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By A. Nieto

A dump edge and vehicle proximity warning system is being developed at the Colorado School of Mines using GPS and wireless local area networks to improve the safety of off-highway trucks in open pit mines. After two years of research, software development, and testing in the laboratory, field tests are currently being carried out at operating limestone quarries and open pit mining operations to evaluate the effectiveness of the system under rugged operating conditions. This paper describes the progress made on this NIOSH-funded project and discuss, tests carried out recently, at the Morenci open pit copper mine in Arizona.

Jan 1, 2002

By D. Shin

The gold leaching using cyanide from ore or waste has been almost universally in use [1]. Recently, biological gold bioleaching using cyanide producing bacteria, e.g. Chromobacterium violaceum, Pseudomonas fluorescens, or P. aeruginosa, has been investigated as environmental friendly and cost effective method. Among them, C. violaceum has been reported as effective cyanide producing bacterium on gold leaching [2, 3]. C. violaceum produces cyanide using glycine as a direct precursor and subsequently detoxify the cyanide by ß-cyanoalanine synthase [4]. However, until today only 0.026 ? 16.9 mg/L of cyanide production in YP medium has been reported in the literatures by C. violaceum [4-6]. Comparing with adding cyanide chemical, biogenic cyanide concentration is lower than the cyanide concentration added in traditional cyanidation. Since cyanide also forms complexes with a number of other elements such as iron, nickel, zinc, silver, copper, and platinum, it is very important for gold recovery to investigate the enhancement of biological cyanide production and set optimal experimental condition. Most of early studies on gold bioleaching by C. violaceum have been performed to investigate gold leaching mechanism using gold powder, and recently various resources such as ores, electronic scrap, and printed circuit boards of waste electronics [7]. Few studies have dealt with gold bioleaching from low-grade ore. In this research the feasibility of gold bioleaching by C. violaceum from low-grade ores containing gold was evaluated and fundamental study was performed for further scale-up study. The aim of this study was to improve the potential of gold bioleaching by C. violaceum from gold-containing ore; in particular, enhancement of biological cyanide production.

Jan 1, 2012

By Adrian Molinari

A radioisotope probe (Minexan 202) capable of simultaneously analyzing a mineral slurry for five elements and pulp density has been developed by Outokumpu Oy, Finland. The probe is designed to operate immersed directly in a process stream, or it can be equipped with a flow cell through which passes a continuous sample of the main stream. A minicomputer (PDPII) is used to control the probes and calculate the assay data. This paper describes the probe as applied to slurry analysis and compares it to the conventional x-ray on-stream analyzer (Courier 300).

Jan 1, 1977

By Roy A. Grancher

Construction materials indeed face a dilemma...as does the building industry as a whole. A stop & go economy; a severe drop; in housing starts; lingering indecision over just what corrective steps are to be taken or to their degree of commitment; no less basic disagreement in regard to which of the, Nation's problems is really the most pressing -- inflation or recession? Optimism has become a rare quality these days. At moat the cautious view is that this new year will see a long, hard struggle back, with hopes that 1976 at least can truly mark a dual anniversary celebration for the United States and its economic health. Yet the paradox is that once recovery does return, those very construction minerals and materials --which in recent years have experienced the ups and downs of overcapacity, shortage, and now declining demand again-- will once more face the spectre of mass inability to service revived and growing needs for its product. Mounting costs, present marginal expansion investment, and substantial lead times required for new facilities to come into production, could well form a bottleneck to economic upswing. The result again can be another cycle of shortage-induced inflation, and with it continued gyrations within the demand supply relationships of the country's building industries.

Jan 1, 1975

By Troy Holm, Matthew L. Fuller, Frederick H. Earnest

Virtual Reality Animation Of The Proposed El Dorado Mine In El Salvador Assists Regulators In Reviewing An EIA

Jan 1, 2005

By Joel Nonnweiler, Rafael Castro, Ross Webb

The three thousand foot long 66-inch diameter Folsom East Interceptor Section2B was completed accident free, on time and under budget with no measurable surface settlement. The tunnel passed through nested cobbles, highly abrasive sands and gravels, and abandoned mine workings with less than five-feet of cover at times. Preventing settlement was critical since the tunnel passed under a heavily traveled state highway. A pilot project to test microtunneling and pipejacking methods in the same ground conditions abandoned both drives before completing the planned drive lengths. This paper discusses performance of the conventional tunneling method selected to excavate the ground and the effectiveness of the ground modification techniques employed.

Jan 1, 2001

By Erika Moonin, Jim Nickerson, Claudio Cimiotti, Roberto Bono

"In response to the severe drought on the Colorado River basin and in order to preserve existing water capacity to the Las Vegas Valley, the Southern Nevada Water Authority contracted a new deep-water intake (Intake No. 3) located in Lake Mead. The current project (Contract No. 070F-01-C1) includes 5 km (3 miles) of tunnel with very difficult geological conditions and a 200- m (650-ft) deep shaft and marine works. This paper will present the current status of the design-build contract being constructed by Vegas Tunnel Constructors and the challenges and problems faced and the innovative solutions developed to handle the difficult conditions encountered during tunneling with up to 15 bars of pressure.ProjectbackgroundThe Las Vegas Valley receives the majority of its water from Lake Mead, which is located approximately 30 km (20 miles) east of the Las Vegas, NV metropolitan area. Due to the severe drought that has hit the southwest region of the United States, the water level in Lake Mead has receded from its high water level of 372 m (1,221 ft) above mean sea level (amsl) to a low of 330 m (1,076 ft) amsl in June 2015. Should the lake level continue to fall, at elevation 320 m (1,050 ft) amsl, the current water intakes will not be able to draw enough water to meet the needs of the local area. The risk of losing water capacity has prompted the construction of a new deeper intake. Not only is the new Intake No. 3 situated at a lower elevation in the lake at 262 m (860 ft) amsl, the new Intake No. 3 is also located to draw better quality (Fig. 1).Project challengesThe project has had several difficult challenges to overcome:• The work consisted of a 1.2 kt (1,300 st) structure constructed on a barge and lowered 100 m (330 ft) into Lake Mead anchored with 9,200 m3 (12,200 cu yd) of tremie concrete.• The drill-and-blast starter tunnel was impacted by three inflow events, resulting in a one-year project delay.• One of the main challenges was selecting the tunnel boring machine (TBM) and excavating the tunnel with expected hydraulic head pressure of as much as 17 bar (16 bar was the highest pressure recorded during the drive), crossing faulted areas, low rock cover and the risk of tunnel instability due to direct connection with the lake.• Extensive pre-excavation grouting with a constant head pressure ranging from 12 bar to 15 bar.• Structural repair of the cutterhead in difficult hydrogeological conditions [water inflow of approx. 800 m3/hr (4,000 gpm)].• Complete repair of the cascade sealing system for the main bearing and two replacements of the pinion bearings.• The TBM approach to the intake structure."

Jan 1, 2015

Draglines are one of the largest land-based equipment moving across the earth. They typically ranging in size from2.5 to 6.5 kt (2,750 to 7,100 st). Their size, though, makes them difficult to maintain. Recently, G&S Engineering Services used an Enerpac synchronous hydraulic lifting system to lift a 3.2-t(3,500-st) dragline at the Curragh Mine in Queensland, Australia’s Bowen Basin.

Jan 1, 2004

Using a series-model of an automotive short range radar sensor (SRR) and a recently completed experimental radar system, field tests have been performed in a surface mine. It was examined, to what extent low-cost electronically scanning radar sensors can provide useful data for assistance systems on large scale mining machines. Simple sensors are useful for anti-collision safety zones or hopper car automation. The more complex and sophisticated experimental radar system using digital beam-forming can clearly detect and map the contours of trenches and slopes. The overall promising results refer to many more potential applications for electronically scanning radar in surface and underground mining as a reliable alternative to mechanical laser scanners.

Jan 1, 2007

By M. R. Shahan, C. E. Seaman, S. E. Mischler, T. W. Beck

"Float coal dust is produced by various mining methods, carried by ventilating air and deposited on the floor, roof, and ribs of mine airways. If deposited float dust is re-entrained during a methane explosion, without sufficient inert rock dust quantities, this float coal dust can propagate an explosion throughout mining entries. Consequently, controlling float coal dust is of critical interest to mining operations. Rock dusting—adding inert material to airway surfaces—is the main control technique currently utilized by the coal mining industry to reduce the float coal dust explosion hazard. To assist the industry in reducing this hazard, NIOSH’s Pittsburgh Mining Research Division (PMRD) initiated a project to investigate methods and technologies to reduce float coal dust in underground coal mines through prevention, capture, and suppression prior to deposition. Field characterization studies were performed to determine quantitatively the sources, types, and amounts of dust produced during various coal mining processes. The operations chosen for study were a continuous miner section, a longwall section, and a coal handling facility. For each of these operations, the primary dust sources were confirmed to be the continuous mining machine, longwall shearer, and conveyor belt transfer points, respectively. Respirable and total airborne float dust samples were collected and analyzed for each operation and the ratio of total airborne float coal dust to respirable dust was calculated. During the continuous mining process, the ratio of total airborne float coal dust to respirable dust ranged from 10.3 to 13.8. The ratios measured on the longwall face were between 18.5 and 21.5. The total airborne float coal dust to respirable dust ratio observed during belt transport ranged between 7.5 and 21.8. INTRODUCTION During the extraction of coal, various dusts are produced that can be classified into two categories of interest: respirable and float coal dust. Respirable dust (diameter 10.0 = µm) has the capability to penetrate beyond the terminal bronchioles and become deeply embedded into the human lungs, leading towards respiratory disease complications (Potts et al., 1990). Float coal dust is defined as coal dust having a diameter less than 74 µm (Harris et al., 2009). During the mining process, float coal dust can be deposited on the floor, roof, and ribs of mine airways. With the proper mixture of methane gas (between 5% and 15%) and an ignition source, a methane gas explosion can occur (Barker and Humphreys, 1996). The resulting explosion can develop a pressure wave which lifts the deposited float coal dust material into the air, propagating a disastrous coal mine explosion (Harris et al., 2010). The current technique to safeguard against the propagation of a coal mine explosion is to treat the mine airways with incombustible rock dust (typically limestone), maintaining an 80% total incombustible content of the deposited material. NIOSH initiated a project to investigate control technologies that could be aimed at reducing the amount of float coal dust allowed to deposit in the mine airways using three approaches: prevention, capture, and suppression prior to deposition. Reducing the float coal dust being generated during the mining processes and capturing or suppressing airborne float coal dust prior to deposition would in turn increase the efficiency of the applied rock dust used to prevent mine explosions."

Jan 1, 2017

By Joel Darmstadter

The position of the coal industry in America’s fuel and power picture remains one of prime importance. Measured in Btu terms, the industry is the country’s leading energy producer and an important exporter. Foreign coal sales yield annual proceeds of about $4 billion. Coal’s one-fifth share of the nation’s energy consumption is nearly as high as that of natural gas. Coal is the electric utility sector’s principal fuel supplier. It accounts for about55% of the electricity generated at power stations.

Jan 1, 1999

By Frederick Bradley Henderson

This study was initiated to investigate the occurrence of cinnabar in the oxidation zones of some mercury sulfide deposits. Seven mines or mine districts were visited and samples were taken from both the oxidation and primary zones of these deposits in order to compare their mineralogies and assess Vie chemical changes that took place during oxidation. As a result of the study of these specimens, several limiting factors are suggested for the chemical environments and processes active in both the deposition and oxidation of mercury sulfide deposits. The Mt. Jackson mine, near Guerneville, California (location map, fig. 1), was studied in some detail and forms the basis of this paper. The mine has not heretofore been described in detail in the literature. The Mt. Jackson mine is considered typical of mercury sulfide deposits occurring at the faulted boundaries of serpentinite bodies and enclosing sediments. Such mines are common in the California and Oregon Coast Ranges? Specimens collected by the author from the New Idria and New Almaden districts, the Mt. Diablo, the Culver Bear, and the Buena Vista mines in California, and the Opalite district (Cordero and Bretz, mines) on the Oregon-Nevada border were studied for comparison with the Mt. Jackson samples. The mine description, maps and sketches were composed from field maps kindly provided by Francis Fredericks, consulting geologist to the Sonoma Quick-silver Mine Inc. during the author's visit in 1962. Additional information was obtained from the company maps and minor corrections and interpretations were added by the author.

Jan 1, 1965

By A. C. Smith

Although only used in a few U.S. longwall mines, bleeder-less ventilation systems can be an effective spontaneous combustion control method in mines having a demonstrated history of spontaneous combustion. To provide insights for the optimization of bleederless ventilation systems for U.S. underground coal mines, a computational fluid dynamics (CFD) study was conducted to model the spontaneous heating in longwall gob areas using a bleederless ventilation system. A single longwall panel with a bleederless ventilation system was simulated, and typical longwall mine ventilation data were used in the simulations. The permeability and porosity profiles for the longwall gob were estimated using a geotechnical model and were used as inputs for the CFD modeling. The effects of gob permeability and resistance of the collapsed entries on the spontaneous heating were studied. The effectiveness of using nitrogen injection to prevent spontaneous heating in the gob was also examined.1

Jan 1, 2008

By P. Koh

A novel approach incorporating computational fluid dynamics (CFD) and flotation modelling has been used for investigating flotation cell designs. CFD modelling has increasingly been employed to enhance understanding of the cell hydrodynamics in mineral and coal flotation. Opportunities for improving the flotation cell performance can be identify by modelling. The CFD-flotation model from CSIRO incorporates cell hydrodynamics that affect particle-bubble interactions. Information from the model includes velocities, turbulent dissipation rates, gas hold-up, particle-bubble attachment and detachment rates. The attachment and detachment rates have been found to be effective measures of cell performance for cell design.

Jan 1, 2011

By M. S. Safarzadeh

Over the last fifty years, the treatment of enargite concentrates has not received much attention primarily because of the availability of other clean concentrates suitable for processing with existing smelting and/or leaching technologies. As traditional copper ores have become scarcer, copper-arsenic ore deposits have garnered more interest. Arsenic release is a significant concern during the treatment of enargite by pyro or hydrometallurgical methods. Enargite is also very refractive in standard leaching procedures. Thus, economical treatment options for enargite concentrates are needed. Preliminary experiments have shown that the acid-bake leach process could be adapted and used for the treatment of enargite concentrates. In this study, low-temperature (100-400 ºC) sulfuric acid baking of an enargite concentrate followed by water-leaching has been evaluated. The results indicate the thermal transformation of enargite to copper sulfate during sulfuric acid baking, with most of the arsenic being released from the concentrate into the gas phase for baking at 400 ºC. The condition for maximum copper extraction (~100%) from the concentrate was found to be 400 ºC, sulfuric acid amount of 0.5 mL/g of concentrate, and 2 h baking time. Part of the arsenic was captured in the form of arsenopyrite (FeAsS). XRD analysis proved the presence of some arsenic in the form of claudetite (As2O3) in the baked concentrate. Acid baking of pure enargite behaved in similar fashion.

Jan 1, 2012

By J. L. Cupp, R. C. Ford, B. R. Romig

The Climax Molybdenum Mine, located near Leadville, Colorado, is the site of a lengthy mining history spanning more than 80 years. In the 1960’s, extraction of molybdenum from oxide ore located adjacent to the massive molybdenite sulfide deposit resulted in the construction of an earthen core dam to impound fine-grained oxide tailing in the Eagle River Valley. Through recognized value of water storage and reclamation opportunities, a tailing removal project was initiated in 1993 to convert the impoundment facilities to a post-mining beneficial land use of developed water resources. An evaluation of the effect residual materials and lake dynamics would have on in-stream water quality was performed. Eagle Park Reservoir stands as a model for future reclamation efforts that involve water delivery to highly sensitive receiving waters. This paper provides a case study on project development, the evolution of water quality assessment, and the regulatory framework that contributed to this project’s success.

Jan 1, 1999

By K. A. Lapakko, D. A. Antonson

Fourteen samples of pyrite-bearing Archean greenstone rock (d < 6.35 mm, 0.04% < St < 1.22%) were characterized (particle size, chemistry, mineralogy) and subjected to laboratory dissolution testing. The only sulfide and carbonate minerals identified were pyrite and siderite, respectively. Quartz, chlorite and sericite typically comprised 90 to 98 percent of the mineral content. For the first 60 weeks, seven samples with sulfur contents less than or equal to 0.16% produced drainage pH values exceeding 6.0. Over this period, six of the seven samples with sulfur contents greater than or equal to 0.20% produced drainage pH below 6.0, with minimum values ranging from 3.2 to 4.7. The seventh sample (0.72% S) had a siderite content of 18%. Small amounts of magnesium and, to a lesser degree, calcium carbonates present in the siderite apparently dissolved to neutralize acid and maintain drainage pH above 6.0. Sulfate release rates generally increased as sulfur content increased, and the rates of pyrite oxidation estimated for individual samples were roughly half to five times that reported in the literature for the abiotic oxidation of pyrite by oxygen. Observed neutralization potentials ranged from 0.2 to 2.0 g CaCO3/g rock.

Jan 1, 2002

Gary R. Steele is vice president, corporate marketing with Energy Fuels Resources. As such, he knows the global uranium market. The following are some of his thoughts on uranium?s place in the global energy picture. ME: What are Energy Fuels Resources? thoughts on the global nuclear power industry? Steele: The global nuclear power industry is a major contributor to the electrical needs of the world. Though generation by nuclear reactors has primarily attracted attention through the reactor accidents at Three Mile Island and Chernobyl, nuclear power continues to quietly and safely provide power to a growing and power-hungry world population. As of March 2008, 30 countries were operating 439 nuclear power reactors. Nuclear power plants provided about 15 percent of the world?s electricity production in 2007. France leads the world in nuclear utilization, with 77 percent of its power coming from nuclear plants. And Lithuania, Slovakia and Belgium each derive more than 50 percent of their power needs from nuclear plants. For much of the developed world, nuclear generation has already been contributing significantly to the supply of electricity. Additionally, 34 new nuclear plants are under construction in 14 countries. Leading the rush to build new nuclear generating plants are China, Russia and India. Each of these countries is building six new nuclear power plants. These 18 plants, totaling almost 12,000 MW of generation capacity, will require about 7.25 kt (16 million lbs) of U3O8 for their initial fuel load and will consume about 2.45 kt/a (5.4 million lbs/year) for the rest of their operating lives. The rest of the world, outside of the United States, has used nuclear power as a viable and economic generation alternative since the commercialization of utility nuclear reactors. And current activity supports the strong future of the nuclear alternative internationally.

Jan 1, 2008

By Peter Kowalczyk

Magnetic surveying and map production is well established in land based mineral exploration. Magnetic data are routinely used to map geology in covered terrains, to estimate the depth to basement in overburden covered areas, and to identify altered zones, mineralization, bedding attitudes, and fault networks both regionally in map view, and through interpretation to depth in 3D. Best practices for magnetic survey methods and magnetic interpretation exist in all areas of land based geophysical survey methodology - mineral exploration, hydrocarbon exploration, geological mapping, archeological mapping, and in military applications. At sea, and particularly under the sea, sophisticated magnetic surveys are being done, but it can be argued that these are primarily in niche applications, for example in naval mine-hunting and UXO applications. Magnetic data is not normally collected on AUVs and ROVs conducting mapping and hydrographic survey operations. OFG has developed physical and mathematical calibration routines so that magnetometers can be mounted directly onto AUV and ROV bodies where significant heading errors and magnetic gradients exist. This simplifies the routine deployment of magnetometers on AUVs and ROVs for mineral exploration and other magnetic survey applications without the need for towed bodies, ungainly mounting frames, or degaussing of the survey equipment. Our experience shows that magnetometers can be operated routinely on AUVs and ROVs and that with careful processing useful maps can be produced routinely at low cost.

Sep 1, 2014

By Tim O’Neil

Upbeat, surprisingly so, might describe the mood at the2002 SME Annual Meeting and Exhibit in Phoenix, AZ. More than 4,000 mineral professionals gathered for three days of education, networking and product perusal. The Annual Meeting featured the theme, “Minerals for the Future@ SME” at the Feb. 25-27 gathering. Meeting attendance reached 4,039along with 479 exhibit booths show-casing 325 companies. Exhibitors found a good mix of industry types:37% from mining, 19% from processing, 20% from manufacturing and 28% from environment, education and government.

Jan 1, 2002