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By Gilles Recher, Jörg Riechers, Albert Lueghamer

"INTRODUCTIONIn view of a global trend towards urbanization, more and more trunk sewers and combined sewer overflow tunnels (CSO) with medium to large diameters and the corresponding link sewers are currently built and under design. Shielded tunnel boring machines using segmental lining as tunnel support represent an efficient solution for construction of new wastewater and supply tunnels. Especially in the field of sewers, the durability of concrete structures both exposed to any groundwater present on its exterior and to aggressive waste water as well as gases on its interior is a key requirement. Despite thorough research on segmental lining and mechanized tunneling machinery, conventional thermoplastic liners show comparatively minimal progress in terms of practical advancements. This is in contrast with the development of the latest segment embedded high density polyethylene (HDPE) system. Based on experiences achieved, this paper discusses the latest development of an integral protective lining system in respect of material characteristics and its adaptability to both project and customers’ demands. Reviewed performances, as the bondage behavior of the embedded HDPE system at axial stress loads due to acting thrust cylinders during ring build as well as the ability to drain pressurized water behind the embedded membrane, tested at full scale segments, are also presented. The paper is round off by presenting first details of sewer projects endeavoring to utilize this cutting-edge solution for an integral concrete protection, which will be commenced beginning of 2016.CASE HISTORIES ENCOURAGE ADVANCEMENTS Past experience has shown that unprotected concrete surfaces as well as chemical based linings such as coatings, sprayed linings and cured in-place-systems cannot reach the desired life times. Also the fact that in deep tunnel sewer system hardly maintenance is possible, a durable and maintenance free system is required which only can be reached by applying mechanical anchored HDPE (CPL)."

Jan 1, 2016

By D. Belin

Treatment of dilute acid mine drainage and similarly polluted water is becoming increasingly complicated. The pressure of economics is now exacerbated by legislation which classifies as hazardous waste the precipitates from conventional lime treatment plants. Since acid mine drainage invariably contains sulfate ions, one solution is to use anaerobic Desulfovibrio type bacteria to reduce the sulfate into sulphide ions which could then be used to precipitate out the heavy metals. Results are presented for both batch flask cultures and continuous column tests. Compost was used as the bacterial substrate in the column test which simulated heaps. Conditions changed from aerobic to the required anaerobic deep in the columns. Polluted feeds (up to 700 mg/l zinc) gave effluent containing well below I mg/l zinc over extended periods. Direct transfer of sulphide ions through a stream from an isolated container of bacteria is a good alternative.

Jan 1, 1991

By A. W. Randall

Geological Aspects of Ore Reserve Estimates of Pine Point District Zinc- Lead Deposits, N.W.T. Zinc-lead ores of the Pine Point District, Northwest Territories, Canada are hosted in paleokarst cavities within a Middle Devonian carbonate barrier complex. Of the nearly 100 deposits found, most are irregularly distributed along two main regional stratigraphically controlled trends. The ores, which occur predominantly as open space filling, form deposits most of which average one million tonnes in size with an average grade of 10% combined zinc plus lead. Geological features related to karsting control not only distribution of deposits but also their shape, size and grade. The higher grade ore in these deposits generally occurs in a relatively small core area. Consequently, accuracy of reserve estimation is dependent on drill hole density and understanding of karst geometry. Several case examples will be reviewed to demonstrate the relationship between shape, size and grade of deposit, geological reserves and drill hole density, along with a discussion of geological ore reserve estimation methods.

Jan 1, 1985

By Richard Campbell, Claire Pirona, MEHMET KIZIL, Ismet Canbulat, Stephen Giese, Ravindu Goonawardene, Edward Steed, Serkan Saydam

The Australian longwall mining industry spends millions of dollars per year on proactive and reactive ground consolidation applications across most of the operations currently in production. The design and effectiveness of the applications and products vary widely and are based predominantly on-site precedence or what were considered successful applications at other sites in similar situations. In the continual improve the effectiveness of how consolidation products are used and when by enhancing our knowledge of the mechanical properties of products used in underground coal applications and applying this increased understanding to geotechnical design. One of the current challenges to further developing more appropriate and accurate geotechnical design methods for consolidation activities is the lack of standardised materials testing and knowledge of rock mechanics data on in situ performance. The lack of industry standardisadesign of consolidation programs, with a reliance on experience-based guidance for rockmass consolidation design. consolidation products. The program was designed to provide the industry with a set of geomechanical property index tests and a data set that can be utilised by rock mechanics engineers as baseline information for product evaluation and engineering design. The laboratory work undertaken is critical to understanding the exact small-scale mechanical properties of these products and testing was carried out at Monash University for various states of curing of each product. Recognising that the speed at which a mixed product develops its desired properties to act as a support element in underground coal mines is critical to its serviceability. This paper presents the testing rationale proposed, the testing results, and a framework for how the data set can be used to improve the engineering basis for ground consolidation design, in terms of expected rockmass performance under various mining conditions and application parameters.

Jun 25, 2024

By J. M. Keane

SMEThis loaner is concerned with important criteria relative to the design of small flota¬tion concentrators. For the purpose of this discussion a small flotation concentrator is defined as a facility having a designed ore feed rate of 1,000 metric tons per day (MTPD), or less. The decision to design and construct a small flotation concentrator is the culmination of a series of logical steps relative to the ex¬ploitation of a potential ore body. The information required for a rational and timely decision regarding plant design and construction is usually contained in a feasibility report. The information required in a thorough feasibility report has been summarized (1) (2) as follows: Type of mine or plant and proposed daily, monthly, and yearly production of all intermediate and final products. Quantity of indicated ore reserves. Location of project illustrated by a map showing surroundings, trans-portation facilities, and existing utilities.

Jan 1, 1980

By S. B. Bhagwat

The United States has abundant coal resources that could last at least another century. and probably longer at present consumption rates. Geographically, the coal resources are distributed over the entire nation including Alaska, although there are no coal deposits in the highly populated areas on the two coasts. This allows free access to the coal, but makes transportation more expensive. Not all coals can be utilized equally because they differ vastly in quality. The sulfur content of coals, considered as the most detrimental acid rain-causing element, varies from as low as 0.3 percent in some areas of the western U.S. to 5 percent or more in parts of the Midwest. The chlorine content, which causes corrosion of plant hardware, also varies regionally. The 1990 amendments of the Clean Air Act of 1963 (CAA) require that emissions of sulfur be restricted and rolled back in two stages by the year 2000. There have been a number of reports expressing concern about the future of the industry in the states where high sulfur coal is produced. The remedies devised by the federal government and many coal-producing states in the past to "se-cure" the future of the regional coal industries have focused on the physical task of removing sulfur rather than the economic challenge of doing so at a cost that will enable high-sulfur coals to survive and compete. The past remedies, generally, were not specific enough to account for the characteristics of regional coal deposits and did not look at the coal market as an integrated national and international entity. The State of Illinois has, in recent years, taken a more comprehensive approach to the solution of the problem.

Jan 1, 1992

By T. R. Ley

"RELIABILITY & SAFETY – TOGETHER. REALLY? I was starkly reminded of the challenges facing by the coal industry while talking with a number of senior mining executives. One said to me: “Safety is the #1 priority in our organization but of course, dollars are very, very important!!!” A coal mine worker at the Bluefield Coal Show claimed: “We know our equipment is bleeding hydraulic fluid all over the place but all that matters is getting the coal out”. We all understand. We want our people to go home safely at the end of the day but the coal industry is bleeding – fluids, dollars and real blood. An issue getting plenty of buzz these days is equipment reliability – in mining too! Achieving an optimal return from the massive investments in equipment is a critical requirement for success within a capital intensive industry like coal mining. You can cut costs by scrimping on maintenance, scavenging used parts and downsizing. Or, you can save money by being smarter with your asset management processes. Can we afford to spend money on both safety and reliability? Is one more important than the other? Many leading edge companies from a variety of industries will tell you that you can’t just cost-cut your way to profitability - or even survival. You need to systematically improve the effectiveness of your business. Do reliability and safety both have a place in improving the performance of the coal industry? According to Ron Moore, of The RM Group, the answer is emphatically YES! Ron says: “If you believe in safety, then you MUST believe in reliability and, more importantly, have the appropriate policies, systems, practices and measures in place. If you want lower costs, you must get your processes right. Simple cost cutting will remove resources from your system without changing the underlying system design, and performance will likely deteriorate.” Figure 1 shows the 5+ year results of a large manufacturing company. When plants are running well (high Asset Utilization), then injuries are less likely. Figure 2 plots data from a number of manufacturing plants. If you want sustainably lower costs get your reliability processes right. But these are manufacturing companies, not coal mining operations! It doesn’t matter. The fundamentals still apply. Mining industry thought leaders tell us that manufacturing is 20-30 years ahead of us and we need to learn from them – and do so quickly. Leading companies, no matter the industry, think in terms of operational excellence. They see this as the meshing of people, process and technology to achieve optimal results. Safety and reliability go hand-in-hand. People and equipment are different – but only to the extent that each requires its own relevant, but related, policies, practices, systems and metrics to achieve effective performance."

Jan 1, 2016

By Walter C. Labys

This paper reports on recent modeling efforts to analyze the eastern U.S. steam coal market with a cross-sectional econometric as well as a quadratic programming approach. The background to coal modeling is examined first. The particular aspect of the steam coal market to be modeled are then presented and the corresponding coal model described. Both empirical results and rigorous mathematic pertubation analysis are presented. Conclusions are then drawn regarding potential modeling applications in the policy area.

Jan 1, 1979

By Jacek Galas, Stanislaw Lenczowski

The image of the flotation froth surface in the mineral processing plant contains the information about its composition. This information can be very useful for a technological process automation. Images, captured in the optical part of the measurement system were read by the computer, then were transformed and analysed digitally. The set of image parameters, extracted from an image transforms, was evaluated by statistical analysis. The recognition algorithm constructed in this process allowed to estimate the froth composition.

Jan 1, 1995

By K. T. Valsaraj, L. J. Thibodeaux

Solvent sublation, the separation process for the removal of two hydrophobic compounds (penta- and trichlorophenols) from the aqueous phase, is discussed, as is a steady-state mathematical model for fire process. Solvent Sublation "'as conducted in a continuous countercurrent mode. The underlying mechanisms, theory and experimental details on the effects of process variables on removal efficiency are reported.

Jan 1, 1994

By K. N. Han, X. Xie

The dissolution behavior of palladium powder in thiourea solutions was investigated. The variables studied were temperature, stirring speed and the concentrations of thiourea, acid and ferric ion. Palladium was found to be soluble in thiourea solutions in the presence of an oxidant such as ferric ion. The dissolution of palladium in thiourea solutions was believed to be chemical-reaction controlled, with an apparent activation energy of about 25.3 kJ/mol.

Jan 1, 1997

By Richard A. Bideaux

During 1977 and 1978, a comprehensive study was made of the drill-hole data obtained by Urangesellschaft, USA, from their Juniper Ridge, WY, uranium deposits. This included uranium grade data acquisition, application of a variety of mineral deposit modeling techniques, and estimates of minable reserves, which pointed towards a possible production decision.

Jan 1, 1979

By Clarice L. Amaral, Ricardo Melamed

Clay-coating has been used as an environmental technology tool for the immobilization of toxic elements. The mechanisms of arsenate retention in clays suggest that not only the system pH is of fundamental importance in the process but also the character of metals and ligands that compose the electrolyte system. The goal of this study was to investigate the interactions between system pH and electrolyte ions on the retention of arsenate in an Oxisol soil. The sorption of arsenate decreases with the increase in system pH, reflecting the competitive sorption of arsenate with OH groups. Solutions containing Ca tend to favour the immobilization of arsenate in a relatively broad pH range.

Jan 1, 1998

By S. P. Brown, J. E. Worthington

Increasingly, exploration geology seems to be growing into a practice overly separated from production geology, yet the eventual purpose of exploration is a producing mine. To help in the search for new deposits, exploration "lessons" will be drawn from the papers given at the Fall AIME Applied Geology Symposium. In addition, examples will be re-emphasized to show how early observation of matters now routine to mine work (for example, hydrology, rock mechanics, oxidation state) can help increase the effectiveness of exploration.

Jan 1, 1992

By D. D. Misra

Though computer simulation of coal beneficiation has been in use for nearly two decades the models used in the programs for the simulation of the crushing processes concentrate mainly on the size distribution. This paper suggests the use of an empirical equation approximating to the cumulative probability or error function for the simulation of the liberation process in coal crushing. The algorithm outlined here can be incorporated in a computer program already having a size distribution model.

Jan 1, 1989

By K. A. Natarajan, K. S. N. Murthy

Growth of Thiobacillus ferrooxidans on pyrite mineral surfaces and in 9K leach media was studied through estimation of bacterial protein in the different phases. Bacterial attachment was found to be governed by particle size of the mineral, period of incubation and by stationary or agitation conditions used during incubation. Increased bacterial growth in the liquid as well as on the solid phase was observed with decreasing particle size and increasing incubation periods. Increased bacterial attachment to pyrite mineral surfaces was observed to promote iron dissolution.

Jan 1, 1993

By R. K. Singhal, D. B. Stewart

A variety of equipment is being used for roadheading and tunneling in the mining industry. In United States drum-type continuous miners are used most extensively. In Europe and Canada mine roadways are driven mainly by roadheaders. The application of tunnel boring machines to coal mining is somewhat recent. Such machines are however being used on major projects driving main mine entries.

Jan 1, 1985

By Georgene Renner, Chee Theng, William Gleason

"A walk through the exhibit hall or a glance at the technical programing that was offered at the 2019 SME Annual Conference & Expo and CMA 121st National Western Mining Conference in Denver, CO, Feb. 24-27 makes it evident that the mining industry is an innovative one that is on the cutting edge of technology. However, a glance at the nearly 6,700 attendees of the conference and it is also evident that while the industry is moving forward at a rapid pace in some areas, it is lagging behind in terms of diversity, both in gender and ethnicity.At Monday morning’s keynote session, Hannah Ubi, a millennial and a public speaker who joked that she is the proud owner of a sixth-place swimming trophy and a number of participation medals, addressed a full house that consisted of many men with gray hair or balding heads. The issue of an aging workforce that is rapidly being depleted by retirements is not a new one for the mining industry. In fact, it has been a concern for the industry for more than a decade. The central question has long been, “when the current senior-level people begin to retire, how do we replace them, and how do we fill the knowledge gap that is walking off into the sunset?” SME has been on the front lines in searching for solutions to the impending problem and, along with industry partners, has worked hard to develop programs that will address these issues. Among other efforts, the Society has developed a Ph.D. fellowship program to encourage people to remain in academia to teach the next generation and to help train the next generation to take over in the private sector.“The SME Foundation’s Ph.D. and Career Development Grant program is exceeding expectations at this point with two Ph.D. students graduating and taking a position in academia and two professors achieving tenure,” SME Executive Director Dave Kanagy said during the conference.The Society’s Minerals Education Coalition (MEC) has done its part to help educate future generations about the mining industry with initiatives like EngineerGirl, the Boy Scout Merit Badge and Move Mining, the Shark-Tank-style competition that was held on Monday with five finalists competing for the top prize (ME, April 2019, page 53)."

May 1, 2019

By Shinichi Konda, Gary Nishimura

"Thousands of years ago large glaciers carved much of the landscape in Puget Sound, depositing abrasive and granular soils including cobbles and boulders along with layers of clay and sand. Tunneling in this geology – common throughout much of the northern and Midwestern U.S. – is challenging and can be unpredictable. The use of pressurized face tunneling, most commonly with EPBs and slurry type machines, has made excavation in this geology more efficient, but difficulties still remain. Through analysis of recent projects in Seattle, Washington, USA, the authors draw conclusions as to the best TBM designs and operational parameters for this variable, abrasive and often difficult ground. Performance data is analyzed with an eye towards advancements that could further improve TBM tunneling in glacially deposited soils. INTRODUCTION Over the past several ice ages, extensive glaciers reaching across much of North America transported large amounts of soil and rock as they moved across the land. The substantial weight of the ice sheets mixed together a wide range of soil types along with a variety of rocks and boulders of all sizes. Many rock formations were reduced to pebbles or particles containing highly abrasive characteristics. Any boulders able to survive were generally comprised of harder materials which were scattered throughout the soil. This highly variable mixture of abrasive soils and high strength boulders can be found in many areas across the Puget Sound and other regions of the country. Wherever they are encountered, they often create a difficult and unpredictable mining environment for both equipment design and operation. Modern TBMs are optimized early in the design process for specific types of geology, and unexpected conditions can require extensive modifications. In addition, several operational parameters need to be adjusted to balance ground characteristics, and advance rates can be significantly affected in mixed and rapidly changing soil conditions. Both EPB and slurry machines can be used successfully in these conditions, provided their respective operating criteria are met. Ideally, an EPB is operated with a relatively thick muck consistency, which accommodates moderate changes in soil permeability and maintains a reliable pressure differential through the screw conveyor. However, this also causes higher wear on rotating components and requires more energy at the cutterhead. Alternatively, slurry machines typically operate best with a more fluid muck consistency that can be easily pumped through the extensive piping system. This tends to reduce the wear on the cutterhead and the power requirements of the cutterhead drive system, but also makes the machine more sensitive to changing soil conditions. Generally, the slurry piping system is also more capable of controlling high face pressures, although the screw conveyor of an EPB can also be designed to accommodate most high-pressure conditions."

Jan 1, 2016

By George Hufford

An investigation is made into the applicability of queueing theory to simulating the operation of a large open pit copper mine in the southwestern United States. Actual data from a working mine was used to construct curves for truck loading time, haulage and return time, and dumping times. Known results of investigations of queueing models (Koenigsberg - 1958, Gordon and Newell - 1967, Cabera and Maher - 1973) were used to simulate the actual operation. These did not give acceptable results so commonly used probability distributions were fitted to the actual data. A large computer program known as Q-GERT was used with the various parameters obtained from fitting the curves. Kolmogorov- Smirnov tests were run that showed that this was not satisfactory either. Finally, Q-GERT was used with the actual data from the mine. An appropriate correction factor is then found to apply to the exponential probability distributions tested previously and satisfactory results are obtained.

Jan 1, 1981