The effects of liquid-solid ratio and reaction time on the leaching rate of magnesium at room temperature were investigated,as well as the effects of the molar ratio of MgO/MgCl_(2),the amount of water added,and the a...The effects of liquid-solid ratio and reaction time on the leaching rate of magnesium at room temperature were investigated,as well as the effects of the molar ratio of MgO/MgCl_(2),the amount of water added,and the amount of acid-impregnated slag dosed on the compressive strength and water resistance of LR-MOC.The results showed that the magnesium element in the boron mud could be maximally leached under the conditions of 1:1 concentration of hydrochloric acid at room temperature,liquid-solid ratio of 2.5 mL·g^(-1),and reaction time of 5 h,and the main products were amorphous SiO_(2) as well as a small amount of magnesium olivine which had not been completely reacted.The LR-MOC prepared using the acid-soaked mixture could reach a softening coefficient of 0.85 for 28 d of water immersion when the molar ratio of MgO/MgCl_(2) was 2.2,the amount of water added was 0 g,and the acid-soaked slag dosing was 40 wt%,which also led to an appreciable late-strength,with an increase of 19.4%in compressive strength at 28 d compared to that at 7 d.Unlike previous studies,LR-MOC prepared in this way has a final strength phase that is not the more easily hydrolysed 3-phase but the lath-like 5-phase.For this phenomenon,we analyzed the mechanism and found that,during the acid leaching process,a part of amorphous SiO_(2) dissolved in the acid leaching solution formed a silica sol,in which Mg^(2+)played a bridging role to make the silica sol more stable.With the addition and hydrolysis of MgO,the silica sol gel coagulation slows down,providing a capping layer to inhibit the hydrolysis of the 5-phase crystals and providing some strength after coagulation.The amorphous SiO_(2) in the other part of the acid-impregnated slag generated M-S-H gel with Mg^(2+)and OH-,which synergised with the dense structure composed of interlocking crystals to improve the water resistance of LR-MOC.展开更多
The effect of boron mud and CaF2,which were used as fluxing agents,on surface tension and density of CaO-SiO2-B2O3 ternary slag systems was investigated.The surface tension and density were measured by using the ring ...The effect of boron mud and CaF2,which were used as fluxing agents,on surface tension and density of CaO-SiO2-B2O3 ternary slag systems was investigated.The surface tension and density were measured by using the ring detachment method and Archimedean method,respectively.The results indicated that surface tension and density of the slag systems decreased with increasing temperature in the range of 1380-1480℃.When 5%-10% CaF2 was employed as fluxing agent,the surface tension and density of slag were decreased with increasing CaF2 content,and the surface tension changed from 0.3to 0.6N/m,while the density changed from 3.4to 4.1g/cm3.However,when using 5%-10%boron mud as fluxing agent,the surface tension was enhanced,whereas the density decreased with the increase of boron mud content,and the variation range was 0.4-0.6N/m for surface tension and 3.2-3.9g/cm3 for the density.As a conclusion,using boron mud as fluxing agent to substitute for CaF2 did not cause significant changes in slag surface tension and density.展开更多
Extracting B2O3 from calcined boron mud(CBM) was studied. The effect of factors such as reaction temperature and NaO H-to-CBM mass ratio on B2O3 extraction efficiency was investigated. The results show that increasing...Extracting B2O3 from calcined boron mud(CBM) was studied. The effect of factors such as reaction temperature and NaO H-to-CBM mass ratio on B2O3 extraction efficiency was investigated. The results show that increasing reaction temperature and NaO H-to-CBM mass ratio increases B2O3 extraction efficiency. There are two stages for the B2O3 extracting process: 0–20 min is the first stage, which is rapid; 20–50 min is the second stage, which is slower than the first stage. The overall extracting process follows the shrinking core model, and the first and second stages are determined to obey the surface chemical reaction model and the diffusion through the products layer model,respectively. The activation energies of the first and second stages are calculated to be 41.74 and 15.43 kJ·mol-1,respectively. The B2O3 extracting kinetics equations of the first and second stages are also obtained.展开更多
Desilication kinetics of calcined boron mud(CBM) occurring in molten sodium hydroxide media was investigated. The effects of factors such as reaction temperature and Na OH-to-CBM mass ratio on silicon extraction effic...Desilication kinetics of calcined boron mud(CBM) occurring in molten sodium hydroxide media was investigated. The effects of factors such as reaction temperature and Na OH-to-CBM mass ratio on silicon extraction efficiency were studied. The results show that silicon extraction efficiency increases with increasing the reaction time and Na OH-to-CBM mass ratio. There are two stages for the desilication process of the calcined boron mud. The overall desilication process follows the shrinking-core model, and the first and second stages of the process were determined to obey the shrinking-core model for surface chemical reaction and the diffusion through the product layer, respectively. The activation energies of the first and second stages were calculated to be 44.78 k J/mol and 15.94 k J/mol, respectively.展开更多
The effect of several parameters on the recovery of silicon dioxide from calcined boron mud（CBM）such as stirring speed, temperature, sodium silicate concentration, and carbonation time was studied. The recovery of s...The effect of several parameters on the recovery of silicon dioxide from calcined boron mud（CBM）such as stirring speed, temperature, sodium silicate concentration, and carbonation time was studied. The recovery of silicon dioxide is 88 % when the stirring speed is450 r min-1, temperature is 60 °C, sodium silicate concentration is 1 mol L-1, and the carbonation time is 6 h.The effect of carbonation time on the recovery of silicon dioxide is divided into three kinetic regimes, and the carbonation process of sodium silicate solution follows a second-order reaction based on the double-film theory model. The apparent rate constant of the three kinetic regimes is 0.064, 3.178, and 1.130 L h mol-1, respectively.The amorphous SiO_2 products obtained by carbonating the purified solution have 99.6 % purity and are spherical with diameters of about 100 nm.展开更多
The boron mud is solid waste from a borax factory in Liaoning province, China. The main chemical compositions of the boron mud powder are MgO 43.36%, SiO2 25.99%, Fe2O3 5.55% (shown in Table 1), and its mineral phases...The boron mud is solid waste from a borax factory in Liaoning province, China. The main chemical compositions of the boron mud powder are MgO 43.36%, SiO2 25.99%, Fe2O3 5.55% (shown in Table 1), and its mineral phases are mainly forsterite, magnesite and phlogopite.展开更多
Forsterite is a highly demanded material in high-temperature industries due to its superior performance in elevated temperatures.This study proposes synthesizing high-quality forsterite via high-temperature thermochem...Forsterite is a highly demanded material in high-temperature industries due to its superior performance in elevated temperatures.This study proposes synthesizing high-quality forsterite via high-temperature thermochemical reactions using abundant boron mud waste.The new synthesis method capitalizes on the high reactivity of fine raw powder materials,enabling the reaction to reach completion at low temperatures rapidly.The chemical characteristics,microscopic morphology,and structure of synthe-sized samples are systematically studied using XRD and SEM.The results confirm that boron mud can be efficiently transformed into forsterite after 10 min of reactions at 1500℃.The synthesized products attain over 98.7%densification and contain more than 85.0%forsterite with well-developed grains.The activation energy of forsterite grain growth in the 1100-1500℃temperature range is 165.5 kJ/mol.This study provides a low-cost method for producing forsterite and an efficient and environmentally friendly solution for treating solid waste.展开更多
基金Funded by Provincial Basic Research Projects(No.LJKMZ20220947)。
文摘The effects of liquid-solid ratio and reaction time on the leaching rate of magnesium at room temperature were investigated,as well as the effects of the molar ratio of MgO/MgCl_(2),the amount of water added,and the amount of acid-impregnated slag dosed on the compressive strength and water resistance of LR-MOC.The results showed that the magnesium element in the boron mud could be maximally leached under the conditions of 1:1 concentration of hydrochloric acid at room temperature,liquid-solid ratio of 2.5 mL·g^(-1),and reaction time of 5 h,and the main products were amorphous SiO_(2) as well as a small amount of magnesium olivine which had not been completely reacted.The LR-MOC prepared using the acid-soaked mixture could reach a softening coefficient of 0.85 for 28 d of water immersion when the molar ratio of MgO/MgCl_(2) was 2.2,the amount of water added was 0 g,and the acid-soaked slag dosing was 40 wt%,which also led to an appreciable late-strength,with an increase of 19.4%in compressive strength at 28 d compared to that at 7 d.Unlike previous studies,LR-MOC prepared in this way has a final strength phase that is not the more easily hydrolysed 3-phase but the lath-like 5-phase.For this phenomenon,we analyzed the mechanism and found that,during the acid leaching process,a part of amorphous SiO_(2) dissolved in the acid leaching solution formed a silica sol,in which Mg^(2+)played a bridging role to make the silica sol more stable.With the addition and hydrolysis of MgO,the silica sol gel coagulation slows down,providing a capping layer to inhibit the hydrolysis of the 5-phase crystals and providing some strength after coagulation.The amorphous SiO_(2) in the other part of the acid-impregnated slag generated M-S-H gel with Mg^(2+)and OH-,which synergised with the dense structure composed of interlocking crystals to improve the water resistance of LR-MOC.
基金Item Sponsored by National Natural Science Foundation of China(51174099)Natural Science Foundation of Jiangsu Province of China(BK2010355)
文摘The effect of boron mud and CaF2,which were used as fluxing agents,on surface tension and density of CaO-SiO2-B2O3 ternary slag systems was investigated.The surface tension and density were measured by using the ring detachment method and Archimedean method,respectively.The results indicated that surface tension and density of the slag systems decreased with increasing temperature in the range of 1380-1480℃.When 5%-10% CaF2 was employed as fluxing agent,the surface tension and density of slag were decreased with increasing CaF2 content,and the surface tension changed from 0.3to 0.6N/m,while the density changed from 3.4to 4.1g/cm3.However,when using 5%-10%boron mud as fluxing agent,the surface tension was enhanced,whereas the density decreased with the increase of boron mud content,and the variation range was 0.4-0.6N/m for surface tension and 3.2-3.9g/cm3 for the density.As a conclusion,using boron mud as fluxing agent to substitute for CaF2 did not cause significant changes in slag surface tension and density.
基金financially supported by the National Natural Science Foundation of China(No.51204037)
文摘Extracting B2O3 from calcined boron mud(CBM) was studied. The effect of factors such as reaction temperature and NaO H-to-CBM mass ratio on B2O3 extraction efficiency was investigated. The results show that increasing reaction temperature and NaO H-to-CBM mass ratio increases B2O3 extraction efficiency. There are two stages for the B2O3 extracting process: 0–20 min is the first stage, which is rapid; 20–50 min is the second stage, which is slower than the first stage. The overall extracting process follows the shrinking core model, and the first and second stages are determined to obey the surface chemical reaction model and the diffusion through the products layer model,respectively. The activation energies of the first and second stages are calculated to be 41.74 and 15.43 kJ·mol-1,respectively. The B2O3 extracting kinetics equations of the first and second stages are also obtained.
基金Project(51204037)supported by the National Natural Science Foundation of ChinaProject(N140204016)supported by the Fundamental Research Funds for the Central Universities,China
文摘Desilication kinetics of calcined boron mud(CBM) occurring in molten sodium hydroxide media was investigated. The effects of factors such as reaction temperature and Na OH-to-CBM mass ratio on silicon extraction efficiency were studied. The results show that silicon extraction efficiency increases with increasing the reaction time and Na OH-to-CBM mass ratio. There are two stages for the desilication process of the calcined boron mud. The overall desilication process follows the shrinking-core model, and the first and second stages of the process were determined to obey the shrinking-core model for surface chemical reaction and the diffusion through the product layer, respectively. The activation energies of the first and second stages were calculated to be 44.78 k J/mol and 15.94 k J/mol, respectively.
基金financially supported by the National Natural Science Foundation of China(No.51204037)the Fundamental Research Funds for the Central UniversitiesChina(No.N140204016)
文摘The effect of several parameters on the recovery of silicon dioxide from calcined boron mud（CBM）such as stirring speed, temperature, sodium silicate concentration, and carbonation time was studied. The recovery of silicon dioxide is 88 % when the stirring speed is450 r min-1, temperature is 60 °C, sodium silicate concentration is 1 mol L-1, and the carbonation time is 6 h.The effect of carbonation time on the recovery of silicon dioxide is divided into three kinetic regimes, and the carbonation process of sodium silicate solution follows a second-order reaction based on the double-film theory model. The apparent rate constant of the three kinetic regimes is 0.064, 3.178, and 1.130 L h mol-1, respectively.The amorphous SiO_2 products obtained by carbonating the purified solution have 99.6 % purity and are spherical with diameters of about 100 nm.
文摘The boron mud is solid waste from a borax factory in Liaoning province, China. The main chemical compositions of the boron mud powder are MgO 43.36%, SiO2 25.99%, Fe2O3 5.55% (shown in Table 1), and its mineral phases are mainly forsterite, magnesite and phlogopite.
基金support provided by the National Natural Science Foundation of China (grant number U22A20410).
文摘Forsterite is a highly demanded material in high-temperature industries due to its superior performance in elevated temperatures.This study proposes synthesizing high-quality forsterite via high-temperature thermochemical reactions using abundant boron mud waste.The new synthesis method capitalizes on the high reactivity of fine raw powder materials,enabling the reaction to reach completion at low temperatures rapidly.The chemical characteristics,microscopic morphology,and structure of synthe-sized samples are systematically studied using XRD and SEM.The results confirm that boron mud can be efficiently transformed into forsterite after 10 min of reactions at 1500℃.The synthesized products attain over 98.7%densification and contain more than 85.0%forsterite with well-developed grains.The activation energy of forsterite grain growth in the 1100-1500℃temperature range is 165.5 kJ/mol.This study provides a low-cost method for producing forsterite and an efficient and environmentally friendly solution for treating solid waste.
文摘以铁尾矿为主要原料制备微晶玻璃,通过DTA,XRD,SEM分析方法,全面考察了晶化温度和晶化时间对微晶玻璃结构的影响.实验发现：随着析晶温度的升高,主晶相钙铁辉石没有改变,但晶体形态和析晶率发生了较大的变化;随着析晶温度的升高,晶体的规则程度增加,晶体尺寸增大,析晶率呈先增加后减小的趋势;当析晶温度高于1250℃时,晶体分布均匀程度降低;最佳晶化温度为1200-1250℃,晶化时间为180 min.
