| Global warming is one of the most significant environmental problems,and it is also one of the most serious challenges that human facing in the21st century. In order to avoid the potentially devastating consequences of global warming and climate change,the CO2emissions into the atmosphere caused by human activities should be reduced considerably. Using recyclable ammonium chloride as medium of CO2mineral sequestration has become an emerging technology, while the low ammonium chloride leaching rate of chrysotile turn into a bottleneck restricting the development of this process.The fluid particle reaction kinetics of chrysotile in NH4Cl solution is in conformity with the Elovich model and leaching process is usually finished in1hour. The leaching rate of magnesium can reach12.67%when the concentration of NH4Cl is5mol/1and the reacting temperature is100℃. And the leaching rate rise with the increasing reaction temperature, meanwhile, neither does the ammonium chloride concentration nor the solid/liquid ratio have much influence on it. The activation energy of dissolution process was determined to be129.56kJ/mol, which indicates that the whole reaction was controlled by surficial chemical reaction.For the low leaching rate of magnesium in ammonium chloride, we carried out a research on how heat-pretreatment modify the property of chryostile. When the roasting temperature is600℃, the leaching rate of chryostile can reach55.64%. Heat-pretreatment remove the hydroxyl of chryostile, and increase the specific surface area of minerals, leading to the improvement of reacting rate. But if the roasting temperature was increased, the leaching rate of chryostile dropped again. The cost of using recyclable agent ammonium chloride leaching magnesium ions from chrysotile for CO2sequestration is huge. So it is of great importance to decelop a new progress that can accelerate the leaching rate of magnesium from chrysotile and is economiaclly feasible. |
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