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By Carl F. Austin

The subject of strata control in mining can be approached from both static or loading concepts or from dynamic or impulsive loading concepts. The fracture process itself appears to be primarily a dynamic process as is the gross creation of fractures through the use of impact, stress wave passage or in more general terms, the use of explosives. This paper presents experimental results which indicate that the understanding of the fracture behavior of rock that has been, established in the open literature is not always appropriate. In particular, the results of this experimental program have shown very interesting differences between the formation of fractures in rock and the formation of fractures in other materials such as metals and plastics which are often used as models for rock behavior studies Fracture patterns and causes of dynamic fracturing in various rock and artificial materials are presented.

Jan 1, 1965

By Shingo Morimoto, Toru Sasaki, Masato Shinji

"1. INTRODUCTIONTunnel face stability is one of the most important consideration in New Austrian Tunneling Method. In general, if all of the material properties of ground can be obtained through the field investigations, the tunnel face behavior can be predicted using numerical simulation prior to tunnel construction. However, estimating the safety of a tunnel face is difficult, especially in cases where the ground is very weak such as in an urban area.In this study, numerical analyses of tunnel excavation in very weak ground conditions, such as a low cohesion and low internal friction angle, were carried out. The relationship between the average shear strain distribution on the tunnel face and the overburden was analyzed. This relationship estimates the shear strain of the tunnel face relative to the critical shear strain obtained by the ground properties. The critical shear strain was defined as an allowable value for the maximum shear strain. We proposed the allowable overburden as tunnel face stability index (TFI) that satisfies the critical shear strain criterion of ground. Finally, a design chart of the allowable overburden for various cohesion values and friction angles of ground was created. This chart is useful in the preliminary tunnel design stage to judge the necessity of additional counter measures against normal tunnel support design.2. WEAK GROUND MODELING AND ANALYSIS PROCEDURE2.1 Setting material propertiesWith reference to a past study1), the material properties were adopted on the basis of material properties in the standard worst rock classification case called “DII”2) for standard support pattern of weak ground in Japan. The typical material properties for “DII” are listed in Table 1. In addition, Fig.1 shows the distribution of the representative weak ground according to cohesion and internal friction angle. When the internal friction angle is relatively high and the cohesion is weak, the ground is categorized as sandy ground. Furthermore, when the internal friction angle is low and the cohesion is strong, the ground is categorized as clayey ground."

Jan 1, 2016

By J. Georgi

A number of infrastructure projects are on progress all around Greece at the moment. The common propose of these a project is the promotion of quality in: Design, construction and maintenance stages. They also comply with environmental management, which is, a method of organizing and implementing environmental protection measures. The paper includes by special reference on two important modern transport infrastructure projects for the development of Greece and its communication with Europe and the Balkans. Their landscape types and natural vegetation, local climate, geological conditions, altitudes, aspects and soil types vary As a result, upland landscapes in particular, are endangered. Due to the complex of nature of this environment, the development and the landscape design of the projects is a high challenging task. Wherever the nature of the projects requires intervention to the environment, they intend to follow the direct restoration of landscape and method for ecological balance. The implementation of landscape design of infrastructure projects, aims at restoring the landscape affected by construction works, incorporating transport works into the landscape, emphasizing on areas of particular interest (e.g. archaeological sites), while at the same time observing the principles of an efficient operation and safe use of the alignment. Landscape design provides, among others for the protection of slopes against surface erosion and the reinforcement of their stability, the improvement of road functionality, the aesthetic improvement of the landscape, adaptation of the road landscape to the greater environment, visual guidance of the user, screening of lights of the vehicles moving in the opposite direction, the protection against wind etc. The landscape design strategy and landscape applications are specified by special landscape guidelines and specifications that can be considered as part of the sustainable development of a alignment creating a high a esthetic scenery, ensuring the security of transportation and the environmental protection.

Jan 1, 2002

By S. A. Allison, N. P. Finkelstein

After a brief consideration of the properties of zinc sulfide minerals, their flotation characteristics, and their reactions with thiol collectors, the literature on the activation of the minerals by cupric ion, their deactivation by cyanide, and their depression is reviewed in detail. The distinction between deactivation and depression is stressed. The contradictions in the published results and theories are discussed and attempts are made to resolve them. It is concluded that, whereas all aspects of the subject require further investigation, the study of depression is most likely to yield benefits in practice.

Jan 1, 1976

By J. C. Motz

The advantages of producing a fine mill feed have been recognized for many years. The extent to which fine crushing can be carried out will vary and depends on the ore characteristics, plant and crusher design. Unfortunately, the ore characteristics are generally beyond our control, so the concentration of effort lies primarily on the plant arrangement, equipment design and operation Where fine crushing should stop and grinding begin is controversial and is influenced greatly by personal opinions and experiences. Often, this break point will be different if consideration is being given to a new plant in comparison to a modest expansion. Most new plant designs employ the largest and most efficient equipment. The modification of existing plants becomes more complex because of the space requirements and the related equipment already in operation. Fine crushing is, of course, a relative term. Obtaining a final crusher product of minus 3/4" is commonplace today and can occasionally be obtained in an open circuit final crushing stage.

Jan 1, 1980

By K. L. Bickel

Catalyzed diesel particulate filters (CDPFs) are used for reducing diesel particulate matter (DPM) concentrations in underground mines. The U.S. Bureau of Mines is conducting research on how catalyzed diesel particulate filters perform. Two CDPFs, with two different catalysts, are used on vehicles in two mines. The CDPFs are periodically removed from service and evaluated in the laboratory to determine their DPM collection efficiency, regeneration temperature, and effects on gaseous hydrocarbon (HC) and carbon monoxide (CO) emissions. This report summarizes the results of the laboratory evaluation, and the mines' experience with the CDPFs. Both CDPFs have operated over 2,000 h. One was evaluated after 1,646 h; its collection efficiency at one operating condition was 87.3 pct. After 2,135 h of operation it was removed from service because it was damaged. The second CDPF continues to be used after 2,328 h of service. The laboratory evaluation indicated its collection efficiency decreased after 1,584 h of use and its regeneration temperature increased from 405' C to 420' C. The mines' experiences with the two CDPFs varied. While being used on mine vehicles, both CDPFs became plugged with DPM on a number of occasions because of insufficient regeneration. CDPFs are capable of lowering DPM concentrations in diesel exhaust. They can also lower emissions of CO and HC, depending on the type of catalyst used. In this study, the performance of the CDPFs changed with use. Recommendations are given in this report for proper use of CDPFs in mines.

Jan 1, 1994

By T. A. Griffin

Gentlemen: The subject of this paper is: ADVANCED APPLICATIONS OF BUCKET WHEEL EXCAVATORS AND RECLAIMERS. Against an urgent world wide energy crisis, the role of bucket wheel excavators and reclaimers in the surface mining of fossil fuels and other ores has been raised to new prominence. This paper will review the reasons for the expanded application of bucket wheel technology, its unique contributions, and other factors relative to volume, cost, versatility, and efficiency. Today, surface mining is faced with the twin challenge of (1), accelerating the rate of removal of massive quantities of overburden and ore, and (2), replacing comparable high volumes of overburden back into the mined-out portion of the pit. Optimum quantitites for - a single electrical power plant now range from 5 to 15 million tons of coal per year. The use of bucket wheels offers the best method for meeting this challenge at lowest possible cost. For example, an advanced application that also satisfies environmental concerns involves the simultaneous functioning of two bucket wheel excavators during surface mining operations. Working at spaced intervals and different levels in conjunction with a transfer conveyor and stacker, one excavator removes the ore while the other one transfers overburden to a stacker that replaces it back into the open pit. The result of this continuously operating cycle is: (1) removal of ore and replacement of overburden back into the pit in massive quantities, (2) at accelerated volume and extreme low cost that cannot be matched by conventional loading machines of any size, and (3) fulfills a basic environmental requirement which is to

Jan 1, 1974

By Eugene C. Robertson

The exchange of heat from wall rock to ventilating air was studied in a cross-cut driven through fresh rock on the 4600 level of the Kelley Mine, Six- teen thermocouple probes, 10 inches long, twenty-three probes, 7 feet long, and five probes, 50 feet long, were emplaced in the walls soon after blasting and wall -rock temperatures were monitored intermittently over a two-year period to determine heat loss from the wall rock. Temperatures, humidity, and velocity measurements were made of the air at the same times to determine heat gain. An important but less well-defined variable was the heat transfer by water entering the crosscut from fractures and leaving in the ditch. The balance of heat in and heat out at each probe station is within an acceptable range. Theoretical and empirical models for heat flux into a cylindrical opening fit the data reasonably well, also.

Jan 1, 1970

By Meili Zhu, Qingpu Shi

High temperature, methane, dust and other disasters are getting more serious with mining depth getting deeper and the development of mechanization in underground mines. An application of a descensional ventilation to a coalface is one of the effective measures to solve the above problemes. The descensional ventilation is an venttilation that an airflow in a coalface wouuld downflow along an inclination of a coalface and the direction of the airflow is the same as coalflow. Since 1960's, the descensional ventilation has been applied to 171 coalfaces in 46 coal mines of 23 coal mine administrations in China, such as Pingdingshan , Zhongliangshan, Pubai, Huangshi coal mine administrations. Among the 171 coalfaces, there were 104 coalfaces taking 60.8% in gently inclined seam. The coalfaces in inclined seam and steep seam were individually taking 18.7 % and 20.5 %. There were 77 coalfaces taking 45 % of the total in low gassy coal mines and coal and methane outburst mine were individually taking 17% and 38%. There were 141 coalfaces taking 82.5% of the total in potential danger of dust explosion. There were 125 coalfaces taking 73.1% of the total in potential danger of spontaneous combustion. Therefore, the descensional ventilation can be used in coalfaces under different conditions in China. The practice at home and abroad shown that the application of the descensional ventilation to coalfaces has obvious results in dust control, temperature control, preventing methane accumulation at top corner angle and control of spontaneous combustion in goaf. To more safely and reliably apply the descensional ventilation to coalface and to provide a way for the development of mine ventilation technology in China, the paper will have discussions on the following problems: METHANE EMISSION AND DISTRIBUTION AT COALFACE WITH DESCENSIONAL VENTILATION Methane emission in a coalface with a descensional ventilation is an argued issue for many years. Base on the coal practice, special similar model tests and researches in China, the followings are our main comments. The Descensional Ventilation can Reduce the Methane, Accumulation at the Top Corner Angle. The measurements in six coalfaces with the downward airflow in Qinhemen Mine, Fuxin Coal Mine Administrations shown that the methane concentration at the top corner angle is often up to l% when the coalface has the upward, airflow. The max. methane concentration at the top corner angle is about 0.49 to 0.7% when the coalface has the descensional ventilation. Therefore, with the descensional ventilation, it basically solved the overlimited gas concentration at the top corner angle which is a potential danger to coal production. Because the direction of upfloating gas is opposite to the direction, of the descensional airflow, the descensional ventilation; could increase a turbulent flow mixing capacity of the methan gas and air, and reduce a possibility of methane; accumulation. Due to an air leakage in goat when the coalface with the descensional ventilation lower than an air leakage in goat when the coalface with the, ascensional ventilation, a less methane quantity will release from goat at the descensional ventialtion. It should be pointed out that due to a higher air leakage at ascensional ventilation and the direction of the air; leakage same to the direction of the natural upfloating methane in goaf, those will cause a large methane; accumulation at the top of the goaf and easy bring about, methane accumulation and overlimited methane concentration at the top corner angle with an ventilation vortexflow at the top corner angle. On the other hand, because the direction of the upfloation force function is upward, the descentional ventilation could minimize as possibility of methane accumulation at top corner angle in coal with the descensional ventiltion.

Jan 1, 1991

By Michael J. Pratko

The bulk handling industries have long been plagued with problems in their attempt to obtain one of their major goals - the maximum efficiency for which a bulk handling flow system was designed. Mentor Dynamics Ltd. is an international firm with offices in Canada, Japan, and the United States. Mentor Dynamics Ltd. is in the business of solving the "why not" of a system and engineers the solution for the problem. Studies of the varied difficulties encountered with bulk flow systems indicate that 90% of all flow problems fall into one or more of the following categories: abrasion, impact, sticking, and/or inadequate design. These problems can occur with a myriad of bulk solids: coal, gypsum, aragonite, phosphate, fly ash, ore. Solutions to the problems are as varied as the problems. The proper lining material, ceramic, urethane, rubber, and/ or ultra high molecular weight polyethylene, must be coupled with the correct fastening system, annular ring and 'F' cap, weld washer, button head fastener, weld studs and/or nuts and bolts.

Jan 1, 1982

By Douglas F. Crickmer

Pocahontas Land Corporation, a wholly-owned subsidiary of Norfolk and western Railway Company, owns a 100,000-acre block of coal lands in Martin, Johnson, Pike, Floyd and Lawrence Counties, Kentucky. These holdings were largely acquired in three major purchases between the years 1942 and 1959. The area is undeveloped and constitutes a part of the coal reserve for future mining. This block, which is principally in Martin County, lies in a triangle formed by the Levisa and Tug Forks of Big Sandy River on the sides with Dewey Dam at its base and the Town of Louisa at the apex. The topography'is typical of eastern Kentucky and consists of steep hills rising from 500 to 800 feet above creek level. There is little level ground in the area. As a matter of fact, some roads are on the creek bottoms with what little bottom land is available in the hollows being utilized for small-scale farming. The steep hills are marked by three separate massive sandstone formations which form cliffs ranging from 40 to 100 feet in height.

Jan 1, 1964

By R. L. Bleifuss

The object of this study was to evaluate the oxidized taconites of the western Mesabi iron range and to establish a correlation between the various basic taconite types and their concentratability. This study was made at the Mines Experiment Station of the University of Minnesota under the sponsorship of the Great Northern Railway Company. The initial work included a study of the original mineralogical and stratigraphic facies of the fresh taconite and traced the oxidation and leaching patterns developed during the conversion of this material to oxidized taconite. Subsequent studies have extended this work to include the semi- taconites and also the wash and heavy media ore types widely developed in the area. Each basic, original mineralogical facies or taconite type produces during alteration an equivalent secondary oxidized facies which has a unique mineralogical composition and texture. These control the concentratability of the oxidized taconites. Actually the influence of the original mineralogical composition of the iron formation extends even further and determines whether the most likely product of oxidation and leaching will be a wash ore or a heavy media ore and even to the direct shipping ores where the ratio of hematite to goethite is largely determined by the original taconite type.

Jan 1, 1964

By R. G. Dalbke

An increasing number of water pollution control systems are certain to be installed by many industries in the future because of new federal, state, and local government regulations, and because of the rising general concern about the deterioration of our water resources. Extensive engineering, some of it based on methods not yet developed, will be required if these new systems are to provide optimum pollution control. Capital cost, operating cost, and present and future regulatory requirements will be primary factors to be considered by engineers. This paper outlines procedures and gives examples of advanced engineering practices that have achieved efficient pollution control systems in the steel and nonferrous industries.

Jan 1, 1968

By V. Svalbonas

With the occurrences of serious mill structural failures on both ball and primary mills, the mining industry has entered the era of detailed fabrication specifications. Such specifications, however, have been developed as individual entities, often by people not related to the mill design function. Therefore, there has been no effort to relate mill failure or safety to the existence or elimination of specific fabrication flaws; that is, no cause-effect failure relationships have been developed. The omission of this step produces a specification which can be termed uneconomical at best. The present paper attempts to fill this void, by reviewing methods for design consideration of flawed structures, and describing experimental tests used to tie such data to a meaningful quality assurance program in fabrication.

Jan 1, 1985

By Hugh McMillan

To protect the water supply for the Metropolitan Chicago area, the Illinois legislature, in 1889, created the Metropolitan Sanitary District of Greater Chicago. To insure the quality of the water supply, the Sanitary District collected and diverted the wastes of 750,000 people away from Lake Michigan. Today, the Sanitary District collects and treats the wastes from a domestic population of 5 ¼ million people and an industrial waste load equivalent to 4 ¼ million people. The District serves Chicago and 120 other cities and suburbs in an 858 square mile area. An average of 1300 million gallons of wastewater is treated each day, producing as a by- product about 700 dry tons of solids which contains more than $10,000 worth of plant nutrients when equated to the value of commercial fertilizer purchased in the retail market. The Sanitary District considered several alternatives to past methods for disposing of these solids, and chose land application as a technique to utilize the solids produced by the wastewater treatment process in a beneficial manner.

Jan 1, 1973

By Bruce C. Trent

In order to effectively model subsidence caused by underground openings, a two-dimensional computer code has been developed which couples near- and far-field response. The near-field is simulated by a discrete element block code and a finite difference code represents the continuum region in the far-field. The explicit equations allow rapid and inexpensive solutions to geometries which may lead to subsidence. Two sample problems are presented which illustrate the important features of the code.

Jan 1, 1979

By William L. Rose

Production scheduling is an integral part of intermediate- and long-range open-pit mine planning, affecting equipment selection, manpower requirements and project economics. The development of mining phases, or pushbacks, is discussed in conjunction with generating the best spatial extraction sequence. An approach to scheduling production from these mining phases is then described. Using computers and a production scheduling algorithm, the impact of cutoff grade and advanced stripping policies can be evaluated through sensitivity studies to maximize the return on project investments.

Jan 1, 1985

By D. M. Stephens

Feeder-Breakers were an unknown but much needed piece of machinery when U. S. underground coal mines started converting to more efficient belt haulage of the R.O.M. coal as compared to conventional methods that the 1950's offered. These simple electromechanical machines offered efficiencies in three areas: (1) they contained a surge hopper that allowed a "load' of coal to be dumped without delay; (2) this material was fed horizontally by a drag chain conveyor into a rotating carbide pick breaker that broke all oversize material into a beltable size, and (3) it fed this broken material onto the belt conveyor at a rate conducive to its design. Since its introduction, the Feeder-Breaker has evolved from that first low capacity, low breaking force machine to today's model capable of breaking materials up to 5 MOHS in hardness and having throughput capabilities exceeding 3,000 TPH with availability in the 90 percentiles.

Jan 1, 1985

By Mr. Peter J. Huck

Recent research has developed procedural control and geophysical test methods that can greatly enhance quality control in rock grouting. Confidence that design objectives will be made In construction requires that grout monitoring efforts be carefully designed and integrated into the overall project. Parameters that should be monitored are identified and documentation/review procedures that permit effective evaluation of the grouting effort are discussed.

Jan 1, 1980

By H. G. Fleshman

Thousands of years ago, Chinese water well drillers developed a technique for punching holes in the ground by lifting massive metal bits and letting them fall against the rock. With diligence, they could pound away about 2 feet a day. The Chinese drillers pounded holes in the ground this way for almost 2000 years. In the 1860's, French water well drillers developed a perforated bit moistened by fluids pumped into the hole through a hollow rod. The fluids carried the cuttings from the hole and spared the Frenchmen the task of bailing them out by hand.

Jan 1, 1986