下降过程中吸收热量分解生成氧化镁、二氧化碳和碳酸钙。由于物料重量的差异性，分解产生的氧化镁和二氧化碳一起在旋风负压的作用下，经悬浮反应塔气流分选机处理，从悬浮反应塔一级出口排出，经氧化镁收尘器中进行气固分离处理后，收集即得到本发明产品之一轻质氧化镁。参照现行黑色冶金行业标准YB/T5206-2004《轻烧氧化镁》规定的方法测试本发明制备得到的轻质氧化镁化学成分，结果见表3所示。由表3中数据可以看出，本发明制备的轻质氧化镁满足CBM85的要求。
表3
Figure PCTCN2019099571-appb-000005
(2)氧化钙制备：步骤(1)中未分解的碳酸钙受重力作用在悬浮反应塔中继续下沉，控制悬浮反应塔下层煅烧温度在950℃，未分解的碳酸钙在下降过程中吸收热量分解生成氧化钙和二氧化碳，分解产生的氧化钙和二氧化碳在旋风负压的作用下从悬浮反应塔二级出口排出，经氧化钙收尘器中进行气固分离处理后，收集即得到本发明产品之一轻质氧化钙。参照现行化工行业标准HG/T 4205-2011《工业氧化钙》规定的方法测试本发明制备得到的轻质氧化钙化学成分，结果见表4所示。由表4中数据可以看出，本发明制备的轻质氧化钙满足化工行业标准《工业氧化钙》Ⅲ类产品的要求，可用于塑料橡胶制造以及烟气脱硫等行业。
表4
Figure PCTCN2019099571-appb-000006
实施例3
一种利用白云石分别制备轻质氧化镁和氧化钙的方法，包括以下两个步骤：
(1)氧化镁制备：先将白云石粉磨制成细度为80um筛余6％的白云石生料粉，将白云石生料粉投入悬浮反应塔，控制悬浮反应塔上层煅烧温度在650℃，白云石生料粉在下降过程中吸收热量分解生成氧化镁、二氧化碳和碳酸钙。由于物料重量的差异性，分解产生的氧化镁和二氧化碳一起在旋风负压的作用下，经悬浮反应塔气流分选机处理，从悬浮反应塔一级出口排出，经氧化镁收尘器中进行气固分离处理后，收集即得到本发明产品之一轻质氧化镁。参照现行黑色冶金行业标准YB/T5206-2004《轻烧氧化镁》规定的方法测试本发明制备得到的轻质氧化镁化学成分，结果见表5所示。由表5中数据可以看出，本发明制备的轻质氧化镁满足CBM85的要求。
表5
Figure PCTCN2019099571-appb-000007
(2)氧化钙制备：步骤(1)中未分解的碳酸钙受重力作用在悬浮反应塔中继续下沉，控制悬浮反应塔下层煅烧温度在1000℃，未分解的碳酸钙在下降过程中吸收热量分解生成氧化钙和二氧化碳，分解产生的氧化钙和二氧化碳在旋风负压的作用下从悬浮反应塔二级出口排出，经氧化钙收尘器中进行气固分离处理后，收集即得到本发明产品之一轻质氧化钙。参照现行化工行业标准HG/T 4205-2011《工业氧化钙》规定的方法测试本发明制备得到的轻质氧化钙化学成分，结果见表6所示。由表6中数据可以看出，本发明制备的轻质氧化钙满足化工行业标准《工业氧化钙》Ⅲ类产品的要求，可用于塑料橡胶制造以及烟气脱硫等行业。
表6
Figure PCTCN2019099571-appb-000008
(二)钙镁复合膨胀剂
应用实施例1
一种钙镁复合膨胀剂的制备方法，其生产工艺按如下步骤进行：
(1)镁质膨胀组分制备：先将白云石粉磨制成细度为80um筛余5％的白云石生料粉，然后将白云石生料粉投入悬浮反应塔，控制悬浮反应塔上层的煅烧温度为600℃，白云石生料粉在下降过程中吸收热量分解生成氧化镁、二氧化碳和碳酸钙。由于物料重量的差异性，分解产生的氧化镁和二氧化碳一起在旋风负压的作用下，经悬浮塔气流分选机处理，从悬浮塔一级出口排出，进入氧化镁收尘器。氧化镁和二氧化碳在氧化镁收尘器中实现气固分离，经收尘器除尘净化后的热烟气中二氧化碳含量约为12％(体积分数)，通入碳化反应釜备用，下沉的氧化镁由氧化镁收尘器下端的卸料阀排出即得到所需镁质膨胀组分轻质氧化镁。
(2)活性氧化钙制备：步骤(1)中未分解的碳酸钙受重力作用在悬浮塔中继续下沉，控制悬浮反应塔下层的煅烧温度为1050℃，未分解的碳酸钙在下降过程中吸收热量分解生成活性氧化钙和二氧化碳，分解产生的活性氧化钙和二氧化碳在旋风负压的作用下从悬浮塔二级出口排出，进入氧化钙收尘器。氧化钙和二氧化碳在氧化钙收尘器中实现气固分离，经收尘器除尘净化后的热烟气中二氧化碳含量约为12％，(体积分数)，通入碳化反应釜备用，下沉的氧化钙由氧化钙收尘器下端的卸料阀排出得到活性氧化钙。
(3)碳酸化改性：将通入碳化反应釜中的热烟气加压浓缩成反应压力为0.5MPa，二氧化碳浓度为25％(体积分数)的反应气体，然后将步骤(2)中活性氧化钙由螺旋给料机喂入碳化反应釜中进行碳酸化反应，控制碳化反应釜中的反应温度为220℃，反应时间为30min，可制得本发明所需钙质膨胀组分碳酸化改性的氧化钙膨胀熟料。
(4)复配组合：将步骤(1)制得的镁质膨胀组分和步骤(3)制得的钙质膨胀组分按质量比为1:1投入搅拌机内搅拌2min、充分混合均匀后即得到本发明产品一种新型钙镁复合膨胀剂。
应用实施例2
一种钙镁复合膨胀剂的制备方法，其生产工艺按如下步骤进行：
(1)镁质膨胀组分制备：先将白云石粉磨制成细度为80um筛余5％的白云石生料粉，然后将白云石生料粉投入悬浮反应塔，控制悬浮反应塔上层的煅烧温度为 550℃，白云石生料粉在下降过程中吸收热量分解生成氧化镁、二氧化碳和碳酸钙。由于物料重量的差异性，分解产生的氧化镁和二氧化碳一起在旋风负压的作用下，经悬浮塔气流分选机处理，从悬浮塔一级出口排出，进入氧化镁收尘器。氧化镁和二氧化碳在氧化镁收尘器中实现气固分离，经收尘器除尘净化后的热烟气中二氧化碳含量约为8％(体积分数)，通入碳化反应釜备用，下沉的氧化镁由氧化镁收尘器下端的卸料阀排出即得到所需镁质膨胀组分轻质氧化镁。
(2)活性氧化钙制备：步骤(1)中未分解的碳酸钙受重力作用在悬浮塔中继续下沉，控制悬浮反应塔下层的煅烧温度为950℃，未分解的碳酸钙在下降过程中吸收热量分解生成活性氧化钙和二氧化碳，分解产生的活性氧化钙和二氧化碳在旋风负压的作用下从悬浮塔二级出口排出，进入氧化钙收尘器。氧化钙和二氧化碳在氧化钙收尘器中实现气固分离，经收尘器除尘净化后的热烟气中二氧化碳含量约为8％，(体积分数)，通入碳化反应釜备用，下沉的氧化钙由氧化钙收尘器下端的卸料阀排出得到活性氧化钙。
(3)碳酸化改性：将通入碳化反应釜中的热烟气加压浓缩成反应压力为0.5MPa，二氧化碳浓度为25％(体积分数)的反应气体，然后将步骤(2)中活性氧化钙由螺旋给料机喂入碳化反应釜中进行碳酸化反应，控制碳化反应釜中的反应温度为180℃，反应时间为40min，可制得本发明所需钙质膨胀组分碳酸化改性的氧化钙膨胀熟料。
(4)复配组合：将步骤(1)制得的镁质膨胀组分和步骤(3)制得的钙质膨胀组分按质量比为1:1投入搅拌机内搅拌2min、充分混合均匀后即得到本发明产品一种新型钙镁复合膨胀剂。
应用实施例3
一种钙镁复合膨胀剂的制备方法，其生产工艺按如下步骤进行：
(1)镁质膨胀组分制备：先将白云石粉磨制成细度为80um筛余5％的白云石生料粉，然后将白云石生料粉投入悬浮反应塔，控制悬浮反应塔上层的煅烧温度为650℃，白云石生料粉在下降过程中吸收热量分解生成氧化镁、二氧化碳和碳酸钙。由于物料重量的差异性，分解产生的氧化镁和二氧化碳一起在旋风负压的作用下，经悬浮塔气流分选机处理，从悬浮塔一级出口排出，进入氧化镁收尘器。氧化镁和二氧化碳在氧化镁收尘器中实现气固分离，经收尘器除尘净化后的热烟气中二氧化碳含量约为10％(体积分数)，通入碳化反应釜备用，下沉的氧化镁由氧化镁收尘 器下端的卸料阀排出即得到所需镁质膨胀组分轻质氧化镁。
(2)活性氧化钙制备：步骤(1)中未分解的碳酸钙受重力作用在悬浮塔中继续下沉，控制悬浮反应塔下层的煅烧温度为1100℃，未分解的碳酸钙在下降过程中吸收热量分解生成活性氧化钙和二氧化碳，分解产生的活性氧化钙和二氧化碳在旋风负压的作用下从悬浮塔二级出口排出，进入氧化钙收尘器。氧化钙和二氧化碳在氧化钙收尘器中实现气固分离，经收尘器除尘净化后的热烟气中二氧化碳含量约为10％，(体积分数)，通入碳化反应釜备用，下沉的氧化钙由氧化钙收尘器下端的卸料阀排出得到活性氧化钙。
(3)碳酸化改性：将通入碳化反应釜中的热烟气加压浓缩成反应压力为0.5MPa，二氧化碳浓度为25％(体积分数)的反应气体，然后将步骤(2)中活性氧化钙由螺旋给料机喂入碳化反应釜中进行碳酸化反应，控制碳化反应釜中的反应温度为220℃，反应时间为20min，可制得本发明所需钙质膨胀组分碳酸化改性的氧化钙膨胀熟料。
(4)复配组合：将步骤(1)制得的镁质膨胀组分和步骤(3)制得的钙质膨胀组分按质量比为1:1投入搅拌机内搅拌2min、充分混合均匀后即得到本发明产品一种新型钙镁复合膨胀剂。
应用对比例1
本应用对比例所使用的白云石原料同应用实施例1-3，根据现有的公知技术，先将白云石粉磨制成细度为80um筛余5％的白云石生料粉，再将白云石生料粉在1100℃温度下煅烧90min，制备得到由氧化镁和氧化钙混合物组成的钙镁复合膨胀剂。
现有的标准评价膨胀剂的对混凝土的收缩补偿性能均是在恒温标养条件下进行，但实际混凝土结构中水泥水化放热或者外界环境的变化使混凝土的温度随时间变化。为了评价本发明在实际工程中的应用效果，取某段结构混凝土90d龄期内的实际温度变化历程作为测试温度曲线，对比评价本发明实施例和对比例在变温养护环境下的收缩补偿效果。
表7 检测混凝土用配合比
Figure PCTCN2019099571-appb-000009
Figure PCTCN2019099571-appb-000010
采用本发明所得到的应用实施例和应用对比例，与不掺膨胀剂的空白样本进行混凝土检测试验。按表7所示的混凝土配合比，在搅拌机中将本发明应用实施例、应用对比例和组成混凝土的其他原料共同搅拌成所需混凝土拌合物，控制混凝土出机坍落度140mm-160mm，浇筑成型φ150×500mm的混凝土圆柱体，在试件内埋设应变计，密封养护于环境试验箱中，环境试验箱中的测试温度变化曲线见图3。以混凝土终凝时间为开始测量的起始时间，样品在变温养护时的混凝土自生体积变形测试结果见图4。
结果表明：升温阶段，掺与不掺膨胀剂的混凝土均随温度的升高产生明显的自生体积膨胀变形，其中掺本发明应用实施例1、应用实施例2和应用实施例3的混凝土在温升阶段产生的自生体积膨胀变形相对较小，而掺应用对比例1的混凝土在温升阶段产生的自生体积膨胀变形相对较大；降温阶段，不掺膨胀剂的基准混凝土空白样和掺应用对比例1的混凝土自生体积变形均随温度的下降产生收缩变形，而掺本发明的应用实施例的混凝土自生体积变形在养护温度下降阶段初期依然表现出一定的持续膨胀变形。可见，与应用对比例1相比，本发明的应用实施例在混凝土中具有持续的膨胀性能，特别是在温降阶段表现出明显的膨胀，对超长超厚结构混凝土的温度收缩具有更好的补偿效果。

Claims (10)

  1. 一种制备轻质氧化镁和氧化钙的方法，其特征在于，是利用白云石煅烧分解过程中碳酸镁和碳酸钙分解温度差异性以及分解后物料重量的差异性，在悬浮反应塔内根据负压风选原理，一步法实现氧化镁和氧化钙有效分离，分别制备得到轻质氧化镁和轻质氧化钙。
  2. 根据权利要求1所述的方法，其特征在于，所述悬浮反应塔由上下两层煅烧带组成，中间设有气流分选机隔开。
  3. 根据权利要求2所述的方法，其特征在于，所述的悬浮反应塔气流分选机是指置于悬浮反应塔内部，是由旋风系统、变频系统和分隔轮组成的比重风选分离设备。
  4. 根据权利要求3述的方法，其特征在于，在悬浮反应塔内设置两层煅烧反应区，悬浮反应塔上层煅烧温度控制在550℃～650℃，将白云石煅烧分解成氧化镁、碳酸钙和二氧化碳，由于碳酸钙的分子量是氧化镁的2.5倍，通过比重风选分离设备实现氧化镁和碳酸钙的有效分离，分离出的氧化镁收集后即得轻质氧化镁，未分解的碳酸钙在悬浮反应塔下层900℃～1000℃煅烧温度内继续分解成氧化钙和二氧化碳，收集后即得到轻质氧化钙。
  5. 根据权利要求4述的方法，其特征在于，采用如下工艺步骤：
    (1)氧化镁制备：先将白云石粉磨制成细度为80um筛余4％～6％的白云石生料粉，将白云石生料粉投入悬浮反应塔，控制悬浮反应塔上层煅烧温度在550℃-650℃，白云石生料粉在下降过程中吸收热量分解生成氧化镁、二氧化碳和碳酸钙；由于物料重量的差异性，分解产生的氧化镁和二氧化碳一起在旋风负压的作用下，经悬浮反应塔气流分选机处理，从悬浮反应塔一级出口排出，经氧化镁收尘器中进行气固分离处理后，收集即得到所需产品之一轻质氧化镁；
    (2)氧化钙制备：步骤(1)中未分解的碳酸钙受重力作用在悬浮反应塔中继续下沉，控制悬浮反应塔下层煅烧温度在900℃-1000℃，未分解的碳酸钙在下降过程中吸收热量分解生成氧化钙和二氧化碳，分解产生的氧化钙和二氧化碳在旋风负压的作用下从悬浮反应塔二级出口排出，经氧化钙收尘器中进行气固分离处理后，收集即得到所需产品之一轻质氧化钙。
  6. 权利要求1-5的任一项所述的方法的应用，其特征在于，是用于制备钙镁复 合膨胀剂。
  7. 根据权利要求6所述的应用，制备钙镁复合膨胀剂的方法，其特征在于，使用前述白云石分解分别制备轻质氧化镁和氧化钙的工艺流程加氧化钙的碳酸化工艺流程获得，获得的碳酸化的钙质膨胀组分，和前述镁质膨胀组分制备获得钙镁复合膨胀剂。
  8. 根据权利要求7所述的方法，其特征在于，所述碳酸化工艺流程，即为设置碳化反应釜，利用氧化镁生产过程中产生的二氧化碳，送入碳化反应釜使氧化钙碳酸化。
  9. 根据权利要求8所述的方法，其特征在于，具体采用如下工艺步骤：
    (1)镁质膨胀组分制备：前述白云石分解分别制备轻质氧化镁和氧化钙的过程中，氧化镁和二氧化碳在氧化镁收尘器中实现气固分离，经收尘器除尘净化后的热烟气中二氧化碳含量为8-12％，通入碳化反应釜备用，下沉的轻质氧化镁由氧化镁收尘器下端的卸料阀排出即得到所需镁质膨胀组分轻质氧化镁；
    (2)活性氧化钙制备：即为前述白云石分解分别制备轻质氧化镁和氧化钙中获得氧化钙的步骤；
    (3)碳酸化改性：将通入碳化反应釜中的热烟气加压浓缩成反应压力为0.5MPa，二氧化碳浓度为24％～26％的反应气体，然后将步骤(2)中活性氧化钙由螺旋给料机喂入碳化反应釜中进行碳酸化反应，控制碳化反应釜中的反应温度为180℃-250℃，反应时间为20min-40min，可制得所需钙质膨胀组分碳酸化改性的氧化钙膨胀熟料；
    (4)复配组合：将步骤(1)制得的镁质膨胀组分和步骤(3)制得的钙质膨胀组分按质量比为1:1投入搅拌机内搅拌2min、充分混合均匀后即得到本发明产品：一种新型钙镁复合膨胀剂。
  10. 权利要求6-9所述应用获得的钙镁复合膨胀剂，其特征在于，由钙质膨胀组分和镁质膨胀组分构成，其中钙质膨胀组分为碳酸化改性后的氧化钙膨胀熟料，镁质膨胀组分为轻质氧化镁，碳酸化改性后的钙质膨胀组分与镁质膨胀组分的质量比为1:1；
    所述的钙质膨胀组分为碳酸化改性后的氧化钙膨胀熟料，由白云石煅烧分解生成的活性氧化钙经碳酸化改性得到；
    所述的镁质膨胀组份为轻质氧化镁，由白云石煅烧分解制备得到。
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