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By V. Karra, G. Beerkircher

Application of the innovative WaterFlush® crushing technology to the processing of gold, copper, and iron ores is presented for retrofit circuits and productivity gain in each case is stated. New operations containing WaterFlush are described in brief.

Jan 1, 1995

By J. B. Gwiazda

In designing mine workings and adequate roof supports, it is indispensable to determine properties of the strata surrounding the workings. The proper selection of roof supports is based, before everything else, on a thorough knowledge of the roof rock strength, especially tensile strength. This parameter is a vital factor in the delamination of roof rocks and eventual cave-in. It is also important to know the properties of the floor on which the roof supports are set. While driving galleries, it is essential to know beforehand the strength of rocks that will be encountered in the near future during the work. The devices described will help to obtain this information.

Jan 1, 1987

By Deepak Malhotra

Is operator training necessary for optimization of flotation plants? The answer is obvious-Yes. The author suggests a three-phase program for operators when new plants are built or new crews are hired in existing operations. Case examples are discussed to illustrate the benefits of operator training.

Jan 1, 1999

By Russell E. Martin

Excavating and lining twin interstate highway tunnels each 11.3 m (37 ft) high by 14.6 m (48 ft) wide by 183 m (600 ft) long. A discussion of the geology of the site and problems occurring at the portals and the solutions to the problems. The methods used in placing the concrete lining are also discussed.

Jan 1, 1987

By Dr. -Ing. Karlheinz Timtner

This paper deals with the complicated and often misunderstood relationship between torsional windup, load sharing and peak torques in conveyor backstops. The principals apply in low speed, intermediate speed or high speed applications. Once the controlling factors are understood, a reasonable approach to selection procedures can be achieved.

Jan 1, 1996

By Mohammad Irshad, Larry H. Heflin

INTRODUCTION The planned 166 kilometer (103 mile) Metro rapid rail transit system in Washington, D.C. is being designed and constructed by the Washington Metropolitan Area Transit Authority. At the present time, 112.6 kilometers (70 miles) of this system is in operation and contains 21 route-kilometers (13 miles) of rock tunneling, and 14.5 route-kilometers (9 miles) of soft ground tunneling. An additional 2.4 kilometers (1.5 miles) of single track tunnels in rock are planned and 6 additional contracts will consist of some 8 kilometers (5 miles) of twin tunnel, resulting in 16 additional linear kilometers (10 miles) of single track tunnel in soft ground. The Authority plans, upon its evaluation and the recommendation of the General Engineering Consultant, to include an alternative design incorporating the convergence confinement method of construction known as the New Austrian Tunneling Method (NATM), for Sections E-5, E-6e and E-8a of the E-Route. The Metro system is constructed in a variety of geological conditions and crosses the boundary of two major geographic provinces. Rock tunneling is to the west of this "fall-line" boundary, soft ground tunneling to the east. The soft ground tunneling portions of Metro construction lie in the coastal plain which consist of a

Jan 1, 1987

By D. Nilsson

This paper demonstrates the importance of including a discount rate in the determination of the optimum final depth of an open pit. Without a proper discount rate, a pit will probably end up too deep. Another consideration is future underground mining. If underground mining is profitable, the pit may need to be shallower. Of all of the investments needed, only mining equipment and the underground mine should be included, and amortization and depreciation should not he included in the study.

Jan 1, 1998

Everyone knows the importance of careful handling of explosives. Even so, the point is on occasion all too graphically driven home. Witness the recent blast at a Utah explosives plant that killed five people. Part three of this series on explosives discusses transportation, storage, handling, and destruction. Federal, state, and sometimes local regulations govern the many steps involved in transporting, storing, and handling explosive materials. Regulations minimize personnel exposure to hazardous material and insure that the explosives remain stable and usable.

Jan 9, 1981

By Evert Hoek

Two types of failure have to be considered in designing large openings: (a) Structurally controlled failure caused by discontinuity intersections, (b) Stress induced instability which occurs when induced stresses exceed the rock mass strength. Structurally controlled failures, which occur in hard jointed rock masses at relatively shallow depth, are briefly reviewed. This paper is primarily concerned with stress induced instability at greater depths and with the problem of estimating the strength of a rock mass surrounding an underground opening. Some of the practical aspects of support design for large openings are discussed.

Jan 1, 1981

By J. D. Pfarr

The Homestake Mine, located in Lead, SD, has been in business for 113 years. Until 10 years ago, conventional mining methods were used to extract ore. Due to complexities in the ore bodies and increasing costs, new technology was introduced to the mine. An integral part of this technology was mechanized cut-and-fill mining. This mining method currently produces about 50% of the annual production and has proven to he safe and economical. As a result, the Homestake Mine remains competitive in today's market.

Jan 1, 1992

By Jim Morris

This paper will describe the excavation of a 5.4 percent decline at the Montanore Project for Noranda Minerals Corporation. The 5.3 m by 4.9 m tunnel was driven to provide access for the exploration of a major copper-silver deposit. Soft ground and conventional drill-blast mining were used on the 4,270 m tunnel. Ground support consisted of steel sets and concrete in the soft ground and pattern rockbolts providing the majority of the rock support. A special feature of the project was the use of conveyor haulage in conjunction with the drill-blast excavation.

Jan 1, 1993

By F. H. Muge

The problem of how to handle heterogeneous populations in an ore reserve global estimation arises in many geostatistical studies. In some cases it is possible to split data into different significant types of ore in such way that non-overlapping subpopulations are obtained, and a separate study is possible. In other cases the subpopulations are intermingled and a set of nested structures may model the spatial variability of the ore. Finally, one of the populations, consisting of a small proportion of high grade values of economical meaning, may disturb the structural analysis. In this paper, some methods are proposed to cope with these kind of problems and typical case studies are presented.

Jan 1, 1986

By M. Ghiani, R. Ciccu

After a short review of the basic concepts underlying the application of selective flotation and electrostatic separation to the beneficiation of phosphate ores, the paper deals with the results obtained with these two technologies for a number of run-of-mine ores of different origin and distinct mineropetrographic features. Problems are discussed in the light of the minero-petrographic characteristics of the ores.

Jan 1, 1993

Many organisations, including those in the resources industry have Board-level endorsed principles on sustainability. A key challenge, however, is how to systematically integrate these high-level principles into the design and operation of mineral processing plants. In an effort to meet this challenge the Sustainable Operations framework, called SUSOP®, was conceived and developed through the Corporative Research Centre for Sustainable Resource Processing (CSRP) in Australia. Somewhat analogous to HAZOP (Hazard and Operability Studies) which is well entrenched in the resources industry, the key aim of SUSOP® is to produce a holistic, systematic and rigorous methodology for identifying and assessing sustainability opportunities and risks. This paper argues the need for such a sustainability framework, presents the key elements of SUSOP®, highlights how case studies enhanced its development and articulates the reasons why such a framework will have growing importance into the future.

Jan 1, 2011

By M. G. Yalçin

Marbles commercially known as the Nigde- white crop out in the town of Gümü?ler, around the Çalkama Hill within the Gümü?ler Formation of the Nigde Masif of Paleozoic age. Marbles sporadically occur within the masif, however its prevalent occurrence is associated with the Gümü?ler Formation. Due mainly to its intense fractured nature, the Nigde-white marbles are used as dimension stones, crushed stones and most recently micronized calcite. Insignificant portion accounts for block use through a few quarries.

Jan 1, 2005

By Leo G. Martin, Richard G. Sherman

Recent sewer construction in downtown New Haven, CT required avoiding open trench methods because of near surface utilities and traffic congestion. The .73 km long alignment is in sands with the water table at the tunnel's springline. The designers felt the situation was ideal for an EPB machine; however, the tunneling method was left to the Contractor. The winning bid surprised everyone. The tunnel is being excavated by hand using an open face shield with breasting boards. The review of the bids indicates hand mining was approximately 1/2 the bid price of TBMs. Currently, excavation rates average 14 m/day with no excessive settlements.

Jan 1, 1993

By M. J. Hrebar

This paper reviews large dozer stripping techniques and presents results of two field studies. The first is a seven-shift study of a contour block stripping operation where a Caterpillar DII is used as the primary stripping equipment. The second is a two-shift study of two Cat DIIs dozing blast cast material ahead of a dragline operation. Surveys and continuous time studies were used to determine production rates and as a basis for forecasting unit stripping costs in both cases.

Jan 1, 1994

By Jorge Martinez

The Muck Valley Hydroelectric Project in Northeastern California required construction of a 3.65 meter tunnel through 6,623 meters of mixed volcanic flow deposits within a critical time frame. As Engineer and Construction Manager for the Project, Morrison-Knudsen Engineers invited bids for both Drill and Blast as well as Tunnel Boring Machine methods, selecting a contractor proposing a TBM designed and built specifically for this project which could excavate a wide variety of materials and maintain acceptable progress rates to complete the work within schedule. Tunnel lining as required included shotcrete with metal fibers and full circle concrete.

Jan 1, 1989

By J. S. Y. Wang, R. C. Trautz

To evaluate the potential for water seeping into an underground opening, a 9-m- (30-ft-) long drift was constructed in the unsaturated fractured tuff at Yucca Mountain. Forty seepage tests were performed by releasing finite volumes of water at a constant rate into short test intervals located in boreholes positioned above the drift. The seepage threshold flux, defined as the liquid-release flux at and below which water will not drip into the opening, was determined for 10 test intervals. The seepage data, observations and model results indicate that a seepage threshold exists because a capillary barrier diverts water around the opening.

Jan 1, 2002

By Henry Brehaut

The International Network for Acid Prevention (INAP) was formed in 1998 by 17 international mining companies to promote significant improvements in the management of sulphidic mine materials and the reduction of liability associated with acid drainage through knowledge sharing and research and development of technology. Since its inception two panels have been formed to identify and move forward with research projects and eight networks have been constituted to initiate interaction and knowledge sharing within the membership in specific areas of technical interest. An INAP web site has been developed to facilitate the sharing of information and to encourage the exchange and development of new ideas.

Jan 1, 2000