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By S. Saeb, C. Francke

Introduction Although mining in one form or another has existed for millennia, the use of numerical methods for mine design is a relatively recent development. The basic physics that control the behavior of rock or soil have been known for centuries, but it wasn’t until the last half of the twentieth century that analytical methods that could accurately predict the behavior of a large, irregular rock mass were developed. Before the advent of modern computers combined with differential and integral analytical methods, numerical methods available to mining engineers were limited to closed form solutions for simple excavation geometries. Today, mine-scale three-dimensional stress analyses can be performed on a relatively inexpensive personal computer. Many of the recent advances in rock mechanics modeling are the result of research funded as part of nuclear waste repositories around the world. The large scale exacting performance requirements of waste repositories are frequently very different from traditional rock mechanics projects. These facilities are designed and built under tighter control and scrutiny because of the potential hazards they present to the public. Therefore, a great deal of research towards advancing rock mechanics and numerical modeling resulted from these projects. Much of the repository research is applicable to commercial mines. The advances in modeling programs have been paralleled by advances in computer equipment. Today, a moderately equipped personal computer can handle most mine geomechanical modeling projects in a reasonable period of time. While the learning curve varies, an engineer with modeling experience can develop a medium sized model in a few days. The relatively low investment cost of geomechanical modeling today makes it accessible to most mining operations. The benefits of a solid geomechanical modeling program include reduced operating costs, improved safety, and reduced design costs.

Jan 1, 2007

By Shibo Zheng, Zhengxing Gu, Zhizhong Gao

In recent years, beneficiation tests were conducted on high dolomite phosphate samples from Florida by the authors from China Lianyungang Design and Research Institute (CLDRI). The research results indicated that flotation is the most effective process for recovering phosphate from Florida high dolomitic pebble. Other operations like scrubbing, desliming and selective grinding might work to some extent, but they could only be applied as supplementary approaches in some cases. Heavy media separation and calcination-digestion technologies are hard to produce satisfactory performance. This paper presents the results of both lab scale and pilot plant tests on Florida high dolomite phosphate pebble using the fine particle flotation technology developed by CLDRI. Some discussions are made on the concerns of Florida phosphate industry and further research.

Jan 1, 2002

By P. Latostenmaa, T. Veneranta, J. Järvi, E. J. Peuraniemi

Boliden Harjavalta has operated a copper flash smelter since 1949 thus the smelter celebrates 70th anniversary of flash smelting in 2019. This paper shortly describes the historical perspective of the smelter and gives an update of the current operational issues and process modifications made during the recent years. The plant has carried out several major investments lately providing a firm view on the future. A new landfill area for the final slag was commissioned in 2018. A modernization of the concentrate storage area, a new acid plant and a debottlenecking project of the smelting line have been recently commissioned. At the same time, the tankhouse capacity will be expanded. This paper focuses on smelter modernizations. INTRODUCTION Boliden is a metal company operating mainly in northern Europe with core competencies in the fields of exploration, mining, smelting and metal recycling. Boliden Harjavalta, located in Finland, is part of the Smelters Business area of the Boliden Group and operates a copper and nickel smelter with related sulphuric acid plant in Harjavalta, and a copper refinery in Pori. As a short historical review, Harjavalta’s history may be dated back to the year 1910 when the Outokumpu ore body in eastern Finland was discovered. By the end of 1913, a copper mine was in operation and a copper plant based on Hybinette process was ready for commissioning. Due to difficulties in metal recoveries and throughput the Hybinette process was permanently shut down in 1929, and 100% of the mining production was sold as concentrate abroad. As the mine production increased steadily, a decision of a new smelter was made in early 30’s. In 1936 Outokumpu’s copper smelter based on electric smelting was commissioned in Imatra. The smelter was dismantled and transferred to Harjavalta during the final stages of the Second World War. The copper refinery started in Pori already in 1941 and the first copper anodes were cast in Harjavalta in 1945. First sulphuric acid plant started operation in 1947. Due to the post-war shortage of electrical energy, the plant metallurgists initiated a major development work to start exploiting the latent heat of concentrates. Thus, the flash smelting method was developed in Harjavalta and commissioned in 1949. Ten years later, flash smelting was also applied for nickel concentrates. Table 1 summarizes major historical and technical milestones of Harjavalta. The history of flash smelting is described in details in another paper of this conference (Jåfs et al., 2019).

Jan 1, 2019

By Hannu Johto

Boliden Harjavalta has operated a flash smelter for nickel sulphide concentrates in Finland since late 1959. The original nickel flash smelting process was modified in 1995 to a novel nickel matte smelting (DON) with semi-low iron where the batchwise operated converting became obsolete. Since that, the process has been applied to multiple chemically variable nickel sulphide concentrates with high environmental performance. In this paper, the status of the current smelter operations is described together with the recent modernizations of the nickel flash smelting furnace and the slag cleaning furnaces.

By William B. Schmidt

In July of 1974 a study team comprised of the authors was formed by the Department of the Interior. It was supported in part by funding from the National Science Foundation. The purpose of this study group was to visit coal mines and research and manufacturing facilities in England and Germany, to review the status of mining in these countries, and to identify mining technology which might have application to U. S. mining conditions. The duration of the visit was 18 days. The first week of the trip was spent in England. Time does not permit a complete recitation of the team's impressions but a few of the more interesting technologic developments will be discussed. These fall into the following categories- High Speed Development Ground Support Chainless Haulage and Face Conveyors Nucleonic Steering of Shearers Miscellaneous

Jan 1, 1975

By Charles Sanford, William B. Schmidt, Eugene Moroni, John Murphy, Richard Bullock

An industry/government team sponsored by the Dept. of the Interior completed a study tour of the underground coal mining industries in Great Britain and Germany to review new and emerging coal mining technology. The group found that differences in tradition, mining conditions, and industry capabilities have led to different approaches in technological developments, many of which have the potential for application in U. S. mining. Both countries are working to improve materials and procedures for roadside pack wall. The British are developing a pump-packing system in which bentonite, water, stone, and a special cement are pipelined to the pack area to form a low strength compressible pack wall. The German industry is using anhydrite or blotzdammer to form a high strength pack wall. Both countries are using full-face tunnel-boring machines. The German industry has had considerable success with shield-type longwall supports.

Jan 1, 1977

By F. T. Rabbitts

Introduction When the investigation of radioactive ores began at the Mines Branch about five years ago it was at once evident that improved chemical methods for the determination of uranium were essential. The published methods available were time-consuming and insensitive and were lacking in accuracy and precision. It was desirable to obtain methods which would be rapid, sensitive, and accurate. They should also allow for the possible presence of any interfering elements and should be adaptable to routine analysis by technicians. Chemical methods are necessary to provide standard analysed samples for counting and to check analyses by counter methods. Moreover, counter methods cannot be used, and only chemical methods are suitable, when the sample is not in equilibrium, as with weathered minerals and leach residues. As leaching processes are improved, more sensitive chemical methods are required for the increasingly lower content of uranium in the leached residues. When the leaching process reaches the plant stage, speed of analysis becomes more important, without sacrificing accuracy. The purpose of this paper is to describe briefly .the methods used at the Mines Branch for the chemical analysis of uranium in ores. These methods represent the results of investigations by a number of groups in the United Kingdom, the United States, and Canada.

Jan 1, 1952

By Ragnhild E. Aune, Mark William Kennedy, Shahid Akhtar, Jon Arne Bakken

"In the present study classical induction design tools are applied to the problem of heating nonmagnetic metal billets, using 50 Hz AC. As an example of great practical industrial interest, the induction heating of aluminum billets is addressed specifically. The predicted work piece power is compared with the measured work piece power for a long and a short coil, using well established methods, such as those of Burch and Davis, introduced in 1926/28, Dwight and Bagai in 1935, Baker in 1944/57, Vaughan and Williamson in 1945, and by Tudbury in 1960. A calculation methodology based on a combination of the available tools is also introduced and discussed. The method has proven to give an error of <10% of the actual work piece power. An equation for Tudbury's work piece shortness correction factor is disclosed for the first time.IntroductionInduction heating of metal billets is a practical problem, with a geometry suitable for solution using analytical methods. This paper will examine solutions related specifically to round work pieces in round coils, although the methods presented can be extended to other regular shapes of work pieces and coils[l]. The methods can also be extended to ferromagnetic materials with slight changes[2-3]. It is assumed that the coil and work piece have a consistent diameter over their entire length and that the work piece is at least as long as the coil. Correction factors can be derived for the cases where the work piece is shorter than the coil.The study of induction heating by coils began in the late 19th century with theoreticians like Heaviside[ 4]. The work of Burch and Davis[ 5-7] in the 1920' s greatly improved the theoretical understanding of induction applied to metallurgy. Many investigators in the 1930's-1950's: Dwight and Bagai[8], Baker[l-2, 9], Vaughan and Williamson[3, 10] and others[l 1-12] added to our understanding with clearer mathematics, solutions for specific applications, semi-empirical modifications and practical design tools. Much of the accumulated knowledge is available in books, such as Tudbury's practical text or Simpson's engineering guide from 1960[13-14]. Perhaps the best description and derivation of the theoretical and semi-empirical solutions can be found in Davies[15]."

Jan 1, 2011

By T. A. Lloyd

"This paper indicates the extent to which Canadian coal mine operators have taken advantage of developments in the science and technology of coal that would allow them to better satisfy changing market demands through improving the properties of their products. At some mines, no attempt is made to alter the coal from its as-mined condition, but at most mines grading into various size ranges and hand-cleaning of lump sizes is undertaken.Over-all, Canada Jags behind most of the other major world coal producers in the proportion of its coals being processed in wash plants. To some extent, this is due to the fact that a high proportion of the coal production satisfies market demands without such treatment. On the other hand, a few of the coal mines in Canada, which produce about 25 per cent of the nation's total coal output, have in operation some of the most modern coal beneficiating equipment available, including jigs, flotation cells, water cyclones, centrifuges, disc filters and thermal dryers."

Jan 1, 1968

By Gillies A. D S

The paper presents a review of research in the area of explosible coal dust with respect to safety in the underground mining environment. Research over the last several decades has concentrated on generating dust clouds in small scale laboratory explosion chambers to study flammability limits and the physical and chemical variables which affect explosion propensity. The validity of this approach is discussed and the results obtained for a range of coal types compared.

Jan 1, 1994

By M. M. Singh

Coal mine operators are obligated to mitigate or plan for subsidence under the new regulations. This paper presents the types of subsidence control measures that may be employed to meet these requirements, which include: changes in mining methods, strata stabilization after coal extraction, construction of specially designed surface structures and foundations to accommodate ground movements, and comprehensive planning and coordination of surface land use with underground mining. The basic principles of these techniques, along with specific procedures that may be followed to implement them, are briefly discussed. Subsidence control methods that are currently being investigated are mentioned.

Jan 1, 1985

By van der Merwem J. N.

"Coal pillars are prone to scaling over time, and are progressively reduced in size and consequently subjected to increased load and reduced strength. The effective factor of safety therefore reduces. Databases of failed and stable pillars cannot, therefore, be regarded as definitive.More than a decade has passed since the first attempt to predict the lifespan of pillars. This paper presents a review based on the new database and pillar strength equations. The methodology for the analysis is based on the fact that pillars scale. The ultimate safety factor (defined as the ratio between strength and load at the time of failure) is derived, followed by an estimate of the rate of pillar scaling, which results in an estimate of the expected time of failure.It is suggested that the predicted lifespan should not be used as an absolute indicator of expected pillar life, but rather as an index – the pillar life index (PLI) – to complement the safety factor and related probability of failure when evaluating pillar stability. A pillar with a predicted lifespan of less than 500 years would be regarded as being in danger of imminent collapse, while a lifespan of at least 1 000 years should be required for long-term purposes.The differences between this analysis and that published in 2003 constitute a strong case for regular reviews of all the empirically based stability indicators, namely the safety factor, probability of failure, and the PLI. Reviews at 10 year intervals appear to be required.The constants in the proposed method are valid only for the Witbank No. 1, 2 and 4 seams and the Highveld No. 2 and 4 seams.IntroductionIt is well known that over time, coal pillars are prone to scaling, and thus are progressively reduced in size and consequently subjected to increased load and reduced strength. The effective factor of safety therefore reduces and it is quite possible for failure to occur after a long time interval. In fact, scrutiny of the database of failed pillars indicates that failure occurred after periods ranging from 2 to 49 years, and not immediately after mining.The factor of safety for pillars at the time of failure is not the same as that immediately after mining. The concept of the safety factor is based on the pillar strength obtained by statistical analysis of pillar dimensions immediately, or within a month after mining, when the surveys are conducted. Strictly speaking, the safety factor as commonly used is valid only immediately after mining, and it continues to reduce thereafter. The ideal situation would be to base analyses of pillar strength on pillar dimensions at the time of failure, but that is simply not possible because the real dimensions cannot be measured at that time."

Jan 1, 2016

By George Rice

TEN years ago, October, 1914, the author had the privilege of giving an-illustrated address on investigations of coal-dust explosions1 to this Institute at one session of its fall meeting in Pittsburgh, Pa. On the following day, the members had the opportunity of seeing a large-scale explosion test at the Experimental Mine near Bruceton, in which the explosion was made to follow a predetermined path by means of rock-dust barriers of various types, which had prevented the explosive waves from reaching the outlets of, the mine by the shortest paths.2 There was also shown a "home-made rock-dusting machine discharging the dust from a flexible nozzle, and a cement gun operated for the quick erection of a fire or ventilation stopping, such as might be put up after an explosion. Following that paper, there was presented a paper by J. Taffanel, Director of the Lievin testing station in the Pas de Calais, which reviewed the French coal-dust investigations.3 Another important paper was by Howard N. Eavenson, on Coal-mine Explosions Caused by Gas or Dust.4 This paper contains complete lists of explosions that occurred in North America and Great Britain, from early in the 19th century to 1912; in France to 1903, and in Belgium to 1909. No one can look over these lists without being struck by the great number of explosions and the, appalling aggregate of lives lost by them. Although they still happen, we-are hopeful that we have entered on a happier period of freedom from these dreaded visitations, as the result of great increase in knowledge; of the causes and means of prevention. Looking back over coal-dust investigations, there appear to have been periods of advance and of stagnation.

Jan 3, 1925

By Ronald E. Hamilton

"An attempt to review the recent literature on comminution reveals at once that the subject has many ramifications and that the applications are so diverse that there are very few general statements which can be made.It. seems reasonable to start classification on the basis of size of material as Input to the comminution process. However, we find that this can only be done in a very imprecise manner.The initial step of breaking rock from its natural state of very large pieces in geological formations into sizes suitable for processing is accomplished by blasting. This step in the process has not been ex-amined in this project except to note that great changes have been made during the last decade or so in the explosives used, and in the method of handling them. We should determine what effect changes in mining methods can have on the need for crushing.The second step in the process is usually primary crushing, performed by gyratory or jaw crushers. The largest chunk which can be fed to a jaw crusher depends on the size of the machine, and should be larger than the largest fragment produced in the miring process. It is obvious that the larger the crusher, the less care required in mining to en¬sure the absence of rocks too large to be crushed. The optimum size of crusher to minimize overall cost of mining and reduction is not at all obvious, and no information on this point has come to light in this investigation.It is rather generally accepted that size reduction is most efficiently done in small stages, and that different machines have different opti¬mum size ranges of feed. For example, crushers are preferred for sizes above about 1"", rod mills for the range between 1"" and 0.1"", ball mills are preferred from 0.1""down to perhaps 10 microns, and vibratory mills, or jet mills, below 10 microns."

Jan 1, 1976

By W. M. Houston

Pebble phosphate deposits of Florida have been established from south of Hardee County to north of the Georgia state line or a distance of over 200 miles and mining has been carried out in an ever-increasing scale since 1885. Deposits that can be mined on the economical standards of today, however, are confined in a roughly circular area about 30 miles in diameter, generally within Polk and Hillsborough Counties, in the central part of the State. The phosphate deposit, which is in the Bone Valley formation of the Pliocene age, is covered by Pleistocene terrace deposits of unconsolidated quartz sand. The matrix is composed of approximately 1/3 clay slimes, 1/3 silica sand and 1/3 phosphate pebbles. The phosphate occurs usually as rounded pebbles, ranging in size from about 1 inch down to approximately 400 mesh. The phosphate may vary from well- defined hard pebbles to soft weathered rock. The color and character of the phosphate will range from smooth buff pebbles to black and white or "salt and pepper rock." The screen size distribution varies considerably between locations and the recoverable phosphate varies may extend down to the 400 mesh size in some areas, while in others the phosphate may cut off sharply at about 35 mesh.

Jan 1, 1962

By Whitmell J. Smithwick

Lime is one of the most extensively used chemicals in industry. Other than sulfuric acid, it is used in greater quantities than any other man-made industrial chemical. In 1974 there were 20,368,000 tons of lime used in the United States, which amounts to approximately 190 pounds for each man, woman and child in our nation. Lime also is perhaps the most diversely used of any industrial chemical. It is used in such areas as pharmaceutical, chemical, steel making, glass making, production of copper and aluminum, sugar refining, agriculture, construction, ecological endeavors, potable water treatment and sanitation. Figure I lists the major uses of lime for 1974, which is the latest year for which this data is available. The impact of the use of lime for ecological reasons did not show up to any appreciable extent in 1974, but we expect this to be a significant factor within the next few years. Fortunately, in the United States and also in most of the world, there are many deposits of high quality limestone available for the production of hood quality lime. For this discussion, we will assure that a limestone of a suitable quality and size consist will be available in a storage bin or stockpile near the kiln. Quality requirements for the lime product will be covered. We also will give a brief description of the three most popular types of lime calcining systems, how they function, and expected lime product quality from each of these. Commercial fuels and major accessory equipment will be discussed briefly.

Jan 1, 1976

By John F. Slonaker

This report is a review of current research being conducted in the United States which is intended to increase the utilization of coal ash. In order that this report be as timely as possible, the majority of information was obtained by direct comunication with the people listed in the references. Due to the magnitude of the flyash research program, some projects may be inadvertently omitted. Field research on flyash for use as an agricultural fertilizer is being monitored at Virginia Polytechnic Institute and State University.1 This research is directed at determining the plant nutrients that are available in flyash as well as the quantities of flyash that can be applied to agricultural soil without adversely affecting plant growth, Coal mine spoil and refuse bank reclamation with power plant flyash is being demonstrated by United States Bureau of Mines, Morgantown, West Virginia.2 Numerous highly visible coal refuse piles and strip mine spoil banks contribute to air, water, and land environmental problems. Revegetation of several experimental sites with flyash from bituminous coal-fired power plants was undertaken in West Virginia and Pennsylvania. Conventional farm equipment was used at some of the sites while large earthmovers were required at others. The flyash served as a neutralizing agent, dilutent, and soil amendment to provide some nutrients which enhanced vegetation of the barren areas, Estimated cost of reclamation by this method is $300.00 per acre of previously leveled area. This figure can vary considerably depending upon the topography of the site, haul distance, quality of the soil and quality of flyash.

Jan 1, 1974

By John F. Slonaker, Joseph W. Leonard

This note is a review of current research intended to increase the utilization of coal ash. Due to the magnitude of the fly-ash research program, some projects may be inadvertently omitted. Field research on fly-ash for use as an agricultural fertilizer is being monitored at Virginia Polytechnic Institute and State University. This research is directed at determining the plant nutrients that are available in fly ash as well as the quantities of fly ash that can be applied to agricultural soil.

Jan 1, 1975

By R. E. Collom

VARIOUS chapters already written in the history of development of the North Dome of Kettleman Hills are monotonously identical in the one underlying theme of conservation of oil and gas. Discovered on Oct. 4, 1928, by Milham Exploration Co. with its wildcat Elliot No. 1, the field has been subjected to practically every modern form of produc-tion restraint in the name of conservation. The record thus far developed shows that conservation was had for a time, at a price; and that unitiza-tion must he blessed by single ownership or 100 per cent participation to be effective. In fact, incomplete unitization places a heavy handicap upon its participants in the competitive development that follows.

Jan 1, 1937

By Agne Rustan

Most of the mines in Sweden are metal ore mines in hard rock and none of these mines are classed gassy because there is no methane emission. The risk of methane explosions in Swedish mines is therefore very small. Since the 1960?s, in Swedish mines, there has been a change from electric and pneumatic loaders and transport machines to diesel. Today in almost all Swedish underground mines diesels are used. One of the most common complaint from the underground mine- workers is the exhaust gases from the diesel-vehicles. This is a strong motive for attempts to assure a more comfortable environment. Another motive for a better efficiency of ventilation under ground is the increasing cost of energy for fans and for heating the air during winter. For the largest mine in Sweden, the Kiirunavaara Mine, 36% of the energy for ventilation is used for preheating the air during the seven months when the temperature is below zero. The air quantities used for ventilation are large. In table 1 a comparison of the ratio between yearly produced ore and waste rock and installed fresh &apos;air capacity is shown. [ ]

Jan 1, 1980