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By S. R. Seagle, R. Schuhmann, N. A. Parlee

Rates of CO evolution and CO absorption were measured for liquid-iron alloys containing from 0.15 to 4.4 pet C, using a modified Sieverts apparatus. The alloys were held in alumina crucibles, so that both crucible-metal and gas-metal reactions occurred simultaneously. The data are interpreted on the hypothesis that the C-O reaction rate is controlled by oxygen diffusion across the boundary layers at the gas-metal and crucible-metal surfaces. CARBON-monoxide evolution from liquid Fe-C-0 alloys is a key reaction in steelmaking processes, both in the steelmaking furnace and in the ingot mold. Also, this reaction probably is an essential step in the desulfurization of iron under blast-furnace conditions, for which carbon is the principal reducing agent or deoxidizer present in the iron. The thermodynamic properties of the solutions of C and 0 in Fe and the equilibria of these solutions with gaseous CO and CO, have been investigated in some detail and are reasonably well understood. However, while these equilibrium data have accumulated in the laboratory, other data have accumulated to show that equilibrium conditions are often not achieved under plant operating conditions. Thus, an understanding of the rate and mechanism of the carbon-oxygen reaction not only has theoretical interest, but ultimately may assume considerable practical importance. Reaction Mechanisms and Rate Equations The over-all reaction under consideration is C (in liquid Fe) + 0 (in liquid Fe) + CO (gas) [I] Although this appears to be a straightforward heterogeneous reaction, involving just two phases (liquid metal and gas), a wide variety of reaction mechanisms has been proposed. Different authors have expressed divergent views as to the nature of the rate-controlling steps. Accordingly, a brief discussion of the possible reaction steps will be given. 1) Homogeneous Reaction Within Liquid Iron— Feild' and Jette2 have applied chemical reaction-rate theory as if the C-0 reaction were a homogeneous, second-order reaction occurring within the liquid-metal phase. This mechanism necessarily produces CO "molecules" dissolved in liquid iron. In order to yield CO gas, the dissolved CO must nucleate CO gas bubbles, and the dissolved CO also must be transported to the bubble surface where it enters the gas phase. However, this mechanism is inconsistent with present concepts of the structure of liquid-metal solutions. 2) Reaction at Gas-Metal Interface—At the surface of contact between gas and metal, a second-order reaction between dissolved C and 0 may occur to produce a CO molecule which enters the gas phase. This reaction presumably involves an "activated complex" structure in the interface. Some such surface mechanism appears essential because the carbon and oxygen do not occur in the same species in the two phases and therefore must react in some way at the surface. At liquid-iron temperatures, calculations based on reaction-rate theory indicate that the surface reaction must proceed extremely rapidly and thus cannot be a rate-determining step in the C-O reaction under ordinary conditions.3 ccordingly when the over-all reaction is measurably slow, the surface reaction may be considered at equilibrium; that is Cc* Co* = m'Pco [2] in which Co* and Co* are the concentrations of carbon and oxygen (weight per unit volume of metal), respectively, in the liquid-metal phase at the interface, Poo* is partial pressure of CO in the gas phase at the surface (atmospheres), and m' is the mass-action constant for Reaction [I]. Since activities of C and 0 are not strictly proportional to concentrations, m' is not a true thermodynamic equilibrium constant but varies with carbon content.' 3) Mass Transport—If the reaction is to proceed at the gas-metal surface, as described above, dissolved carbon and oxygen in the liquid iron must come to the surface and gaseous carbon monoxide must move away from the surface. Details of the mass-transport mechanisms depend on the kind of system under consideration. For a stirred metal bath in contact with a CO gas phase, the transport of C and 0 to the surface can be described by 1 Do Mols CO evolved per sec = — 1/16— Do/do Agm (CO-Co*) = 1/12 Do/do Agm *(Co-Co*) [3] In this equation, Do and D, are the diffusion constants for oxygen and carbon in liquid iron, 6, and 6,. are the boundary-layer thicknesses, A,,,, is the

Jan 1, 1959

R. W. Raymond, New Pork City: It seems questionable to me whether Mr. Mezger's identification of the rock-structure he describes, as the Augengneiss of previous authors, is warranted by the definitions given by them. Naumann (1854)t describes Augengneiss as a porphyry-like variety, " which has assumed, by reason of single large kernels or granular concre-

Jan 1, 1896

By R. Escalera-Lozano, M. Herrera-Trejo, M. A. Pech-Canul, J. López-Cuevas, A. L. Leal-Cruz, M. I. Pech-Canul

"The use fly-ash (FA) and rice-hull-ash (RHA) offers the potential for the manufacture of hybrid Al/SiCp/spinel composites via reactive infiltration, both with recycled aluminum. The main reason behind this statement is the beneficial role that both waste materials play in preventing the degradation of SiCp reinforcements when the composites are processed with aluminum in molten state. Experimentally, MgAl2O4 is formed in situ during the infiltration of SiCp-preforms in the temperature range 1050-1150 oC for 50-70 min in argon atmosphere at a pressure slightly above to that of the atmospheric pressure. Results reveal that both FA and RHA help in preventing SiCp dissolution and the subsequent formation of the unwanted Al4C3; and although FA-composites still might be susceptible to corrosion via Al4C3 -by the interaction of native carbon in FA with liquid aluminum- a proper FA treatment significantly mitigates its deleterious effect. Primary corrosion mechanisms and strategies to overcome the potential degradation effects are outlined.IntroductionOwing to inherent materials characteristics and post-processing complications –such as corrosion damage- development of metal matrix composites (MMCs) from recycling/waste sources might be a challenging task. Fly-ash (FA) and rice-hull-ash (RHA) are two primary waste materials that offer excellent opportunities for the development of Al matrix composites. Due to its singular hollow-spherical shape and low density, FA has attracted the attention of many researchers. For this reason, most of the efforts to develop Al-based composites from waste materials have been centered on the use of fly ash. Extensive research efforts in the use of FA for Al-based composites have been undertaken by Rohatgi and coworkers [1-4]. In addition to lowering costs, incorporation of fly ash into aluminum has been proved to decrease the materials’ density, increase their hardness, abrasion resistance and stiffness [1]. One of the major outcomes from the mechanical evaluation of aluminum composites prepared with fly ash is that related to their compression characteristics. Typical compressive stress-strain curves form A356/hollow fly ash composites show a linear elastic region followed by a plateau (associated to the collapse of the hollow particles), and then an increase in stress, representing densification of the foam. The crushing of the cenospheres in the composites has been related to an enhancement in the energy absorption capabilities of the material and to a better damage tolerance [4]."

Jan 1, 2008

By A. Belleau, F. Lavoie

"Quebec Iron Ore Limited (QIO), a subsidiary of Champion Iron Limited (Champion), secured assets in early 2016 from the previous Bloom Lake operations in the heart of the Labrador Trough region of Northern Quebec, Canada. A plan was developed to bring the Bloom Lake facility back in operation once the iron ore market conditions improved. The project restart involved several aggressive moves to change operational effectiveness, one of which was the utilization of the existing Phase 1 Plant with an upgraded process flowsheet and equipment. The production target was 7.4 million tonnes per annum of 66% iron ore concentrate with an approximate 10% increase in iron ore recovery. The Phase 1 upgraded flowsheet was initially based on review of historical Phase 1 data and pilot testing data undertaken during the original Phase 1 operation and was finalized once additional metallurgical test work and process modeling was carried out by Mineral Technologies in late 2016. The final upgraded flowsheet is comprised of rougher spirals, rougher middling scavenging spirals, and an up-current classifier (UCC) with overflow scavenging spiral stage. A portion of the gravity circuit tailings treated by a series of wet high intensity magnetic separators (WHIMS) to boost overall iron recovery. This paper will describe the efforts taken to test and design the Bloom Lake Phase 1 upgraded flowsheet and report on the plant performance since commissioning in first quarter of 2018.SITE HISTORY The Bloom Lake iron mine property is located approximately 13 km north of Fermont, Quebec, and 10 km north of the Mont Wright iron ore mining complex, property of ArcelorMittal Mines Canada. The Bloom Lake mine facilities include a 32 km railway to efficiently transport the high-quality iron concentrate to a loading port located in Sept-Iles, Quebec. The Bloom Lake property was first explored in 1951 and went through multiple minor exploration campaigns by different companies up until 1998. A major exploration program was conducted by Quebec Cartier Mining (QCM) in 1998. This program included line cutting, surveying, diamond drilling, geological mapping, mini-bulk sampling, bench-scale preliminary metallurgical test work and preparation of a “mineral resource” estimate."

Jan 1, 2019

By H. C. Cooke

"The Eustis mine, which was discovered in 1865, lies about 6 miles southwest of the city of Sherbrooke, Quebec, in lots 2, 3, and 4, range 9, Ascot tp. The mine was operated almost continuously from 1865 to 1937, under vanous owners.The ore was pyrite with varying amounts of chalcopyrite, a small amount of zinc blende and galena, and a low content in gold and silver. Parts of it ran quite high in copper, but the mine average would probably have been between 3 and 4 per cent. The high percentage of pyrite made it profitable to separate the ore into a copper concentrate and a pyrite concentrate. The latter was shipped away for manufacturing sulphuric acid, or was treated in a plant erected in 1887 at Capelton by the Nichols Chemical Company.The ore is a replacement of mica schist, which in turn was formed by the shearing of rhyolite flows. Ore also replaces the 'green rock', a term locally applied to carbonatized mica schists. The ore contained numerous 'horses' and smaller fragments of country rock, in all stages of replacement, ranging from those whose character was quite distinct to those whose ancestry could only be detected by an indefinite banding preserved in the sulphides."

Jan 1, 1954

The introduction of computer technology to the mining industry has produced many benefits for the mining engineer. The most significant is the dramatic increase in productivity realized by the individual user. This is important during times of competitive market conditions. Software for the minerals and energy industries has evolved substantially over the past decade. But even today it remains difficult to find a system that features the flexibility and integration capabilities to effectively (and cost-effectively) handle the needs of professionals in each phase of the mining industry - from exploration to reclamation. Several national software developers are now addressing this challenge. One Denver-based company, MINEsoft Ltd., offers a software package that is currently being used in each phase of the mining industry. The basic technology used in MINEsoft's database management system was developed in the 1960s. But during these early years of the computer industry, most of the technology was available only on mainframe computers, and then only as separate entities. MINEsoft's system unifies these various systems in one package that can be used on most computers manufactured today. Database Management System TECHBASE is a flexible, integrated database management system designed specifically for technical applications. The system features a database manager with no practical limit to the amount of data it can store, retrieve, and manipulate, according to the company. TECHBASE in¬cludes Applications Packages (TAPs) designed to meet the needs of professionals in a host of industries. Clients use the TECH BASE system to prepare many reports, including important EPA information. The package reduces data to a manageable level and enables users to increase productivity with a smaller staff. Mining engineers no longer need to do things by hand. What used to be a day's work can be accomplished in an hour or two. Exploration "Using the TECHBASE system to generate maps has probably saved us the expense of three or four draftsmen," says Ralph Fitch, regional manager and senior staff geologist with Chevron Resources in Portland, ME. "The system has great flexibility. You can treat it much like a spreadsheet. If you are halfway through with a particular project, the system allows you to add fields and calculations with ease but without starting over." Fitch uses TECHBASE for the "straightforward" plotting of results and generation of geochemical and geophysical profiles. "In exploration," he says, "these are the two key elements ... the generation of maps and data profiles. The system allows you to plot as many elements and variables in these areas that you like." Other aspects are important, too, says Fitch, including drill hole sections. "We use all the basic capabilities the system provides in the complete package," he explains. "When shopping for a system, TECHBASE was clearly dedicated to exploration in the

Jan 9, 1987

By M. Murphy

The multibillion dollar cost of cleaning up thousands of environmentally contaminated sites across the country created by decades of inadequate disposal of hazardous waste has led to a search for "deep-pocket" sources of cleanup funds. The resul1:: is the emergence of a growing body of law that could have a profound impact on commercial financing transactions and other investment activities when present or past owners of contaminated property are involved.

Jan 1, 1988

By A. P. Whittlestone, J. D. Johnson, R. J. Pine, M. E. Rogers

standpoint. The effect on efficiency of collisions

Apr 1, 1995

By Eli T. Conner

WITH Thomas G. Fear, chairman of the Coal Di- vision, presiding, the coal miners opened their program Monday morning with a general session at which three papers were presented. The first, "The Classification of Coal for Stationary Steam Generation," was presented by the author, Thomas W. Harris, Jr. In discussion, H. T. Coates inquired if it would not be possible to pick out a geographical coal section, certain seams or a group of mines, which would rank high in a desired feature or features, perhaps giving different -- - local sections or different mines something to designate a rating ("good," "fair," and "poor"). This might be done relative to anti-clinkering, free-burning, ,anti-slagging, smokelessness, friability and grindability. These might be listed or arranged on a map or diagram so that the prospective customer could find a coal that rated particularly high in desired characteristics. C. A. Reed pointed out, in part, that coal producers and sellers have found a bad but necessarily present condition in the country, especially with the smaller user of coal. This is entirely due to the fact that the employer expects his purchasing representative to be a genius and have expert knowledge of everything he buys, coal included, whereas in the larger plants he has and uses expert knowledge from the active organization when necessary. J. B. Morrow said that size rating was important in classifying coal and he emphasized that it was impossible to come to a definite basis on analysis alone.

Jan 1, 1933

By MEHMET ALI RECAI ONAL, MAHMUT CAMALAN

The key motivation of this study is to evaluate the potential of well-known hazardous gases—carbon dioxide (CO2), hydrogen (H2) and oxygen (O2)—as grinding aids for mineral liberation in ball milling. The results show that exposure of chromite ore particles to CO2 flow will promote chromite liberation at breakage and, therefore, using CO2 as a grinding aid may partially reduce the carbon footprint of the mining industry. For that purpose, the use of two-phase (gas–solid) or three-phase (gas–solid–water) moving-bed mixers are recommended for the pretreatment of mill feed before ball milling.

By P Blattner

The Late Miocene gold-silver bearing epithermal system at Waihi has some close similarities in its paleo-thermal and geochemical structure with modern, volcanic-hosted geothermal systems such as Ohaaki-Broadlands. At Waihi an extensive braided quartz vein system is enveloped by hydrothermally altered andesites with minor tuff breccias and tuffs. A main stage of vein filling consists of multiple phases of chalcedonic quartz and fine to medium grained quartz, which are accompanied by pyrite, sphalerite, galena, chalcopyrite and acanthite below the base of oxidation. Platy calcite is present locally. Fluid inclusion studies indicate that the main stage quartz was deposited at temperatures of 189¦-273¦C from dilute (Tm of -0.1 to -1.0¦C) fluids that were locally boiling. Homogenisation temperature Th versus Tm data points lie within the field enveloped by dilution and boiling/gas loss paths determined for the Ohaaki geothermal field, and indicates that the parent hydrothermal fluid for the Waihi epithermal system had a similar composition to that at Ohaaki, ie 0.2 wt% equiv NaCl and 3.3 wt% equiv CO2. The hydrothermal alteration mineralogy and the isotopic composition of vein calcite indicate that the hydrothermal fluid contained relatively high concentrations of CO2 , as at Ohaaki. Oxygen isotope analyses of main stage quartz range from 6.1 to 11.6 %0 and of vein calcite from 2.29 to 9.4%0. Calculated d18Owater values for the hydrothermal fluid that deposited the main stage quartz range from 2.0 to -5.7%0, with a trend to less negative values with depth. They are similar to those in the deep chloride fluid in active geothermal systems with a substantial fluid throughput. A high fluid throughput at Waihi system is also evident from the extensive high intensity hydrothermal alteration and large volume of quartz deposited in the vein system.

Jan 1, 1995

Lonmin, earlier than any other primary platinum producer, had to deal with the concentrating and smelting of UG2-rich ores and concentrates respectively. Smelting was performed at a fairly modest scale compared to the company's industry peers in the platinum group metals (PGMs) industry, and was focused on smelting concentrates obtained through low mass pulls while still maintaining high recoveries at its concentrators. Lonmin gradually smelted larger quantities of UG2 concentrates. Initially two 2.3 MW Infurnco furnaces were commissioned in 1982, followed by three 5 MW circular 3-electrode Pyromet furnaces in 1991. Deep electrode immersions and moderately high hearth power densities were used in all the designs. Lonmin decided to continue with circular furnace technology when it planned its new high-intensity No. 1 Furnace. Neither Lonmin nor the technology supplier and EPCM company foresaw the challenges that scale-up would bring when applied to the smelting of UG2-rich concentrate blends. Superimposed on the high chromite content, was the low base-metal loading, mineralogical difficulties, and fine particle size that resulted from milling of all concentrates (especially UG2 and recycle materials within the smelter). Through a process of fundamental diagnoses of furnace run-outs and wear patterns observed during repairs, the main challenges operating this high-intensity furnace were identified as sulphur vapour corrosion of the copper coolers, uneven and unpredicted movements of refractory bricks with associated copper cooler lift and matte tapblock movement, the formation of three-phase 'mushy' zones, high refractory and taphole wear rates, uncertainty in matte level and associated insufficient matte buffer height, and high furnace operating temperatures. These factors seldom worked in isolation and will be explored in more detail in the paper. The variability in furnace feed characteristics led Lonmin to redesign Furnace No. 1, to invest in backup furnace capacity, and to invest in improved monitoring and control. These improvements consisted of online and high-frequency off-line monitoring of feed chemistry and mineralogy, online pressure monitoring of water-cooled circuits, an alternative matte liquid level measurement in the furnace, and electrode immersion estimation. Improvements were also made at the converters by installing and utilizing optical spectral analysis of the converter flame to characterize converter behaviour and achieve the desired iron end-point for white matte. This paper also briefly discusses the current and future expansion plans, as well as ancillary operations at the smelter such as flue-gas handling and materials handling.

Jan 1, 2011

By Arthur T. Ward

DESPITE the intense preoccupation of most of those members connected with the mining, concentration, and reduction of iron ores, the luncheon and subsequent technical session of the Eastern Magnetite Committee were exceedingly well attended. Many of the older faces were absent, but new ones took their places. More than sixty, all told, took in the technical session. Chairman Crockett opened the session by calling upon Meredith E. Johnson, whose paper, with its accompanying graph, was in reality a comprehensive historical review of iron mining from colonial days to the end of 1941. with some notes on current expansion which indicates that New Jersey is destined to become a still more important. factor in the production of magnetite ores.

Jan 1, 1942

By C. Hanson

Two modes of potential loss of oxime extractants in liquid extraction processes for the extraction of copper have been studied. In loss "by chemical degradation, two mechanisms of acid hydrolysis are possible, some reagents degrade primarily in the organic bulk phase, Others at the interface between the organic phase-- phase protects the oxime but salts added to the aqueous acid phase can promote the rate of degradation. The reagents reported on are the LIX series (Henkel Cpn), SME529 (Shell Chem.Co.) and P5100 (Acorga) Loss by organic entrainment in the aqueous phase leaving mixer-settlers has also been studied, parameters investigated including impeller/tank geometry and the phase inlet arrangements. The consequences of extractant loss by the above mechanisms...are commented upon. They include the direct economic cost, the possible environmental problems and the implications for downstream operations such, as electrowinning.

Jan 1, 1980

By Bradford P. Simser

The theoretical capacity of various ground support components can be misleading, especially in bursting ground where the failure mode is often in the retainment system. Wire mesh screen seams often peel open rather than breaking the wire strands, fractured rock often un-ravels around the bolts rather than breaking the bars. If a weak link(s) in the system fails prematurely, then the potential capacity of the system may never be fully realized. Underground observations are used to show how some support systems behave in the field. Various combinations of wire mesh screen with friction bolts, rebar, modified conebolts, cablebolts, shotcrete and mechanical rockbolts are considered. A short case history is used to contrast the performance of ?just-intime? development in a high stress faulted area versus a tunnel subjected to multiple stress changes in a similar environment. The latter proved to be a serious ground support problem when the well developed fracture zone around the opening was subjected to dynamic loading from a large seismic event causing a severe rockburst. In such cases an improved mining strategy may be more relevant than higher capacity support systems.

Feb 1, 2008

With the dawning of a new century came the beginning of a new era in the coal industry. Instead of the traditional practice of only buying and selling produced coal in the United States, a coal futures market was established. The New York Mercantile Exchange began trading coal futures in July 2001. But, even in this new era, many of the old is-sues that have beset the coal industry still remain, as was evident in2001. Coal production increased to are cord level during 2001, according to preliminary data from the US Energy Information Administration(EIA). Production in 2001 rose by4% to 1.01 Gt (1.12 billion st), compared with 2000 (Table 1). This barely surpassed the previous record level of 1 Gt (1.11 billion st)set in 1998. Coal consumption remained unchanged. The additional production was used to replenish the depleted stockpiles that had resulted after two years of declining coal production and increasing coal consumption.

Jan 1, 2002

By H. L. Luo

SYSTEMATIC investigations of the Fe-Ga system have been reported only very recently."' The maximum solid solubility of gallium in a-Fe is nearly 50 at. pet at 900°C. However, from Ref. 1, it was not evident that the a-Fe solid solution could be retained successfully beyond 17.38 at. pet Ga by solid-state quenching. The present investigation reports the retention of a-Fe solid solution at 50 at. pet Ga by quenching from the liquid. An ordered phase of CsC1-type B2) structure was observed between 34 - 50 at. pet Ga. Since it was considered very probable that the CsCl structure would occur at high temperatures, alloy filings were also quenched by the conventional quenching technique. In addition to the CsCl phase, a second ordered phase of BiF3-type (DO3) structure was found in the range 25 - 30 at. pet Ga. Alloys were prepared from elements of 99.99 pet purity or better, induction-melted in alumina crucibles under hydrogen. After reweighing, the alloy ingots were cast into wires under argon. From the weight losses and the reproducibility of the lattice parameters, compositions were estimated to be within ± 0.3 at. pet. The techniques of quenching from the liquid state were reported before.3-5 Prior to quenching, a small section of cast alloy wire (30 - 50 mg) was melted in an alumina insert under an argon flow. The quenched specimens were in the form of flakes, typically 1 sq mm in area. For solid-state quenching, alloy filings passing 200 mesh were sealed under a reduced helium atmosphere in a thin-bottom silica tube. After heating for -30 min at the desired temperature in a vertical furnace, the sealed tube was rapidly dropped into ice water so that the thin bottom of the tube broke on impact. The quenched alloy filings were always ferromagnetic and could be collected by a magnet. X-ray diffraction patterns were taken with iron-filtered cobalt radiation in a 114.6-mm-diam Debye-Scherrer camera. High-angle lines were always resolved and spacings were computed relative to ? (CoKa1) = 1.78890Å. Lattice parameters were obtained from extrapolation against the Nelson-Riley function. The variation of lattice parameter with composition is shown in Fig. 1, together with the data of Dasarathy and Hume-Rothery.1 Uncertainties in the present measurements are within the dimensions of the symbols or indicated by error bars. X-ray diffraction lines indicative of CsC1-type ordering could be clearly identified for alloys of 34 - 50 at. pet Ga quenched from the liquid and alloys of 35 - 41 at. pet Ga quenched from -975°C. Within experimental error, no difference in

Jan 1, 1968

By Ryan Ward

The Missouri River Intake Screen Structure and Tunnel (MRISST) is one phase of the Red River Valley Water Supply Project (RRVWSP), a vital piece of infrastructure in the state of North Dakota to transport water to drought-laden communities in the eastern half of the state. The scope of work consists of constructing a cofferdam in the Missouri River, mining a 1,600-foot by 74-inch tunnel from a secant pile shaft near the riverbank into a cofferdam, and erecting a 40-foot Y-shaped vertical pipe structure in the cofferdam to support the intake screens. Construction personnel worked in the river through the North Dakota winter to construct the cofferdam and contended with high hydrostatic pressures and raveling sands, gravels, cobbles and boulders while mining the tunnel. Diligent planning and meticulous execution were essential to overcoming the challenges encountered below the Missouri River.

Jun 13, 2023

By L. Karka

The gold processing plant location in the Chalkidiki coastal area has been studied as a land use conflict case study in the context of a EU research program. The sustainability assessment of the plant establishment is made on the basis of a group of sustainability principles and criteria adopted in the framework of the SPECTRA project. Since the gold processing project has not been implemented yet its sustainability assessment is made on the documents submitted by TVX Gold during the procedure for the siting consent and the granting of environmental conditions. The assessment, appearing on a table, reveals an important effort to achieve a high degree of protection during the operation and after completion of the activity. The specific nature of the development and the knowledge of the local opposition in favour of tourism development have obviously influenced the priorities set.

Jan 1, 2003

By J Samosir, L A. Snyman

Northparkes is located 27 km north of the township of Parkes in central New South Wales, Australia. The operations consist of underground block cave mines and an ore processing plant that produces high-grade copper and gold concentrate. Production is currently sourced from the E48 Lift 1 block cave mine and open cut stockpiles. Mining commenced at Northparkes in 1994 as an open cut operation. Underground block cave mining began in 1997. Northparkes was the first mine in Australia to use the highly efficient block cave mining method, which relies on gravity and natural rock stresses to fragment the ore.An issue affecting production in 2011 was the stability of the E48 mine. A small portion of the drives on the extraction level began to deteriorate as the ground support system failed. The problem was temporarily fixed by stopping production in three extraction drives and tight filling selected areas within these drives (and drawpoints) with low-strength concrete. This action provided immediate support and stability whilst allowing time to investigate potential ground support remedies. From these investigations it was decided to use resin injection technology and additional ground support to stabilise the rock in the aforementioned extraction drives as the concrete plug was excavated in a controlled advance and sequence. This made the area safe and ensured the ongoing safe operation of the E48 mine. The redevelopment of one of these drives began late in 2011, with the remainder being progressively redeveloped over the next two years in order to maintain the extraction level stability.This paper looks at the strategies employed to safely re-open previously converged drawpoints and associated extraction drives that were subject to high abutment loading that was possibly associated with premature cave breakthrough.CITATION:Samosir, J and Snyman, L A, 2014. Redevelopment at Northparkes following significant drive closure, in Proceedings AusRock 2014: Third Australasian Ground Control in Mining Conference , pp 87–92 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 5, 2014