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By T. Tomioka

1. An Overall View of the Japanese Ferroalloys Industry 1) Depressed Demand for Ferroalloys: In Japan consumption of ferroalloys in the last ten years has decreased, although there has been some fluctuation from year to year. During this term production figures of the steel industry, which are closely related to consumption of ferroalloys, are as follows: Shipment of steel products for the domestic market has declined gradually from 69 million tons in 1979, which was the peak year for steel production, to 60.3 million tons in 1982 and 60.4 million tons in 1983, the level of 1978. In addition, exports also have been a downward trend since 1976, which was the peak year with tonnage of 34 million tons, to 28 million tons in 1982 and 31 million tons in 1983.

Jan 1, 1984

By Jai Ghosh, Aprad E. Torma, Roger Guay

The catalytic effect of ferrous ion in the industrial biohydrometallurgical heap and dump leaching processes is explained. During the bacterial leaching of metal sulfides, ferric ion will partly be hydrolyzed and a variety of sols, gels, amorphous and/ or crystalline mono- and polynuc- lear hydroxo- and sulfato complex species formed, especially by olation and aggregation reactions. There are many problems associated with these iron precipitates especially in the purification of leach solutions. The present study will discuss the iron precipitation reactions; gives kinetic and thermodynamic evaluations of the effect of temperature on pyrite and ferrous iron oxidation; and reports on the tolerance of heavy metal ion concentrations by Thiobacillus ferrooxidans.

Jan 1, 1989

By W. Lin, M. J. McPherson

When a large area of open gob collapses suddenly, a windblast is produced that can cause considerable damage throughout the infrastructure of a mine. In a few cases, the windblast has been accompanied by ignitions of methane and/or coal dust. This paper describes the conduct and results of laboratory tests involving the compression of mixtures of air, methane and coal dust under a falling weight and while allowing controlled escape of the mixture. The transient responses on pressure and temperature sensors were recorded. In addition to an analysis of those records, the paper highlights those conditions in which ignitions occurred.

Feb 24, 1997

By Bruce D. Hansen

For many years, Newmont has focused on improving its operations. After the merger between Newmont and Santa Fe Pacific Gold, Newmont created synergies of more than $50 million a year in Nevada. This was done primarily through optimal ore movements and consolidation of various functions. During the current period of low gold and copper prices, Newmont has refocused its efforts on efficient operations worldwide. At its mine facilities in Nevada, Newmont has used a combination of several strategies to decrease the costs of operations and to increase profitability. These include computer technology, optimal use of infrastructures, procurement strategies, functional consolidation, enhanced mine planning and several available metallurgical processing options.

Jan 1, 1999

By Warren C. Gerler

An overland belt conveyor system is installed for only one reason to save money. It must pay its way on a ton-mile basis over a stated period of time, and do so in competition with other forms of transportation. Such a system with its economies has recently been installed at Simco-Peabody's mine near Coshocton, Ohio by Link-Belt Company. Three miles in length, this system carries coal from open pit and underground mining facilities to the Conesville Power Plant of Columbus & Southern Ohio Electric Company. The coal was formerly trucked from the mine direct to the power plant; but over the years the mining operations have moved progressively farther and farther from the plant, making the over-the-road hauling distance correspondingly greater. Simco-Peabody has mining operations over a considerable area just east of the Conesville Station. The majority of the coal is recovered by conventional strip mining. Some underground mining` is performed by the high wall method.

Jan 1, 1963

By Hemendra N. Kalia

The target to double the coal production by 1995 presents a formidable challenge to the coal mining industry. The mines of future, probably will be located in relatively difficult geological environment because of the exhaustion of the well defined bedded and easily minable deposits. To compound the problems of mining industry will be the reliance of power plants need for coal. The coal must reach the power plants on schedule to avoid expensive blackouts and brown¬outs. It will be imperative that the mines operate without interruptions and at designed capacities. The parameters which have been traditionally responsible for the interrup¬tions of production are: breakdown of production machinery, labor management relations and geological anomalies. Of these three problems, solutions for the first two can be arrived at by developing procedures to correct the situation. A planned maintenance and preventive maintenance program will go a long way in minimizing the equipment breakdowns. Labor relations will eventually improve as the miners begin to enjoy long-term employment. However, with the geological problems, the situation will probably continue to deteriorate and would require careful planning to minimize the impact of geological problems on production and safety. Some of the geological aspects which interfere with production are: faults, washouts, slips and slickensides, water bearing overlying strata, impuri¬ties in the coal seam, and presence of expansive clays in the coal floor. The design of large capacity mines will have to incorporate the geological distur¬bances and mine through them it may become very uneconomical to abandon producing sections because of the presence of the geological anomalies. This paper discus¬ses the geological aspects of coal mining which should receive consideration from the inception of the mining ventures. Pertinent geological aspects are discussed to develop the data base which will aid in evolving safe and efficient mine layouts.

Jan 1, 1976

By S. Ripke

Between 2002 and 2004, the performance of a six million ton per year iron ore beneficiation plant dropped significantly. In a classic case of “who done it,” was it the mine, the concentrator, an ore change, or something else? While average annual final product grade decreased 8% (indicated by an increase in silicate gangue from 2.76% to 2.99%), the weight recovery also decreased by 8% (from 37.92% to 34.79%). This represents a loss of 832,000 tons of iron ore worth about $16 million for the two year period! The concentrator had been optimized to produce a high grade wet concentrate as feed to the dry side of the plant. But, did optimizing an individual unit operation’s grade give the best overall plant performance? In this paper, the investigation and solution to this mystery will be revealed.

Jan 1, 2007

By Doandy Yonathan Wibisono

Shotcrete is a versatile and widely utilized rock support material in mining and civil engineering projects due to its adaptability, strength, and efficient application. It immediately stabilizes rock surfaces, effectively controlling loose materials and preventing rockfalls in underground excavations. This paper focuses on assessing and analyzing data from observations of nozzlemen (shotcrete sprayers) during primary ground support activities in an underground mine. The study highlights the importance of nozzlemen’s skills in ensuring the quality of shotcrete application, which is critical for underground mining operations’ structural integrity and safety. A comprehensive training program and field support were implemented to enhance the nozzlemen’s proficiency. The training set covered theoretical knowledge and practical techniques to improve shotcrete application daily. Proficiency improvement was assessed using quantitative metrics, with rebound percentages decreasing by 5–14% as nozzleman competency increased. The results of this initiative showed significant improvements in shotcrete quality, including increased efficiency, reduced waste, and fewer reworks or rehabilitations. The findings aim to contribute to a broader understanding of best practices in shotcrete application and nozzlemen training, ultimately enhancing ground support application measures in the mining industry.

Feb 1, 2025

By Ehsan Alavi, Brian Hagan, Glen Frank, Michael A. DiPonio, Michael Mooney, Lisa Mori

"The data from EPB cells located inside the pressurized chamber of EPB TBMs and also the data from the pressure sensors in grout lines are quite important in controlling the EPB operation. However, there have always been questions in regards to pressure distribution along the shield body. Could the pressure distribution data be used to come up with potential locations for ground loss? Does the overcut region, the space between the shield body and the maximum cut diameter, consist of broken material or EPB muck, or does that region consist primarily of void space? During free air interventions, how does pressure distribute along the TBM body? To address these questions, one of the two EPB TBMs used in the Northgate Link Light Rail project in Seattle, WA is equipped with EPB cells in front and rear body to monitor the pressure distribution along the TBM body in addition to the standard 6 EPB cells located inside the cutterhead chamber and pressure sensors located at the grout lines. This paper discusses the results of this study and weighs on the valuable data that can be collected by using the shield pressure sensors.INTRODUCTIONThe cutterhead of the TBM is normally equipped with overcutters on the cutterhead periphery which extend into the annular space beyond the diameter of the TBM shield. Thus, the overcutters serve to disturb and excavate some of the ground in the annular space which reduces friction and resistance around the TBM body. This phenomenon is necessary to help the TBM steer and navigate around curves. Additionally, the shield of an EPB TBM is also often shaped like a cone, with the diameter decreasing from the front to the tail shield. This conical shape also helps the TBM to navigate because material that is cut by the cutterhead either gets pulled into the cutterhead or it gets pushed out of the way – around the cutterhead and into the annular space. In EPB tunneling, the conditioned material from the face that does not get pulled into the cutterhead mixing chamber flows into the shield gap and pressurizes the surrounding ground. Additionally, grout can travel from the segment annulus into the shield gap. The pressure in the shield gap mainly depends on the pressure of the material at the face and the grouting pressure behind the tail shield."

Jan 1, 2016

By BERND SCHÖNHERR, JÖRG DEHNERT, PETER WINDISCH, JENS STOPP

The Quick-Erect Stopping System (QESS) offers a new way of reducing the radon exposure of miners in Germany, especially during remediation work in old mines. The QESS is a lightweight, modular and reusable construction kit of interlocking telescopic aluminum tubes, radon-proof foil and expanding foam. It is designed to seal off radon-rich parts of galleries within minutes. Originally, the QESS was developed to protect miners against radon exposure. Then, the QESS found the attention of several mine rescue teams at a German mining conference. Some mine rescue drills by The Student Mine Rescue of the Technical University Bergakademie Freiberg, Wismut Mine Rescue and Front Range Mine Rescue helped to improve the system and highlighted its potential for mine rescue operations. Now, the QESS is well-suited for small-scale mining. The QESS can be used to both protect miners from radon exposure and to support mine rescue operations. Moreover, the QESS was also successfully used in ventilation experiments.

By M. C. Roberts

Currently, mineral producers are suffering through a major downturn in prices for their products, even though it has only been a few years since they were enjoying high prices. From an historical perspective, the current situation is another of the cyclical down-turns that often reoccur every 5 to 7 years or so. This paper uses time trend decomposition techniques to identify the cycles and statistical methods to find the duration of these cycles for a variety of mineral prices. Given some idea of how long and severe these cycles typically are, the mining industry can better plan to weather the downturns and take advantage of the upturns. For example, timing investments in new projects to take advantage of the cyclical upturns can dramatically improve project profitability.

Jan 1, 2000

By John B. Sabey, Vernon R. Degner

The industrial coal processing trend toward greater fines production, due to mining techniques and customer requirements for reduced ash and sulphur content in the fine coal product, is the basis for ongoing efforts to improve the performance of the flotation machine. WCO has successfully adapted the principles of the beds Column to a full size machine prototype. Recent plant evaluation tests confirmed the initial promise of this concept by achieving a considerably lower ash product while maintaining the combustible recovery level of conventional flotation machinery. The paper will include a review of the fundamental principles of the beds Column concept, together with a summary of the WEMCO R&D Program from concept evaluation and laboratory testing, through pilot, to full size machine tests. The performance of the WEMCO/Leeds flotation column will be compared to conventional flotation concepts using a flotation "kinetics" approach, which quantifies the floatable and non-floatable specie recovery performance using the Klimpel model as the basis for analysis. The variety of distinct features unique to this concept include a series of barrier rods which are used to advantage, often together with countercurrent reflux water flow, to achieve a significant improvement in product grade. The hydrodynamics associated with the mechanics of "gangue stripping" from the rising "air bubble-floatable specie" matrix will be briefly reviewed.

Jan 1, 1988

The dissolution kinetics of gold in iodide solutions with oxygen in an autoclave was investigated. The leaching process was described by a gas-liquid-solid heterogeneous reaction. The effect of stirring speed, temperature, partial pressure of oxygen, and concentration of lixiviants on the overall leaching rate was investigated. It was found that the dissolution of gold was limited by a heterogeneous chemical reaction. The apparent activation energy was measured to be 34.7-54.3 kJ/mol under the conditions studied. Experimental findings were in good agreement with the kinetic model proposed.

Jan 1, 1996

By J. Bartrum, A. Bowler, G. Butcher

The purpose of this paper is to outline the design, specification, and operation of the 8.5-m- diam (28-ft-diam) SAG mill commissioned at Kidston Gold Mines during January 1985. Amenability of Kidston ore to SAG milling, coupled with substantial cost advantages, led to the specification of this mill, equipped with variable speed drive to overcome the large variation in ore hardness. Operation of the mill is effected via a number of automatic control loops. Problems experienced with automatic control plus other electrical and mechanical failures have led to design changes and the formulation of future operating strategies.

Jan 1, 1987

By M. Fan

Coal has in general a wide range of density from minus 1.3 to plus 2.0 g/cm3 because of its variations in purity, rank, and porosity, etc. The coal density has great impact on froth flotation performance, but much less attention has been paid to particle density than particle size. Our previous research results demonstrated that cavitation-generated nanobubbles around 700 nm in diameter can significantly improve coal and phosphate flotation performance over a wide particle size range. In this study, the effect of nanobubble on the flotation performances of different density fractions (minus 1.3, 1.3-1.4, 1.4-1.5, 1.5-1.6, 1.6-1.8, 1.8-2.0, 2.2-2.2, and plus 2.2 g/cm3) of coal was investigated using a bank of 10-liter flotation cells, a specially designed 50-mm-inside-diameter column, and a 152-mm-inside-diameter column. It was found that nanobubble has the biggest impact on the flotation performance of 1.4-1.8 g/cm3 medium-density coal particles.

Feb 23, 2014

By C. P. Newman, T. Gray, G. Beale, T. Cluff

Predictive geochemical and limnologic modeling of pit lakes is an important aspect of modern permitting. One of the key assumptions of many predictive pit-lake models is that highwalls and pit backfill become unreactive once submerged by the filling pit lake. Existing pit lakes provide useful data to test this assumption. The Sleeper pit lake (northwestern Nevada) is near hydrologic equilibrium and contains good-quality water that generally meets regulatory requirements for pit lakes. Despite the overall stable geochemical composition, seasonal trends in the hypolimnion indicate the generation of solutes and fluctuations in pH. This work applies mass balance, analysis of subaqueous pyrite oxidation, and trends in solute concentrations to evaluate the potential causes of long-term solute generation in the hypolimnion of the Sleeper pit lake. Results will aid in refining the effect that inundation of highwalls and waste rock has on ultimate pit lake chemistry and long-term closure planning. In the case of the Sleeper pit lake, ongoing solute loading does not substantially change the closure plan at this time as influent groundwater contains abundant alkalinity. INTRODUCTION As mine pit lakes become more widespread, regulatory agencies are increasingly requiring advanced predictive modeling of pit-lake geochemistry during permitting. The end goal of all those involved in these permitting actions (i.e., the mining company, the regulatory agencies, and the public) is to have pit lakes become geochemically and hydrologically stable for the long term, which may then allow mining permits to be relinquished. The modeling endeavors therefore are important to inform long-term closure of pit lakes. The conceptual models and numerical methods used to predict pit-lake water quality are complex and require substantial amounts of data and a variety of assumptions (Castendyk et al., 2015). One of the common modeling assumptions is that solute generation via acid mine drainage is eliminated (or at least decreased) by the filling of the pit lake and inundation of highwalls and any in-pit waste rock. However, few studies have reported on observations that support or refute this assumption. The water-quality record of the Sleeper pit lake is an ideal dataset with which to test these assumptions. The former Sleeper mine is located in northwestern Nevada (Fig. 1), and has been inactive (in terms of ore extraction) since 1996. The mine extracted Au and Ag from the famous high-grade Sleeper vein and associated widespread stockwork mineralization (Nash et al., 1995). Water quality in the pit lake has been monitored since the cessation of dewatering in 1996. The current pit lake actually occupies three separate sub-pits, the Sleeper, Wood, and Office pits (Fig. 1). The Sleeper and Wood pits undergo regular water-column monitoring using a conductivity-temperature-depth (CTD) probe, and sampling for dissolved inorganic constituents at several depths (~10, ~130, and ~330 ft. below lake surface). Groundwater quality is also monitored using a series of wells (Fig. 1).

Jan 1, 2019

By Chikaosa Tanimoto

INTRODUCTION Bratislava is located at the intersection of important traffic routes, including motor-ways, roads, railways, air traffic, trading, and inland waterway with an important harbour. The construction of the D2 Motorway Bratislava, Lamacska cesta Stare grunty was the last missing section of D2 Motorway and its completion linked the Czech Republic through Bratislava to the Hungarian Republic. Traffic was obliged until its completion to use the Lamacska Road and Mlynska Dolina, which were the most heavily trafficked roads in the city. The section of D2 Motorway to be completed in 2006 was 3,300m in length, of which the SITINA Tunnel was approximately half the length. After putting into operation the transit traffic(motorway) and urban traffic was separated. Transit traffic by passing the town was eased. The junctions D2 with Lamacska Road (Harmincova) and Mlynska Dolina also allowed better use of the motorway for the urban traffic The tunnel construction was specified by the features with the highly weathered and thermally altered granitic rock formation with the overburden of Quaternary sediment of 2?4 m thick, very thin overburden, severely controlled deformation limit and environmental protection. The tunnel had to be excavated beneath and nearby the academic complex area and the zoo, where sensitive facilities exist and animals live in. The tunnel consisted of two tunnels (Tunnel A and B) with the length of 1,415 and 1,440 m, respectively. The overburden thickness was in the range from 10?30 m. The standard cross-section and the one with invert arch were 79.5?81.5 m2 and 92.1?93.3 m2. The excavation took 21 months from September 2003 to May 2005. The construction was based on the concept of NATM. The SITINA Tunnel was the third application of NATM in Slovakia, following the BRANKISKO Tunnel (commenced in July 2003) as the first and the HORELICA Tunnel (in October 2004) as the second NATM practice. To protect the surrounding structures and citizens from tunneling operations, seismic monitoring was performed in association with blasting. The allowable limit of blasting vibration was fixed to be under the particle velocity of 15 mm/sec. The tunnel excavation cleared this limit as expected before construction. In driving through the difficult geological situation the excavation work hit 49 faults, and some of them occasionally caused serious face instability. In principle, the rock formation has been affected by the high hydrothermal effect and the resultant clay filing along faults and joints. The auxiliary reinforcement with the 4?8 m long pipe roofing was needed to protect the vicinity of mining face area. This operation extraordinarily required additional works and time which had not been expected before construction.

By Pramod C. Thakur

Methane drainage by cross-measure boreholes on retreat longwall faces can be a viable alternative to the vertical gob degas boreholes under favorable circumstances. The research was done in a mine working Pittsburgh Coal seam in Northern West Virginia under U.S.B.M. Co-operative Agreement No. 14-09-0050-3252. The study was the first application of this technique to Pittsburgh coal seam. A total of fourteen, small diameter, inclined boreholes were drilled over a retreat longwall panel from gate roads, to intersect the overlying coal seams. All boreholes were manifolded to a pipeline and the gob gas was extracted by an exhaust fan on surface. The methane capture ratio was poor at 7 to 18% at various stages of the longwall panel. A vertical gob degas borehole captured an additional 20% gas. Poor results were due to premature failures of the cross-measure boreholes leading to air leakage. For better performance the boreholes should be drilled from a point 30 to 45 m from longwall pillar over the largest chain pillar, the standpipe should be grouted for at least 6 m, and the entry containing boreholes and the pipeline must be supported to ensure access for maintenance, and optimization of methane capture. Coursing the ventilation air around longwall such that it forces methane-migration towards cross-measure boreholes can further improve methane capture. The optimum vertical inclination is 45° ± 10°.

Jan 1, 1983

By M. Churchill, V. R. Degner

Over the past two decades, declining ore body grades and increased operating and construction costs have provided an incentive for the development of progressively larger flotation machines. As a result, the 1.7-2.8 m3 (60-100 cu ft) flotation machine of the 1950's and 1960's is being rapidly replaced by large volume machines. The result has been improved flotation machine specific capacity (tph processed per sq ft of floor space); specific power (hp per tph processed); and process control simplicity. The recent development and satisfactory plant evaluation of the 28 m3 (1000 cu ft) flotation machine allows economic and operating advantages in high tonnage mill applications. Some principles of mechanically induced air flotation and the development of the large 28.3 m3 (1000 cu ft) flotation machine are reviewed here. Performance evaluation in beneficiating metalliferous ores-copper, zinc, and iron-is also given and recently completed plant results provided. Mining lower grade ore bodies results in the need to process increased tonnage in the concentrator. This greater tonnage requires more individual flotation machines, unless individual machine capacity, or cell volume, is increased. As the ore processing rate of the concentrator increases, the benefits of progressively larger individual cells in the flotation section become more significant. The accompanying figure illustrates the advantages of a larger flotation machine. In the figure, the number of machines in the rougher-scavenger section is related to the plant tonnage for three sizes of flotation machine: 8.5 m3 (300 cu ft), 14.2 m3 (500 cu ft), 28.3 m3 (1000 cu ft). The 28.3 m3 (1000 cu ft) flotation machine results in 95 fewer machines, compared to the 8.5 m3 (300 cu ft) machine at 45.4 kt/d (50,000 stpd) feed. The flotation cell reduction is, of course, doubled at a plant production rate of 90.7 kt/d (100,000 stpd). Using fewer flotation machines saves floor space. The 14.2 m3 (500 cu ft) and the 28.3 m3 (1000 cu ft) machines result in a floor area reduction, relative to the 8.5 (300 cu ft) machine requirements, of 134.7 and 418.1 m2 (1450 and 4500 sq ft), respectively, for the 45.4 kt/d (50,000 stpd) rate and 269.4 and 836.1 m2 (2900 and 9000 sq ft), respectively, for the 90.7 kt/d (100,000 stpd) rate. In addition, flotation practice has shown that the "specific power intensity"-power per unit cell volume-is less for increased cell size. This results in a power draw reduction, for the rougher-scavenger circuit, of between 552 and 686 kW (740 and 920 hp) for the 14.2 and 28.3 m3 (500 and 1000 cu ft) machines, respectively, when processing 90.7 kt/d (100,000 stpd). Fewer cells improve machine control and simplify maintenance needs while reducing floor space and power requirements. These are tangible incentives for the development of large flotation machines for high tonnage applications. Flotation Principles The accompanying figure shows how key hydrodynamic regions influence the performance of a mechanically induced air flotation machine. Air is induced into the fluid from the top of the cell, due to the mechanical action of a rotating impeller. The impeller circulates the liquid, or pulp, from the bottom of the cell. The result of these dual flow paths is the mixing of the two fluids and one solid phase in the highly agitated region where physical contact between the air bubbles, and the solid particles to be floated, is accomplished. The particle to be floated is assumed to have a properly prepared hydrophobic surface prior to flotation. Upon leaving the three-phase mixing region, the "floatable particle-air bubble matrix" and

Jan 7, 1982

By L. G. Tejada, T. Sjursen

In the production of ferronickel at Falconbridge Dominicana's plant in the Dominican Republic the Reduction Plant plays a vital role by partially reducing the nickeliferous oxide ore, and pre- heating the charge to the electric furnaces. Ore is agglomerated in the form of pillow-shaped briquettes which are screened and fed to 12 open-top shaft furnaces. Hot (over 1250°C) reducing gases are partially cooled (less than 1150°C) and introduced through a set of primary tuyeres. The reducing gas rises counter-currently to the flow of solids. A portion of the partially spent reducing gas is withdrawn at the furnace top and recirculated through a set of secondary tuyeres, 1800 nrm above the primary tuyeres. Together with the recycle gas a controlled amount of air is also added to react with the partially spent reducing gas in order to preheat and dry the charge in the upper part of the shaft furnaces. The calcine is discharged through three discharge legs and pusher block assemblies into open-top refractory lined cars. These cars are then hauled to the electric furnace, parked over selected feed ports, and discharged through bottom gates. The furnace exhaust gas is de-dusted in cyclones and then passed through Venturi scrubbers. The slurry is fed to a thickener, filtered, and recycled to the ore receiving hopper in the ore preparation area. Dust generated throughout the plant is collected, wetted to conform with briquette press feed, and recirculated in a controlled manner through the feed system.

Jan 1, 1979