Search Documents

By Frank Cook

In this two-year study, an evaluation of mining and reclamation practices at 159 randomly sampled surface coal mines in the United States was conducted. It is concluded that reclamation practices in most of the 22 coal-producing states were adequate during 1975, but that improvement in reclamation performance was desirable in the acid area of the central U. S. and in mountainous southwestern Virginia. Productivity improvements should result from research to determine efficient or optimal operating procedures for dragline stripping of single and multiple seams, surface mining of lignite, multicut and multiseam haulback mining on steep slopes, mountaintop removal, and surface mining in swampy or deeply glaciated areas. Specific candidate research projects are discussed in this report.

Jan 1, 1976

By Denis Labrie

Résumé Cent soixante (160) câbles d'ancrage ont été installés au toit de la rampe à la Mine-laboratoire de CANMET à Val-d'Or, Qué bec, Canada, pour prévenir toute dégradation suite à l'élargissement de la voie de roulage dans un secteur tournant à 180 degrés, communément appelé Virage Santa Barbara. Le roc à cet endroit est de nature bloqueuse et stratifiée, et son épaisseur au toit de la rampe est limitée à environ dix (10) mètres, le tout sous une couche de terrain meuble saturée en permanence. Le soutènement mis en place a été conçu pour former une zone de compression et supporter une strate de roc d?environ quatre (4) mètres d'épaisseur. Les critères de conception et les méthodes d'installation sont présentées. Un contrôle de qualité rigoureux a été effectué au moment de la mise en place du support, notamment en ce qui concerne la mise en tension des câbles eux-mêmes et la qualité du béton utilisé lors de l'injection. Des instruments de mesure seront mis en place sous peu pour dépister tout mouvement éventuel au toit de la rampe. Abstract Design and installation of an active mine ground support using tensioned cables at the Experimental Mine, Val-d?Or, Québec, Canada. One hundred sixty (160) cables were installed at the back of the ramp at the CANMET?s Experimental Mine located in Val-d?Or, Québec, Canada, to prevent any degradation of the ground after the enlargement of the roadway in a sector turning at 180 degrees, usually called Virage Santa Barbara. The nature of the rock mass in this area is blocky and stratified, and its thickness above the ramp does not exceed ten (10) metres. Eight (8) metres of soil, mostly saturated, cover the bedrock on top of the ramp. The ground support was designed to form a compression zone at the back, aimed to carry a strata of rock of around four (4) metres thick. The design criteria and the methods of installation of the ground support are described in the paper. A strict control of the quality of the grout used for injection and the tension placed in the cables was carried out during the installation of the support. Ground monitors will be installed soon, to detect any movement that could take place above the ramp.

May 1, 2001

By Mark Lawshe, Shosie Serata

The conventional method of mining underground, using narrow rooms and wide pillars, has proven to be poorly adapted to the powerful earth forces that act on underground openings. The high costs of roof bolting, timbering, steel arching, and other means of artificial roof support for both room-and--pillar operations and longwall gate roadways attest to the limitations of traditional mine design. Too often, productivity halts when corners buckle under "cutter roof' stresses, floors heave, and roof strata fall. In the 1960s, an entirely different approach to strata control was developed. The Stress Control Method (SCM) stabilizes failing roofs and heaving floors by removing the cause of failure - highly concentrated stresses around the openings. This is achieved by regrouping three to 10 rooms into a single entry where the rooms are separated by very narrow yielding but stable pillars. SCM employs a specified excavation sequence to redirect earth pressures away from the mine openings. The yield pillars act as scaffolding until a permanently protective secondary stress envelope forms around the entry (lower part of Fig. 1). The result is a dramatic improvement in roof stability and a significant reduction in artificial support costs. Some roof bolting must still be done, mainly to meet Mine Safety and Health Administration (MSHA) requirements. Potash, salt, coal mining The stress control method was first applied to the deep potash mines of Saskatchewan. The new SCM design actually increased room widths to enlarge the stress envelope, redistributing the stress concentration away from the entries (Serata and Schultz, 1972). This resulted in a turnaround from pervasive roof fall/floor heave conditions that threatened operations in the eight new mines opened in the Saskatchewan potash field during the 1960s. In addition to eliminating all roof bolting, SCM successfully stabilized ground conditions and substantially increased productivity over the original design (Serata, 1976, 1982). Similarly, the deep Boulby potash mine of Yorkshire, England, was about to close after various conventional means of combating roof failure had failed. An SCM test area was excavated that resulted in the ground quickly stabilizing without need o artificial support (Serata, 1982; Chilton and Laird, 1982). Another example is the Diamond Crystal salt mine in Louisiana. Here, multiple level mining was being extended from the third to the fourth level downward in the Jefferson Island salt dome. Extensive roof failure was occurring at 396 m (1300 ft) ii the third level. SCM design principles in creased the room size from 24 to 49 m (80 t( 160 ft) on the fourth level at a depth of 457 m (1500 ft). This unprecedented expansion of room width was first questioned and later ap¬proved by MS HA, which expressed satisfaction in seeing the improvement documented by field validation data in 1973. The most recent SUM application to salt mining has been in the Michigan Basin a: Goderich, Ontario. The anticipated abandonment of Domtar Chemicals Group/Sifto Salt Division's deep operation in bedded sale was prevented by a multi-year SCM implementation. The success of SCM in dry mining[lecc] to its application to solution mining of salt This adaptation of the method is now being implemented in bedded salt at Fort Saskatchewan, Alberta by Dow Chemical Co., and in St. Clair, MI by International Salt Co. Application of SCM to solution mining in a salt dome is proceeding at Napoleonville. LA by Dow Chemical. The same technology has also been applied to cavern design for the Louisiana Offshore Oil Port (LOOP), and the compressed air energy storage (CAES)

Jan 1, 1989

By Timothy A. Clancy

To help reduce the Nation's dependence on imported chromite, the Bureau of Mines is conducting research on the use of dolomites as an alternate material. Dolomite is a plentiful domestic resource and offers certain advantages as a refractory raw material. A review of the literature has indicated that there are many sources of high-purity dolomite in this country and that European nations use a greater proportion of dolomite refractories, primarily in steelmaking, than the United States, The Bureau of Mines characterized 14 domestic dolomites as to chemistry, density, mineralogy, microstructure, and thermal behavior, to develop baseline data on their suitability as refractory raw materials.

Jan 1, 1983

By Jr. Abel

Subsidence is controlled by a complex combination of mining and geologic factors. For example, a world-wide compilation of data shows that, as the percentage of shale in the overying rock mass decreases and the amount of sandstone increases, the angle of draw (and the area affected by subsidence) decreases. Limestone in the overburden appears to cause as much as a three-fold decrease in the angle of draw compared to a like amount of sandstone. Increased amounts of sandstone were accompanied by a greater surface subsidence relative to the mining height. The total thickness of overburden did not appear to influence the subsidence magnitude above super-critical panels. The greater the thickness extracted the smaller percentage of that thickness that shows up at the surface as subsidence. The greater the percent of the seam extracted, the greater the subsidence reaching the surface. The maximum subsidence above room and pillar panels is dependent on the pillar height and minimum width as well as the other factors listed.

Jan 1, 1980

By M. C. Harris

The past twenty to thirty years have seen unprecedented research activity aimed at understanding the performance of flotation froths. In 1990, Finch and Dobby coined the term froth recovery factor, Rr, to represent the efficiency of the froth in delivering particles from the pulp-froth interface to the concentrate. Originally defined for flotation columns, Rr has also been found useful in modeling mechanical flotation cells, and a number of techniques, based on quite different approaches, have been developed for measuring the froth recovery in industrial flotation cells. None of these techniques is universally successful. This paper reviews the concept of the froth recovery factor, and the basis of each of the techniques that have been proposed to measure Rr, and examines the reasons for this parameter being so difficult to pin down. Advances in Mineral Processing Science and Technology Proceedings of the 48th Annual Conference of Metallurgists of CIM Sudbury, Ontario, Canada Edited by

Jan 1, 2009

By L. T. Matthews, C. E. Loo, R. P. Williams

The behaviour of iron ores and fluxes in the high temperature zone of a sintering bed is extremely complex. Following a review of current knowledge, an attempt is made to define relevant terminology to describe the processes that occur in this part of the bed. A deformation temperature is used to quantify the initial formation of melt, which is produced predominantly by reactions between fine particles in the sinter mix. The subsequent assimilation of larger particles is considered to depend on the reactivity of the melt and the assimilation resistance of these particles. Novel laboratory experimental techniques are used to quantify these parameters. Results demonstrate that the properties of the raw materials used have an extremely important influence on the initial processes of melt formation and assimilation and also on the nature of the sintering reactions and sinter-bonding phases.

Jan 4, 1992

U.S. Bureau of Mines contract H0122053, "Improved Sensors and Fire Control Systems for Mining Equipment", was an investigative effort involving: ? Study of the fire problem on large mobile mining equipment ? Identification of equipment most prone to fire, to serve as a design case example ? Design of an improved fire protection system ? Demonstration of the developed system This effort was performed during the period June 1972 through May 1973, and was conducted in two phases. Phase I, June through November 1972, was devoted to identifying the fire problem and developing and evaluating design criteria. Phase II involved translating the design into hardware and demonstrating its effectiveness during actual fire tests, first on a wooden mockup of a truck, then on an operating truck at a working mine site.

Jan 1, 1973

This paper aims to increase our understanding about existing capacity-building approaches and their implications for obtaining a social license to operate in the mining industry. The notion of ?capacity building? is gaining increasing currency in the mining sector in developing countries due to a rapid rise in the globalisation of mining operations. Capacity-building is conceived here as a process that lasts after the mine-cycle, intended to provide local mining communities with tangible skills and knowledge to gain meaningful employment in mining or other industries relevant for the local economy. Building community capacity to understand and effectively respond to these transformations is vital for obtaining a social license to operate, as it promotes sustainable and locally relevant development. Accountability mechanisms such as global norms and international standards increasingly highlight the need to build capacity among stakeholders, particularly among local communities adjacent to mining operations. International frameworks and mining companies have embraced the notion of capacity-building as a driver to assist corporate social and operational performance. However, this narrow understanding of capacity-building through the prism of corporate social responsibility and ?best practice? is preventing the industry from meaningfully impacting communities and maintaining a social license to operate. This latter notion is being widely embedded across multiple industry sectors, as a social and economic reward from mining companies to compensate communities for natural resource extraction and gain social acceptance. Although both concepts are widely recognised in the minerals industry, insufficient attention has been paid to the implications of applying a top-down (mining-orientated) or a bottom-up (community-orientated) capacity-building approach for obtaining a social license to operate, or indeed how these two concepts are linked and applied in practice. At times, communities lack the necessary capacities in the form of education and skills to deal with mining-led livelihood transformations. This is preventing both mining companies and communities from forging sustainable livelihoods and responding to mining-led livelihood transformations, a situation that is creating discontent among communities and reducing the possibility of obtaining and renewing a social license to operate for the industry. Based on a review of current scholarly debates, accountability mechanisms in the mining industry and fieldwork findings in Colombia, this paper will contribute to an understanding of the implications of existing capacity-building approaches that support a social license to operate.

Aug 1, 2013

By D. K. Uko

In the stretch-bend or bending-under-tension test, a strip is rigidly clamped and restrained at each end and bent by central transverse loading using a radiused punch: The strip deflection at failure has been used as a measure of formability for high-strength low-alloy (HSLA) steels by other investigators. In this work, a detailed study is made of strains developing during stretch bending of an 80,000-lbf/ in 2 (552 MPa) yield stress steel using different punch radii. It is shown that toward the end of the process, the bending strains at both the inner and outer surfaces are tensile and suddenly increase at a rapid and approximately equal rate. The strain ratio in the failure region departs significantly from plane strain , even using a large width-to-thickness ratio of about 10. The effective fracture strains appear to be independent of bend ratio (punch radius/thickness) and significantly below the fracture s train in simple tension. Metallographic and tensile data were obtained for the subject material and, for one bend ratio, the effects on stretch-bend parameters of annealing both on this material and a. carbon steel were compared.

Jan 1, 1977

By O. P. Hood, R. H. Kudlich

When a gasoline locomotive is used in a mine there is danger of the noxious gases of the exhaust vitiating the air, but if enough air is circulating in those parts of the mine in which the locomotive is used, these gases are so diluted that they are rendered harmless, and the health of the workmen is not affected. In some mines the use of gasoline locomotives is impracticable, though in the majority of mines where they have been tried they have proved to be safe and economical. To determine the limitations that should surround the use of these machines in mines so that they shall not be detrimental to health and so that their economic advantage may be retained, it is necessary to ascertain the volume and the character of the exhaust gases and the amount of these gases that may be safely allowed in the mine air, and also to determine safe conditions of operation. The problem is primarily one of ventilation and like all ventilation problems must be intelligently computed to meet the conditions of each mine. The investigation described in this bulletin was undertaken 'by the Bureau of Mines in an endeavor to obtain exact information on some of the basal questions involved in the use of gasoline locomotives in mines, this investigation being one of many that the bureau has been conducting in its efforts to increase safety and efficiency in mining.

Jan 1, 1915

Australian coals tend to be young in geological age and high in ash by world standards; preparation of the coal before marketing is almost universal. On the basis of float and sink data from 39 locations in the Eastern Australian coalfields, the coals are placed in four categories representing increasing difliculty in their washability characteristics. These seem to be related neither to the geological age nor the geographical position of the deposit and Hunter Valley coals, for example, span all categories. The influence of crushing on the washability of Australian coals is briefly considered and from limited data it is concluded to be appreciably smaller than for British or North American coals. A strategy for the float and sink analysis of Australian coals is proposed and the influence of washability characteristics on current trends in the selection of separating processes for coking and steaming products is discussed.

Jan 1, 1979

By William P. Stroud

Chemical alteration of the compressive strength of sandstone has been investigated by the U.S. Bureau of Mines (USBM). Successful development of this technology would offer an attractive alternative to the methods now used for stress control in mines. Sandstone cores were stressed to failure under uniaxial compression at two different strain rates. Specimens saturated with either distilled or tap water showed an average 14% reduction in stress at failure compared with those dried in vacuum. Samples saturated with dilute solutions of aluminum chloride, hydrochloric acid, and polyethylene oxide showed no statistically significant difference in failure stress compared with those saturated with water. By contrast, compressive strength of the cores was increased some 7% by saturation with the nonpolar solvent carbon tetrachloride. No correlation was found between zeta potential and compressive strength.

Jan 1, 2010

By Michael L. Wayman

Archaeological and ethnographic work during the last century has shown clearly that metals have played a small but important role in prehistoric Arctic cultures. For at least the past several millenia both iron and copper have been used in the North, primarily for blades, projectile points, knives, awls, engraving tools, fishhooks, scrapers and axes. In addition they were used for joining purposes as staples and rivets. It is of great interest to enquire into the origins of these metals. In this connection one begins with the observation that to date there has been no clear evidence for the smelting or melting of metals in the Arctic prior to the arrival of Europeans. This can be explained partly by the absence of traditional pyrotechnologies such as the high-temperature firing of ceramics and the heat treatment of bone and wood. Another factor which surely inhibited the development of smelting/ melting operations is the relative absence of wood in the region. The production of charcoal for smelting requires large quantities of wood, to the extent that the desertification of a number of areas in the Old World is believed by some to have been at least partly caused by charcoal production. In the North this was obviously not possible. Thus the Arctic peoples were restricted to using native (naturally occurring) metals and metals obtained by various direct and indirect forms of contact with areas of the world where smelting was practiced. Both of these sources were important in the case of iron; we know that meteoritic iron, telluric (native) iron and smelted wrought iron were all used in the Arctic. These three types of iron will be considered in tum.

Jan 1, 1999

By Alan K. Burton

Massive increases in the productive capability of open pit nines after World. War II were in a large part made possible by the introduction of ever larger trucks and the supply of a seemingly bottomless ocean of inexpensive and readily accessible oil. Over a period of about 25 years, a variety of technological developments permitted a tenfold truck payload increase, from about 32 tonnes (35 tons) to 320 tonnes (350 tons). There is no, doubt that this was a remarkable achievement resulting in impressive benefits of scale as well as the ability to control what would otherwise have become an intolerable traffic congestion problem in today's large open pit mines. It became fashionable and economically possible during this time to mine large quantities of low grade material and to tolerate very high stripping ratios. As tine has gone by and as easier to get at and higher grade deposits have been depleted, ore grades have tended to decline while stripping ratios have increased. The alternative to reduced revenues has been an ever increasing demand to step up production which in turn has led to a continuing demand for ever larger and larger trucks. While a larger truck has had the effect of reducing the cost of the operator per unit of material moved and of reducing traffic congestion, it has not specifically addressed the subject of fuel cost.

Jan 1, 1981

By AIME AIME

THE American Engineering Council, which is the working body of The Federated American Engineering Societies, held its first meeting in Washington, Nov. 18 and 19, 1920. The Federated American Engineering Societies was formed in Washington in June and is composed of engineering and technical societies, national, state, local and regional. These Member Societies elect delegates to the American Engineering Council, which is the administrative body of the Federated. The meeting was called to order by Richard L. Humphrey, Chairman of the Joint Conference Com¬mittee, and the program (which is printed below) was carried out without substantial change by E. S. Carman, who was elected temporary chairman. Under the Constitution, the Council appoints an Executive Board, the members of which are chosen according to the proportional membership of the vari¬ous Member Societies in their respective districts. Under this plan, with the present membership, 'the national societies will have 14 members and the local societies 6 members on the Executive Board.

Jan 1, 1920

By Xinhua Wang, Qiangqiang Wang, Yubin Li, Shusen Li, Lifeng Zhang

"Numerical simulation on the fluid flow in a Flow-Control Mold (FC-Mold) were performed. The motion of inclusions were calculated. With FC-Mold, the flow pattern and surface velocity become more symmetrical, and at higher casting speed the velocity of liquid steel in the top region of the mold was largely reduced with the highest velocity of the meniscus reducing from 0.65 mis to 0.4 mis, and the meniscus shape became flatter. With FC-Mold, more inclusions approached to the surface of the slab and the amount of inclusion in the center of mold became fewer. Larger inclusions were easier to remove, however, the EM filed of the FC-Mold could hardly improve the removal of inclusions from the molten steel.IntroductionElectromagnetic brake technology is an effective method to control the flow pattern within continuous casting mold, together with other casting parameters, nozzle design and mold geometry [1-5]. Due to the interaction between the applied magnetic flux and the conductive molten steel inside the mold cavity, a force is generated in the direction opposite to the jet flow, which can decelerate the high speed steel jet from the SEN ports. The potential benefits include fewer surface and internal defects, fewer inclusion especially at higher casting speed. However if used imperfectly, electromagnetic forces can have opposite effect [6]. Numerical models are the best tool to optimize electromagnetic flow control. In the current study, numerical simulation was performed to investigate the flow field in a continuous casting FC-Mold, and the effect of different operation parameters on the flow, surface level and velocity in FC-Mold were discussed."

Jan 1, 2013

By John D. Rockaway

Failure of the mine floor supporting coal pillars frequently occurs when the subcoal strata include "underclays" or other low strength strata. The failure process has been studied to define the response of these materials to applied coal pillar loads and to determine the applicability of bearing capacity analysis to evaluate unsafe conditions. The study has been accomplished through an investigation of both the intact and insitu geotechnical properties of the subcoal strata and through the installation of floor movement monitoring instrumentation. The results of these studies have indicated that both the shear strength of the underclay and the stratigraphy of the subcoal strata must be considered in the analysis. The shear strength was the major controlling factor determining the ultimate load carrying ability of the materials, but the thickness and stratigraphic position of the weak layers influenced the mechanism of the failure process. The methods of bearing capacity analysis were used to define pillar stability that included provisions for taking into consideration a two-layer system. Conditions assumed for a coal mine where a weak underclay overlies firmer strata. The results of the analysis compared very well with observed mine conditions, indicating marginal conditions in areas of the mine which later experienced pillar support failure. In addition, a "heave factor" was derived to predict potentially unstable floor conditions in the mines studied in detail.

Jan 1, 1979

By John D. Ridge

Here are summarized 162 papers, published between 1933 and 1967, that deal with various aspects of ore genesis. Emphasis is placed on additions to, or modifications of, ore-formation theory, no matter what type of deposit is discussed. More space is given to papers on the formation of base-metal sulfides solely because more papers are written on this subject. The final conclusion is reached that a chemically and geologically sound theory for the genesis of ore deposits can be built around the concept of concentration of ore e’ements in a magmatically produced ore fluid and around such surface processes as may act to concentrate economically valuable materials from rocks of any origin exposed at the surface.

Jan 1, 1968

By John D. Sullivan

A DISCUSSION of the developments of the past decade in the field of refractories, and the effect of these developments on the performance and life of open-hearth furnaces, is perhaps best introduced by reference to Fig. 1. This shows the most important types of refractories doing into various parts of the furnace, together with their cost, and remarks on their use. It has been estimated that half of the refractory makers market comes from the iron and steel industry, and something like one-third of all refractory brick used finds its way into open-hearth furnaces. To melt steel, a furnace capable of withstanding temperatures close to 3000 deg. F. is required. The furnace is assembled of various refractory materials selected by experience and economic considerations. Furnace structures today, from a refractory standpoint, are considerably different from a quarter century ago. Furnace operators, interested in the performance of refractories, care little how they are made or where they come from so long as they give reasonable service. But, the entire history of the refractory is important and technical knowledge of the ceramic materials used in making the refractory is necessary to the manufacturers, so that the proper article gets into the hands of the ultimate consumer.

Jan 1, 1936