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By Frank J. Hirner

Economic open-pit and surface mining often call for ever increasing volumes of lower grade materials. So it is important, often critical, to develop precise expense and production estimates for the large electric mining shovels now in use. An electric shovel's basic application is to "shovel up" material, starting at ground level with the dipper moving up into a working face or bank. It's impractical to dig below ground level with a shovel, except briefly or in unusual circumstances. The shovel working face is "the bank," whether the material is dug from natural bed or blasted. The shovel's digging attachment, the boom and dipper handle, is built in standard and long range configurations. A standard digging attachment is normally used for loading into haulage equipment. The long range attachment is normally used for side or hack casting to a spoil pile. It is also used fir loading into haulage equipment placed above shovel ground level, as in some coal loading applications. Shovel clipper size and hauler capacity should he matched so that a hauler can he loaded in three to four shovel work cycles. Five cycles is usually the limit of good practice. If fewer than three cycles are required, the hauler is too small. More than five cycles indicates possible excess harder waiting time for loading, or shovel waiting time for too few haulers. Full dipper loads, including the last dipper or ''pass, " are essential for economical shovel and hauler match. Consistent need for a final partly full dipper to fill the hauler shows an improper match between the two.

Feb 1, 1981

By Malcolm J. McPherson, Daniel J. Brunner

This paper describes an experiment conducted to investigate the law of airflow on a mechanized longwall coal face. Background to the Square Law relating frictional pressure drop and airflow is presented and deviations from this Law are discussed. The procedures used to investigate the Law of Airflow for the longwall are described and the results are presented. The results verify the Square Law relationship for airflow along a mechanized longwall face.

Jan 1, 1987

By N. S. Tanious

Retrievability of emplaced nuclear waste from the geologic repository is a performance objective imposed by Federal Regulations. This requirement is designed to provide confidence in the Department of Energy's repository design by keeping the option of retrieval open if the engineered or natural systems prove inadequate for containment and long-term isolation of high-level nuclear waste. This paper presents a summary of current Nuclear Regulatory Commission Staff thinking on the design of the repository for retrieval, and level of retrievability demonstration that may be required during site characterization. However, this paper does not represent official U.S. Nuclear Regulatory Commission position on this topic.

Jan 1, 1989

By W. R. Hopkins

Over 95 percent of the world's refined copper is now produced by electrolytic processes. The bulk of this electrolytic copper comes via the conventional route for sulfide ores of concentration, smelting and electro-refining. A rapidly increasing percentage of world production is now achieved using hydrometallurgical routes involving dissolution of the copper values from minerals, purification of the resultant leach solution by solvent extraction and finally deposition as cathodes by electrowinning. The technology can now be considered mature and this paper endeavors to summarize recent developments which, from the authors' perspectives, are important.

Jan 1, 1989

By Yoshinori Shimada, Oleg Kotiaev, Hiroaki Sakamoto, Toshihiro Asakura, Naotoshi Yasuda, Norikazu Misaki, Masahiro Shinoda

"To ensure that trains run safely, the performance of railway civil engineering structures is checked by periodic inspections. General inspection method has merits and demerits, but none of them offers the combination of high accuracy and quick inspection. In an effort to resolve this problem, West Japan Railway Company, the Institute for Laser Technology and the Railway Technical Research Institute jointly developed a remote laser sensing system as an alternative to the impact acoustics method for detecting defective concrete elements in tunnel linings. The proposed remote laser sensing system has two lasers, one to apply an impact to the concrete surface and the other to measure the vibration of the concrete generated by the impact laser. The impact laser is a high-energy pulse laser that induces vibration in the concrete. The detection laser has a signal beam and a reference beam. The signal beam reflects on the concrete surface and goes into the dynamic hologram crystal. The reference beam diffracts in the dynamic hologram and enters the detection sensor with the signal beam. The vibration of the concrete surface can be measured to detect the movement of an interference pattern. A prototype of the remote laser sensing system was developed as shown in Figure1. A vibration and acoustic insulators are equipped to remove a noise generated from a maintenance car or electric generator in this system. The proposed laser remote sensing system and the detection algorithm were verified with the help of field test conducted in a tunnel on the Shinkansen. An impact test using hammering was applied to obtain the accurate response acceleration on the surface of the concrete before application of the proposed method. In this test, the result obtained from the proposed method has good agreement with that obtained from the impact test by hammering. Consequently, it is verified that the proposed method can be used as an alternative to the standard impact acoustics method."

Jan 1, 2016

By Joseph Kurtak

When prospectors discovered mineralized outcrops in Pine Creek Canyon in 1916, little did they know the site was destined to become one of the world's greatest tungsten mines. Located outside Bishop in California's rugged Sierra Nevada mountain range, the mine's development imposed unique challenges to the hardiest of mining men. In its early years, the Pine Creek operation was plagued by bad luck and poor timing. But through the perseverance of a dynamic group of mining personalities, it would gain world class status. Pine Creek tungsten supplied much of the defense needs of the United States during World War II and put the Bishop area on the map as a major contributor to the nation's stockpile of strategic metals. The mine's history was shaped by world politics, the ups and downs of metals demand and economic survival through technological innovations. In contrast to many mines, Pine Creek's workings went horizontally into and then up inside the mountains - nearly to the ridgetops. This resulted in the name "Mine in the Sky" being attached to the operation. The origin of Pine Creek's ore bodies is related to the emplacement of a portion of the Sierra Nevada batholith about 100 million years ago. During the intrusive process, granitic magmas engulfed overlying calcareous sedimentary rocks, flooding them with silica-rich hydrothermal fluids and metamorphosing them to skarn. The fluids also contained tungsten, molybdenum and copper. They precipitated as scheelite, molybdenite and chalcopyrite, respectively, during the metamorphic process. The ore-bearing skarns occur as near-vertical tabular pendants in the intrusive rocks. These were later exposed by the uplift of the Sierra Nevada mountain range and glacial erosion.

Jan 1, 1998

By Harry R. Price, Jerome C. Neyer

INTRODUCTION Safety must be a primary consideration in the design and construction of tunnels. Tunnel construction has historically been considered a high-risk business. During the construction of the 14.8 kilometer (9.25) mile St. Gotthard Tunnel in the Swiss Alps in the 1870s, 310 lives were lost and another 877 workers permanently disabled. In more recent days, two tunnel construction accidents in 1971, one in Michigan and one in California, claimed the lives of 38 workers. Prior to 1971, most regulations governing safety in tunnel construction were developed by the U.S. Bureau of Mines. These included a 1941 Bulletin 439, "Some Essential Safety Factors for Tunneling" and a 1968 Bulletin 644 which updated Bulletin 439. In 1970, the United States passed the Occupational Health and Safety Act (OSHA) which became effective in early 1971. That act covered all sorts of workplace activities including Tunnels and Shafts in 29 CFR 1926.800. In 1989, a revised and renamed 29 CFR 1926.800 was issued for Underground Construction. Some of the changes introduced in this rule were the outgrowth of improvements made in the California and Michigan codes after the 1971 accidents. These new regulations are the "Rules to Live By" for tunnel construction in the United States and are generally accepted as appropriate for tunnel construction throughout the world.

Jan 1, 1995

By D. Maxton

INTRODUCTION This paper traces the application of High Pressure Grinding Rolls (HPGR) at industrial and pilot scale in Australia. The Argyle Diamond Mine installed the first of two smooth segmented HPGRs during 1990 in an open-circuit secondary-tertiary crushing application to increase throughput. In 2002 a third HPGR was added to improve liberation and so increase the recovery of smaller diamonds. The latest improvements in wear technology (tyre with tungsten carbide studs) were incorporated in the design of this machine. Extensive HPGR pilot-plant trials were undertaken during the 1990s at both the Kalgoorlie Consolidate Gold Mine and the Boddington Gold Mine. The purpose of these trials was to evaluate HPGR as a method to increase throughput, as an alternative to SAG milling, and also to ascertain if downstream benefits existed. One of the challenges for HPGR circuit designers is to translate what occurs at small laboratory and pilot scale into what is likely to happen in a full-scale circuit. Scale-up from pilot machine results is normally recommended by manufacturers. However, such tests need relatively large quantities of material, particularly if meaningful data on wear are to be obtained. Laboratory tests are preferable, as they need relatively small quantities of ore, but may be questioned in terms of how they relate to full-scale operation. Modelling and simulation have played a particularly important role in this respect in Australia. Models are available which have proven to be very accurate at being able to scale throughput and specific energy response from laboratory to industrial machines. More recently, work in Australia has also been done in developing a model which has the potential to scale laboratory wear data as well.

Jan 1, 2004

By Fathi Habashi

IT APPEARS that the phenomenon of ion exchange by which saline water was converted to sweet was known to Moses and Aristotle. However, the credit for the recognition of this process is generally attributed to Thompson (1850) and Way (1850), who reported that when a soil was treated with either ammonium sulfate or ammonium carbonate solution, most of the ammonia was adsorbed and calcium was released. It was later proved by Eichorn (1858) that the adsorption of ions from ground waters by clay constituents was a reversible process. The first attempts to utilize ion exchange phenomena was in the field of water softening around 1906, using natural and synthetic silicates. In 1935 Adams and Holmes in England observed that crushed phonograph records (phenol-formaldehyde and amine-formaldehyde resins) were capable of exchanging ions.

Jan 1, 1970

By Agne Rustan

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

Jan 1, 1980

By S. Chander, A. Briceno

The properties of surface films on pyrite have been studied through electrochemical techniques of cyclic voltammetry and AC impedance, measurements. The characteristics of the surface films depend on the conditions of oxidation and the source of pyrite. At potentials near 0.0 V, some pyrites have large values of polarization resistance, showing a certain degree of passivity. Some pyrites show more passivation than others, however. On oxidation, meta- stable phases of Fe(OH)2 and Fe(OH)3 form that transform to more stable phases on aging. The growth of surface films near the corrosion potential of pyrite follows a linear kinetics that is attributed to a chemical (or an electrochemical) reaction as the rate determining step. The surface film is considered to be a hydroxide or an oxide because it is hydrophilic. This study has also demonstrated that AC impedance ,measurements can be used to study the growth characteristics of films at mineral/solution interfaces.

Jan 1, 1988

By Robert L. Bonomi

One of the major operating costs for any labor-intensive operation is that of its employees' wage and benefits package. Today's packages are extremely complex, with multiple pay rates for different grades and shifts, intricate bonus criteria, and expansive benefit packages that include all sorts of medical, dental, pension and other costs that can be "hidden" from direct examination and consideration. The problems of estimating the total cost of such a package to a company becomes even more acute at negotiation time, when pressure from both sides to settle intensify and changes to package offers come rapidly. A comprehensive system is needed that can evaluate these costs and perform sensitivity analyses, on the various components of an agreement so as to aid in the solving of major labor deadlocks, productivity problems, and cost impacts created by those agreements.

Jan 1, 1982

By S. K. Vidyarthi

Most wastewater clean-up processes suffer from a fundamental lack of specificity in that a Reverse Osmosis process removes all dissolved solids, an Electrodialysis Reversal process removes all ions, wanted or unwanted, etc. Most techniques require the use of a membrane or contact surfaces that are prone to foul-up and are ineffective in situations where solids may be present. A photochemical process for the metallurgical industry on the other hand has the ability to operate specifically on targets that can range from one selected ion to an entire group of homologous species such as all biologically active species. Processes can be designed to change the oxidation states of a target altering the environmental impact. Several processes are currently in operation ranging from Cyanide removal to disposal of radiation wastes. This paper describes applicable photochemical processes with the help of certain key model examples.

Jan 1, 1988

By O. Akinkugbe

The safe, productive exploitation of coal in multiple-seam situations requires specific design technology. At present, there are two general design approaches that the mining engineer can use to analyze the multiple-seam problem in question, either simple empirical relationships or complex numerical models. Often, the empirical approaches are too general for the specific problem and the numerical models require too much time and expertise for the practicing engineer. In this paper, a new program designed for quickly and easily calculating the stresses, strains, and safety factors associated with basic multiple-seam mining situations is presented. The program implements a simplified, two-dimensional boundary-element method in order to model the complex multiple-seam stress and displacement interactions. The program incorporates automatic coal and gob property generation to simplify the input, and inherently calculates pillar safety factors to enhance the output.

Jan 1, 2004

By Gastón Díiaz, Enzo Carranza Meza

El Teniente Mine of Codelco-Chile, located at Los Andes Range of Mountains, 90 kilometers South far from Santiago, the capital city, has been exploited for more than 90 years, with over 1000 million tonnes of copper ore extraction. No doubt, this particular record, has been possible to achieve due to an efficient combination of human and technological efforts in the exploitation of one of the biggest ore deposits of the world. Throughout times, the exploitation has evolved from a mainly manual one to a highly mechanized exploitation. Notwithstanding, different and several geomechanical problems that occurred in one of its areas, increased the risks to personnel that should normally operate large equipments in its working face. This last condition, forced El Teniente mine to design and develop systems and technologies that would allow the use of tele-operated LHD, picking hammers and drilling equipment (jumbos) from a safe zone. Currently, El Teniente Mine is using in its extractive works equipment such as LHD, picking hammers, and drilling Jumbos, that can be manually or teleoperated commanded from a Central Control Room located one kilometer away from the production area. In general, a new technological era has been opened in the mining exploitation at El Teniente: the exploitation era with telecommanded robots.

Jan 1, 1998

By Richard M. Bennett

Twelve linear test foundations were constructed over an advancing longwall panel in southern Illinois, six were located along the centerline, and six in the maximum tension zone. One footing in each set was a control foundation constructed according to conventional practice. It suffered severe damage. Footings with reinforcing bare and post-tensioning had much smaller elongations, with the post-tensioning preventing cracking of the footing. Footing-soil interface treatments of plastic-on-sand and plastic-on-soil served to reduce damage. The addition of steel fibers to the footing had about the same effect as an interface treatment. Sill plate construction (butt-jointed versus lap-jointed) appeared to significantly affect the behavior.

Jan 1, 1986

Africa is rich in natural resources, much of which remain untapped. Despite that, international mining companies have largely stayed away from the continent due to political instability in many countries, lack of infrastructure and the inability to gain control of mineral deposits. Today, optimism is growing concerning African mining. Many of its nations are moving toward privatization of their mining industries. They see it as a way to improve the lives of their populations and become politically stronger. Ministers from 22 African nations were Denver, CO in June for the World Bank's Multilateral Investment Guarantee Agency's Fourth Annual African Mining Investment Symposium. The three-day symposium drew more than 400 mining executives and government representatives. Foreign mining investment in Africa is on the increase. In 1996, international mining companies spent about $418 million on exploration. That is more than double the $190 million spent in 1994. Mining executives say the mining climate in Africa is improving because countries are privatizing the industry and rewriting mining laws that encourage natural resource development. They estimate that private mining firms now control about 80% of mining today. Mine development will help lift the living standards for Africans, the ministers said. The average income for ordinary Africans is about $500 a year. If this new mining boom continues, citizens of nearly all African nations will reap the benefits of better infrastructure and government services, as well as more higher paying jobs, the ministers said. They also issued a word of caution to mining companies attempting to join in the African boom. Concerns are being raised about the treatment of villagers and the environment. In the past, foreign companies would "behave about like colonial masters," said Gerald Ssendaula, natural resource minister for Uganda. Africa is in a different position now, he said. "Now we are solving our own problems." Mining companies must respect local communities or risk creating unrest that will threaten fragile new governments, said Akolang Tombale, chief geologist for Botswana. On the other hand, he said villagers must accept that mining development will benefit them. "They feel these are their natural resources. There must be a mutual interaction between the companies and the people."

Jan 1, 1997

By Judith M. Ballantyne

Carlin-type. disseminated, sediment-hosted gold deposits can be better described as hydrocarbon-associated gold deposits. A new genetic model for these deposits involves the intrusion of one or more small bodies of magma into a shallow hydrocarbon reservoir or ma of hydrocarbonenriched rocks, imposing a convecting geothermal system on the local groundwater. Pyrite, commonly associated with the organic material, provides a substrate for deposition of gold and other trace elements in an environment rich in dissolved sulfide. Both diagenetic and hydrothermal pyrite may act as gold depositional sites. Thermal cracking of hydrocarbons, catalyzed by illite, subsequently generates an oxidizing environment by depleting hydrogen. As oxidation increases, arsenic sulfide minerals and barite m stabiied at first. Increasing hydrogen depletion converts sulfide to sulfate, generating acid oxidizing conditions which: alter pyrite to hematite; continue the deposition of sulfates; and ultimately develop late stage acid-sulfate assemblages containing minerals such as kaolinite. alunite. and jarosite. Gold released from the oxidizing pyrite is redeposited as free gold, and pehaps remobilized.

Jan 1, 1988

By Terry Quinlan

The financial evaluation of an orebody uses estimates for the grade of ore produced during each year for the life of the mine. Assay data from the Dolphin Scheelite Mine is used to estimate grades by the Polygonal, Ellipsoidal and Disjunctive Kriging Methods. The results are compared with simulated production data, to show the existence of a bias associated with each method. The affect of bias on the financial evaluation of a theoretical model ia assessed.

Jan 1, 1979

By B. K. Mishra, R. K. Rajamani

A numerical method known as the discrete element method (DEM) is used to track the motion of individual balls in large-diameter ball mills. As a result, the en masse motion of the charge, force distribution, fall-height distribution, and energy distribution emerges from the simulation. Hence, it is possible to investigate the effect of mill diameter, liner profile and ball size distribution on the force regime created within the mill. Simulation results for 14-, 16- and 18-ft diameter mills are shown. The proportion of energy lost in high-intensity impacts and sliding ball motion is discussed. The DEM simulation technique opens the way for a closer examination of liner profiles on ball-charge motion.

Jan 1, 1992