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By K. Iturralde

Dense transport infrastructure areas lack green facilities, they produce annoying noise and they are big energy consumers. As far as there is no free land or space, adding a vegetal covering to existing infrastructures has become a choice in order to get a more pleasant and comfortable environment. Noise barriers are getting spread all over the highways and sometimes they install photovoltaic panels. Is this just a hype or are there real causes? A green acoustic barrier with an energy generator could be interesting for covering the existing urban transport infrastructures. The specific geometry of the infrastructures requires a personalized product. If we measure the infrastructure environment's characteristics, which are humidity, temperature, sunlight and size, we can create an accurate 3D model. This model would be used for various purposes. For instance, it could be a useful tool to design and fabricate the customized prefab acoustic barriers and plant containers. And it would be helpful for adjusting efficiently the future performance of the vegetation and photovoltaic panels. But the insertion of vegetal elements in infrastructure surroundings can be a tough operation. It requires special skills and techniques. Nowadays, those tasks are performed almost manually and they require a big effort. The prefab containers for vegetal elements would ease the robotic assembly on site.

Aug 1, 2013

By R. L. Veenstra

This paper explores the connection between the stresses observed and the failure mechanisms present in the modelled cemented paste backfill. In order to look at this connection, the authors have used a previously developed model to conduct a sensitivity analysis of the model?s strength and permeability input parameters. The results from the sensitivity analysis were then compared to determine what causes modelled stresses and failure mechanisms to vary. Increased insight into the behaviour of the modelled paste will help clarify how paste behaves in the field.

Aug 1, 2013

By Ferrin Prince

New Gold?s New Afton mine is an 11,000 tonne per day block caving mine, located 8 km west of the city of Kamloops, British Columbia. The reserve is estimated at 52.5Mt with grades of 0.65 g/t Au and 0.93% Cu. Block caving requires a considerable amount of infrastructure development before production can begin. Each excavation had its own challenges, often further complicated by interactions with the caving stresses and fault structures. The main areas of interest were: the production crusher complex, the surface to underground infrastructure, and the footprint interaction with the faults. The ore zone at New Afton is bounded by two very weak fault zones, with large fault affected areas and associated splays. The resulting rock mass rating (RMR) is 35-50, with some areas significantly weaker due to clay infill. These conditions created a unique and decidedly difficult environment in which to develop New Afton?s infrastructure. Despite these difficulties, the mine began production on schedule in July 2012. The main production crusher for the mine is a gyratory crusher that allows for direct truck dumping, with a smaller jaw crusher in series to facilitate the initial development and production. The crusher chamber was redesigned several times to minimize the chamber volume, resulting in a 40% decrease in volume without losing functionality. After drilling and geotechnical testing, the location of the crusher was changed to eliminate the threat of fault affected ground in the area; the entire complex moved a short time before mining began on the chamber. The mining techniques used enabled tight control of the crusher pocket excavation, while also allowing for the timely completion of the chamber. The locations of the surface to underground infrastructure were tightly constrained by geology, surface infrastructure, and an existing open pit. The VR5 raise was drilled and abandoned part way through the reaming process when the drill string became stuck in fault gouge material. It was relocated and successfully completed. The VR7 raise hit a region of poor rock strength and deviated more than 11 m. Poor ground conditions caused a 130m section of the raise walls to fail. An innovative rehabilitation program was undertaken to re-establish the raise for ventilation. A surface to underground slick line was also installed to ease the material movement underground. A layout of the Extraction level was changed from herring bone to straight through drawpoints that resulted in a net reduction of 1.3 km of development. The Apex level was added to aid in the breakage over the major apex pillar and allow for geological mapping. A portion of the caving footprint is located within the footwall fault. The low strength, high clay content, and small joint spacing of the material resulted in blast-hole cut-off and drift deformation. Drift rehabilitation was a key factor in the successful development of the cave footprint. Innovative drilling and loading techniques were used to keep the holes open and to impede movement along the joint structures.

Aug 1, 2013

By N. Valkanov

This paper presents results of an investigation into the connection between minerals liberation management and flotation, responding to lead-zinc concentrator ?Erma reka?, in Bulgaria. Monitoring of a Zn flotation circuit was carried out. The causes for the high silica content in the final Zn concentrate were established. Quartz is present mainly as liberated particles (> 60?80 %) in the fine fractions of the products; therefore the selectivity of the flotation process is not effective. Two approaches were tested to reduce the quartz content of Zn concentrate: froth washing in Zn cleaner flotation and new gangue depressants in the Zn circuit. Experimental results from bench-scale flotation and industrial tests show that it is possibile to reduce the silica content of final Zn concentrate more than 2 times without the need for extensive regrinding. The depression of liberated quartz particles on all operations of Zn circuit using stage depressant addition is the right solution to produce high-grade Zn concentrate that meets the metallurgical requirements.

Aug 1, 2013

By A. M. Esteves

This paper offers an overview of local content policies and practice in the mining sector. Specifically, the paper aims to answer the question of how national and regional governments, industry and civil society can work together to seek an optimal outcome while pursuing their diverse objectives. The paper begins by defining local content and its scope at the subnational level. Specific recommendations for the design of local content policies to mitigate social, economic and governance risks are developed. The document then offers some recommendations regarding the role of partners in design, implementation, monitoring, and enforcement of local content policies.

Aug 1, 2013

In this study, we develop a detailed model of the likely future carbon footprint of primary copper supply. We develop a peak copper production model, based on a detailed copper resource data set, and combine this with a comprehensive life cycle assessment model of copper mining and milling to predict greenhouse gas emission rates and intensities of Australian and global copper production up to 2100. By establishing a quantitative prediction of both copper production and corresponding greenhouse gas emissions of Australian and global copper industry, we then analysed the emissions intensity of various energy input scenarios, such as business-as-usual, solar thermal electricity and solar thermal electricity with biodiesel. The Australian Government has an aspirational goal for long-term greenhouse gas emissions of an 80% reduction from the 2000 level by 2050. For the copper sector, this means moving from about 12.6 Mt CO2e in 2000 to a goal of some 2.52 Mt CO2e in 2050 (assuming equal emissions reductions across the economy). Based on the energy sources modelled, only the solar thermal plus biodiesel scenario was capable of achieving this goal at about 0.15 Mt CO2e, since the solar thermal alone scenario still includes normal petro-diesel as a major source of emissions. Overall, it is clear that there are abundant resources which can meet expected long-term copper demands, the critical issue is more the carbon (and environmental) footprint of different copper supplies and use rather than how much is available for mining. It is clear that the switch to renewable energy can have a profound impact on the carbon intensity of copper supply, even allowing for increased energy intensity as ore grades decline, and a complete conversion to renewable energy will position the copper sector to meet existing annual greenhouse gas emissions targets and goals.

Aug 1, 2013

By Kremena Dedelyanova

The paper presents research of mechanism for the creation of air bubbles in vibratory a column flotation machine. Factors are discussed that influence the increase in the duration of the bubble in the area of contact with the mineral particles. Formulas are derived for the parameter effect of vibrations, applicable to the design of flotation machine. The collision efficiency of the bubbles in a vibratory column flotation machine is determined.

Aug 1, 2013

By M. Kuyumcu

With annual production of almost 3.5 million metric tonnes of K20, former East Germany (GDR) was the world?s third-largest producer of potash, ranking behind only the Soviet Union and Canada. More than 80 % of production was intended for export to earn urgently needed hard currency. For this reason, beginning in the 1970s, East Germany began to mine unprofitable hard-salt sources and carnallitite fields, which are geomechanically problematic. In the course of restructuring from a centrally planned to a market economy after German reunification, only two of the nine existing potash mines were classified as economically viable for privatization. All six potash mines in the South Harz Region were closed between 1991 and 1993. The orderly safekeeping of these potash and other decommissioned ore mines and the rededication of mining areas were assigned in 1992 to a German state-owned company GVV founded especially for this purpose. Elaboration in the present documentation covers the local necessity of the type and extent of filling and safeguarding measures. As a result of the remedial measures taken, it was possible to prevent the collapse of cavities and damage to surface facilities. This documentation describes the safeguarding successes to date, with appreciable reduction and stabilization of surface settlement and with significant lessening of seismic events. Also presented are concepts updated to the state of the art for safeguarding of numerous potash mining shafts for long-term effectiveness in separation of the workings and watercourse levels in the cap rock. In the course of 100 years of production, six mining dumps resulted with a total volume of approximately 170 million m3. They consist of up to 95 % of water-soluble salts. Every year, precipitation dissolves up to 500,000 tonnes of this salt, which enters as a highly concentrated solution into watercourses and ground water. Explanation follows of measures for minimization of environmental pollution by covering of dumps and controlled drainage of alkaline solutions from the dumps. Finally, presentation is made of the results of the successful work until now by GVV for reuse of decommissioned mining sites with settlement of new companies for creation of additional jobs and for revitalization of the monostructured South Harz Potash Mining Region.

Aug 1, 2013

By J. R. Rau

While refuge chambers are common place in most underground mining projects, there are different philosophies as to what life support systems are to be considered and how these systems are to be applied. Case studies in the underground mining industry have examples of emergencies where the external compressed air and power supply to the refuge chamber were compromised due to proximity of services to the fire location. In 2005, The Department of Industry and Resources, Western Australia, drafted guidelines that listed specific requirements for refuge chambers which included a secondary life support system that would operate independently of external sources. The objective of this document is to examine what critical life support systems are essential for safe entrapment in the event of an emergency and to examine considerations for their application.

Aug 1, 2013

By W. G. Pariseau

Face and pillar bursts, bumps and bounces are violent failures that occur in underground coal mines in response to a complicated interplay of face and pillar geometry, seam depth, coal strength and moduli and interactions between roof, seam and floor strata. Additional complications arise from the presence of gas, mainly methane, and associated pressure and flow that vary with time and are further influenced by the rate of face advance. Numerical models provide a means of quantitatively accounting for the various complications of mining geometry, the stratigraphic column, mechanical properties, gas flow properties and associated interactions. A fully coupled hydromechanical finiteelement code, utAH4, serves the purpose well and allows study of the important interaction between stress concentration and gas pressure in determining safety and stability of the face during the advance of a longwall panel in a deep underground coal mine in central Utah. Face advance is relatively fast compared with gas flow and depressurization in coal seams of low gas permeability. Consequently, gas pressure is high at the face. When a longwall is stationary, depressurization occurs at the face, so effective stress and strength increase. thus, when gas flow at the face is high and requires a pause in face advance to bring gas concentration to an acceptable level, a second benefit occurs because of timely depressurization. However, quantitative analysis of a deep coal mine shows that regardless of gas pressure, high stress concentration is more likely to pose a threat to face and pillar wall stability.

Aug 1, 2013

By Piotr Litwa

The paper focuses on actions aiming at improvement of work safety in mines, particularly in those extracting hard coal, taking into account the characteristics of natural hazards in Polish underground mining and the reasons of mining disasters connected with those hazards. It refers to conclusions addressed to scientific and research centres, drawn during last decade by Commissions appointed by the President of the State Mining Authority in order to investigate reasons and circumstances of incidents, which till now, could not have been accomplished because of financial reasons. Furthermore, the paper presents basic assumptions of the Strategic Research Project Improvement of work safety in mines, announced by the National Centre for Research and Development at State Mining Authority?s President request.

Aug 1, 2013

By Zhang Junzhi

This paper relates cross-border mergers and acquisitions (M&A) risk management theory to actual coal enterprises in China. The 3 phases of M&A are preparation, implementation and integration. By using the Analytic Hierarchy Process and fuzzy evaluation methods, we will try to establish a model to assess risks of the cross-border M&A of China?s coal enterprises. We then apply this model to the case of Yankuang Group acquisition of the Felix Company and receive the assessment results. There are significant reasons for quantitative research on risks of cross-border M&A of China?s coal enterprises, such as effective prevention and risk-aversion, and facilitation of cross-border M&As.

Aug 1, 2013

By Andrew Gillam

Outline of Presentation ? AMEC overview ? Benchmarked companies ? GRI 3.1 Guidelines ? Best practice examples ? Report content and boundary ? Strategy and profile ? Environmental ? Social GRI G3.1 ? Gold Standard for Reporting ? GRI ? Global Reporting Initiative ? 1997 outgrowth of Coalition for Environmentally Responsible Economies (CERES) and UN Development Program (UNDP) ? Official collaborating centre of UNDP and works in collaboration with UN Global Compact ? Coalition of companies, business organizations, accounting firms, CSR consulting firms and nogovernmental organizations (NGOs) ? Mission: develop and disseminate globally applicable Sustainability Reporting Guidelines ? Now de facto CSR reporting standard; appeal lies, in part, with supported flexibility in reporting approach and scope ? Latest generation G3.1 (March 2011); includes expanded guidance for reporting on human rights, local community impacts and gender

Aug 1, 2013

In some parts of the world explosions in mines are more commonplace events. Even in the more developed nations explosions have occurred in recent times. In some cases these mines have significantly lowered their lost time injury frequency rates and as such considered themselves to be ?safe? operations. The consequence of these explosions has been devastating. It is not just the loss of those underground, but also to the families that have lost people in them and the broader community that has lost friends, income, business opportunities, and in many cases support and sponsorships. It begs so many questions, ?What went wrong??; ?Why were the circumstances not foreseen??; ?What could have been done to prevent it??; ?How is it that no one stopped it, reported it, fixed it etc.??. Being held accountable for negligence, should not be overlooked, however this may not aid the processes required to find all the answers. If the nature of explosions is understood, the circumstances and tools to prevent them are readily available then the occurrence and reoccurrence are due to weaknesses or inadequacies of the systems of work or in the implementation of them. This paper restates the fundamentals of gas explosions, examines the options to control the underground environment through ventilation, gas management and monitoring, education and training. Case studies have been used to examine systematic failures in ventilation management. In some of these cases it is not so much, the system that had been developed, but the interpretation and implementation of the system that resulted in the failure and subsequent loss.

Aug 1, 2013

By M. Kermani

This paper presents and compares the physical properties of Gelfill and cemented hydraulic fill (CHF) obtained by lab experiments. Gelfill has an alkali activator such as sodium silicate in its materials in addition to primary materials of cemented mine backfill which are deslimed tailings, water and binders. The CHF and Gelfill samples with various mixture designs were cast and cured for 28 days. Initially, the influence of sodium silicate concentration on the mechanical properties of samples was evaluated using the unconfined compressive strength (UCS) test. Consequently, the effect of curing temperature on CHF and Gelfill samples cured in various curing temperatures ranging from 5?50 °C was studied using the UCS test. Microstructure of selected samples was studied wirth the mercury intrusion porosimetry (MIP) technique. This study concludes that: (i) The mechanical properties of CHF can be improved by the addition of appropriate amount of sodium silicate. (ii) The rate of strength acquisition in Gelfill samples is faster than CHF samples over 28 days of curing period. (iii) Curing temperature strongly influences the mechanical and microstructural properties of CHF and Gelfill samples. (iv) The microstructure analysis revealed that the addition of sodium silicate can modify the pore size distribution and total porosity of Gelfill which can contribute to the better mechanical properties of Gelfill. (v) The MIP tests suggested the microstructure of specimens were changed by adding sodium silicate in a way that the Gelfill samples had a higher percentage of fine pores than CHF samples.

Aug 1, 2013

By Jan Butra

In copper ore mines located in the Pre-Sudeten Monocline the deposit mining using room and pillar systems has been carried out for more than forty years. When implementing mining systems in deep copper ore mines it appeared to be necessary to adapt them to variable geological conditions and natural hazards. In the initial period of exploitation there were mainly caving and rockburst hazards. The adaptation of room and pillar system was connected with a state of knowledge in the scope of identifying, forecasting and controlling rock mass hazards. The new solutions allowed the safe and efficient exploitation of a blanket deposit of variable thickness from about 2 to 15m, seated on progressively increasing depth. They included exploitation in constrained conditions, such as in protective pillars. In the exploitation period, technical and organisational activities aimed at rockburst hazard control were introduced including active methods for controlling rockburst hazard and procedures for conducting mining works in the rockburst hazard conditions. When mining at a depth exceeding 1,200 m, the exploitation method and technique are additionally affected by thermal hazard and by gas and rock breakout hazard. New solutions of the room and pillar system and a longwall system with mechanical mining have been developed for exploitation in the associated hazard conditions. The require application of many innovative solutions in the scope of mining process and ore haulage mechanisation, excavation support and forecasting and control of existing hazards. The main purpose of these solutions is to conduct the safe and economically effective exploitation of the deposit.

Aug 1, 2013

By J Cardozo

El presente texto señala las pruebas que comprenden el proceso de rehabilitación de la mina Pierina de tajo abierto. En esta perspectiva, las pruebas y monitoreos identificaron que los paneles cubiertos con el sistema de confinamiento geocelular Geoweb asociados a otros geosintéticos y a un tratamiento biológico de los suelos tienen buen rendimiento, generando vegetación y un comportamiento estable en los cinco años que tiene el proyecto.

Aug 1, 2013

By Shahé Shnorhokian

Numerical modeling is increasingly being used as a tool to examine complex geomechanical issues related to rockmass behaviour and stability of underground openings. The in-situ stress regime and the evolution of mining-induced stresses during the life of an operation, taking into account the planned stope sequence, are topics that can only be handled through the use of a realistic and calibrated numerical model. This paper presents a case study of a deep underground Canadian mine in northern Ontario. A FLAC3D model was constructed and calibrated based on in-situ stress measurements. In the first stage, the evolution of stress regime was studied and compared with the occurrence of rockburst events during a period of three years. The locations of clusters were examined and compared to the mining sequence during that period. In the second stage, stresses within a diminishing ore pillar were examined based on the planned stope sequence and compared to levels deemed acceptable to the mine. Based on the results, an alternative sequence was arrived at to reduce stress accumulation in the pillar, or induce it to occur at a further distance from a brittle dyke in the vicinity of the orebody.

Aug 1, 2013

By C. Graham

Thin Spray-On Liners (TSLs) have been researched and in development for over two decades and yet their fully functional and widely justifiable application in mining has yet to be achieved. While the explanation for this is partly technical, it is also clear that proving and communicating the operational and economic case for why a mine should change from mesh or shotcrete liners to a TSL is not a trivial matter. Evidence must be presented and communicated effectively, that is both obvious and compelling for a mine operator. The paper describes recent work carried out and directed towards this end, with funding from CAMIRO?s Deep Mining Research Consortium and additional support from 3M Canada and ABB Canada. The essential progress that has been, or is in the process of being made, will be described in providing the necessary proof of acceptable or superior TSL performance in the following areas: polymer formulation, health and safety, geotechnical specification, robotic liner application, business case economics and yielding ground support effectiveness. Future plans are also presented to demonstrate the performance of a new 3M composite TSL/yielding bolt support system in underground trials where the substrate rock is intended to fail through a number of mining-induced mechanisms.

Aug 1, 2013

By Don W. Dotson

In 1962, Kondner prepared several papers dealing with hyperbolic stress-strain response of cohesive soils. The following year, Brinch Hansen proposed 80% and 90% failure criteria for stress-strain behavior of cohesive soils. Fellenius was instrumental in popularizing these failure criteria for pile load tests and offered a direct solution equation for the failure load according to the 80% failure criterion. Since the 90% Criterion has been incorporated into the International Building Code, equations for the direct solution of the failure load at the 90% Criterion would be useful to practicing engineers. This Technical Note supplies the derivation methodology for the 80% Criterion and provides expressions to determine the load and deflection at failure for the 90% Criterion.

Aug 1, 2013