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"The Cooperative Research Centre for Mining Technology and Equipment (CMTE) is funded by the Commonwealth Government, by its mining research members — the Universities of Queensland and Sydney and the CSIRO1, and by its industry members — BHP Coal, RioTinto R&TD, Hamersley Iron, Mining Technologies Australia, Pasminco, Shell Coal, WMC Resources, Advanced Mining Technologies, and Aberfoyle. The Centre conducts work aimed at improving the competitiveness of the Australian mining industry. The current work is focused in four areas: new mining and drilling systems, geological sensing, automation, and equipment maintenance and reliability. This paper describes much of the work in these program areas that relates to metalliferous mining. Mechanized Rock ExcavationThe disadvantages of the drill-and-blast excavation method are widely recognized and the last half of the 20th century has seen mining companies and mining research organizations aggressively pursue technology to excavate rock by other means. As discussed below, despite considerable effort and large amounts of funding, the quest for mining’s “Holy Grail” has been unsuccessful in all but the weakest rock types.COMRO (the Chamber of Mines Research Organisation) supported by the South African gold mining industry, spent three decades and (probably) tens of millions of dollars developing prototype drag bits and, later, impact breaking machines aimed at the mechanized stoping of narrow, tabular reefs. This work has not yet produced a commercially-attractive mining system. Work continues in South Africa to mechanize these stoping operations although now the emphasis is on the use of diamond-wire sawing techniques. This work remains in the experimental phase.Both British Coal and Germany’s Bergbau- Forschung spent many years developing techniques trying to extend the range of rock types which roadheaders could cut economically. Again, although new knowledge was produced, it is difficult to claim that any new commercial mining systems emerged from this work."

Jan 1, 2001

By John B. Phillips

The mine is entered by a central vertical shaft, strongly timbered, and containing two compartments-one for the passenger cage, the other for the large skips bringing the ore to the surface. A man-way, for emergencies, is also provided, parallel to the shaft. The cage is a single-deck steel box, carrying about thirty persons; by means of arrangements above and below, it can also hoist and lower materials needed in the workings. Levels are run at intervals of 100 feet. In special cases, where the ore conditions warrant, sub-levels are operated, such as those at 1,113 feet and 1,123 feet (Fig. 7), which are connected by winzes with the 11 th level. One of these was pushed for 40 feet, and then abandoned because it was unprofitable to take up ore of the grade encountered. The ore between levels is removed by stoping. The drifts follow the course of the veins as much as possible, with numerous cross-cuts. Winzes, raises, connections, etc., are blasted out where needed. The main drifts are at least 8 ft. high by about 9 ft. wide. All former narrow drifts had to be widened sorne time ago, by ruling of the Ontario Department of Mines, to lessen the danger of accidents with cars in the small passages. Accurate plans of the under-ground workings are kept in the office, and extensive surveying is always being done underground to keep the maps up to date, measure the cubical contents of stopes, and so forth. Timber is extensively used in the construction of supports and chutes, and in the sinking of the shaft. Steel and concrete are too expensive to compete with timber, which 1s abundant in such sections as have escaped forest tires.

Jan 1, 1926

By W. P. Campbell

Introduction OWING to the necessity of curtailing the length of this paper, nothing like an exhaustive treatment of the subject will be attempted. Instead, merely a few aspects will be considered, viz., water trouble in wells, sampling of waters, analysis, methods of reporting analysis, and the comparison of a few typical waters. The waters discussed will not be confined to those occurring in areas where oil or gas has already been found, but will include samples from areas in which drilling is being carried on in the hope that oil or gas may be found, i.e., from unproved fields. The Water Problem The problem of dealing with water encountered in oil and gas producing areas has engaged the attention of petroleum engineers from the early days of the industry. Water was not always considered a menace to oil sands; indeed, a certain amount of it was considered beneficial in some areas, but if such exist today they are very exceptional. In some fields, the problem is more acute than in others, and at times has baffled all attempts to solve it satisfactorily. Wells have been brought-in with promise of good production, but after a brief period have 'gone to water'. Whether ?it has always been a case of poor engineering in the form of unsuccessful water shut-off of 'top' or 'bottom' water, or because 'edge' water was present and water and oil were in such close contact it was impossible to remove the one without the other, is hard to say.

Jan 1, 1929

By K. Konigsman

"Representatives of various industries and the Canadian coast Guard formed a Bulk Cargoes Committee three years ago. In 1976 and 1978, I have attended the meeting which take place once per year here in Ottawa as representative of the Canadian Mineral Processors, Dave Hendricks from Granisle accepted the charge in 1977. Our Secretary, Bob Bruce, has suggested repeatedly that I report to the Membership on the deliberations to this group. Twice I found good excuses; this year I did not. I was reluctant to address you since the Committee's deliberation proceeded at a pace which might be identified as Government squared. The Committee advises a Government agency which in turn negotiates with foreign Government agencies.At the outset, I will describe the developments which led to the formation of the Committee and its purpose.The Canadian Mining Industry ships annually millions of tons of products to overseas customers; be it iron ore, coal, fertilizer, or base metal concentrates. Most loadings are in vessels of foreign registry and all will be directly affected by Canadian or International regulations of the transport of such bulk commodities. The major shipping nations are members of an Intergovernmental Maritime Consultative Organization (IMCO). This organization elaborates regulations which govern shipment of all cargo, bulk materials and concentrates included. At IMCO'S deliberations, Canada has one vote, one voice on the Consultative Committee and is represented by our Coast Guard. The Coast Guard has over the years been in contact with industries when discussions concerned shipment of bulk cargoes. In the early sixties, a ""Concentrate Committee"" did exist. It consisted of metallurgists from a number of mining companies and Government representatives. This committee was instrumental in the development of what became known as the ""Concentrate Code"", legislation which has evolved into the Canadian Bulk Cargoes Code as it is known today. The concepts of the flow moisture point and transportable moisture limit originated from its work. Incidentally, both criteria are widely accepted and utilized world-wide. The Concentrate Committee faded away once the Concentrate Code has been adopted."

Jan 1, 1979

By Anthony T. Eyton

Intelligent Systems: Advantages for Mining ? Increased safety (reduced risk to workers) ? Increased productivity (reduced downtime) ? Reduced maintenance costs ? Customized solutions for different mines ? Growing acceptance among mine managers A Typical Precarn Project ? Meets definition of intelligent systems ? Involves at least two Precarn members ? a technology developer partner and a user partner ? in a true collaboration ? Involves at least one university and may have various other players ? Leads to a demonstrated prototype ? Costs $2-4 million, and lasts 12-30 months ? Gets up to 40% of its funding from Precarn (max. $1 m) ? Produces new intellectual property -- owned by the project team

May 1, 2002

By Richard P. Curtin, John M. Goris, Lewis A. Martin

Cable bolt supports are being recognized as an effective ground control system in under-ground coal mines in North America, and their use has increased considerably during the past few years. The U.S. Bureau of Mines personnel are conducting both laboratory and field tests to evaluate the performance of these supports under a variety of conditions and to establish realistic design guidelines. This paper describes efforts to evaluate the capability of cable bolts to resist the high shear forces often present in longwall operations. Shear tests were conducted on pairs of 0.025 m3 (0.88 cu. ft) concrete blocks having joint surfaces ranging from rough to smooth. Tests were conducted on blocks both with and without reinforcement with 15.2 mm (0.6 in.) diameter steel cables. During each shear test, the loads and displacements along the normal and shear axes, as well as loads on the cable, were monitored. Cableloads were determined using strain gauges attached to the outside surfaces of the barrel-and-wedge anchors used for pretensioning the cables. Test results show that a cable bolt placed across a joint more than doubled shear resistance of shear blocks having both smooth and rough joints.

Jan 1, 1996

"THE GOLD MINING REGION of Timmins - Val d'Or, astride the Ontario-Quebec border, has long suffered the effects of rising costs during the period when the U.S. price of gold was fixed at $35 per ounce. The federal government, through such assistance programs as that set up under the Emergency Gold Mining Assistance Act (E.G.M.A. ) in 1948, has subsidized the gold mining communities of Canada for a total of over $300 million to March 31, 1972. Of this, the Timmins - Val d'Or ""gold belt"" has received more than twothirds, almost $220 million. In spite of these continuous subsidies, only 12 gold mines are still producing in the Timmins - Val d'Or belt, whereas 71 mines have received subsidies for some period since 1948. The vital question is how the communities previously supported principally by the mining of gold will survive in the long run, as many of the older mines either are already depleted or are quickly becoming so. With the rising price of gold on the 'free market in recent months, prospects look a little brighter for the time being. Even with the increased official price of U.S. $38, which made the maximum government subsidized price about $48 per ounce, gold mines have not sold any gold to the government since January 1972 and some stopped doing so months before that. The populace of the region has not been enthusiastic about relocation nor about extensive retraining programs in the past and probably will not be in the future. So, when the remaining gold mines become depleted, the old problems of community depression will remain."

Jan 1, 1973

By David Ulrich Furrer

Materials and manufacturing processing technologies have played an important role in the development and capabilities of nearly all manmade products. Market drivers for fuel efficient, low cost, environmentally friendly, more capable transportation has given rise to significant materials challenges and subsequent developments. The rate of improvement and implementation of new commercial products can be limited by the rate of new materials and process technology development and qualification. As many materials are being designed for unique requirements and even location-specific unique properties, the implementation of tools and methods to enable rapid characterization and validation of material definitions and design systems must also be accelerated. A review of new integrated material, manufacturing process and component designs, engineering processes and emerging tools and methods will be discussed. The linkage of computational materials science and engineering into component design will also be discussed along with the challenges and opportunities for further growth and application of integrated computational materials engineering (ICME).

Jan 1, 2015

By Maurice Séguin

The primary aim of all ground geophysical work has been, of course, to locate orebodies. As with any geo-physical method, its success depends on a proper mastering of the types of surveys and equipment used and their application to the physical properties associated with the orebodies. The Schefferville deposits are iron ores subjected to enrichment by the process of leaching. Although some ore types are porous and low in demiity, most of the ore zones have had a net increase in density brought about by enrichment. In the course of their formation, the magnetic characteristics of the rocks have usually changed, as much of the magnetite was altered to relatively non-magnetic iron oxides and hydrous iron oxides. Ali drift-covered areas underlain with iron-formation are potential ore-producing areas. From these first two physical proper-ties and a determination of the thickness of the over-burden, a combined gravity-magnetic-seismic and/or resistivity survey allows for the detection and sorting out of iron-formation and potential ore zones from the country rocks. If the iron-formation possessed relatively uniform physical and chemical properties, the problem of locating areas underlain with ore, using geophysical methods, would be greatly simplified. Unfortunately, the iron-formation is a complex assemblage of rock types, each having different physical and chemical characteristics. In spite of this, qualitative and semi-quantitative correlation between the results of the surveys and the geology and structure of the area could be established. In addition, a semi-quantitative to quantitative correlation of the values of the residual gravity anomalies with the specific gravity, the iron content, the porosity factor, the dimensions of the under-lying orebodies and the values of the ground magnetic intensity above a reference lithologie unit, with the per cent weight Fe304 recovery and the susceptibility, led to the discovery of a direct-shipping iron ore deposit in the Schefferville mining district of Canada.

Jan 1, 1968

By L. Vollert

In-situ recovery of metals is presently experiencing a revival not seen since early applications in amenable copper oxide deposits, uranium and generally applications where neither, porosity and permeability, nor process chemistry have been prohibitively difficult. With ever decreasing grades in current mining operations or Greenfields projects and ever increasing capital and operating costs, in-situ recovery is looked to as the processing option that will both unlock these deposits as well as potentially derive revenue from mineralised waste remaining in the ground once traditional mining and processing methods become uneconomical. In-situ recovery is also being looked to as a mining method that minimises the environmental impact sustained in the application of traditional energy and water intensive mining and processing operations where millions of tonnes of ore are mined from the earth, processed on surface and then disposed of in both waste dumps and tailings facilities. The key challenge facing companies like Newcrest is that these low-grade deposits or remnant mines are generally hard rock applications that require costly methods to liberate the valuable minerals. A further challenge includes identifying suitable chemistries that both facilitate the economic recovery of gold and copper and that may be considered environmentally acceptable. This paper presents a desktop study whereby the issues of access creation and chemical extraction are discussed and evaluated with a view to driving future research in the area and unlocking this application as a real processing option. INTRODUCTION Mining companies are increasingly challenged by low grade, deep and complex ore deposits which are no longer economically exploitable by current methods. The large footprint of current open pit operations can present obstacles for permitting and social acceptance. For these reasons in-situ recovery (ISR) technologies are receiving renewed attention as a technology which could be used to exploit these more complex deposits economically and with less environmental impact. The environmental impact may be further reduced if emphasis is placed on use of renewable energy sources rather than traditional grid power, gas turbine or diesel generators are employed to drive the operation. A potential renewable energy driven ISR mine of the future is shown in Figure 1.

Jan 1, 2019

By R. H. Schonewille

One of the many challenges in developing new metallurgical processes is choosing the best option for validating process design parameters and establishing the process operating window. Historically this has been achieved by constructing pilot or demonstration plants of considerable size and complexity, to enable integrated operation of all key process units for a significant duration. While this would appear to be the best option for minimizing technical risk, it is often impractical from a perspective of cost, schedule, resources or bulk sample acquisition. Such an undertaking can even provide a false sense of security, as the optics of running a complete scaled-down version of a commercial plant suggest a high level of process understanding, regardless of the challenges encountered during operation. Xstrata Nickel has undertaken numerous process development and improvement projects over the past 15 years to support green field project development and continuous improvement in existing operations. The approaches used have included; computer simulation, cold flow modeling, construction of pilot test units in third party facilities, commercial plant referencing and the more conventional construction of integrated test plants. Regardless of the strategy employed, the keys to success have included; managing stakeholder expectations, involving the commercial plant design engineers in the planning stage, anticipating subsequent data and sample requirements and most importantly, constructing and operating complex demonstration plants only as a last resort. This paper provides examples of various process development approaches used by Xstrata Nickel and discusses the rationale specific to each project.

Jan 1, 2011

By Brian C. Asbury

Gold-bearing quartz veins with auriferou pyritic wall rock alteration haloes at the Komis deposit near Waddy Lake in northern Saskatchewan occur in fractured Archean intermediate volcanic rock flanking a plutonic felsic intrusion. Three ore zones totalling 1.5 million tonnes grading five g/t gold have resulted from a combination of patterns of high density of fracture-filling quartz veins created by contrasting competencies of four predominant rock types and preferential gold deposition in magnetitebearing andesite host rock. Pre-glacial surface weathering remobilized gold from a nearby pyritized intermediateto- felsic dyke to form the EP Zone with a wide variety of supergene accessory minerals. Much of the EP Zone wa eroded by glacial action to forn1 a highly anomalous gold-bearing till dispersion train which facilitated its di covery.

Jan 1, 1986

By H. H. Bird

Kilembe is situated in the foothills of the Ruwenzori Mountains in Uganda. Precambrian stratiform copper de-posits are currently being mined at a rate of 90,000 tons per month. Complex ore structures and variable ground conditions have led to diverse mining methods in the past. New mining areas contain more shallow-dipping, highly contorted orebodies, in heavy ground. Cut-and-fill mining will be practised in the future. The geology, mining and milling are described.

Jan 1, 1968

By D. A. Grieve

"Mineable coal seams in the East Kootenay region belong to the Mist Mountain Formation of the Jurassic -Cretaceous Kootenay Group. Three structurally separate coal fields (Crowsnest, Elk Valley and Flathead) are recognized, all of which are characterized by compressional tectonic features such as f aiding and thrust faulting, and by /ate-stage normal faulting. Tectonic history has greatly influenced coal mineability and quality. Coals range in rank from low to highvolatile bituminous, and reactive maceral content ranges from less than 60% to greater than 90%. A wide range of metallurgical and thermal coal qualities is found. Measured reserves (up to 1981) include 1.03 billion metric tonnes metallurgical and 165 million metric tonnes thermal coal. Introduction a) Location -Coal fields of the East Kootenays region occur in the Front Ranges of the Rocky Mountains, within 30 km of the Alberta -British Columbia boundary (Fig. 1). They extend over 175 km north from near the U.S. border, and occupy the regions of the Crowsnest Pass and Elk and Flathead River drainages. The deposits are accessible from Highway 3 (Fig. 1) and various secondary roads. The towns of Fernie, Sparwood, Elkford, Coleman and Blairmore serve the coal industry. East Kootenay coal deposits are contained in three structurally separate coal fields, the Crowsnest, Elk Valley, and Flathead coal fields (Fig. 1). Coal is currently being produced by B.C. Coal (now Westar Mining Ltd.) at Sparwood, by Fording Coal 20 km north of Elkford, by Crows Nest Resources at Line Creek 15 km southeast of Elkford, and by Byron Creek Collieries at Corbin. Westar Mining has also constructed a new mine on the Greenhills Range 8 km northeast of Elkford. Pre-requisite engineering and environmental studies have been carried out on the Elco Mining property, 35 km north of Elkford, and on the Sage Creek coal property near the U.S. border (Fig. 1). b) Coal land tenure -Coal rights in the East Kootenays are either held as freehold land, or are licensed from the provincial government. The former category includes lands acquired under the Railroad Act of 1890. Shortly after this the federal government also obtained 50,000 acres of coal-bearing lands from the Crown Provincial, the so-called Dominion Government Coal Blocks. Major holders of coal rights in the area are Westar Mining and Crows Nest Resources. Large blocks are also held by Fording Coal and related companies, Sage Creek Coal, and Canada Permanent Trust Company as trustee for Elco Mining, and small blocks are held by Byron Creek Collieries and Coleman Collieries. In addition the provincial government holds an area in reserve for possible future use of B.C. Hydro at the extreme north end of the Elk Valley coal field."

Jan 1, 1985

By Eduardo A. Pérez, Alejandro R. Alonso, Rosa María Luna-Sánchez, Gretchen T. Lapidus

Rare earth elements have been widely used in various sectors, from the aerospace and steel industries, to electronic applications, particularly in displays and batteries for portable devices. The high demand for newer and better equipment, such as cell phones, tablets and lap tops, has increased the consumption of the rare earth elements and at the same time the need for its recovery from electronic wastes. For that reason, the recycling of batteries is important, principally the Ni-HM batteries, due to their elevated content of rare earths elements, in addition to the high concentrations of cobalt and nickel. The current processes are based on dissolution in strong acid solutions (sulfuric acid concentrations from 2 to 4 mol/L), and temperatures from 30 to 90°C. In the present work, electrodes from spent Ni-HM batteries were leached using 1 mol/L H2SO4, in the presence of ozone as the oxidant, where recoveries of 96% for La, Ce and Nd were obtained at room temperature. The separation of Ni and Co from the leach solutions was performed using an electrochemical reactor, after which rare earth elements were precipitated, obtaining a mixture of its hydroxides with impurities below 1%, according to EDS analysis.

Jan 1, 2014

By C. L. Reichardt

"Pressure exerted on gold producers by regulators, project financiers, and civil society in the wake of the Baia Mare tailings spill in Romania during 2000 prompted most responsible gold companies to sign up to the International Cyanide Management Code for the Manufacture, Transport, and Use of Cyanide in the Production of Gold (the Code). The Code stipulates a ‘cradle to grave’ approach more comprehensive than that applied to any other mining reagent and poses particular challenges for operators who use cyanide-bearing tailings for backfill. This paper examine some of the challenges for Code compliance facing deep underground gold mines that employ backfill technology, most particularly the requirement to demonstrate that the potential migration of cyanide (and its degradation products) from emplaced backfill will not have an unacceptable impact on worker health and safety or on the receiving environment, either during mine life or after closure.Although the Code only contains a single reference to backfill, more careful consideration confirms that most sections of the Code that deal with tailings management are potentially applicable to mines where tailings material is used for backfill. Certain principles of the Code also pertain to aspects of operations, worker safety, emergency response, training, and dialogue with stakeholders relating to backfilling practice.For gold mines of the Far West Rand, the most significant cyanide-related risks associated with backfill operations relate to worker exposure to cyanide-bearing seepage and HCN gas. There is potential for seepage of cyanide-bearing water from backfill to compromise the beneficial use of surface and groundwater, and thus impact on downstream users and ecosystems. However, the extreme depth of mining and the specific geological and hydrological controls on the Far West Rand suggest that the potential environmental risks associated with backfill are likely to be considerably less significant than the cyanide-related risks to the workforce."

Jan 1, 2007

By H. D. B. Wilson, W C. Brisbin

The Thompson-Moak Lake nickel belt lies along the root of a Precambrian mountain range of the island-arc or alpine type. This range coin-. cides with the boundary between the Superior and Churchill blocks of the Canadian Precambrian shield. The nickeliferous peridotites and nickel ores occur along a negative gravity strip, which also coincides with strong thrust faulting and the axis of greatest deformation of the mountain range. Similar structures and highly nickeliferous peridotites occur in present-day island arcs. Much of the belt is covered by Paleozoic rocks, but a length of 270 miles may be explored by present-day methods. Nickel deposits have been located along 60 miles of the belt. The length of the favorable structure and the size of the known deposits suggest that this will be one of the world's major nickel regions. The regional gravity anomalies, which consist of a branching negative strip bordered by two positive strips, are best explained by major warps of a crust consisting of a granitic and basaltic layer. The ore deposit

Jan 1, 1961

By Beaumier. M., J. -P. Lalonde

"Les réultats obtenus dans les sols sur quatorze aires d'essai et six cheminements régionaux dans I'A bitibi-Témiscamingue indiquent clairement qu'il existe des variations régionales importantes dans les teneurs en éléments traces de l'horizon A1 formé sur l’épais recouvrement glacio-lacustre de cette région. Les anomalies obtenues correspondent à celles qui ont été décelées lors de précédents levés des eaux souterraines et du till de base.Selon les critères d'évaluation utilisés, treize des quatorze aires d'essai ressortent comme anomales dans Ie contexte abitibien; dix de celles-ci sont tres anomales. Ceci suggère fortement qu'un levé régional de sols, fondé sur une approche multi-éléments, identifierait entre 70 et 90 % des cibles géochimiques reconnues par des échantillonnages en profondeur. Les résultats d'un échantillonnage systématique effectué sur une région de 1000km2 viennent aussi appuyer cette hypothèse. Conséquemment, les sols formes sur les sédiments glacio-lacustres sont un médium très utile pour inventorier de grandes regions recouvertes par ce typ e de sédiments.L 'horizon A1 est Ie plus utile pour ce type de levé parce qu'i1 est facil e d échantillonner, qu 'it assure une plus grande constance du typ e de matériel échantillonne et qu'il contient des teneurs accrues.De multiples mécanismes de dispersion géochimique ont joué des rôles d 'importance variable pendant et après la mise en place des sédiments glacio-Iacustres. Les plus importants sont la pression hydrostatique, la diffusion chimique et électrochimique ainsi que la bio-accumulation. Si on veut progresser dans la connaissance de ce milieu complexe, on devra adopter une approche plus systemique tenant compte de I'interaction des mécanismes agissant dans l'environnement global avant, durant et apres Ie depôt du mort-terrain."

Jan 1, 1984

By A. S. Knight

THE breaking and handling of ore is obviously the most important consideration when the layout of a new mine is contemplated. The problem must be attacked with due regard to the claim area of the property, the dip of the orebody, the anticipated percentage of payability, the width of the reef, and the amount of dislocation anticipated by dykes, faults, or sills. Among these, as far as East Geduld is concerned, the three most important items are: Area. 2,640.5 claims. Average dip 12° (from flat to 35°) Average channel width 36 inches. We are fortunate on the Witwatersrand in 'chat there is usually sufficient information available from surrounding properties to determine, within narrow limits, the factors mentioned above. With this information avail-able, the choice of layout is not limited, and it will be found that on the Witwatersrand each group has developed its own technique to suit its individual requirements. On East Geduld, the layout of the property for handling ore is known as the endless-rope haulage system. Following is a brief description of the general principles followed.

Jan 1, 1942

By Tapio Leskinen

"In the 1960’s, when large flotation machines appeared on the market, this was a part of a world-wide trend towards the use of ever larger machine units.One factor that has played a decisive part in this development is the increased of the amounts of ore that have to be handled as the exploitation of successively poorer ores becomes necessary. The advancing application of instrumentation and automation has worked in the same direction.In 1970, a working group was set up within Outokumpu Oy, for the purpose of flotation machine development. The principal task of this group was to be the design and development of- a new type of rotor of increased efficiency, especially for the dispersion of large amounts of air- a mechanical-pneumatic flotation machine of substantially larger size that existing plant.This development project required an extensive program of theoretical investigation and experimental studies at several concentration plants of the company.The commonest flotation machine presently used in the concentration plants of Outokumpu Oy is the VK-3. It is of the mechanical-pneumatic type, and the volume of its cell tanks is 2.5 m3 per shaft. This machine was developed within the company, and its first development phase i s represented by the OKKO 3, built for the Kotalahti concentrator in 1959. It was, in its time, comparable in volume to the largest machines that were then in use anywhere in the world."

Jan 1, 1976