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By Kenneth N. Han, Yuhong Chen

The removal of carbonaceous material from Carlin gold ore has been investigated via froth flotation. The effect of type and concentration of various oils as flotation collectors and of sodium silicate as the dispersion agent on the overall recovery of carbonaceous material has been studied. Other variables affecting froth flotation efficiency were also examined closely. These included particle size, pH of the solution, and temperature. The effect of reduction and oxidation of carbonaceous material on froth flotation efficiency has also been investigated. This investigation showed that aromatic type oil was the most effective collector. Also found in this investigation was that oxidized carbonaceous material was difficult to float unless the oxidized portion was subject to reduction before flotation. More than fifty percent of the carbonaceous material was able to be removed via froth flotation. It can be concluded from this study that the effect of pH and temperature during the rougher flotation state is of little significance to the overall recovery of carbonaceous material. Since pyrite is responsible for the high consumption of chlorine, removal of pyrite is very important in order to reduce the overall consumption of chlorine.

Jan 1, 1990

By Todd L. Hollingsworth, Jeremy K. Hobbs

In 2001, the Radomiro Tomic Mine located near Calamq Chile, added a tertiary crushing facility. An 84" wide mobile tripper is used to fill their tertiary crushing storage facility. This paper is a we study to demonstrate the drive and control systems in use on the tripper. Of special note is the design concept used to allow the system to operate multiple motors in both demand and regenerative modes through a single VFD. Also noted is the use of touch screen local controls, handheld radio controls, starting/stopping/ braking philosophies, safety device interfaces, and the local to remote control interface.

Jan 1, 2004

By Samir Kumar Das

Presently Geographic Information System (GIs) is gaining wider acceptance id appreciation in various resource management surveys, generation of various thematic maps, various scientific investigations, environment assessment, disaster management, etc in India but they are general in nature. A huge number of Global Positioning System (GPS) based "Total Station" are playing good roles in India for accurate and quick surveying . The GPS based real time Mine Management and Truck Dispatching System for optimization of productivity is being installed in the Panchpatmali opencast bauxite mines of India. This paper dealt in depth on GIs and GPS and their present roles in the Indian mining scenario.

Jan 1, 2002

By D. W. Tedder

Several bauxite feeds and residue sands and muds, produced by Bayer plants in the US and over-seas, were fractionated using dry and wet magnetic separators. The magnetic sand fractions typically contained about 50 to 60 wt % Fe2O3 and the bulk of the radioactivity in the sands. The muds are more difficult to process, but some fractionation is possible using a combination of classification and magnetic separation techniques. Among the mud samples, higher radiation levels are often associated with the less magnetic fractions. Bauxite is more easily fractionated using dry magnetic separation. Much of the radioactivity in bauxite appears to concentrate in the sand and mud residuals.

Jan 1, 1987

By M. A. Chandler, G. T. Adel, J. N. Richardson, E. C. Gutierrez

A rapid, bench-top analyzer has been developed to determine P2O5 content and CaO/P2O5 ratio in phosphate ores. The analyzer utilizes a portable computer equipped with a frame grabber to measure the reflective intensity (gray level) of phosphate samples placed in front of a television camera. P2O5 content is related to the average gray level of the sample, while CaO/P2O5 ratio is determined from the amount of bright material present. The sensor is currently being used to analyze flotation concentrate samples at Texasgulf's phosphate operation near Aurora, North Carolina. Sensor development along with results from laboratory and in-plant testing are discussed.

Jan 1, 1993

By Bill Sayer

Cadman, a wholly owned subsidiary of Heidelberg Cement, is a leading supplier of sand and gravel as well as ready mix concrete in the greater Seattle area in western Washington State. Cadman's aggregate mine is located in North Bend, 34 miles east of Seattle, WA, and consists of a "Lower Pit" and an "Upper Pit." In 2005, Cadman planned the upgrade of the North Bend mine operation as follows: Upper Pit (Figure 1): 1. Crushing Plant, Stacker and Stockpile 2. Storage Reclaim Belt Feeders 3. Feed Conveyor 4. Downhill Overland Conveyor Lower Pit (Figure 2, Photo 12): 1. Radial Stacker 2. Storage Reclaim and Truck Load-out

Jan 1, 2008

By Douglas J. Piper

On reflection of certain overall circumstances which have pervaded the gold mining industry, it appears useful to point out some specifics which the writer hopes will improve the potential for success in the application of hydraulic dredges to gold mining activity. I will, prior to entering into that discussion, comment briefly on rule of thumb for the application of the three types of equipment. The three are bucket line, bucket wheel and drag line dredges. From a standpoint of high volume movement over a short distance, between 50 and 300 feet, the drag line dredge is historically the most cost effective type of machine to be utilized if bulk excavation is the single driving consideration. It is typical for this sort of equipment to operate in the 10 to 30 cents per cubic yard range, however, cost of operation is not the sole consideration. Typically the drag line mixes and remixes the material which it excavates. In the event that gold recovery is the object of the exercise, a strong potential for loss of the valued mineral exists. Additionally, drag lines do a poor job of bottom cleaning, particularly if there is a ridged or creviced bottom which must be cleaned and in some cases partially removed to assure recovery of the highest percent of valuable ore. The bucket line dredge has, until recently, been considered an extremely cost effective device. However, the high cost of manufacture of this type of equipment has mitigated against its use in the majority of

Jan 1, 1992

By D. M. Hausen

The role of applied mineralogy in mineral beneficiation begins with early prospect evaluation, and continues through stages of amenability testwork and pilot plant studies to the ultimate development of viable processes for mineable orebodies. After plant construction, mineral products from various locations, i.e., grinding circuits, flotation cells, gravity circuits, kilns, smelters, etc., require quick identification and control monitoring for optimum efficiency and recovery. Ore/gangue minerals are identified, quantified, and textural associations investigated by microscopic, spectrographic, and electron-optical instruments. Mineralogic analyses of large numbers of samples have required the development of sophisticated computer systems that merge analytical and mineralogic data into useful diagnostic data bases

Jan 1, 1991

By J. Hanna, I. Anazia

Selective fatty acid flotation of carbonate gangue from sedimentary apatites was achieved under acidic pHs without a specific apatite depressant and without conditioning the pulp with the collector. Concentrates (35% to 38% P2O5, 0.8% to 1% MgO) with high recoveries (80% to 85%) were produced from Indian and Chinese dolomitic ores. The calcareous and/or dolomitic-siliceous phosphate ores of South Florida and Utah required two flotation stages: one for carbonate removal, as mentioned above, and the other for phosphate recovery from siliceous gangue. Preliminary tests on the South Florida ore gave concentrates analyzing 29% P2O5 and 0.8% MgO, with a P2O5 recovery of 76%. A concentrate obtained from the western US phosphate ore from Utah assayed 30% P2O5 and about 1% MgO, with a P2O5 recovery of 89%.

Jan 1, 1988

By K. R. Weller, U. J. Sterns

The goal of most in-plant studies is to identify factors that limit overall plant performance. A major finding from such studies is that interactions between unit operations are always important, usually specific for a particular ore and plant combination, and are one of the limits to plant performance. Computer simulation based on process models developed from in-plant studies is a useful tool for identifying limits to performance and for estimating the effects of proposed changes at both pilot and industrial plant scales. Examples involving interactions between comminution and various separation and agglomeration processes are presented, and directions for future development discussed.

Jan 1, 1989

By Jeffrey Anderson, Cindi Byrns, Andy Davis

A closure plan was developed for the Intera Pond Facility, a former acid leaching collection pond at the BHP Robinson Mining Operations. To properly close the Intera Pond Facility, an engineering plan that was both technical and cost effective was developed. A primary objective of this closure project was to demonstrate to State regulators that following the proposed plan would minimize further degradation of water resources. Field data demonstrated natural attenuation of metal enriched solutes via carbonate reactions. Prospective fate and transport modeling indicated that it would not continue to degrade waters of the State.

Jan 1, 2000

By C. Tsatsanifos

Following closure of an old asbestos mine in Zidani, Kozani Prefecture, Greece, the geotechnical and environmental restoration of the tailings slopes was required. The geotechnical aspects of the restoration included the formation of gentler slopes to increase stability, in combination with drainage works for the same purpose. The environmental aspects of the restoration included covering the slopes with successive layers of soil in order to minimize infiltration of rainwater, and hence the potential for further transport of asbestos fibers, and to provide a suitable layer for revegetation of the slope. The paper presents results of slope stability evaluation using both limit equilibrium and finite element analyses and raises some issues related to reducing impacts to the geoenvironment when designing such restoration projects.

Jan 1, 2006

By Keith G. Wallace, Gary K. Rogers

As a supplement to an analysis involving methodologies for the estimation of airflow resistance in shafts used for both ventilation and hoisting, a detailed shaft characterization survey was distributed worldwide. The survey provided detailed information which enabled verification of recommended velocities and established limitations on fill factors and relative velocities. This paper evaluates the information obtained for 37 shafts and presents a statistical evaluation of the results. Apart from airflow rates, conveyance rates, and physical characteristics, qualitative information regarding means of conveyance stability and velocity control techniques at unloading and loading points are also presented. Calculations of fill coefficient, free area velocity, and most importantly, relative velocity between the airflow and hoist, are conducted. These results are presented by frequency diagrams which illustrate the trends, as well as provide limitations for these parameters. The data illustrates that, commonly, the fill coefficient for two or more conveyances, does not exceed 30 %. A limit of 50% is suggested for a single conveyance shaft. A recommended free area velocity of 10 m/s (1,970 ft/min) for combined ventilation and hoisting shafts, is sup- ported by these results. Relative velocities of 30 m/s (5,905 ft/min) are most frequent and 50 m/s (9,840 ft/min) being a practical maximum.

Jan 1, 1987

By Roland Hoet, Jim Patilla, Nick Madison

Increasing conveyor capacity and reliability is a common goal for many underground mines. This task is especially challenging when you must work with existing structure, belt, etc. Meeting this challenge, The Pittsburgh & Midway Coal Mining Co. North River Mine switched from constant fill to actively controlled fluid couplings, realizing a capacity increase from 2,100 tons per hour (2,300 stph) to 2,550 tons per hour (2,800 stph), with improved reliability. This paper will present a case study of The Pittsburgh & Midway Coal Mining Co.'s North River Mine underground conveyor haulage system. These conveyors included the main line conveyors as well as a tension controlled tripper booster panel conveyor. Characteristics and performance of the coupling and control system will be illustrated, demonstrating the systems controllability, simplicity, and dependability.

Jan 1, 2002

By Glenn L. Krum

Inflation has received much attention due to its effect on capital budgeting, associated cost overruns, and declining real profits. This study focuses on the effects of inflation on the evaluation of a mining investment and the estimation of a mining project's revenues. The study indicates that the best method for estimating future returns is the fore- cast dollar scheme. In this scheme, the metal price was held constant, and the operating costs were "inflated" along a historical regression line. The conclusion was reached by comparing the "actual" performance of a 3000 tpd (tonnes per day) lead mine model with 'its estimated performance during four time periods (1950-1960, 1955-1965, 1960-1970, 1965-1975). The individual data files for each time period and estimating method (6 files by 4 time periods) were pro- cessed by a suite of cash flow computational and investment analysis sub- routines. The analysis presumed that the mine was part of a large corporation which could utilize the expensed, development and exploration costs and any investment tax credits, in the year that they were incurred.

Jan 1, 1979

By Roger J. Hornberger, Paul F. Ziemkiewicz, Dirk J. A. vanZyl, Gene E. Krueger, Harry H. Posey, Kim A. Lapakko, Charles H. Buckmam

The Acid Drainage Technology Initiative (ADTI) was initiated in 1995 by federal agencies, the National Mining Association and the Interstate Mining Compact Commission to identify, evaluate and develop cost- effective and practical acid drainage technologies. In 1999 ADTI was expanded through the addition of the metal mining sector group, which began organization efforts in 1998. ADTI addresses drainage quality issues involving metal mining and related metallurgical operations and acid drainage from coal mines, for abandoned, active, and future mines. ADTI is a technology development program. It is not a regulatory or policy development program. The guiding principle of ADTI is to build a consensus among industry, federal and state regulatory agencies. ADTI is focusing these efforts on technology development and technology transfer in the areas of mine drainage sampling/monitoring, prediction, avoidance/remediation and modeling.

Jan 1, 2000

By N. S. Tanious

This paper summarizes results from an investigation into possibly the largest coal pillar failure in the USA. The newly opened coal mine worked an 3.35 m (11 ft) seam under overburden depth that ranged from 91 to 671m (300 to 2200 ft) . The mine main entries, and the enclosed pillars, experienced a massive slow squeeze. The squeeze could not be controlled and the mains were lost. A new set of mains were driven. Entry convergence (closure) measurements were carried out behind the advancing face to monitor stability. Pillar stresses were also measured under four different depths of overburden: 229.433, 472.579 m (750,1420,1550, and 1900 ft). The strength of pillars in the new mains was calculated from the loads that triggered the failure in the old mains, using three pillar strength formulas. The stress measurements showed that the new pillars supported more load than their predicted strength, indicating that current strength formulas are inadequate under deep conditions.

Jan 1, 1992

By George E. Niewiadomski

The exposure of miners to radon gas and its airborne daughter products is a serious health problem which has long been recognized in the uranium mining industry. The association of high exposure to alpha particle emitters with incidence of lung cancer is well established. There continues to be a pressing need to reduce and eventually eliminate the high incidence of occupational lung cancer among uranium miners through the development of new and improved measurement and control technologies. This paper highlights the current efforts of the Bureau of Mines radiation hazards research program. It is aimed at obtaining a fundamental understanding of the behavior and transport of radon and radon daughters, developing more accurate and reliable instruments and measurement methods and developing cost-effective control techniques. Also discussed are the most recent accomplishments and the future research plans of the program.

Jan 1, 1981

By V. W. Skema, M. W. Smith

Pennsylvania has 4,000 km (2,500 miles) of streams that do not meet water-quality standards due to acid mine drainage (AMD), making AMD the greatest cause of water pollution in the state. The problem is mainly caused by abandoned coal mines. To abate AMD, Pennsylvania is using a watershed-based approach that includes remining as a key component of a comprehensive restoration strategy. The Tangascootack Creek Water-shed was targeted for AMD restoration through remining. Geologic mapping and overburden data were analyzed using Earth Vision software to identify areas of coal reserves that could be remined to improve water quality. Incentives are offered to encourage mining in these designated areas.

Jan 1, 2002

By Yixian Zhao

Although many ultimate pit limit design algorithms have been developed for the past one- quarter century, only the well known Lerchs-Grossmann's (LG) algorithm is capable of producing a truly optimum ultimate pit limit today. This paper presents a graph theory oriented algorithm for optimum ultimate pit limit design. This algorithm produces a true optimal solution and maximizes the total undiscounted net profit for a given 3-D block mine model. The algorithm performs much better than the well known LG algorithm, in terms of the reduction in computation time and computer memory requirements. More importantly the new algorithm is easier to understand and implement than the LG algorithm. Specifically, this paper discusses: 1) the computer representation of arcs and the rules of arc generations which dictate the formation of trees in the graph, 2) the mechanism of joint support and re-allocation, 3) the properties, the general procedures of the algorithm, and the suggested specific steps to implement the algorithm, 4) comparison between the new algorithm with LG algorithm, and 5) some experience in implementation of the algorithm and two case study results.

Jan 1, 1992