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By James R. Evans

Orange County, adjacent to the populous and industrialized Los Angeles area, is the fastest growing county in California and is second only to Los Angeles County in total population (figure 1). In addition to an equable climate and a burgeoning economy, there is room in Orange County for growth and expansion. Growth over the past decade has resulted in rapid development of industrial tracts, housing areas, and shopping and commercial centers, mostly in former agricultural areas. The value of new building in 1972 was a record amount-over I billion dollars (figure 2). Problems relating to the proper direction of growth are the concern of both government and the private sector. The intelligent and efficient use of areas to be developed requires planning for the conservation and protection of the County's natural beauty and for the orderly development of natural resources. The availability of sand and gravel, which is used in many phases of construction, will be a major controlling factor in the future of the County.

Jan 1, 1974

By James S. Redpath

INTRODUCTION Background Early in 1972 our firm was asked by Cominco, managers of Arvik Mines Limited, to carry out an underground exploration programme referred to as the "Polaris Project" on a zinc-lead deposit in Canada's High Arctic. We had carried out numerous projects in the far north but this was to be the first long decline driven in perma-frost. Despite the short notice it was possible to meet the quickly approaching summer shipping deadline. We were able to do this by drawing heavily on our own and Cominco's background in Arctic operations. The project was an excellent example of owner-contractor co-operation and this spirit was responsible for the success of the project. Unusual Aspects There were a number of unusual aspects of the Polaris Project which are discussed in this paper. The extremely remote location, the short shipping season, and the fact that the work was carried out in permanently frozen ground, when combined with the lack of handy fresh water and a very severe climate, make it unique in many respects. Despite these handicaps, a record was set during the driving of the exploration decline.

Jan 1, 1974

By Chi-shing Wang

The U.S. Bureau of Mines has been developing the mechanical roof pulling technique as a method for evaluating the effectiveness and the comparative advantages and disadvantages of various roof bolting systems, based on the characteristic responses of bolted nine roofs to a prescribed external loading system. Preliminary experiments were conducted in the Bureau's Safety Research Coal Mine using a 12-foot and a 16-foot-span test rig. The experiments have proved the capability of the test rigs and suggested the viability of the test method. This paper summarizes the test concept and the experimental results.

Jan 1, 1974

By Irving Hoch

INTRODUCTION The demand for tunnelling can be related to urban population size and density; often, tunnelling occurs when a certain city size and density threshold is reached, and increases thereafter as a function of those population characteristics. Subways for rail mass transit are the most notable example, of course, but tunnels for water supply and perhaps for sewerage can also be related to size and density. As cities grow large they sometimes outgrow their local water supply and have to import water from distant places via tunnels; witness New York City, Los Angeles and San Francisco. And it has been suggested that Chicago use deep tunnels for storm water storage because tertiary treatment to meet water quality standards will require treating storm water runoff.(1) Other uses of underground space also increase with urban density, e.g., underground parking, concourses and shopping centers such as Rockefeller Center in New York City and the Place Ville-Marie in Montreal. These examples can be viewed as illustrative of the central point of urban land economics. As the number of people locating in a place increase, they bid up land values and make the more intensive use of land economic, with land defined to embrace the space both above and below the surface. Hence, we are led to think about the city, and of urban land use, in three dimensions. Now, if we accept the relation of underground space use to urban size and density, recent demographic trends seem anything but hopeful for future tunnelling demand: urban density is declining, population growth is slowing down generally, and there

Jan 1, 1974

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

3.1 Criteria for Selection A coal deposit has the following major characteristics: i) wide distribution as a flat-lying, thin, bedded deposit ii) stable nature of its major components and ranking characteristics such as carbon, heat content, volatile components, specific gravity, etc. iii) number of constituents and characteristics which under present regulations limit usage, such as content of ash, sulphur, sodium, etc. iv) effect of characteristics of over- and under- lying host rocks including porosity and permeability, lithology and general geology v) low value, high bulk nature. Because of the relative stability of its major components and its low unit price, coal does not require the same attention to detail as do the metal deposits. However, new regulations combined with social pressures make it imperative that more accurate information be made available concerning factors which affect the quality of coal and which may have an adverse effect on the environment when the coal is mined or burnt. The method selected for the evaluation of a coal deposit must, therefore, be flexible and sensitive enough to be used to interpolate stable parameters whose general distribution character-

Jan 1, 1974

By William A. Cline

The iron mine and beneficiation facilities of Marcona Mining Company are located on the coast of south central Peru. The facilities include an open pit mine, crushing, concentrator containing grinding, magnetic-separation and flotation facilities, pelletizing plants and a completely self sufficient infrastructure. Total production capability is about 10,000,000 DLTPY, of which almost 6,000,000 DLT result from the fine-grind magnetic concentrate. Over 1,500,000 DLT of fine-grind concentrate is obtained from processing high-pyrrhotite ore. Although the orebody contains quantities of oxidized primary ore and transitional ores (mixed magnetite and hematite), the principal ore is predominantly a coarsely crystalline to fine grained massive magnetite.(l-3) In the primary ore the major impurities found are silicates and the iron sulfides- pyrite and pyrrhotite. Sulfur levels typically average about three percent although levels of five percent are not unusual and some ores contain up to ten percent total sulfides. In general the silicates and pyrite are readily rejected from finely ground primary ore by magnetic separation and very basic froth flotation processes. The high iron, low sulfur concentrate produced is particularly suitable for production of high quality oxide pellets. However, pyrrhotite is not removed from the magnetite matrix by either of' these simple beneficiation methods.

Jan 1, 1974

By Parer W. R

During the last fifteen years there has been a marked change in the demand and supply patterns of coking coal. The world demand, predominantly Japan, has increased from 23 million tonnes of world export/import coal in 1960 to an expected total of at least 100 million tonnes by 1975. In the last ten years Australia has been the main beneficiary in the growth of the export coal trade. This has been brought about by its proximity to Japan and its large econ- omically mineable reserves of coking coal. A feature of the recent coal development in Australia has been the requirement of companies in new areas to provide massive capital for infrastructure costs. The ability of the Australian coal industry to retain a large share of the world export market depends to a large extent on reasonable costs to transport coal from mine to the market place. In some areas of Australia this means that railway lines, loading and unloading facilities, and ports will have to be up-dated at substantial costs. On the long haul to Europe the recent increases in the prices of bunker fuel have made the price of coal less competitive when compared with sources

Jan 1, 1974

By Ronald D. Hill, Elmore C. Grim

Coal-haul and mine access roads are defined as any road constructed, improved or used by the operator (except public roads) that ends at the pit or bench. These roads constitute approximately 10% of the total area directly disturbed by the surface mining operation(l). In some cases, the land disturbed by haul roads exceeds the area included in the mining operation. Studies (2 and 3) of the U. S. Forest Service in eastern Kentucky show that typical contour mining roads exhibit poor alignment, excessive grades, insufficient strength and durability, and poor drainage. Mine roads in other Appalachian- States, particularly where contour mining is practiced, appear much the same as those in Kentucky. Access roads(4) were also found to be a large source of sediment. It is possible that of the sediment that finds its way into the streams as much (or even more) originates from the haul roads as from the mining operation. Most roads are built as cheaply as possible, and good road-building design and practice are ignored. Maintenance schedules are generally inadequate, and upon completion of mining, haul roads are usually abandoned, with little or no attempt made to bed them down(5 ) . Such roads deteriorate very rapidly (Figure 68). Area mining, which is practiced in flat to gently rolling terrain, presents fewer haul road related environmental problems. These roads through necessity are generally well engineered because of the heavy equipment using them, such as 240 ton (217 metric ton) haul trucks. They must have wide beds, good alignment, and adequate drainage to permit coal haulers to run at top speed during all seasons of the year. Excessive dust can be a public nuisance and a driving hazard, and it is hard on equipment. Calcium chloride and sodium chloride have proven to be effective materials for controlling dust. Two applications during the summer when the ground surface is moist at the rate of 1/2 pound per square yard (.26 kilograms per square meter) (3 1 have been suggested. Th4 most common procedure is to keep the roads wet by using water trucks. Sediment that reaches the streams can be traced to one or more of the following five basic phases of haul-road life:

Jan 1, 1974

By Robert M. Cox

The objective of this study was to determine if significant relationships exist between coal mine roof stability and the time roof is left unsupported. Additional factors such as geology, opening geometry, and mining methods were also studied: to determine their relative influence on mine roof stability. The results of the study indicate that geologic factors such as shear zones (either joints or faults) and changes in roof rock lithology were the principal factors governing mine roof stability. The time lapse factor appeared to be of critical importance when poor mine roof conditions are encountered. The study pointed up the need for improved and permissible rock mechanics instrumentation for use in coal mine investigations.

Jan 1, 1974

By S. L. Crouch

An important class of mining problems involves excavations in planar seam or vein-type deposits. In many instances it can be assumed that the seam is at 'infinite' depth in a homogeneous, isotropic or transversely isotropic, linearly elastic rock mss, and that the normal to the plane of the seam is a principal stress direction. Rational planning of excavations in such deposits requires a knowledge; of the stresses and displacements induced by complicated, irregular excavation geometries in the plane of the seam. This problem previously has been solved either numerically or by means of an electrical resistance network analog. Both of these methods effectively simulate the mined portions of the seam as a dislocation in an otherwise continuous mass, and determine the complete solution in terms of the stresses and displacements at the seam. In both cases, the plane of the seam is divided into a number - say, M x N - of squares, and the solution to the problem is determined in terms of the solution to an M x N system of equations. The numerical approach requires that these equations be solved explicitly, while the analog; solves them instantaneously with current analogous to stress and voltage to displacement. A purely numerical solution of practical problems can require a substantial amount of computer time, particularly in situations that demand some sort of sequential analysis, either due to successive mining or to nonlinear behavior of the seam material. This report describes a combined analog-digital computer system for solving problems that are impractical when either device is used separately. The digital computer and the analog are interfaced so that the digital computer can receive information from the analog via a switching matrix and an analog to digital converter, and can activate points of the analog via another switching matrix and a set of digital to analog converters. The resulting hybrid system can be used to simulate arbitrary "stress-strain" characteristics for any portion of the seam by an iterative procedure similar to the initial strain method used in nonlinear finite element analysis. Thus, the hybrid system combines the speed of analog computation with the decision-making capability of the digital computer: the analog instantaneously solves the set of equations, and the digital computer decides how the initial strains must be altered for the solution to be compatible with the prescribed "stress-strain" characteristics for the seam material. The hybrid computer system has many implications for rational planning of underground excavations, since it allows practically any type of inelastic seam behavior or artificial support characteristics to be simulated. Inelastic seam behavior, for example, might be due to either rock failure or to time-dependent deformation.

Jan 1, 1974

By Wilson Blake

This report presents the results of a 7-year Bureau of Mines program to review, revise, and make an effective engineering tool of the microseismic method of determining the stability of rock structures. The program consisted of developing new microseismic equipment and data analysis techniques and extensive field investigations to demonstrate the effectiveness and potential of the broad-band microseismic method. The guidelines for choosing the components of a microseismic system are presented along with approximate cost figures. Different microseismic systems are discussed, including completely automated systems. Procedures for conducting microseismic investigations and analyzing microseismic data are discussed in detail. Field situations which show the full value of the microseismic technique as an engineering tool are described.

Jan 1, 1974

By E. L. Michaels

Laboratory and pilot scale tests have been made to deter- mine the utility of heavy media separation, particularly a cone type separator, as a means of recovering aluminum from shredded municipal solid waste. The effect of the method of shredding on the behavior of aluminum in a heavy media system was deter- mined. Two-stage pilot scale heavy media separations were made with size fractions of shredded refuse. Recoveries of aluminum, as well as other components of the refuse, were measured and medium losses were determined. The experimental results indicate that with certain reservations a heavy media cone system can be utilized for aluminum separation and recovery from shredded and air classified municipal solid waste. Observations made using two-stage heavy media separation in a drum unit are included. Qualitatively, the results from the two types of separators are similar.

Jan 1, 1974

By R. J. Evans

The generation and disposal of solid waste from electric utility plants using a lime or limestone wet-scrubbing system and the potential effects on the environment were estimated for 1975 and 1980. The study indicated that in 1975 approximately 5.8 million tons of desulfurization solid waste (50 percent solids) will be generated. In 1980, when it is estimated that desulfurization will become commercially accepted, approximately 71.4 million tons of this material will be generated for disposal and/or utilization. The desulfurization waste material when combined with lime, fly ash, and water may have potential for use as a roadbase material, landfill reclamation, and synthetic aggregate.

Jan 1, 1974

By Lyman H. Hart

Some of the significant facts that will affect the supply and demand for metals during the next few decades are given in this presentation. This is important because the only hope for intelligent guidance of the national destiny depends upon presenting a consistent and accurate picture of basic problems. The metals problems now fomenting are only slightly less important than those precipitating the energy crisis. Admittedly, it is difficult to generate serious thinking on this subject when the world is enjoying easy access to all metals at modest prices. This is possible because of the current world capacity to over-produce, and United States credit standing, at least up to now, has permitted buying freely on world markets. Although both these vital conditions are subject to change, there is little doubt that if the U.S. financial house is kept in order, we can muddle along for a while on a generally expanding, metal-based economy. But should our credit standing be permitted to collapse, or should there be a tightening of world supplies of metals, the nation would immediately find itself in trouble. Unfortunately, clear signals indicate that both of these conditions are threatening. The metal age started many centuries ago, and with the exception of the noble metals, barely a dent was made in world reserves until the present century. Then, as a result of the pioneering ideas of D. C. Jackling and Paul Gemmel, and the willingness of the McNeals, Penroses and Guggenheims to back ideas with money, a virtual explosion of metal production was propagated throughout the world. It is important to examine the causes of this expansion to determine whether it is a trend that may be sustained or whether it is anomalous and therefore attributable to circumstances not likely to be repeated or continued. This period of plenty is a once only phenomenon. Vast metal resources have been sitting around here for eons, while the world was unaware of or unconcerned with their existence. But when population began to grow exponentially, and ways were discovered to use metals to develop machines to do the work of men and animals, the exploitation of raw materials increased at a staggering rate. And now the realization is dawning that minerals are a wasting asset and are beginning to present supply problems that should begin to be of concern. Two main factors have caused this condition; One is the population growth, and the other is the expanding demand for irreplaceable raw materials as nations become more developed. A group of systems analysts, at Massachusetts Institute of Technology in a book Limits of Growth, has warned that at present rates of population growth and resource consumption together with environmental constraints, a point will be reached within 100 years when the world population will become totally incapable of supporting itself. The authors conclude that this end result could be avoided if a planned equilibrium could be established at a lower rate of population growth and resource consumption. Fortunately, there is evidence that the population problem is moderating. The growth rate in the U.S. has decreased from 2.3% per year in 1900 to 1.1% in 1970. But, even at the lower rate, population will double in 70 years. The world rate is greater, and if it continues, world population will rise from 3.5 billion to nearly 10 billion in 50 years. All of these projections are questionable because the dangers of growing population are now being recognized. A marked decrease in growth rate has been noted in the more developed countries-in fact, it was zero in the U.S. in 1972. The other factor affecting consumption of raw materials is the increase in per capita use of most items as individuals become more affluent. Many economists believe that developing countries such as China and India represent a vast future potential market; but there are others, with whom the author agrees, who believe over-population tends to stagnate development. Nevertheless, it is a fact that vigorously developing societies increase consumption at a rate far above their population growth rate.

Jan 1, 1974

By Fred Pena

Cyprus Pima Mining Company is located in the Mineral Hill District of southern Arizona, approximately 22 miles south-southeast of Tucson. Cyprus Pima Mining Company is owned 50.01% by Cyprus Mines Corporation, 24.99% by Utah International Incorporated, and 25% by Union Oil Company of California, with Cyprus having the management responsibility. Cyprus Pima's history has been one of continued expansion from an initial plant of 3,000 TPD in 1957; 6,000 TPD in 1963; 18,000 TPD in 1966; 36,000 TPD in 1967; and 53,500 TPD in 1972. The major reason for Expansion IV was that a large volume of low-grade ore had to be moved to get at a higher grade ore in the course of proper pit development. With mining costs already defrayed, this relatively hard, low-grade material became economically profitable for subsequent milling and concentrating treatment. Similar material previously stockpiled was available for ore treatment. In an effort to meet the continuing search for lower unit costs, the largest milling and concentrating equipment had to be examined. The management of Cyprus Pima Mining Company began investigating autogenous, and semi-autogenous milling in 1964 when two carloads of ore selected from the Cyprus Pima pit were sent to the Koppers--Hardinge Operation at York, Pennsylvania for testing. One car contained approximately 40 tons of hard arkosite and the other contained approximately 40 tons of ore classified as soft Hornfels. The purpose of the testing was to determine the amenability of both ore types to autogenous or semi-autogenous grinding.

Jan 1, 1974

By Jacob Feld

Introduction The best way to eliminate the possibility of rapid excavation in tunnel work is to start an argument between Owner Engineer and Contractor. And arguments are readily started when work is progressed without a frank open agreement on the rules of the game. Fifty years ago a tunnel contractor took a job to excavate and line a tunnel, providing all labor and materials under the guidance and continuous instruction of the Engineer who provided all survey work, checked each new heading and set the lines for the next round of drill holes, usually designed and ordered protective measures, kept record of progress and controlled payment for the work. In my first job in a tunnel, muck cars were loaded by hand and hauled by donkeys. Progress was, at today's criteria, not rapid. The Contractor or in the case of a large concern, his executive field representative was always at the site, knew most of his men by name, and there was a mutual feeling of respect between him and the Engineer in charge of the work. Misunderstandings were cleared up when they came up, expeditiously and fairly, even though satisfaction was not always expressed. The Owner came for the ground breaking and usually for the holing through shot. The Owner had full reliance on the Engineer's ability and integrity. The Engineer recognized the Contractor's expertise in being able to man the job and produce results.

Jan 1, 1974

The panic bars (and associated linkage's and electrical circuitry) that are defined in this document are a machine operator-actuated control for the emergency deenergization of the tram motors on Self-propelled, electric and diesel face equipment; including haulage equipment such as shuttle cars. There are nine basic types of panic bars (and several variations) that are recommended in this document, but all of the panic bars are characteristically of the "fire door" type that is frequently encountered on outside exit doors of many public and soma commercial buildings. It is also the intent of the following panic bar designs that, when emergency brakes are added to the face equipment machinery for which they are required, that they be designed and hooked up so that actuation of the panic bar will result in automatic application of the emergency brakes (immediately following the deenergization of the tram motors). The following panic bar design requirements are a restatement of the proposed requirements defined in the Federal Register, requirements cited in 'Guidelines for the Design and Installation of Devices for Deenergization of Self-Propelled Electric Face Equipment/Automatic Emergency Brakes" by C. E. Lester and J. D. Greenhalgh of MESA, and Bendix recommendations that were formulated as a result of discussions with personnel at the various machine manufacturers and underground coal mines that we surveyed, discussions with G. L. Judy (our consultant), etc:

Jan 1, 1974

By R. V. Subramanian

This project financed by the Bureau of Mines investigated the use of polymers to achieve rock bonding and reinforce coal mine structures for better or permanent ground support. Support was achieved by pumping the polymers into the rock interstices to bond the mass together for increased structural competence. Holes were drilled in the mine roof, after which the polymers were injected at about 100 psi to permeate the cracks. Initial laboratory work indicated that of all the resin systems tested, the epoxy resins could most likely be modified to be suitable for rock injection. This was confirmed when several potentially suitable resin systems underwent intensive evaluation. In a series of three field tests, two conducted in a copper mine with coal mine-type shale and the third in a coal mine, it was shown that the polymers penetrated cracks less than 0.005 inch wide. The fast-setting epoxy systems, cured out in thin films under mine conditions, produced a bond exceeding the strength of the uncracked virgin rock.

Jan 1, 1974

By L. W. Saperstein

One of the most critical skills developed by underground coal miners is the ability to interpret natural warning signals in terms of impending roof failure. A miner receives a variety of signals which can be called warning and which can be classed broadly by sense: aural, visual, and tactile. This paper concentrates on those signals which are airborne and audible. These signals are creaks, cracks, pops, groans, snaps, booms, tears, rips, and other assorted pulses which emanate from the roof strata, coal pillars, and artificial support in response to the stresses induced by the mine opening. These pulses are sometimes referred to as "talk". Although it is clear that miners rely on roof talk to assess the roof's stability, it is not clear of what roof talk is composed. It has been described in a variety of figurative ways, but has not been scientifically characterized. As will be shown shortly, the purpose of this research is very specific. The ramifications, however, are very broad, and are, indeed, still being followed.

Jan 1, 1974

By Manuel Viveros J.

This paper will deal with the type of rocks so called evaporites, which are sedimentary rocks produced by water evaporation from seas, lakes or marginal lagoons, in warm and arid climates. Salts derived from these deposits are precipitated according to their solubility; that is, the more soluble precipitates first, overlain by other sediments like silts, shales, limestones, sands, etc. The most common evaporites, according to their chemical composition, are : Chlorides Sulphates Carbonates Nitrates Borates Common salt, or halite, sulphates like anhydrite and gypsum, are the most important. Potassium chloride (silvite and carnalite) and potassium sulphate are of great commercial value.

Jan 1, 1974