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By S. Banisi, J. Marois, A. R. Laplante

"This paper compares the behaviour of gold and ore in the grinding circuit of Hemlo Gold Ltd. Particular attention is given to grinding kinetics, classification behaviour, and liberation. For grinding kinetics, laboratory grinding of gold flakes and silica, 840-1200 um in size (14/20 mesh), was also performed to provide a standard for comparison and to study in a controlled environment the mechanisms of breakage, folding, smearing and impacting.Grinding kinetics were characterized at laboratory scale with breakage and selection functions. The breakage function showed that 75% of gold disappearing from the 840-1200 um class reported to the 600-840 um; this figure is much higher than for silica ( 46%) or most other minerals, and implies that comparatively fewer fine fragments are produced from the breakage of gold flakes, on account of gold's malleability. The selection function of silica was four times that of gold. At plant scale, the ratio of the selection function of ore and gold increased from 6 for at 50-100 um to 20 at 500-1000 um.Observation of original flakes and their fragments with the scanning electron microscope showed that the main mechanism of ""grinding"" from the 840-1200 um to the 600-840 um class was folding rather than actual breakage. This was confirmed by a measure of individual flake weight. The postulated breakage cycle is that relatively globular flakes become increasingly serrated through grinding; they can then regain their original shape through folding and reflattening into cylindrical and spherical shapes, as the majority does; however, some fragments will at this point undergo actual breakage. Photographic evidence is presented to support the proposed mechanisms.Smearing of gold unto silica was observed when silica was ground after a gold, and embedding of silica into gold flakes when gold was ground after a silica. Both mechanisms occur whenever gold and harder minerals are jointly ground, and result in ""unliberation"" of gold. It is postulated that smearing of gold onto other minerals plays an important role in explaining how gravity recovery can increase overall gold metallurgy, especially when used ahead of flotation.Classification of gold in the primary hydrocyclones takes place at a much finer cut-size than ore, 20 vs. 57 um. This and the slower grinding kinetics result in high gold circulating loads in the primary loop, 6700%, and a gold content in the primary cyclone underflow (PCUF) is twenty four times that of the ore. The gold size distribution for primary cyclone overflow is much finer than that of the ore, although they are essentially similar in the PCUF.Liberation, or more accurately ""gravity recoverability"", was assessed with a 7.5 cm (3"") Knelson concentrator. It varied between the thirties for the primary mill discharge and two cyclone overflows, to highs of 89 to 92% for the PCUF and secondary mill discharge, 89 and 92%, respectfully."

Jan 1, 1991

By G. S. Dobby, J. A. Finch

"I. INTRODUCTIONA significant development in flotation over the past few years has been the increasing industrial use of flotation columns, primarily in Canada. The column differs dramatically from conventional mechanical flotation machines, both in design end operating philosophy, which has been a principal reason for its slow acceptance by the mineral industry. Boutin, Tremblay and Wheeler (1. 2) developed the concept in the early 1960's and since then plant and laboratory columns have been marketed commercially by Column Flotation Company of Canada Ltd. In 1980-81 at Mines Gaspe, Quebec, three columns replaced 13 conventional cleaners in a molybdenum upgrading circuit, with superior results (3). Since then many of the copper producers in British Columbia have installed columns for copper and molybdenum cleaning, including Gibraltar, Lornex, Highmont and Island Copper. There now appears to be widespread interest in flotation columns.The column is particularly attractive for applications involving multiple cleaning stages and can upgrade In a single stage compared with several stages of mechanical cells. This results in simpler, more controllable circuits. Importantly, the column itself is well suited to computer control. A significant problem, however, has been that of translating laboratory data to plant performance. The purposes of this communication are to address the problem of column scale-up and to describe some of the transport mechanisms of a flotation column, leading to a kinetics based model.A schematic of a flotation column is shown in Figure]. Industrial columns are up to 13 m high and 0.3 to 1.8 m in cross section (either square or circular). Three zones can be identified:a collection zone, with feed entering 2 to 3 m below the top of the column and descending against rising bubbles generated at a gas sparger; a washing zone, where a packed bubble bed is generated by a downward flow of wash water; and a conventional froth (2 - 5 cm thick), the sole purpose of which is particle transport to the launder. The tailings withdrawal at the bottom of the column is controlled at a rate slightly greater than the feed flowrate (called a positive bias).An important element is the washwater, added just below the froth zone. The component of the washwater that flows downward (to make up the bias) is sufficient to prevent coalescence of rising gas bubbles. The packed bubble beg so generated is very efficient at suppressing gangue entrainment to the concentrate."

Jan 1, 1985

Burr Mineral Resource has: ?Grade / Thickness / Tonnage ?Dry Caprock ?Low Carnallite ?Low Clay / Insolubles ?Flat & Continuous Deposit ?Proper depth

May 1, 2009

By L. K. Walker, G. A. Kosick, P. D. Young

"MillEX is an information management system designed by mineral processors for mineral processors. The system utilizes ""cutting edge"" software technology to gather and store all automatically and manually recorded data from the plant operation and laboratories. This data is delivered to the desk of superintendents, metallurgists, technicians and managers, and permits the user to query, correlate, graph, report and present this data in minutes. In the past this task would have taken days and even weeks of tedious work to complete.MillEX allows the engineer/analyst to quickly develop a very thorough understanding of the complex relationships of process variables and equipment that exist in the plant, and their effect on product quality and quantity. The time and resources that are currently wasted on duplicating data entry will be an effort of the past.This paper describes the structure of MillEX and how it conforms to the needs of mineral processing personnel.INTRODUCTIONPicture a personal computer on your desk which will carry out the following commands:1. Plot a graph over the last six months, using weekly averages, of percent minus 200 mesh material in the primary cyclone overflow.2. Overlay this graph with a graph of concentrate grade versus recovery over the same time period.3. Retrieve a prior month end report, update all operating supplies tables and metallurgical performance with this months data, and embed the graphs created above.4. Edit text and print the current month end report. This is only one example of the type of power MillEX isbringing to the mineral processing industry."

Jan 1, 1992

By Jack J. Ayotte, Michael R. Nadon

"Today's demand for better and more efficient methods inspires new approaches to construction and mine development.A project at Asarco's Aquarius Mine provided a challenge that resulted in the adaptation of a civil construction technique to a mining application.This paper describes the construction of an escapeway shaft to surface from the mine's 150m level. The prime consideration was to provide the most cost-effective method of establishing a shaft collar in the 145 ft (44 m) of water-bearing overburden. This problem was resolved with the employment of the drilled in-caisson method.The remainder of the 500ft (152m) deep shaft was raise bored and portable hoisting equipment was used to install a permanentmanway and shaft liner.IntroductionHaving completed the first phase of exploration development in 1982, J.S. Redpath Limited was engaged to carry out an engineering and cost study to investigate the feasibility of re-opening Asarco's Aquarius Mine near Timmins, Ontario. The scheme was to develop the proven ore reserves and proceed with shrinkage stoping while carrying out further exploration development and diamond drilling.One significant and costly component of the project was the provision of an escapeway shaft to supply additional ventilation as well as a second means of egress from the mine. The major complication to this task was the presence of 145 ft (44 m) of water-bearing overburden at the site. The first and obvious approach was to use conventional ground-freezing methods as had been employed previously on .this property for the initial development shaft. This being the only ""sure"" method available at the time of the budget estimate, it was used as a basis for the study but its considerable projected cost and time demand inspired further investigation into other possible solutions.After considerable research and several brainstorming sessions, a Redpath team came up with an approach whose basic procedures had been used extensively in the civil construction field, although they were novel to the mining industry."

Jan 1, 1987

By J. A. L. Henderson

THE potential oil-and gas-bearing area with "which this paper deals is the large undefined Carboniferous basin, roughly triangular in shape, occupying about 10,000 square miles of southern and eastern New Brunswick. Its base, about 135 miles long, lies on the gulf of St. Lawrence and embraces the whole eastern coast-line of the Province, while its apex lies in the south-west corner of the Province, near the International boundary (see map, Figure 1). The Carboniferous basin may be divided roughly into two areas-the Northern basin and the Southern basin-by a structural feature represented by a ridge of low hills running north-easterly from the Saint John river, near Saint John, on the southwest, to Indian mountain, about eight miles north of Moncton, in the northeast. Within the Northern basin, all evidence regarding the presence or attitude of the older Mississippian Albert Shale series, the only oil-bearing rocks known in New Brunswick, is for the greater part obscured by a thick and practically horizontal blanket of Pennsylvanian strata and, although evidences of oil and gas have been reported, none has been positively identified. Five parallellines of gentle folding, running to the northeast, occur in the Pennsylvanian rocks, within a distance of 100 miles from north to south. This folding is reflected in the courses of the rivers, which lie within the synclines. The relationship of the folding in the younger rocks to structures in the uncomfortably underlying older rocks is unknown, but should now be possible of clarification by means of a geophysical survey accompanied by drilling. Independent geological examinations have yielded no evidence of value in this respect, nor have five exploratory boreholes drilled by per-cussion tools to a maximum depth of 3,645 feet been of assistance, as only one inconclusive hole completely traversed the beds which normally overlie the Albert shales.

Jan 1, 1940

By Sir Stopford Brunton

Gold was first found in Nova Scotia about 1830-40, but its significance at that time was not appreciated. Probably the first discovery that resulted in any work was made by Lieut. C. !'Estrange, at Mooseland, on the Tangier river, in 1858.1 Since that time gold has been mined with varying success until now, and from 1868 onwards work has never altogether ceased. Gold mining in Nova Scotia is at the moment under a cloud, and the idea generally accepted by most people is that it has failed in the past, and that there is no prospect for it in the future. The actual reasons for the present situation have never been carefully analysed, and it seems a good thing to see what really is the state of the case and whether or not this general idea is worthy of credence. It is the purpose of the present paper to analyse the situation in the light of present knowledge, and to set forth some data which may assist in the future development of the Province.

Jan 1, 1926

By Paul Staples, Fred Woodcock, Robert Grant, Mike Cooper

"Noranda's Brunswick Mining Division, near Bathurst, New Brunswick, processes 10,500 TPD of complex Cu-Pb-Zn bearing ore. Brunswick uses conventional rod and ball milling techniques to achieve a flotation feed size of 75% passing 400 mesh. Over a two year period, testwork was performed using a Marcy pilot plant ball mill to assess the impact of several key variables on secondary grinding efficiency. Four graded mill charges were used to compare balls and slugs at 25 and 29 mm sizes. Data was evaluated by determining grinding rates using a commercially available steady state simulator. Results were critical in Brunswick's efforts to achieve finer grinds while minimizing cost per tonne.IntroductionBackgroundThe Brunswick orebody is an extremely fined grained volcanogenic massive lead, zinc, copper, silver, iron sulphide body between two metamorphosed sedimentary and felsic volcanic rock units. Pyrite content is about 60% with 20% non-sulphide minerals, mainly silica and chlorite.Size reduction at Brunswick is performed by three separate parallel lines consisting of rod mills, primary and secondary ball mill circuits, all in series. The line 3 grinding circuit is presented in Figure 1."

Jan 1, 1997

By G. D. West, J. D. Purdue

"Marked Ball Wear Testing (MBWT) employs identified grinding balls which are placed in an operating mill for a period of time, retrieved from the mill, and then measured to determine the amount of wear experienced. This is an excellent method to evaluate the relative differences in the wear rates of various grinding ball materials and/ or manufacturing process variables simultaneously and under actual production milling conditions. This paper outlines the methods of ball identification, testing and evaluation procedures and discusses the strengths, weaknesses, and proper application of marked Ball Wear Test results. INTRODUCTIONThe consumption of grinding media in the mineral processing industry represents a substantial cost to the comminution process. Grinding media is most often found to be the second highest consumable cost next to energy. To determine the selection of the most cost effective media, one must determine the specific wear mechanisms present in a given grinding application and decide which media system addresses these mechanisms most economically.A MBWT has definite advantages over other methods used to evaluate the relative consumption rates of grinding media. It allows the comparative testing of a large number of different ball types under identical operating conditions in a very short period of time. In addition, production wear rates can be accurately predicted directly from MBWT results. Typical MBWT test periods are in the order of 350 to 700 operating hours for high wear rate application and upwards of 2000 or 3000 hours for low wear rate applications. These times are much less than the 5000 or more hours required to purge a mill of the incumbent ball charge (to convert it to the test ball) and then provide even a minimal test period in which to conduct a full production test, for just one type of ball. Under production test conditions the evaluation of competitive product or the development of improved grinding balls is necessarily slow."

Jan 1, 1991

By J. Kazakoff

"The success of gold recovery at the Jolu gold mill depends on many variables. The most important ones are the people, the ore body, plant design parameters, equipment selection and cost control. This paper will briefly hiqhlight the above, the main focus, however will be on the gravity gold circuit.The gravity circuit requires judicious operator attention in order to operate properly. In return the circuit gives immediate visual results for mill peopleIntroductionThe development of the Jolu property to the production stage was carried out quickly, efficiently and economically. The property became a gold producer ahead of schedule and under budget.The Jolu property is a joint venture between International Mahogany Corp., a 70% partner, and Corona Corporation, a 30% partner. Corona Corporation operates the Jolu Gold Mine, located 140 kilometers north of LaRonge and 520 kilometers north of Saskatoon."

Jan 1, 1990

By Daven N. Compton

The optical properties of Au nanoparticles have been known for some time, with both Au colloids and Au nanoparticles embedded in glasses having been extensively studied. In this study, Pt nanoparticles have been incorporated into Au colloids, and the linear and non-linear optical properties investigated. UV-VIS spectrophotometry, fluorescence spectroscopy and the z-scan method have been used to examine the effects of such additions.

Oct 1, 2003

By Jean-François Lessard

The performance of rock pass systems has a significant contribution to the economics of underground mines. Operational concerns include hang-ups due to arching of material, blockage and degradation of the rock pass. This papers presents the preliminary results of a comprehensive rock pass database on the engineering and operation of rock pass systems in Quebec underground mines.

May 1, 2002

By R. E. Michelutti

"The Sudbury area environment became drastically altered commencing in 1871 with lumbering, repeated fires and early open roasting operations from 1887 to 1929. These combined factors had such a pronounced effect that approximately 24 square miles were totally denuded of any vegetation and 87 square miles were semi-barren to somewhat stressed.The two nickel producing companies in the area have reduced the sulphur dioxide emissions considerably over the years. Falconbridge Limited, alone, reduced sulphur dioxide emissions by 77% from 1971 to 1984.These reductions have resulted in improvements to the air, soil, lake and vegetation quality in the Sudbury area.INTRODUCTIONThe Sudbury area environment became drastically altered commencing in the 1870's with lumbering, repeated fires and early open roasting operations from 1888 to 1929. These combined factors had such a pronounced effect on the Sudbury environment that approximately 24 square miles (64 sq. km.) were totally denuded of any vegetation and 87 square miles (225 sq. km.) were semi-barren.Over the years, the Sudbury area environment has improved considerably. This has been due to emission cutbacks by both Inco Metals and Falconbridge Limited, coupled with industry, government and community reclamation programs. Before the improvements are discussed, a better understanding of the historical degradation is required."

Jan 1, 1986

By B. Jago

From the perspective of metallurgical processing, gold ores can be classified into freemilling and refractory ores. Their extractive metallurgy is largely driven by mineralogical factors such as gold particle size, association with other minerals, coatings and rimmings, presence of cyanicides, oxygen consumers and preg-robbers, presence of refractory gold minerals, and invisible gold in sulphide and sulpharsenide minerals. Gold process mineralogy helps address issues and problems related to gold ore processing. It is widely used as a predictive and trouble-shooting tool in gold ore processing, and provides useful information on process selection, flowsheet development, recovery improvement, and reagent consumption optimization. By combining classic mineralogical techniques, modern instrumental analysis, and diagnostic metallurgy, the mineralogist is able to balance the various types of gold occurrence in an ore.

Jan 1, 2006

By G. M. Hughes, J. Ellis

"IntroductionHydraulics has been considered a science for thousands of years. Applications included water wheels, dam; and slice gates but today the term ""hydraulics"" commonly refers to ""power hydraulics"" in which fluid is used under controlled pressure to do work. The mining industry employee’s hydraulics in practically every aspect of its operations, on such equipment as trucks, front end loaders, LHD units, crushers and hydrostroke feeders. The many benefits of hydraulic drives such as ease of variable speed control, high power: weight ratio low envelope size of hydraulic actuators and ease of maintenance have been extensively developed in the pulp and paper, chemical, steel, and other basic industries, but until quite recently, concentrator operators have not taken advantage of the versatile methods of power transmission offered by hydraulic systems.After some preliminary testing at the Lynn Lake concentrator Sherritt Cordon Mines Limited installed several hydraulic system; at their Fox Mine concentrator to drive slurry pumps and conveyors. The systems used at Fox and the systems which will be installed at the Ruttan concentrator are briefly described in this paper. Since acceptance is based mainly on understanding a few basic principles of hydraulics system; including pumps, motors, circuitry and central methods are also presented in the paper.PRINCIPLES OF POWER HYDRAULICSBasicsHydraulic systems provide an uncomplicated, versatile means of power transmission. The basic system is quite simple. It consists of five main elements, as shown in Figure 1, which are:1. Prime Mover - generally an electric motor.2. Hydraulic Pump - fixed or variable positive displacement type such as a piston or vane p.mp which displaces a constant amount of fluid for ead1 revolution - this unit converts mechanical energy of the prime mover into fluid energy.3. Oil Reservoir - a standard tank to operate under atmospheric pressure which has a capacity of 2 - 3 times the maximum gpm outp.it of the hydraulic pump."

Jan 1, 1972

By H. P. Jacobi

"INTRODUCTIONPine Point Mines, operated by Cominco Ltd., is located approximately 65 miles east of Hay River, N.W.T. on the south shore of Great Slave Lake.The milling operation started in the fall of 1965 with a capacity of 5,000 tpd. An addition was put into operation late in 1968 to bring the nominal capacity up to 8,000 tpd. The present milling rate is 11,000 tpd.With a feed grade of approximately 2.9% Pb and 6.0% Zn the annual concentrate production amounts to roughly 130,000 SDT of lead concentrate and 370,000 SDT of zinc concentrate for a total of 1/2 million tons of product.This tonnage is moved by railroad. Pine Point is served by the Great Slave Lake Division (G.S.L.) of the Canadian National Railways which connects to the Northern Alberta Railway System (N.A.R.) at Roma Junction, at Peace River, Alberta. The system in turn connects to the CNR and the CPR in Edmonton, Alberta. From here the concentrates move inland chiefly to Trail, B.C., with some shipment to other Canadian and U.S. smelters, and to the port facilities of Pacific Coast Terminals at New Westminster, B.C. for offshore export.This paper will focus on the problems associated with the movement of lead and zinc concentrates from Pine Point to port facilities on the west coast."

Jan 1, 1975

The common theme of these four objectives is declaration. Declaration tells the compiler that an entity exists and also provides the name and nature of the entity. Since everything you create has to be declared, you must know how to declare correctly and be able to make appropriate use of all the declaration tools available to you. This objective recognizes the importance of declaration by requiring you to know everything about Java declarations Write code that declares, constructs, and initializes arrays of any base type using any of the permitted forms both for declaration and for initialization. This objective addresses your understanding of all aspects of arrays. Arrays are the simplest possible data collection and are supported by all modern programming languages. However, Java?s arrays are different from those in other languages, especially C and C++, because they are actually exotic objects. This objective recognizes the importance of being able to make use of all the functionality of arrays. You will be expected to know how to declare, construct, and initialize arrays.

May 1, 2011

By B. McLaughlin

"The Penna shaft is the deepest single-lift shaft in North America. Agnico-Eagle started sinking the Penna shaft in 1995 with a hoisting plant capable of hoisting 1800 t/d from a 2240-m deep shaft. Exploration success at depth led to the replacement of the existing double drum hoist by another double drum hoist capable of hoisting 7000 t/d. The use of another double drum hoist, instead of a Blair multi-rope winder, to hoist 24.5 t skips was only made possible by lowering the safety factor.This paper describes recent experiences at Penna and in South Africa, and examines the possibility of extending the double drum hoisting system to a depth of 3 km. IntroductionThe original Penna production hoist was a 4.88 m (16 ft) diameter double drum and single clutch machine. Béliveau (1996) and Scott (1996) have described this hoisting plant. In 1998, a decision was made to increase mining capacity from 1800 t to 4500 t of ore per day from the shaft bottom. Final capacity had to include an allowance of 1800 t of waste per day for future capital projects. While daily capacity was to be 6300 t, it would, by taking into account the different rock densities, be equivalent to hoisting 7000 t of ore.The steps taken to lower the safety factor were presented by McLaughlin and Scott"

Jan 1, 2004

By Denis Thibodeau

The selected mining method for the Rodeo lower Zone is slot and slash. Initial design indicated that the stope height should be limited to a maximum of 18 m, thus six levels were needed to extract the ore. Higher stope height in the Rodeo Lower Zone means less development thus less capital required to extract the available reserves. It was proposed to eliminate one level by establishing 30 m and 24 m level intervals. To ensure that no stability problems will be encountered by eliminating one level, a Matthew analysis, based on diamond drill core information, was performed for the Lower Rodeo Ore Body. In addition, comparisons between the rock mass quality of Meikle Main Zone below 1825 L and Meikle East Zone between 1600 L and 1750 L with the rock mass quality of the Lower Rodeo were made

May 1, 2002

By P. Brad Marchant

"To properly evaluate bioleaching as a commercial alternative for sulphide concentrate oxidation, to enhance cyanidation response, it was necessary to define and optimize critical operating variables outside of the laboratory under less than ideal conditions. A complete bioleach testing laboratory was installed at Equity Silver Mines to aid in pilot plant flowsheet development.A continuous pilot scale bioleach circuit was constructed to provide data for meaningful valuation of biotechnology on a plant scale. The important operating and design parameters for pilot plant testing are described. Plant scale feasibility and design considerations, to treat a refractory pyrite/arsenopyrite concentrate produced from flotation tailing, are discussed. 1.0 BACKGROUNDEquity Silver Mines Limited is located 37 km southeast of Houston in central British Columbia. A 70% owned subsidiary of Placer Development Limited, Equity is Canada's largest open pit silver producer. Ore reserves were estimated at 28 million tonnes grading 106 g Ag/t, 0.96 g Au/t, and 0.38% Cu from two pits, the Southern Tail and the Main Zone. Detailed geology and mineralogy has been described previously(1,2).The concentrator flowsheet consists of conventional crushing, grinding, flotation, and dewatering circuits processing 5 300 tonnes per day of new mill feed. The resultant Cu/Ag/Au concentrate is trucked to Prince Rupert for shipment to market. Mill tailing reports to a closed circuit pond from which mill process water is recycled. Details of the concentrator process have been reported( 2,3).Production in the Southern Tail pit, from July 1980 to March 1984, resulted in mill tailing averaging 0.9 g Au/t and slightly more than 20 g Ag/t. Historic data indicate that unrecovered gold is associated with arsenopyrite and silver losses with unliberated tetrahedrite or minor silve,, bearing sulphosalts. Main Zone mill tailing, which commenced production in March 1984, contains approximately 0.5 g Au/t which is probably associated by majority with silver bearing minerals and pyrite while silver losses, 30-40 g Ag/t, are associated with unliberated silver and antimony bearing minerals."

Jan 1, 1985