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By Martin Langenderfer, Catherine Johnson, Alexander Douglas

Mine haul roads degrade rapidly due to extreme loads on sub-optimal construction materials. Unmanned aerial vehicles (UAV) are suited to quantify large-area road-network conditions, such as surface roughness, defects, and grade to optimize remediation of poor conditions and reduce overall costs. Mine haul roads present unique challenges, such as material type and edge characteristics, to automatic road detection that often fail, requiring manual road input. This research proposes a new method for analysis using the road center determined by principal curve analysis of a haul truck’s Global Navigation Satellite System (GNSS) traces; analysis grids were created from this center line. A dense point cloud from UAV photogrammetry was generated, and multiple linear regression analysis was conducted on each individual grid. The root mean square error in each grid indicates the surface roughness, and the change of slope between grids indicates the road grade inconsistencies. This method was applied to 26 road sections, and the results were validated by images taken from the truck operator’s vantage point. Critical defects were identified including excessive pothole formation, corrugation, depressions retaining water, and narrowing of travel lane. The results demonstrate this is a valid method of road identification and quantification of road defects at a mine site.

Dec 19, 2023

By A. E. Aho

"The material presented in this paper will be subject to modification as new data become available, but it is presented in the hope that it will inspire more intensive mineral exploration and geologic studies of what appears to be one of Canada's richest mineral provinces. A metallogenic province 400 by 150 miles in extent, lying mostly northeast of Tintina trench, encompasses most of the base metal deposits of Yukon, as well as deposits of other metals. Its main features are northwesterly trending arcuate fold belts, with several orogenic axes, which include most of the metamorphosed rocks, granitic intrusives and mineralization; and which are modified by regional uplifts, northwest-striking fault trenches, and lesser transverse folding and faulting.The main base metal occurrences and their regional controls are summarized briefly. Most of the replacement-type deposits are localized in late Proterozoic to early Paleozoic rocks, particularly Lower Cambrian -probably because these are the most physically and chemically favourable hosts encountered in an appropriate temperature and pressure environment; perhaps because of early age of deposition. Most of the deposits also occur near heat sources or intrusives with associated structural uplift, which has, moreover, served to expose the older rocks. They also tend to occur near known or suspected regional fault trenches, such as Tintina, Macmillan and Hess, although this relationship may be fortuitous. In detail, they may be localized in fold axes, flat-lying beds or other appropriate structural traps. Vein-type deposits are fracture-controlled and localized by dilational localfties, the competence of wall rocks and ""damming"" effects.In the Anvil district, large stratiform iron-zinc-lead replacement deposits lie parallel to gently plunging flex-ures in phyllite in a zone parallel to the Tintina trench, along the southwest flank of the arch-like Anvil batholith. About 80 million tons of massive sulphide ore probably existed before erosion of the Faro orebody, the Vangorda deposit could have been of similar magnitude before erosion and much more tonnage probably remains to be discovered in the district. The Anvil deposits may differ from others found to date in Yukon, but resemble the Sullivan orebody of southeastern British Columbia in their large size, localization in essentially non-limy peptic to arena-ceous host rocks of Proterozoic or early Paleozoic age and proximity to the Rocky Mountain -Tintina trench sys-tem. These features suggest an origin from primordial subcrustal sources.More major ore deposits, not only of lead, zinc and copper but probably of other metals as well, will no doubt be found in similar environments in Yukon or Alaska. Thus, the base metal province of Yukon offers challenging opportunities for prospecting, development, field studies and basic research."

Jan 1, 1969

By Friedel. Michael J.

The U.S. Bureau of Mines investigated acoustic emission (AE) and the Kaiser effect in six types of rock: St. Cloud gray granodiorite, Barre granite, Dresser basalt, Salem limestone, Berea sandstone, and a volcanic tuff. AE signatures were used for interpreting the rock deformation stage and for indicating mechanisms of failure in uniaxial compression. The research demonstrated the advantages of using the volumetric stress-strain curve, as opposed to the more conventional uniaxial curve, for correlating AE response signatures with deformation stages and fracture processes in the rock. Standardized experimental procedures were used for the AE monitoring. The Kaiser effect was shown to be capable of determining prestress levels to within a few percentage points in uniaxial compression tests. Also, prestress memory was shown to be retained in the rock for periods of up to at least. 5 months, the maximum period of testing. The Kaiser effect AE technology holds promise for providing a comparatively inexpensive and less complex method for examihing stress history in rock. However, since the conftning stress has a pronounced influence on the Kaiser effect, it must be considered in developing technology for determining peak fteld stresses based on the Kaiser effect.

Jan 1, 1990

By C. D. Chapman

Current regulations regarding the landfill disposal of asbestos containing wastes are inadequate to ensure there are no ground water or airborne emissions. Accordingly, there is growing recognition that asbestos wastes can only be safely disposed of by using techniques that destroy the hazardous fibres. An innovative high-temperature plasma arc technology (The MAGRAM Process) is being developed for the recovery of magnesium metal from asbestos together with supplementary magnesia containing feedstock. The furnace will operate in. open bath mode with aluminium and/or ferrosilicon being employed as reductant. An important advantage of the process is that magnesium vapour within the furnace will be generated close to atmospheric pressure rather than at reduced pressure under which existing processes operate. Thermodynamic modelling work has been undertaken to define the range of slag composition and furnace temperature under which magnesium production at atmospheric pressure is feasible. The effect of slag chemistry, reductant addition, and temperature on product quality and yield have also been investigated and key aspects have been tested on bench scale. A 300 kW pilot plasma furnace unit has been employed for the treatment of calcined asbestos wastes. Aspects of design and operation of the unit are detailed. Acknowledgement: This work is substantially financially supported by the European Communities under the Industrial and Materials Technologies (Brite EuRam H) Research and Development programme.

Jan 1, 1995

By Jung-Hum Lee, Young-Joon Lee, Eui-Joon Hong, Seon-Hong Kim, Chan-Dong Kim, Keon-Woong Jeong, Ki-Lim Kim

"Subsea tunnel needs to be built over 50km long to connect between nations and continents. However there are only 19 tunnels longer than 5km in Korea, and there is no history of constructing and operating a tunnel longer than 50km. As the concept of a subsea tunnel, which withstands high water pressure and has an extremely long length is completely different from that of a land tunnel, all kinds of the latest technologies for tunnel construction are required such as survey and analysis of geology, design and construction under high water pressure, ventilation and prevention of disasters within an ultra long tunnel. Therefore, this paper describes the determination of tunnel cross-section under a high speed railway, structural stability, ventilation and fire safety under construction and operation, etc. through the virtual project for the length of 108km subsea tunnel under high water pressure of maximum 20bars from Honam to Jeju island in Korea. 1. INTRODUCTION The Honam-Jeju virtual project is subsea tunnel project to link from Honam(land) to Jeju(island) extending the currently operating Honam high speed railway line, and the same express train(t=18, design speed 350km/h, total train length 200m) operating at Honam line is applied in this project. As Honam-Jeju site is approximately 80km in straight distance with 160m maximum depth, subsea tunnel project should determine the various issues such as air quality/ventilation, aerodynamics, temperature, drainage, fire & life safety, structural stability. Figure 1. is the plan of subsea tunnel, with be constructed using Shield TBM. This double tube-Single track is composed of cross passages (every 350m in general section and 40m in emergency station), service tunnel, pressure relief ducts (every 250m), cross-over tunnels, shafts and emergency stations. 2. ALIGNMENT AND SITE CONDITON This project is planned as an ultra long tunnel of total length more than 105km via existing islands between Honam and Jeju island because straight alignment requires an artificial island which has high cost and construction risk, by deep water depth, though this is the shortest distance (see Fig 2). Water depth and topography in project site is divided into two blocks by Chuja Island. In first block to Chuja Island, depth of the water is 40m on average and maximum 60m, which indicates gradual change of water depth relatively. Also, outcrop bedrock is widely distributed near island."

Jan 1, 2016

By Norman A. Pace

This paper is one of a series being published by the Federal Bureau of Mines on methods and practices used in mining and preparing crushed stone for market. Performance, in terms of units of work or tons produced per machine and per operator man-hour, is given whenever that information can be obtained. Direct operating costs are useful for comparing different methods and are included, if available. In addition to describing equipment and methods used} the Bureau considered it desirable to discuss the engineering reasons for the choices that have been made. This paper is particularly concerned with operation of the Camak quarry and plant of the Weston-Brooker Co. The quarry and plant are near Cedar Rock, north of State Highway No. 80 and east of Middle Creek in Warren County, Ga., and about 40 miles west of Augusta. Rail access is by a spur line of the Georgia Railroad from Camak, 5 miles southwest. The main office of the company is at Cayce, S. C.

Jan 1, 1959

By T. Imgrund, A. Bischoff, S. Spürk

"Specific conditions of underground coal mines at great depth, such as high temperatures, high rates of methane inflow and natural ventilation pressure provide considerable challenges for the reliable design of appropriate mine ventilation systems. For decades coal mining in Germany has coped with these extreme circumstances. Based on these experiences appropriate software tools for simulating mine ventilation networks have been developed and continuously enhanced. This paper examines differences in the simulation results and underlying calculation methods of two software solutions. The analysis is based on the comparison of FlowNetTM and VentSim DesignTM (Version 5.1) regarding the accurate prediction of fluid mechanical quantities and their validation with real measurements. A special focus lies on exceptional ventilation scenarios typical for deep coal mines, like gas inflows, fire events and buoyancy effects. The purpose of the comparison is the future utilization of the experiences gained during mining at up to 1,500 m depth for state of the art ventilation design. INTRODUCTION Ventilation is an essential component of mine operations—as providing fresh air to workplaces, diluting and removing explosive, toxic or asphyxiating pollutants and assuring sufficient climate conditions. On the other hand, the costs of ventilation contribute to a large extend to the overall operating costs of a mine, as the share in the energy consumption of a mine may be in the range of 25–50% (Belle, 2008). Accordingly, proper design of ventilation systems has been a task since early times. Consequently software for modelling of ventilation networks has been developed in order to improve efficiency and accuracy of calculations (Maleki, 2018). Compressible flow has not been considered by initial ventilation modelling software tools. In Germany, the consideration of changes in airflow density—depending on pressure and temperature—in the algorithms of ventilation simulation software has been started in 1974 by Duepre & Hofbauer. This development had been continued by the Pruefstelle fuer Grubenbewetterung (Test Centre for Mine Ventilation) and resulted in the release of a computer ventilation software named “Wetter”. The mine inspectorate of the German state of North Rhine-Westphalia, which supervises the major coal mining district in Germany, declared ventilation simulation based on compressible flow being “state of the art” in 1985 (Pollak, 1985). This pronouncement made allowance for assessing the consequences of underground fires and downtimes of main fans based on advanced software solutions."

Jan 1, 2019

By J Q. Cooper

The New Zealand rail authority, Kiwi Rail and Auckland Regional Transport Authority (ARTA), are jointly planning a new mainline rail link between Auckland’s downtown Britomart Station and the existing Western Line at Mt Eden. In 2009, APB&B, a consortia of Aecom, Beca, Parsons Brinkerhoff and Hassell Architects where commissioned to develop the conceptual design, Assessment of Environmental Effects (AEE) and business case for the new 3 km rail line towards preparing a Notice of Requirement to protect the route through Auckland’s central business district.This paper describes the engineering challenges in the development of the conceptual design for the three proposed underground stations, the running tunnels and connections to the existing network. Feasible alignment and station location options were developed and evaluated using multi-criteria analysis based on key client functional requirements, constraint mapping and environmental impacts. The resulting preferred scheme was then developed to a conceptual design suffi cient for assessment of environmental effects, risks, and the development of a robust construction methodology to allow high level capital cost estimates.The paper describes some of the major challenges overcome to develop the concept, including steep gradients, narrow street envelopes with existing buildings and structures, the need for large platform spaces with low ECBF rock cover and complex connections at Britomart and the main line near Mt Eden.The development of the conceptual design of the underground stations in particular demonstrates the need for a holistic value engineering approach to satisfying the architectural and functional requirements, in a highly constrained dense urban environment and at lowest practical cost. The construction methodology was a key input to the conceptual design development throughout.The conceptual design will be used as the fundamental basis for the development of the AEE and business case for the project in the future.

Mar 8, 2011

By R. H. Roberts

The Environment Weipa is located at 12° south latitude on the west coast of Cape York Peninsula, North Queensland, Australia. The climate is tropical with most of the 1 600 mm. average annual rainfall falling between November and March. During the short winter months (May/ August) the weather is clear and pleasant, with temperatures seldom exceeding 27°C.Throughout the remainder of the year, conditions are frequently oppressive due to consistent high ambient temperatures accompanied by high humidity. The terrain is of low relief, and generally not more than 6 to 10m. above mean sea level adjacent to the coast. The coastline features numerous short estuaries which discharge run-off from the heavy rains collected by creeks and rivers. The whole area is covered by an open forest, the predominant species of which is Eucalyptus tetradonta. These eucalypts have only limited commercial value and are heavily infested with termites. Despite the fact that Weipa is close to the location of the first reported sighting of the Australian coastline by a European (William Janz - 1606), it remains very isolated. There is no developed road or rail connection to centres of population, so that transport of practically all products, personnel and materials to and from Weipa is by sea and air. Cairns (population 49 000) is 580 km. by air and 670 nautical miles by sea; Brisbane, the

Jan 1, 1977

By S. F., French

IN reviewing the design of the ore haulage system for the Morenci project, the reader should bear in mind that the railroad and its equpiment cannot be considered as an independent railroad provided only for the purpose of transporting ore from one point to another, but as an integral part of the operation which begins at the electric shovels loading ore at the mine, and ends where the ore, after having been crushed in the primary crushing plant, is deposited in the bins at the secondary crushing plant. Obviously then, the problem consisted of designing a system that would function to the best possible advantage in complete co-ordination with the other units.

Jan 1, 1942

By Stephen Darmawan, Mahdi M. Disfani, Arul Arulrajah, Alireza Mohammadinia

Deep mixing using cementitious compounds is an in-situ method of ground improvement for improving the strength, compressibility of loose sand. Artificial light cementation can increase the stiffness of loose sands significantly and reduce the settlement of loose deposits. The increase in contact area between the particles with a thin layer of cementitious agent depends on the confinement and void ratio of the soil mass. Hence, the stiffening effect of cementation not only depends on the type and amount of cementing agent and inter-particular force chain of loose deposit but also depends on the stress level at the time of cementation. In addition, the cementation effect in loose deposits can be deteriorated at relatively low strain levels. Decementation softening can cause detrimental and irreversible impacts on the soil deposit. This study investigates the effect of initial confinement and subsequently the initial void ratio at the time of cementation on small strain behaviour and decementation softening of cemented loose sand under ko loading. The effect of inter-particular contact of sand particles based on the specific surface area and also soil density was also investigated by means of shear wave propagation. This study present insightful information on effect of primary consolidation stress levels, density of soil and cementation level on softening and collapse of loose deposits improved using deep soil mixing technique. Better understanding of soil-cement interaction by optimization of binder content for deep mixing activation can lead to increasing the level of confidence in using this technique in ground improvement applications.

Jan 1, 1900

By Jörg Thomasberger

Delivering liquid steel to a steel processing unit at right temperature is an important criterion for high production steel shops, but it is surprising how little attention has been paid in the past to manage this vital phase in the steelmaking process-the steel in transit. The ladle running costs, both directly and indirectly, contribute significantly to the cost of steelmaking and should be an area of concern to any high production steel plant. Here we are talking not only of refractory costs or preheating fuel costs, but also cost of extra heating in ladle furnace, additional process delays incurred in delivering steel at right temperature to downstream unit in case proper care is not exercised at upstream unit, and occasional costs of ladle breakout due to inability to judge the residual life of the ladle. This paper emphasizes the need of a comprehensive ladle management system, an aspect which has not been properly addressed in the operations of a steel plant, in improving the productivity of a steel melt shop. Starting with review of present status and the attempts at implementation of ladle tracking in steel melt shop automation system, it looks at components of an exhaustive Ladle Management System (LMS), and finally gives an idea of benefits that will accrue from implementation of such a system in a steel melt shop.

Aug 17, 2017

By John J. Sammarco

Abstract- Emergency shutdown systems (ESDs) for mining machinery provide critical functions to safeguard miners. Traditionally, ESDs were realized with simple hardwired circuits; today, there is a growing trend to use programmable electronic technology such as programmable logic controllers (PLCs). This paper describes an analytical study to quantify the safety integrity of a PLC-based ESD and a hardwired ESD. The safety integrity level of each design approach was determined by quantifying the average probability of failure on demand (PFDavg) as described by the recommendations for programmable electronic mining systems published by NIOSH and the IEC 61508 international standard. The safety analyses addressed system architecture, hardware failure probability, proof test interval, diagnostic coverage, and human error probability. The results indicated that a same level of safety, safety integrity level 3 (SIL 3), could be attained when evaluating random hardware failures. Neither approach could attain SIL 3 if manual activation was used. Human error was the limiting factor where, using human reliability analysis, PFDavg < 1 x 10-1; thus, the ESD does not meet SIL 1. It is apparent that automatic verses human¬activation of the ESD is a very important safety consideration. Manually actuated ESDs can only achieve SIL 1 regardless of the technology; therefore, additional independent safety layers of protection are needed to exceed SIL 1. Secondly, it is apparent that the technology choice is very important. The PLC-based ESD was much simpler to design and to validate safety1.

Jan 1, 2007

By Ruth F. Brinkley

Principle activities of the Bureau of Mines Explosives Research Laboratory from July 1, 1960 to June 30, 1961 are reviewed briefly in Part 1. Part 1 also includes data obtained in connection with several minor investigations which are not sufficient to warrant separate publications. Part 2 gives brief abstracts of publications that appeared during fiscal year 1961; in general, the research reported in these publications antedates this period.

Jan 1, 1963

By T. S. Golosinski

Use of contractors to excavate, load and haul mined material is widespread in Australia. It is also becoming a common practice in many other countries. The paper reviews current practices in Australian contract mining. Various types of contracts are reviewed, including partnering arrangements and alliancing between the contractor and the mine owner. Applicability of various types of contracts to specific mining situations is discussed, as is their impact on overall mine performance

Jan 1, 1998

By P. Valicek

Anglo American Platinum Limited is constantly striving to improve safety and productivity. There are many different initiatives taking place within the organization in order to ensure continued safe operation and profitable ounces for the future. One of the opportunities and potential growth areas that has been identified and is being explored is that of mechanization. In order to do this, the approach that has been adopted by Anglo American Platinum is to fully understand and analyse the current mechanized mining methods. Once each configuration is fully understood, the method can then be optimized and new mining technologies and systems can be developed to overcome the current shortfalls. This paper will discuss a methodology that was developed by Anglo American Platinum (in conjunction with Cyest Corporation) and adopted to optimize the mechanized mining layout and fleet configuration, and will also present the final findings of the study. Due to the impracticability of piloting every possible option in the workplace, extensive modelling and simulation exercises were conducted to determine realistic parameters for productivity and value. The study resulted in a full understanding of mechanized mining systems and their associated layout. From the results of the study a mining / logistic layout was developed which highlighted the following opportunities: 1. Create safe operations through the reduction of personnel in the ?high-risk zone? of stopes 2. Separate machines and personnel by use of remotely operated machines 3. Create focused mining on primary development from the production stoping, thus having dedicated teams on development and stoping. 4. Develop primary development ahead of the stoping activity. This enables: a) Understanding of the geology and subsequent implementation of the correct b) technology (?fit-for-purpose?) required to mine that area based upon this geological knowledge c) Ability to install tipping points ahead of stoping, creating ?immediate stoping reserves?, thus increasing flexibility and reducing production risk d) Improved productivity by having adequate faces available and reduction in re-development to establish faces. 5. Quicker return on Investment due to recovering revenue from ?on-reef development? 6. The layout allows flexibility between stope sections enabling better ?resource sharing? 7. Optimize the long-term ratio of machine makeup of the fleet in relation to the production outputs 8. Creates an agile mining layout allowing rapid response to market pressures. The findings and work presented in this paper is currently being implemented at different test sites within Anglo American Platinum and will demonstrate that improved safety and productivity can be achieved through the adoption of mechanization.

Jan 1, 2012

By Guy Reed, Russell Frith

"Current coal pillar design is the epitome of suspension design. A defined weight of potentially unstable overburden material is estimated, and the dimensions of the pillars left behind are based on holding up that material to a prescribed or user-defined Factor of Safety. In principle, this is seemingly no different to early roadway roof support design. However, for the most part, roadway roof stabilisation has progressed to reinforcement, whereby the roof strata is assisted in supporting itself. This is now the mainstay of efficient and effective underground coal production. Suspension and reinforcement are fundamentally different in their roadway roof stabilisation approach and, importantly, lead to substantially different requirements in terms of roof support hardware characteristics and their application. In suspension design, the primary focus is the total load-bearing capacity of the installed support to ensure that it is securely anchored outside of the potentially unstable roof mass. In contrast, reinforcement recognises that roof de-stabilisation is a gradational process with an ever-increasing roof displacement magnitude leading to ever-reducing stability. In a reinforcing situation, key roof support characteristics relate such design issues as system stiffness, the location and pattern of support elements within the roadway, and mobilising a defined thickness of the immediate roof to create (or build) some form of stabilising strata beam. The objective is to ensure that horizontal stress acts across the roof of the roadway and is maintained at a level that prevents mass roof collapse. This paper presents a prototype coal pillar and overburden system representation where reinforcement, rather than suspension, of the overburden is the stabilising mechanism via the action of in situ horizontal stresses within the overburden, the suspension problem potentially being an exception rather than the rule, as is also the case in roadway roof stability. Established principles relating to roadway roof reinforcement can potentially be applied to coal pillar design under this representation. The merit of this assertion is evaluated according to documented failed pillar cases in a range of mining applications and industries found in a series of published databases. Based on the various findings, a series of coal pillar system design considerations and suggestions for bord and pillar type mine workings are provided. This potentially allows a more flexible and informed approach to coal pillar sizing within workable mining layouts, as compared to common industry practices of a single design Factor of Safety (FoS) under defined overburden dead-loading to the exclusion of other potentially relevant overburden stabilising influences."

Jan 1, 2017

By K. B. Lindsey

Geologically, the Williston Basin is a large structural depression of sedimentary rock in Montana, North Dakota, and South Dakota and Manitoba and Saskatchewan, Canada. The approximate It-mite of the basin are shown on figure 1; it is roughly circular with a diameter of about 400 miles and contains approximately 120,000 square miles. Although the petroleum potentialities in this area had long been recognized, it had not been vigorously prospected by the petroleum industry because of its geographic location, rigorous winters, depths to possibly productive zones, difficult geological problems, and the fact that more seemingly favorable areas were available for prospecting. With the discovery of oil near Edmonton, Alberta, in the prolific Devonian reefs, an incentive was given to explore for oil in the southeast extension of the same sedimentary trough, the Williston Basin. The Virden field discovery in southwestern Manitoba in January 1951 was a direct result of this southeastward movement. Discovery of this shallow field was followed soon after by discovery of&apos; deep production on the Nesson anticline in North Dakota at Clarence Iverson No. 1 well. North Dakota then became the twenty-seventh petroleum-producing State.

Jan 1, 1954

By C. O. Hawk

A PART of the Bureau of Mines effort to improve the conversion of coal to liquid fuels, batch autoclave tests were made on the hydrogenation of bituminous coal by a dry method, which featured charging the autoclave with dry ingredients only-coal, catalyst, and hydrogen. This innovation, which omitted the liquid vehicle used in earlier work, limited the products to those made from the coal charged. The effects of the common process variables (catalyst, hydrogen pressure, temperature, and residence time) were studied. Tin catalysts showed the highest activity in the widest variety of forms and were the easiest to disperse; dry mixing in the autoclave during the heating-up period usually sufficed. Ammonium molybdate, on the other hand, was inactive when dry mixed, but it compared favorably with the best catalysts known when applied by impregnating the coal with a solution of a molybdenum compound. As a group, metal naphthenates were the most effective; in fact, molybdenum naphthenate was the most active catalyst the Bureau tests disclosed. One-hundredth of a percent of molybdenum in this form (calculated as the metal in weight-percent of maf coal) induced 90-percent conversion of coal. However, because of their high cost, naphthenates have as yet only technical significance in coal hydrogenation. Long residence time and high reaction temperatures tend to increase the amount of thermal decomposition products formed (light hydrocarbon gases and/or char). High hydrogen pressure favors the production of liquids.

Jan 1, 1965

By Alvin Schallis

The. problem of supplying enough magnesia for the American war effort has become highly important. Before hostilities began, only about two-thirds of our, require vents came from domestic sources; now they must supply almost all the magnesia we need. A further burden is placed upon our own supply by the fact that more and more magnesia is being required, not alone to pace the war tempo of general industrial activity, but also to replace chrome ore in refractories and to make magnesium metal. The domestic magnesite and brucite industry is equipping itself to satisfy much of this greater demand for magnesia, but the remainder must be obtained elsewhere. The principal sources of magnesia are magnesite, brucite, dolomite or high-magnesium limestone, natural brines, sea water, salt-works bitterns, magnesium silicates, and magnesium salts. Although dolomite is tae subject of this paper, it should be considered in perspective with all these highly competitive sources of magnesia.

Jan 1, 1943