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By Sanjeeva Latchireddi, Travis Orser

"Today’s high capacity semiautogenous grinding (SAG) mills expend vast amounts of energy and in doing so consume tons of shell liners and steel balls, while processing ore. The energy efficiency of these high throughput grinding mills can be attributed to the field of breakage and slurry discharge system. The charge motion and breakage of particles inside the mill depends on the shell lifters design, while the discharge of ground particles is controlled by the grate and pulp lifters. The limitations imposed by poor grate and pulp lifter design become increasingly apparent with increasing size of ag/sag mills and their operation in closed circuit. The design of these mill components has been largely based on trial and error and hence varies considerably between manufacturers. This paper discusses the use of two state of the art design tools - Millsoft™ and FlowMod™. Millsoft™ is an effective tool to design the shell lifters and optimize charge motion, whereas FlowMod™ simulates the slurry discharge system to design grate and pulp lifters. The application of these simulators will be discussed using case studies of full scale mills.INTRODUCTIONMany large mining operations around the world have one or more semi-autogenous (SAG) mills doing bulk of the work in their size reduction operation. The SAG mill is usually followed by a ball mill to finish the size reduction prior to the concentration step. In the past when primary, secondary and tertiary crushers fed material directly to large ball mills, the energy efficiency of the concentrator was determined for the most part by the ball mill operation, whereas now the energy efficiency of a plant often rests largely on the SAG mill operation. As a result mines have shifted their emphasis in optimization from ball mills to SAG mill"

Jan 1, 2005

By A. Brown

"The mining industry is no exception to the general rule that continuing research is essential to good management; in fact, because of the imperfect state of knowledge in regard to many important factors associated with a mineral extraction, mining research assumes a position of unusual importance. On the basis of a recent visit to mining research centres in a number of European countries, the author describes their organization and their role in the mining industries of these countries. Some observations are made on Canadian mining research efforts, with a view to indicating a more systematic basis of procedure."

Jan 1, 1960

By Albert L. Toenges

A phase in strip mining of bituminous coal is the overturning of the surface of the land. The ;purpose of this report is to acquaint the operators and others interested in stripping with the work that has been done in certain States to reclaim the surface of land from which the coal has been removed by this method of mining. The preparation of this manuscript follows an extensive study of the subject in the field in the course of which a large number of strip mines were visited. ACKNOWLEDGMENTS The information used in the report was obtained through the courtesy and cooperation of the operators of the mines visited, State officials and educational institutions, and others interested in the subject.

Jan 1, 1939

By George S. Rice

"The author was a member of a Commission sent by the Secretary of the Interior to France to investigate developments in mining and metallurgy under stress of war conditions, and also to observe the extent and character of the destruction of the collieries and the steel and iron plants, and methods which were being taken to reestablish them. This commission consisted of F. G. Cottrell, Chief Metallurgist of the Bureau of Mines, Frank H. Probert, Dean of the University of California Mining School, and George S. Rice, Chief Mining Engineer of the Bureau. While conducting this investigation a trip was made to the Saar Basin to observe the conditions there. Following this Mr. Rice acted as advisor on mining matters to the Representative of the Economic Council in an Interallied conference held at Cologne in April 1919, and subsequently visited the mining districts in central and southern France, Belgium, and Great Britain.The Germans, in planning a campaign for world supremacy, had as one of their first objectives the seizing of the important Briey iron ore deposits of France and the coal fields of Belgium and northern France.Large resources of coal and iron have led to the commercial greatness of the countries possessing them, as exemplified by the great development first in England then in the United States, and in Germany when the minette high phosphorus iron ores became useful through the invention of the Thomas and Gilchrist dephosphorizing process in 1878. However, this development was anticipated by the German scientific advisors in 1871, and led to the then known deposit of minette ore in Lorraine being taken from France by Germany.When these ores became available, Germany made such tremendous strides that its minette ore developments were not sufficient and importation of ore was necessary. Meantime France, by drilling, had established the extension of the minette ore field into French Lorraine. Then it was discovered that France had greater resources, while the German resources were being rapidly depleted.Although Germany, in its Westphalian basin, possessed the most important coal field on the Continent, containing the largest resources in coking coal outside of Great Britain, its coal was distant from the sea coast, so it could not be an important factor in the export business. No doubt this fact caused the German Imperialists to look forward: to securing the coal basin of Belgium and northern France for future ocean trade.It was a striking feature in the German conduct of the war that, although the steel and iron plants of Belgium and France and other industrial establishments in the invaded regions of Belgium and France were utterly destroyed, the iron mines in French Lorraine were not destroyed nor materially damaged by the Germans in their retreat, while the destruction in France continued until the day of the Armistice. The other striking fact is that the coal mines Of Belgium were not destroyed. It can only be conjectured whether this was due to President Wilson's threat of retribution, which did not stay their hand in France, or was due to the fact that they did not consider Belgium as a real competitor. It was evident they wished to cripple France industrially when they could not hold these northern provinces."

Dec 1, 1919

[This is the sixth in a series of reports on properties of commercial motor fuels, made in accordance with a cooperative Agreement between the Cooperative Fuel Research (C.F.R.) Committee and the Bureau of tines of the Department of the Interior. The first report gave data on motor gasolines sold during the winter of 1935.-36.3/ The present report cover brands of gasoline represented by 1,490 samples plus thus: from the Pacific Coat, which ;sere averaged by the Pacific Coast Technical Group before being submitted and are published exactly as they were submitted. In some areas reports were received from 8 to 10 companies on the same brands of gasoline, Whereas in other areas only one Company reported on a brand. Thus, it can be seen that soma of the data are more representative than others. The inclusion of data from several cities within some of the districts has improved the report by reducing the number of brands reported by only one company. Severe changes have been made in the districts. A new district, Memphis, Tenn., has been formed to include Arkansas any western Tennessee. The Rocky Mountain area, have been divided into three sections. Salt Lake City and Denver form the Middle Rocky Mountain district; Laramie, Wyo., Idaho, Montana, and. Spokane, Wash., are included in the North Rocky Mountain district, and Arizona, New Mexico , and El Paso, Tex., have been combined to represent the South Rock Mountain district. The Cleveland district has been expanded to include Ohio ant. Indiana. Eastern Pennsylvania, Maryland, and northern Virginia are included in the Washington (D. C.) district. The Atlanta district includes Georgia, South Carolina; Mississippee, and northern Florida.]

Jan 1, 1938

By A J. H Newell

The background and the basis for conducting a Technical Due Diligence are discussed as well as the source information, typical studies and potential limitations. Typical short comings including ‘show-stoppers’ are presented for the metallurgical area, with examples. Issues found in other areas such as geology, mining, infrastructure and financial evaluations are briefly reviewed, highlighting the input and interaction required by metallurgists with these disciplines. A checklist is provided as a guide to maximise the success of a Due Diligence as well as a check on the quality of a Feasibility Study.CITATION:Newell, A J H, 2015. Fatal flaws in technical due diligences, in Proceedings MetPlant 2015, pp 61–77 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 7, 2015

By Larry A. Haas

The U.S. Bureau of Mines is investigating ways of enhancing the high-temperature softening-melting (HTSM) properties of domestic taconite pellets. These properties, which are important for determining the performance of pellets in blast furnaces, include pellet bed contraction, pressure drop, S-value (area under the pressure-temperature curve), and softening and metal-slag drainout temperatures. Experiments showed that HTSM properties were related to the physiochemical properties (fired strengths and reducibilities) of pellets containing different levels of limestone and dolomite flux. Flux additions resulted in slightly lower green and fired pellet strengths, but improved metallurgical properties, such as reducibility. The influence of reduction conditions on HTSM properties was evaluated by varying the pellet metallization starting temperature and the carbon monoxide content of the CO-N2 gas mixture. HTSM property change was more sensitive to flux addition levels when metallization was initiated at 1,100° C with 20 pct CO in the gas stream. The S-value and the metal-slag drainout temperature were found to be the best criteria for characterizing HTSM properties. The optimum flux addition level was about 8 pct (4 pct dolomite, 4 pct limestone) or a basicity of about 1. At higher flux levels, a higher metal-slag drainout temperature was obtained.

Jan 1, 2010

By Jerry C. Tien

Without a doubt, the scope of China?s coal boom has been nonstop. Despite the world economic slowdown, China?s year-on-year gross domestic product (GDP) jumped 10.3 percent year-on-year in 2010, boosted by a faster than expected 9.8 percent expansion in the fourth [ ] quarter. And, the first quarter of 2011 expanded another 9.7 percent. According to a frequently cited statistic, the country is building two mid-sized coal plants each week. This amounts to a yearly increase equivalent to the entire power grid in the United Kingdom. China?s coal production was doubled in the last 10 years, from 1.044 Gt (1.15 billion st) in 1999 to 3.2 Gt (3.52 billion st) in 2010. This is 3.2 times the U.S. production (986 Mt or 1.085 billion st) and nearly half (46.3 percent) of the world?s total coal production (6.91 Gt or 7.6 billion st). This rapid increase of demand for coal has made China the world?s largest coal importer in 2009. With the economic situation improving, this trend is expected to continue.

Jan 1, 2011

By A. C. Stevenson

THE hoisting equipment selected for use at the Hecla mine in 1907 was one of the first Ilgner type Ward-Leonard controlled hoists put into ser- vice. Development of the Hecla below the 2000-ft. level, which is the ultimate depth of the old equipment, and the additional service required by the "Star," necessitated additional hoisting capacity. It will be our endeavor to give j70u a brief summary of the engineering which determined the selection of the new equipment. The engineer in making his decision as to size, speed, etc., must .make a duty study approximating as closely &s possible the actual opePating conditions which will eventually result. Primarily, it is necessary to know what work must be done. The amount of material which must be hoisted under the maximum condition, as well as its distribution from the various levels of the mine was carefully studied by the mining engineering department, as the ore reserves, their relative-position and the probable method of working them had to be considered. The final figures reached, taking into consideration four different operating conditions, were, in tons per day, as follows:

Jan 1, 1930

By R Berry, N Bonnici, K Nguyen, S G. Walters, M Kamenetsky, C L. Evans

Mineral maps produced via optical and scanning electron microscope û mineral liberation analyser (SEM-MLA) automated mineral identification systems are being used to examine the relationships between mineral phases in spatially well-constrained samples of intact and crushed rock. The use of sophisticated image analysis software allows data pertaining to individual or groups of mineral phases to be extracted from the mineral maps. Analyses of the extracted data can be used to identify populations of phases. Data extracted from the images can be compared with mineral processing data, eg hardness, grindability, degree of liberation, from the same sampling intervals, enabling ore characterisation to be linked to processing behaviours in a spatially constrained, quantified manner that can potentially assist with mine planning and optimisation.

Jan 1, 2008

By T van Niel, M Trefry, B Baker, I Rea, A Hawdon, D McJannet, D Boadle, R Fandrich, A Littleboy

Many open cut mines extend to depths well below the natural water table level with constant dewatering required to maintain operations. When mining activities cease the groundwater starts to fill the void and pit lakes form. The resultant pit lake is directly connected to the surrounding water table and understanding the hydrological and chemical evolution of these lakes is important for minimising environmental impacts. In Western Australia alone there are currently 1800 mine voids and more than 150 mines operating below the water table (Johnson and Wright, 2003). In conjunction with BHP Billiton Iron Ore, CSIRO has been undertaking research to measure and model rates of evaporation from pit lakes in the Pilbara region of Western Australia. Extreme high temperatures and low humidity ensures that this region experiences the highest evaporation rates in Australia.CITATION:McJannet, D, Hawdon, A, Boadle, D, Baker, B, van Neil, T, Littleboy, A, Trefry, M, Rea, I and Fandrich, R, 2016. Measurements and modelling of evaporation from abandoned mine pit lakes, in Proceedings Life-of-Mine 2016 Conference, pp 106–109 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jun 28, 2016

This is the sixth in a series of reports on properties of commercial motor fuels, made in accordance with a cooperative agreement between the Cooperative Fuel Research (C.F.R.) Committee and the Bureau of Mines of the Department of the Interior. The first report gave data on motor gasolines sold during the winter of 1935-36.3/ The present report covers 54 brands of gasoline represented by 1,480 samples plus those from the Pacific Coast, which were averaged by the Pacific Coast Technical Group before being submitted and are published exactly as they were submitted. In some areas reports were received from 8 to 10 companies on the same brands of gasoline, whereas in other areas only one company reported on a brand. Thus, it can be seen that some of the data are more representative than others. The inclusion of data from several cities within some of the districts has improved the report by reducing the number of brands reported by only one company. Several changes have been made in the districts. A new district, Memphis, Tenn., has been formed to include Arkansas and western Tennessee. The Rocky Mountain areas have been divided into three sections. Salt Lake City and Denver form the Middle Rocky Mountain district; Laramie, Wyo., Idaho, Montana, and Spokane, Wash., are included in the North Rocky Mountain district, and Arizona, New Mexico, and El Paso, Tex., have been combined to represent the South Rocky Mountain district. The Cleveland district has been expanded to include Ohio an,"- Indiana. Eastern Pennsylvania, Maryland, and northern Virginia are included in the Washington (D. C.) district. The Atlanta district includes Georgia, South Carolina; Mississippi, and northern Florida.

Jan 1, 1938

By Albert L. Toenges

A phase in strip mining of bituminous coal is the overturning of the surface of the land. The purpose of this report is to acquaint the operators and others interested in stripping with the work that has been done in certain States to reclaim the surface of land from which the coal has been removed by this method of raining. The preparation of this manuscript follows an extensive study of the subject in the field in the course of which a large number of strip mines were visited. ACKNOWLEDGMENT The information used in the report was obtained through the courtesy and cooperation of the operators of the mines visited, State officials and educational institutions, and others interested in the subject.

Jan 1, 1939

By G. K. Rogers

The portal, which is the near-horizontal, surface point of entry to an underground excavation, can often be an exceedingly difficult area in terms of ground control. Surface and subsurface failures at portals, as discerned during a study involving over 300 case histories, are unfortunately, common. To aid in the engineering evaluation of portals, the Geomechanics Classification System was appended with discontinuity orientation assessment values and support/excavation guidelines. Also, a design model utilizing RMR predicted rock loads in conjunction with half-dome theory is proposed for the most common type of portal failure. Other pertinent comments and recommendations relating to portal stability are included.

Jan 1, 1989

By William C. Cooley

A literature search and survey were prepared on the technology of surface hydraulic mining, with particular reference to its possible use in the United States forstripping overburden from surface coal mines. Extensive use was made of Russian references which were translated into English. The advantages and disadvantages of hydraulic mining and hydrotransport are identified as well as criteria for selecting potential applications. At present, the major U.S. application is in the phosphate industry of Florida and North Carolina. Potential locations for hydraulic stripping of overburden from coal seams are identified in the states of Alaska, Illinois, Montana, Washington and Wyoming. Other potential applications include the hydraulic mining of peat in Minnesota, and the stripping of overburden from lignite in Texas, Montana, North Dakota and South Dakota. Further research is recommended, particularly on the subject of dewatering of fine clay slimes to avoid water pollution and to permit rapid reclamation of mined areas.

Jan 1, 1976

One of the seminal pioneering papers in reserve evaluation was published by Danie Krige in 1951. In that paper he introduced the concept of regression techniques in providing better estimates for stope grades and correcting for what later became known as the ‘conditional bias’. In South Africa, the development of this approach led to the phenomenon being dubbed the ‘regression effect’, and regression techniques ultimately formed the basis of simple kriging in Krige’s later papers. In the late 1950s and early 1960s, Georges Matheron (1965) formulated the general theory of ‘regionalized variables’ and included copious discussion on what he termed the ‘volume-variance’ effect. Matheron defined mathematically the reason for, and quantification of, the difference in variability between estimated values and the actual unknown values. In 1983, this author published a paper that combined these two philosophies so that the ‘regression effect’ could be quantified before actual mining block values were available. In 1996 and in some earlier presentations, Krige revisited the regression effect in terms of the conditional bias and suggested two measures that might enable a practitioner of geostatistics to assess the ‘efficiency’ of the kriging estimator in any particular case. In this article, we revisit the trail from ‘regression effect’ to ‘kriging efficiency’ in conceptual terms and endeavour to explain exactly what is measured by these parameters and how to use (or abuse) them in practical cases.

Jan 1, 2015

By Efrem R. Reeves, David C. Byrne

This study was conducted as part of a project involving the evaluation of a new type of noise exposure monitoring paradigm. Laboratory tests were conducted to assess how “nonstandard” dosimeter microphones and microphone po­sitions measured noise levels under different acoustical condi­tions (i.e., diffuse ?eld and direct ?eld). The data presented in this article re?ect measurement differences due to microphone position and mounting/supporting structure only and are not an evaluation of any particular complete dosimeter system. To varying degrees, the results obtained with the dosimeter microphones used in this study differed from the reference results obtained in the unperturbed (subject absent) sound ?eld with a precision (suitable for use in an ANSI Type 1 sound level meter) 1/2 -inch (12.7 mm) measurement microphone. Effects of dosimeter microphone placement in a diffuse ?eld were found to be minor for most of the test microphones/locations, while direct ?eld microphone placement effects were found to be quite large depending on the microphone position and supporting structure, sound source location, and noise spectrum.

By Doug Harding

The Niagara Tunnel Project (NTP) is a 10.4-km- (6.5- mile-) long, 14.4-m (47.5-ft) bored tunnel that will run under the city of Niagara Falls from the Upper Niagara River to the Sir Adam Beck power station. The completed project will enhance the capacity of the Sir Adam Beck power station by adding 500 m3 /sec (17,657 cu ft/sec) of water through the tunnel. The project uses the world?s largest hard-rock tunnel boring machine (TBM) at 14.4 m (47.5 ft) in diameter to excavate the tunnel. Features of the project include the use of a high performance (HP) main beam TBM, state-of-the-art ground support and tunnel logistics systems. A continuous conveyor is used for muck transport from the TBM to the disposal area In June 2004, the Ontario government announced that Ontario Power Generation (OPG) had been given approval to proceed with the third tunnel under the city of Niagara Falls ? the first two tunnels were constructed in the 1950s using drill-and-blast techniques. The third tunnel, appropriately named the Niagara Tunnel Project (NTP), consists of a 10.4-km- (6.5-mile-) long TBM-bored, concrete-lined tunnel with a finished diameter of 12.5 m (41.1 ft). In August 2005, OPG the selected of Strabag of Austria, one of the largest construction companies in Europe, as the contractor to build the NTP at a price of C$600 million. In September 2005, Strabag selected The Robbins Co. of Solon, OH to design, manufacture and deliver a new 14.4- m- (47.5-ft-) diameter high performance, state-of-the-art main beam hard rock TBM to be used in the excavation of the tunnel. To meet the aggressive construction schedule as requested by OPG/Strabag, the TBM needed to be sup-plied as ready-to-bore within a 12-month period after the contract was awarded to Robbins.

Jan 1, 2008

By A. M. Ouchi

Existing empirical design tools have been developed from fair-to-good quality rock masses (RMR76 >50). This paper presents a focus of ground control research presently being conducted by the Rock Mechanics Group in the UBC Mining Department in incorporating weak rock masses (RMR76 <50) into existing empirical design relationships. An emphasis is being placed upon the updated span design curve/critical span graph originally developed at UBC. The original database has been augmented with over 450 weak rock data points from mines such as the Stillwater mine (Montana), the Eskay Creek Mine (BC) and several mines in the Carlin Trend and other parts of Nevada. The original database is comprised of spans supported with ?traditional? mechanical bolting. In weak rock environments however, this type of support has been found for the most part, ineffective. This paper presents the span and weak rock RMR76 relationship for four different support categories. This work attempts to provide rock mechanic tools that will enable a mine operator to make economic decisions that will also ensure a safe working environment.

Jan 1, 2008

By Camila Oliveira de Souza

O material em estudo consistiu em um aço inoxidável austenítico 201LN, na forma de chapa com aproximadamente 5,00 mm de espessura na condição laminada a quente. As etapas de processamento adotadas neste estudo consistiram em laminação a temperatura ambiente e pré-resfriamento em salmoura, com o objetivo de avaliar a formação de martensita e evolução da resistência mecânica do material. As técnicas de caracterização utilizadas foram macro Dureza Rockwell C (HRC), Ferritoscopia e Difração de Raios-X (DRX). Os resultados preliminares mostraram que tanto a fração volumétrica de martensita formada, como a dureza, foram maiores nas amostras submetidas a maiores percentuais de redução e pré-resfriamento em salmoura.

Oct 30, 2017