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By E. G. Williams

Manganese-ore has been found upon the Isthmus of Panama throughout' a region of nearly three hundred square miles, over the greater part of which, however, it is known only in small bodies without commercial value. Only six mines, controlled by two companies, have actually shipped ore, although a large area has been taken up in miningelaims. The ore-bearing region extends along the coast of the Carib. bean Sea, beginning on the west near Puerto Bello and extending easterly about 35 miles toward Point San Blas. Ore has been discovered in the interior, at a maximum distance of about 10 m. from the coast. Fig. 1 is a map of a portion of the Isthmus

Jan 1, 1903

By Ben V. Petersen

Surveying is to tunneling, as a steering wheel is to a car—somewhat essential if you want to end up in the right place. The principles of tunnel surveying have remained unchanged since the first tunnels were constructed: To mathematically connect the selected start and end points of a tunnel and physically translate that alignment onto the ground. The alternative is just dead-reckoning and leaves the probably less than satisfying end results to chance. Today’s laser-guided tunnels often have to thread the needle through a maze of soil types, utilities, structural features and other underground considerations. Surveying makes it possible.

Jan 1, 2005

By Roderic A. Ellman

The new Woodrow Wilson Bridge (WWB) will replace the existing bridge over the Potomac River to connect Alexandria, Virginia to Prince Georges County, Maryland. The new WWB will extend approximately 1.1 miles across the river, with a 367-ft long bascule span in the main river channel where the water depth is about 36 ft. The bridge is primarily comprised of fixed spans in relatively shallow water and a bascule span over the navigation channel. The subsurface soil profile was quite variable along the bridge alignment. In Virginia, there was fill over soft Alluvial deposits underlain by dense Terrace deposits, as well as remnant foundations from a former ship yard. At the bascule span, there was up to 50 ft of a soft organic silty clay layer underlain by a deep deposit of stiff Cretaceous clay. Along the Maryland approach, there were Alluvial deposits over dense Terrace deposits over stiff Cretaceous clays and dense Cretaceous sands. The variation in subsurface conditions led to the selection of alternative deep foundations that suited the specific conditions and were based on the design phase testing program, from which ultimate design capacities were determined. During construction, there were instances of unexpected pile performance, notably different than that experienced during the design phase testing, requiring changes to the contract installation criteria and re-design. This paper will present the types of deep foundations used for the project, the performance criteria assumed during the design, the measured performance and difficulties encountered during construction, and the resulting remedial actions, i.e., changes to contract installation criteria and/or re-design due to the unanticipated field conditions.

Jan 1, 2009

By Colwell J. B, Constantine A. E

A unique, regional grid of deep (12 - 14 second record length), seismic reflection and refraction data has been recorded by the Australian Bureau of Mineral Resources (BMR) across the offshore Gippsland Basin and parts of the adjacent Bass Basin, in southeastern Australia. These data have been combined with onshore mapping to produce a new model for the development of the Gippsland and adjacent Bass Strait basins. Overall, the Gippsland Basin contains up to 12 - 14 km of sediment in an ESE-trending depocentre bounded on its north and northwestern margins by a detachment ramp, and on its southern side by a relatively linear, listric fault system. The basin, together with the adjacent Bass and Otway Basins, appears to have formed as part of a linked, largely- strike-slip to 'transtensional' system, which started to extend through Bass Strait, probably during the latest Jurassic. Each of the basins developed by movement on a common detachment or detachment complex, which produced headwall extension at their western ends, in the areas now occupied by the Strzelecki Ranges, Otway Ranges - Torquay Sub-basin, and Robe Trough. Adjustments and reactivation from the mid Cretaceous of several postulated microplates in the region, largely in response to Tasman Basin rifting, gave rise to the wrench-related and compressional structures which form the major petroleum targets in the Gippsland Basin. However, the same process formed largely extensional stuctures in the Bass Basin. Our interpretation of the tectonic history of the Gippsland Basin leads us to the conclusion that there may have been several phases of petroleum generation and migration, and that potential petroleum traps appear to exist in the deeper section, in structures sometimes not reflected at the top or near-top Latrobe Group levels.

Jan 1, 1992

By Göran Bäckblom

The Swedish mining companies LKAB and Boliden, the equipment supplier Atlas Copco, the general contractor NCC and the specialist company Reflex joined forces in 2005 to advance the field of rock technology for the purpose of mining and underground construction. The creation of the company Rock Tech Centre is part of the strategy developed by the Swedish mining industry to strengthen co-operation with industry, academia and society. This paper outlines the current R&D strategies developed for the industry in general, discusses what focus areas are selected and provides some details on the current RTC project portfolio, especially faster and better drifting.

May 1, 2006

By Steve Collinsworth, Nils Heinke

In 1989, I realized the definite need for change in the Blast Hole Drilling Industry. With over 25 years of experience in dealing with the industry, I am well inGormed and educated concerning the problems that occur in Blast Hole Drilling. After continues interaction with the Drill & Blast Superintendents, Drillers, Purchasing Agents, Mechanics, and others in the field, a basic understanding was developed as to the origins of the main problems that the industry f&s with their drillings programs.

Jan 1, 1997

By Julie Hunt

Rimfire Minerals Corporation: early stage precious metal exploration specialists with discovery opportunities in partnership with major and mid-tier gold producers or prominent junior exploration firms. Mike Roberts, Senior Geologist

May 1, 2006

By Yoshinori Iwasaki, Shosei Serata, Yutaka Mochida

A new comprehensive insitu instrumentation technique named this RCC Method has been developed for rapid assessment and improvement of the structural stability of underground openings. When applied to tunnel construction, the degree of present and prospective safety of underground openings can be determined in quantitative terms within 10 to 20 minutes of microcreep observation. When applied to mining, roofs and floors can be stabilized by controlling the stress conditions. This stress control method has eliminated the need for intensive roof bolting and extensive floor renewal in all cases where it was applied. Use of this technique is illustrated by field examples from the Seikan Undersea Tunnel of Japan and deep potash mining in Canada. NEW INSTRUMENTATION TECHNIQUE: THE RCC METHOD Failure problems in underground excavation usually arise in weak non-elastic grounds where conventional rock mechanics theories of elasticity are not only useless but also misleading. Presently, discontinuity planes in the ground are being considered a factor in assessing these failure problems, and while this development is interesting academically, it is not of much use in actual excavation work, where it is nearly impossible to identify and quantize all existing planes of discontinuity. Even if such an extraordinary task could be accomplished at an underground excavation site, effective use of the data would be difficult and impractical for rapid excavation work, with the possible exception of rare cases of ideally elastic ground.

Jan 1, 1976

By Bill York-Feirn

The Colorado Mine Safety & Training Program (MSTP), in late 2005, completed and began distributing two new training tools; one geared to underground coal mine foremen and the other to surface aggregate employees. Through strong partnerships with MSHA, Colorado Coal Mine Board of Examiners, Colorado Mining Association and the Colorado Rock Products Association, the MSTP continues to create innovative and interactive training tools for not only Colorado, but for the national mining community. "Although we shoot and produce these materials in Colorado, it's important to us to make sure they are useful nationally," said Bill York-Feirn, MS TP Manager. The interactive DVD program "Underground Mine Foreman Certification Study Guide (Coal)," was completed in October 2005. It won the 2005 Grand Prize at the MSHA National Training Materials Competition in Beaver, West Virginia. [ ] This program is fully based upon the requirements of Title 30 Code of Federal Regulations (30 CFR) Parts 48, 50, 70 and 75 for underground coal mine foremen. It contains eight modules plus immediate access to relevant laws in the appendix. Topics covered include: Federal Law, Practical Math Skills, Mine Gases, Ventilation Maps, and scenarios addressing a variety of practical mining concerns. The DVD is designed for self-¬paced study and practice.

Jan 1, 2006

By Keith A. Heasley

In the past, numerous displacement-discontinuity (DD) models of stratified rock masses have been proposed using a homogeneous isotropic elastic overburden. In this paper, it is postulated that a laminated overburden model might be more accurate for describing the displacements and stress in these stratified deposits. In order to investigate the utility of using a laminated overburden in a DD model, the fundamental mathematical basis of the laminated model is presented and graphically compared with the fundamental behavior of homogeneous isotropic elastic overburden and with field data. Specifically, the stresses and displacements surrounding an idealized longwall panel as determined from the laminated overburden model are presented and compared with results from the homogeneous isotropic overburden and with measured abutment stress data. Also, the remote displacements and surface subsidence as calculated by the laminated overburden model are compared with homogeneous isotropic calculations and with measured subsidence data. The results of this investigation show that the laminated overburden is more supple, apt to propagate displacements and stress further, and better able to fit observed data than the classic homogeneous isotropic overburden. Ultimately, it is suggested that the laminated model has the potential to increase the accuracy of displacement and stress calculations for a variety of mining situations.

Jan 1, 1996

By Rowan A' Murry Karstel

One way to ensure dragline productivity is by Increasing the size of the dragline bucket. In August 1994, Optimum Colliery in conjunction with Van Reenen Steel, Northwest Applied Technology, SSAB of Sweden and Barlows Equipment launched the new lightweight dragline buckets. Optimum built the first prototype bucket that was used for the deslgn for future buckets. After knowledge had been gained from measuring the input force of the bucket Northwest Technologies designed the new bucket with finite element analysis. Together with the knowledge of quenched and tempered steel from SSAB of Sweden and Barlow Equipment, the new Wrightech bucket was born.

Jan 1, 1998

By R. W. Culbertson, S. Kasper

During the 1920's, approximately 11,000 small gasifiers were in operation in the United States. They converted about 15 million tons (13.6 Mt) of coal per year into low Btu gas. In some cases, hot raw gas was used for applications such as firing open hearth furnaces or brick kilns. In other cases the gases produced in the gasifiers were cooled, cleaned and desulfurized for various utility and industrial purposes. The steel industry was by far the largest user. The most important fact was that the conversion of coal to a usable fuel gas was demonstrated to be commercial. During the late 1940's and early 1950's, this form of energy was largely replaced by natural gas as the pipeline net work was expanded. Producer gas was no longer economically competitive. Over the past 25 years, government controls on the interstate price of natural gas have maintained this situation. At present only three commercial small coal gasifier plants are still in operation in the United States. These facilities are operated

Jan 1, 1980

By E. M. Spokes

Starting in 1980, a committee of the National Research Council studied the question of why some underground coal mines are safer than others and what could be done to improve the ones with poorer performance. The results indicated that safety is improved by management commitment to safety, by cooperation between labor and management on safety matters, and by quality training of employees and managers. Younger miners have higher accident frequencies, but are less likely to be killed or permanently disabled by a lost-time accident. Methods for improving safety performance are proposed.

Jan 1, 1987

Capture airborne coal dust generated by a continuous mining machine to reduce workers? dust exposure and to improve face visibility. Approach Develop a low-profile dust collector system which can be mounted on the boom of a continuous miner. How It Works When coal is mined with a milling head continuous miner, a substantial amount of coal dust (respirable and non-respirable) escapes the dust suppression sprays at the cutter head. This can cause poor visibility around the cutting head and can expose the workers to high levels of respirable dust. A practical means of removing this dust is with a scrubber mounted directly on the mining machine. Under a Bureau of Mines contract, a low-profile, machine-mounted dust collector (MMDC) was developed to avoid adding extra height to the continuous

Jan 1, 1983

By Gene Mattila, Ron Boyd

Introduction Rock bolting is a general term that encompasses pinning, roof bolting, rib bolting, and cable bolting. Rock bolting contributes the highest nonproductive cost and is the most significant safety risk in mining today. Total installed bolt costs are now more than $20 per bolt. Rebolting or repair work doubles this. And bolting accidents account for about 30% of all fatal and nonfatal lost time accidents. It is only logical, then, for the mine operator to install the highest quality anchors possible. Every bolt on the market - tensioned, untensioned, full contact, or point anchor - has designed capabilities in axial, shear, and fluctuating ground conditions. Bolts will provide a designed support if material specifications and installation procedures fall within the manufacturer's recommendations. This also assumes that there are no unexpected geological or operational changes. Proper material specifications and installation procedures should guarantee the mine operator a quality anchor. To help assure this, the Mine Safety and Health Administration (MSHA), the US Bureau of Mines (USBM), and the AMC Manufacturers group developed stringent ASTM materials standards. These govern mechanical point anchor bolts and bolts using threaded and nonthreaded rebar. There are also minimum standards that suppliers must comply with in the manufacture of frictional bolts. However, most frictional bolt standards are based on the manufacturer's own specifications. It would be impossible to set uniform regulations on frictional bolts. Each bolt provides support in a slightly different manner and thereby requires different material needs. Quality Control In any case, material quality can generally be assured through tight order specifications and periodic quality control checks. The problem with installing quality anchors does not solely lie with the material. It includes all the events that occur from the time a bolt leaves a manufacturer to the time it is installed. The anchoring ability of any major type bolt can be affected by transportation, storage, mechanical performance of installation equipment, installation demands of the operator, proper drilling accessories, and local geology. Table 1 and Fig. 1 document the negative events that can affect each bolt and the degree to which it can be affected. Drilling a hole of oversized diameter, for example, is an operator controlled factor. It will adversely affect most bolts. An over-sized diameter reduces, or even eliminates, the anchorage capability of a mechanical shell. It will reduce the support capacity of a split set to nearly nothing. And it will cause a partial or incomplete grouting around the resin bolt. Frequently, due to bit wear, holes are drilled undersized in diameter and may not be properly cleaned out. In this case, it will be difficult for the operator to push the mechanical shell into the hole, thereby causing him to drill another hole. In cases where the bolt is obviously not providing anchorage, operators will probably drill another hole and place another bolt. Rock Bolt Regulations It is the situations where a bolt is improperly installed in the hole, but gives the appearance of a good bolt, that are frightening. In fact, some safety officials and engineers believe that only 50% to 60% of installed bolts are working. These bolts cause irregular ground load transfers in other bolts and overload them. This causes hazardous situations and overstressing. It is these bolts that fail prematurely 200 to 255 mm (8 to 10 in.) behind the face and possibly contribute to the high accident rate. The government and several manufacturers recognized the need to check the integrity of rock bolts. These programs are in different stages today. Tight torque regulations have been established for mechanical

Jan 4, 1985

By J. Miettunen

"The lining of a grinding mill has an important role in creating the conditions for the grinding process. The main purpose of the lining is to transfer the energy taken by the mill motor to the contents of a mill. The power draw curve of the mill, if measured with sufficiently short intervals, describes how well the lining works in lifting and mixing the material to be ground.The power draw curve can also be used for determining the volumetric filling of a mill. This new measuring technique was developed at the Pyhasalmi concentrator in 1989-90. The measuring device with its PC-connections offers an excellent tool for controlling volumetric mill filling, for maximizing throughput and for research purpose (e.g. process studies, mill linings design).The paper describes the new method and the results achieved at Outokumpu's concentrators.INTRODUCTIONVarious methods have been developed for measuring mill load; weighing, noise, etc. Weighing is one of the most reliable methods but installing the sensor to existing mills is often difficult. Besides the load measurement does not indicate the volumetric filling if the specific gravity of the mill feed fluctuates. Noise measurement has often failed with its sensitivity to various disturbance sources.As known, the power draw measurement is one of the most accurate measurements in grinding circuits and therefore it has been utilized in sophisticated control, e.g. in power peak seeking algorithms for maintaining maximum grinding efficiency.About 10 years ago power oscillation measurement was developed at Pyhasalmi concentrator. In this method the amplitude of the oscillation caused by the lifters was measured. The oscillation amplitude and the mill filling has quite a good correlation and together with the power draw measurement it could be used for maximizing mill throughput (Koivistoinen and Miettunen, 1989). The main difficulties in this method were that the dependence between mill filling and the amplitude is unlinear and that the dependence also is individual for each mill.The method developed during 1989-90 is also based on the power oscillation but on its phase shift. In principle level of the material in a mill is measured. The method has been successfully used for maximizing throughput at Pyhasalmi and Enonkoski concentrators and at Harjavalta slag concentrator."

Jan 1, 1991

By G. J. Borbely, E. A. Devuyst, V. A. Ettel

"A new method for oxidative destruction of cyanide in industrial waste waters and slurries, such as gold mill barren liquors, tailing slurries and flotation tailings has been developed at the Inca research laboratories. Rapid decomposition of cyanide and related species is attained by treating the waste waters with a mixture of S02 and air at controlled pH and in the presence of a small amount of copper which acts as a catalyst. The approach selectively oxidizes cyanide and metal cyanide complexes, and also removes iron cyano complexes which are not removed by alkaline chlorination.The new method is shown to be less reagent intensive and therefore more economical than alkaline chlorination for treating gold mill and flotation waste waters. INTRODUCTIONOver 90% of the gold mined in Canada is extracted from the ore by ""cyanidation"". Wastes from the process consist of tailings which contain free cyanide, cyanide combined with heavy metals, thiosalts and thiocyanates. Because of the concern over the effect of toxic cyanides on the environment, all cyanide containing effluents will have to be treated in the future to meet certain government set concentration limits."

Jan 1, 1982

By Larsson Lars-Erik, Rani Isa, Martin Jönsson, Håkan Bredenberg, Mats Larsson

"IntroductionSteel Core Piles are used extensively in Scandinavian countries, where hard rock is found within reasonable depths. A steel core is cast into a drilled steel tube casing and a rock hole is extended below the casing. This pile type is considered a very reliable type of pile, and for urban environment it has several advantages compared to other types of piles. One critical phase of the installation is the drilling of the casing. Usually a DTH (Down The Hole) hammer is used. Drilling in fine grained soils, e g silt, below the ground water level, may give rise to an excessive volume of soil material flushed up from the point of the casing, resulting in unacceptable settlements around the pile installation area.Using a new method for drilling of the casings, the ELEMEX-method has proven to significantly reduce the risk for such problems. In the paper a case record from a ground improvement project in central Stockholm is described. Ground settlements around the drilling area were carefully monitored over a longer period. Both the new drilling method and the conventional DTH casing drilling method where used, so that the corresponding ground settlements could be compared. Settlement records and comments are included in the paper.The paper also gives a description of the project. The installation of new piles and foundation constructions cover a whole city block in Stockholm downtown. The reason for the replacement of the old, damaged wooden piles were due to their destruction caused by a long time lowering of the ground water table. The paper gives a description of the new drilling method as well as an overview of usual urban foundation issues and their solution in Sweden, Finland and Norway.Drilled Foundation MethodDrilled Foundation, using drilling methods originally developed for drilling of large diameter rock holes, is today a standard method for the installation of piles, tiebacks, drilled pile walls and other foundation components, especially in urban built up areas where other techniques as drop hammers, augers, vibratory hammers and other equipment fail to meet the requirement, se ref(1). Drilled foundation is for example used for"

Jan 1, 2014

By Catalin Florin Petre, Elahe Ghasemian Langeroudi, Abdelaaziz Azizi, Éric Proulx, Caroline Olsen, Paul Blatter, Faïçal Larachi, Claude Gagnon

"The recovery of gold from ores is often accompanied by the release of other species in the leach solution. This state of affairs leads to depleted free cyanide levels in the slurry. Therefore, separation and quantification of these cyanicides and free cyanide at different stages of the cyanidation process as well as in waste solutions is crucial to provide mitigation tools by preventing leaching of deleterious metals for environmental considerations.COREM and the research group of Prof. Larachi have been working together on the control of gold passivation and cyanicides during cyanidation for several years. Previously, a first capillary electrophoresis (CE) protocol for the speciation of sulfur and cyanicides (SCN-, Cu, Fe) during cyanidation of gold complex sulfide ores was developed and validated for assessing industrial process water.The separation of zinc cyanide complexes used to be confronted with a number of difficulties due to the weak and/or undetectable cyanocomplexes in formally available CE protocols. Moreover, according to our knowledge, no direct CE protocol exists to separate free cyanide. Therefore, a new study aimed at developing a second CE protocol for the detection and quantification of cyanide complexes of zinc and nickel as well as of free cyanide in the cyanidation process water.To achieve this goal, six common carrier electrolytes such as pyridine, trimellitic acid, 4-methylbenzylamine, sodium chromate, phthalic acid and tris base were studied, using an indirect UV detection method. The best results were obtained using sodium chromate for which all ions were successfully separated and quantified. In addition, the effect of electric field strength, injection volume, electro-osmotic flow (EOF) modifier and background electrolyte (BGE) concentration were examined, while peak height, peak area and noise were considered for optimization.As a result, the new protocol is expected to complete the initial CE protocol by detecting cyanide complexes of zinc and nickel as well as free cyanide. Moreover, analytical determination of free cyanide in the presence of weak cyanide complexes achieved by the new protocol was also compared to conventional titration using silver nitrate solution. This new CE protocol will contribute to applied research and help plants to better understand and eventually control the behaviour of cyanidation circuits."

Jan 1, 2011

By Thomas F. McLoughlin, David K. Hylbert

A new method of satellite imagery analysis has been developed during underground mine roof research. Landsat positive film transparencies were projected onto topographic base maps to scale and lineaments enhanced with a Ronchi grating (method A). Thirty-five millimeter slides of video-enhanced scenes were also projected onto base maps (method B). Both methods permit direct plotting of lineaments to scale and direct correlation with surface and subsurface data wing transparent overlays.

Jan 1, 1981