Tons Of Ore Research Articles

Sources of ore‐forming material for Pb‐Zn deposits in the Sichuan‐Yunnan‐Guizhou triangle area: Multiple constraints from C‐H‐O‐S‐Pb‐Sr isotopic compositions

The Sichuan‐Yunnan‐Guizhou Pb‐Zn triangle area is located in the western margin of the Yangtze Block and comprises more than 400 ore deposits or prospects. This triangular area contains 200 million tons of ores at average grades of 5 wt.% Pb and 10 wt.% Zn. The Pb‐Zn ore bodies are mainly distributed as stratoid and vein types within the Neoproterozoic to Permian carbonate rocks, which are typical epigenetic Pb‐Zn mineralizations. Previous studies have mainly focused on individual deposits. In this study, the compositions of C‐H‐O‐S‐Pb‐Sr isotopes of approximately 20 typical deposits are summarized and studied in detail to reveal the source of the ore‐forming material. δ13CPDB ‐ δ18OSMOW isotopic compositions of the hydrothermal calcite, dolomite, and fluid inclusions show that CO2 in the ore‐forming fluids could have been derived from marine carbonate with subordinate incorporation of organic matter. In addition, δDH2O ‐ δ18OH2O isotopic studies also indicate the multisource features of the ore‐forming fluids, for example, meteoric water and metamorphic water; meanwhile, some deposits are related to organic fluids. The δ34S values of most sulphide minerals range from +9.0‰ to +28.6‰, similar to late Neoproterozoic to Permian seawater sulphate (+8.0‰ to +38.7‰). This similarity suggests that the reduced sulphur in sulphides could have been mainly derived from the thermochemical sulphate reduction of the host strata seawater sulphate. In addition, thermal decomposition of sulphur‐bearing organic matter could have provided some of the reduced sulphur for mineralization in some Pb‐Zn deposits. The Pb isotopic compositions of the sulphides from most deposits are totally homogeneous and located between the crustal Pb and orogenic Pb evolution curves. Comparing these deposits with the regional basement rocks, sedimentary strata, and Permian Emeishan basalts, we propose that the metals for Pb‐Zn mineralization were mainly derived from the basement rocks and sedimentary country rocks. For some deposits (e.g., Jinshachang) with highly radiogenic Pb isotopic compositions, their Pb mainly originated from Precambrian basement carbonaceous slate and Lower Cambrian shales. The (87Sr/86Sr)t ratios of sphalerite, hydrothermal calcite, and fluorite range from 0.7099 to 0.7469, higher than those of the regional sediments and the Emeishan basalts, but lower than those of the Proterozoic basement rocks. Such features also indicate the mixing source for Sr in sulphides and ore‐forming fluids. The comprehensive study of multiple C‐H‐O‐S‐Pb‐Sr isotopes from typical deposits suggests mixed sources for the ore‐forming fluids and materials in this triangular area.

Structural setting of Fimiston- and Oroya-style pyrite-telluride-gold lodes, Paringa South mine, Golden Mile, Kalgoorlie: 1. Shear zone systems, porphyry dykes and deposit-scale alteration zones

The Golden Mile in the 2.7 Ga Eastern Goldfields Province of the Yilgarn Craton, Western Australia, has produced 385 million tonnes of ore at a head grade of 5.23 g/t gold (1893–2016). Gold-pyrite ore bodies (Fimiston Lodes) trace kilometre-scale shear zone systems centred on the D2 Golden Mile Fault, one of three northwest striking sinistral strike-slip faults segmenting upright D1 folds. The Fimiston shear zones formed as D2a Riedel systems in greenschist-facies (actinolite-albite) tholeiitic rocks, the 700-m-thick Golden Mile Dolerite (GMD) sill and the Paringa Basalt (PB), during left-lateral displacement of up to 12 km on the D2 master faults. Pre-mineralisation granodiorite dykes were emplaced into the D2 shear zones at 2674 ± 6 Ma, and syn-mineralisation diorite porphyries at 2663 ± 11 Ma. The widespread infiltration of hydrothermal fluid generated chlorite-calcite and muscovite-ankerite alteration in the Golden Mile, and paragonite-ankerite-chloritoid alteration southeast of the deposit. Fluid infiltration reactivated the D2 shear zones causing post-porphyry displacement of up to 30 m at principal Fimiston Lodes moving the southwest block down and southeast along lines pitching 20°SE. D3 reverse faulting at the southwest dipping GMD-PB contact of the D1 Kalgoorlie Anticline formed the 1.3-km-long Oroya Shoot during late gold-telluride mineralisation. Syn-mineralisation D3a reverse faulting alternated with periods of sinistral strike-slip (D2c) until ENE-WSW shortening prevailed and was accommodated by barren D3b thrusts. North-striking D4 strike-slip faults of up to 2 km dextral displacement crosscut the Fimiston Lodes and the barren thrusts, and control gold-pyrite quartz vein ore at Mt. Charlotte (2651 ± 9 Ma).

Investigation of Affecting Parameters on Heap Leaching Performance and Reducing Acid Consumption of Low Grade Oxide-Sulfide Copper Ore

Heap leaching method is known as cheap method for copper extraction. Presence of clay and acid consumer waste minerals are the most critical issues because they may bring out the process from economic mode. For reduce acid consumption and increasing copper extraction in heap leaching method, about 3 tons sample was taken randomly from different low grade zones. After homogenization and spelling into small parts, bottle roll tests were carried out to achieve maximum copper recovery and acid consumption in a short time at pH= 1, 1.1 and 1.2. Maximum copper recovery were 60.8, 60.2 and 60.1%, respectively. Also acid consumption were 107.30, 99.90 and 93.23 kg/t of ore, respectively. After diagnostic tests, nine columns with dimension 2m height and 15cm diameter were filled by 0.5, 1 and 1.5 inches ore. Columns were irrigated with 7, 9 and 11 g/l as acid solution concentration at flow rates of 7, 11 and 15 l/m2*h for 63 days. Results showed that there are high correlation between copper and iron recoveries. Copper recovery changed from 25.5% to 58.9% while iron recovery changed from 4.7% to 15.2%. Acid consumption were achieved between 18 to 54 kg per ton of ore. Acid solution concentration and irrigation flow rate are the most important parameters on the copper and iron recoveries. By increasing of leaching period Copper extraction will increase, but acid will be waste more. Copper and iron recoveries were increased with increasing the acid solution concentration and irrigation flow rate but Increasing in amount of acid consumption does not increase copper extraction inevitably. Irrigation flow rate of acid solution has significant effect on acid consumption. With decreasing the ore particle size, both of copper recovery and acid consumption were increased.

Chapter 17 Geochemistry and geochronology of granites hosting the Mawchi Sn–W deposit, Myanmar: implications for tectonic setting and emplacement

The Mawchi Mine in Myanmar is a historic world-class Sn–W deposit within the tin province of Southeast Asia, extending from Yunnan in SW China through Myanmar and Thailand, via Malaysia, to the Tin Islands of Indonesia, over a distance of 2700 km (Cobbing et al. 1992; Schwartz et al. 1995). The Mawchi Mine (Fig. 17.1) is located about 219 km SE of Nawpyitaw, the capital city of Myanmar. It was the world's largest tin–tungsten quartz vein system exploited before World War II, and between 1980 and 1990 the Mawchi Mine produced 17 000 tons of ore (unpublished Mawchi Mine data). Fig. 17.1. Granitoid belts of Myanmar and adjacent countries (modified after Cobbing et al. 1992 and Sone & Metcalfe 2008). Bender (1983) gave a summary of the geology of the Mawchi Mine described by Hobson (1940, 1941); the petrology of the rock types and mineralization were described by Dunn (1938). Subsequently Khin Zaw & Khin Myo Thet (1983) discussed fluid inclusion studies, but no new data have been published on the geology of the Sn–W granites of the Mawchi Mine in recent years. In this contribution we discuss the petrogenesis and tectonic setting of granites associated with the Mawchi Sn–W deposit based on our recent investigations of its petrology, geochemistry and its timing through U–Pb zircon dating. Cobbing et al. (1986, 1992) distinguished Granitic Provinces in the Southeast Asian Tin Belt; this concept has formed a widely accepted basis for the discussion of the granites in Southeast Asia. In Myanmar the Central Valley Granite Province (Cobbing et al. 1992) extends from Wuntho southwards into Salingyi and Popa. Most of the granitoids in this belt are metaluminous, calc-alkaline I-type granites; their composition ranges from diorite to granodiorite and their ages from Cretaceous to Cenozoic (Khin Zaw 1990; …

Perfection Of Methods Of Mathematical Analysis For Increasing The Completeness Of Subsoil Development

The economy of Russia is based around the mineral-raw material complex to the highest degree. The mining industry is a prioritized and important area. Given the high competitiveness of businesses in this sector, increasing the efficiency of completed work and manufactured products will become a central issue. Improvement of planning and management in this sector should be based on multivariant study and the optimization of planning decisions, the appraisal of their immediate and long-term results, taking the dynamic of economic development into account. All of this requires the use of economic mathematic models and methodsApplying an economic-mathematic model to determine optimal ore mine production capacity, we receive a figure of 4,712,000 tons. The production capacity of the Uchalinsky ore mine is 1560 thousand tons, and the Uzelginsky ore mine - 3650 thousand. Conducting a corresponding analysis of the production of OAO “Uchalinsky Gok”, an optimal production plan was received: the optimal production of copper - 77961,4 rubles; the optimal production of zinc - 17975.66 rubles. The residual production volume of the two main ore mines of OAO “UGOK” is 160 million tons of ore.

Application of truncated gaussian simulation to ore-waste boundary modeling of Golgohar iron deposit

Truncated Gaussian Simulation (TGS) is a well-known method to generate realizations of the ore domains located in a spatial sequence. In geostatistical framework geological domains are normally utilized for stationary assumption. The ability to measure the uncertainty in the exact locations of the boundaries among different geological units is a common challenge for practitioners. As a simple and informative example of such a boundary, one can consider the boundary between ore and waste materials in an ore deposit. This boundary addresses the percentages of the ore and the waste, and also affect the future economy of mine and all precedent mine designs and mine plans. Deterministic approaches, based on interpretation of geological phenomenon, provide just one scenario of ore-waste variation, and do not offer a model for uncertainty of boundaries. On the other hand, geostatistical simulations, based on stochastic models, can measure the uncertainty of such a boundary. Through different techniques for spatial simulation of the categorical data (geological domains) truncated gaussian simulation has been proved to be versatile when geological units have sequential geometries and/or there are few number of indicators (ore and waste). This study addresses the application of TGS for conditional simulation of ore and waste domains in Golgohar iron ore deposit. Separation of the ore and waste domains has affected the ore tonnage estimation and resource evaluation. Various simulations can be considered as the spatial realizations of ore and waste. TGS can generate realizations of the domains and measure the uncertainty of ore-waste boundary. The accuracy of result has been checked through performance evaluation section and different scenarios (e.g. best, average and worst). The best scenario is the one with the most accuracy that is calculated from confusion matrix. The scenario No. 44 with 96 million cubic meters tonnage has an accuracy over 86 percent that is proposed as the best scenario for future mine design and planning.

Production Quality, Value and Revenue in Polish Copper Mines

Polish copper ore deposits, located in the Legnica-Głogów Copper District (LGOM) documented an area of over 200 km2, at a depth of 600-1400 meters. The estimated resources equal to 22.7 million tonnes of copper (proven and probable), or 44.4 million t (measured and indicated), or 8.7 million t (infered), at the criterion of profitability at a cost less than 50 cents per ton of ore. Organization of production takes place in the combine of mining and metallurgy (KGHM). Ore is extracted in three mines: Lubin, Polkowice-Sieroszowice and Rudna. The total production of these mines is about 31 million tonnes/year of ore, from which it receives a 576000 t/y of copper, 1152 t/y of silver, 1066 kg/y of gold, and certain amounts of Pb, Zn, Se, Re, Ni, SO4, H2SO4. The quality (grading) of the ore in exploited deposits is varied, affecting the quality and quantity of produced concentrates, what influence on its market value. The paper presents a brief description of ore deposit and estimates mines revenues and production profit. Calculations show that at today's (June 2016) metal prices each of the mine can expect the following net smelter revenue: Lubin ∼⃒41, P-S ∼⃒70, Rudna ∼⃒75 $/t of ore. But estimated cost production differs less, i.e.: 45, 56 and 65$/t of ore respectively, because of mining depth.

Sulfur- and lead-isotope geochemistry of the Balugou Cu-Pb-Zn skarn deposit in the Wulonggou area in the eastern Kunlun Orogen, NW China

The small-scale Balugou Cu-Pb-Zn skarn deposit (45 298 tonnages of ore at 0.1% to 3.99% Cu, 0.20% to 0.43% Pb and 0.76% to 10.92% Zn) is located in the Wulonggou area in the eastern Kunlun orogen, NW China. Ore deposition is spatially and temporally related with the pre-collisional Anisian Balugou granites (~244 Ma). The mineralization hosted by the contact between marble beds within the Paleo-Proterozoic Jinshuikou Group and Balugou granites, was structurally and lithologically controlled. The mineralogy of the Balugou deposit includes an early simple skarn mineral gangue (epidote with little diopside) and a late complicated quartz sulfide assemblage (pyrite, pyrrhotite, chalcopyrite, sphalerite, galena, bornite, quartz, carbonate and chlorite). The δ34S values of eighteen sulfides range from -2.1‰ to +2.8 ‰, with an average of +0.07‰, and the calculated δ34SH2S values for H2S in hydrothermal fluids range from -3.2‰ to +2.4‰, with an average of +0.03‰, suggesting a relatively homogeneous magmatic (±mantle) source, with sulfur produced directly by the Balugou granites. The sixteen sulfides have 206Pb/204Pb ratios from 18.367 4 to 18.384 1, 207Pb/204Pb ratios from 15.634 6 to 15.641 5, and 208Pb/204Pb ratios from 38.455 5 to 38.485 0, which are close to those of K-feldspars from the Balugou granites, but are far away from age-corrected lead isotopic ratios of six wall-rock samples. So it was considered that the Pb sources of sulfides must be almost derived from the Balugou granites rather than the older wall-rocks. Collectively, it’s suggested that the Balugou Cu-Pb-Zn deposit belongs to skarn deposit, and the sulfur and lead deposited in it were leached from the Anisian Balugou granites.

Application of Biohydrometallurgy to Copper Mining in Zambia: Prospects and Opportunities

The consumption of copper worldwide has grown fast since 2000; the mining industry is increasingly faced with the necessity to process low grade ores and waste tailings, from current mining operations. The economic extraction of copper from low-grade ores requires low-cost processing methods such as biohydrometallurgy. This study looks at a general panorama of copper mining in Zambia and discusses biohydrometallurgy as a novel and economically viable process for copper extraction. It also presents future prospects of this technology in Zambia. Since early 1930s, the copper mining industry has been the economic and social pillar of Zambia with about 80% contribution to the total export earnings and about 13% Gross Domestic Product (GDP). Mineralisation in the Zambian Copperbelt is dominantly sulphide, comprising of chalcopyrite, bornite and chalcocite among others with grades of the ore deposits generally in the range of 3 - 4% copper and 0.1 - 0.2% cobalt. Huge low grade copper deposits (~0.67% Cu) which are dominantly sulphides (chalcopyrite) were recently discovered in Lumwana area in the North-western Zambia and are currently being exploited. Reports show that more than one billion tons of ore (c.2.7% Cu) has so far been mined from the mines on the Copperbelt Province of Zambia and conservative estimates suggest that a further two billion tons await exploitation. This provides considerable opportunities for further exploration and mining in Zambia. However, there is currently no commercial copper processing plants in operation on a large-scale in Zambia via biohydrometallurgical process. In order for Zambian mining industry to considerably improve recoveries at inherently lower capital cost, there is need to focus effort on research in this innovative technology and its application.

Pilot scale microwave sorting of porphyry copper ores: Part 2 – Pilot plant trials

An experimental pilot plant was constructed, commissioned and operated at a major porphyry copper mine to understand the challenges of microwave infrared thermal (MW-IRT) sorting at scale and to compare batch laboratory performance with pilot-scale continuous sortability performance. A method was developed to define the 95% confidence intervals on pilot plant operating windows from experiments on 50–150 fragments performed in a laboratory based replica of the pilot scale microwave treatment system. It appeared that the laboratory testing methodology predicted the sortability of the ores fairly well. For the 11 ore types and three size classes (−76.2+50.8mm, −50.8+25.4mm and −25.4+12.7mm) tested over 233 pilot plant experiments, approximately 42% of the better optimised pilot plant runs predicted copper recovery to within ±5% copper recovery and approximately 84% of the runs to within ±10%. These figures were improved to approximately 50% predicted to within ±5% and approximately 90% to within ±10% if the −25.4+12.7mm size class was omitted. It was demonstrated that laboratory testing better predicted pilot plant sorting performance and provided a narrower operating window when a larger sample size (>50 fragments) was considered due to improved representivity. It is, therefore, fully expected that better predictions would result from larger laboratory sample sizes than those tested during any future testing campaigns. To date, approximately 15,500 tonnes of ore has been processed through the pilot-scale test facility, generating significant engineering know-how and demonstrating MW-IRT sorting at a scale in the order of that required by the mining industry.

Block model data reduction and sensitivity analysis

ABSTRACTMaximising ore tonnage at a selected target grade requires that appropriate ore identification criteria be established. Iron ore mining block models may consist of many millions of estimated blocks, each block corresponding to the smallest mining unit, with grade interpolated from drill-hole data. Each block can be considered as a potential ore candidate. Analysis of such a huge database can require large computational resources, especially for sensitivity analysis requiring multiple computations. However, an alternative streamlined approach is possible, where the data are compressed to an appropriately smaller and representative subset. The consequent data reduction not only makes it feasible to consider the simultaneous analysis of multiple pits but also considerably speeds up computation, enabling sensitivity analysis of the potential ore tonnage as a function of the required grade. Ore identification criteria can be successfully established using appropriately chosen reduced data comprising less than one per cent of the blocks. The ore identified is virtually indistinguishable in tonnage and grade from the ore that would be selected using the entire block model. Two methods of data reduction are tested: sampling (using a proportion of unaltered blocks), and binning (consolidating groups of blocks to a single average grade). The source blocks are first sorted (such as by location, analyte grade, Principal Component score, random order or value) before sampling or binning. In this study, the sorting options considered were by location and Fe grade. The effectiveness of each method was evaluated using the block model sub-sets to select the maximum tonnage of ore at a specified target grade. Block model data from an anonymous Pilbara iron ore project with about one million blocks averaging 1.132 kt were used. The blocks are from multiple resource models, to be blended to a single product. Sampling is shown to be superior to binning, because sampling preserves the full variability while binning, although matching the block mean grade, reduces the block variability. It was found that the appropriately sampled data sets (sorted by location) gave results virtually identical to the results for the full data set, even when the samples comprised less than one per cent of the original blocks. The reduction in computer time to identify maximum tonnage at a specified grade was approximately proportional to the sample percentage. The increase in computation speed greatly facilitated sensitivity analysis. A sampled data set of one-eighth the total block model was used to investigate the effects of changing each of the component grades around the original grade specification. The results of this sensitivity analysis are discussed, and illustrate the potential benefit of carrying out sensitivity analysis in determining feasible and marketable product grades.

Ore selection to maximise value

Ore selection is generally aimed at producing product with a consistent target grade matching a perceived market requirement. A composite selection criterion ‘Comp’ (a linear function of the grade vector) can be used to maximise ore tonnage at a specified target grade (in Fe and contaminants) extractable from a block model. The blocks correspond to the selective mining units, with grades interpolated from diamond drill-hole data. An iterative procedure has been developed to identify the coefficients and cut-off value for the composite function ‘Comp’, maximising potential ore tonnage at target grade. Commonly, target grade is pre-determined by marketing. However, there is no guarantee that maximising ore tonnage at a specified target grade maximises the potential value of the mine. If the value of ore could be expressed as a linear function of the grade components, then these coefficients would be appropriate for the selection criterion ‘Comp’; the cut-off value for ‘Comp’ would correspond to the marginal cost of production; all blocks with a ‘Comp’ score above the cut-off would be classified as ore, and the cumulative grade of these ore blocks would be the average product grade over the life of the mine. Unfortunately, no such value function for iron ore is generally available. Methods for estimating the value function are discussed, using the spot price and sensitivities based either upon operational tolerances for Fe and the contaminants or upon published price differentials. This approach has been applied to an anonymous Pilbara deposit with about one million blocks averaging 1.1 kt. It is shown how the optimal target grade, cut-off grade and maximum tonnage can all be explored as a function of marginal cost and iron ore price. Alternatively, given marginal cost and an iron ore price, the effects of changing the tolerances (and therefore the relative costs of the contaminants) can also be explored. The procedure can enable informed decision-making for an iron ore mine. Rather than setting final policy for the entire life-of-mine, it enables target grades and tonnage estimates to be revised by re-computation as the mine life proceeds, to recognise changes in market conditions and knowledge about the resource. It should be emphasised that this paper is concerned with ore selection rather than ore sequencing. Appropriate ore selection is a necessary but not sufficient condition for maximising value. Having identified the set of blocks that potentially maximise value, the sequence in which they are mined will present a trade-off between producing at constant grade and extracting high-value ore early. The sequencing issue is not considered here. It is shown that optimum ore selection for an open-pit mine is independent of any consideration of discount rates, although ore sequencing will depend upon the time value of money if the product grade is to vary across time. Although the study considers an iron ore deposit, the method can be extended to any open-pit mining where ore value can be expressed as a linear composite of multiple grade components.

The Bauxite deposits of Seydişehir region (Mortaş and Doğankuzu deposits); Their geological, mineralogical and geochemical characteristics

Turkey hosts essential bauxite deposits, typically of the karstic-type. The most economically important bauxite deposits of Turkey form in the Seydisehir-Akseki region of the central Taurides Mountains. The Mortas and Dogankuzu deposits are the most important deposits in that region. The bauxite beds contain boehmite, hematite, rutile, smectite, quartz, diaspore, calcite, pyrite, marcasite and goethite. Brown to red-colored bauxite minerals are massive, oolitic – pisolitic textured. The Seydisehir schists could be possible parent rocks of bauxites, and have unearthed acidic source (mostly granite) with hornblende and plagioclase minerals. The schists were compositionally mature with minimal alkali feldspar sediments. The Mortas deposit is 400 m long and up to 40 m thick; it averages 10 m thick. It has about 5 million tons of ore reserves, with ~50 percent Al2O3. The Dogankuzu bauxite deposit is situated 2 km southwest of the Mortas deposit, with 14.9 million metric tons of ore at 61 percent Al2O3. The Dogankuzu ore was deposited on a fault-controlled karst surface of Cenomanian limestone succession, which was overlain by 5- to 10-cm-thick Santonian limestones. The bauxite has been mined by the Seydisehir aluminum factory, which was founded in 1973, and privatized in 2005. The plant is capable to produce 65.000 ton liquid aluminum per year, around 15% of Turkey’s Aluminum demand.

LIXIVIAÇÃO DE MINÉRIOS DE OURO DE BAIXO TEOR POR ROTA ALTERNATIVA AO PROCESSO DE TANQUES AGITADOS (CIL)

Avaliou-se no presente trabalho uma rota alternativa para a lixiviação de minérios de ouro de baixo teor para se integrar a uma planta industrial no Uruguai que atualmente emprega o processo Carbon in Leaching (CIL). Diversos ensaios de lixiviação utilizando-se a técnica bottle roll test de 20 litros e colunas de 3 metros foram realizados visando-se estabelecer alguns parâmetros, critérios de operação e dimensionamento para avaliar um processo industrial de lixiviação para tratar cerca de 1.000.000 de toneladas de minério contendo cerca de 0,65 g de ouro por tonelada de minério (g/t). Foram concebidas pilhas de 4 metros de altura, minérios com uma granulometria 80% menor que 12,67 mm (P80 de 12,76mm), tempo de operação de 3 anos e atingindo-se uma produção anual de 455 quilogramas de ouro.doi: https://doi.org/10.18540/2446941602022016029

An application of possibilistic programming to production sequencing of mining parcels

The mineral industries have recently experienced low commodity prices and escalating operational costs. This forces mining companies to find more efficient and productive ways to operate mines. The production sequence of mining blocks significantly affects the profitability of a mining project. Under capacity and access constraints, high quality blocks are forced to be produced during earlier periods to take advantage of the time value of money. However, financial and quality characteristics (e.g. grades, ore and waste tonnages of a block, ore prices) are imprecise at the planning stage. This research aims to address the uncertainties associated with grade and financial parameters so as to obtain a robust solution. Within this scope, the sequencing problem of mining parcels is formulated as a multi–objective optimization problem in fuzzy form, and subsequently is converted to a maximin (maximize the minimum) formulation. This formulation is then solved using a mixed integer programming solver. Two case studies show that the proposed fuzzy possibilistic model can generate an efficient compromise solution while considering uncertainties.

Fluid inclusion characteristics and molybdenite Re-Os geochronology of the Qulong porphyry copper-molybdenum deposit, Tibet

The Qulong porphyry copper and molybdenum deposit is located at the southwest margin of the Lhasa Terrane and in the eastern region of the Gangdese magmatic belt. It represents China’s largest porphyry copper system, with ∼2200 million tonnes of ore comprising 0.5 % Cu and 0.03 % Mo. The mineralization is associated with Miocene granodiorite, monzogranite and quartz-diorite units, which intruded into Jurassic volcanic units in a post-collisional (Indian-Asian) tectonic setting. Field observations and core logging demonstrate the alteration and mineralization at Qulong are akin to typical porphyry copper systems in subduction settings, which comprise similar magmatic-hydrothermal, potassic, propylitic and phyllic alteration assemblages. Molybdenite Re-Os geochronology confirms the relative timeframe defined by field observations and core logging and indicates that the bulk copper and molybdenum at Qulong were deposited within 350,000 years: between 16.10 ± 0.06 [0.08] (without and with decay constant uncertainty) and 15.88 ± 0.06 [0.08] Ma. This duration for mineralization is in direct contrast to a long-lived intrusive episode associated with mineralization based on previous zircon U-Pb data. Our fluid inclusion study indicates that the ore-forming fluid was oxidized and contained Na, K, Ca, Fe, Cu, Mo, Cl and S. The magmatic-hydrothermal transition occurred at ∼425 °C under lithostatic pressure, while potassic, propylitic and phyllic alteration occurred at hydrostatic pressure with temperature progressively decreasing from 425 to 280 °C. The fluid inclusion data presented here suggests that there has been ∼2.3 km of erosion at Qulong after its formation, and this erosion may be related to regional uplift of the Lhasa Terrane.

Aerogravity and remote sensing observations of an iron deposit in Gara Djebilet, southwestern Algeria

The Gara Djebilet iron ore region is one of the most important regions in Africa. Located in the southwestern part of Algeria at the border with Mauritania, the Gara Djebilet region is characterized by steep terrain, which makes this area not easily accessible. Due to these conditions, remote sensing techniques and geophysics are the best ways to map this iron ore. The Gara Djebilet formations are characterized by high iron content that is especially rich in hematite, chamosite and goethite. The high iron content causes an absorption band at 0.88 μm, which is referred to as band 5 in the Operational Land Imager (OLI) Landsat 8 images. In this study, we integrated geological data, aerogravity data, and remote sensing data for the purpose of mapping the distribution of the Gara Djebilet iron deposit.Several remote sensing treatments were applied to the Landsat 8 OLI image, such as color composites, band ratioing, principal component analysis and a mathematical index, which helped locate the surface distribution of the iron ore. The results from gravity gradient interpretation techniques, 2-D forward modeling and 3-D inversion of aerogravity data provided information about the 2-D and 3-D distribution of the iron deposit. The combination of remote sensing and gravity results help us evaluate the ore potential of Gara Djebilet. The estimated tonnage of the iron ore at Gara Djebilet is approximately 2.37 billion tonnes with 57% Fe.

Characterization of local geochemical anomalies in soils and stream sediments for improving land-use planning: A case study from Nisa, Portugal

One of the largest and most important near-surface deposits of uranium in Portugal is found in the region of Nisa. Unexploited resources in the Nisa deposit are estimated at about 32 million tonnes of ore. To better understand the processes of natural dispersion of chemicals, such as hydrogravitational erosion and reactive transport, samples of soils and of stream sediments were collected in the vicinity of the Nisa deposit and analysed for chemical signatures of metals (uranium, chromium, molybdenum, niobium, vanadium, and zinc) and semi-metals (arsenic). Stream sediment samples were taken from sites along a 470-m-long stretch of a river bed near the mineralization, with soil samples being collected from riverbanks. Univariate, bivariate, and multivariate statistical analysis as well as GIS mapping tools were used to identify and interpret variations in geochemical concentrations of the different elements and the relationships between them. The analyses allowed local background (reference) values to be established with respect to the geochemical anomaly caused by the mineral deposit. These background values were compared with legislation standards established for the remediation of soils and sediments. Recommendations to be considered in land-use planning with respect to the occurrence of natural geochemical anomalies are presented.

Measuring the specific land requirements of large-scale metal mines for iron, bauxite, copper, gold and silver

The amount of land directly disturbed by mining is a key generic environmental pressure indicator. A novel method based on the measurement of the cumulative net area disturbances using Landsat satellite images and its correlation with the cumulative ore production at the mine site was applied. Weighted disturbance rates (WDRs) were calculated indicating the annual quantity of hectares newly disturbed per million metric tons of ore extracted. Results show that open pit (OP) have a smaller average WDR (5.05 ha/Mt) than underground (UG) mines (11.85 ha/Mt). This is explained by the relation between the annual amounts of new net area disturbed and of ore extracted which is larger for UG than for OP mines due to the annual extraction volume (lower for UG). Overall findings demonstrate that bauxite mining has the highest WDR (7.98 ha/Mt), followed by gold (6.70 ha/Mt), silver (5.53 ha/Mt), copper (4.5 ha/Mt) and iron (4.25 ha/Mt).

Current methods and possibilities to determine the variability of Cu content in the copper ore on a conveyor belt in one of KGHM Polska Miedz S.A. mines

In this paper the methodology of ore sampling on a belt conveyor in one of KGHM Polska Miedz S.A. mines was presented together with the results of analysis of the variation of ore tonnage and quality. The ore was transferred from one mine to another one through the analysed transfer conveyor on the route from the mine Division of Mining to copper plants. The transported ore was sampled in person from Division of Concentrators on a regular basis for metal accounting purposes between both mines. The ore quality control became a significant problem since it is impossible to predict with satisfactory advance both Cu content in the feed as well as its lithology composition which is required to improve and optimise the enrichment efficiency.