Magnetic properties and cation ordering of nanopowders of the synthetic analogue of kuramite, Cu3SnS4

An extensive characterisation of the magnetic properties of synthetic powders of kuramite, with formal composition Cu₃SnS₄, was performed. Powders were investigated through superconducting quantum interference device (SQUID) magnetometry, electron paramagnetic resonance (EPR) spectroscopy, X-ray powder diffraction (XRPD), scanning and transmission electron microscopies (SEM and TEM) and microanalysis. SEM and TEM reveal the presence of nanodimensioned particles. XRPD clearly shows that Cu₃SnS₄ crystallised in a cubic sphalerite-type structural model, in spite of the stannite-type tetragonal structure described for the natural phase. This difference arises from a full random distribution of cations. Synthetic kuramite nanopowders exhibit a marked paramagnetism, originated by the presence of Cu(II), definitely assessed by EPR measurements. Moreover, the overall magnetic behaviour of the sample cannot be simply ascribed to diluted paramagnetism, and this suggests the presence of strong superexchange interactions among Cu(II) ions even at room temperature. The main consequences of these results are the definitive assessment of the chemical formula Cu(I)₂Cu(II)SnS₄ and of a random distribution of Cu(II), Cu(I) and Sn(IV) ions within the available tetrahedral sites.     

Hydrogen bonding in basic copper salts: a spectroscopic study of malachite,Cu2(OH)2CO3, and brochantite,Cu4(OH)6SO4

Infrared and Raman spectra of the basic copper salts malachite, Cu₂(OH)₂CO₃, and brochantite, Cu₄(OH)₆SO₄, as well as of deuterated and ¹³C substituted samples are presented and discussed in terms of group theory and the hydrogen bonds present. The main results are that (i) the hydrogen donor strengths of the OH^? ions are strongly increased due to the very great synergetic effect of the copper ions, (ii) the acceptor strengths of the H-bond acceptor groups (SO₄ ^2-, CO₃ ^2-, and OH^? ions) are significantly modified by the linkage and coordination of the acceptor atoms — this complicates true assignment of the OH bands observed to the two and six different OH^? ions present in malachite and brochantite, respectively -, and (iii) the Cu — O stretching modes at 430–590 cm^?1 and 420–520 cm^?1 for malachite and brochantite, respectively, exhibit strong, partially covalent Cu — O bonding.     

Precipitation of iron,manganese, zinc,and copper on clean,ceramic surfaces in a stream draining a polymetallic sulfide deposit

Acid-cleaned ceramic plates placed upstream and downstream from a Cu-Zn-Pb sulfide deposit (Magruder mine) developed a precipitate of Fe-Mn oxides in a 36-day period. Copper and Zn concentrations on the coated surface, normalized to surface area and ratios with Fe and/or Mn, are distinctly anomalous for a distance of 2 km downstream from the mine.The major source of metals in the coatings is interpreted to be groundwater percolating into the stream bed. Anomalous concentrations of Cu and Zn in groundwater from the Magruder mine area, due to oxidation of sulfide minerals, probably accounts for the anomaly identified on the ceramic plates.     

Precipitate flotation of copper as the sulfide,using recyclable amphoteric surfactants

An experimental study was made to identify surfactants which are effective for removal of copper from dilute aqueous solution (100–500 ppm) by precipitate flotation as the sulfide, and which at the same time can be recovered from the CuS product for recycle. Batch flotation experiments confirmed that a cationic surfactant was necessary for flotation of CuS from such dilute suspensions; however, no satisfactory way could be found for recovering cationic surfactants from the CuS. This led to consideration of amphoteric surfactants, which are cationic at low pH and anionic at high pH. It was found that a change to negative, rather than simply neutral, charge was required for efficient surfactant recovery. It was further found, through the assistance of experiments in which the CuS suspension was agitated with solvents, that certain functional groups which interact chemically with the CuS surface should also be absent from the surfactant molecule. Following this logic, Amphoterge K-2 (Lonza Chemical Co.) was identified as a suitable surfactant, provided CuS was precipitated with S^2? in excess. Tests established that 95% of adsorbed Amphoterge K-2 could be recovered by raising the pH to 11 and boiling the suspension for one hour, followed by decanting. Surfactant thus recovered was effective in a second flotation test. Foamate solids settled rapidly; such behavior would help reduce the consumption of chemicals for the pH change.Column flotation studies were made using Amphoterge K-2 for removal of Cu²⁺ present at 100 ppm and pH = 2. High removals of CuS could be obtained at concentrations of surfactant above about 25 ppm, for which conditions a substantial fraction of the surfactant remains in solution rather than being adsorbed onto the CuS. The recovery of CuS would be improved by introducing the surfactant in a separate feed, below the feed of CuS suspension. Adding some surfactant in the CuS feed, as well as in a lower feed, gave an even better recovery of CuS (99.8%) at sufficiently high surfactant loadings.     

初论大陆环境斑岩铜矿

位于额尔古纳—呼伦断裂北西侧的乌努格吐山铜钼矿为一大型斑岩型铜钼矿床,矿区岩浆岩发育,为确定赋矿围岩和成矿母岩的侵位时代,探讨岩石成因,本文选择该矿床代表性的岩石样品,采用激光剥蚀多接收器电感耦合等离子体质谱法(LA-MC-ICP-MS)和激光剥蚀电感耦合等离子体质谱法(LA-ICP-MS),对岩浆岩的锆石U-Pb同位素和锆石Lu-Hf同位素进行了分析测定。研究表明：①研究区锆石稀土元素含量较高,重稀土强烈富集,具δEu负异常和δCe强正异常,稀土配分曲线具左倾特征;②不等粒二长花岗岩为赋矿围岩,锆石²⁰⁶Pb/²³⁸U加权平均年龄为200.96±0.88Ma(MSWD=3.0),岩体形成于早侏罗世,锆石Lu-Hf同位素特征表明岩浆源区为幔源物质和少量古老壳源物质的混合;③流纹质碎斑熔岩为成矿母岩,锆石²⁰⁶Pb/²³⁸U加权平均年龄为179.58±0.91Ma,形成于早侏罗世,锆石Lu-Hf同位素特征显示岩浆源区以幔源物质为主。研究结果揭示了从赋矿围岩到成矿母岩岩浆源区从壳源到幔源过渡的演化过程。

     

Pleistocene recycling of copper at a porphyry system,Atacama Desert,Chile: Cu isotope evidence

We present Cu isotope data of hypogene and supergene minerals from the Late Paleocene Spence Cu-Mo porphyry in the Atacama Desert of northern Chile. Chalcopyrite displays a restricted range of δ⁶⁵Cu values within the values reported for primary porphyry Cu sulfides (+ 0.28‰ to + 0.34‰, n = 6). Supergene chalcocite samples show heavier and remarkably homogeneous δ⁶⁵Cu values, between + 3.91‰ and + 3.95‰ (n = 6), consistent with previous models of Cu leaching and enrichment in porphyry systems. Secondary Cu minerals from the oxide zone show a wider range of composition, varying from + 1.28‰ and + 1.37‰ for chrysocolla (n = 6) to very light Cu isotope signatures reported for atacamite between -5.72‰ to -6.77‰ (n = 17). These data suggest redox cycling of Cu during supergene enrichment of the Spence Cu deposit, characterized by a first stage of supergene chalcocite formation from acidic, isotopically-heavy leach fluids of meteoric origin down-flowing in a semi-arid climate (44 to ~ 15-9 Ma). Reworking of the initial supergene copper assemblage, during the Pleistocene, by rising neutral and chlorine-rich deep formation waters under well-established hyper-arid climate conditions lead to the formation of atacamite with extremely fractionated Cu compositions. Essentially coeval chrysocolla formed by dissolution of atacamite during short episodes of wetter climatic conditions occurring in the latest Pleistocene.     

云南某硫化铜矿选矿试验

为确定云南某硫化铜矿矿石性质,制定合适的选矿方案.采用化学多元素分析、X射线衍射分析仪(XRD)、物相分析、矿物解离分析(MLA)和扫描电镜等分析测试技术,研究了矿石的矿物组成、连生体矿物共生特性及铜、硫的嵌布状态等.结果 表明,原矿含铜0.141％、硫9.80％,铜主要以硫化铜形式存在,硫的赋存形式以硫化物(黄铁矿)为主.黄铜矿多呈它形粒状,主要与黄铁矿、磁黄铁矿、褐铁矿、菱铁矿、石英、绿泥石共生;黄铁矿多呈它形粒状,主要与磁黄铁矿、菱铁矿、石英、钙铁榴石共生.脉石矿物主要为石英和钙铁榴石.针对矿石性质,采用"混合浮选—铜硫分离"的选铜工艺流程,根据最佳条件参数进行铜硫分离闭路试验,得到了铜品位、回收率分别为15.34％、58.75％的铜精矿;硫品位、回收率分别为30.44％、55.04％,含铁39.13％的硫精矿.相较现场生产指标,铜精矿品位提高了5％,回收率提高了近20％.铜硫分离效果显著,为低品位硫化铜矿铜的回收提供了借鉴.     

Microbial mutualism in leaching of Cu−Ni sulfide concentrate

With tightening legislations on air pollution and decreasing grades of Cu and Ni ores, the mineral processing industry will have to find an alternative to smelting. One such hydrometallurgical alternative is bacterial leaching; it utilizes the action of Thiobacillus ferrooxidans on sulfide minerals converting them to metal sulfates which can be leached by acid produced by the bacteria. The metal is recovered by cementation, solvent extraction or electrowinning. In the present paper, the authors report their test work with a Cu-Ni sulfide concentrate and show that the mutualistic association of T. ferrooxidans with nitrogen-fixing bacteria Beijerinckia lacticogenes helps leach more metal faster in a leaching medium devoid of any added carbon or nitrogen source. Use of intentionally mixed bacterial culture in ore leaching has not been previously reported.     

铜镍硫化物矿床研究进展

从赋矿岩体、控矿因素、成矿作用和矿体类型等方面综述了铜镍硫化物矿床的最新研究进展和成果。认为赋矿岩体由镁铁质—超镁铁质的不同岩石组成,其锶同位素组成显示深源的特点;岩浆的深部熔离作用使岩体的出露大小与矿床规模没有正相关性;成矿界面主要有岩性组合界面、构造界面、构造物理—化学界面和构造流体界面等,它们严格控制成矿物质的最终定位;除岩浆熔离和结晶分异成矿作用外,成矿作用强调厂硫化作用、热液成矿作用和接触交代成矿作用,相应的形成了热液型矿体和矽卡岩型矿体。     

花岗岩中铟与锡铜铅锌的关系及其富集成矿意义

全球已知的富铟矿床多与锡石硫化物矿床或富含锡的硫化物矿床有关,这些矿床的形成均与酸性岩浆作用有关。尽管铟的富集参考机理已经积累了较多研究成果,但关于锡在铟的富集成矿过程中起了什么作用?花岗岩浆演化过程中铟与锡等成矿元素的关系如何?等等,这些科学问题依然有待深入的研究。本文对滇东南薄竹山花岗岩和其中的"包体"、都龙矿区南温河花岗岩及矽卡岩矿物、广西昆仑关花岗岩、湖南柿竹园和骑田岭花岗岩中In与Sn、Cu、Pb、Zn的关系进行了初步研究,结果表明,花岗岩浆从结晶成岩→分异出成矿流体→遭受变质与蚀变→与围岩发生接触交代的全过程,In与Sn始终保持同步变化的正相关关系,而In与Cu、Pb、Zn之间不存在相关关系。此外,花岗岩中云母类矿物是In和Sn的主要载体矿物,且其中In与Sn也同样具有很好的正相关性。上述研究结果表明从岩浆结晶成岩到富集成矿过程中,铟与锡是共同迁移的。本文认为在锡存在的情况下,铟更容易超常富集,这可能就是富铟矿化多与锡矿化伴生的重要原因之一。     

Plumboselite, Pb3O2(SeO3), a new oxidation-zone mineral from Tsumeb, Namibia

Plumboselite, ideally Pb₃O₂(SeO₃), is a new selenite (IMA2010?C028) from the Tsumeb mine, Namibia. It occurs as fibres on clausthalite and is also associated with smithsonite, mimetite and vaterite. Plumboselite occurs in subparallel to divergent clusters of thin, flattened, colourless fibres up to 0.3?mm in length, but not exceeding 5???m in width and 2???m in thickness. The fibres are elongated parallel to [001] and flattened on {010}, with {010} the only form observed. The crystals have a dull to adamantine lustre and a white streak. The tenacity is brittle and the Mohs hardness is estimated to be between 2 and 3. Plumboselite crystals are optically biaxial with parallel extinction and are length fast in all orientations. The Gladstone-Dale relationship predicts n _av?=?2.115. The high indices of refraction and small crystal size prevented the determination of other optical properties. The calculated density is 7.814?g/cm³. The empirical formula (based on 5 O atoms) is Pb_2.92Ca_0.01Se_1.03O₅. Plumboselite is orthorhombic, space group Cmc2₁, a?=?10.5384(11), b?=?10.7452(13), c?=?5.7577(7) ?, V?=?651.98(12) ?³ and Z?=?4. The five strongest lines in the powder X-ray diffraction pattern are [d _obs in ?/(I)/hkl]: 3.155/(100)/221; 1.956/(26)/042,402; 2.886/(22)/311,002; 1.713/(21)/223; 2.691/(17)/040. The crystal structure was solved from single-crystal X-ray diffraction data and refined to R ₁?=?0.0371 on the basis of 200 unique reflections with F _o?>?4??F. The structure is based on double [O₂Pb₃] chains of edge-sharing oxo-centered [OPb₄] tetrahedra along c, between which are sited SeO₃ triangles. The two independent Pb²⁺ atoms and the Se⁴⁺ atom have sterochemically active lone electron pairs.     

西藏北部舍索与拉屋铜矿床硫化物铅同位素特征

本文在系统的野外地质工作基础上,对舍索与拉屋矿床的矿石硫化物铅同位素组成进行综合分析,进而示踪其成矿物质来源。结果显示,舍索矿区矿石硫化物铅的²⁰⁶Pb/²⁰⁴Pb值为18.517~18.776,²⁰⁷Pb/²⁰⁴Pb值为15.671~15.756,²⁰⁸Pb/²⁰⁴Pb值为38.955~39.33;拉屋矿区矿石硫化物铅的²⁰⁶Pb/²⁰⁴Pb值为18.651~18.757,²⁰⁷Pb/²⁰⁴Pb值为15.707~15.823,²⁰⁸Pb/²⁰⁴Pb值为39.183~39.561。研究表明,舍索与拉屋矿床矿石硫化物铅同位素含量比值具有明显的上地壳特征,指示两个矿床成矿物质主要来自上地壳。其中舍索矿床成矿物质富集受燕山期岩浆作用影响,而拉屋矿床部分成矿物质由晚石炭纪地幔物质的喷流沉积作用提供。     

S K- and L-edge XANES and electronic structure of some copper sulfide minerals

The S K and L-edge x-ray absorption near-edge structures (XANES) of low bornite, cubanite, chalcocite, covellite, enargite and tetrahedrite have been measured with synchrotron radiation. The near-edge features are interpreted based on comparison with the S K- and L-edge spectra of chalcopyrite and a MO/energy band structure model. The XANES spectra of these sulfides reflect the DOS of unoccupied S s-, p- and d-like states near and above the Fermi level. In tetrahedral Cu-Fe sulfides, the Fe³⁺ 3d crystal field band has much more significant DOS of unoccupied S 3p-and 3s-like states than the Cu⁺ 3d crystal field band. For Cu sulfides, the Cu⁺ 3d crystal field band has the higher DOS of S 3p- and 3 s-like states in tetrahedral structure than in structures with the triangular CuS₃ cluster. The shifts in both S K- and L-edges correlate approximately linearly with the energy gap.     

The distribution of Hg, Ba, Cu and Zn in the vicinity of cupriferous sulfide deposits, Troodos complex, Cyprus

A geochemical rock- and soil-sampling program was carried out in the vicinity of eight concealed “Cyprus type” deposits, occurring in marginal mafic to intermediate metapillow lavas of the Troodos Ophiolite Complex. The mineralization of massive and stockwork sulfide ore is characterized by the predominance of pyrite, intergrown with less chalcopyrite and minor amounts of sphalerite.Background values of Hg are in the range of 8–12 ppb for soils and 3–6 ppb for surface rocks. Anomaly/background ratios of 10:1 (soils) and 5:1 (rocks) have been found only, where Hg migrated along channels formed by faults cutting shallow-seated mineralization. Here, Hg sometimes shows significant correlations with Cu, Zn, Ba and exceptionally with Co. However in one case an Hg anomaly in soils and surface rocks was detected directly over a deposit. The use of Hg as indicator element for these types of deposits is therefore limited. Buried mineralization may be delineated more distinctly by Cu, Zn and Ba.     

The structure of freedite,Pb8Cu(AsO3)2O3Cl5

Summary The structure of freedite, Pb₈Cu(AsO₃)₂O₃Cl₅, [a = 13.578(2),b = 20.099(3),c = 7.465(1)Å; = 105.73(1)°; space group C2/m; Z = 4] was determined by direct methods and Fourier summations. The refinement of the atomic coordinates and thermal parameters-the metal atoms anisotropic, the remaining atoms isotropic-yielded anR value of 0.086 (R _w = 0.061). The five crystallographically independent Pb atoms are each surrounded by three resp. four O atoms and four Cl atoms. The novel feature of this structure are formal [(AsO₃)₂(CuCl)₂(AsO₃)₂] groups, in which the Cu atoms are tetrahedrally coordinated to two Cl and two As atoms [Cu-Cl = 2.43(8)Å2 × , Cu-As = 2.32(1)Å2 ×]. The mineral is considered to contain Cu(I) and As(III) atoms linked together by covalent Cu-As bonds. The formal groups mentioned are bound to the Pb atoms via Cl and O atoms.

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Die Struktur des Freedits, Pb₈Cu(AsO₃)₂O₃Cl₅

Zusammenfassung Die Struktur des Freedits, Pb₈Cu(AsO₃)₂O₃Cl₅, [a = 13,578(2),b = 20,099(3),c = 7,465(1)Å; = 105,73(1); Raumgruppe C2/m;Z = 4] wurde anhand direkter Methoden und Fouriersummationen bestimmt. Die Verfeinerung der Ortskoordinaten und der Temperaturparameter - Metallatome anisotrop, übrige Atome isotrop -ergab einenR-Wert von 0,086 (R _w = 0,061). Die fünf kristallographisch verschiedenen Pb-Atome werden von drei bzw. vier O-Atomen sowie jeweils vier Cl-Atomen umgeben. Ein neues Bauprinzip dieser Struktur sind formale [(AsO₃)₂(CuCl)₂(AsO₃)₂]-Gruppen, in denen die Cu-Atome durch zwei Cl- und zwei As-Atome tetraedrisch umgeben sind [Cu-Cl= 2,43(8)Å2 ×, Cu-As = 2,32(1)Å2 x]. Es wird angenommen, daß in diesem Mineral Cu(I)- und As(III)-Atome vorliegen, die über kovalente Bindungen verknüpft sind. Diese formalen Gruppen sind über die Cl- und O-Atome an die Pb Atome gebunden.

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With 2 Figures     

The spatial distribution and source of arsenic, copper, tin and zinc within the surface sediments of the Fal Estuary, Cornwall, UK

ABSTRACT Estuarine sediments commonly form major sinks for contaminants released during industrial activity. Many industrial processes lead to the release of metals initially in solution, which can then be adsorbed on to, for example, Fe hydroxides or clay minerals. However, in the mining industry, there are two major contaminant waste streams: (1) metals discharged in solution via mine drainage; and (2) particulate grains of the ore‐forming or related minerals released after ore processing. The release of particulate waste can have a major long‐term impact on environmental geochemistry. In this study, we have mapped the distribution of arsenic, copper, tin and zinc within the surficial sediments of the Fal Estuary, Cornwall, UK, an area that drains a historically important polymetallic mining district. There are clear spatial variations in the contaminants, with the highest levels (> 2800 p.p.m. As, > 5000 p.p.m. Cu, > 3000 p.p.m. Sn and > 6000 p.p.m. Zn) within Restronguet Creek on the western side of the estuary. Mineralogical studies show that small (< 20 µm) grains of detrital arsenopyrite, chalcopyrite, cassiterite and sphalerite are very abundant within the surface sediments. Most of the sulphide grains are fractured, but mineralogically unaltered, although some grains show alteration rims caused by oxidation of the sulphides. The geochemistry and mineralogy are indicative of sediment supply from the discharge of particulate waste into the estuary during historical mining activity. Subsequently, this particulate waste has been largely physically and biologically reworked within the surface sediments. Although considerable effort has been made to minimize contaminants released via mine drainage into the estuary, the potential flux of contaminants present within the intertidal and subtidal sediments has not been addressed. Benthic invertebrates living within the area have adapted to be metal tolerant, and it is likely that the dominant source of bioavailable metals is a result of alteration of the particulate mine waste present within the intertidal and subtidal sediments.