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By C. A. Pickles, J. M. Toguri

The refining of two molten Ag-Cu alloys, containing 7.5 and 11.2 mass% Cu, with a borosilicate slag was investigated using both air and pure O2 to determine the effects of the following variables: flow rate of oxidising gas; injection time; mass of sodium borosilicate flux; and injection of the oxidising gas into either the slag or the metal. The results demonstrate that more than 90% of the Cu can be removed with Ag losses of less than 5% and that refined metal with a Cu content of less than 0.5 mass% can be produced. Ag losses to the slag increased with the amount of Cu removed, and a mechanism is proposed to account for this

Dec 1, 1995

Collecting the clay fraction of active stream sediment from a flowing stream for geochemical analysis i a difficult process. One either takes a sample of dry fine-grained sediment from the stream bank (dry weather and dry sample are uncommon in parts of New Zealand and Tasmania), or dredges up a sample of sand and mud out of the stream.The latter method produces a soggy ample bag full of mud and sand, with varying amounts of gravel, depending on the size of the stream. The water can be filtered from such a sample by means of a Buchner filter funnel, but is difficult to obtain a vacuum in the bush. This problem can be solved by using a small hand- queeze bellows such as used in priming petrol pumps on outboard petrol motors. The common laboratory hand bellows is not powerful enough.A 70 mm diameter two-piece polythene Buchner filter funnel (Fig. 1) can be used. A length of rubber tubing is fitted around the inlet valve of the hand bellows and this valve is then jammed into the pipe at the bottom of the filter funnel (the polythene pipe may be trimmed with a knife to fit over the inlet valve of the bellows). The vacuum is generated and maintained by squeezing the hand bellows.The technique of collecting a sample of the clay fraction is to dredge a sample of the fine-grained active stream sediment out of the stream with a container, such as a plastic mug. The sample is agitated to get the clay fraction into suspension and the muddy suspension is then decanted into the Buchner funnel. The desired clay fraction is obtained as a thin film on the filter paper.If the "fines" are also required, a filter of nylon bolting cloth (stretched across the mouth of a short length of 80 mm diameter polythene pipe and attached by rubber bands or a concentric polythene pipe) can be placed over the mouth of the Buchner funnel and the whole sample of stream sediment...

Jan 1, 1969

By A. B. Hazar-Yoruç

Ferrochromium produced by smelting chromite ores is an important alloying component in the steel industry. Ore, coke and fluxes are mixed and reacted in an arc furnace for a smelting process of ferrochromium. In ad-dition to this process, pre-reduction of chromite ore with carbon is an important industrial process. In all these processes, the mechanism and kinetics of reduction of chromite with carbon play an important role. In this study, the reduction of Turkish chromite ore with carbon was investigated. Chromite and carbon were ground to three different particle size groups. Chromite was mixed with carbon in stoichiometric and excess ratios. The samples were reduced under argon atmosphere at temperatures between 1,200° and 1,350°C. The formed phases and alloy compositions of reduced chromite samples were analyzed by optical microscopy, scanning electron microscope (SEM) with EDAX and X-ray diffraction analysis (XRD). Experimental results showed that the degree of reduction and the reduction rate increased with increasing temperature and decreasing particle size. The highest degree of reduction, 61.4%, was obtained at 1,350°C. The reduction took place in three stages: Stage 1: transformation of Fe3+ to Fe2+ and formation of metallic nuclei, Stage 2: formation of metallic crust around the particles and Stage 3: growth of the metallic crust and coalescence of the metallic phase.

Jan 1, 2007

By Randall M. Wheeler

"Fourier analysis is a very powerful frequency analysis tool. However, it is frequently misunderstood and sometimes used inappropriately. Part of this workshop will involve the basics of Fourier series, the Fourier integral and finally the Fourier transform. Included will be a brief discussion of analysiswindows, including the box and Hamring windows."

Jan 1, 1998

By Wu Aixiang, Zhou Qian, Zhou Zaibo, Liu Juanhong, Wang Hongjiang

To improve the pumping capacity and engineering efficiency of fresh thickened tailings slurry, a high charge density superplasticizer was developed to improve the rheological properties of tailings slurry. The effects of superplasticizer content, the concentration and fineness of tailings, the proportion and type of cementitious materials, temperature, and hydration time on the rheological properties of unclassified tailings slurry and backfill materials were studied. The variation characteristics of the slurry yield stress, plastic viscosity, and thixotropy with different factors were measured by a Brookfield R/S-SST plus rheometer. The experimental results of fresh thickened tailings illustrated that the higher the concentration of the slurry and the finer the tailings, the worse the rheological properties of the slurry. The results of cemented paste backfill materials indicated that the rheological parameters increased as binder content and time increased. The rheological parameters decreased as the temperature increased. The addition of a superplasticizer reduced the rheological parameters and improved the rheological behavior of the fresh thickened tailings and cemented paste backfill materials, which was beneficial to the slurry’s pipeline transportation. This paper can provide technical guidance for slurry transportation in the backfill system and provide a reference for designing the superplasticizer used in tailings.

Jan 5, 2022

By Lumley G, Rowlands D

The overburden slusher (OS) is proposed as a stripping tool that is expected to find application in overburden stripping operations including open cut coal and oil shale mines. OS is expected to combat the effects of increasing depth on the productivity of conventional dragline stripping.Although previously developed stripping techniques have included the use of drag scrapers the OS is sufficiently different as to constitute a new stripping method.A study undertaken at the University of Queensland during 1985 is believed to be the first major study on the use of the OS and preliminary economic results are very encouraging. It appears that the OS has the capacity to remove overburden at a cheaper unit cost than the equivalent powered dragline stripping machine at any comparable depth of overburden. The OS is not adversely affected by increasing stripping depth to the same extent as a dragline. In addition, the action of the OS machine allows for the lowering of spoil face angles, thereby reducing spoil slope stability problems encountered in deep open cut strip mines.

Jan 1, 1986

This report briefly describes the broad program of research and technologic work conducted by the Bureau of Mines on coal and related subjects during 1966. In addition to n description of investigations on mining, preparation, and utilization of coal, an account is given of the Bureau's work in mine health and safety, coal resources, mine explosives, and environmental conditions relating to coal mining and utilization. Details of most of the projects are reported in publications cited throughout this report. Centers and laboratories conducting the coal research and related investigations appear in appendix A; organizations, institutions , and companies contributing to the Bureau's coal research and technologic program are listed in appendix B.

Jan 1, 1967

By G. Lyle

Since its inception CEMI (Centre for Excellence in Mining Innovation) has focused on facilitating innovative solutions to the mining industry in six strategic research areas; GeoRisk, ConstructMine, ValueMine, FindMine, SustainMine and MineTech (visit www.miningexcellence.ca for details). This paper focuses on CEMI?s largest project to date, Ventilation on Demand (VOD). Energy consumption in mines can account for upwards of 40% of a mines operating cost, with a significant portion of this been consumed by the ventilation requirements. VOD provides a significant opportunity to reduce overall mine ventilation requirements and subsequently energy costs, while potentially increasing mine productivity. CEMI is currently in year 2 of an assessment of VOD, focusing on the financial, physical and equipment viability of utilizing such systems in both new and existing mines. This two year program, to be completed by March 31, 2011, is designed to systematically assess such a system to determine if and when it could effectively be applied in underground mines. The paper will describe the process by which the project was initiated, the demonstration projects established to capture data, the means to interpret the data and the modelling developed to calibrate and predict ventilation system requirements.

Oct 1, 2010

Adsorption of Alkylammoniums in the Interlayer of Montmorillonite and its Effect on the Viscosity of Organo-Montmorillonite Gels

Sep 13, 2010

By Ellis S. Hertzog, James R. Cudworth

Tremendous interest has been evidenced in the subject of dewatering and drying ooal for the past 10 years, and yet little effort has been made to summarize the literature, at least so far as this country is concerned. Only a few published articles have dealt solely with dewatering and drying coal. In most cases the subject has been discussed briefly, either in general terms or as to specific installations. It is desirable that a compendium be prepared collecting in one place information on the dewatering and drying of coal, the needs for this process in various fields, the available equipment, and the current American practice in regard to it. This work was underta..lten by the :Bureau of Mines in cooperation with the University of Alabama. New coal-washing plants in which various types of dewatering and drying equipment were in operation were visited in-Pennsylvania; Ohio, India...~a~ and Illinois. The dewatering·and drying of coel has .been studied in this coimtry by the Surface Preparation ·Committee of the ·coal Operato~s• Committee of the .American Mining ·Oongress. In GermaIJY .it has received the special attention of the Reichskohlenr·at, and in Great Britain of the Utilization of Fuel Commi-t-tee of the Insti ti.ite of Min"ing Engineers.

Apr 1, 1938

This paper reviews rehabilitation, closure, and post-closure management of the Tui, Golden Cross, and Martha Mines, all of which are located in the Waikato Region of New Zealand. There was no requirement for rehabilitation of the Tui mine, which was abandoned in 1973. There was a requirement to rehabilitate the Golden Cross mine. Mining at that site ceased in 1997, and rehabilitation is now well advanced. When first approved, there were some requirements for rehabilitation of the Martha Mine, but when reconsented in 1998, those were extended, and in addition a requirement for post-closure management was included. As a result, a Trust, funded by the mining company, has been established to take long-term responsibility for the site following completion of closure. The different rehabilitation/closure requirements at each of these sites illustrates that we have learnt something from the experiences of the past.

Jan 1, 2003

The history of soft and hard rock underground mining is blemished with regional instabilities of mine workings. Whilst the potential consequences of regional instability events are recognised to be high, there is a false perception that the probability of them occurring is very low. In fact, Australia has averaged more than one event per year for the past 20 years. At least five fatalities and over $100 million of losses have been associated with the events. As such, they are a core risk to underground mining and have a significant effect on the quadruple bottom line of business û safety, environment, community acceptance and economics. This paper explores the important roles that risk management has in reducing the probability and consequences of regional instabilities. It concludes that education and continuing professional development are essential elements for effectively managing the risk.

Jan 1, 2003

By Fuzail Siddiqui

"The SIDMIN program aims at filling the mineral processor’s need to know the deportment of ‘minerals of interest’ not just ‘elements of interest’ that pass through the processing plants. Generally, chemistry is used as a tool of routine monitoring on site. Mineralogy, which is relatively much slower, is used more as a tool of research and post mortem investigations and these services are usually provided by a distant facility. The SIDMIN program enables site management to receive chemical and quantitative mineralogical reports on their critical samples daily, simultaneously and affordably.The author developed the SIDMIN program at ZCCM Nchanga Division where it continues to be a powerful tool for monitoring the efficiency of operations. Outlines are given of procedures for quick sample preparation and quantification of significant minerals in process samples. A specimen report is presented, which shows the format of reporting the contributions of individual minerals to metal losses at critical stages of the circuit. It is shown that SIDMIN provides timely information to management, about trends and abrupt changes in the quality of ore, and its processing, in a way never achievable by chemical analyses alone. This greatly helps in resolving the age-old problem of ‘bad ore’ or ‘bad operations’ on a day-by-day basis. For example increase in copper mica in the feed indicates excessive ore dilution during mining. Increased loss of free sulphides was traced to insufficient reagent conditioning time at the Concentrator. Persistent losses of leachable oxides at the Tailings Leach Plant were traced to inadequate leach residence time.SIDMIN is affordable because it can be implemented using basic optical microscopes, minimal quantities of micro-chemical reagents and custom trained site staff who demonstrate good colour perception and an ability to follow laid down procedures consistently."

Jan 1, 2000

By B. H. Moore

Foundation and excavation problems associated with lock construction projects vary widely. Each lock requires a different foundation to respond to a unique geologic setting. The range of heights and founding materials are illustrated thru description of selected structures encountered in the United States. Examples range from 113-ft high John Day Lock on the Columbia River founded on basalt rock to the 17-ft high Lock No. 5 on the Arkansas River floated on a clay foundation. A description of the basic elements of design and construction is presented. Several case histories involving lock design and construction are assessed to aid in recognition of potential problem areas on forthcoming construction. In the past decade there have been many improvements in construction materials and techniques. The application of these new approaches to lock construction is discussed.

Jan 1, 2010

By C. W. Whitten

Iron ore deposits in south-central Missouri have emerged as a possible resource for the rare-earth elements. The Pea Ridge Iron Mine is one such deposit. Rare-earth minerals at the Pea Ridge Iron Mine are contained in breccia pipes consisting primarily of silicon oxides and feldspars. These pipes extend up through the magnetite ore body and appear to be alterations and replacement of earlier hematite. The mineralogy of these pipes is very complex and varied, which could complicate the concentration and extraction of the rare-earth minerals. This U.S. Bureau of Mines !eport represents a study by characterization of the mineral phases to assess the amenability and development of concentration and extraction techniques. Previous characterization of rare-earth minerals has been mainly by transmitted light microscopy. This method along with reflected light microscopy, scanning electron microscopy, and X-ray diffraction was used to identify and characterize the rare-earth and associated minerals. The minerals identified were the major ore minerals, magnetite and hematite; the rare-earth phosphates, monazite and xenotime; the rare-earth silicate, allanite; the minor associated minerals, cassiterite, pyrite, and apatite; and the gangue minerals, feldspar, quartz, and actinolite.

Jan 1, 1990

By S. N. Lekakh

Phosphorous segregated at grain boundaries during solidification and heat treatment dramatically decreases low temperature toughness of precipitation hardened Fe-Mn-Al-C austenitic steel. A thermodynamic analysis was performed to evaluate the possibility of decreasing P and subsequent segregation by Ca- and Ce-additives in the melt. It was shown that the predicted probability of forming a P containing compounds depends on melt composition and treatment sequence. Experimental heats were performed and several micro- and macro-structural effects of Ca- and Ce-additives were recognized by using an automated inclusion analysis technique.

Jan 1, 2010

By R. S. McClain

The Federal Bureau of Mines investigated residues from aluminum plants, to determine if carbon could be removed by flotation while recovering fluorine and aluminum compounds for recycling to the reduction process. This publication summarizes studies on samples representing three types of plant waste products, supplied by three aluminum-producing companies. Samples of flue dust, pot skimmings, and pot linings from the various plants all responded to a simple turpentine flotation scheme to reject 90 to 97 percent of the carbon. Aluminum compound recoveries ranged from 42 to 94 percent on the flue dust, were about 95 percent on the pot skimmings, and ranged from 75 to 89 percent on the pot linings. Fluorine recoveries from the same samples ranged from 35 to 63, 92 to 95, and 77 to 86 percent, respectively. The pot linings contained soluble salts of aluminum and fluorine which were recovered by precipitation with sodium aluminate and carbon dioxide gas. Composites of residues from each plant responded to flotation much the same as the individual samples. Aluminum is produced by the electrolysis of alumina in a molten cryolite bath. The electrolytic reduction cell consists of a carbon-lined box containing a pad of molten aluminum which serves as a cathode, a carbon anode, and an electrolyte of molten cryolite in which the alumina is dissolved. Alumina is reduced to aluminum at the cathode, and carbon is oxidized at the anode.

Jan 1, 1961

By D. M. A. Flight, G. E. M Hall, P. R. Simpson

theoretical viewpoints.

Apr 1, 1994

By I. R. Hanby

A simple solution to the problem of whether to round the calculated number of trucks up or down to the nearest whole number is to adopt as criterion the minimum cost per unit volume/mass moved, assuming all trucks in the fleet are of the same type. When the effects on journey time of varying haul-road slope are calculated for several rolling resistances, it is shown that the optimum angle of 7.5 degrees is moderately independent of both rolling resistance and height climbed; the lower the resistance, the lower the sensitivity to ramp angle, but if haul-road gradients do not exceed 1 in 10 (5.7 degrees) for safety reasons then travelling time will never be more than 7% greater than its theoretical minimum. Further calculations result in a graph of the maximum payload values to incur the minimum cost, for different values of total effective resistance

Jan 1, 1991

By T. G. Carter

Support system design for tunnels and underground excavations has for many years relied heavily on the use of rock mass classification systems and the Hoek-Brown failure criterion as a means for characterizing rock mass behaviour. Because of their development, both the GSI system and the Hoek-Brown criterion admirably characterize most ?normal? rockmasses from the viewpoint of their behaviour for rock excavations. They, however, run into difficulties when applied at the two ends of the rock competence scale. This is largely because block size and incipient strength are such that rockmass behaviour in these domains tends not to be controlled by interblock shear strength but rather by material strength. At the low end of the rock competence scale (UCSi <<15 MPa and GSI generally <30) discontinuities play less of a role and rock mass strength tends to matrix strength. Similarly, at the high end of the scale (GSI >>65, mi>>15), because discontinuities are now widely spaced, block size becomes so significant that again, intact material behaviour rather than the fracturing becomes the dominant factor controlling rock mass strength. In this paper several case examples are presented to illustrate the application of the high-end (spalling) and low-end (weak ground) transition Hoek-Brown relationships proposed by Carter, Diederichs and Carvalho (2007) as a basis for better defining rockmass behaviour at the extreme ends of the rock competence scale.

Jan 1, 2008