Surface pretreatment can change the surface properties of minerals,placing them in either a favorable or an unfavorable state for flotation.To solve the separation problem associated with magnesite and dolomite,surfac...Surface pretreatment can change the surface properties of minerals,placing them in either a favorable or an unfavorable state for flotation.To solve the separation problem associated with magnesite and dolomite,surface pretreatment experiments with citric acid,tartaric acid,and tannic acid(TA)on magnesite and dolomite as well as flotation experiments on pretreated samples were performed in this study.Experimental results demonstrated that when citric acid and tartaric acid are used for surface pretreatment,the separation effect of magnesite and dolomite is poor.However,when TA is used,the separation effect of magnesite and dolomite improves.SEM and BET analysis indicated that surface pretreatment with TA changes the surface morphology of the two minerals,resulting in additional concave pores on the dolomite surface,and a significant increase in pore size and specific surface area.The adsorption quantity test and contact angle measurement demonstrated that after surface pretreatment with TA,the magnesite adsorption capacity on sodium oleate(NaOL)slightly decreases and the dolomite adsorption capacity on NaOL considerably decreases.XPS detection concluded that the surface pretreatment of TA on the magnesite surface mainly relies on physical adsorption with weak adsorption ability and poor ability to act on Mg sites.The TA surface pretreatment action on the dolomite surface is mainly through chemical adsorption,and it is strongly and selectively adsorbed on the Ca site of dolomite through O.Actual ore rough selection experiments reveal that TA pretreatment successfully removes dolomite from magnesite,resulting in a high-quality magnesite concentrate characterized by a MgO grade of 45.49%and a CaO grade of 0.75%.展开更多
In this study,an efficient stabilizer material for cadmium(Cd^(2+))treatment was successfully prepared by simply co-milling olivine with magnesite.Several analyticalmethods including XRD,TEM,SEM and FTIR,combined with...In this study,an efficient stabilizer material for cadmium(Cd^(2+))treatment was successfully prepared by simply co-milling olivine with magnesite.Several analyticalmethods including XRD,TEM,SEM and FTIR,combined with theoretical calculations(DFT),were used to investigate mechanochemical interfacial reaction between twominerals,and the reaction mechanism of Cd removal,with ion exchange between Cd^(2+)and Mg^(2+)as the main pathway.A fixation capacity of Cd^(2+)as high as 270.61 mg/g,much higher than that of the pristine minerals and even the individual/physical mixture of milled olivine and magnesite,has been obtained at optimized conditions,with a neutral pH value of the solution after treatment to allow its direct discharge.The as-proposed Mg-based stabilizer with various advantages such as cost benefits,green feature etc.,will boosts the utilization efficiency of naturalminerals over the elaborately prepared adsorbents.展开更多
Traditional magnesia-based refractories face challenges such as high thermal conductivity and poor slag penetration resistance,which contradict the energy efficiency requirements of modern metallurgy.In this study,mic...Traditional magnesia-based refractories face challenges such as high thermal conductivity and poor slag penetration resistance,which contradict the energy efficiency requirements of modern metallurgy.In this study,microporous magnesia was prepared using low-grade magnesite via the one-step sintering method.The microstructure and properties of microporous magnesia prepared by high-silicon and high-calcium magnesites calcined at various temperatures were compared.The pore structure and phase evolution were analyzed,the effect of which on the properties of lightweight magnesia-based dry vibration mix was discussed.The results indicated that within high-silicon magnesite,SiO_(2) initially reacted with Mgo to form Mg_(2)Si0_(4),which gradually reacted with Cao impurities as the temperature increased transforming into a Mgo-Cao-SiO_(2) ternary liquid phase and uniformly permeated along the grain boundaries.Due to the bridging effect of strip-like Cao in high-calcium magnesite,the reorganization and sintering of Mgo grains at high temperatures were inhibited,resulting in the presence of a significant number of elongated pores within the magnesia after calcination at various temperatures,which was detrimental to the mechanical properties and slag resistance.The microporous Mg0 prepared by high-silicon magnesite at 1700°C exhibited the superior physical properties.The microporous Mgo aggregates had a stronger interlocking force with the matrix,resulting in a greater bonding strength.Moreover,the micropores not only effectively reduced the thermal conductivity but also facilitated the supersaturated precipitation of molten slag,hindering further penetration.Compared to the dry vibration mix prepared by fused Mgo,the lightweight magnesia-based dry vibration mix prepared with the high-silicon magnesite exhibited higher mechanical strength(~40%increase)and thermal insulation performance(0.870 W·(m·K)at 1000 C),and improved slag resistance.展开更多
Flotation separation of magnesite and its calcium-containing carbonate minerals is a difficult problem.Recently,new regulat-ors have been proposed for magnesite flotation decalcification,although traditional regulator...Flotation separation of magnesite and its calcium-containing carbonate minerals is a difficult problem.Recently,new regulat-ors have been proposed for magnesite flotation decalcification,although traditional regulators such as tannin,water glass,sodium carbon-ate,and sodium hexametaphosphate are more widely used in industry.However,they are rarely used as the main regulators in research because they perform poorly in magnesite and dolomite single-mineral flotation tests.Inspired by the limonite presedimentation method and the addition of a regulator to magnesite slurry mixing,we used a tannin pretreatment method for separating magnesite and dolomite.Microflotation experiments confirmed that the tannin pretreatment method selectively and largely reduces the flotation recovery rate of dolomite without affecting the flotation recovery rate of magnesite.Moreover,the contact angles of the tannin-pretreated magnesite and dolomite increased and decreased,respectively,in the presence of NaOl.Zeta potential and Fourier transform infrared analyses showed that the tannin pretreatment method efficiently hinders NaOl adsorption on the dolomite surface but does not affect NaOl adsorption on the magnesite surface.X-ray photoelectron spectroscopy and density functional theory calculations confirmed that tannin interacts more strongly with dolomite than with magnesite.展开更多
Given the depletion of high-quality magnesite deposits and the rising demand for high-end magnesium materials,the separation and utilization of high-calcium magnesite ores have become essential.However,the similar sur...Given the depletion of high-quality magnesite deposits and the rising demand for high-end magnesium materials,the separation and utilization of high-calcium magnesite ores have become essential.However,the similar surface properties and solubility of semi-soluble salt-type minerals,pose significant challenges for the utilization of dolomite-rich magnesite resources.In this study,1-hydroxypropane-1,1-di phosphonic acid(HPDP)was identified for the first time as a high-performance depressant for dolomite.Various tests,including contact angle measurements,ζ potential analysis,X-ray photoelectron spectroscopy,and atomic force microscopy,were conducted to elucidate the interfacial interaction mechanisms of HPDP on the surfaces of the two minerals at different scales.Additionally,molecular modeling calculations were used to detail the spatial matching relationship between HPDP and the crystal faces of the two minerals.It was emphasized that HPDP specifically adsorbed onto the dolomite surface by forming calcium phosphonate,ensuring that the dolomite surface remained hydrophilic and sank.Moreover,it was found that the adsorption strength of HPDP on the mineral surfaces depended on the activity of the metal sites and their spatial distribution.These findings provide a theoretical foundation for the molecular design of flotation reagents for high-calcium magnesite ores.展开更多
The process of aluminothermic reduction of a mixture of calcined dolomite and calcined magnesite had been developed. The mechanism of the process was studied by SEM and EDS. The reduction process was divided into thre...The process of aluminothermic reduction of a mixture of calcined dolomite and calcined magnesite had been developed. The mechanism of the process was studied by SEM and EDS. The reduction process was divided into three stages:0≤ηt/ηf≤0.43±0.06, 0.43±0.06≤ηt/ηf≤0.9±0.02 and 0.9±0.02≤ηt/ηf<1, whereηt andηf are the reduction ratio at time t and the final reduction ratio obtained in the experiment at temperature T, respectively. The first stage included the direct reaction between calcined dolomite or calcined magnesite and Al with 12CaO·7Al2O3 and MgO·Al2O3 as products. The reaction rate depended on the chemical reaction. The CA phase was mainly produced in the second stage and the overall reaction rate was determined by both the diffusion of Ca2+ with molten Al and the chemical reaction. The CA2 phase was mainly produced in the third stage and the reaction process was controlled by the diffusion of Ca2+.展开更多
The vacuum aluminothermic reduction of the mixture of calcined magnesite and calcined dolomite was studied. An isothermal reduction method satisfying the vacuum aluminothermic reduction was proposed. The experiments w...The vacuum aluminothermic reduction of the mixture of calcined magnesite and calcined dolomite was studied. An isothermal reduction method satisfying the vacuum aluminothermic reduction was proposed. The experiments were carried out at 4 Pa. The results indicate that the reduction rate is increased with increasing temperature, content of aluminum and pellet forming pressure. The XRD patterns of pellets at different reduction stages confirm that the reduction process can be roughly classified into three stages：the formation of MgAl2O4, and Ca12Al14O33 phases;the phase transformation from MgAl2O4 and C12A7 to CaAl2O4;the formation of CaAl4O7 phase. The experimental data were divided into three parts according to the kinetic models. The apparent activation energies of the three parts were determined to be 98.2, 133.0 and 223.3 kJ/mol, respectively.展开更多
The flotation separation of magnesite from calcium-containing minerals has always been a difficult subject in minerals processing.This work studied the inhibition effects of carboxymethyl cellulose(CMC),sodium lignosu...The flotation separation of magnesite from calcium-containing minerals has always been a difficult subject in minerals processing.This work studied the inhibition effects of carboxymethyl cellulose(CMC),sodium lignosulphonate,polyaspartic acid(PASP)and sodium silicate on flotation behaviors of magnesite,dolomite and calcite,providing guidance for the development of reagents in magnesite flotation.The micro-flotation results showed that among these four depressants,sodium silicate presented the strongest selectivity due to the highest recovery difference,and the flotation separation of magnesite from dolomite and calcite could be achieved by using sodium silicate as the depressant.Contact angle measurement indicated that the addition of sodium silicate caused the largest differences in surface wettability of the three minerals,which was in line with micro-flotation tests.Furthermore,zeta potential test,the Fourier transform infrared(FT-IR)spectroscopy and atomic force microscope(AFM)imaging were used to reveal the inhibition mechanism of sodium silicate.The results indicated that the dominated component SiO(OH)3of sodium silicate could adsorb on minerals surfaces,and the adsorption of sodium silicate hardly affected the adsorption of NaOL on magnesite surface,but caused the reduction of NaOL adsorption on dolomite and calcite surfaces,thereby increasing the flotation selectivity.展开更多
Carboxymethyl cellulose(CMC)was introduced as a depressant in reverse flotation separation of quartz from magnesite.The flotation behavior and surface properties of magnesite and quartz exposed to CMC were studied by ...Carboxymethyl cellulose(CMC)was introduced as a depressant in reverse flotation separation of quartz from magnesite.The flotation behavior and surface properties of magnesite and quartz exposed to CMC were studied by zeta potential tests,atomic force microscopy imaging and contact angle measurements.The addition of CMC as the depressant in reverse flotation using dodecylamine(DDA)as the collector exhibited a selectively depressive performance towards magnesite and achieved an improved recovery of magnesite.The study of surface properties demonstrated that CMC and DDA exhibited different adsorption strengths on the surface of magnesite and quartz.It was found that the adsorption of CMC on magnesite surface was stronger than that of DDA,which hindered the subsequent adsorption of DDA on magnesite surface.On the contrary,the quartz surface was strongly adsorbed by DDA instead of CMC,which proved that the addition of CMC did not influence the flotation of quartz.展开更多
We investigated whether the vertical roller mill can be efficiently used in the beneficiation of low-grade magnesite and whether it can improve upon the separation indices achieved by the ball mill.We conducted experi...We investigated whether the vertical roller mill can be efficiently used in the beneficiation of low-grade magnesite and whether it can improve upon the separation indices achieved by the ball mill.We conducted experiments involving the reverse flotation and positive flotation of low-grade magnesite to determine the optimum process parameters,and then performed closed-circuit beneficiation experiments using the vertical roller mill and ball mill.The results show that the optimum process parameters for the vertical roller mill are as follows:a grinding fineness of 81.6wt%of particles less than 0.074 mm,a dodecyl amine(DDA)dosage in magnesite reverse flotation of 100 g·t?1,and dosages of Na2CO3,(NaPO3)6,and NaOL in the positive flotation section of 1000,100,and 1000 g·t?1,respectively.Compared with the ball mill,the use of the vertical roller mill in the beneficiation of low-grade magnesite resulted in a 1.28%increase in the concentrate grade of MgO and a 5.88%increase in the recovery of MgO.The results of our causation mechanism analysis show that a higher specific surface area and greater surface roughness are the main reasons for the better flotation performance of particles ground by the vertical roller mill in the beneficiation of lowgrade magnesite.展开更多
Calcined magnesite is a binding additive and an MgO-bearing flux for pellets production. The effects of cal- cination temperature and time on the characteristics of calcined magnesite were investigated. Experimental r...Calcined magnesite is a binding additive and an MgO-bearing flux for pellets production. The effects of cal- cination temperature and time on the characteristics of calcined magnesite were investigated. Experimental results in dicated that the best calcination condition was 850℃ and 1h. Under this condition, the hydration activity of the eal cined magnesite was 80.56%, and the average diameter of crystal grain D, specific surface area S and the medium particle size D50 were 25.4 nm, 45.40 m2/g and 3.41μm, respectively. This kind of calcined magnesite was a good binding additive for pellets production. At the same proportion of calcined magnesite, the effects of activities of cal cined magnesite on metallurgical properties of green pellet and indurated pellet showed that calcined magnesite with high activity could improve the dropping strength and compressive strength of green pellet and enhance the burst temperature of green pellet; however, the effects of activity on compressive strength, low-temperature reduction degradation index, reduction swelling index and reduction index of indurated pellet were not obvious.展开更多
Fourteen soil properties in 17 sampling sites were analyzed to study the soil degradation in a magnesite mining area in Halcheng City, Northeast China. Such areas have hitherto received little attention. The current p...Fourteen soil properties in 17 sampling sites were analyzed to study the soil degradation in a magnesite mining area in Halcheng City, Northeast China. Such areas have hitherto received little attention. The current practices of magnesite mining in this area resulted in degradation of soil quality and specifically led to an increase in soil pH, the ratio of magnesium to calcium, bulk density, clay dispersibility, total magnesium and equivalent calcium carbonate and a decrease in surface soil porosity and available phosphorous. The soil quality in the areas affected by intensive mining activity was obviously worse than that of areas far away from the mine. Four factors were identified and ＂magnesium factor＂, ＂pH factor＂ and ＂fertility factor＂, involving 13 soil properties, explained 82~0 of the total variance in the entire data set. Discriminant analysis showed that the total magnesium, water-soluble calcium and available phosphorous were the most sensitive indicators for soil quality.展开更多
China has abundant reserves of magnesite, making it the world’s leading source of this strategic mineral.Sparry magnesite is the main type of magnesite deposit, and is easy to exploit.It occurs mainly as the sediment...China has abundant reserves of magnesite, making it the world’s leading source of this strategic mineral.Sparry magnesite is the main type of magnesite deposit, and is easy to exploit.It occurs mainly as the sedimentary-metamorphic type.Production is centred on eastern Liaoning Province, where a world-class large to super large magnesite ore processing and production facility has been developed.Hydrothermal metasomatic deposits, associated with ultramafic complexes and eluvial deposits produced by weathering, are two other important types found in China.The Western section of the Bangonghu-Nujiang metallogenic belt is an important target region for prospecting lake-sedimentary magnesite deposits.Based on a systematic analysis of material from 62 magnesite production areas, this study investigated the metallogeny of magnesite and delineated 13 magnesite metallogenic belts.Maps were produced showing metallogenic regularities in magnesite deposits, the metallogenic system of the magnesite deposits, and the distribution of the metallogenic belts of Chinese magnesite deposits.It provides a theoretical basis for forecasting the location of potential magnesite resources in China.Finally, it explores some key scientific issues, including the formation processes of ultra magnesite ore-concentrated areas, and their sources of magnesium.展开更多
In-situ powder X-ray diffraction(XRD) and Fourier transform infrared(FTIR) spectra were measured on the natural crystals of calcite(Ca0.996 Mg0.004 CO3), dolomite(Ca0.497 Mg0.454 Fe0.046 Mn0.003 CO3) and magnesite(Mg0...In-situ powder X-ray diffraction(XRD) and Fourier transform infrared(FTIR) spectra were measured on the natural crystals of calcite(Ca0.996 Mg0.004 CO3), dolomite(Ca0.497 Mg0.454 Fe0.046 Mn0.003 CO3) and magnesite(Mg0.988 Ca0.010 Fe0.002 CO3), with a temperature up to 796 K. The thermal expansion coefficients were evaluated for these carbonate minerals, resulting in the values of 2.7×10^-5, 3.3×10^-5 and 3.5×10^-5 K^-1 for calcite, dolomite and magnesite, respectively. The magnitude of these coefficients is in the same order as those for the isothermal and elastic moduli of these carbonates(e.g., calcite<dolomite<magnesite). The IR-active internal modes of the CO3 group systematically shift to lower frequencies at elevated temperature, and the isobaric(γi P) and isothermal(γi T) Grüneisen parameters for the internal modes are generally smaller than 0.5. The corresponding anharmonic parameters(ai) are typically within the range of-1.5–+1×10^-5 K^-1, which are significantly smaller in magnitude than those for the external modes. We also calculate the thermodynamic properties(internal energy, heat capacities and entropy) at high temperatures for these carbonates, and the anharmonic contribution to thermodynamics shows an order of calcite>dolomite>magnesite. The Debye model(harmonic approximation) would be valid for magnesite to simulating the thermodynamic properties and isotope fractionation β-factor at high P-T condition.展开更多
It is hard to manufacture high purity,dense sintered-magnesia from natural magnesite in the prevailing process of calcining and sintering,for two reasons:a)impurity,and b)low sintering activity of coarse-grained magne...It is hard to manufacture high purity,dense sintered-magnesia from natural magnesite in the prevailing process of calcining and sintering,for two reasons:a)impurity,and b)low sintering activity of coarse-grained magnesite.In this paper,95%MgO magnesite was used as the starting material and finally magnesia of high density(3.47 g/cm^3)and high purity(98%MgO)was obtained after the flotation purification and a three-step sintering process.An industrial scale of the beneficiation system of natural magnesite was introduced for magnesite purification.In lab experimental,the three-step sintering process was implemented by calcining,hydrating,re-calcining and sintering,which has proven the possibility of densified magnesia from natural magnesite.展开更多
This paper summarizes recent data about magnesite and talc genesis in Carboniferous host rocks of Western Carpathians (Slovakia) , which occur in two distinct belts in tectonic superunit Veporicum and its contact zone...This paper summarizes recent data about magnesite and talc genesis in Carboniferous host rocks of Western Carpathians (Slovakia) , which occur in two distinct belts in tectonic superunit Veporicum and its contact zone with Gemericum. The northern Sinec magnesite and talc belt (with main deposits Kokava, Sinec, Samo, Hnust'a-Mutnik) contains economic accummulation of magnesite and talc, while in the southern Ochtina belt ( main deposits in Dubrava massif-Dubrava, Mikova, Jedl'ovec; Lubenik, Ochtina, Kosice-Bankov, Banisko, Medvedia) the magnesite is dominating.The magnesite genesis by successive replacement of Carboniferous calcite to dolomite and magnesite during metamorphic process Ml (northern belt 280-400℃; , southern belt 370-420℃: ; Radvanec & Prochaska, 2001; Kodera & Radvanec, 2002) , being supplied by Mg from Permoscythian evaporitic bittern brines, relates to Variscan post-collisional (post-VD) evolution. The extensional tectonics and the high heat flow facilitated the generation of a hydrothermal system.The time-separated later metamorphic and sourcely different fluid flow event (M2; 1. c. ) produced talc. Tectonic, microtectonic, metamorphic and geochronological data relate the talc origin with the Alpine Upper Cretaceous (88-84 Ma; Maluski in Kovacik et al. , 1996) tectonothermal event AD2. This event, being the consequence of Alpine collisional ( AD1 ) crustal thickening and metamorphic core complex origin, meant regional extension and pervasive fluid flow of open system in crustal discontinuities. This process was prominent in the northern belt ( Sinec shear zone) located more closely to Veporic thermal dome, while towards its peripheral parts (southern Ochtina belt) the M2 metamorphic process and steatitization gradually weakened.Studies from Sinec shear zone (being the prominent AD2 -AD3 structure of northern Sinec belt) , where the dolomite/magnesite lenses (replacement in M1) and their accompanying lithology were in AD1 sandwitched between more competent basement blocks, proved in AD2 the pervasite steatitization, the talc and dolomite 2 origin in extensional microstructures ( metamorphic process M2; 490 -540℃, 240-330 MPa, 1. c. ).The economic accummulations of talc in Sinec belt are the products of antithetic shearing during the AD3 phase, being the gradual continuation of AD2 ( change of kinematics from unroofing to regional transpressional shearing). Contrary to the northern Sinec belt having located the AD3 deformation into narrow shear zone with soft lithology surrounded by hard lithology, in southern Ochtina belt the deformation AD3 was accommodated by wide soft rock column with rigid carbonate blocks floating inside. The lower P-T ( M2)conditions and deformational gradient in Ochtina belt during AD2 and AD3 phases caused why no economic talc accummulations developed there.The results of presented study can be used as general criteria for magnesite and talc prospection in Alpine type terranes.展开更多
Laboratory studies were made on the floatabil-ity of magnesite and dolomite with sodium oieate as the collector. The adsorption mechanism of sodium oieate on the surface of minerals was examined. The results show that...Laboratory studies were made on the floatabil-ity of magnesite and dolomite with sodium oieate as the collector. The adsorption mechanism of sodium oieate on the surface of minerals was examined. The results show that the ion-molecule association polymer of oieate in the pulp is a main active component of the collector . In both neutral and basic media , the adsorption type of sodium oieate on the surface of carbonate minerals is mainly chemisorp-tion, forming Mg(Ol)2 and Mg(Ol)2·HOl.展开更多
Sintered magnesia clinker （also called sintered MgO ） was prepared with Mg（ OH）2 （prepared by light calcining hydration of magnesite ） and magnesite as starting materials, respectively, by the technical process ...Sintered magnesia clinker （also called sintered MgO ） was prepared with Mg（ OH）2 （prepared by light calcining hydration of magnesite ） and magnesite as starting materials, respectively, by the technical process ： light calcining （850 ℃ 1 h） → grinding → molding → firing （1 600 ℃ 3 h ）. The morphology and structure of light calcined MgO powders prepared with magnesite or Mg（ OH）2 were analyzed by XRD, SEM and FT-IR. The sinterability and microstructure of sintered magnesia prepared with magnesite or Mg（ OH） 2 were researched. The results showed that： （1） light calcined MgO powders prepared with magnesite or Mg （OH）2 were both face-centered cubic structure. The light calcined MgO prepared with magnesite had the residual of functional group CO3^2-, and that prepared with Mg （OH） 2 didn＇ t have CO3^2- , and was easy to break, which reduced the grinding time. （2） Because of the high activity of the light calcined MgO prepared with Mg（ OH） 2 and the catalysis of the water residual in the decomposing process of Mg（ OH） 2, the apparent porosity of sintered magnesia decreased to 0. 6% from 2.0% of before hydration, closed porosity decreased to 2. 8% from 6. 1%, and bulk density increased to 3. 46 g · cm^ -3 from 3.29 g · cm^ -1.展开更多
In order to widen the application of microcrystalline magnesite, the microcrystalline magnesite in Sichuan and Tibet area was used as the raw material to prepare light-burned MgO at 700,800,900, 1 000, 1 100 and I 200...In order to widen the application of microcrystalline magnesite, the microcrystalline magnesite in Sichuan and Tibet area was used as the raw material to prepare light-burned MgO at 700,800,900, 1 000, 1 100 and I 200 ~C for 3 h, respectively. Then the physical and chemical properties of the light-burned MgO were detec- ted, and its application prospect was analyzed. The re- sults show that： （1） microcrystalline magnesite com- pletely decomposes forming light-burned MgO calcined at the temperature range of 700 - 1 200 ~C ; the MgO con- tent of the light-burned MgO is higher than 96. 51% ; the chemical activity is 88 - 130 s and the grain size is 40 - 200 nm ; it has the advantages of high purity, high activity and fine grain; （2） the light-burned MgO pre- pared with microcrystalline magnesite can be widely used in many industries; it can be used in refractories indus- try to prepare high-purity sintered magnesia and large crystal fused magnesia, or as an additive for refractory products, etc. ; it can also be used in magnesium chemi- cal industry to prepare electrical grade magnesia, sili- con-steel magnesia, environmental friendly flame retard- ant magnesium hydroxide, magnesium sulfate fertilizer, pharmaceutical grade magnesia, food grade magnesia, etc.展开更多
Cr2O3 has eminent slag corrosion resistance. So, the magnesite -chrome brick is thought as an important refractory material used in RH refining furnace in the process of steel-making around the world. After chromebear...Cr2O3 has eminent slag corrosion resistance. So, the magnesite -chrome brick is thought as an important refractory material used in RH refining furnace in the process of steel-making around the world. After chromebearing sols being prepared by sol-gel method, single sol （ Cr（ OH）3） and mixed sol （ Mg（ OH）2 - Cr（ OH）3） were impregnated into magnesite - chrome bricks by vacuum impregnation. The corrosion resistance of the impregnated bricks to silicon steel slag was studied by porosimetric analysis and fractal dimension calculation. The results showed that the corrosion resistance of impregnated magnesite -chrome brick was better than that of the unimpregnated brick and the brick impregnated by MgSO4 solution, and the one which has surface-treated by Mg（ OH）2 -Cr（OH）3 sol was the best, mainly because of lower apparent porosity, smaller pores diameter and their smoother inner sarface.展开更多
基金Project(BGRIMM-KJSKL-2024-07) supported by the Open Foundation of State Key Laboratory of Mineral Processing,ChinaProjects(52374259,52174239) supported by the National Natural Science Foundation of China。
文摘Surface pretreatment can change the surface properties of minerals,placing them in either a favorable or an unfavorable state for flotation.To solve the separation problem associated with magnesite and dolomite,surface pretreatment experiments with citric acid,tartaric acid,and tannic acid(TA)on magnesite and dolomite as well as flotation experiments on pretreated samples were performed in this study.Experimental results demonstrated that when citric acid and tartaric acid are used for surface pretreatment,the separation effect of magnesite and dolomite is poor.However,when TA is used,the separation effect of magnesite and dolomite improves.SEM and BET analysis indicated that surface pretreatment with TA changes the surface morphology of the two minerals,resulting in additional concave pores on the dolomite surface,and a significant increase in pore size and specific surface area.The adsorption quantity test and contact angle measurement demonstrated that after surface pretreatment with TA,the magnesite adsorption capacity on sodium oleate(NaOL)slightly decreases and the dolomite adsorption capacity on NaOL considerably decreases.XPS detection concluded that the surface pretreatment of TA on the magnesite surface mainly relies on physical adsorption with weak adsorption ability and poor ability to act on Mg sites.The TA surface pretreatment action on the dolomite surface is mainly through chemical adsorption,and it is strongly and selectively adsorbed on the Ca site of dolomite through O.Actual ore rough selection experiments reveal that TA pretreatment successfully removes dolomite from magnesite,resulting in a high-quality magnesite concentrate characterized by a MgO grade of 45.49%and a CaO grade of 0.75%.
基金supported by the Key 491 R&D Programof Hubei Province(No.2022BCA083).
文摘In this study,an efficient stabilizer material for cadmium(Cd^(2+))treatment was successfully prepared by simply co-milling olivine with magnesite.Several analyticalmethods including XRD,TEM,SEM and FTIR,combined with theoretical calculations(DFT),were used to investigate mechanochemical interfacial reaction between twominerals,and the reaction mechanism of Cd removal,with ion exchange between Cd^(2+)and Mg^(2+)as the main pathway.A fixation capacity of Cd^(2+)as high as 270.61 mg/g,much higher than that of the pristine minerals and even the individual/physical mixture of milled olivine and magnesite,has been obtained at optimized conditions,with a neutral pH value of the solution after treatment to allow its direct discharge.The as-proposed Mg-based stabilizer with various advantages such as cost benefits,green feature etc.,will boosts the utilization efficiency of naturalminerals over the elaborately prepared adsorbents.
基金National Natural Science Foundation of China(52302027,52272022 and 52472032).
文摘Traditional magnesia-based refractories face challenges such as high thermal conductivity and poor slag penetration resistance,which contradict the energy efficiency requirements of modern metallurgy.In this study,microporous magnesia was prepared using low-grade magnesite via the one-step sintering method.The microstructure and properties of microporous magnesia prepared by high-silicon and high-calcium magnesites calcined at various temperatures were compared.The pore structure and phase evolution were analyzed,the effect of which on the properties of lightweight magnesia-based dry vibration mix was discussed.The results indicated that within high-silicon magnesite,SiO_(2) initially reacted with Mgo to form Mg_(2)Si0_(4),which gradually reacted with Cao impurities as the temperature increased transforming into a Mgo-Cao-SiO_(2) ternary liquid phase and uniformly permeated along the grain boundaries.Due to the bridging effect of strip-like Cao in high-calcium magnesite,the reorganization and sintering of Mgo grains at high temperatures were inhibited,resulting in the presence of a significant number of elongated pores within the magnesia after calcination at various temperatures,which was detrimental to the mechanical properties and slag resistance.The microporous Mg0 prepared by high-silicon magnesite at 1700°C exhibited the superior physical properties.The microporous Mgo aggregates had a stronger interlocking force with the matrix,resulting in a greater bonding strength.Moreover,the micropores not only effectively reduced the thermal conductivity but also facilitated the supersaturated precipitation of molten slag,hindering further penetration.Compared to the dry vibration mix prepared by fused Mgo,the lightweight magnesia-based dry vibration mix prepared with the high-silicon magnesite exhibited higher mechanical strength(~40%increase)and thermal insulation performance(0.870 W·(m·K)at 1000 C),and improved slag resistance.
基金supported by the National Natural Science Foundation of China (Nos.51974064,52174239,and 52374259)the Open Project of the Key Laboratory of Solid Waste Treatment and Resource Utiliza-tion of the Ministry of Education,China (No.23kfgk02).
文摘Flotation separation of magnesite and its calcium-containing carbonate minerals is a difficult problem.Recently,new regulat-ors have been proposed for magnesite flotation decalcification,although traditional regulators such as tannin,water glass,sodium carbon-ate,and sodium hexametaphosphate are more widely used in industry.However,they are rarely used as the main regulators in research because they perform poorly in magnesite and dolomite single-mineral flotation tests.Inspired by the limonite presedimentation method and the addition of a regulator to magnesite slurry mixing,we used a tannin pretreatment method for separating magnesite and dolomite.Microflotation experiments confirmed that the tannin pretreatment method selectively and largely reduces the flotation recovery rate of dolomite without affecting the flotation recovery rate of magnesite.Moreover,the contact angles of the tannin-pretreated magnesite and dolomite increased and decreased,respectively,in the presence of NaOl.Zeta potential and Fourier transform infrared analyses showed that the tannin pretreatment method efficiently hinders NaOl adsorption on the dolomite surface but does not affect NaOl adsorption on the magnesite surface.X-ray photoelectron spectroscopy and density functional theory calculations confirmed that tannin interacts more strongly with dolomite than with magnesite.
基金supported by the Fundamental Research Funds for the Central Universities(No.N2201005).
文摘Given the depletion of high-quality magnesite deposits and the rising demand for high-end magnesium materials,the separation and utilization of high-calcium magnesite ores have become essential.However,the similar surface properties and solubility of semi-soluble salt-type minerals,pose significant challenges for the utilization of dolomite-rich magnesite resources.In this study,1-hydroxypropane-1,1-di phosphonic acid(HPDP)was identified for the first time as a high-performance depressant for dolomite.Various tests,including contact angle measurements,ζ potential analysis,X-ray photoelectron spectroscopy,and atomic force microscopy,were conducted to elucidate the interfacial interaction mechanisms of HPDP on the surfaces of the two minerals at different scales.Additionally,molecular modeling calculations were used to detail the spatial matching relationship between HPDP and the crystal faces of the two minerals.It was emphasized that HPDP specifically adsorbed onto the dolomite surface by forming calcium phosphonate,ensuring that the dolomite surface remained hydrophilic and sank.Moreover,it was found that the adsorption strength of HPDP on the mineral surfaces depended on the activity of the metal sites and their spatial distribution.These findings provide a theoretical foundation for the molecular design of flotation reagents for high-calcium magnesite ores.
基金Project(MYF2011-34)supported by High-tech R&D Projects of Liaoning Province Magnesia Materials Industry,ChinaProject(2011221002)supported by Industrial Research Projects of Liaoning Province,ChinaProject(N100302009)supported by the Fundamental Research Funds for the Central Universities,China
文摘The process of aluminothermic reduction of a mixture of calcined dolomite and calcined magnesite had been developed. The mechanism of the process was studied by SEM and EDS. The reduction process was divided into three stages:0≤ηt/ηf≤0.43±0.06, 0.43±0.06≤ηt/ηf≤0.9±0.02 and 0.9±0.02≤ηt/ηf<1, whereηt andηf are the reduction ratio at time t and the final reduction ratio obtained in the experiment at temperature T, respectively. The first stage included the direct reaction between calcined dolomite or calcined magnesite and Al with 12CaO·7Al2O3 and MgO·Al2O3 as products. The reaction rate depended on the chemical reaction. The CA phase was mainly produced in the second stage and the overall reaction rate was determined by both the diffusion of Ca2+ with molten Al and the chemical reaction. The CA2 phase was mainly produced in the third stage and the reaction process was controlled by the diffusion of Ca2+.
基金Project(MYF2011-34)supported by High-tech R&D Plan of Liaoning Province,ChinaProject(2011221002)supported by Industrial Research Projects of Liaoning Province,ChinaProject(N100302009)supported by the Fundamental Research Funds for the Central Universities,China
文摘The vacuum aluminothermic reduction of the mixture of calcined magnesite and calcined dolomite was studied. An isothermal reduction method satisfying the vacuum aluminothermic reduction was proposed. The experiments were carried out at 4 Pa. The results indicate that the reduction rate is increased with increasing temperature, content of aluminum and pellet forming pressure. The XRD patterns of pellets at different reduction stages confirm that the reduction process can be roughly classified into three stages：the formation of MgAl2O4, and Ca12Al14O33 phases;the phase transformation from MgAl2O4 and C12A7 to CaAl2O4;the formation of CaAl4O7 phase. The experimental data were divided into three parts according to the kinetic models. The apparent activation energies of the three parts were determined to be 98.2, 133.0 and 223.3 kJ/mol, respectively.
基金supported by the Youth Science Foundation of China(No.52004333)the Key Laboratory of Hunan Province for Clean and Efficiency Utilization of Strategic Calcium-containing Mineral Resources(No.2018TP1002).
文摘The flotation separation of magnesite from calcium-containing minerals has always been a difficult subject in minerals processing.This work studied the inhibition effects of carboxymethyl cellulose(CMC),sodium lignosulphonate,polyaspartic acid(PASP)and sodium silicate on flotation behaviors of magnesite,dolomite and calcite,providing guidance for the development of reagents in magnesite flotation.The micro-flotation results showed that among these four depressants,sodium silicate presented the strongest selectivity due to the highest recovery difference,and the flotation separation of magnesite from dolomite and calcite could be achieved by using sodium silicate as the depressant.Contact angle measurement indicated that the addition of sodium silicate caused the largest differences in surface wettability of the three minerals,which was in line with micro-flotation tests.Furthermore,zeta potential test,the Fourier transform infrared(FT-IR)spectroscopy and atomic force microscope(AFM)imaging were used to reveal the inhibition mechanism of sodium silicate.The results indicated that the dominated component SiO(OH)3of sodium silicate could adsorb on minerals surfaces,and the adsorption of sodium silicate hardly affected the adsorption of NaOL on magnesite surface,but caused the reduction of NaOL adsorption on dolomite and calcite surfaces,thereby increasing the flotation selectivity.
基金the financial support from the National Natural Science Foundation of China(No.51774041)。
文摘Carboxymethyl cellulose(CMC)was introduced as a depressant in reverse flotation separation of quartz from magnesite.The flotation behavior and surface properties of magnesite and quartz exposed to CMC were studied by zeta potential tests,atomic force microscopy imaging and contact angle measurements.The addition of CMC as the depressant in reverse flotation using dodecylamine(DDA)as the collector exhibited a selectively depressive performance towards magnesite and achieved an improved recovery of magnesite.The study of surface properties demonstrated that CMC and DDA exhibited different adsorption strengths on the surface of magnesite and quartz.It was found that the adsorption of CMC on magnesite surface was stronger than that of DDA,which hindered the subsequent adsorption of DDA on magnesite surface.On the contrary,the quartz surface was strongly adsorbed by DDA instead of CMC,which proved that the addition of CMC did not influence the flotation of quartz.
基金the National Natural Science Foundation of China(Nos.51874072 and 51804200)the State Key Laboratory of Mineral Processing(No.BGRIMM-KJSKL-2017-02).
文摘We investigated whether the vertical roller mill can be efficiently used in the beneficiation of low-grade magnesite and whether it can improve upon the separation indices achieved by the ball mill.We conducted experiments involving the reverse flotation and positive flotation of low-grade magnesite to determine the optimum process parameters,and then performed closed-circuit beneficiation experiments using the vertical roller mill and ball mill.The results show that the optimum process parameters for the vertical roller mill are as follows:a grinding fineness of 81.6wt%of particles less than 0.074 mm,a dodecyl amine(DDA)dosage in magnesite reverse flotation of 100 g·t?1,and dosages of Na2CO3,(NaPO3)6,and NaOL in the positive flotation section of 1000,100,and 1000 g·t?1,respectively.Compared with the ball mill,the use of the vertical roller mill in the beneficiation of low-grade magnesite resulted in a 1.28%increase in the concentrate grade of MgO and a 5.88%increase in the recovery of MgO.The results of our causation mechanism analysis show that a higher specific surface area and greater surface roughness are the main reasons for the better flotation performance of particles ground by the vertical roller mill in the beneficiation of lowgrade magnesite.
基金Item Sponsored by National Natural Science Foundation of China(51074206,51074040)
文摘Calcined magnesite is a binding additive and an MgO-bearing flux for pellets production. The effects of cal- cination temperature and time on the characteristics of calcined magnesite were investigated. Experimental results in dicated that the best calcination condition was 850℃ and 1h. Under this condition, the hydration activity of the eal cined magnesite was 80.56%, and the average diameter of crystal grain D, specific surface area S and the medium particle size D50 were 25.4 nm, 45.40 m2/g and 3.41μm, respectively. This kind of calcined magnesite was a good binding additive for pellets production. At the same proportion of calcined magnesite, the effects of activities of cal cined magnesite on metallurgical properties of green pellet and indurated pellet showed that calcined magnesite with high activity could improve the dropping strength and compressive strength of green pellet and enhance the burst temperature of green pellet; however, the effects of activity on compressive strength, low-temperature reduction degradation index, reduction swelling index and reduction index of indurated pellet were not obvious.
基金Supported by the Knowledge Innovative Program of the Chinese Academy of Sciences (No. KZCX2-YW-446)the National NaturalScience Foundation of China (No. 40930739)+1 种基金the Key Program of Action Plan for Revitalizing Northeast China with Science andTechnology of the Chinese Academy of Sciences (No. DB2X-2-027)the National Environmental Protection Commonwealth Projectof China (No. 200809047)
文摘Fourteen soil properties in 17 sampling sites were analyzed to study the soil degradation in a magnesite mining area in Halcheng City, Northeast China. Such areas have hitherto received little attention. The current practices of magnesite mining in this area resulted in degradation of soil quality and specifically led to an increase in soil pH, the ratio of magnesium to calcium, bulk density, clay dispersibility, total magnesium and equivalent calcium carbonate and a decrease in surface soil porosity and available phosphorous. The soil quality in the areas affected by intensive mining activity was obviously worse than that of areas far away from the mine. Four factors were identified and ＂magnesium factor＂, ＂pH factor＂ and ＂fertility factor＂, involving 13 soil properties, explained 82~0 of the total variance in the entire data set. Discriminant analysis showed that the total magnesium, water-soluble calcium and available phosphorous were the most sensitive indicators for soil quality.
基金supported by the China Geological Survey Program (Grant No.1212010633903, 1212011220369)the National Natural Science Foundation of China (Grant No.41372092)the Chinese National Non-profit Institute Research Grant of CAGS-IMR (K1303)
文摘China has abundant reserves of magnesite, making it the world’s leading source of this strategic mineral.Sparry magnesite is the main type of magnesite deposit, and is easy to exploit.It occurs mainly as the sedimentary-metamorphic type.Production is centred on eastern Liaoning Province, where a world-class large to super large magnesite ore processing and production facility has been developed.Hydrothermal metasomatic deposits, associated with ultramafic complexes and eluvial deposits produced by weathering, are two other important types found in China.The Western section of the Bangonghu-Nujiang metallogenic belt is an important target region for prospecting lake-sedimentary magnesite deposits.Based on a systematic analysis of material from 62 magnesite production areas, this study investigated the metallogeny of magnesite and delineated 13 magnesite metallogenic belts.Maps were produced showing metallogenic regularities in magnesite deposits, the metallogenic system of the magnesite deposits, and the distribution of the metallogenic belts of Chinese magnesite deposits.It provides a theoretical basis for forecasting the location of potential magnesite resources in China.Finally, it explores some key scientific issues, including the formation processes of ultra magnesite ore-concentrated areas, and their sources of magnesium.
基金supported by the National Key Research and Development Program of China(No.2016YFC0600204)the National Natural Science Foundation of China(Nos.41590621,41672041)
文摘In-situ powder X-ray diffraction(XRD) and Fourier transform infrared(FTIR) spectra were measured on the natural crystals of calcite(Ca0.996 Mg0.004 CO3), dolomite(Ca0.497 Mg0.454 Fe0.046 Mn0.003 CO3) and magnesite(Mg0.988 Ca0.010 Fe0.002 CO3), with a temperature up to 796 K. The thermal expansion coefficients were evaluated for these carbonate minerals, resulting in the values of 2.7×10^-5, 3.3×10^-5 and 3.5×10^-5 K^-1 for calcite, dolomite and magnesite, respectively. The magnitude of these coefficients is in the same order as those for the isothermal and elastic moduli of these carbonates(e.g., calcite<dolomite<magnesite). The IR-active internal modes of the CO3 group systematically shift to lower frequencies at elevated temperature, and the isobaric(γi P) and isothermal(γi T) Grüneisen parameters for the internal modes are generally smaller than 0.5. The corresponding anharmonic parameters(ai) are typically within the range of-1.5–+1×10^-5 K^-1, which are significantly smaller in magnitude than those for the external modes. We also calculate the thermodynamic properties(internal energy, heat capacities and entropy) at high temperatures for these carbonates, and the anharmonic contribution to thermodynamics shows an order of calcite>dolomite>magnesite. The Debye model(harmonic approximation) would be valid for magnesite to simulating the thermodynamic properties and isotope fractionation β-factor at high P-T condition.
文摘It is hard to manufacture high purity,dense sintered-magnesia from natural magnesite in the prevailing process of calcining and sintering,for two reasons:a)impurity,and b)low sintering activity of coarse-grained magnesite.In this paper,95%MgO magnesite was used as the starting material and finally magnesia of high density(3.47 g/cm^3)and high purity(98%MgO)was obtained after the flotation purification and a three-step sintering process.An industrial scale of the beneficiation system of natural magnesite was introduced for magnesite purification.In lab experimental,the three-step sintering process was implemented by calcining,hydrating,re-calcining and sintering,which has proven the possibility of densified magnesia from natural magnesite.
文摘This paper summarizes recent data about magnesite and talc genesis in Carboniferous host rocks of Western Carpathians (Slovakia) , which occur in two distinct belts in tectonic superunit Veporicum and its contact zone with Gemericum. The northern Sinec magnesite and talc belt (with main deposits Kokava, Sinec, Samo, Hnust'a-Mutnik) contains economic accummulation of magnesite and talc, while in the southern Ochtina belt ( main deposits in Dubrava massif-Dubrava, Mikova, Jedl'ovec; Lubenik, Ochtina, Kosice-Bankov, Banisko, Medvedia) the magnesite is dominating.The magnesite genesis by successive replacement of Carboniferous calcite to dolomite and magnesite during metamorphic process Ml (northern belt 280-400℃; , southern belt 370-420℃: ; Radvanec & Prochaska, 2001; Kodera & Radvanec, 2002) , being supplied by Mg from Permoscythian evaporitic bittern brines, relates to Variscan post-collisional (post-VD) evolution. The extensional tectonics and the high heat flow facilitated the generation of a hydrothermal system.The time-separated later metamorphic and sourcely different fluid flow event (M2; 1. c. ) produced talc. Tectonic, microtectonic, metamorphic and geochronological data relate the talc origin with the Alpine Upper Cretaceous (88-84 Ma; Maluski in Kovacik et al. , 1996) tectonothermal event AD2. This event, being the consequence of Alpine collisional ( AD1 ) crustal thickening and metamorphic core complex origin, meant regional extension and pervasive fluid flow of open system in crustal discontinuities. This process was prominent in the northern belt ( Sinec shear zone) located more closely to Veporic thermal dome, while towards its peripheral parts (southern Ochtina belt) the M2 metamorphic process and steatitization gradually weakened.Studies from Sinec shear zone (being the prominent AD2 -AD3 structure of northern Sinec belt) , where the dolomite/magnesite lenses (replacement in M1) and their accompanying lithology were in AD1 sandwitched between more competent basement blocks, proved in AD2 the pervasite steatitization, the talc and dolomite 2 origin in extensional microstructures ( metamorphic process M2; 490 -540℃, 240-330 MPa, 1. c. ).The economic accummulations of talc in Sinec belt are the products of antithetic shearing during the AD3 phase, being the gradual continuation of AD2 ( change of kinematics from unroofing to regional transpressional shearing). Contrary to the northern Sinec belt having located the AD3 deformation into narrow shear zone with soft lithology surrounded by hard lithology, in southern Ochtina belt the deformation AD3 was accommodated by wide soft rock column with rigid carbonate blocks floating inside. The lower P-T ( M2)conditions and deformational gradient in Ochtina belt during AD2 and AD3 phases caused why no economic talc accummulations developed there.The results of presented study can be used as general criteria for magnesite and talc prospection in Alpine type terranes.
文摘Laboratory studies were made on the floatabil-ity of magnesite and dolomite with sodium oieate as the collector. The adsorption mechanism of sodium oieate on the surface of minerals was examined. The results show that the ion-molecule association polymer of oieate in the pulp is a main active component of the collector . In both neutral and basic media , the adsorption type of sodium oieate on the surface of carbonate minerals is mainly chemisorp-tion, forming Mg(Ol)2 and Mg(Ol)2·HOl.
文摘Sintered magnesia clinker （also called sintered MgO ） was prepared with Mg（ OH）2 （prepared by light calcining hydration of magnesite ） and magnesite as starting materials, respectively, by the technical process ： light calcining （850 ℃ 1 h） → grinding → molding → firing （1 600 ℃ 3 h ）. The morphology and structure of light calcined MgO powders prepared with magnesite or Mg（ OH）2 were analyzed by XRD, SEM and FT-IR. The sinterability and microstructure of sintered magnesia prepared with magnesite or Mg（ OH） 2 were researched. The results showed that： （1） light calcined MgO powders prepared with magnesite or Mg （OH）2 were both face-centered cubic structure. The light calcined MgO prepared with magnesite had the residual of functional group CO3^2-, and that prepared with Mg （OH） 2 didn＇ t have CO3^2- , and was easy to break, which reduced the grinding time. （2） Because of the high activity of the light calcined MgO prepared with Mg（ OH） 2 and the catalysis of the water residual in the decomposing process of Mg（ OH） 2, the apparent porosity of sintered magnesia decreased to 0. 6% from 2.0% of before hydration, closed porosity decreased to 2. 8% from 6. 1%, and bulk density increased to 3. 46 g · cm^ -3 from 3.29 g · cm^ -1.
文摘In order to widen the application of microcrystalline magnesite, the microcrystalline magnesite in Sichuan and Tibet area was used as the raw material to prepare light-burned MgO at 700,800,900, 1 000, 1 100 and I 200 ~C for 3 h, respectively. Then the physical and chemical properties of the light-burned MgO were detec- ted, and its application prospect was analyzed. The re- sults show that： （1） microcrystalline magnesite com- pletely decomposes forming light-burned MgO calcined at the temperature range of 700 - 1 200 ~C ; the MgO con- tent of the light-burned MgO is higher than 96. 51% ; the chemical activity is 88 - 130 s and the grain size is 40 - 200 nm ; it has the advantages of high purity, high activity and fine grain; （2） the light-burned MgO pre- pared with microcrystalline magnesite can be widely used in many industries; it can be used in refractories indus- try to prepare high-purity sintered magnesia and large crystal fused magnesia, or as an additive for refractory products, etc. ; it can also be used in magnesium chemi- cal industry to prepare electrical grade magnesia, sili- con-steel magnesia, environmental friendly flame retard- ant magnesium hydroxide, magnesium sulfate fertilizer, pharmaceutical grade magnesia, food grade magnesia, etc.
基金supported by the Natural Science Foundation of Hubei Province (2007ABA372)the New Century Excellent Talents in University (NCET-06-0676)
文摘Cr2O3 has eminent slag corrosion resistance. So, the magnesite -chrome brick is thought as an important refractory material used in RH refining furnace in the process of steel-making around the world. After chromebearing sols being prepared by sol-gel method, single sol （ Cr（ OH）3） and mixed sol （ Mg（ OH）2 - Cr（ OH）3） were impregnated into magnesite - chrome bricks by vacuum impregnation. The corrosion resistance of the impregnated bricks to silicon steel slag was studied by porosimetric analysis and fractal dimension calculation. The results showed that the corrosion resistance of impregnated magnesite -chrome brick was better than that of the unimpregnated brick and the brick impregnated by MgSO4 solution, and the one which has surface-treated by Mg（ OH）2 -Cr（OH）3 sol was the best, mainly because of lower apparent porosity, smaller pores diameter and their smoother inner sarface.
