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By R. O. Vernon

The Florida Peninsula has existed as a part of a much broader plateau, since at least the Early Cretaceous. This plateau, the Floridan Plateau, now consists of the present peninsula and a broad submerged shelf of equivalent size extending the length of the state and out into the Gulf of Mexico. Florida Peninsula was separated from the mainland United States by a negative area called the Suwannee Straits. To the south of this feature existed an environment similar to today?s Bahamo Banks where very pure calcium and magnesium carbonates with associated evaporites were deposited. Thus the Eocene and Oligocene contain little or no quartz sand or clay minerals except in the Panhandle west of the Suwannee Straits where some clastics were contributed by rivers from the north.

Jan 1, 1966

By B. J. Arnold

Coal blending inherently means homogenizing a mixture of coals so that the properties of the blend meet some specifications for maintaining power plant performance and emission requirements. In practice, however, coal blending is, at best, coal mixing. The degree of blending sophistication required depends on the reason for coal blending in the first place. If it is to maintain fuel characteristics that will diminish the chance of slagging and fouling, then some swings in variability may be tolerated at some power stations. However, if emissions limits are the issue, then more sophistication may be needed. Emissions limits are becoming stricter with requirements to meet averages for shorter time frames (hours and days instead of weeks and months). These restrictions require closer control over the quality of the blend being fed into the bunkers at the station. Even scrubbed units should have a consistent quality of fuel as feed so that sorbent additions can be minimized. To meet these challenges, engineers must consider available equipment and control techniques and the properties of the parent coals when evaluating new blending systems.

Jan 1, 1994

By W. J. Kogelmann

Roadheaders, also called Boom Miners or Boom-type Tunneling Machines have been in North America since 1968, when first introduced by Willy Kogelmann, the founder of Alpine Equipment Corp. (?Alpine?). Roadheaders were invented in Europe in the late 1940s. Machines with in-line, axial cutter heads were developed in the former Soviet Union. The British Dosco DRCL is based on the Russian PK-3 roadheader. Roadheaders with transverse ?ripper? cutter heads were invented in Hungary (1). The Austrian-made Alpine Miners of VOEST-Alpine, purchased by Sandvik AB, are based on a 1965 Hungarian license. Roadheaders are widely used in the mining and tunneling industries because they can excavate drifts, entries and tunnels with cross sections of any shape and size, can handle mixed faces, work on steep grades, and negotiate tight curves and cross-cuts. A roadheader?s only major limitation is the strength and abrasiveness of rock and minerals to be excavated. This paper covers roadheader selection criteria, improvements in reliability, attachments for flexibility (Multi-Tool Miner), and automated support systems for increased cutting time for increased shift production.

Jan 1, 2008

By Stanley Dempsey

Since its passage, the Mining Law of 1872 has been modified several times to meet the changing needs of America's society and economy. Despite the fact that it continues to provide an effective framework for a robust US exploration and mining industry, the mining law continues to be criticized in some quarters as outdated. Pressure to reform the Mining Law of 1872 has reached new levels in recent years. Many proposals for reform of the law have been introduced during the 1990s. None, though, have been enacted. The issue will not likely disappear and is certain to be raised during the 105th Congress. To provide a better understanding of the status of current congressional reform proposals, this article presents an overview of the major moments in the history of mining laws in the western United States - from the days before the 1872 mining law and the days following its promulgation, to the current dilemma over mining law reform. The future of the mining law is assessed as are the interests at stake for the modern mining industry. Mining before 1872 No discussion of the Mining Law of 1872 is complete without some historical background to provide an understanding of the origins of this unique law. There was plenty of mining activity on the public lands before the mining law was enacted. At first, the federal government's policy was to allow all miners to work freely on the public lands and to resolve disputes among themselves. In this "hands off" environment, miners operated according to laws they promulgated. These were based on previous experiences in Europe and Mexico. These "frontier codes" of groups of individual miners took the form

Jan 1, 1997

By G. B. J. Leon, M. Karmis, C. Newman

"The prediction of surface deformations due to underground mining operations has been a long recognized practice with case studies documented as far back as 1556 in Georgius Agricola's De Re Metallica (Latin for On the Nature of Minerals). There is currently increased public awareness and regulatory scrutiny on the potential impacts of underground longwall and second mining operations, but this time the focus is placed on environmental impacts to overlaying bodies of water such as streams, rivers, wetlands, lakes, etc. (Karmis and Agioutantis, 2015). Community residents and environmental groups, as well as federal and state regulatory agencies, have often cited adverse stream impacts and demanded stronger measures and scrutiny in issuing mining and reclamation permits (Booth, 2006). Mining companies are required to focus on the protection of sensitive bodies of water through the monitoring of stream flow and water quality, management and rehabilitation techniques, as well as the adoption of ""no mining zones,"" which potentially sterilize large portions of minable coal reserves. This paper examines the use of an empirical modeling approach for the protection of surface streams based on evaluation of ground strain magnitudes. Utilizing enhanced features of the Surface Deformation Prediction Software (SDPS), ground movements can be predicted accurately in the vicinity of surface bodies of water. The modeling of ground movements can aid in establishing optimum extraction sequences, while the magnitudes of anticipated subsidence can be used in the evaluation of mitigation plans when undermining surface bodies of water. INTRODUCTION When utilizing high recovery underground mining methods, such as longwall or room-and-pillar mining, the movement and deformation of the overburden propagates toward the surface and may affect the integrity of overlying surface streams (Peng et al, 1996). Published studies cite three major mechanisms of subsidence as most likely to impact streams: displacement, slope, and strain. While subsidence-induced vertical displacement cause little structural damage to the stream bed, it may create adverse drainage and stream flow issues as the subsidence trough allows for ponding (Dawkins, 2003). Subsidence initiated changes to the slope, or tilt, of a stream may have adverse effects on water flow. As the stream enters the subsidence trough, the gradient increases providing potential erosion control problems. When exiting the subsidence trough, a reduction of the gradient may inhibit stream flow, causing localized ponding (Peng, 2008). While vertical displacement and tilt both may have detrimental effects to surface streams, subsidence induced strains have been documented as being the most damaging to surface streams and structures causing distortion, fractures, or failure (Singh, 1992). When stream beds are subjected to high tensile strain, tensile cracks may form at the surface level allowing for the direct loss of stream flow through fissures. When stream beds are located in areas of high compressive strain, rock layers forming the stream bed can fail as the stream bed, ""ruptures,"" upward blocking stream flow or having the stream diverted into the facture zone at the base (Iannacchione, et. al., 2010)"

Jan 1, 2016

By Richard H. T. Garnett

In 1900, placer gold was discovered on the beach of Nome, AK on the southern coastline of Alaska's Seward Peninsula (Garnett, 1991). The site is about 800 km (500 miles) from Anchorage. Nome is connected to Anchorage only by air (daily) and by sea (summer). Total onshore placer gold production from Nome's immediate vicinity was more than 155.5 t (5 million oz). Alaska Gold Co, has continued to produce gold onshore with, until recently, two bucketladder dredges, each of 255-L (9-cu ft) bucket capacity. Small-scale marine dredging for gold has been at- tempted several times this century (Garnett, 1991). Western Gold Exploration and Mining Co. Ltd. Partnership (WestGold) is the only company to have been successful in achieving a significant offshore production. The Nome bucketladder-dredging operation from 1986 to 1990 constituted a unique marine-mining experience in the United States. \Inspiration Gold Inc., WestGold's predecessor, acquired six offshore leases in 1985. The total lease area of 87 km2 (21,551 acres) extended from the coastline to the 4.8-km (3-mile) offshore limit (Fig. 1). Those leases al- ready had been partially explored. Drilling was conducted off the shorefast winter sea ice. Therefore, it was rarely more than 1.6 km (1 mile) from the shore or in water deeper than about 9 m (30 ft). In 1985, estimated reserves comprised of a 5-m (17-ft) vertical thickness of sediments below 6.3 m (20 ft) of water. This meant a mean digging depth below the mean sea level (msl) of 11.3 m (37 ft). It was thought that the offshore Nome deposit possessed a feature that is common with many terrestrial gold placers - the secret of profitable exploitation of the marine deposit lay in maximizing the dredge throughput to minimize the unit costs. The inability of the project to withstand the prohibitively high cost of a new dredge was recognized. So Inspiration Gold purchased a used unit. This was the world's largest ocean- going bucketladder dredge (Fig. 2). Binzn was an 850-L (30 cu ft) bucket capacity dredge that was lying idle in Singapore. Originally constructed in the Jurong shipyard of Singapore in 1979, Bima was designed by Mining and Transport Engineering, a subsidiary of IHC Holland. Billiton Marine used the dredge for tin production at Pulau Tujuh in Indonesia (Dieperink, 1978) before it was laid up in mid-1985. Bima underwent a nine-week refit before departing Singapore on June 4,1986, with 800-t (880-st ) of deck cargo. It was dry-towed for 32 days to Alaska. A slower, less expensive, wet-tow at the authorized 5.5 kmthr (3 knots/hour) would have delayed the dredge's arrival in Alaska untl almost the onset of winter. The 13,000-km (8,100-mile) voyage was made on the deck of Smit Lloyd's "Giant-4" submersible barge towed by its 7.8- MW (10,500-hp) tugboat. The first season's dredging revealed several major shortcomings in Bima. Further repairs and modifications were undertaken at Tacoma, WA. The dredge returned to Nome for the June start of the 1987 summer dredging season. The refitted Bima worked offshore at Nome from 1987 to 1990. It produced 3.67 t (118,078 oz) of gold at an average recovered grade of 824 mg/m3 (0.0204 oz/cu yd). In 1991, the dredge was dismantled and sold.

Jan 1, 1997

By J. E. Hoffman, Massimo Maccagni, T. J. Keefe, Marco Olper, O&apos

The problem relating to the use of insoluble anodes in acidic and highly aggressive environments has still not been definitely solved, and it is therefore a recurring subject of discussion. The fields of application in which insoluble anodes play a fundamental role are mainly in the electrolytic extraction of metals, in cathodic protection with impressed current, and in the production of oxidized halogenated salts. Based on the foregoing, B.U.S Engitec Servizi Ambientali (BESA) developed an electrode suitable for the use in the above-mentioned system. The basic component of the BESA anode is a bimetallic wire made of a copper rod (core) covered by a thin layer of valve metal, to be chosen between tantalum (Ta) and niobium (Nb). The wires, coated with suitable catalyst (PbO2, Pt or others) are inserted in a plastic frame and fixed to a current feeder by means of a screw, ensuring an optimal contact. Experimental data on the operating conditions, such as kind of electrolyte, current density, electrode potential, corrosion tests and fields of possible application, are described.

Jan 1, 1993

By E. D. Hummer

During the planning phase of the fine coal cleaning addition at the Gary Coal Preparation Plant, careful consideration was directed toward the problem of minus 48 mesh refuse disposal. The plant flow sheet included wet screening the raw coal at 1/4 inch, pumping the minus 1/4 inch raw coal to bowl desiltors for desliming, and then cleaning the disliked raw coal on tables. The material to be removed from the circuit as minus 48 mesh refuse consisted of the minus 100 mesh desiltor overflow thickened in two 120 foot diameter thickeners and minus 1 mm screened from the table refuse. Later a flotation plant was added to recover coal from the desiltor overflow, and a classifier replaced the screens to make a sharper size separation of the table refuse at 48 mesh Today the minus 48 mesh refuse at Gary consists of thickened flotation tailings and thickened spiral classifier overflow. The transportation of large quantities of fine wet refuse filter cake mixed with jig and table refuse over existing conveying equipment would have been neither dependable nor economical. Filtration was therefore impractical, and disposal of the fine materials was a problem. The decision was to pump the material to storage ponds

Jan 1, 1965

By James J. Scott

Shale formations are the Nemesis of the Mining Engineer. Shales react to changes in environment in the most unusual and unpredictable manner. Increase in temperature may cause spalling, increase moisture and compression induced fractures may occur, and if a full face is exposed it may deteriorate due to atmospheric exposure. Combine only small amounts of shale in layered fashion with hard brittle competent rock and the whole structure may be fractured and fail due to stresses generated in and around the shale. In this paper the author will discuss failure mechanisms encountered under various field conditions and remedial action which may be employed by the engineer.

Jan 1, 1969

By Corneille S. Ek

Flotation of several copper and lead-zinc ores has been carried out with mercaptobenzothiazole (MBT) as promoter. The results of laboratgory batch flotation tests have been compared with those obtained when using more common collectors like xanthates or dithiophosphates. It generally appears that MBT is an effective collector of all the sulfides, including pyrite, but that high selectivity is rather difficult to attain, except for gangue drop-out. Some kinetic tests have been performed to check the froth production rate by MBT as compared to other collectors.

Jan 1, 1995

By Shinya Ono, Tsuyoshi Katoh, Yuusaku Tominaga

In order to monitor/control airflow rate distribution in a complicated ventilation network installed many regulators, an integrated system composed of expert system, exerting programs for simulation to get macroscopic characteristics and drawing diagram, monitoring system and so on is introduced in this study. This system is made up of airflow velocity sensors and computers linked to an local area network. The main results of this study are as follows; 1) Combinations of two branches to monitor aerodynamic resistance change in a branch p in a network can be selected by comparing factor's value in a branch relation table. 2) When the combination of sensor branches for a branch p does not exist in the network at present condition, the system changes aero- dynamic resistances of appropriate branch q placed a regulator by referring branch relation table. And then the system asks other computer to get macroscopic characteristics under altered value of aerodynamic resistance of the branch q. 3) Dot pattern diagram shows airflow rate relation between an active branch and a passive branch. Three relations such as a) a straight line, b) a monotonous curve and c) extremums are displayed in different patterns for all the sets between an active branch and a passive branch at a time. 4) The ranges of airflow rate in coal faces by changing aerodynamic resistance of any one branch placed a regulator are shown in the Pareto diagram using values in the branch relation table. 5) Ventilation transfer diagram with two parameter, one shows airflow rate in a coal face and the other shows energy provided by main fans to overcome aerodynamic resistance in a net- work, is utilized to decide countermeasures for decreasing energy consumption in the network on increasing of airflow rate in the specified branch.

Jan 1, 1995

By V. K. Kollipara

Dust dispersion characteristics in mine airways are important for developing engineering controls for dust and explosions. Authors here have used CFD modeling approach to analyze the dust dispersion characteristics in mine airways. The technique was initially validated with the published field experimental data. The results obtained were in a reasonable agreement. CFD validation results show that in a single entry the dust concentration decreases exponentially as a function of distance. Finer particles can travel up to a distance of 350-400 m away from the source. Parametric studies indicate that air velocity and input dust concentration has significant influence on dust concentration distribution. CFD modeling was then applied to study the dust dispersion characteristics in a room-and-pillar mine layout. Preliminary results show that dust concentration distribution is highly dependent on the airflow patterns and air velocity distribution. The distribution is not exponential until the velocity in the travel way becomes uniform. Data developed in this study may be used to design mine layouts and engineering controls for dust control and explosions.

Jan 1, 2011

By L. B. Sand

Zeolite ores and protores occur in extensive deposits in the western United States. A recent paper1 describes the general geology and mineralogy of these deposits and their geographical distribution. The zeolites are alkali-and silica-rich varieties of mordenite, erionite, chabazite, phillipsite, ferrierite, and clinoptilolite. The zeolites were formed primarily by the alteration of Tertiary pyroclastics and in some cases by the alteration of Tertiary siliceous flows. The altered pyroclastics are of principal economic significance. The volcanic ash and tuff were deposited in restricted basins where saline lakes developed. The pyroclastic layers often are of uniform thickness and macrotexture for miles from the center of the basin and interfinger with detritals toward the edge of the basin. Thus, in addition to unaltered volcanic glass, the gangue minerals in these deposits include some combination of primary minerals in the pyroclastics, alteration products of the glass other than the zeolite of interest, and detrital minerals. The gangue minerals include quartz, cristobalite, tridymite, opal, orthoclase, micro cline, montmorillonite, hornblende, calcite, gypsum, thenardite, and iron oxides. The presence of one or two other zeolites in the layer in some cases also is considered as gangue. There are no quantitative mineralogical descriptions of these deposits in the literature; this: study was undertaken to obtain this information. As the zeolites occur as single crystals, crystal aggregates, zeolite-glass particles and in cemented aggregates, a method of study was chosen which would give the size distribution of the zeolite in these types of association. For this reason dispersion of the rock was achieved with a minimum of grinding action. This excluded those zeolite ores, silicified by hydrothermal altera¬tion which require grinding. A relative index of the ease of disaggregation of the zeolite ores thus is obtained, but the technique does not give absolute size distributions of the zeolite crystals. Samples were selected for analysis which do not necessarily represent the best ore horizon, but do represent a spectrum of zeolite occurrences from significant deposits. They are mordenite, erionite, and phillipsite from Rome, Oregon, clinoptilolite and chabazite from Reese River, Nevada, chabazite (and var. herschelite) from Bowie, Arizona, erionite from Jersey Valley, Nevada, and erionite from Pine Valley, Navada.

Jan 1, 1967

By J. J. Zimmerman

Over-exposure to noise remains a widespread, serious health hazard in the U.S. mining industries. Most other categories of illnesses and injuries associated with mining have improved, with the exception of hearing loss. Mine Safety and Health Administration (MSHA) coal noise data from 2000-2004 show that the continuous mining machine is first among all equipment with 35% of the noise overexposures. Joy Mining Machinery, in collaboration with the National Institute for Occupational Safety and Health (NIOSH), is conducting research to reduce noise generated by continuous mining machines. This paper describes a ?JOY Designed for Noise Reduction? (JOY-DNR; Patent Pending) tail section as a noise control for reducing the noise overexposures of continuous mining machine operators. Underground results show a 45% and 65% noise exposure reduction for the operator when compared to a standard machine. Utilizing this newly developed noise control, along with previously proven controls, will provide continuous mining machine operators an opportunity to be within the MSHA-Permissible Exposure Limit (MSHA-PEL).

Jan 1, 2010

By R. W. Bartlett

Aeration curing, over- a long duration in wet- red stockpiles, shows promise as an affordable pretreatment method for oxidizing gold encapsulating sulfide minerals, and possibly organic matter, in low grade refractory ores. Following aeration pretreatment, the ore is reclaimed, neutralized, and cyanide leached by conventional practices. Large tonnages of subeconomic material, including mine stripping waste, may he converted into ore by this new technology. The results presented show that a successful application of this technology will likely require crushing to about -2 cm (-3/4 in.), followed by aeration in a wet stockpile for long periods, up m three years. Natural convection may he inadequate, hut forced air ventilation, at modest pressures and power consumption, is affordable.

Jan 1, 1991

By A. Bascetin, A. Nieto

One of the most difficult problems in mining operation is how to determine optimum cutoff grades of ores at different periods over the lifespan of the mine that will maximize the net present value (NPV) of the mine. Cutoff grade optimization maximizes the NPV of a project subject to capacity constraints in the mine, mill and the market.. This paper describes the determination of a cutoff grade strategy based on K. Lane’s algorithm adding an iterative optimization factor calculated for every year during the live of the mine to maximize the project’s NPV. The introduced algorithm is a windows based program developed at Virginia Tech which coded in visual-basic within a spreadsheet environment (Excel). The resulting cut-off windows based program is a user-friendly tool which calculates interactively different mining cutoff grade scenarios. The benefits of the methodology are demonstrated using a hypothetical case study. The authors have observed an improvement of the total NPV using this iterative approach using a year by year optimization factor.

Jan 1, 2007

By C. Orf. Chukabarah

Acoustic pollution (noise) is a significant mine environmental system problem. The U.S. Bureau of Mines (USBM), Environmental Protection Agency (EPA), Department of Labor (DOL) and other researchers have all performed contributory research on noise in mining environments. The present study addressed the problem of unavailability of a computerized, practical, routine, user-friendly, and user-editable, prose-styled application program with which one can determine (a) the noise exposure indices among mine workers, (b) mine system noise exposure level on time-weighted average basis, and (c) predictive relationships among mine workers' age, prior exposure to abnormal noise levels, prior auditory pathologies and the risk/degree of mining-induced hearing impairment. Results showed that such a program ("NEIL") is accomplishable. Additional results revealed that most U.S. mines operate within the statutory noise exposure levels. Furthermore, the mine worker's age was statistically confirmed to be the main predictive risk factor for mining-induced occupational hearing impairment.

Jan 1, 1992

By Brian W. Hester

All gold occurrences in Tanzania are of Precambrian age and in geological settings similar to gold deposits in other parts the world. The three main areas of interest are perhaps the least prospected of areas of gold mineralization in Precambrian rocks in non- aligned, or market economy nations. Historic production exceeds 77.660 kg (2.5 million oz). Current results by small scale workers go unreported, but have been estimated to be as high as 11.000 kg (350.000 oz) annually. Gold occurs in both lower and upper Precambrian rocks. In the older. gold is associated with greenstones and iron formations typical of many cratonic areas of Precambrian age. The Tanzanian Craton lies in the north west quarter of the country where it is flanked on both east and west sides by mobile belts involving upper Precambrian rocks of high metamorphic grade. Gold occurs in fractures in the western belt within two distinct areas.

Jan 1, 1989

By L. W. Laage

Throughout recorded history, underground fires have plagued mining operations. Compared with other hazardous situations in underground mining, a fire can become a global problem by swiftly spreading deadly carbon monoxide and other products of combustion (POC's) throughout the whole mine, often without warning. Experience has shown that when fires are detected and located in their early stages, they are much easier to control and proper escape routes can be more intelligently selected. Recent advances in sensor and data communication technology have made reliable mine fire .detection system installations possible. Unlike building construction. in a mine, it is impractical to install detectors at every desired location. Abandoned workings and unsafe locations preclude sensor installations from both safety and economic standpoints. The net effect is that some fires are detected and located early while the location of others, even if detected early, remains unknown too long for effective evacuation and fire fighting.

Jan 1, 1989

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