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By J. M. Ortiz

Grade control and short-term planning are usually based on the samples obtained from blastholes. These samples may carry a large sampling and sample preparation error. At El Tesoro copper mine in northern Chile, an advance drilling grid is used for short-term planning and grade control. These drill holes are sampled well in advance, and a short-term model that incorporates several variables and sophisticated estimation methods can be prepared for decisionmaking. An additional advantage of the advance drilling samples is that reverse circulation can be used instead of conventional down-the-hole equipment, and a very careful sampling and sample preparation process can be implemented, reducing the total sampling error. Advance drilling can be performed on a wider grid than blasthole drilling, hence the decision about the grid requires assessing the economic benefit of different sampling grids. Furthermore, this process allows the cost of poor sampling and the effect of different estimation procedures to be quantified. We demonstrate the optimization of the drilling grid for short-term planning and grade control at El Tesoro mine by means of the economic evaluation of the performance of different drilling grids, with different drilling techniques (which differ in the sampling error). The methodology is based on creating dense (exhaustive) geostatistical simulations of the grade distribution over a volume defined for a production period in respect of the geological model, and assuming each simulation as the true grade distribution. Then, samples are obtained from the exhaustive simulations at a spacing similar to the advance grid to be evaluated, and a sampling error is added. The short-term estimation procedures used on the mine are applied to determine the destination of each block and the profit obtained. This profit can be compared with the maximum profit (unachievable) and with the profit under different sampling errors and grids. The results show that the current 8 x 8 m drilling grid is appropriate and by reducing the sampling error, misclassification is also reduced, leading to an increase in profit of about US$ 5 million in 4 years.

Jan 1, 2012

By Hernán Parra

El presente trabajo señala la fase de tratamiento metalúrgico de pirrotitas que contienen oro, donde en la concentración por flotación se encontró un esquema adecuado para tratar pirrotitas auríferas considerando las restricciones ambientales que no permitieron incorporar técnicas de cianuración directa, que es como suelen tratarse es-tos minerales en el mundo. Asimismo, se propuso el uso de concentradores centrífugos para recuperar el oro libre fino en una primera etapa gravimé-trica, y concentradores de mesa Gemeni para obtener concentrados de alta cali-dad disponibles para fundición.

Sep 9, 2007

"The measurement of error in assays collected as part of a mineral exploration program or mining operation historically has been undertaken in a variety of ways. Different parameters have been used to describe the magnitude of relative error, and each of these parameters is related to the standard measure of relative error, the coefficient of variation. Calculation of the coefficient of variation can be undertaken in a variety of ways; however, only one produces unbiased estimates of measurement error: the root mean square coefficient of variation calculated from the individual coefficients of variation.Thompson and Howarth’s error analysis approach has also been used to describe measurement error. However, because this approach utilizes a regression line to describe error, it provides a substantially different measure of error than the root mean square coefficient of variation. Furthermore, because regression is used, Thompson and Howarth’s results should only be used for estimating error in individual samples, and not for describing the average error in a data set. As a result, Thompson and Howarth’s results should not be used to determine the magnitudes of component errors introduced during geochemical sampling, preparation, and analysis.Finally, the standard error on the coefficient of variation is derived, and it is shown that very poor estimates of relative error are obtained from duplicate data. As a result, geoscientists seeking to determine the average relative error in a data set should use a very large number of duplicate samples to make this estimate, particularly if the average relative error is large."

Jan 1, 2007

By Michael S. Wieland

Charge malfunction problems result from rather universal damage mechanisms and are widespread throughout surface and underground delay blasting. Recent refinements in instrumentation technology reveal a range of charge performance difficulties, not just outright misfires. This report focuses on the U.S. Bureau of Mines research regarding desensitization and malfunction of delay detonators and cap-sensitive explosives, utilized in underground coal mining. Delay blasting generates tremendous shock waves and rifting forces that fracture and heave the surrounding stratum. The shock waves from charge explosions propagate outward in all directions through the coal, impacting neighboring charges with later delays. The impact phenomena have debilitating effects, causing degrees of reduced charge performance ranging from misfires or weak detonations to out-ofsequence detonations. Impaired charges react poorly. fracture less coal, and produce fumes with higher toxicity. Coal-mine, underwater, and simulator tests were conducted to m3re thoroughly understand the shock-wave and rift-compression damage mechanisms. Recently the U.S. Bureau of Mines partially resolved the malfunction problem by demonstrating the feasibility of formulating a rugged explosive, which could pass the requisite tests for certifying an underground coal-mine explosive. The charge formulation was not certified only because it lost initiation sensitivity too quickly from natural aging and had to be rebatched to finish the testing.

Jan 1, 1994

By J. Andrew Cornier, Mike Cooper

"Upon successful completion of the AG/SAG Mill project (Cooper et al., 2001) the Brunswick Mine concentrator was configured with single line processing through the AG/SAG mill, followed by two parallel ball mill and flotation circuits. The Stage Grinding project was undertaken to utilize a pre-flotation stage on the AG/SAG mill primary cyclone overflow and simplify the flowsheet by consolidating the two ball mill and flotation circuits, resulting in single line processing fi-om AG/SAG mill to final concentrate. Concurrently, the reclaim water supply capacity was increased to enable flotation cleaning at lower percent solids.Benefits from the Stage Grinding project include revenue enhancement from increased zinc grade and recovery combined with additional lead recovery. Further benefits included a reduction in the number of process pumps, reduction in loss associated with spillage to sumps and process simplification through efficient use of equipment layout.The Stage Grinding project was implemented in six phases over a period of seven months in 2000. Each phase was commissioned during scheduled concentrator shopdays with minimal additional downtime required. One year after project approval the Stage Grinding project was completed at a total cost of $1 1.8 million.INTRODUCTIONThe Noranda Inc. Brunswick Mine, located near Bathurst, New Brunswick, is one of the world’s largest leadzinc mines. Milling of ore began in 1964 from the No. 12 orebody, with an expansion in 1966 to accommodate ore fkom the No. 6 open pit located several kilometers away. In 1980 the pit was exhausted and the concentrator rationalized to accept a design feed rate of 10,500 tomes per day from the No. 12 mine. In excess of 100 million tomes have been milled to date, representing over three-quarters of the known reserve. The concentrator employs differential froth flotation to produce lead, zinc, copper and leauzinc bulk concentrates. The ore is massive sulphide, with approximately 20% valuable minerals, 60% pyrite and 20% silicates."

Jan 1, 2002

By H. Verakis, M. J. Sapko

The Pittsburgh Research Laboratory (PRL)1 of the National Institute for Occupational Safety and Health (NIOSH) in collaboration with the Mine Safety and Health Administration (MSHA) Technical Support Center has devised a prototype hand-held instrument which can provide a direct assessment of the potential explosibility of a coal and rock dust mixture. Current Federal regulations require that rock dust be applied in all underground areas of a coal mine to mitigate the propagation of a coal dust explosion. To determine compliance with the Federal regulation, mine inspectors collect dust samples from sections of underground coal mines for an MSHA laboratory analysis of incombustible content. However, the laboratory analysis may not be completed for more than a week or two, during which time the mine area from which samples are taken may be inadequately protected. The operation of the Coal Dust Explosibility Meter (CDEM) is based on the difference in optical reflectance between light rock dust and dark coal dust. For a given coal volatility, the optical reflectance of such mixtures is relatively constant at the limit of explosibility, independent of the coal dust particle size. The CDEM is not intended to replace the current MSHA laboratory analysis of coal mine dust samples for incombustible content, but to serve as a supplemental device for enhancing mine safety through improved rock dusting practices.

Jan 1, 2006

A computerised cataloguing system for geological specimens is described. The catalogue is designed for use with a compactus-type storage system. The information stored in the catalogue for each specimen includes the type of specimen, locality information in terms of standard ~ap sheets and descriptive location, geological age, stratIgraphy, and specimen descriptions. The catalogue can be interrogated at any level of detail on the basis of any combination of these specimen parameters.Other information stored for each specimen 'is the compactus address, collection date, reference information and the type of analyses performed on that specimen:Any mterrogatlon produces a listing of those specimens which satisfy the search criteria.

Jan 1, 1974

As the theme of the conference is ære-discover Otago' from the minerals point of view, it is also timely. Of the eight million ounces of gold recorded produced from Otago, perhaps a quarter of this came from the goldfields of St Bathans, Vinegar Hill and Cambrians. The most notable among them was the Kildare Hill Mine, which is the so-called Blue Lake at St Bathans today. The bottom wash encountered in this mine contained the famous Kildare lead, which averaged 7 1/2 dwt to the dish, and is still one of the richest leads of alluvial gold known in the world. The richness of this lead, the best encountered in these gold fields, is otherwise stated to have yielded more than 42 ounces of gold to the cubic yard. It should be borne in mind that this equates to about $22 000 per cubic metre, in todayÆs values. I have been told by older residents of this district that in fact about 1 million ounces came out of the Kildare mine and associated workings. In todayÆs values, this would be about 530 million dollars worth of gold. The largest mines in the district were at Surface Hill, Kildare Hill, Nicholsons, Vinegar Hill, the Never Fail claim at Shepherds Flat nearby, and at Cambrians. It would appear that in almost every case, work stopped when the bottom wash progressed too deep down dip of the anticline hills on which it was initially found. The mining methods were sluicing and hydraulic elevating, and although the gold bearing ground did not stop, eventually it exceeded the ability of the mining methods then available years ago, to work it further. When it is realised that the previous mining has removed what is likely to be only a low percentage of the gold resources in these fields, a tantalising situation presents itself today in that mining technology now available will enable another cut to be taken off these fields. As in the past, I believe this will be million ounce plus and multi-million dollar scenarios, where the economic and social benefits will become widespread prizes.

Jan 1, 1992

By P. A. Hagerty

Biological treatment of metals-impacted water using sulfate reduction is a viable means of treatment that has been applied in pilot and full scale at numerous projects. One of the fundamental challenges with this type of treatment is the selection of an appropriate substrate to support the sulfate reduction process long-term. The substrate degradation products provide a carbon source and an electron donor for metabolism by sulfate-reducing bacteria and consequently organic characteristics are critical; however, the physical attributes of the substrate are equally critical to an efficient and optimized substrate mix. This paper explores the affect of particle size (a.k.a. grain size) of several substrate mixes on the treatment efficiency of sulfate reducing treatment systems. Substrate selection can be separated into two phases of evaluation, the primary selection phase and the secondary optimization phase. The primary selection phase considers such fundamental attributes as source availability, economics, bioavailability and longevity. These fundamental activities are conducted in order to identify potential candidate ingredients of the substrate mix which are regionally available, economically viable and consistent with the biogeochemical aspects of the project. Recent work has been conducted in the development of testing protocol for organic substrates to quantify bioavailability (Martinez Hernandez et al. 2010, Place et al. 2006) as part of the primary selection phase. Once the substrate ingredients have been selected based on the primary criteria, the mixture of these ingredients is then developed based on an optimization process, including consideration of the substrate ingredient?s particle size distribution.

Jan 1, 2011

By P. Trueman

A project is underway to convert a validated methodology to a system that will permit the near real time interpretation of loading data from longwall powered supports, allowing rapid adaptation of mining strategies, maintenance scheduling and set pressures for optimal roof control. Such a system has the potential to significantly reduce roof control problems and is a pre-requisite to successfully fully automating a longwall face. The development depended upon a robust methodology for interpreting the pressure sensor data coming from the face in the context of support strata interaction using a novel characteristic load cycle analysis concept. New software was developed capable of handling the large quantity of data emanating from a modern longwall with the current level of signal corruption and loss, accurately delineating load cycles and extracting the critical load cycle features essential for interpreting how the support and strata are interacting. Existing software being used to access the pressure data were found either to be incapable of delineating load cycles at all or, where they could, the accuracy was low, making it impractical to use them in combination with the new advances in load cycle analysis. The software is currently being extended from ?off line? to ?on line? in order to provide a real time response to changing strata conditions.

Jan 1, 2006

By G. Tamaro

The World Financial Center is situated on a 60,000 square meter site at Battery Park City at the southern tip of Manhattan Island. The foundations for the buildings and the related infrastructure posed difficult design and construction problems since the site was filled land in the Hudson (North) River. Foundation construction was made difficult by both the geology and the existence of two railroad tunnels which passed under the site. The soils at the site were unsuitable to support construction of heavy structures, and as a result, all of the foundations had to be carried down to bedrock, or the glacial till over rock. Two buildings were supported on piling and special battered caissons which provided lateral support against wind loading. The other two buildings were supported directly on rock, requiring excavation to depths of 19 meters (63 feet) below grade.

Jan 1, 1989

By J. A. Woolf, E. S. Leaver, A. P. Towne

"INTRODUCTION A report giving experiments dealing with factors affecting the floatation of the most commonly occurring silver minerals was published years ago. At that time we could not obtain suitable samples of many of the so-called sulfo-salts of the base metals, which are generally silver--bearing and which comprise an appreciable percentage of the natural silver ores. Since Leaver and Woolf's work was published, samples of impure tennantite and enargite have been obtained, and considerable experimental flotation work has been done with synthetic mixtures prepared from these samples. During the present national emergency, research dealing solely with the recovery of gold and silver must necessarily be curtailed. However, many deposits of strategic minerals and critical base metals contain an appreciable amount of gold and silver, the recovery of which would aid greatly in recovering the strategies by taking care of a considerable part of the cost of treatment. Because of this, the recovery of precious metals should not be overlooked entirely. As the Bureau of Mines is now utilizing all of its facilities for the development of increased domestic productions of strategic and critical minerals, this is the last report not concerned primarily with such minerals that will be published until the war ends."

Sep 1, 1942

By G. M. Potter, J. B. Rosenbaum, Masami Hayashi

Most Japanese copper smelters are located in areas of concentrated industrial activity and high levels of atmospheric pollution. A review of unofficial sulfur dioxide emission control data from major Japanese smelters shows capture of 91 to 99.7 percent of the sulfur in the smelter feed. The bulk of Japanese smel ting capacity was constructed in the last 10 years. Six of the major sme lters use flash furnaces, and two use reverberatory furnaces. A prototype three-furnace continuous system is in use as a parallel train with reverberatory furnaces at one smelter. Most of the sulfur dioxide is manufactured into sulfuric acid. The remainder is captured by gas scrubbers that yield gypsum and sodium salts. Ready markets exist in Japan for the acid and other su lfur byproduc ts.

Jan 1, 1967

By D Preedy, J K. Claflin, S R. La Brooy

A gold mine in north-eastern Africa has expanded throughput from 5 to 10 Mt/y in recent years. The original carbon regeneration kiln was incapable of achieving required throughput or meeting process conditions to reactivate the carbon due to heavy fouling by high molecular weight frothers and collectors. A new high temperature kiln was required.The design criteria for the carbon reactivation kiln and associated equipment were revised, then implemented in close cooperation with a kiln vender who had previously supplied kilns operating successfully on highly fouled carbon. The result is a whole facility, holistically designed to achieve the technical criteria.The new carbon reactivation facility has been operating since 1 July 2014. What have we learned? What has performed to expectations? What could be done better?This paper presents lessons learnt regarding the design, implementation, operation and maintenance of the Ausenco Carbon Reactivation Kiln. ‘Lessons’ are associated with threats and opportunities (risks) that have that have been realised. The importance of identifying and managing risks for even small straightforward projects is demonstrated.CITATION:Claflin, J K, La Brooy, S R and Preedy, D, 2015. Lessons learnt and performance – installing and commissioning an Ausenco carbon reactivation kiln in Africa, in Proceedings MetPlant 2015, pp 163–174 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 7, 2015

To reduce the respirable dust generated by auger-type continuous coal mining machines. The Approach: Use water sprays close to the cutting bits on the auger so that coal fragments are thoroughly wetted as they are formed to prevent dust dispersal into the ventilating air. How It Works: The "wet auger" system of dust control uses water sprays distributed on both shafts of auger type continuous miners. This approach has been tested underground by personnel of the Bureau's Twin Cities (Minn.) Mining Research Center on a Wilcox Mark 20 continuous miner, in a cost sharing contract with Buchanan & Sons Coal Company, Inc. Personnel of the Interior Department's Mining Enforcement and Safety Administration collected dust samples and analyzed the data. A test machine was fitted with six sprays on each auger (see Fig. 1). Water flow rates from 8 to 12 gpm at pressures from 90 to 120 psi, or about 8 gallons per ton of coal mined, were required. At these rates of water usage, mining personnel experienced no problems with work-

Jan 1, 1974

The evolution of surface mine layout configuration is a function of the schedules and sequence of material excavation within the optimized layouts. The production schedules and sequence of materials movement from multi-bench and multi-face operations are difficult to plan and execute. However, the ability to maximize the profit or net present value of an orebody is largely dependent on the mining schedule. The mining schedule will determine the life of the mine, the projected cashflows, and the investment requirements over the mine life. The pit geometries, pit expansion rates and the periodic volume of materials from different benches in a multi-bench, multi-face open pit mine determine the equipment requirements. The volume of materials excavated, as well as pit layout changes from circular and elliptical geometries of an oil sands mine were modeled using analytical geometric and parabolic partial differential equations (PDEs) and solved within Matlab. The results show that the geometric values are almost the same as those obtained from PDEs for different pit configurations. The economic analysis shows that both the current mining system (CMS) and the cyclic excavator conveyor belt control system (CycEx CBCS) are viable with high NPV (= $3.20 × 1010), PI (> 19%) and IRR (> 29.02%) with short discounted payback periods (= 3.24 months). The CycEx CBCS option is more economic than the CMS option. Its NPV is 1.27 times that of the CMS option. The PI and IRR for the CycEx CBCS option are respectively 2.24 and 1.13 times that of the CMS option. As well, the CycEx CBCS option has almost half the DPBP of the CMS option. The CMS option has an operating cost of $1.386 per tonne ($2.774/barrel) while that of the CycEx CBCS option is $0.779/tonne ($1.558/barrel). These results show that the CycEx CBCS option is the better option for mining companies working on oil sands deposits to invest in.

Jan 1, 2011

By Steve Kral

The Society for Mining, Metallurgy and Exploration’s origins can be traced back to 1871. This was when 22 Pennsylvania coal mining engineers founded the American Institute of Mining Engineers (AIME). The organization’s objective was to “promote the arts and sciences connected with economic production of the useful minerals and metals, and the welfare of those employed in those industries by all lawful means.” Metallurgy and Petroleum were added to the AIME name in 1919 and 1956, respectively. Divisions of AIME were formed throughout the following years in recognition of the increasing trend toward specialization among mineral industry engineers. At the time, SME’s divisions consisted of the Coal Division (1930, now known as the Coal and Energy Division), the Industrial Minerals Division (1935), the Mineral and Metallurgical Processing Division (1948) and the Mining and Exploration Division (1949). The Environmental Division was created in 1997.

Jan 1, 2007

A variety of environmental financial assurance instruments are in use across the globe. This paper reviews some of the more common forms currently used in New Zealand, Canada, USA and Australia. In order to be effective, the form of assurance instrument selected needs to be aligned with a countryÆs specific environmental objectives, geography and political climates and also allow for a healthy investment climate. Industry and Government both have a strong interest in ensuring financial assurance criteria meet these objectives.   Recently Golder Associates have been involved in financial assurance assessments for various mining and quarrying companies across the South Island. Multiple stakeholders and regulatory agencies can make the setting of effective and fair financial assurance criteria a complex exercise for both regulatory agencies and industry.  The author relates experience gained in assessing financial assurance under current New Zealand legislation (RMA, 1991), effectively dealing with issues such as ôdouble bondingö and overviews potential approaches to dealing with transitional issues for historic and existing operating mine sites.

Jan 1, 2006

By Brendan Donnelly, Jung-Hoon Sul, Lasitha Piyathilaka, Sanghyun Jeong, Benjamin Probyn

The chains of armored face conveyor (AFCs) are constantly in contact with water and wet coal, which results in a significant proportion of unplanned downtime experienced on longwall equipment due to corrosion. While reverse osmosis (RO) is one of the most prevalent water treatment methods for reducing salinity and dissolved solids in coal mining, its impact on the corrosion of the AFC chains has not been well studied. This work studies the direct effects of RO water on the corrosion of AFC chains. Immersion tests followed by surface micromorphology analysis and corrosion indices indicate that the RO water increased the corrosion rate of the AFC chains due to the reduced tendency of preventive films on the chains.

May 1, 2024

By A. M. Radigan, W. G. Prast

M.S. Azun The authors' paper did not explain the facts and reasons why state companies are established and what their role is in international industrial mineral trading. Also, I do not agree with the conclusion implying that the main goal for state companies is to capitilize natural resources. Almost all state companies are founded by certain laws and their activities are arranged by state regulations. Their only aim is to operate mineral deposits for their people and to protect the rights of the people. Although some ore deposits, such as nonstrategic or small, may be exploited by privately owned companies, the state has the right to control the operation and production. Activities of state companies may or may not be widened because of the character of the deposits and the importance of the mineral market involved. For some countries, although governments may occasionally change hands, the policy of the mineral trading system is not affected by this change. There is no doubt that any government desires to make more earnings to increase GNP, when it is involved in operating and trading mines. It wants to produce and sell the finished products, instead of unprocessed ones, if possible. When it is known that some mineral deposits are relatively rare, such as Turkish boron deposits, the government can nationalize the mines to control production and affect the market. If there is an abundance of a certain mineral in the market, the government can cut production and set a floor price, such as Canadian potash. Also, when production of a specific mineral is unique, such as Turkish chromite, the price of such mineral may be set by correspondant government. One may add that if some governments with their state companies produce a certain mineral in a larger amount, they may decide to establish a cartel to protect their production and price. These are the facts followed by government-owned state companies and partially government-owned companies. The reason being charge of many deposits by the state companies is always the same: "protect" the mineral rights of the people.

Jan 2, 1984