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By Prakash M. . P. E. Donde

1. INTRODUCTION The Washington Metropolitan Area Transit Authority (WMATA) has often taken a leading role in introducing innovative construction technologies to build its transit system. Most recently, Contract Section E-5a, which included Fort Totten Station and Tunnels was constructed utilizing the New Austrian Tunneling Method (NATM) in soft ground. Along with the station and tunnels, two permanent shafts were also constructed in soft ground employing the NATM technique. This project is located within the District of Columbia on the Greenbelt Route. The subject of this paper is to discuss the unique method of construction of these two shafts, and explore the benefits of applying the NATM technique to the construction of deep shafts. The design of the shafts was performed jointly by Jenny Engineering Corporation of Springfield, New Jersey, and Mayreder Consult of Linz, Austria. The designers also provided construction support services and a resident NATM expert at the site during construction. The construction of the project started in April 1988 by a joint venture of Mergentime Corporation and H. T. Construction, a subsidiary of Hochtief Company from Germany. This $48.7 million construction project has been completed. 2. SUBSURFACE CONDITIONS The two NATM shafts are located primarily in Cretaceous-age deposits that are over 100 million years old. These deposits are intermixed and lenticular in nature

Jan 1, 1993

The PEMAC Commitment to World Class Industry in Canada The Plant Engineering and Maintenance Association of Canada PEMAC is a national, not-for-profit industry and technical association for plant and facility maintenance, engineering and physical asset management practitioners and professionals. Founded mid 80?s in the last century PEMAC is a knowledge based organization that focuses on sharing knowledge with our members and the profession. We provide education and professional development programs and certification for maintenance practitioners and professionals. We develop, produce and participate in conferences, seminars and trade shows.

May 1, 2008

By William Fink

ZINC is one of the effective elements introduced to enhance the strength of aluminum. This strengthening is principally attributable to the high solid solubility of zinc in aluminum and the pronounced variation of solubility with temperature. Consequently an accurate determination of the solid solubility curve is desirable. The solid solubility relations have been studied by numerous investigators. Shepherd' first established the existence of a solid solution region at the aluminum end of the diagram (y phase) by specific volume and microscopic determinations. Bauer and Vogel2 published a constitutional diagram which showed the limits of solid solubility as determined by thermal and microscopic methods. Hanson and Gayler3 presented the aluminum-zinc diagram which is now most generally accepted (Fig. 1). Chill-cast samples were given thermal treatments designed to obtain equilibrium conditions, quenched, and microscopically examined.. The solubility was placed between 15 to 20 per cent at 600 C., 20 to 22 per cent at 140° C. and 36 to 38 per cent at 270° C. Sander and Meissner4 decidedly modified the limits of they phase field of Hanson and Gayler's diagram by using similar methods on chill-cast specimens annealed for a shorter period of time. Tanabe,5 utilizing dynamic hardness, electrical conductivity and dilatometric measurements of specimens at temperature, obtained values comparable to Hanson and Gayler's at room temperature, but appreciably lower at higher temperatures. Nishimura6 concluded from age-hardening results of aluminum-zinc alloy chill castings, which had been quenched from 400° to 500° C., that the solubility of zinc in aluminum at room temperature is less than 5

Jan 1, 1932

By Kenneth A. Gutschick, Harry L. Francis

A large number of minerals and chemicals (Table 1), some mineral-derived, are used in the treatment of both potable water and domestic sewage waste water and solids (Anon., 1990). In water treatment there are ten principal process uses as shown in Table 2 (Anon., 1990), which also lists the major chemicals in each process. Since lime (calcium oxide, calcium hydroxide, and dolomitic lime) is the largest chemical (by tonnage) used in water treatment, this chapter will deal primarily with this product. Note that it is included in five of the process uses shown in Table 2, and that indirectly it is also used in at least one other category (taste and odor control, where lime is used with potassium permanganate to provide optimum pH condition). POTABLE WATER TREATMENT Water Softening The biggest use for lime in water treatment involves water softening, where it serves to reduce carbonate hardness caused by dissolved bicarbonate and carbonate compounds. Currently there are more than 1000 domestic water softening plants (Table 3) located in most sections of the country, but particularly in Ohio, other midwestern states, Florida, and Texas, where limestone bedrock abounds (Anon., 1990). Among the other uses for lime in water treatment are coagulation, disinfection, and removal of heavy metals due to high pH softening, removal of certain radioactive and organic compounds and fluorides, neutralization of acidic water, removal of silica, particularly with dolomitic lime, and removal of color. Most of the above advantages accompany water softening, although at some plants lime is used specifically for one purpose, such as silica removal with dolomitic lime, minimizing pipeline corrosion by addition of lime to correct an aggressive water, and others. Hardness in water comprises two types - carbonate hardness, caused by dissolved calcium and magnesium carbonates and bi- carbonates, and non-carbonate hardness caused by dissolved non- carbonate salts, particularly calcium sulfate, calcium chloride, magnesium sulfate, and magnesium chloride. Total hardness is the sum of the carbonate hardness and non-carbonate hardness. Waters are classified as soft (0 to 75 mg/L as CaCO,), moderate (75 to 150 mg/L), hard (150 to 300 mg/L), and very hard (above 300 mg/L). Most water plants strive to reduce total hardness to about 100 mg/L, although in recent years the tendency in some cities has been to allow a little higher value in order to reduce both chemical costs and the amount of water softening sludges produced. There are four basic types of softening plants: lime softening, primarily to reduce carbonate hardness; lime-soda softening, for reduction of both types of hardness (in some plants caustic soda is used in place of soda ash, but it is more costly); split lime-zeolite, where a base exchange mineral is employed in place of soda ash (this system also requires salt [sodium chloride] to regenerate the zeolite mineral); and finally zeolite softening, which is generally used in small systems for private houses and small municipalities. Principal disadvantages of the latter system are its relatively high cost and the salt requirement, which introduces considerable quantities of soluble salts into the waste water discharge system.

Jan 1, 1994

By James Douglas

An address before the Meeting of the New York Section, Nov. 4, 1914. As life advances one is inclined to look backward instead of forward, and the vista over which my memory carries me has been filled with such a shifting panorama of changes in metallurgy that the whole practice of the art seems to have been re-created. The first cupola furnace that I saw in operation was at one of the group of mines at Capelton, Quebec, from which the Nichols company still draws some of its sulphur supply. At that time it was operated by a Hartford, Conn., company, under a General Adams. When its small brick furnaces made a campaign of a week and smelted 10 tons a day, the feat redounded to the credit of the operator. The introduction of the water-jacketed cupola dates forward to the next decade. I was using one in Pennsylvania, making copper matte, to the horror of a noted metallurgist, who could not conceive it possible that you. could bring fused sulphides in contact with steel without rapid corrosion. In our ignorance we were doing what seemed to be an impossibility, and it is just that recklessness and disregard for precedent which has characterized so much of the work of American metallurgists, and carried us forward at such headlong speed. Once the water jacket was accepted as the type of the. copper cupola, its almost unlimited expansion in length, but not in width, was a matter of convenience rather than of skill. In Butte the cupolas have been enlarged by adding furnace to furnace. The first reverberatories which I saw in operation were those in Professor Hill's Black Hawk establishment, where the concentrates from the Gilpin County gold mills were run down into matte for separation in England. Sixty dollars per ton was the usual deduction in those days before gold and silver was paid for. Smelting was done with wood as fuel, and the capacity of the furnace was about 10 tons per diem. Shortly after this Professor Hill formed an alliance with Richard Pearce, who was running what, if I recollect aright, was called the Swansea Works, at the bend of the river approaching Georgetown.

Jan 4, 1915

By David M. Parkes, Mike Fisher

In 1947, coal production in Western Canada was 10 Mt (11 million st) which predominantly came from 120 underground mines. By 1968 production was down to 1 Mt (1.1 million st). Production in 1981 was back up to 29 Mt (32 million st), but only 1.5 Mt (1.7 million st) of the total was from underground mines. In fact, because of competition from open-pit mines, only two underground mines were operating in 1981-the McIntyre and B.C. Coal mines. While several other underground mines are being planned, this article will deal with only the two in production. Geology The geology in Western Canada is frequently complicated; hence only more regular deposits are mined. Coal is generally thick, often steeply pitched and usually soft or well cleated. The 5000-km (3,100-mile) coal belt that runs from the Yukon to Mexico is well developed in Western Canada. It is divided into two distinct regions-the Rocky Mountain Lower Cretaceous coals and the mostly uniform level Upper Cretaceous coals of the plains area to the east. Isolated pockets of coal occur at Vancouver Island and Hat Creek. Hat Creek's massive 300-m (984-ft) thick geologically recent lignite deposit is 250 km (155 miles) inland. Geography The infrastructure of Western Canada is shown in Fig. 1 along with the locations of the two mines. Both rely on exports of premium low volatile metallurgical coal mostly to the Pacific Rim. The rail distance from both mines to port is 1100 km (684 miles)-accounting for a significant portion of the sales cost of the coal. Mining Methods Two main mining methods are used-room and pillar and hydraulic. Longwall has been attempted and is being considered again. In the past, a simple hand method used gravity to help mine most of the coal on steep pitches. Levels were driven in the seam, rising slightly to assist in draining. On the advance, mining would start at the upper level, usually from adits driven in the side of the mountain. Rooms or angles were driven up 100 m (328 ft) at a suitable angle for the coal to flow down. On retreating out of the level, the pillars would be taken, starting from the highest point, using batteries to stop coal or rock flushing down the room. Batteries consisted of three to six stout wooden posts set at an angle to resist material flow. Coal loading was directly from chutes at the bottom of raises into 1- to 2-t mine cars hauled by diesel or battery locomotives. Often output was restricted by the supply of empty cars. Mechanization began in the 1960s but was difficult in these conditions. Mines such as Canmore and Coleman continued operation into the 1970s but closed because steep seams, high methane emissions, and faulting made mining difficult. McIntyre Mines The McIntyre mines are located 360 km (224 miles) west of Edmonton, Alberta, in the foothills of the

Jan 4, 1983

By Mould G. R

The paper presents a general background to the subsidence research programme being undertaken by the Department of Mineral Resources and Development in New South Wales. The results of the studies undertaken over the last ten years are summarised. The differences between these results and those obtained by the National Coal Board are discussed. The results of a study carried out on the effect of total extraction beneath a freeway in the southern coalfields are discussed in some detail. The procedures developed for the const- ruction of a 500 mm diameter natural gas pipe- line crossing a number of collieries in the northern coalfields are also outlined. The future direction of the Department's subsidence research programme is discussed.

Jan 1, 1980

Soil Testing for Engineers. By T. W. Lambe. Published by John Wiley & Sons. 165 P. $5.00.-Filling a need for a text for the teaching of soil testing in the laboratory, this book is also of value as a reference for practicing engineers and for personnel in soil laboratories. Following an introductory chapter on general laboratory procedures are chapters devoted to the individual laboratory soil tests which are commonly employed. Apparatus, supplies, recommended procedures, discussion of procedure, calculations results, and numerical examples are provided for each test. Brief derivations of formulas and explanations and discussions of calibration procedures and special techniques are given in the appendix. Mesabi Pioneer. Copyrighted 1951 by the Minnesota Historical Society.- Publication of this book has been made possible by a generous gift to Society from the E. J. Longyear Co. of Minneapolis. This book covers the evolution of the Mesabi Range from a wilderness into the nation's greatest iron producing area. In this book is found the first hand experiences of Edmund J. Longyear who saw the development of the range from its beginnings, and who himself took a notable part in it. In 1890 Edmund J. Longyear sank the first diamond drill hole on the Mesabi. During the next two decades he sank pits and holes- 7133 of them-throughout the length and breadth of the Mesabi Range, exploring for iron ore. He saw roads and railroads built. He watched the range communities--Hibbing, Chisholm, Biwabik, Mountain Iron and the others change from exploration camps to

Jan 11, 1951

By P. W. Shimer

The purpose of this note is to call attention to a source of error in the determination of graphitic carbon, made by the usual method of solution in hydrochloric acid. Although the method is tedious, because of the necessary treatment of the separated carbon with caustic potassa, alcohol and ether, the text-books seem to give it preference; and it is, perhaps, used more generally than the method of solution in dilute nitric acid. Solution in hydrochloric acid usually gives higher graphitic-carbon results than solution in nitric acid, and many, therefore, consider it more trustworthy, the inference being that the lower results obtained by nitric acid are due to the loss of some of the finely-divided graphite by reason of the oxi-

Jan 1, 1896

By Gluch KD

The current Mining Act has been the mechanism for administering and encouraging the State's mining industry through the 1970's up to the present. Although it has been subjected to considerable amendment there continues to be judicial challenge as well as criticism in relation to ambiguity of interpretation. Expansion of the mining industry and pressures placed upon "it by the ever increasing interaction with other land users have highlighted deficiencies in the current legislation and the need for a strong and progressive Act covering the rights and obligations of miners and their relationships with those outside the industry. - It is considered that the most positive results can be achieved by a complete redrafting of Queensland's mining administrative legislation.

Jan 1, 1987

By H. E. Hirsch

Propelled by the invention of the transistor at Bell Laboratories, germanium's unique properties have advanced our electronic world by many years. Germanium has found major uses in infrared optics, fiber optics and a revised vigor as a catalyst for PET plastic production. Other advanced applications are in various stages of development. The solid state electronics industry has been the driving force behind the accelerating demand for gallium since the late sixties. Past developments of substrates for light emitting diodes, lasers and magnetic bubble memories are paling in view of the current excitement over the use of semi-insulating gallium arsenide for high performance integrated circuits. This application requires gallium metal and gallium compounds of extraordinary purity.

Jan 1, 1986

By O. C. Carter, B. J. Scheiner

The Bureau of Mines is investigating the effects of rainfall and gypsum/cooling pond water on the rate of metal and nonmetal ion mobility through phosphogypsum stacks located in central Florida. Since leachate contains metal and nonmetal ions that have the potential for migration into surface and groundwater, laboratory column leach tests were conducted. Synthetic rainwater was passed through the column and metal and nonmetal ion migration was monitored. Similar experiments were conducted using a number of synthetic solutions which simulated a number of different compositions of gypsum/cooling pond water. Results indicate that within the first five pore volumes most of the mobile metals and nonmetals were removed.

Jan 1, 1992

By M. J. Sanzotti, C. J. Bise

This paper examines the potential for controlling longwall-induced subsidence by pneumatically backstowing waste rock into the void created by mining. The paper also examines scheduling the process as a unit operation of the mining activity. Based on a review of background literature and interviews with representatives of various mining companies, public-interest groups and state and federal regulatory agencies, a hypothetical case-study evaluation of pneumatic stowing at a southwestern Pennsylvania mine was conducted. The study indicated that current stowing technology cannot keep pace with the production potential of longwall systems in the United States. Further, at the mine used in this case study, concomitant stowing would reduce subsidence by only 50% of what would normally be incurred during full longwall caving, and the longwall coal-production rate would decrease from 3,630 t (4,000 st) per shift in the nonstowing case to 1,360 t (1,500 st) in the stowing case. A preliminary cost analysis reveals that pneumatic stowing would add from $5.79 to $11.57 per t ($5.25 to $10.50 per st) to the operating cost of producing coal at the case-study site.

Jan 1, 1997

By Richard A. Mullins, James J. Merle

Systematic sampling and analysis in coal-washing plants results in product control and economical operation. A well-organized laboratory system reduces operating costs and increases sales if the operating and sales companies make full use of information it supplies. The operating cost of a control laboratory is less than 1 pct per ton of coal produced. THE system of laboratory control as practiced by the Ayrshire group of mines was begun with the construction and organization of the first laboratory in conjunction with the completion of its first wash-ery in 1941. The primary purpose of this laboratory was to maintain a check on the quality of the coal produced from the washing plant. The laboratory was equipped to determine proximate analyses, float-and-sink tests, and screen analyses, and was staffed by a chemist. an assistant. and a technician. Members AIME, are Assistant Preparation Manager and Chief Chemist, respectively, Ayrshire Collieries Corp. and Subsidiaries, Danville, Ill. Joint AIME-ASME Fuels Conference. French Lick. October 1949. TP 2855 F. Discussion (2 copies) may be sent to Transactions AIME before June 30, 1950. Manuscript received Aug. 22, 1949. Soon it became apparent (1) that product control could be accomplished, (2) that a substantial reduction in operating costs could be effected by close control of coal losses in the rejects, and (3) that information furnished by the laboratory was of continuous value to the operating and sales companies. Consequently the laboratory function was expanded to supply them with additional data as required. As the parent company expanded and new mines were added, control laboratories were established at each mine equipped with washeries, and a central laboratory was maintained at one of the mines that was located equally convenient to all of them. A well-planned control laboratory assures production of a uniform, high-quality product. Whenever coal of substandard grade is loaded inadvertently, the sales company can be informed and the proper channel of distribution made. Conversely only constant and strict laboratory supervision can insure proper production of the various grades. Knowing the product, the producer can keep out of many customers' arguments that may be both awkward and expensive. Double checking between customers and mine laboratories have solved many disputes' Some nager insist On buying coal On the analysis basis only, with penalties for substandard coal and premiums for coal above normal quality. A substantial percentage of the coal sold by the Ayrshire group is of this nature. The usual procedure is for the customer to sample and analyze the coal as it is unloaded at the plant, and the mine laboratory samples it as it is loaded at the mine for subsequent analysis by the central laboratory. Only the unloaded moisture is considered, rather than the average of mine and plant moisture, and the buyer sends duplicate samples to the central mine laboratory for this determination. The average of the two analyses determines the price of coal at the mine. In this particular case, the laboratory plays an important part in increasing realization for two reasons: (1) every attempt is made to maintain plant efficiency and product quality as high as possible, (2) check on analyses and sampling by the buyer or seller.

Jan 1, 1951

By Richard A. Mullins, James J. Merle

Systematic sampling and analysis in coal-washing plants results in product control and economical operation. A well-organized laboratory system reduces operating costs and increases sales if the operating and sales companies make full use of information it supplies. The operating cost of a control laboratory is less than 1 pct per ton of coal produced. THE system of laboratory control as practiced by the Ayrshire group of mines was begun with the construction and organization of the first laboratory in conjunction with the completion of its first wash-ery in 1941. The primary purpose of this laboratory was to maintain a check on the quality of the coal produced from the washing plant. The laboratory was equipped to determine proximate analyses, float-and-sink tests, and screen analyses, and was staffed by a chemist. an assistant. and a technician. Members AIME, are Assistant Preparation Manager and Chief Chemist, respectively, Ayrshire Collieries Corp. and Subsidiaries, Danville, Ill. Joint AIME-ASME Fuels Conference. French Lick. October 1949. TP 2855 F. Discussion (2 copies) may be sent to Transactions AIME before June 30, 1950. Manuscript received Aug. 22, 1949. Soon it became apparent (1) that product control could be accomplished, (2) that a substantial reduction in operating costs could be effected by close control of coal losses in the rejects, and (3) that information furnished by the laboratory was of continuous value to the operating and sales companies. Consequently the laboratory function was expanded to supply them with additional data as required. As the parent company expanded and new mines were added, control laboratories were established at each mine equipped with washeries, and a central laboratory was maintained at one of the mines that was located equally convenient to all of them. A well-planned control laboratory assures production of a uniform, high-quality product. Whenever coal of substandard grade is loaded inadvertently, the sales company can be informed and the proper channel of distribution made. Conversely only constant and strict laboratory supervision can insure proper production of the various grades. Knowing the product, the producer can keep out of many customers' arguments that may be both awkward and expensive. Double checking between customers and mine laboratories have solved many disputes' Some nager insist On buying coal On the analysis basis only, with penalties for substandard coal and premiums for coal above normal quality. A substantial percentage of the coal sold by the Ayrshire group is of this nature. The usual procedure is for the customer to sample and analyze the coal as it is unloaded at the plant, and the mine laboratory samples it as it is loaded at the mine for subsequent analysis by the central laboratory. Only the unloaded moisture is considered, rather than the average of mine and plant moisture, and the buyer sends duplicate samples to the central mine laboratory for this determination. The average of the two analyses determines the price of coal at the mine. In this particular case, the laboratory plays an important part in increasing realization for two reasons: (1) every attempt is made to maintain plant efficiency and product quality as high as possible, (2) check on analyses and sampling by the buyer or seller.

Jan 1, 1951

By J. B. Conway

RECENT studies of first-stage creep data have led to a special least-squares procedure for use in calculating the Andrade creep-equation constants. This procedure is easy to apply, uses only experimental data, and yields results which do not vary with the individual making the analysis. Taking logarithms of the Andrade equation I = lo(1 +ßl1/3)ekt leads to In l = In lo + In(1 + ßl1/3) + kt A residual can then be defined as the difference between the logarithm of an experimental length value and the logarithm of a calculated length value. Following the usual least-squares approach differentiation with respect to 10 and k of the expression for the sum of the squares of the residuals leads to two equations which cannot be solved directly for the three constants involved. However, values of ß can be assumed and corresponding values of lo and k can then be calculated. Then the sum of the squares of the residuals can be calculated. For a certain value of ß this sum will exhibit a minimum value to identify the least-squares values for ß, lo, and k. An illustration of the application of the above least-squares approach is obtained by employing the creep data for lead originally presented by Andrade' in the development of the one-third creep law. A plot of the sum of the squares of the residuals as a function of ß is shown in Fig. 1 along with the corresponding lo and k values. The minimum is seen to occur at ß = 0.0143 from which lo = 39.149 and k = 7.27 x 10-5. Based on these results the Andrade equation for these lead data is 1 = 39.149(1 + 0.0143 t1/3)e7.27 x 10-5t compared to the equation I = 39.13(1 + 0.01457/l/3)e6.95 X 10-5t developed by Andrade (calculation procedure not given but was probably a graphical solution). Calculating length values using the above equations and comparing with the experimental length values, residuals corresponding to the difference between experimental and calculated length values can be obtained. The sum of the squares of the residuals can then be calculated. For the case of the least-squares approach a value for this sum was found to be 2.37 x 10-3 compared to a value of 3.47 x 10" for the equation originally proposed by Andrade. In other words, while the constants proposed by Andrade provide an excellent fit for the lead data, a still better representation is afforded by applying the least-squares approach discussed above. A similar result was obtained for the lead data at 162oc.l The least-squares approach led to 1 = 9.866(1 + 0.0497 t1/3)el.011 x 10-2t compared to the equation I = 9.94(1 + 0.0433 l1/3)e1.06 X 10-2t given by Andrade. In this case, too, the sum of the squares of the residuals is slightly smaller for the equation based on the least-squares approach. It should be pointed out that a double trial and er-

Jan 1, 1965

By Robin Phinney

Certain statements in this presentation may constitute "forward-looking" statements which involve known and unknown risks, uncertainties and other factors which may cause the actual results, pe1formance or achievements of the Corporation, or industry results, to be materially different from any future results, performance or achievements expressed or implied by such forward-looking statements. When used in this presentation, such statements use such words as "may", "would", "could", "will", "intend", "expect", "believe", "plan", "anticipate", "estimate" and other similar terminology. These statements reflect the Corporation's current expectations regarding future events and operating performance and speak only as of the date of this presentation. Forward-looking statements involve significant risks and uncertainties, should not be read as guarantees of future performance or results, and will not necessa1ily be accurate indications of whether or not such results will be achieved. A number of factors could cause actual results to differ materially from the results discussed in the forward looking statements including, but not limited to, the factors discussed in the Corporation's annual information form filed on March 9, 2011. Actual results could differ materially from those currently anticipated due to a number of factors and risks. These include, but are not limited to, the failure to obtain necessary regulatory approvals, including environmental approval, the failure to secure full project financing, the failure to implement the recommendations set out in the Technical Report, the failure to raise financing to implement the recommendations in the Technical Report, risks associated with the mining industry in general (e.g., operational risks in development, exploration and production; delays or changes in plans with respect to exploration or development projects or capital expenditures; the uncertainty of estimates and projections relating to production, reserves and resources, costs and expenses; and health, safety and environmental risks), decrease in potash prices and exchange rate fluctuations. Although the forward-looking statements contained in this presentation are based upon what management of the Corporation believes are reasonable assumptions, the Corporation cannot assure shareholders that actual results will be consistent with these fonvard-looking statements. These fon\?ard-looking statements are made as of the date of this presentation and are expressly qualified in their entirety by this cautionary statement. Subject to applicable securities laws, the Corporation assumes no obligation to update or revise them to reflect new events or circumstances. This presentation is a market update based on the Corporation's public disclosure and does not form a part of any offer of securities, or constitute a solicitation of any offer to purchase or subscribe for securities. Any purchase of securities in the company should be made solely on the basis of information contained in the Corporation's public record which is available on www.sedar.com .

May 1, 2013

By James P. Dorian

Like Russia and Ukraine, Kazakhstan is one of a few former Soviet republics well-endowed in mineral and energy resources (Fig. 1). Kazakhstan is the second largest newly independent Commonwealth state. It possesses major fuel and power centers, including 20 electric power facilities that operate on the more than 300 kt (330,000 st) of coal extracted daily. These power stations supply Central Asia, the Urals and Western Siberia with much needed electricity. Kazakhstan plays a critical role in Central Asia as it serves as both the regions' economic and political hubs. While Kazakhstan already contains a robust and diversified minerals industry, the government is actively pursuing foreign investment to boost production capacity and improve efficiencies in operations. A primary objective of the Kazak government is the expansion of metal processing facilities to improve the country's long-term export potential. Since 1991, international mining companies have found the investment climate of Kazakhstan relatively favorable. This is due to tremendous efforts by government officials to create sufficient investment legislation and a national minerals policy, while eliminating bureaucratic bottlenecks common to most other former Soviet republics.

Jan 1, 1993

By Michael F. Roach, Joseph K. Cavey, Gary E. Taylor

A rigorous horizontal drilling and chemical grouting program was specified beneath the Hollywood Freeway (U.S. Route 101) section of Los Angeles Metrorail Contract C-311.Twin 6.67-m (22-ft.) diameter starter tunnels were to be conventionally mined through amixed alluvial and bedrock face consisting of silty sand, gravel, and weathered sandstone and siltstone of the Topanga Group. The contact between the alluvium and bedrock dipped toward the Crossover Excavation where the horizontal drilling and grouting operations were performed. The intent of this grouting program was to stabilize the mixed face to minimize ground loss and surface settlement, and to reduce groundwater inflow into the tunnel headings. Given the highly variable mixed face conditions, horizontal drilling up to 86 m (284 ft.) resulted in upward trending trajectories which likely followed the bedrock contact. Chemical grouting was performed in a primary, secondary and tertiary, three dimensional sequence. Evaluation of the primary and secondary grouting parameters indicated where tertiary grouting was required. Grouting pressures induced a small rock failure at the tunnel heading as well as increased stresses on the tiebacks of the excavation.

Jan 1, 1997

By P. Muduli, Y. Xi, T. M. Yegulalp, A. J. Arias

A short review of current practices and recent developments is followed by a description of a newly developed approach for solution of the optimum, ultimate pit limit problem. The new approach utilizes network modeling of the problem for solution by maximum flow algorithm. The latest developments in the implementation of maximum flow algorithm present significant time and memory savings as compared to initial development due to Ford and Fulkerson (1956). Results of a series of computational tests are presented to demonstrate how this approach performs as compared to the well-known Lerchs Grossman algorithm. It is also shown that the solution by the new method automatically includes several optimal solutions based on a predetermined number of benches to be included in the analysis.

Jan 1, 1994