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By D. J. Duck

INTRODUCTION Construction of the 3,600,000 kilowatt Third Powerplant at Grand Coulee Dam started in late summer 1967 approximately one year after authorization by Congress. The project was made possible by a treaty with Canada providing for cooperative development of the Columbia River which was signed in 1961 and ratified in 1964. Description of the Work The existing Grand Coulee power complex consisted of a dam and two powerplants with a switchyard serving each plant, one on each bank of the river. See Fig. 1. The switching facilities were connected to transformers at the powerplants by overhead 230-kilovolt and 115-kilovolt tie circuit conductors. [ ]

Jan 1, 1997

A new method, localized uniform conditioning (LUC), was proposed in 2006 for modelling grades of small blocks of ore when data spacing is too broad for their accurate modelling by the linear regression based techniques, such as kriging (Abzalov, 2006). It represents a modified uniform conditioning (UC) technique that calculates the grade distribution functions for the large panels. LUC uses partitioning of the panels onto the small blocks and then ranks them in increasing order of grade. Based on the block ranks, a single grade value can be deduced for each block from the UC model of the gradetonnage relationships of the corresponding panel. After being first presented in 2006, the LUC method has been implemented in ISATIS© (commercial software) and became one of the common approaches for grade estimation when data spacing is broad in comparison with the estimated block size. Several years of study on the LUC method and its application to different geological environments, have allowed identification of the strengths and weaknesses of the method, which are as follows: ? The method produces accurate grade-tonnage functions, which are in a good accordance with a volume-variance relationship principles ? An initial ranking of the selective mining unit (SMU) blocks can be made by direct kriging from the sparse data grid. Therefore, the LUC method can be particularly useful at the early stages of exploration and mining project evaluations when sparsely distributed data is often the only available information ? Accuracy of the local estimation depends on the SMU ranking techniques. When ranking performed by direct kriging of the SMU blocks their spatial distribution is approximate. When the variogram of the studied variable is characterized by a large nugget effect, the block ranks produced by kriging can significantly differ from their ?true? distribution ? Block ranking can be improved using auxiliary data, either geophysical or geochemical. This allows use of the LUC method for integrating different data sets. In particular, LUC can be used for grade control in open pits by integrating resource definition data (e.g. drill-hole assays) and blast-hole assays. The latter are used for the block ranking.

Jan 1, 2014

By Stephen Hodgson, Ken Brouwer

September 2005, Northern Dynasty Mines announced the discovery of a new, high-grade deposit at its Pebble project in southwest Alaska. The product of insightful geological investigation, Pebble East, as it is now known, is quickly growing into one of the most significant copper deposits in the world. Preliminary analysis shows it could reduce the U.S. copper supply deficit by a third. The new deposit has also altered Northern Dynasty’s view of how Pebble should be developed. This article describes the Pebble project as it is currently understood and outlines the work planned for the next several years.

Jan 1, 2007

A survey has been undertaken of the petrography of North Island greywackes with a particular focus on the occurrence in them of smectite (swelling clay) and chlorite, two minerals that are closely associated, chemically similar, and commonly interlayered with each other. Smectite is the mineral which is a major cause of greywacke aggregatesÆ poor performance. Smectite occurs in post-metamorphic shear zones and in surface weathering profiles over greywackes. This study focuses on the petrography of fresh greywacke rocks.   The occurrence and abundance of smectite and chlorite and their relationship in greywackes is largely a function of the chemistry of the sediment and the maximum temperature that the sediment has been subjected to during diagenesis and/or very low grade (anchizone) metamorphism. Rock chemistry, particularly total iron and MgO, determines the smectite and/or chlorite content in fine-grained greywackes (argillites and siltstones) but chemistry is less influential in sandstones, where at low grades of metamorphism much of the Fe and Mg of the rock is held in unreacted detrital minerals and the mineral constituents of lithic grains.   Four zones which represent different levels of diagenesis and very low grade metamorphism, based on the crystallinity of illite and chlorite in the greywackes, and the proportion of smectite interlayered with chlorite, have been mapped in the North Island. In the anchizone smectite does not appear as a discrete mineral, it is always interlayered with chlorite. In the upper anchizone chlorite contains approximately ten per cent of smectite interlayered with chlorite. In the lower anchizone about 30 per cent smectite can occur in chlorite.   In addition to the smectite and chlorite inherent in the greywackes as the result of the thermal overprint, smectite as a discrete mineral and smectite-chlorite interlayered minerals with high levels of smectite, occur in abundance on shear zone surfaces and in alteration zones adjacent to shear zones; these are the main contributers to the high levels of smectite recorded in many greywacke aggregates.

Jan 1, 2006

By J. McMurray

Introduction Uranium was recovered from mining of collapse breccia pipe deposits in the Arizona Strip district in northwestern Arizona (Figure 1) intermittently between 1956 and 1990, with cumulative production having totaled 23.3 million pounds of U3O8 (8960 tU) at an average grade of 0.6% U3O8. Production was suspended in 1990 because of low uranium prices, but the recent resurgence in market price once again makes the breccia pipe deposits potentially attractive exploration and development targets. This paper describes: (1) formation of the pipe structures and their metallogenesis; (2) mining and milling of breccia ore; and (3) potential roadblocks to development of new breccia pipe mines. Breccia Pipe Formation Formation of the breccia pipes began in cave systems formed during development of karst topography in the Mississippian Redwall Limestone. The karst Redwall surface was eventually covered by up to 900 meters of shallow marine to continental sediments ranging in age from Pennsylvanian to Triassic. The pipes were formed by progressive upward stoping caused by groundwater ascending under hydraulic head along near-vertical faults, joints and fractures. The stoping process involved both chemical disaggregation and mechanical failure of roof and wall rock. Upward stoping of successively younger units allowed for upward propagation of a pipe and resulted in a chimney-like column of breccia between the steep walls of the pipe. Syndepositional thickening of sedimentary units of varying ages indicates that pipe formation began as early as early Pennsylvanian time and continued intermittently through Triassic time.

Jan 1, 2007

By J. A. Hayes

For over a decade the Osterberg Load Cell has been successfully used to determine the shear capacities of drilled shafts. Since the test method measures side shear directly, analytical complications due to the influence of end bearing resistance are removed. The data suggest that the side shear component of a drilled shaft's capacity is often more significant than end bearing. Given the interest in the use of side shear in drilled shaft design in compressible materials, it is important to examine factors that can influence capacity. We have found that some factors widely believed to influence capacity, such as slurry type, are not as important as commonly thought in most materials. Factors that are not usually considered as important, such as casing use, hoop spacing, concrete slump, concrete additives, spacers and rebar clear cover, seem to be more influential with respect to side shear capacity. For example, substantially lower than predicted shear resistance can occur when the rebar clear cover is small with respect to the cage diameter. We observe this most often in fine-grained cohesive soils. This effect can be exaggerated if the rebar cage has tight hoop spacing, if the concrete has low slump and if the hole is not straight. We have also noted that improper use of temporary casing can have a dramatic effect on side shear resistance. In some cases we have observed tested shear capacities reduced to less than 5% of either predicted or available shear values.

Jan 1, 2003

By Steve Dillingham

Whenever misfired holes or portions of misfired holes remain after a blast is fired, a hazardous situation exists until the unfired explosive materials have been disposed of properly. Yet, there are so many factors that can contribute to misfires that it is impossible to give blanket instructions on how to handle them. To complicate matters, misfires today are rare due to reliable blasting products. As such, it isn’t very surprising that many blasters have never had to deal with a misf i re condition. While the likelihood of a misfire occurrence is minimal, you should always be pre p a red to handle a misfire should you be involved in such an event. To begin, every blaster and blasting org a n i z a t i o n should develop a misfire policy which contains the company’s safe operating pro c e d u res, emergency contact list, as well as any regulatory compliance re q u i re m e n t s . Tailgate and/or company-wide safety meetings should communicate the company’s contingent misfire pro c ed u res and any special site-specific precautions BEFORE the start of any project.

Jan 1, 2004

By D. R. Murray

A four-year study was carried out to determine the ability of coniferous trees to aid in the reclamation of uranium tailings at Elliot Lake. Five species were planted: white cedar, white spruce, jack pine, scotch pine and red pine. More than 570 bare-root, two-year-old seedlings were planted on bare tailings and in areas of established grasses. A further division was made between areas of coarse and fine tailings. Over-all survival and growth of the trees has been far below expectations based on previous experience with several varieties of grasses. The criteria for assessment have been per cent survival and yearly growth as determined by plant height. Pine was superior, with 68% survival when planted in bare coarse tailings, 45% for vegetated coarse tailings and 34% for vegetated fine tailings. Cedar had the worst survival rates at 49%, 14% and 7% respectively. No species survived on bare fine tailings. The survival and growth of the coniferous trees have been related to species, environmental conditions and tailings properties.

Jan 1, 1978

By R. C. E. Bray, Peter Price

"The property of Pamour Porcupine Mines, Limited, is in the eastern Porcupine area, about 12 miles northeast of Timmins. It covers parts of lots 3-6 (inclusive), cons. 5 and 6, Whitney tp., Cochrane district, Ontario. It is an amalgamation of the old La Palme, Three Nations, and Porcupine Grande properties.The first discovery on the Pamour was made in 1911. During 1911 to 1914 a small shaft was sunk on the Three Nations vein to the 200-foot level and a 100-ton stamp mill was put in operation, but only a small production was achieved. The property remained idle from 1914 to 1923. In 1924 some diamond drilling was done along the Keewatin-Timiskaming contact with some encouraging results, but the gold mineralization encountered was too low in general at the price of gold then prevailing to warrant further · work. The increase in the price of gold revived interest in the area, and the above noted amalgamation was effected in 1934. Options were taken and successively dropped by two large mining companies. Following this, exploration both on the surface and underground was started by Quebec Gold Mining Corporation, Limited. Diamond drilling in the early part of 1933 showed considerable ore in conglomerate and greywacke to the east. In the middle of 1935 Noranda Mines, Limited, assumed control and management. A new shaft was sunk and the property was ·equipped with a mill having an initial capacity of750 tons a day. This was subsequently enlarged to 1,500 tons a day.From the commencement of milling (May 16, 1936) to the end of 1946, 5,025,545 tons of ore having an average grade of 0.1327 oz. a ton ($4.64 at $35 an oz.) have been mined and milled."

Jan 1, 1954

The effect of composition on electrical conductivity (resistivity), viscosity and liquidus temperature of the slags encountered in electric smelting of PGM-containing suphide concentrates is reviewed along with the relationsip between slag composition, slag-matte separation and metal losses to slag. Optimization of slag composition at furnace temperature is attempted on the basis of opposite and parabolic trends of the viscosity-conductivity relationships of the slags. The importance of surface tension of slags is emphasized using available and estimated information, which are grouped into a useful correlation. These values are coupled with or incorporated into slag viscosity plots to illustrate the correlation between the two factors which influence slag-matte separation as well as refractory attack. The electrode in the slag-resistance furnace is the central factor in the design and operation of the furnace by its role of conveying the smelting power. The obvious parameters are the size and positioning in the slag bath, which are defined by slag resistivity, furnace resistance, cell constant and power input. The flow of heat generated by the electrode current determines the energy distribution and furnace dimensions creating viscosity profiles, which in turn affect flow conditions. Thus the flow of slag and matte isdiscussed in conjunction with the furnace geometry, stirring action of the electrodes, buoyancy and electromagnetic effects. The action of the electric furnace as a settler is discussed. The rectangular furnace is considered as a channel reactor in this analysis and the action of the electrodes is described to indicate a balanced settling rate in the area of electrode action. Discussion of the design and production capacity of the electric furnace with reference to operating current, power input, furnace dimensions and electrode size are based on considerations derived mainly from slag properties such as its resistivity, viscosity and liquidus temperature.

Jan 1, 2004

By D van der Wal, R Dobbe, K Moeller

"Ore mineralogy and texture are primary variables controlling mill recovery efficiency in flotation plants. However, tracking daily variations of key mineralogical characteristics such as species-by-species liberation is not possible with current on stream analysers and assay lab techniques. In addition, traditional plant mineralogical analysis limited by long data turn-around times from central analysis laboratories typically provides only a time-averaged view of mill performance, e.g. by means of monthly composite feed, con or tailings analysis.This paper presents the results of a development and first field test of an on-site Automated Mineralogy solution (MLA or QEMSCAN) with the specific goal of monitoring recovery variation, ore quality and flotation performance on a mineral species-by-species and day-by-day basis, from up to twelve million direct particle observations per month. The trial was performed at a Pb/Zn-Ag operation in the US from November 2012 to April 2013. The focus of the study was three-fold: to validate the robustness of equipment and operational procedures for daily use by mine site technicians at a remote mine site to develop a methodology to boil down hundred-thousands of Automated Mineralogy particle data from size-by-size con and tailings samples to a couple of numbers meaningful to chief metallurgists to monitor recovery trend changes and correlate these to changes in the feed properties and/or flotation efficiency.The study focused primarily on the Pb/Ag rougher-concentrator circuit. Ten polished blocks of two and three size fractions of con and tailings were prepared by mine site technicians during a daily twelve hour shift. Eight hours of daily measurement time by the instrument revealed an estimate of the dayÆs recovery performance, ore quality and flotation performance for Freibergite (Ag-species) and Galena (Pb-species), within 36 hours from initial sampling. Data quality was assessed by means of calculated versus measured assay reconciliation. Cumulative sum curves of recovery performance, ore quality and flotation performance reveal trend changes with a frequency of 1 to 4 weeks. These were correlated to cumulative sum curves of e.g. locked and slimed particle classes of the mineral species of interest, attempting to identify a possible root cause of recovery performance trend changes. Systematic over-grinding and flotation chemistry issues were the primary causes of below average plant operations during the trial.CITATION:van der Wal, D, Dobbe, R and Moeller, K, 2013. Development of an on-site mineralogy solution for metallurgists, in Proceedings MetPlant 2013, pp 126-132 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Jul 15, 2013

By J. D. Bateman

DURING the summer of 1942 several chromite deposits were discovered in the Lac du Bonnet district about eighty miles northeast of Winnipeg. The deposits are confined to the Bird River complex, a folded composite sill of basic and ultrabasic igneous rocks of early Precambrian age that lies to the north of Bird river (1). The outcrop of the sill represents the trace of an easterly plunging anticline, the south limb extending from the northeast bay of Lac du Bonnet eastward to Bird lake, and the other limb, 6 to 12 miles north, lying between Maskwa river and Euclid lake. The south limb of the sill is 20 miles long, and the northern counterpart 15 miles; but its continuity is interrupted by faulting and by the intrusion of younger granite, so that the total length of outcrop of both limbs does not likely exceed 25 miles. The sill is intrusive into early Precambrian greenstones and associated sedimentary rocks. The chromite discoveries have been made at several localities on both limbs of the sill, and in each case at the same geological horizon. The sill comprises an upper layer of hornblende gabbro and a lower layer of serpentinized peridotite, and altogether is from 500 to 3,500 feet thick. The chromite zone is within and near the top of the peridotite layer, and thus about midway of the sill, both of the limbs of which stand nearly vertical. This geological relationship was established early in the exploration of the initial discoveries and served as the basis for successful predictions of later discoveries. The chromite zone probably persists throughout the length of the sill, but its width and chromite content are not everywhere the same. The initial exploration along both limbs of the sill has shown a combined total length of about 12,000 feet of chromite ore varying in width from 6 to 12 feet. In many places the overburden is thick and obscures the continuity of the chromite zone; but as investigation proceeds the known deposits will be extended and new ones will be found. Thus, although a total length of 12,000 feet of ore has been investigated up to the present time, there is an indicated length of approximately 31,000 feet along which the ore is more than 4 to 5 feet wide. This estimate is based on geological considerations and represents a total tonnage in the order of 15,000 tons per vertical foot of depth.

Jan 1, 1943

By Dale W. Richardson

Ductile hafnium was not obtained consistently by the conventional Kroll process. The bimetal reduction modification produced a more ductile hafnium by lowering the impurities, especially oxygen, in the sponge metal. Hafnium oxide was chlorinated in the presence of carbon to form anhydrous hafnium tetrachloride, which was reduced by sodium and magnesium in an inert atmosphere to produce sponge hafnium metal. After vacuum distillation to remove the byproducts, the sponge was arc-melted into ingot and rolled into strip. Metallic impurities were decreased by evaporating the hafnium tetrachloride from a fused salt. An excessive amount (over 1,200 parts per million (p.p.m.)) of aluminum was contained in some of the hafnium oxide, much of which remained as aluminum chloride in the hafnium tetrachloride during chlorination. Evaporation of the hafnium tetrachloride from a fused NaCI-KCI mixture during the Mg-Na reduction greatly lowered its aluminum content, as most of the aluminum and some of the other metallic impurities were retained by the fused salt.

Jan 1, 1961

By A. Lashgari

Surface coal mining in the Appalachian region consumes a significant amount of energy in the form of diesel fuel and blasting agents. emission of oxides of nitrogen (Nox) from these sources represents an environmental challenge to the mining industry. this paper presents the results of research work related to determination of Nox emission of mining equipment and blasting agents, which is part of a broader industrial project conducted by the Appalachian research Initiative for environmental research (ArIeS). Data for this project are collected from an operating surface coal mine in West Virginia. the research work presented here may be used by mining professionals to aid in quantifying Nox emission and determine strategies for reducing its overall environmental impact.

Oct 1, 2013

By K. Hoover, G. Labarre, S. Rantanen

"As part of the Namew Lake project a mill was constructed to treat 1900 tpd of ore grading approximately 0.90% CU and 2.45% Ni to produce copper and nickel concentrates.Nickel occurs mainly as pentlandite and violarite while copper occurs as chalcopyrite. Two main ore types are present1 lower grade disseminated sulphides in a talcose ultramafic gangue and a higher grade solid sulfide with a granitic breccia matrix.Primary crushed ore from underground is treated on surface in a conventional closed circuit crushing plant using 2-stage cone crushing. Crushed ore is conveyed to storage and then fed at a controlled rate to a grinding circuit employing a rod and ball mill with hydrocyclone classification. Rougher flotation separates and cleans nickel and copper sulfides from waste materials followed by a high lime separation circuit to separate the minerals into final concentrates. Dewatering is achieved through use of high capacity thickeners and pressure filters prior to delivery to a loadout area. The crushing and milling control is highly automated.Plant design was based on metallurgical samples obtained from drill cores. After the first year of operations, plant results compared favourably with design projections.INTRODUCTIONThe Namew Lake Project is a joint venture partnership between Outokumpu Mines Ltd. (Canada) and Hudson Bay Mining and Smelting Company Ltd. (60%). The project included construction of a mine and milling complex to treat approximately 500,000 tonnes per year of copper-nickel ore grading o.91% and 2.44% Ni. Known reserves are estimated at 2. 65 million tonnes. The deposit is located approximately 65 km south of Flin Flon (120 km by road) and about 5 km east of the Manitoba-Saskatchewan border. The decision to construct a concentrating facility was made June 15, 1987 and construction started a week later. The facility, designed for 1900 tonne per day throughput, was ready for commissioning in September 1988. Outokumpu Engineering of Finland was chosen to prepare metallurgical flowsheets, select and develop plant layouts, and provide construction management. Kilborn (Toronto) contributed detailed engineering for civil, structural, mechanical and electrical components and outokumpu Equipment of Canada, the design, the supply, and commissioning of the instrumentation package. Hudson Bay undertook the initial metallurgical test work and preliminary design work."

Jan 1, 1990

By K. Oraee

Mining Ventures are considered as high risk projects and therefore managing the risks is inevitable. Risk assessment is an important part of the complex process of risk management, hence applying appropriated and practical methods for ranking the risks associated with projects, can help to perform a better risk management. In this research the applicability of using Techniques for Order Preference by Similarity to Ideal Solution (TOPSIS) method for risk ranking in an underground mine, extracting by block caving method, was studied. Via this method, the risk associated with reserve estimation ranked as the first while in conventional method (P-I Matrix method) located in the sixteenth. Also there were significant differences in ranks of the other risks. Considering the more criteria, with different weights, in comparison with conventional methods, the results comprised from TOPSIS method are more reliable. By implementing this method risks are ranked better and more realistic and consequently then will be managed more efficient.

Jan 1, 2011

By W. Duyvesteyn, B. Sabacky, T. Spitler, D. Verhulst

"The Altair TiO2 pigment process is based on hydrochloric acid leaching of ilmenite at high-acid concentration. Titanium is transferred by solvent extraction into a high-purity aqueous stream with a high titanium concentration. HCl gas is recovered by pressure-swing distillation and is used to regenerate the leaching solution.A new method of TiO2 recovery in dense film with simultaneous dehydration and hydrolysis provides great flexibility in adjusting the characteristics of the TiO2 pigment product.Modifications of this method lead to a flexible, low-cost, high-tonnage process first for the production of nano-sized TiO2, and later for stabilized zirconia-based nanomaterials and nano-sized titanates.IntroductionProcesses for the production of TiO2 from ore by a hydrochloric acid route have been proposed in the past. Most of these processes dissolve impurities and recover TiO2 as a residue or as a hydrolyzed phase in the original solution (Turner, 1948; Berkovich, 1975; Morris, 1982; Judd, 1986; Chao, 1993). Solvent extraction of titanium after leaching in aqueous HCl has also been studied (Tsuchida et al., 1982; Narita et al., 1983) or at least mentioned as an alternative (Ellis, 1963). A number of small-scale studies on leaching and solvent extraction in both sulphuric and hydrochloric systems have appeared recently (John et al., 1999; Lanyon et al., 1999; Sole et al., 1999. As far as we know, only Kerr-McGee (Morris, 1982) and a plant in India and one in Malaysia use a hydrochloric acid route (20 wt% HCl) to commercially produce synthetic rutile.The Altair process originated in a search for an economical method to treat high-magnesium ilmenite deposits, while avoiding the production of a waste metal salt by-product. The first attempts aimed at producing pure TiO2 by leaching out the impurities. Further work centred on completely dissolving the ilmenite in concentrated hydrochloric acid and reprecipitating TiO2. To decrease the impurity level in the product, solvent extraction of titanium into a purified stream was introduced. It also became clear that to take full advantage of the increase in leaching efficiency provided by concentrated acid, it was necessary to regenerate HCl gas."

Jan 1, 2002

By Tony A. Rorke, Joe R. Brinkmann

The application of instrumentation to better understand and improve production blasting is one of the most fruitful areas of explosives and blasting research. The majority of instrumented studies of production blasting have relied on the extrapolation of far field measurements to postulate blast performance in regions of interest closer to the charge where rock breaking takes place. However, the nonlinear and dissipative nature of the quantities being measured raises serious questions as to the accuracy and validity of such extrapolations.

Jan 1, 1991

In 1953, Dr. N. H. Fisher of the Bureau of Mineral Resources, acting on behalf of the Society of Economic Geologists, which is considering the sponsoring of a uniform system of nomenclature for ore reserves, enquired from the Australasian Institute of Mining and Metallurgy whether it had ever considered this subject and particularly whether it had ever set up any standard definitions or specifications with regard to ore reserves.As this had not been done, but was thought to be desirable, the Council of the Institute appointed a Committee consisting of H. H. Dunkin, Associate, Professor of Mining Engineering, University of Melbourne (Convenor), E. A. Rudd, Professor of Economic Geology, University of Adelaide, I. N. Campbell, Chief Geologist of Western Mining Corporation; and the writer to consider and report on this supject.In December 1953, the Committee submitted its first report to the council and this report (reproduced here as an Appendix) was widely circulated among member companies, and engineers, with an invitation to comment on the proposal. A large number of, replies was received and studied.After studying the replies the Committee issued a second report in part as follows:-From these replies we have learned that the suggestions made in the first teport of the Committee are unacceptable to most of those interested, on one or all, of the following grounds;-(a) number of categories,(b) definition of categories;(c) nomenclature.

Jan 1, 1955