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By George Hope, Brigitte Lacouture

"The Red Dog mine has increased mill throughput most years since start-up. Although flotation equipment has been added over the last 10 years, the Red Dog metallurgical performance has been restricted by a lack of adequate flotation capacity. Two reduced tonnage trials conducted in 1997 as well as numerous SAG relines have consistently indicated the potential to significantly increase both zinc concentrate recovery and grade with additional flotation capacity. Later in 1999, a new circuit was designed with increased flotation capacity while simplifying the current circuit, providing for three stages of dilution cleaning, and creating a retreat section. The purpose of the retreat section is to target the more complex particles and allow the chemical environment to be fine tuned for improved iron depression. In total, 21 Outokumpu OK50 (50 m3) mechanical flotation cells and four 3.66 mØ column cells were added to the current flotation circuit. The VIP (value improvement program) mill optimization project is also addressing thickening, water treatment, and power generation issues and has a total budget of US$105 M. Start-up of equipment was phased in to minimize the impact on current operations and the project was completed by the end of 2001. IntroductionRed Dog Operations started production in November 1989. The mine is located above the Arctic Circle in northwest Alaska. It is linked by an 80 km road to a port-site facility where the concentrate is stored. Concentrate is shipped to markets throughout the world during the one hundred days of open seas. As of January 2002, the Red Dog main pit had 38.4 Mt of reserves grading 19.2% Zn, 5.3% Pb, and 102 g/t Ag. Additional reserves and resources contribute an additional 72 Mt at 15.6% Zn, 4.2% Pb, and 78 g/t Ag. Red Dog is a Mississippian to Permian, black shale-hosted, zinc-lead-silver deposit located in the DeLong Mountains, western Brooks Range, Alaska. All the rocks associated with the mineralizing event are considered to be part of the exhalite rock package. Silicification was a dominant component of the mineralizing event and the host shale has been silicified and locally resembles a chert. The major sulphides in decreasing order of abundance are sphalerite, pyrite, marcasite and galena. Most of the deposit’s silver occurs within the crystal structure of the galena. The dominant ore mineral, sphalerite, is very fine grained to amorphous and is commonly intergrown with silica. Ore textures are massive, fragmental, chaotic, veined and rarely show classic sulphide sedimentary layering. The upper portion of the orebody has been physically and chemically weathered. Oxidation has altered the sulphides to sulphates. The zinc and iron sulphates are very soluble and are readily depleted from the weathered cap, while the lead sulphate is residual and is, therefore, enriched."

Jan 1, 2003

This study was conducted to establish the effects of a diesel particulate filter (DPF) system with sintered metal substrate on the concentrations and size distributions of nano and ultrafine aerosols and concentrations of nitric oxides in underground mine air. The study focused on the formation and transformation of nucleation mode particles in mine air under prevailing test conditions. Experimental work was conducted in the NIOSH Diesel Laboratory at the Lake Lynn Laboratory experimental mine, a facility developed to allow evaluation of control technologies directly in underground conditions. The DPF system was examined for four repeatable steady-state engine modes using a naturally aspirated mechanically controlled Isuzu C240 diesel engine fueled with ultralow sulfur fuel. The engine coupled to an eddy-current dynamometer was operated in the underground drift with tightly controlled ventilation. Measurements upwind and downwind of the exhaust system discharge were used to quantify the effects of the DPF system on the mine air. A baseline was established using a standard muffler. The study showed that sintered metal DPF systems reduced the total mass of aerosols in the mine air by more than ten-fold when compared to a muffler. The nucleation mode aerosols (50dem<40 nm) in mine air were found to be strongly influenced by engine operating mode. The concentration of nucleation mode aerosols was found to be significantly higher for high-load modes than for low-load modes. The muffler and DPF system resulted in comparable total nitrogen oxides (NOx) concentrations. However, the nitrogen dioxide (NO2) fraction of the total NOx was found to be substantially higher for both systems for low-load modes than for high-load modes.

Jan 1, 2009

By J. W. Wilson, P. C. Graham

SUMMARY The Witwatersrand quartzites in which South African gold mining operations are moat exclusively conducted, are notoriously difficult and costly to drill. Despite this situation, however, with the high cost of developing new mines and extending existing mines, together with the rising cost of labour and mining problems resulting from the ever-increasing depths of workings, the demand for raise-boring in these formations is increasing rapidly. Not only is the demand for raises and shafts increasing, but also the length and size of these excavations. Raise-boring studies carried out in South African gold mines have indicated that increased penetration rates and possibly reduced costs could be obtained if higher thrusts were available at the reaming head. Until fairly recently there has been no raise-boring machine suitable for underground use that possessed the thrust and torque characteristics necessary to achieve high penetration rates in hard abrasive quartzite formations and the cutters available were not really developed for high loading. In response to these requirements a raise-borer, the Robbins 83R was designed and built in Seattle, U.S.A. for the Anglo American Corporation. This machine is operating in South African gold mines and is currently being used at a depth of 12 000 ft below surface in one of the. Group&apos;s mines. The initial raises bored have substantiated that increased penetration is attainable at high thrust and it is now apparent that the machine is sufficiently versatile to drill raises of up to 12 ft in diameter in quartzite formation over a length of 2 000 ft.

Jan 1, 1974

By Steve Kral

After years of cutbacks, closures and layoffs, the mining industry is beginning to expand again. Metals prices are up and so is investor interest and confidence in the industry. Gold prices began to slowly move up in January2003 and finally cracked the $12.86/g ($400/oz) mark in early December. Silver, too, is up, as is copper. So the mining industry is feeling good about itself again and many companies are expanding existing mines and developing new ones. One side benefit to mining’s improved outlook is that companies are beginning to send more of their employees to industry conferences. Such was the case at the109th Northwest Mining Association meeting in Spokane, WA. The meeting was held in early December and attracted 1,100 attendees and 84 exhibiting companies. That is up from 2002’s attendance of about 900 people and 65 exhibitors. The theme was “A Partnership into the Future.”

Jan 1, 2004

By J. B. Oosthuizen

Mechanical rock breakers are used in block caving operations to reduce the size of ore fragments which are too large to pass through grizzlys at the load-haul-dumper tipping points. Several layouts of grizzly, rock breaker and ore pass are possible. The authors evaluated three different layouts at the Premier Mine Division of De Beers Consolidated Mines. The first layout consisted of a 15m surge bin before the breaker, which was located 15 m below the production level. The second layout had a 43 m longs urge bin, with the breaker located 43 m below the production level. The third layout did not have a surge bin, the breaker was located on the production level and operated at the tip. The ore throughput, availability and utilisation, delays, costs and operational experience with each system are discussed. It was found that the rock breakers did not represent a bottleneck in the ore transfer system and a surge bin did not significantly improve the production capacity. The mine has decided to make use of rock breakers situated on the production level, breaking rocks at the tip.

Jan 1, 1997

The modern theory of sampling of particulate minerals essentially consists of a recent generalization of the procedures for applying and calibrating the formula usually known as ?Gy?s Formula? for sampling variance control, in which the central concept is a parameter called the liberation factor l. A model which can be experimentally adjusted was proposed by one of the authors several years ago, based on geostatistical considerations. This new model, which relates the liberation factor to the sizes of the fragments and mineral grains, solves the usual difficulties faced in the past, and permits predictions that are well verified in practice. Unfortunately, an older, arbitrary and less general formula is still widely used. The vast majority of today?s misapplications of Sampling Theory of Particulate Materials can be traced back to the use of this antiquated and generally incorrect model. Following a brief history of the models used for the liberation factor and a description of its main variable, the liberation size, and to illustrate the importance of proper modelling of l, this paper presents demonstrative calculations of the absurdity of the incorrect model using the particular case of gold mineralization as an example, followed by some more positive examples of application.

Jan 1, 2002

By J. Jonas, J. M. Harrington, K. Wangerud, S. D. Fundingsland, J. G. Harrington

EPA NRMRL Mine Waste Technology Program and Region VIII Superfund office are jointly conducting an in-situ technology demonstration at the Anchor Hill Pit Lake, Gilt Edge Mine Superfund site. The goal is to develop in-situ treatment cost/performance data for potential application in long-term water treatment/management at Gilt Edge and similar sites. The pit contained 77,000,000 gallons of pH 3water with elevated metals, sulfate, and nitrate. The Green World Science® patented process for in situ treatment was implemented to isolate and sequester metals; create stable long-term water quality and restore a sustainable ecosystem. COCs have decreased more than 99%, and dissolved discharge standards were attained.

Jan 1, 2004

By S. Benedict Levin

In the spring of 1944, during the emergency In the supply of strategic mica, the Bureau core-drilled six aggregating 913 feet, at the Blister mica Trim. Cheshire County, N.H. These holes indicated a downward extension or the mica shoot which was being mined at that time and developed information essential for economic mining of the deposit.

Jan 1, 1949

By Randy Clarkson

"Free gold particles occur in many base metal and precious metal mines throughout the world. Occasionally mine operators are unaware of the presence of free gold particles in their ores because they have not seen free gold hand specimens or at the working face of the mine.Due to the high density and malleability of gold, large circulating loads of free gold particles can build up over time in grinding circuits. This gold is often deposited in unintended traps throughout the mineral processing system.These unidentified free gold deposits represent a serious security risk as well as inaccessible inventory of gold. Deposits of free gold particles often remain undetected by mine management until they are accidentally discovered while repairing mill equipment. The trapping and subsequent release of gold particles can frustrate attempts to calculate accurate metallurgical balances.Nuclear tracers have been used to determine the free gold recovery efficiency of gravity recovery equipment, drills, and sampling equipment (Clarkson, 1994, 1997, 1998, 1999 and Walsh, 1986, 1992). In 1995, the author used radiotracers to locate and eliminate gold traps at La Mine Doyon (Clarkson, 1997). In 1998 and 2001, the author also salted mineral processing circuits at Royal Oak's Pamour Mine in Timmins (Clarkson, 1999) and at Gold Corp’s Red Lake Mine in Ontario with radioactive gold particles.The gamma and X-ray radiation from gold's nuclear isotope (Au198) were detected through steel, in pipes, and in moving equipment with scintillometers. The radiotracers proved to be a safe, rapid and accurate method of identifying gold traps, improving security, determining the recovery efficiency of Knelson gold concentrators and estimating retention times of gold particles in various processes."

Jan 1, 2003

By N. F. Manrique

El presente texto refiere el aporte de la química analítica como método de control en las operaciones de la industria minera. La química analítica trabaja con los métodos analíticos, los cuales están en constante actualización al tiempo que los análisis por instrumentación. En este sentido, se muestra que métodos analíticos clásicos como aquellos de reciente adaptación sirven para determinar el cobre, plomo, zinc, plata y oro, entre otros minerales, ais como se describe el rango, tiempo y costo para cada método utilizado.

Jul 20, 1961

By E. Owens, R. Gudavalli, D. Wilder, T. Xia

As mechanical shock and vibration environments evolve, it is important to understand their potential effect on human operators. Human beings are sophisticated mechanisms comprised not only of passive components with mass, damping, and stiffness characteristics, but also of components that can actively affect apparent mass, stiffness, and damping. Because the lumbar spine can exhibit local, short-column buckling, stability of the human trunk depends on the responsiveness of the neuromuscular control system.1-2 We have been evaluating the ability of patients with back pain to respond to a series of sudden loads. We believe the results have implications for isolation design and standards development. Methods 153 patients, aged 21 to 55, presenting with back pain agreed to enroll in a research study that randomly assigned them to one of three treatment arms: high velocity low amplitude spinal manipulation, low velocity variable amplitude spinal manipulation, or wait for 2 weeks and then be randomized to one of the above groups. Response to sudden load testing was one of a battery of baseline evaluations performed upon entry into the study and prior to treatment. EMG electrodes were attached to the skin over the paraspinal muscles of the standing participant bilaterally 3 cm from midline at the L3 level. While standing upright on a force plate (Bertec), participants were fitted with a strap around their back and hooked to a load cell in front of their chest. An accelerometer was rigidly attached to the load cell. Impact was applied to the chest using a cord attached to a falling weight. The weight’s fall distance was varied between 9 and 13 inches to account for the size of the subject. The subject was blindfolded and wore headphones playing white noise to prevent cueing of when the weight was dropped to apply the load. Hence, although the participant knew a load was about to be applied, he or she did not know the instant it would occur. Just before the weight was dropped, a 4 second data collection process was started for the two EMG electrodes, load cell, accelerometer, and force plate. The load drop was repeated 6 times, at irregular intervals, over a period of 2 minutes. The raw data thus collected was reduced to obtain several values: 1) length of time from the pull on the harness to the beginning of the response of the left and right paraspinal muscles (LES, RES), 2) time and magnitude of the maximum response, 3) force and acceleration experienced at the chest, and 4) the time and magnitude of the center of pressure location (COP). A general linear model was used to evaluate the results. Results For the EMG data, of the 1,824 observations made, 90% of them indicated a response. Prior to the sudden load, resting muscle activity was different between left and right sides (p=0.0001) and between males and females (p=0.0001). Female subjects began to respond to the sudden load within 92 to 110 ms and males from 101 to 109 ms. Females exhibited more variation in starting

Jan 6, 2006

By Scott G. Honan, Wayne F. Luinstra

"Since 1992, the concentration of gold using gravity methods has progressed to become an important part of production at Hemlo Gold's Golden Giant Mine. Currently, the gravity circuit accounts for approximately 25% of the Golden Giant Mine's Gold production. This circuit consists of a 30 inch Center-Drain Knelson Concentrator and a Shaking Table. The evolution of gravity concentration will be discussed with an emphasis on the economic justification for a gravity circuit as well as the practical aspects and metallurgical impact of operating such a circuit. It will be demonstrated that the operation of a gravity circuit has definite benefits to the operation of the Golden Giant Mill and will continue to play an important role in future gold production.1.0 IntroductionHemlo Gold Mines Inc. Golden Giant Mine is a 3000 TPD underground gold mine and milling facility located 40 km east of Marathon, Ontario. Mining is accomplished by means of sublevel longhole open stoping. The ore is processed using conventional crushing, 3-stage ball milling, conventional cyanidation and CIP processes. The mill and concentrator are described in more detail in other publications1,2.Since July of 1992, the Golden Giant Mine has been using a gravity circuit for gold recovery in the mill's grinding circuit. Despite the fact that gold recovery averages over 96% using conventional cyanidation and carbon-in-pulp processes, the gravity circuit has become an integral part of milling operations. This paper will discuss the economic justification for a gravity circuit as well as the practical and metallurgical aspects of its operation."

Jan 1, 1996

By S. M. Bradshaw

The principles of microwave heating are discussed with reference to dielectric properties, heating phenomena and microwave equipment. Microwave regeneration of granular activated carbon for the carbon-in-pulp process is examined on a laboratory scale, with special attention being given to highlight the problem areas and specific considerations related to microwave heating. Results indicate that microwave regeneration of carbon with 40% moisture on a wet basis by heating to 650°C with steam addition regenerates the carbon to virgin carbon activity levels but with a higher abrasion resistance. A preliminary economic assessment showed that the capital cost for 120 kg/h microwave unit would be R540 000 with an annual operating cost of R 320/t carbon. These figures yield a return on investment of 12%. The aim of this paper is to provide an introduction to microwave heating and to illustrate its application to the microwave regeneration of granular activated carbon for the carbon-in-pulp (CIP) process.

Jan 1, 1998

Industrial minerals by definition are minerals used as part of an industrial process and usually are one of a number of components, eg finely ground Limestone is an extender in the manufacture of paint. They are normally non-metallic and non-fuel, but like all generalisations there are a number of exceptions. Take rutile û a source of titanium, a metal and also the raw material in the manufacture of titanium dioxide pigment. Industrial minerals under this general definition include construction and agricultural minerals. They are included in the same grouping, principally because their sources are similar and in many cases the raw material, example limestone, can be multi-functional. Calcium carbonate raw materials such as limestone, are used in a wide range of applications from industry as an inert filler, to agriculture as a &apos;lime&apos; source and to construction and as an important component in the manufacture of cement. As far as this paper is concerned I will avoid discussing the agricultural or construction applications, including burnt lime production.

Jan 1, 1985

Estimating Breakage of Fine Ore Particles by Media in a Small Ball Mill Using DEM

Sep 13, 2010

By Marius B. Wechsler

There are considered deep piles which are fixed in blocks of rotating machinery foundations. A mathematical background is developed for determining the behavior of this kind of piles for motions caused by horizontal and vertical oscillations, as well as by roc-king and twisting. It is assumed that the piles come across a top soil layer of depth c, not capable of lateral support, and penetrate over a length b, in a bottom firm soil layer, or in a bottom soft soil layer in which vibrations can produce voids around the piles. With respect to b and c, as well as to the elastic properties of piles and soils, the analysis leads to the maximum bending moments and shear forces subjecting the piles, to the maximum lateral bearing on the bottom soil layer, as well as to the deflection of the pile and the displacement of the foundation block. The results of the performed analysis can be applied to seismic loads too, and they are illustrated by a numerical example.

Jan 1, 1987

By L. Li

The rock quality designation (RQD) was initially introduced by Deere (1963) for civil engineering. But, its application has been largely extended to rock mechanics and has become a fundamental parameter in geotechnical engineering (e.g., Hoek & Brown 1980; Milne et al. 1998). The success of this definition is due, in great part, to its simplicity. However, this index includes a number of limitations. Among these limitations, a critical one is associated with the arbitrarily selected threshold value (e.g., Priest & Hudson 1976). Consequently, the RQD value would vary with different threshold length for the same core. Also, using the customarily and universally adopted but very arbitrarily selected threshold value of 10 cm (for NX cores) in the assessment of RQD, the RQD values usually tend to be either high or low in most rock engineering. Some intermediate values (50%) are less frequently encountered (Harrison 1999). The original definition of RQD does not well represent the actual quality of rock masses. In this paper, an improved definition of rock quality designation (RQDc) is given.

May 1, 2009

Nominating Committee.-On the recommendation of the President, the Board of Directors, at their meeting on Apr. 25,1913, appointed the following Nominating, Committee to nominate officers and directors for next year: John Hays Hammond (Ex-President), Chairman. Robert H. Richards Chairman of Boston Local Section. Richard S. McCaffery, . . . . Chairman of Spokane Local Section. Chester F. Lee Chairman of Puget Sound Local Section. Frederick G. Cottrell, . . . . San Francisco, Cal. Charles W. Goodale Butte, Mont. James W. Maleolmson, . . . . Kansas City, Mo.

Jan 5, 1913

By John C. Stankus

At the 13th Conference on Ground Control in Mining, a paper was presented detailing a successful test in which a new truss system was utilized, in lieu of wood cribs, for tailgate support in the Pittsburgh seam (Stankus et al., 1994). Since that time, additional tests using this same truss system in the Pittsburgh and other seams are now complete. Also, several mines are now using trusses for full panel tailgate support with no cribs. Through an extensive instrumentation program, much data and new information has been gained from these tests and the full panel usage. From this data, not only have new concepts pertaining to tailgate support been developed, but also for headgate, pillar configuration, primary and supplemental support. In this paper, an update will be presented summarizing the results of these various tailgates.

Jan 1, 1995

By E. J. Haug, K. L. Clifford, K. L. Purdy

St. Joe Minerals Corp.&apos;s Southeast Missouri Mining and Milling Division produces lead, zinc and copper sulfide concentrates at three of its operations. The Viburnum and Fletcher mills have been described in previous papers. The new Bushy Creek mill, dedicated in May of 1973, is an updated version of the Fletcher mill incorporating 8.5 m3 (300 cu ft) lead and zinc

Jan 2, 1979