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By M. Scherbakov, W. Shi

Abrasion is an important mode of performance for any element of an engineered product that involves material contact for example, a conveyor belt cover. Abrasion resistance is considered to be one of the leading factors in belt cover design and improvement. Various types of abrasion testing are reviewed by and compared to actual belt applications. A new quantitative screening torsional abrasion test is developed by Goodyear to mimic a dynamic contact between belt cover and differently shaped stones of various weights dropped onto belt at any angle, velocity and height.

Jan 1, 2004

By Firoze E. Katrak, John R. H. Black, Paul R. Ammann, Michael J. Loreth, Servi. Italo S.

Germanium is produced primarily as a by product from zinc concentrates. The important sources of gallium are alumina ores (bauxites) and zinc concentrates and residues from zinc processing. In addition, gallium as well as germanium may soon be recovered from a depleted copper mine near St. George, Utah. The major uses for germanium are in semiconductors, lenses in infrared optical systems, catalysts, and gamma radiation detectors. The major markets for gallium are in light-emitting diodes, solar cells, laser diodes, integrated circuits, microwave devices, and magnetic bubble memories. CRA projects a healthy growth in the demand for both metals. However, the role of scrap metal will continue to be important over the next decade, thus decreasing the overall demand for primary gallium and primary germanium. This paper summarizes the key elements and the economics of the markets for germanium and gallium. Much of the information, such as plant-by-plant costs of production and estimates of consumption by end use for various countries is from proprietary databases of Charles River Associates.

Jan 1, 1986

By Rob McIvor, Joe Keating, Gary Simmons

As more complex ores are processed, finer grinding becomes more necessary. A cross section of several industries will be presented with discussions not only of find grinding issues but also the classification of fine particles. JOHN MANSANTI: Our next topic will be fine grinding. Again, the intent is to present a topic that is generic enough to apply to multiple industries. Our first speaker is Gary Simmons. Gary is filling in for Phil Walker from Twin Creeks. Phil was not able to join us this week, because of some issues they're having with the autoclave. Gary, being involved in the development phase, is very familiar with the topic. Gary spent about three years with American Cyanamid and another four years with Noranda. He also spent some time with Meridian Gold, then became the director of metallurgy with Santa Fe Pacific Gold. He spent seven years there and is presently the director of process technology with Newmont Gold.

Jan 1, 1998

By R. V. Ramani, R. Bhaskar

An airborne dust cloud is an ensemble of particles of varied size, density, shape and states of aggregation. An understanding and quantifying of the dispersion and deposition of the dust generated in mines is essential to the development of measures for reducing worker exposure to dust. In coal mining, the major portion of the dust is generated during the cutting of coal using a shearer or a continuous miner. The major phenomenon affecting ambient concentration is the deposition of dust. Particle deposition may take place due to the effect of gravitational, inertial, electrostatic, and thermal forces, and mechanisms such as Brownian and eddy diffusion and inertial impaction. The three major mechanisms of deposition in turbulent flow in mines are diffusion (Brownian and eddy), sedimentation and inertial impaction. The mechanisms determining particle deposition are size dependent. From a review of the literature, there appears to be a knowledge gap in the understanding of the deposition phenomena in mine airways. In order to obtain a better understanding of the deposition of dust for various particle sizes, and to develop a set of data for evaluating predictive mathematical models for dust-flow in mines, a series of dust flow experiments was performed under controlled conditions in mine airways. It appears that the deposition data generally follow the theoretical behavior of dust based on the combined effect of diffusional and gravitational deposition. In this paper, the findings of the study on the deposition of dust in mine airways and its dependence on size, velocity and concentration are discussed. A set of deposition equations that could be used to determine the approximate deposition at various points in a mine airway are presented.

Jan 1, 1992

By G. F. Friel, J. C. Edwards, C. C. Hwang

In the implementation of a mine fire alarm and location strategy, the Interpretation of the fire signature Is Important. Smoke and CO are the two dominant fire signatures, and many mine fire detection systems utilize sensors which respond to smoke or CO through a diffusion mode or a mechanical pump mode. The fire signature may be modified during its transport along airways and at crosscuts. The modification occurs through dilution of the contaminants. In this Investigation, computer codes were employed to compute the effects of contaminant dilution on the contaminant signature when a straight flow passage has one dead-end crosscut. The model predicted the airflow within always and the entrainment of contaminants into the crosscut from the airway. One application of the model is to determine the most suitable location for CO detectors for early mine fire detection.

Jan 1, 1995

By F. Woodcock, A. R. Laplante

A test to characterize the amount of gravity-recoverable gold (GRG) in an ore is described. Typical GRG results are given and possible uses are discussed. The overall database, which includes 68complete tests, is presented. The ore samples treated had an average GRG content of 63% of the total gold in the sample, with a standard deviation of 20% and a range of 3% to 97%. Both the F8(, of gold and the GRG content at a grind of 100% finer than 850 pm correlate well with the overall GRG content (at 80%finer than 75 pm). The primary use of the test is to determine whether gravity recovery should be used and how. Results can also be used to predict gravity recovery, as many of the ores tested are from plants employing gravity recovery. Gravity-circuit simulation can be used to refine recovery estimates or for optimization studies.

Jan 1, 2000

By Nicolae Dobritoiu

From experience and scientific references it is known that during information processing, the following error types are transmitted: technical, analogy errors and method errors. For decreasing the value of these errors, especially of the method ones, old algorithms should be perfected and new ones should be developed for processing, interpreting and achieving the graphical layout by means of automatic data processing. In this respect, we propose a new deposit model based on numeric mathematical modelling which requires the use of automatic data processing. The utilization of the numeric model of the proposed deposit, allows the obtaining of the following advantages: • the model is used for any deposit form; • it is used for the calculation of deposit resources (volume, weight, and content); • it is used in design due to the facility of obtaining sections through the deposits area; • it eliminates at "0" the errors of graphical data transcription; • the use of the model imposes a uniform geological research; • the algorithm is transposed in a package of programs.

Jan 1, 2002

Over the last two decades, the mining industry has spent considerable time and effort in installing sophisticated control systems (including expert systems) to regulate and improve the performance of AG/SAG mills. Yet the need for these systems is often overlooked – unmeasured and uncontrolled variation in the feed material. With AG/SAG mill technology replacing rod and ball mills as primary grinding equipment, the need for careful and thoughtful feed preparation has gone. To maximise mill throughput, operations need to better understand the ore characteristics affecting AG/SAG mill performance. Industrial operating data will be used to illustrate these ideas and concepts. It is often quite surprising which ore characteristics that are the most influential on mill throughput.

Jan 1, 2004

By Slavko Ostojic, V. G. Hill

This paper reviews various bauxite classification schemes with respect to the differences in texture, composition and geological associations of the deposits. It demonstrates that a techno-economic classification, based on: a) associated rock type - lateritic versus karstic, b) content of aluminum ore minerals - gibbsite, boehmite and diaspore, and c) gangue minerals (iron oxides etc.) has a geological basis with natural cut-off points for the bauxite types identified. Thus, this scheme is seen as applicable to bauxite resources. It also provides a basis for their rational exploitation taking into consideration the long-term interests of both the bauxite producing and consuming countries. Against this background, the industrial mineral or non-metallurgical grades of bauxite are seen as localised and relatively rare occurrences. Their consumption should, therefore, be aimed toward the specific (hence more remunerative) products as indicated by the bauxite characteristics.

Jan 1, 1984

By K. Soucek

Extraction of hard coal reserves, but also of mineral resources in general in the underground coal mines includes in itself many anthropogenic interventions in the earth crust. These interventions are closely associated with the solution of stability problems in the mine and with occupational safety. One of potential applications of such geo-technical interventions in rock mass is the chemical grouting technology. The chemical grouts are very suitable to affect the physical and chemical properties of rock mass. With the present development of chemical grouts, primarily based on polymers, there come into existence new composite materials during the grouting process (the so called geo-composites), which properties significantly differ from the original rock. An important factor, which affects a choice of chemical grouts and at the same time the effectiveness of grouting technology is the resulting properties of geo-composites. The properties of a coal geo-composite differ from the ones of the unmodified coal seam. On the basis of the laboratory geo-mechanical tests, the differences of properties of both material types were found. While the pure coal samples were destroyed very brittle and explosive, the geo-composite samples were making higher level of tenacity and load bearing ability after overstep of material strength. The presented paper discusses the different behaviour of these original and modified coal samples. The X-ray CT scans were used for observation and demonstration of failure evolution in these samples of pure coal and coal geo-composites after compressive loading.

Jan 1, 2006

By C. N. Bensley, S. K. Nicol

The major developments in fine coal processing in Australia are reviewed. Emphasis is placed on the approaches taken by various Australian coal producers to improve the recovery of the coarse size fractions (minus 0.5 plus 0.25mm) and upgrade the selectivity of flotation at ultrafine sizes (minus 0.075mm). The effects on fine coal preparation of flotation circuit changes, the influence of physical and chemical variables on coarse coal flotation and the impact of spiral concentrators and column flotation, are discussed. Reference is also made to the development of oil agglomeration technology for the treatment of fine coal refuse and some of the factors which have led to its current demise.

Jan 1, 1988

By Kot F. v. Unrug

In spite of extensive research and accumulated experience from mining operations, appropriate coal strength values for pillar design remain debatable. Coal strengths determined in the laboratory on standardized samples vary widely among various coal seams with poor repeatability. Penetrometric in situ strength testing obtains multiple measurements at multiple horizons within the coal seam to provide a strength profile. Alliance Coal has used that method in many of its mines for pillar design. Pillars in these mines perform well. This paper presents a series of case studies and discussion of issues related to coal pillar design. The analysis demonstrates that the proposed default in situ strength of 900 psi is appropriate when no other data exist. However, in the case of appropriate strength measurements combined with analysis of pillar structural composition, differing values can be used successfully. In areas where the penetrometric derived in situ strength is greater than the standard 900 psi in situ strength, reserve recovery has been optimized as required by law without compromising safety.

Jan 1, 2009

By André Vien, Robert Edwards, Rob Perry

A metallurgical control application can only succeed if the system's lowest common denominator, its instrumentation and regulatory control is implemented and maintained correctly. This paper describes the basics of regulatory control implementation including some practical guidelines for instrumentation installation, operator interface design, loop tuning, and continuous loop performance analysis. Tuning and analysis techniques are illustrated by step-by-step industrial examples. A small investment in basic control pays dividends in better overall plant performance and provides a solid foundation for advanced control efforts such as expert systems.

Jan 1, 2000

By B. (Manas) Das

Rock characterization for geotechnical purposes using the microhardness technique is discussed in this paper. The concept of rock characterization and its steps are logically developed. The geotechnical properties should be functionally tethered to the technological problems for characterization. The overriding geotechnical concern is rock mass stability. The important factors in this respect are rock properties, structural discontinuities, ground water, field stress, temperature and technological factors. The rock properties are the primary factors and the other factors generally affect rock properties. Of the rock properties the strength and elastic properties can form a basis for rock characterization. The microhardness technique can provide these two properties. Study on coal shows that the microhardness impressions can be used for this purpose. On the basis of this study coals of all ranks can be divided into distinct geotechnical groups. The details of these are discussed in this paper.

Jan 1, 1986

By Michael M. Maier

The manuscript of this paper was not available for publication when the Proceedings went to press. Should the author elect, he may distribute copies at the time of the Symposium.

Jan 1, 1986

By Stuart Brashear, J. W. Reil

The manuscript of this paper was not available for publication when the Proceedings went to press. Should the authors elect, they may distribute copies at the time of the Symposium.

Jan 1, 1986

By Qing-Wang Hao

In this paper, the authors attempt to develop engineering based approaches for estimating safety factors against pillar and floor failures and predicting likelihood of subsidence events over abandoned coal mines in Illinois. There are two critical problems involved in the analysis: determination of geotechnical properties, and consideration of time effect. The authors attempt to solve the problems by generating hypotheses, which are used to modify existing engineering models for estimating pillar and floor safety factors. The modified models are validated using data from two well established databases of subsidence events over active and abandoned mines in Illinois. The data analysis suggests that most of the trough type subsidence events in Illinois were caused by floor failures rather than pillar failures. The subsidence incubation period seems to be directly related to initial floor safety factors at the time of mining. This correlation can be used to predict the likelihood of subsidence and to assess subsidence risks within both spatial and temporal contexts where detailed mine maps are available.

Jan 1, 1986

By C. I. Basilio

The adsorption of O-isopropyl-N-ethylthionocarbamate (IPETC) and O-isobutyl-N-ethoxycarbonylthionocarbamate (IBECTC) on chalcocite, chalcopyrite and pyrite has been studied using UV and in-situ FTIR~ATR spectroscopy. Thionocarbamates were found -to adsorb strongly on chalcocite at pH 4-10, but consider-ably less on chalcopyrite and pyrite. The FTIR spectra show that the surface species of thiono-carbamates are bonded to metal atoms on the mineral surfaces. However, at high concentrations, IBECTC also forms physically-adsorbed species. Adsorption of these thionocarbamates cannot remove or prevent the formation of sulfoxy oxidation products on pyrite, unlike the case with the xanthate-pyrite system. This finding may account for the observed flotation selectivity of these reagents against pyrite. The spectroscopic information is compared with flotation test results.

Jan 1, 1988

By Wan-Kyu Choi, Arpad E. Torma

The electrochemical reactions involved in a zinc sulfide flotation concentrate leaching with sulfuric acid in presence and absence of Thiobacillus ferrooxidans, as well as with ferric chloride - hydrochloric acid containing media, have been investigated. The cyclic voltammetric measurements revealed that many intermediate electrochemical reactions are involved in the zinc sulfide leaching. Using chronoamperometric and chronopotentiometric techniques, it was found that the leaching process is controlled by solid - state diffusion. The activation energy of solid - state diffusion process was determined by the Price's approach to be 21.3 kJ. The leaching mechanism is discussed in terms of solid - state properties (energy bondings) of the high energy gap solid zinc sulfide semiconductor and energy density states of redox systems of acidic leach media. A generalized model for the mechanism of zinc sulfide oxidation is present.

Jan 1, 1990

By W. M. Shaver, R. Letourneau, W. R. Dengler

Dynatec Mining Limited contracted to sink a 1500 metre (4960 ft.) concrete lined shaft for Falconbridge Nickel Mines in Sudbury, Ontario, Canada. The shaft is 6.3 metres (20.5 ft) in diameter inside the concrete lining and is equipped with steel furnishings. Dynatec used the owner supplied 4.6 metre (15 ft.) diameter double-drum hoist to sink the shaft with 12.5 tonne buckets for muck removal and 4 cubic metre concrete buckets for concrete placement. One of the unique features of the shaft sinking operation is the use of a four-boom electric hydraulic drill jumbo permanently mounted in the shaft sinking stage. This paper will describe the performance obtained with the electric hydraulic drilling equipment and the high capacity muck removal and concreting equipment.

Jan 1, 1991