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By J. A. Oraniscak

Longwall mining operations continue to increase extraction rates and the potential to generate higher amounts of airborne respirable dust (ARD). The National Institute for Occupational Safety and Health (NIOSH) has gathered data from underground longwall surveys and laboratory crushing tests to identify the important factors influencing the amount of ARD levels generated. Coal-seam characteristics, operational parameters (i.e.,cut sequence, mining height, etc.), extraction rates and dust-control parameters (i.e., airflow, water flow, etc.) were examined to determine their influence on ARD levels measured at longwalls during actual mining operations. ARD generated by a laboratory crusher while crushing bituminous coal samples collected from underground longwalls was also examined to determine if there were cor relations with coal-seam properties. Results from the longwall and laboratory data collected indicated that low-ash, high-volatile coals (low moist fuel ratio or MFR coals) generate higher amounts of ARD. It was found that face ventilation and water application to the coal product are essential elements to controlling longwall ARD levels.

Jan 1, 2000

By A. Burger Pintér

To be meaningful the sharing of ideas about the National Environmental Management Act (NEMA) and social issues within the context of Mining and Metallurgy (M&M) requires an honest scrutiny of the M&M/social environment relationship, both past and present. It is not a secret that this relationship has been and is fraught with difficulties. Thus from all perspectives (M&M, society and environmental and social consultants) such a dissection, that highlights the realities, both good and bad, is uncomfortable. For this section of the colloquium to have any value, the honest but difficult approach needs to be taken.

Jan 1, 2000

By Nora M. Hutt, Kevin A. Morin

Geochemical static tests are a basic component of geochemical assessments and predictions for acidic drainage, and include acid-base accounting and total-metal contents. A key database for such information is the International Static Database (ISD), which currently contains more than 45,000 static-test analyses from over 200 minesites. Such large databases are useful in identifying general trends and, just as important, the percentage of exceptions. General trends and significant exceptions can be seen in the ISD by comparing one parameter against another. This paper shows that bulk neutralization potential (bulk NP) obtained from acid titration is often a good indicator of neutralizing capacity above values of 10 t CaCO3/1000 t. Other types of calculated neutralizing capacity are then compared to bulk NP to determine if they, in fact, reliably represent actual neutralizing capacity and if they can substitute for the more time-consuming and expensive bulk NP. For example, bulk NP correlates better with Carbonate NP (from carbonate analyses) and Total-carbon NP (from total-carbon analyses) than with (Ca+Mg) CaNP (from solid-phase analyses of calcium and magnesium). This means that, in general, (Ca+Mg) CaNP is a less accurate substitute for bulk NP than the other types, and thus requires intensive site-specific justification if a substitution is attempted. This also means that measurement of the frequently less-expensive parameters of total carbon and carbonate can often substitute, within site-specific error bars, for the bulk-NP titration. However, the ISD also shows that non-carbonate minerals make the primary contribution to neutralization in up to 20% of samples, so Carbonate CaNP and Total-carbon CaNP do not always reveal the full neutralizing capacity of a sample.

Jan 1, 2000

By Peter Halbach

The two HYFIFLUX cruises of the German RV SONNE (SO 99/1995 and SO 134/1998) were organized in the framework of a co-operation between several German universities and two European marine research partners. It is a multidisciplinary program for the study of hydrothermalism with its associated geological, mineralogical, and biological processes in the North Fiji Basin (NFB) in the SW-Pacific. The main achievements of the HYFIFLUX cruises were detailed multibeam Hydrosweep mapping in order to identify the detailed tectonic setting, water sampling at hydrothermally active vents, mineral sampling at inactive sites with sulfide, sulfate, and silica mineralizations, and sampling of basaltic rocks, (Halbach et al. 1999). Oceanic accretion in the NFB is characterized by a double spreading system (Auzende et al. 1994),with one spreading axis located in the median part of the basin (Central Fiji Ridge, CFR) and the second one located immediately west of the Fiji platform (West Fiji Ridge). Most of our investigations were done in the northern part of the N 15° segment of the CFR, which corresponds to area A of our program, area D is located farther south in the NFB and corresponds to the N-S segment of the CFR (Fig. 1). During previous works under the French-Japanese STARMER project, the active ?White Lady? mound and the extinct Père Lachaiseí site were sampled; these samples were studied by Bendel et al. 1993. Here an inactive hydrothermal field was studied, where there were many sediment-covered chimneys in various stages of disintegration, (Bendel et al. 1993). However, the area immediately southwest of the nodal circular basin, which is the triple point junction of the medium-spreading Central Fiji Ridge (about 6 cm/yr spreading rate

Jan 1, 2000

By V. D. Tathavadkar

Chromite ore is of immense importance for the extraction of metallic chromium and chromium chemicals. The mineralogy and crystal structure of chromite phase are therefore important part of our investigation on the extraction chemistry of chromium species. In this investigation, we have studied the effect of the processing parameters, i.e., the temperature and the oxygen potential on the microstructure and composition of mineral phases formed in the Cr2O3 ?Al2O3 -FexOy -MgO system. In particular the importance of the spinodal decomposition reaction is emphasized in the extraction of chromium as sodium chromite and sodium chromate. Experiments were carried out in order to study the differences in the crystallography of different chromite minerals. Phase equilibria in natural chromite minerals were investigated by calcining chromite mineral in air, argon, and 5% hydrogen + argon atmospheres over a temperature range from 200 to 1200 °C. The effect of the oxygen partial pressure and temperature on the phase constituents of the calcined product has been discussed. The microstructural changes were examined using scanning electron microscope (SEM) and the changes in elemental composition in different phases were analysed by electron probe micro analyser (EPMA). The results obtained from EPMA studies were used to calculate lattice parameter of the spinel lattice, and these values were compared with the values obtained from X-Ray powder diffraction data. On the basis of the experimental data, the mechanism of the spinodal decomposition of complex spinel phases is described under the influence of oxygen partial pressure and temperature.

Jan 1, 2000

By Tadashi Aiura, Yasuhiro Miura

"A small amount(0.2mass%) of Scandium(Sc) was added to the 7.NOl and 5083 Al alloys as a refiner and stabilizer of microstructure, and the resulting microstructures were discussed in comparison with the effects of the conventional additives. The followings are summarized: 1) in the as-solidified structure, a ·decreased tendency of constitutional supercooling and increased solubility of Mg were recognized for the Sc-added 5083 alloy. Sc is a -better microstructure refiner for the 7N01 alloy than Zr, in a sense that it does not suppress the favorable effect of· coexisting Ti. 2) Sc effectively suppresses recrystallization both in the 5083 and 7N01 alloys. 3) The rod like primary Al3Sc crystals formed during solidification, as well as the fine dispersion of Al3Sc precipitates formed by subsequent heat treatment, can act as a strong recrystallization suppresser. IntroductionThe 7N01 and 5083 alloys are the most popular industrial Al alloys and they are widely' used for various structures because of their superior properties. Fine macro and micro structures of the materials are required for obtaining acceptable sec resistance,consistent appearance of anodized surface and good weldability, as well as good mechanical properties. In order to produce fine grain structures, transition metals, such as Cr, Zr, and Mn, have been conventionally added.It has been reported that Sc is an efficient refiner [l, 2] and can be an alternative for the conventional and also suppresses recrystallization in Al alloys [3,4]. Scandium is the lightest transition element and forms an equilibrium intermetallic phase. The equilibrium phase, Ll2-Al3Sc, is coherent with the matrix, and of _spherical shape. A fine dispersion of the spherical precipitates is obtained by quenching and aging after solutionizing annealing. The authors have already reported a part of the experimental results on the effect of Sc on the as homogenized microstructure of the 5083 alloy [5]. In the present study, the effects of Sc on the macro and micro structures of the industrial high strength Al alloys(7N01 and 5083) for extrusion are investigated, and the superior role of Sc as a grain refiner is shown"

Jan 1, 2000

By A. E. Dabbagh

Saudi Arabia’s mineral potential offers development target that compliment the national effort to diversify the income of this oil and gas economic based nation. Ma’aden, a joint stock company with paid-up capital of US$1 billion, has from its inception in 1997, actively developed in-house engineering and management skills to transform the Arabian shield’s mineral potential into such real projects. Gold mine operating facilities of 100,000 oz/yr underground and 50,000 oz/yr open pit are de-scribed, as well as 3 targets, two of which are underdevelopment; Al Hajar (3,000 tpd at 2.5 gpt Au)and Al Amar (5,000 tpd at 20 gpt Au). Emphasis is also on exploitation of phosphate rock and down-stream fertilizer products, based on the Kingdom’s107,000 sq. km. northern basin geological reserve. Al Jalamid, the prime target, represents 216 million tonnes of these P2O5 reserves. Saudis and expatriates, together, lead international engineering companies and contractors operating and developing these facilities.

Jan 1, 2000

By J. J. Gusek

Passive treatment of mine drainage using constructed wetlands has been employed on coal and metal mine sites since about 1985. The technology has advanced significantly since then; there are currently over 600 of these systems treating coal mine drainage in the Eastern U.S. at flow rates of hundreds of liters per minute. Passive treatment performance at three metal mines discussed in this paper has been positive for a wide variety of flows, water chemistry, and climates. The sites include a high-altitude underground copper mine, acidic seepage from a gold heap leach pad, and pumped effluent from an active underground lead mine in Missouri.

Jan 1, 2000

By C. Restarick, R. G. Robins, R. M. Taylor, I. Ennis

Lime addition to acid mine drainage waters (AMD), possibly accompanied by aeration, has been the basis for their remediation by precipitation of predominantly metal hydroxides. An efficient novel alternative technique causes precipitation of double M(II)-M(III) hydroxy sulfates which readily precipitate and are easily dewatered. When the Fe(II)/Fe(III) + Al(III) ratio of the AMD is appropriate, the Green Precipitate (GP) Process provides a more effective alternative to normal liming/aeration. The process can be adapted to give a continuous in-line treatment by the choice of suitable computer-controlled reactors designed to improve the liming efficiency, reduce scaling and control the rate of treatment. The processes are described in terms of the chemistry involved.

Jan 1, 2000

By K. Iwami, K. Abe

"Onahama Smelter and Refinery has been operated-since 1965 arid currently produces 243,000 metric tons per year of cathode copper. The Onahama tankhouse consists of conventional-type No.1 and 2 tankhouses with the capacity of 123,000 metric tons per year and No.3 tankhouse with 120,000 metric tons per year, adopting jumbo tank system, using hazelett anode respectively.In October, 1996, for the purpose of improving the - anode verticality, new anode copper body press machine has been installed in No.1, 2 tankhouses; by increasing Walker type anode copper weight by 35kg to 365kg. Consequently, it is possible to raise current density from 191 to 222 A/m2 and the No.1 and 2 tankhouses capacity was increased by 15,000 metric tons per year to 138,000 metric tons per year.At present, the refining capacity is 258,000 metric tons per year in total including No.3 tankhouse.This figure is the largest one in Japan.IntroductionSince the Onaham tankhouse was put into operation in 1965, the cathode copper production has increase with much labor cost saving.The following two cases to increase Walker type anode copper weight by 35kg to 365kg were studied.a) To increase the cathode copper production by raising current density.b) To save the labor cost by prolonging the anode cycle in order to decrease the exchanging time of electrodes.So the electrolytic tests were carried out to confirm· the effect of current efficiency, cathode copper quality and working conditions for space adjustment.As a result, we concluded that it was indispensable to introduce the anode body press machine to keep usual current efficiency and cathode copper quality with same workers, and to be possible to increase cathode copper production.In addition, the high-speed press machine was needed to maintain same working time and which specifications were decided through various investigations. In October 1996, the new anode body press machine made by Kawazoe Machine Works, Ltd. has been installed in No.1 tankhouse."

Jan 1, 2000

By Charles Deacon

The mining industry is constantly taking greater cognisance of their operating costs as a strategy to counter the effects of falling commodity prices. As a result, optimal operating efficiency is more important than ever. One such operation is that of blasting. Considering the relative increasing costs of explosives and accessories it is desirable to optimise the number of blast-holes fired by maximising their individual output. This achievement may now only be possible following the advent of higher technologies in the form of modified explosives and electronic detonators. This paper reviews and introduces some techniques of blast monitoring, types of operations where each is most suited, resulting modifications to blast designs, and identifies some pitfalls to watch out for when analysing the results.

Jan 1, 2000

By G. J. Koons, J. L. Uhrie

Field density studies carried out at the Phelps Dodge Chino Mine have found that truck-induced compaction is limited to the upper 2.4 meters (8 feet) of an individual lift. Hydraulic properties of material compacted to field densities were determined in a laboratory setting and saturated flow models were then run, simulating the effect of compacted zones within a stockpile. Modeling shows that compaction can effectively prevent solution flow through large portions of the stockpile, implying that great care must be taken to ensure that ripping is carried out to a full depth of at least 2.4 meters (8 feet) across the entire stockpile to achieve uniform solution flow. Uniform solution flow will result in maximum leach recovery.

Jan 1, 2000

By W. J. Nokleberg, B. A. Bouley, T. K. Bundtzen

Central Alaska contains a wide variety of pre-, syn-, and post -accretionary mineral deposits that are related to the growth and evolution of the north-west North American continental margin. Withinpre-accretionary terranes, the Devonian-Carboniferous, carbonate platform-hosted MVT zinc-lead deposits of the Kandik and Reef Ridge districts in central Alaska, and the Devonian-Mississippian volcanogenic massive sulfide (VMS) polymetallic deposits of the Bonnifield, and Delta mineral belts of eastern Interior Alaska have received the most exploration interest to date. Syn-accretionary rift related, mafic and ultramafic sill swarms and zoned plutons of the Kluane-Nikolai igneous belt are currently being explored for Ni-Cu-Co-PGE deposits. Syn-accretionary granitoid complexes in the PurcellMountains, Illinois Creek, and Sitylemenkat areas have been explored for uranium-REE-gold, and tin-silver mineralization respectivelyPost-accretionary granitoid intrusions and associated volcanic fields that range in age from mid-Cretaceous to early Tertiary contain significant gold-silver-polymetallic resources in the East Central Alaska, Hogatza, and Kuskokwim Mineral belts. Collectively the three main post-accretionary plutonic/volcanic belts of central Alaska are part of the Tintina Gold Province, where exploration since 1990has identified about 848 tonnes gold.

Jan 1, 2000

By J. Maiti, A. Bhattacherjee

A literature review on quantitative analysis of mine safely studies revealed that numerous investigators explored a wide- range of techniques, including the investigation of bivariate and multivariate statistical models. Although these researchers addressed various issues of accident causation and prevention, they, in general, did not investigate through the use of quantitative models the multivariate relationships of several factors affecting mine safety in a causal framework. In this paper, systems dynamics and structural equation modeling are presented to simultaneously represent and study the effect of policy variables related to accident prevention along with the factors causing accidents and injuries. The application of these models to a group of mines revealed that current training practices at these mines do not appear to alleviate accident occurrences. It is inferred that the use of these quantitative techniques can provide a new direction of research in mine-safety studies.

Jan 1, 2000

"With the globalization of the mining industry, many companies are now seeking to invest in underground diamond mines, with the purchase of small diamond pipes being seen as particularly attractive. However, recent experiences in South Africa have shown that many projects fail due to a lack of awareness of the hazards associated with diamond mining. In this paper three significant hazards are dealt with — mud rushes, block crushing, and implementation of an inappropriate mining method. Measures that assist in the prevention of these three hazards are given.IntroductionFor over a hundred years, South Africa has been seen as the centre of the diamond mining industry, possibly having the largest number of operational underground diamond mines in the world. Despite the fact that this industry has been dominated by large mines of De Beers Consolidated Mines Limited, many small underground mines have operated profitably for a number of years, exploiting diamondiferous fissures and pipes. In the last decade there has been renewed interest in these small operations from international companies. However, many of these projects have not realized their full potential owing to a lack of appreciation of the hazards inherent in the operation of a diamond mine.Hazards Associated with Diamond MiningIn the development of a diamond mine, the mining company must be aware of the hazards associated with diamond mining. There are three main hazards: (1) mud rushes; (2) block crushing; and (3) selection of an inappropriate mining method (not a natural hazard, but a planning induced hazard). Each of these hazards will be dealt with in turn in the following sections."

Jan 1, 2000

By M. G. Lipsett

"Mining properties are becoming increasingly remote, a challenging situation for operating and maintaining equipment. Logistics of transporting workers and materials can be alleviated by having timely, accurate information of equipment location and operating condition, and by automating some activities. This paper discusses an infrastructure for remote operations, with strategies for communicating different types of data, and a design method so that systems can interact with either an operator or another system. A remotely operated excavator prototype is described, with on-board performance and diagnostic monitoring systems now used on production equipment. IntroductionSyncrude Canada Ltd. operates an openpit oil sands mine near Fort McMurray, Alberta. For twenty years, draglines and bucketwheel reclaimers have fed conveyors that transport dry oil sand to an extraction and upgrading plant. In converting to a truck and shovel operation, Syncrude has developed slurry pipelines and bitumen froth pumping to allow more remote leases to be mined more than 30 km from the base plant.There are organizational and resourcing challenges in operating and maintaining equipment in three nearby, but separate, mines. The logistics of transporting workers and materials to production and support equipment become more difficult, and operations and maintenance personnel and facilities become more distributed. Supervising mine operations will rely even more on having timely, accurate information about equipment location and operational status.Syncrude is typical of an open-pit operation. Voice communications are the preferred way to exchange information for making immediate decisions about operations and maintenance. A large number of narrowband FM broadcast radio channels keep teams of miners working together. Haul truck drivers, shovel operators, and dispatchers talk on one channel while maintainers coordinate activities with the control tower on another. Cellular phones have become popular for supervisors who have to talk with planners and engineers in offices without radios."

Jan 1, 2000

By Shigehito Deki

"A new wet process has been developed for the synthesis of various kinds of oxide thin films on various kinds of substrates, even which have complex surface morphology, from aqueous solution. The process was named as the LPD, Liquid Phase Deposition, method, which has some advantages over the conventional dry processes. This process can be applied to an on-site synthesis of advanced materials in the thin film technology. In this paper, some current topics on the synthesis of the composite thin oxide films by the LPD method, are presented.IntroductionGenerally, metal oxide thin films have been made by different preparative processes such as r.f. sputtering, chemical vapor depositon, CVD, laser ablation and sol-gel method, etc [1-3]. Each method has it own advantages and disadvantage. In some cases, the process is not suitable for the preparation of thin film on substrate with large surface area or complex surface morphology, and makes the deposition apparatus complicated and expenisve. By using Liquid Phase Deposition, LPD, method which overcomes some of those problems, metal oxide or hydroxide thin film can be formed on the substrate with large surface area and complex surface morphology, which are immersed into the aqueous solution only at ambient temperature and under atmosphere without any special equipments and high energy. And also, multicomponent oxide thin films can be formed readily by mixing solutions containing the objective metal ions, because it is performed in the aqueous solution which is typically a homogeneous mixing system. This process utilizes ligand-exchange, hydrolysis, equlibrium reaction of metal-fluoro complex species, MF x (x-2n>-, and F consumptive reaction. In the aqueous solution, MFx<x-2n>-is hydrolyzed with water to release F ions by a ligand exchange equilibrium reaction as following;"

Jan 1, 2000

By Martin J. Kenwright

Within the famous Harrods department store, a new lift shaft has been constructed, servicing a depth of 22m below ground level as well as the existing 6 storeys of the store. The shaft will connect with a new goods tunnel which is to be excavated beneath the shop, as well as new floor space above ground level which has resulted from the infilling of a previously existing lightwell within the store. The construction of the deep shaft while maintaining uninterrupted use of the store by the Client led to a number of innovative solutions being undertaken. Empirical assessments were made of settlements anticipated from the construction process, which took place within a congested environment of existing foundations. Various elements were designed and installed to mitigate the effects of the inevitable ground movement on the surrounding overlying structure, which supported sensitive high quality finishes and mechanical and electrical installations. The reinforced concrete lining of the shaft was contained within a cofferdam of minipiles. The minipile placement accuracy (1 in 150) was vital as it could not interfere with the subsequent tunnelling works. As the scheme progressed this became even more critical since the minipiles were needed as support for parts of the permanent works. This paper describes:- the high quality placement and control of the minipiled cofferdam, the methods employed in assessing ground movements and the techniques used to mitigate against the effects of these movements.

Jan 1, 2000

By H. Sis, S. Chander

The pressure filtration behaviors of dispersed and flocculated alumnae slurries at high percent solids were investigated with the objective of determining the effect of surfactant type and concentration on slurry properties. A high-purity alumina powder was used as a model solid. Dispersion of the alumina was controlled by pH and by surfactants that are known to act as electric and steric stabilizers. The effects of both ionic and nonionic sutfactants were investigated. Surface charge measurements of the slurries were carried out by an electrokinetic sonic amplitude (ESA) method to better understand the mechanisms. The effect of surfactant type and concentration on the kinetics of pressure filtration and cake properties are discussed.

Jan 1, 2000

By A. E. Lewis

The emphasis of this paper is on the characterization and testing of the slag produced by a secondary lead refinery. This work forms part of a broader investigation aimed at reducing loss of valuable product from the process as well as minimizing the environmental impact of the process wastes. It was this work that led to a critical examination of the standard waste classification tests. Characterization of the slag was carried out using a number of complementary techniques. In the broader context, the slag characterization aided in identifying process deficiencies and thus was a critical tool in suggesting potential for process optimization. For this study, the slag characterization provided a relatively comprehensive picture of the composition and properties of the slag, which facilitated understanding the behaviour of the slag under batch test conditions. On the basis of quantity of hazardous components alone, the slag is hazardous according to South African Acceptable Risk Limits (ARL). However, when both the quantity and the leach potential of the hazardous components is taken into account, standard waste tests carried out by three independent agencies indicate that the slag should not be classified as hazardous according to local regulations. Also, according to United States Environmental Protection Agency (US EPA) limits, which are independent of the quantity of the waste, the slag would not be classified as hazardous. The standard waste tests used by the independent agencies was the Toxicity Characteristic Leach Procedure (TCLP), a test which was developed by the US EPA to classify hazardous wastes. One of the requirements of this batch test is that it should be quick, simple to carry out and that the results should be reproducible. Previously, the applicability of the TCLP test to mineral processing and metallurgical wastes has been challenged on a number of points. Additional testing of the slag was carried out using both the TCLP and the Synthetic Precipitation Leach Procedure (SPLP) recommended by the American National Mining Association as being more appropriate for mineral processing wastes. The particular physical and chemical characteristics of the secondary lead slag highlighted additional limitations of both the TCLP and SPLP tests as standard laboratory batch procedures. Keywords: environmental protection, secondary lead processing, slag, leach testing, TCLP, SPLP, ARL, hazardous waste, batch tests

Jan 1, 2000