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By Jan Wolski

Increasing interest in the Bucket Wheel Excavator (BWE) technology calls for a universally understandable definition of suitable performance factors which would reflect the unique features of this technology. The importance of properly designed and calculated performance factors for the BWE systems cannot be overemphasised. They are used by all levels of management in any mining organization for a wide variety of purposes, in particular for budgeting, for selecting new equipment, for monitoring current equipment and for comparison with other operations.

Jan 1, 1984

By Ulrich Maidl, Gustavo Aguiar, Argemiro Ferreira, Marco A. Peixoto Silva, Marc Comulada

"Metro Line 5 in Sao Paulo is being constructed. This lot extends for 4,940 m with twin EPB shield tunnels under a dense and busy urban area, with an excavation diameter of 6.9 m. The tunnels run predominantly in the tertiary soils of Sao Paulo where extensive experience exists from previous EPB shield tunnel projects. However, new experience is being gained in Sao Paulo in shield tunnelling through Saprolite, the weathered product of the underlying Gneiss crystalline basement, through the resulting residual soils and in rock-soil mixed face conditions. Furthermore, experiences in difficult mixed face soil conditions with overconsolidated clay at the face in combination with loose sands at the crown under the groundwater table will be presented. Additionally, the design, operational and controlling approach followed for the shield drive at particular critical cross-sections where the shields were driven close or under buildings. INTRODUCTION Within the framework of Sao Paulo´s metro network expansion, the excavation of the shield tunnels for Metro Sao Paulo Line 5 is currently taking place. The present paper deals with the description of the most relevant features from the construction of the Line 5 – Lot 3 tunnels. The paper presents how particular challenges were dealt maximising potential of EPB shield tunnelling technology. Challenges were posed not only by the difficult boundary conditions of urban shield tunnelling, such as shield drive under buildings, but also by complex geotechnical situations. PROJECT DESCRIPTION The great urban area of São Paulo is one of the biggest cities in the world, with around 20 Million people living in the city and in the suburb area. The city faces great mobility problems and in the last years the government has been investing great amounts on the megacity´s metro expansion. The Line 5 Extension plays an important role to connect the south area to the central area of the city, with a whole extension of 11 kilometres, including 11 new stations. It is estimated that this line will transport almost 900.000 passengers/day. The first stretch of the expansion, Lot 3, consists of two single tunnels, almost 5 kilometres long each, crossing 4 stations. Figure 1 shows details of the Line 5 Expansion."

Jan 1, 2016

By R. D. Lopez

The concept of "heat recuperation" for the grate-kiln pelletizing system was first implemented at the Sydvaranger plant in Norway in 1974. Essentially, heat recuperation involves bringing hot air from the second stage of the pellet cooler to the drying zone to increase drying-air temperature to the maximum limit. 'Burner-fuel savings result from a lower kiln secondary-air mass flow at a higher temperature. Because of the fuel benefits achieved at Sydvaranger, heat recuperation has been included innumerous new grate-kiln plants built since then, and some older plants have been retrofitted for heat recuperation. In recent years there has been much confusion about the fuel benefits of heat recuperation. To answer some of the questions, a mathematical model was developed and plant tests were conducted at Minntac Phase 111. Minntac is a magnetite taconite concentrating and pelletizing plant, and Phase III has two indurating lines. This paper presents the results of the studies and plant tests.

Jan 1, 1980

By M. du Plessis, J. P. Gouvea

Mesh based areal support is commonly applied in South-African deep-level gold mines. It forms part of an integrated support system that can cater for both rockfall and rockburst incidents. The application has been successfully applied over many years. Operations have different geotechnical conditions and practical considerations, which has led to the development of various types of mesh and integrated mesh-based support systems (i.e. meshing and lacing versus welded or chain-link mesh sheets). Typically rolls or sheets of mesh is pinned with rockbolts to the surface of an exposed excavation. Applications vary from hangingwall coverage in a conventional stope gully to complete excavation coverage in footwall drives of conventional mines or on-reef drives in massive mechanised mines. It is however critical to understand the behaviour of the rockmass and apply suitable support systems.

Apr 26, 2022

By William E. Horst

Ore grindability data based on various techniques to measure comminution characteristics are used to evaluate the crushing and grinding efficiency in mineral processing operations. The importance of achieving improved comminution efficiency, in terms of energy consumption, has been emphasized by recent increases in the cost of electricity. From a theoretical standpoint, the objective of a grinding operation might be expressed as maximizing the production rate at a given grind size while minimizing the energy consumption per ton of material ground. To achieve this objective in an industrial operation presents a challenge especially in view of changes in the raw material which are normally encountered. Various procedures1-5 used to determine energy-size parameters and grindability measurements have been reported. The proposed relationships between particle size and energy consumed have much in common between many of the techniques for measuring grindability. Probably the most widely used parameter to measure ore grindability in recent years is the Bond work index6, Wi, which is defined as the kw-hr per ton required to break from infinite size to a product size of 80 percent passing 100 microns. If the breakage characteristics of a material remain constant over all size ranges, then the calculated work index would be expected to remain-constant since it expresses the resistance of material to breakage. However for most naturally occurring raw materials differences exist in the breakage characteristics depending on particle size, which can result in variations in the work index depending on grind size. Consequently work index values are generally obtained for some specified grind size which typifies the comminution operation being designed or evaluated.

Jan 1, 1975

By F. G. Miller

In mid-1972 we determined that a fresh approach to coal mining research was needed for the industry as well as for Bethlehem. The reasons to us were obvious: Productivity was in the throes of a steady decline, and labor and maintenance costs were spiraling upward. Yet, despite this predicament, nowhere in the U.S. at that time was there a comprehensive and coordinated research and development plan in the offing. The Bureau of Mines had not yet been charged with such a responsibility, and industry was content to rely on machinery manufacturers for innovations. After studying our own mining practices, the state-of-the-art of mining research elsewhere, and development work by manufacturers, we presented a comprehensive research package to our management at the end of 1972. The ideas and experience of many operating and management personnel in our Corporation contributed to the formulation of the final plan as approved.

Jan 1, 1976

By C. Perea, O. Restrepo, C. Ihle, H. Estay

In this study, research on the use of monosodium glutamate for copper leaching, with emphasis on the thermodynamics and oxidant characteristics, is presented. Copper dissolution was conducted following a hydrometallurgical route, using monosodium glutamate in alkaline solutions. The effect of oxidizing agents such as hydrogen peroxide (H2O2) and potassium permanganate (KMnO4), and the efficiency of copper leaching with glutamate compared with glycine have been studied. Results, obtained at room temperature, showed 92% recovery of copper using 0.03 M hydrogen peroxide, 0.5 M monosodium glutamate at a pH of 9.44.

Mar 2, 2022

By Brig M. Moudgil

It was reported earlier that francolite and dolomite from the South Florida deposits cannot be selectively floated using conventional conditioning with sodium oleate as the collector. However, dolomite could be separated from francolite if the minerals were first conditioned at pH 10 followed by reconditioning at a lower pH. An optimum separation was achieved at a reconditioning pH below 4.5. Reconditioning pH and collector concentration were determined to exert a major influence on the selectivity. Flotation, adsorption and transmission infrared spectroscopic results are presented to elucidate the mechanisms underlying the observed selectivity.

Jan 1, 1984

By T. Klemetti, W. H. Su, M. A. Van Dyke

Entry stability in coal mines is dependent on geologic conditions and engineering controls. Most engineering controls in ground control are predictable and standardized for typical geologic conditions. However, geologic anomalies may exist that are difficult to detect with traditional core hole drilling. Borescopes offer a cost-efficient way to gather more geologic data between core holes. Additional data obtained from borescope results provide a clearer picture to enhance detection of hazardous conditions due to geologic anomalies. The equipment, methods, and analysis of borescope results provide geomechanical engineers with a clear understanding of strata behavior and the best information to implement roof control plans and supplemental support to enhance miner safety and health. INTRODUCTION Borescope technology has changed very little since its inception. However, the idea to use borescopes to examine roof strata started with the U.S. Bureau of Mines in 1979 with the production of a fiber-optic borescope (FitzSimmons, et al., 1979). The first documented use of a borescope in the coal mining industry began during the 1980s in Australia by researcher John Shepherd. Shepherd’s idea was to use a borescope to collect a series of data points from the roof lithology and compose a geologic cross section. The cross section was then used to identify key features that suggested the beginnings of roof failure. The features Shepherd identified were bedding plane separations in the roof and low angle, extension, and tensile failures. Shepherd also suggested that the borescope findings could be used for geologic mapping for lithological variation, fracture distribution, and determining if supplemental roof support was needed (Shepherd, et al., 1986). In the United States the first publication about borescope usage for coal mine stability assessment was by Su and associates in 1999, who specifically related the combination of using borescope, geophysical, and corehole data to produce geologic hazard maps (Su et al., 1999). This work directly linked the usage of a borescope with the design of supplemental roof support. The use of borescopes in mining was adopted industry wide by the 2000s. Operator case studies were being published using borescopes to aid in supplemental support recommendations and hazard mapping. An Australian study published in 2007 based the optimization of secondary support after each longwall pass on the results of borescope data. The study stated that the borescope was an invaluable tool for understanding roof behavior (Black, et al., 2007). In 2009, a publication by the National Institute for Occupational Safety and Health (NIOSH) took the concept of borescoping one step further. The work centered around creating a roof quality index (RQI) for limestone mines based on borescope data. The RQI attempted to assign a ranking to establish the nature of the roof and its stability (Ellenberger 2009). In theory, this would have been a very useful tool, but the RQI system has not been widely adopted in the industry.

Jan 1, 2019

By Peter J. Szabo

In 1980, a caravan of representatives of Japanese trading companies debarked on the shores of the United States bearing gifts of watches, electronic games, and radios. In early 1983, we find in a parking lot of a major U.S. coal company, a haggard general manager of marketing returning to the Orient with a box under his arm of trinkets of his own; cross pens with company logos, alarm clocks, etc. The tables have turned, but our fellow sitting in a jet plane over the Pacific Ocean had only to heed the warning of the famous 19th Century poet well familiar with the ways of the Far East. Kipling said; "And the End of the Fight is a tombstone white and with the name of the late deceased, And the epitaph drear, a fool lies here who tried to hustle the East."

Jan 1, 1984

By M. K. Rizkalla

This paper discusses the time-dependent behaviour of rock when it involves the presence of several layers of rock strata in the vicinity of mine openings, mining in sequences and the placement of backfill. The paper describes numerical techniques which proved useful when such situations are encountered in practice. The model is elastoviscoplastic. At given time stations, short term loading or changes can be made to the creep behavior of the rock. The modelling technique is first described and is followed by simulations of stresses and displacements in a potash mine with the primary objective to demonstrate the effect of such aspects as mining and fill sequences in 3-D. This involves cutting finite elements representing the strip of the mining face and simultaneously filling those elements representing the newly placed fill. The stiffness of the fill varies with the degree of compaction at each point. In this way, the effect of the time of fill placement, the gap between the top of the fill and the back as well as the degree of compaction are simulated. The second example is a 2-D problem simulating the long term effect of backfill, as a material compacting with time, on the settlement of the layers above it as well as the closure of the room.

Jan 1, 1996

By S. Tuylu, D. Adiguzel, A. Bascetin, H. Eker

"Tailings can be more stable in-site where they are stored and and so the risk of conventional tailings dam accidents can be reduced by alternative methods. In recent years, surface paste disposal (SPD) method is one of the alternative tailings storage methods. According to the results obtained from the previous lab scale experiments, optimum storage design was determined and then, this design was carried out in-site application under atmospheric conditions by a pilot scale tests. In the field study, two separate dams with no environmental hazards were established by the hazardous waste storage directive, whose surface area is measured as 400cm × 200cm. Also physical changes in the paste tailings were measured by the sensors such as volumetric water content, mutric suction and oxygen consumption. In addition, seepage water was collected in the drainage pool and examined for acid mine drainage and metal mobilization risks. As a result of the preliminary data obtained from measurements of pilot scale tests, when the pH value of seepage in the cemented dam (only 1th and 10th layers with cemented) is about 11, the pH value of seepage in the uncemented (reference) dam is measured at 8-9. INTRODUCTION Environmental damages occurred during the deposition of mine process tailings at surface using conventional methods (tailings dam etc.) can be reduced and/or eliminated with the use of new technologies and methods to an important extent. Nowadays, it has been investigated to safely deposit metal mine wastes generally discharged into surface tailings dams, seas, rivers, creeks etc. using Paste Tailing Technology which gains the growing importance in recent years. Meanwhile, Paste Tailings Technology has two applications in industry as an underground paste backfill and surface paste deposition. Particularly scientific studies about deposition of process tailings as paste sample in underground and surface have been increased. These studies showed that surface paste deposition can minimize the free water amount which is the biggest problem in conventional tailings dams. Additionally, it also provides less particle segregation, in other words, the formation of more homogenous material, the development of geotechnical properties which causes to obtain more stable material, increases the strength and stability of the paste with addition of binder where necessary surface paste material, and reduces the risk of Acid Mine Drainage (AMD) (Bascetin et al., 2017a). Theriault et al. (2003), Martin et al. (2006) and Simms et al. (2007) reported that Bulyanhulu mine in Tanzania is the first gold mine to employ surface paste disposal (SPD) worldwide. Here, tailings are deposited alternately via several towers. The tailings flow away from each tower to forming a conical deposit. Each layer had a lower thickness than 30 cm. The fresh tailings were poured on top of drying and hardening layer after a waiting period of 5-30 days. No cement was added into the tailings to prepare paste material. Uncemented paste was deposited by a solid content of 73% which corresponded to a 250 mm slump cone height (Yilmaz et al., 2014). In a study conducted by Yilmaz (2010) illustrates the preliminary results of a field cell testing undertaken to investigate the effect of in situ climate conditions and material properties on the performance and quality of fine-grained, sulphide-rich paste tailings at the LaRonde mine in Quebec, Canada. A total of two field cells are constructed in the surface disposal site of the mine and categorized as cemented cell CC and uncemented cell UC (Bascetin et al., 2017b)."

Jan 1, 2018

By George M. Anderson

The extraction of industrial minerals is usually confined to relatively small mining operations. The recent COSMAR (Committee on Surface Mining and Reclamation) report found that 93% of all mines in the United States were of the small unit variety. Also, of the total number of mines in the U.S. (15,279) 96% were in the industrial minerals (non-metals excluding coal) category. To break it down further, 86% were sand and gravel, and crushed stone operations. Therefore, we are talking about a very large number of small mining operations. If these small miners can afford to hire a college graduate, what kind of training should this person have beyond the normal mining engineering curriculum to best serve the problems that he or she will encounter?

Jan 1, 1981

By R. W. Sims

"He?s an SOB, but he's my SOB." Many of us have heard this line in reference to attorneys, and can appreciate the humor. However, the thought reflects a deeper attitude that lawyers should be used for attack purposes in the legal system or the regulatory process. Often, more permitting progress can be made with tact and flexibility than with inflexible, overly aggressive strategies. Usually, administrative hearings or other litigation work to the disadvantage of the applicant. Thus, I have concerns about approaching any permitting system with a hard-line attitude. On the other hand, the project team must always be prepared to defend permit applications and present a legally adequate case at public meetings, administrative hearings, or judicial proceedings. This paper discusses a number of strategies intended to increase the probabilities for successful permitting, whether opposition is informal or highly organized.

Jan 1, 1990

By J. Y. Hwang

Alunite has been utilized as raw materials for producing alumina and potassium sulfate fertilizer in Russia for many years. In the United States, this mineral has not been commercially processed though reserves of 5 to 10 billion tons of alunite ore have been estimated. Major constituents of these ores include quartz and alunite. The minerals are finely intergrown and liberation occurs below 10 microns. Adequate separation techniques for such fine particles have not been developed. A new method for the beneficiation of alunite ore is proposed in this study. 'Ibis method utilizes a small amount of fine magnetite upon which the liberated quartz is selectively flocculated. The co-flocculated magnetite and quartz are then separated from the alunite in a high gradient magnetic separator. Clean products, e.g. an alunite concentrate of 90% grade with 80% recovery, has been obtained from an Utah ore. Techniques for the selective co-flocculation of magnetite and quartz, the separation of the carried quartz, and the recovery of magnetite after separation are discussed.

Jan 1, 1985

By Michael A. Trevits

The National Institute for Occupational Safety and Health (NIOSH) in partnership with Strata Products tested the sealing capability of Ventstop®? as part of an ongoing mine fire control and suppression research program. Ventstop®? is a multi-purpose, inflatable device that is produced by Minvent Solutions and is available world wide for use in the metal and nonmetal mining industry. Ventstop®? is also used in the Australian coal industry as a temporary ventilation control device. The device can be quickly deployed, is reusable and can be placed in horizontal and vertical mine voids to control dust, fumes and smoke. Deployment, multi-day inflation and air leakage tests were conducted at the NIOSH Lake Lynn Laboratory to determine the capability and limitations of Ventstop®? in a simulated coal mine setting. During the tests, Ventstop®? was also subjected to low level forces of a nearby methane gas ignition. It is thought that Ventstop®? could be used by the US coal mining industry to temporarily close an underground mine area in response to a fire or spontaneous combustion heating event, to temporarily redirect mine ventilation during longwall equipment moves or during stopping construction. This paper describes this inflatable temporary mine sealing technology and presents the results of the NIOSH tests.

Jan 1, 2009

By W. L. Staker

The Bureau of Mines investigated selective extraction of Au and Ag from a low-grade Au ore containing Hg. Gold and silver were extracted from the ore in cyanide slurries, and Hg extraction was suppressed with sodium or calcium sulfide. Maximum Au extraction and minimum Hg extraction were obtained using solutions containing 0.34 lb NaCN/ton of solution. Increasing the cyanide concentration increased Hg extraction without increasing Au extraction. Mercury extraction from the ore was suppressed with 0-5 to 2.9 Pb CaS/lb Kg in the ore. Gold-to-mercury ratios of 100:1 to 400:1 were obtained in the leach solution, and on the activated carbon in a CIP circuit.

Jan 1, 1983

By R. H. Hanewald

The processing of EAF baghouse dusts from both the specialty steel industry and low alloy producers will be reviewed. In addition, the INMETCO process has been modified so as to recover nickel, chromium and iron from many other waste materials such as pickling solutions or filter cakes, spent nickel and chromium plating baths, carbon refractories from pickling tanks, and super alloy wastes including baghouse bags. INMETCO is the only North American company presently capable of recycling nickel-cadmium batteries by high temperature metals recovery. This, along with the details of INMETCO's BDAT Test Program and results performed to pre-agreed standards with the EPA will be discussed.

Jan 1, 1992

By V. J. Hucka

A 0.5 m (20 in) diameter high pressure natural gas pipeline crosses over a coal mine located in Central Utah. Ground movement induced by the mining operation could possibly place excessive strain on the pipeline causing it to rupture. The mining operation extracts coal from two seams using the room and pillar method. The seams are situated one on top of the other and both lie directly under the pipeline. At present, only the upper seam is being mined beneath the pipeline. However, in the future, the mining operation of the lower seam will also affect the pipeline. As would be expected, mining of both coal seams causes surface subsidence. This is especially true when the pillars are extracted during retreat.

Jan 1, 1983

By Takashi Goto

In 1968 three historical rockbursts had occurred at Bibai Coal Mine in Hokkaido. At the time they had been observed by several seismic observatories as natural earthquakes away more than 100km from Bibai City. These facts taught us that the occuerrence of failure yielded in underground opening that was accompanied with seismic wave could be observed by seismometer on the surface. After two years from this desaster, the study concerning to microseismic events generated from underground mining panels has been begun by researchers with heart-throb.

Jan 1, 1982