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By Fazel G. Jahromi, Ahmad Ghahreman

"Several studies were performed on the atmospheric leaching of copper sulfide minerals in the presence of activated carbon and a new catalyst, AF 5. AF 5 is a carbon based catalyst with similar properties to those of activated carbon however much better mechanical properties. The activated carbon surface chemistry has been investigated in various studies; however the connection of the surface chemistry of activated carbon and AF 5 with the sulfide minerals during the atmospheric leaching process is not well-understood yet. Based on the surface analysis, AF 5 showed higher surface area than activated carbon (AC). Adsorption and oxidation of copper, arsenic and iron ions in the presence of different activated carbon were investigated. Adsorption properties of both catalysts were similar and 18-24% of iron, 12-18% of copper and 10% of arsenic adsorbed on the catalysts surface form 5 g/L Fe(III) and Cu(II) and 2 g/L As(III) at 80°C. In oxidation experiments, both catalysts reduced Fe(III) and Cu(II) ions and re-oxidized the reduced species in the presence of oxygen and oxidized As(III) ions. The addition of oxidizing ions can enhance the oxidation process kinetics and increase the catalytic capability of carbon.INTRODUCTION Hydrometallurgical processes of copper sulfide concentrates are under development and various different methods have been proposed to increase the atmospheric leaching rate of copper sulfide minerals. These methods include using different media, reagents, and catalysts. Among different methods, leaching of the copper sulfide minerals in the chloride media has some advantages over sulfate media. Smaller scale of operation, increased leaching rates, and lower sulfate formation are some of the benefits of the chloride leaching media over other similar media. Moreover, using ferric and cupric ions as oxidants and utilizing activated carbon as a catalyst has been proven to enhance the leaching rate of copper sulfide minerals effectively. Activated carbon (AC) and AF 5 (micro porous carbon based catalyst) are two of the most efficient and practical catalysts in copper sulfide leaching processes. AC can enhance the copper recovery of enargite in chloride media from 69% to 92% after 96 hours of leaching under the similar conditions (Jahromi & Ghahreman, 2016). It has been shown that AC at acidic pH can generate hydrogen peroxide in the presence of oxygen which can leach copper minerals (Ahmumada et al., 2002)."

Jan 1, 2017

By Y. Béliveau

Emission of perfluorocarbon gases, CF4 and C2F6, produced during anode effects from aluminum electrolytic cells are a significant part of the total equivalent CO2 emitted by aluminum plants. With the current concerns about global warming, the reduction of these PFC gases is a key issue in reducing greenhouse gases for a smelter and achieving GHG emission agreement goals. This paper will present the approach taken by the Alcoa vertical-stud Soderberg plant in Baie-Comeau to reduce GHG emissions generated during anode effects and close emission gaps with other Alcoa Soderberg plants. The approach has been to adapt the existing technology in place at the Baie-Comeau Soderberg plant. PFC emissions were lowered by reducing both the anode effect duration and frequency through different methods. Examples of change include: implementing skimming practices and wider side crust break area for better alumina dissolution in bath, increasing the ratio between reacted and pure alumina, reducing the time to declare anode effects in the potrooms, implementing best work practices and finally educating the workforce on the importance of reducing PFC emissions.

Jan 1, 2007

By E. A. Hart, J. E. Gill

"The property of Arntfield Mining Corporation, formerly Arntfield Gold Mines, Limited, covers an area of 2,110 acres and lies in Beauchastel township, western Quebec. The Francoeur mine lies to the west, and to the east are the West Wasa and Wasa Lake properties.The property was staked in September, 1923, by the late F. S. Arntfield. The early surface work was concentrated in the west part of the property along the Francoeur-Arntfield shear zone. The zone was opened by No. 1 shaft, which was sunk for an inclined depth of 250 feet. A series of silicified lenses were discovered farther east, where No. 2 shaft was later raised to the surface. A third shaft explored a shear zone about 1,900 feet to the east, where No. 3 shaft orebodies were developed.The mill was built at No. 3 shaft and production commenced in July, 1935, at 125 tons a day. This was increased to 280 tons by 1938, and later to 350 tons. The mine continued operations on this scale until April, 1942, when the exigencies of war necessitated closing. The Company was reorganized in 1944 and underground development was resumed in June, 1945. The total value of gold and silver produced to April, 1942, was $2,011, 755 from 529,987 tons of ore.ROCK TYPESThe area is underlain by highly deformed and altered Keewatin volcanics overlain by little deformed Cobalt sediments along the south boundary. The lavas in the vicinity of the mine workings are rhyolite, trachyte, andesite, and a flow breccia of intermediate composition. The fragmentals range from fine, well-bedded tuffs to coarse agglomerate in which acidic and basic horizons can be distinguished.The intrusive rocks are diorite and quartz-feldspar porphyry in the form of stock and sills, and narrow dykes of mica lamprophyre and syenite porphyry."

Jan 1, 1954

By T. Winkler

This paper presents elements of the Virtual Working Environment for identification of hazards occurring in the mining industry. The Virtual Working Environment includes models of machinery and models of anthropometric features. Examples are given for identification of technical hazards at the design stage using the following computer programs: Finite Elements Method, Multibody System Analysis and Human Body Modeling. One of the methods to improve work safety at the machine and equipment maintenance stage is to share design and operational knowledge in a form of an Interactive Electronic Technical Manual (IETM). An IETM is created using so-called reusable knowledge elements connected by relationships. A metamodel created in Unified Modeling Language is one of the forms for description of these relationships. The metamodel can represent, for example, interrelations between elements of repair procedures. Examples of procedures realized during the replacement of a damaged cutting bit are presented and discussed.

Aug 1, 2013

By Carol Odell

This paper was prepared as a brief for Prospectors and Developers Association of Canada (PDAC) to guide input at a series of round tables carried out by the Federal Government in response to the 38th Standing Committee on Foreign Affairs and International Trade (SCFAIT) report, on ?Mining in Developing Countries and Corporate Social Responsibility?. This document mandate is to provide background information, analysis and recommendations on the practice of Canadian exploration and mining companies abroad. This research was based on 11 case studies of Canadian companies which have experienced conflicts or controversies overseas. All case studies were assembled through an extensive literature review of publicly available documentation and communications with representatives of the mining companies to assist in deepening the insights into the drivers of the conflicts and the needs of Canadian companies in similar situations. The case studies include both exploration and mining operations. Our analysis begins with the identification of general and case specific drivers of conflict/controversy in each case study. Company names are kept confidential and only anonymous results are presented. We make ample use of simple flow charts and schematic diagrams to explain how contextual drivers and aggravators and company drivers and mitigators play varied and interrelated roles in conflicts. The diagrams also illustrate the cumulative analysis of drivers including the linkages among drivers/aggravators/mitigators across different domains (social, governance, NGO/media and company). Finally, we discuss needs of companies and propose recommendations for addressing social responsibility and human rights concerns.

May 1, 2007

By J. Mirza, E. Nicol, J. Lipkowski

Gold passivation in thiosulfate leaching media is a major barrier to its implementation. Addition of Cu (II) into the leaching solution has shown to aid in gold dissolution, but the mechanism by which it acts, and its role in the passive layer, remains unknown. Surface Enhanced Raman Spectroscopy (SERS), in tandem with linear sweep voltammetry, were employed to determine the dependence of leaching currents on mass transport and for fingerprint identification of sulfur species on the surface of gold. SERS leaching experiments were performed using gold nanorod electrodes that showed increased stability compared to other SERS active surfaces.

Jan 1, 2011

By J. B. Boisvert, P. Oshust

A significant source of uncertainty in the diamond resource contained in kimberlite pipes is the volume of the pipes. Often the material within a pipe will be mined as ore, leaving the actual geometry of the pipe as a significant source of uncertainty. It is desirable to use stochastic techniques, rather than deterministic methods, to model pipe geometry because stochastic techniques generate multiple realizations that are reproducible and can be used to assess uncertainty in pipe geometry. The proposed methodology uses sequential Gaussian simulation of pierce point locations interpreted from drillholes through a kimberlite pipe. Kimberlite pipes are approximately cylindrical in shape; therefore, the data are transformed to cylindrical coordinates to facilitate the simulation of pipe geometry. Rather than using xyz coordinates to define the pierce points, z, ??and pipe radius are used. The radius variable can be simulated in z-??space to generate multiple realizations of pipe volume. Uncertainty in the volume of the pipe can then be evaluated. This methodology is demonstrated with a kimberlite pipe at BHP Billiton’s Ekati diamond mine.

Jan 1, 2008

By T. K. Bose

According to the Intergovernmental Panel on Climate Change (IPCC), the average global temperature has risen over the last century. If this trend continues over the next century, the IPCC projects a significant increase in temperature and a rise in sea level. The changes in climate could adversely impact human health, agriculture, water resources and ecosystems. Most national and international agencies have concluded that our use of carbon-rich fuel is responsible for global warming through the greenhouse effect. In the future, the situation may get worse if the increased need for energy in countries like China, India and Brazil is fulfilled by burning fossil fuel. Advanced natural gas-fuelled vehicles have the potential to reduce carbon monoxide and reactive hydrocarbon emissions substantially compared to gasoline vehicles. Further environmental benefits can be realized by using a blend of natural gas and hydrogen. Such an approach will help create an infrastructure for an eventual transition to hydrogen.

Jan 1, 2005

By John D. Campbell

Alberta Plains coals exhibit an almost rectilinear system of vertical fracturing called "cleat", which is best traced by mapping true bearings of underground coal mine rooms. The cleat pattern is approximately conformable with a pattern of surficial features and a pattern of bedrock jointing in the Alberta Plains, and with the trend of the Rocky Mountain Trench, but not with the distribution pattern of coal rank nor with the trend of the eastern boundary of the Rocky Mountains and Foothills physiographic province. The processes resulting in cleat remain in doubt, but cleat is always of practical importance in extracting coal from deeply buried deposits.

Jan 1, 1979

By R. D. Brown

The Federal Government's White Paper on Tax Reform received further major criticism in the reports of the Committees of the House of Commons and the Senate, which recently completed a lengthy review including public hearings of the government's proposals. These reports both criticized the emphasis placed by the White Paper on its concept of tax equity rather than on a system which would promote economic growth. However, the Finance Committee of the House of Commons was prepared to accept, with modifications, a number of the White Paper's key reform proposals. The Senate Finance Committee was more critical of the basic thrust of the tax reform program and recommended that a modification of the existing tax system would be more appropriate to Canada's needs. Both Committees re-commended a more favourable treatment of mining income than that originally proposed in the White Paper, and to some extent both Committees suggested proposals that were even more favourable to the industry than those set out in Finance Minister Benson's amended proposals made in August of this year. This article out-lines the principal recommendations and comments in the reports of both the House of Commons Committee and the Senate Finance Committee.

Jan 1, 1971

By José J. Suárez

As pressure grows for commodity pricing, new mines are more difficult to develop, the stock markets demand better financial returns from mining companies, resources for the developing and operations are scarce, and developing countries in Asia, and Africa demand more metals, it is important that mining companies effect better utilization of capital to develop capital projects. In the last few years, the costs for Capital projects have been impacted by the following factors:

May 1, 2013

By B. Goard

"IntroductionCemented backfill has been placed underground in slurry form in Inco Limited's Ontario Division mines since the early 196Os. The slurry was traditionally mixed on surface at between 65 and 70 wt% solids* and transported underground via gravity through a borehole-pipeline distribution system. This method of placement, while simple and dependable, has proven to be costly because of the large amounts of transport water involved.A significant quantity of the slimes buildup on mine levels is caused by the backfill water carrying cement and other fine material out of the stopes. The level cleanup and eventual pumping or hoisting of the slimes and water back to surface result in substantial indirect backfilling costs.The cement that remains in the stope is always overhydrated because of the high water cement ratios that exist. As a consequence, high concentrations of Portland cement must be added to the backfill to produce the fill strengths required for the different mining methods.Pouring backfill at these densities also demands extensive fill preparatory work in the stopes to withstand the hydraulic heads created by the slurried fill. This, along with the delays in pouring necessary to allow for water drainage, result in significant losses in productivity.These negative aspects of slurry placed fill has led Inco Limited to investigate several methods of transporting backfill underground via pipeline, at higher densities (i.e. 75 to 95 wt.% solids). Three separate transport methods are presently being experimented with by the Company's Mines Research Department. Each utilizes a different technique or form of flow transport, i.e. concrete pumping technology, high density slurry flow, and pneumatic conveying."

Jan 1, 1987

RISKGATE is an interactive online risk management system developed by the Minerals Industry Safety and Health Centre (MISHC; University of Queensland) to assist the mining industry in implementing continual improvement in management of major unwanted events so maximising health and safety performance. A comprehensive body of knowledge has been compiled from diverse mining industry experts for risk management of tyres, collisions, fires, isolation, strata underground, ground control open cut, explosions, explosives, manual tasks and slips/trips/falls. This paper presents an overview of the RISKGATE body of knowledge captured specifically for the management of unwanted events that stem from the handling and use of explosives (drill and blast) within surface coal mining operations. The knowledge presented is divided into a series of initiating events (listed below) within which there are further degrees of classification based on design, operation, and management concerns. Initiating events: ? Loss of control of explosives and associated chemicals in storage on site ? Loss of control of explosives and associated chemicals during transport ? Loss of control of explosives and associated chemicals during manufacture ? Loss of control of explosives and associated chemicals during handling and blast operations ? Loss of control of explosives and associated chemicals during disposal The system guides the user in generating substantive and leading-edge controls to assist in the design, management and reporting of drill and blast operations to meet stringent internal and external requirements. From a broader industry perspective, RISKGATE provides an environment for knowledge capture and knowledge exchange to drive innovation and best practice in the identification, assessment and management of risk. By capturing operational knowledge from industry experts, RISKGATE provides a cumulative corporate memory at a time of high personnel turnover in the coal industry.

Aug 1, 2013

By D. Fodor

In Romania, there are significant lignite and brown coal reserves hosted by different regions of the country. The most important lignite bearing zone of the country situated in the North ? West part of Oltenia region and which covers a surface area of 2,500 km2 and host a total reserve of 3.0 billion tons of lignite, of which more than 95% can be exploited by open cast method. The paper deals with the existing geological and mining conditions of the zone , the distribution by mining basins and exploitation perimeters, the open cast working technologies and the economic outcomes obtained throughout the time. Years ago, for the improvement of the economic situation as a whole and in each unit, a large production reorganization, technology update and modernization process was started up. There are described the rehabilitation measures of the technological lines and modernization of the equipments of the production flow-sheet, measures developed at present, too and which will still continue in future. There are mentioned the equipments considered, the components under modernization and the economic outcomes obtained so far. At the end of the paper there are presented the future actions for the equipment modernization and perspectives of the lignite deposit exploitation to meet the national economy requirements of solid fuels.

Aug 1, 2013

By Lachezar Tsotsorkov

Being a mining company, Assarel-Medet has a significant impact upon the environmental components. In order to meet the legal requirements and the requirements stipulated by the effective permits as well as to reduce the environmental imprint throughout the years, the policy of the company to implement a number of projects to improve the environmental components quality and the environmental state in the company?s region. The projects associated with atmospheric air quality management and reduction of the impact exercised by Assarel-Medet JSC by implementing various measures to eliminate the potential sources of the impact, preventive and rehabilitation initiatives as well as organizational and administrative activities are among the most important ones. A stable improvement of atmospheric air quality in the region and minimization of the company impact upon the ground air state in the region was observed in the period from 2005 to 2012 due to the applied measures. This project is a contribution to the environmental protection, in particular to atmospheric air protection, by applying integral monitoring and modeling methods to identify the negative impact by the mining companies and plan measures to reduce and restrict it as well as to improve the quality of the environment and living area of people working and living in the impact range as an element of sustainable development.

Aug 1, 2013

By K. E. Waters, M. Mirnezami, R. Gauvin, A. Jordens, K. W. Malas

"There is currently very little information on the physico-chemical properties of rare earth elementbearing minerals, or on their processing. With the increasing demand for rare earths, this is something that needs to be addressed. This paper introduces some surface chemistry analysis of fergusonite (YNbO4), and the bubble-particle attachment. Zeta potential measurements indicate adsorption of sodium oleate and, to a lesser degree, potassium amyl xanthate onto the surface, and an increase in attachment to an air bubble is observed at pH 4.5 and 6.5. At a pH of 10.5, no attachment is observed, whether in the presence of the reagents or not. This analysis, although initial, will be used to initiate flotation tests, in order to facilitate the selective recovery of fergusonite. INTRODUCTIONRare earth elements (REE) are increasingly in demand, due to their prevalence in both renewable energy devices and high-end electronics. An article in the New Scientist highlighted the importance of a number of REE, many of which most people are be unlikely to have heard mentioned (Crow, 2011). From batteries (lanthanum and cerium) to magnets (dysprosium and neodymium) and lighting (yttrium), the REE are crucial to the advancement of technology and energy saving devices. For example, neodymium is finding most use in the high end magnets that keep the motors turning that power wind turbines and electric cars. In the case of yttrium, the demand outstripped the supply in 2010, emphasising the need to develop deposits containing this and other REE (Crow, 2011). The impact of our dependency on REE has become even more apparent with the reduction in exports by China, which currently controls 97 % of the world’s rare earth production (Pitts, 2011).With the increasing demand for rare earth elements (REE), there is a drive to exploit the known resources around the world. However, the physical beneficiation of the rare earth element bearing minerals is a subject which will require a great deal of investigation to fill the knowledge gaps surrounding these developing rare earth projects. There are numerous articles on REE mineralogy as well as the hydrometallurgical processing of REE concentrates (Alex, Suri, & Gupta, 1998; Peter Gromet & Silver, 1983; Ring et al., 1993; Schnetzler & Philpotts, 1970; Uda, 2000), however a common feature amongst these resources is the lack of detailed descriptions of the physical beneficiation processes required to concentrate REE-bearing minerals. There is work being conducted into reagents and methods for use in recovering some rare earths from their associated ores (Bulatovic, 2010; Ni, Parrent, Cao, & Liu, 2011), but much more in-depth research is required."

Jan 1, 2012

By Robert Cluff

The Campo Morado precious-metal-bearing, volcanogenic massive sulphide district occurs in a Lower Cretaceous felsic volcanic sequence in a northerly trending belt in the Guerrero Terrane in northeastern Guerrero, Mexico. During upper Cretaceous to Early Tertiary greenschist-facies regional metamorphism, the rocks were deformed strongly into a northeast-verging fold-and-thrust belt. The deposits belong to a low-sulfidation, volcanogenic massive sulphide system formed in a subaqueous environment, and are of the siliciclastic type. Most are on the flanks of felsic domes or in adjacent basins and many are associated with heterolithic volcaniclastic rocks. The Reforma and possibly the El Rey massive sulphide deposits are interpreted to be overturned, and the Naranjo, El Largo, and Estrella de Oro deposits and the El Profundo occurrence to the south are upright. The G9 deposit and the La Lucha and San Rafael occurrences are in an over-thrust plate further to the southwest. In several of the deposits, zinc, lead, silver, and gold are concentrated near the stratigraphic top, and copper is concentrated near the stratigraphic base; copper also is concentrated in replacement bodies near the top of some domes. Major minerals are pyrite, quartz, ankerite, sphalerite, chalcopyrite, and galena. Gold and silver occur in argentian gold, and silver also occurs in tennantite/freibergite and galena. Underlying stockwork zones contain disseminated and vein quartz, pyrite, chlorite, and ankerite, with locally abundant chalcopyrite and/or sphalerite. Exploration since 2004 has enlarged greatly the El Largo and the high-grade G-9 deposits, and slightly enlarged the El Rey deposit. The cumulative in situ massive sulphides for the Reforma, Naranjo, El Rey, El Largo, and G9 deposits exceed 45 Mt.

May 1, 2006

By K. M. Wild, C. D. Martin, F. Amann

"Argillaceous rock formations, in particular clay shales, are notorious for creating challenges in rock engineering. Due to their generally low hydraulic conductivity and their complete saturation in their natural state at depth, the behavior of clay shales is usually characterized by a strong hydro-mechanical coupling.This paper presents typical pore pressure responses monitored in different underground rock laboratories and explores alternative ways for their interpretation. The underpinning processes and their relevance are identified based on analytical and conceptual numerical models. Pore pressure monitoring data from Opalinus clay at the Mont Terri Underground laboratory, the Boom Clay at the Mol facility and the Callovo-Oxfordian clay in the Meuse/Haute–Marne URL show a similar pore-pressure response associated with stress changes accompanying tunnel construction although the tunnels were built in different rock types, at different locations, and under different in-situ conditions.The numerical analyses in this study shows that the pore pressure response around an excavation in low permeable clay shales may have different explanations. Pore pressure drops observed in the tunnel near field can theoretically be explained by both, a pure elastic response in an isotropic or anisotropic rock mass with an anisotropic stress state, or a inelastic response and related dilatancy. However, a comparison between the numerical models and the in-situ measurements revealed that the latter is more likely. This conclusion is justified by the observation that pore pressure drops occur significantly ahead of the tunnel face which is not the case in elastic numerical simulations. Pore pressure measurements in the far field, where failure processes are unlikely to occur, can only partly be explained by a linear poroelastic models. The introduction of an anisotropic material plays a key role in reproducing the responses, conceptually."

Jan 1, 2015

By K. N. Subramanian, H. Kanduth

"It is well known that chalcopyrite can be dissociated into simple sulphides by heating with elemental sulphur at about 475°C:CuFeS2 + S -> CuS + FeS2Experimental work was undertaken to determine whether this ""activation"" could be used to advantage in the selective leaching of copper from chalcopyrite concentrate.A method of treating copper concentrate with molten sulphur was developed and the activated product was leached in dilute sulphuric acid using oxygen, ferric iron or manganese dioxide as the oxidant. The object was to obtain a solution suitable for electrowinning with minimal purification, but it was impossible to obtain rapid extraction of copper without simultaneously dissolving a large proportion of iron. This was attributed to the fact that some of the copper was present as a low iron-copper sulphide (idaite) and that the pyrite formed during the ""activation"" step was more easily oxidized than natural pyrite."

Jan 1, 1973

By Wei Yingchun

Based on the deep burial depth of coal deposits in Huainan-Huaibei coalfields, Anhui Province, China, this paper puts forward the concept of partitioning of coal deposits according to occurrence conditions. This process is controlled by tectonic forces. The classification scheme of coal deposits exploration types is presented according to occurrence and mining conditions of coal deposits as viewed from the perspective of deep coal exploration properties. The principles underlying geological exploration services for the resources development are incorporated. There are six exploration types of coal deposits in the Huainan and Huaibei coalfields. Exploration models tailored to different types of exploration have been established and exploration strategies corresponding to different exploration models have been proposed. Steady-state temperature must be measured for the deep heat-harm type of coal deposit. The sealing coring of mine gas samples should be performed for the high mine gas type of coal deposit. For coal deposits with complex structures, such as those located beneath nappes, coal-controlling structural styles must be performed. Existing data on shallow districts are very important to the research of folds and fault-block types of coal deposits beneath and peripheral to old and existing coal mine areas. For the types of fault-block coal deposits hidden by thick Cenozoic cover, particular attention must be paid to comprehensive use of research on regional coal occurrence law and geophysical methods. The present work promotes the exploration level of coal deposits in Huainan-Huaibei coalfields to best meet the need for sustainable development of the coal industry.

Aug 1, 2013