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Several major impediments threaten the successful delivery of tunnel and under-ground construction projects. In addition to technical design and construction risks associated with tunnel projects, many of which are well understood, budgetary pressures, funding constraints and the complexity of procuring, administering and executing multiple concur-rent projects in a large program could also have a catastrophic impact on the program?s objectives. Contributing factors often include poorly managed design, procurement, construction, managerial, organizational, market and stake-holder risks, as well as nonconforming inputs or outputs to the costs and schedule, or any other potential inabilities to deliver the required or desired results. A strategy to prevent ?failure? of a project requires a proactive and holistic approach to risk management. Through planning, identification, analysis, management, monitoring and control of the project?s risks (both threats and opportunities), attention to management of risk will in-crease the probability and impact of positive events and decrease the probability and impact of events adverse to a project?s objectives.

By John L. Schroder

In selecting the best system of mining for a particular operation, many different factors must be considered. The system to be finally selected should be that which provides: 1) The highest possible degree of safety for mine personnel. 2) The lowest cost per ton of product. 3) The maximum coal production per man-shift. 4) The most suitable quality of final product, considering its intended use. 5) The maximum percent recovery of coal per acre of reserve consistent with cost and subsidence rights. 6) Consideration for the ecology of the area. Some of the important factors to be considered when choosing a method of mining are: 1) Amount of cover over the coal seam. 2) Type of the rock in the overburden. 3) Characteristics of the coal seam including: (a) the thickness of the coal seam; (b) the nature and location of any impurities or irregularities; (e) the dip (or pitch) of the coal seam; (d) the nature and direction of any definite cleavage ill the czoa1 seam; (e) the hardness of the coal; (f) the structural strength of the coal; and (g) the presence, anti amount, of explosive gas (methane). 4) Quantity of water likely to be encountered in the mining operation. 5) Nature and strength of the roof (top) over the coal seam. 6) Nature and strength of the floor (bottom) under the coal seam. 7) Any previous or concurrent mining in seams above or below the coal seam to be worked. Information on items 1-7 may be obtained in several ways. Topographical and geological reports and maps of the area are generally available

Jan 1, 1973

By Richards J. W.

J.W. RICHARDS, South Bethlehem, Pa. (communication to the Secretary?).-Mr. Howland's paper, data and conclusions have interested me intensely, and have led me to study carefully the record-of his 26 furnaces therein given. Mr. Howland is undoubtedly right in his conclusion that when expressing the amount of carbon burned at the tuyères in percentage of the total

Jan 1, 1917

By A. M. Anthony, A. Y. Atta, S. S. Magaji, U. Abubakar-Zaria

There are two major gold recovery methods: the hydrometallurgical technique, which employs cyanide solutions, and amalgamation method, which involves mercury (Hg). These methods present considerable health, safety, and environmental concerns. Past applications of alpha-cyclodextrin (α-CD) on gold scraps show that α-CD is not only inexpensive, but is also environmentally friendly. This research work used α-CD to recover gold from gold ores instead of gold scraps. The gold ore was sourced from Shanono gold deposit site Kano State,Nigeria. The gold ore was characterized by fire assay (FA) for the precious metal. The concentrate was digested with aqua regia (AR) for 24 h. Modified AR, where hydrochloric acid was replaced with hydrobromic acid, was used for the gold digestion due to the good match in molecular recognition between gold bromide ion (AuBr)− and α- CD in a second sphere coordination complex. The digestate was characterized using atomic absorption spectroscopy (AAS). Gold recovery using this technique is pH sensitive, and five pH values (2.0, 3.6, 4.0, 5.4, and 6.0) were investigated. FA analysis showed the Shanono gold ore deposit contains an average of 4.71 ppm of gold, AAS analysis showed highest gold recovery of 69% at pH 4.0, which is lower than recoveries from the metal scraps. This could be due to the presence of other gangue minerals closely associated with the ore. However, gold recovery using α-CD on Shanono gold ore has shown to have a higher yield of 69% compared to 35.5% yield obtainable by Artisan Small Scale Miners using mercury.

May 5, 2020

By Len Blackman

The Absaroka-Beartooth Study Area is a tract of approximately 1.4 million acres of National forest land in southern Montana, part of the Greater Yellowstone Area. This study evaluated the mineral potential of four mineral terranes containing undiscovered resources in the area. The geological data is probabilistic, with estimates of the possible number: of deposits and their grades and tonnages. Possible future development scenarios range from no development to many mines, including some very large. As two thirds of the study area is within the Absaroka-Beartooth Wilderness, the future development scenarios reflect the area's mineral potential, not what we expect to see in the foreseeable future. Based on the analysis performed on these four terranes, the most likely future scenario for the study area would include the potential for two medium sized, (predominately) gold, mines, each employing a few hundred workers. There is a small chance, less than 5%, that a large Porphyry Copper or Superior Iron deposit would be discovered and be economically feasible to develop.

Jan 1, 1994

By Luisa Perez, Carlos Perea

El método de explotación por subniveles es uno de los más utilizados en operaciones mineras de mediana y gran escala, como es el caso de la minería de zinc en Perú. Para seguir la secuencia de explotación, este método requiere el relleno de los caserones vacíos, como por ejemplo el relleno en pasta, el cual se produce mediante la mezcla del relave producto de la planta concentradora de mineral con un 3.5 % de cemento, con el fin de que dicho relleno actúe como pilares de gran dimensión que aporten el sostenimiento necesario a la mina (0,8 MPa). Sin embargo, esto genera una dilución con el mineral a explotar al momento de avanzar en los tajos aledaños. Por ese motivo, y por la necesidad de lograr la automatización de la operación minera, se decide evaluar el relleno detrítico cementado, evaluación que se realiza mediante el análisis de resistencia, estudios de factibilidad, rendimiento en costos, aumento de productividad y seguridad en la operación. El resultado son valores máximos de resistencia de los pilares de 1,6 MPa, que evitan la dilución y mejoran el porcentaje de recuperación de mineral.

Sep 20, 2019

By R. Zins

During the past few years, a completely new concept has been applied to the design of drives for operating at very low speeds. In this, the motor is supplied by a variable-frequency thyristor cyclo-converter. Today, frequency converters with practically unlimited power ratings can be constructed. The system frequency of 50 or 60 Hz is reduced to about 10 % of these values. This makes it possible to operate the synchronous motor, which has a correspondingly high number of poles, at the extremely low speed of the driven mill, i.e, without interposed gearing. The first motors of this type were built to drive ball mills in the cement industry, which are very similar to those employed for ore processing. Here, too, the tendency is to build units of ever increasing capacity. In the case of conventional drives with mechanical gearing, this involves correspondingly increasing difficulties. These difficulties have prompted various studies of the possibility of applying the new type of drive to ore mills as well, but a gearless drive has not yet been built for this application. However, gearless drives for ore mills will certainly materialize soon and it was therefore considered a logical step to report at the A.I.M.E. Conference on the experience gained with these drives in the cement industry, and on the present state of development.

Jan 1, 1973

By Thais Couto Silva

Foram realizadas simulações numéricas, utilizando Computational Fluid Dynamics, para determinar o comportamento fluidodinâmico em condições isotérmicas de metal e gás no interior de um reator RH. São estudados os efeitos da taxa de injeção de gás sobre a distribuição espacial de gás, taxa de circulação e campo de velocidade no sistema. Analisa-se, a partir dos dados de simulação, os resultados de uma operação industrial de dessulfuração por adição de reagentes na câmara de vácuo.

Aug 16, 2017

By F. C. Appleyard

As one of the more important Industrials Minerals, gypsum occupies a significant place in the economy of the United States, particularly in that segment which can be loosely called the Construction Industry. For many years, products made from gypsum have been a major building material, and the usefulness and versatility of these products is such that their widespread use is expected to continue. In 1968, according to U.S. Bureau of Mines statistics, the value of all gypsum products sold in the United States was 405,000,000 - and although this value has dipped from the 1964 high of $ 432,000,000, it is expected to trend upward in the next few years to equal and surpass this figure as the construction industry recovers from its current squeeze of "tight money" and high interest rates. There are many factors to be measured in determining the potential value of any mineral deposit, and how it might fit within its particular industry. What, then, are the qualities which a gypsum deposit must have in order to profitably participate in the four hundred million dollar plus business which is the gypsum industry? First let's consider the geology of gypsum, the geographic distribution of deposits, and the more important factors such as size, grade, capital requirements, and operating cost. Then, an understanding of the uses of gypsum, various types of products, and location of markets would be helpful, along with such other factors as the structure of the industry, price trends, etc.

Jan 1, 1970

By Ricardo Oliveira Gallart de Menezes, Claudio Gerheim Porto, Reiner Neumann

The Jiboia heavy mineral sands deposit is a new discovery associated with the São Francisco River delta on the northern coast of Sergipe state. The identified resources are part of the much larger mineralized trend. Mineralization is hosted in paleodunes deposited on Holocene marine terraces (Fig. 1). The dunes are up to 30 m above sea level, and mineralization occur from 6 m above sea level upward. The main ore minerals constitute pseudorutile, ilmenite, zircon, rutile and monazite. This work presents a thorough characterization of the mineralogy and granulometric distribution of the Jiboia orebody.

Apr 1, 2024

By M. J. Ackerman

This study was undertaken to make a comparison between the cost of mining coal under roof bolt and under conventional timber methods of roof support. Studies were made at 14 mines in Pennsylvania, eastern Ohio, and northern and southern West Virginia. At each mine data were obtained for sections of the mine where the physical conditions, mining equipment, and mining systems were similar. Coal, recognized as one of the basic industrial fuels, is very competitive with other fuels, and management, in order to protect and enlarge its market, must be continually alert to find more efficient methods of production. Continuous production of coal is desired by all operators but never obtained. In mechanized mining the performance and production vary with operating time, which can be interrupted by many variable factors, such as condition of the roof, method of roof support, condition of equipment, water, ventilation, power, transportation, efficiency of operating crew, and supervision.

Jan 1, 1961

By L. E. Cardwell

This publication contains routine analyses and related source data for 390 natural gas samples from 22 States and five foreign countries. Of this total, 385 samples were collected during calendar year 1969. The remaining five analyses are of samples collected during previous years, but releases granting permission to publish the results were not received until 1969. All samples were collected as part of a continuous survey of the free world for occurrences of helium in natural gas. This survey has been conducted in the United States by the Bureau of Mines since 1917. In late 1965, the survey was expanded to include foreign gasfields. The analyses published herein were made by mass spectrometer and a special helium analysis apparatus which are described in Bureau of Mines Bulletins 4863 and 576.4 Eleven previous publications have presented the results of 8,660 gas analyses made by the Bureau of Mines Helium Activity prior to 1969. The first three, Bulletins 486,6 576,6 and 617,7 contain analyses and related source

Jan 1, 1970

By Thorkil Kristensen

El presente texto cuestiona la nueva legislación propuesta relativa a la producción e inversiones en la Gran Minería del Cobre. Para ello, se han determinado metas dentro de un programa y así lograr lograr un mayor ingreso de divisas, mayor tributación, nuevas fuentes de trabajo, etc. Entre las principales metas tenemos: el aumento de la refinación del cobre en el país, la participación directa del Estado en la comercialización del metal, el desarrollo de la manufactura de cobre en Chile aprovechando la experiencia y «non how» de las Empresas y finalmente, la integración al país de las empresas e industrias, de modo que la economía general participe del beneficio de su actividad.

Jul 1, 1966

By R. J. Keene

The South Works high-tonnage billet caster was started in late March 1971, with the first heat being successfully cast to completion. Currently, over 31,500 tons per month are being produced. U. S. Steel designed and built this caster with the objective of producing quality-steel billets for critical bar, rod, and wire applications. The essential design parameters were based on studies conducted on the Research Laboratory's pilot caster, also located at South works. 1,2,3)* The caster is a four-strand, straight-mold machine that produces 7.5-inch- square billets at rates exceeding 300 tons per hour. An in-line-reduction mill reduces each strand to either 6-inch-, 5-inch-, or 4-inch-square billets.

Jan 1, 1972

By R. G. B. Pickering

Over the last few years Lonmin Platinum and Sandvik have embarked on a unique partnership of collaboration through a systematic approach to developing equipment to mechanize and automate narrow reef platinum mining. After the initial design and manufacture of the equipment the key aspect is the integrating equipment, people and method into a mining system. Another key aspect of mechanization is the optimization of equipment utilization, and this philosophy has ensured continual evolvement of mining methods. This paper describes the trials and development that have resulted in the mining method described as Lonmin mechanized breast.

Jan 1, 2007

By A. U. Miller

Protection against fire is a greater problem at a coal mine, than at an ordinary industrial plant. Generally mines are located in isolated districts and do not have the protection of city fire departments; consequently fire fighting aquipment must be installed by the mining company. Fire protection around a mine is just as essential as it is in the city.. and undoubtedly is more important if the fire should be underground where many lives would be endangered and all means of escape cut off. A surface fire can generally be attacked from any angle, but an underground fire can be attacked only as conditions will permit.. U. S. Bureau of Mines engineers have investigated many serious mine fires that undoubtedly could have been extinguished in incipiency if a fire extinguisher or fire hose and water had been readily available. In past years very little attention was given..to fire fighting equipment and organization around mines, but in recent years three gen a derde hange of opinion among many of those engaged in mining, and nearly all up-to-date mining companies now have some kind of fire protection about their mine Probably the first company in Illinois to install regular fire fighting equipment and effect a fire fighting organization at its mines, was the Madison Coal Corporation, which operates several mines in Illinois. The main office of this company is in Chicago and the general field office is at Glen Carbon, Ill.

Jul 1, 1930

By Xun Zhang, Huiqing Tang

The inner shape of a blast furnace is of fundamental importance for blast furnace ironmaking to achieve goals of high yield, high quality, low fuel rate and long campaign life. Therefore, it is worthwhile to design better furnace inner shapes. This paper conducted numerical simulations of performance for the blast furnaces with conventional and modified inner shapes. By comparing the calculation results of the two blast furnaces with the same operation conditions, it can be found that there are some certain differences. It is necessary to optimize the inner shape of blast furnace considering the results of simulations. This paper provides references for future blast furnace inner shape design and related technology developments.

Mar 1, 2017

By R. D. Williams

Several hydrometallurgical leach processes have been recently proposed for the recovery of copper from copper concentrates. These include the Cymet Process of Cypress Metallurgical Processes Corporation, the Arbiter Process of the Anaconda Company, and the Treadwell Process of Treadwell Engineering company(1). These processes and similar processes for recovery of other minerals, have several phenomenological similarities which make their quantitative description difficult at best. These include (a) the presence of more than one phase, (b) non-uniform mineralization of the feed concentrate, (c) surface and diffusional effects, and (d) a particle size distribution which varies with time. Semi-theoretical, rather than purely empirical, treatment of such processes in their developmental stages will result in a better understanding of the physico-chemical mechanisms in effect. This, in turn, will allow reliable process designs to be made on reasonable time scales for reasonable development costs. Once a production unit is built, such an approach will provide straightforward methods for process control and optimization. A research and development effort to determine criteria and procedures for semi- theoretically characterizing such mineral leach recovery processes has been initiated in a joint venture by the Arizona Bureau of Mines and the College of Mines at the University of Arizona. This group has as its task the mathematical characterization of hydrometallurgical leach recovery processes using semi- theoretical mechanisms for the underlying phenomena. The resulting models are experimentally verified and parameterized on the laboratory scale in such a way that they can be utilized with similarity criteria to provide reliable scaleup to production designs. This discussion will be centered around the elements of such an approach and how they fit together.

Jan 1, 1975

By W. G. Mine

In September, 1953, seismographs were installed in the Crowsnest Pass area of Alberta and British Columbia to study the 'bumps' which were occurring in the coal mines at Fernie and Coleman, and to investigate the possibility that they might be related to minor earthquakes in the area. During the initial phase of the work, three seismographs were operated at widely separated stations, two in the region of coal mines at Coal Creek and Coleman and one at Turner Valley, distant from any mining operations. Some earthquakes were recorded at all three stations and, in addition, many small disturbances were recorded by the seismographs located near the mines, especially -by the instrument at Goal Greek. A closer network of radio-linked seismographs was then in-stalled near Fernie, the records of which definitely established that the small disturbances were occurring in the mine workings, both active and inactive. No relationship was established between bumps and local earth-quakes in the area. This work was initiated as a -co-operative effort with the Fuels Di-vision of the Mines Branch, Department of Mines and Technical Surveys, which has undertaken a study into the phenomena of ground stress relief in underground mine workings.

Jan 1, 1958

By M. Trim, Y. Sun, D. Tepavac, A. Kumar

Configuration of Rozelle Interchange Project’s ventilation system required design and construction of some of the largest and tallest underground civil caverns attempted in Australia. The paper focuses on the technical challenges of designing these caverns within a heterogeneous, generally weak sandstone under highstress conditions while providing a construction sequence that would align with the contractor’s preferred techniques and schedule. Various construction techniques were investigated, but ultimately an observational approach relying on a construction sequence and specialized instrumentation met both the designer’s and contractor’s requirements. Relevant data obtained from excavations and the construction monitoring program are presented within.

Dec 1, 2022