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By Paul M. Tyler

Fully a decade ago, demand for ground mica began to exceed supplies of scrap mica from manufacturing operations and of waste block from feldspar and sheet mica mining in the United States, with the result that in recent years the market has absorbed larger and larger quantities of mica recovered as a by-product from clay washing,1 as a joint product with kyanite12 and by grinding schists. So far, only schists that contain a large percentage of mica have been utilized for making ground mica, but already there has been a good deal of wishful thinking with regard to recovering mica as an aid to the prospective working of low-grade gold ores and ores of certain base metals. With wet-ground mica selling at $60 to $100 a ton and even dry-ground mica worth over $20 a ton, many ores that could not be considered as otherwise workable under present conditions will show commercial possibilities if they can be made to yield even a relatively small percentage of salable mica. An interesting paper might be written on the coming role of industrial minerals as joint products of metal mines. It is largely a matter of markets. Many years ago I watched the mess left behind the gold dredges in the mountains of Colorado and thought of the Denver sand and gravel operators who prided themselves upon their canniness in providing devices for catching gold merely as an incident to their regular business of selling what we miners classed as "tailings." Nowadays almost every milling or mining operation near settled communities finds use for at least part of its waste for road material or concrete aggregate and several eastern iron mines have gone into the crushed-stone business. Promoters now mention fertilizer "filler" as potentially salable at all the way from $1 to $10 a ton, or whatever is needed to cover costs of mining and treating the "ore" and leave the metal values as "clear profit." In emulating the pork packers in their efforts to utilize "everything but the squeal," mining engineers may go too far; on the other hand, they should not let

Jan 1, 1942

By George H. Holmes

This paper is one of a series being prepared by the Minerals Division of the Bureau of Mines on mining and milling methods and practices at various mines in the United States. It describes such methods at the Caselton mine of the Combined Metals Reduction Co. The Caselton mine and mill are in secs. 28 and 29, T. 1 N., R. 67 E., M. D. B. & M., Lincoln County, Nev., about 10 miles by paved highway south- west of Pioche, Nev. (fig. 1). the history of the district and company This circular summarizos operations, describes physical features, labor and living conditions, the geology, ore deposits, and the ore. Prospecting and exploration methods are outlined, and shaft sinking, drifting and crosscutting, and raising are covered under development methods. In the soction on mining mothods, stoping and slushing are discussed, following which are descriptions of underground transportation, hoisting, ventilation, drainage and sampling, and surveying. The surface and crushing plants are described, and milling practices are presented in dotail with explanation of the filter plant and assay office. Safoty practices and the company organization are described in the concluding sections of the circular.

Nov 1, 1950

By Paul M. C. B. M. Cools, Martin Th. van Staveren

In 2010, the 5-years joint industry programme Geo-Impuls started in the Netherlands. The ambitious goal of this programme is to reduce geotechnical failures in our civil engineering projects by half in 2015. In the Geo-Impuls programme over 40 client organizations, engineering firms, contractors, research institutes, and universities are involved. In a risk-driven way, and based on top risks and dilemmas, the participants defined three central development themes. These themes are (1) contracts, for dealing with legal issues, (2) geo-engineering, for dealing with technical issues, and (3) communication, for paying attention to differences in risk perception by the human factor. In total 12 Working Groups contribute to these themes by producing one or more specific tools. These provide practical solutions for how to deal with contractual, geotechnical, and communication issues. The tools include working processes, guidelines, best practices, as well as some instruments. The development of these tools, as well as the available results, will be presented in this paper. From the start, Geo-Impuls embraced geotechnical risk management (GeoRM) as the risk-driven way of working for geotechnical engineering and construction. Over the past years, GeoRM and its supporting tools were already successfully applied in several projects. Therefore, the paper also describes also the GeoRM implementation process, including the quality assurance and control. Finally, the effectiveness of GeoRM will be discussed, by summarizing an analysis of all published geotechnical failures and accidents in construction projects in the Netherlands, which decreased substantially over the past 4 years.

Jan 1, 2017

By J. M. Cummings

DURING the past year, the writer has investigated the treatment of a variety of British Columbia tungsten-bearing ores. Much of the test-work described in this paper was carried out in collaboration with Mr. A. G. Lyle in association with the British Columbia War Metals Research Board at the University of British Columbia. The remainder was completed in the laboratories of the Department of Mines at Victoria. Two mills in the Province are at present treating tungsten ores. Descriptions of these are included through the co-operation of Messrs. S. Gray (1) and A. A. Almstrom (2). MINERALOGY, OCCURRENCE, AND SPECIFICATIONS In the present paper, attention is directed solely to scheclite, inasmuch as known occurrences of other tungstcn minerals in British Columbia are of mineralogical interest only. The properties of scheclite are listed below: Percent W03 .. 80.6 Tenacity ...... Very brittle Çrystallization Tetragonal Lustre ........ Vitreous to resinous Cleavage ...... Good in 4 directions Magnetism ... Non-magnetic Specifie gravity 6.05 Diaphaneity .. Transparent to translucent Hardness. . . . . . 4.5-5.0 Scheelite may contain as much as ten per cent of molybdenum in solid solution, but most of the specimens from British Columbia examined by the writer were relatively pure.

Jan 1, 1943

By Paula Rodrigues Caumo

A tecnologia da fabricação de aços, nas últimas décadas, apresentou grandes avanços, os quais resultaram em melhorias da qualidade, principalmente no que se refere à remoção de inclusões. As inclusões podem ser responsáveis por prejudicar as propriedades mecânicas por meio da geração de trincas ou fraturas entre outros defeitos. O distribuidor do lingotamento contínuo também pode atuar na remoção destas partículas. A eficácia desta função do distribuidor demanda o conhecimento das características do escoamento do aço líquido de modo que se possa propor modificações na configuração do distribuidor. Esse conhecimento pode ser obtido mediante a utilização de modelos físicos para simular os fenômenos envolvidos. O objetivo deste trabalho é, a partir de um distribuidor com jato aberto, construído em acrílico e em escala 1:1, verificar o percentual de inclusões passantes pelo veio com ou sem a presença de bolhas. O trabalho foi executado com e sem tubo longo, sendo o tubo longo empregado para prevenir o arraste de ar para o interior do modelo. Os resultados foram obtidos por meio do ensaio de remoção de inclusões com o auxílio do ensaio de distribuição de tempos de residência. As variáveis utilizadas neste estudo são: presença bolhas e velocidade de lingotamento.

Aug 16, 2017

By P. Bakke

Following extensive R&D efforts, Hydro Magnesium has launched a new alloy series with remarkable combinations of properties. The AE alloy family is based on additions of aluminium and rare earth elements to control mechanical properties, including elevated temperature creep strength. By combining these alloying elements with manganese additions, high purity alloys with outstanding corrosion performance are defined. A basic philosophy behind the developments has been to simultaneously approach all the critical issues related to developing a commercial material. Apart from the obvious requirements for material properties, the critical issues relate to die casting performance, as well as alloy production, recycling and environmental compatibility. Some of the important elements related to alloy production and recycling are addressed in the present paper.

Jan 1, 2006

By B Ellis

Brunswick Mine is one of the largest underground zinc/lead mines in Canada, producing 3.4 million tones of ore annually. As mining activities advance to deeper levels, ground pressure also becomes greater. To cope with the highly stressed ground, the mine has taken some strategic measures to ensure the targeted production level. Such measures include the implementation of a pastefill system and transferring the mining method from primary/secondary stoping to pillarless pyramid stoping. With the pillarless mining method, stope sizes become smaller and the number of active stopes is also less than before. In addition, mining sequence and cycle time have to be strictly followed according to production schedule. The blasting project described in this paper tackles one of the steps in the mining cycle aimed at shortening the blasting cycle time in a stope. Furthermore, this project was conducted and managed with the Six Sigma initiative in Noranda which was implemented in the fall of 1999. Like a typical process review, the blasting operation was examined by breaking it down into many steps that can be quantified and measured. Each activity was then correlated with different factors associated with blast design as well as blast operations underground. It was found that the utilisation of voids plays a key role in the blasting cycle time. With improved void utilisation ratio, blasting cycle time has been reduced from an average of 12 shifts to ten shifts per stope. This improvement translates into approximately 180 000 tonnes of ore being blasted without any increase in manpower. This paper presents the technical aspects of the study, as well as some operational issues and improvements made during the project.

Jan 1, 2001

By R. Mattos, E. Calcina, G. Quispe, S. S. Kanchibotla

During blasting, rock breaks and moves but standard grade control practices do not adjust ore waste boundaries to cater for blast movement. Rock movement resulting from blasts can result in mischaracterization of grade boundaries resulting in ore loss and dilution. Ore loss takes place when ore is mischaracterized as waste and sent to waste dumps, and dilution occurs when waste is mischaracterized as ore and sent for processing. Las Bambas operations of MMG Peru, realized the economic impact of blast movement on ore loss and dilution and adjust ore boundaries using limited blast movement measurements. This is a step in the right direction but has limitations for everyday application. This paper discusses the advantages of disadvantages of current blast monitoring techniques and introduces an operational tool to estimate polygon movements for different blast designs and confinement conditions. Blast movement estimates from this new tool have been compared against the estimates from the current tools for several production blasts and the results were quite promising.

Mar 2, 2022

By Daniel F. Meyer, William C. Paschen

INTRODUCTION The problems involved with moving millions of tons of rock are being addressed by nationally recognized tunnel contractors who have converged in Chicago over the past 5 years. This wealth of expertise has been needed to meet the risk and challenge of constructing the world's largest network of underground tunnels which in turn has required a dramatic advance in the art and science of tunneling. These pioneers, through innovation, adaptation, and hard work, have eliminated the one major concern of The Metropolitan Sanitary District of Greater Chicago - how to move 8 million tons of rock. The Metropolitan Sanitary District of Greater Chicago (MSDGC) serves 122 municipalities covering 866 square miles in Cook County, Illinois. Of these cities, towns, and villages, 53 have combined sewer systems. On an average of once every four days, these systems overflow about 4 million gallons of combined sewage and rainwater into the area's rivers and canals. The overflows occur at approximately 640 outfall locations of which 10% are owned by the MSDGC, with the remainder of the points belonging to various other municipal bodies. All those who own these "point" sources of pollution are in violation of Illinois State and Federal regulations. To enable its member municipalities to come into compliance with State and Federal law, the MSDGC is implementing its Tunnel And Reservoir Plan (TARP). TARP is a regional solution to the problem of combined sewer overflow in the metropolitan Chicago area. TARP will greatly reduce the pollution of area waterways by intercepting the combined sewage and rainwater carried in the existing sys-

Jan 1, 1981

By Giulia M. B., Ferruccio Cribari, Alessandro Bertero, Eliano Romani, Roberto Sorge, Francesca Casini

"The use of Artificial Ground Freezing (AGF) to form earth support and seepage control barrier systems has had applications worldwide. These cover a variety of construction problems, including the formation of frozen earth walls to support deep excavations, structural underpinning for foundation improvement, and temporary control of ground water in construction processes. An application of AGF during construction of Line C of Rome underground is described in detail.The new line “C” of San Giovanni metro station was constructed adjacent to the existing line “A” of San Giovanni station; the new metro line “C” is deeper than line “A” and runs below the existing station. The underpass project envisages an Artificial Ground Freezing in order to create a structural and waterproof temporary cut-off suitable to the two new tunnels excavation, while keeping trains running in the safest possible condition. The excavation of tunnels under the water table, with a hydraulic head of over 10 m in not homogeneous soils having different mechanical properties and permeability and below existing sensitive structures, involves special ground freezing sequences and methods, as well as peculiar drilling systems and operations, such as TDDT (Trevi Directional Drilling Technology).Artifical Ground Freezing IntroductionNatural freezing occurs seasonally in many areas of the globe and can affect negatively the engineering performance of geotechnical structures; on the other hand, man-made freezing is a controllable process that can be used by civil engineers to stabilise temporarily the ground in order to support and/or exclude groundwater from an excavation until the final retaining and lining structures are constructed. Freezing and thawing of the pore fluid within soils involve complex thermal, hydraulic and mechanical processes that have significant mutual interactions. For example, phase changes of the pore fluid caused by temperature variations can modify the pore water pressure in the soil, which, in turn, can induce mechanical deformation. At the same time, any changes in the hydraulic and mechanical conditions affect the thermal processes by advection and changes of ice and water contents.An application of AGF which will be presented in the paper, refers to the construction works of Line C of Rome underground. In this case AGF was carried out to provide temporary support during excavation of the two Line C running tunnels directly underneath the existing S. Giovanni station of Line A, in the safest possible condition. In order to keep the trains of Line A operational during excavation, a temporary structure was installed and a real-time monitoring system was conceived in order to control the temperatures of the soil during freezing and the response of the structures of the existing station."

Jan 1, 2016

Unlike the bituminous part of the coal industry, the production of anthracite has been fairly well publicized; in fact until about 1845 whenever the coal industry of Pennsylvania was mentioned in papers, magazines or books, anthracite only was meant. Beginning with shipments by river in 1820 fairly complete records of shipments were published each year, and as this variety of coal was the only one used for domestic purposes east of the mountains and north of the Potomac, there was considerable interest in the producing fields on the part of the public. Transportation of anthracite was the cause of the building of the early canals in the state, and later, of some of the earliest railroads. In most publications it has been assumed that commencement of shipments in 1820 was the beginning of the industry; this is far from being so, and it is with the earlier developments this chapter will deal, leaving the later and better known records to existing publications. (See Table No. 53.) The first reference to coal in Pennsylvania by Gabriel Thomas in 1698 has already been mentioned,1 it could only have been anthracite in that section; although of course, he never saw any coal there. Little coal was used excepting by smiths for many years after that. In 1728 the Coventry Forge paid the expenses of a man "to town for Sea Coall and Steell for ye hammer;”2 in 1729 New Castle coal was sold in Philadelphia;3 in 1740 an advertisement mentioned, "very good Pitt and Sea Coal at 18 pence a bushel; at which price 'tis allowed to be cheaper Fewel for Hearth Fireing than Wood at the present Rates,"4 a view not shared by most of the people there for about eighty years; in 1752 Newcastle coal was again mentioned.5 There are no references to coal in the writings of any of the Moravian missionaries, although some who settled near Mauch Chunk in 1746 said that the Indians there made their pipe heads of a soft black stone, which was much more apt to have been slate than anthracite." Several stream

Jan 1, 1942

By Isabela Leao Amaral da Silva, Felipe Perisse Duarte Lopes, Alice Barreto Bevitori, Sergio Neves Monteiro, Ruben Sanchez Rodriguez

"The fibers extracted from the stem of the ramie plant are among the strongest natural lignocellulosic fibers with a potential to be used as reinforcement of polymer matrix composites. Characterization of the ramie fiber has recently been conducted for its physical and mechanical properties. However, the effect of increasing temperature on the ramie fiber behavior has not yet been fully investigated. Therefore, the objective of this work was to perform a thermal analysis on ramie fibers with different diameters within the naturally found range of practical interest. The analysis was conducted by thermo-gravimetric, TGA and DTG, as well as differential scanning calorimetric, DSC, techniques. It was found that the ramie fibers present thermal stability up to 200°C and then suffer a sharp deterioration between 300 and 500°C, resulting in characteristic peaks.IntroductionSince the middle of last century, polymer composites have substituted many conventional monolithic materials in applications ranging from aerospace to sport [l]. The main advantages of these composites are the low density and flexible properties specially using fiber as reinforcement to suit the mechanical performance requirements [2]. These are usually high strength and stiffness requirements that could be reached with synthetic fibers such as glass, carbon and aramid fibers. In recent years, however, the use of synthetic fibers is being questioned in terms of problems caused to the environment. In fact, as non degradable material, synthetic fibers are associated with long term pollution when discarded. Moreover, the expended energy for fabrication and processing can be related to relatively large amounts of C02 emissions and represents a contribution to global warming [3]. Glass fiber, in addition, is toxic and cannot be incinerated as a waste in thermal power plants [ 4]. Possible substitutes for glass fiber are the natural fibers. Many natural fibers are today being considered as viable alternatives to replace glass fiber as reinforcement of polymer composites. In particular, some natural lignocellulosic fiber extracted from plants present a real potential for this replacement [2-8]. Their comparative advantages are lower density and reduced cost as well as renewability, biodegradability, recyclability and neutrality with respect to C02 emission [3]."

Jan 1, 2011

By Roy H. Paddon

This paper describes the 6, 000 tpd, three stage haulage system at the Ozark Lead Company's mine in southeastern Missouri. It details the methods and problems pertinent to the loading, hauling, sorting, crushing, storing and hoisting of waste rock and ores obtained from underground development headings and production areas. The Ozark Lead Company is a wholly owned subsidiary of the Kennecott Copper Corporation. Its mine is located nine miles south of Bunker in Reynolds County at the south end of the "New Lead Belt" mining district. Development started in May, 1964, by drilling a seven foot diameter (six foot cased), 1, 250 foot development-ventilation shaft. Drifting began in August, 1965, to obtain a bulk ore sample, to test ore continuity, and to drive two mine levels while the pre-grouted production shaft was being sunk. Over 7, 900 feet of 12 by 24 foot drifting was done from this small shaft. In March, 1966, a 20 foot diameter, three compartment, concrete lined production shaft was collared. It intersected existing development headings at a depth of 1, 195 feet in April, 1967, and was completed along with a concentrator and other facilities in June, 1968. Mine production began that month, with 5, 000 tpd reached in 1970.\

Jan 1, 1971

By W. H. Brandt

THERE has been much progress in the last two decades in understanding the hardenability of steel. Roughly, the progress has been along two lines, which may be designated as empirical and fundamental. This empirical work has progressed to the point where steels may be manufactured to the desired characteristics quite closely and heat-treatment and application problems can be approached with considerable confidence. Particularly noteworthy among the empirical work is that of Grossmann,12 who has given formulas for calculating hardenability as a function of composition, and the establishment of the isothermal transformation curve by Davenport and Bain.13 The latter does not fall entirely in the class of an empirical study, for while it provides a means of presenting a tremendous amount of empirical data in the form of a single curve, it also outlines clearly the problems that face the fundamental investigator. The isothermal transformation curve shows clearly that the phenomena occurring in the neighborhood of the knee of the curve are those that limit the hardenability of steel. Above the knee of the curve, the product of decomposition of austenite is lamellar pearlite and fundamental progress has consisted chiefly of a detailed study of structure and formation of pearlite, largely at the hands of Mehl and his collaborators.1-5 They have shown that formation of pearlite proceeds by a process of nucleation and growth and they measured both the nucleation and growth rate. However, there is still a wide gap between our empirical knowledge and fundamental knowledge, owing largely to the fact that there is no satisfactory theory of nucleation rate or of growth rate. This paper is being written in an attempt to fill in a small part of the gap. A method was presented recently14 for calculating the velocity of edgewise growth of pearlite using an expression for the carbon concentration that satisfies the diffusion equation. The edgewise velocity of pearlite growth in a plain carbon eutectoid steel was calculated, using linear extrapolations of the ferrite and cementite solubilities. While the results are in fairly good agreement with the experimental facts, the calculated velocity of edgewise growth is smaller at 600°C. than G, the radial growth velocity of pearlite nodules, whereas one would expect it to be larger. In this paper the calculation will be repeated using a new extrapolation for the ferrite solubility, which gives better agreement between G and V, the calculated velocity of edgewise growth. A calculation will also be made of the effect of carbon content on velocity of edgewise growth, and the problems of calculating the effects of other alloying elements on growth rates will be discussed. It will be assumed that the mechanism of pearlite growth, established by Mehl and

Jan 1, 1945

By O.W. Ellis

Recently there has been a considerable revival of interest in the effects of the various elements commonly added to brass for the purpose of increasing its strength. For many years the work of Guillet2 alone gave reliable information in this regard. Even today his determinations of the coefficients of equivalence of the various elements relative to zinc in brass are those universally employed in industry. This is so because these coefficients have stood the test of time—their substantial correctness has been proved in almost universal practice. It is not our intention to discuss here these coefficients or their use. Rather do we wish to emphasize the need for further systernatic studies of the mechanical properties of the ternary systems of copper, zinc, and other individual elements. Since Guillet published the results of his first investigations Millington, 16 Smalley33 and Thiband 45 have added somewhat to our information. In general they have confirmed the findings of Guillet, which may be stated in the following rather general terms: 1. The addition of aluminum to the 70:30 and 60:40 brasses progressively increases their hardness and strength and reduces their ductility and resistance to shock. 2. The addition of small amounts of iron to a 60:40 brass improves its strength without affecting its ductility. 3. The addition of small amounts of manganese to a 60:40 brass causes a progressive increase in its strength and reduction in its ductility. A considerable amount of information has been amassed in regard to the effect of nickel on brass (9, 22, 41) which it is unnecessary to refer to here, in view of the scope of this paper. The situation in regard to these alloys in 1926 was very clearly stated by an anonymous writer,47 in The Metallurgist of February of that year, whose remarks were so to the point that they are well worth quoting: It will he seen that there are still large fields remaining to be studied in each of these systems (those of the aluminum, iron, nickel and manganese brasses) before our knowledge is adequate. When we come to the more complicated systems the position is even less satisfactory, and on account of the very incomplete nature of the work which has been

Jan 1, 1929

By O. W. Ellis

Recently there has been a considerable revival of interest in the effects of the various elements commonly added to brass for the purpose of increasing its strength. For many years the work of Guillet2 alone gave reliable information in this regard. Even today his determinations of the coefficients of equivalence of the various elements relative to zinc in brass are those universally employed in industry. This is so because these coefficients have stood the test of time—their substantial correctness has been proved in almost universal practice. It is not our intention to discuss here these coefficients or their use. Rather do we wish to emphasize the need for further systernatic studies of the mechanical properties of the ternary systems of copper, zinc, and other individual elements. Since Guillet published the results of his first investigations Millington, 16 Smalley33 and Thiband 45 have added somewhat to our information. In general they have confirmed the findings of Guillet, which may be stated in the following rather general terms: 1. The addition of aluminum to the 70:30 and 60:40 brasses progressively increases their hardness and strength and reduces their ductility and resistance to shock. 2. The addition of small amounts of iron to a 60:40 brass improves its strength without affecting its ductility. 3. The addition of small amounts of manganese to a 60:40 brass causes a progressive increase in its strength and reduction in its ductility. A considerable amount of information has been amassed in regard to the effect of nickel on brass (9, 22, 41) which it is unnecessary to refer to here, in view of the scope of this paper. The situation in regard to these alloys in 1926 was very clearly stated by an anonymous writer,47 in The Metallurgist of February of that year, whose remarks were so to the point that they are well worth quoting: It will he seen that there are still large fields remaining to be studied in each of these systems (those of the aluminum, iron, nickel and manganese brasses) before our knowledge is adequate. When we come to the more complicated systems the position is even less satisfactory, and on account of the very incomplete nature of the work which has been

Jan 1, 1929

By G Harbort

Traditional engineering design for flotation circuits use the “Rule of Thumb” approach. Typically this uses a nominated maximum head grade for design. A scale-up factor is applied to laboratory flotation tests for residence time. This scale-up factor is usually based on a designers experience at other flotation sites and may or may not be relevant to the circuit being designed, or the flotation equipment being used. A small number of locked cycle tests are assumed to represent the ore body and the results of these are often used for financial analysis, independent of changes in mine plan throughput and mineralogy.The engineering “Rule of Thumb” approach is only strictly accurate where there is very little variability in throughput, head grade and mineralogy. It may provide accurate design for mature established operations where a brownfield expansion is being considered but is unlikely to provide accurate design for a new, greenfield site.The use of geometallurgical modeling with floatability component simulation provides a design methodology with significantly less associated risk. The use of geological data for optimisation of operating plants has become a significant part of the modern process mindset. The underlying principle is to use spatial metallurgical information to drive production planning, mine planning, blast design, blending strategies and plant set-up. At a design stage the process designer can use geometallurgical information to evaluate bottle necks and potential design flaws and propose the best investment strategy for the project benefit.This paper details the geometallurgical characterisation of the Andash deposit and methodology used to review the project’s detail design and projected production.

Aug 8, 2011

By W. B. Coleman

Considerable discussion on the effect of iron and steel scrap in blastfurnace burdens was presented in the January, 1927, issue of Mining and Metallurgy. Therein the question is asked as to what causes the difference in physical properties of pig irons where the chemical analyses are practically the same. This point no doubt has been noticed by a number of furnace operators, but several years ago very little thought was given to it. The foundries purchased pig iron, had it analyzed and found it to be within their specification. The castings made from this iron at times would be satisfactory and at other times hardness and shrinkage would occur. Since the iron was chemically correct the foundries generally were at a loss as to what to do. They changed their method of melting in the cupola and in some cases this corrected the trouble. In some instances the foundry would continue eliminating a brand of iron until the castings produced were satisfactory. Through this process of elimination they would finally arrive at the conclusion that a certain brand of iron was causing the trouble. During the course of this elimination minor changes might have been made in the melting and in the end satisfactory castings were secured without discovering any definite reason for the trouble. Frequently the foundries blamed the manufacturer of the pig iron although the seat of the trouble was in their own method of melting. I have in mind one foundry in particular that was using three brands of pig iron for producing their castings and their losses were rather high. Three entirely new brands of iron were substituted in the charge and still the losses continued. Even after using six brands of pig iron the management felt that the pig iron was the cause. The difficulties encountered in the melting of iron in the cupola, over the past several years, reflect in a great many cases on the operation of the cupola. At different times certain brands of iron were unsuitable for producing a certain class of castings, but at the same time one could see no reason why the iron should be considered abnormal. Irons from furnaces where production and low cost are the main factors that are being used in foundries produce in most cases harder cast-

Jan 1, 1927

By R. J. Labine, D. I. Brisbin, R. Roussain, P. R. Coad

"Abstract - The Owl Creek Mine is located near the west end of the Neo-archean Abitibi greenstone belt, 17 km northeast of Timmins, Ontario, and 4 km north of the Destor Porcupine fault. Gold occurs in epigenetic quartz veins and their pyritic wallrocks in two zones within a package of east striking, steeply north dipping, volcanic and sedimentary rocks. At the West Zone, 1 729 603 t of ore with a grade of 4.83 g/t Au (268 587 troy oz.) were produced from an open pit centered on a wedgeshaped unit of Tisdale Group basalt that occurs between two overturned, south facing units of Porcupine Group graywacke and argillite. Basalt/graywacke contacts are locally marked by graphiticcarbonaceous argillite, strike-parallel faults and massive quartz veins.Deformed quartz+/-ankerite veins occur along the graphitic sedimentary/volcanic contacts and in gently to moderately dipping fractures in basalts, and, to a lesser extent, in graywackes. Veins also occur sub-parallel to steeply dipping 070° foliation. Altered host basalts are composed of iron carbonate, sericite, quartz, carbon, chlorite and disseminated pyrite. Gold occurs as inclusions in pyrite, and less commonly as free gold in fractures and along graphite-quartz grain boundaries in quartz veins. Fractures preferentially developed in more competent basalts during pre- to syn-ore deformation are interpreted to have provided the permeability required for emplacement of mineralized quartz veins. Carbonaceous basalt/graywacke contacts further enhanced gold deposition by acting as chemical traps. The interaction of hydrothermal fluids with these carbonaceous sedimentary rocks led to the characteristic local darkening of host basalts due to carbon impregnation and chlorite development."

Jan 1, 1998

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Jan 1, 1925