Dissolution rates of silicate minerals in water from a subcritical to a supercritical state effect of solvent properties

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	Dissolution rates of silicate minerals in water from a subcritical to a supercritical state effect of solvent properties
	Zhang, RH (Zhang, Ronghua); Hu, SM (Hu, Shumin); Zhang, XT (Zhang, Xuetong)
刊名	RESEARCH ON CHEMICAL INTERMEDIATES
	2011
卷号	37 期号:2-5 页码:243-258
关键词	Critical region Dissolution kinetics Silicate minerals Solvent effect High temperatures and high pressures
ISSN号	0922-6168
英文摘要	Hydrothermal reaction experiments of silicate minerals (actinolite, pyroxene, etc.) were carried out using flow-through reactors in the temperature range from 25 to 400 degrees C at 23 MPa. The dissolution in water of a multi-oxide silicate mineral, for example actinolite or pyroxene may require the breaking of more than one type of metal-oxygen bond. Differences between the rates at which these bonds break are often sufficiently large for dissolution to be non-stoichiometric. Dissolution rates (of Si) for actinolite and pyroxene in water were found to increase with increasing T from 25 to 300 degrees C, and then decrease with increasing T from 300 to 400 degrees C. The maximum release rates of Si are reached at 300 degrees C. The different metals in the minerals often have different release rates at a fixed temperature. At T < 300 degrees C the release rates of Na, Ca, Mg, Fe, and Al from minerals are usually higher than that of Si. In contrast, release rates of Si are higher than those of the others at T >= 300 degrees C. The hydrolysis of Si-O-Si bonds and metal ion-H+ ? exchange reactions at T < 300 degrees C are different from reactions at T >= 300 degrees C, at 23 MPa, because the solvent properties of water (decreasing density and dielectric constant in the region from sub-critical to supercritical state) affect reaction rates. log r (dissolution rates of Si) increases with 1/dielectric constant, as the temperature rises to close to 300 degrees C (or up to 374 degrees C) and at the critical pressure.
学科主题	岩矿鉴定与测试
WOS关键词	ELEVATED-TEMPERATURES ; FLOW SYSTEMS ; KINETICS ; STOICHIOMETRY ; PRESSURES ; FLUORITE ; FLUIDS ; PH
WOS研究方向	Chemistry
语种	英语
出版者	SPRINGER
WOS记录号	WOS:000291159400015
内容类型	期刊论文
源URL	[http://119.78.100.197/handle/2HKVOGP0/39317]
专题	中国地质调查局
作者单位	Chinese Acad Geol Sci, Inst Mineral Resources, Open Res Lab Geochem Kinet, Beijing 100037, Peoples R China
推荐引用方式 GB/T 7714	Zhang, RH ,Hu, SM ,Zhang, XT . Dissolution rates of silicate minerals in water from a subcritical to a supercritical state effect of solvent properties[J]. RESEARCH ON CHEMICAL INTERMEDIATES,2011,37(2-5):243-258.
APA	Zhang, RH ,Hu, SM ,&Zhang, XT .(2011).Dissolution rates of silicate minerals in water from a subcritical to a supercritical state effect of solvent properties.RESEARCH ON CHEMICAL INTERMEDIATES,37(2-5),243-258.
MLA	Zhang, RH ,et al."Dissolution rates of silicate minerals in water from a subcritical to a supercritical state effect of solvent properties".RESEARCH ON CHEMICAL INTERMEDIATES 37.2-5(2011):243-258.