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By Mike Sharwood

This subject is to be discussed in greater depth by Mike Sharwood. It has also been the subject of a mini-symposium by the Melbourne Branch of the AusIMM in October, 1993. The papers from this symposium were distributed to the membership late last year "to raise their consciousness and to promote greater awareness and understanding of the wide range of liabilities that may arise". An introductory paper by Nicholson outlined the many areas in which liability may arise with particular emphasis on expert reports, eg: Takeovers Schemes of arrangement Acquisitions from associates Prospectuses Related party transactions Directors' duties Continuous disclosure Other influences (environmental, occupational health and safety, trade practices)

Jan 1, 1994

By Rodrigo Afonso Hatwig

Os aços inoxidáveis duplex (DSS) e superduplex (SDSS) são ligas que se caracterizam por apresentar uma microestrutura composta por frações volumétricas similares das fases ferrita e austenita. Dependendo da composição química e do tratamento termomecânico aplicado, a microestrutura dos aços inoxidáveis DSS e SDSS poderá apresentar, além das fases ferrita e austenita, fases intermetálicas deletérias. Neste trabalho, um estudo termodinâmico-computacional foi realizado com o objetivo de acompanhar a evolução das fases de aços superduplex no intervalo de temperaturas entre 300°C e 1.200ºC. Para tanto, fez-se uso do software de simulação termodinâmica FactSage v. 6.4. Os resultados descrevem de forma eficaz as fases principais e secundárias em função da temperatura e composição química.

Aug 8, 2018

By Rolland R. Mates

This paper describes the use of post- tensioned rock anchors to reduce the risk of future damage to a residential structure as a result of coal mine subsidence. The project described in this paper was performed by the Office of Surface Mining Reclamation and Enforcement (OSMRE) of the U. S. Department of the Interior. The OSMRE was created to administer Public Law 95-87, the Surface Mining Control and Reclamation Act of 1977. The responsibilities of OSMRE include "reclamation and restoration of land and water resources, adversely affected by past coal mining including prevention, abatement, control of coal mine subsidence. ?('l) Consequently, OSMRE has been addressing mine subsidence problems since its initial subsidence stabilization project in 1979. Stabilization activities have primarily consisted of supporting the overburden material by injecting materials through drilled bore holes into the underground mine voids. Injection of various materials into mine voids, including fly ash mixtures, coal refuse, cement grout, and gravel has proven to be a successful method of reducing mine subsidence-related surface movements, and has been extensively utilized in mitigating mine subsidence problems. However, the cost of drilling for injection can be extremely high in areas where the depth to the coal seam is great.

Jan 1, 1986

By V Kveldsvik, N Ragvin, T Eiken, G Grøneng, G V. Ganerød

Catastrophic rock slope failures have caused destructive tsunamis in Norwegian fjords. At the Åknes rock slope the tsunami generating potential is large due to the potential large volume involved in a possible catastrophic failure. Widening of the upper crack has been recorded since 1986, and in recent years, a quite extensive investigation and monitorin campaign has been conducted. Data from some of these investigations are presented and analysed with respect to a preliminary evaluation of the stability of the slope.

Jan 1, 2006

By Steven J. Page, John A. Organiscak

Airborne dust generation is one of the byproducts of coal mining, processing, and handling. The amount of airborne total dust (ATD, respirable size and larger) and airborne respirable dust (ARD) generated is of primary interest for designing the level of engineering controls needed for adequate dust abatement. Laboratory crushing experiments were conducted in a wind tunnel with a roll crusher to identify relationships among crushing parameters, product size, coal rank properties, and airborne dust generation. Through the first series of experiments, the effect of primary and secondary breakage processes on both product size and airborne dust generation was examined. Through a second series of experiments, the effect of coal rank properties on product size and airborne dust generation was studied using a uniform crushing process with secondary breakage. Laboratory results indicate that secondary breakage of a particular coal notably increases the specific amount of ATD generated, while negligibly impacting the specific amount of ARD generated. A strong positive relationship was identified between the specific amounts of ATD and ARD generated during the primary breakage process (with minimal secondary breakage), but a negligible relationship was observed between the same two variables when secondary breakage was introduced into the crushing process. This indicates that most of the ATD and ARD is generated from the primary breakage, while secondary breakage has a more of an influence on generating additional amounts of larger sized ATD. Additional experiments involving the uniform crushing of eight different bituminous coals showed that the coal rank, expressed as the inherent moist fuel ratio (MFR = fixed carbon =(volatile x inherent moisture)), had diverse relationships between the product size created and the amount of airborne dust generated. As bituminous coal rank or MFR increased, the amount of coal product fines < 250 gm increased while the mass percentage of ATD and ARD liberated from these < 250 µm product fines decreased. Air dry loss (ADL) moisture in the coal was found to be inversely related to the dust cloud electrostatic field, influencing dust liberation from the coal product fines. Since the MFR was directly related to the dust cloud electrostatic field, opposite the ADL-electrostatic field relationship, the diverse relationships between the product size created and the amount of dust liberated from the < 250 µm product fines were explained. Finally, 12 to 14 times more ATD was generated as compared to the ARD generated during these experiments. These results should provide a fundamental basis for initial estimation of the airborne dust loading requirements of engineering control methods for coal crushing.

By Alessandro Ibarra Mendonça

Embora a metalurgia do pó e o forjamento sejam técnicas totalmente consolidadas no mundo industrializado, surge o forjamento de sinterizados e o sinterforjamento para somar as vantagens de cada processo convencional em uma única técnica de processamento. O presente trabalho propõe a obtenção de uma peça denominada cruzeta, forjada utilizando billet sinterizado como matéria prima. O pó de ferro ASC 100,29 e o grafite UNICARBO 50- fino foram utilizados para obtenção do Billet , através da metalurgia do pó convencional, pressão de 600 MPa, a partir da curva de compressibilidade. Foi escolhida a cruzeta como peça alvo, devido a seu uso na indústria automotiva. A geometria da peça foi modelada em Solidworks e posteriormente realizado o projeto e construção das matrizes para o forjamento. Realizaram-se ensaios de compressão para determinar e analisar a densificação do produto, em função dos fechamentos de poros, do billet sinterizado. Ainda, foram realizados cálculos de volume para determinar a altura do billet necessária para o preenchimento da cavidade da geometria determinada. Confeccionaram-se billet sinterizados a 1150ºC em atmosfera redutora, mantido até 900°C e rapidamente transferida para uma matriz fechada de forjamento para a execução do processo de sinterforjamento a morno. Foram realizados ensaios metalográfico, de dureza e microdureza do billet sinterforjados para validação do processo. Após este processo, obteve-se peças sinterforjadas, onde analisou-se o preenchimento, ausência de dobra e trincas macroscópicas.

Aug 16, 2017

By H. A. Schnell

"The Phase I Mill at Cluff Lake in northern Saskatchewan was designed to accommodate a very specific high grade uranium ore. As this high grade ore was depleted, construction was undertaken on a new mill circuit (Phase 2) to process a more conventional lower grade ore deposit.The Phase 2 Mill expanded the ore throughput to 800 tonnes per day. The new process employs crushing, grinding, leaching, counter—current decantation, solvent extraction and magnesia yellowcake precipitation and drying to produce a yellowcake concentrate.This paper discusses the process decisions required for this expansion and outlines the new mill circuit. Included is a review of the start up in August, 1984.1.,INTRODUCTION The Cluff Lake Uranium deposit is located 720 kilometers north of Saskatoon in northern Saskatchewan. A high grade deposit was discovered in 1970 with the first production taking place in 1980 after lengthy hearings. The original mill (or Phase 1 Mill) was specifically designed to accommodate this very high grade ore for a very limited plant life.Pilot plant work was carried out in 1981 on the other lower grade ores found in the immediate Cluff Lake area. Feasibility and process selection studies were then undertaken as the Phase 1 mill was nearing its end of life. These studies were completed in March 1983 when approval was given to construct the new Phase 2 mill."

Jan 1, 1985

By Lucas Breder Teixeira

Vasos metalúrgicos podem ser revestidos com linhas de tijolos refratários, com ou sem argamassa. Devido ao grande número de interfaces entre os tijolos, o sub-sistema tijolo/junta impõe dificuldades computacionais ao projeto da montagem. Buscando comparar a influência do projeto refratário nas tensões presentes na estrutura, um revestimento com juntas secas foi modelado utilizando um material homogêneo equivalente. As propriedades termo-mecânicas deste material equivalente foram determinadas usando o método de Homogeneização Periódica e dependem tanto da temperatura quanto do estado da junta (aberta ou fechada, nas duas direções). Este modelo foi usado para simular uma Panela de Aço através do Método dos Elementos Finitos (MEF) com o intuito de demonstrar a influência dos seguintes parâmetros: presença ou ausência de juntas; espessura da junta e projeto refratário. O trabalho pretende auxiliar o desenvolvimento de projetos refratários e fornecer melhores estimativas da aplicabilidade de uma dada configuração.

Oct 30, 2017

By A. J. Nicol

Field experience in uranium has shown it is most economical to ram through a drilling program to obtain maximum footage per drill hour. Drift surveys can then determine the course of the holes. Using this method is generally cheaper than paying the additional cost involved in using the drilling technique and equipment necessary to maintain straight holes. Factors Affecting Direction of Bit Travel: In all rotary-drilled holes there is an interplay of forces or conditions affecting the direction of bit travel. Rarely is a straight vertical hole obtained. One of the major factors is weight on a drill string. In looking at a joint of drill stem it is hard to imagine its being quite flexible, but flexing of the steel increases when many joints are made up together, and even a slight weight added to the upper portion causes a buckling or spiraling effect in the hole. The result is that the bit deviates from the vertical.

Jan 1, 1959

By Giovanni Franco Sepúlveda

Dado que los procesos de planificación minera en los depósitos a cielo abierto en Colombia se realizaron a través de herramientas deterministas que excluyen la evaluación de riesgos y las incertidumbres del negocio minero, se plantea modelos alternativos de planificación minera que optimizen las condiciones de competitividad y productividad a través del uso de los algoritmos genéticos y su aplicación a los procesos de planificación minera para explotaciones a cielo abierto. Es decir, se busca realizar una aproximación al planteamiento minero estocástico desde dichos algoritmos genéticos y así mejorar la cadena productiva del proceso minero.

Mar 1, 2014

By George F. Weaton, Eugene P. Pfleider

13.4-1. History. During the past ten years the mining and production of iron ores has been through a revolution. From 1939 through 1948, which included World War II, 561,000,000 tons of iron ore was mined and shipped from Minnesota&apos;s Mesabi Range to the blast furnaces of the United States for the production of iron and steel products (20, 28, 29). The iron mining industry, anticipating the exhaustion of this highly productive source of raw material, instigated a worldwide search for new sources of iron ores. This search was highly successful, both as to quantity and quality. Venezuela (38), Canada (17, 28, 42), Peru (19, 23, 50, 52, 54, 56) Chile, (1, 66, 75), Brazil, and Liberia were among the countries where enormous deposits of high quality iron ores were discovered. The exploitation of these deposits took away the monopoly held by the Lake Superior region for so many years and created a highly competitive market for high quality natural iron ores. 13.4-2. Exploration and Development Practices. SPECIFIC TO IRON MIN- ING. American industries are motivated to continue exploration because new ore discoveries often lead to an improved competitive position with respect to raw material supply. Exploration techniques have advanced rapidly in recent years, to a degree that potentially important iron ore reserves, stratigically located, may now be detectable by application of a combination of refined and diversified geophysical exploration methods. Since the days of the dip needle, iron ore people have placed greatest reliance on the magnetometer. Its successive stages of development progressed from the balance and the torsion type to the fluxgate, and then to the "sophisticated" magnetometers-conceived and developed in th field of atomic physics. By far the greatest advancement in magnetometer prospecting was made when the self-orienting fluxgate magnetometer took to the air. This was not a new development, but it was a breakthrough in reconnaissance investi-

Jan 1, 1968

By C. A. Hartnagel, D. H. Newland

Most of the petroleum produced in New York State is obtained by flooding; that is, water drive. No important oil fields have been developed during the past 30 years, nor does there seem much hope that the productive oil areas will be substantially enlarged in the future. There is some prospect that additional supplies may be obtained by deeper drilling, but deep tests for gas to the Oriskany sandstone in some of the oil-producing areas have been without results so far as any discoveries of oil are concerned. Although the flooding method had been made legal in 1919, and some floods had been in operation previous to 1921, that year marks the beginning of a rapid increase in oil production by the new method. The flush production of oil in New York was in 1882, shortly after the discovery of the Richburg pool in Allegany County. The oil production in that year amounted to 6,685,000 bbl. The 1937 production of 5,478,000 bbl. was the largest since the flush production of 55 years ago. The effectiveness of water-flooding for increasing oil production from the old New York fields is shown in Table 1. Table 1.—Production of Oil in New York since 1921 Year Barrels Year Barrela 1921 988,000 1929 3,377,000 1922 1,000,000 1930 3,647,000 1923 1,250,000 1931 3,363,000 1924 1,440,000 1932 3,508,000 1925 1,695,000 1933 3,181,000 1926 2,242,000 1934 3,804,000 1927 2,603,000 1935 4,236,000 1928 3,377,000 1936 4,633,000 1937 5,478,000 The area of the New York oil fields is about 60,000 acres. It has been estimated that not over one-fourth of the area is being flooded. Very little of flooded territory has ceased to produce. Some leases flooded by the early, less scientific methods are being again subjected to the water

Jan 1, 1938

Jan 1, 1941

By Nancy Estrada, Jane Nowell, Cathy Jennings, Debra Yniguez, Carol Lavery, Kristin Harrer

Pilots of the MH-60S helicopter are exposed to continuous whole body vibration (WBV). Pilot fatigue is a growing operational concern due to the increased frequency of extended durations of missions (6-8+hours) in support of Operations Iraqi Freedom and Enduring Freedom. Endurance aspects of the currently used rotary wing seating systems were not optimized for the longer missions and wide range of pilot anthropometric measurements, which is now typical of naval aviation. The current seating systems were designed primarily to meet crashworthiness requirements, not for the wide range of pilot anthropometry or to mitigate WBV. Albeit, an issue, pilot fatigue and reduced mission effectiveness are also critical concerns. Current Hazard Reports indicated that pain in pilots’ legs and backs begin two to four hours into the flight and increase with time. Mission readiness also decreases with an increase in flight duration due to the constant distraction of pilots shifting in their seats while trying to get comfortable. Froom, et al [2] reported a dose-response relationship between the length of military helicopter flights and back discomfort. He also concluded that this pain is typically dull, over the lower back, and its prevalence and intensity are dependent on the total flight hours of exposure. Methods This study evaluated WBV produced in the pilot seating systems onboard the MH-60S. The purpose of the study was to test and compare the effectiveness of two different seat cushions, the current seat cushion versus an anti-vibration seat cushion. Both seat cushions were measured for acceleration levels averaged over five-minute intervals using a triaxial seat pad accelerometer. The recordings were completed for a 3-hour straight and level flight. A frequency analysis from 0-80 hertz (Hz) was conducted on all acceleration measurements to determine the dominant axis and frequency of the pilots’ vibration exposure. The results were then compared to the applicable Threshold Limit Values (TLVs) established by the American Conference of Governmental Industrial Hygienists (ACGIH) [1] and the International Organization for Standardization (ISO) 2631.1 [3] to determine the MH-60S pilots’ permissible exposure time for both seat cushions. Results The results of the study showed that for both seat cushions the vibration levels of the z-axis at 16 Hz had the shortest allowable exposure duration, according to the ACGIH TLVs. In the z-axis at 16 Hz, the MH-60S’s current seat cushion’s acceleration levels indicated an exposure time limit of approximately 6 hours, while the anti-vibration seat cushion’s acceleration levels pierced the 8-hour exposure time limit curve. This is shown in the graph below.

Jan 6, 2006

By B. R. Mohal, S. Chander

"The adsorption and wetting behavior of freshly ground and aged coals has been determined in the presence of a nonionic surfactant. The amount of surfactant adsorption changes with the concentration and ""age"" of the coal. The freshly ground coal has smaller amounts of adsorption at lower surfactant concentrations than the ""aged"" coal whereas at large surfactant concentrations, the order is reversed . In the latter case, more surfactant is adsorbed on fresh coal than on the ""aged"" coal . . It is proposed that at low concentrations, the surfactant adsorbs through both hydrophobic and hydrophilic interactions with the molecule lying parallel to the· surface, whereas at higher concentrations surface micelles form at the hydrophobic sites. The wetting behavior correlates well with the adsorption behavior.INTRODUCTIONNonionic surfactants have many applications in the coal and mineral processing industry. They can be used as dispersing agents to modulate flotation, flocculation and filtration of particulates (1). They can also be used to increase the wettability of hydrophobic solids such as coal and can hence be used as dust suppressants (2,3). Although the adsorption of representative nonionic surfactants such as Triton N-101 (an ethoxylated nonylphenol with 9.5 moles of ~thylene oxide and HLB equal to 13.4) have been studied extensively on substrates such as calcium carbonate (4), silica (5) carbon black (6) and graphite (7), very few studies are available for coals. Coals differ from other substrates with respect to two important characteristics: 1) coal are porous and 2) coals consist of a patchwork of hydrophobic and hydrophilic sites (8). Since the adsorption characteristics of a surfactant are influenced significantly by the nature of the substrate the characteristics of the coals must be taken into consideration."

Jan 1, 1989

Jan 1, 1938

Jan 1, 1938

Jan 1, 1941

By Anthony T. C. Goh, Zhiye Zhao, Laddu B. Jayasinghe, Hongyuan Zhou, Yilin Gui

"Ground vibrations from blasting are undesirable and they are very short in duration with high principal frequencies and high amplitude. Structural response to that kind of excitations may differ significantly from that generated by lower-frequency earthquake vibrations. In practice, the damage to nearby structures to generated ground vibrations has been controlled by various codes and regulations available. However, the existing vibrations limits are not always applicable, as they depend on the geological conditions of the site and the dynamic characteristics of the structure. This paper investigated the influence of the rock-soil interface on the response of pile foundation to ground-borne vibration from rock blasting, through numerical simulations using finite element software LS-DYNA. It is found that the slope of the rock-soil interface greatly influences the location of damage and the extent of damage on the pile. The bottom of the pile is subjected to a larger blast pressure and stresses are highly concentrated at the pile bottom. Thus, the pile bottom can fail in shear before it reaches its plastic moment capacity.INTRODUCTIONDrilling and blasting is the widely accepted method to large-scale rock breaking activities in civil engineering constructions due to its cost effectiveness, higher efficiency and ability to break hard rock. However, ground vibrations from blasting are undesirable and it can cause damage to nearby structures. In practice, the damage to nearby structures to generated ground vibrations has been controlled by various codes and regulations available. The existing vibration limits are not always applicable, as they depend on the geological conditions of the site and dynamic characteristics of the structure.Pile foundations are commonly used as foundations of high-rise buildings and bridges to transfer the heavy loads from the superstructure above through weak compressible soil strata into deeper, competent soil layers which have adequate capacity to carry these loads. In engineering practice, many piles are normally designed to carry mainly vertical loads and very little lateral loads, as typically the vertical loads (the gravity) are significantly larger than the horizontal loads such as wind loading. However, in recent years, there have been a number of reported case studies of translational soil movements that have induced stresses and bending moments that have damaged pile foundations and in some cases resulted in collapse of the superstructure. Typical lateral load include nearby construction activities such as an excavation for a basement or slope, the construction of a road embankment or a tunnel, as well as earthquakes (Abdoun 1997; Goh et al. 1997; 2003; Chen et al. 1999; Dobry et al. 2003; Boulanger et al. 2007; Black et al. 2007)."

Jan 1, 1900

By C. W. Chao, M. Melashvili, F. Hilário

The processing of a bulk concentrate containing copper as chalcocite, enargite, bornite and chalcopyrite along with pyrite and precious metals of silver and gold was studied. A leaching study was undertaken to examine the application of the atmospheric acid leaching process to a bulk copper concentrate for copper recovery followed by cyanidation or thiosulfate leaching for gold and silver recovery. The extraction of copper exceeded 90% under some conditions and the recovery of gold and silver reached a maximum of 44 and 45%, respectively. A sample of bulk concentrate was roasted in air to oxidize the sulfides with release of sulfur dioxide followed by acid leaching of the roaster calcine and cyanidation of the acid leach solution. The copper extraction reached over 92% and the gold extraction exceeded 88%. The sulfur dioxide may be captured for acid production. INTRODUCTION The processing of a large primary copper deposit in Indonesia is under investigation. One of the possible routes for processing involves flotation of a bulk copper-gold concentrate followed by treatment by an atmospheric leach/SX-EW process for copper recovery. The atmospheric leach residue would then be leached for recovery of gold and silver. A second route involves roasting of the concentrate followed by acid leaching and SX-EW for copper recovery. The leach residue from the roaster calcine would then be leached for recovery of gold and silver. The roaster off-gases could be used for sulfuric acid manufacture, enabling the production of a valuable by-product. The Cobre Las Cruces (CLC) process (Munoz, Garcia, & Delgado, 2017) was designed to treat a resource of copper discovered close to Seville, Spain. The process was developed by Outotec with MK Gold (original project owner). INMET Mining subsequently purchased the deposit from MK Gold and built the copper processing facility. The CLC process is similar to the Mt. Gordon Copper process; except that OKTOP reactors have been installed instead of a low temperature, low pressure autoclave process. The plant was designed to treat 1.3 mtpa of ore at a grade of 6.2% Cu to produce 72,000 tpa of cathode copper over a 15 year project life. The main gangue mineral at Cobre Las Cruces was pyrite. The Cobre Las Cruces ore is therefore similar to a rougher flotation concentrate containing copper minerals and pyrite. The roasting of a rougher flotation concentrate can be designed to produce hematite, basic copper oxides and sulfur dioxide off gas. The acid leaching of the basic copper oxides may produce soluble copper for SX-EW recovery of copper. The sulfur dioxide off-gas may be used to make sulfuric acid.

Jan 1, 2019