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By R. W. Smith, A. M. Raichur, M. Misra

Mycobacterium phlei has very good potential as a hematite flotation collector. The flotation recovery of hematite is dependent upon the solution pH and concentration of the microorganism. The critical pH for maximum recovery of hematite is around three, which corresponds to the point of zero charge of the microorganism. An excellent correlation between the flotation recovery and bacterial adhesion on hematite is observed. The adhesion of Mycobacterium phlei on hematite can be described by the potential energy of interaction calculations using an extended DLVO theory.

Jan 1, 1994

By D. Washington

The US economy and the demand for nonfuel minerals grew at lower rates in 1995 than in 1994. Demand for major metals, such as aluminum, copper and steel, was mixed but relatively stable. The building industry, including highway construction, helped to support modest overall growth in demand for industrial minerals. The value of processed materials of nonfuel mineral origin produced in the United States during 1995 was estimated to be $395 billion, an increase of almost 10%compared with 1994 (Fig. 1). The estimated value of US raw nonfuel minerals production during 1995 was $38billion, about 7% more than in 1994. The value of US minerals production has increased in 30 of the last 35years.

Jan 1, 1996

By M. E. Ryan, C. L. Hoebbel, E. J. Haas

DISCLAIMER The findings and conclusions in this paper are those of the authors and do not necessarily represent the official position of the National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention. Mention of any company or product does not imply endorsement does not constitute endorsement by NIOSH. ABSTRACT It has been suggested that effective disaster prevention and response in mining requires that elements of emergency management be incorporated into everyday operations, planning, and decision-making, much in the same way that the industry approaches routine risk management. Since Congress passed the MINER Act in 2006, the newly mandated structural and technological advancements in mine emergency response preparation have been made and are apparent, but measureable improvement in mineworker emergency preparedness is difficult to ascertain. To begin exploring whether measurable indicators of mine workforce preparedness can or should be addressed within a risk management framework, NIOSH researchers examined the datasets from two separate research efforts—one which measured the organizational safety climate and self-reported safety performance, and the other which measured individuals’ perceptions of their own self-escape competency. INTRODUCTION In response to the mine disasters in 2006, the United States Congress passed the Mine Improvement and New Emergency Response Act (MINER Act), which strengthened existing regulations [30 CFR, Part 48] and introduced new provisions to improve mine emergency response. Since that time, new technological and structural features, such as mandated redundant communication systems, personnel tracking systems, and lifelines in primary and secondary escapeways, have been installed in underground coal mines across the country. Additionally, mine operators are required to develop emergency response plans, provide adequate supplies of breathable air throughout the mine, provide more frequent and realistic expectations training, and are required to immediately notify the Mine Safety and Health Administration (MSHA) in the event of an accident. While the structural and technological advancements in emergency preparedness are readily observable and easily measured, levels of individual mineworker preparedness remain difficult to assess. There is a general consensus that deficiencies in competence in the non-routine tasks required for individual miners to effectively respond to a mine emergency likely remain (e.g., National Research Council [NRC], 2013), and NIOSH research continues address this concern (Haas, et al., 2015; Hoebbel et al., 2018). To maximize an operation’s capacity to effectively prevent disasters and/or respond to emergency events, it has been suggested that individual and emergency management efforts be incorporated into everyday operations, planning, and decision-making in much the same way organizations manage routine risks to health and safety (Haddow et al., 2017). To the authors’ knowledge, the mindful intersection of routine risk management policies and practices and emergency prevention and response readiness have yet to be empirically studied within the mining industry.

Jan 1, 2019

By E. D. Attanasi

Geologic resource assessments describe the location, general characteristics, and estimated volumes of resources, whether in-situ or technically recoverable. Such compilations are only an initial step in economic resource evaluation. Forecasts that assume that resources that exist in nature can be commercially produced as needed ignore economic constraints. This paper identifies, by example, the salient features of a geologic assessment that will assure its usefulness for economic analysis. These features are demonstrated with examples of coal resource assessments and coal bed gas assessments.

Jan 1, 2001

By Laszlo Toth

A feeder is used to control the gravity flow of bulk solids from storage areas, like a bin or a stockpile. For this type of application, it is important to select a proper drive that can fulfill all of the demands put on it. High starting torque capacity, variable speed and the ability to handle frequent starts and stops are some of the demands that the drive must be able to meet. The following is a comparison of the most common type of drives used today for feeder applications. When a feeder is started, the breakaway torque may reach as high as200% of the running torque. The accelerating torque usually is set to protect the carrying element of the feeder, like the belt for the belt feeder and the carrying chain of the apron feeder (Fig. 1).

Jan 1, 2003

Traditional fine grinding mills in mineral processing relied on the use of steel medium for particle size reduction. The successful development of the Isa Mill(a horizontal stirred mill with 3000 litres of net chamber volume and 1120 kW rated motor power)adopted a novel product separator design that has led to a major revision of medium use in fine grinding. The Isa Mill separator has also successfully operated with a wide variety of medium types such as silica sands, river gravel, smelter slag, run-of-mine ore fractions and steel shots, with size ranges from 0.5 to 10 mm. A great flexibility of the Isa Mill operations has been achieved for processing a feed as coarse as 120 um to a product as fine as 5 µm. This paper discusses the performance of two inert grinding media used in the Isa Mills in Mount Isa Mines of Australia for processing galena and sphalerite bearing ores to below 10 microns. They are the copper reverberatory furnace slag (CRFS)and the heavy medium plant rejects (HMPR). A methodology was also demonstrated for comparing the medium performance and for scaling up the Isa Mills from a 1.5-litre laboratory batch mill to a full scale 3000-litre mill.

Jan 1, 2000

By Steve Kral

The mining industry in northern Ontario is known mostly for its huge nickel deposits. Inco’s and Falconbridge’s nickel mines in the Sudbury Basin are the best known. And with nickel prices being what they are, interest in the region continues. And how. Inco and Falconbridge want to merge. Teck Cominco wants Inco, but without Falconbridge. Xstrata made a hostile bid for Falconbridge, which Falconbridge rejected. And, in June, Phelps Dodge trumped them all when it made an approximately US$40-billion friendly offer for Inco and Falconbridge in a two-part deal.

Jan 1, 2006

By William D. Leech

Lebanon used a TBM for the firsttime to excavate a tunnel in the country. A main beam TBM, built in 1979, bored the 3.8 m (12.5-ft) diameter by 4,020 m (2.5-miles) Madiq Tunnel. The TBM bored through karstic terrain of dolomitic limestone, limestone and marly-limestone rock having near horizontal beds with more than twelve faults crossing the axis of the tunnel. The TBM also encountered more than six major karst features, filled with various combinations of boulders, clay, void space and water. The excavation through these collapsed-breccia zones drastically slowed the TBM?s progress. When complete, which the Madiq Tunnel is a part, the Kesrouane Water Project along the coast will bring fresh and irrigation waters to the parched and heavily populated region north of Beirut. The paper will describe the tunnel geologic features, karst genius, TBM upgrades and performance, and TBM/karst difficult situations

By R. L. Zick, D. C. Finn

Introduction The high-density sludge process was originally developed by Bethlehem Steel Corp. for use on acid mine drainage (AMD) and diluted waste pickle liquor discharges requiring continuous chemical-treatment. This work began in the early 1970s and was first put into practical use around 1973. To date, there are approximately 15 operating systems that have been installed to treat mine drainage in the United States. In addition, there are another 10 systems installed outside of the United States. The dense-sludge process is an innovative and improved method for treating acidic metal-bearing streams in a manner that minimizes the volumetric generation of sludge for disposal. The technology utilizes a sludge-recycle process that forms particles with a low affinity for water. These particles are unlike conventional metal hydroxide solids that contain tightly bound interstitial waters. Typical acid mine drainage streams contain high sulfate concentrations that combine with calcium ions in lime-based treatment systems to form gypsum crystals. Compared to the form generated in conventional lime treatment systems, the physical form of the gypsum is radically altered when the dense-sludge process is utilized. The characteristics of the metals particles are also changed in this process, as the metal hydroxides are converted to metal oxides. The dense-sludge particles settle faster, dewater more readily, are more easily pumped and hold much less water than conventional precipitates. In some cases, because the metal content of the sludge is more concentrated, it can be economically recovered. In general, the conventional and dense-sludge treatment processes are very similar. The changes required to implement the dense-sludge process are minor, and, typically, much of the existing equipment can be utilized. The net results of the process are: reduced operational costs associated with sludge generation, improved process control (particularly pH control), reduced gypsum deposition (i.e., less scaling) on system components and reduced sludge generation resulting in less return water for treatment. Despite the relative simplicity of the process, the application of the technology requires careful discrimination, and the "experience factor" for implementation is an important consideration that should not be over looked.

Jan 1, 2000

By F. N. Kissell, C. D. Litton

This study predicts the level of smoke that miners might meet while trying to escape a coal mine fire and describes how smoke would impede their safe escape. For this study, the authors assumed that miners exit through an escapeway adjacent to the burning entry, that some air would leak from the burning entry to the escapeway. The following conclusions were made: • A very low amount of air leakage to the escapeway can produce a critical level of visual obscurity from smoke. This shows that intake airways may be as susceptible to smoke visibility problems as return airways. • This critical level of smoke obscurity is reached much before a critical level of carbon monoxide is reached. • Small fires can cause a severe sensory irritation that further limits vision. Thus, reliable eye protection is very important. These results show that methods to guide miners through dense smoke will contribute greatly to saving lives during mine fires.

Jan 1, 1993

By James L. Poole

The gold and silver markets from the late 1960's to the present are reviewed and the outlook for these metals in the 1980's is presented. Included in this discussion is a summary of the basic supply and demand balance for gold and silver since the mid-1960's. an explanation of the price formation for the metals, some of the relationships between the prices of these metals and selected economic parameters, and how these factors affect the outlook.

Jan 1, 1981

By Michael Karmis

The International Conference on Sustainable Development Indicators in the Mineral Industries(SDIMI 2003) was held May 21-23, 2003 on the island of Milos, Greece. The objective of this international conference was to assist the mining and minerals industries in their global transition to sustainable development. The main theme of the conference was the development, monitoring and assessment of sustainable development criteria for mineral operations. Emerging technologies were also presented that can assist in the development of criteria and performance indicators.

Jan 1, 2003

By S. Hardcastle

Tele-remote operation of production equipment from surface will change the design criteria for underground mines. And for ventilation, with machine operators on surface, conventional planning to dilute and remove pollutants can become redundant. Natural Resources Canada with industrial partners are investigating what will be the new environmental design criteria. Additional complications include new mining equipment being designed without standard services and mines’ desire to eliminate conventional auxiliary ventilation. Findings to date show the cooling of equipment’s hydraulic systems to be the most demanding element, especially in dead-ends and when stationary. Consequently, revised ventilation based heat control strategies for equipment are being developed for the automated mine of the future.

Jan 1, 2001

By R. A. Hodge

Over the past decade, there has been a significant increase in effort put to tracking progress toward sustainability. Many aspects of society are participating in this “movement” including mining. The drivers are diverse and include evolving ideas in business and public administration as well as concerns for human well-being, community robustness, environmental integrity, and overall social and ethical responsibility. The scale in question varies greatly from local to global. For the most part, there has been a pre-occupation with developing discrete measurable signals. This paper argues that the overwhelming focus on the quantitative is ill-advised and that a more effective approach is to bring together the best of both quantitative and qualitative. The mining industry in particular is well-placed to affect this shift and reap the associated benefits.

Jan 1, 2004

By Kent von Maubeuge, Charles R. Landis

The global bentonite industry is a dynamic market balancing a range of end uses with an ever growing number of bentonite producers. In addition, markets in developed countries are elevating the level of detail and transparency for materials reporting in programs, such as the Registration, Evaluation, Authorization and restrictions of Chemicals (REACH) program in the European Union. Bentonite is impacted by programs of this nature. The majority of the bentonite products sold around the world are sodium bentonites. These sodium bentonites consist either of natural sodium bentonites, or naturally occurring bentonite dominated by divalent interlayer cations (Ca+2 andMg+2) subsequently exchanged with sodium cation. The latter variety is often called “sodium-activated“, or “soda-ash treated” bentonite. Once exchanged with sodium, these bentonites are often difficult to distinguish from natural sodium bentonites using common commercial testing protocols. Due to their similar colloidal and bulk chemical properties; the lack of test procedures designed specifically to identify this product feature; and the failure to completely or effectively explain their differences, sodium-activated bentonite is often considered to be identical to natural sodium bentonite in the industry. This article defines both general types of sodium bentonite and presents a technique that could serve the industry as a tool to confirm the variety of sodium bentonite in question. Specifically, geochemical properties such as carbon (C13/C12) and oxygen (O18/O16) isotopic ratios can distinguish activated, even slightly activated bentonites, from bentonites not introduced to additional sodium during manufacture.

Jan 1, 2004

By Glen Frank, David R. Chapman

Determining the number of boulders and cobbles that will be encountered in the tunnel envelope is one of the most difficult problems confronting the geotechnical engineer in the design of tunnels in glacial terrain. This issue is very important to the contractor, both in determining what methods will be used to construct the facilities and the advance rate that can be achieved for the chosen construction methods. The cost of constructing tunnels by pressurized face tunneling techniques is very sensitive to accurate characterization of the very coarse fraction (large cobble and boulder sized clasts), and no standard method is current available for characterizing boulders and cobbles. Careful use of large diameter borings and the sampling and analytical techniques outlined in this paper can provide a means to answer this difficult question. By performing large diameter borings and carefully recording and sampling the cobbles and boulders encountered, an estimate for the amount of these materials present in the formations sampled can be provided. Using this method allows the designer to communicate the expected geologic conditions to the prospective bidders in a manner that is both definitive and defensible. This paper describes the method as it was used in conjunction with the design of a large diameter sewer tunnel in the Columbus, Ohio area.

Jan 1, 2005

By Albert Musschoot

The expanding applications of vibrating feeders for controlling the flow of bulk materials, and their adaptation for processing requirements, have developed considerable interest in stockpiling and reclaim systems. The general design of these units consists of a material transporting trough, or platform, driven by a vibratory force system. Design flexibility and variety is limited only by engineering ingenuity. The basic motion of the vibratory trough, or work member, is a controlled directional linear vibration that produces a material tossing or hopping action. Material travel speeds vary from 0 to about 30 m/min, depending on the combination of frequency, amplitude, and slope vibration angle.

Jan 6, 1981

The United States continued to depend on imported bauxite during 1995. Domestic bauxite mine production remained at about the same level as in 1994. It amounted to less than 1% of total world production. All of it was used for nonmetallurgical products, such as abrasives, chemicals, proppants and refractories. Metallurgical grade bauxite was imported from 12 countries. Principal suppliers for this 10 Mt (11.1 million st) of ore were Guinea (39%), Jamaica (35%), Brazil (17%) and Guyana (8%). The average value of imports, c.i.f. US ports, was $31/t ($28/st). Calcined refractory-grade bauxite imports totaled235 kt (259,000 st). It had an average value of $112/t($102/st) c.i.f. US ports. China supplied 61%, Guyana30%, Hong Kong 4% and France 3%. Imports of other grades of calcined bauxite, primarily for the abrasives market, totaled 259 kt (286,000 st).They were supplied by China (59%), Greece (20%), Brazil (14%) and Australia (6%). The average value was$74/t ($67/st) c.i.f. US ports.

Jan 1, 1996

By John Reilly

The author?s paper at RETC 2007, ?Alternative Contracting Methods? addressed strengths and weaknesses of DBB+DB and introduced Construction Manager/General Contractor (Portland model) and Alliancing (Australian model). Considerable interest in these was expressed by several public agencies at that Conference and at the presentation. The author is assisting the Washington State Department of Transportation (WSDOT) and the Toronto Waterfront Revitalization Corporation (TWRC) with possible implementation of Alliancing. WSDOT is evaluating ways to do this and is considering a delivery methodology, under existing Legislation, based on the CMGC Portland model with incentives and disincentives, moving towards Alliancing. This paper will build on the 2007 paper and update implementation considerations.

Jan 1, 2008

By Michael L. Ogilvie

The proportion of underground coal production as a percentage of overall Australian production has fallen in the last 10 years, with underground production remaining more or less static at about 53 Mt (58 million st). However, underground coal mining remains a viable industry in Australia, due to use of modern longwall mining systems. In 1993-1994, 26 longwalls were in operation, with total production exceeding 39 Mt/a (43 million stpy). Some of these longwalls achieve productivity levels approaching efficient opencut operations, and in some cases, they exceed them. These high-production longwall mines are not without problems when depth and distances from outcrop increase and the gas content of the seams approaches or exceeds critical limits. When gas content of a coal seam exceeds 6 m3/t (233 cu ft/st), gas flows into the mine may be sufficient to interrupt production from time to time.

Jan 1, 1995