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By H. G. Warrington

Abstract As part of the active development programme pursued by Dominion Magnesium Limited since 1945, a modern extrusion plant was erected and has been in operation for about twelve months. The only source of nigh purity magnesium in the world, Canadian metal is produced by metallurgical processes within the frame-work of the mining industry, which gives a different viewpoint to every phase of production from other world suppliers of commercial grade metal whose operations are based on chemical industries and techniques. The superior properties of corrosion resistance and grain refinement have aided a programme of standardization, reducing the number of alloys supplied in extruded form from seven to four as an aid to economic production. The first big step was the development of a general purpose alloy known as AZ?21x covering all decorative and medium stressed applications, which will supersede two older alloys. Sales approaching a million feet in this alloy show that it bids fair to become the 'mild steel' of the magnesium industry, its applications ranging from terrazzo floor strip to textile machinery and television mast components. In the high stressed field, metallurgical features preclude low-cost extrusion of the older high-strength alloys, but recent development of a magnesium alloy containing zirconium promises an easily workable metal. Hitherto produced by expensive chemical additions, research now shows that the alloy can be produced by metallurgical means, which may make this alloy available for a wide range of commercial applications. Thus the future development programme for extruded products in the form of tube, bars, shapes, and structural angles and channels may evolve two alloys to cover all applications for strengths up to 52,000 lb. per sq. in. Such standardization is the result of taking advantage of the physical and metallurgical properties of high-purity magnesium instead of accepting techniques based on metal produced by older processes.

Jan 1, 1951

By George M. Douglas

The southeastern shores of Great Slave lake present a curious anomaly in geographical and geological exploration, in that an area so large and important, and withal so comparatively accessible, should nevertheless have remained unexplored, unmapped, and indeed almost unknown, until quite recent" times On their return from the famous journey to the mouth of the Coppermine, the band of Indians with whom he travelled led Samuel Hearne across Slave lake. He was the first white man to see that great body of water and it is rather curious that it should have been seen first from the north rather than from the south. Hearne's account of the lake is vague, and he made no attempt ?to map the part through which he travelled. About 30 years later John Franklin, on his first journey to the Arctic, crossed the lake from the mouth of the Slave river to the Yellow Knife river. Franklin's maps show all of his route in accurate detail, except that part of it which lay through Slave lake. In 1833-34, Captain, afterwards Sir George, Back made the first exploration of the eastern end of the lake. Captain Back was then on his way to the Arctic coast by way of the Great Fish river, and his Indian guides led him through Great Slave lake by the route they had followed from time immemorial. This route, partly because of its directness, and partly because of its sheltered character, lay through the great mass of islands in the middle of the lake to the Talthei narrows, and thence along the sheltered north shore with its many coves and harbours. Pere Petitot made extensive journeys in Slave lake as well as other parts of the far north.

Jan 1, 1929

By Bradley Stoughton

It is very easy to reduce iron ore at a temperature well below its melting point and produce a more-or-less-pure metal which can be used directly for implements, tools, or machines. This simplicity has been the cause of much money loss by persons who were so satisfied with the successful operation of a process that they paid all too little attention to the commercial aspects of it. How easy a direct process is may be gleaned from the fact that it was practised with some -success by primitive man, and has been in almost continuous operation in one form or another for a period of probably 4,000 years. The production of steel in ton lots, beginning about 1860, brought a new phase into the economic situation, which, however, had been already greatly modified in 1784 by Henry Cort's invention of purifying pig iron. Direct processes survived both of these revolutions, under special geographical conditions, even up to the last few years of the nineteenth century, but ceased to have any general use as the basis of supply for structural, machine, or tool industries even in countries which could have manufactured iron by a direct process, but, instead, imported the product of established iron and steel processes. And this is still the situation today, notwithstanding the invention of an incredible number of 'new' processes since 1900, most of which are abandoned, and only survived as along as their financial backers were willing and able to Jose money. Probably none of these processes failed to work pretty well, and all seemed to show a handsome profit on paper.

Jan 1, 1930

"Previous studies on the effect of polytetrafluoroethylene addition during chalcopyrite leaching under conditions similar to those of the CESL process have reportedly resulted in complete leaching of the copper without the need for grinding of the flotation concentrate. However, these studies employed a pulp density of only 1% and finely sized PTFE particle that required the use of high impeller rotation rates that are not sustainable at an industrial scale. This paper explores the performance of 1/8” diameter balls of PTFE, that readily sink in the leach solution, on leaching performance at impeller rotation rates and ore pulp densities more typical of industrial practice. Possible routes for separation of the PTFE from the leach residues and their regeneration for recycling back to the leaching stage are also discussed.INTRODUCTIONChalcopyrite, CuFeS2, is the most important primary sulfide source of copper. While pyrometallurgical smelting of chalcopyrite remains the only widely accepted route for treating chalcopyrite concentrates, several medium temperature pressure oxidation processes are claimed to be economically feasible (Muir & McDonald, 2007). Among these, the CESL process has been extensively piloted and demonstrated at the prototype scale. The overall process chemistry of the CESL process may be summarized as follows (Marsden & Wilmot, 2007):4CuFeS2 + 5O2 + 4H2SO4 ? 4Cu2+ + 4SO4 2- + 2Fe2O3 + 8S0 + 4H2O (1)4CuFeS2 + 17O2 + 2H2SO4 ? 4Cu2+ + 10SO4 2- + 4Fe3+ + 2H2O (2)Though copper extractions of over 95 % are achieved, the CESL process requires extra grinding of the concentrate (Muir & McDonald, 2007). This is because leaching is conducted at temperatures around 150 °C, where the elemental sulfur produced is molten and grows thicker on the mineral’s surfaces as oxidation progresses, creating an increasingly large barrier for mass transport. In addition, the sulfur is sticky and tends to cause the mineral particles to agglomerate, effectively halting further oxidation of the particles that end up embedded within the agglomerates. Consumable surfactants, such as ligin sulfonate, have been shown to be effective at avoiding agglomeration, but they are not effective at removing sulfur from the minerals. Hence, their use does not obviate the need for fine grinding."

Jan 1, 2012

By Engineering Staff

"This paper briefly describes the surface mining operations at Smoky River Coal Limited (formerly McIntyre Mines Limited, Coal Division) near Grande Cache, Alberta. Geology, mining methods, equipment, manpower and reclamation and environment topics are discussed. Introduction Smoky River Coal Limited, a wholly-owned subsidiary of McIntyre Mines Limited of Calgary, Alberta, produces a high quality, low sulphur, low volatile bituminous coking coal from its minesite located at west central Alberta, approximately 20 km from the town of Grande Cache and 360 km west of Edmonton (Fig. I). Most of the coal property is contained within a 30 km long by 20 km wide block lying in a northwest-southeast direction in mountainous terrain. Elevations vary from 920 m above sea level ·at the plant·site on the Smoky River to 1,600 mat the upper levels of current and proposed mining operations. A total of 11 coal seams have been identified. Only two seams, No. 4 Seam and No. 10 Seam are currently considered of major commercial value. These seams are recovered by both surface and underground mining. Approximately 650Jo of the plant feed coal is obtained from a conventional shovel/truck surface mine; the balance is mined underground by room-andpillar methods. Background In 1921, McIntyre Mines Limited acquired some 26,300 hectares of coal leases at Smoky River. Since then the leases were explored intermittently by different companies including McIntyre. In the mid-l 960s exploration activities increased and several feasibility studies were completed. Development of the area was undertaken by McIntyre in 1968 and, in August of the same year, a long-term contract was signed with a consortium of Japanese steel mills for delivery of 2 x 106 t of clean coking coal for 15 years commencing in 1970. Production was focussed on underground mining, using longwall methods."

Jan 1, 1985

By G. E. Agar, W. B. Kipkie, R. A. Tenbergen

"This paper describes the successful pilot plant testing of a flowsheet, developed at INCO Ltd.'s J.Roy Gordon Research Laboratory (JRGRL), for improved separation of the constituent minerals in a bulk copper nickel concentrate.The flowsheet utilized the fact that xanthate concentration on the mineral surfaces is the most important variable affecting the high lime separation and that reduction of the xanthate concentration could be effected by an oxidative conditioning stage.When the adsorbed xanthate was reduced to a suitably low level, chalcopyrite and pyrrhotite could be floated to leave a high grade nickel concentrate as the residue. Sodium cyanide was added to the froth product to depress pyrrhotite and any remaining pentlandite. The temporary depression of chalcopyrite by the sodium cyanide was overcome by introducing a conditioning step following cyanide addition. The advantages of the flowsheet; improved copper-nickel separation, operation without heating of the pulp, production of both high grade nickel concentrate ( 29. 5% Ni, . 26% Cu) and copper concentrate ( <O. 5% Ni, 30% Cu) were all realized."

Jan 1, 1984

By S. A. Scott

In 1913, potash mineralization was recognized at a depth of over 7,000 feet in an oil-well hole (Norcanol&apos;s Radville No. 1 well) drilled near the town of Raddlle, Saskatchewan. Although, at this depth, potash is not considered mineable by conventional underground mining methods, this discovery shed the first light on the potash deposits of Saskatchewan in much the same manner as oil-well drilling was responsible for the first discovery of potash in the Carlsbad Basin of New Mexico in 19:25. The discovery near Radville alerted the oil-well geologists and, as a result potash mineralization was recognized in the Verbata No. 2 well, near Unity, Saskatchewan, in 1946. The mineralization, which was at a depth ?of 3,466 feet, graded more than 20 per cent K20 over a thickness of eleven feet. This discovery, as its depth, thickness and grade were all amenable to mining,

Jan 1, 1963

By K. Izumi

Ultra-grain refinement and high strengthening of metals by accumulative roll bonding (ARB) was widely reported. However, applications of ARB to magnesium alloys were rather limited. In this study, Mg-9%Li-1%Y sheets were applied to ARB at room temperature. Six 0.5 mm thick sheets were stacked and reduced into 0.5 mm thick by four passes. The procedure was repeated up to three cycles, so that the equivalent strain of 6.2 was applied. The sheets show dual phase structure with a (hcp) and ß (bcc). Grains elongates to the rolling direction with increasing number of ARB cycles. After three cycles, fragmented a grains with average size of about 300 nm are uniformly distributed. After the first cycle, the ultimate tensile strength increases to 180 MPa from 133 MPa, while the elongation decreases, however, still high (26%). The tensile strength slightly decreases by the second cycle and does not change at the third cycle. Meanwhile the elongation increases by the second cycle and the sheets show 41% of the elongation after the third cycle.

Jan 1, 2006

By Y. P. Malhotra, JE. C. Carter

"Syncrude&apos;s overburden removal requirement ranges from 20 million to 30 million bank cubic metres per year to meet tarsand demands for the production of 129,000 barrels of synthetic crude oil per day. The economic tar-sand lies beneath a variable thickness of overburden materials, composed of silts, clays, some sands of lacustrine origin, wind-deposited sand dunes, and out-wash sands and gravels.For the removal of overburden, Syncrude commissioned its own mobile equipment fleet in January 1981. This fleet consists of two Demag 241 hydraulic shovels, ten Titan 33-15B trucks and support equipment. Prior to this, all overburden removal was being carried out by contractors.This paper presents an overview of overburden removal at Syncrude, with particular reference to the performance of its own fleet.IntroductionThe Syncrude Tar Sands Plant was officially opened on September 15, 1978. After an expenditure of approximately $2.26 billion, the second and the largest commercial tarsands plant was on stream toward a permit production rate of 129,400 barrels of synthetic crude oil per day. The Syncrude Plant, a joint venture of six oil companies, the federal government and the Alberta government, is a major step forward toward the goal of Canadian energy self-sufficiency.The Mildred Lake operation of Syncrude Canada Ltd. Is located 40 km north of Fort McMurray and 480 km northeast of Edmonton in the Province o f Alberta.Synthetic crude oil leaving the plant is a blend of two-third s gas oil and one-third naphtha. The two streams combine in a pipeline and flow to Edmonton. The product takes six days to make the journey, arriving at four locations in the city Imperial&apos;s Strathcona Refinery, Gulf&apos;s Edmonton Refinery, the Interprovincial pipeline terminal and the Trans-Mountain pipeline terminal. Each Syncrude owner receives a share of oil equal; to its percentage of ownership in the project. At the present time, the oil is being utilized by Canadian refineries from Vancouver to Montreal."

Jan 1, 1983

By Michael Moats, Adirek Janwong

The use of cylinder electrowinning cells, such as emew® technology, for the recovery of silver from primary and secondary sources has been growing. In this study, common operating parameters used in silver electrowinning were evaluated for recycling applications. Silver powders were produced from an industrial solution in a laboratory scale emew® cell. A design of experiments was employed to evaluate the effects of HNO3 concentration, iron concentration, current density and solution flow rate on current efficiency, particle size, bulk density, and crystallographic orientation. Current efficiency was affected by each parameter with increasing HNO3 concentration having a strong negative effect, increasing iron concentration and current density having moderate negative effects and increasing flow rate having a positive effect over the ranges examined. Finer particles were produced with increasing current density and decreasing flow rate. Bulk density increased when HNO3 concentration increased. The crystallographic orientation of all powders was dominated by the (111) plane. Increasing flow rate decreased the relative intensity of (200) direction. Based on these observations, silver electrowinning in cylindrical cells can operate at high current efficiency and produce larger powders at low HNO3 concentration, low iron concentration, low current density and high flow rate.

Jan 1, 2014

By W. P. Campbell

Foreword At the outset, it should be stated that this paper does not pretend to present a panacea for the ills that &apos;frozen&apos; wells are heir to, but rather is an attempt to bring to the attention of those whose special concern it is, a little theory and some facts, which have been brought to light recently, in connection with the problem of &apos;freezing&apos; as it applies to naphtha-producing wells in the Turner Valley field, and to draw some conclusions that follow from the facts discovered. It should also be stated that the investigation is not to be regarded as in any sense complete, but in progress. Doubtless new facts will be brought to light from time to time which may modify present ideas on the subject, but whether favourable or contrary, these will be welcomed, as the purpose of the Department is to secure as complete information as possible of the factors contributing to &apos;freezing&apos;, since this must be the first step to an intelligent attempt to remedy or prevent its occurrence, if such can be done. It is possible, too, that the cause or causes of freezing may not be the same in all cases, but whether this be so or not will have to be determined later as new information comes to hand. Introduction One of the worries which must constantly confront the operators of gas-naphtha producing wells in Turner Valley-although all, fortunately, have not met with it-is the possibility of the occurrence of what is commonly called &apos;freezing&apos; (going off production).

Jan 1, 1930

By O. W. Ellis

Introduction During the month of September, 1928 enough money had. been promised by private individuals and corporations to comply with the Research ?Foundation Act 1928 (Chapter 57, 18 George V) of the Province of Ontario. The Ontario Research Foundation (referred to below as O.R.F.) may be said to 1iave come into being at that time. Under the terms of this Act, the Treasurer of the Province was empowered to match dollar for dollar of the sums subscribed by private .corporations and individuals up to a limit of $1,000,000. However, the response to the appeal for this by the Premier of the Province, the Honourable Mr. G. Howard Ferg uson, was so exceptional that the Act was amended in 1929 so as to empower the Treasurer to increase the maximum contribution on the part of the Province to $2,500,000. In March, 1933, the Chairman of the Foundation, Sir Joseph Flaville, Bart., was able to report that, in the interval between the Premier&apos;s appeal and December 1st, 1932, private enterprise had paid ?into the treasury of the Foundation $1,670,050, and that the Provincial Treasurer had assumed responsibility for a like sum. The endownment Fund of the Foundation was, therefore. $3,340,100. This sum was ?invested a lm~ s t entirely in Government securities, in securities guar. anteed by the Government, and in 1mmicipal securities. Sir Joseph Flavelle remarked at that time that "The payment of $1,670,050 to the Endowment of the Foundation by private persons and corporations is a somewhat remarkable performance when it is remembered that for three of the five years the business of the country has been suffering from a severe depression". Since that time it has been the consistent policy of O.R.F. to live within the income derived (1) from the investment of its Endowment Fund and (2) from fees collected for services rendered.

Jan 1, 1950

By Richard J. H. Barclay

The Lac Otelnuk iron property is located in the Province of Québec in the Northern Labrador Trough. The Labrador Trough is an extensive geosyncline of Proterozoic rocks, unconformably underlain by Archean gneisses. The Lac Otelnuk iron property hosts two significant magnetite iron-formation taconite deposits that outcrop, are sub-horizontal and are known to extend for at least 25 kilometres along strike. The host sedimentary rock package that includes a cherty iron formation is weakly metamorphosed to greenschist facies.

May 1, 2007

By R. A. Hemstock

"OIL EXPLORATION in Western Canada has produced outstanding results in the past few years. From such successes as Leduc and Redwater on the western plains, oilmen are now moving north in the ever-widening search for oil. They are reaching new frontiers and meeting new problems presented by this vast hinterland.One of the least known but most troublesome phenomena which will be encountered is permafrost. This term relates to a thickness of soil or other superficial deposit, or even of bed-rock at variable depths beneath the surface, in which a temperature below freezing has continually existed .for a long time. This permanently frozen ground affects, in many ways, oil exploration and exploitation. Seismic records are changed, pipe lines cannot easily be ditched into the ground, formation of wax is speeded-up in tubing and pipe lines, roads are difficult to build, and foundations of buildings and even of drilling 'rigs may require entirely new methods of construction.Permafrost underlies roughly one-fifth of the entire 'land surface of the world. It covers the northerly portions of Eurasia and North America. In the area that we are here concerned with, the southern boundary of permafrost extends south of east from about latitude 59°N. on the Pacific coast across the Rocky mountains, through Great Slave and Athabasca lakes, to cape Henrietta Maria, at the junction of Hudson bay and James bay (see Figure 1). Geologists generally agree that permafrost first appeared in the Pleistocene or Ice Age as the result of abnormal ground freezing."

Jan 1, 1952

By C. W. Taylor, F. L. Martin

"THE DICTIONARY defines Metallurgy as the ""science or art of separating metals from their ores and refining them for use"". In these days, however, such a definition is not detailed enough.The modern science of metallurgy is based on two fundamental sciences, physics .and chemistry, and is sub-divided into two major fields: Process Metallurgy and Physical Metallurgy. These fields of metallurgy are now so comprehensive and involved that even the graduate metallurgist has to specialize in one or the other.In recent years, the relatively new science or technology of non• destructive testing has also entered the industrial scene, with tremendous impact and ramifications. So much so that, certainly, no .discussion on metallurgy can be complete without including some reference to it.Obviously, one paper cannot hope to cover in detail the relationship of the whole science of metallurgy to the mining industry. Consequently, only a very brief reference will be made to the field of Process Metallurgy, our major concern being with Physical Metallurgy and Non-Destructive Testing."

Jan 1, 1960

By M. Aushouri, S. H. Mansouri, N. Aminizadeh

A thermo-chemical model of the Peirce-Smith copper converter has been developed to predict the molten temperature. The primary assumption of the model was that all matte, slag and gaseous phases in the converter were in thermal and chemical equilibrium. In this model, the matte components were considered only as copper, iron and sulfur elements. In the slag making stage, all the reacted iron was converted to fayalite. The reaction rate of iron and oxygen in this stage was considered to be constant. The converter temperature was calculated by heat balance over time. The model was validated by a detailed comparison with measured industrial data. A good agreement was obtained. The converter temperature depends on process parameters such as oxygen efficiency and molten emissivity.

Jan 1, 2007

By A. H. Onur, S. Ural

"The Afsin-Elbistan coal deposit with its 3.4 billion metric tons of reserve is the biggest coal basin and one of the most important resources for electrical energy production in Turkey. The coal deposit is located north of Elbistan, Kahramanmaras Province, in southeast Turkey (Fig. 1).The Kislakoy sub-basin of the Afsin-Elbistan basin was selected as the first open cast mine to feed four power station blocks of 340 MW each. The mine is equipped with six identical bucket wheel excavators of the type Sch Rs (2300/5) 32. The annual coal demand of the power station is 18.5 million metric tons. The Elbistan basin encompasses an area of 900 km2, and its centre lies about 1150 m above mean sea level. The sedimentation took place mainly in the upper Pliocene period. The thickness of the coal bed varies from 20 m to 60 m, respectively. The basal part of the coal beds consists of clay, marl and sandy clay. These formations are overlain by gyttja, which may also occur in the form of calcareous ooze, enveloping coal beds. The thickness of the gyttja is up to 35 m (Otto-Gold, 1969). The coal of Afsin-Elbistan is soft coal and the quality has been found to vary considerably throughout the deposit. The thicknesses of the sterile intercalations vary from 0.50 m to 2.2 m and average 1 m in thickness. From the quality control point of view, the coal seam is regarded as upper seam where the gyttja formation occurs as sterile intercalations, and lower seam where the clay formation occurs instead of the gyttja (Fig. 2). The CaO content of upper Kislakoy coal is very high, grinding resistance is low and base to acid ratio of ash, that is, the ratio of acid oxides of metals to base, is greater than one (Ural and Onur, 2001). Contrary to upper Kislakoy coal, CaO content of lower Kislakoy coal is very low, grinding resistance is high and base:acid ratio of ash is smaller than one. Modified Impact Strength Index (MISI) tests are used to determine the grindability of the Elbistan coals (Ural, 1999)."

Jan 1, 2003

By J. M. Goris

"Researchers at the U.S. Bureau of Mines are conducting research on cable-type ground supports to assess their material and support properties and to provide design criteria for implementing cable supports as a workable roof control system under various underground mining conditions. Much of this work involves laboratory assessment of the material and support properties of cable supports using both conventional and birdcage steel cables. Included in this assessment are single and double cables, effects of changes in embedment length on support strengths, water-cement ratios, use of breather tubes, and pumpability and water-bleeding properties of grouts.IntroductionSince cable supports were introduced in the early 1970s, considerable research has been conducted in laboratories and at mine sites to understand their behaviour. The U.S. Bureau of Mines began a laboratory evaluation project in 1985 at the Spokane Research Center (SRC) to study the behaviour of cables supports under uniaxial loads so that the effects of various cable support components, such as grout and breather tubes, could be identified. Other objectives were to compare the behaviour of various types of cables and grouts and to collect meaningful data for numerical analyses. Pull tests were conducted to determine how cables supports reacted under uniaxial loads and how they failed when ultimate loads were exceeded. Such data are essential for the development of numerical models for analyzing rock mass behaviour when the rock is supported with cables.Test ProgramBecause each cable support can be composed of either single or double cables as well as a breather tube, pull tests were designed to include a variety of samples containing these components. A series of samples containing a single conventional cable, a neat cement grout having a water-cement ratio of 0.45, and no chemical additives was selected as a standard (Table I). Then one component in the system, such as the presence of a breather tube, was changed, and results of tests compared to results obtained for the standard samples to determine what influence that component might have on the behaviour of the support system. If significant changes in test data occurred, they could be attributed to that one component. To control the quality of the samples, the physical condition of the cables and tubes were monitored closely, and compressive and tensile strengths as well as flow properties were determined for the grout used in each test series."

Jan 1, 1991

By H. Harzer

Statistics Canada record s indicate that in recent years 70 to 80% of the entire Canadian coal production originated from Western Canadian mines, in which about 55 to 65% of the coals are bituminous. Until recently, less than 20% of the latter were extracted by underground methods , the remainder being surface-mined. However, it is estimated that within the foreseeable future up to 80 or 90% will have to be gained by underground techniques. Although Western Canadian coal resources are considerable, they are unfortunately locked in severely distorted, steeply pitching and faulted seams of variable thickness. Consequently, their economic extraction poses serious engineering problems. One possible solution to the problems is to apply hydromechanical methods to underground mining. This is a well-proven method shown to be economically viable under Western Canadian conditions. This paper endeavours to widen the scope of published data on hydraulic coal mining and is based on practical engineering and cost data gathered through contacts with West German designers and operators of hydraulic mines.

Jan 1, 1978

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