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By Peter W. Lotz

Contents of: ?Sampling for Cyanide in Metallurgical Processes? ?Sampling at process level of operation ?Sampling at environmental level ?Sample stability and integrity issues ?each citing possible objectives, practical example and reasons for surprises Overall recommendations on sampling plans and procedures to maintain sample integrity

Jan 1, 2005

By P J. Minehan

The investigation of the potential of the Webb/Baynes block of the Buller coalfield for anode carbon manufacture has generated much information on the physical beneficiation characteristics of the Buller coals in general. A further 36 drill holes of the block in question and several other samples have been analysed by sink/float analysis, either at a single density or over a range of densities. In addition, many samples have been beneficiated on a laboratory shaking table or by flotation. The ash content can be reduced by a variable factor. The reduction factor of between two and four by sink/float analysts is understandably less for tabling where separation is not perfect. All Buller coals behave similarly, there being greater ash reduction factors for higher ash coals.

Jan 1, 1983

By Jeremy Theys

The Sacramento Regional County Sanitation District (SRCSD) is improving the sewer system in the Natomas area of Sacramento, CA. The Upper Northwest Interceptor (UNWI) system is an ongoing series of tunnel pipeline projects that will provide sewer conveyance for all residents of northeast Sacramento County to the New Natomas Pumping Station, located North of downtown Sacramento, also in the city of Sacramento limits. The New Natomas Pumping Station then carries wastewater flowsto the Sacramento Regional Wastewater Treatment Plant in Elk Grove via the existing Lower Northwest Interceptor. The Joint Venture of Traylor Brothers, inc. and J.F. Shea (TSJV) were awarded the UNWI 1&2 project in late September, 2007. The planned 5.8 km (3.65 mile) construction route for UNWI 1&2 begins at the New Natomas Pump Station and runs north along the East Drainage Canal to the begin-ning of UNWI 3&4 at Bridgecross Drive. UNWI 1&2 includes approximately 5.8 km (19,240 feet) of 3.65 m (144 inch) inside diameter pipe using Earth Pressure Balance Tunneling Methods. The project also includes 16.76 m (55 feet) of 3.04 m (120-inch) diameter interceptor pipeline, twenty three access manholes spaced approximately 305 m (1,000 feet) apart along the alignment, a 2.13 m (84-inch) by 3.65 m (144-inch) transition structure, a 3.65 m (144-inch) by 3.04 m (120-inch) transition structure, and the connection of three existing sanitary sewer lines to the interceptor.

By John McNeil

Mr. President, and Members of the Rocky Mountain Coal-Mining Institute-Gentlemen : I appreciate the distinction of addressing this representative body of men upon a subject that lies so close to the heart of each one of us, and which is one of the principal objects of our gathering here today, in this beautiful city-so beautiful, with its grand and glorious mountains looking down upon us, that its charm makes us almost forget the men we left toiling "underneath the ground." But that object-the safeguarding of our coal-miners, who spend the greater part of their lives delving in the bowels of the earth-is the cause of our gathering from the "rock-ribbed" States of Utah, Wyoming, New Mexico, and Colorado. And, as I look about me, my eye lights on the face of many an old-time friend- on some with whom I have walked for more than thirty years; so, whatever the merit of this little talk of mine, it cannot be said that it was made by a "tenderfoot." You must not for a moment think that I shall attempt the impossible task of completely covering so comprehensive a subject as '(Accidents in Coal Mines,' and take much more time than has been allotted me, or would be advisable for me to consume. So I shall confine myself, as briefly as possible, to some of the most common causes of accidents, and the possible means by which these disasters may be diminished. For a great many years the cause of mine accidents and their prevention have been the subject of grave thought and investigation by both national and state governments. As early as 1835 Great Britain appointed a royal commission of talented men, possessing special knowledge in the conduct of coal- mining, also eminent authorities in science and its application, to search into these matters. Since 1835 there has been a succession of such commissions of research, at frequent intervals, in all countries wherever coal has

Jan 1, 1913

Your assessment of the minerals business. The global mining industry is strong. I am convinced it will continue meeting the mineral needs of the world population for the foreseeable future. Two developments have greatly enhanced the industry’s ability to produce low-cost minerals. Technological innovations have resulted in increased productivity. And there has also been a dramatic expansion of the number of favorable countries in which to explore and mine. Capital expenditures have flowed to the low-production-cost mines and development projects as well as to the exploration projects and stable countries having the best potential for valuable mineral discoveries.

Jan 1, 2000

By Jochen Petersen, David G. Dixon

"Although heap leaching may be perceived as a somewhat low-tech route for the extraction of low-grade minerals, the underlying physical, chemical and biological processes are in fact extremely complex. There has been increased interest in heap leaching of sulphide minerals in recent years with the advent of controlled bio-heap leaching, and the need to mine more marginal ore deposits.A detailed investigation into the dynamics of heap leach processes has provided much insight into the underlying complexities, and has led to the development of a sophisticated modelling tool, HeapSim. Some of the sub-processes that are modelled include mineral kinetics, particle size effects, bacterial growth, oxidation and adsorption, gas adsorption, pore diffusion, bulk advection, gas balance and heat conservation. The interplay of these various sub-processes is illustrated in the paper.Two case studies are presented which illustrate specific features of the model for different applications and how these have helped to identify key areas of concern. The first is focussed on chalcocite heap bioleaching, which shows that by nature of the reaction the process is strongly dependent on the initial supply of acid to the mineral site. In heaps this acid supply can be severely limited by the rate of diffusion from channels of flowing solution into stagnant zones of the heap, whereas in narrow-bore laboratory columns this effect is not observed."

Jan 1, 2003

By Benoit Clermont, Jan Lux

"Magotteaux and Anglo Platinum started a co-operation program with the main aim of establishing the optimum milling configuration measured in terms of throughput, fineness and energy consumption.For this purpose, a fully instrumented pilot milling plant, supplied by Magotteaux (Pty) Ltd, and equipped with a 0.9 x 1.0 m ball mill, was erected at Frank concentrator (Merensky Pt ore). The primary ball mills at Frank concentrator were surveyed in order to set the conditions for the base case. This data was then replicated in the pilot mill under the same configuration. Thereafter, a series of different parameters were varied in order to attempt to optimize the milling system.Only grate versus overflow discharge and open versus closed circuit will be discussed in this paper.It should be noted that this paper does not attempt to give a universal solution as to what milling configuration is optimum in all cases. The conclusions apply for this particular case and probably most others, but it would be advisable to consider each case on its own.CONCLUSION• Overflow versus grate dischargeAn overflow mill has a “pool” of slurry around the toe of the ball charge, which creates a counter lever to the ball charge. This will reduce the absorbed power in the range of 10-15% (depending on the case) and will consequently result in a coarser grind. The tests found a 4% gain in grinding efficiency (Wio) with an overflow mill but this is probably not significant.This lower absorbed power and coarser grind can be counteracted by increasing the ball charge (if below maximum) and/or by increasing the mill volume when removing the grate discharge (a typical grate takes up about 300mm of the mill length).• Open versus closed circuit"

Jan 1, 2003

By A. Zeni, S. L. Bessinger, T. A. Palm

San Juan Coal Company (SJCC) operates an underground coal mine near Farmington, New Mexico. Continuous miners and a longwall produce 7-8 million tons per year. The coal seam at SJCC has tested to have a propensity for spontaneous combustion. As such, during feasibility for this project, it was elected to utilize a bleederless ventilation system on the longwall. Three-entry gateroads are developed, and the longwall gob is sealed as mining progresses. SJCC utilizes a nitrogen injection system to continuously inertize the gob. In 2004, the mine was nearing completion of its first longwall district. The next district would contain longer panels (up to 12,500 feet). Due to the liberation of methane, and to a lesser extent hydrogen sulfide, a typical wrap-around ventilation system would not be appropriate. Not only would gas concentrations likely be challenging, but the overall ventilating pressure in the mine would have to be increased beyond limits established to mitigate the potential for spontaneous combustion. Given the above-described operating constraints, SJCC determined a need for a small ventilation shaft in the back (longwall setup area) of the next district that would draw adequate air past the longwall seals to maintain low gas levels and permit the required regulatory inspections to occur. Extensive ventilation modeling and gas desorption testing indicated that the shaft would be required to handle a volume of air ranging from 40,000 cfm to as high as 185,000 cfm. This large range is driven by the position of the longwall face with respect to the shaft and the effectiveness of the SJCC degasification program (SJCC uses vertical gob vent boreholes and horizontal in-seam methods). Ventilation simulations determined an appropriate diameter for the 350-ft-deep shaft to be 5 feet. Having determined shaft size, the next decision related to the method of shaft construction. Conventional shaft sinking was ruled out, due to the small diameter. Raise boring was an attractive option but had two drawbacks: (1) development crews would reach the bottom of the shaft just a few weeks before longwall startup, leaving a compressed timeframe to install the shaft, and (2) raiseboring requires additional underground entries to be developed to stow the project’s cuttings. While raiseboring remained a viable option, the problems associated with it led SJCC to also investigate blind drilling.

Jan 1, 2006

By Máximo Pérez, Julio C. Videla, Rosa Dzioba

"This paper reports the hydrometallurgical treatment of gravity concentrates of gold samples and outcrops associated with graphite ores obtained from:• flotation tailings of crystalline graphite minerals• outcrop samples of graphitic rock associated with auriferous minerals and free gold located in the Villa Union district and surrounding areas - La Rioja Province - Argentina.Previous studies of the flotation potential of crystalline graphite minerals failed to consider the presence of noble metals.The samples represent a mineralized zone of crystalline graphite which is distributed in different formations with a NE - SW trend in Maz, Punta Colorada and Las Ramaditas hills, covering an area of about 300 square kilometers."

Jan 1, 2003

By W. Kracht

Frothers are surfactants used in floatation to aid generation of small bubbles. Studying events at the moment of bubble creation is a challenge because of the short time frame. This presentation introduces a novel acoustic approach. The technique has the resolution capable of detecting events that occur within 1-2 ms. The transition from coalescence to non-coalescence is tracked as a function of surfactant concentration and gas rate through the capillary. Results are given for some common flotation frothers and n-alcohols (C4-C8). A stress model is used to give a qualitative explanation to the observed action of frothers on coalescence prevention. Results for salt (sodium chloride) are included for comparison).

Jan 1, 2009

By C. T. Agouridis

Head-of-hollow fills or valley fills have gained national attention due to increasing environmental concerns, particularly with regards to headwater stream loss. Researchers at the University of Kentucky in conjunction with outside scientists and consultants in the fields of stream restoration, wetland restoration, and mined land reclamation have developed new design methodologies for creating a headwater stream system for a head-of-hollow fill in eastern Kentucky. The design was largely built on the Forestry Reclamation Approach (FRA), which encourages a non-compacted spoil medium to promote tree growth, in an effort to address concerns related to water quantity and quality as well as habitat development. The major components of the design included 1) modifications to the crown geometry, 2) compaction of the crown to control infiltration, 3) utilization of natural channel design techniques, 4) use of the FRA to promote tree growth, 5) creation of ephemeral channels and vernal ponds, and 6) implementation of a novel bioreactor-wetland treatment system to improve water quality.

Jan 1, 2008

By E. S. Wheeler

The rapid increase in the use of monel metal and malleable nickel in the form of sheet, rod and tube has resulted in a similar increase in the demand for these metals in the form of castings. These castings range in size from small valves and pipe fittings weighing a few ounces to large centrifugal pumps, gate valves and marine propellers, some of the last weighing as much as 24,000 lb. A group of such castings is shown in Fig. 1. A large nickel agitator is shown in Fig. 2. Monel metal castings are widely used in accessories for steam power plants and in a variety of chemical plant equipment where the corrosion resistance, high strength and toughness characteristic of this metal render it particularly valuable. Nickel castings find extensive use in the construction of corrosion-resistant apparatus, and are often used in conjunction with wrought nickel sheet and tube in the fabrication of equipment for handling a variety of chemical and food products, particularly dairy products. In response to this demand for castings, numerous foundries have undertaken the production of castings of these metals and have met with varying degrees of success. The successful production of castings of monel metal and nickel requires careful attention to molding practice, proper melting equipment

Jan 1, 1930

By Y. Duraisamy

This paper presents the compressibility of tropical peat reinforced with cylindrical cement column. When a cement column installed vertically in peat, its compressibility was reduced because of the hardened skeleton matrix formed by cement particles bonding with adjacent soil particles in the presence of pore water. The effects of diameter, number of columns and cement proportions in cement columns on the compressibility have been investigated in this study. The results indicated that compressibility index Cc and Ca decreased with the increase in diameter of the cement column. Specimens with 45 mm and 60 mm diameter of cement column were cured for 28 days, after which they were subjected to Rowe Cell Consolidation test. Based on the results obtained, it shows that cement columns can successfully reduce the compressibility of tropical peat.

Jan 1, 2007

By Mark S. Redfern, Kim M. Corneliusa, Christopher A. Hamrick, Sean Gallaghera

Coal miners often handle heavy electrical power cables, weighing up to 10 kg per meter. These cables are manually lifted and attached to the mine roof to prevent damage from mobile underground equipment. Data suggest that workers who commonly perform cable handling tasks experience a high rate of lost time back injuries. In this study, six male underground miners performed a total of 12 cable-hanging tasks in standing, stooping, and kneeling postures, during which kinematic and ground reaction force data were collected. Reductions in vertical work space were found to result in a linear increase in the peak moment experienced by the lumbarspine (p<0.05). In restricted postures, peak moments were not significantly different in stooping vs. kneeling postures (p>0.05). Average lumbopelvic flexion during the tasks was highest in stooping conditions, followed by standing and kneeling exertions (p<0.05). Implications of this data with respect to design of cable handling tasks are presented and discussed. Keywords: Biomechanics, posture, low back pain, restricted workspace, mining

By Alberto Barreda

A medida que la extracción del mineral progresa, la necesidad de madera en la construcción de edificios e instalaciones de la mina, también se incrementa. Por ello, el objetivo del presente trabajo señala la importancia de la madera como factor de producción en la industría minera, al tiempo que describe la silvicultura como técnica agronómica de ayuda en dicha manufactura. Revisando los cuadros estadísticos realizados en el Perú durante los años 1949- 1955, muestran que de cada extracción global de minerales (metálicos y carbón), obtenemos el promedio de 0,9 pies cúbicos de madera por tonelada de mineral extraído, con un equivalente de 5 pies tablares por pie cúbico, como factor de conversión. El problema surge cuando al intentar desplazar la venta de madera importada, se agotan las fuentes de desabastecimiento local, generando una crisis de reservas en el mercado libre. En consecuencia, se propone el establecimiento de plantaciones forestales en áreas localizadas y dentro del plazo de 10 a 12 años, las cuales prolongarán la conservación de la madera nacional, mejorarán la calidad de la misma y a su vez disminuirán los precios de venta.

Jul 20, 1956

By G W. Heyes, P J. Guy

Investigations were undertaken to assess the suitability of CSIROflotation methods for improving the efficiency of separation of heavyminerals in the monazite circuit at the Westralian Sands Limitedoperations at Capel, Western Australia. Flotation work was conducted on two plant samples. The first was a high-titanium product containing considerable amounts of zircon and silica as quartz and aluminosilicates, and the second was a low monazite/zircon material containing high levels of silica. A three-stage process including reverse flotation was developed totreat the first sample. In this process monazite, zircon, quartz, andaluminosilicates were selectively concentrated by flotation and screening to produce a titanium-rich product. In the first stage, an acid amine float, monazite, zircon, and some non-zircon silica were recovered and in the second stage, an alkaline amine float using a fluoride activator, more quartz and staurolite were floated. The titanium minerals were thus concentrated in the unfloated fraction. In the third stage, the titanium-rich flotation tail was screened at 250 ¦m to remove the remaining coarse aluminosilicates. In a single pass, the three-stage process yielded a TiO2 recovery of 64.0 per cent with the titanium-rich product assaying 70.3 per cent TiO2.

Jan 1, 2001

By C. E. McManus

MANY mechanical advances have been made on mining equipment during the year 1951. There have been a number of trends established and many modifications made on open-pit equipment to increase the efficiency and availability of all the machines necessary in the moving of overburden and iron ore. Some years ago, the trend toward larger shovels for the loading of off-highway trucks began, but in the last year, it has become general practice to use the 5 to 7 ¼ -yd quarry-type shovels in the loading of haulage units. For years these larger shovels were used in the locomotive haulage pits. As the truck capacities increased from 15 to 20 to 30 tons, the need for larger loading units became apparent. Today in most mines, large shovels are in evidence and a few 8-yd shovels will be delivered this year for loading off-highway trucks. Torque Converter-Shovel The Diesel-driven shovel with its friction bands has been modernized with the torque converter. There have been about ten shovels remodeled to take a torque converter in the drive system. The large high-torque, low-speed Diesel engine was removed and replaced by a high-horsepower, high-speed, automotive-type engine. This engine was connected directly to the torque converter. The torque converter was connected to the shovel through the standard original sprocket and chain. Dual governors controlled engine performance. One governor controlled the high idle of the engine; the other governor, which is connected through a flexible shaft to the output shaft of the converter, controlled the loading of the engine. With this dual governor hook-up, the engine anticipates load conditions and is operating at high idle and full throttle before the shovel load is transmitted back through the converter to the flywheel. It has been found that with this automotive-type engine and converter, the shovel capacity has been increased about 20 pct. Also, the wear on the friction bands, breakage of hoist cables, and other mechanical breakages has been reduced materially. Alloy-Steel in Shovels The shovel equipment manufacturers have been experimenting with low-temperature-strength, high-alloy steels to combat the excessive breakage that occurs in extremely cold weather. High-nickel alloy steel has been used in critical areas that are affected by low temperatures, the most notable being dipper sticks. Most shovels ordered today are equipped with some of this special, alloy steel. More and more manganese alloy is being used for replacement parts such as shovel pads, idlers, drive sprockets, etc. Although the initial cost of these parts is considerably higher than the standard replacement items, the life of these manganese parts is considerably longer and well worth the added expenditure. Dipper-teeth repair is still a problem. Most companies use the small replaceable inserted tooth. It has become common practice among some of the companies to "job out" their dipper-tooth repairs to outside welding companies. This necessitates an additional inventory of teeth, but it does guarantee an adequate supply of replacement teeth at all times. These contractors have set up their shops on a production basis and can do an acceptable job at a high rate of speed. Thermite welding has been used in retipping teeth. To date, the process cannot be called successful but with improvements the time required to repoint the dipper teeth will be decreased considerably. The submerged arc process has been tried in the replacement of these dipper points, but like thermite welding has not proven successful. Here again, if a method can be developed to use submerged arc, the job of teeth repair will be made much easier. New model shovels in 6 ½ and 8 cu yd sizes fea-

Jan 1, 1952

By S. J. Dillingham

As we enter the new century and close out the old, it has become standard procedure for most blasters to complete a blasting log or shot report following a blast. However, how can you be sure these completed blasting logs are worth the paper or electronic space they occupy.3 Is the recorded data accurate and meaningful? Will the blasting logs stand up under investigation? This paper will attempt to define the purpose of a blasting log, illustrate common mistakes, discuss potential problems, and indicate steps that a company or individual blaster can take to improve and protect against costly errors. The end result will be a reminder of the importance of accurate documentation following a blast that must be given the same individual effort as went into the blasting itself. This paper will also attempt to achieve a proactive training resource to improve the use of blasting logs. A completed blasting log is, quite possibly, the only witness to the overall credibility of the work of the responsible blaster. The log may remain perpetually silent, only to end up in a file that is moved progressively with time to various levels of long-term storage. But, will this silent witness be ready to speak out should a concern arise from the blasting ? Will the blasting log communicate with authority and credibility, or will it be ridiculed by investigation and silenced in shame with costly adverse results for the blaster and company? It is not enough to simply complete a blasting log. The information it contains must be accurate enough to stand the test of time and arduous scrutiny. Unfortunately, most blasters and their associated blasting companies do not realize the status of the silent witness until it is too late.

Jan 1, 2000

By H. E. Biber

DURING the production of tin plate a thin layer of FeSn2, is formed at the interface between the steel sheet and the protective tin coating. Because excessive amounts of this alloy layer are undesirable, the kinetics of its formation is a subject of interest in the tin-plate industry. A recent study of this subject at our laboratory uncovered a relationship which should be of general interest to anyone studying kinetics of reactions in metallic systems. It had been previously concluded that, at any given temperature in the range 175" to 330°C, the Fe-Sn alloy layer would have a parabolic growth rate.1,2 However, our studies showed that this rule apparently holds only when the tin plate is heated very slowly to the "reaction" temperature; when the tin plate is rapidly heated, considerably different growth rates occur. An example of this effect of heating rate on growth behavior is contained in the accompanying results of alloy-layer growth measurements at 240°C in oil baths stirred at 10,500, 1800, and 0 rpm. The heating curves for these three conditions are given in Fig. 1, and the growth data are presented in Fig. 2. With the rapid heating rate, provided by the stirring at 10,500 rpm, the alloy layer had three distinct stages of growth. In the initial stage, which persisted well beyond the time required to heat the tin plate to bath temperature, the alloy layer formed very rapidly. The growth followed a rate law of the form w = ktn where n > 1. This initial stage was followed by a growth-retardation stage of about 50-sec duration in which little additional alloy was formed. In the third stage the growth again followed a rate law of the form w = ktn, but here « =0.3. With the intermediate heating rate provided by stirring at 1800 rpm, the three-stage nature was less pronounced and the slope of the third stage increased (i.e., n > 0.3). With the slow heating rate provided by the unstirred oil bath, the alloy layer grew in two stages. The initial rapid-growth stage persisted only until the specimen was heated to bath temperature, no growth retardation was observed, and the slope of the main portion of the plotted data was greater than in the stirred baths, having a value of almost 0.5. Similar results were obtained for other bath temperatures in the range 200" to 300°C. This effect of heating rate on growth behavior may be due to changes in the rate of nucleation of FeSn, crystallites. The iron and tin are in contact from the onset of heating. Thus the initial formation of FeSn, occurs not at the "reaction" temperature but rather while the tin plate is being heated to that temperature. Because nucleation is in general temperature-dependent, different heating rates could cause different over-all nucleation rates, which in turn could cause different growth behaviors. A more detailed discussion of the growth of Fe-Sn alloy layer and the effect of heating rate will be published shortly.

Jan 1, 1965

By M. J. Fairweather, Keith Lee, Naseem Mian

"The initial metallurgical response of the lead flotation circuit at Cominco Alaska's Red Dog Mine was substantially below feasibility expectations. A program of diagnostic mineralogical analysis pointed the way to a number of process improvements, including simplification of the flow sheet and installation of a large flotation column as a lead cleaner. A diagnostic mineralogical analysis of the improved circuit shows that inadvertent activation of both sphalerite and pyrite has been substantially reduced, resulting in significant improvements in metallurgical performance. Directions for further improvements to the circuit performance are suggested by the recent analysis.IntroductionRed Dog is a high-grade, sedimentary exhalative (sedex) deposit with relatively simple mineralogy. The primary non-sulphide gangue minerals are quartz and barite, with minor barium carbonate (witherite). The iron sulphate minerals, siderotil, rosenite and copiapite occur variably throughout the deposit. Mineral texture is variable ranging from liberated sphalerite grains visible to the naked eye to intergrowths, particularly between sphalerite and galena, to less than ten microns. Both pyrite and marcasite are present. To date no enhanced reactivity of marcasite has been observed. For this discussion, ""pyrite"" will be used to refer to both iron sulphide minerals. In common with other sedex deposits, Red Dog contains organic and sulphur impurities."

Jan 1, 1997