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By A. Warczok

Metal losses in discard slag are the main factor determining overall recovery. The metals are present both in dissolved form and as matte or metallic inclusions, varying in size from 2 to 1000 µm. Pyrometallurgical slag cleaning usually consists of heating the slag, reduction of oxides and settling of matte/metal droplets. Heating the slag decreases viscosity and accelerates reactions. Reduction of magnetite liberates inclusions and facilitates co-reduction of dissolved metal oxides. A significant amount of the matte and metal is present as very fine metallic inclusions, too small for settling. The coalescence of these matte or metal inclusions is required to remove them from the slag. The developed new concept of slag cleaning combines DC furnace technology with an extra magnetic field for vigorous slag stirring, enhancing mass transfer to the reductant surface, accelerating the rate of reduction, and destabilizing the emulsion of matte or metal inclusions. Intensive slag stirring increases the probability of collision of inclusions, will accelerate their growth and will therefore improve settling. The process is carried out in a patented DC channel furnace, where the liquid metal or matte layer acts as a cathode and the floating coke bed on the slag surface is the anode. In the first part of the furnace, a superimposed magnetic field induces a Lorentz's force causing the slag to start an intensive circular motion. The next furnace zone does not experience any stirring and is dedicated for quiet sedimentation of the inclusions. A mathematical model of gravitational coalescence combined with forced slag motion showed the possibilities of effective removal of copper matte inclusions. The results of laboratory pilot scale tests of continuous slag cleaning showed fast slag reduction and confirmed the improved matte removal from the slag. Conceptual analysis shows the potential use of the technology in various other non-ferrous industries, like for example nickel plants. It is also possible to use this technique batch wise.

Jan 1, 2007

By Kazutoshi Haga, Ariunbolor Narankhuu, Ariuntuya Battsengel, Yasushi Watanabe, Altansukh Batnasan, Akita University

"Rare earth minerals are usually concentrated by flotation, magnetic or gravity separation methods to produce concentrates that are subsequently leached with hydrochloric (HCl), sulfuric acid (H2SO4) or nitric acid (HNO3). About 75 % REEs are lost in gypsum by-product when apatite is dissolved in H2SO4, whereas more than 80% of REE can be extracted from the apatite using HCl and HNO3 leaching processes, respectively. Therefore, the main aim of this study was to find an efficient process of dissolution of rare earth elements (REEs) from apatite ore by sulfuric acid solution due to its lower cost. In order to optimize the dissolution process, effects of different parameters, namely, concentration of H2SO4 (0.05 – 6 M), solid/liquid phase ratio (1:50 – 1:100), temperature (20 – 80 ºC), agitation speed (300 – 900 rpm), and leaching time (0.5 - 6 h) on the dissolution of REEs from apatite ore were examined in various intervals. The contents of main REEs in the apatite ore used in this study were (as % wt): 3 % La, 6 % Ce, 0.6 % Pr, 2.1 % Nd, 0.2 % Sm and 0.3 % Y. X-ray diffraction (XRD) analysis identified fluorapatite and phlogopite as main minerals in the ore. The results obtained from leaching experiments showed that more than 85% of REEs were dissolved from the apatite ore under the optimized conditions, which were: 1 M H2SO4, particle size of -150 + 100 µm, S:L phase ratio of 1:50, agitation speed of 500 rpm at 20 ºC for 1h. The XRD analysis revealed that main mineral compositions of the residues from 1M and 6 M H2SO4 leaching are gypsum (CaSO42H2O) and hemigypsum (CaSO40.5H2O), respectively.INTRODUCTIONThe term rare earth elements (REEs) denote the group of 17 chemically similar metallic elements consisting of the 15 lanthanides, plus yttrium (Y) and scandium (Sc) in the periodic table. These metallic elements are generally divided into two sub-groups; (1) the cerium sub-group, which is called “light rare earth elements” (LREEs), includes the elements from lanthanum (La) to europium (Eu), and (2) the yttrium (Y) sub-group elements, which are known as “heavy rare earth elements” (HREEs), are the remaining lanthanides from gadolinium (Gd) to lutetium (Lu) plus yttrium (Gupta and Krishnamurthy, 2005). The REEs occur together in the minerals due to their chemical and physical similarities, which cause problems of separating them from one another (Abreu and Morais, 2014). Although REEs are relatively abundant in the earth’s crust, they are typically dispersed and rarely occur in concentrated forms, making them economically challenging to obtain. There are a wide variety of rare earth minerals, however economic deposits of REEs in mining are bastnasite (La, Ce) FCO3, monazite (Ce, La, Y, Th) PO4, and xenotime YPO4 (Binnemans, 2013; Xie, et al, 2014). Due to the unique physical, chemical, catalytic, electrical, magnetic and optical properties of REEs, demand of these elements has increased dramatically with the advent of new technologies in electronics, communication, construction, energy and medicine (Jordens, et al, 2013). Since 1990, China has provided about 90 % of REEs worldwide. Japan and United States are the largest consumers of China’s REEs. In 2010, China announced to reduce REEs exports to Japan, as it tended to increase prices of REEs and to reduce a stable supply of REEs in the world market (Humphries, 2013). Therefore, there has been an increase in recent exploration activities intended to reveal new commercial sources of REEs and to bring them into production (Antico, et al, 1996). Apatite is an important host mineral for REEs in igneous and metamorphic rocks and can be used as an ore for those metals (Kanazawa and Kamitani, 2006). Apatite is also the main source of phosphate fertilizers and phosphoric acid (Habashi, 2013; Emsbo, 2015)."

Jan 1, 2016

By D. S. Salonine

Aluminum alloys offer a wide range of capability with a unique combination of advantages that makes them the materials of choice for numerous products and markets. One of the most important applications is their use as the primary structure and outer envelope in aerospace vehicles. Wide and thorough studies on hot working and microstructure evolution of aluminum alloys have been made in Russia. The most important appear to be: - introducing the structure diagrams in strain rate - temperature coordinates which show areas of different microstructures (non-recrystallized, recrystallized, and mixed) after the hot deformation and the following heat-treatment for common aluminum alloys (Yu.M. Vainblat); - studying the press-effect ("structural effect" by V.I. Dobatkin); - learning the influence of hot worked substructure on aging mechanisms; conducting researches on press heat-treatment. These works allowed a deeper understanding and a better control of the mechanical behavior of aluminum products. Comparisons are made to equivalent developments in Europe and America.

Jan 1, 2004

By Lawrence Devon Smith

The Business Case for Sustainable Development ?What are SD & TBL? ?Investment Funds & Fund Managers ?Banks and Risk Aversion ?The Dilemma of Juniors ?Meet Your New Partners ?The Cost of Problems ?The Cost of Delays Sustainable Development ?Humanity has the ability to make development sustainable -to ensure that it meets the needs of the present without compromising the ability of future generations to meet their own needs.? Our Common Future BrundtlandCommission, 1987

May 1, 2003

By H. Kuno, H. Kobayakawa

A borehole inclinometer with FBG optical fiber sensors has been developed to clarify very slow slope movements, and the results of its application to a real slope have been shown. The main characteristics kept in mind while developing this inclinometer are as follows. Firstly, the workability must be good so that only one cable is required for taking the measurements, because the inclinometer is composed of several FBG sensor elements constructed on an optical fiber. Secondly, the minimum interval of the distorted measurements must be close, namely, within 100 mm. Thirdly, the inclinometer must excel in thunder resistance. The measurements were executed by setting up the developed borehole inclinometer on a slope where the rate of displacement is several millimeters per year. The movement of the device was developed by comparing it with that of the results of an existing borehole inclinometer. The area of the displacement concentration, 1 m in width for 4-m sections, was confirmed by the existing borehole inclinometer. The boring core, recovered using a high-quality drilling technique, was examined. Landslide clay was not permitted at the location where the displacement had concentrated as a result of comparing the measurement results with the boring core, and the rotation of gravel by the movement of the slope’s land block was allowed. These results show the slope being caught in the stage just before a primary landslide. In addition, the feature whereby the slope behavior depends on the depth was analyzed by comparing the information on the underground displacement with precipitation and earthquake records.

Jan 1, 2015

By N. J. Contini, R. W. Knopp

"In March 1988, old Denver flotation cells were removed from Dickenson's Arthur w. White Mill, and a new flotation circuit, consisting of four Prochem rougher cells and a Hydrochem agitated cleaner column, was commissioned. The refractory portion of the gold in the ore is associated with arsenopyrite, therefore the flotation circuit is set up to produce a saleable sulphide concentrate. Tailings from the leach circuit are conditioned prior to being pumped as feed to the flotation circuit. The prototype Hydrochem agitated column has been in operation as a single cleaner stage for rougher concentrate. The effect of flotation circuit changes on gold recovery data, as well as cleaner concentrate production, and development work to achieve the target results, have been investigated. Flowsheet modifications and the resulting circuit performance data, along with test results to date, will be presented.INTRODUCTIONThe mill is capable of treating 1000 stpd of ore averaging approximately 0.30 oz/ton Au. The ore is crushed and ground to 75% - 200 mesh. Gravity concentration, cyanidation, and Merrill - Crowe precipitation yields 84% gold recovery. Detailed descriptions of the comminution, gravity separation, and leaching circuits, as well as background information have been presented elsewhere (Suttill, Van Weert et al). The target cleaner concentrate grade is 1.0 oz/ton Au for custom smelting and refining. Historical gold recovery values of the old circuit was approximately 20% of the gold present in the float feed at the target grade. The recovery value objective set for the new circuit during the planning stages was 50% of the gold present in the flotation feed at 1.0 oz/ton Au in cleaner concentrate."

Jan 1, 1989

By X. Cao

Friction stir processing (FSP) is used to produce wrought microstructures at the surface of sand-cast aerospace grade magnesium alloy ZE41A-T5. It is found that the microstructure is significantly refined in the stir zone and the flow arm. The stir zone is largely comprised of equiaxed magnesium grains of approximately 4.5 pm compared with about 50 µm in the base cast material. In the stir zone, however, abnormal growth of some grains is also observed. Vickers microindentation hardness tests indicated that the stir zone experiences some increases in hardness. Single surface passes with low distortion, lack of pores and cracks were successfully obtained indicating the great potential of the FSP technique for modifying, improving and repairing magnesium alloy castings. This will probably open new opportunities to apply magnesium alloys in aerospace industry.

Jan 1, 2007

By G. Bonnivard

"A complete laboratory process for the treatment of lateritic ores containing a high proportion of iron, as well as chrome and alumina, has been established. The ores treated originate from the tropical zones and result from superficial climatic alteration. According to recent estimates, the known reserves of such ores reach many billions of tons, thus representing huge potential reserves for the elements they contain.The process used is based on the alkaline roasting of pelletized ore in the presence of sodium carbonate. This treatment results in the separate recovery of pellets of upgraded iron ore, pure chrome oxide and hydrated alumina. The research described in the paper aims at determining the best experimental conditions for obtaining the highest extraction of the required oxide from this type of ore."

Jan 1, 1967

By Harry J. Cain

Introduction The property of Pioneer Gold Mines of B. C., Limited, is located in the Lillooet mining district of British Columbia, on Cadwallader creek, 54 miles distant by motor road from Shalalth, a station on the Pacific Great Eastern railway. Milling by the present Company was commenced in 1924, a small amalgamation plant, consisting of a crusher, Bryan mill, and plates being operated until 1928. Tailing from this plant was impounded and later treated in the 100-ton continuous counter-current decantation cyanide plant which was erected during 1927-28 and placed in operation during May of 1928. A second cyanide plant, employing continuous counter-current decantation, having a nominal capacity of 200 tons, has been erected during the past few months and was put into operation during September of the present year. The ultimate capacity of the combined units of the present mill has not been determined, but it is expected to be much in excess of the rated capacity. The Ore The ore, as received at the mill, consists chiefly of quartz carrying free gold, with small amounts of pyrite, arsenopyrite, and pyrrhotite in evidence, though probably amounting to less than one per cent of the total. Some gold is very closely associated with the sulphides. The country rock is a basic igneous rock, probably an augite diorite. Near the vein it is highly altered to sericite, which slimes readily on grinding, and does not settle very well. The quartz is of two types, clear and ribbon. In the latter, the ribbons, which are not much thicker than paper, consist of shattered sulphides. In crushing this ribbon quartz, breakage is often along the streaks, exposing these shattered faces to advantage in subsequent treatment. While gold is the metal for which the ore is mined, some silver is also present and is paid for by the mint. It is, however, unimportant from a commercial viewpoint. From the standpoint of crushing and grinding, the ore might be termed 'medium 'hard'.

Jan 1, 1932

By Minerals Refining Company, Gerald Luttrell, Biao Li, Robert Bratton, Roe-Hoan Yoon, Stan Suboleski, Nikhil Gupta

Flotation is regarded as the best available method of upgrading coal and mineral fines in the mining industry. However, its efficiency deteriorates rapidly with decreasing particle size. Furthermore, ultrafine concentrates are difficult to be dewatered economically. Due to these technological problems, some operators are forced to discard at least part of the ultrafine materials to tailings (or refuse) ponds, causing significant losses of valuable resources and creating environmental concerns. To address these technological issues, a new separation process named hydrophobic-hydrophilic separation has been developed on the basis of the recent advances in the science of hydrophobic interactions. The results obtained to date show that the process can recover and dewater ultrafine particles simultaneously with high separation efficiencies. Following a series of extensive laboratory tests, the process has been scaled up to proof-of-concept and pilot-scale continuous tests. The results obtained with desliming cyclone overflows, screenbowl effluents, and by-zero coal flotation feeds can be cleaned to less than 4% ash and moisture with over 97% organic matter (or coal) recoveries. The results obtained with mineral fines also showed encouraging results.

Jan 1, 2016

By Fred A. Webber

STEEL ROPE WIRE is one of the more specialized commodities among the many grades of highcarbon steel wires. In its production there are many metallurgical aspects of interest from the steelmaking on through the final stages of wire drawing. We produce rope wire in an integrated mill com prising all the operations from the blast furnaces to finished wire drawing in the wire mills. Steelmaking is carried out with close control on hot metal, selection of scrap, and fluxing materials. The basic open hearths are of 170 tons capacity. Steel is teemed into 19 1/2 in by 19 1/2 in big-end-down molds and is hot-topped with the use of clay refractory hot-tops. The weight of this ingot is 6,900 pounds. All high -carbon steel ingots are charged hot into the soaking pits and are then rolled through the blooming mill in 16 p asses to a bloom ax~ in. by 41/2 in. and approximately 65 feet long. Necessary bottom and top crops are taken on the bloom as it passes from the blooming? mill to the billet mill. The still hot bloom is continuously rolled through the billet mill in . 5 passes to a 2 3/8 in. square. Billets are cut to 32 feet in length by a flying shear and then allowed to cool on the hot bed.

Jan 1, 1957

By E. G. Leonardon

The question of geophysical prospecting is one that is beginning to occupy a pre-eminent place in the minds of those actively concerned in the discovery and exploitation of ore deposits. This is in marked contrast to the reception accorded such ideas when the Junior author, six and a half years ago, began introducing electrical prospectii1g to the mining fraternity on this continent. Happily, the mention of geophysics no longer evokes the sceptical and pitying smiles that it did in those days. A little reflection will show that modern geophysical methods are merely a logical development from pre-existing technique. In the study of geological problems, is it not logical to use all possible physical properties of matter? The study of crystal form and cleavage, the examination of thin sections of minerals by means of polarized light or ordinary light, in fact, utilize physical properties of minerals for the benefit of the geologist. These are, of course, laboratory methods, and the extension of the study of similar properties into field work was inevitable. This began with the magnetometric surveys, used as early as 1760 in New Jersey to locate iron ores. Eighty-four years later, John Locke's work in the United States resulted in pointing out relationships between the terrestrial magnetic field and main tectonic features of the earth's crust.

Jan 1, 1928

By Edouard Asselin, Tasawar Javed

This study was conducted as a part of ongoing work to characterize sulphide concentrate leach residues generated under CESL (Cominco Engineering Services Limited) and Vale pilot and demonstration plant medium temperature (150 °C) process conditions. Three different samples were analyzed. Derivative samples were prepared by extracting gypsum, sulphur and amorphous/poorly crystalline iron oxyhydroxide phases from the leach residues. Thermal behavior of the samples was studied by thermal gravimetric analysis (TGA) and differential thermal analysis (DTA) in the temperature range 25 to 800 °C in both air and nitrogen atmospheres, with XRD analyses both before and after heating. Thermal transformation temperatures for different iron oxides/oxyhydroxides present in hydrometallurgical leach residues vary over a wide range which suggests the variable crystallinity of the phases. Raman spectroscopic analysis was carried out to help identify the type of iron phases in the residues. Furthermore, hydroxylamine hydrochloride (HaHC) and oxalate extractions were used to compare the fractionation of the amorphous/poorly crystalline iron phases in the residues. Given the compositions of the residues, any thermal events in the temperature range of 200 °C to 480 °C were attributed to amorphous/poorly crystalline iron phases.

Jan 1, 2014

By J. C. Keenan

Company-community agreements are widely considered to be a practical mechanism for recognising the rights, needs and priorities of peoples impacted by mining, for managing impacts and ensuring that miningderived benefits are shared. The use and application of company?community agreements is increasing globally. Notwithstanding the utility of agreements, the gender dimensions of agreement processes in mining have rarely been studied. Prior research on women and mining, however, does show that women are often more adversely impacted by mining than men, and face greater challenges in accessing development opportunities that mining can bring, however there is currently little to no guidance for companies, government or communities in terms of bringing a gender perspective to the fore in mining and agreement processes. While it is undisputed in human development literature that investment in women and sensitivity to gender delivers long-term health, education and local development outcomes, a number of key factors remain unexplored in debates about mining and development. These include: women?s participation in agreement processes, the gendered distribution of agreement benefits, and the extent to which impacts and benefits influence (either positively or negatively) women?s development and economic inclusion. This paper presents the results of an applied research project undertaken by the Centre for Social Responsibility in Mining (CSRM) at The University of Queensland and funded by a partnership between the Minerals Council of Australia (MCA) and the Australian Agency for International Development (AusAID). The project sought to connect with practitioners who had been directly involved in agreement processes to hear grounded perspectives on the interaction of gender dynamics and agreements, and connect those experiences with the broader literature. Findings from this study have implications for the role of companies and governments in promoting gender equality and empowerment as part of their commitments to sustainable development. A key challenge for companies will be navigating the territory of cultural norms and gender equality. The authors argue that without consideration of the gender perspective, and appropriate responses, mining agreements may not be inclusive or representative and may exacerbate gender inequalities and fail to contribute to long-term sustainable development.

Aug 1, 2013

By Akiyoshi Horiuchi, Manabu Kanno, Shigeki Sato, Taro Aichi

"AKITA ZINC Co., Ltd. (Iijima Zinc Refinery), jointly owned by DOWA METALS & MINING Co., Ltd.(DMM), has used the company’s own hematite process for iron control since the beginning of operations in 1971. The hematite process consists of reductive leaching with SO2 gas and iron removal in autoclaves by high temperature hydrolysis. This process enhances not only zinc recovery but also the recovery of gold, silver, copper, lead and rare metals, which is carried out at another DOWA metallurgical plant. All by-products produced in the hematite process are marketed and sold. This paper presents an overview of the hematite process and the recent process improvements made.INTRODUCTION DMM carries out mining and smelting activities for precious metals, PGMs, rare metals and base metals such as copper, lead and zinc. It owns KOSAKA SMELTING & REFINING, producing copper and lead, and the AKITA ZINC Co., Ltd. (AZC) in Akita Prefecture. DOWA is a specialized smelting company which has established a metallurgical complex for copper, lead and zinc, including a recycling business. AZC was established in 1971 at a production capacity of 72,000 t/y zinc; it is jointly owned by DMM and five other non-ferrous metal companies. AZC has increased its capacity continuously and now produces 210,000 t/y of zinc. Figure 1 shows the changes in zinc production and capacity at AZC."

Jan 1, 2016

By Wm. D. Jr. Sheldon

THIS paper presents practical data to aid in the selection of a mine ventilating fan, and outlines considerations to be made to ensure satisfactory operation and optimum efficiency of the fan. Much has been published on the general subject of mine ventilation, but the writer has found few specific data on factors and considerations which govern the selection of a fan-data which should be available to the operator if his fan is to give satisfactory service within the range of the high-efficiency portion of its performance curve and deliver the specified air capacity when operating against the anticipated range of resistance of the mine. The total quantity of fresh air furnished by the ventilation system must be adequate to provide, and to ensure at all times, safe and healthful working conditions in the mine. It is assumed that the mine operator is able to determine the air quantities required for the various parts of the mine.

Jan 1, 1941

By P. A. Studemeister

"A trondhjemite stock intrudes a volcanic sequence that has massive sulphide lenses and that is metamorphosed to the greenschist facies at Gutcher Lake, 25 km north of Wawa, Ontario. The stock is 4 km2 in plan and is partly enveloped by an aureole of chlorite-epidote-amphibolehornfels up to 1 km wide. Within this contact aureole, biotite is partly pseudomorphosed by chlorite;epidote and hornblende are mottled by chlorite, calcite, plus quartz; albite has 0% An to 8% An; and hornblende porphyroblasts have actinolite rims. The stock has chlorite pseudomorphous after biotite; and feldspar is mottled by white mica plus calcite and has a clear rim of albite. Fractures filled with quartz, calcite, ankerite, chlorite, white mica, pyrite, and native gold cross-cut the stock and its hornfels aureole. These gold-bearing veins are enveloped by foliated rocks with quartz, calcite, white mica, and chlorite that grade outward from the veins into trondhjemite or hornfels.The stock, emplaced into a submarine volcanic series, emanated heat that caused seawater to convect and formed a contact aureole of hornblende hornfels. The stock eventually intruded its aureole and this culminated with regional metamorphism to the greenschist facies. Regional metamorphism hydrated the stock and its hornfels aureole. Native gold precipitated with quartz along fractures from metamorphic flu ids in response to cooling and wallrock hydration. exploration for this type of gold deposits should focus around felsic intrusions that have albite and that have contact aureoles retrograded by regional metamorphism."

Jan 1, 1985

By J. A. Finch

For base metal sulphides, iron rejection starts in mineral processing. This review focuses on the changes in plant practice specifically to improve iron sulphide rejection by controlling contaminant ion effects and discusses selected innovations in mineral processing that can be expected to play a role in iron control. One change to control contaminant ions is size reduction (the use of stage grinding and inert stirred milling) and another is system chemistry (order of reagent addition and exploitation of the flexibility of sulphoxy species). Plant examples illustrate the successes, and indicate that there are several options available. The general innovations consider the new tools for measuring gas dispersion properties and quantifying froth characteristics from images. Examples of their application to improve concentrate quality illustrate the potential. Other innovations adapt geostatistics to model variations in ore flotation response to provide feed forward control and rigorously apply the statistical experimental methodology in plant test work. An example from one concentrator shows that significant improvements to reduce the iron content of concentrates can be achieved by applying these basic principles.

Jan 1, 2006

By G. Marchand, R. H. Hay, E. C. Pearson

"AbstractA polishing .technique is described together with two anodic etching methods for aluminum and its alloys. Some of the optical and structural characteristics of the film formed by •these etching methods are discussed and it is shown to what degree these properties of the film are related to the crystallographic orientation of the metallic substrate. Applications to the study of recrystallization and twinning phenomena and to the study of plastic deformation, banding, and texture estimation are discussed. Micrographs are shown .to illustrate the manner in which the technique is particularly well suited to the study of such phenomena.IntroductionThe physical metallurgist is constantly faced with the problem of polishing and etching of metallic sections. Mechanical polishing is tedious, time consuming, and not applicable whenever a surface entirely free from plastic deformation is required. Etchants are generally required to reveal the grain structure in order to determine its size, shape, and regularity, or to bring up constituents. In the case of aluminum, the .most common etchant to reveal grains is a mixture of three acids: HC1, HN03, and HF. This etchant is fairly satisfactory on certain alloys and for certain metallurgical conditions but in general fails to give a good definition of the grain on castings, on highly alloyed products, and whenever the grain is smaller than 100 microns in diameter. Besides size and shape, a grain, or crystal, has an orientation and may be endowed with several types of imperfections."

Jan 1, 1952

By André Piché

"Over the last ten years, several developments have been undertaken to conceive a machine capable of carrying out simultaneously all the mining tasks in hard rock deposits: cutting, mucking, hauling, ground support and dust control.The main advantages of continuous mining over conventional drill and blast is the elimination of the cyclical nature of the actual methods. Other advantages sought are improved stability of mine openings, higher productivity, lower costs, and a cleaner and safer mining environment. Noranda has con-tributed to these developments in a major way. As a member of HDRK, Noranda participated in the development of two mechanical continuous mining machines; the TM60 and the Wirth. Noranda also undertook a development of its own based on the utilization of electricity to break rock. This technology is called plasma blasting (PBT). The concept of plasma blasting is illustrated in Figure 1.When the operating voltage is reached (18kV), the energy is released through a high current switch (500k A) into a coaxial powercable. It is then delivered to the tip of an electrode inserted into a drill hole which is filled with an electrolyte (water). When the energy reaches the electrolyte, it is instantaneously transformed into a high temperature, high pres-sure plasma that produces a shock wave capable of breaking rock(1).After initial testing of the plasma blasting technology in the lab and in the feld, two experimental platforms were constructed. The first one, a test bench, was erected at the Noranda Technology Centre in Pointe Claire, Quebec.(2)The second one is a rock breaker prototype based on a standard diesel-powered carrier (Fig. 2). Each platform was equipped with a 300 kJ pulsed-power module.In 1993, the rock breaker prototype was used for an extensive series of tests in the field. During that campaign, over 700 oversized boulders were blasted. The results of the tests demonstrated that more durable components for PBT were needed. The test bench was then used to successfully develop and test long-lasting components (probe, switch, cable, connector) that can be adapted to industrial platforms leading to the commercialization of the technology."

Jan 1, 1996