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By M. J. Allan, D. J. Barratt

This paper reviews current testing methods for sizing autogenom and semiautogenom mills in the North American context with comments on the necessity for test work and requirements for different circuits and equipment selection. The economics of testing and the value received are discussed.

Jan 1, 1987

By Haitao Wang, Shen Wang, Dongyin Li, Yongjia Xu, Jinzhao Liu, Xiangjun Chen

The safe and efficient driving of the roadway along the gob is becoming an increasing challenge due to the influence of the integrity and bearing capacity of the side coal and rock mass in the gob under the roof cutting mining mode. The mechanism of protection of the gob-side roadway is shown by modeling the influence of roof cutting and the application of a destress technique on the lateral coal and rock mass zones. The distribution characteristics of stress, displacement, and fracture in the overburden are analyzed by numerical simulation method under the three working conditions. The results indicate (1) construction of row holes and blasting can form artificial structure’s fracture plane above the roadway, which can effectively cut the connection of overburden. The artificial structure’s fracture plane decreases the peak value of the lateral coal body’s support pressure. The peak point and the critical location of the stress reduction area are both transferred to the deep part at the same time, providing adequate space for the gob-side roadway. (2) The stress arch foot in the lateral rock mass rises to the rock layer at the bottom of the roof cutting plane after top cutting, as does the high-pressure area of deviator stress. The fracture plane prevents lateral coal and rock mass instability and limits the negative effects of roof deformation above the gob-side roadway. (3) The triangle slip fracture zone moves to over the roof cutting drilling zone due to the fracture plane, showing a high position compared to its original zone.

Jul 11, 2023

By Charles H. Dowding

INTRODUCTION "On many projects, the tendency is to drop interest and support of the geological service as soon as it seems safe. That . . . is a short-sighted policy . . . It would be of further service perhaps to learn whether predictions were reasonably true to life." --C.P. Berkey, 1938 (3) This paper quantitatively compares predicted and encountered shear zone size and location and rock type for tunnels in the Colorado Mineral Belt. The Colarado Mineral Belt is composed of igneous formations with associated metamorphic rocks and faulting. As such, it represents the most complex of provinces for at-grade predictions (27). Shear zone and rock type data are assumed to be statistically homogeneous because of the common geology of the seven tunnels. It is often felt by geologists and engineers that the amount of information from which a geological model is created is so low that any statistical inferences are unstable. In other words, the addition of new data may drastically alter the means and variances suggested by the model. Therefore, predictions are rarely couched in quantitative statistical terms but modified with "probably," "most likely" or "possibly." Comparison of predicted and encountered data from past geological models will permit the "probably's" to be quantified and distilled from the art of geological prediction. To date, two other studies of the validity of predictions have been made (26 and 16). Together, these two studies indicate that

Jan 1, 1976

By Vaughn E. Livingston

Washington State has a variety of industrial minerals and although not many are produced currently (1982) most have a history of production (table 1). The value of industrial minerals produced in the state exceeds by several times the production value of metallic minerals. In 1981, 15 minerals - cement, limestone, clay, gemstone, pumice, sand and gravel, stone, diatomite, gypsum, olivine, peat, talc, garnet, silica, and dolomite - were produced. Combined value of nonmetallic production for 1981 is estimated at $218,999,000. Cement had the largest estimated value at $102 million, followed by sand and gravel at $47 million, and crushed stone at $29 million. These figures are from the US. Bureau of Mines preliminary production figures for 1981.

Jan 1, 1982

By G. Richard Dreese

Most coal mining states have passed or amended laws restricting strip ruining in the past two years. In light of this and in anticipation of further restrictions by the states and the federal government on strip mining this paper attempts to show the Impact of these new laws on the structure of the coal mining industry in Ohio and specifically on one small stripping firm in Ohio. The implications of the study are applicable to other states under similar circumstances and to other industries which are being caught up in the ecological-economic struggle.

Jan 1, 1973

By W. Z. Rogers

U.S. feldspar output sold or used in 2004 was estimated to be 790 kt (871,000 st), valued at $43 million free-on-board plant. This was below 2003 and about the same volume as 2002. The strong housing market in the United States maintained demand for ceramic tiles, plumbing fixtures, and fiberglass insulation requiring feldspar and shipments of glass containers increased by about 4 percent. Imports of ceramic tiles and plumbing fixtures continue to increase, taking the place of U.S. produced goods, and the feldspar required to make them. Output included flotation concentrates, feldspar content in feldspar-silica mixtures, potash feldspar and aplite.

Jan 1, 2005

By Langtry E. Lynd

Ilmenite concentrates prepared from beach and dune sands of Florida, India, Australia, and other localities deviate to varying degrees from the theoretical composition of pure ilmenite, and generally contain more Ti02 than the formula FeTiO3 would indicate, and some Fe203. This variation in composition is due to different amounts of altered ilmenite in the concentrates.(l) The alteration has been shown to take place by oxidation and leaching of the iron in ilmenite, to yield residual products consisting of amorphous or very finely crystalline titanium dioxide and ferric oxide, Other studies (2) have stressed that ilmenite may alter first to an amorphous titanium-iron oxide, or to an amorphous mixture of titanium and iron oxides, with later alteration to crystalline titanium dioxide. There has been some speculation as to whether alteration of ilmenite is usually caused by weathering or by hydrothermal processes,(3, 4, 5) Three main methods of approach were used to study the mechanism and rate of ilmenite weathering, (1) Etch tests were used to learn the relationship between crystallographic orientation and the rate of chemical attack on ilmenite. (2) Altered ilmenites in New Jersey sands were compared with ilmenite in rocks of the area from which the sands were probably derived, (3) Experiments were carried out to determine at what rate, and by what agents, originally fresh ilmenite could be altered in the laboratory under simulated weathering conditions.

Jan 1, 1959

By A. J. MacKellar

The economic viability of any project is generally assessed on an evaluation of the total capital constructed costs along with operating costs, owner's costs and market conditions. This paper will be directed to the role that Cost Engineering plays in the development of the capital costs and the cost control techniques applied thereto.

Jan 1, 1975

By Ross Goodman, Jesse Salai

The Ohio River Tunnel Project encountered multiple unexpected geotechnical challenges such as crown and invert instability due to the overstress condition affecting the strata above, below, and in the tunnel alignment during and after TBM excavation along with the potential for methane inflow. This paper showcases how the orientation of a tunnel alignment has a significant impact on how in-situ geological stress can impact the excavation of a tunnel from the contractor’s point of view and how geological features influence gas inflow to the alignment over time.

Jun 13, 2021

By C. M. Brinckerhoff

Much has been written in the mining technical magazines about the caving system. Many of these articles were published in the Transactions of the American Institute of Mining Engineers prior to World War II. In recent years little has been written on mining methods or on the detailed planning always required. Block caving had primarily been used to mine deep copper ores in Africa, the United States and in Chile, although other ores had been mined by this same system. Asbestos ore had been caved in Canada, tin ore in Bolivia, molybdenum ore in Colorado, iron ore in Wyoming and Sweden, and limestone in California.

Jan 1, 1984

By Valerie (Wollet) Rebar

Successful execution of fast-track projects is an arduous task at best. Effective and organized management, a comprehensive technical design with an independent check-and-balance system, and optimal schedule components all play major roles in project success, regardless of the required timeline. However, a fast-track schedule intensifies the significance of each of these elements due to the heightened time constraints.

Jan 1, 2008

By A. H. Srnallbone

Over the past few years the rising production costs, shortage of skilled labor, and increased use of lower grade ore bodies have all added justification for the use of on-stream analysis. A rise in the number of on-stream units indicates that this type of assay is now being accepted as a necessity. On-stream analysis is a much more rapid means of obtaining true assays of a flowing product when compared to wet chemistry or "grab" samples dried, briquetted and assayed by x-ray. In contrast, on-stream analysis uses real time samples assayed every 30 seconds while each stream is assayed every 5 to 15 minutes. It is very important not only to know that a change has occurred in the process, but to know what caused the change and how to correct for the change. For example, in a tailing sample the elements of interest comprise between 1% and 10% of the sample. The remainder is water and gangue. Previously the gangue was not assayed nor were the low atomic number elements used for corrections. In addition to the demand for higher accuracies some concentrators were being penalized for excessive Ca or in some cases 5i in their concentrates. This penalty was being imposed by the smelter in order that they could better cope with pollution problems and prolong the life of their furnaces. But until Ca, 5i, and S are measured on-line, nothing can be done about their control. By accurately measuring these light elements on-line, a complete assay is obtained of the total sample providing improved accuracy for the important products. The justification for complete accuracy assays is now even more obvious because they are possible at very 1ittle increased cost and at no increase in analytical time.

Jan 1, 1977

By Charles R. Marek

There is an ever-increasing need for quality construction materials to provide the necessary housing and transportation facilities required for the protection and movement of people and goods. By the year 2000, requirements for housing in the United States will have doubled due to population growth. Requirements for transportation facilities in this same period will also have increased substantially. Further, all existing facilities for both housing and transportation will require substantial maintenance of one form or another. Aggregate is the basic material of the construction industry. There is some occurrence of aggregate source material in virtually every state of the United States, and in every country in the world. United States reserves of commercially useable aggregate have never been systematically estimated and are probably so vast as to be incalculable.1 However, in many areas its existence is largely negated by inaccessibility. Often it is lodged deeply or intricately in the earth or it is too distant from markets to offer a desirable "return on investment" under the present economic structure. Other factors that prevent its utility are the occurrence of small scattered deposits that individually are too small to justify the necessary capital investment for exploitation and collectively are too widely disseminated; also, the aggregate nay be deficient in certain desired chemical or physical qualitites.1

Jan 1, 1974

By S. K. Kawatra

It is common in coal-cleaning operations to produce a fine waste stream which contains a considerable amount of coal, but which is not economical to recover both because it is mixed with large amounts of difficult-to-remove clay slimes, and because the fines are often heavily oxidized. Conventional froth flotation machines cannot produce an acceptable product from such material in a single stage of flotation, and even flotation columns often have difficulty cleaning this type of feed. A new type of flotation column was designed specifically to deal with these problems, and was installed and tested in a coal-cleaning plant in Ohio. The feed coal contained 39.8% ash as fine clay, and 2.83% total sulfur, and was 80% passing 176 micrometers. The coal was a thickener product which had oxidized for some time, and was very difficult to float. However, using the new column it was possible to recover up to 85% of the calorific value in a product containing less than 11% ash, and up to 60% of the calorific value in a product of less that 8% ash. The bulk of the pyritic sulfur was rejected from the coal as well. Multistage flotation tests showed that the flotation column was able, in a single stage, to produce the best froth flotation product that it was possible to recover from this coal.

Jan 1, 1994

By J. Brooks

The use and application of shotcrete for ground support in the Asia Pacific Region is as diverse as the countries that make up this region. This paper will attempt to describe the many methods used on selected projects within that region. The project description(s) will include project logistics, equipment, mix design, products and application methods utilized along with specifications and performance results (where available). The author will attempt to reach a conclusive opinion on the success, or nonsuccess, of the various shotcrete methods employed and the development of shotcrete within the Asia Pacific Region.

Jan 1, 1999

By Elena Chiriotti, Federico Valdemarin, Jan Cenek

"SUMMARY The “28 May Station” is the only transfer station between the existing Green and Red metro lines in Baku. As part of the huge development strategy of the metro network, the complete separation of the existing underground lines has been planned at this location, in order to simplify the operation of the future metro system. The extreme challenge of the project is represented by the need of achieve the separation of such lines over a breakdown of the operation of just five weeks. The lack of direct access from the surface, a complex geology with artesian water layers, a congested underground space and sensible buildings represent additional constraints. The chosen design solution consists in creating a complex steel pipe jacking frame around the operating tunnels and then excavating under such frame two large caverns where the separation of the existing lines and the construction of the new metro tunnels will be achieved. Soil treatments have been conceived to mitigate the geotechnical risks and to reduce possible impacts on the existing structures. The paper illustrate the challenges of this extraordinary project, one of the most complex underground structures under study, the design solutions and the risk management approach used to manage the complexity and to design the mitigations measures. INTRODUCTION The metro network in the capital of Azerbaijan is rapidly growing together with its metropolitan area. The beginnings of the existing metro system started in Baku in 1967 in Soviet times. To date, only two lines (Green and Red) are in operation with a total length of 34 km, including 23 stations. The future network will be much wider: besides the construction of three completely new lines and the extension of two existing lines, the whole metro project includes the development and modernization of the existing metro sections. A consortium formed by Systra (leader), Mott MacDonald (Praha) and Saman (Korea) awarded the contract for the preliminary and detailed design of infrastructures for the extension of Baku Metro Network. This extension consists in 83 km of new lines and extension of existing lines. As part of this modernization project, the connection of the Green Line at the 28 May / Cefer Cabbarli Stations, focus of this paper, represent also it’s ""Achilles' heel"" given that the already very congested system have only one transfer station."

Jan 1, 2016

By S. P. Sandoval

In 2002 the Freeport-McMoRan Technology Center undertook research to develop a lower-cost alternative to guar for cathode smoothing in copper electrowinning. The work was conducted at the Technology Center?s SXEW Test Facility located in Morenci, Arizona. Bench-scale copper electrowinning cells were designed and implemented to screen a number of potential polymers for cathode smoothing. These included modified polysaccharide polymers that were nonionic, cationic, and anionic in nature.

Jan 1, 2010

By James H. Boettcher

In the second quarter of 1979, ASL Inc. inquired whether Crocker National Bank ("CNB") would provide $4 million in term loan financing to help ASL acquire the outstanding shares of the S&S Coal Company in West Virginia. ASL had, prior to approaching CNB, sought financing with the assistance of a financial advisor from a number of commercial banks without success. A summary of the initial terms requested by ASL is shown in Table I compared with the actual terms the transaction closed with. It is not difficult to note that the two sets of terms differ significantly. This is often the case when financing requests based on the expectations and vision of a mine developer are juxtaposed with more pragmatic requirements of a commercial bank. The "art" and fun of structuring financing plans for mining ventures (highly leveraged acquisitions or grass roots) comes in working with mine developers to arrive at a final financial structure that meets their objectives and constraints as well as those of the bank or other financial institution providing much of the financing. This article briefly describes the process we went through with ASL beginning with the terms they requested initially and ending with the ones on which the transaction was finally closed.

Jan 1, 1981

By Timothy J. Matthews, Timothy J. Batchler, Daniel J. McElhinney

The National Institute for Occupational Safety and Health’s (NIOSH) Mine Roof Simulator (MRS) at the Pittsburgh Mining Research Division was commissioned for operation in 1981. The MRS was originally designed for longwall shield research and was the only hydraulic press in the world with the capability to apply biaxial loads to these large structures. The results of this forty-year research program have contributed to improved performance and increased knowledge of longwall shields, mobile roof supports and hydraulic cylinders in the mining industry. Also, considerable research and development have been conducted to develop standing support technologies for the mining industry. The Support Technology Optimization Program (STOP) was developed to evaluate how these various technologies can impact and improve both ground control conditions and mine safety. Additional MRS research has included the performance of ventilation stopping walls including the development of a new testing protocol to evaluate the transverse loading capabilities under arching load conditions and evaluating the performance characteristics of welded wire screen as used in underground mine roof surface control. The NIOSH Mine Roof Simulator has been a reliable and valuable tool for the past forty years for the evaluation of safety structures used in mining, and this research has contributed significantly to the advancement toward safer mines. This paper will summarize those research results and provide a glimpse of planned future activities.

By C. D. Litton

When methods to prevent the occurrence of fire in underground mines fail, the next line of defense is to rapidly and reliably detect the developing fire, so that subsequent evacuation and control procedures can be safely and successfully implemented. To provide this capability requires an understanding of the operational principles of different types of fire sensors, their merits as well as their limitations, and performance characteristics of the monitoring systems that control and process sensor data; an understanding of how fires develop and the different types of fires that can occur, along with their characteristics and the hazards they present; an understanding of the impact of the mine environment and routine mining activities, not only in terms of these effects on fire sensors but also in terms of the impact of mine ventilation and mine geometry on fire growth, fire characteristics and the detection process. All of these factors are components of the technology of fire detection, and when insufficient knowledge of any of these components exists, the ability to implement adequate mine fire detection systems is diminished. Within the last decade, significant advances have been made in fire detection technology applicable to underground mines. These advances include not only the development of improved sensors and better monitoring systems, but also an expanded understanding of how to deploy sensors, set sensor alert/alarm levels, account for ventilation effects, etc. In addition, there has been an increase in our knowledge of the types of fires that occur, the types of combustibles involved, characteristic times for fire growth and development, the levels of heat, smoke and gas that are produced and the hazards that result. It is the intent of this paper to provide not an overview of current mine fire detection technology and, also, to present data obtained for some smoke sensors that have potential for use in underground mines. The paper will also discuss the data, information and resources that are currently available and seek to identify those areas most in need of further research and development.

Jan 1, 2011