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美国双语教育研究之评介 被引量:6
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作者 翁燕珩 《中央民族大学学报(哲学社会科学版)》 CSSCI 2000年第4期133-140,共8页
本文是一篇介绍与分析美国双语教育的文章 ,主要介绍了美国双语教育发展的历史进程。介绍了代表美国官方意识的学者对美国双语教育及其研究的分析和评论以及美国学术界对美国双语教育的研究和评论。同时还介绍了其他研究者对双语教育的... 本文是一篇介绍与分析美国双语教育的文章 ,主要介绍了美国双语教育发展的历史进程。介绍了代表美国官方意识的学者对美国双语教育及其研究的分析和评论以及美国学术界对美国双语教育的研究和评论。同时还介绍了其他研究者对双语教育的研究、分析和评论。 展开更多
关键词 双语教育 美国 效度 淹没 过渡 浸浸型
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Leaching behavior of metals from limonitic laterite ore by high pressure acid leaching 被引量:14
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作者 郭学益 石文堂 +1 位作者 李栋 田庆华 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2011年第1期191-195,共5页
The leaching behavior of metals from a nickeliferous limonitic laterite ore was investigated by high pressure acid leaching process for the extraction of nickel and cobalt.The effects of sulfuric acid added,leaching t... The leaching behavior of metals from a nickeliferous limonitic laterite ore was investigated by high pressure acid leaching process for the extraction of nickel and cobalt.The effects of sulfuric acid added,leaching temperature,leaching time and liquid/solid(L/S) ratio on metals extraction were examined.More than 97% Ni,96% Co,93% Mn,95% Mg and less than 1% Fe are extracted under optimum conditions.Analysis of the high pressure acid leaching residue by chemical and XRD analysis indicates that the residual iron and sulfur are mainly present in phases of hematite and alunite,respectively.The high pressure leaching process provides a simple and efficient way for the high recovery of nickel and cobalt from laterite ore,leaving residue as a suitable iron resource. 展开更多
关键词 high pressure acid leaching limonitic laterite leaching behavior NICKEL
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Selective leaching of chromium-containing slag by HCl 被引量:1
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作者 杨志辉 柴立元 +2 位作者 王云燕 赵堃 舒余德 《Journal of Central South University of Technology》 EI 2008年第6期824-829,共6页
A batch of column experiments was carried out to investigate the change of Cr(Ⅵ) concentration leached out from chromium-containing slag with HCI as leaching agent, and to study influences of pH, ratio of solid mas... A batch of column experiments was carried out to investigate the change of Cr(Ⅵ) concentration leached out from chromium-containing slag with HCI as leaching agent, and to study influences of pH, ratio of solid mass to solution volume, flow velocity and temperature on Cr(Ⅵ) leaching. The optimal parameters were obtained for Cr(Ⅵ) leaching and a fitting model was established to describe the procedure of Cr(Ⅵ) leaching. The results show that Cr(Ⅵ) concentration in leachate increases with decreasing pH and increasing flow velocity and temperature. Moreover, Cr(Ⅵ) leaching percentage increases with increasing ratio of solid mass to solution volume. The optimal parameters for Cr(Ⅵ) selective leaching are as follows: pH=3.0, 1:5 of ratio of solid mass to solution volume, 180 mL/min of flow velocity and 40 ℃ of temperature. The procedure of Cr(Ⅵ) leaching fits well with the model: v= 1.87t^-0.54, indicating that the leaching rate of Cr(Ⅵ) declines in an exponential order of-0.54. 展开更多
关键词 chromium-containing slag Cr(Ⅵ) leaching leaching rate dynamic model
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