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By A. W. Jolliffe

AEROPROSPECTING may be defined as the application of the air view to the search for mineral deposits. The term is suggested as a preferable alternative to either aerial prospecting (which may be confused with areal prospecting) or air prospecting. The air view may be obtained by visual observation from an aircraft or by examination of air photographs; each has its particular advantages and disadvantages. Aeroprospecting should be regarded only as an aid to, and not as a substitute for, accepted prospecting methods ( l ). The Precambrian region north of Great Slave lake consists of two well defined physiographic units, a feature first noted by J. T. Wilson (2). The boundary between these lies close to the north shore of the east arm of the lake and extends northwesterly near Spencer, Beniah, Carp, and Ghost lakes (Figure 1). South and west of this line, exposed bed-rock makes up the greater part of the land area; eskers are very rare, and overburden is largely limited to rock-walled valleys and depressions. North and east of the line, outcrops are rare or absent, eskers are abundant, and most of the surface consists of drumlin-like drift hills, elongated parallel to the direction of ice movement (Figure 2). Where this boundary passes through the area shown in Figure 1, it lies near the 1,200-foot contour and may mark the maximum extent of the lake or sea arm present in this vicinity toward the end of the Pleistocene period. For convenience, the first area may be called the 'bed-rock belt' and the other the 'drift belt'.

Jan 1, 1945

By S. W. Marcuson

In the late 1960's concerns about the natural environment reached high levels within North America and provided activists with suitable platforms for exerting influence over the general public and politicians. In response a host of regulatory mechanisms were developed, statutes, voluntary measures, land grants, codes of practices etc. Emerging environmental awareness from the era provided impetus for rapid technological change that encompassed all industries, especially the base metal business. The resulting clean up impacted all aspects of copper production, dealing with issues such as waste disposal, water and air quality with specific impact on emissions of sulfur dioxide and particulate. This paper provides a perspective of these changes reviewing the macro-economic impact of environmental movement in mining with its specific implications to the copper smelting industry. The fundamental challenges that were faced by the old, but capital-intensive North American plants and the approaches taken to deal with the changing times are reviewed with special emphasis on the conceptual approach to smelter S02 abatement and different paths taken in the USA and Canada. The role of economics, sustainable R&D and presence of technical infrastructure that facilitated the change process is elucidated, and speculations are made about the future state of pyrometallurgy and the natural environment. Cu2007 -

Jan 1, 2007

By James A. Finch, Yue Hua Tan, Wei Zhang

"The paper is part of our study of the frother structure-property relationship using bubble rise velocity. Single bubble rise velocity profiles were determined in a 350 cm column for surfactants from the polypropylene glycol (PPG) family. Using velocity at 300 cm, the concentration to reach minimum velocity (CMV) is determined. The CMV is shown to decrease as alkyl chain length (n, number of carbons) increases and as the number of propylene oxide groups (m) increases. Linear correlations log CMV vs. n and m were observed. Taking literature data for critical coalescence concentration (CCC), linear log CMV vs. log CCC correlations were also noted. Mechanisms are briefly discussed, and prediction of CCC made for a commercial polypropylene glycol.INTRODUCTIONAs one of the great enabling technologies of the 20th century, froth flotation is a highly versatile method for physically separating minerals by exploiting differences in wettability (hydrophobicity). Over the last century, flotation reagents have undergone significant developments (Khoshdast and Sam, 2011). One important group of reagents is frothers which are used to reduce bubble size, slow bubble rise velocity and help stabilize froth (Klimpel and Isherwood, 1991).Frothers, originally derived from natural sources (e.g., pine oil and cresylic acid), are largely replaced today by synthetic products which provide more consistent properties. Polyglycols, based on PEO (polyethylene oxide), PPO (polypropylene oxide), or PBO (polybutylene oxide) groups, were first described by Leja and Nixon (1957) and have attracted wide use since then (Farrokhpay 2011). The chemical structure of polyglycols can be represented by a general formula: R(X)mOH, where R = H, or CnH2n+1 and X stands for EO (-C2H4O-), PO (-C3H6O-), or BO (-C4H8O-). The polypropylene glycol ethers (CnH2n+1(PO)mOH) are the most common of these reagents (Pugh, 2007) and the focus of this study.In general, the chemical structure of frother molecules comprises two parts, a non-polar hydrophobic hydrocarbon (alkyl: CnH2n+1) chain and a polar hydrophilic head. By introducing the ether -Olinkage, which acts as another polar site, the propoxy group (-OC3H6-) in the structure makes the frother readily soluble in water (Somasundaran and Wang, 2006), facilitating the industrial use of these frothers. Available as by-products, Dow Chemicals introduced as series of polyglycols, e.g., Dowfroth (DF) 200, 250, 263, and 1012, the most familiar being DF250 (CH3(PO)4OH), a polypropylene glycol methyl ether. While no longer available from Dow, these and other polyglycols are still widely used."

Jan 1, 2016

By A P. Powell

This paper deals with the power plant at Cassiar Asbestos Corporation Ltd., Cassiar, B.C. It discusses the units installed in the plant, the distribution of power and the costs involved. The efficiencies and economics of this power plant are considered to be somewhat better than average. Introduction C ASSIAR Asbestos Corporation's power plant had its inception in 1952 with a 15-by 15-ft. log cabin containing two International Harvester diesel generator sets of 50 kw. total generating capacity. Over the years, it has grown to its present size -an 80 by 82 ft. by 35-ft.-high rigid-frame Butler building housing eight 2,300-volt diesel generating sets, a 2,300-volt distributing switchboard, a 550-volt auxiliary panel, three air compressors, six heat exchangers and other related equipment. The units in the power plant, numbered according to their order of placement, are rated as shown in Table I. The total generating capacity of the plant is 3,673 kw. All of the generators are of the open vertical design except that on No. 7 engine,

Jan 1, 1965

By G. W. Brooks

This short article is quite different to the general run of papers that are presented to the Institute, but no apology is offered because I consider that first-aid and mine-rescue work are of equal importance to many other subjects that are dealt with in our Transactions. Members of the Institute should be as much interested in the safety of persons engaged in the mining industry as they are in the practical methods of modern mining. We must not only do our best to conserve life and property by adopting every known device to that end, but we must also prepare ourselves so that we may take prompt and effective action when life is in danger, or when property is subject to loss. The need for such preparation in Alberta is perhaps greater than in most places where mining is carried on, and we must spare no effort to assemble at every mine men who are well trained in first-aid and mine-rescue work. The large area over which the mines are distributed renders central training stations out of the question, hence the need for local rescue-teams. Hospitals with skilled staffs, close enough to the mines to be convenient, also seem to be out of the question; therefore the greater need of a high standard of first-aid training for the people in our mining camps. The Government mine-rescue cars are supplied with the equipment necessary for training persons in this essential work and also for dealing with disasters should they occur. The question then arises: are there a sufficient number of men who are trained ? If so we can rest assured that what is possible to be done will be done. But if a sufficient number of trained men are not available much loss of life and damage to property is likely to result.

Jan 1, 1925

By John L. Rich

A New Field for the Mining Industry A new field for the mining industry is in prospect. This is the recovery of the petroleum which has been left in the ground in the older oil fields whose yield has declined until they are no longer profitable to operate in the ordinary way. The fact that an oil field has reached the economic limit for operation by pumping does not necessarily 'mean that the oil has ? been exhausted. In many such cases not over one-fifth, or even one-tenth, of the total oil content of the field may have been taken out when this stage has been reached. This means that there exists a large reserve of oil which can be recovered by whatever process best takes advantage of the natural conditions under which the oil occurs. Mine drainage is one of the processes by which this oil may be recovered. Its relative importance will depend partly on the ingenuity and wide-awakeness of mining engineers, and on mining capital. The opportunity is undoubtedly at hand. In order that we may be in a position to judge the possible advantages of mining methods for the recovery of this oil, I have reviewed, on the following pages, the methods now in use, and have discussed the physical conditions of the reservoir rocks in which the oil is found, and the suitability of the various recovery processes, in use or proposed, in the light of these reservoir conditions.

Jan 1, 1927

This document presents estimates of future "total cash cost per ounce" and "minesite cost per tonne" that are not recognized measures under United States generally accepted accounting principles ("US GAAP"). This data may not be comparable to data presented by other gold producers. These future estimates are based upon the total cash costs per ounce and minesite costs per tonne that the Company expects to incur to mine gold at the applicable projects and do not include production costs attributableto accretion expense and other asset retirement costs, which will vary over time as each project is developed and mined. It is therefore not practicable to reconcile these forward-looking non-GAAP financial measures to the most comparable GAAP measure. A reconciliation of the Company's total cash cost per ounce and minesite cost per tonne to the most comparable financial measures calculated and presented in accordance with US GAAP for the Company's historical results of operations is set forth in the notesto the financial statements included in the Company's Annual Information Form and Annual Report on Form 20-F, for the year ended December 31, 2009, as well as the Company's other filings with the Canadian Securities Administrators and the SEC.

May 1, 2011

By G. Vibert Douglas

"Gold occurs in Nova Scotia in three ways, saddle reefs, fissure veins, and fossil placers. Of these the saddle reefs are the commonest. They have been the source of most of the gold and have also been the subject of most of the literature on the gold occurrences.The Meguma or Gold-bearing series of Nova Scotia is a conformable succession of quartzite's and slates, possibly Precambrian in age, which have been folded into a number of anticlines and synclines that strike (Fig. 1) roughly east and west. This folding has been termed Acadian and is probably a westward continuation of the Caledonian revolution in Britain. It may have started in the Ordovician and continued through the Silurian and into the Lower Devonian. It was followed by the intrusion of the great Devonian granite batholiths. It is thought that the mineralization is connected with the late phases of the cooling of the granite. As the name saddle reef implies, the veins form on the crests and flanks of the anticlines, possibly in the synclinal troughs as well. The beds favoured by the solutions are the slates. The reason for this is apparent when it is realized that in order to fold over 30,000 feet of sediments (the thickness of the Meguma according to E. R. Faribault) through p radians of arc it is necessary to have a differential movement between the top and bottom beds of p times the thickness of the sediments. In the case of the Gold-bearing series, in which strong quartzite beds lie between incompetent slate beds, most of this differential movement was taken up in the slates. The evidence for this is the remarkably fine drag folding and the intense shearing and comminution of some of the beds of slate (Fig. 1). The quartzites exhibit some shearing and faulting, but there is little doubt that the greater permeability lay along the incompetent slate beds. The mineralizing solutions followed these beds and also passed from one slate bed to another through a joint or fault in the intervening bed of quartzite. These joining veins are called angulars in Nova Scotia. Within the veins the gold is in shoots and the real problem is to find out what controls the position and extent of the shoots."

Jan 1, 1954

By W. Beres, R. E. Miller, B. Shiari, L. R. Zhao

A dynamic multiscale (MD/FE) method has been used to study dislocation generation and plastic deformation during a nanoindentation process which is physically associated with the generation of heat within the specimen and as a consequence with a temperature rise. Two different techniques are applied to study the temperature effect on the nanoindention process. In the first technique, a global Nose-Hoover thermostat is applied to the entire atomistic region to keep temperature constant during simulation (finite temperature approach). In the second method, the thermostat is applied only on a damping region along the MD/FE interface. Both techniques are able to effectively and efficiently absorb high frequency reflected waves from atomistic/continuum interface. The temperature profile of the atomistic region beneath the indenter is reported and discussed at four different initial substrate temperatures for both techniques. The loaddisplacement (load/unload) curves for different temperature-controlling techniques are compared and discussed. The nucleation and propagation of dislocations in the atomistic region are investigated for both techniques. Correlations between the observed features in the load-displacement curves with the motion and pile-up of dislocations are reported as a function of temperature.

Jan 1, 2006

By H. Vermette, J. Demers, R. Leclerc, P. Bergeron, P. Hudon, A. Lessard

The Arvida Smelter marked its 80th anniversary in 2006. Arvida currently operates 6 potrooms equipped with prebaked side-feeding pots producing 160 000t of aluminum per year, requiring the supply of 300 000t of alumina per year. In the past, to ensure reliable alumina supplies to the pots, especially in winter, a safety stock of alumina was kept inside the plant. The improved reliability of shipping on the Saguenay River has cut the need for such a stock. However, the stoppage of 8 Soderbergtechnology potrooms, starting in the 1980s up to 2003, generated alumina from the cleaning of pot pits, totaling 18000t and leading to the building-up of a significant alumina stock again. Concerns over working conditions, effect on potroom operations, and dust emissions prevented Arvida from tackling effectively this impressive alumina stock. Yet the increasing cost of alumina has created a strong motivation to use the stored alumina. In 2004 Arvida launched a project to recycle the stored alumina. This 4-year project aimed at clearing the alumina stock without affecting the operation of the smelter. It involved changing work organization, improving equipment and controlling the effect of the recycled alumina on the smelting process and working conditions.

Jan 1, 2006

By Sergio Romo, Gerardo Fuentes, Adriana Garcés

Refractory ores with gold entrapped in a sulfide matrix, must be processed in a first stage with chemical or physical treatment in order to liberate the gold for a subsequent step with cyanide. The goal of this research was to compare the refractory behavior of a gold concentrate treated using two pretreatment methods: pressure oxidation and fine grinding. Gold concentrate from Viacha Mining in Bolivia, assaying 50.11 gpt, with a P80 of 131 ?m was used. The concentrate contains arsenopyrite and pyrite as main sulphides in the matrix. A preliminary test with cyanide resulted only 13.5% of gold extraction with 4 hours of stirred leaching. Using an autoclave oxidation with sulphuric acid and 12 bar oxygen pressure at 220°C pretreatment, the cyanide gold extraction increased to 69.0% in 4 hours. When material was ground in a pulverizer, producing a P80 of 20 ?m and the product directly cyanided, stirred leaching gave a gold extraction of 65% in 4 hours. For both techniques, the effect of temperature, sulfur produced in autoclave oxidation, optimization of the cyanide and the nature of residues were also studied.

Jan 1, 2014

By R. D. Brown

"AbstractOver the past five years, tax rates in the Canadian mining industry have skyrocketed upward across Canada, as both federal and provincial governments have sought to increase their share of mining revenues.However, the past few years have not only brought high tax rates to the industry, but also a number of important new federal and provincial tax incentives.In large part, these incentives ~ special credits or reduction in tax for carrying out specific exploration, processing or other activities - have helped to moderate the adverse effects of the higher tax rates and have provided inducements for exploration and processing activities which might not otherwise have been undertaken.However, the effectiveness of certain of these incentives can be questioned: our over-all tax structure now consists in large part of punitively high marginal rates with some extraordinarily generous but capricious tax reductions for specific activities and may not be in the best long-term interest of either the industry or the nation.A rational tax structure, with moderate and stable tax rates, together with reasonable incentives confined to activities specifically requiring them, could be a more effective spur to investment than the present tax and incentive jungleIntroductionIN THE YEARS since federal tax reform, the mining industry in Canada has faced a continued escalation in its tax burdens as federal and provincial governments have leapfrogged each other in imposing new and higher taxes on the industry. The result has been that marginal tax rates imposed on mining and processing activities throughout Canada have jumped to hitherto unparalleled levels."

Jan 1, 1977

By P. A. Riveros

The literature on the arsenic disposal practices of the metallurgical industry and the long term stability of the disposed arsenic compounds were reviewed from a Canadian perspective. The review was complemented with visits to selected operating metallurgical sites to obtain information on their specific arsenic disposal practices and the behaviour of their impounded residues. The arsenic disposal procedure currently favoured by the industry involves the formation of an insoluble ferric arsenate compound which is allowed to sediment at the bottom of tailings or residue ponds. It has been shown recently that this poorly formed crystalline compound is similar to ?arsenical ferrihydrite? which is ferrihydrite containing strongly adsorbed arsenate anions. Despite concerns about its long term stability on thermodynamic grounds, arsenical ferrihydrite appears to be stable for many years in the proper environment which includes a slightly acidic pH and oxidizing conditions. A high Fe/As ratio and the presence of heavy metals appear to increase the stability of arsenical ferrihydrite. High temperature operations, such as those encountered in the autoclave treatment of refractory gold ores, are conducive to the formation of scorodite, FeAsO42H2O, and/or a series of ferric arseno-hydroxy-sulphate compounds depending on the solution composition. Scorodite has several advantages over arsenical ferrihydrite as a disposal compound including a lower iron demand, a higher density and a greater thermodynamic stability. New procedures have been developed to generate scorodite at ambient pressure. These procedures would offer significant reductions in capital cost because of the elimination of the need for autoclaves. Lime precipitation which was widely used in the past is being abandoned as a result of strong evidence showing that calcium arsenate compounds decompose slowly in contact with atmospheric CO2 to form calcium carbonate and soluble arsenic acid. In all cases, the long term stability of the disposed arsenic compounds depends on a number of factors including disposal site characteristics, particle crystallinity and size distribution, the presence of complexing agents and the effect of bacterial activity.

May 1, 2002

By G. H. Hope, D. Green

"Recent process advances at Lac Minerals Est Malartic Division are discussed. The Est Malartic mill treats massive sulphide, copper/gold ore from the Bousquet 2 mine, to produce a gravity gold product, a copper flotation concentrate and a gold precipitate. The mill operation has been improved by the application of Knelson concentrators to replace jigs, the application of Outukumpu high grade tank cells and optimizing the cyanide leach to minimize cyanide consumption.IntroductionThe Est Malartic mill is located near the town of Malartic in the Abitibi Region of north western Quebec. The mill has been in production since the mid- J 930's processing mainly clean, free milling gold ore. Active mining from the Est Malartic mine ceased in 1980 and the mill was switched to custom processing of ore from La Mine Doyon located some 45 km to the west. This custom processing arrangement continued until 1987 when the expanded mill at Doyon became available to process all of the Doyon production. In 1987, Lac Minerals commenced development of a second mine at the Bousquet site located 40 km west of Malartic. This mine, Bousquet 2, is the down dip extension of the La Ronde mine developed by Agnico Eagle. During pre-feasibility evaluations, it was determined that modification of the Est Malartic mill to handle this new ore source was economically more attractive than building a new facility on site. Modifications to the mill to process the high copper/gold ore from the Bousquet 2 mine began in late 1989 and the new circuits were commissioned in mid-1990. Modifications included the addition of both gravity and flotation concentration circuits to recover coarse, free gold and the copper. The existing leach circuit continued operating on the copper flotation tailings with some minor modifications to the solution handling systems. An SO,/air cyanide destruction circuit was also added at this time."

Jan 1, 1993

Mining companies around the globe have long struggled with the need to ensure that earth moving equipment is designed to be operated and maintained under all site conditions without causing harm to people. Incident and accident data from a range of sources clearly identify mining equipment related issues as major causal factors. One Australian source, the NSW Department of Primary Industries? International Mining Fatality Database Project Report (2008) noted that ?Approximately 77% of mining accidents resulting in a fatality have? involved equipment?. The largest number of fatalities were associated with trucks; the next with LHDs. Many of the technical advances in equipment design over the past few decades have not been matched by advances in the human factors design of mining equipment, resulting in a ?design vacuum? that must be filled prior to commissioning new equipment. This ?design vacuum? is generally filled by local dealers. They retrofit equipment according to customer requirements to mitigate risks that have not been designed out by the Original Equipment Manufacturer (OEM). Mining companies have been frustrated by lost time and additional costs associated with this need to retrofit ex-factory designs. Some companies have attempted to address the problem by negotiating company or site-wide ?solutions? to equipment designs, but this has not simplified or clarified the issue from the point of view of the equipment manufacturers. A number of mining companies operating in Australia first discussed the concept of a joint customer approach to improve the Human Factors design of earth moving equipment at the factory level in 2004. They agreed that a new approach to engaging with OEMs was needed; one that would define the ?Problem?, in other words, the basis of the risks, rather than dictate the ?Solution?. The Earth Moving Equipment Safety Round Table (EMESRT) was formally established in 2006 by six global mining companies to establish a process of engagement between Original Equipment Manufacturers (OEMs) and mining customers.

May 1, 2009

By Noel Billette, Jean-Luc Chouinard

"An analysis of the number of industrial injuries shows that the mining sector is particularly affected, since mining is one of the most dangerous industrial activities in Canada. This has led to numerous inquiries, and supports the need for an in-depth study aiming at the identification of factors responsible for these accidents. One possible factor often pointed at is the small crews incentives and this paper presents a scientific approach applied to check a potential link between bonus and accidents at two mining companies located in northwestern Quebec.The data required to do so were the accidents, the salaries and the number of hours worked at each mining site by the hourly paid personnel for the period from June 1979 to January 1982. The analysis of the results derived from the initial information shows different behaviours of the frequency rate vs the bonus rate at these mines. The number of days lost per accident is independent of the bonus rate at both mine sites, as shown by Khisquare tests on contingency tables.IntroductionA wide variety of opinions has been pinpointed by a survey of the literature related to individual or small crew incentives and industrial accidents in sectors of activity where it applies. In addition, various formulae of mining contracts take place in the industry on one part, and statistics from this sector indicate a high accident frequency rate on the other part. These fact s have lead to this scientific investigation which does isolate the direct impact of the bonus on workers' accidents. This study was undertaken with the full support of the Quebec Metal Mining Association.The conclusions of this preliminary phase of the researchproject are presented for two mining complexes in northwestern Quebec. The procedure is somewhat similar to the approach of the Belmoral Commission, with the underlying assumption that bonus has a direct impact on accidents."

Jan 1, 1986

By P. W. Percival, J. J. Janssens

"Whitehorse Copper is a 2600-ton-per-day underground copper mine located within the city limits of Whitehorse, Yukon . In early 1978, due to increasingly difficult ground conditions. it was decided to investigate the conversion from longhole open stoping to vertical crater retreat mining. On-site crater testing by C-I-L demonstrated the feasibility of V.C.R. mining at Whitehorse Copper.After some investigation. a down-the-hole drilling rig was chosen and drilling began in November /978. Blasting began in June /979. and to September 1980 approximately one million tons of ore had been blasted. In-field changes to both drilling and blasting techniques have been implemented. Some of these changes were dictated by problems encountered; others were made to improve efficiencies.To date. V.C.R. mining has proven successful from a drilling and blasting aspect.IntroductionWhitehorse Copper Mines Ltd ., a division of Hudson Bay Mining and Smelting Co., Limited , is a 2600-Lp.d. underground copper mine. The plant site is located I mile west of the Alaska Highway, and approximately 7 miles south of Whitehorse city center. Production is from the Little Chief orebody, and total output is from vertical crater retreat stopes.The Little Chief and Middle Chief orebodies at Whitehorse Copper had original reserves in excess of 6 million tons, most of which graded 2.00/0 copper or higher . The orebodies are typical skarn deposits that have developed along the contact between an intrusive diorite and a limestone-quartzite flank pendant. The limestone has been metasomatized to form a calcium-magnesium skarn which, along the limestone / quartzite contact, has locally further developed into a mineralized magnetite-serpentine skarn. The principal copper minerals are bornite and chalcopyrite, with minor chalcocite and valleriite. Skarn gangue minerals are serpentine, diopside, garnet, epidote, calcite and wollastonite. Appreciable values in gold with some silver are present and recovered as well."

Jan 1, 1981

By E. Viljamaa

In this research, earlier developed information integration method and novel web technologies are applied to intensify infrastructure construction process control. The applied method uses semantic methods to integrate scattered information that is later on exploited by process management using state-of-the-art web technologies. The applied method and web technologies not only improve the process management situation awareness by integrated up-todate multi-source process data but also provide platform independent access and visualization tool for process data. Utilization of such technologies potentially lead on cost savings, make processes safer and also more environmentally friendly. The integration method also enables intelligent queries to the integrated data making possible to use machine based inferring to the data.

Aug 1, 2013

By Philippe V. Scheers

Polycrystalline gold, glassy carbon and gold-activated glassy carbon electrodes were compared for the production of hydrogen peroxide by the cathodic reduction of dissolved oxygen. Gold was deposited on glassy carbon by sputtering with a sputter coater and by electrodeposition from a diluted KAuCl4 solution using short potential steps. The sputtered gold particles were not adherent enough, but there were no adhesion problems with the electrodeposited gold particles. The gold coverage of the glassy carbon surface could be varied by applying a different number of potential steps. The overpotential for the electroreduction of oxygen to hydrogen peroxide decreases with increasing gold coverage of the glassy carbon surface, and for gold coverages exceeding about 16 %, the overpotential is close to that observed on polycrystalline gold.

Oct 1, 2003

By Roy O. Ifill, W. Charle Cooper, Alan H. Clark

"Queen’s UniversityIn representative, run-of-mine samples from the Panel and New Quirke mines of the Elliot Lake uranium district, Ontario, brannerite, ametamict uranous titanate, occurs in microscopic grain-aggregates which display wide variations, both in textural habit and in the relative proportions of brannerite, titania polymorphs and/or “uraniferous titania”. As is widely documented, much of the brannerite occurs as trellis-like arrays of laths and needles pseudomorphing rutile oranatase. In some cases, the laths and needles are cemented by coffinite. Brannerite, with an average composition of (U0.629Th0.039Ca0.20)(Ti2.199Fe0.13)O69contains =3 wt% Th and is distinctly Ti-rich relative to the ideal composition, UTi2O6. Much of the Si reporting consistently in electron microprobe analyses (between 1 wt%and 5 wt%) is tentatively attributed to contamination by the quartz-sericite matrix, and a minor proportion is attributed to the presence of coffinite intergrowths. “Uraniferous titania” (average par-tial composition by weight: 10.8% U, 0.3% Th,32.9% Ti) is considered to represent an intermediate stage in the conversion of titania to brannerite.The leaching behaviour of brannerite in its different modes of occurrence was studied qualitatively by the rotating-disc (polished section) method in H2SO4and HCl solutions at 25° to70°C. Redox potential was not measured. The progress of the dissolution of the individual brannerite crystallites and grain-aggregates was monitored by optical and scanning electron microscopes. Regardless of its morphology and texture (laths or needles, reticulate or blocky),brannerite is not readily leachable. Regardless of the process conditions, the rate-controlling step appears to be the initial leach-pit formation. These pits expand radially through the aggregate as leaching proceeds. This dissolution mode is independent of the relative amounts of brannerite and titania, i.e. the type of grain-aggregate. Secondary coffinite intergrowths are readily leachable and enhance the overall leaching kinetics of brannerite by accelerating leach-pit formation. These data provide, for the first time, information on the controls on the leaching of the uraniferous phases which dominate the lower-grade ores in the Elliot Lake district."

Jan 1, 1996