Abstract
A method for preparing active magnesium oxide comprises the following steps: injecting a raw material of a magnesium chloride solution, and mixed gas of NH3 and CO2 into a hypergravity reactor, performing a rapid mixing reaction of the gas and the liquid under a hypergravity condition, wherein the magnesium chloride solution concentration is 0.2-0.5 mol/L, the volume ratio of NH3 to CO2 is (1.6-2.4):1, the reaction temperature is 70-80 DEG C, the hypergravity level is 150-960 g, performing reaction precipitation, filtration, washing, and drying to obtain an intermediate of basic magnesium carbonate, then calcining the basic magnesium carbonate at a temperature of 500-900 DEG C to obtain the active magnesium oxide. The invention can reach the requirement of rapid gas-liquid mixing so as to realize rapid microscopic uniform mixing under a condition with a high reaction solution solute concentration and a large processing capacity, and thus reach the homogeneous nucleation condition required by the preparation of the intermediate of basic magnesium carbonate; the method of the invention is simple in process, easy to control, free of aging, high in efficiency, and high in product activity.
Description
A kind of method of preparing activated magnesia
Technical field
The present invention relates to a kind of preparation method of activated magnesia, specifically adopt gas-liquid short mix reaction precipitation to prepare presoma magnesium basic carbonate, then at high temperature calcine presoma magnesium basic carbonate and obtain activated magnesia, belong to ultra-fine grain preparation field.
Background technology
Activated magnesia (Magnesium oxide, activated), molecular formula MgO, relative molecular mass 40.30,2852 DEG C of fusing points, boiling point is 3600 DEG C, is a kind of odorless, tasteless, the nontoxic unformed powder of white.Activated magnesia is insoluble in water, is insoluble to alcohol, is dissolved in acid or ammonium salt solution.Solubleness in water is along with CO in water 2the increase of content and increasing.Absorb airborne carbonic acid gas and water and can generate magnesium basic carbonate.
Activated magnesia, owing to having the advantages such as the photopermeability that granular, high reactivity, the specific surface area of particle is large, good, is widely used in the fields such as electronics, electrical equipment, optics, instrument, national defence, aerospace.Activated magnesia can also be as efficient Dissociative agent, and absorption toxic chemical substance, is widely used in field of environment protection.
The production method of activated magnesia is a lot, can be divided into by the source difference of raw material: the one, and the production method taking mineral as raw material; The 2nd, the production method taking bittern as raw material.
(1) production method taking mineral as raw material
In traditional industry, producing activated magnesia mainly produces taking rhombspar as raw material.Rhombspar main component is CaMg (CO 3) 2, chemical composition is CaO:41%, MgO:21.86%, CO 2: 47.33%.Belonging to trigonal system, is the double salt of calcium carbonate and magnesiumcarbonate.Its major impurity is Fe, and Mn also has Zn, Ni and Co once in a while.
Rhombspar carborization reaction principle is as follows:
MgCO 3·CaCO 3→MgO+CaO+2CO 2↑
MgO+CaO+2H 2O→Mg(OH) 2+Ca(OH) 2
Ca(OH) 2+2CO 2→CaCO 3+H 2O
Mg(OH) 2+2CO 2→Mg(HCO 3) 2
Mg(HCO 3) 2+2H 2O→MgCO 3·3H 2O+CO 2↑
5MgCO 3·3H 2O→4MgCO 3·Mg(OH) 2·8H 2O+6H 2O+CO 2↑
4MgCO 3·Mg(OH) 2·8H 2O→4MgCO 3·Mg(OH) 2·5H 2O+3H 2O
4MgCO 3·Mg(OH) 2·5H 2O→4MgCO 3·Mg(OH) 2·4H 2O+H 2O
4MgCO 3·Mg(OH) 2·4H 2O→5MgO+5H 2O+4CO 2↑
Its concrete chemical process is that rhombspar and anthracite proportioning are by a certain percentage sent into calcining in lime calcining cellar for storing things, obtains clinker dolomite (MgOCaO).In digestive shelf, under stirring state, directly clinker dolomite is digested to dolomite ash breast with hot water or useless magnesium water, again by certain density dolomite ash breast with being pumped into carbonating tower, use the carbonic acid gas through washing and purifying from lime calcining kiln to carry out carburizing reagent to Dolomite milk.The main component of the carbonization solution after carburizing reagent is Magnesium hydrogen carbonate, and throw out is calcium carbonate.Filter the heavy magnesium water that obtains clarification by flame filter press, through being pumped into pyrolysis groove, make its pyrolysis generate magnesium basic carbonate with steam direct heating clear liquor.Magnesium basic carbonate suspension liquid after pyrolysis filters and obtains filter cake through plate-and-frame filter press, and filter cake is predrying, and remove portion free water, then delivers in calcining furnace, and calcining at a certain temperature obtains Product Activity magnesium oxide.
(2) production method taking bittern as raw material
Producing high-purity and ultra-pure magnesium products with the liquid magnesium such as seawater, bittern resource has many good qualities.The impurity phase containing in seawater, bittern is to less, simpler than removal of impurities in magnesium ore deposit as impurity removing operation, and the cost of removal of impurities also can reduce greatly.Its preparation method mainly contains bittern carborization, bittern-ammonia process, bittern-ammonium carbonate method etc.
Bittern-carborization
This method is taking the magnesium chloride containing such as bittern, seawater solution and Adlerika etc. as raw material, with the carbonic acid gas, rhombspar or the lime that after rhombspar or limestone calcination, produce be raw material, digest, the reaction such as precipitation, carbonization, pyrolysis, calcining produces activated magnesia.
Bittern-carborization reaction principle is as follows:
Dolomite calcination MgCO 3caCO 3→ MgOCaO+2CO 2↑
Or limestone calcination CaCO 3→ CaO+2CO 2↑
Digestion MgOCaO+2H 2o → Mg (OH) 2+ Ca (OH) 2
Precipitation MgCl 2+ Ca (OH) 2→ Mg (OH) 2+ CaCl 2
Carbonization Mg (OH) 2+ 2CO 2→ Mg (HCO 3) 2
Pyrolysis Mg (HCO 3) 2+ 2H 2o → MgCO 33H 2o+CO 2↑
5MgCO 3·3H 2O→4MgCO 3·Mg(OH) 2·8H 2O+6H 2O+CO 2↑
4MgCO 3·Mg(OH) 2·8H 2O→4MgCO 3·Mg(OH) 2·5H 2O+3H 2O
4MgCO 3·Mg(OH) 2·5H 2O→4MgCO 3·Mg(OH) 2·4H 2O+H 2O
Calcining 4MgCO 3mg (OH) 24H 2o → 5MgO+5H 2o+4CO 2↑
The concrete reaction process of this method mainly comprises: rhombspar or Wingdale obtain dolomite ash through calcining, adds water after digestion, reacts and obtains magnesium hydrate precipitate with bittern.Precipitated magnesium hydroxide obtains carbonization solution after carbonization, and its main component is Magnesium hydrogen carbonate.By clear liquor, through being pumped into pyrolysis groove, pyrolysis generates magnesium basic carbonate.Magnesium basic carbonate suspension liquid after pyrolysis obtains Product Activity magnesium oxide after filtering, wash, dewater, be dried and calcining.
Bittern-ammonia process
The method is one of important method of producing activated magnesia.It has history very remote, and along with the progress of needs and the equipment of social development, this method also progressively occupies a tiny space in the production of activated magnesia.The principle of this technique is very simple, is about to the exquisite bittern of crossing and reacts generation magnesium hydroxide with ammoniacal liquor, calcines and obtain Product Activity magnesium oxide.
The reaction principle of bittern-ammonia process is as follows:
MgCl 2+2NH 3·H 2O→Mg(OH) 2+2NH 4Cl
Mg(OH) 2→MgO+H 2O
Its main process comprises: the dry and calcining of halogen water purification, logical ammonia precipitation magnesium hydroxide, magnesium hydroxide.Ammonia or ammoniacal liquor are passed in the exquisite bittern that concentration is 0.2mol/L, and temperature of reaction is advisable at 50-60 DEG C, now Mg 2+transformation efficiency larger, pH value is greater than 12, is conducive to reaction and carries out to generating magnesium hydrate precipitate direction, in order to obtain the magnesium hydroxide that particle is less, can adopt logical ammonia speed faster, generally in 1-2h, logical ammonia is complete.The reaction paste obtaining is filtered and obtained magnesium hydrate precipitate by vacuum filter or plate-and-frame filter press.To precipitate repetitive scrubbing several times, wash away the soluble impurity that magnesium hydroxide surface adsorption, obtain the magnesium hydroxide that purity is high.The magnesium hydrate precipitate having washed is dewatered, dry, calcining obtains activated magnesia.
Bittern-ammonium carbonate method
The main raw material of this explained hereafter is bittern (or Magnesium dichloride hexahydrate) and volatile salt (or bicarbonate of ammonia) cheap and easy to get.
The reaction principle of bittern-ammonium carbonate method is as follows:
MgCl 2+4NH 4HCO 3+2H 2O→MgCO 3·(NH 4) 2CO 3·4H 2O+2NH 4Cl+2CO 2↑
5[MgCO 3·(NH 4) 2CO 3·4H 2O]→4MgCO 3·Mg(OH) 2·4H 2O+10NH 3+6CO 2↑+20H 2O
4MgCO 3·Mg(OH) 2·4H 2O→5MgO+5H 2O+4CO 2↑
Concrete technology is: by bittern purifying, be mixed with certain density strong solution, concentration and the bittern concentration of volatile salt are suitable.Volatile salt is joined in bittern, quickly heats up to more than 70 DEG C with superheated vapour, obtain a large amount of white precipitates, after system ageing 1h, put into suction filter, with deionized water wash to filtrate substantially without till chlorion.The filter cake obtaining is transferred in moisture eliminator and is dried, then pulverize, finally send in calcining furnace and calcine, obtain Product Activity magnesium oxide.
The shortcomings such as it is low that aforesaid method all exists purity, active low, and economy is low, and environmental benefit is low.The present invention, compared with bittern-ammonium carbonate method and additive method, it is advantageous that, the standby Product Activity magnesium oxide of this legal system is not only active high but also purity is also very high, and this method does not need to prepare ammonium bicarbonate solution, the useless NH that can directly be discharged by factory 3and CO 2through hypergravity machine by MgCl 2after solution coupling absorption reaction, make precursor magnesium basic carbonate.Adopt hypergravity machine as reaction unit, use MgCl 2solution coupling absorbs NH 3and CO 2prepare activated magnesia, both can save installation cost, can strengthen again NH 3and CO 2assimilation effect.And this technique is simple easily to be controlled, and preparation process does not need ageing, and direct filtration drying and calcining obtains Product Activity magnesium oxide.
Summary of the invention
The present invention is directed to the deficiency that prior art exists, the production method of the activated magnesia that a kind of technique is simple, product yield is high, production cost is low, contamination-free produces is provided.
A kind of method of preparing activated magnesia of the present invention, is characterized in that, comprises the following steps: with industrial hex-ammoniate, CO 2and NH 3for raw material, taking supergravity reactor as reaction unit, NH 3and CO 2volume ratio be (1.6-2.4): 1; First, magnesium chloride solution is heated to 50-80 DEG C, introduce rotor internal cavity by liquid inlet tube, be sprayed at through shower nozzle on the inner edge of rotating rotor, liquid enters the effect that is subject to filler in rotor after rotor, circumferential speed increases, and the centrifugal force of generation pushes it against rotor outer rim, and liquid is thrown to after shell collects and leaves hypergravity machine through liquid outlet tube by rotor; Carbonic acid gas, ammonia gas mixture through gas inlet tube by tangentially introducing rotor exocoel, under the effect of pressure difference, entering filler by rotor outer rim contacts with liquid countercurrent, under hypergravity condition, complete after mass transfer and reaction process, gas leaves rotor from rotor center, is drawn by gas outlet tube.Liquid circulation charging, the disposable charging of gas, whole reactive system is by temperature regulating device temperature control, temperature of reaction keeps 70-80 DEG C, reaction finishes rear filtration, gained solid washes away ammonium ion and chlorion with deionized water, at temperature 100-110 DEG C, is dried and obtains intermediates magnesium basic carbonate, subsequently magnesium basic carbonate is calcined and is obtained activated magnesia at temperature 500-900 DEG C.Mother liquor send soda factory to recycle.Its reaction equation is as follows:
5MgCl 2+4CO 2+10NH 3+10H 2O→4MgCO 3·Mg(OH) 2·4H 2O+10NH 4Cl
4MgCO 3·Mg(OH) 2·4H 2O→5MgO+5H 2O+4CO 2↑
Density of magnesium chloride is 0.1-1mol/L, more preferably 0.2-0.5mol/L; Working pressure is normal pressure, 1atm; The preferred 150-960g of hypergravity level; The preferred 1-8 of vapour-liquid volume ratio; Calcining temperature remains on 500-900 DEG C of scope, preferably 500-700 DEG C; The circulating reaction time is preferably 25-35min.
The reacted reaction mixture body of magnesium chloride solution and mixed gas counter current contact enters stirring tank through discharge gate, then squeezes into supergravity reactor through recycle pump and continues to loop NH 3and CO 2absorption reaction, whole reactive system, by temperature regulating device temperature control, filters after reaction reaches terminal, is dry cake at 100-110 DEG C in temperature, obtain intermediates magnesium basic carbonate, subsequently magnesium basic carbonate is calcined and obtained activated magnesia under temperature 500-900 DEG C condition.
Magnesium chloride solution of the present invention is configured according to common collocation method, and raw material adopts industrial hex-ammoniate, and dissolve medium adopts tap water.NH 3and CO 2can directly adopt the useless NH being discharged by factory 3and CO 2.
Reaction raw materials density of magnesium chloride of the present invention is in certain limit, and density of magnesium chloride is low, though product pattern is even, output is lower, and economic benefit is poor; If excessive concentration, causes reaching before finishing inductive phase the condition of homogeneous nucleation, cannot obtain the uniform magnesium basic carbonate intermediate of pattern, the product reunion degree making is comparatively serious, and equipment easily stops up.Reaction raw materials density of magnesium chloride of the present invention is 0.1-1mol/L, preferably 0.2-0.5mol/L.
Temperature of reaction of the present invention keeps 70-80 DEG C.If temperature of reaction is low, products therefrom is generally the mixture of magnesiumcarbonate double salt, its less stable; Temperature of reaction is too high, not easy to operate.
Supergravity reactor of the present invention is disclosed hypergravity swinging bed device, the rotating packed bed reactor (application reference number 91109255.2,91111028.3,01268009.5,200520100685.3,02114174.6 and 200510032296.6) that comprises the forms such as bed of packings, deflector type, helical channel, preferably hypergravity is rotary packed bed.
Hypergravity level of the present invention refers to the size of the centrifugal acceleration of hypergravity swinging bed device rotor rotation generation, conventionally represents with the multiple of gravity acceleration g, main relevant with the rotating speed of rotor and the internal-and external diameter of rotor.The horizontal g of hypergravity rcan represent with following formula:𝑔𝑟=ω2𝑟=(2πn60)2(𝑟12+𝑟22)2
In formula: n is the rotating speed of rotor per minute
R 1, r 2be respectively the inside and outside footpath of rotor
Hypergravity level of the present invention need to be controlled at certain limit according to preparation, to ensure that decomposition induction time completes the full and uniform mixing of magnesium chloride solution and mixed gas before finishing, thereby meets the needed homogeneous nucleation condition of magnesium basic carbonate of preparing.Hypergravity level is too low, and it is insufficient that reactant mixes, and after hypergravity level acquires a certain degree, the raising of hypergravity level does not almost affect reaction.General experimental result is: higher at the wide-ultra gravity horizontal limiting, will within the shorter time, reach required homogeneous nucleation condition, and the pattern of the intermediate product magnesium basic carbonate obtaining is even, thus the magnesian activity of product is higher.The preferred 150-960g of hypergravity level.
Calcining temperature of the present invention remains on 500-900 DEG C of scope, preferably 500-700 DEG C.If calcining temperature is too low, although the magnesian activity of product is high, it is incomplete that intermediate magnesium basic carbonate decomposes; Calcining temperature is too high, although the decomposition of intermediate magnesium basic carbonate is very thorough, product MgO activity is low.
The operations such as separation of the present invention, filtration, washing, dry and calcining are conventional treatment process.
It is raw material that the present invention can adopt bittern and industrial gaseous waste, and Product Activity is high, production cost is low, and contamination-free produces, and production technique is simple.Product is spheroidal particle, and the surface of spheroidal particle is made up of nanometer sheet decussate texture, and the quality index of this product reaches the activated magnesia quality standard that GB is announced simultaneously.Be mainly used in the fields such as electronics, electrical equipment, optics, instrument, national defence, aerospace.In addition, can also be as efficient Dissociative agent, absorption toxic chemical substance, is widely used in field of environment protection.
Magnesium oxide prepared by the present invention is activated magnesia, and product chemical index meets HG/T2573-94 standard premium grads index, as shown in table 1.
Table 1 activated magnesia chemical industry standard HG/T2573-94 standard
Activated magnesia iodine absorption value prepared by the present invention is greater than 120mgI 2/ g MgO, citric acid activity value (CAA) is less than 15s, and average apparent granularity is less than 3 μ m, and specific surface area is greater than 13m 2/ g (measuring method of activated magnesia iodine absorption value, citric acid activity value, average apparent granularity and specific surface area can reference ” magnesium compound is produced and application ” (Hu Qingfu compiles, Chemical Industry Press, 2004))
Beneficial effect of the present invention: the present invention is applied to magnesium chloride solution coupling high-gravity technology and absorbs NH 3and CO 2prepare intermediate magnesium basic carbonate, then calcining obtains activated magnesia, utilize the characteristic of supergravity reactor strengthening microcosmic mixing and mass transfer, and control corresponding processing condition, and not only can reach the be beyond one’s reach requirement of gas-liquid short mix of traditional reactor, make under the condition higher at reaction soln solute concentration, treatment capacity is large, can realize quick microcosmic evenly mixes, reach and prepare the needed homogeneous nucleation condition of intermediate magnesium basic carbonate, and technique easily controls, without ageing.Method simple process of the present invention, efficiency is high, and Product Activity is high, and the scale that is easy to is amplified.
Brief description of the drawings
Fig. 1 is the schematic diagram of the technical process of the embodiment of the present invention;
(1) head tank, (2) pump, (3) liquid meter, (4) supergravity reactor, (5,6,7) under meter, (8) gas mixing tank, (9) gas meter, (10) liquid distributor, (11) temperature regulating device;
Fig. 2 is the stereoscan photograph of the prepared activated magnesia of the present invention;
(a), (b) corresponding embodiment 1, (c), (d) corresponding embodiment 2, (e), (f) corresponding embodiment 3, (g), (h) corresponding embodiment 4.
Embodiment
Following examples just illustrate of the present invention, and the present invention is not limited to following examples.
Following examples all adopt rhythmic reaction operating method, that is: certain density magnesium chloride solution is heated to assigned temperature in head tank, squeeze into supergravity reactor through recycle pump, with carbonic acid gas, ammonia and nitrogen (or air, be equivalent to simulate industrial gaseous waste) gas mixture counter current contact, hybrid reaction, liquid circulation charging, the disposable charging of gas, reaction finishes rear filtration, wash away ammonium ion and chlorion with deionized water, being 100-110 DEG C in temperature is dried, obtain intermediates magnesium basic carbonate, subsequently magnesium basic carbonate is calcined and is obtained under assigned temperature activated magnesia, its flow process is shown in Fig. 1.
To in head tank (1), be heated to assigned temperature 50-80 DEG C by certain density magnesium chloride solution, be squeezed in supergravity reactor (4) N by pump (2) through liquid meter (3) 2(or air, its object is in order to simulate industrial gaseous waste), NH 3, CO 2after gas mixing tank (8) mixes, be delivered to supergravity reactor by gas meter (9) through under meter (5,6,7).Start after reactor, magnesium chloride solution is introduced rotor internal cavity by liquid inlet tube, be sprayed on the inner edge of rotor through liquid distributor (10), liquid enters the effect that is subject to filler in rotor after rotor, circumferential speed increases, under the effect of centrifugal force, flowed to outer rim by inner edge, after system stability, pass into gas, gas mixture through gas inlet tube by tangentially introducing, under the effect of pressure reduction, entering filler by rotor outer rim contacts with liquid countercurrent, reaction mixture body enters stirring tank through discharge gate, then squeezes into supergravity reactor through recycle pump and carries out NH 3and CO 2circulation absorption reaction, whole reactive system is by temperature regulating device (11) temperature control, after reaching terminal, reaction filters, be dry cake at 100-110 DEG C in temperature, obtain intermediates magnesium basic carbonate, subsequently magnesium basic carbonate lower calcining under 500-700 DEG C of condition is obtained to activated magnesia.
The preferred hypergravity of rotating bed super gravity reactor of the present invention is rotary packed bed, and the filler in packing layer includes, but are not limited to: silk screen, porous plate, waved plate, foam materials or the structured packing of metallic substance and non-metallic material.The hypergravity level of supergravity reactor is 150-960g, and the circulating reaction time is 25-35min.
Embodiment 1
Compound concentration is the magnesium chloride solution 3L of 0.2mol/L, and 70 DEG C of temperature of reaction regulate liquid flow rate 100L/h, gas flow 350L/h, NH 3and CO 2volume content be respectively 22% and 13%, normal atmosphere of working pressure, rotating speed 600rpm, rotor diameter 15cm, internal diameter 5cm (the horizontal 220g of hypergravity), reaction reaches after terminal, vacuum filtration, with deionized water washing leaching cake several, dry 10h at 100-110 DEG C, obtain intermediate magnesium basic carbonate, be 700 DEG C of calcining 2h magnesium basic carbonate in temperature subsequently, product is for the surperficial bar-shaped activated magnesia being made up of nanometer sheet (nanometer sheet is made up of Nano microsphere) decussate texture is (as Fig. 2 (a), (b) shown in), particle length is respectively 10-15 μ m, width is all 2.5 μ m, nanometer sheet thickness 25nm left and right, the iodine absorption value of product is 110mgI 2/ g MgO, citric acid activity value (CAA value) is 11s, specific surface area 49m 2/ g, the utilization ratio of magnesium ion is 95%.
Embodiment 2
Compound concentration is the magnesium chloride solution 3L of 0.3mol/L, and 75 DEG C of temperature of reaction regulate liquid flow rate 100L/h, gas flow 350L/h, NH 3and CO 2volume content be respectively 22% and 12%, normal atmosphere of working pressure, rotating speed 800rpm, rotor diameter 15cm, internal diameter 5cm (the horizontal 391g of hypergravity), reaction reaches after terminal, vacuum filtration, with deionized water washing leaching cake several, dry 10h at 100-110 DEG C, obtain intermediate magnesium basic carbonate, be 650 DEG C of calcining 2h magnesium basic carbonate in temperature subsequently, product is that the surperficial bar-shaped activated magnesia being made up of nanometer sheet decussate texture is (as Fig. 2 (c), (d) shown in), particle length is respectively 12-17 μ m, width is all 3 μ m, nanometer sheet thickness 20nm left and right, the iodine absorption value of product is 120mgI 2/ g MgO, citric acid activity value (CAA value) is 10s, specific surface area 56m 2/ g, the utilization ratio of magnesium ion is 97%.
Embodiment 3
Compound concentration is the magnesium chloride solution 3L of 0.4mol/L, and 80 DEG C of temperature of reaction regulate liquid flow rate 100L/h, gas flow 350L/h, NH 3and CO 2volume content be respectively 22% and 11%, normal atmosphere of working pressure, rotating speed 1000rpm, rotor diameter 15cm, internal diameter 5cm (the horizontal 612g of hypergravity), reaction reaches after terminal, vacuum filtration, with deionized water washing leaching cake several, dry 10h at 100-110 DEG C, obtain intermediate magnesium basic carbonate, be 500 DEG C of calcining 2h magnesium basic carbonate in temperature subsequently, product is that the surperficial spherical activated magnesia being made up of nanometer sheet decussate texture is (as Fig. 2 (e), (f) shown in), the mean diameter of particle is 3 μ m, nanometer sheet thickness 20nm left and right, the iodine absorption value of product is 170mgI 2/ g MgO, citric acid activity value (CAA value) is 7s, specific surface area 97m 2/ g, the utilization ratio of magnesium ion is 96%.
Embodiment 4
Compound concentration is the magnesium chloride solution 3L of 0.5mol/L, and 73 DEG C of temperature of reaction regulate liquid flow rate 100L/h, gas flow 350L/h, NH 3and CO 2volume content be respectively 22% and 10%, normal atmosphere of working pressure, rotating speed 1200rpm, rotor diameter 15cm, internal diameter 5cm (the horizontal 882g of hypergravity), reaction reaches after terminal, vacuum filtration, with deionized water washing leaching cake several, dry 10h at 100-110 DEG C, obtain intermediate magnesium basic carbonate, be 600 DEG C of calcining 2h magnesium basic carbonate in temperature subsequently, product is that the spherical activated magnesia that is made up of nanometer sheet decussate texture of surface is (as Fig. 2 (g), (h) shown in shown in), the mean diameter of particle is 2.5 μ m, nanometer sheet thickness 20nm left and right, the iodine absorption value of product is 150mgI 2/ g MgO, citric acid activity value (CAA value) is 8s, specific surface area 83m 2/ g, the utilization ratio of magnesium ion is 94%.