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By C. Barbee

Density tracers are a useful diagnostic tool for evaluating the separation efficiency of dense medium circuits. Unfortunately, the full capabilities of density tracers are often not realized in practice due to problems that occur during the retrieval step. To overcome this problem, an electronic monitoring system has been developed to automatically identify and count the tracers as they pass through a cleaning circuit. This technique, which relies on recent breakthroughs in transponder technology, improves the reliability of tracer data by eliminating statistical errors associated with lost tracers. Field tests showed that very accurate counts (>98%) of the transponder-based tracers could be achieved in full-scale trials. In addition, this simple system makes it possible for efficiency tests to be performed very rapidly by a single person in an extremely cost-efficient manner.

Jan 1, 2008

By Shamsher Prakash

Estimation of vertical load carrying capacity of a single vertical pile under earthquake loading is an important task of a design engineer. Lateral vibration of vertical pile is highly influenced by the magnitude of vertical load. Several load reversal, during earthquake loading introduce gap between pile soil interface which reduces its load carrying capacity and increases lateral motion. This paper presents a simple time domain numerical scheme to estimate the lateral pile response, considering the loss of contact of pile at pile soil interface, during impact and earthquake loading. The motion of the pile is limited in the vertical plane. Time domain has been discretised into small intervals. The non linearity of soil properties has been taken into account by discretised Winklers model with Wolfes frequency independent mass spring dash pot coefficient for geometric damping. Suitable software has been developed which keeps track of the load reversal point of each elements.

Jan 1, 1996

By Jason A. McLennan

Conditional bias is an infamous problem with estimation methods including kriging. Changing estimation parameters will mitigate, but not remove, conditional bias. The conditional bias of kriging is well understood; however, there is widespread confusion in the literature and among practicing geostatisticians regarding the conditional bias of geostatistical simulation. There is no conditional bias of simulation when the simulation results are used correctly. The correct use of simulation for recoverable reserves estimation is to (1) generate multiple realizations conditional to all available data at a small scale, (2) linearly average all realizations to the chosen block size and (3) calculate the probability of each block being ore and the ore grade of each block. The ?probability of ore? and the ?ore grade? are conditionally nonbiased.

May 1, 2002

By George Munro

Heavy water inflows of up to 1350 1/sec in the 19.6 km Moawhango-Tongariro Tunnel section of the Tongariro Power Development Scheme in New Zealand gave rise to severe operating problems, particularly in the equipment stripping stage when pumping installations had to be removed. Due to the necessity to commence stripping from the upstream side the contractors. Codelfa-Cogefar (NZ) Limited, took the decision to install a steel bulkhead some 5000m in from the lower. Tongariro, portal. The article lists the considerations taken in the placement of the bulkhead, and gives details of its design, installation and final removal. A brief description of the geology of the tunnel. together with water flow sources, rates and pressures is also included.

Jan 1, 1981

By Wenya X, Bingchen C

About 60 per cent of magnesite ores of Haicheng Magnesium Mine, due to their low grade, are not currently commercially exploitable. In this paper, the flotabilities of the main component minerals of the ores were studied in detail with ether amine as collector. Based on. these, a new technique of reverse-direct flotation with single etheramine as collector for the beneficiation of the ores was developed. It gave highly satisfactory results. On the basis of the calculation by means of CNDO/2 method, of the studies of the solution chemistry of magnesite and of the adsorption tests and Zeta-potential measurements, the key mechanism in the new technique about activating effect of Ca2+ on the flotation of magnesite was suggested.

Jan 1, 1993

By A. F. Symonds

The effects of harmonic resonance between the supply impedance and power factor correction capacitors on systems with large harmonic sources, such as mine winders, are well known. The similar effects of resonance with cable capacitance are not commonly encountered and, hence, are not always considered in the design of medium-voltage networks. This article considers some of the aspects of resonance between the supply impedance and the cable capacitance and presents one successful approach to solving the problem.

Jan 1, 1998

By Duk-Won Park, Syd S. Peng

INTRODUCTION More than five years have elapsed since the first shortwall panel was installed in a US mine in 1972. By the latest count, 11 mines have tried the shortwall method on 34 panels. Potentially, the shortwall method (see Figure 1) offers the combined advantages of longwall and continuous mlning. But just like any other mining method, shortwall is not a panacea. It is only applicable under a set of stringent conditions. Coal operators at eight of the eleven mines are satisfied with shortwall mining, though there are only five mines presently producing coal from shortwall panels.

Jan 1, 1981

By C. H. Reynolds, Robert C. Pruess

Late in 1954 exploratory drilling indicated a substantial orebody on the Rattlesnake claims of Woodmont Inc., a Continental Uranium Inc. subsidiary. Woodmont holdings are located about 35 miles southeast of Moab, Utah. Only a few miles north of Big Indian Valley and other Chinle-sand uraninite deposits, the claims are in an entirely different geologic environment. Detailed development drilling continued until the Deep North orebody was outlined, covering an area approximately 300 x 450 ft. All exploratory drilling and about 80 pct of development drilling was wet core. Chemical assays for each hole sample, applied at 1-ft intervals against the measured core length, were put into a conventional ore calculation formula. Forty-six holes were drilled to delineate the Deep North orebody.

Jun 1, 1956

By S. J. Jung, F. Lock

This research came about because of the recognized need for a safe, easy way to line small-diameter bored raises (less than 150 cm). Currently, an operator must go down the raise and apply the concrete lining manually, using the shotcrete method of application. With an automated system, there would be no man positioned in the bore itself. All control functions could be commanded from a central location. Shotcreting in the confined space of a small-diameter bored raise presents problems that can be overcome by the application of shotcrete using a remote system.

Jan 1, 1995

By D. Malhotra

Gold and silver ores are generally leached in weak cyanide solutions for recovery of precious metals. However, pretreatment of refractory ores requires flotation to concentrate the precious- metal minerals. Also, flotation is a common concentration technique for recovering precious metals as byproducts in sulfide-mineral flotation circuits. The present paper reviews current plant practice and future challenges for precious metal recovery.

Jan 1, 1999

By S C. Dominy

The Minerals Education Australia program is offering a tertiary learning environment for the global mining industry. The Minerals Council of Australia has instigated this initiative, which is run by the Minerals Tertiary Education Council. The program is a pioneering partnership between the Australian minerals industry, Australian governments and key Australian universities. It is designed to deliver key undergraduate and postgraduate courses for tomorrowÆs minerals industry professionals in the fields of geoscience, mining and minerals engineering and metallurgy. The flagship course for geoscience professionals is the G3 Masters program. This is a coursework-based degree supported by the Minerals Tertiary Education Council, and a partnership between James Cook University, the University of Tasmania and the University of Western Australia. These partners represent the leading-edge providers of minerals geoscience education and R&D in Australia. The G3 program provides the full spectrum of post-graduate training skills in exploration, mining and economic geology topics.

Jan 1, 2003

COMMITTEE IN CHARGE SPENCER PENROSE, Chairman A. E. CARLTON, Chairman Finance Committee GEORGE M. -TAYLOR, Vice-chairman. J. DAMSON HAWKINS, Secretary DENVER COLORADO SPRINGS Finance Finance T. B. STEARNS A. E. CARLTON RICHARD A. PARKER SPENCER PENROSE T. B. BURBRIDGE GEORGE M. TAYLOR A. L. BLOOMFIELD, Treasurer Arrangement Registration DAVE G. MILLER LOREN C. LENNOX FRANK BULKLEY HORACE F. LUNT GEO. E. COLLINS J. M. TIPPETT Entertainment Arrangement and Entertainment F. H. BOSTWICK GEORGE M. TAYLOR F. E. SHEPARD J. D. HAWKINS HOWLAND BANCROFT A. E. CARLTON B. P. MORSE A. L. BLOOMFIELD J. G. PERRY THOMAS B. CRONE E. P. ARTHUR ETIENNE A. RITTER CRIPPLE CREEK PUEBLO THOMAS B. CRONE J. F. WELBORN E. B. ARTHUR H. B. CARPENTER N. S. GREENSFELDER L. B. EAMES A. E. CARLTON F. ROBINSON B. F. HILL J. G. WILLIS

Jan 8, 1918

By Bob Clayton, David Readett

Jameson Cell technology has found applications in the cleaning of entrained material in copper Solvent Extraction - Electrowin plants. The materials involved are largely organic substances that have not been totally removed prior to treatment of the rich electrolyte in the tank house. This paper discusses the recovery of the entrained organics in the rich electrolyte streams at Phelps Dodge Morenci in Arizona. Mount Isa Mines in Queensland. Australia and the Olympic Dam Operations in South Australia. The paper details the design, performance, the feed and product characteristics, capacity and operation. In one operation the entrained material has been observed to include crud that has been formed in the SX train. The mechanism of recovery is also discussed.

Jan 1, 1993

As the gold price, and consequently ore reserves, improved in the late 1970's, a programme of upgrading the gold recovery circuit at the Phoenix treatment plant at Central Norseman was initiated. The introduction of oxidised ore with a high clay content from the North Royal open cut caused a reduction in thickening and filtering capacities, which in turn restricted plant throughput and increased gold losses in the residue solutions. Test work into alternative washing facilities showed that the installation of a five stage counter current decantation system would restore throughput and reduce soluble gold losses. Installation of the system achieved the objectives of increased plant tonnage, increased proportions of the high grade oxidised ore in the mill feed and decreased gold losses in the residue waters.

Jan 1, 1978

By K. J. Shoop, S. J. Ripke, T. C. Rao, T. C. Eisele

This study investigated the use of a 7.6-cm inside diameter, 344.2-cm-tall horizontally baffled column to reduce the ash content of a low-sulfur bituminous coal. Tests were carried out to determine how the baffled column responded to changes in feed rate, reagent dosage and feed quality. The tests were also carried out to compare the columns performance to a conventional column installation in an operating plant. In this paper, the results of this investigation are reviewed and discussed.

Jan 1, 1999

By H. A. D. Kirsten

The professions are subject to a wide range of changing conditions, and are as a result forced to become more competitive. Although there is a need for specialization under these circumstances, no formal recognition, definition, or control of specialists exists. Some of the professions have attempted, over extensive periods of time, to resolve the issues involved, and have met with varying degrees of success. It appeared from the replies to a questionnaire sent to over one-hundred-and- .fifty professionals, that both advanced education and experiential training, are considered to be necessary qualifications for specialization. The opinion as to whether it should be lift to the individual to cal himself a specialist, or whether recognition should be based on peer review, was divided The majority did not want the number of specialists to be controlled The response to the reservation of work for specialists was ambivalent.

Jan 1, 1995

By Charles S. Phillips

Kaiser Aluminum and Chemical Corp. (KACC) had been discharging spent bauxite-generally referred to as red mud-into the Mississippi River for almost 20 years when, in 1972, it agreed to store the waste solids on land. KACC decided to utilize a DREW system (decantation, drainage, and evaporation of water) where the spent bauxite is deposited in a large drying bed, surrounded by a 9-m-high levee. At the bottom of the bed, corrugated, perforated plastic pipe is encased in filter sand. The company built one DREW bed at Gramercy, LA, in 1973 and a second at Baton Rouge in 1974 using draglines, tractors, and rubber-tired scrapers. When a third bed was needed in 1977, the estimated construction cost using draglines was judged too high and KACC personnel began searching for a better, less expensive method for constructing the levee. A bucket-wheel excavator and conveyor system was selected and has proved to be less costly than more traditional earth-moving systems.

Jan 7, 1980

By B. E. Fernow

In order to ascertain to what extent the mining industry has been dependent upon forest-supplies, for the purpose of a report upon

Jan 1, 1889

Discussion of the paper of J. C. Febles, presented at the Butte meeting, August, 1913, and printed in Bulletin No. 79, July, 191.3, pp. 1267 to 1283. J. W. RICHARDS,. South Bethlehem, Pa. :-In looking at these precipitating launders the idea has come to me that the iron could probably be kept much cleaner if there were laid on the bottom of the . launders some sheet copper, with which the iron would be in contact, and as the solution passed over the tendency would he to precipitate the copper on the sheet copper and thus keep the iron cleaner than it is under present conditions. As soon as a piece of iron becomes coated with copper, its surface becomes inactive, and the presence of a sheet of copper in electrical contact with the iron would tend to precipitate the copper on the sheet copper and to keep the iron clean.

Jan 11, 1913

By Granholm S

The current emphasis within the mining industry to reduce the cost of production has stimulated interest in the fields of maintenance and operational reliability of capital intensive mining equipment. From an economic point of view, high reliability is desirable to reduce the maintenance costs of the systems. Two graphical methods consider reliability analysis. The first one, the method of Total Time on Test (177)-plotting deals with the reliability data which are free from trend and serial correlation. The second method which is based on time dependent modelling approach deals with the data which are not free from trends and serial correlation. The examples show how these graphical methods can be used to calculate the optimal maintenance intervals for components or systems.

Jan 1, 1991