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By M. R. Peterson, C. R. Ferguson, T. H. Jeffers

The ability of microorganisms such as yeast, bacteria, and various aquatic flora to sorb metals from dilute aqueous solutions is well documented. Although microorganisms have significant potential in decontaminating waste waters, techniques and equipment suitable for bioassisted decontamination are limited. The Bureau of Mines has investigated the use of microorganisms immobilized in porous polysulfone beads for extracting toxic and heavy metals from dilute waste streams. The minus 8- plus 12-mesh beads were fabricated from high-density poly- sulfone dissolved in dimethylformamide (DMF). Dried, thermally killed yeast, algae, duckweed, xanthan gum, and alginates were blended into the polysulfone-DMF, and spherical beads were formed by injecting the mixture into water. Microscopic analysis revealed microorganisms immobilized within the bead pores. The beads had excellent handling characteristics and were tested in stirred reactors, fixed bed columns, and fluidized bed columns for their ability to remove metal contaminants from several waste waters. The effluents resulting from these waste waters met or exceeded the National Drinking Water Standards for cadmium, copper, manganese, and zinc. Other heavy metal contaminants readily sorbed by the beads included arsenic and mercury. Elution of metal values from the beads was accomplished using dilute nitric acid or sodium carbonate.

Jan 1, 1989

By William S. Brack

The mining industry is very capital intensive. Competition for shareholder investment has never been greater. Among our challenges is the need to meet shareholder expectations (return on investment), and one area of focus lies in our ability to deliver value on our capital investments. Our ability to meet project expectations affects not only the economics associated with the immediate project but also directly influences our ability to finance future projects. Moreover, our ability as individual companies to attract investor capital is influenced by how we have done overall as an industry, and our industry track record has not been that stellar. With safety, scope, cost, schedule, and quality as guiding principles, our project managers today must address high expectations on every project. This paper examines some items that should be on today's project management checklist. PROJECT ENGINEERING Herbert Hoover, himself a mining engineer, said Engineering is a great profession. There is the fascination of watching a figment of the imagination emerge through the aid of science to a plan on paper. Then it moves to realization in stone or metal or energy. Then it brings jobs and homes to men. Then it elevates the standards of living and adds to the comforts of life. That is the engineer's high privilege.

Jan 1, 2004

Early experiences suggested autogenous mills were difficult to operate and consumed substantially more energy than conventional rod/ball mill circuits. As our understanding has increased and the technology has matured this perception has changed to the point where most new comminution circuits are ag/sag based. In addition many operators have replaced existing conventional circuits with this technology. The JKMRC has been studying ag/sag mills for over 20 years. During this time it has amassed what is probably the single largest and most detailed data base of pilot and full scale mill operations in the world. This has been used to help develop and refine its cur- rent commercially available mathematical model of ag/sag mills. A decade of its application has greatly helped simplify both design and operation of ag/sag milling circuits as well as helping to promote the effective use of recycle crushing, secondary crushing and closed-circuit operation. This paper describes the development of ag and sag milling in terms of our understanding and the evolution of the technology. In addition the application of mathematical modelling and simulation in designing and operating efficient circuits is described with the aid of practical examples.

Jan 1, 1998

By R. Worrall

The global mining industry has been proactive over the last decade in finding ways to embrace the concept of sustainability. However, legacy mine sites (which include abandoned derelict and orphan mine sites) across the world continue to present issues for the global mining community, governments, local communities and NGOs. Unfortunately there has been much less academic focus on this area of mining and sustainability. This paper seeks to address how principles of sustainable development can be used to guide the development of processes for addressing post mining landuse issues for legacy mining areas. This is being done using a case study area located near Ipswich, in southeast Queensland, Australia. This area has a 160 year history of coal mining, and was one of Queensland?s crucial early industries. Mining in the area ceased in 2003 leaving a degraded landscape covering an area in excess of two thousand hectares adjacent to one of the fastest growing urban areas in Australia. A sustainability criteria and indicators framework for post-mining landuse on legacy mined land, developed from current best practice used for measuring sustainability across a range of industries is being developed. A review of current best practice suggests the framework should: (1) consider in equal measure environmental, social and economic factors; (2) have a minimum number of indicators which should be easy to identify and measure; (3) must have indicators with a meaningful output; and overall, the framework must consider particular requirements of the site being investigated. Application of the framework to the case study area is an ongoing aspect of this research, and the results will be evaluated through the use of expert stakeholders.

Jan 1, 2007

By Angelus S. C. Owili-Eger

The past decade has witnessed an unprecendented proliferation of groundwater computer models. Some of these numerical models were developed for the purpose of simulating groundwater movement in mining environments and predicting inflow rates into active mines. However, a general acceptance of these models as routine planning tools by the mining industry has been slow. Until recently, the major use of these models in the industry is by consultants. There are several reasons that have contributed to this situation. Some of these factors - include scarcity or non-existence of an appropriate data base information required for executing these models, the difficulty and costs involved in acquiring data, and the fact that the instructions for using these models are often too involved and time consuming. Today, however, the state-of-the-art technology has been advanced to a level where numerical models can be routinely used to simulate and predict inflow rates into active mining environments. Such environments include highly fractured (longwall) and deforming flow media. Features integrated into these comprehensive and yet easy to use models are double-porosity-pressure, multiphase, and non-darcian flow conditions. This paper reviews the role that computer modeling has played in mining-related operations by presenting several case studies and the state-of-the-art tools currently in use. Included will be some of the practical field applications that have been compiled during the past decade.

Jan 1, 1986

By J. D. Pitts

Long distance slurry pipeline systems for steam coal, iron concentrates, copper concentrates, and limestone, first used nearly 60 years ago, are now transporting nearly three billion ton-miles annually. At this time a phosphate concentrate pipeline is nearing start-up and systems for transporting coking coal, lead/zinc concentrates, and fly ash are planned. The solids pipeline concept was first patented in the early 1900's and put into practice in the 1950's. Table 1 summarizes the major elements of several presently operating commercial systems. Increased control system sophistication has been accompanied by significant drops in control equipment size and cost, as illustrated by recent cases of pipeline operation with progressively more advanced level of control: 1) The Consolidation Coal (Ohio) and Savage River (Tasmania) iron concentrate pipelines started in 1957 and 1967, respectively, used simple hard-wired control logic. 2) The Black Mesa (Arizona) coal slurry pipeline commissioned in 1971 added a hard- wired programmable logic controller for some of the start-up and shutdown routines. 3) Two years after its start-up in 1974 the Pinto Valley (Arizona) copper concentrate pipeline was tied into the concentrator digital computer system for data logging. 4) The Samarco (Minas Gerais, Brazil) iron concentrate pipeline which came on-line in mid-1977 was the first slurry system to use a dedicated supervisory computer for its control. Communication to remote areas was via micro- wave and buried cable.

Jan 1, 1979

By Robert A. Haney, Scott G. Vail, Kenneth G. Fields

The Mine Safety and Health Administration, in cooperation with IMC Global Operations, Inc., conducted a joint study to determine the effectiveness of the technology currently in use at the mine to control diesel particulate exposures. IMC Global operates an underground potash mine using diesel-powered equipment to extract minerals. IMC uses a variety of technologies to control worker exposures to diesel particulate. These technologies include: ventilation, low sulfur fuel, oxidation catalytic converters (OCC), maintenance and work practices. The study was conducted over a two-week period, two shifts per day. During the first week (six shifts), baseline data on exposures and diesel particulate emissions were obtained. New OCC's were installed over the weekend on all equipment on the test section. During the second week (six shifts), data were collected to assess the effectiveness of the new OCC devices. In addition to exposure and diesel particulate emissions data, mine ventilation, engine exhaust temperatures and mine operational data were obtained. The primary means of determining diesel particulate concentrations was the respirable combustible dust (RCD) method. Gas concentrations carbon monoxide (CO), carbon dioxide (CO,), and nitrogen dioxide (NO,) were measured using passive dosimeter badges and gas bottles. Results of measurements of diesel particulate, gases, and air- flows were analyzed to determine the effectiveness of airflow and oxidation catalytic converters for controlling diesel particulate exposures. The use of oxidation catalytic converters resulted in reductions of both workers' exposures and diesel emissions.

Jan 1, 1997

By Robert F. Randolph

New technologies confront mining organizations with unprecedented human factors challenges. Likely problem areas range from the design of the human- machine interface to the design of work groups and mine organizational structures. However, these human design considerations are commonly ignored in most industries, resulting in a failure rate of 75% for advanced technology programs. The U.S. Bureau of Mines is addressing these concerns through a program of research on the human side of high technology mining systems. Interviews with mining industry participants and researchers have identified concern in several areas, including training and equipment design. Although new mining technologies promise to improve overall safety by relocating miners away from hazardous areas, data from MHSA accident reports and other sources suggest that certain types of new hazards may be created. Many of these new hazards can be reduced though a systems approach to ergonomic design of equipment, tasks, and work processes. This evidence, combined with reviews of high technology human-machine systems in other industries. can help in the design of safe and efficient future mining technologies.

Jan 1, 1992

By Gerald G. Griswold, James O. Greenslade, Cherie Tilley, Richard Reseigh

INTRODUCTION The Harrison Western Corporation, a leading Denver based mine contracting and engineering concern, is presently engaged in sinking two 1,006 m (3,300 ft) shafts for the Phillips Uranium Corporation at their Nose Rock Project, approximately 13 miles northeast of the small community of Crownpoint in McKinley County, New Mexico. The Nose Rock Project is the first attempt by the Phillips Uranium Corporation to tap the deep uranium reserves in what has become known as the Grants Mineral Belt. (See Figure 1) Project Description Phillips Uranium Corporation's plan for the large 2700 metric ton per day (2950 tons/day) mining facility calls for a series of deep access and ventilation shafts ranging from 4.27 m (14 ft) to 5.49 m (18 ft) in diameter to approximate depths of 1,006 m (3,300 ft). The initial pair of shafts consists of one production shaft and one ventilation shaft separated by a distance of 91 m (300 ft). The interbedded layers of sedimentary sandstones and shales to be penetrated by the shafts contain several major water producing aquifers, the deepest being the mineralized zone called the Westwater Canyon Member of the Morrison Formation.

Jan 1, 1981

By S. Mathur

Oxide particles are commonly used as fillers in plastics, paper, rubber, etc. (particulate composites). The successful fabrication of such composites is dependent upon the adhesive strength of the filler particles to the matrix. The compatibility of the matrix and the filler particles is generally enhanced by the adsorption of surface modifiers such as surfactants and polymers at the particle-matrix interface. To develop a scientific basis for the selection of the appropriate modifiers it is necessary to understand their adsorption mechanisms. specifically, the adsorption of polymeric additives is attributed to a combination of chemical and electrostatic interactions, hydrogen bonding and van der Waals forces. Hydrogen bonding has been suggested to be the primary adsorption mechanism for nonionic polymers. However, a literature survey of the Poly(ethylene oxide) (PEO)-oxide system suggested that PEO, a nonionic polymer, was substrate specific. A systematic study was undertaken to investigate the adsorption mechanisms of PEO on oxide particles. It was determined that strong Bronsted acid sites on the surface interact with the ether oxygen, a Lewis base, of PEO to induce adsorption. In this work, characterization of PEO binding sites on oxides is reported and the mechanisms of PEO adsorption are discussed.

Jan 1, 1999

By Matthew E. Eisenmann, Gerald H. Luttrell

Performance data from phosphate plants are often untrustworthy because of difficulties associated with highly variable feeds and unstable equipment operation. In some cases, this problem is further compounded by improper sampling procedures and unreliable laboratory analyses. Questionable data often lead to misleading conclusions that result in lost productivity and profits. Data reliability may be checked using mass balances, but the mathematics associated with this procedure can be overwhelming when multiple data sets or complex circuits are evaluated. To overcome this problem, a simple spreadsheet-based mass balance program has been developed specifically for plant operators. To use this program, operators simply enter a description of their circuit and input the assay values (e.g., % BPL, % Insol, etc.) for each stream. The program then generates the best estimates of the assay values and flags values that may be unreliable. The spreadsheet is specifically designed to be easy to use and requires no knowledge of statistics or programming. This manuscript reviews the mass balance problem and describes how spreadsheet programs can be used to evaluate plant data. An example problem involving the analysis of data around a two-stage phosphate flotation circuit is presented.

Jan 1, 2002

By L. Tondo, W. Lim

The high pressure grinding rolls (HPGR) is a relatively new technology which offers the potential benefits in energy savings, circuit simplicity and improved product characteristics in minerals processing applications. Over 300 machines are now operating world-wide, but most of these are used for grinding cement clinker, and relatively few are used in conventional mineral processing. One of the rea- sons for its current limited use in the minerals processing industry is that design, scale-up and flowsheet assessment procedures are seen to be relatively immature and untested. This has reduced confidence in the potential application of the technology. To help rectify this situation an industry funded research project was undertaken, one of whose aims was to develop and prove a mathematical model of the HPGR and a scale-up procedure. Data were collected from tests using laboratory, pilot and in one case a full scale unit (2.2m diameter). A range of feed types were tested including quartz, limestone, kimberlite, bauxite, iron ore and gold ore. These data were then used to develop models of the size reduction performance, power draw, throughput and operating gap for a wide range of pressures, feed sizes, and roll speeds. This paper describes the models that have been initially developed and illustrates their accuracy using some of these data.

Jan 1, 1998

By S. K. Kawatra, T. C. Eisele

Microorganisms, such as the bacteria Thiobacillus ferrooxidans, have been reported to depress pyrite flotation (Elzeky and Attia, 1987; Atkins, 1990). However, the depen¬dence of the depression on the type of organism or on suspension pH is still being determined. In this study, the relative effectiveness of various microorganisms (chemolithotrophic bacteria, chemoorganotrophic bacteria and yeast) over the pH range of 2 to 12 was studied. Screen¬ing tests using microflotation showed that every microorgan¬ism tested was capable of depressing naturally hydrophobic pyrite at acidic pH. Larger-scale experiments with both mineral pyrite and coal pyrite using Thiobacillus ferrooxidans and Saccharomyces cerevisiae as depressants, showed that these microorganisms are very effective depressants for mineral pyrite at acid pH, but they are largely ineffective at neutral and alkaline pH, where the mineral pyrite surface is not naturally hydrophobic. The flotation response of the coal pyrite was completely different from the mineral pyrite. The coal pyrite was most floatable near neutral pH, with the floatability decreasing in acidic or alkaline solutions. De¬pression of the coal pyrite by yeast was not selective between the pyrite and the associated coal under the experimental conditions.

Jan 1, 2000

By G. Barrasso, E. Nordheim

"The European aluminium industry, through its member organisation the European Aluminium Association (EAA), initiated a program on sustainable development for the aluminium industry in 2001. The first step involved the development of a set of sustainable development (SD) indicators for the industry, taking into account of the different interests involved and also the different existing conventions. The indicator set was developed during 2001 and 2002 with the assistance of recognised partners, including Wuppertal Institute from Germany and Versailles University from France. As well, both internal and external stakeholder groups were involved in order to validate the indicators. This has resulted in a set of thirty-four indicators used in the first survey exercise. In the survey the EAA, together with the national aluminium associations, attempted to cover all European plants producing alumina, primary aluminium, rolling ingots, extrusion ingots, foil and recycled aluminium -covering approximately 800 plants. The survey used two points in time, 1997 and 2002, in order to start developing a trend for the individual indicators and to measure progress over time. The industry response to the survey was very positive, with a total industry coverage based on tonnage reported of over 80% for 2002 data and 70% for 1997 data. The results also show a solid progress for most indicators and particularly for social indicators such as training performance, community involvement and employees health programmes. The EAA is committed to conducting this as a regular exercise and is engaged in a number of stakeholder workshops in order to present the survey results, to review the indicators used and to also consider adjustments of these based on feedback from stakeholders and experiences from the first data collection."

Jan 1, 2005

By J. T. Sitarski, R. C. Emmett, L. W. Luinstra, R. P. Klepper

A mining operation in Zimbabwe produces a pyritic gold concentrate that requires oxidative pretreatment prior to cyanidation in order to liberate 80 percent of the gold values. Bio- oxidation offered the potential of increased gold recovery and was considered to be an economically advantageous alternative to the existing practice of roasting the concentrate. Based on bench- scale test work, a small bio-oxidation plant, capable of processing approximately 50 percent of the concentrator production, was installed at the mine to evaluate this approach. The plant included two 57 m3 bioreactors in series and the ancillary equipment needed to prepare the feed concentrate, to wash the leached residue prior to cyanidation, and to neutralize the waste liquor. The plant was operated for a year-and-a-half, and the conditions needed to achieve a 90 percent liberation of gold values were determined. A number of critical technical problems were encountered, and many were resolved on-site. Others have been addressed since the pilot plant was moth-balled in June 1988. Valuable insight was gained from the operation of the pilot plant, which has provided useful guidance for continued process and equipment improvement.

Jan 1, 1990

By Jorge Gutierrez C.

CODELCO-CHILE, the world's largest copper producer, began an integrated study of the informatics situation in the corporation at the end of 1980. As a result, a five years strategic Systems Plan was elaborated and approved by top Corporate management. Main points in this plan were: a systems architecture with information integration to the top level management; a higher degree of information technology in the production areas, an optional systems development resources utilization and a high profitability of the plan itself. During the study phase a series of theoretical definitions were fixed and used as a basis for the plan's design. A "common systems" approach was chosen as the development strategy instead of corporate systems or separate divisional efforts. Top management should be highly involved in the revisions of the plan, as well as qualified users should be chosen as project managers. The systems architecture should grant the information integration to the corporate level, in order to support an integrated planning and administration environment for the corporation. A total of 15 projects were defined, involving 570,000 man-hours and shifting the development efforts towards the production and production services areas. The paper presents a critical evaluation of the whole process, showing its good and bad aspects and a positive global balance. It also points some suggestions and hints to any corporation who wishes to get involved in a similar experience.

Jan 1, 1989

By André G. Journel

As opposed to graphics applications in medical sciences and mechanical engineering, computer imaging of the subsurface faces a severe problem of data shortage. Most graphics softwares include an interpolation algorithm aimed at producing slick graphic output, irrespective of the attribute being interpolated, the quantity and quality of the data available, and what the map is intended for. It is suggested that the power of modern computers be also used in providing representations of the subsurface that accurately reflect actual spatial variability and the large variety of soft information available beyond hard data. Since any subsurface representation is uncertain, a measure of that uncertainty should be provided which can be used for risk analysis.

Jan 1, 1992

By V. Rastogi

Surfactant-based bactericides are able to control acid formation in sulfidic materials such as pyrite and sulfidic ores, thereby helping to abate acid rock drainage. Bactericides are used in the following two ways: as periodic or continuous spray treatments for the prevention of acidification of material actively handled and moved and in controlled-release form for reclamation. Site-specific bactericide treatments are designed for active sites and reclamation. Results from two active coal refuse sites show that acid production can be reduced by 88% or more. Results from reclaimed sites show that bactericide treatment can be more effective than the addition of alkaline materials such as limestone and can reduce acid production from 3,500 to <30 ppm. The controlled-release-pellets treatment outlasts the life of the pellets, as shown by a study of a site now 10 years old A single treatment sets up a change in site microbiology to replace acid-producing Thiobacillus ferrooxidans bacteria with heterotrophic bacteria and creates a stable site without the need for further treatments. A secondary beneficial effect of bactericides is on revegetation, and biomass from treated areas is almost 10 times that from areas not treated with bactericide. Depending on the application, bactericide treatment can be cost effective upfront and certainly long-term, compared to the perpetual water treatment that could be required, even after productive use of the site is completed

Jan 1, 1997

By John C. Galloway, Heinz G. Leistner

ACKNOWLEDGEMENTS The investigations described in this paper were supported by contracts with the Defense Nuclear Agency (DNA) under direction of Lt. Col. John Galloway, and by Boeing Company research funds under supervision of James Wooster. Other engineers of The Boeing Company who contributed to the work of this investigation were Don Armitstead, John McAvoy, and Tom Day. INTRODUCTION In this paper, we are describing a current concept for placing intercontinental ballistic missiles (ICBMs) in sites deep underground to be used as a strategic Future Secure Reserve Force (FSRF). The objective of such concepts is to utilize soil and rock cover to protect high value strategic weapons from destruction by nuclear attack. The burial deep underground achieves two purposes. First, it imposes a miss distance upon the attacking weapon equal to the depth of burial minus any penetration capability the weapon might have. This tends to offset increasing accuracy of weapon delivery. The other purpose is to absorb as much of the weapon&apos;s energy as possible, thus reducing the effects of powerful weapons. This use of soil or rock cover over military facilities began with the development of man&apos;s capability to loft projectiles. Until recently, underground military installations, by their nature, performed defensive functions. Since they are not mobile and their weapons in the past had very limited range, an enemy would have to approach them before an engagement could take place. Thus, they were often used to control "choke points" on sea lanes as in the case of Gibraltar or

Jan 1, 1979

By James W. Martin, Robert R. Faddick

INTRODUCTION Virtually every sector of society in our country feels the impact of tunnels, either through the transportation of water, commodities, or people. The economic implications are staggering. The Committee on Rapid Excavation (1) reported that during the near future, 1968-1975, underground excavation activity will comprise 946 miles of tunnels (subways: 85 miles; underground urban highways: 123 miles; intercity highway tunnels: 210 miles; water supply tunnels: 528 miles) and 5,119 million tons of crude ore; metals: 874 million tons; nonmetals: 899 million tons; and coal: 3,346 million tons. It is estimated that the cumulative demand for underground excavation in the decade 1970-1979 will be 13 billion dollars for construction-oriented demand and 16 billion dollars for mining-oriented demand. The respective figures for the decade 1980-1989 are estimated at 22 billion dollars and 18 billion dollars. Of the many advantages claimed for tunnels (2, 3, 4, 5) the environmental considerations are becoming increasingly important. Transportation tunnels particularly for rapid transit systems, offer reductions in noise pollution and air pollution while improving aesthetics and optimizing land use (fewer problems of right-of-way and disruption of utilities). Considerable interest has been shown recently in sub-surface construction and mining (6, 7, 8). Recognizing the future demands for tunnels has led to considerable study of methods to improve rates of tunnel advance per day, safety, and the overall economics. The search for higher rates of advance has Led away from what has heap termed conventional methods (drilling

Jan 1, 1974