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The leaching of gold and silver by ammonium thiosulfate solutions in the presence of copper has been actively studied in recent years. Newmont Gold Company has successfully tested the ammonium thiosulfate for gold extraction following biooxidation pretreatment of low grade refractory carbonaceous/sulfidic ores. In this paper, the chemistry of the copper catalyzed leaching process is reviewed. Factors affecting both the leaching reactions and the stability of the lixiviants are reviewed and discussed from a solution chemistry perspective.

Jan 1, 1996

By Francis F. Pitard

The presence of elements, minerals, or chemical compounds in materials at very low concentrations is becoming a constantly increasing concern for several segments of the Industry. Some trace elements or chemical compounds may be considered as hazardous, some are simply considered as undesirable In complex processes where they could be constantly recycled and end up as the major factor of decreasing quality for some valuable products. In some other cases, the presence of a trace element or mineral may be highly desirable because of its economical value: precious metals are falling into this category, they probably were the first trace elements to draw our attention. Tremendous quantity of money is spent for analysis at the trace level, also the analytical "tool" has been considerably improved during recent years, but still the sampling aspect of the problem remains obscur for many, and because of it, large quantity of analytical efforts become meaningless. Not only the absence of sampling strategies is badly affecting the representativeness of a large majority of samples, but furthermore for the same reasons, many laboratories are failing In their endeavor to prepare reliable standard reference materials. The reason of this failure has its roots in the unability to estimate effectively the sampling characteristics of the element, mineral, or compound of interest, not to mention the unability to perform precise and accurate complete analysis, so essential for the instrumental analyst (1). In this paper a strategy to perform a better sampling operation is recommended. SELECTION OF A PROBABILISTIC APPROACH AS SOON AS PRACTICALLY POSSIBLE It Is essential to differentiate probabilistic sampling from non-probabilistic sampling. As Illustrated in Figure 1, the sampling operation Is a selection process which could be performed In two different ways: I. A probabilistic selection process according to which all elements of a lot of material to be sampled are submitted to the selection with a same probability of being selected. 2. A non-probabilistic selection process according to which all elements of a lot of material to be sampled are submitted to the selection with different probabilities of being selected.

Jan 1, 1986

By P. Berendsen

Structures along the rift were subjected to episodic reactivation. Major north-northeast-trending high-angle normal or reverse faults and northwest-trending trans-current fault systems, may exercise control over ore-forming processes. Gabbro and basalt are the dominant igneous rock types. Carbonatite and kimberlite occur in Nebraska and Kansas. Concentrations of Cu, Ni, Co, Ti, Au, Ag and PG-minerals are known to occur in this setting Arkosic sandstone, siltstone, shale and minor carbonate units occur on top of the rift basalts and in flanking basins where they may reach thicknesses of 10 km. The potential for stratiform or unconformity-related metal liferous deposits must be considered.

Jan 1, 1986

By C. J. Veal, C. I. House, S. R. Bellamy

INTRODUCTION Coal gold agglomeration (CGA) is a new concept in gold processing. It involves the recovery of oleophilic (oil-loving) gold grains by causing them to adhere selectively to the surfaces of coal oil agglomerates. Under optimum conditions very high recoveries of gold. can be achieved. The agglomerates are recycled to build up gold loading to typically 1000 - 5000 g/tonne. Bullion can be produced by burning the loaded agglomerates with subsequent recovery of gold from the highly loaded ash either by dissolution/electrowinning or smelting. A wide-ranging programme of laboratory testwork has been performed to investigate the response of different ore types to the process. This has shown CGA to be most applicable to ores in which the gold is liberated or easily liberatable, relatively coarse (ca 500 µm) and fine (<5 µm) gold grains being recoverable with equal ease. The best opportunities for CGA seem to be: • placers containing fine gold not recoverable by gravity concentration • low grade gravity concentrates to avoid multiple magnetic/gravity separation stages and amalgamation • free milling ores where the gold can be liberated at a reasonable ore particle size eg >d80 50 µm • tailings past or present from gravity concentration plants. CGA testwork ranging in scale from laboratory to pilot plant on tailings produced by gravity concentration in the 19th century Australian gold rush has already been reported (Bonney, C F, 1988; House, C I, Townsend, I C and Veal, C J, 1988). An economic appraisal for a Canadian free milling gold ore has also been published (Buckley, S A, House, C I and Townsend, I G, 1989). This paper describes results of a detailed laboratory programme to assess CGA as a means of recovering gold from a beach sand deposit in New Zealand. The area from which the samples were taken consists of quarternary interglacial marine, lagoonal, fluvial and eolian deposits. The heavy minerals present are predominantly ilmenite and garnet and small concentrations of gold. In certain locations the sands and gravels are consolidated by a limonitic cement. In the 19th Century some parts of the deposit were mined and the ore processed using stamp milling and gravity concentration. Gold recoveries were low, probably below 50%, due primarily to the fine size of the gold grains, the flaky nature of the gold and also imperfect liberation by the stamp mills. Our laboratory testwork was divided into three parts: i) Preliminary studies on an initial sample to assess the feasibility of treating the ore by CGA ii) Extended studies on further samples from various locations in the deposit to confirm predictions from (i) iii) Conventional gold recovery techniques. EXPERIMENTAL PROCEDURES All CGA tests were performed by agitating a slurry of ore in water in a 0.6 dm3 pyrex beaker fitted with four vertical baffles. When required, potassium amyl xanthate collector was added and the slurry conditioned for 5 min. Coal (ex BP Coal Australia&apos;s Tahmoor Colliery) previously ground to a d80 50 µm was added followed by a commercial grade of gas oil (density 840 kg/m3). The agglomeration time was 30 min. The agglomerates were separated from the tailings by screening, both were then dried and analysed for gold by fire assay. This test procedure provides a reasonably accurate estimate of gold recoveries that might be expected from our 1 tph pilot plant. Ore samples were ground either dry in an agate ring disc mill or wet in a steel batch tumbling

Jan 1, 1989

By P. Songfack

In this work, the slurry flow in the ball mill is solved with Navier-Stokes&apos; equations and the marker and cell technique (MAC), which tracks the fluid-free surface. Considering different planes in the radial and axial directions, this numerical approach leads to the direct calculation of the slurry velocity profile, mill holdup, and volumetric flow in the ball charge and pool. The MAC technique takes as input, the results of a direct three-dimensional simulation of the motion of grinding media, and in turn, provides a detailed knowledge of the hydrodynamics of slurry flow through the porous structure of ball load. This technique is a new approach to the mass transport problem that overcomes the limitations of indirect studies such as residence time analysis and holdup measurements.

Jan 1, 1994

By A. S. Azman

The mining workforce experiences high rates of hazardous noise exposure and hearing loss. However, previous studies have identified specific behavioral and attitudinal barriers that keep miners from effectively acting to prevent their own hearing loss. NIOSH has developed several new hearing loss prevention tools and interventions that specifically target these barriers to prevention. The NIOSH Hearing Loss Simulator addresses motivation to take action and knowledge about the consequences of noise exposure. The QuickFit earplug test device and QuickFitWeb online hearing protection tester address barriers to effective earplug and earmuff use by verifying at least 15 decibels of protection. The NIOSH Roll-Pull-Hold technique helps miners obtain better protection through an easy-to-remember set of steps that improves attenuation by 9 decibels. The ?Inquiring Ears Want to Know? fact sheet helps miners to understand audiograms and to use them to maintain their hearing health. Each of these interventions can be used within the context of a comprehensive hearing loss prevention program.

Jan 1, 2010

By Irvine G. Reilly

Results of a preliminary study of the ammoniacal leaching of covellite (CuS) in an aqueous oxidizing system in the presence of a non-miscible organic sulfur solvent are described. Up to 60% of the sulfur can be recovered from the solvent as elemental sulfur 1 while achieving high degrees of solubilization of the mineral. The effects of temperature, particle size, oxygen pressure, ammonia concentration and ammonium ion concentration on the degree of sulfur recovery were investigated. Maximum recoveries were achieved at moderate temperatures and in well-buffered systems, with a large excess ammonia concentration. Oxygen pressure and particle size were found to have little effect on fractional recovery of sulfur. A simple empirical model based on electrochemical theory correlating the effects of some of the parameters cont-rolling the degree of sulfur recovery is presented. The results of this work also confirm that in any proposed reaction mechanism for the oxidative ammoniacal leaching of copper sulfides, the primary oxidation product of the sulfide ion in elemental sulfur.

Jan 1, 1978

By C. W. Newcom

The mining industry continues to be under expanded scrutiny in the health and safety arena, both from federal regulators and the media. While this paper will briefly discuss how enforcement activity, both with citations issued and the size of penalties proposed, the primary focus will be practical suggestions to deal with some key, high-risk areas for a mine operator which could have substantial impact, both in terms of liability and mine operations. It goes without saying that all mine operators need to continue compliance programs they have in place with careful ongoing evaluation of those plans for areas of improvement. The focus here will not be compliance as such, but rather steps to take and procedures to have in place to try to minimize risks in the face of the potential for more significant liability. Thus, our focus will be procedures to respond to unwarrantable failure citations, immediately reportable accidents, and to deal with potential pattern of violation issues.1

Jan 1, 2011

By H. L. Monroe

Meramec Mining Company, owned 50% by St. Joseph Lead Company and 50% by Bethlehem Steel Corporation,- is engaged in the mining, concentrating and pelletizing of iron ore from the Pea Ridge Mine which is located in the rugged, wooded Missouri Ozarks about 15 miles from the town of Sullivan or 75 miles southwest of St. Louis. The orebody was delineated in the middle 1950&apos;s by the St. Joseph Lead Company during the Company&apos;s intensive exploration program to discover new lead orebodies to replace the declining reserves of the famous Southeast Missouri Lead Belt. An airborne magnetometer survey was run by the U.S. Geological Survey, the Missouri Survey and several mining companies, (of which St. Joseph Lead Company was the principal supporter). The survey was published in 1950 and disclosed an anomaly in the vicinity of Pea Ridge. In 1950 test drill holes disclosed that under some 1300 feet of sediments there did exist an iron deposit of probable commercial significance. No further action was taken until 1956 when additional drill holes confirmed beyond reasonable-doubt-that this was a major iron ore discovery.

Jan 1, 1965

By G. C. Kachel

Significant effort has been expended and considerable success has been realized m the application of instrumentation and automatic control equipment in the mining and ore processing industries. This effort has been applied principally to process equipment with the objective of increasing throughput, minimizing labor requirements and/or improving grade or product quality. Less spectacular, but quite rewarding has been the successful application of instrumentation and automatic control equipment to a wide variety of material handling equipments. This paper describes some of this work including: (1) automatic weighment of load-haul-dump units and trams underground; (2) automation of skip loading; (3) instrumentation applied in feeders and conveyors; (4) level measurement in bins, silos, vessels and sumps; (5) automatic blending of sized materials; (6) automatic loading of ships, trains and trucks; (7) automatic control of tailings disposal facilities

Jan 1, 1973

By A. M. Raichur

The selective adhesion of hydrophobic Mycobacterium phlei to coal particles is responsible for flocculation of fine coal from associated ash forming minerals. The driving force for the differential adhesion is the hydrophobic interactions between the fatty acid surface of the organism and hydrophobic nature of coal. The effect of Mycobacterium phlei on surface hydrophobicity, surface charge and mechanism of adhesion on coal and associated minerals are controlled by several factors including hydrophobicity and surface and solution chemistry of the system. Adhesion measurements indicate that maximum adhesion occurs below the isoelectric point (IEP) of the coal particles. While massive adhesion of Mycobacterium phlei is observed on coal, however, negligible amount of Mycobacterium phlei attaches to mineral pyrite and quartz.

Jan 1, 1995

By M. C. Stuttle

MDL Rock Lasers has undertaken successful mapping trials of abandoned mine workings using its underground cavity scanning system. The work was being performed for Kalgoorlie Consolidated Gold Mines (KCGM), Australia&apos;s largest gold producer. MDL Rock Lasers supplies underground surveying systems to the mining and quarrying industry KCGM&apos;s Fimiston Super Pit, located in Kalgoorlie, Western Australia, is Australia&apos;s largest open-pit gold operation. Fimiston&apos;s final pit design is expected to be 3.7 km (2.3 miles) long, 1.5 km (0.9-miles ) wide and 540 m (1,770 ft) deep. During the early days of Australian mining, underground operations were labor intensive. Mining was selective and generally narrow stopes were mostly backfilled. Improved processing technology and mine mechanization during the 1970s and 1980s has permitted larger scale operations to adopt less selective underground-stope operations. The "super pit" concept was a logical step for mining companies working toward economies of scale. However, the industry recognized that there was no precedent for excavating a 500-m- (1,640-ft-) deep open pit through ground previously affected by old workings. To appreciate the geotechnical challenge facing KCGM, it is necessary to consider that under the pro¬posed area at the open pit, stoping reached a level of 1 km (0.6 miles) and was supported by more than 2,000 km (1,240 miles) of development headings. The company was fortunate because plans were available for the Golden Mile underground operations. The existing plans were interpreted by the mine&apos;s geotechnical team and computer models were constructed of the underground workings. These models can be imported into three-dimensional mine planning packages, such as the Vulcan&apos;s Unix-based software, Envisage, to assist analysis and design. This prior knowledge of the workings provided the focus for investigating and confirming ground conditions using probe drilling. After several iterations of drilling, followed by detailed analysis, several decisions were made relating to the nature of the ground and the mining approach to be taken. It was recognized that the stope models were not perfect due to hu¬man error, lack of original survey information and progressive deterioration in ground conditions. It also became apparent that the sole reliance on probe drilling was inefficient in terms of time and quality of information. This was particularly true in complex areas where stopes are in close proximity. A major concern was the presence of open stopes (voids). In many cases, stopes consist of combinations of filled and void sections. The condition of pillars within these underground workings is extremely important. In time, pillars collapse and voids will propagate in upward and lateral directions. So systems needed to be developed that allowed rapid and accurate verification of ground conditions. KCGM was introduced to MDL Rock Lasers while investigating technology for underground mining. The two companies decided to use the C-ALS, MDL Rock Laser&apos;s underground laser, cavity scanning system, to improve the management of mining through affected ground. This system was to be used in conjunction with probe drilling and void mapping activities. A field test in one area of the Fimiston Mine verified the capability of the C-ALS system to quickly and efficiently assist in this decision making process. The C-ALS scanner features lightweight, carbon fi¬ber alignment rods from Measurement Devices Ltd.&apos;s (MDL) Boretrak MKII. This is a borehole deviation system that stops the two axis measurement head rotating and lowers the system down a borehole. The scanner is deployed by a 110-mm (4.3-in.) borehole, up, down or sideways. The operator can then carry out vertical and horizontal plan section scans at any user specified ARC (an angular increment of 2°) or the distance between two points on the ARC (CHORD) increments. Windows &apos;95 software enables the operator to control the cavity scanner remotely, surveying the area in real time. The system makes data quick and convenient.

Jan 1, 1999

By Sue Sawyer

In October, November and December, teachers at the National Science Teachers&apos; Association (NSTA) area conventions were lured to visit the Minerals Education Coalition (MEC) booth by the promise of free rocks, video tapes, and literature on earth science topics. Teachers were content to stand in lines that at times took as much as an hour and a half to progress through the exhibit. Adding to their interest was the opportunity to converse with people from the minerals industry who were staffing the booth. The MEC was formed by a group of associations and companies in the minerals industry. They felt the need to educate the public about the current-day minerals industry and how it affects everyone&apos;s life. The American Institute of Mining, Metallurgical, and Petroleum Engineers, Inc. (AIME) underwrote the major expenses of exhibit space and exhibitor services at all three conventions in 1997. SME members have been active in staffing and chairing the NSTA exhibit booth. But they represented only about one-third of the volunteers for the booth. Additional volunteers were drawn from local minerals companies, associations, interested teachers and other support groups. (See donors list on page 64.) In 1997, the conventions were held in Pittsburgh, PA, Denver, CO and Nashville, TN. The local SME GEM Committees chaired Pittsburgh and Denver and The Rogers Group Inc. supplied the chairperson in Nashville. Each exhibit relies on a local committee to plan and run the booth. Support is available from the GEM Projects Coordinator at SME headquarters. Usually the chair of the committee is drawn from the local SME membership. It is easy to see why the MEC booth is so popular. Free literature, videos, posters, workshop packets and rock specimens were handed out to about 5,500 science teachers at the three sites. Feedback from the attending teachers was overwhelmingly positive: "Who do we thank for these great materials?" Some of those great materials included Caterpillar&apos;s outstanding donation of Common Ground videos and teacher packets for Pittsburgh, Denver and Nashville for every teacher expected to attend. Placer Dome sent enough What&apos;s a Mine coloring books and It Comes from a Mine activity books for teachers at all three sites. Newmont supplied all teachers with an excellent poster describing gold processing. Women in Mining Education Foundation had plenty of its classroom activity handouts. The American Coal Foundation provided a list of its educational materials that are given out free to teachers who request them on school letterhead. The National Mining Association had its Facts About Minerals and Facts About Coal available. US Borax provided the funding to reproduce the NMA black and white posters that were published as inserts in Mining Voice magazine. In addition, each site had other materials chosen by the local committees to round out their selections. At each exhibit site, committees raise between $8,000 and $12,000 in cash donations from industry to support the high overhead of producing this exhibit. Usually, there are between 12 and 18 different rock specimens representing a range of mineral ores from aggregates to the metal ores. The committee arranged to have these donated (along with the freight charges to ship them to the site). Literature is also donated by the industry. It covers a diverse spectrum from basic information on rocks and minerals to posters, flow charts, videos and coloring books. Other donations include storage space before the event, haulage of items to the hall and door prizes. These exhibits could not have been staged without the network of SME Local Sections and the able chairs and committees at each site. At this time, credit should be given to their extensive donation of time and effort.

Jan 1, 1998

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&apos;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&apos;s Station The operator&apos;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 M. A. D. Azevedo

The effect of pulping reagents on the flotation de-inking of laser printed wastepaper was investigated with regard to the removal efficiency of toner and mineral filler particles for different pH values. These results show that caustic pulping causes the toner to be released from the fibers at larger particles sizes. On the other hand, acid pulping not only causes the toner to be released at smaller particles sizes but also increases the concurrent flotation removal of mineral filler particles. It was experimentally observed that the froth generation and stability during flotation were improved for acidic pH values.

Jan 1, 1997

By E. Yan, M. Mankosa, G. Luttrell

"During the past decade, column flotation cells have become widely accepted for upgrading ultrafine sulfide ores. However, the use of columns has been widely relegated to cleaner circuits due to their comparatively high selectivity derived from the use of wash water dispersed over a deep froth. High tonnage rates and low feed grades make using column technology in roughing and scavenger stages challenging due to the resulting size of the needed equipment. To specifically address this challenge, a new high-intensity flotation system known as the StackCell™ was developed. This technology makes use of a novel pre-aeration method coupled with froth washing to simultaneously provide improved flotation kinetics and selectivity. The novel aeration system provides efficient bubble-particle contacting thereby shortening the residence time required for particle collection. This article reviews the technical design features of this new flotation technology and presents recent data from in-plant pilot testing in a copper-sulfide application. INTRODUCTION Column flotation cells have become very popular in the minerals processing industry for cleaner circuits due to their ability to produce a high-grade froth concentrate via the use of froth washing (Luttrell et al., 1999; Kohmuench et al., 2004). The use of wash water minimizes the nonselective recovery of ultrafine impurities that are normally entrained into the froth product from conventional flotation machines. On the other hand, the unique design of a column cell typically requires a large tank volume. Column cells must be tall to ensure that the pulp residence time is long enough to offset their inherently slow flotation kinetics and to minimize internal mixing that is detrimental to overall cell performance. The tall design minimizes the total floor space required for the column installation, but substantially increases the foundation load. The large size of the column tank can also create issues during fabrication, transportation and installation. To address these concerns, the engineering team at Eriez Manufacturing developed a next-generation flotation technology called the StackCell?. This high-intensity flotation machine was designed to provide column-like separation performance within a very compact volumetric footprint. This article describes the key working features of this new technology and provides data from recent pilot-scale tests conducted in gold and copper-sulfide applications"

Jan 1, 2016

By S. B. Patton

A computer model, which quantitatively utilizes the relationship between the interactive and dynamic processes of methane drainage, mining, and ventilation, is presented. The model includes simulation of the coalbed methane reservoir for prediction of gas-emission rates under the influence of degasification wells and longwall mining, ventilation network-generation, and ventilation simulation. As mining progresses step-wise through the coalbed-methane reservoir, the ventilation network is created and subsequently simulated, iteratively determining fan requirements to safely reduce methane concentrations. The model can be used to quantitatively study the effectiveness of methane degasification on the ventilation system in a longwall panel.

Jan 1, 1992

By L. M. Pruett

The Arizona Legislature is currently in the process of considering mined land reclamation legislation in the 1994 legislative session. A bipartisan legislative study committee has drafted proposed mined land legislation. The committee has attempted to craft legislation that is appropriate for the unique conditions in Arizona. Existing Arizona and federal laws and regulations extensively regulate the environmental performance of mines in the state to protect public health, safety and the environment. The proposed mined land reclamation legislation does not replace or duplicate these statutory provisions relating to environmental protection. Instead, the purpose of the proposed legislation is to provide for the reclamation of land that is being mined and to fill the gap in existing laws by requiring the reclamation of land that currently is being mined or that has been mined since 1986 to provide for future land use. The legislation would require an operator to submit a reclamation plan describing the exploration operations, mining operations, post-mining land use and the proposed reclamation measures for review by a state agency. Financial assurance also would be required in an amount such that a third party could complete the approved reclamation measures. Arizona&apos;s mined land reclamation legislation would recognize Arizona&apos;s leading role in hard rock mining and emphasize the mining industry&apos;s economic importance to Arizona and the nation. Because mining operations necessarily require disturbing the surface of the earth to extract valuable minerals, reclamation requirements would be adapted to different conditions and would vary depending on site-specific conditions and on the commodity being mined. The current proposal does not identify the state agency that will administer the mined land reclamation program and approve reclamation plans, substantial changes to plans, and transfers of reclamation plans to other operators.

Jan 1, 1994

By K. F. Unrug

The concept of bolting mine roofs to prevent roof falls was initiated in the 1950&apos;s and was quickly accepted by the mining industry because it was inexpensive, effective and convenient. The principle regarding roof bolting were that: a) the loose and fragmented rocks were suspended from or clamped to more competent surrounding rock and b) generally, by clamping several layers of thin and laminated strata, a more competent monolithic beam is created.

Jan 1, 1991

By G. Pierson

Explanations of commodity price levels, or movements, commonly focus on the supply and demand fundamentals of the particular commodity, or else are assigned to speculative activity. Comparisons of metal price histories with monetary and other economic data support the argument that the supply of and demand for money are no less important in price determination than are the supply and demand of the commodity itself. That these relationships should exist is evident in the price identity and are consistent with monetary theory. The patterns developed have limited usefulness as predictors, but their recognition is essential for the construction of price scenarios for planning purposes.

Jan 1, 1996