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By A. McLean, M. Iwase, K. Wakimoto, K. Katogi, Y. Kikuchi

One of the greatest obstacles to the application of physical chemistry principles to the elucidation of slag-metal reactions is a lack of knowledge of activities of the reacting species. To a large extent, oxygen potential of the slag phase governs iron and steelmaking practice. Without oxygen control by means of appropriate sensors, the behaviour of the other elements cannot be managed. In this paper, measurements of the FeO activity with various types of electrochemical FeO sensors will be described together with examples of their applications for improved strategies toward better practice for ladle metallurgy and sulphur and manganese distributions between slag and metal phases during steelmaking. Measurements of FeO activity have also been made in order to improve dephosphorization reactions. This type of work has led to significant reduction in volume of slag generated within the steelmaking vessel, which in turn has important implications for refractory wear, metal yield, alloy recovery and improved productivity. Finally, an on-line sensor is described that permits the oxygen potential to be determined for both the metal phase and the slag phase during steelmaking in the BOF.

Jan 1, 2004

By Jim Owens

The methodology of quarrying changed significantly in the Indiana limestone industry in the 60 years between Sept. 11, 1941 and Sept. 11, 2001. The former was the date of the Pentagon groundbreaking ceremony, while the latter was when the building was damaged by American Airlines Flight 77. So too, though to a lesser degree, did the machinery and methods used to fabricate the stone. The rededication ceremony on Sept. 11, 2002 marked the end of the Phoenix Project, as the rebuilding effort was named. The story of this remarkable project illustrates what the American construction(and Indiana limestone) industry can accomplish when working toward a common goal.

Jan 1, 2005

By Geoffrey Fosbrook, Donald Phillips, Anil Parikh

The Second Avenue Subway is a $16.8 billion project planned by the Metropolitan Transportation Authority (MTA) in New York City. It will reduce overcrowding and delays on the Lexington Avenue Line, improving travel for both city and suburban commuters, and improving access to mass transit for residents of the East Side of Manhattan. The project is a new, two-track, 13.5 km (8.5 mile) subway extending from Lexington Avenue at 125th Street in Harlem on the north end of Manhattan, to Water Street at Hanover Square in Lower Manhattan. The first phase of construction includes rock tunnels from 92nd Street to 62nd Street and connection to the existing 63rd Street station, three new stations, and track and systems from 105th Street to 63rd Street, allowing service between 96th Street and Brooklyn via an existing Broadway Line. The following describes the Project in detail, discusses the construction challenges addressed in the design, and the initial design/build contract to be awarded in 2005. A discussion of the planned mined construction of two rock caverns and a cut-and-cover station construction are also included.

Jan 1, 2005

By Guthrie. R. K., H. B. Hill

"INTRODUCTION During the early 1920's world-wide attention was attracted to a group of oil fields (Mexia, Wortham, Currie, Richard, and Powell) later known as Mexia-Powell fault-line fields in Limestone, Freestonne, and Navarro Counties, Tex. Enormous yields of high-gravity oil from the wells in these fields resulted in drilling campaigns that quickly surpassed all previous records for rapid, intensive development of productive areas. The discovery of oil in the Mexia filed in September 1921 was followed quickly by the finding of oil in the Currie field in October. In January 1923 oil was discovered in the Powell field; in February 1924 the Richland field, midway between Currie and Powell fields, was brought in; and in November 1924 oil was discovered in the Wortham field, situated between Mexia and Currie fields. Each of the fileds was developed rapidly: wells were spaced closely and had high initial production; production peaks were reached early in the producing lives of the fields; subsequent decline was rapid, and there was early and rapid encroachment of edge water.In 1927 Bureau of Mines engineers, in their investigations a engineering conditions in oil,completed a preliminary study and published a mimeographed report 4/ on underground conditions in the Wortham field, and in 1928 they reported on production and development problems in the Powell Field. 5/ field."

Aug 1, 1943

By D. F. Malan

In deep level hard rock mining the rheological behaviour of the rock is important as time-dependent aseismic processes can lead to a stable dissipation of energy thus reducing violent outbursts. Underground closure measurements, observations of time-dependent fracture formation and siesmic data indicate that the rock in deep South African gold mines shows significant time-dependent behaviour. The objective of this work is to quantify the time-dependent rock behaviour for laboratory specimens and underground conditions. Laboratory experiments indicated that lava and quartzite specimens undergo measurable creep strain at stress magnitudes below the failure stress. Quartzite is however prone to more significant creep at lower stress levels. A viscoelastic analysis showed that laboratory creep results can not fully explain the behaviour observed underground. The in situ behaviour is governed mainly by the rheological behaviour of the fracture zone and the resulting time-dependent formation of new fractures. A viscoplastic discontinuity model implemented in a boundary element program is used to simulate this behaviour.

Jan 1, 1997

By Daniel Mageau

Ground freezing has been used for over 100 years to provide shoring and ground water cutoffs for hundreds of projects worldwide, including drilled shafts, tunnels and cofferdams. Typically, these cases involved difficult soil/water problems where ground freezing was likely the only solution. This paper discusses a recent ground freezing project where a frozen soil wall was used for a more conventional problem. A 4-foot-thick frozen soil wall was used to provide shoring and groundwater cutoff for a 20-foot-deep excavation during construction of a cast-in-place concrete storm water detention vault. The site is located along the northbound on-ramp to I405 from westbound SR522 in Woodinville, Washington. The frozen soil wall was successfully formed in soils consisting of till fill over soft organic silt and loose saturated sand in about 3 weeks. The depth to ground water varied from about 4 to 8 feet over the site. The unfrozen soil inside the frozen soil wall was excavated vertically to the frozen soil boundary. The vertical excavation remained open for approximately 2 months with no dewatering required. On one side, fully-loaded dump trucks and other construction equipment operated within 6 feet of the wall face with zero wall movement. This paper addresses the construction issues related to installation and operation of ground freezing shoring. The overall wall performance of the frozen soil wall as well as basic geotechnical design issues are also discussed.

Jan 1, 1998

By Frank Sames

The control of the environmental effects, especially blast vibration and airblast, has become a dominating planning criterion for most surface blasting operations. Compliance with existing regulations is generally achieved through constraints in the blast design, or monitoring programs. Commonly, blast vibration and airblast signals are rated and compared only by their maximum amplitude and the principal frequency associated with the peak.

Jan 1, 1997

By Zhao-cheng Liu

Iron oxide red pigment powders of high quality were synthesized from pyrite cinders. Iron ox-ide red pigment powders were synthesized by hydrothermal method from the precursor of Fe(OH)3 and Fe(OH)2 colloid, which were obtained after ammonia solution reacted with acidic leaching solution produced by the reaction of pyrite cinders with sulfuric acid. Effects of reaction concentration, reaction temperature, reaction time, pH value and n(Fe2+)/n(Fe3+) on main properties of oxide iron red were studied by experiments. The prepared particles were characterized by means of X-ray diffraction (XRD) and scanning electron microscope(SEM). The results revealed that the synthesized iron oxide red particles were _-Fe2O3 and pseudocubic with particle size of 0.50~0.75µm. Furthermore, the quality of iron oxide red pigment powders reached the first grade of national standard (GB1863-89 ).

Jan 1, 2009

Barrick Gold plans to have four new gold mines in production by 2006. Together, the mines would increase the company’s output by 40 percent. The projects include Veladero in Argentina, Alto Chicama in Peru, Cowal in Australia and Tulawaka in Tanzania. All of them are scheduled to begin production between the first quarter of 2005 and the first quarter of 2006. They are expected to drive Barrick Gold’s growth profile to a target of 211.5 to 217.7 t (6.8 million to 7 mil-lion oz) of gold production in 2007. The company’s projected output for 2004 is 152.4 to 155.5 t (4.9 million to 5million oz) in 2004. Overall, higher production and lower costs are expected in the early years from the new mines.

Jan 1, 2004

By Ware AR, Doyle BJ, Hoogvliet H

The Ladolam deposit lies within the altered volcanic rocks of the caldera floor, part of which now forms Luise Harbour. It was discovered in 1982 in the course of a reconnaissance drainage sediment sampling programme. This was designed to follow up indications of surface hydrothermal activity noted by Government geologists during an earlier survey of the Tabar-Feni island chain. Diamond drilling began in September 1983 and by the end of 1989 a payable and proved mineable reserve containing 19 million ounces of gold had been established. Rock types and structures are masked at the surface by intense alteration and weathering. An extensive drilling programme has enabled the identification of these features and the relationships between them necessary for an understanding of the factors controlling gold mineralisation. It has also led to the recognition of two distinct phases of alteration. The first phase of porphyry-style potassic alteration was followed by violent caldera formation, producing extensive brecciation and veining. The second alteration phase partly over- printed the first phase and was an epithermal one, evidenced by argillic, advanced argillic and phyllic assemblages. During this event, a large volume of fluids circulated under the favourable structural conditions; these fluids included a sulphur- rich, neutral chloride brine believed to have transported the gold. Boiling and mixing of circulating fluids in the open breccias is thought to have resulted in deposition of the gold. There is evidence that this process is continuing at the present day.

Jan 1, 1991

By Stewart A. Silling, Dale S. Preece

The two key results of rock blasting are fragmentation and movement of geomaterials. Movement/flow of the blasted rock is often referred to as heave. Modeling the movement of full scale blasting is now possible with 3D distinct element models and parallel processing.

Jan 1, 2016

The 21st Annual American Mining Hall of Fame Awards Banquet sponsored by the Mining Foundation of the Southwest will be held at the Sheraton Tucson Hotel in Tucson, AZ on Saturday, Dec. 6, 2003. This year’s inductee, guest of honor and featured speaker at the banquet will be Thomas J. O’Neil, recently retired president and chief operating officer of Cleveland Cliffs Mining. Prior to Cliffs, O’Neil spent 10 years with Cyprus Minerals. He was also professor and head of the Department of Mining and Geological Engineering at the University of Arizona. As representatives of mining heritage, the Hall of Fame will induct James Boyd and Thomas F. Walsh. Walsh discovered a rich gold telluride vein in Ouray, CO, which became the Camp Bird gold mine. Boyd was a former director of the U.S. Bureau of Mines, vice president of Kennecott Copper and later president of Copper Range.

Jan 1, 2003

A series of flotation experiments were carried out in a 2.25-dm3 laboratory-scale Rushton turbine cell using hydrophobic quartz particles. Flotation was performed at a constant mean bubble diameter over a range of superficial gas velocities and impeller rotational speeds. The overall flotation rate constant increased linearly with increasing superficial gas velocity (and hence bubble surface area flux). The rate constant also increased linearly with increasing energy dissipation, until a maximum value was reached. A further increase in energy dissipation had little effect on the rate constant. The dependency of the rate constant on energy dissipation is a reflection of the size range and hydrophobicity of the particles used in this study. The flotation rate constant increased with increasing particle size, except at the highest energy dissipation value examined, for which the flotation rate of the larger particles reached a plateau and, in some cases, decreased. Good agreement was obtained between the experimental results and those predicted by a fundamental flotation model using experimentally measured values for mean energy dissipation and the Sauter mean bubble diameter. The bubble velocity was adjusted to obtain the best fit to the experimental data. The inferred bubble velocity, based on the flotation model, was found to increase with increasing superficial gas velocity (and bubble surface area flux) and was found to decrease with increasing impeller rotational speed. While the inferred bubble velocities were significantly lower than experimentally measured bubble velocities, and, except at low superficial gas velocity values, significantly higher than the bubble swarm velocity calculated from gas holdup measurements, similar trends with impeller rotational speed and superficial gas velocity were observed in all cases.

Jan 1, 2007

By T. Robyn

The Bolivar Cu-Zn skarn deposit in the Piedras Verdes mining district of Chihuahua is one of many base and precious metal deposits in the north-northwest trending Sierra Madre Belt extending across the states of Chihuahua, Durango and Sonora in northwestern Mexico. The information presented here is drawn from two papers on the Bolivar property1,4 plus new information. Historical mining and exploration for polymetallic Cu-Zn-Pb-Ag-Au deposits in the Sierra Madre Belt dates to Spanish Colonial days. Access to the Bolivar Property (Figure 1) is by paved road (approximately 305 km southwest from Chihuahua) and approximately 80 km by all-season gravel roads to the villages of Cieneguita (population ~1,000) and Piedras Verdes (population ~500) adjacent to the property. [ ] The Bolivar property comprises an old Cu-Zn producer (the Bolivar Mine), exploration concessions adjacent to the Bolivar Mine, and a new camp at the mine that supports mining, exploration and maintenance. From 1980 to 2000, former operators extracted approximately 300,000 tonnes of ore that was hand sorted to an average grade of 5-6% Cu and 25-30% Zn. From 2005-2010, Dia Bras produced from the mine just over 600,000 tonnes at an average grade of 1.7% Cu and 8.6% Zn. Dia Bras transported mineralized rock 275 km by truck and rail to its Malpaso mill, located about 30 km west of Cuauhtémoc in central Chihuahua, from 2005 until October 2011 when the new Piedras Verde mill was commissioned only 5 km from the mine. (Note: the Company cannot use the term ?ore? because it has never completed a feasibility study.)

Jan 1, 2012

By S. M. Spottiswoode

Crush pillars are widely used in mine workings on the Merensky Reef in the Bushveld Complex to prevent panel collapses. Crush pillars are expected to fail as or soon after they emerge from the face and failure should occur non-violently. Unfortunately, violent failure occurs frequently and is said to be the main cause of seismicity associated with mining of the Merensky Reef. Recent work by Napier, Malan, and du Plessis has shown that limitequilibrium quasi-static models are able to simulate pillar failure using three states of strength of rock in pillars, namely intact, residual after failure, and decayed strength after later time-dependent (viscous) weakening. We have previously introduced an additional state of strength to account for the dynamic failure that results in seismic events, and found that this approach could be used to generate synthetic seismic catalogues similar to observed seismicity for deep-level gold mines, where seismicity takes place mostly on advancing faces. The less brittle seam material of the Merensky Reef, compared to the brittle quartzites and lavas of the Witwatersrand reefs, results in little or no face bursting and is modelled with an assumed plastic strain of some 0.005 over an effective stope width of 2 m before failure. When this plastic yield is surpassed, we allow the reef to fail ?seismically?. We show that synthetic seismic catalogues modelled in this way have some of the features of observed seismicity. Analysis is greatly facilitated using our custom-built software that reads the mine?s survey data into a database and presents results in an interactive graphical form.

Jan 1, 2014

By O. Ogunsola, M. Downing

This paper gives a brief overview of impacts of coal blending on coal-fired power plants performance and discuses the preliminary results of an on-going study aimed at evaluating the effect of coal properties on the effectiveness, compatibility and thermal reactivity of coal blends. Plant survey studies reported no significant impacts on an existing plant designed for a high rank coal when switched to a blend of low- and high- rank coal. However, slight modification of some aspects (handling, fuel storage/stockpile, transportation, preparation, and general housekeeping) of plant design and operation may be necessary. The preliminary results of an on-going study at the Mineral Industry Research Laboratory shows that more compatible and better blends could be made from coals where ranks are closer than from those where ranks are far apart.

Feb 24, 1997

The Canadian mining industry is one of the strongest in the world. Not only does the country produce a sizable amount of minerals and metals, Canada plays host to hundreds of global mining companies, large and small. The country, for the most part, recognizes the importance of natural resource development, particularly mining, to its economic well being. Like any country, though, there are federal and provincial regulations on the books that the industry takes issue with. But there are also certain economic incentive programs in place to encourage exploration and mine investment. And, unlike the industry and the United States government, the Canadian government and mining industry appear to have a reasonable working relationship.

Jan 4, 2010

Whilst the wider community is both a large consumer of mineral products and relies on mineral exports for much of the wealth which sustains it, the community generally has a poor perception of the minerals industry.   The role of professionals and The AusIMM in the "New Economy" minerals industry is reviewed. The new structure of The Institute is vital as we move forward in times of globalisation, rationalism, increasing litigation, criminalisation of risk and increased focus on corporate governance. This address looks forward to ways The AusIMM and professionals of the future are positioning themselves for these and other challenges.

Jan 1, 2001

By S. Asokan, D. Rathod, Ch. V. G. K. Murty

Tata Steel, a steel arm of Tata Group, is Asia's first and India's largest integrated private sector steel company. Tata Steel’s turnover in fiscal 2004-05 was nearly US$ 3.25 billion. As part of its vision to grow in related industries, Tata Steel is poised to enter the Titania businesses in the Indian state of Tamil Nadu. The Titania project will involve mining, separation of ilmenite & other co-minerals, beneficiation of ilmenite to synthetic Rutile and further maximum value addition to Titanium metal. This paper outlines the journey from the concept to current findings of the Bankable Feasibility Study in developing Sattankulam Heavy Mineral Sands Deposits in the State of Tamil Nadu, India by Tata Steel.

Jan 1, 2005

By N. Sutcliffe

Refractories and slags play a vital role in the production of stainless steel. They are in intimate contact with the steel at temperature, and chemical reactions between the three can and do occur. These interactions can be beneficial, in the case of active tundish and ladle slags, and negative in the case of refractory erosion and slag entrapment. This paper presents the results of both plant trials and laboratory investigations of steel/refractory and slag/refractory interactions. The interaction mechanisms observed are described leading to selection criteria for new refractory products. Keywords: slags, steels, refractories, reaction mechanisms.

Jan 1, 2004