Search Documents

By W. N. Patterson

The three major objectives of this contract were (1) to survey underground diesel-powered mining machinery to determine noise exposure problems, (2) to recommend noise control techniques, and (3) to develop a technique for predicting underground sound levels from surface sound power measurements. The objectives were achieved. The contractor developed information on the severity of the noise problem caused by diesel engines underground and pinpointed the equipment causing the problems. He recommended a number of corrective techniques that can provide relief until long-term solutions are found. A procedure for predicting underground noise levels from above-ground measurements of the machine noise was found valid for several cases tested.

Jan 1, 1975

By J. Yuan

Ground calcium carbonate (GCC) and chemically precipitated calcium carbonate (PCC) have become important mineral-based commodities in recent years. GCC manufacturing generally requires high purity and high brightness deposits of marble, chalk or limestone as the stone source. PCC usually uses limes made from lesser quality limestone deposits. GCC products have a wide span of particle size, with a d50 size ranging from sub micrometers to as large as several inches such as those used in landscaping. PCC products are typically limited to less than 10 µm (1,250 mesh). Each PCC product has a narrowly distributed size range. GCC and PCC products tend to have higher levels of whiteness com-pared with other traditional filler and extenders, such as kaolin and talc. Published statistics of GCC production volume often vary due to the exclusion of certain size range GCC products. According to Roskill’s latest estimate, world GCC capacity was believed to exceed 56 Mt (62 millionst) during 2004 for all grades.

Jan 1, 2005

By R. G. Zaripova, N. D. Ryan, H. J. McQueen

The austenitic and ferritic stainless steels do not undergo any phase transformation that induces very fine grains in the product through thermomechanical processing as practiced in most other steels. Considerable grain refinement can be achieved by intense multistage deformation descending through warm to cold working; notably multi-axial forging of bulk material can attain high strains with diminished risk of cracking. Hot working to improve ductility yields finer grain sizes as the T is reduced and strain rate E raised; increased strain has limited effect due to the steady state regime. Ferritic steels develop subgrains with size diminishing as E rises and T falls with the advantage of retained strain hardening; recrystallization delivers grains several times the cell size. In austenitic steels, dynamic recrystallization (DRX) provides finer grains at higher E and lower T with a lower limit due to intergranular cracking. The DRX grains contain a strengthening substructure that can easily be retained by quenching; if static recrystallization is allowed to occur the grain size rises markedly. Multistage rolling with diminishing T is able to provide grain refinement to the same degree as straining at the finishing T yet provides better ductility. grains on recrystallization. As a result of the strain induced transformation to martensite, small subzero deformations of austenitic or duplex steels produce very high dislocation densities that yield marked grain refinement when they revert upon reheating.

Jan 1, 2004

By William C. Cooley

A literature search and survey were prepared on the technology of surface hydraulic mining, with particular reference to its possible use in the United States forstripping overburden from surface coal mines. Extensive use was made of Russian references which were translated into English. The advantages and disadvantages of hydraulic mining and hydrotransport are identified as well as criteria for selecting potential applications. At present, the major U.S. application is in the phosphate industry of Florida and North Carolina. Potential locations for hydraulic stripping of overburden from coal seams are identified in the states of Alaska, Illinois, Montana, Washington and Wyoming. Other potential applications include the hydraulic mining of peat in Minnesota, and the stripping of overburden from lignite in Texas, Montana, North Dakota and South Dakota. Further research is recommended, particularly on the subject of dewatering of fine clay slimes to avoid water pollution and to permit rapid reclamation of mined areas.

Jan 1, 1976

By A J. Scogings, W J. Shaw

The successful development of industrial minerals projects requires an integrated, holistic understanding of the metallurgical and product performance test work in the context of the geological setting of the deposit and applied to mining, processing and marketing of saleable products. The product specifications provide the essential starting point for geometallurgical studies. A sound understanding of the desired product is needed to design and interpret a program of test work. Examples are provided from recent studies on bentonite and graphite deposits.For bentonite projects, the naïve testing of only the cation exchange capacity (CEC) as a measure of purity can lead to unexpected outcomes when the deposit is mined. The CEC attribute may remain the same, while other important properties such as pH and swelling index change markedly with depth, due to weathering and oxidation, leading to disappointing production outcomes.For graphite projects it is not enough to report only total graphitic carbon content (TGC). Knowledge is required of the in situ flake size and textures in addition to purity and flake size distribution of extracted graphite, which may all vary from one domain to another across the deposit. Such geometallurgical attributes of the ore will impact on the ‘basket price’ used to estimate the value of marketable parcels of expected product.Disclosure of such information must be considered part of fully informing the market. As with all new project developments, consideration of the JORC (2012) and VALMIN (2015) Codes requires disclosure of all material information. This includes the geometallurgical characterisation, ie those aspects of the mineralogy that impact on resource evaluation, ore reserve definition and project valuation.CITATION:Shaw, W J and Scogings, A J, 2017. The importance of geometallurgical test work for industrial minerals projects, in Proceedings Tenth International Mining Geology Conference 2017, pp 83–92 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 20, 2017

Human-caused global warming has become the environmental cause celebre of the early 21st century. The strong warming alarmist camp currently includes the United Nations, most Western governments, most of the free press, many large corporations (including Enron, before it failed), the major churches, most scientific organisations and a large portion of general public opinion. This phalanx of support notwithstanding there is no scientific consensus as to the danger of human-induced climate change. There is, therefore, a strong conflict between the level of public alarm and its scientific justification. How can this be? In a democracy, the media serve to convey to the public the facts and hypotheses of climate change as provided by individual scientists, governmental and international research agencies, and NGO and other lobby groups. In general, the media have promulgated an alarmist cause for climate change; they have certainly failed to convey the degree of uncertainty that is characteristic of climate science, or a balanced summary of the many essential facts that are relevant to human causation. Climate change is as much a geological as it is a meteorological issue. Natural climate changes, both warmings and coolings, are indeed a societal hazard. We usually deal with geological hazards by providing civil defence authorities and the public with accurate, evidence-based, general information about events like earthquakes, volcanic eruptions, tsunamis and floods, and then by adapting to the effects when a damaging event occurs. As for other major natural disasters, the appropriate preparation for extreme climate events is to mitigate and manage the negative effects when they occur, and especially so for dangerous coolings. Attempting instead to æstop climate changeÆ by reducing human carbon dioxide emissions is a costly exercise of utter futility. Rational climate policies must be based on adaptation to dangerous change as and when it occurs, and irrespective of its sign or causation. The issue now is no longer climate change as such, the reality of which will always be with us. Rather, the issues are, first, the failure of the free press to inform the public about the true facts of human-caused climate change and of the dangers posed by natural climate change. And, second, the vested interests held by many of the groups of warming alarmists. These interests include not only the obvious commercial ones, but also the many scientists and science managers who have discounted or remained silent about the huge uncertainties of the human-caused global warming hypothesis because it suited them to do so. Public opinion will soon demand an explanation as to why experienced editors and hardened investigative journalists, worldwide, have melted before the blowtorch of self-induced guilt, political correctness and special interest expediency that marks the sophisms of global warming alarmists.

Jan 1, 2007

By Gualberto Salas Torrelly

El avance tecnológico en los sistemas de iniciación en voladura abarca desde el sistema convencional (Mecha de Seguridad y Fulminantes hasta el sistema de iniciación electrónica, donde a través de un control de vibraciones se controla la energía liberada en un disparo, optimizando la fragmentación y disminuyendo el daño a las paredes del pit. En ese sentido, el sistema de iniciación con detonadores electrónicos, fija con claridad los conceptos de precisión, flexibilidad y seguridad. Por ello, el presente trabajo señala el uso de detonadores electrónicos por la Sociedad Minera Cerro Verde con la finalidad de evaluar sus resultados en seguridad, precisión, fragmentación, vibraciones, y control de daño a las paredes de la mina. Los resultados fueron óptimos -en tanto mejoró la fragmentación, el proceso de carguío y se incrementó el flujo en chancado primario.

Sep 12, 2005

Hydrogen and carbon monoxide reduction data were obtained on pelletized materials of the type currently being prepared commercially in Australia.Pellets, approximately 1 cm diameter, made from Deepdale, Iron Prince, and Mt. Newman iron ore were reduced by hydrogen over the temperature range 500°-900°C and the reduced pellets were examined by thermogravimetric, microscopic, electron probe, and x-ray techniques. After an initial time delay it was found that up to 95 per cent reduction the data could be described by a porous model where gaseous diffusion through the solid is rate controlling. Independent measurements of effective diffusivity supported the values obtained from the reduction data. Above 95 per cent reduction the rate decreased markedly due to the formation of retained wustite or fayalite.Comparison with reduction by carbon monoxide over the temperature range 750°-900°C showed that the rate of reduction was approximately five times slower than for reduction by hydrogen.The rate of reduction was found to be a function of the initial properties of the pellets which may account for the widely conflicting results that have been obtained with previous investigations on porous pellets.

Jan 1, 1971

By J Wesseloo and Y Kim, Y Potvin, G Mungur, D Grant

At the previous MassMin conference held in Sudbury in 2012, the authors proposed a new framework going beyond dilution and equivalent linear overbreak sloughing (ELOS) for stope reconciliation in relation to the planned stope design. More specifically, the new process investigates performance outcomes including rock overbreak (OB) and fill overbreak (FOB), rock underbreak (UB) as well as geomechanical and operational aspects such as blasting, fragmentation and other production data.Based on the findings of the original 2012 study, a comprehensive data gathering program has been undertaken involving design and reconciliation data from 43 stopes mined between September 2012 and October 2014 at BHP Billiton’s Olympic Dam (OD) operation. The new database structure was based on four types of data:stope definition and performance datastope geometrygeotechnical parametersoperational parameters.The new database allows a more in-depth investigation of stope performance. It is now possible to quantify and analyse UB and OB performance from each wall individually as well as the crown. In this paper, the influence of several parameters on recent stope performance at OD is analysed. The underlying reasons for stope wall performance outcomes are discussed in this paper.CITATION:Potvin, Y, Grant, D, Mungur, G, Wesseloo, J and Kim, Y, 2016. Practical stope reconciliation in large-scale operations part 2, Olympic Dam, South Australia, in Proceedings Seventh International Conference and Exhibition on Mass Mining (MassMin 2016), pp 501–510 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2016

By J. R. Lucas, R. L. Frantz

Mine sealing programs for the alleviation of acid mine drainage were begun by the Federal Government in the '30's. As part of an acid mine research project to The Ohio State University, a field test was undertaken to determine the effectiveness of mine seals for reducing mine acid. Details of the tests made at the McDaniels mine show the feasibility of air-sealing and flooding an acid-producing drift coal mine. Work by the University continues. The Federal Government undertook in the early thirties an extensive mine sealing program for the alleviation of acid mine drainage. In the states of West Virginia, Ohio, and Pennsylvania many general summaries have been made on this program but no critical evaluation with supporting data has been found on the effectiveness of mine seals for reducing mine acid. Because of this it was decided to undertake a field testing program as part of an acid mine research project of the Engineering Experiment Station, The Ohio State University. The objective of this phase of the project was to develop and install a field research laboratory for acid mine drainage studies. Specifications for such a mine laboratory were developed and resulted from the following considerations: 1) Size and preservation—the test mine shou1d be of limited size to permit frequent and detailed examinations; it should be in a reasonably sound condition to permit safe entry. 2) Isolation—the mine should be physically separated from all other mines. 3) Openings—a minimum number would be desirable to reduce the sealing problem. 4) Structure—the mine especially near the openings should be structurally sound. 5) Acid production—the mine should be producing significant quantities of acid. After considerable searching, the McDaniels mine was selected in the Hocking coal field in Vinton County just above Lake Hope State Park in southeastern Ohio. The small drift mine in the middle Kittaning coal consisted of two small rooms with one mine opening about 6 ft above a seasonal stream bed. Before it was finally decided to seal the mine, a short study was made of the acid drainage over several months. Fig. 1 shows a plot of acidity (milligrams per liter), flow (gallons per minute), and acid production (pounds per day) vs time over the sampling period. Because the coal was overlain with a porous sandstone, the mine drainage was consistent the year around even though the mine was

Jan 1, 1961

By R. G. Knickerbocker, T. E. Evans, D. R. Torgeson

"INTRODUCTION Sponge iron is a product resulting from the reduction of an iron oxide at such a low temperature that fusion does not occur, and the reduced particles retain substantially the same shape as the original ore. The removal of oxygen in the reduction process leaves the metal porous and reactive. Sponge iron may be compared in general to a chemically precipitated substance insofar as reactive properties are concerned. The high specific surface and the orientation of metallic structure are factors which probably contribute to the reactive properties of sponge iron.The term ""gaseous reduction,"" as applied to iron ores, required clarification. Strong evidence exists, for example, that ore is partly reduced to sponge iron by carbon monoxide in the blast furnace at temperatures around 800° C. at a point that may be as high as 30 feet above the tuyores. In 1923 and 1924, Sims and Wood attempted to reduce iron oxide with carbon in an Arsem vacuum furnace at 980° C. These investigators found that only 6 percent of the iron was reduced to metal when the iron oxide-carbon mixture was heated for 1 hour under evacuated conditions, whereas at atmospheric pressure 70 percent of the iron was metallized. Their results indicate that the process of iron-ore reduction at temperatures below the melting point of the ore may proceed largely, if not entirely, by the action of reducing gases even when the reducing agent is solid carbon. Therefore, the term ""gaseous reduction,"" as used heroin, is defined as a process in which iron ore is brought into intimate contact with a reducing gas produced in separate-equipment from the reduction chamber itself.A large amount of pilot-plant development on gaseous reduction of iron ores has been carried out by the Bureau of Mines at the Boulder Experiment Station and had as its objective the reduction of fine iron ore by means of producer gas. The use of use gas was prompted by two considerations: First, the possible utilization of large reserves of Western noncoking bituminous coals and lignites contiguous to iron-ore drewwing; and second, an investigation of the results that might be achieved in the pilot-plant gaseous reduction of fine iron ores by means of a relatively reducing gas. The results obtained, it was felt, would be of considerable value in indicating the direction which gaseous reduction experimentation must take for the development of a commercially practicable and economic process for the production of sponge iron."

Dec 1, 1946

By A. Kapito

The ferrite-pearlite microstructure is the most popular microstructure for alloys used in structural applications, including railway wagon wheels. These alloys have been designed through alloying and thermo-mechanical processing to have a refined microstructure. Ferrite-pearlite alloys are low cost, weldable, have good fabricability, and are reliable under extreme conditions. Given these performance attributes, it seems unlikely then that their dominant position as structural steels would ever be challenged by alternative microstructures. One major achievement in the development of ferrite-pearlite steels has been in the refinement of their interlamellar spacing to very fine distances of the order of < 0.3 um. A refined microstructure increases the hardness of the alloy, thus increasing its life under wear conditions. The interlamellar spacing in pearlitic steels has, however, been refined almost to its theoretical limit. The increasing demand for speed and increased axle loading on railway wagons requires the use of stronger, tougher, and more durable materials. This has opened the window for the development of novel bainitic steels. Bainitic alloys have a higher level of microstructural refinement than pearlitic ones. They have shown to have good wear resistance and rolling-contact fatigue resistance, and high toughness. This paper will discuss the progress to date on the development of bainitic railway wheel alloys. Four alloy chemistries have been chosen for possible further development.

Jan 1, 2012

By F. M. Doyle

Metal removal kinetics and metal ion selectivity in ion flotation were studied from a thermodynamic perspective. Surface tension data could be used with the Gibbs adsorption equation to quantitatively predict the metal ion removal kinetics in alkylsulfate-Cu systems. However, surface tensions predicted cation selectivity coefficients in the sodium dodecyl-sulfate (SDS)-Cu-Ca and SDS-Cu-Pb systems rather poorly, although the predicted order of the selectivity (Cu2+<Ca2+<Pb2+) was correct. Another thermodynamic selectivity model, which used the Grahame adsorption equation and a geometrical analysis, predicted cation selectivity coefficients that agreed very well with experimentally measured values.

Jan 1, 2000

By K. G. Tshilombo

It should be possible to use an oxygen probe to follow iron removal during converting, if local equilibrium is established between iron in the matte and the iron oxides in the fayalitic slag. The oxygen activity is expected to increase strongly as the iron content of the matte decreases (and the iron activity in the matte drops) while the iron oxide activity in the slag remains constant. To test this idea, oxygen activities were measured in synthetic mattes (made up of mixtures of Cu2S, FeS and Ni3S2) when in contact with silica saturated SiO2-FeO slags, and silica and (initially) magnetite saturated SiO2-FeO-Fe3O4slags. The measurements were performed on laboratory scale at 1250°C, using an oxygen probe consisting of an MgO-stabilized zirconia electrolyte and Fe/FeO reference, and containing the sample in a silica crucible. Electrical contact to the matte was by means of a platinum wire. The measured oxygen activity was sensitive to the iron content of the matte, and insensitive to the composition of the gas atmosphere over the melt. The measured oxygen activity was generally close to that predicted by Fact Sage calculations. This indicates that such oxygen activity measurements could be useful to monitor iron removal during converting of nickel-copper-iron mattes.

Jan 1, 2007

Casing or lining pipe is used in boreholes for the following reasons:1. To preserve the hole while drilling and after it is finished.2. To shut water out of the hole or to isolate any particular water, gas, or oil-bearing stratum.Deep holes can seldom be drilled without casing, and only when in firm strata. If caving from the walls is at all likely while drilling, casing is necessary in order to prevent the tools horn being buried...

Jan 1, 1924

This paper is in two parts. The first covers the evolution of dredging leading to the development of the æNZ typeÆ large dredge and the second, current alluvial gold recovery practice in NZ. NZ was the first country in the world to adapt the bucket-ladder dredge to alluvial gold recovery. Between 1857 and 1907, gold worth (at today&apos;s NZ price of about NZ$600/ounce*) over $11 billion was exported û from a country with well under one million people at that time. Over 200 small dredges operated, mostly on the Clutha River, around the turn of the century, however by 1940, only 20 or so large machines remained, and the last of these, the 4000 ton &apos;Kanieri&apos; ceased operations three years ago. Recently recognition of the superior digging power of the hydraulic backhoe and reintroduction of the simple &apos;trommel and riffleÆ plant with about 80 m3 /hour capacity has led to a proliferation of static and floating plants, there being at least 50 currently in operation on the West Coast and in Otago. There are signs however, that the process of evolution of such small unsophisticated plants into larger, more efficient units has begun again. * At the time of writing (October 1984) NZ$l. 00 = US 50ó. NZ dollarsare used throughout this paper.

Jan 1, 1985

By D Hill

In the Ngakuru area zeolite deposits occur in late Quaternary lacustrine vitric tuffs of the Ngakuru Formation and two of the deposits are being mined. The Ngakuru Formation overlies the Ohakuri Ignimbrite dated at c. 240 ka, and is overlain by younger alluvial sands and gravels. Individual zeolite deposits contain 50 - 80 per cent zeolite over a thickness of up to 45 m in thinly stratified vitric tuffs and are localised along NE-trending normal faults. Glass shards in the tuffs are replaced by the silica-rich zeolites mordenite and clinoptilolite. Amorphous silica (opal A), opal-CT, Kfeldspar and smectite are also present. The zeolites and other minerals are very fine grained (&lt;10 8m), with open meshes of crystals that result in high porosities (52 - 70 per cent) in mordenite-rich tuffs. Zeolitic tuff samples typically have cation exchange capacities of 80 to 110 meq/100 g and internal surface areas of 25 - 58 m2/g, which combine to give high liquid and odour absorption capacities. The first zeolite deposit (Mangatete) was found in 1992, and this and the Twist Road deposit are worked by quarry benching into the side of hills. The zeolitic tuffs are dried and crushed to produce a variety of products including adsorbents for soaking up oil/chemical spills and animal wastes, animal feed supplements, water treatment, and sports turf and slow release fertiliser. The Ngakuru zeolite deposits formed at shallow depth (&lt;100 m) along fault zones from reaction of glass-rich tuff beds with groundwater-diluted geothermal water during the late Quaternary, and are as young as 8500 yr BP from 14C dating of plant material in sinter associated with the Mangatete deposit.

Jan 1, 2005

By P D. Katsabanis

According to Persson(1) steady state detonation along a cylindrical charge can be regarded as a self propagating process in which the axial compressive effect of the shock front discontinuity changes the state of the explosive so that exothermic reaction sets in with the requisite velocity.

Jan 1, 1990

By J. N. Van der Merwe

Due to the approaching depletion of reserves in the Witbank Coalfield, and the fact that the Waterberg Coalfield is as yet under developed, there is increasing pressure to extend the lives of the operating coal mines in the Witbank Coalfield. One potential source of coal is the old pillars, often small and at shallow depth, that were not left with secondary extraction in mind. At face value, some of these pillars appear to be suitable for secondary mining due to their high safety factors. However, it is known that over time, these pillars have scaled and the current sizes are smaller than the as-mined dimensions. It is also known that at shallow depth, the overburden is often less likely to fail during secondary mining, resulting in high abutment loads on the unmined pillars. The paper proposes a systematic method to pre-evaluate those old pillars for the possibility of stooping. The method consists of elements of fundamental methods and newly developed technology. In essence, it revolves around using empirical methods to estimate current pillar dimensions, followed by numerical modelling to investigate the probability of progressive pillar failure and then fundamental methods to determine the limits of applicability of the numerical model.

Jan 1, 2012

By A. J. Weinig

IN the accompanying figure consider the classified AB in closed circuit with a ball mill, wherein T = Tonnage of new feed C = Ratio of circulating load Now consider that the circulating load is made up of two portions of ore. One portion is due entirely to the characteristics of the ball mill and the tonnage of new feed impressed on the ball mill. This portion of the circulating load in no way is to be blamed on the characteristics of the classifier and is all composed of oversize. Consider, for illustration, that this portion of the circulating load is handled in the A division of the classifier, assuming that the classifier is divided longitudinally into two divisions by an imaginary line. Because the classifier does not usually make a perfect separation of the undersize, a certain portion of the total circulating load is to be directly blamed on the efficiency of the classifier. Let this portion of the circulating load be considered as being handled in the B division of the classifier. Now if the classifier is operating perfectly (100 per cent efficient), the width due to the B division becomes zero and correspondingly the efficiency of the classifier diminishes as B becomes wider in proportion to A. If E is the mechanical efficiency, then

Jan 1, 1934