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By S. F. Smith

Following a roof beam collapse on a major production district at the British Steel Corporation's Dragonby Iron Ore Mine, Scunthorpe, South Humberside, UK, rock mechanics investigations were undertaken in this room and pillar operation to assess the stability of workings throughout all the underground mine area. Over a four year period room convergence and roof sag were monitored in different mining areas and various junction configurations in order to assess and compare the relative movement of the strata resulting from mining activities, where varying rock bolt lengths and patterns have been utilised. The paper, after shortly describing geological aspects and mining methods, presents the research procedure adopted together with the instrumentation employed and discusses the results obtained during these investigations.

Jan 1, 1995

By Fernando O. L. Xavier

"The Barro Branco coal mine was located in the southern region of Brazil, in the state of Santa Catarina. In 2002, an incident occurred at the mine, leading to a violent, massive pillar failure, resulting in almost 100 failed pillars in less than 3 hours, totaling nearly 700 collapsed pillars after a period of 6 weeks. The paper outlines the geological and operational conditions before the accident and analyzes the primary factors leading up to the event. This paper also discusses and examines the unusual characteristic of violent, uncontrolled pillar bursts that occur over a longer timespan, in comparison to other equally violent but rapid events, such as those that occurred at the Crandall Canyon Mine, at a Book Cliffs District mine, and at the Solvay Mine. INTRODUCTION The southern region of Brazil holds 100% of the coal reserves for the country, and half of it is located within the state of Santa Catarina. Almost the entire Brazil’s coal production, around 8 million tonnes/year, is consumed for electricity generation. Most of the coal mines in Santa Catarina are underground room-and-pillar mines, and most are shallow mines, with depths of cover ranging from 20 to 400 m. The Barro Branco mine, near the city of Criciuma, experienced a violent mine collapse at the end of March 2003, which was analyzed and discussed by Zingano, Koppe, and Costa (2004). The event consisted of violent failure of 100 pillars in less than 3 hours, and a subsequent failure of approximately 700 additional pillars over the next 6 weeks. After the panel collapsed, the mine was closed due to unsafe conditions as a consequence of the seismic event. A map of the collapsed area is shown in Figure 1. GEOLOGY AND MINING METHOD There are two coal seams mined at Barro Branco mine. The first is the 1.5 m to 2.3 m thick Barro Branco Seam, under about 75 m of cover. The second is the Bonito Seam, where the collapse occurred. The Bonito Seam is 2.5 to 5.5 m thick located at a depth of approximately 80 m, with an average dip of 0° to 15°. Various major faults and inherent joints are present in the area."

Jan 1, 2017

By Mark A. Krall

The Conda Partnership's Dry Valley Phosphate mine is a thinly bedded, multiple seam, open pit mining operation where selective mining techniques are used to recover phosphatic shales. The mining methods used are truck/shovel and scraper/ dozer operations. The ore that is mined is shipped 32 km (20 miles) by rail to a beneficiation facility which upgrades the ore via washing and calcining. The mine and beneficiation complexes are owned by the Conda Partnership. The Conda Partnership is a joint venture between Beker Industries Corp. of Greenwich, Connecticut, and Western Co-Operative Fertilizers (U.S.) Inc. of Alberta, Canada. The Conda Partnership operates as a separate entity from the two partners.

Jan 1, 1984

By Chris T. Franke

The Waste Isolation Pilot Plant is a deep underground facility mined in bedded salt interspersed with persistent clay inter- beds. The clay seams delineate beams of salt above and below the excavations which strongly influence excavation performance. This paper reviews available rock mechanics information relevant to improving drift stability by removing the roof beam. Conceptual deformation mechanisms, relevant field data, and numerical analyses were used to investigate the effects of mining the roof of the excavations along a clay seam. Finally, a case study that applies the results of this investigation is presented.

Jan 1, 1997

By R. Hart

In this paper, problems that have been experienced with the rockpass system at Kloof Mine No. 3 Shaft are described. Actions that have been taken to overcome the problems are also described. These include the use of slugshots to remove hang-ups, the abandonment and waste filling of passes, and design criteria adopted for an alternative pass system.

Jan 1, 2006

By Jérôme Girard, Shiu Kam, Sue Longo

"Historically, tailings management in a northern climate has involved the deposition of tailings into the Tailings Management Area (TMA) as conventional slurry. This type of system is obviously viable but presents challenges that are difficult to manage as circumstances change over the life of mine. These issues can include:? Increases in mill throughput, and? Life of the TMA for the life of mine.This case study will present how thickened, high-density, non-segregating tailings are used as an alternative to conventional slurry disposal to achieve greater storage capacity and enhanced environmental performance for a gold tailings facility in a northern climate. This paper will focus on how this change in deposition strategy accommodated the increased throughput of the mill and the increased life of mine. Specifically, the paper will discuss the addition and integration of new processes to the exiting mill system to accommodate the tailings management issues. It will highlight the challenges from laboratory testing to pre-feasibility to the engineered design of the thickened tailings system implemented at Musselwhite Mine.BACKGROUNDGoldcorp Canada’s Musselwhite Mine, in Northwestern Ontario (120 km north of Pickle Lake), is an underground gold mining operation that began production in 1997. The current mill throughput is about 4000 tpd (1.4 Mtpa). Gold extraction is based on a CIP process with cyanide destruction.The existing tailings management area (TMA) is located about 2 km southwest of the mill complex. The TMA is contained by high ground to the north and to the west and flanged by a moraine ridge along the south side. A number of dams have been constructed along this ridge. The dams were first built in 1996 and subsequently raised in 2000 and again in 2005. Excess tailings pond water is discharged to a polishing pond then released to the environment via a wetland.The TMA was originally designed to contain 13.7 Mt of tailings under a ponded surface for closure. The water cover was to inhibit adverse long-term environmental effects because the tailings contain pyrrhotite and other sulphide-bearing minerals that are potentially acid generating. The design was modified during Stage 3 Construction in 2005 to expand the storage capacity to 17.3 Mt (Golder, 2005). As of end of 2009, over 16 Mt of tailings had been deposited in the TMA. The slurried tailings were historically deposited at 50% solids."

Jan 1, 2011

By Chris A. Bennett, Glenn S. Dobby, David A. Bulled

Establishing reagent dosing strategies for new ore bodies has traditionally involved a combination of experience and empirical experimentation using standard laboratory tests. The grade and recovery data resulting from these lab tests have historically been used as direct indicators of plant performance despite the obvious differences between the flotation environments. A reagent scheme selected in this way would subsequently be employed to generate the grade and recovery information for the geometallurgical model which in turn was used for metal production and cash flow forecasts. If the reagent scheme was sub-optimal then so too would be the forecasts and the resulting cash flow.

Jan 1, 2003

By W. Standifird

"Cohesive fracture is a mechanical model widely used for modeling quasi-brittle fracture in rocklike materials. This work discusses use of this model to simulate quasi-brittle fractures generated by injection stimulation during the process of cuttings reinjection in West Africa. Cuttings reinjection is an engineering practice used for disposal of drilling waste. During this process, hydraulic fractures are created at the target formation and milled cuttings are injected with fluid. In practice, this process must remain in compliance with environmental regulations and zero-discharge policies. The purpose of this study is to determine the following factors of injection design for a field in West Africa: (1) pumping pressure capacity required to successfully perform the injection and (2) the injection rate for injection performance and the value of fracture width under injection.A simplified three-dimensional (3D) finite element model (FEM) was built. A poroelastic plastic damage model was used for simulation of the cohesive crack prorogation within the target formation. For simplicity, fracture development in both horizontal and vertical directions was simulated separately. In this way, the computational burden for one calculation was reduced to a reasonably low level, without losing accuracy of the model. Loads of the model include fluid injection and gravity, which balances the initial geostress field. Various values of injection rate were used in these calculations to determine the most reasonable value of injection pressure. The capacity of pressure of a pumping device was determined using this optimized value of injection pressure.Results in values of width and length of fractures created by the injection are presented. Injection pressures at bottom-hole (BHP) corresponding to each value of injection rate are also given. Numerical results for fracture generation and propagation in a horizontal direction were visualized. The pumping pressure capacity required to fulfill the cuttings reinjection work was determined based on the numerical results of optimized injection rates and pressure. The fracture width was determined using the given pumping pressure. The length and height of the fractures was determined using pumping pressure along with the required volume of cuttings waste to be disposed of into the formation.This work presents a case study of 3D finite element modeling of hydraulic fracturing generated by cuttings reinjection. The results of the optimized injection rate and pressure provide a best practice and a useful reference for cuttings reinjection analyses in this region."

Jan 1, 2015

By John Newby, Mahmood Khwaja, Bernard Theron, Janice McGovern, Bernard Catalano, Michael S. Schultz

Launching a full-size pressurized-face Tunnel Boring Machine (TBM) in difficult ground conditions is always challenging. Recently, few projects have innovated the process by scaling the trenchless method of pipe jacking, and modified steel bell approach, to facilitate the launching of a full-size TBM without the need for large and deep trenches, starter/tail tunnels, or for incrementally installing supporting gear as the machine advances. This paper presents three such projects; evaluates the post-bid contractor proposed modifications; details the innovative use of pre-cast pipe segments to facilitate machine launch; and, provides an overall assessment of the benefits, challenges and lessons learned related to the modified approach.

Jun 13, 2021

By G. R. Lane

A large opencast gold mining company in Africa had just completed a feasibility study for an expansion of the operations. A traditional net present value project valuation methodology had been used that showed a very positive net present value (NPV). The project team had conducted a qualitative risk assessment that identified and logged all potential project risks and had subjectively incorporated 'risk' via the discount rate and other assumption contingencies around gold price expectations, operating parameters, etc. Management requested that an independent quantitative risk modelling approach be adopted to obtain a better understanding of the impact of risk on the overall project valuation and confidence level in the final valuation. A detailed project valuation model was configured in the Cyest Carbon Modelling Technology platform, and the stochastic modelling module used to perform the Monte Carlo simulations. Analysis of historical operational performance data relating to actual achievements versus planned and budget determined the historical variability of the underlying parameters as well as variance to budget. This was done at a detailed level for mining rates and costs, processing rate, costs and recovery, and other operational efficiency measures. External market assumptions relating to gold price, exchange rate, and inflation were modelled and the dependency between them modelled using a copula. This case study will demonstrate the approach taken to building and populating the quantitative risk model and the overall results of the Monte Carlo simulation. The final valuation demonstrated that the project had a 44 percent probability of an NPV less than zero i.e. a 44 percent chance of project finance loss.

Jan 1, 2013

By Stanko Nikolic

The Top Submerged Lance (TSL) technology, developed in the 1970s, is now widely used for the processing of a range of materials. TSL technology for continuous converting was first patented in the 1990s. The process is based on the use of calcium ferrite slag. Although this slag system had been applied elsewhere the phase equilibria had not been thoroughly investigated. This lead to a collaboration between the Process Technology group of Mount Isa Mines, now part of Glencore, and the Pyrometallurgy Innovation Centre (PYROSEARCH) at The University of Queensland. Through multiple research programs this complex system was successfully investigated. The results were then implemented within thermodynamic modelling tools. This combined new knowledge was then applied to the design and industrial implementation of the TSL continuous converting technology, ISACONVERT™. This paper describes the key findings of the research and how this was applied to the industrial implementation of the technology.

By Karl A. Higgins, Michael D. Venezia

The South Capitol Street Corridor Project is one of the District Department of Transportation’s (DDOT) largest projects, and is currently under construction. This case study will focus on the design of the foundation piles for the main spans of the iconic Frederick Douglass Memorial (FDM) Bridge, and will include a discussion of the foundation design evolution from an originally designed alternative foundation system (i.e. coffer dams and drilled shafts), to the current use of driven Large Diameter Open End Pipe (LDOEP) Piles. The paper will provide a discussion of the design methodology used during preliminary engineering and final design, and will highlight insight gained from the extensive load testing program completed to date. The load testing program consists of a combination of high strain dynamic testing (PDA), as well as Statnamic Load Testing on select sacrificial, pre-production test piles. Specifically, data gathered during the nearly-completed load testing program suggests the development of significant internal shaft frictional resistance within the tested LDOEP Piles. This paper will also discuss limitations of currently accepted industry design methods for predicting the capacity of LDOEP piles, a subject that is also currently being researched by FHWA. The data from this test pile program will help design assumptions for future projects. INTRODUCTION The Frederick Douglass Memorial (FDM) Bridge carries South Capitol Street across the Anacostia River in Southeast/Southwest, Washington, DC, and is owned and maintained by the District Department of Transportation (DDOT). The existing FDM Bridge is nearly 70 years old, serves as a major artery into the city, and has been classified as functionally obsolete. As a result of the condition, age and limitations of the existing bridge structure, DDOT deemed it necessary for complete replacement of the bridge. The replacement project consists of the construction of a new bridge traversing the Anacostia River, as well as the reconfiguration of the Suitland Parkway and I-295 interchanges located at the eastern terminus of the FDM Bridge. Final design and construction services for the replacement project were procured by DDOT through a Design-Build contract. This paper will focus on the driven Large Diameter Open End Pipe (LDOEP) Piles used for support of the main span of the new FDM Bridge which is currently under construction. Discussion regarding the LDOEP Pile design methodology has been included, along with commentary regarding currently available industry guidance related to design and construction of LDOEP Piles. Much insight has been gained during the mostly-completed and extensive load testing program which consists of a combination of high strain dynamic testing (PDA), as well as Statnamic Load Testing on select sacrificial, pre- production test piles. Specifically, data gathered during the mostly-completed load testing program suggests the development of significant internal shaft frictional resistance within the tested LDOEP Piles.

Jan 1, 2019

By N Currey, G W. Wilson, P Ritchie

Kidston Gold Mine in Queensland, Australia has a 310 ha tailings impoundment that has undergone final closure rehabilitation. Kidston Gold Mine evaluated their closure options for this low acid generating tailings impoundment, and due to a lack of cover soils and the cost of importing material, the mine decided to investigate the possibility of direct vegetation onto the tailings impoundment surface. The mine subsequently embarked upon a well planned and detailed research program to determine the feasibility and sustainability of this closure option. The research program included vegetation trials, toxicology studies for metal uptake by vegetation, as well as a comprehensive closure water balance model for the tailings impoundment complex. This paper describes the results of the long-term closure water balance for the tailings impoundment complex for the pre-closure state of the impoundment, as well as predictions towards the impoundment performance once final rehabilitation of the tailings impoundment complex has been achieved. The water balance presented is unique in that it is founded on unsaturated flow principles and accounts in full the impacts of the surface flux boundary conditions. This novel approach enables the prediction of actual infiltration rates into the tailings impoundment surface, which in turn allows for the calculation of how much seepage will exit from the tailings dam toe drains.

Jan 1, 2003

By M J. Shearer

An investigation into the reliability of the data being collected at the Mount Isa Mines site operated by Glencore in Queensland allowed on-site ventilation personnel to scrutinise pressure and volume measurements collected from the primary surface fans. The investigation effectively identified discrepancies being reported to the on-site remote monitoring system. The difference between the real-time and static measurements on the P63 RAR shaft identified that the in situ differential pressure transducer and piezo annubar system was not operating correctly. This indicated a deficiency of approximately 30 per cent reporting back to the remote monitoring software versus the live readings measured with the Pitot tube bomb and ALNOR AXD610 pressure micro-manometer.Constant monitoring of an operations ventilation network is imperative to ensuring that the underground atmosphere provides a safe and healthy workplace. Further benefits to real-time monitoring allows for the early indication of network failures and promotes increased availability. An innovative approach to out engineer and improve the existing measuring equipment from the 1970s was sought.The use of ultrasonics in the mining industry is not new with ventilation management systems (VMS) equipment available within the marketplace. The introduction and implementation of a reliable product for real-time monitoring was a challenge to overcome due to limited access and suitable measuring points within the mine. The available equipment on the market through mainstream suppliers was not suitable for the unique application required due to the in situ installation of the surface fans. A solution was identified in the oil and gas industry through collaboration and innovative thinking. This paper describes the sustainable approach to implement a reliable air flow monitoring system on-site.CITATION:Shearer, M J, 2017. Case study – an analysis of reliability and efficiency: ultrasonic versus annubar technologies, in Proceedings Australian Mine Vent Conference 2017, pp 51–56 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 28, 2017

By J Harris, J Turner, P Kirsch

Coal mining is recognised globally as a hazardous activity, and as a result operates under high levels of regulatory and public scrutiny while managing a workforce operating in a high-risk environment. Mining companies have developed sophisticated risk assessment procedures, management systems and personnel competency requirements that facilitate the safety and health of employees, and Australia is a world leader in coal mining safety and health.RISKGATE is an Australian Coal Association Research Program funded online platform that delivers broad cross-industry knowledge about current practice in the identification, assessment and management of coal mining risk. Centennial Coal has engaged with the RISKGATE program, managed by the University of Queensland’s Minerals Industry Safety and Health Centre, since its inception in 2010, and contributed topic experts to many modules, including underground topics within the geological and geotechnical domain (strata underground, outburst, coal bumps and bursts, and inrush).In 2013, Centennial Coal experienced significant unexpected strata failure at the Mandalong mine without any personal injury or fatality. This paper presents a case study in the application of RISKGATE to management of this unwanted event, the steps that were implemented, the information that was sourced and the contribution that RISKGATE made to the final outcomes. The Australian coal industry is encouraged to embrace our knowledge platform, and to also openly share processes and practical outcomes that result from integration of RISKGATE in mining operations.CITATION:Harris, J, Turner, J and Kirsch, P, 2014. Case study – application of RISKGATE to managing strata failure in an Australian coalmine, in Proceedings AusRock 2014: Third Australasian Ground Control in Mining Conference , pp 55–60 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 5, 2014

By Patrick Rennkamp, Wolf-Dieter Trodel, Andy Fearn

"The Jansen shafts are completed using purely mechanical excavation. This paper summarises the geology, a description of the shafts, the method used for excavation and the results achieved along with the challenges encountered and the solutions developed during the project. This experience is now being applied in the next generation machines and shaft sinking processes. This pioneering approach is changing shaft sinking in soft and medium to hard rock. INTRODUCTION The Jansen Mining project located approximately 150 km east of the city Saskatoon is the location of the BHP owned potash mine with an expected mining output of eight million tonnes annually upon completion. Mining contractors DMC Mining Services have used two Herrenknecht Shaft Boring Roadheaders (SBRs) to excavate the two blind shafts with an approximate excavation diameter of ten metres (inner diameter approximately 8.3 m) to depths of -975 and -1005 metres, respectively. The SBRs excavate the rock by a partial-face cutting method, using a transverse cutting drum mounted on a telescopic boom. The excavated rock is then conveyed away from the bench by an innovative pneumatic system and transferred into muck buckets to be hoisted to the surface. No drilling and blasting was done to keep to the BHP philosophy of using only mechanical excavation for this reference project. BHP VISION – MECHANICAL EXCAVATION BHP focused on mechanical excavation at Jansen due to the following perceived benefits: 1.No workers in the excavation chamber (shaft bottom), minimizing the exposure to traditional shaftsinking hazards associated with working in the shaft bottom. 2. Minimal damage to the rock fabric reducing the need for ground support and avoiding potential impact damage to freeze tubes located around the shaft. 3. Accurate excavation diameters with no overbreak, reducing volumes of rock to be removed and replaced with concrete lining."

Jan 1, 2019

By G du Toit, P L. Gillot, M Swanepoel

Randgold Resources’ Loulo-Gounkoto Complex is one of the largest gold mining operations in Mali, West Africa. The mine, which is situated on the western border with Senegal, treats more than 4 Mt/a of ore through a conventional three-stage crushing and ball milling circuit followed by a carbon-in-leach plant. Ore supply is achieved by a combination of open pit and underground mining, with the majority of the ore supply sourced from the Gara and Yalea underground mines situated approximately 2 km and 6 km respectively from the gold plant.In 2011, Randgold Resources commissioned Golder Associates to perform an evaluation study for providing structural backfill to both the Gara and Yalea underground mines using the current gold plant tailings. The test work performed as part of the evaluation study concluded the need for a tailings cycloning and dewatering facility capable of producing slurry at a solids concentration of 65 per cent with a particle size distribution that had minimum 25 per cent passing 20 µm and less than 5 per cent of -5 µm material. Tailings desliming was required to ensure a consistent feed quality to the paste preparation plants and to ensure that the system would be capable of handling variation in the feed composition from the gold plant.WorleyParsons, previously TWP Projects, was contracted by Randgold Resources to complete the engineering design for the slurry preparation plant, whilst Golder Associates was retained to complete the engineering design of the two paste preparation plants.This paper discusses the test work, design considerations and engineering design of the slurry preparation plant, termed the ‘intermediate plant’, as well as all ancillary facilities required for the delivery of the deslimed slurry to the paste preparation plants located at the two underground mines.CITATION:Swanepoel, M, du Toit, G and Gillot, P L, 2014. Case study – engineering design for a slurry preparation plant for a paste application in West Africa, in Proceedings 12th AusIMM Mill Operators’ Conference 2014 , pp 477–486 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 1, 2014

By P Nichols, C te Kloot, A Harrison

Ernest Henry mine (EHM) is a sub-level caving operation located in north-west Queensland, Australia. Located below a previously mined open pit, the underground operation ramped up production to 6.8Mt/a in 2017. The EHM ore body dips at 45 degrees to the South and therefore requires each level to “step out” from the level above as seen in Figure 1. Within this step out zone it is important to both maximise recovery and allow for efficient operation of the underground workings production to bring the level up to full production as quickly as possible. Throughout the step out design process, a combination of further defining the ore boundary, using lessons learnt from production performance on upper levels and the introduction of design improvements, has reduced the production ramp-up time, decreased costs and increased recovery for a single level at EHM. CITATION: Nichols, P, te Kloot, C and Harrison, A, 2018. Case study – Ernest Henry Mine: designing step out zones in an inclined sub-level cave, in Proceedings Complex Orebodies Conference 2018, pp 53–54 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 21, 2018

By A. Rai

"This paper provides an overview of the current use of auxiliary ventilation product and the challenges with limited air quantity in dead-end entry or working face. The PVC low frictional factor, low physical constraint and minimum leakage ventilation duct was development with ""made in US and used in US"". The PVC duct development covering operational and total cost of ownership with on-going success will be presented. This paper will discuss mine sites using new PVC vent duct underground and the results from operational and technical side making a difference. INTRODUCTION The Turquoise Ridge Joint Venture (TRJV) is located in northern central Nevada, and is situated within the Basin and Range province, near the northeast end of the Osgood Mountains (see Figure 1). The TRJV mine consists of typical Carlin type- gold mineralization characterized by low strength rock of altered limestone’s, siltstones, and mudstones. The weak nature of the ground facilitates the underhand cut and fill mining methods [3].Mining Method; Underhand cut and fill : The mine uses underhand cut and fill method which has 12’x12’ top cuts and several different size undercuts. The ore body is accessed off of a secondary development heading, utilizing a heading with a cross section of 14W x 14H or 15W x 16H configuration. In the wider and more massive zones, two headings in a production panel may be worked at any one time. Drift round lengths are determined by the type of drilling machine being used. An example of a typical topcut and associated undercut layout is shown in Figure 2. SECONDARY / AUXILIARY VENTILATION IN UNUNDERGROUND METAL MINES The auxiliary ventilation system provides the required air volumes at the face of dead-end developments and production workings, which in many cases may be considered as the primary method of assuring that the air quantity and quality standards in these working areas are satisfied. The Auxiliary fans and ducting systems are usually the primary means of delivering the required air volumes to the face of dead-end developments and production workings. Both centrifugal and axial-flow fans are used in underground auxiliary ventilation systems, usually electric powered. The internally direct driven axial-flow fans tend to be more popular because of their compactness and adaptability to staging. The most commonly used materials for ridged tubing are coated steel, alloyed steel, fiberglass and resin. Flexible (collapsible) ventilation tubing is also used and is usually made from neoprene-coated or nylon material. To add stiffness and reduce collapsibility these fabric ducts can be formed over a steel spring frame. A very important factor in the design of an auxiliary ventilation system is to minimize leakage and reduce the frictional pressure losses along the auxiliary ducting systems by minimizing their friction factors (K)."

Jan 1, 2015

By T. Weatherwax, A. Rai, J. Poor

"This paper provides an overview of the current use of auxiliary ventilation products and the challenges with limited air quantity in dead-end entry or working faces. The PVC’s low frictional factor, low physical constraint and minimum leakage properties were ideal to develop as ventilation duct in conjunction with the concept of ""Made in the US and Used in the US"". The PVC duct supports the operational and total cost of ownership with on-going success. This paper will discuss the continuous improvement made in ventilation ancillary products for optimum results. The paper will also cover mine site usage of second generation PVC vent duct underground and the results from the operational and technical side making a difference in health and safety and overall auxiliary ventilation. INTRODUCTION The Barrick Turquoise Ridge Inc. (TR) is located in northern central Nevada, and is situated within the Basin and Range province, near the northeast end of the Osgood Mountains (see Figure 1). The TRJV mine consists of typical Carlin type- gold mineralization characterized by low strength rock of altered limestone, siltstones, and mudstones. The weak nature of the ground facilitates the need for underhand cut and fills mining methods.Mining Method; Underhand cut and fill: The mine uses underhand cut and fill method which has 12’x12’ and or 14’x14’ top cuts with several different size undercuts. The ore body is accessed off of a secondary tertiary heading, utilizing a heading with a cross section of 14W x 14H or 15W x 15H configuration. In the wider and more massive zones, two headings in a production panel may be worked at any one time. Drift round lengths are determined by the ground conditions and drift dimension. An example of a typical topcut and associated undercut layout is shown in Figure 2."

Jan 1, 2016