Search Documents

By David E. Nicholson

The Bureau of Mines has constructed a special compression chamber for developing stress-strain relationships of mine backfill and simulating the high compressive ground pressures encountered in underground mines. A one-dimensional, or Earth-Pressure-at-Rest model is proposed for backfills subjected to these pressures. Results of the compression tests performed in the chamber indicate that reliable stress-strain relationships can be developed from these tests. The primary objective of the test series was to evaluate the effectiveness of compaction of common backfills in retarding ground closure. Analysis of the stress-strain data shows an eightfold reduction in relative strain in optimum well-graded, compacted backfills over poorly graded, loose backfill material. Analysis of the one-dimensional compression test data also indicates a significant retardation of transmitted stress in dense compacted samples of backfill and natural sands. Although not fully understood, a deformation mechanism is thought to occur at the intergranular contacts in cyclic fashion causing frictional heat loss and a reduction in transmitted stresses in the densely packed materials. The experimental values of transmitted stress are compared with theoretical values of effective stress calculated from the one-dimensional compression relationships developed by Hendron (4).3 These experimental values of transmitted stress compare very closely with the theoretical values of effective stress.

Jan 1, 1968

By R. N. Powell

The Pipeline ore body was discovered in March 1991. The construction of the new mine and mill did not start until early March of 1996. Upon completion of permitting and corporate project approval, the 289 million USD project was “fast tracked”. The commissioning began 11 months after start of construction and the project ended 40 million USD under the budget figure. The objective of this paper is to review and highlight the Pipeline Project history from discovery, design, lawsuits, permitting, and re-design through to current - 1998operating practices. Particular emphasis will review the process design, design mistakes, and design successes. The paper will review project history, feasibility, design concepts, operator training, construction, financial and the current operation. Additional discussion will review what design features worked and which did not work within the process plant.

Jan 1, 1999

By Jilai Xue

Fe-Ni alloys can be used as raw material in making stainless steel. Laterite nickel ore is one of mineral resources for producing nickel alloys. In this work, the laterite ore after dehydration at 800 °C and the anthracite as reducing agent were mixed for pre-reduction at 900 °C, and then reduced to form Fe-Ni alloys at 1550-1620 °C through carbon-thermal reduction process. A high Ni-content alloy component in the metallurgical mixture can be formed through pre-reduction. Better separation of the resulting metals from the slag is found with lower Ni-content alloys produced or higher temperatures during reduction. An effective processing of Fe-Ni alloys needs further understanding of the process fundamentals and optimizing of the process parameters.

Jan 1, 2010

By Adam Gray, Emery Gray

State-of-the-art seismographs can be employed to assist the blasting engineer in understanding the propagation of vibration waves generated by blasting. Wave traces and frequency plots are used to adjust shot loading and timing, especially around close or near- field structures. Successful close-in blasting vibration monitoring requires careful consideration of the following: Geophone locations Mounting of geophone both on structures and in the ground Differences between ground motion and structural response This presentation will discuss methods used to control and monitor blast-induced ground and structure motions. Case histories are presented to illustrate seismic monitoring used as a tool to control vibrations and guide the blaster in the design process.

Jan 1, 2005

By Maral Papazian Bedian

Construction contracts in the USA contain the clause "Value Engineering" ? an interesting and curious clause allowing contractor initiated design changes. Misleading is the interpretation of value engineering implying cost saving and sharing with the owner, and curious is the timing, just before beginning of actual construction. It is not surprising that such a clause would simply be ignored, because it involves change, often major design changes in very short time; and change is feared, moreover, it is vehemently resisted by all parties, owner, designer, contractor. The problem in the USA may lie in the divergence and separation of the two entities: Designer/Engineer and Builder/Contractor, assigned to the "one" engineering project. The priorities and incentives of these two groups are very different. The Engineer spends years, even decades, in design and prepares contract drawings often without a deep understanding of construction methods. Worse, with all the time available to him and in our era of tremendous advances in computational methods and speed, the designer turns in plans that are inexcusably exaggerated code-based design with excessive safety factors. As to the Contractor, he builds, often without appreciation of design principles or regard for design engineers. Redesign to apply a new technology or optimization of an inferior design just before construction becomes unthinkable. It is not surprising that adverse and hostile relationship between the designer and the contractor is a norm with extended disputes and claims, not to mention the cost these entail. Surprisingly, "Value Engineering" was successfully implemented in record speed on several very large projects in the metropolitan New York area. The process of change was unconventional, painful, and even comical. Four case studies are presented: two Design/Build: the 1.2 billion dollars Hudson-Bergen Light Rail Transit System in New Jersey and the 90 million dollars MTA Bus Depot in Manhattan, and two Conventional Design/Bid/Build: the 90 million dollars Queens Boulevard Bridge and the 150 million dollars Long Island Expressway.

Jan 1, 2002

By P. M. Prasad

Off-grade molybdenite concentrates, mainly derived from secondary sources as by-products of the processing of copper, uranium and tungsten ores, do not satisfy the purity requirements (percent MoS2) for the production of molybdenum bearing products. This investigation is a continuation of a successful effort to refine a low-grade molybdenite concentrate to prepare a high-grade MoS2 using a mixed acid (HF + HCl) leach procedure. Specifically, this investigation is concerned with an understanding of the separation chemistry underlying the removal of the oxide/silicate gangue and the base-metal sulfide associations present in the low-grade molybdenite by their selective dissolution in the two acids. Experiments were conducted on an off-grade concentrate containing 42.6% Mo. Results of the controlled dissolution tests indicate that both HCl and HF are suitable for the removal of the associated alumina and both work well for iron, nickel and copper. However, HF was found to be the most effective for dissolving silica/silicate and magnesia. An attempt was made to rank the leaching efficiencies of the acids used singly, sequentially or in a mixed mode. Scale-up (300 to 2,000 g) experiments were conducted to validate this approach. Excellent purification of the concentrate was possible by processing the off-grade concentrate with 10% HCl plus 15% HF at 363 K for 7.2 ks in open polypropylene reactors with internal stirring. These conditions leached practically all of the oxide and silicate gangue and 96% of the metallic impurities. Starting from the low-grade molybdenite concentrate (42.6% Mo; 71.1% MoS2) it was found feasible to obtain a refined product containing 97.8% MoS2, which is suitable for industrial use.

Jan 1, 2007

By Michael G. Rulff, Tracy M. Holmes

"Vast amounts of time and money are spent fighting flow problems in plants that involve the handling or processing of industrial minerals. Because these types of projects tend to be capitalintensive, the right decisions, made at the design stage, can have a substantial positive effect on the economics of the project.Some of the problems related to solids flow in mineral processing plants include:•,Flow stoppages•,Uncontrolled flow•,Segregation of blended materials•,Build-up and dead material resulting in loss of live capacityUnfortunately few Universities in North America provide courses in the design or selection of bulk solids handling equipment, let alone the theory of bulk solids flow, with the result that engineers do not fully appreciate the effects of bulk solids handling on their process. The usual method of selecting “standard” equipment, all too often, leaves plant operators hammering on hoppers to promote flow, a technique that is not only usually ineffective but also unsafe and often causes damage to equipment. In short, too little consideration is given, at the design stage of projects, to the particular material and operating environment involved and how these will affect handling between process steps.This paper seeks to give a general understanding of bulk solids flow theory including flow patterns and flow property tests, and presents functional design guidelines to ensure reliable flow. As well, a case history will be presented. Our message is clear: To ensure uniform, reliable flow, a plant design must take into account the specific flow characteristics of the bulk solid to be handled or processed."

Jan 1, 2008

By Robert J. F. Goodfellow, William A. T. Meakin, Kevin Clarke, Eric Cole

INTRODUCTION New York City Water Supply—Background and History Since the 1840s New York City has been developing the largest, and perhaps, the best urban water supply and distribution system in the world in terms of quality and reliability. One of the engineering marvels of the modern world, the New York City water supply and distribution system serves a population of almost nine million, including residents in nearby Westchester, Putnam, Ulster, and Orange Counties of New York State. The average daily supplies presently are running at almost 60 m3/sec(about 1,350 million gallons per day). The watershed for the New York City water supply system, under the jurisdiction of the New York City Department of Environmental Protection (NYCDEP), consists of19 reservoirs and three controlled lakes, and covers an area of approximately5,000 square kilometers (about 2,000 square miles) north of New York City. The watershed total available storage capacity is about two billion cubic meters (560 billion gallons) and is divided into three reservoir systems: the Catskill and Delaware watersheds located West of the Hudson River; and the Croton watershed, located east of the Hudson River, see Figure 1. The first element of the system, the Croton Aqueduct, started operations in 1842.Through several updates and expansions, the present-day Croton system was in place by 1911, providing a potential maximum supply of about 15 m3/s (about 340 mgd). The system includes ten reservoirs and three controlled lakes. In the late 1800s, with the tremendous growth of the City, New York City water engineers began to look for additional sources. Between 1907 and 1929, the City acquired water rights and constructed a new 148 km (92 miles) Catskill aqueduct to convey water from the Ashokan Reservoir to the City. The Catskill system also included the construction of the Kensico and Hillview Reservoirs just north of the City,

Jan 1, 2005

By Martin H. Rogoff

This publication combines a critical review of the literature on the microbiology of coal with an introduction to those areas of microbiology related to studies of coal as a biological material. The attack on coal by microorganisms as yet remains doubtful. Only the low-rank coals contain an indigenous microbial flora, and even these organisms are not peculiar to coal, but are common soil and water forms. No experimental data have as yet been presented, either in the literature or in the present work, which unequivocally demonstrate the oxidation of coal by microorganisms. Reasons for the resistance of coal to such attack, including insolubility, physicochemical structure, steric hindrance of enzyme action, and the presence of antibiotic materials in coal are discussed. Microorganisms do attack large aromatic molecules and the mode of oxidation of aromatic ring systems by bacteria is presented. Well-defined pathways are known for the oxidation of polycyclic compounds with one to three rings, and these paths with their key intermediates are described and related to the possible oxidation of coal.

Jan 1, 1962

By H G. Bosmare, G Bedser, C V. B Cunningham

Peak Quany has achieved substantial improvements to its bottom lie by giving close attention to blasting practice, and in pr@icnlar by introducing electronic delay detonators for routine production blasting. The precision and flexibility provided by these units has enabled the quarry to gain control over fmes and curtail oversize without increasing explosive usage. In addition, the extent of nuisance from blasting vibrations has been reduced.

Jan 1, 1998

By M. J. Leeuwner

Computational fluid dynamic (CFD) modelling is used to research the complex flow structures that exist in a hydrocyclone. By simulation of a two phase (water and air) flow system, the internal flow and multiphase interactions are investigated. The suitability of CFD modelling as a design tool is further evaluated by examining the effect of varying device dimensions. Three hydrocyclone geometries, used in previous studies, are specified. A transient simulation approach, which employs the Reynolds Stress Model as turbulence model and the Volume of Fluid model as multiphase model, is followed. Results are validated qualitatively against experimental measurements from the previous studies. Keywords: CFD modelling, hydrocyclone, Reynolds stress model, multiphase flow

Jan 1, 2008

During fiscal year 1966 the Bureau of Mines published 99 scientific and technical papers and engaged in 67 research projects on petroleum, natural gas, and oil shale. A basic appropriation of $3.4 million was supplemented by $1 million in cooperative funds from other Governmental agencies and industry groups. Petroleum conservation was advanced by development of scientific knowledge and improvement of technologic methods in both the extraction and utilization of petroleum, natural gas, and oil shale. Experimental work was carried out at research centers in Bartlesville, Okla., and Laramie, Wo., and in laboratories in Morgantown, W. Va., and San Francisco, Calif. ACHIEVEMENTS IN FISCAL YEAR 1966 Bureau of Mines--Petroleum Research in fiscal year 1966 (July 1, 1965- June 30, 1966) was involved in many public issues--air pollution, peaceful uses of nuclear explosives, utilization of oil-shale resources, computerization of recovery-stimulation techniques, and fuels for supersonic airplanes. Scientific contributions included compositional studies of petroleum and oil shale, determination of thermodynamic properties of petroleum compounds, development of analytical techniques, and correlations of petroleum properties with geologic occurrence. Technologic advances included rock-fracturing research, in situ combustion studies, waterflood techniques, use of radio-tracers to study stability of petroleum fuels, and hydrogenation as a tool to prepare shale-oil products.

Jan 1, 1968

Experiments on High Efficiency Separation of Mixed Plastic Wastes by Vortex-Tube Separator

Sep 13, 2010

By C. J. A. Mcewan, C. M. Rice

The Rosita Hills contain rich, vein- and breccia pipe-hosted precious metal deposits. Volcanic activity occurred in two cycles - an early, mainly andesitic cone-building phase that terminated in the formation of a caldera and breccia pipes and a later phase characterised by trachytic lavas and dykes, rhyolite domes and lamprophyre dykes. Alteration consists of weak propylitic and argillic and, locally, intense advanced argillic, K-feldspar sericitic and silicic types. Marked trace-element depletions (Rb, Sr, Zn, Mn) are associated with K-feldspar-sericitic alteration and with advanced argillic alterations, whereas enrichments (Pb, Ag) are associated with K-feldspar-sericitic alteration. Gold distribution is highly localised and is controlled by breccia pipes and a caldera ring fault; it is not related to district scale alteration. In general, the geochemical and alteration patterns are complex, but they are clearly influenced by linear structures, the caldera ring fault and breccia pipes. Pipe-hosted Au-Ag and vein-hosted Ag mineralisation are associated, respectively, with early andesitic and late, post-caldera rhyolitic activity. The pipe-hosted and, especially, the vein-hosted mineralisation show affinities with adularia-sericite-type epithermal deposits

Jan 1, 1991

The objective in control blasting is to reduce overbreak to control the final pit wall slope, shaft, drift, ditch, bench, etc. to the final planned excavation limit.

Jan 1, 1990

By M. Nduna

Surface properties of metal sulphides have a great significance in various areas of engineering and science, such as acid mine drainage, contaminant sorption, and metal separation. In various attempts at producing metal sulphide particles from synthetic solutions, prodigious quantities of nuclei that grow only to colloidal dimensions have been frequently reported. This copious nucleation is promoted by the high levels of supersaturation that characterize most precipitation reactions. Colloidal particle formation in precipi¬tation-based separation processes results in sub-optimal solid-liquid separation, which is alleviated by the production of more highly crystalline particles or agglomerates. The current work approaches this challenge from an electrochemistry perspective, by measuring surface charge potential of precipitant particles during metal sulphide precipitation with respect to the concentration of metal sulphide lattice ions in solution. Electrophoresis was used to measure the metal sulphide particle zeta potential and the settling properties were obtained by performing settleability measurements using an Imhoff settling cone. A suspension of copper sulphide particles was precipitated from synthetic solutions of copper and sulphide ions at equimolar concentrations. Immediately after precipitation the copper sulphide particles had a zeta potential of -50 mV and a settleability of about 7 ml.l-1. With the addition of copper ions the settleability increased by a factor of nearly three times and the zeta potential also increased to a maximum of -40 mV. A decrease in zeta potential to a minimum of -60 mV was observed after the addition of sulphide ions and this was associated with a settleability of 0 ml.l-1.

Jan 1, 2013

The mechanization of the coal industry in New South Wales involved the introduction of large face and transport machines. The trend is towards still higher capacity units with .greater horsepower and it became apparent that a potential risk of damage to the hearing of workmen existed. In order to assess whether the sound levels were SUfficiently high to impair the hearing of workmen a sound level survey of all major operations in the industry was carried out by the Mining Engineering Division of the Joint Coal Board.The results indicated ·that the operations could be classified into three categories of risk, probably hazardous, of doubtful hazard due to the intermittency of the operations, and of low hazard.Legislation has subsequently been enacted requiring the wearing of hearing preservation aids in some of the probable risk operations.

Jan 1, 1974

By Yasser Mohamed

Daily field management of earthmoving operations requires quick and regular decisions for allocating available equipment to different jobs on a project. A general foreman?s day starts with matching several activities with a suitable set of available equipment to achieve the highest productivity and lowest unit cost. Usually, this decision-making process needs to be quick, and depends to a great extent on the foreman?s experience, which varies from one individual to another. Many analytical solutions with various degrees of sophistication and optimization exist to address such decisions. However, adopting any of these solutions is contingent on how accessible and easy-to-use the solution is. This paper discusses the development process of a webaccessible solution for evaluating earthmoving fleet composition and allocation scenarios. The solution relies on discrete event simulation and an optimization backend engine, but introduces the user with a simplified and easy-to-use interface that is accessible from any mobile device, and is customized to specific user?s needs. The developed system gathers most equipment and site-related input data from a company?s information systems to minimize user input. The user mainly needs to formulate equipment and job combinations and allocation scenarios (e.g. soil type, quantity, and hauling distance), according to equipment availability each day. Then the system will evaluate the productivity and unit cost estimates for each scenario, allowing the user to choose the most suitable one. It may also be used to automatically recommend the optimum solution given an available list of equipment. The paper presents the process followed in prototyping the proposed system in collaboration with a major Canadian earthmoving contractor, and customizing it to the user needs within the company. It also describes the overall structure of the developed system and its core simulation model.

Aug 1, 2013

By A Jewbali, J Phillips, C Boyle

Normal practice in the mining industry is the creation of a single geological model. These models provide a single interpretation of the geological and mineralisation domains. These interpretations infer the exact behaviour of ore domain contacts at shorter scales when resource definition drilling is done on wider scales and are thus locally highly uncertain. The interpreted geological model provides a single number for the volume and tonnes of mineralised material enclosed by the mineralisation envelope. It is on this single number for volume and tonnage that capital intensive mine development decisions (mine design and scheduling, stockpile strategy, waste management, closure planning, dewatering strategy, product quality, etc) are based. Some of these decisions require knowledge of grade variability for small volumes of material such as quarterly production periods. It is generally recognised that this information cannot be derived from single kriged geological models, but can potentially be modelled by conditional simulation techniques. Uncertainty in the extent and continuity of the mineralised envelope and its effect on grade variability for shorter production periods is thus recognised as a major source of uncertainty in new mine development.CITATION:Jewbali, A, Boyle, C and Phillips, J, 2013. Quantifying domain uncertainty for an iron ore deposit, in Proceedings Iron Ore 2013 , pp 157-168 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 12, 2013

By Chris Breeds, Ken Johnston, Omar Fulton

This paper describes the process typically involved with obtaining permits for quarry blasting in urban, suburban, and rural areas, including: content of SEPA (State Environmental Policy Act) driven documentation; regulatory review and comment; public interaction; public hearing(s); periodic regulatory review(s); negotiated solutions; monitoring; and the role of public interaction, demonstration(s), and education in the process. Case studies will be presented of projects undertaken in the State of Washington that illustrate the approach and regulatory interaction as well as the importance of public interaction throughout the process. Reference will be made to the role of national and state regulations and local codes and ordinances that provide additional limitations on blasting practice. The paper will also present regional blast monitoring data that are used in the permitting process and the layout and design of blast monitoring systems typically required as conditions of the quarrying permit. Our presentation will include tools, which we have developed to assist with explaining blast related phenomenon to both regulators and the public.

Jan 1, 2003