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By William Gleason

With more than 20 major mines extracting copper, gold, coal, molybdenum and lime, Arizona is recognized as one of the better mining jurisdictions, not just in the United States, but in the world. However, that is not to say the road to production is always paved with gold, or in many cases, copper. Earning the license to mine in Arizona is a complex process with years of paperwork and permitting before the first tons of ore are ever processed. Now, get the federal government involved and the process becomes even more complex, and the path to production can become even longer.

Jan 1, 2013

By M. E. Poad, W. G. Pariseau, M. A. Laurenti

In 1986, a cooperative effort by Homestake Mining Co., the US Bureau of Mines and the University of Utah was initiated to determine shaft stability while recovering high-grade ore in a nearby pillar. Premining finite element simulations indicated the shaft would remain in elastic ground. Six years have elapsed and, despite some initial concern during the first lifts, it appears that the bulk of the original reserve will he safely and profitably recovered. An integrated application of rock mechanics tools from laboratory testing through numerical modeling to mine measurements and observations contributed substantially to the operational success of the project.

Jan 1, 1996

By Carl G. Bock

INTRODUCTION Rapid transit systems involving near surface tunneling in hard rock are becoming more numerous, especially along the northeast corridor of the East Coast. Tunneled systems are under construction in Washington, D.C. and are being planned for Atlanta, Buffalo and Baltimore. Near surface tunneling is defined for this paper as being that in which the crown is 100 feet or less below ground surface. For Rosslyn Station, the total cover ranged from 52 to 70 feet. The rock cover, however, ranged from 40 to 50 feet which is slightly less than the station height and about two-thirds of its width. Rosslyn Station (Fig. 1) is the only station excavated completely in hard rock in the Virginia portion of the 98.5 mile Washington Metropolitan Area Transit Authority's (WMATA) rapid transit system. The station site, oriented in a north-south direction beneath a main thoroughfare and flanked by multistory office buildings, was fixed by the need to serve a dense population center at a specific location and geologic conditions were a secondary consideration in siting. There was no previous underground rock excavation in the Washington Metropolitan Area of the size and scope of Rosslyn Station that offered a practical case history guide to the geologic conditions and excavation problems to be encountered. GEOLOGY The regional geology of the Washington Metropolitan Area is divided into two physiographic provinces by the northeast trending Fall Line (Fig. 2). Northwest of this boundary is the Piedmont Province

Jan 1, 1974

Atlas Copco, a leading supplier of equipment and services to the mining and construction industries, is consistently pursuing its strategy to offer the most productive and economical solutions by continuously offering new innovative products. These are in most cases developed and tested in close cooperation with demanding end users before Being officially launched on the international market. The demands for higher productivity and improved overall economy have resulted in systems for automation of the drilling cycle and also tools for integrating the Drilling equipment to the production control system used by the customer. In terms of improving the blasted material quality, Atlas Copco has placed emphasis on hole straightness and the need for hole logging and positioning. By applying state of the art Technology to today?s computerized drilling rigs, major steps in improving overall drilling and blasting performance have been achieved. This paper will give some examples derived from the latest development of solutions for the Rotary drilling product line.

Jan 1, 2010

By G. Robert Frey

INTRODUCTION This chapter on underground rotary drills briefly describes the equipment features, selection or applica¬tion criteria, safety features, and relative costs of both face and roof drills. After a brief description of the basic components, the application, safety, and cost con¬siderations will be explored. ROTARY DRILL COMPONENTS As illustrated in Fig. 1, an underground rotary drill consists of five basic components. These components are the energy system, chassis, boom, feed assembly, and operator's station. Energy System The energy system of a typical underground drill con¬sists of an electric motor, driving a hydraulic pump or pumps. Usually, the drill is equipped with a cable reel to store the trailing power cable from the portable power center in the mine. A simple control box is supplied to house electrical switchgear and protective devices. In addition to the pump, the hydraulic portion of the energy system includes the hydraulic cylinders, hydraulic tram motors, relief valves, control valves, etc., necessary to actuate the various machine functions. Chassis The chassis provides the frame or support structure for the other four basic components of the drill. Fre¬quently, it incorporates an oil reservoir for the hydraulic system. The chasis provides the support for the trans¬mission, which drives rubber tires or, in the case of some foreign machines, the crawler tracks. The steering link¬age and steering tires also may be considered as parts of the chassis. Boom The boom is the structure that supports the feed assembly; it is either hinged or pivoted on the front of the chassis. Hydraulic cylinders on the boom are used to lift or swing the boom relative to the chassis and to swivel or "roll" the feed assembly. Feed Assembly The feed assembly is made up of the support struc¬ture with an integral thrust mechanism, a rotation unit, centralizers to stabilize the auger, and a hose handling arrangement. In addition, most drills have an extension frame with a tilt device to aid in positioning the feed. Operator's Station The operator's station is the area from which the miner operates the drill. UNDERGROUND ROTARY DRILL APPLICATIONS Underground Face Drills Underground face drills are used in mining opera¬tions that utilize the conventional mining system. The face drill is used to drill holes in the exposed face of the material, and the face is then "shot" by means of explo¬sives or high pressure air. The loose material then is ready for loading and transporting from the face to the preparation plant. Typical specifications for under¬ground face drills are listed in Table 1. Certain parameters should be established as to where the drill is to be used and what is expected of it. To create an awareness of some of the considerations that too often are overlooked, some questions are listed that should be asked in conjunction with the selection or application of the proposed drills. Energy System: Can the drill be supplied with the proper voltage to match the available or proposed elec¬trical power system of the mine? Is the system 250, 460, 500, 550, or 950 v; dc or ac; 3-phase; 60 or 50 Hz? Is the drill equipped with an adequate electric motor to handle the proposed duty cycle? Typical motor power on a single-boom drill would range from 25 to 40 kW (35 to 50 hp); the nominal power for a dual-boom

Jan 1, 1982

By C. T. Thompson

"Rotary percussion" implies two types of energy, rotary and percussion. Into these categories fall rock' drills of varying sizes. The larger ones drill above 6" diameter holes; the medium size, 2 3/4" to 4 1/2" holes; and the smallest, 1 1/4" to 2" holes. Essentially, the larger holes are drilled with doom-the-hole drills using tri-cone bits. Percussion energy evolves from the drill piston and rotation power from the rotary table or overhead drive, using drill collars or pull down mechanism to preload the bit.

Jan 1, 1963

By Harley G. Pyles

Rotary Percussion drilling has shown great improvement over rotary drilling, when hard roof is encountered. In addition, Rotary Percussion drills have eliminated the need for air drills in many applications. Improved drilling rates have been achieved but roof bolting is still a bottleneck in many operations and the demand for further improvement will continue. Drilling rates beyond current performance is limited by the capabilities of existing drill steels and bits to resist increased horsepower input. The most apparent immediate solution to improved drilling is to increase the strength and rigidity of the drill steels. Drilling experience indicates that a l-1/2" diameter or 1-5/8" diameter hole can be drilled as rapidly or 'more rapidly than the standard 1-3/8" diameter hole. Greater torque and thrust capacities can be achieved through the use of larger O. D. and I. D, steels, however, this is only possible if the larger hole sizes can be made allowable. Large diameter anchorage shells can be made available at a slight extra cost.

Jan 1, 1965

By Jacques Bernazeaud

Rouez is a recent discovery of a major low-grade sulfide body (± 100 m, 0,6 % Cu, 0.3 % Pb, 1 ,5 % Zn, 21 g/t Ag, 1.5 g/t Au) in a populated farming area of Brittany, France, some 30 kilometres northwest of Le Mans. The discovery is the result of an airborne electro- magnetic (INPUT) survey. It is the first time that the INPUT method has been used in France. The survey Gas successful in spite of the numerous interferences normally found in populated areas. The lack of a good drainage system would not allow the discovery of Rouez using stream sediment geochemistry alone. Ground geophysical surveys confirmed the airborne work and gave sufficient information to make the first hole a discovery hole. The deposit is Proterozoic in age and sediment-hosted. The metamorphism is low grade.

Jan 1, 1983

By S. Kittel, P. Galleguillos, H. E. Urtubia

The rougher flotation at Escondida consists of 80 cells of 100 m3 each, with injected air. Escondida has developed a system of automatic control of the rougher flotation using video cameras, which have been operating since 1997 for remote monitoring and manual control. Since 1999, an image processing software and a group of rules have allowed implementation of an expert system. To date, the expert system controls the superficial speed of each cell by adjusting the air flow and the froth depth of the flotation bank. Preliminary tests of the expert control on two of the eight rows gave 1.2% higher rougher recovery at a 92% degree of confidence. The proven benefits are already sufficient to move towards a complete plant implementation.

Jan 1, 2001

By James T. Furey, Laurence D. Hartzog, Graham A. Karklin

A pilot plant study was conducted to evaluate the performance of column flotation in the recovery of gold from the gold/tellurides bearing sulphide ore of the Kensington deposit (Echo Bay Mines and Coeur d'Alene Mines), and to compare the performance of column flotation to conventional "mechanically agitated" flotation, Tests were conducted in a 150 mm diameter, 60 liter glass column with ground flotation feed split from a concurrently operating conventional pilot plant, thus permitting direct comparison between the two processes. During the test program, the effects of wash water rate, gas holdup, froth depth, residence time and flow bias were examined in detail. The bulk metallurgical ore sample had an average "as tested" feed grade of about 5 git gold and 1 % sulphur, with the gold occurring primarily as inclusions of montbrayite (Au2Te3) in pyrite, with minor amounts of native gold. Conventional flotation using 60 minutes residence time across four roughing stages recovered about 97% of the gold into concentrates grading about 50 g/t Au. A single stage of column flotation roughing using 25 minutes residence time matched the conventional circuit recovery of97%, but produced grades of +150 git Au.

Jan 1, 1992

By Kerry Spickelmier

A traveler driving across desolate central Nevada to the Round Mountain property can easily identify with turn- of-the-century prospectors seeking a fortune, or at least an existence, from the high desert. But now a shadow passing overhead is as likely a sophisticated fighter aircraft from Stillwater Naval Air Station as a circling bird, and the famous trails west show only as historical markers along the highway. Even the approximately 400- km (250-mile) trip southeast from Reno or northwest from Las Vegas takes hours now, not days. And the camps of Round Mountain’s early prospectors have been replaced by one of the world’s largest gold heap-leaching operations. While Round Mountain’s uniqueness begins with its scale, it doesn’t end there. Consider the mine’s low cutoff grade of 0.2 g/t (0.006 oz/st) gold, made possible by a new dedicated (not reusable) leach pad. Also, the operation’s degree of automation means that ore dropped in the south crusher system is not manually handled until it is stripped from the pads. There is the bonus of a geothermal field that is tapped to heat the leach solutions in the winter. And, of course, there was that “unexpected” hitch expected in all mining operations. For Round Mountain, it meant buying a gravity plant to process the gold nuggets discovered last summer in a fault gouge.

Jan 1, 1993

By Erich U. Petersen

Chemical zoning studies of mineralization can be useful in guiding exploration efforts. They permit one to determine the limits of mineralization and to correlate mineralized intervals in drill holes. Fahlore minerals are well suited for zoning studies because they are common minerals found in a variety of deposits, exhibit chemical diversity, and record the chemical evolution of migrating hydrothermal fluids. Zoning information in the form of metal ratios preserved in fahlore minerals was used to determine ore body limits in the Orcopampa precious metal system, Peru, and to correlate between multiple ore horizons in a sediment hosted massive sulfide (SHMS) currently under investigation. The current generations of electron microprobes provide the most efficient, accurate and economic way to analyze the tens to hundreds of sample required to successfully describe and use zoning information at the mine scale.

Jan 1, 1991

By Don Suttie, Frank Roybal, John Wright

The Roybal Raise incorporates the simplicity and low cost of a short bald-headed raise while overcoming the usual impediments to driving a high baldheaded raise. The concept provides for speedy excavation and maximizing the use of the excavated opening, using the rock for structural support. The design is simple: two baldheaded raises are driven parallel to one another, interconnected by dogholes about 8 m (25 ft) apart. In this fashion, the raise can be driven safely and efficiently to 60 m (200 ft) or more. When the raise is complete, the excavation requires no timber for support or partitioning. Rather, the rock itself supports the construction. As a test, a two-compartment Roybal Raise was attempted at the Independence mine in the Willow Creek District of Alaska. One side was driven 2 x 2 m (6 x 6 ft), intended for a manway and equipment skip. The other was driven 1.5 x 1.5 m (5 x 5 ft) for a muck compartment. Both sides were driven at a 65° angle from horizontal and 1 x 1 m (4 x 4 ft) dogholes spanned the 4.6-m (15-ft) pillar between the two compartments. After topping out at 50 m (160 ft), the raise was found to meet all expectations of efficiency, low cost, and practical simplicity. Technique Preparing the Roybal Raise for driving involves no elaborate or costly site prep except assembling materials and providing for muck removal. Normally, the raise muck falls directly onto the sill or track and is picked up either by an overshot mucker or a front-end loader. Raise mining proceeds initially by taking up both compartments simultaneously to the first doghole. It progresses by alternating one side as a clear manway for access with the other side, the active side, as a muck compartment (Fig. 1A). This stage proceeds quickly for no mucking or staging is required to cycle the first three rounds. On the fifth round, in addition to the normal raise round, rib holes are winged out toward the adjacent raise, thus starting the dogholes. Finally, as the sixth raise rounds are drilled and shot, the first doghole is also completed from both sides. The second stage commences by establishing one side as a clear manway for access while the other side, used as a muck compartment, is prepared for active mining. Figure 1B illustrates this step in the succession of raising with the active side advancing to the second doghole level. During this stage, services are maintained through the manway side and equipment is stowed in the doghole during blasting. As the active side advances, muck may be allowed to fill the bottom portion of that side since it is unnecessary to clear it for access. The next stage of raising involves cleaning out the former muck compartment and preparing it for use as a manway. At the same time, the former manway is prepared for advance and use as a muck compartment (Fig. 1C). As in the previous step, the same doghole is used for access and equipment storage. The active side advances until the second doghole is completed, at which point equipment and access are moved to the new doghole. From there, the active side is driven past the second doghole 8 m (25 ft) more to the third doghole level. Again, half of the doghole and the next raise round are mined. The fourth stage involves switch ing back the manway side for the muck side (Fig. ID). The new muck side is driven to the third doghole where equipment storage and access are reestablished. From there, the active side is advanced to the fourth doghole. In the same fashion, the raise is advanced to the top, alternating the manway side with the active side, maintaining access through the inactive manway, and storing equipment in the uppermost doghole. The cycle time for driving each compartment, regardless of the raise height, is greatly improved over that for normal bald-headed raises of comparable height. By storing equipment in the upper-

Jan 1, 1984

By Henry H. Rubin

Rubber and its contributions to the economic solutions of environmental problems in the minerals industry. The intelligent applications of "Rubber" to systems of noise abatement, vibration isolation, dust containment, weak and corrosion resistance has proven economically beneficial. Intelligent application requires a thorough understanding of the nature of the material, knowledge of the process wherein it is going to be applied, and consideration of the environmental conditions in which it will serve, for these determine the proper amount, type, compound and configuration for an economically successful application.

Jan 1, 1979

By Joel K. Waterland

The Homes take Mining Company at Lead, South Dakota has a yearly production of 1,868,741 tons of ore produced from horizontal cut-and-fill stopes and timber cut-and-fill stopes. This production, in addition to the necessary development (drifts and raises), requires 5,168,271 feet of drilling annually. The rock for the most part consists of quartz; mica schist; and cummingtonite schist; and must be considered as relatively hard. Penetration rates average about 15 inches per minute using an operating air pressure of 100 psi. The rock is tough, rather than brittle, and dulling occurs quite rapidly. The average regrind period is approximately 19 feet per regrind using a 1-7/16 inch carbide bit. At the present time, all drilling is accomplished with 2-5/8 inch bore airleg mounted drills, and 2-3/4 inch and 3-inch diameter bore -stopers (raising only). These machines are all direct striking, with 4-1/4 inch chucks. 7/8-inch hexagonal carbon drill steel with forged collars are used in conjunction with 1-7/16 inch multi-use, threaded, carbide bits. 62,793 rods, and 16,234 bits are used to maintain the yearly production. The number of rods noted are the rods that were sent: underground, both new and reconditioned.

Jan 1, 1963

By Russell L. Dahl

In a continuing effort to improve plant efficiency, United States Steel's Atlantic City Ore Operations completed the rubber lining of its balling drums in late 1982. This resulted in benefits of reduced bentonite consumption, reduced maintenance costs, improved production rates, and lower power consumption. These advantages far outweigh the disadvantages of increased oversize production and increased surging on the roll screen sizing devices. Certain operating characteristics and variables are discussed herein.

Jan 1, 1983

By Christopher J. Bise

INTRODUCTION Face haulage in underground mines and pit haulage in surface mines are the principal domains of rubber- tired haulage vehicles. In underground mines, cable- reeled or battery-operated shuttle cars and diesel-powered load-haul-dump vehicles are used; trucks are primarily used in surface mines. Although many concerns go into the selection of rubber-tired haulage vehicles, such as clearance and tire life, the most important factor from a mine-planning standpoint is the production capability of the vehicle in the mine environment. Therefore, this chapter will address this topic. UNDERGROUND FACE-HAULAGE VEHICLES The selection process for underground face-haulage vehicles is, in some respects, much simpler than that of the other haulage systems discussed to this point. It is simpler because these vehicles, which transfer the mined material from the face to the intermediate haul¬age system, are manufactured in various size ranges to cope with the confinement of underground opening widths and heights. However, since these vehicles oper¬ated in an intermittent fashion in conjunction with a constantly advancing face, the system's lack of perma¬nence and overall dynamic nature create a more diffi¬cult situation for predicting productivity. The emphasis in this section will be on prediction of productivity. There are three fundamental steps that must be taken to analyze the productivity potential of any face¬haulage system: l) Recognize the geologic (seam thickness, etc. ) and mining (opening widths, etc.) constraints that affect the velocity/clearance aspects of the haulage equipment, and select equipment from manufacturers' specifications with these con¬straints in mind. 2) Secure the elemental times of the face-haulage system. 3) Incorporate the elemental times into an accepta¬ble mine plan. By recognizing the geologic and mining constraints that affect the system layout, parameters, such as vehi¬cle payload, tonnage to be hauled per cut, and haulage distances, can easily be determined. Elemental times can be developed in two ways: 1) In an existing operation, a time study of the dynamic system can be conducted by placing three time-study engineers at the following static locations; (1) near the loading machine, (2) near the change-out point outby the face, and (3) near the dump. By synchronizing their watches and recording the actions of the haulage vehicles at these three locations, their time studies can be reduced to provide elemental times, such as vehicle tram rates (empty or loaded), vehicle discharge times, and loading rates. 2) In the absence of an existing operation, average values for the elemental times can be provided from other mines operating in similar condi¬tions, or by the manufacturers themselves.

Jan 1, 1986

By Hung-Kei H. Lam

Rubidium and cesium were discovered by Bunsen and Kirchhoff about 100 years ago. These two elements are by no means as abundant as sodium or potassium. Their occurrence in minerals is widespread, but usually as minor constituents. There is no known specific ore containing rubidium, but rubidium is found replacing the. other alkali metals in .some minerals.. Perhaps the highest concentration of rubidium found in one mineral is in lepidolite, KLi(OH,F)2A12Si3010, which contains from 0 to 3.5%*Rb20. 0n the average, lepidolite contains about 0.5% Rb20. Other sources of rubidium are carnallite, KMgCl3?6H20; pollucite, H20.2Cs20.2AI203.9SiO2; rhodizite, R20.2A1203-3B203; biotite, H2K(Mg,Fe)3A1(Si04)3; sea water, rivers, marine and fresh water organisms, soils, and plants. Cesium, even though it is the least abundant. of the stable alkalies, has a specific ore. Pollucites a hydrous cesium aluminum silicate, may con¬tain as high as 42.5% Cs20, although again, the average Cs20 content is about 25% among the handful of known deposits. Other cesium-containing minerals are lepidolite and carnallite. Rubidium and cesium are very much like potassium in chemical properties, consequently, they are hard to separate. Because of the difficulty in obtaining pure cesium and rubidium compounds coupled with the scarcity-of supply, prices were high and the two elements enjoyed little industrial use. Just before the Second World War, the world. supply of rubidium and cesium, from Germany, was a matter of tens of kilograms per year and prices were about

Jan 1, 1959

By John R. Twining, Michael D. Lawton, Ross A. Jeffree

The Finniss River system in tropical northern Australia has received 'acid-drainage' contaminants from the Rum Jungle uranium/copper mine site over the past 4 decades. Following mine-site remediation that began in 1981-82 the annual contaminant loads of sulfate, Cu, Zn and Mn have declined by factors of 3, 7, 5 and 4, respectively over 1990-93, compared to the 1969-74 pre-remediation loads. Comparison of the frequency distributions of contaminant water concentrations over these pre- and post-remedial periods have shown varying degrees of reduction in the highest levels following mine-site remediation, that are consistent with reductions in their annual-cycle loads. Among the three selected major metal contaminants the reductions in maximum water concentrations are most pronounced for Cu. The demonstrated reductions in the highest water concentrations of all four contaminants are also associated with previously reported ecological improvement in the Finniss River system, compared to the benchmark of environmental detriment established in 1973fl4, prior to the beginning of remediation at the mine site.

Jan 1, 2000

By T. Braun

A greenfield open pit gold mine in Latin America suspended operations less than three years into an eight-year mine plan after a waste rock dump and heap leach facility sustained substantial damage from a deep-seated landslide. No injuries to employees were recorded because of the slow-moving failure. Due to early detection by the operations team, the owner had sufficient notice of the potential failure and successfully rinsed the heap leach facility prior to the failure event. Engineers estimated approximately 35 million cubic meters of mass movement below the waste rock and heap leach facilities. The original eight-year mine plan produced approximately 60,000 ounces of gold per year. After the failure, the owner terminated gold production, re-configured the mine site to a safe, standby condition and launched a detailed investigation into the root-cause of the failure. Approximately two years after the shutdown, legal interests filed a statement of claim and named three engineering design firms and individuals involved in the project. Several years of litigation, including discovery and deposition proceedings, followed as the legal process considered evidence spanning a 20-year timeline. Changes in project ownership and consulting firms during the development and operations phase complicated the process. In 2017, the plaintiff and last defendant settled. The author was involved as the corporate representative for one of the engineering design firms.

Mar 2, 2022