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By Don Langlois, Udo Weber

"The effect of grinding media performance on milling and operational behaviour was demonstrated under different selected milling conditions of calcium carbonate. A variety of grinding media material and bead sizes, along with 2 different stirrer tip speeds, were used in the grinding process to generate a particle size reduction of the calcium carbonate (CaCO3). To determine the optimum milling parameters the collected test data was used to calculate and evaluate specific energy as well as stress intensity under different milling conditions.INTRODUCTIONAs a result of increasing energy costs and raw material prices it is important to look at the efficiency of the manufacturing process. Wet grinding and ultrafine wet grinding in stirred media mills are now a possible cost-effective production step for the processing of industrial minerals and precious metals. The generation of smaller particle sizes (down to micrometer scale) can be advantageous for further production steps – i.e. better liberation of precious metals or improved industrial mineral qualities.In the following, the wet grinding process is investigated under different milling conditions of calcium carbonate. Different grinding media materials varying in specific weight, bead size and stirrer tip speeds are used to determine optimal energy consumption for the milling process.DESCRIPTION OF TEST CONDITIONS AND PARAMETERSMill ParametersTests were performed in a Drais Laboratory Perl Mill PML H/V with an installed electrical motor power of 3 kW. The mill chamber is silicon carbide where as the stirrer and discs are made of yttria stabilised zirconia. The mill working volume is 0.9 l. A screen cartridge with a screen size of 0.2 mm is used to separate the beads and slurry at the outlet of the mill. All tests were performed with a grinding media filling grade of 80% (Mill working volume). The stirrer tip speed was set at 6 m/s and 10 m/s."

Jan 1, 2009

By Jon Sinnreich

Ensuring the accuracy of collected data during deep foundation static load tests is of paramount importance. Typically, pile head displacements are measured relative to a purpose-built reference system, which is assumed to be fixed. This study presents a simplified error analysis of this assumption, illustrates the potential magnitude of these errors, and proposes an improved method of pile head displacement monitoring.

Jan 1, 2009

The 23rd annual American Mining Hall of Fame Awards Banquet sponsored by the Mining Foundation of the Southwest will be held at the Tucson Marriott University Park Hotel, Tucson, AZ on Saturday, Dec. 3, 2005. The Mining Foundation of the Southwest is a non-profit organization. It educates the public about the mineral industries and reports outstanding accomplishments in the fields of mining and the earth sciences. This year’s inductee, guest of honor and featured speaker at the banquet will be Pierre Lassonde, president of Newmont Mining and resident of the World Gold Council. He is one of Canada’s leading gold analysts.

Jan 1, 2005

By W. Hurst

The authors of this paper, in substituting values in a material balance equation associated with a gas reserve and a water drive, cannot find sustainment of what the gas in place should be; therefore, their conclusion is that this type of problem dealing with gas reservoirs is insoluble. They have introduced the word, "cybernetics," based on the work of Norbert Wiener, that further extends this line of reasoning, namely, to the effect that the system is a "black box", and that the gas reservoir and aquifer can take on infinite aspects 'based upon their past performance, to quote the authors. The inference is that this black box is an unknown. which permits in computer programming to subscribe as many variables as possible to observe by adjustment of one to another those combinations of conditions that fit field behavior. This may satisfy those in this discipline whose dedication is to programming, but to the others this is a comparison to the rationalization of the combinational results of the throwing of dice—a probability procedure. In reservoir engineering we are more direct. We learn from the examination of individual we'll and field data exactly what is in this black box. I now come to the impasse that has confronted these authors in their machine calculations. In this I have reproduced from their own production data (Tables 1 and 2 of their paper) pressure vs cumulative gas produced. shown as Figs. D-1 through D-5. A perusal of any of these five plots, for the corresponding fields in the Po Valley, shows the straight-line relation of pressure vs gas produced, evidencing pressure depletion. The point I make is that in their fundamental production data, there is no variance from a straight line that can support a water drive.

By Rudy Tenbergen, Dick Farmery, Jim Naylor

"Paste backfill has replaced cemented rock fill as one of the components to improve ground · control and mine safety at the Macassa Operation of Kinross Gold Corporation in Kirkland Lake, Ontario. It is the first operation to utilize "" flash thickening ""of very fine gold tailings to a paste consistency in the ""Paste Production and Storage Mechanism"", a joint technical development of Inco and GL&V. The tailings paste is mixed with alluvial sand to produce an engineered quality paste backfill. The development leading up to the decision to proceed with this novel technology is discussed, as well as commissioning of the backfill operation.IntroductionThe occurrence of a major rockburst on November 23, 1993 prompted a review of mining and backfill procedures at the Macassa No 3 shaft . This shaft is some 7238 ft deep and lies in a mining belt that is prone to seismic events. The recommendations were to change the mining from underhand cut and fill to mechanized long hole stopping and to look at alternatives to the rockfill backfill system in place. The Macassa cemented rock backfill operation, while producing the desired fill stiffness had drawbacks as compared to paste fill. With paste fill, placement rates are faster, more openings can be filled, it is less expensive and less prone to the occurrences of compensable incidents.Macassa mining personnel visited the Sudbury operations of Inco in 1993, where development on paste backfill was in progress. As some of the R&D was taking place with funding from the Premier's Council Technology Fund of the Ministry of Trade and Technology of the Province of Ontario , Inco personnel at that time did some feasibility and conceptual consulting on the use of paste fill for the industry. Inco had developed the use of alluvial sand paste fill, an engineered blend of alluvial sand and tailings fines and was doing development work to eliminate the ""conventional"" way of producing paste from mill tailing by thickening and filtration. This latter development work was taking place with GL&V Ontario. That work led to the filing of a joint Inca/ GL&V patent application for the PPSM, the Paste Production and Storage Mechanism with all marketing rights being held by GL&V."

Jan 1, 1997

By L. F. Bishop

THE ore bodies of the Butte district1 are found in many different vein systems having many different structural characteristics; some are narrow with self-supporting ore but with weak walls; some are wide with weak or strong ore and weak walls; some of the veins dip steeply and others do not; some have well defined walls, and others, in the "horsetail" area, are mined to sample limits. Consequently, many types of stoping methods are used in mining these ores. The stoping methods used in the Anaconda Copper Mining Company's properties are the square-set and cut-and-fill. The square-set method is the principal stoping method used because, generally speaking, the ore and walls are weak, the ore is high grade, and good extraction is required. These square-set stopes may be classified as conventional, vertical slice, slot, timber rill, and Mitchell slice types. The conventional type square-sets are those of various shapes and sizes, mined by horizontal slicing to the boundaries of the stopes. The rock is slid to the chute and the filling is moved by gravity. The ore and waste may be handled with a scraper when local conditions require it. The vertical-slice square-set system is the type used in narrow veins that are mined in vertical panels. The slot stopes are stopes in wide veins that employ a slot across the vein instead of a con- ventional chute to handle the ore. The timber rill fs a type of square set in which the ore is mined as in inclined cut and fill but the square-set timber is used. The Mitchell slice is the type used for some broken or heavy ore blocks, or for pillar extraction between two converging slot stopes. The cut-and-fill method is used where the ore will stand without much support although the walls may be weak. The principal type of this method is the horizontal cut-and-fill, with mechanical scraping. The inclined cut-and-fill, or rill, stopes are used in some veins too narrow for scraping. The production from the various meth: ods in use for the second six months of 1944 are shown in Table I. [ ] This paper deals mainly with the vertical slice and slot types of square-set stoping, because of their effect on production locally and their potential possibilities here and in other districts, with sufficient reference to conventional square-setting for comparison.

Jan 1, 1945

By R. H. Colquhoun, A. W. Bolland, H. J. H. Pieterse

"American Barrick Resources Corporation acquired the goldstrike property in north eastern Nevada in early 1987. Since that time, the company has undertaken an extensive development program. This paper will overview the milling, autoclaving, and heap leaching facilities which are part of the $400-million Betze development plan. Gold production at the Mine has increased from 40,000 ounces per annum in 1987 to more than 500,000 ounces in 1991. And in 1992 Goldstrike will be the single largest North American gold mine when it produces 1,000,000 ounces.1. SUMMARYAmerican Barrick Resources Corporation acquired the Goldstrike property in northeastern Nevada in early 1987. Since that time, the company has undertaken an extensive development program. This paper will overview the milling, autoclaving, and heap leaching facilities which are part of the four year, $440- million Betze Development Plan. Gold production at the Goldstrike Mine has increased from 40,000 ounces per annum in 1987 to more than 500,000 ounces in 1991. In 1992, Goldstrike will be one of the largest North American gold mines, when it produces appro approximately 1,000,000 ounces.2. INTRODUCTIONAmerican Barrick Resources Corporation is in the process of developing the Betze gold deposit, located on Barrick's Goldstrike property in the Carlin area of Nevada, U.S.A.The Goldstrike Mine has 17.9 million ounces of proven and probable reserves and an additional 460,000 ounces of possible reserves. Additionally, the Purple Vein deposit, one mile north of the Mine, is expected to add at least 4 million ounces of reserves by year end 1991.The Goldstrike ore body contains both oxide and sulphide ore. The largest part of the reserves are contained in the high grade, deep sulphide ore. Mining of the sulphide ore contained in the Betze deposit involves the removal of large quantities of overlying oxide ore. Oxide ore is treated through one of the following processes:-"

Jan 1, 1992

Beneficiation of Coal Fines from Tailing Ponds of Tuntbilek Washing Plant

Sep 13, 2010

By A. Bhattacherjee

The Shewhart [X]?and R charts are still the most popular control charts in use today for continuous monitoring of quality data. However, for these charts to function properly, the underlying assumption of normality and independence of data must be satisfied. When either independence and/or normality of data are not present, which is a common feature of ore quality data, an application of the conventional Shewhart [X]?and R charts may introduce false alarms in the analysis of the data. To address these issues, a guideline is proposed for construction of appropriate univariate and multivariate control charts for a variety of situations. A use of this guideline to a bauxite mine suggested the construction of special cause control chart for the analysis of individual variables namely, Al2O3% and SiO2%; whereas, the multivariate T2 chart based on residuals is proposed for the bivariate analysis of the variables. The case study clearly revealed that without considering the data correlation, one may be in a state of false impression about an out of control condition while using the Shewhart [X]?and R charts for univariate and the Hotelling T2chart for multivariate analysis. To compare the effectiveness of the control charts, specifically the Shewhart [X]?and the special cause control charts, a simulation study was conducted. It was found that the conventional Shewhart chart provided lower probability of coverage than the special cause control chart. It was also revealed that the quality specification of Al2O3% is met as the variation of Al2O3% is well within the specification limits; whereas, it is difficult to meet the quality specification of SiO2% on a regular basis.

Jan 1, 2002

By L. K. Bandyopadhyay

The expert system component of Knowledge Base System supports the analysis and interpretation phases of ventilation design with an algorithmic program used for the solution of alternate design. The paper describes the ?ES-VENT? knowledge based system developed at Central Mining Research Institute, Dhanbad, India for an on-line diagnosing of the ventilation problems using the ?IITMRULE? expert system development tool. In the ?IITMRULE? expert system tool, it has been decided to use a backward chaining reasoning process to reach the goal state i.e. the final conclusion. ES-VENT system is made of three modules: On-line Data, Diagnostics and KBS. Each module is being a collection of several programs. The paper mainly deals with the parameters affecting the ventilation of underground mines such as air-velocity, air pressure, temperature, dust, and humidity and gas contents. The graphical presentation of these parameters on the computer and the interactive part of the developed program is expected to help a ventilation officer to determine the changes in a ventilation circuit necessary to bring the mine ventilation to the desired value. Once such changes are physically effected, the display will indicate if the changes have brought the desired effect or not on ventilation. Keywords: Ventilation network, on-line data, expert system, intelligent system, knowledge base, inference engine.

Jan 1, 2002

By K. Y. Haramy, R. O. Kneisley

This U.S. Bureau of Mines report summarizes a study of large-scale strata response to longwall mining at a western U.S. coal mine. This study utilized surface and subsurface measurements, geologic mapping, in situ stress measurements, and pressure cell readings to characterize strata behavior. Preliminary analysis of surface subsidence and time-domain reflectometry (TDR) was used to determine a suggested main roof caving sequence. Coal ejected from the face apparently resulted from brittle failures that occurred because of lack of significant yield zone development. The combination of a strong coal with pronounced directional behavior, low overburden pressures, a good caving roof, and a high-production environment that minimized time-dependent loading apparently reduced yielding of the longwall face. The panel 1 headgate-entry design appears adequate; however, the abutment pillar and adjacent panel tailgate rib are highly stressed and may contribute to problems during second panel mining. The small chain pillar yielded after passage of the face, but the pillar width may be near maximum since evidence of a stressed core exists.

Jan 1, 1992

Continuously monitor and record respirable dust levels underground by a reliable, sensitive, and fast-response device. Approach A light-scattering photometer, having a LED (Light Emitting Diode) light source and other significant improvements, has been designed and incorporated into a portable continuous monitor. How It Works The monitor continuously draws air into the sampling inlet through a cyclone that removes dust particles larger than respirable size. The dusty air enters the photometer vertically downward through a cylinder which is intersected by the optical system. (This cylinder appears as a circle in the drawing of the photometer.) The center of he column of dusty air intersects a beam of pulsing light from the LED, causing some of the light to be reflected, scattered, and refracted. Only the light that is scattered at an angle of about 700 from the light beam passes through a lens to the photodetector which generates an output voltage Signal proportional to the dust content in the air. This signal is detected, amplified, and converted to a digital readout directly in milligrams of dust per

Jan 1, 1979

By Lenin Salazar Dulanto

La baja de precios en algunos minerales ha obiligado que las empresas mejoren su proceso productivo a través del uso de equipos de última tecnología en los procesos de mecánica, hidráulica, electricidad y electrónica, así como en la eficiencia en el corte y taladrado, extracción y transporte. Sin embargo, tanto el desatado y sostenimiento manual desarrollaron un estréss y desgaste de energía en el trabajador. En este sentido, el presente trabajo señala una nueva forma de realizar tales operaciones en el ciclo de minado de la empresa Milpo a fin de garantizar la seguridad física de los trabajadores y equipos.

Jul 31, 2003

By D. R. Babich, E. R. Bauer

Noise-induced hearing loss (NIHL) in mine workers, especially underground coal miners, continues to be a problem in the mining industry. The recently enacted MSHA noise standard, Part 62 – Occupational Noise Exposure (Federal Register, 1999), is aimed at reducing NIHL in the mining industry. The U.S. National Institute for Occupational Safety and Health (NIOSH) is conducting a cross-sectional survey of noise sources and worker noise exposures to address NIHL in various aspects of coal mining including surface mining, coal preparation plants and underground mining. In underground bituminous coal mining, noise surveys, consisting of full-shift worker noise exposure, time-motion studies and equipment noise profiling, have been completed on longwall and continuous miner sections in six underground coal mines. The studies revealed widely varying shift-to-shift worker exposures, with workers in certain occupations routinely exposed to potentially hazardous levels of noise. A summary of these studies is reported, including worker dose, source/dose relationships and equipment noise profiles.

By Amalia Giannakou

This paper utilises 3-D finite-element modeling to study the static and dynamic lateral harmonic response of inclined piles, in a homogenous and a non-homogenous soil, modeled as a linear hysteretic medium. The results of a comprehensive parameter study are presented in the form of dimensionless plots of: (a) static and dynamic swaying and rocking stiffnesses and damping ratios, and (b) distribution of internal forces (bending moment, shear and axial force) with depth. These plots can be readily utilised in practical applications and they offer insight on the role of the inclination in the response of flexible piles.

Jan 1, 2006

By L. K. Walker, G. A. Kosick, P. D. Young

"MillEX is an information management system designed by mineral processors for mineral processors. The system utilizes ""cutting edge"" software technology to gather and store all automatically and manually recorded data from the plant operation and laboratories. This data is delivered to the desk of superintendents, metallurgists, technicians and managers, and permits the user to query, correlate, graph, report and present this data in minutes. In the past this task would have taken days and even weeks of tedious work to complete.MillEX allows the engineer/analyst to quickly develop a very thorough understanding of the complex relationships of process variables and equipment that exist in the plant, and their effect on product quality and quantity. The time and resources that are currently wasted on duplicating data entry will be an effort of the past.This paper describes the structure of MillEX and how it conforms to the needs of mineral processing personnel.INTRODUCTIONPicture a personal computer on your desk which will carry out the following commands:1. Plot a graph over the last six months, using weekly averages, of percent minus 200 mesh material in the primary cyclone overflow.2. Overlay this graph with a graph of concentrate grade versus recovery over the same time period.3. Retrieve a prior month end report, update all operating supplies tables and metallurgical performance with this months data, and embed the graphs created above.4. Edit text and print the current month end report. This is only one example of the type of power MillEX isbringing to the mineral processing industry."

Jan 1, 1992

By D. Bedell, J. Robitalle, D. Macgilliveray

Agnico Eagle (Cadillac Quebec, Canada) selected the new Eimco PEC E – CAT™ clarifier thickeners for their counter-current decantation circuit, which handles approximately 200tph leached gold/silver ore. The E-CAT is based on rakeless ultra-high rate thickening technology that originated in South Africa. Four 9m diameter and two 10m EIMCO E – CAT ultra high rate, rakeless thickeners were installed in the fall of 2000. Thickening and clarification performance has been excellent. Problems with level control have been resolved and the plant personnel continue to improve the operating control techniques. The CCD circuit is critical to the success of the operation and good recovery. Data will be presented showing the wash ratios and recovery achieved. A brief history of the operation and the decision to utilize the CCD system will be presented.

Jan 1, 2002

By D. G. MacBeth

Most belt scales on the market are factory calibrated to minimum accuracy figures of 0.1% - 0.2% at several load points. However, if the same belt scale is not properly installed and maintained on the customers conveyor then the scale will not measure up to the claims of the manufacturer or to the requirements of the operator.

Jan 1, 1975

Jan 1, 1967

By Pierre Mousset-Jones

A questionnaire was sent out to three classes of mines to determine the extent of the heat problem in U.S. and Foreign underground mines. The following list shows the replies received from this questionnaire, however not all the known hot mines in the US replied. A complete listing of the results can be seen in Appendix I. 1) US coal mines - 37 replies 2) US non coal mines - 23 replies 3) Foreign non coal mines - 36 replies. At the present time there are approximately eleven non coal and one coal mine in the US experiencing heat problems which require special efforts to maintain an acceptable working place climate. However since the survey was completed some of them have been placed on standby. The Mine Safety & Health Administration (MSHA) does not have any specific regulations relating to heat stress. Informally the American Conference of Governmental Industrial Hygienists guidelines are followed which use wet bulb globe temperature (WBGT) with values ranging from 26.7°C to 31.1°C for a moderate workload, and different rest regimes. An MSHA report (Misaqi 1976) recommended that conditions should not exceed 26.1°C WBGT for men and 24.4°C WBGT for women. However, quite recently the organizations involved with planning two of the proposed nuclear waste repositories in the United States, have opted for the criteria of an air cooling power of 300 w/m2, and a WBGT of 27'C respectively.

Jan 1, 1986