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By R. Butar-Butar, J. Mosher, G. Banini, J. Hollow, A. Villanueva

The effect of High Pressure Grinding Rolls (HPGR), as a preceding stage to a conventional ball mill circuit at PT Freeport Indonesia’s C1/C2 concentrators, has been studied in terms of downstream grinding efficiency and circuit performance. When milling the product from the HPGR, mill capacity increased by 21% for the same product grind size, when compared to processing similar ore from a conventional crushing circuit. This achievement is a result of several reasons, among them: reduction in feed size (F80), fines generation beyond the proportional reduction in F80, reduction in ore hardness induced by HPGR comminution mechanism, optimization of the recycle system of the HPGR and ball string optimization in the ball mill circuit given the new feed to the mill.

Jan 1, 2012

By M. Hawker, M. Kreuh

The mining and metallurgy industry is known to be of cyclical nature associated with price volatility. As such, some years are quite lucrative and other years require mining companies to tighten their belts. The field is a mix of junior, mid-tier, and major mining companies. One thing that is common to all of them is the time required and the cost to develop a flowsheet in accordance with best practices. Although a long list of factors can impact flowsheet development, this paper will include the impacts of: experienced metallurgical engineers and laboratories, representative samples for high quality and valuable testwork results, and following engineering development stages. The paper also provides typical time frames to complete selected engineering flowsheet development steps.

Jan 1, 2014

By Rainer Süss

An investigation was carried out by Mintek to investigate the influence of a range of alloying additions (vanadium, cobalt, zirconium, antimony and germanium) on the formability and hardenability of alloys with gold content >90 wt%. This paper reports on the hardening mechanisms that can be utilised to increase the hardness of gold (>90 wt% Au) by conventional alloying, as well as the hardening effect obtained by alloying with specific elements. Preparation methods for the alloys are described, which include the steps of melting, annealing, quenching, cold working and age hardening. Focus is given specifically on alloys that were developed at Mintek with a gold content >90 wt%, which are not only harder, but exhibit good resistance to tarnishing and corrosion.

Oct 1, 2003

By K. J. Mintz

Conveyor belts installed in an underground mine can be a potential source of a major fire, thus the need for fife-retardant belting. A Canadian Standard, CAN/CSA-M422-M87, incorporating a small-scale flame test, a drum-friction test, a flame propagation test and an electrical surface-resistance test, has been developed to meet the varied needs of the mining industry. It is recommended that mines use Types A and B belting described in that Standard, because they will have passed the large-scale flame propagation test, rather than Type C, which does not require that test. Belting that has been approved by the U.S.A. Mine Safety and Health Administration (MSHA) may be much less fire-retardant than any Canadian approved belting.

Jan 1, 1992

By G. Grant Smith

In situ bulk density of coal is a variable applied to various aspects of coal resource evaluation, such as compositing ply analyses of coal attributes that are expressed on a weight per cent basis, and determining tonnages from volume estimates. Its value is a function of composition and porosity of the in situ material. When densities of ash-free coal, ash and water are fixed, in situ bulk density of a coaly mix can be expressed as a function of proportionate weight of ash in the mix. Correlations between in situ bulk densities and weight per cent ash contents of coaly mixes have been estimated for four general rank classes of coal (low medium volatile bituminous, high volatile bituminous, subbituminous, and lignitic).

Jan 1, 1991

By Himmelman. Nicholas P.

In this paper, the hardware foundations and data collection methods of a real time collision avoidance system for electric surface mining rope shovels are described. The primary goal of the system is to help a shovel operator avoid accidentally colliding the shovel?s dipper with either a nearby haul truck or the shovel?s tracks. To achieve this goal, the system requires complete and precise knowledge of the shovel?s geometry and movement, as well as the location of any nearby haul trucks. This paper describes the subsystems created to acquire this necessary information. This system is unique in that all of its components are mounted solely on the shovel and that it is designed to be easily retrofitted to a shovel without significant modifications.

Oct 1, 2009

By Euler De Souza

This paper presents a study conducted to assess sillmat behaviour during undercut mining and to provide a comprehensive understanding of the effects of arching and sillmat thickness on stability. The design study investigated the effects of such parameters as stope width and height, closure strains, orebody geometry and inclination, wall roughness, fill properties and cure time on the stability of cemented sillmat during undercut mining. Arching effects have been quantified based on centrifuge modeling studies for the different mining conditions. Observations have indicated that the degree of arching is a function of stope geometry, wall roughness, fill cohesion, and wall closure. Arching effects increased with decreasing stope width, increasing backfill cohesion and frictional resistance, increasing wall roughness and with wall closure.

May 1, 2002

By Tarrant Elkington

Underground mine planning practices are typically manual and time consuming and will often produce sub-optimal solutions due to the application of generic rule-of-thumb assumptions or ?tried and tested? choices. The development of computer-automated tools for underground mine planning enable a wide range of scenarios to be considered rapidly in arriving at an optimised solution, subject to input assumptions. We have applied these tools to demonstrate ?optimised? solutions that challenge industry standard practices. Further, we have incorporated grade and price/cost uncertainty into these tools to gain an understanding on how the consideration of uncertainty may further alter strategy selection. Finally, we enable the tools to dynamically adjust cut-off grades in conjunction with the evolution of prices/cost.

May 1, 2010

Cobalt mostly occurs as a minor, but valuable, constituent in most nickel and a few copper ores, however it is not generally found alone in commercially viable deposits. Its concentration and extraction are therefore intimately linked to the recovery of the primary metals and the major task for the metallurgist is to extract cobalt of commercial grade from a much larger mass of either nickel or copper and sometimes both. With a particular focus on Vale Inco?s operations, this paper provides a brief overview of the mineralogy of the main deposits being currently exploited that contain cobalt as a co or by-product. The concentration and then extraction to metal are reviewed and some advances released into the public domain are discussed.

May 1, 2009

By Erin N. Legault-Seguin

The Lac des Iles Mine (LDI) is located approximately 100 km northwest of Thunder Bay, ON. The mine has been in operation since 1993. The initial mine production was 2,300 mtpd and increased to 15,000 mtpd following a mine expansion project that was completed in 2001. Effective Oct. 29, 2008, LDI was shut-down under care and maintenance due to low metal prices. Prior to shutting down, LDI was the only primary PGM deposit in operation in Canada and of the few found globally. The complex geology and physical properties of the deposit causes several challenges for the concentrator. This paper will discuss the solutions to the main challenges of attaining nameplate tonnage and achieve satisfactory Pd recovery and concentrate grades.

May 1, 2009

By M. H. B. Nasseri

Barre granite?s samples have been tested for fracture toughness under mode I along two different directions with respect to microstructural fabrics were investigated. 3D objects counter algorithm technique is applied on micro CT images to identify physical properties such as crack induced porosity, crack density, generated total surface area and contribution of individual mineral grains within the damaged zone.The result obtained justifies very well the fracture toughness anisotropy in Barre granite, and explains the difference in the structure of the damage zone evolving as a result of test crack interacting with pre-existing microstructural fabrics. The present study has potential application in the fields of rock mass stability, oil reservoir stimulation, rock fragmentation and damage in blasting and emplacement of dykes.

May 1, 2009

By E. Marcoux, F. Lotfi, A. Belkabir, L. Maacha, A. C. Brown, S. Brunet

"Koudiat Aïcha is a small Zn-Pb-Cu deposit, enclosed in the Visean Sarhlef volcano-sedimentary series of the Moroccan Hercynian Jebilet massif. Base metal mineralization is located between a basal unit consisting of black argillite with arenite intercalations, and an upper unit composed of black argillite with locally fossiliferous calcareous units towards the top. Paraconcordant gabbro sills are present in both the upper and basal units, and the enclosing strata. Three successive phases of deformation linked to regional deformation overprint the volcano-sedimentary rocks and gabbros, as well as the sulfide mineralization.The mineral deposit includes several lenses of massive to semimassive pyrrhotite, 1 to 20 m thick, with a large halo of disseminated sulfide veinlets and sulfide nodules within a zone of intense chlorite alteration in the footwall. The ore mineralogy consists of massive to semimassive pyrrhotite with lesser amounts of sphalerite, chalcopyrite, arsenopyrite, galena, pyrite, and stannite.Lead isotope results (206Pb/204Pb averaging 18.27) suggest that the metals of the Koudiat Aïcha deposit are derived from the volcano-sedimentary host rocks. Sulfur isotopes also indicate a volcano-sedimentary origin, with bacterial reduction of sulfate (d34SCDT = -7.5‰ to -10.5‰). The conditions for sulfide meta-morphic equilibration range from 250° to 330°C (sphalerite and chlorite geothermometers). The gabbroic sills could have been a local heat source for hydrothermal circulation. Based on these geological and mineralogical features, a Besshi-type model seems appropriate for the genesis of the Koudiat Aïcha mineralization.Koudiat Aïcha est un petit dépôt de Zn-Pb-Cu, encaissé dans la série volcano-sédimentaire Viséenne de Sarhlef dans le massif Hercynien de Jebilet au Maroc. La minéralisation en métaux usuels se situe entre une unité basale d’argilite noire interlitée d’arénite et une unité supérieure composée d’argilite noire comprenant localement des calcaires fossilifères près de son sommet. Des sills de gabbro paraconcordants sont présent à la fois dans les unités basale et supérieure, ainsi que dans les strates environnantes. Trois phases de déformation successives associées a la déformation régionale superposent leurs effets sur les roches volcano-sédimentaires, les gabbros, ainsi que la minéralisation sulfurée. Ce gîte comprend plusieurs lentilles de pyrrhotite massive a semimassive de 1 a 20 m d’épaisseur au sein d’un large halo de veinules de sulfures disséminés et en nodules au sein d’une zone intensément chloritisée dans le mur du gisement. Le minerai consiste en pyrrhotite massive à semimassive avec des quantités subordonnées de sphalérite, de chalcopyrite, d’arsénopyrite, de galène, de pyrite, et de stannite. Les résultats de l’analyse des isotopes du plomb (206Pb/204Pb moyen de 18.27) suggèrent que les métaux du gîte Koudiat Aïcha proviennent des roches volcano-sédimentaires encaissantes. Les isotopes du souf¬fre indiquent eux-aussi une origine volcano-sédimentaire, impliquant la réduction bactérienne des sulfates (d34SCDT = -7.5‰ et -10.5‰). L’équilibration métamorphique des sulfures s’est produite entre 250° et 330°C (géothermomètres à sphalérite et chlorite). Les sills de gabbro pourraient avoir été la source de chaleur locale responsable de la circulation hydrothermale. Sur la base de ces caractéristiques géologiques et minéralogiques, il semble approprié d’invoquer un modèle de type pour Besshi pour expliquer la genèse de la minéralisation de Koudiat Aïcha."

Jan 1, 2008

By P. C. McLeod

THE GECO OREBODY, located north of lake Superior in the Thunder Bay district of northern' Ontario, was discovered in 1953. Diamond drilling in the following year indicated a 15,000,000-ton ore-body, and production plans were made for the shipment of copper and zinc concentrates in three years. To accomplish this, the Geco Project was initiated. The property was in an undevdoped, inaccessible area, and the project involved the conversion and extension of a logging road to the property, the construction of two railways and seventy miles of hydro transmission line, the erection of a municipality, the building of a plant, and the development of an underground mine to produce 3,300 tons per day. This paper describes some of the methods used in the underground development phase of the Geco Project.

Jan 1, 1958

By The Staff

WE were requested to make a digest of our original grinding report, Fine Grinding Investigations at Lake Shore Mines. This digest is much easier to read than the original report, but it lacks the experimental 'evidence' found in the first report which, in many cases, is much more interesting and educational than the conclusions derived from it. In the course of rewriting the paper, we noticed several new angles on the test data which had not occurred to us previously. From the data included in the report and other tests not published, calculations were made which indicated a line of new test work. These tests, among other things, more than suggest a technique for designing the length of mills, the position and number of classifiers, and the total loads a mill should carry.

Jan 1, 1941

By M. C. Bétournay, J. E. Udd

"The legacy of abandoned mines in Canada creates issues that impact on both the health and safety of Canadians and the environment. Solutions to the problems of abandoned minesites require a detailed understanding of site conditions, the engineering solutions which may be relevant, and planning for effective use of the land. In this paper, the authors outline the basic thrusts that have been developed at CANMET to address this problem. These include: multiprovincial agreements to develop a national database; methods of site rendering; a ten-year research program to develop engineering approaches; the review of a large number of case studies; and outlining the associated risks. Examples of the applications of this research are provided in the areas of: municipal, provincial, and federal co-operative projects; site-specific applications; and international linkages."

Jan 1, 1997

By E. Demedde

Carbon anodes in aluminium reduction cells are continuously consumed during electrolysis. In prebake cells the anodes are replaced at regular intervals. The spent anodes, called butts, are often allowed to cool in air while emitting fluorides into the building from the hot alumina cover and the adhering bath. In modem smelters spent anodes are placed inside enclosures and fluoride emissions during cooling are effectively reduced. Fluoride emissions from spent anodes were estimated by considering the kinetics of fluoride formation, a heat transfer analysis of the cooling anode butt and the ventilation flow from a cavity. Fluoride emissions from large anode butts cooling inside enclosures were compared with those cooling in air. Good agreement with published experimental values was obtained for enclosures having different leakage opemngs, when a hydrofluorination reaction of the spent anodes was included.

Jan 1, 2006

By Moe Momayez

Shotcrete is a practical and economical support system in many Canadian underground mines. Although shotcrete technology has gained acceptance in the mining industry, there are some problems that have emerged with respect to quality assessment and thickness measurement of the liner. This paper presents recent tests performed with a miniature seismic reflection device developed primarily for thickness measurement of this heterogeneous liner. Work was performed on site in an underground mine in Ontario, Canada. This paper also presents the results from laboratory tests performed on fibre reinforced and non-reinforced shotcrete panels that were used to assess the P-wave velocity in both materials. The results of these tests were used in a second on site investigation. The NDT thickness measurements showed good agreement with direct thickness measurement such as coring.

May 1, 2001

By Paul B. Warrington

This paper presents a discussion of the factors affecting copper scrap markets, including such items as price levels, freight. grades of material, sources and packaging. Reference will also be made to the effective life and turn-around of the copper content of some products. Introduction IN TERMS OF SIZE, copper scrap is second only to ferrous scrap in tonnage recycled. However, in total value, it is second to none. For example, world scrap recovery during the preceding 4 years averaged just under 2,300,000 metric tons per annum, and at an average price of 70 ¢ a pound, this works out at a turnover of about $3.5 billion, which indicates that the copper scrap industry, or recycling as it is now becoming known , is a substantial one.

Jan 1, 1977

By W. A. MacWilliams, R. G. Reynolds

"This paper describes, for the first time, a patented method of extracting sodium sulphate from a natural deposit in Western Canada. The method resembles, but is not, strictly speaking, solution mining. The fact that a plant based on this method has been in successful operation since late 1969 will be of added interest. The deposit in question is located near Metiskow, Alberta, and conventional surface recovery methods could not be applied because of heavy concentrations of mud. Considerable pilot work went into the separation and recovery process on which the plant operation is based. The history of the industry is covered briefly as background to this development. Today it is clear that the method has broader application within the industry and, in concept, may generate interest in many other applications."

Jan 1, 1973

By J. Lee

A monolithic caisson is one of the major structural components commonly used in the construction of docks, breakwaters, and container terminal quay walls. Since the structure of monolithic caissons is typical and somewhat simple, its design process is also typical and repetitive, but still time consuming. To reduce the total time and enhance productivity, we developed a parametric model in Revit to automatically generate a 3D model of a monolithic caisson. It is designed to generate the Revit model of a caisson with concrete body and reinforcing bars. The size of caisson, the number of reinforcing bars, and the space between reinforcing bars are automatically changed when users update parameters. This paper presents how we developed this parametric family in Revit for monolithic caisson design and how it would enhance its design process.

Aug 1, 2013