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By James J. Kabat, James A. McDonald

Impregilo/SA Healy JV recently completed this Project using the first slurry shield TBM’s in the United States. The Project used two TBM’s to mine 18,000 feet in sands, gravels, and silty alluvial materials under the Willamette River and downtown Portland, Oregon. This paper discusses alignment and geological conditions, equipment selection and plant setup, and tunnel excavation means and methods, parameters, and results. Extensive hyperbaric operations were required and will also be discussed.

Jan 1, 2007

By George S. Koch

We evaluate the exploration effort by diamond drilling for zinc in central Tennessee and southern Kentucky through a statistical analysis comparing the Middle Tennessee district with the older Tri-State and Upper Mississippi Valley districts. All of the ore deposits are of the Mississippi Valley type and are similar geologically. Through statistical analyses we attempt to answer these questions: Had the drilling density in the Middle Tennessee district been applied to the Tri-State district, how much of the ore in the Tri-State would have been discovered? Had this drilling been done in the Upper Mississippi Valley district, how much of the ore in that district would have been found? Which of these two older districts does Middle Tennessee more closely resemble in intensity of zinc mineralization? Is more drilling warranted in the Middle Tennessee district? Our data base includes tonnage and area distributions of ore deposits in the Tri-State dis¬trict, sizes of ore bodies and probabilities of their recognition in the three districts, and data for the Elmwood mine in the Middle Tennessee district. Our statistical analysis considers the consequences of drilling holes in the three districts on square grids at coarse, intermediate, and fine spacings. We conclude that the drilling pattern assumed for Middle Tennessee would have found some but not all of the ore in the two older districts. We believe that in intensity of mineralization Middle Tennessee more closely resembles the Tri-State than the Upper Mississippi Valley district, and that more drilling is warranted in the Middle Tennessee district.

Jan 1, 1979

By Lawrence F. Rooney

The wide distribution of limestone and dolomite and the decentralization of the depedent industries give the State Geological Survey a major role in the, development of these mineral resources. The amount of geological information necessary for efficient exploration is so large that few companies can afford to do the necessary basic field work or store the data. The state surveys fill these responsibilities and thus might be said to serve as the geological research departments of the limestone and dolomite industry. At the Indiana Geological Survey, the data of most value to limestone producers are in the form of unpublished measured sections, well records, cores, chemical analyses, directories, and geologic maps. Much of this information is published in summary form. The Survey also assists individual members of industry in exploration and evaluation of mineral deposits. In addition, a progressive State Survey provides the geological infor¬mation necessary for the development of new resources which do not appear to justify industry's own preliminary efforts.

Jan 1, 1966

When a company like Lonmin, the third largest platinum producer in the world, is mining one of the most precious metals in the world, time is money. Every piece of equipment is expected to be in top shape because every minute of downtime can add up to lost profit. Two different types of platinum ore are mined and processed by Lonmin, namely Merensky and UG2. Merensky has a grade of 3.5 g/t (0.1 oz/st) and UG2 has a grade of 4.5 g/t (0.13 oz/st). The mine also produces platinum group metals (PGM), which consist of platinum, osmium, palladium, rhodium, iridium and ruthenium. Although South Africa has more than 80 percent of the world?s PGM reserves, these minerals are very scarce. Lonmin is considered a low-cost producer of these minerals, generating 21.5 t (694,000 oz) of platinum and 18.6 t (600,000 oz) of PGMs in 2012. So when the company?s Karee K3 concentrator plant in Rustenburg, North West Province, South Africa, was experiencing high operating costs on the transfer points, a solution was needed.

Jan 1, 2012

By X. Wu

A quantitative damage evaluation caused by ground motions associated with strong roof caving is presented. The strong roofs are modeled as either cantilevering or bridging beams over continuous elastic foundations subject to an exponentially distributed vertical stress. Major factors influencing roof caveability and strain energy buildup are identified and investigated. A methodology to evaluate the strain energy accumulation caused by overhanging roof is presented. The potential for mine tremors is determined in terms of the local Richter magnitude ML which depends on the seismic energy transformed from the stored strain energy released when the roof fails. A particle velocity model is applied to estimate the damage area associated with roof collapse. A case study from a Utah coal mine shows that estimations of bump severity and damage area agree well with the field observations.

Jan 1, 1995

By J. A. Herbst

In spite of potential theoretical and economic advantages of large-diameter ball mills, many manufacturers elect not to build these mills owing to what is perceived as an excessively large design risk. This risk results from the fact that traditional predictions for mill-scale-up to large diameters are not always accurate. It is apparent that alternative methods of analysis and scale-up are required. Recent studies have shown that detailed population balance models which account for important grinding subprocesses, i.e., grinding kinetics, material transport, and classification, are capable of predicting the performance of small- and intermediate diameter mills (up to 4.3 m (14 ft)) from small-scale batch tests. These same models are used in the current study to predict the performance of a "borderline" large ball mill (4.7x5.5 m) at Asarco's Sacaton operation, a ball mill (5.0x5.8 m) at Kennecott's Chino operation, and one of the world's largest ball mills (5.5x6.1 m), at Cities Service Pinto Valley operation. Model parameters required for scale-up have been estimated in a 380-mm diameter batch mill. Predictions are compared with the results of detailed plant sampling in the three plants. For the Sacaton and Chino operations, the error of the predictions was found to be less than 2.5%, while the corresponding error for the Pinto Valley operation was less than 2.7%. It is concluded that proper representation of the major subprocesses of grinding in the model equation is the key to achieving accurate scale-up. Of special importance is the need to account for the size distribution of the grinding media and the influence of the size distribution environment in the mill on grinding kinetics.

Jan 1, 1983

By Mark Van Dyke, Ted Klemetti, Joe Wickline

"The identification and mitigation of adverse geologic conditions are critical to the safety and productivity of underground coal mining operations. To anticipate and mitigate adverse geologic conditions, a formal method to evaluate geotechnical factors must be established. Each mine is unique and has its own separate approach for defining what an adverse geological condition consists of. The collection of geologic data is a first critical step to creating a geological database to map these hazards efficiently and effectively. Many considerations must be taken into account, such as lithology of immediate roof and floor strata, seam height, gas and oil wells, faults, depressions in the mine floor (water) and increases in floor elevation (gas), overburden, streams and horizontal stress directions, amongst many other factors.Once geologic data is collected, it can be refined and integrated into a database that can be used to develop maps showing the trend, orientation, and extent of the adverse geological conditions. This information, delivered in a timely manner, allows mining personnel to be proactive in mine planning and support implementations, ultimately reducing the impacts of these features. This paper covers geologic exploratory methods, data organization, and the value of collecting and interpreting geologic information in coal mines to enhance safety and production.The implementation of the methods described above have been proven effective in predicting and mitigating adverse geologic conditions in underground coal mining. Consistent re-evaluation of data collection methods, geologic interpretations, mapping procedures, and communication techniques ensures continuous improvement in the accuracy of predictions and mitigation of adverse geologic conditions. Providing a concise record of the work previously done to track geologic conditions at a mine will allow for the smoothest transition during employee turnover and transitions. With refinements and standardization of data collection methods, such as those described in this paper, along with improvement in technology, the evaluation of adverse geologic conditions will evolve and continue to improve the safety and productivity of underground coal mining."

Jan 1, 2019

By Mark Van Dyke, Ted Klemetti, Jake Beale, Zoheir Khademian, Joe Wickline

In 2016, a 3.7-ML magnitude event caused by mining activity occurred at a longwall mine in southwestern Virginia which was recorded by the United States Geological Survey (USGS) and felt by local residents. The event was the largest of its kind since a global mine design change by the operator was instituted in 2008 following three large events in 2005, 2006, and 2007 (3.4, 4.3, and 3.4 Moment Magnitude (Mw), respectively). Two of the three pre-2008 events (2005 and 2007) damaged ventilation controls in the mine which fueled a mine fire. In 2016, the mine’s management requested researchers from the National Institute for Occupational Safety and Health (NIOSH) to access geological data and determine what parameters could possibly lead to events of a magnitude of 1.0 ML or greater. Evaluation of 2152 geological data points and modeling revealed three major geological factors in common with the majority of the 181 recorded +1.0 ML events from 2009 through 2016. Three levels of seismic potential were identified as follows:

Aug 4, 2023

By H. Simpson

Middelburg mine is an opencast export mine operating in the Eastern Transvaal Coalfields of the Republic of South Africa (Figure 1). The mine was commissioned in 1983, to its original design capacity of 4.25 million sales tonnes which was subsequently raised to 5.5 million sales tonnes in 1989. This increase in export tonnage was brought about through an increase in the mines export allocation and the revision of management strategies. The maintenance of this increased tonnage with minimal additional capital has been achieved through improved operational efficiencies and the upgrading of planning operations through the purchase of an Enhanced Mine Scheduling Software Package (EMSSP/MINESTAR). Simultaneously with this requirement were additional factors that contributed to the implementation of the EMSSP. The mine was owned by a joint venture of two partners and is operated by Middelburg Mine services (Rand Mines Pty. Ltd) (Figure 2). This structure of ownership required the evaluation of numerous planning options to be under-taken concurrently and hence the need for an efficient streamlined scheduling pack-age that could fulfill this requirement. Compounding the EMSSP needs further, were the problems experienced in the export market, these being the external pressure from current and new suppliers in the market place which obliged management to provide solutions to rapidly changing market conditions. These fluctuating market conditions have had a direct effect upon the mine's planning strategies because of the large percentage of the mine?s sales sold on the international spot market. The sanction factor for all South African exporters has had a negative effect upon price and this was compounded further through internal competition in 1987 via suppliers attempting to maintain the market position.

Jan 1, 1991

By R. Tamblyn

Vertically stirred media mills are a highly effective low-footprint solution for the ultrafine grinding of industrial minerals. This work investigates the effect of media density on flow patterns within the mill. Direct irradiation of a media particle leads to decay through positron emission, consequently forming two anti-parallel gamma rays, which allow for the real time tracking of particle position. Grinding media of the same size, but with a range of specific gravities are followed using this method, and the effect on the flow within the mill is revealed. The technique is seen to be an effective method to highlight the velocity profiles within the mill, as well as the zones where grinding is less efficient ? areas of relatively low velocity and high residence time. The changing media is seen to effect the overall flow patterns within the mill, having consequential effects on the efficiency of the grind.

Jan 1, 2009

"The Mine Haul Road Optimization Alliance is an Australian industry-academia collaboration which has been developed to support mine haul road operators by fully integrating mine road design research solutions with industry end-user service providers to design, assess, implement and monitor the various equipment, materials and road management strategies required to optimize the safety, environmental and economic performance of a haul road. Initially, a broad overview of the university-industry collaborative landscape is presented, following which the current situation in the Australian mining sector is reviewed both nationally, and on a country-wide basis, internationally. This insight places realization of a collaboration between Curtin University Western Australian School of Mines Mining Engineering and Metallurgical Engineering (WASM ME2) and the Haul Road Optimization Alliance (HROA) industry members into context of opportunity. Following an overview of the HROA collaborative structure, aims and objectives, it is shown how academia and industry can collaborate to deliver a more robust solution to mine haul road design, performance or management needs, especially where integrated solutions are needed. Critically in this approach, implementation and monitoring data provided by industry and service-providers alike forms the foundation on which to develop research knowledge and innovation that is more responsive to the end-user requirements, typically represented by ‘early goals’ and implementable solutions. The paper concludes with examples of how the alliance collaborations work in practice to deliver improved mine haul road designs and optimized operational performance, together with the mechanisms used to ensure industry needs are met through focused, end-user driven research and integrated solutions implementation."

Jan 1, 2016

By Terry O. Arney

This paper is a description of the digital Data Acquisition and control System that is installed at Cities Service's Pinto Valley Concentrator. Pinto Valley Concentrator ? The Pinto Valley Concentrator (5, 41 is located approximately seven miles west of the town of Miami, Arizona. The Concentrator is situated south of the open pit mine and was designed to process 40,000 tons of ore per day with an average grade of .45% copper. The comminution process consists of primary, secondary, and tertiary crushing, and single-stage closed-circuit grinding 161. Concentration of the copper sulfides is by means of froth flotation. Concentrates are transferred to the Inspiration Consolidated Copper Company smelter in Miami, Arizona through a slurry pipeline.

Jan 1, 1976

By R. W. Leonardson

Tectonic activity in northern New Mexico during late Oligocene and early Miocene time presaged events which led to the development of molybdenite deposits at Questa. East-northeast directed crustal extension produced north-northwest striking tensional fracture systems paralleling the early Rio Grande rift. A sequence of Oligocene andesite flows and breccias is overlain by a thick early Miocene rhyolite ash-flow tuff. Eruption of the tuff initiated collapse of the Questa cauldron: the south margin of which occurs as an east-northeast striking, north-dipping structurally weak zone. Continued east-northeast post-cauldron extension permitted the high level emplacement of granite stocks with coeval rotational deformation of fault blocks composed of cauldron fill and [ ] floor. The stocks occupy north-northwest fracture zones in the south margin of the cauldron, and porphyry dikes occupy east- northeast striking faults that define the south margin. These two fracture systems have played a dominant role in localizing the intrusive porphyries and associated mineral deposits at Questa. A molybdenite-bearing breccia matrix and related stockwork mineralization generally occur within volcanic rocks. Mineral deposits are spatially related to fault zones and the upper con- tact of their source intrusives. Deposits are localized in fault zones up to several thousand feet long and 100 to 500 feet in diameter. Magmatic-hydrothermal solutions from the source aplite porphyries have produced potash metasomatic alteration which is strongly centered on the mineral and ore zones. Alteration in ore is represented by orthoclase, quartz and secondary biotite. This pattern grades into secondary biotite and propylitic zones forming successively weaker alteration assemblages away from ore. Younger phyllic and argillic assemblages are particularly widespread only where strong north-northwest extensional fracture zones cross the south cauldron margin.

Jan 1, 2013

By Bruce A. McKinstry

Introduction For many major mining projects the time frame from initial planning to production can be measured in decades. Hecla's Silver Shaft project, scheduled to go into production by the end of this year, includes a complete surface facility, shaft with an ultimate depth of 2.4 km (7,700 ft), complete ore pass and loading pocket system, and 610 m (2,000 ft) of development drifting and stope preparation. The project was conceived in the fall of 1979, and the duration of a mere four years from conceptual engineering to production is testimony to what can be accomplished when a mining company and a contractor work as a team rather than developing into two warring camps, as often happens. Engineering In 1979, Hecla Mining Co. awarded a contract to J. S. Redpath Corp. to perform feasibility investigations and design engineering related to a proposed new shaft facility at the Lucky Friday Mine. The Lucky Friday, in Mullan, ID, is a major producer of silver, as well as significant quantities of lead and some zinc. In late 1979, stoping was in prog-

Jan 10, 1983

By K. A. Grace

"An ore is a rock regardless of its rarity or value."* The application of geology does not cease with the discovery and delineation of a mineral resource, but continues in the calculation of the economic parameters that determine reserves. Reserve determination, reduced to essentials, is the determination of the cost of production of a mineral commodity from a resource. This cost comprises mining, processing, waste disposal, reclamation and marketing costs. Geological input is vital in the calculation of the individual cost parameters from mining to reclamation, and even has some impact on marketing. Geology thus has a critical role in the determination of reserves.

Jan 1, 1985

By Alan D. Randolph

A size-continuous breakage kinetics model is postulated and supported with industrial grinding mill data. It is shown that the kinetics parameters include the effects of possible classification at the mill discharge. The estimated parameters were then used in the kinetics model to simulate the behavior of a grinding mill in open and closed circuit operation. While material transport and kinetics are equally important in open loop operation, heavy recycle in a closed circuit make a detailed material transport model for grinding unnecessary. In effect, the mill can be considered as backmixed. This suggests that more emphasis should be placed on modeling the classifier than the development of detailed material transport models for the grinding mill.

Jan 1, 1975

By Harrison A. Schmitt

During .the past five decades or so we have passed from a time when it was difficult to point to a mine or an ore body and verify that it had been discovered by geological methods, through the. Twenties when the common saying was, "Who ever heard of a mine found by a geologist?", to recent decades when hundreds of mines and ore bodies are acknowledged geological discoveries and the above query can be ignored. Recently, however, the application of mining geology appears to have been downgraded, or so it seems to me. Basic geology in mining has been cheapened and glossed over in favor of geophysics and outcrop sampling, even though the latter is merely one technique of mining geology and, to some extent anyhow, has been used for a. long time. (Locke, 3, pp 81-87). Geophysics by itself and in conjunction with geology has had success in certain geological provinces, but limited attainment in mountainous terrane except in those few cases where strongly magnetic minerals are associated with ore. Nevertheless, in the Cordillera .many experimental techniques are offered as proved ones. This is not an intent to try to depreciate honest geo- physics. Continued experimentation and use of it is approved by all, but at the same time it is foolhardy to throw mining geology overboard, Generally both approaches should be considered and usually, at first anyhow, geology is the most direct one.

Jan 1, 1960

By Luzheng Chen

The study aimed to evaluate the separation performance of a full-scale continuous centrifugal concentrator in the reconcentration of fine hematite from high-gradient magnetic separation (HGMS) concentrate in a tailings recovery plant, and to investigate the usefulness of the technology in industrial applications. The effect of changing the operating variables on concentrate grade and recovery was studied. The results indicate that among the variables considered in the study (water spray pressure, centrifugal acceleration, feed volume flow rate, feed percent solids and the reciprocation and spacing of water sprays), the change in centrifugal acceleration affects the recovery the most and continuous concentration can be achieved only when the water spray has a sufficient pressure. In addition, the reciprocation and spacing of the water sprays have a significant influence on the concentrate grade. Although performance of the full-scale concentrator is slightly inferior to pilot-scale trials, due to limitations in the scale-up design and the fluctuations of feed material characteristics, this concentrator provides a potential way to achieve continuous concentration and obtain a high-grade concentrate from tailings.

Jan 1, 2010

By Stephen C. Moore

The Grossschloppen vein-uranium deposit, Bavaria, West Germany, was examined utilizing underground workings during 1980-82 by Esso Erz GMbH, an affiliate of Exxon Minerals Company (EMC). Geologic evaluation entailed dense drilling of a portion of the deposit from workings constructed specifically for the program. Discovered in 1977, the deposit was initially explored by surface diamond drillholes which allowed definition of a 30-60 m wide vein system discontinuously mineralized along a 1000 m strike length and to at least a 450 m depth. The underground program was conceived as a cost effective procedure to answer questions on vein correlation, grade continuity and variability. A 1200 m decline allowed access for detailed sampling of approximately 10% of the known area of mineralization. Fanned drillholes, logged by gaga probe, were spaced to provide intersections of veins at 10 to 20 m intervals. Six cross cuts also penetrate the pitchblende and uranophane mineralization which occurs in 0.1 to 2.5 as thick quartz veins. Detailed cross-sections and level plans were constructed for resource estimates of the intensively studied portion of the vein system. The program resulted in the discovery of local, high grade areas and an average grade in the evaluated area nearly double that expected from surface drilling.

Jan 1, 1983

A machine that improves safety during the cutting of boxholes (ore-passes) and travelways in underground mining operations has delivered impressive results in trials conducted at a South African platinum mine. The technology is a joint effort by Sandvik Mining and Construction and platinum mining company Lonmin. The ABH 1600 boxhole borer was built by Voest-Alpine Bergtechnik, Sandvik’s Austrian subsidiary. It was delivered to the Lonmin Eastern platinum mine in February 2005. There, it was deployed underground on the Number 8 Level (320 m or 1,050 ft below the surface) at the mine’s Newman incline shaft.

Jan 1, 2006