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By K. J. Miller

Electrophoretic mobility measurements of coal and pyrite particles in distilled water revealed a difference between the migration speeds of the two materials toward the anode in a dc electric field. This information led to the development of a laboratory electrophoresis column for separating fine pyrite from coal by utilizing the electrokinetic and the specific gravity differences between coal and pyrite. The study demonstrated on a laboratory scale that pyrite and other impurities can be separated from fine coal by electrophoresis using a stage separation technique. In a cost analysis, electrical power for electrophoresis was extrapolated to about $1 per ton of clean coal product. But, since the only successful tests ever made were in the laboratory with prewashed samples of minus 100-plus 325-mesh coal in distilled water, the cost figure derived is not representative of conditions prevalent in commercial coal cleaning operations. True conditions would reflect costs many times as great. In the course of the work, several scale-up techniques were considered but their feasibility became academic in view of the physical and economic problems associated with electrophoretic separation of pyrite from coal. Although the process and apparatus were finally deemed impractical for commercial coal preparation, the electrophoresis column may have some application as a laboratory device.

Jan 1, 1974

By B. C. Haimson

The Committee on Rapid Excavation of the National Research Council has recognized in its 1968 report the need for "improvement of rock-mechanics techniques for measuring subsurface stress field in deep boreholes and for determining stress distribution in walls of underground excavations". The technique recommended in this paper as being most suitable for both deep hole and tunnel wall stress determination is Hydraulic Fracturing. Using this method stresses are calculated directly from the fluid pressures necessary to initiate and extend a fracture away from a borehole. Stress determination by hydraulic fracturing is rather insensitive to inhomogeneity or anisotropy, is not limited in depth except by the length of the hole, requires simple equipment which is commercially available, and can be carried out by unskilled personnel. The method has been worked out theoretically and extensively tested and verified in the laboratory. A number of field tests in deep holes ranging from 300 to 6300 ft have yielded surprisingly good results. Preliminary underground tests have been very encouraging and most recent measurements in a tunnel complex at the Nevada Test Site yielded stresses that were both consistent and reasonable when compared with the expected directionsand magnitudes. It is recommended that hydraulic fracturing be considered as a method of in-situ stress measurement both in the pre-excavation stage of design and during tunneling.

Jan 1, 1974

By Peter N. Blakey, Jean-Paul Paquette, Barton A. Thomson

"FROM THE BEGINNING OF THE PIT, it was known that the surface mining method had a projected life of about ten years, and that the ore extended to depths recoverable only by underground mining. When serious consideration was given to underground mining in 1968, it was realized that tremendous advantages could be gained by starting the underground mine as early as• poss1ble. These included: 1. The availability of underground ore for grade control, which would become more difficult as the pit deepened. 2. The need to develop new systems, equipment and skills to take full advantage of the technological revolution in underground mining. 3. Early knowledge of rock behaviour through trial mining on a small scale prior to finalizing plans for major blocks. In addition, the pit would be available to guarantee the mill supply if problems were encountered. 4. With sufficient time and early mining experience a much better job could be done on all mine planning. Because ample reserves of economic underground ore were virtually assured, the desired underground mining capability became a function of two restraints: first, the time required to excavate and construct the permanent headframe, shaft and ore-handling facilities necessary to handle large volumes of stope ore; second, the time for lateral and stope development on at least one level which would normally follow shaft sinking. The decision made was to move immediately on the permanent hoisting installations and at the same time embark on the planned ramp from surface, which would allow much stope preparation to be completed prior to .bringing the shaft on stream. Both projects were placed on an urgent basis early in 196S' and the following decisions made shortly thereafter."

Jan 1, 1974

By Russell C. Drew

The United States has long been recognized for its ability to marshall the many tools of its scientists and engineers to meet national threats or crises. Two major World Wars, the Dust Bowl, the Soviet Missile threat, Sputnik, and more recently the Energy Crisis have stimulated military weapons development, massive land reclamation and water management programs, NASA, and the Space Program, Project Independence, and soon a new agency, the Energy Research and Development Administration. While our record of successful responses to these major national concerns lends support to the expectation that we will succeed in dealing with the current energy problem and potential future crises as well, the crisis mode of response is becoming increasingly wasteful of funds and human and natural resources. This waste, while always of a concern, is a more important factor than previously because of the accelerating pace at which the world has been shrinking, relatively, in comparison to its human population and that population's increasing demand for resources, both renewable and nonrenewable. If present growth patterns continue, in the year 2000 there will be two people to feed, clothe, house, and satisfy for every one person that existed in 1970. On a finite planet, with finite land areas, limited resources, and only partial understanding of the means by which future problems can be addressed, one of the major threats to mankind will be scarcity and one of our major challenges will be better management of our resources. The challenge will be to guide Federal investments in R&D that are of sufficient magnitude and in the proper

Jan 1, 1974

By J. R. Pennington

The town of Green River, Wyoming, is located along the Green River on an arid plateau at a elevation of 6,300 feet. Green River has become the center of a booming soda ash industry. The rapid development of coal, oil, and gas resources, coupled with the soda ash boom, have created growth pains for the area. Green River and Rock Springs have experienced a 20-25% population increase in 1973 alone. However, public officials, business leaders, and local citizens are taking positive steps to ease the problems relating to housing, schools, medical services, and recreational facilities. What Is Soda Ash? Soda ash is one of the most widely used chemicals in the world. It is an important raw material in the manufacture of glass, paper, soap, petroleum products, metals, chemicals, pharmaceuticals, plastics, and a host of other items essential to every day living. In ancient times, soda ash was obtained from water solutions of various desert earths. Later, it was produced by leaching the ashes of wood and seaweed. For the past 100 years, it has been manufactured by the ammonia-soda process, which employs large quantities of salt, limestone, and coal as raw materials.

Jan 1, 1974

By Kenneth R. Ware

I INTRODUCTION The Washington Metropolitan Area Transit Authorities (WMATA) rapid transit system (METRO), currently under construction, will have a total length of 98 miles. Forty-eight of these miles are underground and require either open cut excavations or tunnels. Despite stringent construction controls, it is inevitable that some ground settlement will occur adjacent to the deep open cut earth excavations and large diameter earth tunnels. It is therefore essential to underpin nearby important structures to prevent excessive differential settlements and Fig. 1 presents the METRO criteria for this underpinning. This paper describes the underpinning methods currently used on METRO and evaluates the effectiveness of each method. II DESCRIPTION OF SUBSURFACE STRATA The foundation materials in the Washington, D.C. area are extremely variable. Fig. 2 presents an idealized profile showing typical subsurface strata. The engineering properties of each stratum have been determined by extensive exploration and testing programs. Fill: Washington, D.C. fills consist of every variety of soil and rubble. They are not important to this study because no underpinning is founded on fill material. Terrace Deposits: Formed in outwash plains during the glacier period, these deposits are composed of random layers of either sand 1 The writings and opinions expressed herein are solely those of the author and do not necessarily reflect those of WMATA.

Jan 1, 1974

By R. V. Ramani, P. M. T. White, D. Sutton

This report was prepared by The Pennsylvania State University under USBM Contract No. G0111808. The contract was initiated under the Coal Mine Health and Safety Program. It was administered under the technical direction of DMSE, with Mr. G. R. Schottler acting as the technical project officer. Mr. J. A. Herickes was the contract administrator for the Bureau of Mines. This report is a summary of the work recently completed as part of this contract during the period June, 1971 to December, 1973. This report was submitted by the authors on March 31, 1974. The project personnel express their thanks to Dr. Jay Politzer, The Pennsylvania State University Computer Center for providing the subroutine POLITZ and function IFIND, to Dr. Ray Masters, Department of Architectural Engineering, for permission for the use of the GRID program and to Dr. Lother Weyher of Bethlehem Steel Corporation for providing coal data.

Jan 1, 1974

By Robert C. Edmiston

"Further, we search for the veins by observing the hoar-frosts, which whiten all herbage except that growing over the veins, because the veins emit a warm dry exhalation which hinders the freezing of the moisture, for which reasons such plants appear rather wet than whitened by the frost," Georgius Agricola, De Re Metallica, 1556 In view of Agricola's statement, made in 1556, the concept of using the heat released by oxidizing sulfides as an ore guide can hardly be considered a product of twentieth-century technology. In fact, thermal exploration has received relatively little attention in modern times compared to other potential field geophysical methods. There have evolved, however, two basic approaches to thermal exploration for subsurface heat sources. These are 1) the measurement of surface temperatures by infrared, thermal imagery and 2) the measurement of geothermal gradients in exploratory drill holes.

Jan 1, 1974

By Gerald Zink

The object of underground excavation--apart from mining-- is to create an opening to serve as a part of some useful structure. The value of the opening lies in its conformity to the design configuration and its stability during the planned life of the structure. The wire saw could be used to excavate openings of high value at a cost competitive with present methods. First, a discussion of present methods will be used to explain where wire sawing fits in and how it should be applied. PRESENT EXCAVATION METHODS Tunnel Boring A recent advance in tunneling technology is the use of mechanical boring machines. There are many ways that a boring machine can reduce the cost of a tunnel or increase its value. I will mention a few of the advantages that have been demonstrated in tunneling projects. A tunnel can be bored without overbreak, allowing concrete lining to be poured to the design thickness without waste. Boring creates a minimum of disturbance to the tunnel wall, preserving the natural strength of the rock and reducing the amount of support which must be installed to maintain stability. A boring machine maintains the tunnel at its full dimensions and proper shape, and it leaves no rock projecting from the wall which must be trimmed off. The use of boring machines is presently limited to openings of uniform cross section and great length. If the previously mentioned attributes of mechanical boring could be applied to excavation of a wide variety of chambers and passages, then a corresponding decrease in cost and gain in value would be possible for chambers.

Jan 1, 1974

By Ben E. Lusk

First of all let me say what a genuine pleasure it is to be here. Acapulco certainly is a beautiful change. I'm going to spend sometime talking about change, because frankly I'm astounded at the rate of change in our world today. One good example of this, reminds me that the first time I spoke before the AIME two years ago, we were at the Ramada Inn in Beckley, West Virginia. Today we're at the Princess Hotel in Acapulco, Mexico. Now that's what I call a change. Seriously though, I'm sure you've all heard it said that the most consistent thing about our society is its constant change. Five years ago, no one could have predicted the changes we experienced in the United States during the first half of the 1970's. In the past twenty-four months alone, we have seen two presidents, three vice-presidents and hundreds of administration and government personnel changes. We have stumbled from one social crisis to another, while suffering through rising inflation, major energy shortages and labor unrest that could plunge us into a full scale economic depression. In view of these constant and unpredictable changes around us, it's obvious that we must learn to deal with change and "roll with the punches" if we are to survive. A controversial book published recently, explores in detail the various aspects of change and its impact on man.

Jan 1, 1974

In February 1974 a continuous synthetic polymer dosing plant was installed at Hamersley Iron Pty. Limited's Pellet Plant at Dampier. The polymer, supplied in a liquid sus- pension, is used to improve the drying characteristics of green pellets. 'Three years of test work were involved in the development of the use of polymers. Polymer is continuously dosed to the balling spray water system at a rate determined by the flow of spray water to the discs. Problems have been experienced with handling the polymer in 44 gallon drums, the increased viscosity of the spray water, disc overloads, increased bed strength and increased "stickiness" of pellet fines.

Jan 1, 1974

By W. O. Henderson, H. W. Seaney

The sinking and grouting methods employed at the 3C and 3D ore hoisting shafts and the No. 5 service shaft are discussed. The reasons for selecting a circular section over a rectangular one and other technical aspects are reviewed.

Jan 1, 1974

By Jorge A. Benitez Muro

Within the exploration programs carried on by the Consejo de Recursos Naturales No Renovables, the one with the largest coverage (more than 75, 000 square kilometers) is the northern Coahuila Exploration Project. Due to its nature, geochemical exploration methods were selected to obtain quick results. The program included essentially, three main stages : 1. - A regional geochemical stream sediment survey. 2. - Semi-detailed studies of the anomalous areas selected in the previous stage, and 3. - Detailed exploration of the promising areas. To the date, the first two stages have been completed, and the third one is being carried on. The work was started on september 1972, and it will probably take one more year before drilling can be started, but at the end of stage three it is expected that at least 5 important targets will have been detected. The regional work was conducted by 3 field crews, but the detailed program is being done by only one.

Jan 1, 1974

By Frank E. Caropreso, William P. Badger

A hydrogen peroxide precipitate process has been adopted by Atlas Minerals for the recovery of uranium oxides from sodium chloride strip solutions. Adoption of the process was based on laboratory and plant tests comparing hydrogen peroxide with other precipitants. Plant operation has demonstrated that the hydrogen peroxide process consistently yields uranium concentrates of high purity and barrens of low uranium content. Increased U3O8 concentration in the product, reduced levels of impurities which incur penalties, and higher product density have produced economic advantages.

Jan 1, 1974

To improve the efficiency and speed of under-ground post-disaster rescue operations. The Approach: Develop a battery-powered mine-rescue vehicle designed to carry rescue crews, rescued miners, and their support equipment. How It Works: The experimental vehicle, shown below, was designed and constructed by the Mine Safety Appliances Company under contract to the Bureau of Mines. ATV Manufacturing Company and Delco Electronics were subcontractors. A rechargeable, silver-zinc battery provides power to a 3-horsepower permissible motor, the speed of which is regulated by a solid-state controller. Three wheels on each side are independently driven by a chain and mechanical trans-mission.

Jan 1, 1974

By Jose F. T. Agapito

The mining engineer must be able to predict the structural behavior of the rock around underground openings so that he can answer questions relating to safety and economics. With the present status of rock mechanics knowledge, exact predictions cannot be attained and approximate idealizations are made. As a first approximation, structural design makes use of theory, laboratory testing of rock properties, and available experience from excavations in similar rock formations. However, realistic design can usually be obtained only after in-situ observations and measurements are made. After all the information is collected, judgement and experience play a most important role in the final formulation of the design. This paper describes part of a geotechnical program which was instrumental in obtaining information for the design of large oil shale pillars. The work was carried out during 1971 and 1972 in the experimental mine of the Colony Development Operation. Colony is an oil shale venture formed between Atlantic Richfield Company, Operator, The Oil Shale Corporation, Cleveland-Cliffs Iron Company, and Sohio Petroleum Company to conduct research and development in mining and retorting of oil shale, The property is located in the southern edge of the Piceance Creek Basin in northwestern Colorado, approximately 250 miles west of Denver (Figure 1) . Mining was conducted by the room-and-pillar method in a 60-ft high portion of the Green River Formation at a depth of 600 to 850 ft, Pillar dimensions are approximately 60 ft by 60 ft. The mine site is in the eastern face of the canyon containing the Middle Fork of Parachute Creek, The distance from the mine to the side of the mountain varies from 500 to 1,200 ft, and its height above the stream floor is approximately 700 ft.

Jan 1, 1974

By R. D. Mollison

"Ecstall Mining Limited was formed to operate the Kidd Creek mine, discovered by Texasgulf Incorporated in 1961 the orebody is geologically very complex, containing rich values of zinc, copper, silver and lead. The first phase of the operation involved an open pit, railroad and concentrator complex, which was under construction in 1965 and began operations in late 1966. The open pit, with rim dimensions of 2,000 by 1,000 feet, was computer-designed and highlights excellent wall control and efficient ore extraction and grade control. The railroad was built over the worst type of muskeg country, but it has been well maintained, resulting in an uninterrupted supply of ore in the trains. The 10,000-tpd concentrator, located 17 miles from the mine, is highly instrumented and automated. It features computer control of reagents and, in addition to the copper, zinc and lead flotation circuits, has a modern gravity tin plant. The concentrator is large, because very fine grinding is required for good metallurgy and nearly 2,500 tons per day of concentrates are produced. In 1969, work was started on the underground mine to take over from the open pit; it began partial production in mid-1973. The mine is highly instrumented, has a ramp from surface, a high-production shaft, an underground gyratory crusher and an efficient orehandling system, and employs the latest mining techniques. The electrolytic zine plant, rated at 120,000 tons of slab zinc per year, started operation in April, 1972, with batch leaching and purification circuits. It has been converted to continuous leaching and is now in the process of converting to continuous purification. Further modernization and automation will be carried out in the next few years. Five service departments support the five operating departments. These are maintenance, engineering and technical services, geology, administration and employee relations. How these ten departments function and work together using the most advanced technology to produce an efficient operation is the main theme of the Ecstall Story."

Jan 1, 1974

By R. E. Jones

"Crusher sizing and application in mining operations is the selection of a crusher or a series of crushers to reduce run of mine ore to a size suitable for either autogenous or conventional grinding. It is important that the crusher or crushers be sized to operate within the range to which they have been designed. By the range to which they have been designed, we mean that the reduction ration must be held between specified limits. Reduction ration is the relationship between feed size to product size.In todays plants reduction is usually accomplished in three stages by primary, secondary and tertiary crushers.Primary crushers are either jaw or gyratory and are designed to handle run of mine feed at an open side setting of 5-1/2” to 7”. Reduction ration should not exceed 7 to 1.Jaw CrushersThe model size of a jaw crusher signifies the feed opening. A model 60 x48 jaw has a feed opening 60” wide by 48” long. The 48” is the dimension between the top of the swing jaw and the top of the stationary jaw. The 60” is the width between the two side frames. The crusher open side setting is the discharge opening at the bottom of the crushing chamber with the jaws in an open position. When corrugated jaw plates are used, the open side setting is measured from tip of one jaw plate to the valley of the opposite jaw plate. If a jaw crusher has a 6” open side setting with a 1” jaw motion, you could also say it has a 5” closed side setting."

Jan 1, 1974

By J. L. Holman

The Bureau of Mines, at its Rolla Metallurgy Research Center, has devised methods for separating and reusing the major portion of waste plastics discarded in urban and industrial refuse. Waste plastic concentrates from a local collection drive, recycling center collections, urban refuse pilot plants, and the secondary metals industry were separated into three major thermoplastic families--polyolefins, styrenes, and vinyls--based on differences in density using a Bureau-designed sink-float-elutriation hydraulic separator. Other separation methods and systems such as air classification, jigging, liquid media, screening, and electrostatics were studied. Vinyl plastics contain up to 50 percent HC1. It was found that over 90 percent of the HC1 in vinyls can be recovered as usable hydrochloric acid by pyrolysis at 350° C. The remaining pyrolysis products which had heats of combustion in excess of 12,000 Btu/lb, could become valuable as a future source of energy. A characterization study conducted on eight chopped wire insulation wastes from secondary copper and aluminum processors showed that most wastes contained 2 to 7 percent residual metal and large percentages of vinyl. The residual metal content of some of these wastes was lowered to 0.1 percent and the vinyl portion segregated using various separation techniques. The research also suggests ways in which reclaimed thermoplastics may be fabricated into useful products.

Jan 1, 1974

By D. W. Duncan, A. Bruynesteyn

An ore containing chalcopyrite was microbiologically leached in 6 ft columns at particle sizes ranging from -2 +1 ½ inches, to -3/8 + 3/16 inches. The rate of leaching increased exponentially as the particle size decreased. The controlling factor was the active leaching volume made up of the particle surface area and the depth of penetration of the bacteria and leach liquor into the particle. This volume became an increasingly larger part of the total volume as the particle size decreased. The sample under test leached poorly at larger particle sizes and it was calculated that under commercial conditions, it would produce at best a pregnant solution containing 100 mg/l (0.2 lb/ ton) of copper per 100 ft of dump height.

Jan 1, 1974