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This paper describes the results of a laboratory study on the upgrading of Algoma siderite by the amine flotation of silica and silicate gangue. The experiments indicate that a virtually complete removal of silica is possible in a rougher flotation con-ducted in tap water at natural pH, without prior desliming of the ore. Grinding considerably finer than the apparent liberation size is essential for maximum silica rejection. A cationic collector, Aeromine 3037, gave best results when used in combination with a modifier. Of the several modifiers tested, a Dutch potato dextrin, Dextrin 4356, was found to be the most effective. Both iron recovery and the grade of the final iron product are enhanced by floating the pyrite contained in the ore prior to the amine flotation of the silica, and by scalping the magnetics from the silica concentrate. F OR over twenty years, the Algoma Ore Properties Division of The Algoma Steel

Jan 1, 1963

By D. G. Almond

Nkomati Nickel Mine in South Africa processes one of the world?s hardest ores in a 375k TPM autogenous grinding circuit. The plant employs an unconventional processing circuit, comprising a primary autogenous mill (AG or FAG) and pebble crushing circuit followed by a secondary hybrid pebble/ball mill and classification cyclone cluster. Advanced Process Control (APC) or Expert Control is now generally accepted as an advantage in most modern high capacity concentrator grinding circuits. This paper reviews the installation of model predictive control at Nkomati and examines the results and benefits of installation in an autogenous mill during plant ramp-up. The paper also demonstrates how predefining process control objectives together with good plant and supplier cooperation can achieve a robust and reliable APC implementation on a very short site program. The results conclusively demonstrate operational and economic benefits during circuit operation with the advanced process control system ON. Production performance and circuit stability were significantly better than during manual control.

Jan 1, 2012

By L. C. Lien

Tower crane layout (TCL) is a typical construction site layout (CSL) problem, which is suitable for a wide range of work assignments and site conditions. Tower crane is one of the key facilities for vertical and horizontal transportation of materials, especially for heavy prefabrication units such as steel beams, ready mixed concrete, prefabricated elements and large panel formwork such as machinery and equipment, and a wide variety of other building materials within a construction site. However, it is a difficult combinatorial optimization problem to determine the locations of tower cranes with materials quantity supply and demand for engineers. Swarm intelligence (SI) was very popular and widely used in many complex optimization problems which was collective behaviour of social systems such as honey bees (bee algorithm, BA) and birds (particle swarm optimization, PSO). This study applied a hybrid swarm algorithm namely particle bee algorithm (PBA) based on a particular intelligent behaviour of honey bee and bird swarms by integrates theirs advantages. This study compares the performance of PBA with BA and PSO for a proposed hypothetical construction engineering of TCL with materials quantity supply and demand problem. Results show that PBA performs better performance than the mentioned algorithms on a proposed hypothetical TCL problem.

Aug 1, 2013

By A. Motamedi

Indoor localization has gained importance as it has the potential to improve various processes related to the lifecycle management of facilities and to deliver personalized and location-based services. Radio Frequency Identification (RFID) based systems, on the other hand, have been widely used in different applications in construction and maintenance. This paper investigates the usage of RFID technology for indoor localization of RFID equipped movable assets during the operation phase of facilities. The location-related data on RFID tags attached to fixed assets are extracted from a Building Information Model (BIM) and can provide context-aware information inside the building which can improve Facilities Management (FM) processes. The paper proposes a new approach to use received signals from available reference tags in the building attached to fixed assets to locate movable assets. The approach uses signal pattern matching and clustering algorithms for localization. As a result, a user equipped with an RFID reader is able to estimate the location of target assets, without having access to any Real- Time Location System (RTLS) infrastructure. A case study is performed to demonstrate the feasibility of proposed methods.

Aug 1, 2013

By Yang Shuxin, Guo Qiliang, He Ping, Lu Lizhi, Yao Rui

"We combined stepwise regression and constrained regression statistical method to obtain the best boundary conditions for the calculation of in-situ stress field in Wushaoling tunnel using finite element method. Our numerical results reveal that: the main geologic factors contributing to the initial background stress are gravity and tectonics; the principal stress values would drop in fault zones; the angle between the maximal horizontal stress and the axis of Wushaoling tunnel is acute; Wushaoling tunnel tends to become stable when this tunnel has 2:1 ratio of the height to its width; the possibility of rock-burst exists under high stress.INTRODUCTIONStress state of engineering region is an important factor affecting the stability of project. Geological disasters in the project area are closely related to their stress environment. Wushaoling tunnel which is 20,050 meters long, lying along Lanzhou-Wuwei segment of Lan-Xin Railway in China, is the key project of Lan-Wu double-track railway. The region surrounding this tunnel is under a high stress environment. Accurate identification of the stress environment of the engineering area and the interaction between geomaterials and geotechnical engineering construction holds significant scientific and practical value for engineering design, construction, and operation.Many scholars explored and discussed the present-day tectonic stress through investigations of tectonic evolution history (Ding, & Lu, 1986), crustal deformation (Zoback, 1992), focal mechanisms (Yang et al., 2003, Xie, Cui, & Zhao, 2004), and so forth. However, the above methods would only provide the approximate direction of the principal stress in a broad region, and could not give the absolute stress values. In-situ stress measurement is one of the primary means to directly gauge the current crustal stress. However, in-situ stress measurement can only be applied in small number limited by measurement conditions."

Jan 1, 2015

By G. Merle, David L. McKay, Elmar Randveer

"THE ENGINEERING AND TECHNICAL SERVICES department is responsible for supplying the following services:1. Administration and co-ordination of the work required for capital projects.2. Engineering, design and drafting services for inplant changes or improvements as requested by the operating• and maintenance departments.3. Rock mechanics.4. Preparation of plans and layouts required for efficient extraction of the ore as mutually agreed with the mine operating departments.5. Mine planning and long-term schedules in co-operation with the mine operating departments.6. Grade control (long term and short term) and the preparation of ore and waste removal schedules to maintain a uniform grade of mill feed. This also includes the calculation of metal reserves and metal production forecasts.7. Surveying, underground and surface.8. Operations research at the mine site.9. Industrial engineering.10. Chemical analyses and assays.11. Instrumentation.12. Environmental control.A staff of approximately 35 supervisors, engineers and scientists, and 80 technicians, supply the foregoing services. Consulting engineering and drafting firms are used to supply specialized services and technical personnel in-house at Timmins to handle overloads on capital projects under the direction of Ecstall engineers.The operating and maintenance departments depend on the engineering department to supply engineering, design and drafting services for any new facilities or for any planned alteration to existing facilities. To do this efficiently requires a high level of communication and co-operation with these departments. This has been a major factor in developing the present organization of the department shown in Figure 63.The organization is predicated on a strong central technical and engineering resource from which personnel can be assigned responsibilities for different projects, and in different areas, as the work load demands. Job satisfaction is very high because of the variety and challenge in the tasks. Additionally, participation in projects with production and maintenance personnel broadens each technical employee's knowledge of operating and maintenance problems."

Jan 1, 1974

By L. Bos

The availability and reliability of large grinding mills and their Gearless Mill Drives (GMDs) are of paramount importance for the grinding process. Although GMDs have been in service for decades, and are known for their operational efficiency (reliability and robustness with reduced operating cost per ton), compared to conventional drives, in the last decade due to certain reasons some failures led to serious unscheduled shutdowns and significant insurance events. The majority of these notable "insured" failures have happened on GMDs installed on relatively large mills, as the financial impact of a failure is proportional to the through-put of the mill. Despite the occurrences of these events, as mining operations are driven by lower ore grades and the ability to continue reducing operating costs per ton, the trend for having larger mills is still very present and there is no reason why this trend should not continue. It is obvious that if not handled correctly, the possibility of large value GMD loss events, coupled with the continuing increase in mill size or required availability and reliability targets, could potentially lead to major conflicts as it becomes difficult for the insurance companies to judge the risk and hence may result in hesitation to insure these grinding circuits. This paper will not only describe the conflicting situation from both an insurer's perspective and from an equipment supplier's perspective, but also how these conflicting challenges can be successfully mastered. It has to be noted that not only the mining companies themselves, but also their insurance companies and the involved equipment suppliers have a common interest: to reach the highest availability and reliability in order to avoid or at least minimize unscheduled shut down times, and most importantly prevent unplanned events that result in extended production stoppages or reductions in through-put of GMD driven mills. From the very beginning onwards, the complete service concept together with emergency plans must be integrated on every level in the design of the grinding circuit. This approach must be implemented continuously and without compromises by all involved parties during all following stages, such as basic design, detail design, manufacturing, quality inspection and testing, packing, transportation, storage, installation, commissioning, operation and maintenance. The concept of formal risk analysis related to mill operations, maintenance and spare parts strategies must be an integral part of mining companies? decisions related to the selection for installation and continued use of large mills powered by GMDs. The service concept in place for operating mills shall also have a clear focus on very early detection of any abnormalities, so that the risk can be mitigated and unscheduled shutdown times avoided. However, if a major failure occurs, then procedures and tools shall already be available in order to ensure that production impact is minimized.

Jan 1, 2012

By C. Horstmann, D. Andreo, G. Barthold

"The concept of large single line grinding circuits provides a valid answer in project feasibility studies by reducing capital investment requirements compared to parallel lines for the same plant throughput rates. The benefits of this concept are reflected as well on the operational aspects, in terms of higher and greater process stability, and reduced operational costs mainly due to the associated lower maintenance expenditures. However, concerns exist in the minerals industry on whether large single line grinding could reduce the overall concentrator plant availability. The mechanical design and integrity, the mill and gearless mill drive integration, as well as assets management aspects of this type of equipment are the key to guarantee successful availability records. Together with an overview of the added value provided by large single line grinding circuits, this paper focuses on risk mitigation strategies during mill and gearless mill drive integration, as well as on the design of the equipment itself, for the key aspects which could put at risk the operations availability.INTRODUCTIONDespite a large long term demand for commodities, the mining industry has never faced complex challenges as it is doing today. Decreasing high-quality and accessible deposits, declining ore grades in existing mines, shortages of electrical energy (e.g. in Chile) and an aging workforce are the most significant among the megatrends affecting our industry. In addition to this, flat underlying commodity prices and high price volatility are currently posing strong requirements to miners when entering into the process of approving investments.Nowadays to get projects financially approved (optimizations, expansions, new plants), capital expenditure has to be reduced, as observed up to 30% compared to the last decade, and at the same time the plant design has to be such to demonstrate that operating costs will also be significantly lower than in the past.When it comes to the concentrator plant, the concept of large single line grinding circuits provides a valid answer in project feasibility studies by significantly reducing the capital investment requirements compared to parallel lines for the same plant throughput rates. The benefits of this concept are reflected as well on the operational costs, in terms of higher and greater process stability and reduced maintenance expenditures."

Jan 1, 2016

By A. Ducastel, S. Connemann, A. Stark, F. Bouillot, C. Fricke-Begemann, LSA, H. Knapp, L. Horckmans

"Refractory materials are essential for all high-temperature applications in industry. Depending on the position in the furnace and specific process requirements, refractories are produced from several raw materials, such as dolomite, magnesite, bauxite, graphite or chromite. Most of these raw materials are not rare but strict quality requirements limit the producers of refractories to only a few deposits in the world. Thus, raw material supply is a critical factor for the production of refractories and accounts for 40-50 % of the total costs of refractories.A possible way to lower dependency on raw material supply is recycling of spent refractories. Main challenge in recycling is the separation of different brick types from each other and the removal of impurities, such as steel or slag. The European FP7 project REFRASORT aims to apply sensor-based sorting for separation of spent refractories. Sensor-based sorting is known from food industry, recycling and mineral processing and has proven its reliability. Nevertheless, some adjustments are necessary compared to applications in mineral processing because of other sensor-types and a higher number of products in one sorting step. This paper presents the results of feasibility tests for sensor-based sorting of refractories with near infrared spectroscopy and laser-induced breakdown spectroscopy (LIBS). Both sensors showed the potential to identify different brick types but the most promising results were obtained using LIBS technology. INTRODUCTIONRefractories are solid, ceramic products, which can sustain temperatures of more than 1500°C, without losing their stability or shape. Bricks of refractories have to withstand corrosion in contact with liquid steel or slag. Various high temperature applications, such as the production of glass, steel, copper or cement, require high quality refractories. The quality requirements of refractory bricks are strict, because small impurities can lower the thermal strength significantly."

Jan 1, 2016

By T. T. Ni

FOR MORE THAN 200 years, the Kochiu district of Yunnan province has been, and it still is, the hub of China's tin industry. The district produces annually from 80 to 90 per cent of that country's out-put of tin, which averages about 9,300 tons a year and places China fifth among the tin producing nations of the world. The tin ore reserves of the country are estimated (1) at 1,873,370 metric tons, of which 1,500,000 tons are in the Kochiu district. The mill of the Yunnan Consolidated Tin Corporation, described in this paper, is the only one of its kind in China. MINING AND SMELTING There are only two tin mines in the Kochiu district operating with modern equipment -the Hsin-Chang and the Lao-Chang, both owned by the Yunnan Consolidated Tin Corporation, a government company. The Hsin-Chang mine has four working levels with cross-cuts 6 ft. by 6 ft. and is equipped with steel mine cars and trucks to haul the ore. The ore is hoisted to surface in a three-compartment shaft and transferred to the mill by a 4-kilometer aerial tram. The Lao-Chang mine has two circular shafts 656 feet apart, each equipped with two cages. Haulage-ways 1,600 meters and 1,000 meters long, respectively, have been driven to the southwest from these shafts and are connected by three cross-cuts.

Jan 1, 1951

By Mike Dry, Mani Manimaran, Mykolas Gladkovas, Mariam Melashvili, Chris Fleming

Development of a new hydrometallurgical flowsheet requires quantitative description and optimisation of all chemical processes in each step in the process, as well as mass and energy balances across a fully integrated circuit incorporating all the unit operations. This paper covers steps leading to early modelling of a gold processing plant based on a bromine/bromide lixiviant. Research conducted at SGS Lakefield in collaboration with Albemarle provided the data that were used in the development of this model. A previous investigation in this series described the leaching behaviour of various mineral types in Stabilized Bromine reagent. This paper is concerned with the gold recovery operations associated with a conceptual bromine leaching process. The recovery of gold by different types of resin and activated carbon was studied, along with various methods of stripping the gold from the extractant. The circuit is closed by electrolysing the spent leach liquor to oxidize some of the contained bromide back to bromine that would allow recycling the regenerated leach solution back to the leach step in the process.

Jan 1, 2015

By F. Habashi

"A short account will be presented on the extraction of rare earths from monazite sand, bastnasite ore, and phosphate rock of igneous origin. This includes mineral beneficiation, leaching methods, fractional crystallization [of historical interest], ion exchange, solvent extraction, precipitation from solution, and reduction to metals. INTRODUCTIONOriginally, the term rare earths was only used for the oxides, R2O3, which are similar to one other in their chemical and physical properties and are therefore difficult to separate. Within the rare earth group, the elements scandium, yttrium, and lanthanum differ in their atomic structure from the elements cerium to lutetium (the lanthanides, Ln). Scandium occupies a special position with respect to this classification and its other properties, and therefore does not belong to either of these groups. The rare earth elements always occur in nature in association with each other. The isolation of groups of rare earth elements or of individual elements requires costly separation and fractionation processes owing to the great similarity of the chemical and physical properties of their compounds, which explains why the history of their discovery has extended over such a long period.The word “rare”, when used to describe this group of elements, originates from the fact it was thought that these elements could only be isolated from very rare minerals. Considering their abundance in the Earth’s crust, the term rare is now inappropriate. These elements are lithophilic and are therefore concentrated in oxidic compounds such as carbonates, silicates, titano-tantalo-niobates, and phosphates.The abundance of the rare earth elements taken together is quite considerable. Cerium, the most common rare earth, is more abundant than cobalt. Yttrium is more abundant than lead, whereas Lu and Tm are as abundant as Sb, Hg, Bi, and Ag. For all practical purposes promethium does not occur in nature. It forms only in nuclear reactors."

Jan 1, 2012

By T. J. Fee

Introduction The International Nickel Company have been pioneers in mine rescue work in Ontario. Following the fire in the Hollinger mine in the spring of 1928, the Company purchased ten self-contained oxygen breathing outfits, ten all-service gas masks, an oxygen high-pressure pump, life line, inhalator, ten cap-lamps with batteries, and a complete stock of spare and accessory parts. An instructor from the U.S. Bureau of Mines, Pittsburgh, came to the Creighton mine for one week and trained twenty men in the use and limitations of all equipment. Monthly training courses were commenced in the fall, and have continued to the present time. Of the original twenty men trained, ten are still on the Creighton mine rescue teams. In the meantime, and as an aftermath of the Hollinger fire, the Work-men's Compensation Board of Ontario and the Ontario Department of Mines established a central mine rescue station at Timmins. This was completed in the spring of 1930. It was then decided, in view of the great expansion in mine development in the Sudbury district, to build and equip a similar station to serve all the mines there, namely, Creighton, Frood, Garson, Falconbridge, Sudbury Basin, and Errington. An extensive survey was made and a central location selected opposite the Frood mine. The International Nickel Company donated a site, and the station was completed in the fall of 1930. The station is a two-storey brick building, 27 ft. by 47 ft., with a large garage adjoining it. The ground floor is used for equipment and for training the crews. On the second floor are living quarters for the superintendent and his family. The garage houses a closed truck, in which all necessary equipment can be taken to any desired point for training purposes or for actual mine rescue work, if and when necessary. The garage is also used as a gas room, where the men are trained in an irrespirable atmosphere. A gas-tight observation window between it and the training room enables the superintendent to see and direct the men undergoing training, weight exercisers and other devices being used.

Jan 1, 1935

By Alan Bauer

New developments in drilling, blasting and explosives in both open-pit and underground mining operations are discussed, as well as novel surface blasting techniques such as are used in tar sand mining.

Jan 1, 1978

By Nick Hazen

Many successful actions are required to bring a profitable extractive metallurgical operation into production. Competent process development performed within the project development schedule increases the chances of obtaining project financing and decreases the risk of engineering design errors being built into the commercial plant. The general sequence of steps in process development is well known: technology review, desktop studies, scoping studies, prefeasibility, and so on, with an increasing requirement for experimental evidence as the studies advance. This paper suggests principles for guiding process development work so that the efforts stay on track toward a smooth startup and a profitable commercial operation. It emphasizes closely aligning the research with the corporate goals of the mining company management, understanding the mineralogy and variability in the deposit, and guiding by flowsheet and material balance. Examples of hydrometallurgical process development leading to the early use of solvent extraction in the mining industry are given.

Jan 1, 2014

By Masahiro Eguchi, Giuseppe Granata, Chiharu Tokoro, Hiroki Fukuda, Yuichiro Toba, Shungo Hobo

"Currently, large amounts of wastewater containing boron are discharged from industries like coal-fired power plants. Although coagulation-sedimentation is widely employed for their treatment, only a little consideration has been given to its mechanism. An additional problem is that the produced sludge has poor solid-liquid separation. This study is focusing on coagulation-sedimentation using magnesium, examining the mechanism and improving the solid-liquid separation. First, the co-precipitation with magnesium hydroxide was conducted against high-concentration boron wastewater with 500 mg/dm3as B. Second, in order to improve the solid-liquid separation by maintaining high reactivity, low-crystalline magnesium oxide was synthesized from magnesium carbonate by calcination at 400–700°C. It was tested as an adsorbent of boron and compared to co-precipitation with magnesium hydroxide. Co-precipitation showed high removal capacity. X-ray diffraction (XRD) of the sludge revealed the presence of other compounds besides magnesium hydroxide. This result suggests that other processes play a role other than simple adsorption on to magnesium hydroxide, and provides a plausible explanation for the observed high separability. As for the adsorption, the synthesized magnesium oxide immobilized as much or more amount of boron than co-precipitation. Furthermore, the results of fourier transform infrared spectroscopy (FT-IR) suggested the residual magnesium carbonate improved solid-liquid separability due to its poor solubility.INTRODUCTIONBoron is used in various industrial applications. In glass industry, the addition of a little amount of boron into glass products can enhance heat-resistance and chemical-resistance. Semi-conductor industry also employs boron as dopant for silicon. From these industries, large amounts of wastewater containing boron have been discharged. Additionally, coal-fired power plants have been recently discharging highly concentrated boron wastewater because the amount of boron contained in coal has been increasing due to a gradual decrease of the quality of coal. Since boron is partially proved to be toxic for animals, plants, and human beings (WHO, 1998),the guideline of the World Health Organization limit the boron concentration in drinking water to 2.4 mg/dm3(WHO, 2009).Because boron does not precipitate from solutions by simply changing the pH, the removal could be carried by operations such as adsorption or ion exchange. However, since ion exchange is an expensive operation with relatively low capacity, it is not suitable to treat the large amounts of wastewater produced by heavy industries like the coal-fired power plants. Therefore, coagulation-sedimentation method is still widely used as a suitable alternative way."

Jan 1, 2017

By Selwyn G. Blaylock

There is no more important problem today than industrial relationship, and probably none that is receiving more thought. But in these days of Epie and Utopia, one has to be rather careful in speaking on this subject. Consequently, for fear that my plea for taking the working man into the family might be misconstrued, by some, as a step towards communism or socialism, I would like to say at the outset that I believe that, so long as we have human individualism, human ambitions, human hopes and fears, straight socialism is as far off as the Millennium. The same applies to communism, which only differs from socialism in that the communist realizes that his ideals can only be attained by massacring millions and destroying all that we hold sacred. Each still looks to Russia for inspiration and guidance, totally disregarding the Soviet swing-back to individual contract work and differential wage scales. They seem to be oblivious of the tyranny and repression in the present Russian system, and get very restless when reminded of it. In spite of the fact that the standard of living in civilized countries has improved tremendously and is still improving, we find that, every seven or eight years, production in many lines has outstripped consumption, and we have had panics or depressions of greater or less magnitude, accompanied by extensive unemployment. It is evident to every thinking person that there must be no little inefficiency in the control of industry. For four long years, governments and industrialists have striven to find the key to solve the present problem. Many countries are getting back to a position approaching normal-Canada probably more so than most. None, however, can feel assured that they have actually cured the situation. All kinds of schemes have been developed; tariff barriers have sprung up over-night where none existed before; currencies have been inflated to gain added security in the home markets and to try to gain advantage in export trade; and each country watches the movements of the others with fear and mistrust. I am not prepared to formulate a full solution of our troubles, but I hope to be able to demonstrate the feasibility and wisdom of the type of industrial relationship I advocate, and also that it may be a large, and possibly an essential, step towards the solution of our difficulties.

Jan 1, 1935

By R. Wang

"Under high stress conditions, rock bursts, borehole breakouts, and spalling events are common phenomena that occur around underground openings. In general, together these three phenomena represent brittle failures of an intact rock mass; however, individually they reflect different failure modes under high stresses. After analyzing and comparing the stress-to-strength criteria for rock bursts, borehole breakouts, and spalling events, proposed by previous researchers, it is found that these brittle failure phenomena share common stress-to-strength prerequisite. The stress-to-strength preconditions for brittle failures can be defined by the ratio of the maximum tangential stress around an underground opening to the uniaxial compressive strength (UCS) (s?max/sci) or by the ratio of the maximum far-field principal stress to the UCS (s1/sci). Both these indicators can be used to reflect the same stress preconditions. For s?max/sci, a ratio of 0.4±0.1 represents the critical stress requirement for brittle fracture. However, for s1/sci, a ratio of 0.15±0.05 should be considered as the critical stress requirement. Numerous engineering case studies and analysis of rock mechanics based on the Hoek-Brown criterion also verify these two stress-to-strength preconditions. Here, these two indicators are presented with an error range because complex rock mass quality ratings, lithology, and geotechnical conditions have profound impacts on the stress-to-strength preconditions for brittle failures. INTRODUCTIONHigh stresses are one of the most important factors that must be considered when undertaking underground rock mass projects (Kaiser et al., 1998). Wang et al. (2009) reviewed current progress in the evaluation of high stresses and their corresponding criteria. However, after clarifying the definition of high stress, civil engineers need to understand the deformation and failure behaviors of rock mass around an opening under high stresses. Under high stress conditions, the deformation of rock masses around an opening can be categorized into two groups, i.e., severe brittle failures (or rock bursts) and compressional plastic deformation of the surrounding rock mass, as indicated in Figure 1."

Jan 1, 2015

By Jason J. Ballentine

This paper presents a case study of how an asset strategy and zero based budget was developed for an existing crushing plant that had been purchased from the contract service provider by an Australian Iron Ore miner. The goal was to directly align the strategies and budget to the business goals. This however was not a simple task due to poor historical records and a general lack of information. These challenges were overcome and the benefits of a documented maintenance strategy, a justifiable zero based budget and employee engagement were realized.

May 1, 2007

By M. F. Goudge

MAGNESIA refractories and magnesium metal are both essential war commodities. The need for magnesium, which had just made its debut as a commercial metal a few years before the outbreak of the present war, is widely known because this new and valuable light metal has already received much publicity. Less widely known but equally important in the war effort are magnesia refractories. They are indispensable to the efficient functioning of the great metallurgical plants producing steel, nickel, copper, and other metals, where, because of their resistance to extreme high temperature and chemical attack, they are used in lining the furnaces, which are operated at a white heat. The demand for refractories in the metallurgical industries rose rapidly upon the outbreak of war, and now, in consequence of the continued great expansion under way in the manufacture of steel, nickel, copper, and other metals, the need for magnesia is greater than ever. Since 1915, part of the Canadian requirements of basic refractories has been supplied from the deposits of magnesitic dolomite in Argenteuil county, Quebec. The products from these deposits are excellent for many uses, but the magnesitic dolomite has too high a content of silica and lime to be used in making a type of magnesia brick required in nickel converters, and in the roofs of reverberatory furnaces used in the copper and steel industries. There is now a large and growing demand in Canada for bricks and shapes for these uses. This demand has always been supplied from the United States. Makers of these products in the United States, in turn, formerly imported most of the necessary high-grade, dead-burned magnesia from Austria and Manchuria. Not only are these sources closed, but refractory chrome ore from the Philippines is no longer available and chrome refractories may have to be in large part replaced by magnesia.

Jan 1, 1942