应用化工系统分析理论中萨金特与威斯特伯格(R W H Ssrgent&A W W esterberg)的单元串搜索法和自由度分析法,对30万t/a大型凯洛格合成氨装置氨合成系统进行流程分块、再循环回路切割和单元设备计算排序,结果表明,当一定的原始设计...应用化工系统分析理论中萨金特与威斯特伯格(R W H Ssrgent&A W W esterberg)的单元串搜索法和自由度分析法,对30万t/a大型凯洛格合成氨装置氨合成系统进行流程分块、再循环回路切割和单元设备计算排序,结果表明,当一定的原始设计变量确定后,计算顺序中的每个单元设备(或选择的体系)的物料子问题的自由度均为0或小于0。该法既可避免复杂的物热联解并省去全系统的迭代收敛,又可应用序贯联立模块法进行物料平衡的模拟计算,使计算快速准确。展开更多
In acid treatment technology of Baotou mixed rare earth ore,large quantities of ammonia-nitrogen wastewater are produced in the step of ammonium bicarbonate precipitation to transform rare earth sulfate.In this paper,...In acid treatment technology of Baotou mixed rare earth ore,large quantities of ammonia-nitrogen wastewater are produced in the step of ammonium bicarbonate precipitation to transform rare earth sulfate.In this paper,we adopted a green precipitant magnesium bicarbonate(Mg(HCO3)2) to substitute ammonium bicarbonate to eliminate ammonia-nitrogen pollution.The effects of n(HCO3^-):n(RE^3+),aging temperature and aging time on the crystallization using Mg(HCO3)2 precipitation method were investigated.The results indicate that the rare earths could be completely recovered when n(HCO3^-):n(RE^3+) is higher than 3.15:1.The crystal water content of rare earth carbonates is affected by the aging temperature.The precipitate has a bad filterability when the aging temperature is over 40℃.This can be attributed to the less crystallized water molecules of the hydrated rare earth carbonate precipitation.The mixed rare earth carbonates are prone to be crystalline,and have a good filterability at aging temperatures below 40℃.Meanwhile,the evolution mechanism of crystalline mixed rare earth carbonates is reasonably deduced,the amorphous rare earth carbonates are first dissolute and then recrystallized.Under the optimized aging conditions,the purity of the crystalline precipitate meets the requirements of the fine product standard(GB/T 16479-2008).The filtrated could be used to produce Mg(HCO3)2,thus to realize the recycling of magnesium sulfate.展开更多
文摘应用化工系统分析理论中萨金特与威斯特伯格(R W H Ssrgent&A W W esterberg)的单元串搜索法和自由度分析法,对30万t/a大型凯洛格合成氨装置氨合成系统进行流程分块、再循环回路切割和单元设备计算排序,结果表明,当一定的原始设计变量确定后,计算顺序中的每个单元设备(或选择的体系)的物料子问题的自由度均为0或小于0。该法既可避免复杂的物热联解并省去全系统的迭代收敛,又可应用序贯联立模块法进行物料平衡的模拟计算,使计算快速准确。
基金supported by the National Science and Technology Support Program of China(2015BAB16B02)the National Natural Science Foundation of China(51504034).
文摘In acid treatment technology of Baotou mixed rare earth ore,large quantities of ammonia-nitrogen wastewater are produced in the step of ammonium bicarbonate precipitation to transform rare earth sulfate.In this paper,we adopted a green precipitant magnesium bicarbonate(Mg(HCO3)2) to substitute ammonium bicarbonate to eliminate ammonia-nitrogen pollution.The effects of n(HCO3^-):n(RE^3+),aging temperature and aging time on the crystallization using Mg(HCO3)2 precipitation method were investigated.The results indicate that the rare earths could be completely recovered when n(HCO3^-):n(RE^3+) is higher than 3.15:1.The crystal water content of rare earth carbonates is affected by the aging temperature.The precipitate has a bad filterability when the aging temperature is over 40℃.This can be attributed to the less crystallized water molecules of the hydrated rare earth carbonate precipitation.The mixed rare earth carbonates are prone to be crystalline,and have a good filterability at aging temperatures below 40℃.Meanwhile,the evolution mechanism of crystalline mixed rare earth carbonates is reasonably deduced,the amorphous rare earth carbonates are first dissolute and then recrystallized.Under the optimized aging conditions,the purity of the crystalline precipitate meets the requirements of the fine product standard(GB/T 16479-2008).The filtrated could be used to produce Mg(HCO3)2,thus to realize the recycling of magnesium sulfate.
