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By M. T. Ityokumbul

Flotation columns and their variations are increasingly replacing conventional cells in mineral-processing circuits. While the operational characteristics of columns differ from those of conventional cells, the same scale-up methodologies are being employed. This practice may be attributed to a poor understanding of the factors that control throughput. The use of tall flotation columns is frequently justified because of the need for an increased particle residence time. However, it is shown that longer particle residence times alone do not translate into increased recoveries. In this paper, throughput data from several industrial flotation-column installations is presented. Also, an attempt is made at using dimensional analysis to provide a scale-up methodology for the factors controlling column throughput.

Jan 1, 1997

By S. D. Thompson, L. Adler

Several researchers in the last 20 years have developed computer simulation models for designing coal mine belt systems. A careful review of these reveals that each omitted or oversimplified important factors, especially in belt loading. To remedy this, the coal mine belt capacity simulator (CMBCS) was developed to include various types of probability distributions, delays, and longwall and continuous haulage. CMBCS is computer coded in FORTRAN and employs the Monte Carlo simulation technique. Basically, the model simulates the loading and corresponding flow of coal through a belt system. By recording spillage and belt stoppage statistics for the simulated flow, belt and surge bin capacities can be evaluated. A complete user's guide is available. The modeling and verification of CMBCS are briefly described, and its major advantages and disadvantages are explored.

Jan 1, 1987

By Fernando Muge

A complex pyrite orebody located in the South of Portugal (MO INHO) was exploited in the past by cut and fill methods until a certain level. It was decided to design a new plant for non ferrous metal extraction and the rate of production and exploitation method was modified accordingly. So, a sub level stoping (SLS) method was en visaged for the exploitation of the deepest part of the orebody (under 265 m level). For the planning of this SLS method, it was decided to perform a geostatistical study of the orebody, on the basis of the available information, which consists mainly of channel samples assayed for Cu, S, Zn and Pb.

Jan 1, 1979

By J. A. Herbst, C Lo. Y, Z. Rogovin

The identification and quantification of incipient overload conditions in mills have recently been found to be very significant in the design of tumbling grinding mills. To investigate these phenomena, a series of experiments was conducted in a Plexiglas mill operated in both dry and wet modes. For on-stream measurement of the mill charge weight, volumetric filling, dynamic angle of repose, and mill power, an electronic system was developed. The mill was filled to various levels with 19.1-mm (3/4-in.) ceramic balls as grinding media. As feed material, grindable limestone or 3.2-mm (1/8-in.) nongrinding ceramic balls were fed at various steady-state rates to determine the incipient overload conditions. The prediction of overload has apparently been reduced to predicting the feed rate that results in 50% mill filling.

Jan 1, 1988

By Andrew M. Garvie, William W. Plotnikoff, Eugenia Y. Kuo

Water infiltrating the surface of waste rock dumps transports pollutants into the environment. Lysimeters have been used to quantify the infiltration rate. To date their design has been guided by modeling under steady-state conditions. Recently a two-dimensional finite element code has been developed to model the response of lysimeters to time-dependent infiltration rates. It was used to investigate the response of lysimeters installed in a waste rock dump and subject to a monsoonal rainfall pattern. The results are presented and compared with field data.

Jan 1, 2000

By M. A. Cristovici

The use of surfactants as wetting agents to suppress sulfide ore dust has been investigated. Numerous surfactants were examined to determine their characteristics and to investigate their ability to improve the wetting of the sulfide ore dust. However, the surfactants selected as suitable dust suppressors proved to have a negative effect on the flotation of ore contaminated with such reagents. A method was developed to eliminate the detrimental influence of dust-suppressing surfactants. It consisted of surfactant adsorption on activated carbon and separation of loaded carbon prior to flotation. The technique is simple and requires minimal changes in the plant flowsheet.

Jan 1, 1992

By Chris Chmura, Ketut Karmawan, Ian J. Duckworth

P.T. Freeport Indonesia operates a mining complex located in the highlands of West Papua, Indonesia. Present production from PTFI’s DOZ Underground Block Cave Mine is approximately 40 thousand tonnes per day (ktpd). This paper describes the design process and recommended ventilation infrastructure necessary to expand the DOZ Mine reserves and to increase sustained daily production above 50 ktpd. The enlarged footprint will feature longer production panels of up to 650 m in length, more active draw points, a second large gyratory crusher, and additional men and mobile equipment. The increased ventilation capacity will be achieved through the development of new, dedicated ventilation drifts, and primary Underground exhaust fans.

Jan 1, 2005

By D. Edward, C. Clarkson, B. A. Firth

The presence of misplaced ultrafine particles decreases the separation efficiency of unit operations used in coal preparation. Although the classification of fine coal was considered to be adequate for the needs of the coal industry during the 1970s and 1980s, it is apparent that further improvements in the yield/ash/moisture relationship achieved by coal preparation plants will require increased efficiency in this size-separation step. This paper describes the capability of current and developing techniques to address the problems that need to be overcome.

Jan 1, 1998

By O. Fernandez, M. Vesely

Abrasive grinding, leading to ultrafine product and "critical size" material buildup inside the mill, is proposed as the cause of high power consumption and low capacity in many fully autogenous grinding processes. Addition of steel balls (hence, semiautogenous grinding) or pebble removal and separate crushing have been used, with different efficiencies, to overcome the problem. Information and data for the conceptual analysis, basic design, and operation of a pebble crusher at the Los Bronces semiautogenous grinding plant is presented along with data showing a production increase of 1000 t/d (1100 stpd) and significant operating costs savings.

Jan 1, 1987

By V. Ciribeni, R. J. Ferretti, C. de Arrieta, E. E. Rossi

The relationship between collector concentration and the solution pH at which flotation occurs is discussed for different minerals. When flotation results are plotted as log of the concentration against pH, the values define areas of total, partial or no flotation. The experiments were performed in three different conditions: a) floating with the same solution used for conditioning; b) floating with water at the same pH as the conditioning solution; and c) floating with water at pH = 7. In each case, the results obtained are quite different. It is suggested that the presence of a second layer of collector reduces flotation over some domains in the graphs. These domains are called depression areas.

Jan 1, 1992

By W. J. Dolinar, S. P. Sandoval

The US Bureau of Mines (USBM) implemented the Fe2+/ Fe3+-SO2 anode reaction in a Cu-electrowinning cell with full-size electrodes. Electrowinning was conducted using industrial electrolyte at 258 A/ m2 (24 A/ft2) and 40°C. Manifold injection of electrolyte provided circulation between the electrodes. Five-day operation using an optimized manifold gave an average cell voltage of 0.94 V at 89% current efficiency, which amounted to an energy savings of 2.82 MJ/kg (0.355 kW-hr/lb), compared to conventional electrowinning. Acid milling 5was completely eliminated, and the SO2 concentration 23 cm (9 in.) above the cell averaged 0.06 ppm.

Jan 1, 1996

By R. H. King, R. E. Cameron

Mine managers need better information to locate new opportunities and then to assess the effect of their decisions. We are developing the Intelligent Decision Support System (IDSS) and its two major modules, the Pattern Recognition System (PRS) and the Knowledge Representation Subsystem (KRS) to automatically provide the information from monitoring system sensors. This paper focuses on the KRS Algorithms that extract key information from lists of time-study type event sequences. Because a static system cannot operate effectively in a dynamic mining environment, we are prototyping an index- based technique that allows the system to adapt itself to this dynamic environment.

Jan 1, 1991

By G. Zandt, H. R. Pratt, W. A. Hustrulid, M. Bouchon, D. E. Stephenson

PREFACE The National Waste Terminal Storage Program was initiated to conduct the research to select a site for the disposal of high level radioactive waste in deep geologic formations. As part of this program, the Savannah River Laboratory at Aiken, South Carolina, is conducting geologic research of generic applicability on the potential subsurface damage to a repository from an earthquake. Part of this study involved the collection of data on subsurface damage due to an earthquake, and another part involved the calculation of displacement fields as a result of an earthquake. Both of these studies were conducted at Terra Tek of Salt Lake City. This report is an abridged and combined version of both studies which was presented at the Rapid Excavation and Tunneling Conference in Atlanta, GA, on June 19, 1979.

Jan 1, 1979

By Jerome P. Downey

Treatment of tungsten ore at Anschutz Mining Company's Chicote Grande (Bolivia) operation results in a relatively high grade arsenopyrite byproduct stream. Laboratory and miniplant testwork have been performed at Colorado School of Mines Research Institute to examine the technical feasibility of recovering a marketable arsenic product fr an this source. Process selection was constrained by the remote location of the millsite, which demands an uncomplicated, low maintenance operation. As a result of the research effort, a two-stage roasting/condensing process was developed, featuring the use of an indirect heating method. Arsenic was efficiently extracted and the arsenic trioxide (As203) product consistently exceeded the industrial purity specification of 99.5%. Key process parameters have been secured for extrapolation of the process to pilot or small commercial scale.

Jan 1, 1985

By Keith G. Wallace, Malcolm J. McPherson

In order to model accurately a mine ventilation system in an existing mine, it is necessary to determine the resistance to airflow in all main airways. This is accomplished by measuring the airflow and pressure differential in each airway. Gauge and tube methods have been used to determine pressure drops in ramps and level airways. However, it has rarely been used in evaluating the frictional pressure drop in shafts. Because shafts commonly have the highest pressure loss in mines, it is critical that the resistance of these airways be determined accurately. This paper describes the theory and practice of using the gauge and tube method for determining the pressure drop in shafts. The pros and cons of using this method are discussed as well as a comparison between the gauge and tube and barometer measurement techniques. Case studies showing the accuracy of shaft gauge and tube measurements are also presented.

Jan 1, 1991

By C. Bemelmans, L. Chia, T. O’Keefe

Lead alloys function effectively as oxygen-evolving anodes in copper SX-EW operations, and they are highly resistant to corrosion. However, the presence of an organic (from solvent extraction circuits) in the electrolyte seems to enhance solution line attack. Laboratory tests showed that lead is soluble in D2EHPA, Acorga and LIX 984 to a limited, yet measurable, degree. Lead alloys and various lead phases formed on the anode were tested to evaluate their effect on the corrosion process in organic media. Possible causes for anode corrosion and mechanisms responsible for their initiation are discussed.

Jan 1, 1998

By F. M. Doyle, S. M. El-Raghy, M. F. El-Demerdash, E. Peters

The Activity Distribution Diagrams (ADD) developed by the authors are computed for Cu-S-H2O and Mo-S-H2O systems. The distributions of metal and sulfur between all species are estimated against pH at different potential levels. Both M-H2O and S-H2O distributions are compared to the M-S-H2O distributions to estimate the changes occurring due to the presence of sulfur. The method of computation follows the Activity Term Criterion, taking into consideration the multi-equilibrium interrelations and conservation of mass. Results are analyzed in terms of dividing a distribution curve into three basic segments. These segments are formation, stability, and dissolution.

Jan 1, 1993

By K. H. McDaniel, D. M. Loring

The underground ventilation system at the Waste Isolation Pilot Plant (WIPP) provides for the unparalleled ability to ensure the safety of the workers, the public and the environment. Although small spatially, the system can vary the airflow from 31.2 to 217.1 m3/s (66,000 to 460,000 cfm). The system can automatically incorporate HEPA filtration in the event of radioactive contamination. Remote-capable regulators individually control the four main splits, and they can be adjusted from the surface if necessary. A ventilation remote-monitoring and control system provides real-time information. Future areas of concern include DPM compliance, system psychrometry, logic-based real-time mine-ventilation simulation and automation using PLC technology. This paper discusses the evolution of this system.

Jan 1, 2003

By M. Scherbakov, W. Shi

Abrasion is an important mode of performance for any element of an engineered product that involves material contact for example, a conveyor belt cover. Abrasion resistance is considered to be one of the leading factors in belt cover design and improvement. Various types of abrasion testing are reviewed by and compared to actual belt applications. A new quantitative screening torsional abrasion test is developed by Goodyear to mimic a dynamic contact between belt cover and differently shaped stones of various weights dropped onto belt at any angle, velocity and height.

Jan 1, 2004

By Craig J. Nelsen, David A. Smith

In 1987, LAC Minerals (USA), Inc. conducted a high resolution helicopter electromagnetic (EM) and magnetic geophysical survey on the Ortiz Mine Grant, New Mexico. The primary purpose of this survey was to assist in geologic mapping of a major structural zone, the Tijeras-Canoncito Fault System (TCFS). This structure is a very important ore- controlling feature in the area. Geophysical signatures over known deposits was a secondary goal of the survey, but direct detection of mineralization was not anticipated. The TCFS was revealed to be a complex, branching and anastomosing system of faults which locally form the bounding structures of a graben. The geophysical survey guided subsequent geologic mapping by redirecting field investigations, and geophysically redefining some features which previously had been only partly defined.

Jan 1, 1989