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By S. A. Kenzap

Risk & Uncertainty ? Uncertainty about a situation can often indicate risk, which is the possibility of loss, damage, or any other undesirable event. Most people desire low risk, which would translate to a high probability of success, profit, or some form of gain. Risk = Likelihood x Consequence Risk is the possibility of loss, damage, or any other undesirable event.

Oct 1, 2010

By Young Hyun Paik, Hyung Sup Choi, Yeun Sik Kim

The basic studies on the surface properties and flotation characteristics of ilmenite were made by electrophoretic, adsorption, contact-angle and floatability measurements. The isoelectric point of ilmenite is found to be at pH 5.6. By combining the results of electrokinetic studies and adsorption measurements, a clearer picture of the ilmenite-solution interface was observed. These findings were correlated with the floatability of ilmenite obtained by Hallimond tube tests. The general flotation characteristics of ilmenite are compared with those obtained for magnetite and rutile. It is indicated that the above three minerals, namely, ilmenite, magnetite and rutile, have very similar surface properties and flotation characteristics. Therefore, it is difficult to make an effective separation of these minerals by flotation. However, it is found that sodium orthophosphate acts as a selective depressant for magnetite in anionic flotation. Therefore, close pH control of the pulp in the presence of the phosphate ion enhances the possibility for a successful separation of these minerals.

Jan 1, 1967

By S. G. Shabestari

Thermal analysis is a tool that is generally employed to predict the structure of the alloy before the actual casting is carried out. By cooling a sample of the molten alloy and recording the temperature-time curve, important solidification events may be analyzed by using the first derivative-cooling curve. In this research, strontium is added to (AS5U3G) 319 aluminum alloy and its influence on the formation of intermetallic compounds e.g. Al15(Mn,Fe)3Si2, Al2Cu, Al5Mg8Cu2Si6 formed during pre- and post-eutectic reaction have been investigated. Also any changes in solidification parameters such as temperature of Al-Si eutectic under cooling and temperatures of nucleation and growth of each phases caused by strontium addition, have been determined via the first derivative cooling curves. The effect of strontium on the formation of various intermetallic compounds has been studied by using very accurate thermal analysis equipment and the microstructures were analyzed using an optical microscope. The various phases reported in this paper were identified using Scanning Electron Microscopy (SEM) and linked to Energy Dispersive Spectroscopy (EDS). Formation of all pre- and post-eutectic phases was interpreted by comparing the phases formed in the microstructure and the reactions detected by using cooling curves. The results of this research indicate that thermal analysis technique can be used as an on-line process control in the production lines in aluminum casting industries.

Jan 1, 2004

By J. R. Maxwell

In 1970 expansion was completed increasing mill capacity from 2,000 to 3,000 T.P.D. Actual grinding capacity is 3,400 T,P,D. at a grind of 60% -200 mesh,The ore bodies are vein type, containing about 12% sulphides, with mill heads averaging 2.25% Cu, 0.015 oz.Au, and O.4O oz, Ag. per ton.Summary and Conclusions:During the period Jnnuar-1 1971 to December 1973 inclusive the use of large cells at Opeminka have shown that metallurgy is comparable to when using conventional cells, Operating and maintenance costs are lower, An on stream analyzer with reagents controlled by computer, are being assessed further.Opej1atljn Of Cells:!lo cell level adjustments are required when tonnage is adjusted 20 to 25%.Depending on mill heads and grade of concentrate reagents are adjusted to the first rougher for metallurgical control. Reagents to second rougher and scavengers are seldom adjusted as feed to this section has a maximum variation of about 0.2'~ Cu.Power – Maintenance and Space Requirement :Our total power consumption for 3,400 T.P,D. flotation circuit for operation and air supply is 280 H.P. Previous power drawn using conventional cells was 400 H.P. at 2,000 T.P.D.Total maintenance costs for flotation circuit has averaged $1,100.00 per year for the 3 years of operation, this cost should remain constant.Floor space required for cells and walkways is 2,000 sq.ft.

Jan 1, 1974

By A. S. H. Kabir

Due to the high specific strength and excellent corrosion resistance, Ti-6A1-4V has been widely applied in aerospace industries. In this study, the welding performance of 3.2-mm and 5.1-mm thick Ti¬6A1-4V sheets was studied using a 4 kW continuous wave Nd: YAG laser. It is found that the use of filler wire, matching the parent metal composition, can bridge the joint gap and produce full penetrated welds up to a width of 0.6 mm without cracking. The laser welds were characterized in terms of the bead geometry, defects, microstructures, and hardness. With increasing joint gap, the percent porosity area increased, reaching just over 1% of the fusion zone area at a gap width of 0.6 mm for the 3.2 mm and 5.1 mm thick sheets. The maximum underfill depth in the Ti-6A1-4V laser welds was about 5% or 7% of the sheet thickness for the 3.2-mm and 5.2-mm thick materials, respectively, meeting the AWS D17-1 specification. The microindentation hardness was maximum in the fusion zone and sharply decreased through the heat affected zone until reaching the base metal value.

Jan 1, 2011

By P. H. Rodriguez

The aquatic hazard classification system of the OECD and EU requires that sparingly soluble metal substances (SSMS) be tested using the OECD Dissolution/Transformation protocol in order to quantify the release of the ecotoxicological relevant species (dissolved ions). The SSMS category contains massive forms of metals, which due to their low solubility and slow transformation characteristics are a special case. The main factors that produce the release of metal into solution are exposed surface loading, pH, and stirring rate. The classification system at present prefers the use of mass loading as opposed to surface loading, in which case the amount of metal released will primarily be a function of the pH, and mass loading. Within the framework of the European Copper Voluntary Risk Assessment, coordinated by the European Copper Institute, we have proposed and developed a methodological procedure in which we demonstrate that surface area is an intrinsic property of a SSMS and we link the exposed surface loading to the toxicity reference value in order to obtain an aquatic hazard classification for massive metals. As example, the aquatic hazard classification for copper massive will be discussed. This approach is recommended for metal massives and metal powders.

Jan 1, 2007

By E. A. Davies, Trevor T. Jones

"Aspects of materials, design and operation of suspension equipment is dealt with, hazard, fatigue and special metallurgical properties of certain steels to resist are described, as is the effect of temperature in service modifying the properties of some steels to resist stress concentration and propagation of cracks.The influence of steady impact and fatigue loading and its results are described. Control of manufacture including nondestructive testing is outlined and acceptance parameters and strength calculations are given. Quality requirements and control in manufacture are outlined. A short description of the overwind detaching hook, together with illustrations of the operation of detachment are presented.MaterialsWinding engine ratings of 8000 h .p. and large capacity shafts 2000 m in depth (4000 m depths have already been reached and it may be necessary to go to 6000 m) and up to ten conveyances are not uncommon today. Loads of 100 or even 200 tons hoisted at low speeds are possible within the near future. Some of these appliances are designed to protect lives and installations in hazardous conditions when, due to human or mechanical fault, a malfunction occurs in the system. In addition, such equipment includes suspension gear of various kinds designed to anchor and apply high mechanical tensions to numerous steel ropes installed in shafts necessary either for the safe passage of conveyances or for balancing purposes when heavy loads are in motion.No unique metallurgical problems are presented in underground mining operations, but they have two special characteristics that influence the metallurgical aspects of the de sign of suspension gear and other equipment concerned in the transport of men and materials. (1) Any uncontrolled release of energy caused by the unexpected failure of a component is more likely to injure personnel and cause costly damage to installations in the narrow confines of an underground mine shaft. (2) Some mechanical equipment in mines, tends to be overloaded in service and suffer plastic distortion."

Jan 1, 1987

By Hooman Askari-Nasab

Open pit mine plans define the complex strategy of displacement of ore and waste over the mine life. The objective of the mine plan is to maximize the future cash flows within the technical and physical constraints. Various mixed integer linear programming (MILP) formulations have been used for production scheduling of open pit mines. In the MILP formulation the slope constraints guarantee that all the overlying blocks are mined prior to mining a given block. Traditionally, the slope constraints have been modeled with cone templates representing the required wall slopes of the open pit mine. The overall pit slopes constructed by these templates are a function of the width and height of the geological block model. Therefore, the overall slopes are fixed in one bearing. This paper presents a general MILP model for open pit mine scheduling with variable slopes constraints. The methodology utilizes a directed graph to capture the precedence of extraction of blocks and pit slopes in different bearings. Depth-first-search algorithm was used to traverse the graph for constructing the slope constraints in the MILP problem. TOMLAB/CPLEX was used as the implementation platform to efficiently integrate the mathematical solver package CPLEX with MATLAB. A case study on intermediate scheduling of an iron ore mine over twelve periods was carried out to validate the models.

Oct 1, 2009

By R. G. K. Morrison

As mines grow deeper, the problem of ground control becomes one of increasing importance. The literature on the subject has grown extensively in the past few years, but is still far from conclusive. Detailed and precise observations are on record covering most phases of the problem, and control measures have progressed to the point where, in a large measure, they are effective. The success of methods to date must be attributed to the efforts which have been exerted to reduce convergence of stope walls and to the realization that a regular progression of stope faces approaching longwall has a beneficial effect. This paper attempts to explain the relationship between these two factors and the general problem of ground control. The problem at present lacks the co-ordination of the practical with the scientific outlook, but fortunately as time goes on there are indications that our scientific friends are becoming more interested and more familiar with the practical issues involved. Opinions vary widely regarding the mechanism of the problem and there are several schools of thought, two only of which will be discussed. One associates the incidence of rock-bursts with the stresses built up by a sagging hanging-wall, while the other takes the view that stresses primarily responsible for the sagging hanging-wall are also the cause of rock-bursts. The first group starts its reasoning from the convergence of the walls, probably the most conspicuous feature of deep mining, and works back to the conclusion that rock-bursts are in sorne way due to the breaking up of the sagging layers. The second group begins with the stress zone apparent around excavations at depth and follows mathematical conceptions based on certain assumptions which, in the absolute sense, are known to be inaccurate, but which are justified by the similarity between the conclusions reached and the results obtained in practice. This reasoning is followed to the point where rock-bursts result from the failure, under stress, of rock in situ, quite independent of wall convergence.

Jan 1, 1939

By P. Personnet, D. Wheaton, E. Couzinie, V. Demetriou, Brooks. W., G. Girault, M. Meyer, L. Charbonnel

A common problem in Gas Treatment Centers (GTC) from primary aluminium smelters is the temperature of the gas to be treated : above a threshold, filtering media are irreversibly damaged. The traditional way of dealing with high gas temperature is to dilute with fresh air, which implies over sizing - and therefore higher cost for - the GTC in order to have the capacity to treat this dilution air without compromising on pot suction. A system was developed which decreases gas temperature without having to use dilution air. This system is based on water pulverization in gas collectors. The water vaporization leads to a temperature decrease of the gas. A pilot system was trialed in our R&D unit. Satisfactory results led to the development of an industrial system based on Envirocare equipment (partnership), which was trialed in our production plant in Tomago (NSW, Australia). This patented system was then generalized in this plant, which is now using it with success during austral summer.

Jan 1, 2006

By H. N. Tran, D. Barham

"A systematic survey of the appropriate literature in terms of phase equilibria and possible reactions involving deposits in Municipal Solid Waste (MSW) incinerators are analyzed particularly with respect to the theoretical first melting points of typical ashes and the possible presence of a liquid phase at the temperature of ash-metal interface. Conclusions are drawn on the basis of the possible presence or absence of various metal chlorides and sulphates in such situations, and their effects on the problems of fouling and metal corrosion. From preliminary results, it would appear that ZnCl2 is unlikely to be present in any molten phase which causes corrosion because it evaporates rapidly from such liquids. It would also appear that PbCl2 and, by inference, ZnCl2 will sulphate at relatively low temperatures if the flue gas contains SO2 and O2.IntroductionMunicipal Solid Waste (MSW) incinerators produce fly ash which deposits on heat transfer surfaces throughout the furnace, leading to corrosion and loss of energy recovery efficiency. Despite a massive amount of research carried out on the subject of corrosion in MSW incinerators, the problem of corrosion of heat transfer metal is still with us, and no definite over-all cause and effect relationship has yet been identified. In order to make a contribution to the eventual solution of this problem, the authors have examined the problem from the beginning, using their knowledge of fouling and corrosion problems in black liquor recovery boilers as a starting point.The incineration of MSW has been used for many years to reduce the volume of material sent to landfill (ash volume compared to raw waste volume), and, in most cases, to recover energy at the same time by raising steam The steam may be ""low- or high pressure/ temperature"" depending on its end use. The higher the steam pressure and temperature, the greater seem to be the problems with corrosion of heat exchanger metal, presumably because the metal must withstand higher surface temperatures.The chemical and physical composition of MSW is extremely variable, not only on a regional basis, seasonal basis, and day-today basis, but also on a minute-by-minute basis, due to the inhomogeneity of MSW. This makes it extremely difficult to define cause and effect relationships, because both cause and effect are transient in nature."

Jan 1, 1991

By C. O. Campbell

THE recognition by C. W. McKee, field engineer for Springer Sturgeon Gold Mines, Limited, in the fall of 1940, of the economic possibilities of a small outcrop of baryres near Pembroke, in Hants county, Nova Scotia, followed by aggressive exploration and development by the Company, has placed Canada for the first time in its history in the position of becoming a major producer of barytes and its products. In past years, production of this mineral in Canada has been unimportant. Thus the coral output from 1885 ro 1933, inclusive, amounted to only 41,027 short tons, following which there was no production until 1939. Deposits in Nova Scotia, and particularly in the Lake Ainslie district, Cape Breton, have been the main source of supply, with a production between 1866 and 1925 of 31,689 tons. Following the examination of the outcrop of baryres near Pembroke by Mr. C. W. McKee in October, 1940, the area surrounding it was trenched, and, as this work gave encouraging results, a diamond drilling programme was commenced. A grid system was laid our and sixteen holes aggregating 2809.3 feet were put down, spaced at 100-foot intervals, the deepest hole being 300 feet. This drilling outlined a body of high-grade baryres over 600 feet long and 200 to 250 feet wide, with an average depth of 120 feet and estimated to contain well over one million tons of ore. The limits of the body were reached on the west, north, and southwest, but the drilling was suspended before the eastern limit was determined. Quarrying operations, and construction of a 100-ton mill, were commenced in February, 1941. The mill was placed in operation on May 29th, and on June 15th, eight months after the initial discovery, the first shipment of 2,500 long rons of milled baryres was made to Trinidad, British West Indies.

Jan 1, 1942

By JAMES E. TILSLEY

Veins at St. Lawrence near the tip of the Burin Peninsula in southeast New/ oundland have been the major Canadian source of fluorspar. Some 2.8 million tonnes were shipped during the period 1933-1977, mostly from five of the more than forty veir.s known. Most of the veins occur in granite. individual veins may be several km in length, comprising a number of mineable lenses up to 760 m long and 25 111 thick. Fluorite content averages about 50 per cent, but may exceed 90 per cent locally. Quartz, calcite, barite and a few sulphides are the other vein constituents. Jn recent years, gravity concentrates were shipped to a flotation plant at Arvida, Quebec, where the fluorspar concentrate was used as a flux in the making of alum in um. Competition f rom Mexican fluorspar was a major factor in the closure of the mines. Ample reserves are available should economic conditions improve.

Jan 1, 1984

By James McMahon

Although doubt has been expressed many times as to who first brought self-contained breathing apparatus to this side of the Atlantic, there is none whatever that the first organized station was established at Glace Bay, N .S., by the Dominion Coal Company, in 1907. This station was started with 20 sets of 1907 "Draeger" apparatus and all necessary station equipment and supplies. After the fire at No. 1 pit, Sydney Mines, in 1908, the Nova Scotia Steel Company installed 15 sets of "Draeger" and sup-plies, which were housed in a rescue car (a converted pull-man.) In 1909 or '10 a fire occurred at the Back Pit, Stellarton, where the apparatus from Glace Bay was used, and subsequently the Acadia Company erected a station and in-stalled 10 sets of "Securitas" apparatus. In 1912 the station at New Waterford was opened and equipped with "Draeger," and the same year the station at Springhill was built and equipped with the same type. Sometime during past years the Nova Scotia Steel Company acquired a couple of "Proto" machines, and after the explosion at the Allan shaft in 1918 the Acadia Coal Company added some "Gibbs" to their station. From this it will be seen that when the coal-fields were organized under the British Empire Steel Corporation the equipment was rather mixed, therefore steps were taken by the executive to stanardize the whole of the rescue and recovery work.

Jan 1, 1924

By E. Mohammadi Zahrani

In this study, Mg-doped fluorapatite (Mg-FA) nanopowders were prepared through a sol-gel, technique and characterized. Designated degree of Mg2+ ions incorporation into the apatite structure was indicated by the x value in the general formula of (Ca10-xMgx (PO4)6F2), where x=0, 0.25, 0.5, 0.75, and 1. XRD, AAS, FTIR and TEM techniques were utilized to characterize the synthesized nanopowders. In vitro bioactivity of the powders was evaluated in simulated body fluid. Powders had a crystallite size less than 100 nm. It was concluded that Mg-substitution could alter bioactivity and dissolution behaviour of Mg-FA. These two parameters were proportional to magnesium content of the powders.

Jan 1, 2010

By A. Aubin, H. Yang, G. Zaluski

The Athabasca Basin of northern Saskatchewan and Alberta is an exceptionally rich metallogenic region, hosting more than 2.8 B lb U3O8, of which over 927 M lb U3O8 have been mined out since extraction first started in the late 1970’s. A detailed compilation of several empirical features of 85 deposits located within the basin was conducted in order to understand the distribution and variability of the geological characteristics of the mineralization and its associated alteration. A new empirical classification was devised based on four parameters: 1) geometry of the mineralization (dimensions and relation to the unconformity surface), 2) size, grade and metallurgical complexity of the mineralization, 3) lithostructural setting, and 4) extent and nature of associated alteration haloes. This compilation defines the footprint characteristics of the Athabasca Basin deposits, which guides decision-making processes from early exploration and discovery to resource expansion and extraction.

Jan 1, 2020

By C. M. Campbell

The Inconceivable Wealth propaganda goes on apace. Premier King, at Vancouver, has stated that we still have, untouched, natural resources, "beyond the wildest dreams." Principal Currie, in an address before the Canadian Society in New York said that Canada's resources, "are as yet merely scratched and it is not possible to compute her almost fabulous natural wealth." Mr. Meighen, in the last election campaign announced that, "under the providence of God, Canada is more richly endowed, perhaps, than any other country in the world." Four years ago a despatch was sent to Premier King "on behalf of" this Institute advising him that "Inconceivable Wealth" in minerals in this country was assured. This was made as a statement ~f "incontrovertible fact." Specifically, this despatch stated that this wealth was on such a scale that the mining industry would in the future lead all others in this country. This inventory is still in effect as far as this Institute is concerned.

Jan 1, 1926

By G. Avramovic-Cingara

Grain boundary characteristics and microstructural evolution are analyzed in a comparative study using orientation imaging microscopy (OIM/SEM) and transmission electron microscopy (TEM/SAD). The subgrain sizes and misorientations were determined by the OIM for aluminum deformed in torsion to equivalent strains between 0.2 and 4 over the temperature ranges of300-600°C and strain rates 0.01-1 s". The OIM gives clearer evidence of boundaries with high misorientation than does TEM, but it overestimates their frequency b y missing boundaries less than 1 0. T EM more clearly reveals low-angle arrays of widely spaced dislocations resulting in finer subgrain sizes than those indicated by OIM. The evidence supports a mechanism combining dynamic recovery (DRY), deformation band formation with permanent boundaries and geometric dynamic recrystallization (gDRX) in contrast to the hypothesis known as continuous dynamic recrystallization (cDRX).

Jan 1, 2004

By I. E. Puddington, F. W. Meadus

The beneficiation of barite in mill tailings using an agglomeration technique has been demonstrated. Barite was selectively absorbed from a conditioned aqueous slurry into a collector oil by mechanically mixing slurry and oil. The resulting oil-bonded barite-containing agglomerate was washed, to remove gangue material, and further mechanically contacted with dilute H2SO4 This treatment resulted in the transfer of barite into the aqueous phase. Grades as high as '97% BaSO4, with recoveries of 80%, have been obtained using this technique.

Jan 1, 1973

By Hans Lundberg

The magnetometer which was developed during the war for detecting submarines has proven exceedingly valuable in outlining deep-seated structures in oil exploration, and will be useful also to geologists in outlining regional structural features in the Precambrian. Our magnetometer has been developed to outline local and detail structures. 1 am quite sure that all geophysicists and geologists would agree with me that, in ore prospecting, it is important to obtain as much detailed information as possible. We know that, as we ascend from the ground and get away from the magnetic ore-bearing structures and orebodies, the magnetic intensity decreases rapidly, but, worse than that, we lose the details even faster. Figure l shows two strong, very sharp, magnetic 'highs' over two orebodies which, as our distance increases, rapidly merge into one fairly broad, moderately strong anomaly. If we drilled on this maximum, we would not encounter any of the orebodies. Therefore, we should fly the airborne magnetometer as close to the ground as possible in order to duplicate the results of the magnetic ground surveys. The first chance to accomplish this came with the helicopter, which is an exceedingly maneuverable aircraft. It can be landed in a cleared space not much more than fifty feet square. With floats, it can be landed anywhere, even in a swamp, on thin ice, or on soft snow. It can stand still in the air, hovering over a given point. It can ascend and descend vertically, fly sideways and even backwards, at the will of the pilot. It flies forward at any speed up to l00 miles an hour. The helicopter can be taken to any desired position at a given time. It can fly at any useful altitude from a few feet to several thousand feet above the ground. It can fly very close to the ground with safety. In bare areas, the survey flight may be performed a few feet above the ground. In forested areas, however, the flights, to clear the trees, must be made at l00 to 150 feet. To mark out a certain point, a small parachute-like marker may be draped over a tree or laid on the ground. This can be done from the helicopter without touching the ground.

Jan 1, 1947