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By Kevin W. Cargill

In September 2004, Hurricanes Frances and Ivan caused the Pigeon River in western North Carolina to flood. This flooding eroded the embankment below Interstate 40 (I-40) and sent one of the eastbound lanes, along with the roadway shoulder, into the river below the embankment. North Carolina Department of Transportation (NCDOT) needed to reopen all the lanes of I-40 as soon as possible and considered this damage to be an emergency situation. NCDOT contracted Schnabel Foundation Company to design and build a repair that would keep this important interstate open and reestablish the eastbound lane. The obstacles included limited work room, the requirement of keeping the remaining lanes of I-40 in service, and producing a final product that would be relatively maintenance free and last at least 100 years. The proposed repair had to consider that the existing interstate was founded on a rock fill that was constructed from rock blasted off the adjacent mountain side. The selected design included two, tied-back micropile walls to address these obstacles and other issues. Each of the walls were constructed of 10.75 inch diameter micropiles and corrosion-protected tieback anchors installed through the existing rock fill into competent bedrock, concrete wales, and a reinforced shotcrete facing. This successful project was completed during the coldest months of the year and within the timeframe established by the State of North Carolina. This paper will discuss the design and construction of the repair and the many challenges that had to be overcome.

Jan 1, 2006

By Edward Halse

THE occasional occurrence in metalliferous veins of rounded fragments of rock, matrix or ore, lying loose, embedded in clay, or enclosed in some kind of cement, may be attributed to four causes:¬ I. They have been washed in from the surface, or from an upper portion of the vein. II. They are of concretionary origin. III. They have been produced by movements in the country-rock or in the walls of the vein. IV. They have been found in situ, by the upward, downward or lateral flow of water in the vein itself. In this paper the word " conglomerate " is confined to a rock composed of rounded fragments or pebbles cemented together, as distinguished from a " breccia," in which the rock-fragments are angular. I. BOULDERS AND PEBBLES WHICH HAVE BEEN WASHED IN FROM THE SURFACE, OR FROM AN UPPER PORTION OF THE VEIN. In this type it is presupposed that the vein at onetime com¬municated by a fissure or open space with the surface, or with the upper portion from whence the fragments have been washed. One well-authenticated occurrence was described long ago by Fournet. Owing, no doubt, to later dislocations in the lode, pebbles from an old alluvium and sands containing titaniferous iron, as well as fragments of wood, were found in a vein at Huelgoët, in France. "Toutes les parties tendres du filon de Pranal ou ces pédnomènes sont les plus prononcés ont été excavés jusqu'a d'assez grandee profondeurs par l'impétuosité des torrents, qui ont deposé la matière alluviale."1

Jul 1, 1905

By C. F. McCarroll

The effectiveness of an industry's safety activities can be gaged best by the accident records of that industry. In an effort to gage conditions in the petroleum industry, and with the objective of helping to reduce the number of accidents in it, the Bureau of Mines from time to time has tabulated, analyzed, and published pertinent statistical information.3/. These reports have dealt with distribution, causes, and costs and related phases of accidents for various and collective divisions of the petroleum industry in several sections of the country. This type of study aids the personnel of the Bureau in planning the course of its activities in accident-prevention work and gives useful data to persons engaged or interested in the promotion of safety in the petroleum industry, which will aid them in their efforts to reduce the number and severity of accidents. A majority of petroleum operators and "service? contractors have acknowledged their responsibility to provide their employees with safe working conditions and to their stockholders for greater economic value of invested capital by establishing safety divisions within their respective organizations. Such divisions have a primary duty, namely, to see that properly designed and guarded machinery and working equipment are furnished the employees and that they are trained in the safest practical methods of performing their work. Some companies and individual operators, however, have shown little or

Jan 1, 1939

By Neville Slade, Doug Shumway, Dayan Anderson, Joe Siefke, Curtis James

The Mojave Desert is a particularly fragile ecosystem that faces several significant impacts. These include rapid housing development, overdrafted water supplies and loss of wildlife habitat — all a result of mining, industrial activity and urban sprawl. During the past three years, a diverse group of educators, natural resource managers and business leaders was assembled under the auspices of a local community college. This group’s goal was to provide unique natural resource education opportunities for the region.

Jan 1, 2005

By C. B. Kenahan

The Bureau of Mines is developing methods for reclaiming the metal and mineral values contained in municipal incinerator residues. This report describes the first phase of the research, in which reliable methods for sampling and analyzing municipal residues were established and the composition and characteristics of the residues were determined. Samples were obtained from a variety of grate-type furnaces and also from a rotary kiln furnace. The samples were processed on a batch basis and separated into their natural categories by a variety of methods including screening, magnetic separation, air separation techniques, and handpicking. The main components of the residues were determined to be metal and metal oxides, glass, and ash.

Jan 1, 1968

By Taylor R. G

This paper reports a biogeochemical study of the Siberia lode of the Herberton tin field. Soil near the orebody contained high levels of Fe, Cu, Pb, Sn, As, Mld Mn. Polycarpaea spirostylis and Indigofera dominii were associated with these high levels but several other species apparently could not tolerate them. The potential of these species as indicator plants is discussed.

Jan 1, 1975

By Brian Gar Wingfield

"The introduction of the QuarryMan laser profile system in 1987, along with the development of the corresponding 3-D software, gave a qualified operator pertinent information about dimensions of quarry highwalls, pattern and hole loading design, stockpile profiles, etc . . . Attributes helpful for this endeavor included surveying, computer, and blasting knowledge. Since not all operators had theseskills, a simpler model, the QuarryAce, was designed to look a t highwall dimensions in 2-D view . Al though less sophisticated than the QuarryMan instrument and its software, it is simpler to instruct in its use and has the ability to determine burdens at different depth levels . An in-house user f r i e n d l y computer program was designed to utilize QuarryAce depth vs. burden data . This program was created to enable laser and computer novices to generate information useful to the everyday blaster."

Jan 1, 1992

By T. Y. Chong, J. A. Folinsbee, M. Fullam

PJV Dome Mine has used some form of gravity concentration since start of milling operation in 1909 to recover free milling gold. Amalgamation and conventional jigs were first used and were replaced with the Knelson Concentrators in 1993. The Knelson concentrates produced were upgraded on a conventional shaking table prior to smelting and refining into gold bullion. In May 2002, a comprehensive review of the latest gravity recovery technology led to a piloting campaign aimed at further improving gravity recovery. The Knelson concentrates, subjected to intensive cyanide leaching in an Acacia pilot plant, were found to be amenable to intensive cyanide leaching with over 98% of the gold being dissolved within 24 hours. An Acacia Intensive Leach Reactor was successfully installed and commissioned in December 2002, to replace the shaking table. his paper describes pilot scale testing, installation, commissioning and optimization of the Acacia Intensive Leach Reactor. Also, the economic impacts on down stream processes are highlighted.

Jan 1, 2005

Beneficiation of Coal Fines from Tailing Ponds of Tuntbilek Washing Plant

Sep 13, 2010

By A. S. Macfarlane

Mineral resource management (MRM) practice has developed in South Africa over the course of the last ten years, with the purpose of integrating previously isolated technical functions into a value chain aligned, process organization, responsible for mine planning and optimization. The implementation of MRM within various companies has met with varying degrees of success, often resulting in incremental improvements in the planning process and, conversely, often becoming the scapegoat for poor delivery on plans and projects. The reason for this has been, amongst others, a lack of a suitable metric to define the success rate of MRM in the business at hand, in terms of its contribution to the bottom line. This paper is the result of extensive research by the author into this subject, which has resulted in the conclusion that economic value added is an appropriate measure that will lead to real optimization and value creation in mining companies, if applied within a new, holistic model

Jan 1, 2006

By M J. Daniel

Mineral resources all over the world are often heterogeneous and have variable ore properties and ore grade. As a result the ore processed in concentrating plants varies over the life of mines. Consequently the circuits often suffer from bottlenecks typically at the stages of crushing, semi-autogeneous (SAG) and ball milling. Bottlenecks may be remedied with equipment retrofits, however, design engineers should consider a phased approach to the circuit design that delays initial capital expenditure over the life-of-mine. This paper deals with the debottlenecking of existing mineral processing plants by means of high pressure grinding roll (HPGR) applications. It also deals with the use of innovative flow sheet designs using HPGRs for the design of Greenfield plants by engineering or mining companies. In the case of Greenfield plant design an analysis with respect to energy efficiency and operating cost (OPEX) is presented. The analysis compares the performance of SAG based circuits against HPGR circuits that may be influenced by variable ore properties. Globally about 600 HPGRs are installed in various applications in the cement and minerals industries. In excess of 100 of these HPGRs are used since the mid 1980s for crushing and grinding of various ore types including æhard rockÆ applications. HPGR technology is mature enough to be considered as an ideal debottlenecking device. HPGRÆs are versatile, they have a low installation footprint and they are flexible in its machine settings (pressure, roll speed), which can be adjusted to react to ore variations whilst maintaining a high throughput. Examples for the benefits of using HPGR in terms of energy efficiency and operating costs are presented by this paper. æEco-efficientÆ flow sheets and sustainable development initiatives are linked to energy savings as an æenergy costÆ and benefit to the environment. Energy savingsÆ can also be analysed in terms of the ædollar costÆ (OPEX) savings. This paper demonstrates that HPGR is more energy efficient and may reduce the overall grinding energy requirements in the order of 16 per cent depending on the target grind size and ore properties. The HPGR is more cost efficient and may reduce overall grinding costs by as much as 19.3 per cent depending on the cost of energy, grinding media and the rate of grinding media wear in the comminution circuit.

Jan 1, 2009

By J Pric, M Fulton, C Xia

A cyanidation study was conducted on a mild refractory gold ore sample from the Central zone of Clarence Stream Property, owned by Freewest Resources Canada, to develop a leaching strategy to extract gold. Gold, at a grade of 8.00 g/t, is present as native gold, electrum and aurostibite. The ore also contains 2.8 per cent pyrrhotite, together with several antimony minerals (0.8 per cent berthierite and gudmundite, 0.18 per cent native antimony and stibnite). It also exhibits weak preg-robbing properties with 0.16 per cent organic carbon. Aurostibite, a gold antimony compound, is particularly known to be insoluble in cyanide solution. The antimony dissolves in cyanide solution to form antimonates, which retards gold dissolution. Industrial practice of extracting gold from aurostibite generally consists of producing a flotation concentrate, which is leached in a pipe reactor at low alkalinity and high oxygen pressure with about 20 g/L cyanide. The proposed new approach is efficient and allows the extraction of gold directly from an ore at atmospheric pressure and a low cyanide concentration at pH 10.5. The effects of grinding, pretreatment, lead nitrate, kerosene and cyanide concentrations have been investigated. The maximum gold extraction obtained on the ore was 87.9 per cent using 800 ppm NaCN, 500 g/t lead nitrate, 30 g/t kerosene, DO 10 ppm and pH 10.5 in 168 hours. The associated cyanide consumption was 1.3 kg/t. The additions of lead nitrate and kerosene increased gold extraction. In comparison to a P80 of 74 ¦m, a P80 of 30 ¦m significantly increased gold extraction. Gold in solid solution in gudmundite and arsenopyrite was believed to be responsible for the unleached fraction until mineralogical analysis of hydroseparation concentrates of leach residues showed that most of the unleached gold occurs as aurostibite, either as locked grains in sulfides/sulfarsenides or as grains with passivation rims of an Au-Sb-O phase. Coarse gold was also found. Gold extraction was not sensitive to cyanide concentration from 250 ppm to 1200 ppm NaCN and high pH was detrimental. Decreasing the cyanide concentration reduced the cyanide consumption to 0.85 kg/t. The removal of coarse gold using a Knelson concentrator and a Mosley table prior to leaching increased the gold extraction to 90.4 per cent (leach residue at 0.77 g/t).

Jan 1, 2007

By Elli Nurminen

In this work the thermodynamics of the metallic sulphate decomposition reactions were studied through thermodynamical calculations and thermogravimetric methods. The decomposition temperatures and mechanisms were determined for cupric sulphate, ferric sulphate and also for industrial flue dust from a copper flash smelting process. The aim was to determine the thermodynamic conditions for sulphate decomposition and to estimate whether the reactions are kinetically likely to take place in the flash smelting process heat recovery equipment. The information is essential in CFD-modelling of the reactions taking place in the boiler and for optimising the process.

Jan 1, 2006

By Fahimeh Dehghani, Louis Ackah, Tathagata Ghosh, Justin Godbold, Jia Liu, Meisam Peiravi, Manoj Mohanty, Azam Baharlouei

Primary economical deposits of rare-earth elements (REEs) are exhausting all over the world, and it has become necessary to find new sources and methods for their extraction. In addition, increasing the application of REEs in modern technological society has increased its demand globally. One of the important movements to compensate for the future shortages of critical metals is the recovery of REEs from recyclable materials. This paper presents a review of the classification and extraction methods, as well as general applications of REEs with emphasis on secondary sources such as coal and coal byproducts, iron ore tailings, apatite, and phosphate byproducts. An overview of the current state of knowledge on the various methods of REE beneficiation and extraction is covered. These methods include physical separation, as well as hydrometallurgical and bio-hydrometallurgical techniques. The application of these REE extraction techniques for enhanced recovery has been driven primarily by the unique industrial application of these important elements. This paper further explores the existing and potential environmental challenges associated with REE extraction. The authors have presented a wide array of literature, in-depth discussion of the subject, and a succinct summary of processes and relevant case studies.

Sep 23, 2020

By L. A. Updegraff

Before discussing the application of capacitance for the measurement of moisture content in a moving stream of coal it might be well to first give a brief description of the process and then show how it can be applied to the coal industry. A capacitor may be described as a device having two conductors separated by an insulator, the conductors hereafter being designated as a test cell or test plates and the insulator as the dielectric. Capacitance, therefore, is a measure of the ability of a capacitor to store an electrical charge. Two basic factors that affect capacitance are the dimensions of the capacitor and the dielectric constant of the insulator. Capacitor dimensions which affect its capacity are the area A of the conductive surface, and the distance d between plates. Capacitance is inversely proportional to the distance between plates and directly proportional to area A, so if capacitance is indicated as C and the dielectric constant as K the equation for capacitance would be C = AK/d. The dielectric constant can be described as the ratio of the actual capacitance of any given material to that of a vacuum, which is unity. In industrial applications the area of the plates remains constant as also does the distance between them, leaving the dielectric constant as the only variable to affect the capacitance measurement. Figure 1 is a schematic diagram of an r-f excited capacitance bridge in which a test cell is part of the circuit. This bridge consists of four capacitors in two pairs connected across an a-c voltage source. In one side of the circuit the two capacitors are fixed but in the other side they are variable, one being the rebalance capacitor operated by the servo motor and the other the test plates between which the dielectric passes. Capacity of the plates is a function of the dielectric constant of the material between them and is measured at radio frequency. Within the recording instrument is an r-f oscillator and a 60 c ps modulator. The radio frequency signal is generated by the oscillator, modulated by a 60 cps wave, and sent to the bridge. Therefore the signal entering the capacitive bridge is a radio frequency carrier with a 60 cycle envelope, If the bridge is in balance as the signal enters there would be no voltage drop and so no output by the detector. As long as the dielectric constant remains the same the bridge will stay in balance. However, any change in the dielectric constant, which in this case would be a change in moisture content, would affect the bridge. Higher moisture increases the capacity of the test cell which causes less voltage to develop across it causing imbalance of the bridge. This in turn causes a radio frequency signal to appear at the detector. Output from the detector is a 60 cycle ripple which is in proportion to the imbalance of the circuit. A 60 cycle amplifier boosts the detector signal to enough power to drive the servo motor which positions the recording pen and also rotates the variable capacitor, to which it is mechanically connected, to bring the bridge back in balance. An increase in moisture causes the servo motor to rotate in one direction, but a decrease causes imbalance in the opposite direction, and thus rotates the motor in that direction. This brings the bridge back in balance and stops the motor. The bridge shown in Figure 1 has been modified so as to provide a wide range of adjustments. Coarse and fine span adjustments located in the recording instrument are set to govern the amount of pen movement for a given change in capacitance. A measuring head unit contains coarse and fine zero adjustments for

Jan 1, 1961

By Susumu Uchiyama

This machine was manufactured for excavation of the Roppongi station of the Tokyo Metro Line 12. This machine can excavate both the platform and the rail track at the same time in locations where the traffic is congested and has following features: A multi-centered TBM of the size of 7.06(H) x 13.18(W) m The world first H&V TBM, with right and left machine parts articulated vertically and separately for position control A large erector for simultaneous erection of column and central segments of special shape to construct a highly reliable tunnel This paper reports the design concept, construction, and work record.

Jan 1, 1999

By Donald W. Baggs

This report describes economic mining feasibility studies conducted by the Bureau of Mines to estimate mining costs in the Porcupine mining area of the Juneau Mining District, southeastern Alaska. Investigations were conducted on the economics of three mineral deposit types: 1) massive sulfide deposits containing zinc, copper, and silver, 2) vein gold, and 3)disseminated gold. Cost estimates were developed using the Bureau of mines Cost Estimating S,-stem. Discounted cash flow rates of return were calculated using the Bureau of Mines MINSIM (mining simulation) computer program. Three sets of metal prices were used in the study based on recent historical price information. Underground longhole stope mining of a massive sulfide deposit containing 25 pct zinc. 1 pct copper, and 63.6 g/mt silver was found to be economic at high metal prices at a quantity of 13,200,000 mt ore. Cut-and-fill mining of a 26,400,000 mt massive sulfide deposit was found to be economic at medium metal prices. Open pit mining of a similar deposit was found to he economic at medium metal prices and 26,400,000 mt ore, or at high metal prices and 6,600,000 mt ore. Underground mining of a vein gold deposit was found to be economic at a grade of 17.1 g/mt medium metal prices and 1,320,000 mt ore. Open pit mining of a disseminated gold deposit was found to be economic at a grade of 1.71 g/mt medium metal prices and a quantity of 39,600,000 mt ore.

Jan 1, 1986

By R A. Pax, B Cornish

Increasing the throughput of the MMG Century operation by over 25% from past practice to preserve cash flow close to the end of life of mine has revealed new throughput and load dynamic instabilities in the SAG mill causing significant time averaged loss of production. A twelve microphone array around the SAG mill (Pax, 2014) using the non-contact acoustic measurement methodology (Pax, 2011, 2012) has been used to diagnose the new dynamics. Dynamic acoustic noise signal information allows discrimination of the behaviour of the steel balls and the rock. Determination of mill load, toe and shoulder angles, water holdup, and proxies for mill load are possible.The instability was diagnosed with the help of an abnormality in the liners/lifters of the SAG mill with one row of lifters having a slightly increased in-mill life compared to the rest. The steel shoulder angle is observed to be disturbed cyclically at a rate of precisely one revolution at low throughputs of 750 t/h. However, at throughputs closer to 1100 t/h, the cyclic signal disappears indicating additional dynamics to randomise the repetitive behaviour of the mill charge. The cyclic signal has been used to operate the SAG mill with improved stability at 1100 t/h by adjusting the feed water addition rate.This paper presents and discusses these results and proposes the suggested origin of the extra dynamics. A small consistent aberration of the lifters circumferentially provides a useful detector of stable mill operation and a novel sensor for the dynamics of the internal operation of a SAG mill.CITATION:Pax, R A and Cornish, B, 2015. A novel measurement for the internal operation of a semi-autogenous mill using acoustic sensors – a case study, in Proceedings MetPlant 2015, pp 120–128 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 7, 2015

By K. Szafran, R. E. L. Seal, M. Tansey

Conversion of hydraulic equipment to fire resistant fluids has been hampered by less than satisfactory component performance and in some cases, catastrophic equipment failure. Concern over identifying possible causes to these problems led to a joint research project between the Potash Corporation of Saskatchewan Mining Limited and the University of Saskatchewan. This paper summarizes some of the results and conclusions derived from this joint project. In this study, the research was limited to evaluating the effects of potash contamination on the performance of hydraulic equipment. Two separate types of tests were conducted in order to provide a basis upon which trends could be established. This study concluded that the presence of potash dust in the hydraulic fluid can induce severe wear over relatively short periods of time. It was also deduced that a contaminant free fluid combined with proper fluid maintenance could extend the performance of hydraulic components using fire resistant fluids even under very severe operating conditions, such as elevated pressures and temperatures. Recommendations as to how to achieve this goal and the practicality of doing so are presented.

Jan 1, 1988

By D. F. Scott

Seismic tomography, as used in mining, is based on the principle that highly stressed rock will demonstrate relatively higher P-wave velocities than rock under less stress. A decrease or increase in stress over time can be verified by comparing successive tomograms. Personnel at the Spokane Research Center have been investigating the use of seismic tomography to identify stress in remnant ore pillars in deep (greater than 1220 m) underground mines. In this process, three-dimensional seismic surveys are conducted in a pillar between mine levels. A sledgehammer is used to generate P-waves, which are recorded by geophones connected to a stacking signal seismograph capable of collecting and storing the P-wave data. Travel times are input into a spreadsheet, and apparent velocities are then generated and merged into imaging software. Mine workings are superimposed over apparent P-wave velocity contours to generate a final tomographic image. Results of a seismic tomographic survey at the Sunshine Mine, Kellogg, ID, indicate that low- velocity areas (low stress) are associated with mine workings and high-velocity areas (higher stress) are associated with areas where no mining has taken place. A high stress gradient was identified in an area where ground failed. From this tomographic survey, as well as four earlier surveys at other deep underground mines, a method was developed to identify relative stress in remnant ore pillars. This information is useful in making decisions about miner safety when mining such ore pillars.

Jan 1, 1996