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The 1965 Lignite Symposium, the fourth in a series and the third sponsored by the University of North Dakota and the Bureau of Mines, was held at Bismarck, N. Dak., on April 29-30, 1963. Them 7 symposia provide a forum for those interested in the technology and utilization of solid fuels, especially lignitic coals. As part of the meeting, a 200-mile field trip was taken including inspection of (1) the 200-megawatt, pulverized Lignite-fired Leland Olds plant of Basin Electric Power Cooperative, under construction near Stanton, N. Dak.; (2) the site of the Glenharold mine of the. Truax-Traer Goal Co., Division of Consolidation Coal Co., where a wheel excavator was being assembled; (3) the operating Beulah mine of Knife River Coal Mining Co., subsidiary of Montana-Dakota Utilities Co., near Beulah, N. Dak.; and (4) the 400-megawatt, hydro-electric Garrison Dam powerplant, near Garrison, N. Dak.

Jan 1, 1966

The state of sampling practice in South African minerals industry must be appreciated in the context of the changes that the country has recently lived through. These include the entrepreneurship and investment in local mineral developments, the 'unbundling of mineral assets', the rising foreign control of South Africa's mineral assets, developments in the regulatory environment, and the training that has come to the industry through international experts. In terms of their financial contribution the five most important commodities in the South African mining industry include gold, platinum, non-ferrous metals, ferrous metals, and coal. International Organization for Standardization (ISO) standards form the basis for international trade in two of these commodities and have had a steadying influence on sampling practice over the years. The contribution of the minerals industry to the economic well-being of South Africa and the strong financial links between good sampling practice and minerals marketing, has acted as a driver for improved sampling practice. The state of sampling practice at mining operations of the five main commodities was found to be quite widely divergent with 'pockets of sampling excellence' in each of the commodities. The stages of mineral development at mines for each of the commodities have been described in terms of the sampling sites, sampling mechanisms, and associated problems at different stages of mineral production from exploration, through face sampling, blasthole sampling, and in-mine grade control, ore processing and handling, metallurgical subsampling, process subsampling, and subsampling in the laboratory. In each case the principal errors were identified and their potential impact on value erosion was estimated. In the final analysis it is evident that the greatest problems arise in the early stage of mineral development, and that ferrous metals and coal are particularly susceptible to loss of value through poor sampling practice. Several examples of value lost through poor sampling at the marketing stage that arise from breaching contract specifications, either in terms of grade or sizing, are described. The conclusion is that larger companies with larger ore deposits and greater human, financial, and capital resources are probably more compliant with 'best sampling practice' than smaller companies. Finally the message that equipment suppliers are sending is that business is booming and the awakened awareness of the issues around sampling practice are translating into rands and cents spent on improved sampling equipment.

Mar 1, 2010

By Yousef Ghorbani, Abolfazl Danesh, Fatemeh Kazemi, Ataallah Bahrami, Morteza Abdollahi, Mohammad Raouf Hosseini

This study aims to investigate the effects of operational variables on concentrate grade, recovery, separation efficiency, and kinetic parameters of the copper flotation process. For this purpose, the effects of the pulp solids content, collector and frother dosage, and preparation and concentrate collection time were studied using a Taguchi experimental design. The results of statistical analyses indicated that the concentrate collection time and pulp density were the most influential parameters on concentrate grade. Considering copper recovery, concentrate collection time, collector dosage, and pulp density were the most significant variables, in decreasing order of importance. Also, the separation efficiency was mostly influenced by the concentrate collection time. Furthermore, kinetic studies showed that the second-order rectangular distribution model perfectly matched the experimental flotation data. The highest kinetic constant of 0.0756 s−1 was obtained from the test, which was performed with 35% solids content and 40 and 20 g/t collector and frother, respectively. The highest predicted copper recovery of 99.57% was obtained from the test at 30% solids content, and the collector and frother dosages of 40 and 15 g/t, respectively

By W. R. Hardwick

This paper describes mining methods and practices of the Chino Mines Division, Kennecott Copper Corp., Grant County, N. Mex. It is one of a series being prepared by the Bureau of Mines on mining methods, practices, and costs in various mining districts of the United States. A similar program was conducted from 1928 to 1939, which helped to improve the efficiency of mining operations. The primary purpose of the program is to promote development and conservation of our mineral resources by disseminating technologic information on methods, practices, and related features in mining mineral deposits. It is expected that the program will: (1) Promote efficiency in operating mines; (2) assist operators and engineers in evaluating and developing new mineral deposits; (3) provide data for engineering curriculums in mining schools; and (4) furnish performance and cost data for revising engineering handbooks and for inclusion in engineering textbooks.

Jan 1, 1958

By Jorge Madias

O trabalho está baseado na análise de dados de perto de 200 fornos elétricos a arco de diferente design: convencional, de corrente contínua, de carcaças gémeas, com preaquecimento de sucata no transportador ou em shaft, etc. Incluem-se fornos que processam principalmente sucata, e fornos com carregamento parcial de gusa sólido ou líquido, ferro briquetado a quente (HBI) ou ferro esponja (DRI) a frio ou a quente. São avaliados os consumos de energia elétrica, oxigênio, gás natural e materiais carbonosos; os tempos entre vazamentos, com forno ligado e com forno desligado, assim como a produtividade horária. Com os dados obtidos, se analisa a influência dos metálicos (e seu estado térmico ao momento do carregamento), e o design do forno, sobre os consumos específicos mencionados e a produtividade.

Oct 30, 2017

By P D. "Takis" Katsabanis

The phenomenon of sympathetic detonations in blastholes is investigated by comparing experimental observations and numerical modelling results. Numerical modelling using the TDL computer code and Forest Fire decomposition rates for commercial explosives has shown the importance of blasthole diameter, impedance of the stemming and host rock. Comparison with experimental observations has also shown that sympathetic detonations cannot always be treated as shock to detonation transition. Examination of previous results which have been obtained from calibrated low amplitude shock experiments reveal that there is an ignition threshold prior to the detonation threshold. The difference between the two thresholds is more pronounced in the case of air bubble sensitized products. The ignition threshold can be very important under the confinement provided by the blasthole and the conditions of application. It also correlates well with the pressures expected at the gap distances of interest in the practical application. It is suggested that critical energies are used as the criterion for cross initiation in blastholes. Practical suggestions based on the numerical calculations and experiments based on these calculations are also given and discussed.

Jan 1, 1991

The object of this talk is to bring before members the importance of the prospector and the' State Battery system to the wealth and prosperity of the mining industry in particular and the State of Western Australia in general, and to touch on the more important features.Customs plants of any sort are usually subject to a good deal of critioism, usually on the large profits made at the expense of the customer, etc., and this often clouds the real value of the work being done.Prospectors, on the whole, are a good class of men; they work under conditions and difficulties which would deter those less spirited. Food, water and mining supplies are often difficult to obtain and frequently have to be transported great distances. Their mining tools are usually of the most primitive type, yet during last year over 109,000 tons of prospectors' ore were handled by the State Battery system for 73,250 fine oz. valued in Australian currency at over £587,000, the value being 57/- per long ton at par.This production brings the State Battery system into fourth position amongst the producers of the State, the yield being exceeded by the Lake View and Star, Wiluna and the Great Boulder.In passing I might mention that these notes were written at the end of the year 1940, and the above figures were for the previous period. The figures for last year, 1940, were not quite so good, being 101,000 tons for approximately 60,000 fine oz., valued in Australian currency at £572,000.In spite of this drop the State Battery system maintained its position as fourth in order of gold output for the State.The extractions, as a whole, throughout the system, were 92·54%, made up of 68·86% by amalgamation and 23·68% by cyanidation. These figures, for a group of 20 plants treating widely different classes of ore, must be considered satisfactory. The total production since inception is over £11,000,000 in Australian currency.State Batteries are usually more or less of a standard design. Ore is reduced to about 2i in. maximum size before being sent to the bins. Challenge automatic feeeders control the feed to each mill unit, amalgamated copper plates collect the free gold. Corduroy strakes are used with some ores after amalgamation, but in only a few cases has this been found of any advantage to the customer.The pulp from the battery is sampled, after leaving the tables, with a "Tazewell" sampler and pumped to dams for subsequent cyanide treatment.The "Tazewell" sampler is a machine driven by the moving pulp; and takes about fifteen dips per .minute from such pulp through a slotted...

Jan 1, 1941

By S. D. Hill, G. E. McClelland

To maximize productivity and improve minerals processing technology, the U. S. Department of the Interior, Bureau of Mines, is investigating a particle agglomeration technique as a means of increasing the percolation rate of leaching solutions through heaps of clayey or finely crushed, low- grade, gold-silver ores. Bench-scale and pilot-scale experiments conducted on different ores indicated that the percolation rate of cyanide leaching solution was enhanced markedly by mixing the ore with a binder, such as lime or portland cement, moistening the mixture, then mechanically agglomerating and aging the feed prior to heap building and leaching. In addition, the rate of silver and gold extraction markedly increased without sacrificing total recovery of values. The use of concentrated cyanide solution instead of water during the agglomeration procedure substantially decreased the leaching time required to obtain maximum recovery. Results from bench-scale and pilot-scale experiments using the particle agglomeration technique are discussed.

Jan 1, 1981

By K. Mallikarjuna Rao

There are several methods available to estimate deflection and ultimate Capacity of laterally loaded piles. In this investigation an attempt has been made to verify the existing methods for prediction of ultimate lateral resistance and deflection with the laboratory and field test results reported in the literature. A 75 pile loading test data obtained from the literature was used to evaluate two methods designed to predict the ultimate lateral resistance of rigid piles and three methods designed to predict the lateral deflections of rigid piles and four methods designed to predict the lateral deflection of flexible piles subjected to lateral loads. The accuracy and precision of each method is quantified statistically. The statistical results of the overall analysis indicate that the mean values of the ratios of predicted to measured lateral capacities vary from 0.62 to 1.14 with an average of 0.88. However, the settlement predictions were much more widely scattered than the ultimate load predictions and in general all the methods have a tendency to under predict the deflections. A new method is proposed by modifying the Broms's method to estimate the lateral deflections of free headed rigid and flexible piles separately. The proposed modified methods were found to be reasonably good in comparison to existing methods and to overestimate deflections.

Jan 1, 1996

By Kerry Spickelmier

The only nickel smelter and the only active nickel mine in the United States is Glenbrook Nickel Co., a joint venture (50% each) of Cominco Resources International Ltd. and Cominco Ltd. In 1989, with the nickel price riding high between $2.30 and $2.70/kg ($5 and $6/lb), Glenbrook seized the opportunity to purchase and recommission a southwestern Oregon ferronickel smelter and the adjacent nickel-ore mine. This Douglas County site is only about 97 km (60 miles) due east of the Pacific Ocean, and California's border lies a similar distance to the south. Hanna Mining Co. had closed the operation in 1987. And the following year, the equipment had been largely stripped for salvage value. From November 1990 through August 1992, the mine supplied an average 5 kt/d (5500 wet stpd) of ore. Currently, with import ore supplying 40% of the smelter feed, the mine's daily tonnage averages 4.2 kt (4600 wet st). From November 1990 through August 1993, the mine has delivered 2.1 Mt (2.3 million st) of ore grading 1.22% nickel with an average moisture content of 26%. Buffaloed nickel? A nickel is not worth what it was in 1989 and neither is ferronickel, with recent prices hovering around $1.13/kg ($2.50/lb). To survive, Glenbrook has focused on increasing smelter production to lower its operating costs. And this strategy has triggered several bold moves: • a new, $30 million, port facility and • a 10-year importation contract for ore from New Caledonia, an island approximately 1000 km (625 miles) east of Australia. For a Glenbrook update, a May 25, 1993 visit was made to the company's Oregon operations - the mine and smelter near Riddle plus its new Coos Bay port facility. Unfortunately, as the rain came down that day, so did news of another temporary shutdown. The previous suspension had lasted from Dec. 20, 1992 until Feb. 22, 1993. Barely three months back to work on a wet May afternoon, more than 250 of Glenbrook's approximately 300 employees contemplated yet another shutdown, effective July 31, 1993.

Jan 1, 1993

By Eugene Frey

"INTRODUCTION The Iron Mountain deposits were examined in the summer of 1943 by engineers of the Bureau of Lanes, and a diamond-drilling project was set up under the Strategic Minerals Program. Actual drilling operations, under the supervision of a Bureau engineer, commenced November 9, 1943, and were completed on November 1, 1944. When the Bureau began detailed exploration of the Iron Mountain deposits, the Federal Geological Survey participated. Dr. I. W. Newhouse, of the Survey, and Dr. A. F. Hagner, of the Wyoming Geological Survey, were assigned to the investigation.ACKNOWLEDGMENTSIn its program of exploration of mineral deposits, the Bureau of Mines has as its primary objective the more effective utilization of our mineral resources to the end that they make the greatest possible contribution to national security and economy. It is the policy of the Bureau to publish the facts developed by each exploratory project as soon as practicable after its conclusion. The Mining Branch, Lowell B. Moon chief, conducts preliminary examinations, performs the actual exploratory work, and prepares the final report. The Metallurgical Branch, R. G. Knickerbocker, chief, analyzes samples and performs beneficiation tests. Both these branches are under the supervision of Dr. R. S. Dean, assistant director.With respect to this report, acknowledgment is made to S. R. Zirrmerley and F. T. Allsman, Bureau of Mines, Salt Lake City, Utah, who supervised the work of this project."

Nov 1, 1946

By Deren Zhu

Based on the results of in-situ observations and physical model analysis, a computer simulation method, FEAEBP, has been developed to predict the behaviors of main roof breakage in longwall mining by considering it as a Kirchhoff plate on Winkler elastic foundation. This method in used to investigate the initiation, and development of the breaking process of main roof and its displacement field before and after its breakage. In this paper the simulation method is introduced, characteristics of the displacement field of the main roof is discussed and monitoring variation of the displacement field of the main roof in a Chinese longwall face is demonstrated.

Jan 1, 1989

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

TIMBER supports for large underground cavities are temporary expedients until the permanent filling can be put in. Nevertheless, timber supports are very necessary in some form. The general problem is to support the cavity in all directions withthe minimum of timber, disposed in the strongest way. The simplest way of filling an irregular space with timber sets is to form triangles.The right-angled isosceles triangle (Fig. 1) leads to the true square set, in which caps are equal to struts. The right-angled unequal-sided triangle and the scalene isosceles triangle (Fig. 2) lead to the oblong square set, where caps are longer than struts.The scalene triangle (Fig. 4) leads to the rhombic or oblique set. The equilateral triangle leads to the hexagon set (Fig. 3), in which the caps and struts are all equal. These five plane figures, the triangle, square, rectangle, rhomb and hexagon, are the only figures that will completely fill any irregular plane figure, without interstices. Hexagon sets were first suggested by the writer in 1902 to a mine manager at Broken Hill, who did not see his way to use them.

Jan 1, 1912

The paper deals with the importance of design and of codes of practice in ensuring safe working conditions in mines. The design principles involved in the design process are dealt with, and the importance of a logical design process is emphasized. The links between the requirements for developing a code of practice, embodied in the existing guidelines for the preparation of such a code, and the design principles and process are considered in some detail. Finally, suggestions are included, which may provide improvements to the code and hence, ultimately, lead to further improvement in safe working conditions.

Jan 1, 2004

By Scott Thayer, Michael Murphy, Natalie Cope, Gabriel Esterhuizen, Anthony Iannacchione, Tim Miller, Brent Slaker

"The Subtropolis room-and-pillar mine extracts the Vanport Limestone (Allegheny Formation, Pennsylvanian System) near Petersburg, Ohio. Strata instability problems associated with excessive concentrations of lateral stress caused the mine operator to implement a change in layout design. This mining method has been identified as a stress control layout, which has been used by other underground stone mines in the past with varying degrees of success. Practical experience has shown that entry headings advance in the direction of the principal lateral stress, producing lower stress concentrations with better mining conditions. It is important to minimize stress concentrations along the mining front, so an arrow-shaped advance is recommended. This technique advances more developments (headings) in a “good” direction and reduces developments (crosscuts) in a “bad” direction. As is expected, the stress control layout enhances the potential for shear failures in crosscuts. It is, therefore, important to focus crosscut engineering interventions that either: (a) lower stress concentrations (for example, an arched roof) or (b) enhance strength of the strata containing the shears (for example, rock reinforcement). This study focuses on observing strata conditions on a regular basis and monitoring the response of this strata to changing geologic and mining conditions through 3D Dynamic LiDAR scans.INTRODUCTIONProject AimsThe Subtropolis Mine is extracting the Vanport Limestone in northeastern Ohio. Since the start of mining in 2006, ground conditions have been significantly affected by excessive lateral stress condition. In some other mining districts with this hazard, certain mine layouts have been shown to lessen the potential for unstable ground conditions. The term “lessen” is used to state the realization that stress concentrations are not eliminated but instead occur in less frequency and intensity, and their locations can be projected.The stress-control mine layout, specifically for large-opening room-and-pillar stone mines, naturally evolved at mines suffering from excessive lateral stress problems. These mines will typically experiment with methods to mitigate adverse impacts, thus developing best practices for their conditions. These practices have evolved into a basic framework for the stress control mine layout. For example, Jack Parker was able to write about personal experiences at the White Pine Mine in Michigan (Parker, 1966, 1973). Various researchers at the U.S. Bureau of Mines (USBM), the Mine Safety and Health Administration (MSHA), and the National Institute for Occupational Safety and Health (NIOSH) have studied the effectiveness of stress-control mine layouts over a wide range of geologic conditions (Emery, 1964; Mark and Mucho, 1994; Iannacchione et al., 2003). While the stress control layout design approach has proven successful in many categories, it can be difficult to implement. For example, excessive stress conditions in crosscuts can put the ground control focused intervention at odds with ventilation and haulage constraints, thus limiting optimal crosscut size, shape, and location. Therefore, more information on the effectiveness of this approach is needed."

Jan 1, 2019

By R. W. Baker

"The development of uppers drilling at Brunswick Mining is reviewed. This paper describes design criteria for drilling patterns and the research required for selection of a suitable drill jumbo. The success of the uppers drilling program based on operating procedures is highlighted. IntroductionBrunswick Mining and Smelting Corporation Ltd., operates a 10 500 tonnes per day lead /zinc/copper I silver underground mine some seventeen miles southwest of Bathurst, New Brunswick .The No. 12 orebody, first discovered in 1952 by a group headed by M.J. Boylen, had extensive development, including two shallow shafts (500 ft), and test work carried out on it by St. Joe Lead between 1953-1957. However due to complex metallurgy and depressed metal prices, the operation was suspended.In 1961, a group comprised of M.J . Boylen, K.C . Irving and Patino acquired the rights of St. Joe Lead to the No. 12 property. A concerted development plan was initiated along with construction of the necessary sur face facilities and by July 1964, the property was in production at 4500 tons per day.In 1967 Noranda Mines Ltd. acquired operating control of Brunswick Mining and Smelting Corporation Ltd."

Jan 1, 1988

By W. M. Pytel

The applicability of the beam theory in analysis of roof- pillar-weak floor interaction in partial extraction room-and-pillar mining is presented. The mine structure is modeled as an equivalent multi-indeterminate overburden elastic beam supported by elasto-plastic pillars; resting on a viscoelastic layer of immediate weak floor strata underlain by a competent rock mass. The developed analytical model was initially utilized to conduct sensitivity analyses of different variables affecting the mining system, such as the deformability of coal and weak floor strata, thickness of weak floor strata, number of pillars in a panel, width of pillars, width of panel etc. These analyses were then extended to three overburden strata - coal pillar - floor strata lithologies typical of active coal mining areas in Illinois.

Jan 1, 1989

By B. P. Watson

The first crush pillars on the Bushveld platinum mines were introduced at Union Section in 1978. Before the introduction of crush pillars, serious problems were experienced when stoping advanced to a point 30 m to 40 m on both sides of the centre gully. At least three to four stopes were collapsing per month. The introduction of the pillars stopped the stope collapses in the mining area where they were introduced. The residual stresses of these pillars were never measured; however, the successful elimination of the ?back-break? problem suggests that the original pillars had a residual strength of at least 8 MPa. Apart from back analyses, very little work has been done to determine the residual strength of crush pillars and only very recently have any measurements been made. The lack of knowledge in this field has resulted in pillars being designed based on experience. Concerns about stope collapses, similar to the Coalbrook disaster, have led to larger pillars being cut in more recent times. If such pillars were cut in brittle quartzites they would always fail violently but the ductile nature of the Merensky Reef generally allows large pillars to fail without bursting. Occasionally, however, one would burst in a working area. Increased incidence of bursting has been reported on some mines at deeper levels but most of these bursts occur in the back areas. Nevertheless, the incidence of bursting increases the risk of falls of ground in already dangerous areas, and the larger pillars decrease the extraction ratio. This paper describes the evaluation of stress measurements conducted in two boreholes over a crush pillar with dimensions 2.5 m x4.0 m, and a height of 1.2 m. Boussinesq equations for vertical and shear stress were used to analyse the original measurements and provide a stress profile across the pillar as well as the residual strength of the pillar. The results showed an unexpectedly high peak stress of 280 MPa at the centre of the pillar and a residual strength of 48 MPa. The reason for the high residual strength is suspected to be the result of the stiff environment under which the pillar failed and the small height of the siding on the up-dip edge of the pillar. More measurements should be conducted on several mines to establish a range of residual strengths for narrow crush pillars.

Jan 1, 2008

By E. D. Gardner

Open-cut mining of copper ores in the western United States is a relatively new industry. At first the mining methods were mainly adapted from those used at open-cut iron mines and at quarries, but now efficient practices that are more suitable for the copper deposits have been developed. The pioneer in this field is the Utah Copper Co., of Bingham, Utah, which deserves great credit for working out much of the early procedure. Stripping began at that mine in 1906, and the large Garfield concentrator was put in commission in 1908. Next in order of development were the Nevada Consolidated Copper Co., at Ely, Nev. ; the Chino mine of the Ray Consolidated Copper Co., at Santa Rita, N. Mex. ; the New Cornelia Copper Co., at Ajo, Ariz. ; the Sacramento Hill mine of the Copper Queen Branch, Phelps Dodge Corporation, at Bisbee, Ariz.; and the open cut of the United Verde Copper Co., at Jerome, Ariz. The Sacramento Hill mine began to produce in 1923, and the United Verde open-cut mine has produced ore mainly in connection with stripping. The writer visited the Utah Copper mine in September, 1923; the Nevada Consolidated in August, 1923; the Chino in July, 1924; and the New Cornelia, the Sacramento Hill, and the United Verde open cut at various times during 1922, 1923, 1924, and 1925, mostly in connection with other work.

Jan 1, 1927