从含铜铅金精矿中提取金银的工艺方法

采用湿法预处理除铜 -氨氰法研究了从含 Cu、Pb金精矿中提取 Au、Ag的新工艺方法。它与常规方法相比 ,Au、Ag的回收率分别提高了 34 .78%和 1 2 .52 % ,对于中小型黄金矿山具有推广价值。     

西藏嘎拉勒铜金矿床金和银的赋存状态研究

班公湖-怒江成矿带是西藏重要的铜多金属成矿带。嘎拉勒铜金矿床是该成矿带中发现较晚、研究程度较低且具代表性的矽卡岩型铜金矿床,矿石有用组分中金、银的赋存状态研究相对开展的较少,限制了矿床进一步的综合开发利用。作者通过野外地质调查与采样,采用光学显微镜鉴定、扫描电镜观察和X射线能谱仪测试分析等手段和方法,对矿石成分组分做了详细的研究,重点研究了矿床中金、银的赋存状态及主要载金矿物的特征。嘎拉勒铜金矿床金矿物以自然金、银金矿为主,其次为金银矿,可见粒间金、裂隙金及相对较少的包裹金形式,主要的载金矿物为石英、白云石、方解石、金属氧化物、硫化物及自然铋等。银矿物主要以金银系列矿物形式存在,少量自然银与放射性元素共生,此外,还有少量辉银矿。研究成果填补了该矿区金、银赋存状态研究的空白,对矿床的开发、利用有着重要的指示意义。     

Nitrate depuration of secondary sewage effluents in mangrove sediments

The sewage treatment plant (STP) at La Parguera, on the southwest coast of Puerto Rico, discharges an average of 228,000 dm³ of secondary sewage effluents per day into percolation ponds located at the landward margin of the coastal mangrove fringe. Effluents flowing from the STP percolation ponds to the adjacent mangrove fringe typically exhibited nitrate levels between 0.2 mM and 1.0 mM. Experimental determination of actual and potential denitrification using acetylene block and substrate disappearance techniques indicate that mangrove sediment microbial communities are capable of depurating 10 to 15 times the nitrate added in the STP effluent. Plots of porewater salinities vs nitrate concentrations show exponential decay of nitrate concentration. Our observations confirm the potential of mangrove sediment-microbial communities for nitrate depuration of secondary sewage effluents.     

火试金富集-重量法测定铜精矿中金银含量

研究了新型试金炉和灰吹炉在铜精矿中金银含量重量法检测中的应用,大大提高了铜精矿中金银含量的检出效率,满足了大批量铜精矿样品的快速测定。该方法具有简单、快速、准确度高的特点。     

砂金及"狗头金"次生增生的有限性

对砂金、“狗头金”的次生增生边宽度，砂金和“狗头金”的粒度和成色与原生金矿体的自然金粒度和成色的对比结果表明，砂金、“狗头金”在表生条件下的次生增生程度是十分有限的。对有限增生的原因进行了分析，认为可能与H2O2、微生物等对微细粒金具有双重作用有关，即其对微细粒金的溶解及再生均起作用。从而得出砂金及“狗头金”应由原生金矿体中的富金集合体（大块金及金的巨晶）在表生条件下遭受改造并发生有限增生所形成。     

西藏尼玛砂金矿中金和银的提纯与精炼

为提纯与精炼西藏尼玛砂金矿中的金和银，在王水介质中制作供还原的Au液，选择草酸作为还原剂很容易将Au还原，而且不与其他金属离子反应。砂金的提纯与精炼要经还原Au液、排除HNO3和砂金的2次溶解及Au的还原。尾渣以NaCO3、硼砂、KNO3为配料在焦炭炉中进行熔炼和泼珠，进而分离出金、银。在提取银的操作中，采用饱和NaCl水溶液。制定的金、银王水法提纯与精炼流程所产出金锭的成色大于等于99．99％，银锭成色大于等于99．90％。     

微细浸染型（卡林型）金矿成矿过程中碳和有机质的作用

在众多关于黔滇桂微细浸染型（卡林型）金矿研究成果的基础上，本文通过本类型金矿含碳及有机质的特征；金能形成金属有机化合物及原子簇化合物的特征的研究。提出金以金属有机化合物形式在本区上二叠统富含生物成因有机质的煤系地层中形成预富集；在区域热变质作用中，金以气相金属有机化合物方式向上运移，蓄积在上二叠统至中三叠统各层位的背斜和穹隆部位；动力变质带的断裂活动引起物理化学突变，使金的气相金属有机化合物在构造断裂带解体、裂化从而形成了含细分散碳质的微细浸染型含金硫化物原生矿化；并探讨了主成矿期后与有机质解体有关的叠加热液活动和表生氧化作用对原生矿化的改造。从而从有机质演化角度初步建立了此类型的成矿模式     

粤西金、银矿床成矿规律探讨

粤西是我国华南的主要金、银矿床集中医，医内金矿床与银（金）多金属矿床具有相间排列的分布规律，即从南到北分为以下5个矿带：廉江地区银（金）多金属矿带、高州-信宜金矿带、罗宁-云浮银（金）多金属矿带、德庆-清远金矿带、连山地区银（金）多金属矿带。本文从区域地层、岩浆岩及成矿作用等方面对粤西金、银矿床区域分布规律进行了探讨，认为影响金、银矿床分布的主要因素是不同区域地层、岩浆岩Au、Ag含量的差异及金矿床与银（金）多金属矿床成矿作用的差异。     

Ore-magmatic systems and metallogeny of gold and silver in Northeastern Asia

Regional ore-magmatic systems (OMS’s) and metallogenic gold-silver belts in northeastern Asia are considered, with emphasis placed on their relationships owing to the effect of geodynamic settings and underlying and host rock sequences on the localization of gold and silver deposits of different types. Particular types of lithologic assemblages with specific mineralogical and geochemical features are persistent throughout the metallogenic belts, controlled by regional noble-metal OMS’s. Regional OMS’s with one-, two-, and multilevel local OMS’s producing different types of noble-metal mineralization are described. The problem of mineral typomorphism in metallogenic analysis has been first raised. This analysis permits one to recognize indicators of ore formation (a particular genetic type of deposits, their formation and denudation levels), sources of ore-forming fluids, regional specific geochemistry and its relationship with magmatism. Regular presence of platinum in gold-bearing metallogenic zones is shown.     

The variation of silver content in native gold particles as revealed by ESCA

Depth profiling analysis of native gold samples using X-ray photoelectron spectroscopy (XPS) shows the surface layers of lode gold to be significantly enriched with silver to a depth of 0.02–0.04 microns and the surface layers of placer gold to be depleted of silver up to a depth of several microns. The change in the surface composition of gold samples taken from oxidation zones is of more complicated character. Model experiments suggest the surface segregation of silver in lode gold samples to be due to outward diffusion and oxidation of silver at the surface. In placer gold the depletion of silver is caused by leaching of the latter from the surface layers.     

河北金家庄金矿床矿物化学及金银赋存状态研究

河北金家庄金矿是一产在透辉石岩体中的矿床。本文用多种方法对该床中的主要矿石物进行了矿物化学、矿物标型和金、银赋存状态等方面的研究。不仅发现了含铂、钯的黄铜矿和闪锌矿，而且还找到了针镍矿。为探讨此金矿床的成矿特点提供了一些矿物学依据。     

The Mineralogy of gold and its relevance to gold recoveries

Processing of most gold ores, other than placers, involves conventional gravity separation and direct cyanidation. The difficult (or refractory) gold ores are not amenable to direct cyanidation and these ores require detailed mineralogical investigations to assist in determining the recovery processes. There are six mineralogical factors that can contribute to poorer recoveries. These are 1. the nature of the gold-containing minerals, 2. the grain size of the gold minerals, 3. the nature of the gangue minerals, 4. the associated sulfide minerals, 5. coatings on gold, and 6. chemically bound or invisible gold.Geological Survey of Canada Contribution Number 13089     

The relationship of silver and gold in the basal reef of the Witwatersrand System,South Africa

Ag/Au ratios of individual gold particles and of ore-samples obtained from the Basal Reef conglomerate horizon of the Upper Witwatersrand System in the Orange Free State Goldfield (South Africa) are discussed. The Ag/Au values of individual gold grains were found to be exceptionally constant at about 0.0812, whereas the Ag/Au ratios of the ore-samples have markedly higher values and show a large variation. These values indicate that the detrital gold has been homogenized during transportation and sedimentation and that part of the original silver content has been redistributed. It is likely that the first refining of detrital gold particles occurred in streams which eventually drained into the Witwatersrand basin. Further redistribution of the silver relative to the gold took place in the littoral zone of the basin, where the conglomerates were reworked by wave action and erosion. It is contended that supergenic enrichment of gold might also have taken place close to the original shore-line. These processes are believed to account for an increase in the Ag/Au values of ore-samples towards the northwest in the area investigated. Finally, the gold has been homogenized during the metamorphic period of the Witwatersrand System, when pseudohydrothermal transport and redeposition of certain constituents took place. It is suggested that the main portion of the silver content of the original alloy, which was redistributed during the various processes outlined above, is now present as finely dispersed silver minerals. The hypothesis of an elevation control of the Ag/Au values has been found to be improbable.

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Es werden Ag/Au Verhältnisse von Goldkörnern und von Erzproben aus dem Basal Reef-Konglomerathorizont des Oberen Witwatersrand-Systems im Oranje-Freistaat-Goldfeld mitgeteilt. Die Ag/Au-Werte der Goldkörner sind außerordentlich konstant und bewegen sich um 0,0812, während die Ag/Au-Verhältnisse der Erzproben merklich höher sind und starken Schwankungen unterliegen. Das detritische Gold muß daher während seines Transportes und während seiner Ablagerung homogenisiert worden sein und dabei einen Teil seines ursprünglichen Silbergehaltes verloren haben. Eine erste Raffinierung des Goldes geschah wahrscheinlich während des Flußtransportes der Partikel in den Sedimentationsraum. Weitere Umlagerungen von Silber relativ zu Gold fanden in der Küstenzone des Witwatersrand Beckens statt, im Bereich starker Wellenbewegung und intensiver Aufbereitung des Sedimentmaterials. Es wird zudem angenommen, daß in der Nähe der ehemaligen Küste deszendente Prozesse aktiv waren, welche Gold anreicherten. Diese Silberumlagerungen werden als Grund dafür betrachtet, daß im Untersuchungsgebiet die Ag/Au-Werte von Erzproben in der Haupttransportrichtung gegen Nordwesten hin zunehmen. Schließlich wurde das Gold im Gefolge der Metamorphose der Witwatersrand-Sedimente pseudohydrothermal über kurze Distanzen umgelagert und dabei weitgehend homogenisiert. Es wird angenommen, daß die Silbergehalte, welche bei den verschiedenen Umlagerungsprozessen freigesetzt wurden, heute größtenteils in Form fein verteilter Silbermineralien vorliegen. Eine Abnahme der Ag/Au-Werte mit zunehmender Teufe konnte nicht bestätigt werden.

     

The preg-robbing of gold and silver by clays during cyanidation under agitation and heap leaching conditions

Laboratory scale leaching tests were carried out in different experimental conditions, with monitoring of gold and silver recovery, the concentration of cyanide used in leaching, solution pH, and precious metal adsorption onto clay. Evidence for the adsorption or re-precipitation of gold from cyanide solutions onto clay minerals is conclusive and indicates that adsorption contributes to the total gold loss from conventional cyanidation. The loss is related to the type of clay, and appears to be affected by the extent of time cyanidation. It was observed that silver adsorption capacity was above 80% and that the degree of adsorption for gold oscillated between 1.68% and 7.49%, depending on the type and characteristics of the evaluated clay.     

Electrochemical accumulation of visible gold on pyrite and arsenopyrite surfaces

In galvanic cell arrangements gold is electrochemically deposited on semiconducting sulfide minerals (pyrite, arsenopyrite, chalcopyrite) from aerated as well as H₂S-saturated, gold-bearing 1 M KCl solutions. Observed cell potential differences of about 0.4–0.6 V in setups with one sulfide in aerated (cathode) and the other in H₂S-saturated (anode) solutions are comparable with known self-potentials of natural sulfide ore bodies. Gold preferentially accumulates on the cathode, i.e. under oxidizing conditions. Linked sulfides of variable composition in the same environment, either oxidizing or reducing, yield potential differences up to 20 mV. Such assemblages simulate conditions typically occurring at surfaces of chemically inhomogeneous single crystals (e.g. zonation). Depending on chemical composition, sulfide minerals show either n- or p-type conductivity. Visible gold is preferentially accumulated on individual domains of sulfide surfaces that act as cathodes, i.e. p-type conductors in n-p junctions. The experimental results are discussed in view of electrochemical accumulation of visible gold on sulfides in nature. Arsenic is the most important element in establishing p-type conductivity of pyrite and arsenopyrite. This feature may explain why As is such a powerful pathfinder in gold exploration.     

The role of gold,silver, and lead nanoparticles in the formation of deposits of precious metals

Doklady Earth Sciences -     

The influence of climate, geomorphology and primary geology on the supergene migration of gold and silver

Redistribution of secondary gold and silver through the weathering profile is dependent on the nature and stability of anionic complexes present in fluids of the oxidized zone. Through their effect on groundwater composition, and profile development, external controls such as climate and geomorphology, as well as regional and ore geology, may influence the form and concentration of complexes and hence the mobility of gold and silver during secondary processes. Secondary gold and silver in the supergene zone of the Edna May gold mine at Westonia in Western Australia, and at the Upper Ridges mine near Wau, in Papua New Guinea, have been transported under contrasting chemical and physical conditions occurring in the extreme climate and topography of these regions. Consequent differences in the nature of secondary gold and silver enrichments have been noted. At Westonia secondary gold reprecipitated by reduction at the site of iron oxidation, is of higher fineness (lower silver content) than primary gold, due to the formation of soluble AgCl⁰, and AgCl₂⁻ complexes. Gold migrates as the chloride complex AuCl₄⁻, in the acid, saline groundwaters present in the near-surface iron-rich laterite profile.At the Upper Ridges mine, repeated “flushing” by heavy rainfall in a region of rugged relief, dilutes groundwater and prohibits anion concentration and/or the development of acid conditions on a regional scale. Under neutral to basic, moderately oxidizing conditions, found in the vicinity of the weathering carbonate veins, gold and silver may be complexed by thiosulphate, to form Au(S₂O₃)³⁻₂ and Ag(S₂O₃)³⁻₂ or a mixed complex. Secondary gold-silver alloy is reprecipitated by oxidation in the MnO₂ wad assemblage. Gold of low fineness (high silver content) is reprecipitated by reduction at the water table, as both gold and silver complexes destabilize under similar pH and Eh conditions. The identification of secondary enriched gold horizons, relative to primary ore, has important repercussions for the potential viability of a drilled deposit.     

Correspondence of ores of silver and gold with basement terranes in the American southwest

The ratios of silver to gold produced from epigenetic ore districts of the American southwest reveal a consistency of value ranges, differing by an order of magnitude, that may be identified with either one or the other of two geologic terranes in which the ores occur. A discriminating value of the ratio is about 17.51, the ratio of crustal abundance given by Ahrens (1965). (No further significance is attributed to this value, at this time, beyond the fact that it appears to establish a reasonable separation of values on the basis of geographic occurrence.) Ores relatively enriched in Ag occur in terranes floored by thick Proterozoic clastic and Paleozoic marine successions, and ores relatively enriched in Au lie above or within a Proterozoic basement dominated by maficfelsic volcanic (arc) successions. Proterozoic granites occur in each region. The values of the ratio are broadly consistent within each terrane, irrespective of the age of ore formation, the ore deposit style, associated igneous rocks, structural control, differing interpreted styles of subduction, and weathering histories. These characteristics and associations support a hypothesis that metallogenic signatures of ore districts in this region are fundamentally related to the crust in which the ores occur.     

Some comparative marine chemistries of rhenium, gold, silver and molybdenum

Four metals, Re, Au, Ag and Mo, whose dissolved forms in seawater can potentially be reduced to insoluble states, have been measured in a variety of solids depositing under anoxic conditions: hydrothermal sulfides; coastal sediments; and phosphorites. For comparative purposes these elements have also been determined in ferromanganese minerals and pelagic sediments which have accumulated under oxidizing conditions. Rhenium appears to be a unique sentinel for identifying reducing depositional environments, where enrichments of greater than three orders of magnitude above crustal concentrations are found. Molybdenum follows Re in these sediments but Mo is enriched also in those that accumulate under oxidizing conditions. The reported Mo crustal concentrations appear low in comparison to our measured sedimentary values. Gold and Ag are concentrated in hydrothermal deposits and sulfides appear to be involved in the precipitation of these elements. Coastal sediments adjacent to a domestic outfall of Los Angeles, California contain extraordinary high accumulations of anthropogenic Au, Ag and Pt. The study seeks an understanding of the mobilities and sinks of these metals in the marine environment during the major weathering cycle. Further, anthropogenic contributions to their sedimentary concentrations are identified.