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By P. R. Day, W. K. Webster

"The introduction of large boreholes underground initially involved taking the techniques of open-pit bench blasting to the production stope, but with deeper boreholes and narrower stopes more controlled techniques must be developed in order to maintain good stope walls and prevent dilution of ore or structural damage to pillars due to blasting overbreak. The points discussed are drilling accuracy and drill pattern, the relationship between open-pit wall control and underground mining, the varied explosives products and initiation devices available, and some of the many ways that variations in loading, such as deck charging, etc., can produce desirable results.IntroductionThe use of large-diameter blastholes for underground mining began ten years ago and today they are widely employed in a variety of orebodies and stope configurations. These big blastholes, which range in size from 4.5 to 8 inches in diameter, were originally employed in the same manner ' as open-pit bench blasts; that is, the stope was silled out to full width and all holes were drilled vertical and parallel. This was suitable for competent, massive orebodies, however the popularity of the big drills saw their usage in more narrow stopes, often with poor ground conditions. The dipping orebodies and small drill sublevels resulted in inclined drilling.Today, there is full-ring drilling of 4.5-inch holes. Some 6.5-inch holes are drilled up to 350 feet deep. A 350-foot borehole may contain 6000 to 7000 pounds of explosive. The detonation of this size of charge weight within the confines of an underground stope can have considerable effect on the stability of stope walls and adjacent pillars. Obviously, precautions must be taken to minimize the damage which would result from the large charge weights possible with these big boreholes."

Jan 1, 1982

[RALPH ADAIR Ore Dressing Consultant Bull Mtn. Rd., Asheville, N. C. Phone 4-1693 JAMES A. BARR Consulting Engineer Mt. Pleasant, Tennessee Washington, D.C. BEHRE DOLBEAR & COMPANY Consulting Mining Engineers and Geologists 11 Broadway New York 4. N. Y. I. R. BERENT Engineering Consultants and Contractors Mineral Exploration, Mine Evaluation, Mine Designs and Mine Management 156, Ataturk Bulvarl-Ankara, Turkey BLANDFORD C. BURGESS Registered Professional Engineer Mining Consultant Monticello, Georgia GLENVILLE A. COLLINS Mining Engineer Uranium examinations Cable "Coins" 210 La Arcade Bids. Santa Barbara, Calif.]

Jan 1, 1952

By Sohta Takatsu, Hachiroh Mizubata, Shigeki Kudoh, Kazuya Takekuni, Yoshinori Yamada

A special type of shotcrete is used to improve the performance of open-type TBM in difficult situations. The Hakamagoshi and Johana tunnels are expressway evacuation tunnels of 3.2 km and 5.1 km in length, respectively (total 9.1 km) that were excavated by one open-type TBM. The geological conditions at the sites were estimated to be good before excavation. However, 95% of the rock turned out to be two ranking orders worse than the estimated classes. Therefore, we used a special shotcrete for bad rock conditions, and succeeded in excavating the tunnel at an average rate of 270 m/month.

Jan 1, 2001

By L. G. Stolarczyk, Y. Luo, S. S. Peng

Detection and assessment of severe geological anomalies ahead of a longwall face greatly benefits the mining operation. Electromagnetic-based Radio Imaging Method (RIM) is one of the most promising geophysical methods for this task. Based on two decades of development, the latest RIM instrumentation (RIM-IV) has expanded its operational range up to 1,800ft.A site demonstration of the RIM-IV technology was recently conducted within a longwall panel. An extensive ground truth study was performed to evaluate the accuracy of the RIM survey results. This study compared the generated RIM tomograms of attenuation rate with the mapped geological anomalies. Three different approaches have been employed to examine the accuracy of the RIM results and to correlate the measured signal attenuation rates with physical properties of the coal seam. The study shows that the RIM-IV technology is able to identify and delineate those geological features that would severely affect the longwall mining operation.

Jan 1, 2004

By L. E. Lynd

Ilmenite concentrates prepared from beach and dune sands of Florida, India, Australia, and other localities deviate to varying degrees from the theoretical composition of pure ilmenite, and generally contain more TiO2 than the formula FeTi03 would indicate, and some Fe2O3. This variation in composition is due to different amounts of altered ilmenite in the concentrates. (') The alteration has been shown to take place by oxidation and leaching of the iron in ilmenite, to yield residual products consisting of amaphous or very finely crystalline titanium dioxide and ferric oxide. Other studies(2) have stressed that ilmenite may alter first to an amorphous titanium-iron oxide, or to an amorphous mixture of titanium and iron oxides, with later alteration to crystalline titanium dioxide. There has been some speculation as to whether alteration of ilmenite is usually caused by weathering or by hydrothermal pr0cesses.(3,4,5 Three main methods of approach were used to study the mechanism and rate of ilmenite weathering. (1) Etch tests were used to learn the relationship between crystallographic orientation and the rate of chemical attack on ilmenite. (2) Altered ilmenites in New Jersey sands were compared with ilmenite in rocks of the area from which the sands were probably derived. (3) Experiments were carried out to determine at what rate, and by what agents, originally fresh ilmenite could be altered in the laboratory under simulated weathering conditions. ETCH FIGURES ON ILMENITE CRYSTAL PLANES A rather large ilmenite crystal from Sannidal, Norway, about 11/2 x 11/2 x 2 inches, bearing a few natural faces with imperfect surfaces, was prepared for etching by grinding and polishing crystal planes whose Bravais-Miller indices (referred to hexagonal axes) had been determined by X-ray methods to be 00.1, 10.0, and 10.2. Metallographic examination showed that the crystal was homogeneous, and uniform in orientation, except for the presence of twin lamellae which were oriented with their broadest surfaces parallel to the 00.1 planes of the large crystal. Since ilmenite is rather inert to standard etch reagents, strong solutions of hot sulfuric acid and cold hydrofluoric acid were used. Preliminary tests established that better etch figures were obtained using HF than with H2So4 solutions. The etch figures produced on 00.1 and 01.0 planes of ilmenite by etching 3 to 5 minutes in cold concentrated HF solution are shown in Figures 1, 2, and 3. The figures on 00.1 are "etch hillocks", rather than pits, and according to Honess(6), this phenomenon

Jan 1, 1961

By K. Whysner

The recycling of metal resources in mining influenced water (MIW) requires a paradigm shift from within the mine water treatment industry. The potential to recover zinc for beneficial use in the micronutrient fertilizer industry was investigated through a survey of zinc micronutrient fertilizer representatives. An application of the findings to a case study of the Argo Tunnel influent MIW was then implemented. It was concluded that the potential to beneficially reuse MIW residuals in fertilizers exists; the current process sequences of treatment will need to be modified if metal recycling is to be prioritized.

Feb 27, 2013

By T. G. Carter

Support system design for tunnels and underground excavations has for many years relied heavily on the use of rock mass classification systems and the Hoek-Brown failure criterion as a means for characterizing rock mass behaviour. Because of their development, both the GSI system and the Hoek-Brown criterion admirably characterize most ?normal? rockmasses from the viewpoint of their behaviour for rock excavations. They, however, run into difficulties when applied at the two ends of the rock competence scale. This is largely because block size and incipient strength are such that rockmass behaviour in these domains tends not to be controlled by interblock shear strength but rather by material strength. At the low end of the rock competence scale (UCSi <<15 MPa and GSI generally <30) discontinuities play less of a role and rock mass strength tends to matrix strength. Similarly, at the high end of the scale (GSI >>65, mi>>15), because discontinuities are now widely spaced, block size becomes so significant that again, intact material behaviour rather than the fracturing becomes the dominant factor controlling rock mass strength. In this paper several case examples are presented to illustrate the application of the high-end (spalling) and low-end (weak ground) transition Hoek-Brown relationships proposed by Carter, Diederichs and Carvalho (2007) as a basis for better defining rockmass behaviour at the extreme ends of the rock competence scale.

Jan 1, 2008

By D. J. Steynfaard

Sishen Iron Ore Mine is situated 280 km north-west of Kimberley in the Northern Cape Province of South Africa. The mine produces and sells high quality iron ore of various specifications to various national and international clients. The saleable product is derived from the blending and beneficiation of different types and qualities of hematite iron ore. This paper documents the new developments which were implemented (or are in the process of being implemented) on the mine in the long-term planning, medium-term planning, grade control and material tracking in the beneficiation plant with special attention being paid to the quality of the final, saleable product. The process starts with the long-term planning where the pit shell and pit optimization is determined by Whittle 4X. New developments include the introduction of a linear programming based scheduling system to enhance the long-term schedule generated by Whittle 4X. The LP route was decided on in order to take into account all the constraining factors of the final product that could not be configured in Whittle. To complement this the XPAC Auto Scheduler scheduling package was introduced to do the medium-term mine scheduling. This 18-month rolling plan includes cost parameters to enable the planner to extract a detailed operational budget from the scheduling while ensuring that production standards are maintained and grade constraints are met. The existing grade control system was enhanced with GPS capabilities and a computer system to do material tracking. The high precision GPS system introduced on the shovels allows for the accurate control of the loading procedures at the mining face. Because of the complicated geology and grade composition of blasting blocks it is imperative to accurately differentiate between different materials in the same blasting block and being able to excavate that with the loading equipment. The GPS system on the trucks allows for accurate location monitoring of dumping in order to keep track of specific material types. The state-of-the-art material tracking system developed for Sishen will enable the grade control officer to keep track and record various parameters of the material from its in situ position in the blasting blocks, through the crusher and onto different stockpiles, in various stages of the beneficiation process and onto the blending beds, into the dispatching trains and eventually into the ships for international distribution. These developments elevate the Sishen planning and grade control systems to a new level of service excellence from which management can obtain accurate and timely information on product status. It also enables Sishen to maximize resource utilization while still complying with the tough market constraints.

Jan 1, 2003

Northern Iron Ltd (NIL) is an Australian listed company that recently brought the historic Sydvaranger open pit Magnetite Mine (the Project) in Northern Norway successfully back into production. NIL made the decision to operate the Project on an owner mining basis, due to limited large scale mining expertise amongst Norwegian mining contractors, a long mine life, a limited range in planned mining rate and to minimise costs. As a new mine operator in a country where labour practices are strictly regulated, there was the desire to reduce the risk associated employing and managing skilled personnel. This was achieved by coupling the purchase of the required mining equipment from the original equipment manufacturer&apos;s (OEM) regional dealers with OEM supported Maintenance and Repair Contracts (MARC). This paper examines the process that was followed to implement an owner mining operation in a short time frame; approximately 12 months from the initial requests for quotation to actual delivery of mining equipment to site, and some of the challenges faced. By following a formal and well-tested process, not only was the implementation achieved in the set time frame, but significant value was added through the cost savings achieved in the equipment purchase price and MARC rates that were negotiated through this process.

May 1, 2010

By Valentine A. Chanturiya

The aim of this paper is basically to show progress in the study of nanosecond processes involved in the disintegration and breaking-up of mineral complexes with fine noble metals. We studied the influence of nanosecond High-Power Electromagnetic Pulses (HPEMP) on the physical and technological properties of refractory gold-containing ores and beneficiation products. Experimental data are presented to confirm the formation of breakdown channels and selective disintegration of mineral complexes as a result of pulse irradiation, which makes for efficient access of lixiviant solutions to precious metal grains and enhanced precious metal recovery into lixivia during leaching. Preliminary processing of gravity concentrate with a HPEMP resulted in significant increase of gold and silver extraction into lixivia during the cyanidation stage, with gold recovery increased by ~31% (from 51.2% in a blank test to 82.3% after irradiation). Gold recovery from stale gold-containing dressing tailings products increased after pulses-irradiation from 8-12% to 80-90%.

Jan 1, 2006

By J. E. Murphy

The u.s. Bureau of Mines investigated electrode designs for electrowinning lead metal from a LiCl-KCl-PbCI2 electrolyte at 4500 C. The major objective of this investigation was to decrease the energy requirement for lead electrowinning. Electrolysis was performed in a bench-scale cell using several graphite electrode assemblies. Such parameters as electrode spacing, current density, and chlorine gas removal from the anode were investigated in the bench-scale tests. An optimum electrode assembly, termed the sawtooth design, was scaled up and operated at 3,000 and 4,000 A. The sawtooth electrodes operating at 3,000 A produced lead for 0.66 kW·h/kg. The electrodes were constructed by cutting large triangular grooves in the electrode surfaces. The electrodes were placed together such that the triangular peaks of one electrode projected into the triangular valleys of the other electrode. Chlorine did not build up on the anode with the sawtooth electrodes.

Jan 1, 1991

By E. J. Ripling, M. W. Toaz

Tensile tests were conducted on pure magnesium and on four commercial alloys over a variety of temperatures and strain rates. The high positive slope of the ductility vs testing temperature curves that is found over a short range of testing temperatures for these materaturerials was shown to result from the fact that the microstructure was not stable at these testing temperatures. Pure magnesium did not display a transition temperature, although its sub-room temperature ductility was low. This poor ductility resulted from a grain boundary weakness. The aluminum-bearing commercial magnesium alloys had a higher ductility than the pure magnesium. ness.Thealuminum-bearingcommercialThese alloys did exhibit a transition temperature and grain boundaries that were stronger than the grain material. Both pure magnesium and the commercial alloys began initiating cracks at strains equal to one half of their fracture strain. MAGNESIUM base alloys&apos; enormous potential as structural materials lies in their high strength to weight ratios. At present, the high strength magnesium base alloys such as AZ-80, which will be discussed later, have about as high a tensile strength to specific gravity ratio as the highest strength wrought aluminum alloy, 75s-T6, and, of course, a much higher strength to weight ratio than structural steel. Further, since the magnesium base alloys develop their high strength to weight ratios with moderate strengths and extremely light weights, the ratio of load carrying capacity to the weight of many structures is relatively higher for the magnesium base alloys than their strength to weight ratios would indicate. This results because judicious increases in section size, such as increasing the depth of bending members or adding reinforcing ribs, can frequently increase the weight of a structure linearly while the strength and stiffness increase as the second or third power of the added weight. Strength and rigidity must be designed into lightweight structures by those techniques which establish multiaxial stress states. Consequently, strong, lightweight structures frequently also possess a greater propensity toward brittle failures. In order to insure against these catastrophic failures, an extra premium must be placed on ductility and toughness in light alloys. Current knowledge of the ductility and toughness behaviors—notched behaviors—of magnesium base alloys is limited.* Most of the magnesium base alloys * The state of present knowledge regarding the effect of testing temperature on mechanical properties has recently been summar-ized by Pritchard.&apos; crystallize in the hexagonal system, so that they are expected to exhibit a tough and ductile to brittle transition temperature. Actually, a transition temperature behavior has been reported for commercially pure magnesium in the literature, but the characteristics of this transition temperatureh uggest that it may not be a transition in the usual meaning, but simply the onset of some thermal softening, a performance much like that which face-centered-cubic lead might exhibit slightly below room temperature. If transition temperatures do exist, such important questions as the manner in which they are affected by internal variables such as chemical composition and grain size, or the effect of external variables such as rate of straining or notch severity have never been investigated. The investigation reported upon herein was undertaken in order to define some of the mechanical behaviors of the magnesium base alloys better, to gain a better understanding of the influence of some of the above listed variables, and particularly to understand their effect on ductility and toughness better. Material and Procedure Material-—Pure magnesium and four commercial alloys were used in this investigation. The alloys were selected so that chemically they made up a series with approximately the same minor alloying

Jan 1, 1957

By Bertrand L. Johnson

The major elements essential to plant growth are nitrogen, potassium, and phosphorus. These three constituents of the soil are removed relatively rapidly by growing crops and consequently are the main constituents of commercial fertilizers. Scientific studies, however, have progressively revealed the fact that a number of other plant foods, many of which are not necessarily supplied in commercial fertilizers, are necessary to assist plant growth and fruit production and that soils deficient in certain of these minor elements may be made much more productive by adding them. The farmer looks to the miner to furnish most of the elements requisite to plant growth, which have to be supplied through the medium of fertilizer additions. It follows that the mining industry should keep an eye upon developments in the fertilizer industry and in the results of soil studies as a possible outlet for mineral products. The important industries engaged in the production and marketing of the three principal pant nutrients have already been described in Bureau of Mines publications .3 The present paper discusses the commercial implications with respect to other elements that are now employed as soil additions.

Jan 1, 1935

By Brendan Donnelly, Jung-Hoon Sul, Lasitha Piyathilaka, Sanghyun Jeong, Benjamin Probyn

The chains of armored face conveyor (AFCs) are constantly in contact with water and wet coal, which results in a significant proportion of unplanned downtime experienced on longwall equipment due to corrosion. While reverse osmosis (RO) is one of the most prevalent water treatment methods for reducing salinity and dissolved solids in coal mining, its impact on the corrosion of the AFC chains has not been well studied. This work studies the direct effects of RO water on the corrosion of AFC chains. Immersion tests followed by surface micromorphology analysis and corrosion indices indicate that the RO water increased the corrosion rate of the AFC chains due to the reduced tendency of preventive films on the chains.

May 1, 2024

By Ruilin Yang

Blast vibration in the highwall from a cast blast in open pit mines or in the hanging walls from a stope blast in underground mines is a common concern. Vibration in such cases is a typical near-field situation where the distance from a blasthole to a point of interest varies significantly compared to the distance between the blast as a whole and the point of interest. Most existing blast vibration models are designed for far-field vibration using a single seed wave to represent all blastholes within a blast and do not simulate wave shape change over the distance. Using the site parameters from the analysis of signature hole vibrations, the present blast vibration model yields reasonable agreement with field measurements in terms of vibration amplitude and frequency. Case studies show that the model has been used successfully to assist field vibration control.

Jan 1, 2010

In setting out to describe the methods and machinery employed at Iron Knob the writer does not attempt to give any information as to the situation, topography or geological features of the locality. This, together with estimates of the quantities of ore still available, has been carried out in a most thorough manner by R. L. Jackr and F. R. Hockey. This essay is intended to deal with working methods as they exist to-day, beginning with drilling, blasting, quarry traction, etc., and touching on such details as the supplyof electricity, water and compressed air.At the present time almost the entire output of ore is won from the hill known as Iron Monarch. The form of the hill, a smooth, rounded dome, rising some 640 ft. above the plain and having a base diameter of n miles, lends itself ideally to the &quot;bench&quot; system of open-cut quarrying.Fig. 1 shows the relationship of the benches &quot;A,&quot; &quot;B&quot; and &quot;E&quot; in their order of development. Bench &quot;E&quot; is at present the principal working, but, as the greater part of the ore above this level has now been removed, bench &quot;A,&quot; some...

Jan 1, 1936

By Donald F. Reed

In the Coastal Plain sedimentaries of northeastern Mississippi, high-alumina clays and kaolins, which are bauxitized locally to varying degrees, are found in many places along the contact between the Midway (Paleocene) and the Wilcox (Eocene) series. The trace of the contact extends from Tippah County, on the Tennessee border, south to Winston County, thence southeast to Lauderdale County, and into Alabama. Its length within Mississippi, disregarding sinuosities, is 185 miles (fig. 1). Commercial production of bauxite from the region has amounted to about 400 tons, shipped from one outcrop in Komper County. In December 1941 and January 1942, the Bureau of Mines and the Federal Geological Survey made a reconnaissance survey of the contact zone and selected the most promising areas for further study. In 1942, four areas in Benton, Union, and Pontotoc Counties were investigated by auger and rotary core drilling, and in 194, core drilling was done on five areas in Kemper, Noxubee, and Winston Counties. The present report records the work done by the. Bureau of Mines and the factual data obtained from the investigations of the nine areas in the two projects.

Jan 1, 1952

By J. R. Thoenen

In Progress Rerort 1,4/ a number of facto were demonstrated and conclusions drawn from experimental tests and records made during commercial blasting operations at a number of quarries. For example, the tests showed (1) that vibrations received on outcrops were of comparatively

Jan 1, 1938

By Charles E. Whieldon

Data on the oil fields in Mahoning Columbiana, Carroll, Jefferson, and Harrison Counties, Ohio, were collected from scattered sources and com- piled to make the information readily available to operators who may be interested in conducting secondary-recovery operations in the area. General geology, oil production, oil-productive acreage, core data, reservoir calculations by townships, and miscellaneous data and reference material are presented.

Jan 1, 1965

By Eric R. Borys, Amaneh E. Kenarsari, Brett Gitskin

This case study discusses impacts of excessive Earth Retention System (ERS) lateral movement at a project in city of Chicago. The ERS (cantilevered sheeting) moved inward towards the excavation and caused lateral displacement and cracks in six drilled shafts located about 1 to 2 lateral feet (0.3 to 0.6 m) from the face of the sheet pile wall. Up to 9 inches (23 cm) of horizontal movement was observed on top of the supporting sheet-pile. Similarly, survey measurements showed the top of the drilled shafts moved laterally up to 8 inches (20.3 cm). To evaluate the cause of failure and determine a remediation solution, the soil, shaft and site conditions were investigated. Pile Integrity Tests (PIT) were conducted at the affected drilled shafts. The shafts with identified anomalies were cored and video-recorded. The cause of the failure was determined to be related to variable soil conditions across the site, deeper excavation (i.e., increased effective ERS wall height), and other differences between design and as-built conditions. Internal bracing, in the form of walers and rakers, was installed to limit further movement of the sheet pile as a short-term solution, with additional grade beams framed into the basement slab-on-grade as a long- term solution. Five of the six cracked shafts were spliced with reinforcing bars and high strength grout and one shaft was replaced. INTRODUCTION The subsoil in the Chicago Area mostly consists of glacial till clays underlain by water-bearing granular soil over bedrock. The glacial clays have very soft to medium consistencies for a typical thickness of 30 to 50 feet (9.1 to 15.2 m) below which hard clays (Hardpan, i.e., heavily over-consolidated clay soils) are encountered. The soft clays are often referred to as the “Chicago Blue Clay”. Beach Sands are also found above upper soft clays in several areas, especially within a three-mile strip near Lake Michigan (Peck and Reed 1954). Due to the existence of soft clay in Chicago area, supporting the mid to high rise buildings on drilled shafts extended to Hardpan is a common practice in modern building design. In the early 19th century it used to take about 3 weeks to excavate 1 shaft hole and about 1½ days to fill the shaft with concrete in Chicago (Manierre 1916). The early 19th century methodology of excavating a shaft consisted of hand digging the shaft, installing wood lagging as temporary shoring with spoils removed with a rope and pulley system from the surface. Today, the excavation of a typical drilled shaft in Chicago uses heavy drilling equipment and requires much less time for excavation and concrete placement. It is not uncommon for contractors to excavate shafts and place concrete at a rate of about 2 to 5 drilled shafts per day (with one drill rig).

Jan 1, 2018