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By Rebecca Boakye, Zohreh Kazemi Motlagh, Virginia T. McLemore

The most significant uranium (U) deposits in New Mexico are sandstone-hosted deposits in the Morrison Formation (Westwater Canyon Member), where >169,500 short tons of U3O8 were produced from 1950 to 2002. In addition, >9076 pounds of vanadium (V, a critical mineral) and some molybdenum (Mo) were produced from these deposits. These and other U deposits (limestone-hosted, U-veins) in New Mexico also contain critical minerals. Critical minerals are mineral resources that are essential to our economy and whose supply may be disrupted; many critical minerals are 100% imported into the U.S. Some sandstonehosted, limestone-hosted, and U-vein deposits are elevated in heavy rare earth elements. One sandstone-hosted sample contained 0.3 ppm Re (critical mineral), 659 ppm Se and 408 ppm Mo. The arsenide five-element vein deposits in the Black Hawk district are mineralogically and texturally complex, low- to moderate-temperature, hydrothermal, structurally-controlled, Ag-Co-Ni-Bi-As bearing carbonate vein systems with local minor elements. Mineralized samples from Black Hawk contain up to 9970 ppm Ag, 8540 ppm As, 5690 ppm Co, 72,400 ppm Ni, 57 ppm Bi, 165 ppm Sb, and 32,600 ppm U.

Feb 22, 2026

By B. Radwanek-Bak

The assurance of future raw materials supply to the EU mineral industry has become, in recent years, one of the most important tasks of the EU Commission. It is focused on creation a new mineral policy within the EU zone. One of the starting points for this activity was identification of the mineral commodities that are critical for the sustainable development and technological progress. The paper presents the glance to this problem from the National Member level. Domestic mineral reserve base as a possible source of critical raw materials for the EU was shown. Poland cannot be considered as its resource base. The source of these raw materials are not only scarce in Poland, but also they are not produced, and their demand is now - and according to forecasts is going to be in the future - met by imports. The raw materials in question are not considered exactly critical for Polish economy, but they are of limited economic importance. On the other hand, their growth is a best opportunity and at once the need to the future sustainable development.

Jan 1, 2011

By Peter A. Spencer

Much criticism has been levelled at bacterial oxidation over the quantities of air required for successful operation. Examination of the oxidation reactions and the assumptions concerning oxygen transfer made in the literature (1) indicate that the aeration requirements can be much less than those beirig suggested. Observations made on a large scale pilot test have confirmed reasonable aeration levels in extended site operation over a six month period. These aeration levels have implications for the engineering design and the power needed for aeration and agitation. Thus, these parameters effect both capital and operating costs as well as influencing the complexity of the design and normal operation. A number of companies have developed bacterial oxidation cultures intended for commercial ·expl oi tat.ion ( 2, 3, 4). Most of these cultures have been based on Thiobacillus and operate at temperatures between 30°c and 40°c. This temperature range limits their application in hotter regions unless means for both heating and cooling are provided in the design. Thiobacil!us cultures are also reported as not able to oxidize arsenic (III), which may limit the application of these cultures to successfully treat arsenopyritic ores and concentrates (5). BacTech (Australia) Pty Ltd has developed a culture which operates at temperatures above 4o0 c and which has been tested in a large site based continuous pilot plant at up to 55°c over a six month period. The culture showed resistance to high levels of soluble arsenic, allowing the arsenic to be retained in solution for control led precipitation and disposal. Data for. the arsenic precipitates indicated that these waste solids were relatively stable and, under the correct circumstances, were suitable for disposal into tailings dams without causing environmental problems.

Jan 1, 1990

By Manuel R. Lastra

Critical to successful dump and heap leaching for gold, silver, copper and uranium are factors such as permeability, solution delivery to the ore, and solution recovery. This paper deals with possible techniques for successful accomplishment of these three factors. New developments as well as older techniques are discussed, together with rationale for use of some techniques in reference to others. The authors hope to present a checklist so that the ideal application to individual mine situations can be achieved. This involves a discussion of the merits of each different method and the situations for most logical application. It is hoped that such discussion will broaden the geographic areas where dump and heap leaching can be applied to include greater winter cold and tropical regions of large amounts of rainfall.

Jan 1, 1984

By A Dennis, T Hunter, R Coleman

For metallurgical plant design, it is necessary to progress through successive phases of test work, piloting and process development before involving all the other engineering disciplines and “freezing” the process design criteria and flow sheet. This process usually relies upon the experience, skills and personal preferences of various technology providers, study and engineering entities, test work and metallurgical laboratories and, most importantly, the owner’s team and its operators. Current industry trends include lower grades, more complex orebodies, geometallurgy in defining orebody variation and design envelopes, more common “hybrid” plant processes and the market demands for more reliable, timely and predictable early plant performance.This paper will discuss interaction of these trends and provide guidelines for the level of detail and technical complexity required for a number of different “typical” examples. The paper will pay particular attention to the study definition level translated into the required detail and certainty needed by the overall process “owner” and original equipment manufacturer (OEM) equipment suppliers to ensure the best real plant performance. Some recent case studies will be discussed. In many projects, at a late stage of project definition, it has become common practice to undertake a “value engineering” phase. Although it could be argued that this should be undertaken earlier, it is largely driven by an overall need to reduce capex and “optimise” the perceived “fat” built into the project during the detailed design process. This value engineering can be very counterproductive to project timing and operational performance and warrants discussion.The paper is intended to promote discussion on a topic of wide interest. The authors’ diverse backgrounds and experiences are integral to the views in this paper.CITATION:Dennis, A, Coleman, R and Hunter, T, 2017. Critical process design considerations from test work to operations, in Proceedings MetPlant 2017, pp 12–30 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 11, 2017

By L. Tercero Espinoza, F. Marscheider-Weidemann, C. Gandenberger

"A reliable supply of non-energy raw materials is a precondition for the functioning of the European economy. In line with its importance, the issue of raw materials supply has become more prominent in the past years, especially owing to turbulent raw material markets. However, these turbulences are not due to depletion of the geological resources but to a missmatch of (expected) supply and (expected) demand, with several interacting factors influencing the markets both from the supply as well as from the demand side. A recent evaluation, published in June 2010 within the framework of the EU Raw Materials Initiative, sought to bring together these two sides of raw material markets and asked the question "which raw materials are critical for the EU?" Herein we present the methodology used by the Ad-hoc Working Group on Defining Critical Raw Materials and the results obtained, complemented by results from the study "Raw Materials for Emerging Technologies"."

Jan 1, 2011

By Reno H. Sales

The syngenetic, metamorphic water, and source bed concept theories of ore deposition proposed by Anton Gray, C, Lo Knight and others, to explain ores in sedimentary rocks, are challenged on the basis of a survey of the literature and personal observation, A hydrothermal origin for the Northern Rhodesian Copperbelt deposits is indicated by the presence of post-Roan age igneous rocks and post-gabbro mineralization, the wide distribution of ore in the various Lower Roan lithologic types, and the zoning of the copper-iron sulphlde minerals and minor elements The proposal by Gray and Knight that igneous rocks are not favorable as guides to nonferrous metal deposits, and Gray's hypothesis that the redistribution of connate waters and their dissolved metals by metamorphic processes was responsible for the emplacement of ores, are rejected as contrary to field evidence, The absence of exposed potential igneous source rocks is shown to be an invalid argument for the proponents of any syngenetic hypothesis, The common association of ore deposits with calc-alkaline intrusive rocks and their derivatives is, however, demonstrated to be convincing evidence that an exploration program based upon a magmatic theory of origin, would have found most of the important known non-ferrous metal deposits of the world, It is urged that prospecting be continued on the sound basis of accumulated knowledge of the lithologic and structural facts surrounding known ore deposits.

Jan 1, 1960

By M. K. Larson

Proper employment of numerical stress analysis design tools is based on the demonstrated ability of a model to capture key elements of the geologic site model and accurately simulate how these elements interact with a mine design. While these tools have progressed markedly, they are, at heart, a gross simplification of the abundant complexity of a natural setting and its response to mining. A generic deep longwall site model was developed that includes aspects of the geology of deep coal mines in the Wasatch Plateau and Book Cliffs coal fields of Utah. The site model contains a set of common features and observations of how these features typically respond to mining. This site model was the basis for evaluating use of empirical, boundary element and volume element stress analysis tools to analyze the distribution of stress around a deep longwall panel. More specifically, this evaluation examined shifting of stress to panel abutments and gob, distribution of stress in the abutment, and deformation and failure of bridging strata. Measurements of abutment stress changes at two sites in the Wasatch Plateau region were used to illustrate model calibration. Overall, these comparisons highlight the considerable differences between methods. Volume element tools can incorporate considerable detail and have fewer underlying assumptions, but this detail carries a considerable computational cost. Boundary element tools are much more efficient. But this efficiency also comes at a cost of added assumptions. These assumptions were challenged by the presence of a strong sandstone unit in the overburden, leading to boundary element results that depart significantly from volume element results. Empirical rules are the simplest, but are even more burdened by assumptions, many of which are implicit in underlying cases. Insight into the nature and impacts of underlying assumptions in each method is essential to proper use of results in mine design. Disclaimer: The findings and conclusions in this report are those of the authors and do not necessarily represent the views of the National Institute for Occupational Safety and Health

Jan 1, 2009

By R. J. Enright

Eight mines in canada and three in Australia were visited between September 1987 and Februacy 1988. All mines had encountered problems with sulphide dust explosions and had introduced defence mechanisms to prevent or limit the extent of these explosions. Techniques included dispersion of limestone by various methods, use of water foggers, placing of water and inert stenuning in blast holes, and removal of settled dust to prevent secondary explosions. The techniques were evaluated and it was concluded that certain practices should be modified or discontinued as they were of little value in preventing dust explosions.

May 11, 1988

By D L. Head

Critical risk management (CRM) has become one of the latest safety buzz terms in mining. Everyone seems to be doing it, everyone seems to know about it, yet we are still having fatalities in our industry from well understood hazards such as mobile equipment amongst others.

May 5, 2022

By C Young

In the vast expanse of Western Australia’s mining sector, a critical issue has come to light: many mining operations overlook the power of a Broad-Brush Risk Assessment (BBRA) to uncover their critical risks. This oversight has led to a cascade of challenges, where some mining endeavours find themselves grappling with: - Unidentified and unmanaged fatal risks, casting a shadow of uncertainty and heightened compliance risks. - A bewildering landscape where the concept of critical risks remains enigmatic, with some mistaking the risk register for the BBRA. - A fog of confusion surrounding the guardianship of these critical risks, leaving safety responsibilities blurred and undefined. Yet, the solution lies within our grasp. An effective BBRA empowers organisations to: - Pinpoint with unwavering certainty every ‘true’ critical risk. - Clarify ownership for each critical risk, ensuring accountability and swift action. - Create a prioritised roster of critical risks, illuminating the path to safer operations. - Lay the foundation for essential follow-up actions like bow-tie analysis, the identification of critical controls, and the fortification of the safety and health management system. Join us in this presentation, where we delve into the heart of an industry-leading BBRA process. Discover practical insights that will enable your organisation to craft and implement BBRA strategies, bridging the gaps in your journey toward preventing fatalities and fortifying safety protocols.

Apr 16, 2024

By Antoni Kidybinski

Coal mining both with longwall and room-and-pillar method often encounters severe operational difficulties due to had roof conditions. Rooffalls at entry cross-cuts or along the rib line in longwalls as welt as dynamic and excessive loads on supports due to overhanging of strong roof layers in a goab - are well known phenomena to the mine operators. Also, a number of practical examples may be quoted of dramatic improvement of working conditions after changing of coal winning technology or supports type. It is therefore a question to be answered how far we are able to recognize roof strata properties before mining starts and adjust both coal extraction technology and supports of entries to rock stability foreseen. Furthermore, engineering principles and criteria for decision making should be established. In recent years several in situ rock strength and discontinuities detection testing techniques have been developed both indirect (geophysical) and direct thus making possible closer roof-strata examination. In this paper critical roof span criterion is discussed as a basis for selection of proper mining system in terms of desirable stability of mine opening .

Jan 1, 1982

By J Rola

This paper outlines a laboratory-based design method, founded in critical state soil mechanics, for identification of an appropriate compaction specification to ensure dilative conditions prevail across the design TSF stress range. The method makes use of the critical state line (CSL) and consolidation tests prepared at varying compactive efforts. The CSL and consolidation curves are plotted together in e-log p’ space, with the compaction curves transformed from vertical effective stress to mean effective stress using the coefficient of earth pressure at rest (K0). Consideration is given to the sensitivity of K0 as it is generally not available during the design phase. An example of the design method is illustrated with laboratory data.

Jul 1, 2021

By Bruce Peberdy

Outline ?Building Systems ?Climatic Effects ?Thermal Effects ?Building Components ?Building Materials ?Structural Deterioration ?Maintenance Considerations

Nov 1, 2011

By M. Abouhamad

According to the Canadian Urban Transit Association (CUTA), 140 Billion CAD is required to maintain, rehabilitate, and replace subway infrastructure between 2010 and 2014. The current practice adopted by transit authorities for prioritizing subway stations for rehabilitation is based on the station structural needs. While this classification is reflective of station condition, other factors, such as station size, location and passenger capacity, play an important role. The criticality of a station is an index that represents the functional importance of a station depending upon a set of identified factors. The system criticality is based on several attributes, such as station location, size, and nature of use. This paper presents a novel method of clustering subway stations for rehabilitation priority based on their criticality level. The different stations in a subway network are rated according to their relative importance against predefined attributes. The weights and scores of the attributes are computed with the help of experts and current subway network data. The analysis is done using the Fuzzy Analytic Network Process (FANP) to accommodate the subjectivity of human judgment as being expressed in natural language which entails ?fuzziness? in real-life problems and account for the interdependency between the selected attributes. The output of the model is a criticality based clustering of subway stations. The proposed framework helps authorities prioritize stations for rehabilitation and highlight stations with more criticality for a more robust asset analysis.

Aug 1, 2013

By P. R. Ineson, D. W. James

For a criterion to be useful it must either demonstrate directly the role of exhalative processes in the formation of a deposit or describe a unique attribute of exhalative deposits. Few of those employed in previous investigations entirely satisfy either condition. The limitations of three of the most frequently employed criteria are illustrated by studies of the geology of the King Island Scheelite deposit in Tasmania.

Jan 12, 1993

By J. N. Van der Merwe, M. Mathey

"The South African squat coal pillar strength formula, developed by researchers from the Chamber of Mines Research Organization in the 1980s, predicts an exponential increase in coal pillar strength once a critical width-to-height ratio of 5 is exceeded. The arguments that have been proposed in favour of this formula are discussed critically in this paper.Field experience with squat pillars in the USA and evidence from published physical, analytical, and numerical model pillar studies corroborate the fact that a squat effect is unlikely to occur in coal pillars at width-to-height ratios less than 10. Furthermore, an exponential increase in peak strength of coal pillars does not exist. An alternative design criterion for squat pillars in South Africa is therefore suggested. IntroductionFive decades of coal pillar research in South Africa have produced a wealth of information on the mechanisms contributing to the strength and failure of in-situ coal pillars and accompanying phenomena. The relevant knowledge was sourced from, and for, a South African coal mining environment that remained largely unchanged in the second half of the 20th century. The depth of mining seldom exceeded 250 m, with mined seam thicknesses averaging 3 m and typical pillar width-to-height ratios (w/h) of 3–4.It is therefore not surprising that comparatively little research has been directed at the prediction of coal pillar performance in deeper deposits, where squat pillars of larger width-to-height ratios will be required to support the overlying strata. However, a thorough understanding of squat pillar performance will be necessary should the remaining deep coal deposits of the country be extracted in future, for instance in the Waterberg or Ermelo coalfields.A squat coal pillar strength formula has already been proposed in South Africa. The origin of this formula will be discussed in some detail in the following sections and its appropriateness will be critically reviewed against a great amount of evidence from relevant squat coal pillar research conducted internationally."

Jan 1, 2016

By W. E. Heinrichs, R. W. Davis

Introduction Cross borehole seismic tomography (CBST) is a geophysical technique that allows definition of the distribution of some physical rock property between two boreholes. The method is similar to the computer-assisted tomography (CAT) scans used by the medical industry. This paper describes the method, its applications and the developing trends in its use that interest the mining industry. The idea of using tomography in connection with geophysical methods for measuring rock properties between boreholes has been around for three or four decades. Until the advent of high-speed, large-capacity computers, the necessary calculations were too formidable for production use. Another factor in the development of the technique has been the refinement of a mathematical base to meet the needs of the medical industry. The geophysical applications have benefited from this refinement. An extensive discussion of the basic theory is given in Kak and Slaney (1988). CBST, although widely researched and written about, is still not extensively put to use in mining and engineering projects. Most real world examples in the literature have come from research carried out by government laboratories or by large companies. An exception is the regular use by Prospection Geophysique Francaise (Cottin et al., 1986) in damsite investigations. The Japanese appear to be doing extensive research and testing of CBST's uses in civil engineering projects (Saito et al., 1988). Canada is researching the use of the method in connection with nuclear waste site investigations (Wong et al., 1987). Finland has tested the method in connection with a foundation investigation for a nuclear power plant (Cosma et al., 1984). In the US, the US Bureau of Mines has taken an interest in using CBST as a means to enhance in situ mining operations (Tweeton, 1988). Major oil companies are examining the method as a tool in oil field development (Justice et al., 1989). Description of the method CBST involves placing a series of receivers down one borehole and recording transmissions from an energy source placed successively at a series of positions in another hole. The objective is to generate a dense network of seismic raypaths between the holes. The denser the network of raypaths, the better the features between the boreholes are resolved. Either seismic travel times or sine wave amplitudes are measured by the receivers. Analysis of travel times between boreholes develops a picture of rock velocities between the holes. Analysis of seismic wave amplitudes develops a picture of the distribution of energy transmission characteristics between the holes. These seismic properties can be used to define occurrences of fracture zones, lenticular sequences or other important geologic data not apparent from examination of the borehole logs. When longitudinal (compressional) and transverse (shear) waves are analyzed, the physical properties, such as elastic moduli, can also be mapped. When wave amplitudes are measured, rather extensive corrections to the data are necessary. There is some disagreement among researchers as to the feasibility of making some of the corrections. For this reason, this paper will concentrate primarily on travel time analysis. Wave amplitude analysis will be mentioned occasionally only in passing. This does not mean that amplitude analysis does not provide important data on rock parameters, only that for the present there are limitations on its uses. Vertical seismic profiling (VSP), extensively used in recent years in oil exploration, is similar to CBST. Instead of using two boreholes, however, the VSP method uses an array of seismic sources or detectors down one hole and an array of detectors or sources along the surface radiating outward from the hole. While adequate for determining vertical velocity distributions, the VSP method is not, by itself, suitable for most engineering or mining projects. Computer programs used to analyze the field data make use of the fact that the total travel time or change in signal amplitude between boreholes is described by Dines and Lytle (1979) as: [9k = f Rk f( x,Y) ds (1)] where gk = the total time or attenuation along the kth ray path,

Jan 1, 1992

AT a luncheon attended by engineering leaders representing every section of the country, Col. Arthur S. Dwight, president of the American Institute of Mining and Metallurgical Engineers, and Charles F. Rand, chairman of the Engineering Foundation, past president of the Insti-tute and its present treasurer, on Thursday, July 20, were decorated with the Croix de Chevalier de la Legion d'Honneur by the French Government for distinguished service in engineering tending to closer and more felici-tous relations between the two countries. The decorations were conferred by Consul General Gaston Liebert. In a speech extolling the war work of the American engineer, M. Liebert declared that Germany had been definitely foiled in her attempt to cripple France industrially for a generation by wrecking the coal mines of northern France. Three-fourths of these mines, M. Liebert said, were in full working order and the remainder will be in complete operation within two years. The Germans thought that it would take from 15 to 20 years to accomplish this. M. Liebert said that reconstruction is going on rapidly in northern France, two-thirds of whose indus-tries are now working. The French Government, he said, is planning water-power improvement on a vast scale, which will soon make unnecessary for France to import a single ton of coal. He urged that French students be sent to America to study engineering. In presenting the decorations, Consul General Liebert eulogized Colonel Dwight and Mr. Rand as personify-ing the spirit and service of the American engineer, which, he said, was a powerful factor in the victory over Germany. He spoke of the growing friendliness between the United States and France and described this ceremony as an epoch in international relations. Calvin W. Rice, secretary of the American Society of Mechanical Engineers, who presided, repeated that international unity among engineers was the dream of Andrew Carnegie, who saw in the efforts of the engineer and the scientist the hope of civilization. Mr. Rice said in part: In the Declaration of Independence occurs the statement that all men are created free and equal. Jefferson was familiar with the writings of Rousseau. In fact, he was a remarkable linguist notwithstanding that he wrote the Declaration of Independence when only 32 years of age. He was one of the very few ambassa-dors in the history of the United States who could speak the language of the country to which they were sent. The interpretation of the passage in the Declaration of Independence is that all men have equal opportunity, not that they are born with equal ability.

Jan 8, 1922

By Brenton Cook, Nate Long, Larry Applegate, Aaron K. McCain

"The Northgate Link Extension project is the third phase of the Sound Transit master plan to extend light rail throughout the greater Seattle metropolitan area. When completed, the Northgate Link Extension will extend the existing light rail system north by about 7 km (4.3 miles) from the University of Washington to the Northgate neighborhood. A general overview of the project alignment is provided as Fig. 1. The project was funded by a combination of federal grants and allocations from local taxes. The general contractor on the project was JCM Northlink LLC (JCM), a joint venture between Jay Dee Contractors, Frank Coluccio Construction Company and Michels Corp. SoilFreeze, Inc. was retained as a subcontractor to provide ground freezing design and construction services.The project involved the construction of two parallel 5.5-m, 25-cm (18-ft, 10-in.) (inside) diameter tunnels using earth pressure balance (EPB) tunnel boring machines (TBM) and precast segmental concrete tunnel liners. The two tunnels maintained roughly the same elevation along the alignment and were spaced roughly 12 m (40 ft) apart (centerline to centerline). A total of 23 cross-passages connecting the two tunnels were included at approximate 244-m (800-ft) intervals. Cross passage excavations were elliptical in shape with dimensions of approximately 5.6 m (18.5 ft) in height and 5.3 m (17 ft) in width. The cross-passages were 5.8 to 6.1 m (19 to 20 ft) long as measured between the exterior of the tunnels at springline elevation. Cross passages were intentionally located directly beneath public right-of-ways thus avoiding buildings. Many of the cross passages were located beneath narrow roads in residential neighborhoods with mature vegetation, existing utility structures and piping and limited parking areas. Excavation and support for each cross passage was completed using the sequential excavation method (SEM).The subsurface soil and ground water conditions at the cross-passage locations were described in the Northgate Link Geotechnical Baseline Report (GBR) prepared by Jacobs Associates and the Northgate Link Geotechnical Data Report (GDR) prepared by Shannon and Wilson, Inc. Soils along the project alignment were glacially overridden and characterized as very dense or hard. Subsurface soils consisted of cohesionless sand and gravel (CSG), cohesionless silt and fine sand (CSF), cohesive clay and silt (CCS) and till and till-like deposits (TLD)."

Dec 1, 2018