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By W. Dan Hausel

"Hundreds of diamonds have been found in the United States. The majority of the discoveries occurred during the 19th century as a by-product of placer gold mining. Most of these early diamond finds have no known source, and in many cases are situated in areas unfavorable for diamond exploration based on current models that require kimberlite or lamproite to be emplaced in a stable Archean craton or Proterozoic craton margin.Diamonds have also been recovered in situ from lamproite at Murfreesburo, Arkansas, from kimberlite in the Lake Ellen region of Michigan, and in several kimberlites in the Colorado–Wyoming State Line district. Unverifed reports also suggest that diamonds may have been recovered from other related intrusions at a number of localities in the United States.IntroductionTo date, diamonds have been recovered in situ from kimberlite in the Colorado–Wyoming State Line district and from a kimberlite in Michigan. Additionally, diamonds have been recovered from lamproites in Arkansas. Diamonds have also been reported from kimberlite in Kansas, and from peridotite in New York and Maryland. However, these latter reports have not been verified."

Jan 1, 1995

By C. R. van Staal, L. R. Fyffe, J. A. Winchester

"The geochemical characteristics of Early Paleozoic volcanic rocks are used to establish the following tectono-volcanic regimes in the northeastern mainland Appalachians: foreland continental rift volcanics; fore-arc ophiolites; island-arc volcanics; back-arc ophiolites; and back-arc ensialic volcanics. A Late Precambrian calc-alkaline magmatic arc bounds the Early Paleozoic volcanics to the southeast.The Precambrian calc-alkaline volcanics of the Caledonian Highlands, primitive Cambro-Ordovician oceanic-arc volcanics of the Eastern Townships, and within-plate Ordovician volcanics of the Miramichi Highlands can be related to a progressive change in mode of subduction from compressional Andean-type in the Late Proterozoic to extensional Western Pacific-type in the Early Paleozoic. The development of marginal oceanic basins in the Paleozoic created a more favourable environment for volcanogenic sulphide deposition, particularly in back-arc areas.The influence of tectonic setting is reflected in the distribution, size and metal ratios of the massive sulphide deposits associated with the volcanic rocks; deposits within intra-oceanic arcs in the Eastern Townships of Quebec average two million tonnes grading 2.2% Cu, 4.0% Zn, and 0.6% Pb, whereas those within a back-arc, ensialic rift near Bathurst, New Brunswick, average nine million tonnes grading 0.6% Cu, 5.4% Zn, and 2.2% Pb."

Jan 1, 1990

"Abstract - An estimation of resources of structurally complex gold lodes and stockworks represents a challenging task for geoscientists due to the complex geometry of the lodes and discontinuous grade. In the present case study, the resource of a gold stockwork has been estimated by uniform conditioning after the lode has been subdivided into geostatistically defined domains using the indicator probability model. The indicator probability model represents a powerful tool for structural interpretation of the mineralization and can be applied when traditional 3D volume constraining methods (wireframing) have failed to produce a unique, non-subjective model. For comparison, the resources of the same zone have been estimated without domaining. Results of the study clearly show that estimates obtained without domaining of the mineralization can yield a substantial error due to excessive smoothing of the grade.Application of uniform conditioning for modelling the grade distribution has a significant advantage over linear methods (e.g., ordinary kriging). Uniform conditioning enables estimation of local recoverable resources at different selective mining unit sizes that can be substantially smaller than the drilling density without creation of biases or over smoothed local values."

Jan 1, 2002

By D. R. Nagaraj, Napoleon Tercero, Raymond Farinato

"Several studies conducted recently have shown that molybdenite flotation from Cu-Mo ores is adversely impacted in sea water at pH >~ 10.0 irrespective of the pH modifier; under the same conditions Cu sulfide flotation is relatively unaffected. This has been attributed to the presence of Mg2+ ions and their hydrolysis products in the sea water which adsorb and precipitate on molybdenite surfaces as Mg(OH)2. However, why and how Mg(OH)2 impacts only molybdenite flotation in the complex flotation pulps containing a multitude of minerals is not understood. The work presented in this paper probes the interface and interphase regions near the edge and basal planes of natural molybdenite (MoS2) in aqueous solutions and flotation pulps, particularly in the presence of copper ore pulp and added Mg2+. Differences in interaction of metal ions and their hydrolysis products (Mg2+, Mg(OH)+) were measured on the two faces of this anisotropic mineral. How those differences relate to molybdenite floatability and the impact of aqueous solution chemistry are discussed.INTRODUCTIONWater resource management is an important sustainability challenge in mineral processing. In view of the shortage of fresh water in many parts of the world, mineral processing plants are evaluating alternative sources. Seawater flotation has received much attention recently and there have been several important studies reported in the literature, particularly for the processing of Cu-Mo ores (S. Castro, 2012; S. Castro, Rioseco & Laskowski, 2012; S. Castro et al., 2012; Laskowski & Castro, 2012; Ramos, Castro & Laskowski, 2013; S. Castro & Laskowski, 2013; Laskowski, Castro & Ramos, 2013; Nagaraj & Farinato, 2014; S. Castro, Uribe, & Laskowski, 2014; Veki, 2013). The main conclusions from these studies on Cu-Mo ores in seawater at elevated pH were: a) flotation recovery of Cu sulfides is either unaffected or only marginally reduced, b) molybdenite recovery is adversely affected in seawater at pH values necessary for rejecting pyrite (i.e. pH > 10 to 10.8 depending upon particular system), and c) the precipitation of Mg2+ in seawater as Mg(OH)2 is responsible for the adverse effect on Mo flotation. In order to further investigate the individual effects of Mg2+ and Ca2+ on molybdenite depression in Cu-Mo ore flotation, Nagaraj & Farinato (2014) conducted flotation tests wherein individual metal ions were spiked into tap water during grinding of Cu-Mo ores. They showed the strong adverse effect of Mg2+ addition on Mo recovery and, to a lesser extent, on Cu recovery when pH > 9.5. Under similar conditions, Ca2+ had virtually no effect on either Cu or Mo sulfide flotation. Figure 1 below shows the previous results for Cu- Mo ores in tap water and the effect of addition of Ca2+ and Mg2+ ions. Note that in seawater the adverse effect of Mg2+ on Cu recovery was much smaller than that in tap water (Nagaraj & Farinato, 2014; Figure 4a and 4b and Table 4 therein)."

Jan 1, 2016

By R. I. Grauch, Michael D. Glascock, Chen Nansheng, Jr Coveney, James B. Murowchick

"Unusually rich molybdenum ores (cutoff grade = 4.10/0 Mo) hosted by Lower Cambrian black shales have been mined since 1985 near Zunyi in the province of Guizhou in China. Similar ores were once worked for Mo and Ni near Dayong in the province of Hunan. In both mining areas, mineralization occurs in Lower Cambrian black shale (Niutitang Formation and stratigraphic equivalents) as a single sulfide bed or lens with exposed thicknesses up to 15 cm and reported thicknesses up to 35 cm. In addition to high Mo values (4% to 7%), ore samples contain up to 7% Ni, 2% Zn, 2.5% As, and several hundred ppb Au and Pt-group elements, but the precious metals have never been recovered from the ores. Sporadic occurrences of Mo-Ni sulfide ore beds are found in at least five provinces stretching approximately 1600 Ian from Yunnan to Zhejiang. None of the Mo-Ni ore-bed occurrences has any obvious connection with mafic or ultramafic source rocks. Similar occurrences containing elevated values for Ni, Mo, and PGE exist in Devonian black shale in the Yukon. Future exploration for Pt, Au, Mo, and Ni deposits should consider this previously unknown type of sediment-hosted mineral deposit.Sommaire - Des minerais anormalement riches en molybdène (teneur-limite = 4.1% Mo) provenant de schistes argileux noirs du Cambrien Inferieur ont été exploites depuis 1985 près de Zunyi dans la province de Guizhou en Chine. Des minerais semblables ont déjà été traire pour Mo et Ni près de Dayong dans la province de Hunan. Dans ces deux régions minières, la minéralisation se présente dans le schiste argileux noir du Cambrien Inferieur (Formation Niutitang et équivalents stratigraphiques) sous forme de couche ou lentille unique de sulfures avec des épaisseurs exposées de plus de 15 cm et des épaisseurs rapport6es de plus de 35 cm. En plus des fortes teneurs en Mo (4%-7%), des échantillons du minerai contiennent jusqu’ à 7% de Ni, 2% de Zn, 2.5% d'As, et plusieurs centaines de ppb d'or et d'éléments du groupe du platine; toutefois, les métaux précieux n'ont jamais été récupérés des minerais. Des présences sporadiques sous forme de couches de minerai sulfure de Mo-Ni se retrouvent dans pas moins de cinq provinces s'etendant sur 1600 km de Yunnan a Zhijiang. Aucune de ces présences de minerais, sous forme de couches, ne semble associée a des roches du type mafique ou ultramafique. Des présences similaires contenant des teneurs élevées en Ni, Mo et EOP se retrouvent dans le schiste argileux noir Devonien du Yukon. L'exploration future pour des gisements de Pt, Au, Mo et Ni doit prendre en considération ce type de gisement encore inconnu précédemment."

Jan 1, 1992

By L. A. M. Castro

As Canadian mines progress to greater depths, magnitudes of induced stresses increase, becoming high enough to cause rock mass damage and failure during excavation. In addition, depending on the orientation of key geological structures in relation to the in-situ stresses, induced shear loading can be developed on these structures, creating the potential for: a) remobilization of existing geological structures, b) formation of new seismically active structural zones, created through rock mass damage and coalescence along such structural zones, and/or c) interaction between existing and newly created structures. Numerical analyses were carried out to investigate four possible factors that might cause fault slip on controlling structures, namely: (a) unclamping, (b) day-lighting, (c) stress rotation and (d) pillar shear. Application to an underground mine in the Sudbury Basin allowed verification of these factors and the proposal of two alternative mine planning methods to limit fault slip on key structures: (1) pillar clamping and (2) stope sequencing.

May 1, 2009

By João Felipe Costa, Jair Carlos Koppe, André C. Zingano

Abstract - Traditional mine planning based on block models built with interpolation techniques such as kriging does not take into account the uncertainty associated with the estimates. These models are inadequate for short-range mine planning. In contrast, conditionally simulated models reproduce the actual variability (histogram) and spatial continuity (variogram) of the attributes of interest. Conditional simulation can be used to address the problem of measuring the uncertainty associated with an estimate. This paper outlines how the sequential Gaussian conditional simulation algorithm can be used to assess uncertainty of grade estimates and also illustrates how simulated models can be incorporated into mine planning and scheduling. A case study demonstrates the efficiency of the method in assessing risk associated with geological and engineering variables.

Jan 1, 2000

By I. Cifuentes

Chemical and physical characterization of copper electrodeposits obtained on mesh and plate cathodes in conventional and reactive electrodialysis lab-scale cells have been carried out. The effect of Fe, Mn, Cl and guar on electrodeposit composition and morphology were determined by means of metallographies, scanning electron microscopy (SEM), atomic force microscopy (AFM), inductively coupled plasma mass spectrometry (ICP-MS) and Auger electron spectroscopy (AES). Each impurity influenced the deposit morphology in a different way (e. g. grain size, surface roughness). AFM proved to be a very effective tool for quantifiying and classifiying surface quality.

Jan 1, 2007

By Rodrigo Madariaga, Tracy T. Morris

The practice of stripping copper starter sheets from titanium blanks to be used in a conventional electrolytic tankhouse has been around since the advent of Electrometallurgy. Historically it has been done manually, utilizing many people to produce in some cases thousands of starter sheets per day. Some other conventional tankhouses have successfully converted to using mechanical means to strip starter sheets or have made the switch to permanent cathodes and although robotics have been around for quite some time they have not been used to strip starter sheets until recently. The Amarillo Copper Refinery began using robotics to strip several years ago and the details to how this came about and how the robots work will be described. INTRODUCTION ASARCO LLC (Asarco) was organized in 1899 as the American Smelting and Refining Company. Originally a consolidation of several lead-silver smelting companies, it evolved over the years into an integrated producer of primary non-ferrous metals, including copper, lead and zinc and associated co- products (Marcosson, 1949). Grupo México, S.A.B. de C.V acquired Asarco in 1999. Today, Asarco is a vertically integrated producer of primary refined copper and associated co-products such as gold, silver, molybdenum, selenium and tellurium. Asarco operates three open-pit mines and mills and two solvent extraction-electrowinning (SX-EW) plants all in Arizona plus a copper smelter in Arizona and a copper refinery in Texas. Figure 1 illustrates how the copper metal comes out of the ground at the mine and ends up as a refined product at the refinery The copper refinery in Texas is known as the Amarillo Copper Refinery (ACR) and is located in Amarillo, Texas. It was built in 1975 to replace 3 other aging refineries and was designed to produce 550,000 tons (500,000 MT) of refined copper per year using conventional starter sheet technology. At the time it was commissioned it was the largest tankhouse in the world at just under 1/2 miles long under one roof.

Jan 1, 2019

By Kadir Sariiz

Abstract - The Akçayir-Yürükakçayir Miocene-Pliocene basin in the Central Anatolia hosts ancient lacustrine sepiolite deposits. The succession in this basin consists of conglomerate (Yürükakçayir conglomerate), clayey and silty limestone, dolomitic marl, sepiolite beds and lenses, and dolomitic limestone (Kepeztepe formation). The main impurities within the sepiolite rock are dolomite, opal-CT, calcite, smectite and feldspar as sepiolite + dolomite and sepiolite + opal-CT are the main mineral assemblages. Smectite and feldspar are thought to be of detrital origin. Calcite is found as a secondary filling in root tubes and casts. Sepiolite samples studied display root-marks and root tubes, soapy and massive structure indicating direct precipitation. Sepiolite deposits probably formed at a pH of 8 to 9, and Mg+2 and SiO2 concentrations in moderately saline environments of internal facies of an alkaline lake.

Jan 1, 2000

By J. Severin

Surface mining operations are increasingly involving the design and development of deeper and larger open pits, often with plans to transition into underground mass mining operations. Experiences at the Palabora Mine in South Africa demonstrate the complex interactions between underground workings and the steep slopes above that may lead to slope movements that potentially pose safety and economic concerns. To properly assess the rock mass response to these interactions for planning of future developments, understanding the controlling influence of geological and geomechanical structures is crucial. Preliminary results are presented from a detailed review of historical slope monitoring data from the Palabora Mine, before and after the initiation of block caving 400-m beneath a 800-m deep pit. This paper demonstrates that a detailed analysis of geology and monitoring data can be used to better understand the kinematic controls of complex rock slope displacements and interactions between open pits and underground mines. This investigative treatment of the monitoring data is important in understanding the failure mechanisms prior to undertaking sophisticated 3-D numerical models.

May 1, 2009

By Roger Lacroix

Presentation outline Project definition Characterization of mine ventilation systems Strategies in place and results Detailed study (2 mines) Other potential energy savings Conclusions Next steps

Feb 1, 2008

By Margarete Kalin

Mine Waste Management ?Reduction of Sulphideoxidation or inhibiting weathering of rocks Geologist - broken or ground rocks Hydrologist - sources of contaminants Mining engineer - waste sites Consulting companies - income units People - Ugly, bad, dead Ecological Engineer Landscapes which contain building blocks of an emerging ecosyste

May 1, 2013

By P. E. Weidmark

"PART 1-Published PapersAllcott, G.A., and Archibald, D.E.; ""Description of pillar behaviour at Heath Steele Mines""; Can Min Metall Bull; 74:834:80-87; 1981.Baar, C.A.; Discussion of Theme 1: ""Physical properties of intact rock and rock masses""; Proceedings 3rd Congress Intnl Soc of rock Mechanics; 3:32-33; 1979.Baar, C.A.; Discussion of Theme 1: ""Physical properties of intact rock and rock masses""; Proceedings 3rd Congress Intnl Soc of Rock Mechanics; 3:37-38; 1979.Baar, C.A.; Discussion of Theme 1: ""Physical properties of intact rock and rock masses""; Proceedings 3rd Congress Intnl Soc of Rock Mechanics; 3:38; 1979.Baar, C.A.; Discussion of Theme 1: ""Physical properties of intact rock and rock masses"" ; Proceedings 3rd Congress Intnl Soc of Rock Mechanics; 3:41; 1979.Baar, C.A.; Discussion of Theme 1: ""Physical properties of intact rock and rock masses""; Proceedings 3rd Congress Intnl Soc of Rock Mechanics; 3:42; 1979.Baar, C.A.; Discussion of Theme 1: ""Physical properties of intact rock and rock masses""; Proceedings 3rd Congress Intnl Soc of Rock Mechanics; 3:46; 1979.Baar, C.A.; Discussion of Theme 2: ""Tectonophysics""; Proceedings 3rd Congress Intnl Soc of Rock Mechanics; 3:60; 1979.Baar, C.A.; Discussion of Theme 4: ""Underground openings""; Proceedings 3rd Congress Intnl Soc of Rock Mechanics; 3: 116; 1979.Baar, C.A.; Discussion of Theme 4: ""Underground openings""; Proceedings 3rd Congress Intnl Soc of Rock Mechanics; 3:116-117; 1979.Baar, C.A.; Discussion of Theme 4: ""Underground openings""; Proceedings 3rd Congress Intnl Soc of Rock Mechanics; 3:117; 1979.Baar, C.A. '; Discussion of Theme 4: ""Underground openings""; Proceedings 3rd Congress Intnl Soc of Rock Mechanics; 3:118-119; 1979.Baar, C.A.; Discussions (2) of Theme 4: ""Underground openings""; Proceedings 3rd Congress lntnl Soc of Rock Mechanics; 3:119; 1979.Baar, C.A.; Discussion of Theme 4: ""Underground openings""; Proceedings 3rd Congress Intnl Soc of Rock Mechanics; 3:120-121; 1979."

Jan 1, 1982

By R. F. Tylecote

"The closure of the iron and steel making plant at Consett in Durham in 1980 marked the end of an era-a long era in the world's iron and steel making history. Iron had been smelted in the Tyne-Wear area of the United Kingdom since before the Roman period, but apart from evidence of smithing in the Roman period, the historical evidence for iron production on a large scale dates from the 14th century.The paper describes sites in the area that first worked the bloomery process and then, in the 16th century, as did most of Europe, graduated to the blast furnace process. The main emphasis is on the early introduction of coal to iron making at the end of the 18th century and the use of the steam engine to render integrated sites possible.IntroductionIron has been smelted in the Tyne-Wear area of the United Kingdom since before the Roman period, but apart from clear evidence of smithing in the Roman period, the historical evidence for iron production on a large scale dates from the 14th century. Like many other countries, the United Kingdom benefitted from the visits of foreign observers, such as Jars, Svedenstierna, de la Houliere and Dufrenoy, who left detailed records. In modern times, information gained from excavations of iron and steel making sites has supplemented the historical record.Natural ResourcesUp to the end of the 19th century, the industry was wholly dependent on its own resources. Iron ore, limestone, wood, coal and water power were all found a short distance away from the main valleys of the Tyne and Wear. The main sources of iron ore were the coal measures, with rider ores from the lead vein s in Alston and Weardale, and carbonate ores from shale horizons in the Carboniferous limestone. Good coking coal was available from West Durham and reasonable coal from the Tyne valley and Northumberland limestone. Limestone was plentiful."

Jan 1, 1983

By Theophile Yameogo

Much has been said about the methodology of geomechanical design in underground excavations. However, the geological, hydrogeological and geotechnical complexities encountered at the production horizons in the Athabasca Basin commanded for a novel approach in the geomechanical assessment and design of underground openings. Rock mechanics engineers at Cameco McArthur River have been able to establish a practical methodology that goes beyond known conceptual approaches. In this paper, the author describes the original challenges and unique approach in the geomechanical assessment for drifts and chambers development. The example of the successful development of the 510-8225N Chamber will also be presented.

Aug 1, 2010

By M. Kalin

Tailings deposits are frequently the source of ground water contamination due to the transport of contaminated tailings pore-water. If amendments to tailings covers could be made to facilitate a precipitation reaction and halt or reduce the generation of acid in pyritic tailings, the quality of pore-water quality would be improved which would in turn reduce the production of contaminants. The effects of phosphate wastes, added to base-metal mine tailings in Newfoundland, Canada, were tested. Laboratory and field experiments determined the effects of different mixing ratios of phosphate wastes to tailings volume (1:4, 1:8, 1:12 and 1:20, dry weight) for a total period of 3.2 years. The addition of phosphate at ratios of 1:4 to 1:12 substantially increased the pore water pH, and reduced both acidity and Zn concentrations. These results suggest that addition of phosphate wastes to tailings covers can reduce acidity generation and improve tailings pore-water quality.

Jan 1, 2004

By B. Huffman

This paper examines several new trends in the design and application of linings for copper melting shaft furnaces including the use of large shapes, monolithic back-up linings and improved refractory engineering to significantly reduce refractory installation time, diamond saw blade costs, fuel and down-time. The net results are shown to be dramatically increased refractory service life, reusable safety linings, elimination of hot spots and lower refractory disposal costs.

Jan 1, 2007

By Kathy Pomeroy

Sharing?? l Maybe not the first image that comes to mind when we think about the historical corporate mind set and track record of many corporations ? ! A Fundamental Change in Relationships l From a worldview of independence to one of recognized interdependence l Collaborative action with communities for long range mutual goals l Acceptance of greater accountability for the whole l Community and government relationships based on trust, mutuality, respect for human rights, equity, sustainable agreements

May 1, 2002

Orebody classification systems ? Modern classification systems ? Genesis and environment of deposition (Important in economic geology) ? Shape and structure / Form, texture and mineral content ? Mining and geomechanics ? Size ? Massive versus tabular Requirements for mining method selection ? Classification of ore deposit ? Shape, size, attitude, continuity ? Grade and distribution, strength and large scale structures present, mineralogy and small scale structure, host rocks ? Classification of mining method ? Method of support (Stress ? strength ratio) ? The method selection ? Geographical and economic factors of the location

Feb 1, 2008