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By John Newby, Ulf Gwildis, Fred Marquis

From the Brightwater Conveyance System in Seattle to the Second Narrows Water Supply Tunnel in Vancouver, BC, the design and construction of deep-lying tunnels in the Pacific Northwest often require the incorporation of deep portal shafts. Alluvium overlying marine and glacial deposits combined with the high regional seismicity is the common geologic setting. The latest example illustrating the development of shaft design for this scenario is the 40-m-deep shafts of the Annacis Island Wastewater Treatment Plant New Outfall System. The main components of the shafts include the initial lining, providing the excavation support system to be used for launching and receiving a 5-m-diameter TBM; and the final lining, designed to withstand all static and seismic loads and to remain viable for the intended design life. This paper presents design and construction considerations for these shafts against the background of and lessons learned from past project experiences.

Jun 13, 2021

By Arne Paus-Jenssen

The potash industry in Saskatchewan has recently been the focus of much new legislation at the provincial level and, along with other mining industries in Canada, also subject to changes in tax legislation at the federal level. As a result, the industry presently operates under (a) provincial production controls, a prorationing scheme; (b) a new provincial reserve tax on potash only and; (c) a new federal income tax applicable to all mineral industries. The prorating scheme dates back to 1970 and emerged as public policy because of the excess supply situation faced by the international potash industry towards the end of the sixties. This caused special problems for new mines in Saskatchewan and the provincial government decided to intervene. The new tax legislation at provincial and federal levels, both introduced within the last four years, reflects a belief that insufficient revenues accrue to the public sector from natural resources. All mining industries in Canada, including the potash industry, have had their tax positions completely reversed during these four years. Traditionally the mining sector in Canada has been a recipient of substantial tax incentives and has enjoyed low tax rates. This has changed and the mining sector is now one of the most heavily taxed sectors in the economy. In addition, the mining sector has moved from a situation where its rapid development was favoured by governments to a situation where this is no longer the case.

Jan 1, 1976

By R. H. Grau, C. D. Taylor, A. L. Martikainen

Utilization of belt air in underground coal mines has been discussed extensively during the last decade. The Final Report of the Technical Study Panel on the Utilization of Belt Air and the Composition and Fire Retardant Properties of Belt Materials in Underground Coal Mining formed by the Mine Improvement and New Emergency Response (MINER) Act of 2006 recommends research on leakage, use of booster fans, and escapeway safety. This paper discusses the role of ventilation modeling in evaluating primary escapeway pressurization in a three-entry development system to improve emergency escape in a coal mine using belt air. The intake entry of the National Institute for Occupational Safety and Health (NIOSH) Bruceton Experimental Mine was pressurized using a 1.1-m (42-in.) diameter, 37 kW (50 hp) fan. The work details air movement in the simulated three-entry system and the resulting leakage patterns. Three mine ventilation software packages were compared to analyze their performance in predicting the airflows and leakage conditions with different fan settings. NIOSH researchers found that the measurement results correlated well with the results of modeling.

Jan 1, 2010

By D. M. Steelman

Digital systems have been employed in industry as an aid in process evaluation and control for about 20 years. The earlier systems were quite simple and did little more than periodically scan a multitude of process variables, perhaps comparing them to alarm limits, and print out the results. As time passed, the needs of industry and the imagination of process engineers became more demanding. Rather than perform only alarm checking and logging, operating guides were generated to help the operator gain optimum performance from the process. Eventually, systems were entrusted with the job of manipulating the set points of the local analog control loops in a (DDAC) digitally directed analog control mode. Today digital systems are used to gather all-the process information, including both analog and digital variables; to make the necessary data manipulations; and to control the process end elements in a (DDC) direct digital control mode. During these years of transition from the very simplest systems to the complex systems of today, the demands upon the system engineer have been every increasing. The process engineer has required, among other things, more computational ability at high speeds, faster input and output rates, greater flexibility, better communication facilities (man-machine interface), (process oriented software), and finally, greater reliability at lower cost.

Jan 1, 1969

By Lennart Bergstedt

Boliden Aktiebolag, the prime base metal mining company of Sweden, annually treats some 11-12 million tons of sulphide ore in nine concentrators. Its first flotation plant was established in the early thirties for the complex Boliden ore. Since then, the number of mines and plants has gradually increased. Considerable effort has been devoted to the development of all phases of the technology of ore prospecting, mining, milling, smelting and refining. This has been necessary due to the complex and low-grade ores. The development of concentration has mainly been directed toward the arts of grinding and flotation. During the forties and fifties, open-stage fine crushing followed by two-stage grinding in rod and ball mills with cyclone classification was successfully introduced and used throughout the plants. The increasing cost of grinding media led to studies of an autogenous grinding technique as early as 1945. Basic test work commenced during the early fifties, with a. number of ores tested for pebble grinding. In 1956 a new pilot plant was built, with equipment installed for the continuous testing of pebble grinding and, later, for primary autogenous grinding of run-of-mine ore. The intensive test work showed that pebble grinding was feasible in almost all of the plants. At this early stage of testing, however, the merits of autogenous grinding could not be fully evaluated. As a. consequence the rod mill/ball mill grinding systems were converted to rod mill/pebble mill systems whereever possible. In parallel with the converting of grinding systems the development work concerning the merits of autogenous grinding went on. The major result

Jan 1, 1977

By V. Russel Burkhart

One of the most difficult items to justify economically on any budget is a training program. The costs can easily be identified--primarily the cost of the program and the inconvenience and cost of filling in for the men taking the training by working other personnel extra hours at overtime rates. Operating efficiency, higher productivity, increased plant availability, development of confidence, improvement in morale and less absenteeism are only a few of the benefits which far exceed the costs. A good preparation plant training program can accomplish more in 5 weeks than can be accomplished in five years of on-the-lob operation. During recent years, coal preparation plants have become more sophisticated and complex as the specification for coal used by electric utilities in their power plants have required improvements in coal quality to adhere to air quality regulations and to improve boiler performance and reliability.

Jan 1, 1981

By Lyle A. Hale

The subject area known as upper Dry Valley is located 15 miles due east of Soda Springs in Sections 14 and 23, Township 9 South, Range 44 East, Caribou County, Idaho. The railroad extending from Soda Springs to its terminus at El Paso's Maybe Canyon mine is 8z miles to the north in lower Dry Valley. Initial data derived from trench work in 1962 revealed a variety of econom¬ically significant alterations of the phosphatic beds related to the rather unique geomorphic development in the northern part of phosphate lease 1-012989. It was apparent that such conditions, while valid for near-surface beds in a strike direction, would be misleading if projected to the proposed depth limits of strip mining. Consequently, a subsurface mapping program was initiated in 1963 to determine: (1) the depth and horizontal extent of weathering and related phe¬nomena, (2) the depth, thickness, and quality of ore beds and intervening strata, and (3) structural geology as a guide for mining procedures. Successful use of a scintillometer in 1956 to detect the subcrop position of phosphate beds in the Smokey Canyon area of southeastern Idaho led to the conclusion that gamma radiation surveys of drill holes could be a useful aid in subsurface mapping. The objectives of this paper are: (1) briefly to describe geologic features characteristic of the phosphate lease area and (2) to demonstrate the practical application and theory behind gamma radiation logging as an effective tool in the economic evaluation of a phosphate lease.

Jan 1, 1969

By Fritz F. Prugger

This paper considers some of the main aspects of underground mining in the flat, rich, but deep lying deposits of Saskatchewan. It briefly describes the pertinent geological features as they relate co mining and the practical de-stressing techniques used to allow productive extraction in the high stress environment present in many of the province's mines. Fining layouts, materials handling and the evolution of some of the world's largest mining equipment are examined.

Jan 1, 1980

By Calvin R. Davis

The bucket elevator is probably the oldest known form of conveyor. Its history can be traced back to the days of Babylon where wicker baskets lined with a natural pitch and fastened to ropes operating over wooden sheaves turned by slaves, were used for the elevating of water into irrigation ditches. It is not unnatural for the bucket elevator to be the first in history, for even today engineers and designers recognize that well designed, correctly applied bucket elevators offer unequaled advantages over other bulk material elevating methods. The bucket elevator's vertical design saves valuable floor space. It provides flexibility of machinery layout with lowest initial capital expenditure, which is its principal advantage. While the advantages of the bucket elevator have long been recognized, there has been a tendency to lean away from its use because of high maintenance without reliability. CHAIN Belt Company found that the bucket elevator, if correctly applied, can be built to be as dependable and reliable as any other piece of machinery in today's modern processing plants. It is not difficult to understand why the bucket elevator is looked upon sometimes as a necessary evil in the material handling system. Very little has been published or written about the specific use or application of bucket elevators other than in manufacturers catalogs. Most of today's elevator application was set forth at the turn of the century by Hetzel (1). There have been many improvements made in the manufacturing techniques of elevator components, improvements in material selections, all which can be used to improve today's bucket elevator. To best understand the improvements which have taken place recently in the design and application of bucket elevators, an understanding of basic elevator principles is desirable. In general, it can be said that bucket elevators are classified into two basic types : (1) centrifugal discharge and (2) continuous. Elevators in use today are either of the centrifugal discharge type or the continuous type, or a combination of both in special applications.

Jan 1, 1958

By Thomas E. Ban

D-LM at Mobile The qualified success of iron ore pelletizing processes has influenced considerations for production of highly beneficiated fur¬nace charges. Such beneficiation would necessarily involve some forms of chemical and perhaps thermal conversion for production of prereduced pellets, preheated pellets, precalcined pellets, and perhaps pellets which contain all of the above features as preheated, prereduced, precalcined products. This type of furnace burden will be adapted within a new ironmaking process to be activated commer¬cially during the latter part of 196$ in Mobile, Alabama. This process will integrate a new pelletizing system with an electric smelting furnace and the pellets will be comprised of a composite charge blended from metallurgical proportions of iron ore, coal, and limestone. The plant as designed and constructed by McDowell¬-Wellman Engineering Company will feature the D-LM process and will be owned by McWane Cast Iron Pipe Company. It is significant to

Jan 1, 1968

By Spencer R. Titley

Porphyry copper deposits in the southwestern Pacific area represent relative newcomers to the growing number of occurrences of this mineral deposit type. In addition to firmly establishing the importance of this region and its potential influence within the framework of world copper resources, the deposits of this region are significant from a scientific point of view because of their close relationship to the phenomena of Island Arc evolution. Since the discovery of Panguna on Bougainville in 1964, the list of prospects, proven and unproven, and developments, has grown to more than twenty and the number continues to increase. At the time of this writing, the number of prospects is imperfectly known but the following localities and numbers are fair minimum approximations: Manus (Admiralty Islands) (3); New Britain (5); New Ireland (1); Guadalcanal (2); New Guinea Highlands (6); Misima (1); and Fiji (2); Proven prospects are present in the new Guinea Highlands (2); one deposit is being developed in Test Irian, and one orebody, on Bougainville, is in production. This summary paper concerns a discussion of some of the geological characteristics of producers, developments, and prospects on the Islands of Nets Guinea, New Britain, Bougainville, Guadalcanal, and Manus. I am not aware of publishable data for Misima or Fiji. As so many variables ultimately determine whether or not a porphyry copper occurrence becomes an orebody, not the least of which is geography, this summary treats the characteristics of these occurrences which alloy; their assignment to the porphyry copper category. For purposes of this discussion, I have considered those copper occurrences which are apparently genetically related to talc-alkaline intrusions and in which the content of copper has been upgraded 50 to 100 times the Clarke for that particular host rock. Some of these occurrences are shown on Figure 1.

Jan 1, 1973

By P. Nelson, R. O’Connell, J. Rostami

Tunnel boring machine (TBM) system utilization is a critical factor for predicting machine performance. The process of estimating machine performance, including rate of penetration (ROP) and machine utilization (U) must incorporate an understanding of site geology, TBM specifications and site management. The study herein presents a preliminary analysis of the different activity time and downtime components from hard rock TBMs at two project sites to evaluate their impact on machine utilization. A comparison of crew experience, first between shifts and then between projects is included to analyze its effect on utilization and downtime. This work presents the sensitivity of the utilization factor to selected activities in the projects and the impact of geology and site set-up/logistics on machine performance.

Jun 13, 2021

By R. J. Sweigard

Deep tillage is used widely as a Means of alleviating excessive soil compaction. There has been some concern that the voids created by deep tillage may collapse before a more natural soil structure develops, resulting in recompaction subsequent to deep tillage. A laboratory investigation was conducted to determine the feasibility of pneumatically injecting organic material into the voids during deep tillage to prevent any significant recompaction from occurring. Various amendments were injected into the soil in the laboratory using a small-scale ripping and injection system. Measurements were made of selected soil properties to evaluate the feasibility of this method.

Jan 1, 1993

By William F. Lawrence

Research performed by the West Virginia University Coal Research Bureau under the sponsorship of the U. S. Bureau of Mines has demonstrated that coal-ash can be converted into mineral wool insulation of a quality equal to commercial grade mineral wool. An unexpected benefit has been gained due to the discovery that the usual and costly fluxing agents employed when using conventional raw materials are not required when producing mineral wool from coal-ash. Because coal-ash sources are commonly located close to mineral wool marketing areas and because mineral wool is seldom shipped far as a result of its low weight and high volume, the use of coal-ash may offer the mineral wool producing industry profitable opportunities. Moreover, coal-ash produced from experimental limestone based air pollution control processes also yields high quality mineral wool which may aid in retarding corrosion of metals contacted by the wool. In addition, internal fluxing effects and possible sulfur oxide utilization could provide economic advantages to the use of these "modified" ashes.

Jan 1, 1969

By A. S. Hall

Significant pyrite often does not dissolve in the Sobek (1978) nitric acid extraction; therefore, the standard conservative approach is to estimate pyrite using sulfur present in the sum of the nitric acid and residual sulfur fractions. Alunite, when present, appears as residual sulfur. Because alunite does not generate acidic effluents, overestimation of AGP can occur if all residual sulfur is assumed to be undigested pyrite. Evaluation of 16 samples from the Florida Canyon Mine revealed that petrographic examination coupled with a modification of the Sobek method to include a 6 hour hot (250°F) 'nitric acid extraction resulted in a more accurate estimation of AGP.

Jan 1, 1999

By W. C. Lacy

Traditionally Australia has been a leader in underground mining methods with world standards being established at Mount Isa, Broken Hill, Kalgoorlie, and Mount Lyell. With decline in higher-grade reserves and discovery of a multitude of near-surface oxide gold de-posits attention has shifted to bulk mining of low-grade gold ores by open pit methods, heap leaching and activated carbon recovery of gold values. The paper examines historical change in mining philosophy and the economic effects of isolation.

Jan 1, 1993

By S. S. Xue

A study has been conducted to remove iron from sulfate solutions using Eichrom's Dipex® extractant, P,P?-di(2-ethylhexyl) methanediphosponic acid (H2DEH[MDP]). It is found that this extractant can effectively and selectively extract ferric ion from highly acidic solutions. Ninety-nine percent of the iron was extracted from a simulated feed solution in a single stage. The separation factor, Fe/Zn, was 10 6 Over 90% of the iron in a loaded organic can be recovered in an aqueous solution by reductive stripping. This paper presents the experimental results. A new process for iron removal using Dipex extractant is described and discussed.

Jan 1, 1999

By T. F. Dumm

With increasing interest in the physical cleaning of fine coal, there is a need for extension of the sink-float analysis procedure to finer sizes. Problems arise, however, in ensuring complete dispersion of the particles in the heavy liquids. A procedure has been developed in which surfactants are used as dispersing agents and solids concentration is minimized (using a simple formula to estimate the minimum weight needed for statistical reliability). Using centrifuges to increase separation rates and sub-sieve particle size analysis of the specific gravity fractions, a complete size-specific gravity distribution can be obtained. Analyses have been performed on coal samples as fine as -10 µm.

Jan 1, 1987

By Robert Moore Lewis

Extensive exploration is being undertaken throughout the world in search for heavy minerals, particularly rutile and other titanium minerals. The federal government is sponsoring research involving rutile ores and recovery of stockpile-grade concentrates from domestic sources. Producers are being forced to turn to deposits with a heavy mineral content as low as 0.50% (essentially rutile and zircon). The North Carolina State University Minerals Research Laboratory investigated the possibilities of recovering heavy minerals from the amine tailings of the Texasgulf Inc.'s phosphate plant at Aurora, North Carolina. One laboratory beneficiation procedure using gravity, electrostatic and magnetic processes, resulted in the recovery of 78.7% of the heavy minerals in the amine tailings. Based on this percentage recovery and the present rate of phosphate mining, approximately 13,000 tons per year of heavy minerals (principally ilmenite and zircon) with a potential value of approximately $1,045,000 (1977) could be recovered. The economic potential for recovery of these heavy minerals appears to be favorable. A flotation procedure for up-grading the heavy minerals content in the amine tailings has been developed at the Laboratory, which could allow for concentration of heavy minerals and storing them in tailings area other than main tailings for future processing.

Jan 1, 1978

By Ross K. Digby

The Victorian Tunnelling Centre (VTC) has evolved its purpose from purely training workers, to a tunnelling industry education city. The VTC has now focused its activities on the areas of technology; education and training; applied research; and career education. were identied as the hus around which activities would e conducted to create a tunnelling industry education city. The VTC provides ustralias tunnelling industry with an education facility that not only provides laour training, ut enales the industry to come together to meet, participate in product launches, undertake research, work with new technologies and promote tunnelling careers.

Jun 23, 2024