Search Documents

By J. G. Craig

This paper initially was to be on the design, construction and operation of the Lucky Friday mill. However, this subject has been pretty well covered in some of the mining publications in the past few years - specifically Mining Congress Journal for April, 1961 and Mining World for March, 1962- : In order to avoid too much repetition, we decided to present in this paper a comparison of the Lucky Friday mill constructed in 1959, and the Mayflower mill built by us in 1962. During the past three years Hecla Mining Company has constructed two relatively small mills: The Lucky Friday mill at Mullan, Idaho 750 T/day; and the Mayflower mill at Heber, Utah - 450 T/day. These mills were engineered, designed and constructed by Hecla, using principally our own personnel, with very little outside (contractor) labor employed. This paper presents a comparison of some of the interesting features of these mills, and where differences occur, it discusses the reasons for the various differences. It compares such points as the testing program, physical layout of the plant, construction costs, the grinding section, the flotation section, tailings disposal, metallurgy, recovery, grades, operating costs, etc. To help illustrate, and to compare these features, we will project pairs of slides showing each of the two mills. First a little background and history on the properties ---

Jan 1, 1964

By Thos. B. Douglas

In 1907, the Oklahoma Portland. Cement Company built a small dry process plant at Ada, Oklahoma, then Indian Territory. This plant was later acquired by the Ideal Cement Company of Denver, Colorado, who in 1918 built a new wet process plant along side the old dry plant. The older plant was later shut down .and eventually razed. In 1955, the Ideal Cement Company decided to increase the production at its Ada, Oklahoma operations. After many studies it was decided to build a complete new plant along side the old, near the site of the original 1907 plant. .The new plant was to have a. production of three million barrels annually while the plant then in. operation had an annual production of two and one quarter million barrels

Jan 1, 1961

By Barry D. Simmons

The Millenbach copper-zinc orebody is an ideal Canadian example of a stratabound base metal deposit in volcanic rocks. The mine, operated by Lake Dufault Divison, Falconbridge Copper Ltd. is located five miles north of the city of Noranda in northwestern Quebec. The deposit occurs within an Archean volcanic sequence which forms part of regional acidic volcanic center within the Abitibi greenstone belt. Preproduction ore reserves totalled 2,075,000 tons grading 3.5% copper, 3.6% zinc, 1.1 ounces per ton silver, and 0.02 ounces per ton gold. Stratabound lenses of massive sulphides together with underlying stringer sulphides are closely associated with a dome of quartz-feldspar porphyritic rhyolite approximately 3000 feet below surface. The paper describes the presently known geology of the deposit and includes documentation of sulphide mineralogy and textures as well as sulphide/ host rock relationships. The stratigraphy, petrography and chemistry of the volcanic host rocks are described with emphasis on the alteration intimately associated with the sulphide bodies. Although the volcanic stratigraphy is complex within the mine area, the presence of only low-grade metamorphism and the relative lack of structural deformation allow detailed interpretation of geological history. Presently recognized evidence strongly suggests that the sulphides were deposited at and near sea-floor, by hydrothermal solutions. The dome of porphyritic rhyolite appears to have been the most significant factor controlling sulphide localization.

Jan 1, 1975

By Richard M. Chamberlin

Perlite is an altered rhyolitic glass with 2 to 5 wt % water that expands or "pops" when heated quickly to plasticity while evolving steam to form lightweight, glass foam. Commercial perlite deposits in New Mexico are well-developed zones of chemical weathering (hydration) superimposed on highly permeable and thick glassy zones at the chilled upper surface and toes of high-silica-rhyolite lava flows and lava domes. The maximum tonnage of glass in these volcanoes was predetermined by their unique eruptive histories. New Mexico perlite production (80% of US production of 571,00 st) is mostly from the 3.9 Ma high-silica-rhyolite lava flows at the No Agua Peaks volcanic center. The primary vent at No Agua is defined by a 900 ft-high rubidium-rich composite lava dome, known as West Peak, that contains minor perlite reserves. Slightly less rubidium-rich lava squeezed out from under the west flank of the dome to form relatively thin (250 ft) but highly vesicular lobate flows that now consist of about 50 % recoverable perlite. Finally, rubidium-poor lavas were extruded from a radial dike on the northeast flank of the dome. These thicker (400 ft) flow lobes contain about 20 % recoverable perlite. The largest mass of lava does not always contain the most perlite. The thinner (west) flow at No Agua yields the largest perlite reserves rather than the large composite lava dome or thicker (east) flow.

Jan 1, 1994

By Greg Watson, Dennis Ofiara

"TBMs have been used in mining in decades past, but their use has been limited and sporadic, due to both perceived and actual application difficulties. With new technology and mounting success stories, this is changing. For both coal and metals mining, deep ore bodies require long access tunnels, and an efficient and economical method of reaching those deposits. Today, mining engineers are considering TBMs as part of the overall mine development plan. Planned TBM mine drifts are not only longer, but have more complicated trajectories. Mine development TBMs will have to cope with varying geology, potential for high water inflows, steep gradients, and high temperatures. TBM systems are being planned to cope with such difficulties. TBM systems will be considered and increasingly deployed for mine development, even if commodity prices remain low. TBMs can satisfy the need for increased productivity, better life of mine infrastructure, and safety. Effective conveyor systems are essential to support TBM operation in many mining applications. Many mine development tunnels are slopes, driven down at the steepest practical gradient to reach the deep ore body. Conveyors are often the only safe and effective way to haul the TBM muck form such tunnels. This paper will review the historical use of TBMs in mining, and will discuss the 2015 status of TBMs and conveyor systems in mining, and the special requirements and adaptable features needed in order to make efficient TBMs a reality in mines worldwide.HISTORICAL USE OF TBMS IN MINING APPLICATIONS The first successful hard rock TBM was invented in 1954. Over the next decades, TBMs have been used in many mining applications: Mine access drifts in several Spanish mines •,White Pine Copper Mine, USA •,Selby Coal mine drift, UK •,Coal slopes in Appalachia, USA •,German coal mines accdess drifts, several mines •,Magma Copper San Manuel, USA •,Cape Bretton Undersea Coal Slopes, Canada •,Stillwater Mines, USA"

Jan 1, 2016

By Chee S. Theng

As the 2018 president of the Society for Mining, Metallurgy & Exploration Inc., I am pleased to present the 2018 issue of the Transactions of the Society for Mining, Metallurgy & Exploration Inc., Vol. 344. A significant portion of the contribution that we make as a professional society is the publication of professional and technical papers that accelerate the advancement of scientific knowledge and enable the transfer of technology. Communication within the mining community is the key to a successful society. This technology exchange continues a tradition that dates back to the 1871 meeting of 22 mining engineers in Wilkes-Barre, PA, that resulted in the founding of the American Institute of Mining, Metallurgical and Petroleum Engineers (AIME). Those individuals envisioned that these transaction volumes “would form a most valuable and greatly needed addition to our professional literature.” This volume fulfills that pledge. The 2018 Transactions consists of a total of 59 technical papers, encompassing all 25 papers published in 2018 in the Technical Papers Section of Mining Engineering (Vol. 70) and all 26 papers published in 2018 in Minerals & Metallurgical Processing (Vol. 35). Additionally, this volume contains 8 papers that are being published for the first time in this issue. The papers presented in this volume were written by some of the most distinguished professionals in the industry worldwide. All of the technical papers were peer-reviewed. The process of review and publication requires much hard work by authors, reviewers and our Publications staff. As the 2018 president of SME and on behalf of all our members, I would like to extend our gratitude to all whose volunteer efforts contributed to the publication of this volume. The new year brings an exciting change. The publication of Transactions will cease with this volume. Instead, our Minerals & Metallurgical Processing journal has the new name of Mining, Metallurgy & Exploration (MME), and Transactions as well as the Technical Papers Section of Mining Engineering are incorporated into MME. The journal is published in partnership with Springer Nature, and all SME members have free electronic access to the journal.

Jan 1, 2018

By J. K. Horbaczewski

The reclamation of an open dragline pit (Pond A3P-2) at the Gibbons Creek lignite mine in east-central Texas required neutralization of acid mine pit water. At the start of treatment with hydrated lime (Ca(OH)2) on March 28, 2000, the pond had partially filled with 913,000 m3 (740 acre ft) of pH 4.9 water. Another 666,600 m3 (540 acre ft) of pH 3.3 water was pumped in from an adjacent pit (PitA3P- 1). By the end of the project (July 5, 2000), a combined volume of 1,579,000m3(1,280ac-ft or 417milliongal) in PondA3P-2 had been successfully treated to pH 8.2 with 431 t (475 st) of lime. This was two to three times more neutralizer than laboratory trials and detailed chemical titration had predicted. The main reasons for the difference are thought to be the inadequate representation in a laboratory setting of some of the chemical reactions that occurred in the field, including incomplete mixing of reactants, reactions with clay minerals in the pit walls, the kinetics of biologically-mediated reactions and the kinetics of aluminum oxyhydroxide polymerization (aging).

Jan 1, 2002

By Paavo Eerola

In May of 1984, it was decided that Outokumpu Oy would design and build a new nickel flotation mill to process ore from the newly discovered Enonkoski mine in eastern Finland. Since there hart peen a number of successful process charges in the existing mills, the design effort included the study and incorporation of several new developments, including all-autogenous grinding, "flash flotation", lane cell roughing, large cell cleaning and a computer-based, profit optimizing, process control system. The paper discusses the background and results of those studies, and a description of the resulting mill which will begin production in 1986.

Jan 1, 1985

By Roy A. Grancher

HAPPY BIRTHDAY Not only is 1971 the Centennial Year of the AIME, but it also marks the One Hundredth Anniversary of the United States Portland Cement Industry. On September 26th in 1871 David O. Saylor of Allentown, Pennsylvania, received his patent Numbered 119,413 for the manufacture of portland cement. "Cement" had been used in the United States before that. This was, however, natural cement - a direct product of rocks as found in nature, usually burned at low temperatures in open kilns. During the early 1800s this natural cement played an important role in such projects as the building of the Erie Canal. It was only after the Civil War that small amounts of high priced portland cement was imported from Europe. The successful use of this material in construction led to Saylor's experiments and subsequent patent for the manufacture of a scientifically controlled product in this country. These one hundred years have witnessed four major "ages" of cement . . . three of them occurring in the last quarter century since World War Two. The first age was the "Age of Development", a seventy-year period which saw the growth of cement and its concrete end uses as major construction materials. Next followed a period called the "Age of Demand" when, after the war, cement became in short supply relative to large building requirements. In effect a cement shortage existed. The decade of the Sixties proved to be the "Age of Reaction", with its courses of action coming in response to the problems that arose when the industry's expansion programs provided too much capacity. Today cement, and the concrete industries, find themselves entering the "Age of Reason". Overcapacity, low price, rising costs, and poor returns are several of the reasons behind that name, As these industries face the construction challenge of the Seventies, and beyond, the application of basic management principles (otherwise known

Jan 1, 1971

By A. F. Agnew

Discussion by A.E Agnew Strachan's paper summarizes a wealth of data on water-storage dam "incidents" published by USCOLD and ASCE in 1988, together with a review of tailings-dam incidents published by USCOLD in 1994. The data is summarized by text and 11 histograms. The histograms present a useful compilation of these data, although the patterns within the histogram blocks did not survive the Mining Engineering printing process - so their usefulness is impaired. Unfortunately, the text discussion is too cursory and does not highlight the significant relationships among the various causes of the incidents. Four paragraphs of text and Fig. 1 were devoted to water-storage dams, but the discussion is too sketchy, and Fig. 1 is unclear. Important statistics that could be uncovered are: •the total number of dam incidents tabulated were 500+, •earth embankments constituted 73% of those in operation and •incidents related to earth embankments were 75%, of which dam failures accounted for 24%, major repairs accounted for 42% and accidents accounted for 34%. Strachan concluded that "the majority of the dam failures are associated with overtopping (p. 49), and that the majority of incidents are associated with spillway and other facility structures" - although this is difficult to discern from Fig. 1. Confusion regarding Strachan's use of the terms "dam failures" and "incidents" is compounded by his use of "failures" and "accidents" in one paragraph of his Introduction section followed by his use of "incidents" in the next paragraph. Getting to the meat of Strachan's important paper, the tailings-dam incident survey (USCOLD, 1994), the connection between Figs 2 through 11 seems obscure. First, in the four paragraphs of introductory material, one learns that "incidents consisted of failures, accidents, seepage and other incidents of performance that did not meet design criteria" (p. 50). One does learn the helpful caveat that "structures not related to mill tailings were not included in the review" - so that the Buffalo Creek (West Virginia in 1972) and Aberfan (Wales in 1966) coal-mine failures, together with the ongoing metal-mine remediation work at Summitville (Colorado) do not muddy the waters of his paper. The all-too-brief discussion of the data shown in Figs. 3 through 11 (185 dams in USCOLD plus 26 dams in UNEP) reveals the following: •Figure 3: 57% of the incidents (failures and accidents) occurred with dams less than 20-m (66-ft) in height. •Figure 4: 63% of the incidents were due to failures alone (subset of Fig. 3). •Figure 5: Active dams had 82% of the accidents and 93% of the failures. •Figure 6: Types of dams (upstream, water-retention, downstream, centerline and "unknown") separated according to incidents. •Figure 7: Breaks out the incidents in Fig. 6 by failures, accidents and ground water. •Figure 8: Breaks out incidents by type (overtopping, slope stability, earthquake, foundation, seepage, structural, erosion, mine subsidence and "unknown"). •Figure 9: Separates Fig. 8 data into active and inactive dams. •Figure 10: Separates Fig. 9 data into failures and accidents. •Figure 11: Same as Fig. 8, but broken out by tailings-dam type (Fig. 6). Figures 6 and 7 show that most of the failures are associated with upstream or "unknown" types. Figure 9 shows that the leading causes of incidents for active dams

Jan 1, 2003

By Karin Bäppler

Lyon with half a million inhabitants is the third largest city in France. Urban agglomerations such as Greater Lyon demand intelligent underground solutions for the freedom of mobility of its inhabitants. The city and metropolitan area of Lyon provide an example of a city strategy adapted to the changing needs due to demographic and living standard trends. The Lyon Metro Line B with a length of 2.4 km is one of the strategic projects with regard to city planning and future mobility. The paper will highlight on this special area of application in singular diverse geology with sophisticated mechanized tunnelling technology.

Jun 13, 2021

By B. T. Lusk, J. J. Silva Castro

Currently, there are several methodologies to assess ground vibrations from blasting. Of all available methodologies, one that is becoming more important is the waveform superposition or signature hole technique. This technique is based on a signature waveform assigned to each hole to build the complete waveform for the whole production blast, using the convolution between the time initiation sequence and the signature hole waveform. In the basic methodology of the signature hole technique, the waveform hole-to-hole is assumed to be the same. Several studies and field tests have proven that the waveform hole-to-hole, even in ideal rock mass conditions (rock mass with little or no joint system), changes. In addition to distance or confinement, other factors that could change the waveform hole-to-hole include different geologic paths from the source to the monitoring point and a different energy output of each hole, due to hole loading, explosive composition and/or contamination, priming, etc. These factors result in varying waveforms generated for each hole, making the waveform produced by each hole a somewhat random process. There is available in the literature some proposals to include variability in the waveform hole-to-hole, but the parameters involved are complex and difficult to estimate. In this paper, the variability in the signature waveform hole-to-hole in a blast event was recorded through a field test, and a proposal to include signature waveform variability to develop an equation based on the Fourier series is presented. This methodology is the basis for a future signature hole analysis using a Monte Carlo scheme, taking into account the variation of the amplitude and the frequency content of the waveform hole-to-hole in a production blast event.

Jan 1, 2012

By Blair K. Salisbury

Dissolution within Permian evaporites of the Delaware basin has created extreme lateral geologic and physical property inhomogeneity within and above the evaporites. Discriminating a sulfur deposit's geophysical signature from other variances is difficult. This is particularly true of porosity-dependent gravity and electrical methods. However, other techniques that detect alteration of strata above sulfur deposits may be applicable individually or in combination with other types of data. Relationships between sulfur deposits and gravity, magnetic, gamma radiation, spontaneous potential, and soil geochemical measurements are illustrated by data from several Delaware basin geophysical and geochemical surveys.

Jan 1, 1992

By Nik Sokol, Eric Sekulski, Leo Weiman-Benitez, Jon Hurt, Shrinidhi Vijayakumar, Phaidra Campbell

The Silicon Valley Clean Water (SVCW) Gravity Pipeline (GP) is the first Progressive Design Build (PDB) tunnel completed in North America. As part of the Regional Environmental Sewer Conveyance Upgrade (RESCU) Program, the tunnel is a key component to replacing and rehabilitating components of the existing conveyance system in San Mateo County, California. The GP consists of a large diameter Fiberglass Reinforced Polymer Mortar (FRPM) pipe installed inside a 4.1 m (13.5 ft) inside diameter, 5.3 km (3.3 mile) long precast concrete segmentally lined tunnel. The tunnel was constructed using a 4.6 m (15.2 ft) diameter Earth Pressure Balance (EPB) Tunnel Boring Machine (TBM) through heterogenous silts, clays and sands. Construction included two separate TBMlaunches from a centrally located access shaft, and a tunnel alignment below but in close proximity to very soft Young Bay Mud. Settlement criteria and mitigation strategies focused on protection of an existing 1.42 m (56 inch) diameter force main and adjoining structures along the alignment. This paper discusses the results of the theoretical settlement analysis versus the actual observed ground movements, while also presenting mitigation measures and adjustments made during tunneling to reduce the risks of adverse settlement.

Jun 13, 2023

By C. Vasilescu

Phytotechnologies use plants to remediate various media impacted with different types of contaminants. These technologies can be implemented either in situ or ex situ. The affected media in which phytotechnologies can be applied include soil, sediments, groundwater and surface water. They are best applied at sites with shallow contamination of organic, nutrient, or metal pollutants that are amenable to one of five treatment options: phytoextraction, phytotrans-formation, rhizosphere, bioremediation, phyto-stabilization or rhizofiltration. Phytoremediation can be used along or, in some cases, in place of mechanical cleanup methods. Phytoremediation can be used to clean up metals, pesticides, solvents, explosives, crude oil, polycyclic aromatic hydrocarbons and landfill leachates.

Jan 1, 2006

By Egons R. Podnieks, Wallace W. Roepke

Mining technology to utilize vital lunar resources will be required for any commitment to permanent lunar basing. Lunar mining must be viewed both as a major supporting element for space resource commercialization and for creation of human settlements on lunar and planetary surfaces to support long-range space exploration. The Apollo missions to the lunar surface and results from fundamental research on analogue lunar rocks by the Bureau of Mines, and others, have provided the initial data for developing lunar mining technology. The multi-disciplinary research projected in this paper outlines the scientific and engineering needs to realize the lunar mining goals.

Jan 1, 1990

By M. J. Ross, D. A. Norrgran, J. A. Wernham, J. N. Orlich

INTRODUCTION Laboratory testing for magnetic concentration circuit design is a requirement, just as it is for most other types of concentration. Natural variations in raw materials allow on1 y the broadest of generalities to be made regarding magnetic separation. Further, magnetic fields are geometry dependent, leaving fundamental models of a separator overly dependent upon the exact conditions for which the models were derived. Despite this, an understanding of the basics of magnetic separation and of the problem to be attacked can result in rapid progress towards the final circuit design with a relatively simple testing program. Magnetic Separation Basic Principles A magnetic field can readily be understood in terms of lines of flux. A familiar demonstration of these lines of flux is the pattern of iron filings on a sheet of paper when a magnet is placed underneath. Lines of flux2 are measured in Gauss (1 line/cm2) or Tesla (10000 gauss). Regions of high field strength have a greater number of lines. Field direction is indicated by a convergence of lines. When a particle is placed in a magnetic field it cuts the lines of flux and alters them in one of three basic patterns. These patterns are referred to as diamagnetic, paramagnetic and ferromagnetic. Diamagnetic materials have electronic structures which react to oppose an applied magnetic field. This opposition acts to locally reduce the applied field slightly. The visualization is that lines of flux diverge and go around the particle. Because of this divergence or opposition, a diamagnetic particle will tend to move towards regions of lower flux density. That is to say that the particle will be repelled by a magnetic field. Aluminum oxide and napthalene are examples of diamagnetic materials. Paramagnetic materials have an electronic structure which increases an applied magnetic field. Although these materials also exhibit diamagnetism, they have randomly oriented impaired electrons which align with the magnetic field. The resultant local field enhancement is significantly larger than the diamagnetic opposition. The visual-

Jan 1, 1986

Refractory gold concentrates often contain submicroscopic gold that is encapsulated within the crystal matrix of iron sulfide minerals, such as pyrite, pyrrhotite and arsenopyrite. To recover the gold, the host mineral must generally be broken down chemically by oxidative processes, such as roasting, pressure oxidation or bacterial leaching, which expose the gold for subsequent recovery by leaching in cyanide solution. The focus of attention in these pretreatment processes is usually the oxidation of the sulfides to elemental sulfur, sulfur dioxide gas or sulfate ions. Less attention is paid to the deportment of iron and the changes in its oxidation state, although this can have a profound effect on gold and silver liberation, as well as downstream operating costs. Iron sulfide minerals break down completely during pressure oxidation, and dissolve in the sulfuric acid solution that is gener-ated from oxidation of the sulfides. This dissolution liberates the tiny gold particles that were originally trapped in the sulfide crystals, and gold recovery during subsequent cyanidation is usually very high (>95%). Iron goes into solution in the oxidation process, initially as ferrous sulfate, but this compound is rapidly oxidized to ferric sulfate, which then hydrolyzes and reprecipitates. The form of the precipitate varies depending on the operating conditions in the autoclave and the presence of certain metal cations. When the acidity in the autoclave is quite low (<20 g/L H2SO4) and the temperature is high (>200°C), the formation of hematite is favored. When the acidity is high (>20 g/L H2SO4) and the temperature is relatively low (160 to 200°C), the formation of basic iron sulfate is favored. If the ore or the leach solution contains significant levels of certain cations (such as Na+, K+, NH4+, Ag+ or Pb2+) and the acidity is high (>20 g/L H2SO4), jarosite compounds are favored. Hematite is the desired iron product in the autoclave discharge, for both metallurgical and environmental reasons, but it is difficult to operate an autoclave under the conditions required for effective liberation of gold without converting some of the iron to basic iron sulfate and/or jarosite. These compounds fall into a category of iron compounds known generically as iron hydroxy sulfates, all of which can cause significant processing and environmental problems in the downstream gold process. This paper deals specifically with basic iron sulfate: the conditions under which it is formed in an autoclave, the problems that are caused by its presence in the feed to a cyanidation plant and possible remedial strategies that can be adopted, both in the autoclave and downstream.

Jan 1, 2010

Refractory gold concentrates often contain sub-microscopic gold that is encapsulated within the crystal matrix of iron sulphide minerals such as pyrite, pyrrhotite and arsenopyrite. To recover the gold, the host mineral must generally be broken down chemically, by oxidative processes such as roasting, pressure oxidation or bacterial leaching, which expose the gold for subsequent recovery by leaching in cyanide solution. The focus of attention in these pre-treatment processes is usually the oxidation of the sulphides to elemental sulphur, sulphur dioxide gas or sulphate ions. Less attention is paid to the deportment of iron and the changes in its oxidation state, although this can have a profound effect on gold and silver liberation, as well as down stream operating costs. Iron sulphide minerals break down completely during pressure oxidation, and dissolve in the sulphuric acid solution that is generated from oxidation of the sulphides. This liberates the tiny gold particles that were originally trapped in the sulphide crystals, and gold recovery during subsequent cyanidation is usually very high (>95%). Iron goes into solution in the oxidation process, initially as ferrous sulphate, but this is rapidly oxidized to ferric sulphate, which then hydrolyzes and re-precipitates. The form of the precipitate varies depending on the operating conditions in the autoclave and the presence of certain metal cations. When the acidity in the autoclave is quite low (<20 g/L H2SO4) and the temperature is high (>200OC) the formation of hematite is favoured. When the acidity is high (>20 g/L H2SO4) and the temperature is relatively low (160 to 200OC), the formation of basic iron sulphate is favoured. If the ore or the leach solution contain significant levels of certain cations (such as Na+, K+, NH4+, Ag+ or Pb2+) and the acidity is high (>20 g/L H2SO4), jarosite compounds are favoured. Hematite is the desired iron product in the autoclave discharge, for both metallurgical and environmental reasons, but it is difficult to operate an autoclave under the conditions required for effective liberation of gold without converting some of the iron to basic iron sulphate and/or jarosite. These compounds fall into a category of iron compounds known generically as iron hydroxy sulphates, all of which can cause significant processing and environmental problems in the downstream gold process. This paper deals specifically with basic iron sulphate; the conditions under which it is formed in an autoclave, the problems that are caused by its presence in the feed to a cyanidation plant, and possible remedial strategies that can be adopted, both in the autoclave and downstream.

Jan 1, 2010

By James J. Gusek

The Atlantic City iron mine is located in Fremont County in central Wyoming, near the historic gold mining camps of Atlantic City and South Pass City. The mine lies on the southeast flank of the Wind River Mountains at an elevation of about 2,470 m (8,100 ft) above sea level (Fig. 1). An 81-h M2 (200-acre) tailings impoundment at the Atlantic City taconite operation has been a source of blowing dust. The site qualified for reclamation under Wyoming&apos;s Abandoned Mine Land (AML) reclamation program. The ultimate reclamation construction incorporated commercially available organic amendments and fertilizers into a 300-mm- (12-in.-) thick cap of a sterile clay loam cover material. The water level was lowered in an adjacent flooded mine pit that was feeding uncontrolled seeps into the tailings basin. A wide tailings pond spillway was built that allows flood control while minimizing seasonal water-level fluctuations in the pond. Rock berms and rock snow fences were built for wind-erosion control and soil-moisture preservation. Future work includes tree planting in the protective wind/ snow shadows of rock berms and rock snow fences and plugging a decant pipe. US Steel opened the Atlantic City iron mine in August 1962. It closed in 1983. Taconite iron ore was mined by surface methods. The ore was magnetically separated from the waste. The magnetic concentrate was mixed with bentonite, formed into pellets and roasted to produce a blast furnace feed stock for US Steel&apos;s blast furnaces in Geneva, UT. The pellets were hauled by rail to the Geneva Iron Works. The Atlantic City Mine produced three types of wastes. These included waste rock overburden from mining, a coarse-grained (sand to small-gravel sized), nonmagnetic reject rock termed "cobbs" and fine-grained tailings ranging from 600 to 75 µm (28 to <200 mesh). The waste rock has been used as an aggregate/rip rap source by a local contractor and the Wyoming Department of Transportation (WYDOT). WYDOT also

Jan 1, 1998