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By Ronald E. Hamilton

"An attempt to review the recent literature on comminution reveals at once that the subject has many ramifications and that the applications are so diverse that there are very few general statements which can be made.It. seems reasonable to start classification on the basis of size of material as Input to the comminution process. However, we find that this can only be done in a very imprecise manner.The initial step of breaking rock from its natural state of very large pieces in geological formations into sizes suitable for processing is accomplished by blasting. This step in the process has not been ex-amined in this project except to note that great changes have been made during the last decade or so in the explosives used, and in the method of handling them. We should determine what effect changes in mining methods can have on the need for crushing.The second step in the process is usually primary crushing, performed by gyratory or jaw crushers. The largest chunk which can be fed to a jaw crusher depends on the size of the machine, and should be larger than the largest fragment produced in the miring process. It is obvious that the larger the crusher, the less care required in mining to en¬sure the absence of rocks too large to be crushed. The optimum size of crusher to minimize overall cost of mining and reduction is not at all obvious, and no information on this point has come to light in this investigation.It is rather generally accepted that size reduction is most efficiently done in small stages, and that different machines have different opti¬mum size ranges of feed. For example, crushers are preferred for sizes above about 1"", rod mills for the range between 1"" and 0.1"", ball mills are preferred from 0.1""down to perhaps 10 microns, and vibratory mills, or jet mills, below 10 microns."

Jan 1, 1976

By H Thanasekaran, J Kohmuench, B Seaman

To achieve an efficient separation in the flotation process, valuable particles need to be selectively segregated from the gangue while utilising a minimum number of flotation stages. TodayÆs existing flotation technologies are effective for fine particle size classes; however, limitations due to particle buoyancy and bubble-particle detachment restrict the effectiveness of traditional flotation approaches on coarser particles. As a result, flotation circuits are generally configured to process only fine particle size classes in order to maximise recovery in the primary stages. Eriez has invented a novel flotation technology, the HydroFloat, which overcomes these limitations by carrying-out flotation in a dense, fluidised-bed medium allowing for the recovery of coarse particles (>0.250 mm). Over the last 15 years, this technology has been successfully applied to industrial minerals with several full-scale units installed to recover particles up to and exceeding 3 mm diameter in primary flotation circuits. This paper includes discussions on the history of this technology, process theory, existing applications, and a review of recent sulphide-based laboratory test work conducted for Newcrest mining and others. Benefits of this approach, such as improved recovery, low energy consumption and reduced reagent addition will also be reviewed.CITATION:Kohmuench, J, Thanasekaran, H and Seaman, B, 2013. Advances in coarse particle flotation - Copper and gold, in Proceedings MetPlant 2013 , pp 378-386 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 15, 2013

By N. McEwan

Keywords: refractories, chromite, Marico This paper examines the role of refractory-grade chromite in refractories. The chromite deposit at Verref?s Marico Chrome mine is described. The refractory properties of chromite and their role in basic refractories are described. The properties and metallurgical applications of chrome-containing refractories are described and finally environmental issues associated with chrome-containing refractories are discussed.

Jan 1, 2011

By J. C. Martin

Equations for three-phase, three-dimensional, compressible flow (including capillarity) are reduced to two-dimensional relations by a partial integration. This reduction allows three-dimensional flow problems to be treated with mathematics for only two spatial dimensions. The results can be used to formulate flow equations for two-dimensional reservoir simulators in which the effects of capillarity and fluid segregation in the third dimension are represented. Such reservoir simulators would retain many of the aduantages of two-dimensional simulators while simulating three-dimensional effects. The principal restriction of the method is that the thickness of the reservoir should be small, compared to the distance across the reservoir. INTRODUCTION In recent years, computers have been used to calculate the performances of many reservoirs. Most of the detailed calculations, however, are based on finite difference solutions of the flow equations, and present day computers are seldom able to handle a sufficient number of cells to produce entirely satisfactory solutions, even for reservoirs represented by two-dimensional arrays of cells. The situation becomes much worse when one wishes to approximate the reservoir by a three-dimensional array. A great saving in computation or a more detailed solution can be obtained for many reservoirs by using the partial integration of the equations of flow presented in this paper. The integration reduces the three-dimensional equations to two-dimensional relations; and, for studies of two-dimensional flows in vertical cross-sections, the equations are reduced to one-dimensional relations. Most reservoir performance calculations currently are based on one- or two-dimensional flow re1ations.l-3 In some cases flow in the third dimension is approximated by assuming a particular type of vertical saturation distribution, such as gravity segregation.l.2. The relations developed in this paper approach those for segregated flow as the capillary pressures approach zero, and they approach those for uniformly distributed saturations as the capillary pressures are increased. For this analysis, the ratio of the reservoir's thickness to the maximum distance across it must be small. The capillary pressures between the oil and water should also be small compared to the maximum pressure difference in the reservoir. This requirement is met by most reservoirs. It is assumed that the capillary-pressure curves are well defined, whether or not hysteresis effects are included. Also, the reservoir must have sufficient vertical permeability to allow the fluids to segregate. The results presented here provide a firm theoretical foundation to Coats' et aL5 assumption of vertical equilibrium and extend the relations to three-phase flow. Coats' assumption of vertical equilibrium, which he verified by calculations and experiment, is developed here mathematically from basic flow equations. DISCUSSION SATURATION AND PRESSURE DISTRIBUTIONS Appendix A presents a mathematical analysis of fluid flow in reservoirs where the ratio of thickness to maximum distance across the reservoir is small. The results indicate: (1) that the fluids along any line perpendicular to such a reservoir's upper surface are in static capillary equilibrium (vertical equilibrium); (2) that, to a first approximation, the fluid pressures and properties are functions of only areal position in the reservoir and time; and (3) that hydrostatic pressure gradients exist along any line perpendicular to the reservoir's upper surface. The results might be expected after studying several physical considerations. First, no flow is allowed normal to the upper and lower reservoir boundaries, which are relatively close together.

Jan 1, 1969

By Susheel R. Kolwalkar

A significant increase in the side shear capacity over a period of time is often observed in case of driven piles. This phenomenon is referred to as ?setup? or ?freeze?. This phenomenon cannot be predicted based on the knowledge of the engineering properties of soil. Different kinds of mechanisms have been proposed in order to explain set-up in cohesive soils. In engineering practice, set-up is incorporated in design on the basis of empirical formulae and depends to a large extent on personal experience and judgment of the design engineer. Set-up is a natural process which cannot be accelerated by any existing practice. A research was initiated to investigate the mechanism of pile set-up in clayey soils and explore the possibility of accelerating the set-up process by an electro-kinetic method. The system chosen for the present study consists of a prototype steel pile driven in kaolinite clay. A laboratory test program was developed at Cleveland State University in order to meet the goals of the proposed research. Results obtained from these tests are very encouraging and show pile capacity increase of 200% within the first 5 days of electric gradient application versus those that experience natural set-up. In this paper, theoretical considerations and laboratory test results are presented and discussed.

Jan 1, 2008

By Walter Ensinger

Special foundation works is one of the most innovative sectors in civil engineering and construction. Both engineering techniques and construction machinery are undergoing continu­ous further development. These developments are providing ways to meeting the world-wide requirement for special geotechnical works even faster, even better and more efficiently. Unfortunately, accident prevention organisations have had to realise that the figures on in­dustrial accidents in special foundation works are still above average in number. The Safety & Environmental Working Group of the EFFC thereupon started to carry out a survey on acci­dents occurring in this sector and used this information as a basis for the preparation of acci­dent statistics and an accident analysis. The objective of this undertaking is to determine key accident occurrences and their causes and to consequently determine measures for improved health and industrial safety.

Jan 1, 2002

By John P. Turner, Benjamin J. Turner

"Non-destructive testing and evaluation (NDT/NDE) methods have become standard tools as part of the post-construction quality assurance of drilled shaft foundations. In responding to anomalies, foundation designers, owners, and contractors face a number of choices, including: (i) acceptance of a shaft with known anomalies, (ii) further investigations of integrity (e.g., concrete coring), (iii) repair schemes, and (iv) reject and replace. To assist in selecting the best option, analyses are often performed that involve assessing the structural performance of reinforced concrete shafts that may include defective concrete or voids. Currently, the analytical tools for predicting the flexural strength and stiffness of drilled shafts with defective concrete located in discrete regions of the cross section are limited. This paper presents a robust moment-curvature analysis tool for drilled shafts based on the fiber-element discretization method. The tool allows for consideration of anomalous or defective concrete regions in the shape and location that they are believed to exist in the shaft while considering explicitly the nonlinear material behavior of the intact regions based on expected material properties. A case study is used to illustrate the practical application of the analysis to drilled shaft projects.INTRODUCTIONImperfections such as defective concrete or accidental eccentricity of reinforcing cages are an inherent part of the drilled shaft construction process that will occur occasionally even when construction best-practices are followed. Petek et al. (2002), O’Neill and Sarhan (2004), Poulos (2005), and others have described the effects that construction defects can have on the axial and lateral performance of drilled shafts. Our industry has seen rapid progress in recent years in the development and improvement of tools for detecting drilled shaft anomalies, such as gamma-gamma and crosshole-sonic logging, sonic-echo testing, thermal integrity profiling, and even visual inspection with invasive video cameras. Nonetheless, in most cases the wealth of data from these tests is used by foundation engineers to make a fairly “black or white” decision—should the defects be repaired, or should the shaft be rejected? A third option that is not typically considered is to directly analyze the section, including anomalies, and compare the reduced strength and/or ductility to the actual project demands. This option takes full advantage of the data collected during integrity testing, and may provide a justifiable means for avoiding further construction costs and delays, whether for repair or replacement."

Jan 1, 2016

By T. Hidayat, D. Shishin, S. Sineva, M. Shevchenko

The effects of the slagging components Al2O3, CaO and MgO on the thermodynamics and phase equilibria of the gas/slag/matte system with major elements “Cu2O”-“FeO”-SiO2-S are characterised using an integrated experimental and thermodynamic modelling approach. The experimental technique included high-temperature equilibration experiments using a spinel substrate in controlled gas atmosphere (CO/CO2/SO2/Ar), quenching of the sample and subsequent measurement of the compositions of equilibrium phases with Electron Probe X-ray Microanalysis (EPMA). Thermodynamic modelling is undertaken using the computer system FactSage. In previous experimental studies on this system, the separate effects of Al2O3, CaO and MgO were determined. In the present investigation, the combined effects of these additional components are investigated at 1200oC and P(SO2) = 0.25 atm and a range of P(O2)’s. Special attention is paid to ensuring chemical equilibrium is achieved in each case, for this reason possible kinetic factors are systematically analysed. The results obtained are presented in the form of graphs showing the compositions of matte and slag phases as functions of copper concentration (matte grade). The new experimental data are used for the improvement of the thermodynamic database for multicomponent copper-containing systems. The effects of the slagging elements on this multicomponent system will be presented in the paper. INTRODUCTION Whilst Fe-O-Si form the principal components of copper smelting and refining slags, additional impurities are present in industrial practice typically at 2–5 wt.% Al2O3, 1–4 wt.% CaO and 1–2 wt.% MgO levels (Davenport, King, Schlesinger, & Biswas, 2002). These elements are introduced into the slag as impurities in concentrates and other feedstocks, in fluxes added to the process and in refractory materials. Understanding, and accurate description, of the changes that take place in the smelting process in the presence of these additional elements is of major importance to the optimization of industrial operations. Although experimental data are available on slag/copper matte equilibria, further work is needed to accurately characterise the influence of Al2O3, CaO and MgO on phase equilibria and elemental distributions of elements in gas/slag/matte systems. The individual effects of the Al2O3, CaO and MgO slagging components on equilibrium phase assemblages under selected conditions have been quantified in a recent series of studies on the Cu–Fe–O–S–Si-(Al, Ca, Mg) gas-slag-matte-metal system (Fallah- Mehrjardi, Hayes, & Jak, 2018; Fallah-Mehrjardi, Hidayat, Hayes, & Jak, 2017a, 2017b; Hidayat, Fallah-Mehrjardi, Hayes, & Jak, 2018a, 2018b; Jak et al., 2016; D. Shishin, Decterov, & Jak, 2018; Denis Shishin, Hayes, & Jak, 2018). Since, thermodynamically, the condensed phases do not behave ideally, it is to be expected that the effects of individual elements may not be additive, and the additional interactions between the Al2O3, CaO and MgO slagging components will also have to be taken into account. These additional effects are expected to be smaller than those of the individual components, so higher accuracy is needed. The present paper describes analysis of the precision and accuracy of the experimental technique on multi-component, multi-phase equilibria in these systems to enable the combined effects of Al2O3 + CaO + MgO on slag/matte/spinel equilibria, i.e. for high Fe/SiO2, to be accurately measured. The effects of Al2O3, CaO and MgO on the gas - slag - matte are analysed using a thermodynamic modelling approach with the computer package FactSage.

Jan 1, 2019

By Steven W. Wilson, Brigitte Lacouture, Nichola A. McKay

"The Aqqaluk deposit is a lead-zinc ore body that lies immediately north of the Main Pit at Teck Cominco’s Red Dog Mine in Alaska. It is scheduled to begin production in 2011 or 2012. A project team was formed in late 2004 to plan and implement an ore characterisation and metallurgical evaluation on the Aqqaluk ore. The main objective of this program was to facilitate the transition from Main Pit to Aqqaluk ore in the Red Dog concentrator. The program will develop a detailed, spatially-oriented characterisation of the Aqqaluk deposit attributes including lithology, ore geochemistry, bulk mineralogy, ore texture, as well as evaluating the metallurgical characteristics of ore hardness, process water geochemistry, bench-scale floatability and mineral liberation in ground feed, concentrate and tails. Developing correlations between the metallurgical response and the ore characterisation data is key to the emerging science of geometallurgy. This on-going program is a technical due diligence study that aims to reduce the risk associated with processing a new ore and to provide predictive information for mining and stockpile preparation.The test work to date has focused on characterising the five ore zones currently identified in the Aqqaluk deposit, namely: Siliceous (sub-divided to High Zn:Fe and Low Zn:Fe), Vein, Median Plate and Baritic ores. It identified a number of challenges associated with surface oxidation, or weathering, of the core samples and outlined a program for future sample collection and storage. Metallurgical testing evaluated ore hardness by a variety of methods. Preliminary floatability studies have been completed and some initial links have been established between the ore characteristics and the flotation response. Soluble mineral weathering products, the relative abundance of pyrite and marcasite and the iron content in the sphalerite grains have all shown a correlation to mineral recovery.As new core is received, both the ore characterisation and the metallurgical testing will be continued with a view to strengthen the existing correlations and develop new links."

Jan 1, 2007

By Charles Merguerian

In medium- to high-grade metamorphic terrains such as found in New York City(NYC), rock mass texture and mineralogy are important factors in predicting TBM penetration destiny. Integration of data from over two decades of traditional field and tunnel mapping suggest that hard-rock TBM penetration in the NYC area depends upon textural, mineralogic, and structural control. The bedrock of NYC consists of many different lithologic units of varying age, composition, texture, and metamorphic grade including many varieties of intrusive rock. In addition, brittle faults of numerous orientations cut the polydeformed crystalline bedrock, producing zones of highly fractured and disturbed ground and high water inflows. Pre-bid compilation of published bedrock data, drill core analysis by geologists to establish lithologic and mineralogic trends, integrated surface geologic mapping along a proposed alignment, and targeted petrographic and geotechnical investigations to characterize the rock mass conditions together constitute an important prelude to successful subsurface bidding and tunneling. A carefully planned program of as-built geological mapping, structural analysis, fracture class mapping, and monitoring of machine performance data provide important information for adjusting to changed conditions. In complex terrains, a clear understanding of the structural geology of any proposed tunnel line is the simplest and most cost-effective method to mitigate losses encountered during TBM tunneling.

Jan 1, 2005

By Jeffrey R. Hill

To extend the life of the Merchants Railroad Bridge crossing the Mississippi River in St. Louis, MO, the owner implemented a rehabilitation and reconstruction project. The Merchants Bridge provides a key link in the transcontinental railroad system. The bridge is of local importance to the Terminal Railroad Association ? providing a link between St Louis and a rail switching yard in Venice, IL. The intent of the bridge rehabilitation is to keep the Merchants Bridge in service, even though the bridge was originally constructed in the 1890?s. The project involved replacing the East and West approach deck truss spans with new deck girder spans. The rehabilitation program required construction of new concrete piers to support the new spans. In order to reduce the track down time to two, ten day single track shutdowns, the specifications required that all foundation and substructure work be completed while leaving the existing spans in place. The preliminary bridge design specified rock-socketed drilled shaft foundations. Drilled shafts proved to be challenging due to working from beneath the existing bridge, a high water table, utilities, a flood wall, and existing rail way lines. The micropile alternative was technically appropriate given the access limitations, shortened the foundation rehabilitation schedule by several weeks, and realized a significant cost savings to the Owner.

Jan 1, 2006

By Zay Jeffries

AN acute current shortage of copper, with the prospect that conditions may become worse, indicated by Office of Production Management information. Present estimates of copper requirement for defense indicate that nearly all the available metal will be required in the future for this purpose. Severe dislocations are, expected, but the objective is to distribute the copper available for civilian use in such a manner as to minimize these dislocations. The advisory committee on metals and minerals has been asked for a suggestions which may be helpful in meeting this situation.\

Jan 1, 1941

By S. H. Miller

Biodegradable hydraulic fluids can save tens or hundreds of thousands of dollars in fines and clean up costs in the event of a hydraulic fluid leak or spill. When properly selected, applied, maintained and monitored, a biodegradable fluid will have a long useful life and will protect equipment as well as or better than conventional petroleum based hydraulic fluids.

Jan 1, 2000

By F. A. Guo

Ultrafine-grained surface layers were obtained by surface mechanical attrition treatment (SMAT) in copper and titanium samples. The thermal properties of the deformed layers were characterized using a scanning thermal microscopy (SThM) that allows thermal conductivity to be mapped down to the submicrometer scale. A theoretical approach, based on this investigation, was used to calculate the heat flow from the probe tip to the sample and then estimate the thermal conductivities at different scanning positions. Experimental results and theoretical calculation demonstrate that SThM can be used as a powerful tool for the thermal property and microstructural analysis of ultrafine-grained microstructures.

Jan 1, 2006

By Arthur L. Murray

"INTRODUCTION In compliance with those provisions of the organic act establishing the Bureau. of Mines which relate to improvement of health conditions of persons engaged in the mining, preparation, or treatment of mineral substances, sanitary surveys have been made of towns and villages housing the coal miners, metal miners, and mill and smelter employees of Utah.The purpose of the surveys is to afford studies of conditions prevailing in the various mining and smelter towns so far as concerns housing, water supplies, sewage disposal, refuse disposal the handling of foodstuffs, general sanitation, wash and. change houses, and the control of preventable diseases, all of which directly or indirectly have a bearing on the health and efficiency of employees and their families. Certain other factors have been added to the general sanitary surveys such as school and recreational facilities, which have a decided influence on contentment and efficiency. Through comparisons of favorable and unfavorable conditions and practices, and the dissemination of such information, improvements can be effected which will benefit both the employees and the employers.ACKNOWLEGMENTSAcknowledgment is made of the many courtesies shown by the officials of companies and towns visited. In some instances the towns were entirely under the control of officials of mining companies, being on company property whereas, in other instances, the towns wars incorporated not under company management. Particular acknowledgment is made of the assistance given by the Utah State Board of Health through Health Commissioner Dr. T. B. Beatty."

Oct 1, 1932

By G. S. Takenaka

When Bridger Coal Company transformed their operations from surface mining to an underground longwall operation their plans included not only the addition of new mining equipment but also surface fans for a blowing (supply) air ventilation system. The original system concept included a propane gas fired air heater to preheat the intake air during cold weather and a dual parallel fan and duct system. One fan operated to ventilate the mine while the other fan was for stand-by emergency operation. Equipment proposals were submitted in March, 2005 based on the dual parallel fan system. Discussions conducted during the equipment selection process revealed that several alternative system design concepts were available. The alternative concepts included innovation features that not only saved space and cost but also reduced operating expense as well. Many of the features were incorporated into the final design of the system. A comparison of the original system concept and final installation design are presented in the paper in addition to details of the features and the derived benefits.

Jan 1, 2009

It has long been recognised that Australia can benefit substantially in an economic sense from its rich resource base. The significant resources of the Gippsland Basin are a good example of the wealth of this nation. As cited in popular debate, Australia must value-add to its natural resources to ensure its long term economic prosperity. The significant oil, gas and coal resources of the Gippsland Basin have provided the Strategic Research Foundation with the basis for two major research and development initiatives ensuring the long term economic development of the Basin and Australia. The gas and coal reserves of the Basin together with the area's extensive history in electricity generation provide the rationale for establishing Ceramic Fuel Cells Ltd. A consortium comprising Australia's leading industrialist - BHP, State energy authorities and the Nation's major research and development organisations, has formed Ceramic Fuel Cells to undertake and manage research, development and commercialisation of solid oxide (ceramic) fuel cells which convert fossil fuels directly to electricity with greater efficiency and less pollution than existing technologies. The oil and gas resources of the Basin together with the valuable experience of the operators in recovering these resources, have provided the impetus to investigate the feasibility of a Marine Engineering Research Centre. The commercially oriented research, education and training objectives of the Centre are well supported by the leading industrialists in related industries.

Jan 1, 1992

The Tertiary gold deposits of the Hauraki area are predominantly epithermal vein types containing mineral assemblages of quartz, calcite, pyrite, sphalerite, galena, chalcopyrite, acanthite and native gold (electrum). Sulphosalt, telluride (eg hessite), seleniferous sulphide and selenide minerals are important locally. Studies of wall rock alteration mineralogy, fluid inclusions in gangue minerals, and sulphur isotopes of sulphide minerals indicate that the ore forming fluids had the following parameters: pH, near neutral at depth but acidic near surface; temperature, predominantly 320 - 270¦C for base metal dominated assemblages, 280 - 200¦C for precious metal dominated assemblages and generally below 200¦C for late stage barite; apparent salinity, six to zero equivalent weight per cent NaCl; and CO2 concentration, generally around one mole per cent CO2. There is fluid inclusion evidence for boiling during mineralisation in some deposits. Moderate values off S2 and FO2 are indicated for base metal and mixed base metal û precious metal assemblages of most deposits by the predominance of pyrite + chalcopyrite over other iron-bearing phases; primary bornite is absent, whereas pyrrhotite, hematite and magnetite rarely occur in the veins. The largest gold û silver deposits formed from solutions in which the sulphur species in solution were predominantly reduced. Near surface environments and some deep, predominantly base metal, deposits were formed from solutions with approximately equal concentrations of oxidised and reduced sulphur species.

Jan 1, 1984

By Transfert Environment and Society

Transfert?s added value ? Building bridges between project promoters and communities ? Unique expertise in working toward Social License to Operate through meaningful community engagement ? 25 years of recognized innovation and a systematic approach ? Key mining clients: ? Royal Nickel Corporation ? IAMGOLD - Niobec ? Richmont Mines - Wasamac ? Mine Arnaud ? Managem

Aug 1, 2013

By N. I. Aziz, I. Tague, P. Mackenzie-Wood

The recent mine disasters in Australian coal mines have initiated an introduction of Self-Contained Self-Rescuer (SCSR) as component in the development of new escape strategies for miners. These self-contained self-rescuers are closed circuit, demand sensitive breathing apparatus that make oxygen available to the wearer for a nominal period of time. Their operation is completely independent of the surrounding atmosphere. Once properly donned, the SCSR can assist a miner to escape from an area containing smoke, toxic gases or an oxygen deficient atmosphere. The duration of a typical SCSR is usually taken at the point of complete collapse of the breathing bag which is accompanied by an increase in breathing resistance and inhaled levels of carbon dioxide. Because the oxygen consumption (V02) and the heart rate are correlated, a prediction of V02 and consequently the duration of an SCSR can be made by monitoring the heart rate. Thirty-seven volunteers participated in field simulated escape trials at four underground coal mines. The results from the field trials suggested that oxygen consumption depends on the heart rate, the body weight and exercise rating of the miner. All the volunteers were asked to fill out the questionnaires to evaluate the performance of the units. The miners indicated that they could tolerate the inhaled temperature without any difficulty to breathing resistance. A complete statistical analysis of the field results is also presented.

Feb 24, 1997