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By Louis C. Just, Grahan A. Mathieson

Low cost, greater operating flexibility, and relatively simple operation are just three of the reasons for using minicomputers in the mining industry. No less than a dozen US manufacturers have sold the new generation of minicomputers to mining operations in the US and the world. Many manufacturers produce several models of minicomputers, each with excellent calculating capabilities. Prices for these "mini-giants" range from about $10,000 for a basic system to over $300,000 for a very powerful, sophisticated system with numerous peripheral devices. While the acceptance of minicomputers by the mining sector has lagged behind their penetration into other businesses, mines with minicomputer capability-especially remote mine sites-have found applications in practically all areas of operations including standard payroll processing, mineral deposit modeling and planning, surveying/mapping, production reporting, and daily production scheduling. In fact, the only limit to the further application of minicomputers in mining is the user's imagination. There are some obstacles to the accelerated use of minicomputers in the mining sector: the limited amount of software available, limited information on site-specific uses, and limited interest in the mining market by manufacturers. The latter is especially significant in light of the fact that many manufacturers queried in a recent telephone survey did not compile statistics on locations of their units in mining. The general consensus is that mining sales represent less than 1% of the total market. Many manufacturers do believe that market dynamics will increase their future research and development for the mining industry. The minicomputer was introduced in 1968, when Digital Equipment Corp. of Maynard, MA, developed a small computing device-the PDP-8 minicomputer. It is important to note that since then, it has become increasingly difficult to precisely define a minicomputer (see box, page 1582). The mini has evolved to surpass the capabilities of many of the large computers (mainframes) of 1968, and some models rival the mainframes of today.

Jan 11, 1981

By C. P. Blair

In discussing so-called "volume rates" for the movement of coal, I start from one basic premise: That it is the job of the railroads to devise rates which will move the traffic, while at the same time assuring a fair return on their investment. No matter how reasonable and nondiscriminatory freight rates may be, if they fail to attract and hold traffic to the rails, they are utterly useless - both to the carriers and the shipping public. And it will be my purpose here to show that under certain circumstances the use of volume rates by the railroads enables them. to hold traffic which would otherwise be lost, and to avoid needless dissipation of revenues, Properly employed, volume rates should benefit both the coal industry and the railroads, I do not, however, advocate the discarding of the carload as the basic rate-making unit. Far from it. Sound operating reasons dictate the making of rates based on car- loads, and the tradition of carload rates has a firm foundation in railroad operating costs, many of which vary directly with cars handled. In short, the carload was, Is and, in my opinion, will continue to be the basis for most rail rates on coal, as well as on other commodities. But change is an inevitable result of progress, and we should not be so bound by tradition that we are unwilling to try novel methods of ate making, should the circumstances require, The modern rate maker must, now and then, run the risk of being called an iconoclast if he is to keep up with the times. As T will point out, volume rates were for many years rejected by both the Interstate Commerce Commission and the railroads, But now both the Commission and the carriers have come to recognize that under proper circumstances and conditions volume rates are a powerful and effective tool.

Jan 1, 1959

By S. D. Bechtel

Bechtel Civil and Minerals, Inc., one of the Bechtel group of companies, is a large engineering and construction firm that services the mining industry, among others. The firm's head, S. D. Bechtel Jr., comments on how his E&C company is dealing with the recessionary economy. First, he offered a historical perspective. About a half century ago-in the middle of the Great Depression-W. A. Bechtel and several business partners drew up a fixed price bid to build the Hoover Dam. At that moment in history, the W. A. Bechtel Co. was a modest success, but the times were troubled and uncertain. Money was scarce and a lot of contractors across the country were one project ahead of bankruptcy. The bid for Hoover was a make-or-break proposition for Bechtel, and it turned out successfully. The Hoover Dam was a no-frills operation in an isolated and harsh environment. There was plenty of hard work, long hours, and not many amenities. Controlling costs was critical. Everyone knew what had to be done, and why and what the consequences were. Today's Challenge Bechtel is now a bigger, more complex organization whose management views the current economic recession as a challenge to be met in much the same way W. A. Bechtel met the challenge of the Hoover Dam: by pulling together with a sense of purpose and direction. In many respects, Bechtel's situation today has a number of parallels to that which faced my grandfather. The company is eminently successful, but times are tough and there are plenty of signs that they could get tougher. My grandfather bet on the Hoover Dam to insure the future health of his company and I think we can work together again in that same tradition, make some tough decisions together, and the company's future can be just as promising. The first and most important requirement is to make certain that everyone understands the situation. The Bechtel group of companies are in an excellent financial position now. Its workload hit an alltime high in 1982 and it is well positioned in its principal markets. But the next two years may be critical for the company. Traditionally, Bechtel's work load lags behind general developments in the economy. Although many of its clients continue to suffer serious business difficulties, Bechtel is only beginning to feel the impact. The worldwide market for basic metals remains soft; relatively low prices and abundant supplies of oil and gas have flattened the petroleum market and made once promising synfuels projects economically unattractive; utility clients are still caught in the vise between overregulation and escalating costs. And persistently high, long-term interest rates have made capital investments expensive and difficult to justify. The company maintained a healthy workload through 1982. In some areas it has had little new work and consequently has been forced to lay off some staff as projects have been canceled or concluded. In other areas new work has tided the company over and more people have been hired. But new work bookings have fallen off, creating some uncertainty for the near future. 1983 requirements are clear, although seemingly contradictory. Belt tightening and cost reduction are necessary for Bechtel to remain healthy and competitive, enabling it to handle a possible further downturn with a minimum of turmoil and dislocation. At the same time, we need to allocate resources and funds in areas that will keep us positioned for the turn-around marketplace.

Jan 2, 1983

By Hans W. Schreiber

Most geologic and mining engineering consulting firms* began to experience the recession with declining billing levels, number of inquiries, and proposal requests in late 1981 or early 1982. As of today, most of them have been functioning at reduced income levels for nearly a year. And while many consulting firms have apparently reached a stabilized income level, they can see little prospect for attaining normal (pre-late 1981) billing levels and income for the remainder of 1983. A few firms have escaped being affected by the recession. Such com panies almost without exception are small (fewer than 20 personnel), offer a limited range in technical capabilities, and tend to be highly specialized in a particular niche. They include those specializing in the heap leaching of precious metals ores, in ground water testing programs, and in the derivation of computer-aided programs to monitor particular mineral processing functions. Those firms affected by the economic downturn have instituted a variety of policies and undertaken actions to cope with significantly reduced incomes to bring fixed costs in line with the depressed demand for services. These changes fall into the following broad categories: • management and management practices; • markets and market definition; • marketing and the pursuit of assignments; and • administration and personnel relationships. Not all of the perceived changes have necessarily been instituted by every consulting firm, and any one appears sporadically instituted. Management and Management Practices In favorable times the managers, and often the owners of the equity, of consulting firms tend to concentrate their attention on the part of the business they find most satisfying and enjoyable. For some, this means acting as project or assignment leaders, even undertaking a specific technical aspect of the job. For others, it means constant marketing with the associated heavy travel and entertainment schedules. In unfavorable conditions, such as the current recession, managers tend to spread themselves far more thinly, expending time and effort on all facets of the business including marketing, proposal preparation and cost estimating, budgeting, general administration, accounting and cash flow monitoring, project/assignment overview, and actual client work. The manager who in favorable times concentrated on client work is now less billable. The manager who concentrated on marketing is somewhat more billable. The manager now needs to pay attention to and expend equal effort on each facet of the business just to keep all the facets in relative balance. Falling behind schedule on a client job or carrying an unduly large percentage of accounts receivable exact a cost to the firm. Clearly the absolute cost to the firm is the same whether demand for service is good or slack. But in periods of slack demand the firm is frequently less able or even unable to bear such costs. Marketing and Market Definition Markets appear to have undergone some significant changes: • Federal and state governments have assumed a greater importance as providers of work vis-a-vis both industry and private groups. • Projects with increase-in-capacity aspects have given way to projects with maintenance or reduced operating cost aspects. • Projects searching for new deposits of minerals in generally new locations have given way to projects reviewing known mineral districts or known deposits. • Industrial mineral and mining companies have exhibited a great propensity to cut back the use of consultants and to undertake as much work as possible in-house. Further-more, a number of industrial mineral and mining companies have entered the competitive arena with consulting firms, submitting proposals (usually to the federal government) in an effort to keep their staffs intact and occupied. In response, consulting firms have reevaluated their capabilities by reviewing old work and reassessing personnel. The purpose is to broaden the services offered and the potential client base, thus redefining the available market. For example, a firm specializing in assessment of technical and cost parameters of a deposit would normally assist a prospective lender in judging the deposit's suitability for project financing. That same company could easily expand into the field of analyzing production costs for an individual operation -something that is needed in periods when lower prices reduce profit margins. Similarly, a firm that has confined such economic assistance to commercial banks could expand to provide its expertise to other lending and even equity buying in-stitutions such as insurance companies. Marketing and the Pursuit of Assignments With few exceptions, consulting firms have significantly increased their

Jan 2, 1983

By Simon D. Strauss

The recession that began in late 1980 has proved to be not only prolonged and severe, but in certain ways unique in its effect on the mineral industries among the periods of economic slowdown experienced in the Western world since the end of World War II. This time almost all minerals have been affected. In previous business turndowns, by contrast, some mineral sectors have with-stood economic adversity well. They experienced little or no adverse effect-thanks either to a strong secular expansion in the markets for their particular product or to specific factors that caused demand to be well maintained. For example, aluminum, molybdenum, and nickel are three metals that enjoyed extraordinary growth in applications during the years 1946-1973. These metals were little affected during the recessions that occurred in that era. Similarly, coal did not suffer a pronounced drop in sales in the 1974-75 turndown because, with the price of oil rising sharply, a switch away from oil and back to coal was clearly indicated for some energy-intensive applications. Oil itself was largely impervious to the ups and downs of the business cycle until very recently. And the precious metals, gold and silver, have often been regarded as benefiting from reduced economic activity because labor becomes more available, productivity rises, and operating costs diminish. In the current recession, however, no major mineral has escaped the broad trend. The secular growth factors that were previously so evident for aluminum, molybdenum, and nickel have disappeared, at least temporarily. The stable pricing behavior that previously characterized all three of these commodities has been replaced by extreme price weakness and apparent inability of the major producers to continue their roles as market leaders. Coal and oil both have suffered from a sharp drop in energy requirements. There are those who now anticipate a collapse of the market control over oil prices so clearly exercised by OPEC since 1973. If oil prices are no longer effectively controlled by the governments of the exporting countries, then coal prices are also certain to be affected. And the combination of high interest rates, tight money, and a change in public perceptions of precious metals put the skid under gold and silver quotations in 1981 and early 1982. Although inflation has been viewed as the scourge of most Western countries ever since the oil crises of 1973-74, prices-in constant dollars-of most minerals have not risen. On the contrary, with the exception of the precious metals and oil, for most minerals the prices that prevailed at the end of 1982 were close to the levels of the Great Depression of the 1930s in constant dollar terms. Table 1 compares prices for copper, lead, zinc, and aluminum at the end of 1982 with the average prices in 1934, stated in constant 1967 dollars. This emphasis on prices for mineral commodities reflects the fact that profits of mining enterprises vary directly with the level of prices. Manufacturing and retailing enterprises march to a different tune. They establish sales prices based on costs. Their profits tend to vary with volume. Commodities are for all practical purposes fungible, that is the advantages of known brands in marketing manufactured goods have little application in a commodity market. Thus the individual seller of minerals is unable to establish his sales prices. Except where a monopoly is present, he must sell at the going market. His option is to abstain from selling if he finds the price unremunerative. In past recessions, some mineral producers chose to do precisely that-either accumulating a substantial share of their output in inventory or, in prolonged downturns, abstaining from production. During the current recession, however, private-sector mining companies did not have the option of accumulating inventories to any great extent. Capital costs for new mineral projects or for expansion of existing facilities have escalated at an alarming rate since the early 1970s. Added to this has been the heavy cost of installing pollution control or safety equipment to comply with the regulations adopted in most industrialized countries (and particularly the United States) since 1968. The consequence has been that the financial position of most major mineral enterprises in mid-1980 was already strained. To finance increased inventories meant incurring additional funded debt at high interest costs, thus impairing the concern's credit rating. Management Choices Private-sector managements have had to face up to the alternative of either continuing to produce at an unchanged rate and marketing output at unremunerative prices or reducing output. The latter has meant either operating at a curtailed rate, with con-

Jan 3, 1983

By Franklin J. Stermole

The current financial state of the mineral industry, in general, is bad. Economic prospects for improvements in the near future are uncertain. What will improve mineral investment economics so the mining industry can return to a more normal (in terms of past experience) production level? Basically, mineral commodity prices must rise. They must rise to economically justify reopening closed mines and for management to seriously consider expansion or development of existing and new mines. With the worldwide economy depressed for more than a year now (longer for most segments of the mineral industry), supply/demand relationships for mineral commodities are such that prices are depressed-except for precious metals. In investment analysis of the economic potential of existing or new investments in any industry, product price generally is one of the key parameters having great impact on the economic viability of projects. Petroleum and synfuels industry development contracted last year for the same product price reasons that have brought mineral industry development to a standstill. Much of the new mine development activity now underway or in the serious planning stages around the world involves precious metals ore body development simply because precious metal prices are high enough now or are projected to be high enough in future production years to give overall satisfactory project economics. It will take significant improvement in nonprecious metal mineral commodity prices in 1983 to develop significant new mine investment interest except in very high grade ore body special situations. Mineral Investment Decision Making Before progressing further with the discussion of mineral investment considerations for the coming year, it should be emphasized that mineral investment decision making-like all industry or individual investment decision making does not relate just to economic considerations. Investment decision making should and generally does involve three analyses: • Economic analysis • Financial analysis • Intangible analysis Economic analysis evaluates the relative economic merits of investment situations from a profitability viewpoint based on discounted cash flow analysis of projected investment revenues and costs. Financial analysis, on the other hand, refers to where and how the funds for proposed investments will be obtained. Regardless of the project's economic potential, if you can't finance it, the project will not be done. Intangible analysis considers factors affecting investments but which cannot be quantified easily in economic terms. Typical intangible factors are legal considerations, public opinion, goodwill, environmental and ecological impacts, and regulatory or political considerations, to name a few. New mine development investment decision making in the US has been impacted heavily by intangible considerations in the past decade and will probably continue to be impacted by them in 1983. There is a common tendency in literature and management practice to interchange the terms economic analysis and financial analysis. This often leads to confusion about the rationale for investment decisions. For example, in the past year a majority of companies in all types of industries cut back budgets for new projects. Often this was done not because new project economics were unsatisfactory, but because cash flow from existing operations was reduced compared to previous years due to the recession, and debt service requirements were high from existing loans so new borrowing was undesirable. For financial reasons, in other words, many projects were shelved last year. That included some precious metal mining projects and many petroleum projects. Many other projects were shelved for economic reasons (sometimes combined with financial reasons in the case of marginal economic projects). New mine development for copper, lead, zinc, molybdenum, iron ore, and synthetic fuels are a few examples. Economic Uncertainty and Financial Considerations Mineral project analysis has always involved a lot of uncertainty with respect to determining ore grades, tonnage of producible reserves, operating and capital cost projects, and mineral commodity prices estimates. The wide swings in mineral commodity prices in recent years and the almost impossible task of projecting future prices with any degree of confidence or accuracy concerns mineral project investment decision makers. In developing a new copper or silver mine, it is not today's price of copper or silver that is relevant to economic analysis of the mine, but what the price will be during the producing years. There is no way to avoid projecting the escalation (or de-escalation) effects on revenues and costs. To analyze a project in terms of today's dollar revenues and costs implicitly assumes that escalation will not change today's project costs and revenues; or that, if they do change, the project economics will be unaffected by the changes. This often is not the best or even a realistic assumption. The inherent uncertainty associated with historical mineral price swings is exacerbated in 1983 by the uncertainty of when

Jan 2, 1983

By Kenton E. McElhattan

Financial analysts have often called National Mine Service Co. the only "pure play" company to the mining industry, meaning that an investment in NMS is an investment in the mining industry. As a leading manufacturer and supplier to the industry, National Mine Service does enjoy a close and direct relationship with mining. It is the only independent company that offers products and services that include mining machinery, health, safety, instrumentation, mine supplies, and reconditioning services for hydraulics, electronics, and machinery. But what is a positive relationship in periods of economic upturn can be eauallv as negative during the downturns. In fact, National Mine Service has felt the resounding blows of the current recession in the mining industry. Two-Fold Strategy Rising unemployment, corporate losses, bankruptcies, and mine closings in particular have directly affected NMS. But the company embarked on a strategy several years ago that included a two-fold approach to becoming less dependent upon the vagaries of the US coal industry. One strategy was to develop additional products and services for other mineral industries such as potash, trona, and salt and, where possible, apply the technology developed for the mining industry to industrial markets. The other strategy was to become a more international company. The objective was to make export sales a minimum of 10% of total corporate sales. Even today, NMS believes this is a good strategy as opposed to diversifying because its expertise is in mining, not in other areas. A review of NMS's fiscal 1982 annual report indicates that the company's strategy did begin to pay off. 1982 was a turnaround

Jan 2, 1983

By Graham J. Morgan

The following material is excerpted from a presentation Mr. Morgan gave recently to representatives of the financial community. Introduction 1982 was a period of challenge for United States Gypsum Company because of reduced market opportunity. Housing starts for the first 10 months averaged a seasonally adjusted annual rate of 1 million units, 9% below the comparable 1981 period when housing starts were the lowest in 35 years. Industry gypsum board shipments declined 9% from the already low levels of the same period in 1981. US Gypsum met the challenge with stringent cost reduction programs and aggressive action in the marketplace. In late 1981, anticipating market deterioration, the company's management adopted strategies to focus on two shortterm objectives: • Adjust operations to perform profitably in view of limited opportunities through more efficient operations and asset management. • Continue to strengthen U.S.G.'s resources and ability to take advantage of important market opportunities as the economy improves through selective expansion of production capacity in key growth markets. Concentration on these two objectives resulted in a nine month performance in 1982 that, while certainly not satisfactory by company standards, compared very favorably with that of principal competitors in terms of net earnings, margin on sales, and return on average stockholders' equity. To counteract limited market opportunities, U.S.G. focused on productivity improvement, cost reduction, expense control, and maximization of market penetration. Energy Use Improving performance encompassed all segments of operations. For example, efficient use of energy was a significant factor despite lower operating rates at most plants. Overall, in the third quarter of 1982 versus 1972, the company used 27% less energy per unit of production, a savings of $15 million in that quarter alone. These continuing improvements helped to partially offset constantly rising energy costs. A number of operations achieved superior results in the first nine months of the year compared with the same period in 1981. For example, gypsum board plants in Jacksonville, FL, and Sweetwater, TX, recorded 8% and 7% reductions, respectively, in energy use per unit of production. Paper mills in Oakfield, NY, Galena Park, TX, and Kansas City, MO, each reduced energy use more than 12%, while the Greenville, MS, ceiling products facility achieved a 16%o reduction. Safety Safety is another important element that received increased attention. U.S.G.'s safety performance over the past five years has consistently improved. In 1981 it was five times better than that of the gypsum industry; nearly 10 times better than all industry as measured by the National Safety Council; and almost 20 times better than all US manufacturing as recorded by the Bureau of Labor Statistics. In addition to human concerns, this excellent record results in significant dollar savings that directly affect company results. In 1981, U.S.G.'s pre-tax savings in claims, premiums, and related expenses were about $20 million compared to the industries in which it competes. For the first half of 1982 performance improved further, with a cumulative lost workday incidence rate per 200,000 man-hours worked of only 0.27, an all-time record. Expense Control Careful control of inventories and receivables also received special attention. As of Sept. 30, 1982, inventories were 29%, or $44 million, below the level of Sept. 30,

Jan 2, 1983

By Sohta Takatsu, Hachiroh Mizubata, Shigeki Kudoh, Kazuya Takekuni, Yoshinori Yamada

A special type of shotcrete is used to improve the performance of open-type TBM in difficult situations. The Hakamagoshi and Johana tunnels are expressway evacuation tunnels of 3.2 km and 5.1 km in length, respectively (total 9.1 km) that were excavated by one open-type TBM. The geological conditions at the sites were estimated to be good before excavation. However, 95% of the rock turned out to be two ranking orders worse than the estimated classes. Therefore, we used a special shotcrete for bad rock conditions, and succeeded in excavating the tunnel at an average rate of 270 m/month.

Jan 1, 2001

By Alexandru Corneliu Stematiu, Catalin Popescu, Radu Sarghiuta

"The tunnel sector is excavated into a rock mass heavily affected by tectonics, defined as a regional fault. The rock around the tunnel support undertakes the non – elastic deformation and gradually detaches from the rest of the non affected rock mass, moving inside of the excavated area and tending to fill up the whole space. The initial solution of using stiff support consisting in double steel ribs I12 with circular shape in the upper part and straight vertical pillars in the lower part has proved to be inadequate. Based on the calculations of the subsidence phenomena and a mathematical model, the proposed alternative support was provided by special circular steel ribs – SG-23 –that allows a limited rib deformation (by relative slip between the arch segments) in order to mobilize the contact between the rock contour and the inner face of the rib - not only for the deformed rib but also for the neighboring ribs. 1. INTRODUCTION Hydropower development of Jiu river in Romania, in the narrow gorge sector includes two diversion HPP and a small hydro plant that provides the minimum required flow downstream: CHE Dumitra , CHE Bumbesti and MHC Livezeni (Table 1. Hydropower parameters).The Livezeni intake reservoir is provided by a gated dam located 1250 m downstream of merging point between Jiul de Vest river and Jiul de Est river. The dam is equipped with three radial gates with flap gates with a span of 12 m each and the height of (6 + 3) m. The longitudinal profile of Dumitra head and the location of the gallery zone that is the subject of the paper are presented in Figure 2. Longitudinal Profile – Dumitra Head."

Jan 1, 2016

SOLUTION MINING Solution mining techniques present a means of extracting soluble ores, particularly such materials as salt and potash, from horizons which are not accessible by conventional mining. In the process of dissolving materials, it is evident that solution may be complete or partial. In general, the solution mining operations described in the following section relate to complete solution of the desired compound. Even though the solution of material is complete, there may be instances in which insoluble material is present to a large extent either as granular separated particles or as insoluble layers. The process required for obtaining the desired product involves access wells to reach the deposits, sufficient water supply to yield the production goals, and the development of an underground cavity. The process of solution mining, therefore, depends to a great extent on three factors: availability of a relatively pure strata or formation of salt or potash to be mined, access well or wells, and adequate control of the solutioning process so that enlargement of underground cavities can be fairly well delineated. Since halites represent the most general ores mined by this procedure, the considerations which follow are based primarily on the production of sodium or potassium chloride. The producing formations may be in the form of bedded evc~porites wherein the salt member may be some 30 to 500 ft thick or from salt domes in which great depths of salt occur. Solution mining has been carried out to depths of nearly 10,000 ft. The recovery of saturated brine from wells drilled to effect the solution-mining process leads to further processing. In many instances, the procedures are relatively simple and involve simple recrystallieation or fractional crystallieation, while in others more complex flow systems are required before a final product is obtained. The intent of this section is to provide information relative to the basic procedures for obtaining materials which are soluble in water and to acquaint the engineer with the various aspects of the overall problem which in many instances, may become quite complex and present numerous difficulties. The storage of fluids, particularly hydrocarbons, underground has proven to be a very important part of industry operations. Cavities formed in salt provide excellent storage facilities. The formation of well-defined controlled configurations of such cavities has been possible because of better understanding of the solution process, wide experience gained over nearly 30 yr, and improved technology in drilling and completing wells, surveying caverns, and the operation of numerous types of systems. Solution mining techniques will improve in the future. Many facets of the simple operation of pumping solvents and extracting valuable minerals require further study. Developments undoubtedly will occur to further the processes of mining by solution. In addition to those whose names appear in connection with the individual subjections which follow, a major role in assembling and processing the material in this section was played by Dr. D. A. Shock, Central Research, Continental Oil Co., Ponca City, Okla.

Jan 1, 1973

By Gary A. Almeraris, Thomas F. Peyton

This paper describes the innovative procedures employed during the construction of 3 deep shafts within the confines of New York City. The shafts, which varied in diameter from 1.8m (6ft) to 7.3m (24ft) and had an overall depth of 199m (650ft), were excavated by both mechanical and conventional methods. These were subsequently concrete lined, clad steel riser pipes installed and associated surface structures were constructed. Tricky surface rock blasting coupled with the unearthing of unexpected obstructions caused constant uncertainty during the excavation phase. In addition, the necessity of handling men and material in restricted yet deep openings required the development of a safer and more productive shaft construction procedure.

Jan 1, 1989

By S. C. Carniglia

Bayer-process alumina hydrate becomes in turn the source of a host of special products in addition to the calcines that feed aluminum reduction cells. Though relatively smaller in tonnage, specialty aluminas serve important industrial markets in an exciting and growing variety. Production methods and applications are discussed for: (1) trihydrate as flame retardant in organic materials; (2) high-surface-area transition aluminas as desiccants and scavengers, catalysts and substrates; (3) calcines for industrial ceramics, refractories, and abrasives; and (4) tabular alumina for refractories, bed supports and other uses.

Jan 1, 1977

By Harry Teicher

The subject of Specialty Silica Products could encompass a broad range of materials, some of which would be familiar to members of the Society of Mining Engineers. With the concurrence of your chairman, I have chosen to limit my remarks to synthetic materials, not including such siliceous materials as diatomaceous earth, asbestos, quartz and clays. For purposes of discussion, I have classified Specialty Silica Products into two groups -- powders and liquids -- which I will discuss in that order and which are categorized in Figure 1. The synthetic silica powders are amorphous to x-rays and are manufactured by various processes resulting in products of a wide range of physical and chemical properties, as well as functional performance and applications. Applications or functional properties are generally dependent upon such physical properties as micron-sized particles exhibiting large surface areas per unit weight and low apparent bulk density. Their presence in various systems modify surface properties. As summarized in Figure 2, they act as viscosity modifiers, flow conditioning agents, anti-slip agents, anti-blocking agents, flatting agents in surface coatings, reinforcing agents in polymers such as silicone rubber and numerous other applications. Although the various types of silicas exhibit various levels of functional performance in these end uses, they are not usually equally effective as direct replacements and I will briefly discuss the various types of materials.

Jan 1, 1974

By L. E. Mylting

Modern ash handling systems exist in considerable numbers and a great deal of design and operating experience has been accumulated, It is the endeavor of this paper to point to a number of frequently recurring problems, A general appreciation of these problems will be helpful in both design and operation of systems. The light fly ash and the heavy bottom ash present different problems, and each will therefore be treated separately. Fly ash is collected in the ducting from the furnace to the stack and beneath the mechanical and electrostatic dust collectors. The greatest amount of dust is collected beneath the mechanicals and electrostatics. Hoppers are generally provided as integral parts of the collector. Suitable valves and piping are connected to these hoppers for removal of the dust. The size and shape of these hoppers are important factors in determining frequency of handling and the capacity of the system.

Jan 1, 1958

By Peter Loehr

Full-face tunnelling machines were introduced into German coal mines 12 years ago. It was aimed to utilize these highly efficient systems to drive mine tunnels in rock so that the large demand for development work in some mines could be met. A characteristic feature of coal deposits in Germany - and particularly in the Ruhr Area - is a thick overburden strata. Access is therefore only possible through vertical shafts. A network of horizontal drivages leading from these shafts open the deposits between the different mine levels. The hardcoal-bearing formations are multi-folded and heavily tectonically stressed. Apart from a few extensive fault zones there are many single faults of different natures in the carboniferous strata. During the course of decades coal mining has penetrated to ever increasing depths. Nowadays coal is mined from depths of between 600 m and 1,200 m. The effects of ground pressure in connection with extremely varying rock strengths and high temperatures are particular difficulties which have to be overcome during drivage work. The first full-face tunnelling machines to be applied in the mines had originally bee deigned and developed for tunnelling projects. Not only the machines themselves, but also the back-up equipment had to be adapted to meet the special demands of German coal mines.

Jan 1, 1983

By Lothar Anheuser

The appearance of very large shielded softground TBM's, of 14 m (46 ft) O.D. and more, as needed for two-lane highway tunnels, calls for a thorough search of overall stability and new solutions for front support during maintenance operations in the cutting chamber. The paper deals with the development of a shield for the planned 4 th tunnel crossing under the river Elbe in Hamburg. Specific problems arise from the high water head, the shallow overburden of loose soil and the stone-bearing mixed ground. The choice of the tunneling method and the different features provided to overcome the problems are discussed.

Jan 1, 1995

By V. Svalbonas

Presently the U.S. mining industry is very conscious of costs. It is timely, therefore, to review the dominant specifications used in the industry for procuring large size-reduction equipment. These are compared with other specifications and procurement methods, such as ASME and DOD, using the criteria of resulting costs, safety/ quality, and fitness-for-service.

Jan 1, 1987

By A. J. Hendron, L. L. Oriard

INTRODUCTION Controlled blasting is used at some time during most civil engineering projects where there is rock excavation. Controlled blasting is often necessary because the blasting must take place in the near proximity of adjacent structures. In other instances, the blasting is controlled because a smooth perimeter is desired to minimize rock support and overbreak. The construction of tunnels and shafts for subways, rock excavations for foundations and the excavation of road cuts for interstate highways, sometimes require blasting operations which must be conducted in an urban environment. Unfortunately, blasting operations produce unwanted sounds and vibration along with their beneficial effects. Thus, in the writing of specifications for blasting in an urban environment, potential damage to adjacent structures by ground vibrations must be considered, possible damage to windows from airblasts must be considered, potential damage from fly rock must be considered, and the discomfort to people from ground vibrations, airblast, and noise must be taken into account. The contractor or the owner's engineer is faced with determining the maximum weight of explosives which may be detonated without damage to structures on adjacent property. If the weight of explosive is overestimated, the resulting damage to adjacent structures may result in costly losses. But, if the engineer or contractor is too conservative, and the weight of explosive becomes too restrictive, progress of the project may be curtailed and the cost of excavation will increase accordingly. The potential for damaging adjacent property is becoming more important in construction operations today. In the past, the plaintiff had to prove negligence in some states in order

Jan 1, 1997

By William F. Daly, William H. Hansmire

Installation of initial tunnel support is often the most uncertain element of work in the design of, and a contractor bidding on, construction of a rock tunnel. The risks the construction contractor and owner assume are delineated to a great extent in the technical specifications portion of the contract documents. It is intended that this paper identify current practices for specifying initial tunnel support and the impacts each case has on the assignment of risks associated with providing the initial tunnel support. Examples of recently completed tunnel designs are given.

Jan 1, 1985