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By Steve Kral

Led by a surge in coal production and prices in recent years, Colorado’s mining industry is taking part in the same revival as others states and the world. Not too many years ago, the state’s industry was languishing in the same doldrums as the rest of the mining world. Ironic for a state whose history was based on mining. Now, however, Colorado’s mining can boast increased production in all commodities produced, along with prices that allowed companies to expand, increase work forces and post improved shareholder value. So there was a lot of optimism at the Colorado Mining Association’s (CMA) 107th National Western Mining Conference in February. The conference, held in Denver, attracted more than 500 attendees and 39 exhibitors. The theme was Colorado Mines the World.

Jan 1, 2005

By Faruk Oksuz

The owners of large infrastructure projects are challenged on how to implement sound engineering and construction contracting strategies that address their prime expectations: a quality job, on time and within budget. With the increasing number of large engineering and construction projects worldwide, owners continue to search for alternative contracting strategies to address their risk, quality, sustainability (operability and performance), schedule, and budget concerns. Coupled with the shortage of resources, delays, political pressures, and other obstacles in procurement and negotiation processes, engineers and contractors are also looking for creative ways to optimize contract packaging strategies for efficient and successful project delivery. This paper compiles an array of decision making criteria and suggests a balanced evaluation, ranking and selection strategy in procurement of both engineering and construction services for large tunneling and other infrastructure projects. A number of owners? general preferences and viewpoints are discussed on large tunnel programs encompassing water and wastewater conveyance systems, pump stations and treatment facility upgrades. Contract packaging strategies and project phasing and segmenting alternatives for preliminary engineering, final design, construction management, and actual construction of facilities are featured for several large water and wastewater infrastructure projects. While the selection (and the relevant selection process and criteria) and performance of service providers, whether for engineering or construction, have profound effects on the outcome of any given project, this paper only examines strategies for con-tract packaging. More specifically, the authors evaluated case studies and developed a range of recommendations for packaging of large water and wastewater infrastructure projects with multiple components.

Jan 1, 2008

By V. Rajaram

The Metropolitan Water Reclamation District of Greater Chicago (MWRD) imposed a no-blasting specification (blasting is restricted to the construction shaft and shaft bottom or boot) on the Deep Tunnel project in 1988. This was prompted by numerous complaints from the residents in the vicinity of the project, and controversies experienced on previous projects from blasting the rock overlying the tunnel. This paper will describe the methods utilized by two major contractors who are driving 20 km (12.5 of tunnel along with drilling over 36 shafts under this restrictive specification. The impacts on design, construction, schedule, cost, and the environment are detailed.

Jan 1, 1991

By C. E. Jordan

The Tuscaloosa Metallurgy Research Center of the Bureau of Mines, U.S. Department of the Interior, is investigating the recovery of phosphate from beneficiation slime, as part of the Bureau's efforts to conserve mineral resources through increased use of wastes. Phosphate equivalent to about two-fifths of U.S. production is discarded annually in the wastes. Exploratory flotation tests on the plus 5-um fraction of a slime sample showed promise for a classification-flotation technique. Onsite classification tests at six phosphate washing plants were conducted with a two-stage hydro cyclone system designed to recover the plus 5-um material. The cyclone underflows contained 8.3 to 19.1 percent P2O5, and the recovery of the plus 5-um PZOS values ranged from 81 to 95 percent. The percent P2O5 recovery from the total slimes ranged from 38 to 47 percent. Batch-flotation studies are currently being conducted.

Jan 1, 1978

By S. C. Tadolini

The use of resin-grouted cable supports to control large ground movements in several types of underground mines has increased substantially since being introduced in 1991. Cables offer several advantages over traditional support systems, having large support capacities coupled with the flexibility to be used in low openings. Cable slings have been designed to be installed on-cycle using no-spin technology or a two-piece unit that can be placed with hand-held drilling equipment. Additionally, yielding cable supports have been developed and are being used to control large amounts of movement in coal and evaporite deposits.

Jan 1, 1998

By E. Arioglu

Y. Luo and S.S. Peng are to be congratulated for their outstanding paper providing new results from surface subsidence monitoring over longwall panels under different conditions. This writer found the authors' paper very interesting. In reference to this paper, the following contributions are offered: • In the paper, the maximum possible subsidence (?Smax) induced by chain pillar convergence has been related to a parameter (h/I -p) by linear regression. (Notations are expressed in this discussion's Fig. I (b).) It is a well-known fact that in a goaf the roof lowers onto broken material that gradually compacts. Then the physical behavior of goaf may closely follow the compaction characteristics of broken materials. In light of this assumption, a mathematical means (Fig. 1(a)) of defining the expected compaction (i.e. surface subsidence) represents an exponential expression between ?Smax/m vs. h/1-p. This is based on Luo and Peng's field observations from the Appalachian, Illinois and Alabama coal fields. (The coefficient of regression "r" under consideration was computed to be 0.883). • According to Wardell's (1969) findings for board and pillar mining, the maximum possible subsidence can be expressed in terms of maximum pillar loading (depth, ratio of extraction) and the height-to-width ratio of the pillars left. Using Luo and Peng's 1991 results, this writer discovered a regression equation between the above-mentioned factors. As displayed in Fig. 1(b), the functional expression approximates as closely as possible the observed subsidence data.

Jan 1, 1992

By Tim Neil, O&apos

The coming years should see moderate growth in the US coal industry. That growth may come at the expense of the oil and natural gas industries. Conoco pegs coal growth at 2% a year, until the year 2000. During that same period, Conoco projects only 0.5% annual oil growth and "a flat or negative trendline" for natural gas. This is compounded by the fact that coal has a delivered cost per Btu that is only half as much as it is for natural gas and only a third as much as it is for oil. So said Ralph Bailey to many of the 2600 attending the opening session of the American Mining Congress Coal Convention, May 12-15, in Pittsburgh, PA. Bailey is chairman of the AMC. He is also chairman of Conoco. While coal's projected growth is not spectacular, "it is in fact almost an assured growth," Bailey said. Weak oil and gas prices will likely prevent faster growth for US coal. Most of coal's increased demand will come from the electric utility industry and expanded steam coal exports. Conoco's study projects that domestic coal demand will be strengthened in the 1990s. By then, the present surge of nuclear power plant constuction will be over. And there will be a lack of acceptably priced, large-scale generation alternatives for utilities. "It is not likely that any electric utility is going to be ordering new nuclear reactors," Bailey said. "And as oil and gas supplies become scarcer and more costly, it is only logical that coal is going to fill the gap." At the same time, Bailey believes the US coal industry must find ways to lower its costs. He said cost excesses can be found in "regulatory overkill, labor, and simply bad habits" hidden by years of high inflation. "Those costs have now been laid bare, because we are going through a pe¬riod of disinflation. We have to put our house in order, particularly if we are going to compete in world markets." Bailey also touched on coal research. "The industry certainly accepts the fact that we must find a way to burn coal as cleanly as possible. A lot of work in that regard is going on. I expect there will be some significant break-throughs." Bailey said the coal industry is being squeezed this year. Last year, coal customers accumulated inventories in anticipation of a major coal strike that never materialized. Now, many utility customers are working down these inventories. So they are not taking deliveries on their coal contracts. But coal use is up in 1985, compared with 1984, Bailey said. So increased coal use, along with supply drawdown, should strengthen the coal market before the year is out, he said. After Bailey's presentation, some 100 speakers addressed policy and technical topics at 15 sessions during the four-day meeting. It was the first time since 1977 that the AMC Coal Convention has been held in Pittsburgh. And this year's attendance was up 40% from the last AMC Coal Convention held two years ago in St. Louis, MO. This year's registrants included 228 companies, 225 manufacturers, and 106 associated members. The only negative was the David Lawrence Convention Center. It was less than ideal. By turns, meeting rooms were too small, too cramped, or too far from one another. The session on longwall mining was so crowded that the doors were propped open so conference delegates could peer in. A concurrent manufacturers' forum session needed 50 more chairs to accommodate those wanting to attend. However, on to summaries of some of the presentations. Coal transportation and export Since Congress approved the 1980 Staggers Rail Act, railroad rates for hauling coal have not been excessive. In fact, rail rates for coal have increased less than 0.5% a year, in real terms, since 1980. Moreover, the market oriented principles written into Staggers are contributing to the improved financial and operational health of the nation's railroads. But no railroad is earning excessive profits. That is the gist of a coal transportation study being completed by the US Department of Energy. William Vaughan is DOE's assistant secretary for fossil energy. He affirmed the thrust of the upcoming report. Vaughan did allow that Interstate Commerce Commission (ICC) regulations on rate reasonableness could permit the railroads to exploit their monopoly power on captive shippers. Luncheon comments later made by Don Hodel confirmed Vaughan's comments on railroad rate justification. Hodel is Secretary of the

Jan 7, 1985

By Ann M. Gosier

Over the past 20 years, diesel-powered equipment has been introduced into the underground mining environment in increasing numbers. While the introduction began years earlier in the metal-nonmetal sector, the exponential growth in coal mining use during this time has been more pronounced. Reasons for the continued use and rapid growth of diesel equipment in underground mines are easily understood. The safety and operational advantages afforded by this equipment in production and support systems are demonstrable. As other mine operators witness the advantages enjoyed by their competitors, they too move to introduce an increasingly diverse array of such equipment into their underground mines. As with any industrial technology, the use of diesel-powered equipment entails potential safety and health concerns. Existing Mine Safety and Health Administration (MSHA)approval regulations (30 CFR Parts 31, 32 and 36) apply only to diesel locomotives and mobile diesel-powered equipment for noncoal mines. In the absence of specific regulations, MSHA has required the use of equipment approved under Part 36 (gassy noncoal mines) for areas of underground coal mines where permissible electrical equipment is required. However, a considerable amount of diesel-powered equipment without explosion-proof or fire prevention features is in use in areas of coal mines where permissible electrical equipment is not required. It is on the use of this latter class of equipment that MSHA is focusing much of its regulatory attention relative to coal. The agency also is focused on revising existing occupational exposure limits for gaseous emissions and instituting limits on diesel particulate emissions for both coal and metal-nonmetal mines.

Jan 1, 1993

By J. Finch, J. Yianatos, N. W. Johnson, R. Espinosa-Gomez

A method of determining the maximum concentrate solids rate or carrying capacity is described for given column operating conditions. The method requires alteration of the feed rate of solids to the column at a fixed residence time by manipulation of the % solid of the column feed pulp or the bias rate. The carrying capacity was measured for five streams at the Mt. Isa Mines Pb/Zn and Cu concentrators. As a potential scale up parameter, the mass of solids per unit time per unit column cross section (Ca, g/min.cm2) is explored. Ca is tentatively related linearly to the 80% passing size (d80) of the concentrate. For d80 < 15 pm Ca was less than 4 g/min.cm2 (8 lb/min.ft2) which makes it a critical consideration in scale-up for such fine feeds. An alternative carrying capacity parameter, mass of solids per unit volume of gas Cg was not as useful as Ca since Cg varied inversely with gas rate.

Jan 1, 1988

By A. D. Davis

Limestone-based material shows great promise for removal of arsenic from water. In laboratory tests, it has removed more than 95% or arsenic and more than 99% of cadmium and lead. In addition, the waste material appears to be suitable for recycling or disposal in an ordinary landfill. However, the efficiency of limestone for arsenic removal could be improved. Recent research has shown that iron treatment of limestone can enhance its arsenic-removal efficiency greatly, increasing its attractiveness as an alternative to other methods.

Jan 1, 2012

By J. S. Hall

The productivity and fuel efficiency of iron-ore blast furnace operations has greatly increased in recent times. These improvements, particularly to the Japanese steel industry, have primarily arisen from process engineering studies of the blast furnace and associated operations such as sintering. The development of fluxed sinter based on iron-ore fines reacted to produce highly reducible, low slag sinters has contributed further to a reduction in fuel requirements. The Pilbara province of Western Australia is a significant source of these iron-ore fines supplied to the international market. Increasingly, this market is being offered high quality ores from other foreign sources. To technically assist companies in improving the processing efficiency of ores, and to improve the technical marketing of ores by modelling the processing characteristics of Australian/international ore blends, the Commonwealth Scientific and Industrial Research Organization (CSIRO) is actively assisting the industry by researching the general theme of &apos;iron ore from mine to metal in this paper we outline progress towards a numerical description of: a. ore deposit classification. b. Degradation during transport. c. Direct reduction of iron ore. d. Liquid bath ore reduction/smelting. e. Industrial sintering.

Jan 1, 1986

By G. L. Alston

The mine disaster last November in northern West Virginia has compelled the coal mining industry to take a closer look at the methods of transporting and applying rockdust. The USBM has indicated they would like to see a minimum of 80% incombustble in the back entries and want rockdust to be maintained to within 40 feet of the face at all times. With today&apos;s high rate of advance of mining machines it will be necessary to apply dust in the immediate returns continuously and the working places mutt have dust applied during the operating shift. The inspectors have become more demanding in requiring clean-up of coal and coal dust in the working place before rockdust is applied and are insisting on better clean-up and better rockdust applications along belt conveyors. Maintaining a constant application of rockdust in the back entries can be done with a Trickle-Duster. The machine is designed with hopper capacities of either 400 or 1,000 pounds of dust. The discharge rate of dust being fed through 1-1/2 inch diameter hose can be adjusted from 1/2 to 5 pounds per minute. The hose is extended into the return through the last open breakthrough and the return air carries the rockdust along w th the coal dust, depositing them uniformly on rib, roof and bottom.

Jan 1, 1969

By Jon P. Thorson, James W. Babcock

The second Belt Symposium in Missoula, MT, Oct. 9-16, 1983, was designed by its conveners as a field conference on progress in the Proterozoic Belt Supergroup rocks. The symposium was sponsored by the University of Montana with corporate support by Anaconda Minerals. Asarco Inc., Exxon Minerals Co.. Hecla Mining Co., Molycorp Inc., Noranda Exploration Co., and Utah International Inc. Introduction The Belt Supergroup is a thick middle Proterozoic sedimentary sequence deposited in a basin along the edge of the North American craton. Subsequent geological events have modified the basin so its remaining rocks outcrop in Montana, Idaho, northeast Washington, southeast British Columbia, and southwest Alberta. The Canadian equivalent of the Belt is called the Purcell Supergroup. Several similar age basins occurred along the western edge of the Proterozoic North American craton. The sedimentary sequence in the Belt basin aggregates is more than 18 km (60,000 ft) in the thickest section, where the bottom is still unexposed and the top removed by erosion. The limits of the Belt basin are poorly known because of later sedimentation and tectonic disruption. Knowledge about the Belt terrane has been difficult and tedious to obtain because the rocks are generally monotonous and fine-grained. During the last decade, new 1:250,000 scale reconnaissance maps of most of the Proterozoic Belt terrane were published, open-filed or otherwise brought close to completion. These maps provided the opportunity and challenge to consider the stratigraphy and tectonics of the Belt Supergroup as a complete basin. This broader view has contributed greatly to the solution of numerous geological problems created by previous, more focused work. Along with the availability of better geological base, there have been new exploration developments. The 1973-1983 decade saw proof of the commercial viability of the Cu-Ag mineralization at the Troy mine. The conclusion was also accepted that the Sullivan mine was a sedimentary massive sulfide. So was the conclusion that the Cu-Co mineralization at the Blackbird mine at Cobalt, ID, was the result of similar submarine exhalative processes. And there were discoveries of another Cu-Ag deposit "larger and higher grade" than the Troy mine and of two new massive sulfide districts. The Belt-Purcell terrane has long intrigued exploration and mining geologists as the host of Pb-Zn-Ag veins of Idaho&apos;s Coeur d&apos;Alene district and of the Sullivan mine at Kimberley, British Columbia, one of the largest Pb-Zn-Ag deposits in North America. In the mid-1960s, Bear Creek Mining Co.&apos;s discoveries of the stratabound copper-silver occurrences in the Revett Formation brought new interest in the basin&apos;s geology. The recognition of the Sullivan ore body as a sediment-hosted massive sulfide has also generated minerals exploration activity in the US portion of the Belt basin. This activity increased again after the Australian discovery of the world class Olympic Dam deposit at Roxby Downs, South Australia. This occurred because of some suggested similarities in the regional geologic setting of the Belt basin with the Adelaide geosyncline, the host for the Olympic Dam deposit. Technical Sessions Technical sessions topics included Lower Belt and Ravalli Group stratigraphy, Middle Belt carbonate and Missoula Group stratigraphy, Belt-Purcell stratigraphy, structure and tectonics, strata-related mineral resources, geochronology and geophysics, geochemistry and isotope geology, and a summary of significant problems. Evening poster sessions dealt with the topics and papers presented each day. Since the first Belt Symposium, mapping of the stratigraphic units and their tectonic setting has enabled geologists to progress in conducting a basin analysis. Belt Symposium II revealed no concensus on many aspects of belt geology. However, basic stratigraphic studies have reached the point that models can be constructed. The Prichard Formation is equivalent to the Aldridge Formation, but detailed correlations were not previously available. Studies were made by Finch and Baldwin (Cominco American) and by Cressman (US Geological Survey). These studies established important correlations of key markers within the Aldridge Formation to units in the Prichard Formation. This will help eliminate geologic interpretation problems at the US-Canada frontier and make Belt basin reconstruction more accurate. Also, the Sullivan ore deposit was shown to be formed in the deeper distal part of the basin. This contrasts to the more proximal depositional position of the Prichard Formation. Hamilton

Jan 6, 1984

By David M. Parkes

The hydraulic movement of coal is here defined as the movement of all sizes of coal in pipes and open flumes, by gravity and against gravity. It is not restricted to coal which is in slurry form. In other words, it is not crushed to a size in the 8 to 20 mesh size range. The top size could be as high as 12 inches. The dewatering of coal which is transported hydraulically is carried out to restore the coal to a suitable form for further cleaning, or for transportation by other methods. The process involves complete separation of all the coal, wood and rock from the water so that the water can be recycled without undue damage to pumps, pipes and monitors.

Jan 1, 1976

By M. Misra, I. Anazia

The effects of the enzyme, peroxidase, on the sedimentation and consolidation characteristics of Florida phosphate slimes were investigated. Results indicate that pretreatment with the enzyme was beneficial for slime dewatering and consolidation. Biological activity, resulting from slime pretreatment with the enzyme, induced higher mechanical binding between slime particles.

Jan 1, 1990

By F. Mielli

Mine operation managers are constantly tasked with identifying new ways to produce more, while using less. Mine effectiveness and reliability is the foundation of improving operational performance. Timely decisions need to be made in order to identify production waste. Intelligent data needs to be visualized in real-time. Operational events need to be captured with impacts quantified and root causes identified. Unfortunately, complex information technology solutions often have a very poor success rate, with some reports suggesting 30 percent of complex projects are canceled before completion.

Feb 27, 2013

By Terry P. McNulty

During the last 30 years, at least ten authors have dealt with startup ("ramp-up&apos;) times for minerals beneficiation, hydrometallurgical, and/or pyrometallurgical plants. Most have attempted to identity the reasons for delays and some have suggested attributes common to successful startups, as well as those shared by unsuccessful ones. The most recent has advanced a project characterization matrix as a predictive tool for qualified users. This paper will summarize past work, will review cause and effect, will outline an approach for refining our ability to avoid costly delays, and will seek guidance from professionals most likely to use such a tool. INTRODUCTION During the last few decades, many billions of dollars have been lost by investors in mineral industry projects that did not perform as well as their developers had hoped. The most common form of failure has been the inability to generate a profit quickly, and delayed achievement of planned production rate has been the chief cause. Minerals processing projects are by no means the only kind of plant to suffer from startup delays, as some authors cited in this paper considered inorganic chemical plants and other types of facilities. Furthermore, mines are not without fault and there have been many that were closed after years of disappointing performance. However, our interests as a group are most sharply focused on mineral processing and our database for such projects is relatively extensive. It is sufficient to say that the conclusions made or repeated in the following text can be readily extended to most types of projects.

Jan 1, 2004

By Joseph M. Morrison

This paper offers a comprehensive solution to the problem of dust emissions at belt conveyor transfer points. It discusses details of enclosure design and presents a straightforward procedure for calculating required dust control exhaust volumes. Many design variables are taken into account which heretofore have been commonly ignored or inadequately considered. These include belt widths, belt speeds, enclosure openings, material flow rates, material bulk densities, material lump sizes, height of material fall, material temperature, and ambient air temperature. All of these quantities are handled by means of a "fill-in-the-blanks" type of calculation form which permits quick, reliable solutions by relative "non- experts".

Jan 1, 1970

By George S. Koch

Today, after about 30 years of development, computer-based analysis of geoscience data has reached a mature phase. From the tentative early beginnings recorded in the proceedings of the APCOM meetings, geoscientists are now able to emphasize the need for both pertinent mathematical/statistical models and computer hardware and software. From those models that are well understood in the disciplines of statistics and mathematics and for which effective computational methods are available, practitioners select and develop methodology for their particular purposes. Computer hardware is typically assembled from off-the- shelf components now readily available, with particular emphasis, whenever feasible, on microcomputers for reasons of economy and control by the scientific or engineering user rather than by a bureaucratic computer center. Computer software may be written by the user in high level languages such as Pascal, FORTRAN, or LISP. However, more often today geoscientists use routines available in spreadsheets, data bases, or statistical packages. In so doing, they save time and, programming costs and take advantage of routines written and maintained by large, well- established organizations, while losing the flexibility in specifying exact input/output afforded by writing in a high level language.

Jan 1, 1989

By Travis S. Wellman, Jon C. Volkwein

The Bureau of Mines conducted a study to assess the impact of a directional water spray system on a unique single inlet dust scrubber on a low profile mining machine. Tests were conducted in a full scale model mine using a Joy 12 CM 10-AA continuous mining machine. Tracer gas was introduced at the face and concentrations of the tracer gas were monitored at the face and in the return. Various parameters included: mining position, depth of cut, brattice setback and combinations of scrubber, directional sprays or symmetrical sprays. Results indicated that either directional or symmetrical water spray configuration improved the ventilation effectiveness of the scrubber by a factor of 2 to 3. Average face ventilation effectiveness (FVE) values for all testing of the scrubber and directional sprays were 0.95, versus 0.37 for a standard 6 m (20-ft) blowing curtain without sprays. No FVE values were less than the standard 6 m (20-ft) blowing results.

Jan 1, 1989