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By Jaime Lomelin

[First of all I want to thank the Society of Mining Engineers of AIME for the opportunity to present what Industrias Penoles, S.A. is doing in Mexico to reach the basic objetive of the enterprise without compromising, in short or long term, the living conditions of the community or attempting in an irreversible form against Nature. Industrias Penoles, S.A. is one of the largest mining and metallurgical companies in Mexico. It was founded in 1887 and at the turn of the century installed a lead smelting operation close to the village of Torreon, which became city five years after the start up of the Penoles smelter. Now Torreon has a population close to 300,000 inhabitants. In 1974 Penoles is still the largest industry in Torreon and the dynamic growth of the city is close related to this factor. Today Penoles in Torreon has a lead smelter with a capacity of 130,000 metric tons/year of bullion, an electrolitic zinc plant of 105,000 metric ton/year, and it is modernizing its lead smelter to control pollution and expand it to 190,000 metric ton/year of bullion including all the services and refinery. The Penoles complex in Torreon is the biggest in the non-ferrous metals field in Latinoamérica.]

Jan 1, 1974

In the dimension stone industry, workers in processing shops may be exposed to harmful levels of respirable silica dust when conducting the different tasks in stone preparation, which include cutting, grinding, polishing, and thermaling. To protect workers from this health hazard, operators sometimes ventilate processing shops using fan-powered dust collectors to capture and filter dust. To investigate this issue, NIOSH, Pittsburgh Research Laboratory, in cooperation with a dimension stone operation, upgraded an off-the-shelf dust collector the operator was utilizing in a polishing/cutting shop. Initial dust surveys showed that the unit was under-designed for the amount of dust being generated in the shop. The objective of the research was to cost-effectively increase the air cleaning volume and improve dust capture efficiency of the unit with a larger motor and blower. The unit?s original stock 0.56 kw motor and blower was replaced with a 2.24 kw motor and matching blower to increase airflow. The unit was evaluated both in the laboratory and the shop before and after the retrofit to determine the improvement of the upgrade. The study showed that the 2.24 kw upgrade improved the performance over the original 0.56 kw motor resulting in more dust being cleaned from the ambient air in the shop. The 2.24 kw unit cleaned 19% more air and captured 32% more respirable dust than the 0.56 kw unit.

Jan 1, 2009

ITEC Environmental Colorado has begun reprocessing the tailings from old mining sites near Boulder, CO. And if the technology behind ITEC's pilot project at Gold Hill proves successful and profitable, the company plans to launch similar reprocessing operations in other parts of the state. The pilot project is under the watchful eye of state and federal authorities. They hope the technology becomes the answer to cleaning up old mining sites throughout the West. Remining and environmental cleanup on an economic basis, then, are ITEC's hopes in one the most environmentally conscious counties in the state. Clean up the mine dump sites and recycle the land, for a profit. In June 1998, ITEC Mineral Inc., ITEC Environmental Colorado's Canadian parent, acquired the Gold [ ] Hill Mill facility in Boulder County. Included in the acquisition was 4.4 hm2 (11 acres) containing the Gold Hill Mill and 283 hm2 (700 acres) of additional properties adjacent to the facility. ITEC estimates that there are about 910 kt (1 million st) of dump rock in the area. That is enough to make the operation viable. ITEC will sell the metals recovered through its reprocessing operations. However, due to low metals prices, ITEC is not expecting to make much money on the recovery of precious and base metals. Instead, the company plans to resell the reclaimed land for residential and commercial development or open space. The Gold Hill Mill site is the first of 17 sites in Colorado that ITEC Mineral hopes to clean up and recycle the land. Most notable among the sites is the historic Central City/Black Hawk mining district, which ITEC believes holds considerable potential. The Gold Hill Mill is located 14 km (9 miles) west of the city of Boulder and less than a half mile from the small town of Gold Hill. The mill was. last operated in 1992. The operation was forced to close that year due to environmental and cash flow problems. Gold Hill is in the middle of a region with more than 32 Mt (35 million st) of mine tailings. Independent geologists have' established the average grade of the Gold Hill mine tailings to be 4.5 to 5.3 g/t (0.13 to 0.155 oz/st) of gold and 28 to 44 g/t (0.83 to 1.29 oz/st) of silver. According to these studies, the Gold Hill mine tailings are five times richer in precious metals than the tailings of the Norebec Manitou property in Canada that ITEC is also remining, reclaiming and restoring. Upon acquiring the mill, ITEC undertook a refurbishing program that included adding a second ball mill. This increased the Gold Hill Mill's capacity to 180 t/d (200 stpd). The operation employs 15 people. "The Gold Hill Mill site will demonstrate the efficiency of our integrated remining, reclaiming and restoration process," said Maxine Stewart, president of Denver, CO -based ITEC Environmental. "The abundance of similar mine sites in Colorado presents a number of opportunities to bring the benefits of the ITEC system to other communities around the state." Holly Huyck is technical advisor to the Clear Creek Watershed Advisory Group. She said: "ITEC is cleaning up an orphan mine site that otherwise would continue to contaminate the Boulder Creek watershed with acid and excess metals. This is a win-win situation: ITEC gains marketable minerals while it reclaims mined land and helps to improve the watershed."

Jan 1, 1998

By D. Zaharaki

In the present experimental study the geochemical stability of inorganic polymers was studied by immersing them in various solutions (distilled water, seawater and 0.5N HCl) for a period of 7 months. Inorganic polymers were synthesised by mixing ferronickel slag with kaolinite, potassium hydroxide and sodium silicate solution. The cement like paste was heated at 80 °C for 48 hours and left for curing at room temperature. Their structural integrity was assessed by compressive strength testing after subjection to freeze-thaw cycles as well as high temperature heating. XRD studies were carried out in order to identify new formed phases and provide useful information regarding the progress of the mechanisms involved.

Jan 1, 2008

By B. K. Mishra, R. K. Rajamani

A numerical method known as the discrete element method (DEM) is used to track the motion of individual balls in large-diameter ball mills. As a result, the en masse motion of the charge, force distribution, fall-height distribution, and energy distribution emerges from the simulation. Hence, it is possible to investigate the effect of mill diameter, liner profile and ball size distribution on the force regime created within the mill. Simulation results for 14-, 16- and 18-ft diameter mills are shown. The proportion of energy lost in high-intensity impacts and sliding ball motion is discussed. The DEM simulation technique opens the way for a closer examination of liner profiles on ball-charge motion.

Jan 1, 1992

By Lyman File

This paper discusses the overall challenges to construct a two-lane highway tunnel located in southwestern Colorado on U.S. Highway 160 for the Colorado Department of Transportation by the Kiewit Western Company. The purpose of this project is to provide the excavation and temporary support for a highway tunnel 280 m (916 feet) long. The tunnel cross section is 14.3 m (47 feet) wide by 8.5 m (28 feet) high, 105 m2 (1,130 SF).Construction methods include conventional drill and blast excavation with rockbolt and shotcrete ground support. This unique tunnel is being constructed under alpine tunnelling conditions and in the immediate vicinity of active highway traffic.

Jan 1, 2003

By R. Strandahl

As one of the largest private utilities globally, E.ON currently operates hard coal fired power stations in with a total installed capacity of some 20.000 MW: These thermal power plants consume domestic coals but are increasingly dependent on imported seaborne traded coal (in 2009 approx. 17 million t). Knowing that the company’s reputation and credibility depends in part on how E.ON lives up to the responsibilities along the entire energy value chain, E.ON takes a collaborative approach with the various suppliers. Hence, E.ON’s responsible policy also applies to the procurement of coal; the utility launched in 2009 a comprehensive Corporate Responsibility program with special focus on supply-chain audits. One of the first coal audits focussed on the Cerrejón coal mine in North Eastern Colombia. The authors will share the key learning’s and experience from the Colombian audit jointly conducted with an independent auditor and E.ON experts from the Corporate CR and E.ON Energy Trading.

Jan 1, 2011

By Christopher Haycocks, Lawrence P. Johnson, George M. Neall, James M. Townsend

INTRODUCTION Conventional roof support methods such as mechanical and resin bolting provide adequate support for a wide variety of coal mine roof conditions. However, roof falls remain the single largest cause of death and injury in underground mines and seriously hamper production in many operations, demonstrating that these methods of roof support are not universally effective. One of the most recent and successful advances in coal mine roof control has been the introduction of the roof truss. Although past work on roof trusses (Gambrel1 and Haynes, 1970; Sheory, et al, 1973) shows little quantification of this support technique, numerous field examples have been cited where the truss effectively supported roof which could not be controlled by either mechanical or resin bolts (Kegel, 1969). The truss combines the advantages of both inclined roof bolts and post-stressing the roof. However, the full benefits of roof trusses will only be realized when design criteria to optimize support capacity are determined. The number of trusses required for a given roof condition can then be minimized, reducing installation time and making them economically more feasible. The purpose of this research is to develop roof truss design criteria based initially on laboratory studies of gravity-loaded multi-layered photoelastic mine models. Laboratory test results will then be modified where necessary following future field testing. The ensuing relationships should provide the field engineer with a reliable means of calculating optimum truss configuration, capacity, and spacing for a set of known roof conditions.

Jan 1, 1977

By Greg Wieland

Deep sewer tunnels are required to meet future growth demands of the City of Austin?s down-town redevelopment. The tunnel is 18,000 ft long and varies in finished diameter from 54 inches to 96 inches. The tunnel crosses under Austin?s Town Lake three times and there are four main work shaft sites. Geology, groundwater, foundations, downtown redevelopment, and an active, healthy community put significant constraints on the design. This paper discusses a major underground project for downtown Austin and discusses the risk considerations and the opportunities the design team took toward optimizing the project design for the construction phase.

Jan 1, 2008

By Howard R. Postovit, Bonnie C. Postovit

Raptors are birds of prey. In recent years, these birds have become highly regarded and have been given protection under various state and federal statutes. Surface coal mining can have both negative and positive impacts on raptors. Mitigation strategies and enhancement techniques can be implemented to alleviate negative impacts. The success of habitat reclamation will determine the long-range impact of mining on raptors.

Jan 1, 1989

By L. R. Shotwell, C. F. Voss, R. J. Bastian

Pacific Northwest Laboratory (PNL) currently supports the U.S. Department of Energy's Office of Civilian Radioactive Waste Management in developing and evaluating analytical methods for assessing the suitability of sites for geologic disposal of high-level radioactive waste. The research includes consideration of hydrological, geomechanical , geochemical , and waste package components and the evaluation of the degree of coupling that can occur between two or more of these components. The PNL effort and those of other research groups investing potential waste sites in the U.S. and abroad are producing a suite of computer codes to analyze the long-term performace of the proposed repository sites. This paper summarizes the ongoing research in rock mechanics at PNL involving flow through jointed rock. The objective of this research is to develop a methodology for modeling the coupled mechanical-hydrological process of flow through joints and then attempt to validate a "simple" model using small -scale laboratory test data as a basis for judging whether the approach has merit. This paper discusses the laboratory tests being conducted to develop s joint behavioral constitutive model for the numerical method under development and the modeling approach being considered.

Jan 1, 1986

During 1997-2001, an EC funded project investigated the environmental consequences of the use of industrial waste and sewage sludge based artificial top soils (ATS) in rehabilitating large coalmine waste dumps in the Saar region of Germany. Both the laboratory leaching tests and field lysimeter data analysis carried out by the research partners have shown that the amount of dissolved heavy metals in the leachate was low, and generally below the regulatory limits. However, the dissolved amount of nutrients, especially mineral nitrogen, was found to be relatively high. The hydrological properties of waste rocks and ATS mixtures were established through history matching of the laboratory column tests and the field measurements. 1D column models and 3D field models were used to numerically simulate pollutant transport at the ATS rehabilitated waste dumps. This paper presents the findings of the numerical modelling research carried out for the characterisation of hydrological and pollutant transport properties of rehabilitated coalmine waste dumps in the Saar coalfield.

Jan 1, 2003

By Stanley M. Miller

Analysis of discontinuous rock masses for engineering design purposes requires information about fracture characteristics. For such studies, fractures or other elements of the rock fabric (bedding, foliation, etc.) should be considered in a statistical manner because they generally have high frequencies of occurrence and are discontinuous over the design area. A practical design procedure includes defining structural domains as those areas which contain fractures with similar orientation patterns. Within a structural domain, the statistical distributions of fracture set characteristics (spacing, fracture density, dip, dip direction, etc.) may be computed from mapped data and then used to quantitatively describe the rock fabric. These distributions can then be randomly sampled (using Monte Carlo techniques) to simulate the rock fabric and to help define potential failure surfaces along fractures. 1 The prediction of failure geometries is an essential part of stability analyses used in designing rock slopes or underground openings. In current probabilistic design procedures, Monte Carlo techniques that rely upon the iterative generation and analysis of deterministic instability models do not incorporate spatial aspects of the random variation in fracture set characteristics, 1,2 but consider the characteristics to be spatially independent.

Jan 1, 1979

By R. J. Boyd

SUMMARY The productivity of drill and blast methods of mining in hard rock is limited by the cyclic nature of the operation, and a plateau of performance has been reached, even with the most advanced equipment developments. Higher mine operating costs and lower metal prices have more than ever generated the need for breaking through these productivity barriers. After initial field testing The Robbins Company has designed and manufactured, on a joint venture basis with Mount Isa Mines, Ltd., Australia, a prototype "Mobile Miner" for continuous cutting of hard rock. This paper describes the cutting concept, the initial application of a completed 1,156 m (3792 ft.) long 14% decline, actual performance and delay analysis, developmental modifications, anticipated performances of a fully developed machine, and possible future applications. Sincere appreciation is expressed to the management of Mount Isa Mines, Ltd., for allowing access to the data used in this paper. The views expressed here are those of the author and not necessarily those of Mount Isa Mines, Ltd. INTRODUCTION A paper titled, "Design and Development of a Mobile Mining Machine", was presented by J.P. Kindsvater at the RETC, New York, in 1985. This paper described the evaluation of a test fixture in an andesite quarry near Seattle, followed by design, construction and

Jan 1, 1987

By H. D. R. Browner, D. A. Marsh

The need for a product dewatering step between the milling/classification and leach/carbon stages of gold plants has traditionally been performed by thickeners. Whether these be the 'conventional' or 'high-rate' types both require considerable initial capital outlay even without provision for standby facilities. In addition, their sensitivity (both mechanically and metallurgically) to changing feed conditions often results in these being considered 'high-risk' items of equipment, requiring a high degree of attention from operating personnel.

Jan 1, 1992

By Steve Kral

A near-record crowd of mining history enthusiasts made the trip to Leadville, CO in September to attend the National Mining Hall of Fame and Museum’s 19th induction banquet. Dressed in Victorian garb, black tie tuxedos and formal gowns, the 268 people honored four distinguished men who made a lasting impact on the U.S. mining industry. They joined 188 other inductees. The first induction banquet took place in 1988, with about 500 people attending.

Jan 1, 2007

By Bruce Geller

Attending the Prospectors and Developers Association of Canada (PDAC) meeting and exhibit has become an annual tradition for many in the mining industry. Similar to last year’s synopsis, this report is an overview of the 2003 conference from the eyes of a consulting mineralogist. It is supplemented by conversations with other participants. And it examines the conference handouts. Certain segments of the mining industry have seen improvement throughout the year in terms of metal prices, stronger demand and renewed interest by the investment community. Other segments continue their decline due to depressed commodity prices, higher oil prices, a continued weakness in the global economy and war uncertainties. SARS was known to the world, but it was not a Toronto epidemic during PDAC. In short, this year’s PDAC was permeated by an air of anxiety about the Middle East.

Jan 1, 2003

By Jonathan Baggett, Nino Ripepi, Amin Abbasi, Richard Bishop, Juan Monsalve, John Hole

This work focuses on the operational and safety issues associated with karst voids in large opening underground mines. Issues include water inrush, structural instability, and engineering uncertainty in these environments. Coupled with the fracturing prevalent in folded sedimentary rocks, karst voids are complex and challenging ground-control risks. Traditional methods of predicting karst void locations, such as probe drilling, are impeded by the inconsistent spatial distribution and variable sizes of the features as reported by Li et al. (J Rock Mechan Geotech Eng:232–242, 2010) and Hassan et al. (Procedia Chem 19:737–742, 2016). Ground-penetrating radar (GPR) is a geophysical technique that transmits radio waves into a medium and subsequently detects reflected waves via a receiver. The travel time and energy of received signals are then processed and interpreted. The difference in conductivity and dielectric permittivity between limestone and open karst cavities causes strong reflections. GPR is frequently used as a geophysical surveying technique in several industries; however, there is a lack of published research on underground mining GPR applications as reported by Zhao et al. (2015a; Geophys J Int:62–71, 2015b) and Eskelinen and Pellinen (Constr Build Mater:888–898, 2018). The purpose of this work is to demonstrate the use of GPR in an underground stone mine and to discuss the importance of karst void detection ahead of mining.

By J. I. Schoenherr, T. A. Baloun

Mixed cable waste, which amounts to more than 200,000 tpy in Germany, is subjected to recycling. In most cases cable recycling means only recovering copper and/or aluminum metals. The remaining cable waste contains nearly 3-8% of the reusable materials, and is disposed of in landfills. Aluminum is recovered within copper products and leads to lower product prices. Preliminary laboratory tests show that the use of shaking hydro-tables as well as electrostatic separators result in less than 1 % of metals in the residual material. The products are high in grade at metal recoveries of more than 85%. Furthermore, applying a modified electrostatic separator may also lead to an efficient Cu-Al separation. The separation efficiency amounts to up to 95%.

Jan 1, 2002

By I. J. Duckworth

Due to improved, stringent safety regulations, many modern road tunnels are statistically safer, per kilometer, than above ground roadways. However, the public perception and reaction in the event of a serious tunnel fire is very different to that associated with a surface incident. Vehicle fires in road and rail tunnels are recognized to represent an immediate and extreme danger to the patrons of those systems. Unlike workers in the mining and civil construction industries, the general public are neither trained nor equipped to fight fires or evacuate under deteriorating smoke conditions. Accordingly, for the majority of modern transportation tunnels the ventilation infrastructure is sized on the requirement to control the combustion products from worst-case fire scenarios and to provide a tenable evacuation route for the tunnel users. It is common for these same emergency ventilation systems to be employed, often in a reduced capacity, for other operating modes such as the dilution of pollutants during congested traffic conditions. This is one of the fundamental differences to mine ventilation, where primary ventilation systems are not typically sized based on fire scenarios. This paper presents an overview of the subject of fires in vehicular tunnels. This includes a brief history of major transportation tunnel fires followed by a discussion on the resulting legislation and standards that govern the design and operation of tunnel emergency ventilation systems. A summary is provided on the common criteria, theory, and design techniques that are employed during tunnel emergency ventilation systems design. Information is provided on fire detection and suppression, with a discussion on the growing acceptance of wet suppression as a means to mitigate major fires in road tunnels worldwide.

Jan 1, 2009