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By Tracy E. Chantson, Brian R. Green, Kenneth G. Ashurst

Work that has culminated in the manufacture and testing of a old-selective resin on a pilot-plant scale is dcscribed. Following a brief discussion about the nature of commercially available resins which identifies them as poor candidates for a gold extraction application, the improved properties of the new type of resin are illustrated using results from comparative loading tests. Further results from continuous countercurrent extractions using synthetic leach liquors and elution work using thiourea as the eluant demonstrate the superiority of the new resin over commercial resins and hence, its potential for use in a resin-in-pulp process for gold.

Jan 1, 1989

By W. D. Monaghan, A. J. Kwitowski, A. L. Brautigam

Teleoperation is a technology that can provide significant health and safety improvements in mining operations by locating machine operators hundreds of meters away from the face area. The US Bureau of Mines recently developed a teleoperation system for continuous mining and haulage equipment. This system features near real-time closed-loop control. A prototype system was developed and demonstrated. This system could be used in thin-seam applications down to 36 in (914 mm). Provided are details of the teleoperation system, the results of testing and the expected applications of this technology.

Jan 1, 1996

By R. Hogg

The factors which control the dewatering of fine coal by gravity/centrifugal drainage and by gas displacement (vacuum/hyperbaric filtration) are evaluated. A generalized model is presented and used to describe dewatering kinetics and to establish dewatering limits. Applications to the design of dewatering systems for fine coal dewatering are discussed.

Jan 1, 1995

By R. J. Gochin, G. D. Schena

Mineral processing options and technical innovations should be financially assessed. Indeed technical feasibility alone does not offer an adequate process selection criterion. An appraisal by the use of engineering economics principles leads to a more efficient evaluation and selection of feasible mineral processing solutions. Financial consequences of different options synthesised by profitability indices allow better decision making. Selected examples derived from real world problems are used to illustrate the potential of engineering-economics methods applied to mineral processing.

Jan 1, 1995

By Peter Mathias

The ventilation of long headings tunnels has al- ways posed special problems. The authors trace the progress of one such project from the design stage through the practical problems encountered to the final solution.

Jan 1, 1980

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 John C. Franklin

INTRODUCTION Alpha-emitting radon daughter products are a recognized health hazard contributing to the development of lung cancer in persons exposed to excessive concentrations over an extended period. The primary control technique used by the mining industry is dilution with fresh air. Because the uranium is deposited in porous sandstone in most U.S. mines, the control of this hazard with dilution requires excessive volumes of air. As the mines become larger and deeper, the cost for ventilation becomes a major expenditure for the mining industry Most mines are maintaining levels of radon daughters lower than required by law but to maintain these present levels the mining companies are going to be drilling more vent holes or using other control techniques as the mine expands. These control techniques are being investigated by the U.S. Bureau of Mines to determine their effectiveness, cost, and safety for underground use. [Instrumentation] The Bureau's early research used batch sampling of both radon and radon daughters for determining the concentrations. In both cases it was determined that batch sampling did not give a complete understanding of what was happening to the concentrations. Therefore, continuous monitoring systems were developed for both. A continuous flow-through radon monitor was developed by the Bureau (Franklin, et al.., 1976) using a modified Lucas flask mounted on a photo-multiplier-tube (PMT). The air was filtered twice prior to entering the flask to remove dust, diesel smoke, moisture, and radon daughters. The signal from the PMT was then inverted, shaped, and driven to a data acquisition system (DAS) which accumulated the signals. The DAS has two comparators for setting the scan time and interval, a 24-hour clock with Julian date, a printer, and a perforated paper tape punch. Sampling time is determined by the type of experiment being conducted. Our normal sampling time is one 10-minute scan every 15 minutes, but could be set as low as one scan every minute or as long as a 16-minute scan every 167 minutes. There are two models of the DAS. One is a 10-channel system and the other a 30-channel system. On a 10channel system normally 6 channels are used for radon and radon daughters and the other four channels are used for temperature, absolute pressure, air velocity, and relative humidity as described by McVey (1977). Figure 1 shows a scan of five channels monitoring the radon concentration from intake to exhaust in a stope for a non-work day. If the radon concentration stayed this constant during work days, then continuous monitoring would not be necessary. [ ] Droullard (1977) developed a continuous alpha-beta monitor. This monitor has been modified so that it can be used with the DAS previously mentioned. Control Techniques The U.S. Bureau of Mines has conducted research in controlling airborne radon/radon daughter for 10 years. Major efforts have been conducted in sealing the rock to prevent the release of radon, bulkheading to seal nonproductive areas, backfilling with classified mill tailings, and positive pressure ventilation. Also, tests have been conducted to determine the mining cycles contribution to the radon problem. Surveys One stope with two intakes and one exhaust was continuously monitored to determine the effects of blasting, mucking, and drilling on the airborne radon concentrations (Franklin, et al., 1976). Two other detectors were located inside the stope which were close to the mining activity. In this stope no appreciable change in radon was observed during drilling holes for blasting and roofbolts. This study showed increases up to 40 percent in radon for slushing in the exhaust drift. The radon remained high and very eratic during slushing, as can

Jan 1, 1981

By Hassan El-Shall, M. N. Ahmad, Ponisseril Somasundaran, C. R. Holland, G. M. Walker, N. Iles, R. D. Chandler, Regis Stana, B. Duddy, Patrick Zhang

Phosphoric acid is a major raw material for the production of ammonium phosphate (AP) that is used as an intermediate in fertilizer production. Impurities within commercial grade wet process phosphoric acid are important in producing a fertilizer granule with good handling properties. The impurities identified as being important are; iron (III), aluminium and fluorine-containing compounds. Results show that the viscosity of the AP slurry produced increases by increasing the amount of impurity in the acid. Bench scale tests have been successfully replicated on a plant scale leading to a better understanding of the composition of impurity levels within phosphoric acid required to produce a high quality, free flowing, hard, spherical and non-caking granular fertilizer.

Jan 1, 2002

By Victoria Vaccarezza, Corby Anderson

The demand for rare earth elements for everyday technology and applications has initiated much research into the extraction and recovery of these rare earth elements. An otherwise unknown group of minerals, eudialyte is a zircon silicate consisting of rare earth oxides (REO), contained in a unique mineral structure and represented by a complex chemical formula. Research into extraction and recovery of rare earth elements involves various beneficiation and hydrometallurgical techniques. The goal of beneficiation being to efficiently liberate and upgrade the REO content, followed by hydrometallurgy to extract the desired elements. This overview will discuss previous research on treating eudialyte group minerals via different mineral processing and extraction techniques.

By L. Stas

The authors have been interested in stress measurements in the rock mass for a long time. This paper describes the development of new apparatus for stress measurements in a rock mass. The principle of stress measurement by this device is based on the relief method as applied on the conical shaped surface of the bottom of a borehole. The design started based on the experience of K. Sugawara and Y. Obara who have been using the compact conical borehole over-coring system (CCBO). The conical shape of the strain gauge probe CCBO makes the fixation of the probe in borehole easy and, also, makes the measurement of stress in independent directions possible. The principle of the measuring method, the preparation of the borehole, the design of the probe for continuous measurement of stress during the course of overcoring are described. Also, a simplified version of the probe for long term monitoring of stress variations in the rock mass by means of the inserted body method and the initial laboratory results and in-situ testing of the development sample are described. Additionally, testing was done regarding the possible glues in relationship to the creep effect for this case.

Jan 1, 2006

By W. R. Dearman, N. Turk

A seismic fissuration index (K) is defined as the ratio of the difference in the P and S wave velocities obtained when a dry rock specimen is tested both under a load equal to half the uniaxial compressive strength of the rock (Vo) and without an applied load (Vd) to the velocity obtained without an applied load (Vd), as K = (Vo - Vd)/Vd. A similar seismic fissuration index is also proposed for classifying the dry rock mass in terms of field seismic velocities. The field equation is extended by including the intact rock seismic velocities. K is found to be related to the porosity of rocks. The proposed equation can equally be used for characterizing saturated rocks, using S-wave velocities. However, the time average equation should be used for characterizing saturated rocks, using P-wave velocities, even though this equation gives upperbound estimates of the rock material and fracture porosities.

Jan 1, 1986

By Charles A. McLean

Bucketline dredges are machines for excavating large relatively unconsolidated or weakly consolidated materials from below water level. They are at the upper end of the capital cost range and the lower end of the operating cost range for placer mining machines and have digging capacities, typically, of from 100 cubic yards of bank measure material per operating hour for a shallow digging dredge carrying 2 cubic foot buckets to 1500 cubic yards per hour for a large deep digging dredge with 33 cubic foot buckets. Bucketline dredges used in the mining industry have their mineral processing plants mounted aboard the digging hull. Since dredges are high capital cost items, they require large ore reserves, typically at least ten years. Because of their high capital cost they are usually operated around the clock and for as many months of the year as weather conditions will permit. Typically a well run dredge operating year round would be expected to operate for 600 hours per month. Dredges operated in cold climates cannot operate when the weather freezes the dredge pond or the gravels, and dredges operating at sea cannot operate when high waves might batter the digging ladder against the bottom or upset the mineral extraction process.

Jan 1, 1992

By Lijun Xu, Ragula Bhaskar

The transport of dust particles from a turbulent air stream on to the surface of a mine entry is mainly due to the effect of diffusion, sedimentation and inertial impaction. While the literature in aerosol science contains many references on particle deposition, most studies apply to smooth surfaces in small, short tubes. The deposition data from those experiments may not be applicable to deposition in mine airways that have large areas of rough surfaces and extend several thousand meters. This paper describes the mechanisms of mine dust transportation and deposition, specifically, by estimating the turbulent deposition velocity for coal dust in mine airways. Data from in-mine experiments on ambient dust concentration and dust deposition along a straight entry were used. A statistical model for dimensionless turbulent deposition velocity was developed, and compared with the models developed by other researchers. The model shows that the distance from the dust source is an important factor in the turbulent deposition of mine dust.

Jan 1, 1995

By K. Nuttall, S. Vijayan, A. J. Meinyk, R. D. Singh

For conventional applications, there is limited demand for rare earth elements as well as yttrium and scandium. But the emergence of new high technology applications such as supermagnets, lasers, and superconductors should result in significant demand for some of these elements. This article examines the anticipated applications and demands for rare earth elements over the next decade. It also looks at the implications on the use of available resources. In the context of a growing demand, process methods are reviewed for the recovery of rare earth elements from conventional and unconventional resources. And the article also discusses the challenges facing the mining industry in meeting this opportunity. Reserves and reserve base The rare earths (RE) are a homogeneous group of metallic elements occupying the area from lanthanum to lutetium in group IIIB of the periodic table. Yttrium and scandium are also included with the rare earths because of their chemical similarities and common existence in nature. These 17 elements and their atomic numbers are shown in Table 1. The rare earths are widely distributed in low concentrations throughout the earth's crust (Hedrick, 1985). They occur in many rock formations including basalts, granites, shales, and silicate rocks at concentrations of 10 - 300 ug/g. They also occur in more than 160 discrete minerals. Most of these are rare, but may contain as much as 60% rare earth oxides (REO). More than 95% of the REO occurs in three minerals: monazite and bastnasite for the light rare earths and xenotime for yttrium and the heavy rare earths. Apatite and multiple-oxide minerals, such as euxenite and loparite, are also commercial sources of the lanthanides and yt-trium. Rare earths do not occur in nature in the elemental state. And, except for scandium, they do not occur in minerals as individual compounds. Bastnasite and monazite are the two major minerals used commercially to supply most of the rare earths (Hedrick, 1985). Bastnasite is a key raw material source for the cerium subgroup elements. The largest known bastnasite deposit occurs with iron ore minerals in China. The second largest deposit is situated in California. Typical rock analyses of the fluorocarbonate mineral bastnasite deposit in California show about 15% bastnasite. The REO content of that is about 50%. Monazite is present in beach sands in many parts of the world. This includes India, Brazil, Australia, South Africa, the

Jan 1, 1989

By R. J. Sweigard, R. V. Ramani

Estimated costs and revenues can be used in evaluating postmining land use alternatives. However, postmining land use decisions have to be made in an environment complicated by several additional factors. These factors, including cultural, natural, and managerial issues, are not as easily quantified as costs and revenues but may be more important determinants. There fore, some approach is needed to attach relative weight to the various factors. The concept of fuzzy sets assembled into a structured hierarchy facilitates analysis of the relative value of individual factors and their impact on each alternative under consideration. In this paper, a method is presented that employs fuzzy set analysis to evaluate postmining land use plans on the basis of these nonquantitative factors.

Jan 1, 1988

By Y. M. Jiang, R. L. Sanford, D. W. Park

Artificial intelligence has emerged over the past two decades as an important problem-solving tool. Techniques include expert systems, neural networks, free classification, fuzzy logic and genetic algorithm. These methods can be employed to solve rock mechanics and ground-control problems associated with the highly complex nature of rock masses and ground conditions. A current study focuses on the development of an artificial-intelligence system for real-time interpretation of data collected from longwall monitoring stations and on the development of an early warning system for the prediction of undesired conditions and the prevention of longwall-mine instability problems. The successful application of these artificial-intelligence techniques will contribute to a safer and healthier mining environment.

Jan 1, 1997

By B. M. Moudgill, T. V. Vasudevan

Marine sedimentary deposits account for 80% and igneous deposits 17% of the total world output of phosphate rock. The phosphate mineral is well crystallized and exhibits a greater floatability in the igneous deposits than the sedimentary ores. Both silicates and carbonates contribute the major gangue associated with the sedimentary ores. Although removal of silica from sedimentary phosphates by froth flotation has been in practice for several decades, with the depletion of high-grade reserves, new attempts are being made to improve the efficiency of current silica removal technology and to develop new processes for beneficiation of phosphate ores associated with the carbonate gangue. In this paper, recent developments in processing of sedimentary phosphate ores containing carbonate and silica gangue are discussed.

Jan 1, 1987

By Stanislaw Wasilewski, Zdzislaw Krzystanek

Ventilation process in deep mines features relatively low efficiency. Commonly used passive control by means of regulators and flow throttling leads to remarkable energy losses that could be lower if effective monitoring and remote control of main fan operating point were implemented. In the paper, some results of investigation carried out in Polish coal mines to evaluate real energy losses in ventilation process are described. Different methods for main fans performance monitoring and control are considered and compared especially those using fan drive speed control to minimize power consumption. On the other hand some criteria for power evaluation are analysed and algorithms for optimum location of controllers in ventilation network are considered. The results of investigation are being implemented in the first system for monitoring and control of main fan operating point in Miechowice colliery.

Jan 1, 1995

By M. Ericsson

The extractive industries consist of five major sectors: - Mining equipment and services - Dimensional stone - Industrial minerals - Aggregates - Metal mining These industries produce some finished goods but mostly semi-finished products as they feed into other industrial sectors: Basic metals, fabricated metals, construction, chemicals, dyes and pigments, inorganic chemicals, fertilizers, rubber and plastics and non-metallic mineral products. These are the major down-stream industries in this study. Taken together with the extractive industries they form the mineral resource based cluster. The mineral resource based cluster is a substantial part of the Finnish economy: It employs 211 000 persons, 39% of the number of employees in industry. The cluster?s exports account for 20% of industry exports. Value added is 34% of total value added in industry. Investments reach 35% of total industry investments.

Jan 1, 2003

By R. L. Grayson

Conventional mine safety wisdom states that "the most efficient mines are also the safest." Since the 1980s, small mines (and contractors) have been targeted as the most dangerous because of their fatality records. However, statistical analysis of West Virginia safety and production data from 1993 indicated that, when considering the correlation between accident severity and tons mined per employee-hour worked, the most efficient mines were, with the exception of very small mines, not the safest operations. This paper presents the results of an extended analysis of West Virginia mine safety using 1993 and 1996 data and concludes with the method used to suggest current priorities for focusing interventions.

Jan 1, 2000