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By Ellis Clark

THE mining town of Pribram is situated in Central Bohemia, on the western slope of the Heiliger Berg, 30 miles southwest from Prague. Birkenberg, the village in which most of the shafts and ore-dressing establishments are situated, is built on a mountain of the same name. It is about a mile from Pribram, is 1700 feet above the sea, and is surrounded by graywacke rocks of Silurian origin, which are intersected by greenstone dikes, and in the southerly, southeasterly, and southwesterly direction are bounded by granite. The graywacke formations consist on one side of graywacke sandstone and quartzite, and on the other of graywacke slates. These last are separated from the first in the immediate vicinity of the mines by a graywacke seam converted into clay. For many years this so-cal led clay seam (lettenkkluft) was considered as a boundary of the ore deposits in both zones of graywacke. The graywacke formation is divided according to its hardness, structure, texture, and color, into fine, coarse, compact, slaty, whitish-gray, reddish-gray, and black graywacke. The, miner divides the formation into four divisions. The first or lowest division, which is in contact with the granite, consists of a fine-grained dirty gray slate; the -second is a very fine to a very coarse schist, white to reddish-gray in color, and rich in quartz, but containing little mica; the third consists of a slate with a contused cleavage, which has a dirty gray, dark gray, and very often black color and is often graphitic in its composition ; the fourth consists of a fine to coarse-grained graywacke schist, of a grayish-white or reddish-gray color, and rich in quartz. The cleavage in all four divisions strikes from northeast to southwest, and the dip is sometimes northwesterly, sometimes southerly, and often vertical. All four zones are cut through by a great number of diorite and greenstone dikes and chimneys. The thickness of these dikes, which are of

Jan 1, 1881

By Adriana A. S. Felix, Julio C. Afonso, Luiz C. Bertolino, Bruna L. Novo, Fernanda A. N. G. Silva, Karla M. A. Simões

Palygorskite (Mg,Al)5Si8O20(OH)2(OH2)4.4H2O, is a lamellar mineral with a fibrous morphology. The micropores and canals in the structure give a high specific surface and sorption capacity of various kinds of species. Guadalupe’s palygorskite (Piauí/Brazil) run of mine (ROM) was prepared (PA) and characterized by XRD and XRF. PA is composed by palygorskite, kaolinite, quartz and goethite and has 15.8, 58.0, 4.2 and 7.6% of SiO2, Al2O3, MgO and Fe2O3, respectively. Wet magnetic separation tests were conducted with PA obtaining the magnetic and non-magnetic fractions (PAM and PANM, respectively). PANM was characterized by XRD and XRF and the results of the XRF indicated that the iron content in the PA decreased 8.0% in the non-magnetic product. A new wet sieving was conducted with PANM to obtain a purer fraction (−20 μm) (PANMP) which was characterized by XRD, XRF, CEC, Zeta potential, SEM, TG/DTG. The result showed that this mineral could be used as adsorbent of heavy metals.

Mar 1, 2017

By A. M. McKim, J. S. Ambler

"The iron ore of the Scully Mine is upgraded from 36 per cent Fe to 66 per cent Fe through single-stage crushing, wet autogenous milling, sizing by vibrating screens and two-stage spiral separation, followed by a process in which the concentrate is dried and then further improved by high-tension separators. The capacity of the concentrator is 17,000 long tons of concentrate per day. Discussion of the operation will recognize the special problems encountered in handling preponderantly fine ore, relate issues of interest regarding wear and review mechanical innovations found to be advantageous at Wabush. The modern trend toward big equipment, thoroughly instrumented, has been the theme of design. Effects on availability must be a consideration in this choice, and sectionalizing of circuits to minimize these consequences is as important as streamlined maintenance."

Jan 1, 1969

By C. E. Rodgers

WHEN the writer was engaged early last year by Canadian Comstock and its subsidiary, the Metropolitan Electric Company, to act as Consulting Mining Engineer in connection with the layout and equipment of the new ore-dressing laboratories at Laval University, Quebec, the metallurgical laboratory section of the School of Mines building was completely erected, including plastered walls, partitions, etc., and finished concrete floors. At that time, however, no equipment had been ordered, except three Dominion ball-mills and two Bell screening machines. ADVANCED OR CONTINUOUS LABORATORIES The continuous laboratory section of the Department occupies the basement and three floors of the building, with an approximate floor area of 9,000 square feet. Because of limitations imposed by the design of the building (height and arrangement of rooms, strength and design of floors, etc.), modifications of layout from what otherwise seemed most desirable were, of necessity, made. These included: (a) Omission of automatic sampling of the dry ore. (b) Complete elimination of inclined belt-conveyors through floors. (c) Exclusion of bucket elevators for either dry or wet ore transfer. (d) As a substitute for grill-covered drains and floor sumps, drainage from sections or from individual pieces of equipment was piped to a disposal system in the basement. (e) Substitution in several instances of fabricated steel in place of the usual concrete foundations for machinery. (f) Reducing floor cutting and area of such opening to a minimum. Ore storage and chute capacity above the basement level was also minimized to reduce total weight.

Jan 1, 1941

By Donald R. Williamson

The Cyprus Pima Mining Company's open pit operation was started in 1957 with the normal assumption that the ore reserve estimate was accurate within an acceptable range of values. At that tine reserves were law - volume (+10 million tons) and high grade (+1.5% Cu). Several periods of growth have brought the operation to its present production level of 55,000 tons per day of ore and +125,000 tons of waste. Over the years, a number of attempts to refine and polish the ore reserve figures have been made using a variety of established standard procedures. None of these attempts have produced results which are totally satisfactory, particularly when comparisons are made between ore reserve estimates and short to medium range production figures. Other refinements were tried using adaptations of established methods combined with computer modeling techniques. The resulting mine-model ore blocks were an improvement but they still tended to show too match tonnage of mill feed, often at too low a grade. One attempt at Kriging had only limited success. Statistical studies of operations data revealed relationships which could be used to subdivide ore blocks in much the same way as they are actually mined. Comparisons thus far between these newly developed ore blocks and production data show that the new method of evaluation yields excellent results. A new, better procedure for estimation of ore reserves apparently has been developed for the Cyprus Pima deposits. The specific procedures seem likely to have direct application to other, similar operations. The methods used to develop the procedures could be of value to still other operations.

Jan 1, 1976

By Gary Raymond

The Similkameen Division of Newmont Mines Limited operates a low-grade open-pit copper mine in southern British Columbia. The copper mineralization is extremely erratic.As a result, over seven years of operation, ore control methods have evolved from standard flagging based on blast-hole assays, through an in-pit grab sampling system, to the present method of mining to computer-determined ore-waste boundaries based on geostatistics. These improved ore control methods have resulted in a gain of at least 25% on ore tonnage miffed, at the same grade as obtained using earlier techniques. At the same time, geostatistical ore reserve estimates are now within 7% of milled ore tonnage and grade on a yearly basis, whereas the original polygon ore reserves under-estimated mineable ore tonnage by 15% to 45% and over-estimated grade by about 20%. The author discusses why traditional ore estimation methods give poor results in erratically mineralized orebodies and describes the geostatistical approach to the problem.

Jan 1, 1979

By Augustus Locke

WHY should I, a geologist, be coming before you to talk about finding ore? Certainly, the great discoveries of the past have not been made by geologists, but by men of very different tastes and training. If, in the year 1800, the course of ore discovery could have been foreseen, there would have been no reason to put it into the hands of geologists or other men of technical preparation. It was not geologists but explorers, Indian fighters, prospectors, manual laborers, and hardy financiers, who initiated the American mining industry. Then why this association of geological technique with ore finding? Why this feeling that the way to find ore is to apply to the problem what we call geo- logical principles? Well, to put it broadly, the old method has run out on us. It no longer works. Or, to put it another way, the cost of finding ore by the old method has mounted so high that one old district after another has become, practically speaking, dead, and various other old districts that are still going apparently at full strength are actually beginning to limp, and, with the cost of discovery mounting yearly, to fear, more than they will acknowledge, that the end is approaching.

Jan 1, 1926

By T E. Jeffries, M Zentilli, J STguel, C C. Wilkinson, B G. Rusk, V H. Vry

Laser ablation Inductively Coupled Plasma Mass Spectrometry (ICPMS) analysis of fluid inclusions trapping mineralising solutions in major porphyry-copper deposits indicates that copper concentrations can reach 103 - 104 ppm in both dilute, CO2-bearing fluids and in high salinity brines. Non-Cl transport of Cu is implicated. Au has been determined at 0.2 - 0.4 ppm in the low salinity fluids and may be co-transported with Cu. In contrast, high concentrations of Fe, Mn, Zn and Pb are only attained in brines and correlate strongly with Cl-indicating chloride transport. Physical and/or temporal separation of these fluid types can therefore producemetal fractionation within porphyry systems. Evidence concerning the behaviour of Mo is less clear but brine transport appears to be favoured; phase separation is one mechanism that may account for the fractionation of Mo from Cu and the formation of quartz-molybdenite veins. An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation.

Jan 1, 2008

The present study investigates the nature of gold mineralogical distribution and association in a Cu-Au flotation circuit (1.6 g/t Au, feed head grade). The approach used in this study involves a combination of bulk gold assay and quantitative X-ray diffraction (QXRD), on a size-by-size basis, followed by QEMSCAN analysis on the -75+53 µm, -53+38 µm and -38+20 µm size fractions. The QXRD and QEMSCAN analysis showed that gold mineralogy is complex and fine-grained in the flotation feed, particularly in the -38+20 µm size fraction. Gold and pyrite concentration follow each other closely, suggesting gold-pyrite association. Quartz as the major gangue mineral shows a bi-modal distribution with respect to particle size. The identified gold particles were completely locked (~94 %) in pyrite as fine inclusions and 6 % locked as complex aggregates (-75+53 µm size fraction) whereas in the -38+20 µm size fraction, the identified gold grains occur as fine inclusions (~1-3 µm) within pyrite and silicates. However, in the intermediate size fraction (-53+38 µm), 75 % of the identified gold grains (10-22 µm) were over 90 % liberated and 25 % associated and locked in pyrite and complex aggregates (~2-4 µm). The identified gold grains in the -53+38 µm size fraction occurred as native and electrum with varying silver concentration between 8 and 20 % by weight. In the -38+20 µm size fraction, a gold telluride was also identified. Based on the mineralogical analysis of the feed, possible flotation strategies are discussed. Optimizing the flotation of pyrite is suggested as the primary Au recovery strategy. Keywords: flotation, pyrite, gold, liberation, QXRD, QEMSCAN

Sep 1, 2012

By Richard V. Wyman

The genesis of ore deposits has been tied to plate tectonics through differential petrogenesis in subduction zones. However, many mineral districts, especially in the Basin and Range province of United States and Mexico, appear unrelated to any possible subduction zones or to plate boundaries. It is proposed that the pattern of mineral belts is related to mantle plumes which have been overridden by an advancing continental margin.

Jan 1, 1976

By M A. Knackstedt

Coupling between deformation processes and rock permeability is a major factor influencing the architecture of fluid migration and the localisation of ore deposition in several types of hydrothermal ore systems in middle to upper crustal regimes. Permeability in many hydrothermal systems is controlled by a dynamic competition between deformation-induced porosity-creation processes and porosity-destruction processes. Localisation of deformation within faults, fractures and shear zones leads to flow localisation, with large-scale flow systems forming when active faults and shear zones link to create percolation networks. Numerical modelling techniques are used to explore the growth of fracture networks and evolution of network connectivity during progressive deformation. Initial results indicate that networks reach a percolation threshold at very low strains. Near the percolation threshold, flow is localised along a small proportion of the total fracture population and favours localised ore deposition. At higher strains, flow is distributed more widely throughout the fracture population and may provide reduced potential for production of high-grade deposits. The distribution of mesothermal gold deposits along a small subset of the total population of co-active faults and shear zones in the Archaean Yilgarn Craton in Western Australia indicates that some hydrothermal systems maintain themselves near the percolation threshold for a substantial part of the lifetime of the system. Fluid-driven growth of fault/fracture/shear networks may lead them to self-organise near the percolation threshold.

Jan 1, 1999

By Jackson M. Langton

INTRODUCTION The Morenci-Metcalf district is located on the southern slope of the white Mountains in Greenlee County, Arizona. Both porphyry copper deposits are four to six miles northwest of Clifton, the county seat, and the new Metcalf mine is situated approximately one mile northeast of the Morenci open pit (Figure 1). Chase Creek, a south-flowing tributary of the San Francisco River, dissects the district and separates the two ore bodies. More than 1,200 exploration and development drill holes have been completed in the district and the Morenci-Metcalf ore bodies have been delineated on a 400-foot grid. Recently initiated drilling programs have revealed new data about deeper protore and associated hypogene alteration. This information, correlated with surface mapping and petrographic studies, was utilized to propose a plausible geochronologic sequence for this region. The reasoning behind this study has been helpful in locating new ore beneath leached capping indicative of only protore mineralization. The scope of this paper is to establish a practical solution to a highly theoretical problem of ore genesis and to familiarize the reader with stratigraphic, structural, and mineralogic events responsible for localizing ore in this district. Continued research will possibly alter the proposed time span and relative displacements, but it is doubtful that the order of events will vary significantly. Geochronologic conclusions are therefore presented as general hypotheses and additional geologic mapping,

Jan 1, 1972

By Jackson M. Langton

Substantial evidence supports the theory that high-angle faults and overthrusts in the Morenci-Metcalf region were initially caused by a Late Precambrian-Early Paleozoic stress field. These faults were reactivated in Late Paleozoic-Early Mesozoic time which completed the structural framework prior to the Laramide Orogeny. Excluding an interruption by diabase dikes and sills, Paleocene-Eocene magmas invaded the pre-existing structures and became progressively more sialic in composition and nearer to the surface with each subsequent injection. The last sialic intrusion was highly explosive, rendering the country rocks more permeable for hypogene and supergene activity. Widespread dilation, instigated by uplift and subsequent magma intrusion, caused extension to the northwest and southeast. A major locus of hypo gene alteration and mineralization appears to be centered around the south and southeast periphery of the youngest granite porphyry stock. A potassic, sulfide-deficient core is telescoped by a pyritic, phyllic zone which in turn is enveloped by widespread propylitic alteration.

Jan 1, 1974

By Savage E. N

Two genetic types of base metal deposits occur in the Wainivesi area of central eastern Viti Levu. The Wainivesi deposit is now considered to be a stratiform volcanogenic type, and the Wailotu and Wainiviti deposits are described as contact metasomatic with some hydrothermal manifestations. The Wainivesi mineralization is correlated with the Tertiary "e" stage, i.e. uppermost Oligocene-Iowermost Miocene. Tertiary "e" stage rocks in Fiji are therefore potential ore producers of stratiform volcanogenic type. On the basis of plate tectonics with Fiji part of the New Hebrides Arc prior to rifting apart in the late Miocene, stratiform volcanogenic deposits of the Wainivesi type may also occur in rocks of comparable type and age in the New Hebrides.

Jan 1, 1976

By Graeme Miller

The geotechnical characteristics of the ore are important in understanding the kinetics of a copper heap leach. These characteristics can indicate potential problems and can be used to determine the semi-quantitative changes in field kinetics as compared with column kinetics. The application of this approach allows a more rigorously based determination of ?scale up factors? than has been the case the date. The shrinking core model has been shown to be a poor predictor of leach kinetics based on the crushed ore size distribution. However the model itself is a very useful tool to analyse commercial heap data. Significant geotechnical parameters such as: bulk density / stress characteristic, limit moisture capacity and particle density are used to determine the effect of changes on the diffusion controlled leach rate. By consideration of the geotechnical reaction of the ore mass the leach rate changes are related to changes in these variables. Analysis of commercial heap data has indicated effective diffusion lengths of up to ten times the largest particle size.

Jan 1, 2003

By D. J. Shalanski

In 1962 a computerized data processing system was first installed and programmed for the grading of direct-shipping iron ore from the Sept-Iles terminal of the Iron Ore Company of Canada. Over the years several changes and improvements have been incorporated into this system. It is the purpose of this paper to describe its present operation and features. Sept-Iles is located on the north shore of the St. Lawrence River, 500 miles north east of Montreal. The direct-shipping ore is received by railroad from Schefferville, 320 miles to the north in the Knob Lake Iron Range of New Quebec and Labrador. The shipping season extends from mid-March to December. The maximum tonnage handled in this period being 13,045,000 long tons in 1959. Crude ore receipts for 1974 amounted to 6,568,000 tons of direct-shipping and 4,700,000 tons of plant feed material from Schefferville. This was augmented by 4,447,000 tons of concentrate and 7,572,000 tons of pellets from Labrador City 200 miles north of Sept-Iles. The direct-shipping ore has come from as many as ten mines, and grade variations, even-within the same mines, have been sufficient to require blending for uniform, acceptable cargos. Shipments of low phosphorous, non bessemer and manganiforous iron ore are made, to Canada, the United States, Europe and Japan with grade variations to meet customers requirements.

Jan 1, 1975

By Dhar B. B, Gupta R. C

Grinding of iron ore is an essential step to utilise ore fines for pelletisation needed for DRI units. While preparing iron ore pellets for DRI production, the iron ore needs extensive grinding which is highly energy consuming step causing the process to become non-viable in some cases. In the present paper an attempt has been made to evaluate grinding performance of thermally treated ore compared to normal ore grinding. Such thermal pre-treatment has been found to reduce the energy requirement with lower consumption rate of grinding media. It has been observed that by applying thermal shock the ore is rendered weak with improved grindability. The stresses generated due to thermal treatment may extend existing micro-cracks in the ore and in some cases it may even nucleate fresh cracks. Experimental studies carried out on thermally treated hematitite ore reveals that the heating to 400¦C followed by water quenching can cause a reduction of 45 per cent in grinding energy. The paper gives the details of the experiment and the Results.

Jan 1, 1999

By J. Sanchidrián, A. Fernández, P. Segarra

The combination of chemical analysis techniques as XRF and measurement-while-drilling (MWD) technology in underground mining is a novel approach to gather comprehensive on-line information about physical and mineralogical data. In this work their integration is investigated aiming to delineate the ore/waste boundary. The input data analyzed come from a narrow vein underground mine, where the ore correspond to fluorite, and gathered in two production levels with complex mineralogical characteristics. Two approaches are followed to build a generalizable classification methodology and a site-specific model: a k-means clustering heuristic algorithm to define rock classes based on their physicochemical features, and a machine learning (ML) ensemble model trained with drilling parameters. For an imbalance class problem, a good recognition is obtained for the ore when is related to a high content of silica and for the waste. To predict the ore with low silica content it is necessary to integrate an analysis-while-drilling method to recognize the fluorite content when this mineral is embedded in different rocks. MWD can be employing for the lithologies recognition when representing different structural and mechanical properties between them.

Jan 1, 2024

By Chuck Edwards

"The development of two large, high-grade uranium projects has been proposed for northern Saskatchewan. The projects are now under review by a joint federal/provincial panel. The McArthur River project is owned by the McArthur River joint venture (Cameco Corporation 53.991 %, Uranerz Exploration and Mining Limited 29.775%, Cogema Resources Inc. 16.234%) and operated by Cameco. Cameco proposes to mill the McArthur River ore at the existing Key Lake mill. The Cigar Lake project is owned by the Cigar Lake joint venture (Cameco Corporation 48.75%, Cogema Resources Inc. 36.375%, Idemitsu Uranium Exploration Canada Ltd. 12.875%, Korea Electric Power Corporation 2.000%). The Cigar Lake joint venture proposes that Cameco operate the Cigar Lake mine for the owners, and that Cogema mill the ore at their McClean Lake mill, now under construction. Proposed systems provide safe mining and ore handling, and allow the milling of McArthur River ore at Key Lake and Cigar Lake ore at McClean Lake. This avoids the disturbance of new sites for milling and tailings disposal.The McArthur River and Cigar Lake deposits are the largest known high-grade uranium deposits in the world. The ore grades at McArthur River and Cigar Lake are at least 100 times those that are mined elsewhere. It is proposed to mine these deposits using remote underground mining methods, to crush and grind the ore underground, to pump a thickened ore slurry to surface, and to transport it in special containers by truck to the mills.During all mining and processing stages the ore is fully contained. Radon emission is controlled by positive ventilation of all process vessels, with the process ventilation backed up by the primary mine ventilation system. Radiation is controlled by heavy steel pipe and vessel walls, concrete walls and sometimes lead sheeting."

Jan 1, 1997

By A. Y. Senchenkoa, Y. V. Kulikov

The relationships revealed between ore hardness and specific energy consumed by crushing and grinding are described in the paper. A comparison of key technical and economical parameters of SAG and HPGR circuits is made, based on testing of several ore types for greenfield projects. The comparison of results make it possible to estimate efficiency of the technologies application, depending on ore hardness and taking into account potential risks for a circuit under design. Keywords: Comminution circuits, SAG, HPGR, test results

Jan 1, 2020