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By F. D. Delve

RECENT studies by the author on the reduction of titanium from TiO2-bearing slags have been accompanied by difficulties that are attributed to

Jan 1, 1959

By Thierry Coléou

In this paper, we consider open pit optimization. At present, most methods specify the economic parameters and then find the corresponding optimal pit. But as the economic environment varies (which it does regularly these days), the "optimal" pit changes and quite often changes markedly. The questions are: by how much does it change and which parameters are most influential? The functional approach of Technical Parameterization of Reserves, devised by Matheron in 1975, gives the set of all the different optimal pits, under any economic condition. It separates technical design and economic assumptions and thus permits the use of several optimality criteria when choosing the final pit, and not just the maximization of an additive profit formula. Very efficient specific algorithms are presented to obtain all the potentially optimal pits. Fluctuations in the parameters induce changes in the optimum design. Inclusion relations that exist generate very tight bounds and hence very quickly detect optima, even when using a classical adaptation of maximization techniques (graph theory, moving cone, dynamic programming ...). The advantage of Technical Parameterization of Reserves over other methods is that it provides a nested sequence of optimal pits which can then be used for mine scheduling. Many possible mining schedules can be obtained by using the family of technically optimal projects to split up the orebody. The "optimal" schedule, which is in fact a compromise between the different requirements of the economists, the mine planner and the metallurgist, can be chosen from within the wide scope of possibilities. A practical example of mine scheduling for a chromite mine is presented in detail.

Jan 1, 1989

By K. J. Miller, R. E. Hucko

The Coal Reparation Division of the Pittsburgh Mining Technology Center conducted an investigation to assess and compare the pyritic sulfur reduction potential of coal-pyrite flotation and high-gradient magnetic separation (HGMS). Tests were run on three coals - an Upper Freeport bed coal, a Lower Kittanning bed coal, and a Pittsburgh bed coal - to establish grade-recovery relationships characteristic of both processes. Representative portions of each coal sample were crushed to two top sizes-nominal - 500 pm (-35 mesh) and nominal - 149 pm (-100 mesh)-and subjected to conventional froth flotation. The froth product was then beneficiated by coal- pyrite flotation or HGMS, to provide a direct technical companion of the two processes. At - 500 pm (- 35 mesh), the size normally employed for coal flotation, both coal-pyrite flotation and HGMS effectively separated pyrite from coal, and the performance of the two processes was essentially the same. At a - 149 pm (- 100 mesh) sire, however, the performance of HGMS exceeded that of coal-pyrite flotation. The separation effected by HGMS were more efficient at - 149 pm (- 100 mesh) than at - 500 pm (- 35 mesh). On the other hand, it was concluded that either the effectiveness of coal-pyrite flotation decreases with diminishing top size or the process has not been optimized to treat material finer than 500 pm (35 mesh).

Jan 1, 1983

"Chairman: Professor J. de V. Lambrechts Rapporteur: Mr R. HempPapers:Computer-aided design of a flash smelting installation by M. A. T. Cocquerel, R. T. Gates and L. A. GreenPlanning of mine ventilation by E. U. Reuther and A. DohrnenCoal mine ventilation systems in the U.S.A. by R. Stefanko and R. V. Ramani Heat flow models in ventilation planning by A. J. Dickson and A. M. StarfieldThe first of the papers in the session dealt with a flash smelter installation, while the remaining three papers dealt with mine ventilation. In view of this the Chairman proposed that the paper on flash smelting be introduced and discussed first, after which the remaining three papers would be introduced followed by discussion on all three.Dr Cocquerel, who presented the first paper, used some typical flow diagrams to illustrate the process and stated that the program considered only steady-state operations and did not take into account the dynamical changes. Subjective judgment was necessary for the preparation of input data and some degree of user appreciation was required.Dr Cocquerel said that no work bad yet been done on an optimization program, but that this was being considered. Such a program would require a large amount of physical and chemical data which were not yet available. The variables to be optimized were the energy and material consumptions and the loss of metal in the slag.The Chairman opened the discussion by asking Dr Cocquerel if he could give a brief description of the flash smelting process for the benefit of those not familiar with the subject. Dr Coquerel replied that in the Outokumpu process con¬centrates were injected directly into the furnace, and that the process was somewhat analogous to flash distillation or evaporation processes, but was perhaps closer to the burning of pulverized fuel.The process had two distinct advantages. First, the heat evolved in the smelting reaction was used to heat the furnace, which resulted in less fuel consumption, and, second, the effluent gases were cheaper to treat than the effluent gases from other pyrometallurgical processes. This was important particularly in view of the current interest in pollution problems.Mr P. Marais thought that the authors had done themselves an injustice by not including details of the very complex processes taking place in the furnace."

Jan 1, 2014

The 1996 Arizona Conference was held in Tucson on Dec. 8 and 9. Attendance was 648, a 12% increase from the 1995 conference. The annual conference is organized by the Arizona Conference Board of Directors, representing SME sections from throughout Arizona and adjacent areas. In addition to those representing mining and processing operations in the Arizona region, the meeting was well attended by interested parties from throughout North America. These included vendors, consultants, academia, research organizations and corporate management. The technical program highlighted the meeting. It consisted of a keynote address and morning and afternoon technical sessions. In the technical sessions, 23 papers were presented by the mining, hydrometallurgical, smelting, geology and mineral-processing divisions. The conference was then capped by a banquet that included a talk by a noted economist. Keynote address The program was kicked off by a keynote address titled "Forecasting for the 105th Congress," by Rep. John Shadegg (R-AZ). He was elected to Arizona's Fourth Congressional District in 1994. Shadegg serves on the House Budget Committee, the Resources Committee and the watchdog Government Reform Committee. He stressed the familiar conservative positions of reducing government spending, balancing the budget and states rights. As a member of the House Resources Committee, Shadegg stated his support for the mining industry. Technical sessions Mining division. Two of the five presentations described developments at two Arizona mining operations. T.J. Swendseid of Phelps Dodge presented a paper titled "New developments at Morenci" and P. Garretson of BHP presented a paper titled "Startup of the Robinson Project." Morenci continues to expand its operation and recently broke records for production. Other developments at Morenci included the completion of a 600-m (2,000-ft) drainage tunnel and stockpile rehandling. In addition, Phelps Dodge moved Morenci's crusher plant. It was completely disassembled and reassembled in just eight days. Another interesting presentation was "Predictive maintenance techniques for large electric shovels at Cyprus Sierrita," presented by T. Ritzel of Cyprus Amax. The presentation described high-technology methods for predicting maintenance problems. These methods included vibration analysis, ultrasonic detection, infrared thermography, electrical measurements and tribology (the science of lubricant evaluation). The benefits of these techniques are reduced downtime of the equipment, as was demonstrated in case studies at the mine. The other presentations were "Introduction to NOSA 5-star safety program," by R. McKinnon, BHP Copper North America, and "A new design guideline for mine sealing," by K. Fuenkajorn, Rock Engineering International. Hydrometallurgical division. The hydrometallurgical session consisted of five papers. These included a presentation titled "Recovery of gold and silver using guanidine-based extractants," by M. Vining of Henkel Corp., Tucson, AZ. In this presentation, guanidine-based extractants LIX-79 and AURIX resin were introduced. LIX-79 was shown to have applications in copper-gold and high silver ores. In ammonia-cyanide leaching, AURIX was shown to be more selective in CIL vs. RIL comparisons. Other papers in the hydrometallurgical division included "Application of cobalt in the copper industry," by J. Hawke, OMG Apex Inc.; "Series parallel conversions and production gains at Cyprus Miami Mining's dump leach and solvent extraction operation," by E. Bilson of Cyprus Amax; "Lead alloy anode corrosion at the San Manuel SXEW tankhouse," by W .M. Gort of BHP Copper and "Hydrometallurgical treatment of copper refinery slimes," by B.C. Wesstrom of Phelps Dodge. Smelting division. Three papers were presented in the smelting division session. These included updates and reports on improvements at the Hayden, Hidalgo and BHP San Manuel smelters. For example, W.A. Dutton of Phelps Dodge presented "Recent improvements at the Hidalgo Smelter." These changes were aimed at reducing environmental emissions and increasing production. They included modifications to the fugitive-gas collection system to reduce particulate emissions, rubber lining the acid plant scrubbers to reduce corrosion and the installation of a cold lime softening system for water treatment. Equally interesting papers were presented by D. Norton of Asarco, Hayden, AZ, in a paper titled "Update of the Hayden smelter process," and by D. Jones of BHP Copper, San Manuel, AZ, in a paper titled "Update on first campaign of the BHP San Manuel Copper." Geology division. The session began with a paper that outlined the progress of an exploration project in South America. "The Pierina exploration project, Ancash Province, Peru" was presented by J.D. Lowell, Lowell Mineral Exploration, Rio Rico, AZ. Another paper was then presented on a copper deposit in Grant County, New Mexico. "Zonation of supergene copper minerals at Hanover Mountain, Grant

Jan 1, 1997

By Robert Stefanko

The importance of underground stress instrumentation cannot be minimized. It was Lord Kelvin who said that unless you can assign a number to a quantity,, you know very little about it. Most engineers will agree although this kind of statement is resented by our friends in non-technical fields. Mining is undergoing a revolution from art to science. But how can mining methods be optimized if there is no way of measuring the effectiveness of a given mining method? Do we know how effective a' support is unless we can determine its reaction to the mine structure? How do we assess the need for modifications to existing systems and supports, and how do we measure the effectiveness of such changes? Cut and try techniques are too wasteful of time and energy, and rarely provide solutions to a given problem. The purpose of underground stress instrumentation is to provide answers to some of the above questions -- answers that cannot be obtained otherwise This does not mean that laboratory studies are not valuable -on the contrary. Laboratory and underground studies supplement one another. Rock mechanics had its conception with the study of stresses in homogeneous, isotropic, and elastic models subjected to various force systems. These analyses were valuable inasmuch as they pinpointed possible sources of trouble due to stress concentrations. If the results observed underground did not always agree with the experimental analysis, it was not an indictment of the latter. More probably, the discrepancy could be attributed to the lack of similitude between model and prototype. The more nearly one can simulate underground conditions in a model, the more apt one is to produce results which correlate well-with underground observations. It is impossible to completely simulate underground conditions because all of the significant design parameters have not been recognized and evaluated. What better way can one evaluate these parameters than by underground stress instrumentation?

Jan 1, 1963

All the TECHNICAL PUBLICATIONS and CONTRIBUTIONS published in 1934 are available at Institute headquarters, unless otherwise noted They are also on file in many public, university and technical libraries and, when so indicated in the list, may be found in the TRANSACTIONS Copies of the TECHNICAL PUBLICATIONS have been mailed to those members of the Institute who are registered in the different classes A-Metal Mining, B-Milling and Concentration; C-Iron and Steel Division; D-Nonferrous Metallurgy; E-Insti¬tute of Metals Division; F-Coal Division; G-Petroleum Division; H-Nonmetallic Minerals; I-Mining Geology; J-Mineral Industry Education Division; K-Mining Administration; L-Geophysical Prospecting Other members may obtain copies by writing to the Secretary Copies of CONTRIBUTIONS may also be obtained from the Secretary's office Additional copies are sold at the rate of 1 cent per page, minimum charge, 25 cents Nonmembers may purchase the papers at the prices mentioned

Jan 1, 1935

All the TECHNICAL PUBLICATIONS and CONTRIBUTIONS published in 1936 arc available at Institute headquarters, unless otherwise noted They are also on file in many public, university and technical libraries and, when so indicated in the list, may be found in the TRANSACTION Copies of the TECHNICAL PUBLICATIONS have been mailed to members of the Institute that are registered in the different classes A-Metal Mining, B-Milling and Concentration, C-Iron and Steel Division, D-Nonferrous Metallurgy, E-Institute of Metals Division, F-Coal Division, G-Petroleum Division, H-Industrial Minerals Division (Nonmetalhcs) , I-Mining Geology, L-Geophysical Prospecting Other members may obtain copies by writing to the Secretary Copies of CONTRIBUTIONS may also be obtained from the Secretary's office Additional copies are sold at the rate of 1 cent per page, minimum charge, 25 cents Non-members may purchase the papers to the prices mentioned

Jan 1, 1937

By Peter Ay, Elena Geldt, Satyanarayana Narra, Claudia Glaser

"As part of an extensive research and development project, the technical and technological implementation of the patents DE 10 358 245 B4 and WO/2006/056172 was developed with the goal to present a system for the innovative roll- agglomeration method exhibiting a) a modular setup, b) high productivity and c) suitability for the use of fibres of different applications and product qualities (high technical availability). The processability of the rarely adapted raw fibre materials into high-value intermediates brings forward their application in various processing industries dealing with the production of fibre reinforced plastic composites, heat and sound insulation materials as well as with the gas and liquid cleaning systems. The innovative fibre agglomeration presented in this work is performed by a combination of rolling and pressing the fibres inside a geometrically pre-defined roller table, in which the fibres are forced to bound through entanglement / interlocking and develop into agglomerate. The agglomeration process is carried out in a circular roller path with a rectangular cross-section. For improving the adhesive properties, and thus the quality of the agglomerates, the boundary surfaces can be covered / patterned / lined / coated with various materials. The resulting roll-agglomerates are characterized by different quality parameters such as mass, shape, porosity and stability. The properties of the agglomerates can be modified based on the end-product requirements by slightly modifying the process parameters such as filling ratio, residence time, roll-geometry, procurement of the boundary surfaces, etc. as well as the input material properties such as fibre type, fibre fineness, fibre length, etc. This work carries extensive work on the roll-agglomeration system to assess the effectiveness and the variability based on the product specifications. Agglomerates were produced with wide variations of system parameters with varying roller table liners and based on evaluation of the produced agglomerates with respect to their mass, the geometrical dimensions, their porosity and stability."

Jan 1, 2014

By L. E. Young

GERMANY'S recent collapse and the occupation by the Allies of the coal fields of the Ruhr, the Saar, Silesia, Poland, and Czechoslovakia have focused attention on the postwar coal problems of Europe. American coal operators are interested deeply in what is happening in Britain, particularly in the discussion of plans to rehabilitate and reorganize the entire British coal mining industry, as such reorganization will probably determine the place Britain will occupy in the European coal markets for the next few decades. The continuing decline of British out-ut per man-shift, particularly during wartime, has resulted in a most serious effort to determine whether this unfortunate trend is due to the physical condition of the coal seams, poor management, poor engineering and planning, inadequate use of power and machinery, or failure of labor to co-operate with management.

Jan 1, 1945

By J. Y. Tian

In view of the fact that many domestic iron ore-dressing plant applying flotation cells in the re-verse flotation, to improve the technical level of magnetite reverse flotation, we apply such a technological process of one stage rougher and two stages scavenger flotation column respectively. The middling from the two stage scavenger process are returned to magnetic separation for condensing. By contrast, the technological process of one stage rougher and one stage cleaning flotation cells is made up of by multi-magnetic separation and magnetic middling regrinding separations. It has been proved that the flotation column we offer can simplify the technological process structure, obtain advanced technical indexes, run the system smoothly, reduce energy consumption, and be environ-mental friendly.

Jan 1, 2014

By L. Lorio, B. Hilscher, P. Nayak, N. Yoon

"Mining has been a staple to technological advancement ever since the dawn of time. By harnessing the different physical and chemical properties that each mining commodity brings to the table, more and more innovation is developed and manufactured. As these non-renewable resources continue to be extracted, the industry as a whole faces a challenge in finding the next economical deposit as well as declining grade at the current operations. By means of pre-concentration, ore sorting aims to separate the barren material from the valuable ore to reduce energy consumption and tailings generation, while increasing the feed grade, concentrate grade, mill recovery, and revenue. In addition, ore sorting allows the modification of deposit geometallurgy in order to allow the creation of an optimal mill feed. This paper evaluates the applicability and challenges of ore sorting by utilizing the results from four different mines, and reviews them in detail. The mines include one underground and three open pit mines that are precious metal operations. In order to understand the applicability of ore sorting in these operations, initial rock-by-rock test results and different types of assays (atomic adsorption [AA], inductively coupled plasma [ICP], and fire assay) are utilized. Using the assay results, the grade recovery curves for ore sorting are generated and they are further improved by using and developing an ore sorting algorithm, which is discussed in this paper. The application and evaluation of ore sorting in greenfield and brownfield properties will also be discussed. The state of the art ore sorting technologies for both rock-by-rock and bulk sorting are also reviewed in this paper. The future technologies on the horizon, including different combinations of sensors, are explained. The sorting technologies include X-ray transmission (XRT), X-ray fluorescence (XRF), colour, infrared, electromagnetic, and laser induced breakdown spectroscopy (LIBS)."

Jan 1, 2017

By B. Hilscher, P. Nayak, N. Yoon

"The mining industry is currently facing challenges with declining feed grades and is struggling to find solutions to improve the project’s economic value. By means of pre-concentration, ore sorting aims to separate the barren material from the valuable ore to reduce energy consumption and tailings generation, while increasing the feed grade, concentrate grade, mill recovery, and revenue. In addition, ore sorting allows the modification of deposit geometallurgy in order to allow the creation of an optimal mill feed.This paper evaluates the applicability and challenges of ore sorting by utilizing the results from four different mines, and reviews them in detail. The mines include two underground and two open pit mines that are base metal and precioius metal operations. In order to understand the applicability of ore sorting in these operations, initial rock-by-rock test results and different types of assays (atomic adsorption [AA], inductively coupled plasma [ICP], and fire assay) are utilized. Using the assay results, the grade recovery curves for ore sorting are generated and they are further improved by using and developing an ore sorting algorithm, which is discussed in this paper. The application and evaluation of ore sorting in greenfield and brownfield properties will also be discussed.The state of the art ore sorting technologies for both rock-by-rock and bulk sorting are reviewed in this paper. The future technologies on the horizon, including different combinations of sensors, are explained. The sorting technologies include, X-ray transmission (XRT), X-ray fluorescence (XRF), colour, infrared, electromagnetic, and laser induced breakdown spectroscopy (LIBS).IntroductionOre sorting is a sensor-based sorting technique introduced between the excavation stage and processing stage, where the unwanted waste is diverted to the waste dump and only the ore is sent to the mill for further processing. As a result, the quality of the material entering the mill is improved and the dilution of the ore is reduced. In greenfield projects, sensor-based ore sorting provides an opportunity to reduce the capital cost of the project and increase the return on investment (ROI). With most operations currently facing the challenge of finding a high grade deposit, having a sorting unit provides several advantages while keeping the cost at minimum."

Jan 1, 2017

By D. Tolgyesi, L. P. Gignac

Mine development has evolved in the past 15 years from a human-paced system using hand-held drills and track-bound equipment to a mechanized system using specialized equipment for each component of the development cycle. In most Canadian hard-rock mines, face advance is achieved by the following sequential activities: drilling, explosive loading, mucking and ground support. The state-of-the-art for each work element is reviewed and methods for performance estimates proposed. The entire development system and its production capabilities are considered based on equipment reliabilities, spare units, haulage distances, and muck bay spacing. The effect of the number of working faces on the system's performance will also be analyzed. Manuscript not received in time for publication.

Jan 1, 1983

By Agus Setiabudi

East Pit Wira II Project in South Kalimantan, Indonesia with a radius of <500 meters (1,640 ft) from residential has about 454,168 tonnes of coal reserves, with a total remaining reserves of 3,369,383 tonnes (topography per end of June 2011). Thus, reserves may be lost as much as 13.48%. Therefore, it is needed to determine safe blasting technique which meets the Indonesian National Standards (SNI) No. 7571:2012 of vibration threshold, the maximum vibration of 3 mm/s (0.118 in/s) and air blast of 120 dB.

Jan 1, 2014

By J. E. McGill

The junior and small-scale mining sectors in South Africa play an important role in the livelihoods of numerous communities. Mining presents an opportunity, in the post-1994 democratic era, for many individuals to obtain access to much required empowerment and socio-economic development. These sectors are, however, not without numerous characteristics that pose problems for operators, legislators, and other role-players. Mining is inherently risky, with operators experiencing frequent difficulties and challenges throughout the life of mine. Opportunity exists, and needs to be enhanced, for junior and small-scale prospects and operations to include technical risk assessment techniques in documentation presented in search for funding, and in optimizing monthly planning and longer-term functioning. The focus here is to explore how the risk management cycle may currently be applied to a mineral resource suitable for exploitation by the junior and small-scale mining sectors. No management process can create additional value in the ground, but various available mechanisms can go a long way to quantifying the inherent risk that exists, highlighting the need to manage the risks and hopefully allowing the entrepreneur access to the intrinsic opportunities of the emerging mining sector in South Africa.

Jan 1, 2006

By Richard H. Spencer

Since the passage of the Coal Mine Health and Safety Act of 1969, the Bureau of Mines has made many advances in mine communications. These efforts have resulted in the following developments and demonstrations: Surface-to-surface electromagnetic transmission of baseband voice signals through overburdens as deep as 600 feet. This transmission was achieved with equipment from the Interim Mine Rescue and Survival System Program, and demonstrated that baseband voice communications could be obtained through these overburdens in the absence of mine-generated noise; that is, when the mine power system was shut off, However, during mine operational conditions, the mine-generated noise proved to be so large that effective baseband voice communications to the desired depths could not be effected.

Jan 1, 1975

By John D. Foulkes, David A. Curtis, Robert L. Lagace, John L. Rothery

An investigation is made of the feasibility of developing compact transmit antennas and/or other means to efficiently couple VLF to MF band radio energy between portable wireless communication units in coal mines. The completely wireless communication ranges between two portable radios equipped with practically-sized reference loop antennas in representative coal mine environments are estimated. Antenna technology is assessed with respect to transmit moment, range, intrinsic safety, battery and wearability requirements to deter- mine the most suitable antenna types for use by miners. It is concluded that air-core bandolier loop antennas, and perhaps ferrite-loaded loop antennas, having peak transmit moments of about 2.5 ampere-m5 will be the most effective antenna choices for portable units. This choice, however, will not allow the range goal of 1350 feet to be attained in mines having unfavorable signal attenuation and noise environments. Rectangular air-core loops are compared with grounded horizontal-wire and vertical-wire mode exciters for fixed station applications. The potential for significantly increasing the wireless communication range by inductively coupling to communications and power lines in a mine is evaluated and found to be considerable based on theoretical coupling equations. Lastly, the theoretical performance of a hybrid noise cancelling diversity receiving technique that utilizes both the electric and magnetic field components of the ambient noise to improve the receiver output signal-to-noise ratio under certain adverse conditions is estimated and shown to be favorable when the magnetic and electric field noise components are highly correlated.

Jan 1, 1977

By C. A. Herbert

We all deplore the high accident rate of our coal mines, but when brought to task we immediately attempt to appease our conscience by calling attention to the high tonnage rate per fatality in American coal mines as compared to European mines, losing sight of the fact that the accident rate per hours of exposure has shown no improvement during the past twenty years. Measuring our accidents in terms of hours of exposure, not in terms of production, is the only correct method. Certainly it can be of only scant satisfaction to the miner to know that his chances of getting killed this year are as great, or perhaps greater, than last year, but the tonnage rate per fatality will have gone up. We cannot help asking ourselves why it is the other major industries, almost without exception, have made wonderful strides toward reducing accidents, while coal mining stands alone as the one major industry in which no improvement has been made. It certainly cannot be charged entirely to the increased use of machinery and the increased productivity per man employed, as the other industries likewise, or to an even greater extent, have increased the use of machinery and the production per man.

Jan 1, 1931

Mine Taxation On Monday morning, Sept. 22, a session on- Mine Taxation was held in cooperation with the Internal Revenue Dept., U. S. Treasury, Mr. R. C. Allen presiding. This was followed by two adjourned sessions, at which Mr. R. C. Allen and Mr. A.D. Brokaw presided. The following paper was presented: Federal Taxation of Mines. By L. C. Graton. (Presented by the author; dis¬cussed by R. V. Norris, W. O. Hotchkiss, W. P. Beldon, Paul Armitage, R. C. Allen, E. F. Brown, William Belly, A. D. Brokaw, F. W. Sperr, C. H. Benedict, E. P. Griffitts, W. E. Forsythe, and the author). Coal and Gas The first session on Coal and Gas was held on Monday morning, Sept. 22; the second, on the afternoon of the same day. Mr. Curl Scholz presided at both sessions. The following papers were presented: Research on the Coal-mining Industry. By E. A. Holbrook. (Presented by the author.) Some Factors that Affect the Washability of a Coal. By Thomas Fraser and H. F. Yancey. (Presented by the author.) A Use Classification of Coal. By George H. Ashley. (Presented by title.) Distribution of Anthracite. By A; S. Learoyd. (Presented by title.) Height of the Gas Cap in the Safety Lamp. By C. M. Young. (Presented by the author.) Engineering Features of Modern Large Coal Mines in Illinois and Indiana. By C. A. Herbert and C. M. Young. (Presented by the authors.) Gas-producer Practice. By G. S. Brooks and C. C. Nitchie. (Presented by the authors.) Testing of Coals for Byproduct Coking and Gas Manufacture. By Horace C. Porter. (Presented by the author.) Coals of Ohio and their Limitations for Byproduct Coke. By Wilber. Stout. (Presented by the author.) Outdoor Substations in Connection with Coal-mining Installations. By H. W. Young. (Presented by the author.)

Jan 11, 1919