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By G. S. P. Pereira, E. M. R. Santos

Acid mine drainage (AMD) is a serious environmental problem in mining activities. Prediction is the first step for evaluate the potential of acid generation and there are some possible methods to estimate it. They are described as static tests, which examine the balance between acid producing and acid consuming materials, and kinetic tests, which attempt to predict drainage quality overtime. Static methods are very simple and give a qualitative classification of the ores based on their potential to generate acid drainage. The characterization of ores to determine their acid producing potential is vital for the prevention of long term environmental liabilities. Laboratory tests were conducted under different methodologies to predict the acid producing potential of sulphide overburden, ore materials and tailings from a deposit of copper ore.

Jan 1, 1999

By Priscilla P. Nelson, Steven D. Glaser, Thomas D. Rourke, O&apos

Construction records from six projects which employed full-face TBMs to drive 18 km of tunnel in sedimentary rock have been analyzed. More than twenty individual causes of delay could be identified. Delay causes are characterized on the basis of frequency and duration of incidents. Average utilization and downtime distributions are presented for each project, and frequency distributions of downtime per shift are discussed.

Jan 1, 1985

By Thor Skjeggedal

The Norwegian contracting firm A/S Høyer-Ellefsen has for the last 2.5 years carried out substantial pregrouting in a 7600m long tunnel just outside the city of Oslo. This has been done to avoid groundwater lowering and consequent damage to surface structures. A WIRTH TBM is used in combination with a 2 boom Atlas Copco hydraulic jumbo for the drilling of groutholes in front of the machine. The detailed procedure for the drilling and grouting will be discussed, and the results obtained will be presented.

Jan 1, 1981

By Q. X. Yun

This paper presents a new approach to optimize the transportation system in open-pit mines. The new approach employs artificial intelligence, fuzzy sets, dynamic programming and CAD technique to determine the transportation system. The determination consists of 4 phases: initial selection, road alignment, final decision .and open-pit drawing.

Jan 1, 1992

By Randall J. Essex

Public and private owners of infrastructure projects face a number of real and perceived constraints when considering design-bid-build (DBB) procurement for underground projects. Thus, they may not be considering all of the available contracting approaches available to them. To the extent that the North American tunneling industry believes improvements can be achieved through better forms of contract, we have an opportunity and responsibility to bring these ideas to the owners of our projects. This paper offers suggestions for how we can climb out of our DBB Paradigm Sinkhole—and share some of the benefits of alternative contracting methods.

Jan 1, 2003

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 Y. G. Zhang

Interactive Dynamic Optimization Method (IDOM) will be presented in this paper. IDOM combines inventory theory, dynamic programming, computer simulation and interactive technique to formulate a production schedule for open-pit mines. This new method has been successfully used in metal mines of China for years.

Jan 1, 1986

By Leslie S. Rubin, John C. Roberge, Mackenzie Burnett

A self regulating helical inducer has been developed and tested for dry injection of coarse or fine solids into a hydraulic pipeline. This centrifugal pumping device has also been modified and tested for use as a boost pump in medium and long distance pipeline haulage systems. The helical inducer has been operated as an integral component of a slurry injection vehicle. This compact, low profile vehicle also includes crushing and screening components, solids feeding components, a track drive system for mobility and is run by a single operator. The helical injector and boost pump operate without speed and flow controls allowing for the practical hydraulic transport of excavated materials.

Jan 1, 1983

By B. J. Swenty, J. L. Hubbard, R. L. Peyton

Based on the results of the National Program of Inspection of Nonfederal Dams conducted by the US Army Corps of Engineers during 1977-1981, Missouri was found to have the highest number of "unsafe" dams in the nation. Many of the dams classified as unsafe in Missouri were tailings dams.

Jan 1, 1987

By John E. Tilton

Looking back on the second half of the 20th century, future historians, I believe, will be fascinated by two major political upheavals. The first is the environmental revolution in the 1960s. It erupted in the United States and parts of Western Europe and then swept across the rest of the globe like a wild fire. The second event is the collapse of the Soviet Union. It was the last of the world's great imperial empires. With its demise went central planning as a viable economic system. History, I suspect, will see this second revolution as an offspring of the first. This is because economic and environmental issues were largely responsible for the unraveling of the Soviet Union.

Jan 1, 1994

By M. Mohammed, S. J. Jung

The prime criteria in the design of underground openings with complicated geological structures is ground control. Stability of underground openings for deep mines is critical because incorrect orientation or geometry of the shaft, stopes and accessways often results in the failure of openings due to high stress conditions. Current design procedures for complicated orientation and geometry of mines are rapidly becoming inadequate. In this study, the finite element method (ANSYS) has been used with optimization criteria to design safer, more stable underground openings.

Jan 1, 1995

By H. Benedict

For many years, asphaltic lubricants have been used on large open gears. The asphaltic's diluent is essential to thin the lubricant enough to be sprayed. Once the lubricant has been sprayed into place, the diluent evaporates, leaving the asphaltic to lubricate mating surfaces. Recently, this thinner has been changed to non-cancer causing diluents. The gain in safety corresponded to a lesser ability to evaporate. This paper explores how much diluent remains in the lubricant when it has been assumed to be flashing off. Having quantified the diluent in the lubricant, we can then estimate the effect this has on viscosity.

Jan 1, 2003

By Clifford R. Haryett

The potash industry in Saskatchewan, Canada, has advanced in numerous mining and ore processing areas over the last decade. This article describes these innovations and their effect on the industry in the area. During the 1970s, Canada's Saskatchewan province became a world leader, second only to the USSR, in potash production for crop fertilizer. Despite a serious oversupply in the early part of the decade, and a drop in demand due to the agricultural impact of the oil crisis, the Saskatchewan potash industry continued to make extensive capital expenditures to bring mining and processing innovations onstream. These innovations were directed at reducing production costs, improving work conditions, and overcoming environmental concerns.

Jan 8, 1982

By R. Svensson

Mill linings play an important role in all comminution processes with tumbling mills. The selection of the lining profile and the lining material has a great impact on overall grinding cost and mill throughput. The cost of the lining itself is minor in comparison with media cost, energy cost and the value of the material produced in the mill. The total scope must be considered when mill linings are selected. This paper presents case stories and explains the technology behind: - Different lining profiles in rubber and steel. - Orebed magnetic lining. - Steel-cap rubber lining.

Jan 1, 1995

By J. Girard-Dwyer, T. Camm

Direct costs such as medical, legal, administrative, and worker’s compensation costs, property damage, lost earnings, and lost benefits are typically used to compute the economic impacts of occupational injuries. However, there are also a number of less obvious, indirect costs that substantially contribute to the overall loss costs. In fact, for every $1 of direct costs an estimated $3 to $5 of indirect costs are also incurred. This paper presents a systems approach that incorporates engineering, economics, psychology, and sociology in order to evaluate the total value of investments in safety. By studying the interrelated system comprised of the injured worker, their family and coworkers, as well as the organizational structure that was the setting for the incident, a methodology can be developed that will more accurately capture the true costs of mine injuries.

Jan 1, 2004

By Zhengbin Cheng, Wenguang Lu, Baoqi Sun, Jiaying Tang

This paper studied the flotation separation of feldspar, zircon and kyanite from quartz with a mixture of cationic and anionic collectors. Tests show that collector mixture has specially good effect, using it, the separation of these three silicate minerals from quartz can be successfully achieved at the natural pH value of tap water in the absence of any acid, fluoride and other inorganic reagents. The properties and characteristics of collector mixture were analysed. By means of IR-spectra, ESCA and AES, the action mechanism between collector mixture and minerals was throughoutly studied.

Jan 1, 1995

By Sidney M. Cohen

This paper describes an economical method of upgrading a clay deposit using conventional separation processes into a suitable cement plant feed. The natural size difference of clay and silica in the clay deposit is utilized in the dry air classification device. A case study in which the raw material from a clay deposit is converted into a portland cement plant feed is presented.

Jan 1, 1983

By Charles E. Mergentime, J. Marshall Dean

Mergentime/Loram's extension of the Washington, DC Metro Subway System includes construction of dual 1,770-foot tunnels in soft ground, a crossover structure, a fan structure and pumping station, and other related work. This paper describes the overall construction requirements of the Contract, including subsurface conditions; Mergentime's value engineering of the tunneling and compressed air contract requirement; selection of the tunnel boring machine and backup equipment; installation of the compressed air plant; the manufacture, use and evaluation of the tunnel liners; and the tunneling performances during construction of the first tunnel.

Jan 1, 1985

By H. Suharyono, R. Hogg

A laboratory investigation was performed on flocculation following the addition of polymer to slurries flowing through pipes and in-line (static) mixers. Results are presented showing the effects of flow velocity, pipe length, in-line mixer elements and the use of multiple addition points. Flocculation performance was measured by the settling rate and the supernatant turbidity. The effects of agitation and mixing time are shown to be generally consistent with the results of equivalent tests (both batch and continuous) conducted in stirred tanks.

Jan 1, 1997

By X. Zhou

A novel flotation device, cyclonic static micro-bubble column flotation (FCSMC), was introduced in this paper. FCSMC has been widely applied for fine coal preparation in China, and its application has been further expanded to the mineral processing industry. The FCSMC system features a unique cyclonic structure which enhances the separation performance of the column. In this paper, the cyclonic separation mechanism of FCSMC process was investigated, and corresponding kinetics equations were established to probe the separation principle of this device. Some typical examples of using FCSMC to separate different materials including coal, copper, fluorite, etc., were presented. Key words: cyclonic static micro-bubble flotation column, cyclonic separation

Jan 1, 2008