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By A. Zhecheva

A commercial titanium alloy Ti-6Al-2Sn-4Zr-2Mo has been gas nitrided in this work, in pure nitrogen atmosphere in order to improve its surface properties. The nitriding was performed at two different temperatures, 950 and 1050°C, and for different periods of time. The influence of the initial surface roughness on the diffusion process and on the surface properties of this material was studied. The influence of the processing parameters of gas nitriding on the surface roughness, phase modifications and the microstructure of the nitrided layers has been analyzed using atomic force microscopy (AFM), X-ray diffraction and optical microscopy. Microhardness profiles were obtained on cross-sections of the samples after gas nitriding applying a Knoop indenter.

Jan 1, 2004

By M. G. Zabetakis

The use of liquid hydrogen as a high-energy fuel introduces numerous hazards not ordinarily associated with the use of other more conventional fuels. These hazards are attributable to the unique properties of hydrogen in the liquid and gas states (table 1). Since little work has been conducted on explosion and related hazards of cryogenic fuels, a research program was undertaken to obtain basic data on such dangers for hydrogen and other combustibles under these conditions. These data were used to outline emergency procedures for protecting personnel and equipment when an accidental spillage of liquid hydrogen occurs and to establish a quantity-distance table for the storage of this fuel. The vaporization of liquid hydrogen from a surface is treated as a prob¬lem in heat transfer theory. Two extreme cases are briefly considered: (1) The transfer of heat occurs at constant temperature drop between, the boiling liquid and the hot surface, and (2) the transfer of heat is limited by the rate at which it can flow to the surface from a hot insulating medium. The available data indicate that the former case (1) is applicable when vaporizing from a conducting surface and, initially, when vaporizing from an insulating medium; the latter case (2) is applicable after initial flash vaporization has occurred from the insulating medium. The vaporization rate determines in part the rate at which flammable hydrogen vapor-air mixtures are formed above a spill area. However, the rates at which heat is transferred to the vapor, and air is brought in contact with it also are of importance. Accordingly, the distribution of flammable mixtures above a spill area was determined experimentally. In general, flammable mixtures were found to be both above and within the visible vapor cloud.

Jan 1, 1961

By G. D. Garland

The influence of natural electric currents, induced in the earth by changes in the earth's magnetic field, on the electric logging of boreholes has not always been recognized. Measurements made with fixed electrodes of changes in the vertical potential gradient in a hole near Calmar, Alberta, have indicated the effect of earth currents related to magnetic disturbances. It is found that appreciable errors in self-potential logging could arise during periods of magnetic storms, but the precise pat-tern of disturbance in any area seems to depend on the local structural conditions. As the amplitude of the natural earth currents increases toward the auroral zone, it is suggested that periods of magnetic disturbance be avoided, if possible, when electric logs are taken in the northern part of the western sedimentary basin. NATURAL electrical currents flow continuously near the surface of the earth, apparently as a result of electromagnetic induction

Jan 1, 1962

By Roy G. Mead

BECAUSE of its magnitude, and the type of occurrence, the deposit of boron minerals in the Kramer district, Kern County, California, is unlike any other in the world. Discovery of this vast deposit has brought about many changes in the borax industry, so a discussion of the geology, and the occurrence, would not be complete without a brief history of the development of the borax industry. Until the discovery of boron minerals in the desert regions of California and Nevada some seventy years ago, borax was imported from Tibet and India, principally for medicinal purposes, at almost prohibitive prices. Following the discovery of commercial deposits of boron minerals in California and Nevada, and the subsequent development of new uses for borax and boric acid, the consumption has steadily increased until today borax is used in some form or other in every household.

Jan 1, 1933

By Donald P. Moore

During April 1967 a Frasch sulfur mine was placed in operation near Fort Stockton, Pecos County, in West Texas. This was the first Frasch mine to recover native sulfur from a deposit not associated with the caprock of a salt dome. Since 1967 two additional mines have been opened in west Texas, another one near the first at Fort Stockton and a third one near Orla in Culberson County (Figure 2). Recoverable reserves at the Culberson County mine are estimated to be 57,000,000 long tons of native sulfur (Zimmerman and Thomas, 1969). Total recoverable reserves at the three mines probably exceed 60,000,000 long tons, Studies of the geochemical cycle of native sulfur mineralization in test Texas indicate an origin similar to the deposits on salt domes although the geologic framework is different. A comparison of the geologic setting of the west Texas deposits with the deposits in the Union of Soviet Socialist Republics as reported in the literature, reveals many similarities. ACKNOWLEDGEMENTS The writer wishes to express his appreciation to Cities Service Minerals Corporation for support throughout this study. Special thanks are due Dr. Chris Riecken and Mr. Dave Hardy for their

Jan 1, 1971

By G Britton, P Moynagh

As more than a few mines gradually sink under the weight of emails, whiteboards, notice boards and ever more complex spreadsheets, the holy grail of effective short-term interval planning and control in underground mines is as far away as ever. Despite the mining industry investing ever greater amounts in planning and Enterprise Resource Planning systems, short-term plans become ever more complex and rigid. What the industry desperately needs are not more ‘disembodied voices down the speaking tubes’, but flexible and effective planning systems that encourage people to make reasonable commitments to each other so that everyone can work as a coordinated team to complete the work required each shift.One solution to the challenge has emerged. This paper describes the ‘Fewzion’ shift planning and short interval control system which has been developed at Anglo American’s Moranbah North and Glencore’s Oaky Creek coalmines in Central Queensland. Fewzion has drawn on management theory embodied in Management Operating Systems, Lean and Theory of Constraints approaches to continuous improvement to play a key role in both mines achieving record breaking tonnages.In addition to explaining the Fewzion approach, a case study is presented describing how Anglo American’s Moranbah North improved production by 39 per cent in 2014/2015 and won ‘Coalmine of the Year’ two out of the last four years and how Glencore’s Oaky Creek sustainably improved monthly development meters by 34 per cent within two months of implementing Fewzion.CITATION:Moynagh, P and Britton, G, 2017. How a frontline planning and commitment system improves trust, commitment and results in operations, in Proceedings 13th AusIMM Underground Operators’ Conference 2017, pp 235–240 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 16, 2017

By J. A. Marts

Reservoir properties including porosity and permeability distributions in longwall coal mine gobs have direct application to modeling the flow patterns and gas distributions in the gobs. Proper assessment of these distributions is required to assess gob gas hazards such as spontaneous combustion and explosive methane mixtures and to optimize gob gas venthole operation and nitrogen inertization. Determining the reservoir properties is difficult given that the gob is inaccessible and direct measurements cannot be easily taken. Several techniques have been used by previous researchers and will be discussed. This paper will present the methodology used to model the gob compaction by simulating the sequential extraction of coal. Two Western US coal mines were used for case studies. By determining volumetric strain, the porosity and permeability distributions in the gob can be calculated. The geo-mechanical model predicts an axisymmetric volumetric strain distribution with a steeper slope near the start-up room and a shallower slope near the active face.

Feb 23, 2014

By E Wargem

The conventional method of underground mining involves a process known as drilling and blasting to excavate valuable ore bearing minerals through the load and haul process. Drilling and blasting processes are completed for both the development of the tunnels used to access the orebody and for mining out the orebody itself. The former being called development drilling and blasting, and the latter production drilling and blasting. In either development or production drilling and blasting, the effective recovery will be largely reliant on the extraction of the initial void created in each blast cycle. In development tunnelling, the initial void is commonly known as a Burn Cut. The initial void created in production drilling and blasting has many names such as a Slot, Winze, Rise or Raise. There are drill patterns and charge designs used to create these initial voids in the production cycle. This paper discusses common slot or winze designs for production drilling and blasting; and various critical design criteria for these. The document also aims to provide a process for completing desktop reviews of current patterns employed on-sites and provides an initial guide in a process for improving the recovery of a slot, winze, rise or raise in underground mines.

Mar 29, 2023

By D Horacek, I K. Sheppard

Ok Tedi is in a period of transition. By 2008 mill feed will consist of higher levels of high-grade but metallurgically challenging skarn ores. Additionally, the Taranaki pit will start production in 2008 along with the start-up of a new pyrite concentrator. Taranaki ores are very high in sulfur. Sulfur is captured in a pyrite concentrate prior to tailing entering the Ok Tedi River. These and other complex scheduling issues will need to be resolved over a critical three-year period. With these requirements in mind, Ok Tedi contracted AMC Consultants to develop a custom version of the Life of Business Optimisation System (LOBOS¬) to assist medium-term production scheduling at Ok Tedi. LOBOS utilities enable Ok Tedi planning engineers to:import polygon-based reserve data (Blast Masters) from MineSightÆs Interactive Planning Tools (IP Tools); graphically construct block sequencing and material flow constraints; edit constraints defining standard scheduling, processing and financial relationships; define dump and stockpile attributes; and assign capacities to production systems, plants, dumps and stockpiles. LOBOS converts Ok TediÆs production scenario into a mixed integer program (MIP) and submits the resulting model to IlogÆs Cplex MIP Solver. The Solver seeks an optimal production schedule that maximises net revenue per mill hour while meeting all constraints. This paper introduces Ok Tedi and its production requirements and relates these requirements to the facilities developed for an Ok Tedi version of LOBOS.

Jan 1, 2007

By D. L. Whiting

Dump leaching and ,in-situ solution mining have received considerable attention during the past few years due to their apparent economic viability and minimal environmental impact. Solution mining actually dates back to the 17th century when leaching of copper ore was first reported. However-, modern day leaching didn't begin on a wide scale until the mid-1900's. In-situ mining for copper, nickel, salts, and oil shale is currently looking more attractive as the technology advances. Presently, about 15 percent of the copper production in the United States is from leaching operations at approximately 14 active sites, the largest of which are the waste dumps near the Bingham Copper Mine, Utah. To establish a common background, the discussion is centered around state-of-the-art conditions. For dump leaching, complications inherent to the physical conditions and chemical reactions such as channeling, porosity and permeability, sorption, air flow, rock alteration and pH control are discussed. Emphasis is made on those conditions which render solution recovery rates and solution mineral concentrations unpredictable. By illustrating typical and actual field conditions, the generally accepted flow theories for both dump leaching and in-situ solution mining, including rubblization, are presented. For in-situ mining, hydrogeologic techniques such as geophysical well logging, aquifer testing and digital computer modeling are also discussed. The importance of artificial fracturing and well stimulating to solution injection and recovery is made with regard to project development. Finally, the subject of water pollution control techniques and the potential impact of the

Jan 1, 1977

By B. P. von der Heyden, P. Neethling, M. Tadieb, L. Babedi

The effects of trace element substitutions in sphalerite mineral structure on optimised floatation response have, as yet, not been fully constrained or fully understood. To further this important field of study, this contribution focusses specifically on mineral and surface chemistry, and electro-chemistry of Cd- and Co- substituted synthetic sphalerites using Raman spectroscopy and Zeta potential experimentation. Raman spectroscopy illustrates that the presence of these impurities results in the introduction of a new mode, the relative intensity of which can be correlated (Cd r2=0.95 and Co r2= 0.99) to the dopant concentration. Comparison to X-ray Diffraction results measuring the unit cell parameter further shows that this relative intensity (Cd r2=0.81 and Co r2= 0.99) may provide insights into the degree of lattice strain within the mineral structure. The zeta potential distribution of an un-activated Cd-sphalerite show no detrimental effect as function of Cd content. Although the iso-electric point shifted from 2.45 at 1 wt.% Cd to 2.69 at 3.68 wt.% Cd, the zeta potential remained negative at alkaline media. Conversely, cobalt at low concentration of 0.36 wt.% had a detrimental effect on the surface charge, resulting to a close to neutral zeta potential at different pH. The adsorption of Cu ions on the surface of Co-bearing sphalerite conditioned in an alkaline media slightly increases the zeta potential of Co-sphalerite. While the Cd-bearing sphalerite decrease in negative zeta potential at >1 wt.% Cd indicating a complete exchange between Cu and Zn. The results presented herein illustrate that, based on the chemical nature of the substituting metal; sphalerite will exhibit multiple response to flotation reagents. Maximum recovery of zinc can thus only be achieved through multidisciplinary study and fundamental understanding of the effects of cation substitution on mineral structure and surface chemistry, the latter necessarily affecting the floatation response.

Jan 1, 2018

By J. C. Allan

THE purpose of this paper is to outline the pogress made in the development o the gravity separation method o ore dressing known as Sink-and-Float, which, in the opinion of the writers, has now reached a stage justifying the claim that this new method marks a highly important advance in the technique . The essential feature of the newest development of this process is the extremely accurate separation achieved. This is responsible for higher extraction in the sink-and-float unit on coarse sizes and, in consequence, for substantially higher overall recoveries. Whilst this is the most remarkable feature of the new process, it has further important contributions to make to ore dressing under the following heads: (1) The introduction of the sink-and-float separator as a buffer helps to iron-out irregularities in the mill feed. By supplying a concentrate of constant grade to the flotation section, the process also indirectly improves overall recovery. (2) The addition of a sink-and-float unit to an existing mill results in substantial increase in capacity at low per ton capital cost. (3) Where the plant can be installed underground for the pre-treatment of low-grade ores, there is a saving in hoisting costs, and excellent 'fill' is provided near the point of use. ( 4) Low-grade mixed oxide-sulphide copper ores may be pre-concentrated, thereby producing a flotation feed sufficiently rich to render the oxide residue from such flotation economic for subsequent treatment by leaching or other methods. (5) Application of the process eliminates hard gangue constituents which cause high grinding costs, or gangue constituents which adversely affect flotation. The plant is compact and easily controlled. No highly skilled operators or expensive reagents are required, and the labour and power per ton are low. The separator is extremely flexible, working equally efficiently on any throughput up to its maximum capacity.

Jan 1, 1940

By D. Norval, J. J. Dunkley

The process of atomisation is introduced and related to granulation. Some processes applicable to ferroalloys are discussed, along with their limitations and advantages. Examples of applications of atomisation to the processing of ferroalloys, including ferrosilicon and ferromanganese for use in the welding industry and as injectable additions to steel or cast iron are also presented. The economics of the process and the impact of process scale are discussed, along with criteria for process selection and system design.

Jan 1, 2004

By A Bossilkov

Although environmental and sustainable development reporting has now become widespread in the Australian mining and minerals processing sector, there remains a great deal of diversity in reporting contents and practice. Moreover concerns remain about the effectiveness of reporting for delivering the companyÆs business case for sustainable development as well as for communicating sustainable development performance to a range of external stakeholders. This paper therefore reviews the status of sustainable development reporting in the Australian minerals processing industry. Pertinent international and national developments are briefly captured, leading to a discussion of the framework for integrating sustainable development reporting with sustainable development management (as proposed by the World Business Council for Sustainable Development). This leads to a discussion of the results of a comparative review of sustainable development reports of a cross-section of eight Australian resource companies. Best practice elements are highlighted in regard to reporting on company context, governance, performance and assurance.

Jan 1, 2004

By David W. Tongue

This report describes the engineering work leading to the design of an underground coal mine piping system to transport approximately 2,000,000 cubic feet per day of methane gas to the surface from degasification holes drilled horizontally into the coalbed in existing coal mines. Safety instrumentation for detection of gas leaks and provisions for automatic emergency shutdown are included in the design. It also includes specifications for a safe system of handling gas, water, and drill cuttings during drilling of the horizontal holes and recommendations for compressor and metering facilities at the surface. The main pipeline is recommended to be constructed of polyethylene plastic pipe joined by a butt fusion method while lateral lines and separator and meter piping at the horizontal holes are recommended to be screwed steel piping. The materials used are to be resistant to the forces of impact exerted by falling rock. The pipelines are to be suspended from the ceiling with pipe hangers. All steel components are protected from chemical corrosion by applying protective coatings and the vertical casing to the surface is protected from electrolytic corrosion by a rectifier station. Methane gas detectors monitor the mine atmosphere to detect the presence of gas leaks and a pneumatic plastic tubing line provides for control of the safety shutdown system. Both the recommended design and the required construction procedures are in compliance with the applicable Federal codes for coal mine safety.

Jan 1, 2012

By ALEC CROWELL

Mississippi has had oil production for only the past six years and natural gas production of minor magnitude since' 1926. The search for oil and gas commenced in 1903 and 1496 wells had been drilled in search of oil and gas up to Jan. 1, 1946. As the year 1945 ended, 659 wells were producing oil and gas from 23 separate reservoirs. The production for the year was 8,353,719,000 standard cubic feet of natural gas measured on a pressure base of 15.025 lb. per sq. in. abs., 15.316,009 bbl. of oil¬field water and 19,093,766 bbl. of crude oil and condensate. Production for the year 1944 was 2,636,067,000 standard cubic feet of gas, 14,979,793 bbl. of salt water and 16,420,346 bbl. of crude oil and condensate.

Jan 1, 1946

By M. Bustin, A. Hosseinian, G. Preisig

Hydraulic fracturing and hydraulic shearing techniques are essential for the development of unconventional oil & gas and geothermal resources. Such techniques will also play a key role in the development of CO2 sequestration, and management of high stresses encountered with deep mining. However, the optimal design of hydraulic injections is often limited by continuum treatments of the rock mass without consideration of the influence of the natural fractures present. These may interact with the hydraulic fracture to promote offsets or arrest, or may cause the natural fractures to undergo shear and dilation. Given the limited access to the rock afforded by deep boreholes common to oil & gas and geothermal projects, advanced numerical modeling is critical for understanding key mechanisms and interactions. In this work, we first present a coupled hydromechanical distinct-element model focusing on the propagation of a hydraulic fracture. Normal and shear displacements arising from the generated hydraulic fractures are subsequently integrated into a fracture flow model for detailed analysis of specific flow behaviour and fracture permeability. For this, a scanned 3-D profile of a natural fracture is used to correlate surface roughness to dilation as a function of shearing. Fracture flow is computed at different time steps corresponding to different fracture propagation states and geometries. Modeling results indicate that the opening of a tensile hydraulic fracture is accompanied by millimetre-scale shear displacements associated with slip and wedging between adjacent blocks. This may leads to a mismatch between the upper and lower walls of the fracture if asperities are irregular and strong enough. However, fluid-induced tensile fractures have low Joint Roughness Coefficients (JRC), and associated millimetre-scale shear displacements are too small to ensure a significant offset of asperities that prevent a fully-elastic closure when the hydraulic fracture is depressurized. Injection of proppant is thus critical to keeping hydraulic fracture apertures open. Future work is planned that will see the models calibrated against field data including microseismic event locations, magnitudes and source mechanisms, tiltmeter deformations, stress change, and pore pressures.

Jan 1, 2015

By Henri Carrat

La Geoquímica es una ciencia que estudia la abundancia, la distribución y la migración de elementos químicos en la litósfera, hidrósfera y atmósfera. En ese sentido, el presente texto refiere los métodos utilizados en la prospección geoquímica, así como los procesos que implica. También se muestran los fenómenos desarrollados (dispersiones), métodos, el caso particular del uranio y la prospección química realizada en el C..E. A.

Jan 1, 1963

By Dan Brown

Improvements in construction equipment and techniques in recent years have made possible the use of drilled shaft foundations in diameters and lengths not previously considered practical or feasible. Many highway bridge and other structures are now routinely founded on drilled shafts which -are 8 to 12 feet in diameter and extending over 200 feet in depth below grade. There are unique challenges associated with constructing such large and deep cast-In-place foundations and engineers should be aware of the special needs associated with site investigation, construction specifications, material requirements, and quality assurance. This paper outlines a number of special considerations for these foundations, along with strategies that may be employed to improve the reliability and quality of large drilled shaft foundations.

May 11, 2007

By M. Bryson, G. Marap, M. Ntlhane, M. D. Hlahane

This study investigated flotation of phosphate from a low-medium grade 8-12% P2O5, 65-73% SiO2 sedimentary phosphate ore from Kropz Elandsfontein (herein referred to as Elandsfontein) in South Africa. Quantitative evaluation of minerals by scanning electron microscopy (QEMSCAN) was used to determine apatite grain size distribution, liberation and mineral association in the F2 horizon sample. The mineralogy indicated that apatite was liberated and for the Elandsfontein plant to operate at the design throughput, the flotation feed has to be milled to a coarse grind ranging between 300 μm and 425 μm. Reverse flotation process routes using varying reagent dosages, and flotation feed top sizes that could possibly yield a final product of 31% P2O5,10% SiO2 at a reasonable +70% P2O5 recovery were investigated. Based on the results, a split circuit of coarse (-300+212μm) flotation and fine (-212+20μm) flotation, was mostly preferred as compared to treating the whole ore. A final combined concentrate of 31% P2O5 and 10% SiO2 with P2O5 recovery of 84% could be produced from the reverse split circuit. The robustness of reverse flotation for both coarse and fine fractions was further investigated. Reverse flotation of the fines fraction was found to be robust and produced a final product of 31% P2O5. It was however more challenging to achieve the required product grade and recoveries on the coarser fraction (-425+212μm), suggesting that reverse circuit was not adequately robust at fractions coarser than 300μm. Keywords: Phosphate, sedimentary, reverse flotation, particle size

Jan 1, 2020