Search Documents

By Wittenberg J. C, Reid A. F

A method is described for the rapid and effective production of polished section mounts of ore and mineral particulates to the standards required for automated image analysis. This requires mounting without segregation of particles by mass or density, and it is also preferable to avoid having particles in contact so that they can be recognised as individuals. To achieve this, the particle samples are first split to an appropriate degree in a rotary riffle, and the sub-sample mechanically diluted and thoroughly mixed with an inert filler of the same size range as the particles. Just sufficient epoxy resin is added to make the mixture fluid. During setting, the ore particles are mechanically supported by the inert filler particles, thus maintaining the particles in a random three-dimensional distribution. A rapid two-stage grinding process, based on the successive use of 600 mesh silicon carbide and 1200 mesh (10 um) corundum on cast iron plates, is followed by three stages of mechanical diamond polishing on cloth laps. Hand polishing is entirely avoided, as is the use of papers.

Jan 1, 1984

By Nolan Eckroade, Nigel Pereira

Wireless electronic blasting systems are a new technology that enable truly wireless initiation through rock, air and water. This is achieved using low frequency magnetic induction waves to wirelessly send a firing command to groups of in-hole primers. Fully wireless initiation not only removes the limitations imposed by a wired connection to each primer in a blast, but also enables users to alter the paradigm of conventional mining techniques to advance operational productivity and reduce personnel exposure to high-risk activities. While initially deployed in underground applications, wireless electronic blasting is now being used in the open cut environment. To capture the early impacts in surface mining operations, case studies conducted at three surface mines evaluated blasts utilizing a wireless electronic blasting system against baseline blasts using conventional, wired initiation systems. The purpose of this paper is to outline the specific learnings associated with wireless electronic blasting in surface mining to date. The paper will include references to these specific case studies as well as benefits realized and applications for the future.

By E. A. Lowe, A. F. Bellamy, J. W. Smith

"In the autumn of 1977 Bethlehem management initiated feasibility studies on recovery of by-product molybdenum from concentrate produced at the existing Highland Valley mining operation. Over the fall and winter months test work was carried forward concurrent with design, flowsheet, equipment specification and cost studies. The decision was made to go ahead with a 200 ton-per-day treatment plant. Construction started in early 1978 and progressed to an initial start-up stage in mid-June. Full operational status was reached in August 1978. Operational results through August 1979 are presented. INTRODUCTIONBethlehem Copper Corporation operates a 20,000 ton-per-day Open Pit Mine and Flotation Plant located in the Highland Valley, some 30 air miles Southwest of Kamloops and 20 miles Southeast of Ashcroft, B.C.Two open pits are worked; the Iona Pit with limited reserves of higher Mo content, and the lower grade, more extensive Jersey Pit. Upwards of 150 tons per day of bornite-chalcopyrite bulk concentrate is produced, ranging 0.25% to 1.5% in molybdenum grade depending on the area mined."

Jan 1, 1980

Sufficient time has elapsed since the enactment of the amendments to the mining legislation in 1981 to enable an examination to be made of the way in which the licensing system operates in practice. One of the most important decisions in resource management in New Zealand is whether or not rights of access to the resource should be conferred by the Crown upon an appropriate private sector participant. The licensing system is the means for allocating these rights of access. The manner in which the licensing system is administered, therefore, is crucial to natural resource management in New Zealand. What is the mining licensing system in New Zealand designed to achieve? This simple question admits of no easy answer. Is it the identification and development of the mineral resources of New Zealand? Are these objectives tempered by issues of resource conservation and environmental protection? Is a balance to be achieved among these competing factors? Does the legislation contain any priorities? Does the system respond in an ad hoc manner to particular facts and circumstances or does it operate within a more predictable framework? To what extent are decisions made on access to minerals with reference to the development or conservation of other resources? These questions may be summarised in the title to this paper which poses the question whether mining licences are instruments for resource management.

Jan 1, 1988

By A. G. Doll

"Many power-based grinding models exist, and most operators are familiar with Fred Bond's ""third theory"". Bond's model is most commonly used to describe primary and secondary grinding to product sizes above, for example, 100 µm. Operators sometimes use Bond's equation to describe grinding in situations where it is not appropriate, such as fine grinding below 50 µm. Using an alternative model would be a better choice in this situation.Bond's equation is one in a large family of models. Related equations better suited to fine grinding include the “signature plot”, Von Rittinger's model and Charles' equation. These models have a similar form to Bond's and can be fit to industrial regrind mills and laboratory tests using the simple regression tools in the charts of computer spreadsheets. Operators will find that fine grinding calculations are both easier and more accurate when using the alternative equations to fit their regrind milling surveys or when performing laboratory regrind mill scale-up for plant design.None of these models are new: Charles' equation was published in 1957 and Von Rittinger's model was proposed in 1867. A quick refresh how to apply these equations can turn these oddities from the undergraduate curriculum into useful tools for plant optimization. They can be fit to any type of mill including stirred and tumbling ball mills.IntroductionBuilding a case for fine grind modelling requires reviewing some theory before building a framework for doing fine grinding calculations. The actual calculation procedure recommended is easy and can be applied by plant metallurgists. Don’t be frightened by the theory; the end result is reasonably simple.The observation that mineral breakage is related to the absorption of energy is usually attributed to Von Rittinger (1867). Lynch and Rowland (2005) describe that the ability to empirical test and calibrate energy models of breakage didn’t exist until the widespread adoption of electric motors in the mining industry during the 1930’s and 1949’s. A series of technical papers published by the Allis Chalmers company during the 1940’s demonstrate that they were attempting to do such a calibration using Von Rittinger’s model which is usually stated as: “the energy consumed in the size reduction is proportional to the area of new surface produced.”"

Jan 1, 2017

By A. Roberts

This paper reviews progress in equipment design and in the techniques applied to mine lighting in Great Britain. The incidence of the disease miner's nystagmus, which was a major source of concern only a few years ago, has now diminished, largely owing to improvements in standards of lighting in mines. The reorganisation of the coal mining industry, involving increasing mech-anisation, together with new safety legislation, has brought about the widespread use of mains electric lighting underground. An account is given of some of the results of research to determine the lighting conditions needed for compliance with the compulsory legal requirement of "sufficient and suitable" general lighting at specific localities in British mines. Some details are given of the techniques applied and the results of recent research in the problem of glare from miners' cap lamps. Of the various factors in the working environment of the miner, it is true to say that lighting is seldom given attention comparable with that devoted to other factors, such as dust, heat and humidity, or atmospheric gas content. No doubt one reason for this lies in the ability of the human eye to adapt itself to low brightness levels. Be that as it may, the fact is that at the turn of the 20th century the miner's working light improved little throughout the centuries during which mining technology has developed. Indeed, in coal mines which encounter a methane explosion hazard, flame safety lamps, with a luminous intensity less than one candle power, were virtually the sole means of lighting during almost the whole of the 19th century. The 20th century has witnessed a substantial improvement in lighting techniques underground in coal and metalliferous mining. In Great Britain the general pattern has been one of standards periodically raised by the implementation of Statutory Regulations imposed under successive hlines Acts, but it is fair to add that the more progressive mining companies usually anticipated the Statutory Regulations, which when they have been put into effect have served to turn into general practice what was already being done at the better mines. In earlier years, official requirements were limited to the specification of approved lamp designs, with stipulated minimum values of luminous intensity and light output, but more recently the necessity of satisfactory maintenance of standards during service has been recognized, and the current regulations not only require that a maintenance organisation should exist, but also specify a maximum permissible depreciation below initial approval standards.'

Jan 1, 1961

By Marcos Villegas

El presente texto describe el desarrollo del sistema de gestión de riesgos en la reingeniería de procesos, justificando la inversión en gestión de riesgos de la concentradora Atacocha donde se protege a las personas, activos e ingresos, minimizando el potencial de pérdida de los riesgos y así proveer fondos para recuperar las posibles perdidas y soportar el sistema en salud, seguridad, medio ambiente y Calidad (SSMAC).

Sep 9, 2007

By Desiree Willis

Disc cutters have determined excavation rates of rock tunneling projects for more than 50 years. First developed in 1956 by James S. Robbins, disc cutters (then 279 mm or 11 in. in diameter) were used to bore limestone of 190 MPa (27,500 psi) unconfined compressive strength (UCS) and were loaded with 7.12 t (15,700 lbs) each. Modern cutters have reached up to 508 mm (20 in.) in diameter and are typically loaded with up to 31.7 t (70,000 lb) to economically bore through the hardest of rock up to plus 400 MPa (60,000 psi) UCS. New developments, such as larger cutter diameters, are geared to increasing the bearing capacity and wear life of the cutting structure. This, in turn, increases cutter life, cutter load and cutter penetration. Disc cutters have also been re-designed on a small scale for use in hard-rock utility installations. Additional variables also affect the three factors, including cutter spacing on the cutterhead, cutterhead diameter and cutter materials.

Jan 1, 2007

By Steve Kral

Reducing the cost per ton and increasing productivity are key factors in a mine’s profitability. Mining companies can do little about commodity prices. So to keep a mine operating at a profit, management must reduce costs and improve worker and equipment productivity in every facet of a mining operation. From mining to crushing to processing, mine management is constantly seeking new methods and technologies to improve the way it mines minerals. And it is willing to borrow techniques used by other operators.

Jan 1, 2002

By Lucien Weber

In the Shanghai area, the soil conditions are such that bearing piles have become an essential foundation part of the new highrise buildings. In order to reduce the settlements under the high working loads of about 2300 kN/pile, the Chinese building authorities require the pile tip to penetrate into the compact sand layer, situated at approx. 60-70 m depth. No H-piles have yet been tested under these conditions in Shanghai. This paper describes the driving of 8 H-bearing piles with 4 different shapes and with lengths varying from 45 to 75 m. Dynamic measurements are performed during driving and after a wait time of approx. 40 hours in order to assess the change in bearing capacity in function of time and in order to get an idea about the resistance distribution along the piles by using a stress wave analysis program (CAPWAP). One pile is equipped with channels between the flanges for executing verticality measurements with an inclinometer. However, this test has not yet been performed. One month after driving, two piles of 75 m length are statically loaded both in vertical and in horizontal directions.

Jan 1, 1987

Remote sensing methods have been used to evaluate vegetative growth patterns for many applications, though relatively little work has focused on tracking mine reclamation progress. For coal mines in Central Appalachia, reclamation approaches that include production of biofuel feedstocks are increasingly attractive, as these may yield significant post-mining land values and contribute to carbon-neutral energy supplies. To optimize productivity, the influence of reclamation parameters must be well understood ? which necessitates tracking biomass production over long time periods. Satellite-based estimations may offer low-cost alternatives to conventional biomass appraisals, and also the potential to provide critical input for carbon accounting at varied spatial scales. In this paper, we use biomass production experimental plots on reclaimed mine sites established by the Powell River Project (PRP) for a comparative study between satellite measurements of Normalized Difference Vegetation Index and inventory estimates of biomass under a variety of conditions. The PRP is a unique public-private partnership in the coalfields of southwestern Virginia dedicated to enhancing beneficial use and environmental protection of mined lands.

Feb 27, 2013

By M. Ghoreychi, X. Daupley

ABSTRACT: The paper is devoted to two major aspects related to the abandonment of salt mines: 1)- Long-term risk associated with the mechanical instability of surface and its consequences for public security and properties. 2)- Long term dissolution and transport of salt resulting from its communication with groundwater. Basic characteristic features of salt deposits and mining methods are presented through the studies already undertaken on French mines. This analysis allows to identify major hazards encountered in different traditional salt mines and solution-mining cavities. In particular, the role of overburden (presence and thickness of salt layer in exploitation roof, presence of clayey rocks or hard rocks e.g. dolomite or anhydrite), presence of water-bearing strata and possibly natural brine levels, discontinuities, etc. are discussed. In the second part, the main features of mechanical behaviour of salt (creep, damage) as well as transfer processes of this material are presented. The influence of these aspects on the long term evolution of abandoned salt mines is then analysed. KEY WORDS: exploitation, abandonment, salt, mechanical, stability, transport, solution, brine. ZUSAMMENFASSUNG: Der Artikel bezieht sich auf zwei bedeutende Aspekte beim Salzabbau: 1)-Das langsfristige Risiko zur Bodenoberflächeunbeständigkeit und sein Einfluss über Mensch= und Gütersicherheit. 2)-Die langsfristige Auflösung und Beförderung des Salz beruhen sich auf Studien über französiche Bergbauen. Diese Analyse emöglicht es, die bedeutendesten Risiken in verschiedenen Salzgruben zu identifizieren, bzw. Traditionellen oder durch Auflösung abgebauten. Insbesondere wird die Rolle des Deckgebirges (Vorhandensein und Dicke von Salzschicht am Dach des Grube, Beisein von Tanlager oder hartem Gestein wie Bitterkalk oder Anhydrid), Beisein von wasserhaltigem Boden und/oder gesalzenen Wasserflächen, Trennflächen, usw… erötert. Im zweiten Teil werden die haupsächlichen Eigenschaften des Salzverhaltens (Kriechen und Beschädigung) beschrieben. Ihr Einfluss über das Verhalten von stillgelegten Bergwerken lässt sich analysieren. SCHLÜSSELWÖRTER: Bergwerksbetrieb, Stilllegung, Mechanik, Beständigkeit, Ausbreitung, Aussolung, Solewasser. RESUME: L’article est consacré à deux aspects majeurs liés à l’abandon d’exploitations de sel : 1)- Le risque d’une instabilité à long terme de la surface du sol et son incidence sur la sécurité des personnes et des biens. 2)- La dissolution à long terme et le transport de sel sous l’effet d’une communication avec des eaux souterraines. Les principales caractéristiques de gisements et d’exploitations de sel sont présentées en s’appuyant sur les études antérieures réalisées sur les exploitations en France. Cette analyse permet d’identifier les risques majeurs rencontrés dans différentes mines de sel traditionnelles ou exploitées par dissolution. En particulier, le rôle du recouvrement (présence et épaisseur d’un banc de sel au toit de l’exploitation, présence de terrains argileux ou de roches dures telles que la dolomie ou de l’anhydrite), présence de terrains aquifères ou de nappes salées éventuelles, discontinuités, etc. sont discutées. Dans la deuxième partie, les principaux traits du comportement mécanique du sel (fluage, endommagement) ainsi que les processus de transport de ce matériau sont présentés. L’influence de ces aspects sur le comportement à long terme d’exploitations abandonnées de sel est ensuite analysée. MOTS CLES: exploitation, abandon, mécanique, sel, stabilité, transport, dissolution, saumure.

Jan 1, 2003

By E. R. Spencer, D. R. Babich, L. A. Alcorn, A. K. Smith

Noise is one of the most pervasive health hazards in mining. A compilation of Mine Safety and Health Administration (MSHA) noise survey data for fiscal year 1990 shows that approximately 40% of the total samples taken for longwall occupations exceeded the Permissible Exposure Limit (PEL) of 100% (Gigliotti et al., 1991). To effectively determine worker noise exposures on longwall coal mining systems, it is necessary to provide accurate baseline measurements for these mining systems. This research was designed to develop measurement methods and test procedures for identifying noise sources that are major contributors to the underground noise exposure of longwall coal mining system workers. The measurement system that was used to analyze the noise sources around a stageloader used stationary dosimeters in a documented repeatable pattern to record the sound pressure and dose levels. A time-motion study of the cutting cycle and stageloader operator’s work cycle was done to correlate the sound levels at measurement locations and the resulting operator’s daily dose with significant noise events. Results from the underground measurements show that the highest sound levels recorded were at the stageloader discharge segment and tailpiece controls, where sound levels remained about the same throughout the test.

By J. Olsson

Introduction Stainless steel has by tradition been a common construction material for hydrometallurgy processes and the most common grades can be found amongst the ASTM 300-series, i.e. austenitic grades of type 304L, 316L and 317L. However, there are a number of new grades available today, which imply more cost effective solutions for those designing plants where good resistance to acids, containing the desired metal ions, often contaminated with chlorides and other halides, is the key issue. There are austenitic-ferritic or duplex grades having the same or even better corrosion resistance than the austenitic grades and approximately twice the strength, which enables design in thinner gauges, which in turn implies less weight and less cost. They have also excellent engineering properties, enabling fabrication of process equipment, machinery and different types of tanks. On top of that, they contain less nickel and molybdenum than their austenitic counterparts, which implies not only lower cost for alloying elements, but also a more stable price when considering the price fluctuations for these alloying elements during the last years. This paper describes briefly the family of duplex stainless steel and it presents a number of relevant corrosion tests where duplex grades have been compared with austenitic grades. The results have in several cases been verified by in-plant exposures in zinc and copper production plants. It also describes applications and experience of duplex grades within a variety of hydrometallurgy plants. Installations of highly alloyed austenitic grades will be described as well. The corrosion tests and service experience reported cover hydrometallurgical processes based on sulphuric acid.

Jan 1, 2007

By Eric Bain Wasmund, Lance Christodoulou, Julio Jairo Carmona Franco, María Fernanda Castillo, Jose Concha

"A number of technologies are in practice for selectively removing coarse gold from conventional grinding circuits. These circuits are often designed so that the grinding mill output is size classified, with large (or high density) particles being removed before the tails are returned to the mill. Because of the high relative SG of gold, and the fact that some forms of gold such as free gold do not break apart during conventional grinding, coarse gold can accumulate in the circulating load, and eventually be lost.Eriez has developed a flotation cell that uses fluidized water to enhance flotation of coarse particles. More than 40 units have been sold in industrial minerals, and we are now exploring applications for the HydroFloat® in the gold industry.Mineros S.A currently produces approximately 120,000 oz of gold per year by gravity concentrating alluvial gold ore with a mean particle size of 330 microns, followed by further concentration using a Falcon separator. A 400 mm diameter pilot-scale HydroFloat® was added to the tails of the Falcon to test whether additional gold could be captured. Enrichments of 50-600 times and recoveries normally in excess of 95% were achieved. This allowed direct smelting of the gold concentrate. Metallurgical results and operating parameters such as water addition and power will be discussed during the presentation.This result opens the possibility that the HydroFloat® could be used directly in the grinding circuit, for removing coarse gold in the circulating load. This work also shows the possibility that the HydroFloat® can produce a throwaway tail, which will reduce the size of the circulating load stream and the grinding requirements of the circuit."

Jan 1, 2015

By Kimiz Dalkir

Some things to keep in mind? ! What is your role in knowledge management? ! What knowledge-related challenges are you facing today? ! How does important knowledge get shared in your organization? ! Can you name factors that enable/block innovation and organizational learning in your work context? A brief history of KM? ! Top-down / imposed ! Rigid / bureaucratic ! Slow deployments ! Expensive ! Unpopular: empty libraries, info-junkyards, low adoption rates ! Problems measuring success ! The result: traditional KM is not the answer

May 1, 2003

The Development of a Non-Roasting Technology for Polymetallic Gold and Silver-Bearing Sulfide Concentrates Treatment

Sep 13, 2010

By Patrick J. Coleman, John C. Kerkering

Problem: Mining in the United States remains one of the most hazardous industries, despite significant reductions in fatal injury rates over the last century. Coal mine fatality rates, for example, have dropped almost a thousand fold since their peak in 1908. While incidence rates are very important indicators, lost worktime measures offer an alternative metric for evaluating job safety and health performance. The first objective of this study examined the distributions and summary statistics of all injuries reported to the Mine Safety and Health Administration from 1983 through 2004. Over the period studied (1983 2004), there were 31,515,368 lost workdays associated with mining injuries, for an equivalent of 5,700 person years lost annually. The second objective addressed the problem of comparing safety program performance in mines for situations where denominator data were lacking. By examining the consequences of injuries, comparisons can be made between disparate operations without the need for denominators. Total risk in the form of lost workday sums can help to distinguish between lower and higher risk operations or time periods. Method: Our method was to use a beta distribution to model the losses and to compare underground coal mining to underground metal/nonmetal mining from 2000 to 2004. Results: Our results showed the probability of an injury having 10 or more lost workdays was 0.52 for coal mine cases versus 0.35 for metal/nonmetal mine cases. In addition, a comparison of injuries involving continuous mining machines over 2001 2002 versus 2003 2004 showed that the ratio of average losses in the later period to those in the earlier period was approximately 1.08, suggesting increasing risks for such operations. Discussion: This denominator free safety measure will help the mining industry more effectively identify higher risk operations and more realistically evaluate their safety improvement programs. Impact on Industry: Attention to a variety of metrics concerning the performance of a job safety and health program will enhance industry's ability to manage these programs and reduce risk.

By D. Conklin

Annual fish monitoring of the Red River, NM from the town of Red River to downstream of Questa, NM has been conducted since 1997. This long-term dataset, sponsored by the Chevron Mining Inc. Questa Mine provides an opportunity to evaluate the fish community response to natural phenomena, such as landslides and drought. Hydrothermal scars are present on drainages to the Red River, which can contribute large quantities of sediment to the Red River during localized storm events. Sediment inputs from the hydrothermal scars result in decreased habitat and water quality conditions within the Red River. Landslides from the hydrothermal scars contributed large amounts of sediment to the Red River in the summers of 2002 and 2007. Resident trout populations in the Red River after summer 2002 were depressed at sites adjacent to and downstream of the hydrothermal scars. Resident trout populations had begun to recover by 2005 and 2006; however, after the summer 2007 landslide, the resident trout population was again drastically reduced. In fall 2007, 13 resident trout were collected from 11 sites in the approximately 23 km reach of the river, compared to 691 from the same 11 sites in fall 2006. Resident trout density and biomass has gradually increased since fall 2007, and flows have removed sediment from the study reach. A combination of increased sedimentation and decreased water quality were likely responsible for the decreased resident trout populations in the Red River. Drought and the lack of flushing flows appeared to exacerbate the problem of high sedimentation levels from 2001 to 2004. Climate models predict prolonged periods of drought and increased intensity of storm events, potentially resulting in less favorable conditions for the resident trout population of the Red River in this area.

Jan 1, 2011

By E. V. Lilford

A number of countries have introduced codes governing the valuation of mineral assets and securities. The African continent will follow suit in due course considering the importance of the global minerals industry as it relates to the attraction of foreign investment. South Africa is to introduce the Petroleum and Minerals Development Bill legislating the involvement of previously disadvantaged individuals and communities in the country?s minerals industry. One of the challenges facing the successful implementation of such codes and bills lies with the abilities of independent valuators to value mineral properties and projects on a consistent basis. Certain valuation principles and methodologies are applicable in all jurisdictions in the minerals industry. These valuation tools and principles are considered and developed in this report. They have been discussed and developed to encourage minerals valuators to consider and consistently apply the most applicable valuation methodologies.

Jan 1, 2002