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By Dean Newman, Michael Behrens, Mark Trim, Justin Arifin

Road tunnels in recent infrastructure projects in Sydney, Australia, are designed to have a fire resistance level of either a 4-hour cellulosic fire or a 2-hour hydrocarbon fire. Where permanent ground support for tunnels consists of systematic rock bolts and relatively thin layer of shotcrete, it is important to ensure that during and after the fire event the ground support is designed/predicted not to pose risks to the tunnel occupant. The global behavior of the ground support can be predicted using finite element analysis, and its resistance is derived with consideration of the material strength degradation due to the elevated temperature.

Dec 1, 2022

By J. A. Ehler

Speed and torque control of standard A.C. induction motors can be accomplished using a variety of devices ranging from mechanical, hydraulic, and electrical. Also, the motor can be specified as an A.C. wound rotor or D.C. motor using the associated controls. Normally, any one of these drive types can be adequately used to provide the torque control necessary to accelerate a conveyor belt system. The selection will depend on the economics, experience, and preference of the designer or end user. These drive types will be presented from a functional and performance viewpoint to assist in the understanding of the available technology.

Jan 1, 1998

By B. C. Haimson

The Committee on Rapid Excavation of the National Research Council has recognized in its 1968 report the need for "improvement of rock-mechanics techniques for measuring subsurface stress field in deep boreholes and for determining stress distribution in walls of underground excavations". The technique recommended in this paper as being most suitable for both deep hole and tunnel wall stress determination is Hydraulic Fracturing. Using this method stresses are calculated directly from the fluid pressures necessary to initiate and extend a fracture away from a borehole. Stress determination by hydraulic fracturing is rather insensitive to inhomogeneity or anisotropy, is not limited in depth except by the length of the hole, requires simple equipment which is commercially available, and can be carried out by unskilled personnel. The method has been worked out theoretically and extensively tested and verified in the laboratory. A number of field tests in deep holes ranging from 300 to 6300 ft have yielded surprisingly good results. Preliminary underground tests have been very encouraging and most recent measurements in a tunnel complex at the Nevada Test Site yielded stresses that were both consistent and reasonable when compared with the expected directionsand magnitudes. It is recommended that hydraulic fracturing be considered as a method of in-situ stress measurement both in the pre-excavation stage of design and during tunneling.

Jan 1, 1974

By Jayson Ripke, Peter Amelunxen, Brandon Akerstrom, Fernanda Solís

It is commonly known in the industry that one of the key challenges for a greenfield project, such as Capstone Copper’s Santo Domingo project, is the obtention of samples for metallurgical testing and subsequent plant design. To face this challenge, the Santo Domingo project completed 169,692 meters of drilling. The material collected has been used for a variety of analysis including the economic recovery of iron, which contributes significant economic value to the Santo Domingo business case. Composite and variability samples, covering the main geological units considered in the life of mine (LOM) plan, were selected for bench and pilot scale testwork. Davis Tube Tests, small scale Low Intensity Magnetic Separation (LIMS) tests and a pilot utilizing a 48 in (1.2 m), diameter magnetic separation drum were completed. The testwork demonstrated that the Santo Domingo ore could achieve iron concentrate grades of 65% Fe - suitable for blast furnace, and 67% Fe - suitable for Direct Reduction, primarily by concentration of magnetite. The outcomes of this work have informed the iron concentrator plant design and scale up.

Feb 1, 2025

By T. Weatherwax, A. Rai, J. Poor

"This paper provides an overview of the current use of auxiliary ventilation products and the challenges with limited air quantity in dead-end entry or working faces. The PVC’s low frictional factor, low physical constraint and minimum leakage properties were ideal to develop as ventilation duct in conjunction with the concept of ""Made in the US and Used in the US"". The PVC duct supports the operational and total cost of ownership with on-going success. This paper will discuss the continuous improvement made in ventilation ancillary products for optimum results. The paper will also cover mine site usage of second generation PVC vent duct underground and the results from the operational and technical side making a difference in health and safety and overall auxiliary ventilation. INTRODUCTION The Barrick Turquoise Ridge Inc. (TR) is located in northern central Nevada, and is situated within the Basin and Range province, near the northeast end of the Osgood Mountains (see Figure 1). The TRJV mine consists of typical Carlin type- gold mineralization characterized by low strength rock of altered limestone, siltstones, and mudstones. The weak nature of the ground facilitates the need for underhand cut and fills mining methods.Mining Method; Underhand cut and fill: The mine uses underhand cut and fill method which has 12’x12’ and or 14’x14’ top cuts with several different size undercuts. The ore body is accessed off of a secondary tertiary heading, utilizing a heading with a cross section of 14W x 14H or 15W x 15H configuration. In the wider and more massive zones, two headings in a production panel may be worked at any one time. Drift round lengths are determined by the ground conditions and drift dimension. An example of a typical topcut and associated undercut layout is shown in Figure 2."

Jan 1, 2016

By William Gleason

"It has been more than 10 years since Montana Resources’ copper/molybdenum mine has had a lost-time injury at its site in Butte, MT. With more than 350 employees and an average production of about 15.5 Mt/a (17 million stpy), which includes 29.5 kt (65 million lbs) of copper and 4 kt (9 million lbs) of molybdenum, the mine’s journey to a decade of exemplary safety is an impressive feat that has required hard work, commitment and, most of all, leadership from every level of the operation.It has not always been an easy journey, nor has it been one without scrapes and bumps along the way, but it is one that has produced stellar results. Mike McGivern, vice president of human resources, and Pete Steilman, safety manager at the mine, spoke with Mining Engineering about how the operation transformed from a site that was accustomed to collecting citations for safety violations to one that is now collecting awards for its safety record.Simply put, Montana Resources has made safety a value and the people its top priority.The operations faced many predictable challenges in 2003, when the mine was being brought back online after three years of sitting in care-and-maintenance status. It had been shuttered in 2000 because of low commodity prices and high operating costs, and, in the three years that the mine was idled, the equipment became dilapidated, and some of it was no longer in compliance. Less than half of the workforce returned to the site for the restart, and the team was challenged with getting the gears turning again to produce copper and molybdenum. But the most daunting challenge of all of was keeping the workforce safe during the transition.In the first few years of operation the mine racked up citations from the U.S. Mine Safety and Health Administration (MSHA) at an alarming pace, so much so that in May 2006, Montana Resources received a letter from the MSHA District Office informing the company that the operation was being placed on the Potential Pattern of Violations list due to its excessive citation history and high rate of significant and substantial citations. It was clear that something significant had to be done to change the course of action at the mine."

Oct 1, 2019

By Lingyun Zou, Xinghai Lei, Tiezheng Li, Yifei Song, Nan Wang, Yang Li

The stability of key strata is of utmost importance in ensuring safe and effective coal seam mining operations. To minimize disturbance impacts on these strata and ensure their stability, it is crucial to assess the degree of disturbance caused by mining activities. This study proposes the evaluation index “disturbance degree of key stratum (KSDD)” and establishes a quantitative KSDD criterion to measure the degree of disturbance on key strata. To facilitate the assessment process, an intelligent calculation system for KSDD is developed. The classification criteria are derived by combining the measured three-zone heights from multiple mines. The reliability and accuracy of the KSDD quantitative criterion are validated using field measurement data. Furthermore, the KSDD quantitative criterion is applied to the Meihuajing mining area No. 23, and the distribution characteristics of KSDD are analyzed. The findings of this study can serve as a valuable reference for reducing disturbance and enhancing the stability of key strata during subsequent mining operations. Overall, this work contributes to the field of ground control in coal seam mining by providing a comprehensive approach to assess and mitigate the disturbance caused by mining activities on key strata.

Mar 8, 2024

By Peter A. Gillett, Ian S. Clelland, J. G. S. Hynd

Today mine shaft and slope contracts include a greater amount of ancillary work such as level and pump stations, loading pockets, rotary and side dumps and connecting raises. This ancillary work requires the application of a number of construction methods often for short periods and often at short notice if the contractor is to maintain a profitable operation. In the next decade, the number of shafts that will be sunk by a boring method will outnumber those sunk by traditional methods. This will be particularly true of the deeper shafts where water problems are minimal. The increase of bored shaft work will not decrease the work completed by the shaft sinking contractor but it will change it. A greater emphasis will be placed on the speed of construction of station and other ancillary work. To meet this challenge the contractor requires full information on the ancillary work as well as the shaft work at an early date, preferably pre-bid. The two examples discussed in this paper illustrate the importance of early information. The two main factors of shaft ancillary work construction are sequence and ground support. This paper describes two examples completed recently by The Cementation Company of America Incorporated in Arizona. The first described is a Rotary Dump-Ore Pocket-Ore Pass complex and the second described is the excavation of the Main Station Level in a 2 Station-Loading Pocket-Ore Pass complex. CONSTRUCTION OF ROTARY DUMP, ORE POCKET AND PASS Introductory

Jan 1, 1976

By Rami Abousleiman, Gabriel Walton, Sankhaneel Sinha

"Although conventional coal mine designs are conservative regarding pillar strength, local failures such as roof-falls and pillar bursts still affect mine safety and operations. Previous studies have identified that discontinuous, layered roof materials have some self-supporting capacity. This research is a preliminary step towards understanding these mechanics in coal-measure rocks. Although others have considered broad conceptual models and simplified analogs for mine roof behavior, this study presents a unique numerical model that more completely represents in-situ roof conditions. The discrete element method (DEM) is utilized to conduct a parametric analysis considering a range of in-situ stress ratios, material properties, and joint networks to determine the parameters controlling the stability of single-entries modeled in two-dimensions. Model results are compared to empirical observations of roof-support effectiveness (ARBS) in the context of the coal mine roof rating (CMRR) system. Results such as immediate roof displacement, overall stability, and statistical relationships between model parameters and outcomes are presented herein. Potential practical applications of this line of research include: (1) roof-support optimization for a range of coal-measure rocks, (2) establishment of a relationship between roof stability and pillar stress, and (3) determination of which parameters are most critical to roof stability and therefore require concentrated evaluation.INTRODUCTIONRecent studies on pillar design have suggested that the assumptions utilized in traditional methods such as tributary area theory (TAT) (i.e. overburden has no self-supporting capacity, infinite pillar array, and CHILE material properties) are invalid in many geo-mining conditions (Esterhuizen, Mark, and Murphy, 2010; Frith and Reed, 2017). Although TAT is conservative with respect to pillar loading, and mine fatalities have steadily decreased since 1990, roof-falls and pillar bursts still occur and injure hundreds of miners per year (Mark, Pappas, and Barczak, 2011). Even though large-scale global mine failure has not occurred in a US coal mine since 2007, the mechanics of global and local stability as governed by the relationship between geologic parameters, mine geometry, and engineering design are still not well-constrained.Numerical methods are a highly effective tool that can be used to gain further insight into these relationships. When using such an approach, calibration to existing empirical relationships is imperative to ensure that numerical model results are realistic. In this study, we utilize the discrete element method (DEM) approach in Itasca’s Universal Distinct Element Code (UDEC v. 6.0) (Itasca, 2010).DEM accounts for explicit separation and contact of individual deformable blocks (Jing, 2003) and captures how discontinuities can affect system behavior. Discontinuous and anisotropic rockmass properties are typical features in coal-measure rock which contain various horizontal (bedding) and sub-vertical (joints) fractures depending on their depositional environment, diagenesis, and historic and current stress states."

Jan 1, 2019

By Ewan Alexander

"As human beings, we have managed risk since the dawn of the ages and have been adept at doing so. In order to survive, we hunted or gathered. If we did not take enough risk, we died. If we took much risk, we died (Fig. 1). As individuals and tribes, risk had to be optimized to maximize our chances to thrive, as individuals and as tribes.In today’s world, the risks are vastly different, but in order to thrive, these must be managed. And no industry knows this as much as mining. In fact, the International Council of Mining & Metals (ICMM) has proposed the Critical Risk Model (Fig. 2) as a means of identifying critical risk, critical controls and associated performance standards. The ICMM focuses on sustainable development performance in the mining and metals industry. It has 23 members, representing some of the largest mining companies in the world.This approach is going to help the mining industry. But it must be applied effectively, with the acknowledgment that the system alone cannot be effective. We can say this confidently, as even companies known for the strength of their risk and safety management systems continue to experience significant incidents, and, in some cases, catastrophes. Why does that happen when all safety metrics, including injury rate, are pointing in the right direction? In the view of the author, it is only when leadership, culture and systems work in complete harmony that the resilience of an organization to manage its significant risk is at an optimal level. It remains an ongoing leadership challenge to maintain that balance and the optimal mindset in the organization. So how do you maintain that special balance?Let’s start with a basic premise. Leadership, supported by simple effective systems, creates culture which creates outcomes. Everyone going home safely is an outcome, as is cost effective operations, and to achieve those outcomes efficiently, the organization must focus on the inputs. And those inputs include effective leadership, effective systems (for the purposes of this article, risk and health, safety and environment (HSE) systems), good planning, stable operations and competent workers. This article will focus on gaining maximum performance from your risk management system."

Oct 1, 2016

By Chunbao Sun, Qi Liu, Chao Wang

Entrainment is a process by which fine and ultrafine particles are transferred to the flotation froth from the top of the flotation pulp, and eventually discharge to the concentrate product, evenwhen they are not attached to gas bubbles. Therefore, entrainment can be considered as a two-step process, one at the upper layer of the pulp to the flotation froth, and the other from froth to the concentrate. Entrainment is inevitable for both hydrophobic and hydrophilic minerals and is one of the significant factors affecting concentrate grade. This paper provides a comprehensive review of the entrainment mechanisms and entrainment models, as well as a summary of the main factors affecting entrainment and the techniques thatmay be used to lower or eliminate entrainment. Based on the review, we point out that selective aggregation of fine and ultrafine gangue minerals using appropriate process aids (polymeric depressants, inorganic salts, etc.) to increase their particle sizes appears to be a convenient and economical method. Directions of further research along this line are discussed.

Aug 31, 2020

By Victor F. Hollister

The great increase in post-World War I1 use of molybdenum was made possible by discoveries of that metal in porphyry molybdenum and porphyry copper deposits. This section documents significant porphyry molybdenum discoveries of the post-war period. The most important discovery was Henderson in Colorado. It is not only one of the world's largest and richest, but it was found by a team of geologists who defined the hood model and tested it successfully at Henderson. Under the leadership of Stewart Wallace, these scientists established a set of criteria for exploration for Henderson-type de- posits that was copied by the industry. The discovery bf vertical cylinder type porphyry molybdenum deposits was less renowned. Boss Mountain in British Columbia and then Mt. Pleasant in New Brunswick were given relatively scant notice, compared with the Henderson discovery. However, these deposits have geometrics distinct from that found in the typical hood, which directly affects their exploration characteristics. Mt. Pleasant, included in this section, is a well defined, near vertical breccia pipe. Both the Henderson and Mt. Pleasant discoveries were made by relatively small groups operating independently of the bureaucracy that characterizes large corporations. The management role in each case was one of encouragement. In addition, Wallace had the beneficial experience of working for Climax, whose objective was the discovery of porphyry molybdenum deposits. Henderson was the natural outgrowth of the exploration effort by those who studied and understood the Climax deposit.

Jan 1, 1991

"Mining used to be a business primarily focused on the technical aspects of getting valuable ore out of the ground and extracting the minerals efficiently. Without denying the importance of these skills, a narrow focus on technical issues is no longer enough to guarantee success when it comes to exploiting rare earth element (REE) deposits. Molycorp failed to enter the global REE market in a successful manner, while none of the many REE exploration projects has turned into an active mine so far and none is expected to commence operations in the near future. Accordingly, the world of REE is far more complex compared to other commodities. This paper looks into the REE industry to identify the factors that can connect potential U.S. REE mines to the market. The ability to break free from past thinking and become future-focused is a key driver. Mining of REE is pointless without a corresponding value-adding chain, while developing a value chain without first establishing an uninterruptible source of REE is also senseless. The mining sector must be based on the REE value chain and vice versa, along with the establishment of a market channel for the REE products that come out of the mine. INTRODUCTION It has been seven years since rare earth elements became the subjects of front-page headlines. It was when the controversial Chinese export policy for these critical commodities was epitomised in a maritime border dispute with Japan in September 2010 that resulted in the big REE crisis and price spike of 2011 (Barakos et al, 2016c; Mancheri, 2015). The world was dismayed, especially in REE-importing countries, such as the United States that was and is still totally dependent on Chinese production and exports (Barakos et al, 2016c; Kennedy, 2015). The short-lived alarm initiated a treasure hunt by way of exploration for REE deposits all over the world. The continuously growing demand on the one hand and the Chinese sovereignty of the REE-market on the other, led the rest of the world to explore their own REE resources. In just a few years, more than 400 projects were initiated to explore REE deposits outside of China (ERECON, 2015; Goodenough, 2016). The prices of REE, however, dropped rapidly and at the moment of writing this paper are in 6-year lows, at the level of the price average before the 2011 crisis (Barakos, 2017). The viability of even major established producers is being challenged, not to mention the development prospects of potential REE-market entrants (Barakos et al, 2016b; Rollat et al, 2016). Production cutbacks and industry consolidation in China impel REE market experts to forecast that prices have already reached their lowest point and have nowhere to go but up (Adamas, 2015; Roskill 2015). Yet, expectations for increased REE prices are limited and drastic changes are unlikely to happen in the near future, as there is still excess supply in the overall REE market (Barakos, 2017). Nevertheless, the low prices of rare earths are not the only reason that potential producers are struggling to enter the global REE market. Among other parameters, the separation of the individual elements seems to be the most important factor, as it is technically challenging and expensive to build and to operate."

Jan 1, 2018

By Erich U. Petersen, W. Dan Hausel, William J. Tafuri, Donald M. Hausen, Douglas N. Halbe

The geology of Wyoming has been compared to some of the richest precious metal producing regions of the world including South Africa, Western Australia, and the Superior Province of Canada. These areas are all underlain by ancient cratons that contain some of the oldest rocks on the surface of the earth. But unlike the other cratons, the Wyoming craton (also termed the Wyoming Province) has been greatly modified by Laramide tectonics which thrust slices of the ancient craton through younger Phanerozoic sedimentary rocks. Unfortunately, the nature of the Laramide tectonics left vast regions of the craton at the bottom of the Tertiary basins unavailable to direct examination, but the exposed slices in the mountain cores contain some of the best exposures of Precambrian rock in the world. The cores of these uplifts contain extensive regions of relatively unmineralized gneiss and granite that include scattered fragmented supracrustal belts formed of metamorphosed volcanic, plutonic, and sedimentary rock. Some of these supracrustal belts exhibit similarities to the gold- and nickel- rich terranes of Western Australia. Yet these areas remain incompletely explored. Archean (> 2.5 Ga) gold deposits within the Wyoming craton are primarily confined to greenstone belts and related terranes. These supracrustal belts include relatively narrow vein and shear zone deposits with strike lengths of tens of feet to more than a mile. Some exceptional deposits possess widths of greater than 15 feet to possibly as much as 300 feet, but the majority have widths of± 5 feet. These belts include Cu, Ag, W, Fe, and Cr mineralization, asbestos and pegmatites, and anomalous Ni and Sri in addition to gold. The Proterozoic terrane (<2.5 Ga) exposed in the cores of mountain ranges in southeastern Wyoming includes a thick miogeosynclinal metasedimentary succession which unconformably lies on the Archean craton. These metasedimentary rocks are separated from a predominantly metavolcanic terrane to the south by a major Precambrian suture, or shear zone. The metasedimentary rocks north of the shear include quartzite-hosted stratabound Cu-Ag-Au deposits, Au-Ag veins, and Witwatersrand-type metaconglomerates with isolated gold anomalies. The suture includes scattered base and precious metal deposits in shear zone cataclastics. South of the shear zone, the metavolcanic terrane includes scattered volcanogenic Zn-Cu-Ag massive sulfide deposits, at least one Cu-Au porphyry, and two large layered mafic complexes. The northern edge of one of these layered intrusives yielded some platinum and palladium to miners at the beginning of the 20th century. Phanerozoic sediments host many precious metal anomalies. Some Au-REE anomalies occur in Cambrian conglomerates. Ag-Cu-Zn stratabound deposits are found in bleached Jurassic redbeds in the Overthrust Belt of western Wyoming. The broad Wyoming basins include many enigmatic gold occurrences and anomalies that can only partially be explained by detrital transport in fluvial systems. Many of these anomalies were probably geochemically transported and precipitated. Rocks of Late Cretaceous age along the flanks of the uplifts have numerous black sand deposits. These paleobeach placers contain concentrations of detrital heavy minerals with anomalous titanium, rare earths, and in some cases gold. Gigantic base and precious metal deposits are associated with scattered composite intrusives in the Absaroka Mountains in northwestern Wyoming. This deeply incised volcanic plateau includes several Tertiary age copper porphyry deposits with significant Cu, Mo, Ti, Pb, Zn, Au, and Ag resources that rival the porphyry districts of the Basin and Range Province. In the Black Hills of northeastern Wyoming, disseminated Au-Th-REE mineralization is found in association with fenitized alkalic igneous rock. In addition to disseminated mineralization-scattered gold, fluorite, rare earth and copper veins; lead, zinc, and silver replacement lodes; and tin pegmatites are found in this region.

Jan 1, 1990

By Roberto Fustos, Gonzalo Nelis, Víctor Sanhueza, René Gómez

Hang-ups are a challenging operational problem in block caving mines. They interrupt ore flow and imply hang-up removal activities, which take time, increase operational costs, and involve safety risks for workers. In block caving, the number of hangup events of mechanical arches that appear in the drawbell could be decreased if the drawbell geometry is adequately designed based on the expected rock fragmentation. Here, we compile and analyze hang-ups reported in several block caving mines to evaluate the impact of drawbell geometry, rock size, and vertical load on hang-up frequency at the mine scale. Results show that the ratios between drawbell length and d80 (dL/d80), between drawbell width and d80 (dW/d80), between drawbell volume and rock volume (VDB/VP), and vertical stress are critical parameters that define hang-up frequency. These findings confirm previous experimental studies, where a decrease in hang-up events is associated with an increase in these ratios. Additionally, these outcomes are used in a support vector machine algorithm to define categories of hang-up frequency. The results of this classification algorithm are presented in diagrams, which can be used to estimate the hang-up frequency in block caving projects.

Oct 15, 2022

By Yongheng Jiang, Wentong Wang, Haoming Luo, Chuanju Liu, Qianjun Zhang, Sha Guo

Rock burst has always been a major problem in deep underground engineering with high stress, and rock burst strength evaluation has become an important research topic. To effectively predict the rock burst hazard in underground rock mass engineering, a cloud model (CM) rock burst intensity evaluation method based on the CRITIC method and order relation analysis method (G1) was proposed in this paper. First, a rock’s uniaxial compressive strength σc, tangential stress σθ, uniaxial tensile strength σt, ratio of uniaxial compressive strength to tensile strength σc/σt (brittleness coefficient), ratio of tangential stress to uniaxial compressive strength σθ/σc (stress coefficient), elastic deformation energy index Wet, and depth of cover H were selected as evaluation indices of rock burst intensity. Ninety-five groups of rock burst measured data at home and abroad were selected, and the objective weight and subjective weight of each index were calculated by using the CRITIC method and G1 method, respectively. The comprehensive weight was determined according to the combined weighting method of game theory, and the sensitivity of each evaluation index was analyzed. By utilizing a forward cloud generator, the membership degrees of different rock burst grades were calculated, and then the rock burst intensity grades of the samples were evaluated and compared with the evaluation results of the CRITIC-CM method and G1-CM method and the actual grades. Finally, the rock burst classification ability of the model was analyzed. To better verify the accuracy and reliability of this model, the rock burst case of the W39 line in the Chengchao Iron Mine was analyzed by using this model. The research results show that the rock burst evaluation results based on CRITIC-G1-CM are basically consistent with the actual rock burst grade, and the rock burst intensity grade evaluation model has good practicability and reliability.

Sep 1, 2023

Caterpillar recently held two, two-day demonstration programs for its mining customers. The event, billed as MineDemo by Caterpillar, consisted of two sessions held on consecutive weeks at the company&apos;s Tinaja Hills proving ground south of Tucson, AZ. The program included several classroom sessions that focused on Caterpillar equipment applications, including the VIMS (vital information management system) and the CAES (computer-aided earthmoving system). Also included were field demonstrations and the opportunity to test drive mining-related heavy equipment, including dozers, trucks, graders, shovels and loaders. Featured at the event were the recently upgraded 785, 789 and 793 C-Series trucks. Caterpillar recently announced the availability of the 136-t (150-st) 785C and the 177-t (195-st) 789C. The upgraded haulers have replaced the respective B-Series models. The 218-t (240-st) 793C was introduced in 1996. It, too, has been upgraded but retains the C-Series designation. While attending the press event, the author had the opportunity to test drive the 793C at the Tinaja Hills test site. It was amazing how well the machine handled. The operation was smooth and the braking system was precise. The cab was extremely comfortable. To see a C-Series truck in action, the author also visited Newmont Mining&apos;s Mesquite Mine, located in Cali¬fornia, across the border from Yuma, AZ. The Mesquite Mine operates a new model 785C truck. At the mine, temperatures have been measured as high as 58° C (138° F) in the pit. Needless to say, the ability to operate dependably in extreme heat is an important consideration for the mine operators. An interview with the driver and later with management confirmed that the 785C has worked out well. The driver praised the comfort of the cab and the ease of operation. Management reported significant fuel savings and was impressed by the truck&apos;s maintenance features.

Jan 1, 1999

By R. A. Matuszak

In recent years, a new concept in the control of electrically powered excavators has come into existence. The new type of control system has come to be known as "static" control. The use of the name "static" to describe this system is somewhat misleading since this term refers only to one of the many advantages of this very important advance in excavator control systems. In 1959, the first truly "static" control for Ward-Leonard equipped electric excavators was designed, developed and placed in service. The control system, originally intended only as a more modern electronic type of alternate to the tried and proven rotating amplifier control system then in use, has since proven to be much more.

Jan 1, 1964

By M. Hakan Morcali, Onuralp Yücel, Haldun Gürcan, Serdar Aktas, Semih Özbey, Alper Keskin

"This work presents a method for the precipitation of cobalt sulfate by alcohols, specifically ethanol and methanol. The effect of the initial concentration of cobalt, the volumetric ratio of alcohol to cobalt sulfate solution, the addition of sulfuric acid and ammonia, and the effects of common ions on the precipitation percentage were investigated. The performances of ethanol and methanol were compared in terms of the precipitation percentage of cobalt sulfate, and explanations for different performances are offered. In the sulfate-based solution, the alcohol was shown to displace water ligands from the first coordination sphere of the cobalt(II) cations, which led to the precipitation of the cobalt ions as cobalt sulfate heptahydrate. SEM analysis revealed that the particle sizes of the powders produced by this method are smaller than those of commercially available cobalt sulfate. The scientific literature contains no data on the solubility of cobalt sulfate in ethanol. In this study, the solubility product constant (Ksp) for cobalt sulfate was experimentally calculated to be approximately 1.15 x 10-5.IntroductionCobalt sulfate, which is one of the most important compounds of cobalt, is used in the electroplating and electrochemical industries. The addition of cobalt sulfate to nickel-plating baths makes the treated metals brighter, harder, smoother and more ductile (Armstrong et al., 1988). It is also used as a desiccant for lithographic inks, varnishes, paints and linoleum, as well as in storage batteries, e.g., nickel-cadmium (Ni-Cd) and lithium-ion (Li-ion) rechargeable batteries (Kang et al., 2010). Cobalt sulfate is employed as a coloring agent in ceramics, enamels and glazes to prevent discoloration and as a copigment for the decoration of porcelain. In addition, cobalt sulfate has been used in animal feeds as a mineral supplement (Budavari et al., 1996; Kirk and Othmer, 1999).In the past, brewers used cobalt sulfate to prolong the life of beer foam (Kesteloot et al., 1968). Ranchers have dosed livestock with cobalt sulfate or used fertilizer enriched with this mineral to ensure that their animals obtained sufficient amounts of the trace mineral, which is essential to the production of vitamin B12. Cobalt sulfate has also been used in veterinary medication to prevent and treat cobalt deficiency in ruminants, which causes a reduction in feed intake and body weight, accompanied by emaciation, anemia and debility.Cobalt sulfate is a water-soluble bivalent cobalt salt. Cobalt sulfate heptahydrate dehydrates entirely at 420° C, and the dehydrated salt forms red monoclinic crystals."

Jan 1, 2015

By Daniel R. Stewart

The function of the geological engineer is to assist in mine planning and operations by collecting, interpreting, and applying geologic data to the solution of engineering problems. The geologist supports this effort by collecting additional geologic information specifically useful to the engineer. This use of geologic information reinforces the value of mine geology to the mining process beyond the traditional role of orebody definition. Work discussed includes: evaluation of caving strategies at the Climax and Henderson mines; support definition and slope stability at the Climax mine; and some uses of geology in cavability estimation for the Mount Emmons project.

Jan 1, 1983