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By N. D. Jagger

In order to maximize the benefits obtained from flocculating agents when used as settling aids in high rate and conventional thickeners, it is often necessary to dilute the thickener feed prior to flocculant addition. In some cases, no flocculation at all is possible unless dilution water is used. The most common method of diluting thickener feed has been to recirculate some of the thickener overflow by means of a centrifugal pumping system. This represents a significant capital and operating cost. Supaflo Technologies of Australia has developed and patented an internal recirculation method known as Auto Dilution (or "Autodil") which is based on the principle that an hydraulic head differential exists between the inside and outside of the feedwell because of the higher S. G. of the pulp inside the feedwell, By installing non-return ports in the feedwell wall at the appropriate level, supernatant solution flows into the feedwell at a calculated rate and dilutes the feed without any need for external recirculation of overflow.

Jan 1, 1993

By A. Bruynesteyn

Procedures are discussed to determine if a waste material can become acid producing when left exposed to the environment. When wastes proves to be acid producing, methods are described that can be used to determine the characteristics of the effluents produced from a commercial size waste dump, taking into consideration that large quantities of pollutants can accumulate inside a waste dump during dry periods. The length of such dry periods and the quantity of rainfall greatly affect effluent characteristics.

Jan 1, 1980

By Mark R. Stanton, Douglas B. Yager

Integration and synthesis of mine-site topography, geophysical, and geochemical data yields both two- dimensional and three-Amensional perspective models for the May Day mine located in the Cement Creek drainage near Silverton, Colorado. Induced polarization, geophysical data are spatially registered with geochemical data acquired from drill hole cuttings that are contoured m three-dimensional space, thereby permitting determination of the most metalliferous and sulfur rich zones of a waste pile. This spatial modeling application was developed to be a visually intuitive tool to aid in mine waste reclamation.

Jan 1, 2000

By L. Sletmoen, P. Rocque, E. DeSouza

Plans for achieving planned production rates at the Red Lake Mine High Grade Ore Zone required that the mine ventilation system be upgraded. Time constraints required that only a site assessment of the mine ventilation system be performed followed by recommendations for providing adequate ventilation conditions at the production zone. This paper describes the engineering assessment, design and commissioning of the ventilation system upgrade for achieving increased flows at the high grade ore zone. The work was successfully achieved with minimal capital expenditures and disruption to the mining cycle.

Jan 1, 2003

Successful longwall gate entry design requires control of vertical and horizontal stresses. Vertical, or overburden, stresses are most severe in the tailgate where they are concentrated by longwall panel extraction. Horizontal stresses can also be highly destructive but they are less well understood. This paper discusses measurements of in situ horizontal stress fields in the eastern United States, experience with horizontal stress in longwall mines and methods for predicting and controlling horizontal stresses. The information presented was collected through site investigations at 45 US longwalls and an international literature review.

Jan 1, 1992

By B. Dabrowski, J. D. Miller, D. Halbe, J. Hupka

An air-sparged hydrocyclone (ASH) mobile system was evaluated for continuous stripping and recovery of cyanide (the AVR process) from process water at a gold plant site. The ASH unit performed exceptionally well as an absorber. HCN was removed from the gas phase in a single one second pass with an efficiency exceeding 99%. HCN concentration in the discharged gas phase was lower than 10 ppm, which provided for a safe working environment. The stripping efficiency, controlled by the Henry’s Law constant, exceeded 40% in one pass.

Jan 1, 2004

By R. Debkowski

Mining methods used to protect the workings in underground salt mines against the destructive activity of natural factors are presented in this paper. Major hazards and methods of elimination of their impact on the stability of workings, were determined. Old and modern technical means and technologies used for protection and preservation of the selected most interesting sites were characterized. The results of surveys and studies allowed proposing the change of mine structure i.e. dividing it into monumental and not-monumental part, which should improve execution of necessary protective works.

Jan 1, 2006

By Alfredo Valdivia, Jesus Schabib, Vojtech Gall, William Cao, Curt Cicileo, Andrew J. Thompson

"The East Side Access Project (ESA) involves the construction of geometrically complex underground structures including a large number of caverns and bifurcations. Initially conceived as dual lined structures with either traditional concrete or shotcrete final linings (SFL), construction economy, advances in concrete placement technology and scheduling among others led to a wide use of what is referred to as freeform or pneumatically applied concrete (PAC) for the construction of tunnel final linings. PAC is a method of applying concrete without using formwork, where a wet mix concrete is pneumatically installed to encase reinforcement to full lining thickness. PAC has been widely adopted at ESA well beyond initial expectations. The paper addresses the design and construction aspects of the PAC method and contrasts it to traditional SFL lining placement. The experience made provides guidance for future PAC and SFL applications. THE EAST SIDE ACCESS PROJECT AND USE OF FREEFORM CONCRETE The Long Island Rail Road (LIRR) currently transports commuters from Long Island into Manhattan, terminating at the already congested Penn Station on the west side of Manhattan. Once completed, the ESA Project will provide LIRR commuters direct access to the east side of Manhattan underneath Grand Central Terminal. The ESA Project will help alleviate the congestion at Penn Station, which currently accommodates New Jersey Transit, Amtrak, and LIRR lines; reduce travel time for LIRR passengers traveling to the east side of Manhattan and facilitate connections to the New York City Transit (NYCT) Subway System and Metro North Rail Road. The construction includes mining and lining of new tunnels and facilities under Manhattan and Queens. The tunnels run from Queen’s Sunny Side Yard through the existing 63rd St. Tunnel, underneath Manhattan’s Park Avenue until termination at 37th Street. Differing types of tunneling methods and final lining systems are being used depending on the ground conditions, geometry and size of the excavation, site constraints and functional requirements. Mining of the Queens segment of the ESA Project involved soft ground tunneling by pressurized face tunnel boring machines, cut and cover construction, and conventional tunneling. The Manhattan segment of the ESA Project involves mining in hard rock by tunnel boring machines, drill and blast, and road header."

Jan 1, 2016

By B. Campbell

This paper will detail the successful construction methods of a 20- foot diameter wet well shaft, approximately 180 feet deep in overall depth and 150-feet below the water table, adjacent to Lake Nacimiento, in San Luis Obispo County, California. In addition to this, highlights will include the selection process in determining the most economical support of excavation, while minimizing risk of large water inflows as indicated in the Owner?s Geotechnical Baseline Report (GBR).

Jan 1, 2010

By A. Delgado-Jiménez, O. J. Restrepo-Baena, G. Aristazabal

"Mining industry as a source of raw material is essential to society however, it lacks of good reputation due to the type of management historically applied to many of its social and environmental impacts. It is argued that this situation has hampered the obtaining of social license to operate of a lot of mining projects around the world. The last considerations are very common in Latin American countries. As a result, the mining sector has understood that the viability of the business long term is associated with more profit for the shareholders but also with activities that improve the livelihoods of local communities, enhance the capabilities of local governments and preserve the ecosystems around the projects. Nevertheless, recent studios have shown that most of the current advances to incorporate sustainability concepts in mining have been mainly focused on control and the prevention of environmental and social impacts of extractive activities. Thus, contributing to the development of territories around mining projects constitutes a fundamental aspect of the business competitiveness through reducing cost and risks of stopping projects, innovating new ways of relationship with stakeholders, improving the level of reputation of the industry as well as its position in the market. However, this contribution requires formal strategies and models that enable companies understand the different resources in the territories where their mining activities are developed and those resource transformations, in order to establish the best way to articulate the project with the territory, pursuing an effective contribution to its development, truly sustainable over time even after the mine closure. CONTEXT Currently in the world but especially in developing countries such as Latin Americans, different stakeholders are increasingly vigilant of how mining companies carry out their activities in terms of socio-economic and environmental management of territories, not only for its impact on the livelihoods of the communities that inhabit them, but also because many demanders of raw materials -both countries and companies- have set sustainability standards as a prerequisite to establishing business relationships with mining companies, such as the recently declared Sustainable Development Goals by 2030 (UN, 2015). Accordingly, decide underinvest or not to invest in sustainability issues carries risks for mining companies. However, invest much in the wrong way may involve the same risks. Managers are concerned to ensure profits, and therefore they decide carefully how to invest in the areas of production, R & D or marketing. Likewise, they should think strategically about investing in initiatives related to sustainability. This if they really want that those investments in fact help to improve the competitiveness of the company. The mining industry benefits from natural capital that extracts, so it should implement strategies that lead to remunerate such benefit to the territories (Almaguer, 2007). One option is through the transformation of natural capital in other types of non-existent capital or poorly developed in their areas of influence. In this way, the value generated by the extraction of underground resources is shared and additionally contributing to improving the quality of life of the communities. Historically, mining industry has been into several problems to achieve this, which represents one of the aspects that has most influenced the current reputation of mining industry in some regions of Latin America. Many communities, local governments and civil society organizations continue to associate this activity with the destruction of the social fabric and ecosystems in the territories, and their opposition against companies working in the areas has led to affect the operational continuity of many projects (Hamann, 2003; Prno and Scott, 2012; Slack, 2012)."

Jan 1, 2017

By Carol Cox Russell

More than two thousand abandoned mines within the Animas watershed in Southwestern Colorado are being prioritized for remediation by the Animas River Stakeholders Group (ARSG). Phased collection and assessment of information progressed from large scale to site specific. Prioritization was based on existing or potential environmental impact and technical feasibility of remediation as measured by dissolved Cd, Cu, and/or Zn in the discharge; indicators of habitat degradation; aquatic life in streams; cumulative impacts at the point of compliance; cost effectiveness; treatiblity/feasibility; and cultural and historic preservation.

Jan 1, 2000

By H. Ouellet, J. Paraszczak

The pneumatic jackleg drill remains a widely used tool in development and production drilling in many small-scale and narrow-vein underground mining operations in North America. Several drawbacks of this technology (unsatisfactory drilling rate, noise, vibration, presence of oil mist, etc.) and the successful introduction of water-powered jackleg drills in South Africa have stimulated the interest of many mine operators. The performance of both drill types have been tested in a mine site in Northwestern Quebec, Canada. Results of the testing of penetration and advance rates as well as environmental aspects are presented. They show a superiority of water-powered drills, even though the difference in performance is less significant than that reported from South Africa. Further research avenues are proposed to better evaluate the potential of water drilling technology in North American metal mines.

Jan 1, 1995

By John A. Shuster

Case histories are reported for several soft ground shafts ranging from 6' to 40' in diameter and 50' to 230' in overburden depth for which ground freezing was employed to provide temporary ground support and groundwater control during shaft sinking through the overburden. Cases reported emphasize dealing with difficult site and ground conditions such as working within existing buildings, through very soft, running and bouldery soils, in the presence of substantial lateral groundwater flows, and into salt dome deposits requiring special considerations. Construction procedures, schedule, and relative costs are discussed for each case.

Jan 1, 1985

By D. D. Eyer

New or improved technology will continue to drive productivity improvements through the next decade. In January 1988, I presented a paper titled, "Large Underground Mines of the 1990s? before the SME. I will follow some of the themes developed in that paper as modified by our experience in the past two years. In order for a coal company to be profitable today, it has had to reduce unit costs experienced in the past. This is because the current average realization, even accounting for a recent strengthening, remains below that of a few years ago. Doing business as was done in the past is not good enough. The coal industry needs to increase productivity in the range of 5-10% annually merely to stay even with rising costs. Underground productivity has been increasing more rapidly than that for surface mining. With the exception of the Powder River basin of Montana and Wyoming, underground productivity has caught up with that for surface mining in many regions of America. There are a number of technological factors which have attributed to increases in underground productivity and which should be factors in the future.

Jan 1, 1990

By Subhash Sethi

The WIPP (Waste Isolation Pilot Plant) Project near Carlsbad, New Mexico. is a research and development project sponsored by the U.S. Department of Energy, designed to demonstrate the safe disposal of radioactive waste. A mine (repository) is being developed 2150 feet below the surface in a thick salt bed, which will serve as the disposal medium. The underground ventilation system for the WIPP project was originally designed based on a fixed project scope. The design criteria and ventilation requirements were developed for the performance of various activities as then envisioned towards the achievement of this goal. However, in light of new information and actual site-specific experience at WIPP leading to a clearer definition of the scope-related programs and activities, it was realized that the existing ventilation system may need to be modified. A re-assessment of the ventilation requirements--based on the current status of the facility and a clearer definition of the scope of the experimental programs, waste storage methodology, mine developmental activities. and current equipment list--indicates a two- fold increase in underground airflows from 210,000 cubic feet per minute (cfm) to 425,000 cfm. Various options to provide the increased airflow to the underground facility were considered and analyzed. Based on the techno-economic analysis, safety and environ- mental considerations, and other conditions unique to a facility like WIPP, it was decided to construct a new shaft to serve as the primary fresh air intake, along with the installation of additional fans in parallel with the existing set up. Low cost and the ease with which the new design could be implemented and integrated into the existing ventilation system with minimum impact on current activities and projected schedules were the guiding factors in designing the shaft and related ventilation modifications.

Jan 1, 1987

By Michael Fellows

Epidote is a common hydrothermal alteration product in many copper deposits of the southwestern United States. In many of these deposits epidote, along with calcite and chlorite, generally characterize a distal or halo propylitic alteration assemblage, but the mineral can occur within the central potassic alteration zone as well. Epidote is also a common alteration mineral in deposits formed in calcareous host rocks -- the skarn or pyrometasomatic ore bodies. Within the past 15 years, studies of the major and trace element composition of other alteration phases, principally biotite, associated with base metal ore deposits have demonstrated that some hydrothermal alteration minerals are compositional distinct from their igneous or metamorphic counterparts: However, the use of major and minor element content to identify and zero in on mineral¬ized areas does not appear to be very promising. Little work has been published upon the geochemistry of epidote from this standpoint and the results of my work suggest that a similar conclusion can be applied to epidote. My work (Fellows, 1976) suggests that epidote minerals in hydrothermal alteration suites from porphyry copper deposits in the southwestern United States are generally iron-rich rather than aluminum-rich. As a group, these alteration minerals differ compositionally from epidotes of regional metamorphic terrains. I ascribe these differences to the variations in the oxidation character of the respective environments. However, it appears as though the use of major element compositional variations of epidotes as an exploration tool is severely limited. Epidote is a complex calcium-aluminum silicate. Replacement of aluminum by ferric iron establishes a solid solution series between

Jan 1, 1977

By J. G. Wargo

In situ leaching of disseminate gold deposits has been studied from a theoretical perspective to outline the operating environment for the process. Rock permeability and the relationship of permeability to the site of gold particle deposition are key factors in predicting the efficiency of in situ leaching. Permeability measurements, however, have rarely been made during gold exploration, so that secondary geologic features of the deposit must be used. This paper examines some of the geologic characteristics of disseminated gold deposits and comments on the problems and possibilities of in situ leaching of gold.

Jan 1, 1987

By John Greenhalgh, Benoit De Rivaz

"1.INTRODUCTIONThis paper is based on the Lee Tunnel project, which is part of the Thames Water’s Tideway Project.The client Thames Water has employed a Joint Venture of Morgan Sindall/Vinci Grand Projets and Bachy Soletanche to undertake the design and construction of the project under the management of CH2M Hill at a value in excess of £635 million ($990 million). The 3 main elements of the tunnel project are the permanent lining to the shafts, the precast segmental lining, and the secondary tunnel lining. All 3 are reinforced with different types of Dramix steel wire fibers and each element will be described in this paper. This paper will explain the basic structural design of FRC (Fiber reinforced concrete) based on the post cracking residual strength and will describe all the steps of this project, the testing program realized to support innovative design and the main technical learning point. 2.BASIC CONCEPT OF STRUCTURAL DESIGN OF FRCStructural design of FRC elements is based on the post-cracking residual strength provided by fiberreinforcement. Other cases, like early age crack-control or fire resistance, are considered non-structural use of FRC. For structural use, a minimum mechanical performance of FRC must be guaranteed. Fibers can be used to improve the behavior at SLS (Service Limit State) since they can reduce crack spacing and crack width, thereby improving durability and they can be used to improve the behavior at ULS (Ultimate Limit State) where they can partially or totally substitute conventional reinforcement in most conditions. In the design process, the definition of the performance expected from the material is a key factor and the mix-design of the material has to be optimized for the required structural performance.2.1 Testing Method In order to ascertain the structural requirements requested for the FRC segments, preliminary testing on samples will be required and the effectiveness of the proposed solution will also be assured by the testing of full scale specimens. Structural design of FRC elements is based on the post-cracking residual strength provided by fiber reinforcement. For structural use, a minimum mechanical performance of FRC must be guaranteed. Nominal values of the material properties can be determined by performing a 3-point bending test on a notched beam according to EN14651 (figure 1) or by performing the ASTM C1609 beam test:"

Jan 1, 2016

By R. C. Schmidt

The Mont Klahoyo magnetite deposit is located about 600 km northwest of Abidjan, Ivory Coast. During an exploration period ending in 1977 an international joint venture group investigated the deposit and proved reserves of 670 million tons grading 36% iron. The deposit, occurring at the northeast end of the Baoubly-Kiriao chain of Precambrian iron formations, is associated with amphibolites, pyroxenites and gneisses of the Liberian Shield. At Mont Klahoyo occur two separate iron formations of which the lower member is the ore body. This lower member consists of a highly metamorphosed - banded quartz-magnetite iron formation in which iron silicate bands alternate with beds of quartz-magnetite. mphibolite-pyroxenites and sillimanite-cordierite-garnet gneisses form hanging and footwall rocks. The iron formation has been folded into an elongated overturned "Z" shaped major drag fold with axes trending and plunging approximately northeast. Beds are vertical or dip steeply to the southeast. The ore zone has an average thickness of 130 m and outcrops intermittently over a distance of approximately 5.5 km. Based upon detailed studies of drill cores and the results of ore dressing test work, eight stratigraphic units, identified as K-1 to K-8, are recognizable in the iron formation. Four interbedded units are low grade silicate zones (silicate facies) with the remaining quartz-magnetite units (oxide facies) repre¬senting the important ore zones of the Mont Klahoyo deposit. The ore-bearing "K" units are subdivided further, based upon their specific lithologies, iron content and concentration characteristics, into eleven ore types. The identification of these ore types is considered particularly important to mine planning and flowsheet design. A cap of oxidized materials overlies the primary quartz-magnetite iron formation but no enrichment has occurred. It is proposed that the Mont Kalhoyo iron formations were deposited, possibly chemically, in a volcanic environment as a siliceous iron formation with volcanism providing the primary source of iron and silica. Metamorphism converted the siliceous iron formation to a relatively coarse-grained quartz-magnetite-silicate iron formation.

Jan 1, 1979

By R. D. Lord

This paper deals with the search for the best practical means of storing sulphide bearing tailings, where there is no residual excess of carbonate material. It is the common experience that the sulphide content decomposes, with the aid of bacterial action, and the resulting sulphuric acid escapes, along with any heavy metal solutes, through embankments that are usually porous to some degree. The problem is typified in the tailings of the uranium operations of Elliot Lake, Ontario, where mining started some 20 years ago. The approach to tailings disposal paralleled the practice for other hydrometallurgical plants treating gold and base metal ores. Impoundment areas were designed to retain solids, and a clear and neutral overflow was considered satisfactory practice. Now experience has shown that these areas, some idle for over a dozen years, release acids, in seepage and overflows, to an unacceptable degree. To protect natural water courses neutralizing plants are operated wherever required. Lime slurry is fed continuously into the tailings outflows in a quantity sufficient to raise the pH to 8.5 and precipitate heavy metals that may be in solution. The objection to this procedure is that the plants will require servicing indefinitely, unless a better remedy is found.

Jan 1, 1975