This study investigates the behavior of Mo and Mo isotopes (δ^(98)Mo) in shales following leaching with HCl and HNO_(3) with the aim of simplifying the shale dissolution procedure.Up to 6%of the Mo was lost and the M...This study investigates the behavior of Mo and Mo isotopes (δ^(98)Mo) in shales following leaching with HCl and HNO_(3) with the aim of simplifying the shale dissolution procedure.Up to 6%of the Mo was lost and the Mo isotopes were unaffected when shales were leached using 9 M HCl after ashing.Bulk sample digestion or leaching by 4 M or more concentrated HCl after ashing were all found to be acceptable and reliable approaches to the analysis of Mo isotopes in shales.After black shale (CAGS-BS) was leached with 2 M HCl,1 M HCl,and 9 M HNO_(3),the Mo concentration ([Mo]) in the leachate was lower and δ^(98)Mo was heavier than that obtained from bulk digestion.A Mo isotope mass-balance model showed that the δ^(98)Mo in the residues was lighter than the δ^(98)Mo from the bulk digestion of CAGS-BS and of crustal igneous rocks.No more Mo was lost,nor did Mo isotope fractionation,if the double spike was added before rather than after ashing and followed by bulk digestion or leaching with 9 M HCl.For efficiency,leaching using 4 M or more concentrated HCl after ashing is preferred for Mo isotope measurements.展开更多
The operation variables,including feed rate of ore slurry,caustic solution and live steams in the double-stream alumina digestion process,determine the product quality,process costs and the environment pollution.Previ...The operation variables,including feed rate of ore slurry,caustic solution and live steams in the double-stream alumina digestion process,determine the product quality,process costs and the environment pollution.Previously,they were set by the technical workers according to the offline analysis results and an empirical formula,which leads to unstable process indices and high consumption frequently.So,a multi-objective optimization model is built to maintain the balance between resource consumptions and process indices by taking technical indices and energy efficiency as objectives,where the key technical indices are predicted based on the digestion kinetics of diaspore.A multi-objective state transition algorithm(MOSTA)is improved to solve the problem,in which a self-adaptive strategy is applied to dynamically adjust the operator factors of the MOSTA and dynamic infeasible threshold is used to handle constraints to enhance searching efficiency and ability of the algorithm.Then a rule based strategy is designed to make the final decision from the Pareto frontiers.The method is integrated into an optimal control system for the industrial digestion process and tested in the actual production.Results show that the proposed method can achieve the technical target while reducing the energy consumption.展开更多
基金supported by the National Key Research & Development Program of China(No.2019YFA0708404)the National Natural Science Foundation of China(Nos.41973020,41303002,41873027)。
文摘This study investigates the behavior of Mo and Mo isotopes (δ^(98)Mo) in shales following leaching with HCl and HNO_(3) with the aim of simplifying the shale dissolution procedure.Up to 6%of the Mo was lost and the Mo isotopes were unaffected when shales were leached using 9 M HCl after ashing.Bulk sample digestion or leaching by 4 M or more concentrated HCl after ashing were all found to be acceptable and reliable approaches to the analysis of Mo isotopes in shales.After black shale (CAGS-BS) was leached with 2 M HCl,1 M HCl,and 9 M HNO_(3),the Mo concentration ([Mo]) in the leachate was lower and δ^(98)Mo was heavier than that obtained from bulk digestion.A Mo isotope mass-balance model showed that the δ^(98)Mo in the residues was lighter than the δ^(98)Mo from the bulk digestion of CAGS-BS and of crustal igneous rocks.No more Mo was lost,nor did Mo isotope fractionation,if the double spike was added before rather than after ashing and followed by bulk digestion or leaching with 9 M HCl.For efficiency,leaching using 4 M or more concentrated HCl after ashing is preferred for Mo isotope measurements.
基金Project(62073342)supported by the National Natural Science Foundation of ChinaProject(2014 AA 041803)supported by the Hi-tech Research and Development Program of China。
文摘The operation variables,including feed rate of ore slurry,caustic solution and live steams in the double-stream alumina digestion process,determine the product quality,process costs and the environment pollution.Previously,they were set by the technical workers according to the offline analysis results and an empirical formula,which leads to unstable process indices and high consumption frequently.So,a multi-objective optimization model is built to maintain the balance between resource consumptions and process indices by taking technical indices and energy efficiency as objectives,where the key technical indices are predicted based on the digestion kinetics of diaspore.A multi-objective state transition algorithm(MOSTA)is improved to solve the problem,in which a self-adaptive strategy is applied to dynamically adjust the operator factors of the MOSTA and dynamic infeasible threshold is used to handle constraints to enhance searching efficiency and ability of the algorithm.Then a rule based strategy is designed to make the final decision from the Pareto frontiers.The method is integrated into an optimal control system for the industrial digestion process and tested in the actual production.Results show that the proposed method can achieve the technical target while reducing the energy consumption.
