Search Documents

By Terence M. Gordon, Mati Raudsepp, Gregory M. Dipple

Four methods of measuring mineral abundance in a rock are examined for their potential in assaying for high-tech industrial minerals. One method uses X-ray powder-diffraction data and the other three rely on whole rock chemical data and information on mineral assemblages and mineral compositions. All four methods were employed to estimate wollastonite content in diamond drill core of skarn collected as part of an exploration program and are compared to visual estimates of wollastonite content from core logs. These techniques for assaying wollastonite span a considerable range ofaccuracy and expense, and combined, define a non-linear relationship between these variables. Accuracy increases rapidly relative lo expense up to total costs of about $50 per analysis. Assay methods in the $50-100 per analysis range have associated errors of 5-10% relative and probably suffice for most exploration programs. Improvements in accuracy above this level require a much larger investment. The most expensive assay technique (-$300 per analysis) yields the most accurate measurement of grade (relative error -1%). Its application may best be limited to periodic checks on other assay techniques and for fine-tuning ofmineral separation procedures.

Jan 1, 2001

By K. Mayhew, R. Bruce, A. Heidel, G. P. Demopoulos

"Teck and Aurubis are working together to commercialize a technology for the processing of copper arsenic sulphide concentrates that is economic and sustainable with regards to the environment and community. The pressure hydrometallurgical approach is a desirable option as mineral extraction and arsenic fixation can take place in a single autoclave vessel. A test work program was carried out where a range of copper concentrates with varying arsenic grades was processed under CESL leach conditions. This paper discusses the stability character (in terms of arsenic) of the resulting residues and their mineralogy. The basic ferric arsenate sulphate phase (BFAS; otherwise known as type 2) was identified as the main arsenic carrier. All CESL residues demonstrated high stability (<1 mg/L As) through a range of aggressive (pH and ORP) environmental leach conditions.INTRODUCTIONArsenic deportment and control in the copper industry needs an integrated approach involving each stage of the value chain, i.e. exploration, mine operation, refining process and mine closure. Teck Resources Limited (Teck), Canada’s largest diversified mining company and Aurubis, Europe’s largest copper producer, have formed a partnership to advance the application of CESL copper-gold technology for the development of high arsenic bearing copper resources (Bruce et al., 2011).Among the options for arsenic control in the metallurgical treatment of copper concentrates is the precipitation of ferric arsenate, which is widely accepted as the most suitable method for stabilizing arsenic (Ferron and Wang, 2003). The pressure hydrometallurgical approach to processing arsenic bearing copper concentrates is a favorable option as mineral extraction and arsenic fixation can take place in a single autoclave vessel. Under CESL pressure leaching conditions (150 °C, 1380 kPa) high copper extraction and arsenic (V) fixation is possible.Within the pressure leach autoclave, arsenate and ferric iron react to form scorodite type phases. The precipitate formed under CESL conditions is dependent on the Fe (III) /As (V) ratio and the tenor of cations and anions, particularly excess sulphate (Gomez et al., 2011a). Previous studies on CESL residues have found arsenic to be present as crystalline scorodite (FeAsO4.2H2O) (Bruce et al., 2011), basic ferric arsenate sulphate (BFAS: Fe(AsO4)1-x(SO4)x(OH)x·(1-x)H2O, where 0.3<x<0.7), and/or arsenate adsorbed on to hematite (Gomez et al. 2011b). Although not a focus of previous work, scorodite was the predominant precipitate formed when the concentrate Fe/As was <1.5 (Mayhew et al., 2010), and BFAS was the predominant precipitate when the concentrate Fe/As was >10 (Gomez et al. 2011b)."

Jan 1, 2012

By Lifeng Yang, Xiang Zhang, Liang Yuan, Yonghui Wang, Bing Hou, Mian Chen, Rixing Zhang

Large-scale hydraulic fracturing technique has been widely applied to the development of shale gas reservoirs, where the interaction between natural fractures and critical fracture zones has substantial impact on the propagation of hydraulic fractures. Therefore, it is of significant importance to understand and experimentally verify such mechanism. To reach this end, tri-axial fracturing tests were implemented on 400mm×400mm×400mm block samples collected from Longmaxi shale outcrops. The interplay between hydraulic and natural fractures was investigated during the tests, factoring in the role of pump rate in affecting the created fracture network. Based on the experimental results, the critical fracture zone, defined as the weak formation zone nearby the wellbore created by staged pressure implementation that is observed rapid fracture propagation upon next stage of pressure increase, was thoroughly investigated. The analysis illustrates that given the high brittleness of the shale formation, abundant critical fracture zones are generated around natural fractures with pressure building up at a relatively low pump rate. As the pump rate increases, hydraulic fractures initiate and come into play with critical fracture zones, implying emergence of a large number of micro-cracks. A changing pump rate modifies the way of interaction between hydraulic and natural fractures and the subsequent formation of fracture network. Long term fracturing fluid injection with relatively low pump rate below the activation of critical zones is suggested. Also proposed is appropriate timing when applying a specific pump rate that will contribute to the improvement of hydraulic fracture propagation.

Jan 1, 2015

By J. E. Nesset, F. Rosenblum, J. A. Finch, R. Payant

ABSTRACT Under certain conditions of moisture and oxygen, sulphides can spontaneously self-heat. We tested a hypothesis that galvanic interaction between some sulphides can promote self-heating. Galvanic interaction is controlled by the rest potential difference between sulphides and particle size. A series of binary sulphide mixtures was tested. Individual sulphides and mixtures with low rest potential difference did not self-heat, but mixtures of high rest potential difference did. When testing pyrite-sphalerite mixtures, self-heating increased inversely with particle size, with the fineness of the pyrite governing self-heating, indicating the rate-limiting step is the reduction reaction. The results support the hypothesis that galvanic interaction contributes to sulphide self-heating. A possible mechanism based on hydrogen sulphide as an intermediate product is proposed. The understanding gained will be of interest to those involved in storage, shipping, and disposal of sulphides.

Jan 1, 2012

By J. E. Gill

THE 1938 season was marked by a distinct lull in exploratory activity in the Province of Quebec. Quebec was not unique in this respect, but the condition appears to have been more acute here than in most other parts of the Dominion. Various causes may be suggested to account for this. The general disturbance in political and economic conditions throughout the world has certainly had an adverse influence. Uncertainty induced by changes in the mining laws of Quebec in 1937 contributed. A third cause was the belief, now held by many, that the easily accessible deposits in the main producing belt extending eastward from. the Rouyn district have now all been found and that new discoveries in this field will henceforth come more slowly and more expensively. A fourth is the lack of conspicuous success by companies and individuals who have interested themselves in less accessible areas to the north, notably the Chibougamau district. A fifth, the unattractive appearance, as viewed on published geological maps, of the vast area extending northward to Ungava bay and Hudson strait. A sixth, the attraction of such speculative funds as were available to the Northwest Territories, where spectacular finds were reported in the fall of 1937. Whatever may be the relative importance of these causes, languor in exploration will ultimately be reflected in production returns. This appears, therefore, to be an opportune time to take stock of the general position of the Industry in the Province and to consider ways and means of counter-acting those conditions which are now impeding, or will in the near future impede, its expansion. At the request of the Institute Secretary, Mr. Carlyle, I have prepared a brief summary of accomplishments to date and a discussion of some of the geological aspects of the problem.

Jan 1, 1939

By J. L. Jambor, R. W. Boyle

"The Magnet Cove barite-sulphide deposit is a raking pipe-like body that replaced and partly filled a large brecciated zone at the junction of two faults at the contact between sedimentary rocks of the Horton and Windsor Groups of Mississippian age. The principal minerals in the deposit are siderite, barite, hematite, pyrite, marcasite, galena, sphalerite, chalcopyrite, tennantite, proustite, pearceite, acanthite and stromeyerite. The mineral assemblage and textural relationships indicate that the minerals were deposited from low-temperature solutions. The source of the elements in the deposit is believed to be the enclosing sedimentary rocks, with connate or ground waters as the transporting medium, and solubility products as the governing factor controlling the abundance and order of deposition of the minerals."

Jan 1, 1966

By H. P. Kang, Y. J. Feng

The hard roof in underground coal mines is generally considered as a main cause that induces disasters in working faces and entries, such as rock burst and windblast. Hydraulic fracturing technology is an effective approach to weaken hard roof to reduce ground pressure and control rock burst. The state and achievements associated with hydraulic fracturing technology applied in Chinese coal mines are summarized in this paper. Theories related to hydraulic fracturing are of the essence in fracture design to determine the fracture initiation and propagation pressure and predict the geometry and the characteristics of hydraulically induced fractures. Initially, theory of elasticity was employed to determine the breakdown pressure for a vertical borehole where the rock medium is assumed to be elastic. However, porosity and pore fluid have an influence on the borehole breakdown pressure, and then the poroelasticity theory was applied. Arbitrary deviated boreholes in practice are rather common and the maximum tensile stress criterion was employed to determine borehole breakdown pressure. The effect of natural crack in the rock medium on the initiation pressure has been taken into consideration through fracture mechanics. Meanwhile, considerable achievements have been made on hydraulic fracturing tools and equipment, and a set of mature hydraulic fracturing technologies for hard roof control are available. Some comprehensive investigations on the hydraulic fracturing for hard roof weakening are presented, and successful field applications in the Jincheng and Luan coal mining districts are introduced. Finally, the unsolved problems related to hydraulic fracturing are also put forward.

Jan 1, 2015

By A. Takala, H. Cline, D. Girard

"This article describes the project development and successful implementation of a particle sorter at the Kensington mine. The Kensington underground gold mine and associated milling facilities are located within the Berners Bay Mining District on the east side of Lynn Canal about 45 miles north-northwest of Juneau, Alaska. The paper describes the project from concept, through the development phase, including test work confirming feasibility, to a discussion of operational data and includes shared experiences from operation and maintenance. The project has proven successful in recovering gold that was previously lost to the waste dump and has already resulted in a positive return on investment. The payback was achieved in less than one year.INTRODUCTION The first paragraphs of this paper describe Coeur Mining and the Kensington Mine, its history, geology, mining operation and mill. The second part of this paper gives a quick introduction to sensor-based sorting in general and X-ray transmission sorting (XRT) in particular. This article does not cover costs or economic impacts apart from the pay-back period for the investment at Kensington. Interested readers find more in information on this in the literature (Kleine & Wotruba, 2010; Robben, 2013). Since the publication about XRT sorting at TGME in Pilgrim’s Rest (Kleine, Riedel, Ketelhodt, & Murray, 2010), this is the first time that a comprehensive data set on gold ore sorting using XRT is published. Following chapters highlight the aim of the project for Coeur Kensington, project development through testing and operation before concluding. ABOUT COEUR MINING’S KENSINGTON OPERATION Coeur Mining is the largest U.S.-based silver producer and a significant gold producer with five precious metals mines in the Americas employing approximately 2,100 people. Coeur produces from its wholly owned operations: the Palmarejo silver-gold mine in Mexico, the San Bartolomé silver mine in Bolivia, the Rochester silver-gold mine in Nevada, the Kensington gold mine in Alaska, and the Wharf gold mine in South Dakota. The Company also has a non-operating interest in the Endeavor mine in Australia in addition to royalties on the Cerro Bayo mine in Chile, the El Gallo complex in Mexico, the Zaruma mine in Ecuador, and the Correnso mine in New Zealand. In addition, the Company has two silver-gold feasibility stage projects—the La Preciosa project in Mexico and the Joaquin project in Argentina. The Company also conducts ongoing exploration activities in Alaska, Argentina, Bolivia, Mexico, and Nevada. The Company owns strategic investment positions in several silver and gold development companies with projects in North and South America."

Jan 1, 2017

By T. Kerr, C. Mattich, J. Wilson

"In refractory gold concentrates, gold is occluded in sulphide minerals preventing efficient cyanide leaching. Hence, roasting is used to oxidize sulphur and organic carbon, the latter being necessary to minimize recovery loss through the preg-robbing effect. In 2009, Outotec commissioned the circulating fluidized bed roaster at Syama gold mine in Mali. Since 2013 Resolute and Outotec have been implementing improvements to the roaster performance with the capacity increasing from 8000 t/month in 2013 to above 13,000 t/month in 2016, while achieving a residual sulphide sulphur and organic carbon contents of below 0.1 wt.% and 0.4 wt.%, respectively. Thus a gold recovery in the CIL of above 90% is attained. In 2016, Outotec audited the Syama roaster. The analysis resulted in the Low Carbon Roaster (LCR) upgrade concept which (i) allows re-processing of calcine dust from the spray cooler and ESP after pelletization and (ii) allows the roasting of a further fine-organic carbon rich feed, i.e. de-slime circuit tailings. The LCR upgrade aims to reduce organic carbon to <0.2 wt.% and increase roaster-leaching gold recovery by >3%. Project development included extensive testwork. The LCR process is expected to become operational during FY 2019.INTRODUCTION Double refractory sulphide ores exhibit the characteristics of gold locked within pyrite grains, in the presence of preg-robbing natural (organic) carbon. Hence, to achieve high recovery during subsequent processing steps, i.e. cyanide leaching, oxidation of sulphide sulphur is required, producing a porous calcine by way of a roasting step. This allows for the gold contained within the pyrite grains to be accessible during cyanide leaching. Furthermore, it is necessary to oxidize the organic carbon. Oxidizing the organic carbon is essential as gold recovery loss occurs as a result of gold-cyanide complexes being adsorbed on organic carbon, this phenomenon is termed as preg-robbing (Miller et al., 2016). The gold absorbed on the organic carbon is lost, reporting to the tailings stream. Hence, the aforementioned oxidation of sulphide sulphur and organic carbon is the process goal. Nonetheless, the latter must occur at a controlled temperature which is concentrate/ ore specific, since the pores of the produced calcine should not sinter, as this makes the gold contained in the calcine less accessible during leaching, leading to gold recovery loss. The tight temperature control requirement is a decisive factor in the choice of a Circulating Fluidized Bed (CFB) as the roasting reactor, due to the excellent mixing characteristics of the CFB which results in temperature homogeneity of (+/-10°C). Roasting of double refractory ores, as described above, can be included in the flowsheet after comminution and grinding, a process termed as whole ore roasting, or by including a flotation circuit termed as concentrate roasting. Roasting the flotation concentrate results in less solid flow, increased sulphide sulphur grade and organic carbon content resulting in a higher heating value and higher gold content. A typical composition of the Syama ore and concentrate is given in Table 1. Ore average values presented correspond to the period 2015, while concentrate values are typical for the flotation performance throughout the period 2012–2015."

Jan 1, 2017

By S. Jayasekera, A. M. T. S. Bandara, J. Kyle, E. Koenigsberger, L. Koenigsberger

The extraction of rare earth oxides from fluoroapatite rich phosphate concentrates often involves a weak acid leach of fluoroapatite and a sulphuric acid bake of the leach residue followed by water leach and precipitation to obtain an intermediate product. The main aim of this study was to determine and rationalize the solubility of rare earth metal ions in synthetic solutions representing various process liquors at the temperatures 40, 60 and 80oC. The liquors contained different acid and metal ion concentrations with respect to sulphuric acid, phosphoric acid and sulphate salts of sodium, magnesium, aluminium, potassium, calcium and iron(III). A solid of mixed rare earth carbonates was used as the source of rare earth metal ions. The solubility tests and characterization of solids using XRD were conducted at Murdoch University laboratories as part of the process development for the Arafura Resources Nolans rare earth project. The composition of initial carbonate solids and the solids and solutions formed after saturation were analysed for rare earth and other elements at TSW Analytical Laboratories in Perth using ICP-MS and ICP-OES. The precipitated solid in sodium-rich acidic sulphate solutions is the double salt NaRE(SO4)2 based on the solid assays. However, in acidic solutions free of sodium or of low concentrations of sodium the precipitated solid appears to be RE2(SO4)3.

Jan 1, 2014

By R. D. Corrans

"Abstract - Africa is endowed with a number of the world&apos;s giant ore deposits which have contributed significantly to the development of their host countries. Mineral exploration has a long history in the continent, but mining on an unprecedented scale took off during the latter part of the 19th century, accompanied by the development of lines of communication and other infrastructure to service the major mining centres .The ""Winds of Change"" which swept Africa in the 1950s and 1960s brought in new styles of government and economic management to a number of regions, often with demise of economic viability and infrastructure. ln recent years, with the end of the cold war, collapse of communism and changes in South Africa, new opportunities for mineral exploration are opening up rapidly in Africa. However, due to the large cost, long lead-in time, and high risk of developing new mineral ventures in the continent, it is necessary for the host countries to draft realistic and favorable mineral laws and fiscal codes in order to attract, and not deter, potential mineral investors.There will be an on-going role in mineral exploration throughout Africa for the artisanal miner, the smaller entrepreneurs and mining companies, exploration aid programs funded by the developed countries through African governments, as well as the major mining houses who have the resources to develop larger viable mineral deposits."

Jan 1, 1994

By C. Hunt, J. Vivas, D. M. Allen

"In this paper we present the results of a combined remote sensing - numerical modelling study to improve our understanding of groundwater seepage in open pit and natural rock slopes, and to investigate the interaction between groundwater, in-situ stress conditions and brittle fracture. The location of seepage is a key element in the characterisation of rock slope stability in open pits and natural slopes; definition of the fracture network geometry and its inter-relationship with seepage, however, remains a challenge in engineering practice. Current techniques used to characterize groundwater seepage locations require direct access to the rock slope for a detailed and exhaustive investigation, and can be severely limited due to access and the limited coverage of the survey methods both with respect to the height and length of the sampled rock slope. Herein, we describe remote sensing methods, which allow the collection of structural and seepage information over a wide spatial area. Remote sensing techniques are shown to have the potential to provide additional insights into the orientation and general connectivity of fractures that may play a major role in the general stability of a rock slope. A preliminary methodology for the use of remote sensing in the characterization of seepage zones in a natural slope through the application of ground-based LiDAR and Infrared Thermography (IRT) is presented.One of the most challenging problems in rock slope engineering is the realistic simulation of fluid flow through fractured and deforming rock slopes. Deformation and the development of brittle fractures can cause significant local changes in the permeability and strength of the rock mass, potentially affecting rock slope performance. Understanding fluid flow through fractured and deforming rock slopes, especially in highly-stressed environments is of great importance for slope stability analysis. Changes in the interconnectivity of fractures during slope failure are an important, yet are relatively unstudied in rock slope engineering. We present the results of hydromechanical UDEC-Trigon rock slope models focussing on the potential role of brittle fracture in rock slope failure, its interaction with groundwater pressures, and the influence of the assumed in-situ stress ratio. Damage intensity parameters are used to characterize damage within different regions of a biplanar slope failure."

Jan 1, 2015

By Han Xing, Cui Jianzhong, Qin Ke, Shao Bo, Zhang Haitao

In this paper, a new approach that uses hot-top DC casting process to producing multi-alloy ingots is present. The different type and size of composite and coated ingots (4045/3004/4045 three-layer composite ingots with section 630mm by 1500mm and 4045/3003 coasted ingot with F140mm/F110mm in diameter) are cast by this approach. The macro-morphologies and microstructures of the composite ingots, the temperature distribution and the element distribution in the interface zone were investigated, also and the interface bonding strength was measured. Results show that the solid supporting layer formed on the cooling plates plays a key role in the casting process of composite ingots. The solid supporting layer can prevent the blending of two melts by resisting the impact of alloy melt, which ensures the stable casting process and casting high quality composite ingots, because the contact height is increased using hot-top DC casting. In addition, fabrication and properties of 4045/3004/4045 three-layer composite ingots with section 630mm by 1500mm are reported in detail.

Jan 1, 2015

By Mark Hollingworth

"There is general consensus that as the world continues to change at an ever-increasing pace, companies must continually adapt their operations in order to remain competitive. Those that change fast enough, survive; those that don’t, perish quickly. Today, we hear that it is not worth the time preparing corporate business plans as they are out-of-date before the ink is dry. Within the corporate environment of the 1990s, we must “think” strategically, be a “learning organization”, keep our costs low, focus on our core competencies, stay as flexible as possible and create value. So-called “sustainable competitive advantages” can be obsolete before a patent is issued — if its even worthwhile patenting the advancement. This is industry in the 1990s.Now, while all this radical change has been underway in the global industrial environment, what have Canada’s universities been doing to keep pace with the change affecting one of their major stakeholders? Have they adapted their products and services to suit the new market conditions? Have they built closer links to industry to try to understand how better to serve this important client? Do they welcome industry input as to how to redefine their mission, objectives, strategies or their course contents? Do their students graduate with skills ideally tailored for the global mining industry? In the era of communication, can they write high quality reports in English, never mind speak French or Spanish?In an effort to provide Canada’s engineering faculties with a “blueprint” for the future, the Canadian Academy of Engineering pre-pared a report entitled “Engineering Education in Canadian Universities”, published in August1993, which concluded with the following recommendations:"

Jan 1, 1996

By C. J. Edmonds, R. Bland, W. C. Ferguson, R. Whitehead

"In 1969, the Environmental Science Division of James F. MacLaren Limited received authorization from The International Nickel Company of Canada, Limited to carry out a water quality monitoring program in the Lake Shebandowan region of Ontario, where a new base metal mining and milling complex was expected to go into operation in 1972. The objective of the program is to establish base-line water quality characteristics. Fully realizing their corporate responsibility to minimize the effects of the proposed activities on the environment, Inco decided that it would be desirable to establish a program by which any change in the quality of environmental waters will be detected before detrimental conditions ensue, permitting prompt corrective measures to be taken. The program has been in progress for over two years. The waters are sampled and analyzed four to six times per year. Sampling stations are located in Lake Shebandowan and on the adjacent Gold Creek - Matawin River system. On-site analyses and measurements are made of flow, dissolved oxygen, temperature and pH. Samples also are collected for later analysis in the laboratory. These samples are analyzed for a wide range of chemical and biological characteristics. The paper discusses the extent of the sampling program, the techniques utilized and the value of such programs in maintaining the quality of the environment."

Jan 1, 1973

By A. E. Flynn

THERE is at the present time a revived interest in amalgamation, due to the number of mines starting up, usually on high-grade ore, and utilizing this relatively cheap and convenient means of recovering gold, more especially in their initial stages of production. The marked increased use of the amalgamation process has revealed a dearth of amalgamators and there is no doubt the art of amalgamation has stood still for a generation or two and is not readily applicable to the modern practice of milling gold ores. Mill operators of long experience are learning the art for the first time and are giving it intelligent study, and considerable testing and research work is now being undertaken Most millmen consider amalgamation a simple process, and so it is when we have a clean ore with coarse gold, specially when stamps are used for crushing. In treating Nova Scotia ores by stamps and amalgamation, recoveries of 95 to 97 per cent are common and easily obtained. So-called &apos;under-water feed&apos; is almost universally used in Nova Scotia and is quite beneficial. The water is supplied through jets between the dies and below the die surface and maintains this space as a live trap which catches the gold particles before they are overground and spoilt for amalgamation. With this method, the portion of gold recovered in the battery is higher than usual and often amounts to 80 per cent of the total gold in the ore, the remaining 20 per cent being caught on the plate. As a continuous amalgamator, the simple plate cannot be excelled. Some of the modern devices having moving or covered and not very accessible plates, which cannot be readily inspected and dressed to keep them in condition, do not give the best results in service. An exception might be drawn in the case of amalgamation of very heavy ore or concentrate which would bank up unless the plate is carried at such a steep inclination as to weep mercury. Difficulties in stamp-mill amalgamation are encountered when acid water is used or when grease is present. Also, certain sulphides and graphitic and talcose ores give trouble, resulting in poor gold recovery and high mer-cury loss. The older literature on gold milling deals with the common troubles of this type and the old-time amalgamator was well able to take care of day-by-day difficulties. When the difficulties were unsurmountable, the ore was classed as &apos;refractory&apos; and other processes were used.

Jan 1, 1939

By E. Adam, B. Milkereit, M. Salisbury, L. E. Reed, G. Perron

Integrating seismic reflection, borehole geophysical, and physical rock property studies is an effective means of mapping lithological contacts and structures in the crystalline crust. At Les Mines Selbaie in the northern volcanic zone of the Late Archean Abitibi Subprovince, a high-frequency seismic reflection profile has provided the first images of deep crustal structures of this important polymetallic mine site. Physical rock property and borehole geophysical studies confirm that prominent seismic reflections can be caused by lithological contacts, faults and sulphide mineralization. At Les Mines Selbaie, the first two of these are shown by this study. Clearly identifiable reflection images from sulphide mineralization have not been demonstrated in analysis of the profile. The seismic images provide useful information about gross structure in the vicinity of Les Mines Selbaie. They can also place important constraints on the sequence of tectonic events and, therefore, can aid future deep exploration programs.

Jan 1, 1997

By The Staff

"IntroductionThe published information concerning treatment of uranium ores has been very limited as far as Canadian ores are concerned. Such information has dealt mainly with refining processes for concentrates or rich ores, designed to recover radium rather than uranium; these methods could not be economically applied to low-grade ores.The purpose of this paper is to describe treatment possibilities for some of the .ores that have been treated at the Mines Branch, and .to show how the character of these ores influences methods and results.What is a Uranium Ore?Prospecting for uranium has been extremely active during the past two years and a great many occurrences of radioactive minerals have been recorded. Such prospecting has been based to a large extent on the use of the Geiger counter in the fie1d. This equipment is an invaluable aid when the results are properly interpreted.Most definitely, indications of high radioactivity do not always prove the presence of a valuable orebody. First we have to determine:(1) Is the radioactivity due to uranium or to thorium. There is no immediate market for thorium.(2) Can the uranium in the ore be economically recovered.Chemical analysis is the most exact method of determining uranium content, but a fair estimate of the uranium, and also of the thorium, content can be made from the difference in gamma and beta activity. The Mines Branch guards against misinterpretation by determining both beta and gamma activities and, if more than a minor amount of thorium is indicated, then a Chemical analysis is made."

Jan 1, 1950

By M. O. Pekguleryuz, D. S. Aydin

The high temperature oxidation and ignition resistance of Mg-(0-6) wt% Nd alloys have been investigated via isothermal and continuous heating experiments conducted in air atmosphere. Alloy composition is observed to be effective in low levels (~ 0.5 %) in the ignition temperature (Ti) of the alloys; the Ti of pure Mg increased from 630 °C to 770 °C with 0.5 wt% Nd addition. However, no noteworthy improvement was achieved with further additions up to 6 wt% Nd. The initial microstructure was observed to determine the oxide structure on the surface due to the differing oxidation behavior of the phases (a-Mg + Mg12Nd intermetallics). It has been found that the formation of a Nd-depleted region at the subsurface due to extensive Nd oxidation at the oxide/intermetallic interface lowers the protective ability of the oxide scale.

Jan 1, 2015

By P .. H. Grimley, N. Champigny

"Fourteen companies (Appendix) representing senior mining organizations in Canada were canvassed in order to assess: (1) the current usage and trends, and (2) the usefulness of computer applications in ore reserve estimation and grade control. The results of the questionnaire suggest that:• computers are unsurprisingly, predominant in the mining industry for calculating reserves and performing grade control;• time and cost savings are realized;• computer-based approaches are applicable to underground situations;• geological information is incorporated to the computerization process; and• computer usage does not hinder the collaboration of geologist and mining engineer.A clear need is identified for case histories comparing computer-calculated ore reserves and actual production data.IntroductionAmong the management and technical staff of some mining companies there is a perception that the application of computer based technology for the estimation of ore reserves and grade control, has as many drawbacks as benefits. Some of the objections raised against the utilization of computers for ore reserve estimation are that:• computer-based reserve models work for large open pit mines but not for underground situations;• computer-generated reserves ignore the geologist&apos;s knowledge base; they are strictly a number crunching exercise; and• the use of computers for ore reserves hinders collaboration between the geologist and mining engineer.In order to determine (I) the extent of current computer usage and future trends and (2) whether the objections noted above are borne out by experience, a number of senior Canadian mining companies were canvassed.The respondents were asked to provide:• an assessment of the importance of the computer in the ore reserve estimation and grade control process;• the level of involvement of individuals and staff groups with computer-based ore reserve estimation;• the advantages perceived and realized from the utilization of computer-based ore reserve approaches;• the current and future human resources requirements for the evaluation, implementation, maintenance and development of computer-based ore reserve systems;• the hardware and software resources presently used and planned; and• the developments needed to increase the use and acceptance of computer-based ore reserves."

Jan 1, 1990