The Experts below are selected from a list of 327 Experts worldwide ranked by ideXlab platform
John W Morse - One of the best experts on this subject based on the ideXlab platform.
-
extractability of metal Sulfide Minerals in acidic solutions application to environmental studies of trace metal contamination within anoxic sediments
Environmental Science & Technology, 1998Co-Authors: Craig D Cooper, John W MorseAbstract:Sulfide Minerals are an important sink for metals within anoxic sediments. Extraction techniques using cold HCl to measure the concentration of Sulfide mineral associated trace metals have gained wide acceptance as a proxy for potential metal bioavailability within the environmental community. However, certain metal Sulfide phases that can potentially release metals into a more bioavailable phase do not extract in HCl. Laboratory experiments have shown that covellite (CuS), chalcocite (Cu2S), cinnabar (HgS), millerite (NiS), heazlewoodite (Ni2S3), and vaesite (NiS2) are poorly soluble in HCl; while greenockite (CdS), mackinawite (FeS1-x), pyrrohtite (FeS), galena (PbS), and sphalerite (ZnS) are highly soluble in HCl. Surface area can also affect the apparent solubility of CuS and NiS in HCl. These results indicate that use of HCl-based extraction schemes (e.g., AVS/SEM ratios) to assay sediments for metal contamination could underestimate the potential bioavailability of several metals of general interest...
-
interactions of trace metals with authigenic Sulfide Minerals implications for their bioavailability
Marine Chemistry, 1994Co-Authors: John W MorseAbstract:Abstract Trace metals that are mobilized during early diagenesis can be coprecipitated with and adsorbed on authigenic Sulfide Minerals in anoxic sediments. A major portion (generally > 60%) of the non-silicate bound fraction of potentially toxic metals, such as As, Cu and Hg, is commonly coprecipitated with pyrite near the sediment-water interface. Traditional methods (e.g. 1 N HCl or citrate dithionite extractions) for determining the concentration of potentially bioavailable metals in sediments do not include the pyrite bound fraction. However, pyritized metals can be potentially bioavailable if the pyrite is oxidized. Pyrite oxidation commonly occurs during sediment resuspension, seasonal migration of the redoxocline in sediments and when dredge spoils are dumped on land. Experimental measurements of metal release from pyrite, in initially anoxic sediments exposed to oxic seawater, indicate that a major portion (20% to over 90%) of the pyrite bound metals can be released in a day or less. The As, Cu and Hg released from pyrite usually exceeds the concentration of their potentially bioavailable fraction determined by traditional methods. Consequently, the pyritization-depyritization of trace metals is probably an important process in controlling the bioavailability of many important trace metals.
Hong Zhong - One of the best experts on this subject based on the ideXlab platform.
-
the collecting performance and interaction mechanism of sodium diisobutyl dithiophosphinate in Sulfide Minerals flotation
Journal of materials research and technology, 2015Co-Authors: Hong Zhong, Zhenrui Huang, Gang Zhao, Shuai WangAbstract:Abstract The interaction mechanism of sodium diisobutyl dithiophosphinate (DTPINa) with chalcopyrite, pyrite, galena and sphalerite was investigated by single mineral flotation experiment, adsorption measurement and FTIR spectrum analysis. Single mineral flotation experiments showed that sodium diisobutyl dithiophosphinate exhibited a strong ability to collect chalcopyrite and galena. For chalcopyrite and pyrite, the recovery of chalcopyrite can reach 96.2% when the dosage is 12 mg/L and pH value is 8. In the same situation, the recovery of pyrite is as low as 13.5%. For galena and sphalerite, the recovery of galena reached 91.7% when the dosage was 50 mg/L at pH 11, and the recovery of sphalerite was only 16.9%. DTPINa adsorbed on chalcopyrite and galena surfaces are more than that on pyrite and sphalerite surfaces. The adsorption capacity of DTPINa on the Minerals surface is proportional to its dosage. The FTIR spectrum analysis results showed that the adsorption of DTPINa on Sulfide Minerals surface is chemical and S atoms in P S and P S may have taken part in the reaction. The natural ores experiments also confirmed the excellent performance of sodium diisobutyl dithiophosphinate.
-
a dft study on the structure reactivity relationship of thiophosphorus acids as flotation collectors with Sulfide Minerals implication of surface adsorption
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2013Co-Authors: Jingjing Xiao, Hong Zhong, Diwen Zhou, Phillip Choi, Zhenghe XuAbstract:Abstract Thiophosphorous compounds: diisobutyl dithiophosphate (DIBDTPA), diisobutyl dithiophosphinate (DIBDTPI), diisobutyl monothiophosphate (DIBMTPA) and diisobutyl monothiophosphinate (DIBMTPI) are widely used as flotation collectors and corrosion inhibitors, though the true nature of their bonding mechanisms to solid surfaces is still unclear. Using density functional theory (DFT) calculations, this study investigates the structure-reactivity relationship of these thiophosphorus molecules as flotation collectors with Sulfide Minerals. The results indicate that the O atom(s) bonded to the P atom in thiophosphorus molecules can significantly impact the chemical reactivity of the S atom(s) in the four reagents, and for DIBMTPA and DIBMTPI, they could even attend the chemical bond formation with metal atoms. The reactive power of the four compounds to mineral surfaces of Cu, Au, Ag and Pb Sulfides is predicted to be DIBDTPI ≫ DIBMTPI ≥ DIBDTPA > DIBMTPA, and their flotation selectivity against pyrite and sphalerite is suggested as DIBDTPA
-
the separation of cu fe Sulfide Minerals at slightly alkaline conditions by using ethoxycarbonyl thionocarbamates as collectors theory and practice
Minerals Engineering, 2006Co-Authors: Hong ZhongAbstract:Abstract The bench-scale and industrial flotation test results of Jiangxi Copper Corporation Yongping Copper Mine showed that the flotation separation of Cu/Fe Sulfide Minerals has been achieved at pH values above 13 for xanthates, about 11 for dialkyl thionocarbamates and around 8.5 for ethoxycarbonyl thionocarbamates (ECTC), respectively, and ECTC collectors were powerful for copper Minerals and very selective against iron Sulfide Minerals at pH 8–9. The flotation results have been explained from the structure–reactivity relationship of collectors by generalized perturbation theory and density functional calculation at B3PW91/6-31G(D) level.
Shaoyong Jiang - One of the best experts on this subject based on the ideXlab platform.
-
high precision in situ pb isotopic analysis of Sulfide Minerals by femtosecond laser ablation multi collector inductively coupled plasma mass spectrometry
Science China-earth Sciences, 2015Co-Authors: Honglin Yuan, Shaoyong Jiang, Kaiyun Chen, Chunlei Zong, Rong WangAbstract:An in-situ microanalysis of Pb isotopic compositions in Sulfide Minerals is carried out by using femtosecond laser-ablation multi-collector inductively coupled plasma mass spectrometry (fsLA-MC-ICP-MS). High-temperature-activated carbon was used to filter Hg contained in the carrier gas, which reduced the Hg background signal by 48% and also lowered the detection limit of the analysis. Fractionation and mass discrimination effects existing in the ICP-MS analytical processes were corrected using an internal reference Tl in conjunction with an external reference NIST SRM 610. The proposed method was used to analyze the Pb isotopic compositions of chalcopyrite, pyrite, and sphalerite from the Dulong Sn-Zn-In polymetallic ore district. The results showed that in this ore district, the Sulfide Minerals and different grains of the same Sulfide mineral show a large variation in Pb content up to 1000-fold. The studied pyrites show relatively higher Pb contents and homogeneous Pb isotopic compositions, whereas the sphalerites have low Pb contents but most variable Pb isotopic compositions. It is suggested that the large variation of Pb isotopic composition may reflect a late hydrothermal superimposition on the primary Sulfide formation. In addition, radiogenic Pb accumulated by radioactive decay of trace amounts of U over time in the host Minerals may also be one of the causes for the large variation range of Pb content and Pb isotopic composition of those low-Pb sphalerites. Chalcopyrite and sphalerite grains with Pb content greater than 10 ppm presented a consistent Pb isotopic distribution, whereas all the Sulfide grains with Pb content greater than 100 ppm had consistent Pb isotopic composition within 2s measurement uncertainties. The in-situ analysis of Pb isotopic composition agreed well with the results obtained by conventional chemical methods within 2s measurement uncertainties, indicating that the data obtained by fsLA-MC-ICP-MS are reliable. Additionally, this study indicates that the Pb isotopic composition could truthfully record the source of ore-forming Minerals only for Sulfide Minerals with high Pb content. On the contrary, the Pb isotopic composition of low-Pb Sulfide Minerals may be affected by trace amounts of U in the host Minerals that may lead to a highly radiogenic Pb isotope ratio. Alternatively, it is also possible that late fluid metasomatic overprinting may alter the Pb isotopic compositions.
-
sulfur lead and helium isotopic compositions of Sulfide Minerals from the dachang sn polymetallic ore district in south china implication for ore genesis
Mineralogy and Petrology, 2007Co-Authors: Kuidong Zhao, Shaoyong Jiang, Pei Ni, Hongfei Ling, Yaohui JiangAbstract:The Dachang Sn-polymetallic ore district is one of the largest tin producing districts in China. Its origin has long been in dispute between magmatic-hydrothermal replacement and submarine exhalative-hydrothermal origin. The Dachang ore district comprises several types of ore deposits, including the Lamo magmatogenic skarn deposit near a granite intrusion, the Changpo-Tongkeng bedded and vein-type Sulfide deposit, and the Gaofeng massive Sulfide deposit. Sulfide Minerals from the Lamo skarn ores show δ34S values in the range between −3 and +4‰ with a mean close to zero, suggesting a major magmatic sulfur source that likely was the intrusive Longxianggai granite. Sulfide Minerals from the Gaofeng massive ores show higher δ34S values between +5 and +12‰, whereas Sulfide Minerals from the Changpo-Tongkeng bedded ores display lighter δ34S values between −7 and −0.2‰. The difference in the sulfur isotope ranges in the two deposits can be interpreted by different degrees of inorganic thermochemcial reduction of marine sulfate using a one-step batch separation fractionation model. Sulfur isotopic compositions from the vein-type ores at Changpo-Tongkeng vary widely from −8 to +4‰, but most of the data cluster around −2.9‰, which is close to that of bedded ores (−3.6‰). The sulfur in vein-type ores might be derived from bedded ores or it represents a mixture of magmatic- and sedimentary-derived sulfur. Pb isotopic compositions of Sulfide Minerals in the Dachang ore district reveal a difference between massive and bedded ores, with the massive ores displaying more radiogenic Pb isotope ratios. Correlations of 206Pb/204Pb and 207Pb/204Pb or 208Pb/204Pb for the massive and bedded ores are interpreted as two-component mixing of Pb leached from sedimentary host rocks and from deep-seated Precambrian basement rocks composed of metamorphosed volcano-sedimentary rocks. Pb isotopic compositions of Sulfide Minerals from vein-type ores overlap with those of bedded Sulfides. Similar to the sulfur, the lead in vein-type ores might be derived from bedded ores. Skarn ores at Lamo show very limited variations in Pb isotopic compositions, which may reflect a major magmatic-hydrothermal lead source. Helium isotope data of fluid inclusions trapped in Sulfides indicate that He in the massive and bedded ores has a different origin than He in fluorite of granite-related veins. The 3He/4He ratios of 1.2–2.9 Ra of fluid inclusions from Sulfides at Gaofeng and Changpo-Tongkeng imply a contribution of mantle-derived fluids. Overall our data support a submarine exhalative-hydrothermal origin for the massive and bedded ore types at Dachang.
Peter R Girguis - One of the best experts on this subject based on the ideXlab platform.
-
authigenic metastable iron Sulfide Minerals preserve microbial organic carbon in anoxic environments
Chemical Geology, 2019Co-Authors: Aude Picard, Amy Gartman, Julie Cosmidis, Martin Obst, Charles Vidoudez, David R Clarke, Peter R GirguisAbstract:Abstract The burial of organic carbon (OC) in sedimentary environments promotes long-term carbon sequestration, which allows the release of oxygen in the atmosphere. Organo-mineral interactions that form between terrigenous Minerals and OC during transport to and deposition on the seabed enhance OC preservation. Here, we propose an authigenic mechanism for the coupled preservation of labile OC and metastable iron Sulfide Minerals under anoxic conditions. Sulfate-reducing microorganisms (SRM) are ubiquitous in anoxic environments and produce the majority of free Sulfide in marine sediments, leading to the formation of iron Sulfide Minerals in situ. Using high spatial resolution microscopy, spectroscopy and spectro-microscopy, we show that iron Sulfide bioMinerals precipitated in the presence of SRM incorporate and adsorb organic molecules, leading to the formation of stable organo-mineral aggregates that could persist for years in anoxic environments. OC/iron Sulfide assemblages consist of the metastable iron Sulfide mineral phases mackinawite and/or greigite, along with labile organic compounds derived from microbial biomass or from organic molecules released extracellularly by SRM. Together these results underscore the role that a major group of anoxic microbes play in OC preservation and illustrate the value of the resulting authigenic metastable iron Sulfide Minerals mackinawite and greigite in protecting labile organic molecules from degradation over time.
Li Zhou - One of the best experts on this subject based on the ideXlab platform.
-
galvanic interactions between metal Sulfide Minerals in a flowing system implications for mines environmental restoration
Applied Geochemistry, 2008Co-Authors: Heping Li, Li ZhouAbstract:Abstract Managing mine water that has been contaminated with metal Sulfide Minerals due to galvanic corrosion is becoming an increasingly important environmental problem. Here, galvanic corrosion was investigated by studying galvanic interactions between pyrite–chalcopyrite and pyrite–galena in flowing mediums such as mine discharge water and flowing rainwater. The results showed that the corrosion current density of pyrite–galena is greater than that of pyrite–chalcopyrite under identical conditions. The corrosion current density of the galvanic cell tends to increase with increasing concentrations of strongly oxidizing ions (e.g., Fe 3+ ) in the flowing medium, whereas the existence of non-oxidizing and non-reducing ions (e.g., Na + ) have no obvious influence on the galvanic cell. In addition, the corrosion current density increases with increasing flow rate. Using the galvanic model, mixed potential theory and Butler–Volmer equation, the experimental results were explained theoretically. Because these experiments were performed under conditions very similar to those seen in mine discharge water and flowing rainwater, these results have direct implications for the future management and control of environmental pollution from mining operations.
