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By G. L. Oldright

THE economic manufacture of sulfuric acid by the ordinary chamber process usually involves production on a large scale and a plant that is costly to construct. The nature of sulfuric acid makes it costly to transport any great distance. For these reasons, the metallurgist has not found it feasible, at times, to beneficiate ores amenable to leaching, and a. need exists for a local process that will produce acid cheaply on a small or large scale. To leach ores containing residual sulfides, an oxidizer, such as ferric sulfate, is needed in solution. Precipitation with scrap iron is one of the cheapest methods of removing some metals from solution, giving a plant of low first cost and supplying a source of cheap ferrous sulfate. The other ingredient needed for the process is SO2 roaster gas; the addition of which, as, described below, will give both ferric sulfate and sulfuric acid. Where roaster gas is a waste or obnoxious, product, the expense. for materials is still further lessened. The use of ferric sulfate and sulfuric acid as a solvent lends itself, well to the utilization of scrap iron as a precipitant, and the stages of the process fit in well together as an economic whole.

Jan 8, 1925

Far reaching changes in the executive machinery of the Federal Government are proposed in bills recently introduced in each House of Congress. The Department of the Interior will become the Department of Public Works, if the legislation proposed is enacted; the main idea is to assemble all engineering activities of the Government in one department. Such bureaus of the Interior Department as are non-engineering in character are to be placed under the jurisdiction of appropriate departments, while engineering bureaus from other departments are to be included in the Department of Public Works. The bill proposes that the Patent Office is to be removed from the Interior Department and placed under the Department of Commerce. The Bureau of Pensions is assigned to the Department of the Treasury. The Bureau of Education goes to the Labor Department. The Bureau of Indian Affairs is transferred to the Department of Labor, with the proviso that the engineering and construction work and the land and mineral surveys now performed under the direction of the Bureau of Indian Affairs are to he prosecuted under the Department of Public Works. St. Elizabeth's Hospital and the Freedman's Hospital in Washington are assigned to the Treasury Department. Columbia Institution for the Deaf and the Howard University go to the Bureau of Education, under the provisions of the bill. On the other hand, the Department of Public Works is to absorb the Supervising Architect's Office of the Treasury Department; the Construction Division, River and Harbor Improvements, Mississippi River Commission, and California Debris Commission of the War Department; the Bureau of Standards and the Coast and Geodetic Survey of the Department of Commerce; the Bureau of Public Roads and the Forest Service of the Department of Agriculture.

Jan 8, 1919

By M Ujihira, M Komazaki, K Higuchi, D F

A diesel engine with a misfiring cylinder is likely to break down in a short time when the engine is used without maintenance. The authors have developed a method of detecting the occurrence of cylinder misfiring and specifying the misfiring cylinder by using wavelet analysis and statistical analysis on the root mean square (r.m.s.) values of two kinds of acceleration waveforms. This detection method is considered superior to traditional methods, which require several accelerometers, especially in terms of simplicity. Since the development of the method, research has been conducted on semi-automatic processing of measured signals and signal transmission from the worksite to a remote office. Field tests confirmed that 1 + 105 points of dynamic data could be transmitted through the mobile multimedia network within 15 minutes, and the time for signal processing was within 15 minutes. Final determination on the condition of a diesel engine in heavy machinery could be achieved within 30 minutes. Shortened processing time is expected by improvement of the processing software.

Jan 1, 2003

By H. R. Hanley

ELECTROLYTIC zinc produced from sulfate solution and, with pure lead anodes is always contaminated with a small and varying percentage of lead. The purpose of this investigation is to determine the characteristics of several lead alloys and their influence on the products of electrolysis and power consumption. The study of alloyed anodes has been a matter of interest for some years. Tainton, Taylor and Ehrlinger prepared a highly interesting paper1 on this subject a year ago, in which the effects of silver-lead and some ternary alloys of lead-silver-tin were described. The present paper describes a study of various combinations of 10 metals. The general plan of the work provides for the fabrication of the alloyed anode, its adequate conditioning by preparatory electrolytic operation, the production of cathode zinc and its analysis, the determination of the anode polarization, and other features. A list of the anodes tested, showing composition and polarization at various current densities together with the lead assay of the cathode zinc, is shown in Table 1.

Jan 1, 1930

By Sullivan TD, Redman PG

AND INTRODUCTION The Lochiel coal deposit, a large Tertiary soft brown coal deposit in the mid north of South Australia, is currently being investigated by the Electricity Trust of South Australia (ETSA) as a potential source of fuel for a base load power station. Feasibility studies indicated that the proposed dragline method of overburden removal was viable but economically sensitive to both highwail and dump batter angles. The unusual properties of the unconsolidated overburden sediments and the groundwater regime posed a number of intimately related hydrogeological and geotechnical questions which were addressed before and during the excavation of a trial pit. All strata at Lochiel are of soil strength, and artesian aquifers occur above and below the coal. From the initial evaluation of the deposit a number of hydrogeological questions were defined. These related to the rate at which the pore pressure in the silts is reduced by dewatering, the extent of the reduction in pore pressure due to prestripping, and the feasibility of dewatering and depressurising carbonaceous silty sand sequences. The site of the trial pit was selected to answer these and other questions from the basis of a detailed geological, hydrogeological and geotechnical understanding. The trial pit dewatering system simulated a full scale mine dewatering system and included ten pumped wells, twenty drainage wells, and nearly 400 monitoring instruments. It operated from September 1986 to June 1987. The excavation was carried out between February and May 1987.

Jan 1, 1988

By Bruce A. Kennedy

This is an opportune time to examine the disposition of practical rock mechanics in the mining industry. The rock mechanics world has put on steam with publication of a number of books and the organization of a large number of symposia and teaching seminars. SME has just published Stability ill Open Pit Mining. proceedings of a conference held In November 1970 in Vancouver, R.C. R book entitled Planning Open Pit Mines covering the entire range of open pit mining with emphasis on slope stability has just been published by the South African Institute of Mining and Metallurgy. The Thirteenth Symposium on Rock Mechanics was held at the University of Illinois. Urbana-Champaign, during the last week of August. The University of British Columbia's Division of Continuing Education is holding a symposium and specialty seminars on stability in open pit mining during the first week in November. A tremendous planning effort has started to organize the Tl3ii.d Congress of the International Society of Rock Mechanics in Denver in 1974. This meeting is held every four years in the country of origin of the president of the Society. This third congress comes to the U.S.A. with Leonard Obert of the 17. S Bureau of Mines as president of the Society. The previous two were held in Lisbon. Portugal and Belgrade. Yugoslavia.

Jan 1, 1971

Research on the Differential Flotation of Iso-Floatable Lead-Zinc Sulfide Ore

Sep 13, 2010

By C. E. Sims, H. M. Banta, S. L. Hoyt

Over the past few years, metallic arc welding has been extended to steels of the hardenable type. As compared with other methods of fabrication, production has been facilitated, service performance frequently has been improved, and the overall results have been so favorable that engineers and production men have placed great emphasis on this application of welding. The metallurgist and welding engineer, however, have been confronted with new problems, since, for one reason, the harder steels are more apt to crack and special precautions must be taken if sound joints are to be procured. Some of the factors that are pertinent to this problem are metallurgical, and it is an object of this contribution to discuss steel manufacture and processing methods and to show how their control assists in reducing the hazard of cracking. By this time, the problem of cracking— specifically underbead cracking, or "hard cracks," or parent-metal cracks-—is well known, and a large amount of work has been published, both here and abroad, dealing with this subject.' The tests described are made under restraint to facilitate cracking and arc so designed that a semiquantitative, or at least a relative, value of the cracking tendency is obtained. As one would expect, it has been reported that the incidence of cracking increases with the carbon and alloy content of the steel. More specifically, the cracking tendency is said to increase with the hardenability of the steel, though it is now recognized that the situation is not so simple. The phenomenon itself, on the other hand, has been but loosely described, and it is in only broad generalizations that this cracking has been related to steel metallurgy. Thus, while it has been abundantly demonstrated that the hardenable aircraft steel, S.A.E. 4130, must tend to crack when are-welded, the problem still remains of why two lots of the same composition and the same hardenability can vary so greatly in cracking tendency, or what it is about the prior metallurgical history that so strongly affects the results. Further, while the efficacy of preheating and postheating in preventing cracking is recognized and utilized in production, the mechanism by which they function seems not to have been described. These points are thought to be significant in the production of steel for fabrication by metallic arc welding and, hence, of interest to mill and process metallurgists and welding engineers. Consequently, it is another object of this paper to discuss the mechanism of parent-metal cracking, including the influence of the condition of the steel and the control of cracking by manipulation of the time-temperature conditions during and after welding. A new method of rating the cracking tendency is also discussed, and the results of the test are related to steel composition and structure or prior history. The work to be described was the outgrowth of work in 1940-41 at Battelle Memorial Institutc on two projects, one

Jan 1, 1945

Primary sulphidic gold ores in the Archean provinces of Western Australia can be broadly sub-divided into pyritic, pyrite-telluride, arsenical and antimonial types. Pyritic ores contain only native gold, and are essentially not refractory. Arsenical ores almost always carry some invisible gold, and may vary from mildly to highly refractory. Pyrite-telluride ores contain gold-bearing tellurides, and are refractory to varying degrees. Antimonial ores usually contain aurostibite, and may be very difficult to process. A classification scheme for metallurgical processing, based on mineralogy, is proposed for the ores, and implications for processing are discussed.

Jan 1, 1995

By K. Barron

The glass insert stressmeter, or photoelastic stressmeter, is an instrument designed to determine stress changes occurring in rocks. It has several potential advantages over other such devices in that it is a biaxial device, it is simple and it is cheap to make. The object of this study was to assess the behaviour of the meter under biaxial loads and to examine some of the problems associated with measurement and interpretation of the fringe pattern. This assessment has been carried out by comparing theoretical and laboratory behaviour of the meter. It has been shown that: a) There are certain optimum measuring points in the meter at which measurements should be made for best accuracy. The position of the points depends on the ratio, n, of the biaxial stresses. b) The meter&apos;s sensitivity can be assumed to be independent of the rock modulus E provided that the rock modulus is < 2.5 x 106 psi and not, as previous workers have assumed, if E < 5 x 106 psi. c) There are several methods of separating the principal stresses; some of these are unsatisfactory. A new method is proposed and discussed. d) The meter sensitivity decreases as the ratio of the biaxial stresses approaches unity; the accuracy thus also decreases. e) The axes of symmetry of the fringe pattern give an excellent indication of applied stress direction. f) Laboratory calibrations are in good agreement with theory. The glass insert or photoelastic stressmeter is an instrument designed to determine stress changes occurring in rocks. It has several potential advantages over other such devices in that it is a biaxial device, it is simple and it is cheap to make. This stressmeter has been described in detail.l,2 Basically it is a hollow glass cylinder that has at one end a light source and filters producing circularly polarized light. The glass cylinder and source are grouted into a borehole in rock and the face of the cylinder is viewed through a quarter wave plate and an analyser. If, after installation, a stress change occurs in the rock, then a distinct colored isochro-matic fringe pattern is seen in the meter. The fringe order at any point in the meter can be determined by counting the fringes and measuring the fractional fringe orders by the Tardy compensation method. The relation between the fringe order at any point and the applied stress change can be determined either by calculation or by calibration. The object of this study was to assess the behavior of this stressmeter under biaxial loading conditions and to examine some of the problems of interpretation of the fringe pattern. THEORY Hiramatsu et a14 have determined the stress distribution in a hollow cylindrical inclusion in an elastic host material when subject to uniaxial stress. Using this solution, the biaxial case of stress p in the x direction and stress q in the y direction (Fig. 1) can be solved by superposition. This has been done in Appendix 1. It is shown that the principal stress difference (s1 -s2) at any point (r,?) in the cylinder is given by:

Jan 1, 1965

By Schneider CL

The calculation of the liberation spectrum in the product from continuous milling operations is a problem of considerable importance, and it is difficult to solve because the population balance equation must be integrated in two-dimensional space. Complete solutions require a very detailed knowledge of the complex interactions between the fracture patterns and the mineralogical ore texture when brittle particles are subject to impact fracture. Most of the liberation models that have been developed to date apply only to batch comminution processes and under these conditions the liberation problem can be studied in isolation. When the comminution is continuous and forms a unit operation in a flowsheet that includes classification and separation operations, the situation is very different, and then the liberation of the minerals must be described when single particles of known mineralogical composition are fractured. Important industrial examples are conventional milling circuits closed by hydrocyclone and regrind mills in flotation plants. This paper presents an efficient computational algorithm for the calculation of the liberation spectrum produced by continuous milling operations. The algorithm relies heavily on the detailed internal structure of the Andrews-Mika diagram. The modifications that are required to make this diagram apply to practical ore minerals, and the internal structure of this diagram can be established using single-particle fracture on mono-size, mono-grade material but suitable liberation models are essential to interpret the data in terms of the cross transfer coefficients required for the population balance procedure. Models proposed by Leroux (1992) and King (1990) are compared to experimental data.

Jan 1, 1993

By Michel Aubertin

Les digues de retenue de résidus miniers devraient être conçues de façon à supporter les charges les plus défavorables qui puissent être anticipées. Les nombreux incidents survenus au cours des dernières années à travers le monde montrent toutefois que la stabilité de ces ouvrages reste encore problématique. Les cas de rupture les plus courants sont reliés aux glissements le long des pentes, à la liquéfaction des rejets, au débordement des bassins, ainsi qu?à l&apos;érosion régressive et de surface. Après avoir rappelé la nature et l?importance des certains incidents récents, l?origine de ces problèmes est brièvement présentée. On aborde ensuite le lien entre les critères à adopter pour la conception des ouvrages et les risques associés à leur rupture. De nouvelles avenues pour aider à contrôler certains problèmes sont enfin discutées, en mettant l?emphase sur la codisposition des roches stériles dans le parc à résidus miniers.

Nov 1, 2002

By William D. Manly, John Towers, Paul A. Beck

RECENT work on grain growth in high purity aluminum and in a solid solution type alloy of aluminum and magnesium&apos; showed that the isothermal increase of the average grain diameter D with time follows the equation [D = K(to + A)-Eq I] Here [to] is that portion of the total annealing time [t], which is available for grain growth, i.e. the annealing time less the time necessary for complete recrystallization. The parameters A and n depend only on the temperature. A has the dimension of time, and is usually of the same order of magnitude as the time for recrystallization: R. In some instances R may be substituted for A in Eq I. This is the case for example at long periods of annealing or at high temperatures, where both A and R become small in comparison with t. In such instances Eq I is simplified to [D-K-tnEq2] For high purity aluminum the exponent n increases in the ratio of about 1 to 5 in the temperature range of 350° to 600°C. 70-30 brass has been long known to exhibit grain growth of the continuous type, such as occurs in pure metals. For this reason, it was of interest to determine whether grain growth in brass also follows Eq I and 2 as it does in aluminum. Isothermal grain growth data for 70-30 brass were published in recent years by R. S. French2 and by H. L. Walker3 Fig I shows a log D vs. log t plot of French&apos;s data, together with the 500, 600 and 100°C data by Walker for 42.8 pct reduction by rolling. In such a log D vs. log t plot Eq 2 corresponds to a straight line with a slope of n. As seen in Fig I, the data of French and the 600°C data of Walker can be represented by straight lines. However, the 500 and 700°C data of Walker give curved lines and the average slope of his 500°C line is very different from the slope of the line representing French&apos;s data for the same temperature. Furthermore the curvature of the 700°C line suggests a tendency for grain growth to stop after 8 hr. If confirmed, this would constitute a definite deviation from Eq 2, not explainable on the basis of the specimen thickness effect found in high purity aluminum.1 Walker&apos;s specimens were 0.125 in., i.e. 3.18 mm thick, while the deviation occurs at a grain size of approximately 0.4 mm. A further point of divergence arose recently, when J. E. Burke suggested4 on the basis of Walker&apos;s data, that, instead of Eq 2, grain growth in 70-30 brass follows the equation [D-D. =K• t,Eq3] Here D, is the grain size as recrystallized at the temperature in question. Although it was possible to show5 that, for pure aluminum, for which isothermal grain growth has been carefully investigated, Eq 3 is incompatible with the experimental facts, the situation remained somewhat obscure with respect to 70-30 brass. In view of the discrepancies between the

Jan 1, 1948

By Bryan Morris

Quebrada Blanca (QB) is a copper project located in the semi-arid Andean highlands of northern Chile. The operation is situated 170 km ( 105 miles) southeast of the port of Iquique and 30 km (18 miles) west of the border with Bolivia, at an altitude of about 4300 m (14,000 ft) (Fig. 1). The QB ore body is a secondarily enriched porphyry copper deposit containing reserves of 85 Mt (93 million st) grading 1.3% copper. Underlying the enriched zone is a significant primary ore zone containing several hundred million tons grading about 0.5% copper. In the late 1970s and early 1980s Falconbridge and its affiliates spent $20- $30 million exploring the deposit and conducting feasibility studies. Falconbridge, however, decided not to develop the property. It was returned to its owners, Empresa National de Mineria (ENAMI), a Chilean state mining corporation. In 1988, ENAMI announced its intention to privatize the property through public bidding. Cominco Resources, then 61% owned by Cominco Ltd., examined the property and the extensive data base developed by Falconbridge. In conjunction with its parent company, Cominco Resources submitted a proposal to ENAMI to construct an open- pit mine, with heap leaching and solvent extraction/electrowinning (SX-EW) processing facilities. The plan would use patented heap leaching technology developed by Sociedad MineraPudahuel (SMP), a privately owned Chilean mining company. At that time, a $150-million project that would produce about 45 kt/a (50,000 stpy) of cathode copper was envisaged.

Jan 1, 1993

By E. M. MacKevett

The only source of uranium ore in Alaska that has been mined commercially is the Ross-Adams deposit, a gently inclined, fusiform orebody in alkali granite in which uranothorite and uranoan thoria-nit? ale the chief ore minerals. In mode of occurrence, apparent genetic association with the granite, and to a lesser extent in mineralogy, this type of deposit is uncommon. The mine is in the southern part of Prince of Wales Island (Fig. 1) at an altitude of about 950 ft on the southeast flank of Bokan Mountain. A steep unpaved road 1 3/4 miles long leads to the dock on the West Arm of Kendrick Bay, which can be reached by boat or seaplane from Ketchikan, some 35 miles to the northeast. The southern section of Prince of Wales Island is covered by dense forests interspersed with swampy tracts of muskeg. Most of the higher peaks support only sparse vegetation, and in areas underlain by alkali granite bare rocky slopes prevail to as low as 800 ft. Numerous fiord-like embayments penetrate this part of the island, and their shorelines provide near-continuous rock exposures. Rainfall is heavy, about 150 in. annually. Throughout the year the climate is relatively mild. History and Production: In May 1955 two members of a Ketchikan prospecting group, Don Ross and his wife, found the deposit while working with an airborne geiger counter. Later they confirmed their discovery by ground investigations. During the summer Climax Molybdenum acquired controlling interest in the property and started exploratory diamond drilling, resuming the drilling on a larger scale in the summer and fall of 1956. Climax began mining in July 1957, shipping the ore by barge and train to the Dawn Mining Co. mill at Ford, Wash. The open pit workings, about 370 ft long, between 25 and 75 ft wide. and 25 ft deep (shown in Fig. 2) were shut down in October 1957. As of September 1958 the pit was still inactive, although a small tonnage of known reserves remains in the southern part. The operators believe the 15,000 tons of uranium ore already produced will average 0.80 pct. GEOLOGY The Ross-Adams mine is within a small stock or boss of alkali granite, about 1000 ft from the southeast margin of the granite (Fig. 3). The area around the boss is underlain chiefly by plutonic rocks of intermediate composition and by metamorphosed sedimentary and volcanic rocks. The oldest rocks in the area probably are the metamorphosed volcanic rocks that are well exposed adjacent to the South Arm of Moira Sound. They are considered by Buddington and Chapin1 to be of Devonian age. These light gray to dark gray rocks mainly represent a layered volcanic sequence. They are commonly porphyritic with plagioclase pheno-crysts in an altered, fine-grained groundmass. The

Jan 1, 1960

By Burrows D. R.

Metal-rich sediments precipitating from hot saline brine pools were first discovered in 1965 in the Red Sea.1-2 The subsequent discovery of high temperature black smokers and associated massive sulphides in 1977 at latitude 21oN on the East Pacific Rise3 came more as a confirmation than a revelation. Formation of massive sulphides through precipitation from circulating sea-water had been predicted by Oftedahl in 19584, and the mechanisms well evaluated in basaltic-hosted Cyprus-type 5 and in Kuroko-type deposits.6,7 Sea-floor exploration from 1977 through the 1980?s in sediment-starved mid-oceanic ridge (MOR) settings had little impact on land-based exploration. This is primarily because: a) MOR spreading centres were recognized as poor analogies to even Cyprus-type basalt-hosted deposits; b) their preservation potential was limited due to rapid oxidation and c) the metallic deposits studied were small and therefore not directly comparable to the far larger ore bodies on land. More recently underwater mineral deposit research has focused in a variety of back-arc environments associated with felsic submarine volcanism, environments more similar to those predicted for the formation of Kuroko-type deposits (e.g. Okinawa Trough, 8 Lau Basin, 9 Manus Basin, 10 Aeolian arc, 11). Most studies, while scientifically interesting, were hampered, in general, by a lack of good descriptive data, a reliance on isolated grab samples, and a lack of sub-surface observations. This research has therefore had only limited direct impact on exploration strategies with the possible exception of research conducted in areas where faulting provided enhanced vertical exposures. 12

Jan 1, 2011

By Ralph Sweetser

PROGRESS in blast-furnace practice during 1922 has been in the direction pointed out in my article in the March, 1922, issue of MINING AND METAL-LURGY; this advance has been very satisfactory in spite of the difficulties caused by the great coal strike and the railroad strike. The progress, especially in increased tonnage, has been brought about, not by increasing the size of the furnaces, not by improved mechanical devices, but through the application of better blast-furnace practice; the advance has been metallurgical rather than mechanical. The increase in production per stack, has been more pronounced than in any period since the time that James Gayley began to break blast-furnace records in Pittsburgh. These big tonnages have been made in furnaces designed to make 550 to 600 tons of pig iron per day; but several such furnaces have had monthly averages of between 700 and 800 tons per day with a corresponding reduction of cost, and a reduction in the number of man-hours of labor per ton of pig iron. During this period there has been a wider acceptance of the fact that satisfactory blast-furnace results are more dependent on coke quality than on any other factor. There has always been much rivalry among blast-furnace men in making new tonnage records, and many schemes have been used for getting out big pro-duction, but the blast-furnace man cannot make the high records all by himself; it is necessary for him to have the cooperation of the entire management, and also the help of the organization that makes his blast-furnace coke. Herman Brassert has said that "there is no blast-furnace practice possible that can wholly overcome the effects of bad coke." In the past; the blast-furnace superintendent has often been under suspicion if he complained about the quality of the coke in times of unsatisfactory blast-furnace results, but it is now conceded that if the quality of the coke is not right, complaints are not necessarily made as an alibi.

Jan 5, 1923

By Donald W. Gentry

Introduction The mining industry is perhaps best characterized by the numerous and abnormally high risks associated with the business of mining and by its most basic assets - ore deposits, people and technology. At the most fundamental level, it is the quality and effective utilization of these basic assets that determine a mining company&apos;s ability to compete efficiently in the international market place. The gold industry has received much attention in recent years and especially in recent months, for good reason. This commodity serves as an excellent platform for the subsequent discussion of these three basic assets and their role in mining&apos;s future. Facets of the gold industry The fate of this noble metal in recent times illustrates some of the various risks associated with the mining industry and the importance of high-quality assets, whether they be ore deposits, people or technologies. The following comments pertaining to the gold industry help place proper focus on subsequent discussions. All monetary amounts given are in US dollars. Throughout 1997, falling gold prices broke record after record: first hitting three-year lows, then a 12-year low in July and finally an 18-year low at year&apos;s end. From Jan. 1 through Dec. 31, 1997, the price of gold fell by more than $2.57/g ($80/oz), or some 22%. The decline in gold-mining profitability and stock prices was even more dramatic. At the beginning of 1997, the 20 largest gold producers in North America had a market capitalization of approximately $44.5 billion. At year&apos;s end, this market cap had fallen to $26.2 billion, a reduction of 41%. The total market cap of all the world&apos;s gold companies fell from $71 billion to $46 billion, a 35% drop (Serwer, 1998). Analyses suggest that, at a spot gold price of $9.65/g ($300/oz), only one, or possibly two, North American gold-producing companies can make money when break-even or "total costs of production" are considered. While strong hedge positions mitigate this situation in the short term, clearly, this is an industry in desperate straits. For example, write-downs for North American producers in 1997 were approximately $2.5 billion. Speculative short positions in 1997 were near historical record highs and generally exceeded long positions by factors of 9:1 or 10:1. Much of this is driven by some US commercial banks, hedge fund managers and commodity speculators who can significantly move gold prices sharply over short periods of time by selling gold they do not own in the expectation they can buy it back at a lower price before they have to deliver. These signifcant short positions are likely to continue as long as central banks are willing to sell or loan gold to financial institutions that in turn make the gold available to speculators who hope to capitalize on price fluctuations. The Far East accounts for approximately 26% of the annual demand for gold. Including India, the region accounts for 43% of total demand. More than 85% of the physical demand for gold is for investment jewelry in Asia and the Middle East. This demand is extraordinarily price sensitive. The fairly recent turmoil in Asian markets and economies, combined with currency devaluations throughout the region, have made gold more expensive (30% to 50% in local currencies) for those peoples most likely to treat gold as a safe investment haven. Higher interest rates also have reduced the amount of money they have to spend on consumer goods such as jewelry. All of these recent Asian events are deflationary in nature. Deflation, if coincident with rising unemployment, could result in significant dishoarding of gold. There is one key fact to remember when analyzing

Jan 1, 1999

By Robert B. Parsons

"A joint federal/provincial/industry subcommittee of the Intergovernmental Working Group on the Mineral Industry (IOWG) has published an informative and readable report on taxation matters concerning Canada&apos;s mining industry. The report, which was presented to the federal and provincial mines ministers in September 1986, identifies and discusses key tax issues relating to this industry. The report is mandatory reading for anybody with an interest in mineral exploration or production in Canada.IntroductionIn 1986, Canada&apos;s federal and provincial mines ministers were presented with an important report concerning the taxation of this country&apos;s mining industry. This document is important for a number of reasons, two of the reasons being: first, the report contains an objective analysis of the key mineral taxation issues of the day; and, second, the report is the product of a cooperative exercise involving representatives of various facets of the industry and government. The report should be regarded as compulsory reading for anybody who has an interest in fiscal matters affecting mineral exploration and production.The ""Report on Fiscal Proposals"" was prepared by a subcommittee of the Intergovernmental Working Group on the Mineral Industry (IOWO). IOWO is a group of senior federal, provincial, and territorial government officials concerned with the analysis of mineral policy issues in Canada."

Jan 1, 1986

By C. Wert, G. Mah

A relaxation peak thought to be due to the presence of C-C pairs in cobalt has been observed. It exists both above 420"C, where cobalt has the fcc structure, and below 420"C, where cobalt has the hcp structure at equilibrium. The effect is thought, however, to be caused by motion of C-C pairs in the fcc phase in both instances; enough retained fcc phase was deduced to be present at temperatures below 420°C to make the phenomenon possible. Measurements of the aniso-tropy of the effect in single crystals of various orientations of fcc phase showed the effect to have a maximum value in longitudinal strain for a [loo] crystal and a minimum value for a [Ill] crystal. This observation seems to rule out the possibility of (110) nn pairs being responsible for the effect. From measurements of the strength of the relaxation in the alloys, we reach the conclusion that both the binding energy of the pairs and the specific relaxation per pair are smaller than corresponding quantities for interstitial pairs in bcc metals. DETERMINATION of the details of atom placement of small atoms such as carbon, nitrogen, oxygen, and hydrogen in metals has been a difficult problem. In certain alloys such as martensite extensive departure from random placement of the interstitials can be deduced from X-ray diffraction off the atoms of the host metal, but such diffraction techniques are of small help for small departures from randomness. A technique which does offer promise in the latter instance is the anelasticity of these interstitial alloys. Most previous investigations using this property have utilized alloys in which the solvent is one of the bcc metals, alloys such as These studies have been interpreted to show that an interaction exists between interstitials which causes them to form clusters in more than random numbers; the binding energy of interstitials in such clusters has been deduced to be about 0.1 ev per atom (for small clusters of size two to four atoms). Similar investigations have been carried out on close-packed solvent metals, Ni-C by and Diamond and Ag-O by Papazian.8- In both of these svstems. no relaxation of the singly dissolved interstitial is expected, so an-elastic behavior of the interstitials must be caused by their association in some cluster or complex of non-cubic symmetry. Since relaxations in these alloys were observed to have a strength which varied about as the square of the interstitial concentration, the effect was deduced to be caused predominately by motion of i-i pairs in the crystal. A striking difference is observed in relaxation strength of interstitial alloys between the bcc and fcc systems. The specific effect per interstitial atom is much larger for the alloys in the bcc crystals than for those in fcc crystals. Comparing clusters of size two in the Nb-O system4 and the Ni-C system,7 one finds the magnitude of the anelastic effect per interstitial atom in the former to be some 100 times greater than that in the latter. Such a difference in relaxation strength might be caused by a difference in concentration of the pairs (this means a higher binding energy in the bcc crystals). It might also be caused by a large difference in shape factor of the elastic strain field about the pairs between the two cases (a much more noncubic shape factor would be required for the bcc crystals). This investigation was undertaken to examine the possibility of C-C pair formation in alloys of cobalt and carbon using anelastic effects. Since cobalt has both fcc and hep phases, it seemed to offer the chance that measurements over a range of frequency might permit comparison of properties of pairs in the two crystal types. Although this goal was not reached, several significant facts were deduced from the observations. 1) An anelastic phenomenon believed to be associated with the presence of C-C pairs in cobalt exists. It has many features in common with that observed in nickel. 2) The effect is thought to be caused by pair motion in the fcc phase. 3) Calculations of the relaxation strength A, which includes as a parameter the product of the pair concentration, C, and the square of the shape factor &apos;, show that this parameter is much smaller in the CO-C alloy system than in the interstitial alloys in the bcc systems. 4) From this finding, we reach the conclusion that both the binding energy of C-C pairs in cobalt and the specific relaxation strength per pair are small compared to corresponding values for such pairs in the bcc systems. 5) The crystalline anisotropy of the effect permits the identification of reasonable geometrical models of close C-C pairs. I) EXPERIMENTAL PROCEDURE A) Method of Measurement. The anelastic measurements-—all of which were constant frequency measurements of internal friction—were designed to study the expected phenomenon in both the hcp and fcc structures in cobalt. Knowledge of similar measurements in Ni-C alloys led us to believe that the damping peak should occur below the transformation temperature for frequencies near 1 cps and above for frequencies near 100 kcps. This surmise was correct. The low-frequency measurements were made on wire specimens using a vacuum torsion pendulum; the damping peak was found at about 2&apos;70°C at a frequency of 1 cps. Because of large superimposed damping of magnetic origin at this temperature, a longitudinal magnetic field of about 1500 oe was applied to the

Jan 1, 1969