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Chen L.,Central South University | Chen L.,Shandong Gold Group Co. | Yang T.,Central South University | Bin S.,Central South University | And 4 more authors.

This work reports an efficient reactor, i.e., oxygen-rich side blow furnace (OSBF), for high-lead slag reduction. An OSBF with a cross-sectional area of 8.4 m2 was applied in an industrial-scale test and the results were compared with those from a traditional high-lead slag reduction reactor, i.e., blast furnace (BF), with which an additional electric heating fore well (EHFW) was connected for slag cleaning. By using the OSBF, Pb and Cu recoveries were raised by 1.07% and 7.99% compared with those from the traditional BF+EHFW, respectively. The optimal slag type for recovering metal values in the OSBF was also analyzed. Within the range of Fe/SiO2 = 1.56–1.87 and CaO/SiO2 = 0.8–1.05, lower Pb and Cu contents of the slag can be achieved with Fe/SiO2 = 1.65–1.75 and CaO/SiO2 = 1.0. © 2014, The Minerals, Metals & Materials Society. Source

Leng C.-B.,Chinese Academy of science | Leng C.-B.,University of Tasmania | Huang Q.-Y.,University of Tasmania | Zhang X.-C.,Chinese Academy of science | And 7 more authors.

Studies on zircon ages, petrology, major and trace element geochemistry, and Sr-Nd-Hf-Pb isotopic geochemistry of intermediate volcanic rocks from the Southern Yidun arc, Sanjiang-Tethyan Orogenic Belt, SW China have been undertaken in this paper. They are used to discuss the petrogenesis of these rocks and to constrain the tectonic setting and evolution of the Yidun arc. These intermediate volcanic rocks were erupted at ca. 220. Ma (U-Pb zircon ages). Trachyandesite is the dominant lithology among these volcanic rocks, and is mainly composed of hornblende and plagioclase, with minor clinopyroxene and biotite. A hornblende geobarometer suggests that the stagnation of magma in the lower crust, where plagioclase crystallization was suppressed while hornblende crystallized, giving rise to high Sr/Y ratios that are one of the distinguishing features of adakites, after the primary magma originated from the lithospheric mantle wedge. Steeply right-inclined Rare Earth Element (REE) pattern combined with high La/Yb ratios suggests adakitic affinity of these volcanic rocks, implying that slab-melt from the subducting oceanic crust is a necessary component in the primary magma. Besides, trace element geochemistry and isotopic geochemistry also indicate that partial melting of pelagic sediments in the subduction zone and noticeable contamination with the lower crust were involved in the evolution of parental magma of these volcanic rocks. Based on previous work on the Northern Yidun arc and this study, we propose that the subduction was initiated in the Northern Yidun arc and extended to the southern part and that the Northern Yidun arc is an island arc while the Southern Yidun arc represents a continental arc, probably caused by the existence of the Zhongza Massif, that was invoked to be derived from Yangtze Block, as a possible basement of the Southern Yidun arc. © 2014 Elsevier B.V. Source

Yu G.-B.,University of Science and Technology Beijing | Yang P.,University of Science and Technology Beijing | Yang P.,Beijing Union University | Chen Z.-C.,Beijing General Research Institute of Mining And Metallurgy | Chen Z.-C.,Shandong Gold Group Co.
Meitan Xuebao/Journal of the China Coal Society

In order to solve the difficult problem of pillar extraction safely and efficiently in thin gently inclined ore body, the study of surrounding rock stability is very necessary. Pinglidian mining area of Sanshan Island Gold Mine was studied in this paper. On the basis of site investigation, laboratory rock mechanics test and the mechanical parameter analysis of rock mass, the surrounding rock quality of extracted pillar in thin gently inclined ore body were studied using the RMR classification method, the Q system classification method respectively. Results show that the surrounding rock stability of the stope is average. Also, the roof damage mechanisms of thin gently inclined ore body were analyzed. The rheologic mechanics model of roof was established based on Burgers model, which provides a theoretical basis and reference for roof supporting. In addition, a real-time monitoring system of surrounding rock stress was designed, which works well in pillar extraction in thin gently inclined ore body, and the variation of surrounding rock stress was obtained. The practical application proves that the system has high accuracy and stability. Source

Leng C.-B.,Chinese Academy of science | Zhang X.-C.,Chinese Academy of science | Hu R.-Z.,Chinese Academy of science | Wang S.-X.,Shandong Gold Group Co. | And 3 more authors.
Journal of Asian Earth Sciences

The Xuejiping porphyry copper deposit is located in northwestern Yunnan Province, China. Tectonically, it lies in the southern part of the Triassic Yidun island arc. The copper mineralization is mainly hosted in quartz-dioritic and quartz-monzonitic porphyries which intruded into clastic-volcanic rocks of the Late Triassic Tumugou Formation. There are several alteration zones including potassic, strong silicific and phyllic, argillic, and propylitic alteration zones from inner to outer of the mineralized porphyry bodies.The ages of ore-bearing quartz-monzonitic porphyry and its host andesite are obtained by using the zircon SIMS U-Pb dating method, with results of 218.3 ± 1.6. Ma (MSWD = 0.31, N = 15) and 218.5 ± 1.6. Ma (MSWD = 0.91, N = 16), respectively. Meanwhile, the molybdenite Re-Os dating yields a Re-Os isochronal age of 221.4 ± 2.3. Ma (MSWD = 0.54, N = 5) and a weighted mean age of 219.9 ± 0.7. Ma (MSWD = 0.88). They are quite in accordance with the zircon U-Pb ages within errors. Furthermore, all of them are contemporary with the timing of the Garzê-Litang oceanic crust subduction in the Yidun arc. Therefore, the Xuejiping deposit could be formed in a continental margin setting.There are negative ε Nd(t) values ranging from -3.8 to -2.1 and relatively high initial 87Sr/ 86Sr ratios from 0.7051 to 0.7059 for the Xuejiping porphyries and host andesites. The ( 206Pb/ 204Pb) t, ( 207Pb/ 204Pb) t and ( 208Pb/ 204Pb) t values of the Xuejiping porphyries and host andesites vary from 17.899 to 18.654, from 15.529 to 15.626, and from 37.864 to 38.52, respectively, indicative of high radiogenic Pb isotopic features. In situ Hf isotopic analyses on zircons by using LA-MC-ICP-MS exhibit that there are quite uniform and slightly positive ε Hf(t) values ranging from -0.2 to +3.2 (mostly between 0 and +2), corresponding to relatively young single-stage Hf model ages from 735Ma to 871Ma. These isotopic features suggest that the primary magmas of the Xuejiping porphyries and their host andesites were mainly derived from a metasomatized mantle, with contamination of about 5-10% crustal rocks during ascending.Comparing with typical porphyry Cu deposits, the Xuejiping porphyry Cu deposit is distinct by strong silicific and phyllic alteration and major stockwork veining mineralization in the ore-bearing porphyries, but lack of pervasive potassic alteration and disseminated mineralization. This indicates that there could be more prospective Cu resources in the Xuejiping ore district. © 2012 Elsevier Ltd. Source

Wang P.,Peking University | Wang P.,CAS Guangzhou Institute of Geochemistry | Chen Y.-J.,Peking University | Chen Y.-J.,CAS Guangzhou Institute of Geochemistry | And 3 more authors.
Ore Geology Reviews

The Great Hingan Range is located in the eastern sector of the Central Asia Orogenic Belt, and is the second important Mo province in China, next to the Qinling-Dabie orogenic belt. Previous studies concluded that all the Mo deposits (Mo-only or Mo-dominated polymetallic) in the area were formed in the Mesozoic, and related either to the syn- to post-collisional setting following the closure of the Paleo-Asia Ocean, or to the westward subduction of the Pacific plate. However, the fluids forming the giant Diyanqin'amu porphyry Mo deposit in the area disagree with the features of collision-type Mo deposits, but accord with those of the subduction- or continental arc-type. The Mo mineralization is hosted in the Late Jurassic volcanic rocks and genetically related to the buried porphyritic granite and aplitic granite. Two porphyritic granite samples yield LA-ICP-MS zircon weighted mean 206Pb/238U ages of 158.7±0.8Ma (MSWD=0.64, 2σ) and 158.0±0.9Ma (MSWD=0.38, 2σ), respectively. The aplitic granite yields a zircon U-Pb weighted mean 206Pb/238U age of 156.9±1.1Ma (MSWD=0.48, 2σ), slightly younger than the porphyritic granite. Seven molybdenite samples from the ores yield Re-Os isotope ages of 156.1±2.2 to 158.1±4.3Ma. These ages constrain that the Diyanqin'amu Mo system was formed in the period of 159-156Ma. The granites at the deposit have high contents of SiO2, K2O and Al2O3, and low contents of TiO2, MgO and CaO, showing a peraluminous high-K calc-alkaline affinity. These granites and the host volcanic rocks are characterized by enrichment of K, Rb, U, Pb, Th and LREE, and depletion of Nb, Ta, Ti and HREE, with negative Eu anomaly, which are similar to magmatic rocks in the Andean arc. Zircon grains from the granites show positive ε Hf(t) values of 4.2-9.0, with TDM2(Hf) ages of 0.63-0.94Ga. These geochemical data imply that the granites at Diyanqin'amu are highly fractionated I-type, formed in a continental arc generated by the southeastward subduction of the Mongol-Okhotsk oceanic plate. © 2016 Elsevier B.V. Source

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