Search Documents

By W. Petruk

Imaging is a fundamental requirement when characterizing minerals, ores and related products. Images are used for presentation, texture analysis, characterization, image analysis, identification, etc. The image mode that is utilized is dependent upon the application, mineral properties and available instruments. Different instruments produce images that display different features; in order of increasing complexity they are: hand specimens, a non-polarizing microscope, polarizing optical microscope, scanning electron microscope (SEM), low vacuum SEM, microprobe, secondary ion mass spectrometer, staining, cathodoluminescence, tomography and others. Image analysis uses images produced with either an optical microscope or a SEM, but the SEM images are superior in this application.

Jan 1, 2001

By Paul H. Lu

Methods and results of measuring three basic parameters for ground stability control, ground pressure, strata movement, and geomechanical properties of mine rock are presented in this paper. It is found that these parameters can be measured in situ by simple and practical techniques with nonsophisticated and inexpensive instruments. Specifically, a drillhole dilation technique employing a cylindrical hydraulic borehole pressure cell (CPC) was used to determine the modulus of rigidity. Premining ground pressures were determined by pressure convergence tests with a combination of one CPC and two pre-encapsulated flat hydraulic borehole pressure cells (BPC) installed in a single drillhole. Abutment pressures and pillar loading were monitored with BPC's. Differential strata movements and bed separations were measured with self-recording 10-anchor-point extensometers. Roof-to-floor convergence was measured with self-recording convergence meters. Some applications of these in-situ-determined parameters to mine design and ground stability control are also discussed.

Jan 1, 1984

By John Starkey

"The development of the SAG Power Index (SPI) Test in Canada has created a new and accurate way to measure ore hardness in a SAG environment. Coupled with the standard Bond Ball Mill Work Index Test it is now possible to determine from these two relatively inexpensive laboratory tests, the amount of energy required to grind an ore from the primary crushed size to the desired liberation size. By testing multiple samples to discover where the hard and soft ore zones are located, the representative hardness distribution for the ore body can be determined and grinding equipment selected that is capable to meet production targets for all mining areas of the deposit.Previously, it was deemed prudent to select up to 50 t samples of ore for Semi Autogenous Grinding (SAG) pilot plant tests and a second 5 t sample for metallurgical pilot plant work. The methods outlined in this paper show how the 50 t sample is no longer required for SAG design because it is better to measure the representative hardness distribution of the ore body than the hardness of a “chosen” representative sample. This is demonstrated to be true by the fact that the lower horizons of an ore zone cannot initially be accessed to recover 150mm pieces, and the bulk samples taken, rarely represent the desired design hardness of the ore. Median hardness will not yield a good result in most cases and a clear understanding of the location and extent of the hardest zones is imperative to achieve a truly successful grinding circuit design.This paper discusses two plants (Kubaka and Agnico Eagle) that have been designed using SPI and Bond with no pilot plant test backup. Both have been very successful in that they can grind design tonnage on the hardest ores in the mine. This guarantees that the mine’s profitability is protected in any mining sequence. It also allows the extra power to be converted to higher throughput on softer ores if additional cash flow is needed. The advantages from the owner’s point of view are dramatic. This procedure will be attractive as well when considering the costs for test work, and the samples for testing. Existing diamond drill core is normally used and this allows the inclusion of data from the deepest regions of the mine. In addition, it is also clear that the decision to use a crusher can now be made at the design stage of a project based on measured parameters and the estimated capital costs of alternative designs."

Jan 1, 2003

The Rio Tinto - Cerro Colorado operation was the first major cyanide plant built out of South Africa since the Carlin and Corte mills came on-stream in 1965 and 1969. Its flowsheet was presented in the original monograph, "Gold and Silver Cyanidation Plant Practice, " published in 1975, with a brief description of the plant but without the operating costs. The authors have recently received these data and it was believed worthwhile to present them in this volume along with the aforementioned flowsheet. The Cerro Colorado ore deposit is located at Minas de Rio Tinto in the province of Huelva, Spain, approximately 88 km (55 miles) north- west of Seville. The previously mined copper ore bodies lie on either side of the deposit which is mainly copper ore. The crest of the deposit is a capping of "gossan" containing hematite, limonite, gold, and silver. Separate facilities for primary crushing, concentration of copper ores and cyanidation of gold-silver ores are provided. Fine crushing is common to both ores. The run-of-mine open-pit ore is fed from a stockpile via a surge bin and apron feeder to a jaw crusher. After crushing to minus 150 mm (6 in. ), the ore is washed in a rotary scrubber to remove the clay material ahead of fine crushing. Minus 6 mm (1/4 in. ) screen undersize is pumped directly to the grinding circuit with the screen oversize being crushed to minus 19 mm (3/4 in. ) for feed to the primary ball mill; this is followed by two subsequent stages of ball mill grinding to 80% minus 43 microns (325 mesh). Grinding is with water only; no cyanide is used. After thickening, lime is added to the first two of seven Pachuca tanks for conditioning ahead of cyanide addition in each of the five remaining Pachuca tanks. This flowsheet indicates rapid cyanide consumption and the need to maintain a high strength cyanide solution for silver extraction. Agitation for dissolution of the gold and silver is followed by standard CCD practice employing four 67 m (220 ft) washing thickeners in series, with repulping between each thickener. A departure from American and Canadian practice is the use of Stellar filters developed in South Africa for pregnant solution clarification and recovery of zinc-gold-silver precipitates. The precipitate is treated with acid for zinc removal, the sludge filtered in presses, dried, calcined and smelted to produce dore bullion of 900 fineness containing 12% gold and 78% silver.

Jan 1, 1981

Beaches contain the residue of eroded rocks which have resisted weathering, and it is common to find in all beaches some of the harder, heavy minerals. The natural sorting action of waves and winds tends to concentrate the heavy minerals into banded deposits.The value of such deposits is extremely variable. Even amongst the more concentrated deposits, the principal minerals, in the vast majority of cases, are magnetic, titaniferous magnetite and other forms of iron oxide, which, in the present state of mineral economics and technology, are of little or no value.Valuable minerals of fairly common occurrence in beach sand deposits are rutile, zircon, ilmenite, monazite and chromite, and each of these minerals, as well as others of less common occurrence, is obtained from beach deposits in various parts of the world.Along a stretch of 300 miles of coast from Coff's Harbour in New South Wales to North Stradbroke Island in Queensland, occur unique concentrations of heavy minerals. The principal minerals which occur are rutile, zircon and ilmenite, and for some years these deposits have contributed half to three-quarters of the world's consumption of rutile and zircon 1, ,2. The only other notable beach sand concentrations in Australia are at a number of places in the southwest of Western Australia, where deposits containing highgrade ilmenite are being developed.

Jan 1, 1950

Contribution by F.S.A. de Frey The authors are to be congratulated on a job well done by making, in their paper, such a pool of information available to mining engineers. I would like to comment on the following statement: 'As an alternative to the commonly used deep-level mining methods, consideration should also be given to pillar mining at great depths as a logical extension of the current methods. For example, a 75 per cent extraction Or Ryder's discussion The moderate levels if average pillar stress (APS) (320 MPa) are consistent with pillar stability. Squat 10:1 pillars should never 'fail' in themselves, and foundation strengths are also not exceeded (the stresses are well below the 2 ½ x UCS rule-of-thumb provided the foundations comprise normal strong 200 MPa quartzites). Authors' reply We thank Dr de Frey for his contribution to our paper on shallow hard-rock pillar systems. To considerable extent, we share his enthusiasm the potential role of squat pillars in deep-level mining, although we harbour reservations concerning strata control, mining economics, other issues. We agree wholeheartedly that further research, together with carefully planned field trials, is warranted in pursuit of this potentially highly rewarding concept. .

Jan 1, 1995

By Alan L. Mierke

West Virginia's economy has been closely linked with coal. West Virginia is consistently one of the top three coal-producing states. Its 149 Mt (164 mil¬lion st) produced in 1992 represented 16.5% of total US coal production. In recent years, the state's economy has experienced a diversification away from its traditional employment base of min¬ing and heavy manufacturing. However, the coal industry remains an integral part of the lives of West Virginians. Coal is mined in 33 of the state's 55 counties. In many of these counties, the coal industry is the largest private employer and contributor to the economy. West Virginia has three major coal-producing regions. The northern region produces coal high in gas and sulfur content (steam coal). It is consumed primarily by utility and industrial markets. The southeast region produces high-grade coal low in sulfur content but high in carbons and Btu (metallurgical coal). The southwest region produces metallurgical and steam coal. The high-grade metallurgical coal is used in the production of coke for steel manufacturing. Metallurgical coal also comprises the majority of coal exported from the United States. During 1993, West Virginia was the country's largest exporter of coal, accounting for 44.5% of total US coal exports.

Jan 1, 1995

By H. Gumede

The occurrence of fracturing due to high stress levels is a major factor in hangingwall stability in deep level gold mine stopes. However, rock falls cannot be the result of these fractures alone. Rock falls can result only from the occurrence of unstable rock blocks defined by the interaction of the stress induced fractures and naturally occurring geological planes of weakness. These planes include bedding planes and joint set planes. However, there is a general lack of information on the characteristics of these planes (orientations, spacings and lengths)?it does not appear that any such systematic and quantified information, if collected, has been published. To remedy this situation to some extent, joint mapping exercises have been carried out in several geological environments in two gold mines. The data collected on joint geometry included orientation, spacing and length, and this information is included in the paper. In addition, the paper describes the use of the data collected to evaluate the potential for rock falls and the probability of failure of stope support

Jan 1, 2007

By Joseph G. Wargo

An investigation of trends in exploration expenditures for a selected group of mining companies was undertaken for the interval 1968-1971. These trends were compared with financial factors that are associated with various groups of companies and the implications of these trends are indicated. The sample consists of 21 mining companies, of these, 19 are listed on the New York Stock Exchange and 2 are listed on the American Exchange. Twenty are American, one is Canadian. All are fundamentally "mining companies" in that they derive the bulk of their income from the ex- traction, sale, and at times, fabrication of metals from their own mines. This is in contrast to companies which have mineral exploration departments but derive the bulk of their revenues from sources other than mining, such as oil and gas sales. No companies which can be considered strictly as exploration companies are included in the sample. This definition held up in 1968, however, its strict application became more difficult through the years. In 1971, three or four of the companies were changing their character in that they were phasing out of the mining business and deriving a substantial part of their income from activities other than mining.

Jan 5, 1973

By S. C. Bouffard

Barrick's Zaldivar operation in Chile produces copper by heap leaching, solvent extraction, and electrowinning. The heap consists of a dynamic pad, and its stacking and operating conditions have changed over its 11 years of operation. These changes have included pad re-mining midway through the cycle, tightening of the irrigation drip lines, an increase of the coarseness of the particles, and an increase of the heap height. This paper reviews the heap operating data to understand the effects of these changes on the kinetics and recovery of copper minerals. Field tests demonstrated that neither re-mining nor tightening the irrigation grid added value for both low and high grade oxide and sulfide ores. The P80 of the feed ore was increased by 0.8 mm, which did not reduce the copper recovery of oxide and sulfide ores. The increase of the heap height above 8 m lowered moderately the copper recovery from sulfide minerals, and very slightly the recovery from oxide minerals. Despite the lower recovery, the higher tonnage stacked in the taller heap increased the copper output. Optimizing the chemistry of the agglomeration and feed solution holds more promise for increasing the copper recovery than the above physical changes.

Jan 1, 2007

By M. Botz

For leach solutions containing primarily free cyanide, the silver nitrate titration method is a rapid and acceptably accurate means of analyzing for cyanide. However, in leach solutions containing elevated levels of copper, the titrimetric method significantly over-estimates the concentration of free cyanide and under-estimates the concentration of weak and dissociable (WAD) cyanide. The authors have developed a modified potentiometric titration method for determining WAD cyanide that overcomes issues with high copper levels in solution. The new MP-WAD method involves addition of a chemical ligand to the sample prior to silver nitrate titration to fully release cyanide bound to copper. Once released from copper, cyanide in solution is no longer affected by the presence of copper and titration results are quantitative rather than empirical. In multiple laboratory trials with synthetic solutions and complex actual leach solutions, accurate WAD cyanide measurements were achieved using the MP-WAD method. Analyses obtained with the new method were found to be within about ±10% of analyses obtained with the USEPA OIA-1677 WAD cyanide analytical method.

Feb 27, 2013

By Sharon K. Reamer, Klaus G. Hinzen, Brian W. Stump

"This study investigates seismic wave propagation from two production shots in a limestone quarry. Our motivation is to investigate the efficiency of two superpositioning techniques. The production shots consisted of an 18 and 20 hole explosive array detonated in a single row with constant delay times of 32 and 20 ms, respectively. A single shot was fired on a neighboring part of the quarry bench. The experiments were instrumented with 20 three component seismometers (35-120 m range). The computer-controlled electronic firing system resulted in firing time deviations of less than 1.4% of desired fired times. Linear superpositioning with the observed single shot data produces seismograms which adequately reproduce temporal effects of the multiple explosions; however, spatial effects due to the extended source length (68-76 m) are not modeled with this method. Linear superpositioning with individual half-space Green's functions for each explosion in thearray convolved with a calculated Mueller-Murphy source produces seismograms which match the time duration of the observed production shot seismograms and differ in absolute peak amplitude by less than a factor of three. Parameter estimation for the source is taken from chemical explosion study results. The single source model differs in amplitude from the observed single source seismograms by a factor of 2.3."

Jan 1, 1991

By James Cudworth

THE Birmingham district of Alabama has utilized the slag from its blast furnaces consistently since the earliest development of the slag industry. Today there are producers of slag cement who started business in 1900, and who have, under a progressive policy, expanded the number of their products to meet present demands. There are producers of slag aggregates and other crushed slag products who have been successful for periods of over thirty years. There are at the present two companies, Cheney Lime and Cement Co. and the Southern Cement Co., manu-facturing puzzolan cement; three companies, Birmingham Slag Co., Woodstock Slag Co., and Swann Chemical Co., making slag aggregates and by-products; one company, Tennessee Coal, Iron and Railway Co., a subsidiary of the U. S. Steel Corporation, producing ground open-hearth basic slag for soil conditioning. Two companies, the Sloss Sheffield Steel and Iron Co. and the Woodstock Slag Co., make slag concrete in ready-mix plants and one company, the Superock Company, manufactures fine and coarse slag aggregates under a new granulation process. No Portland cement is made with slag as an ingredient, because dolomite is used so extensively as a blast-furnace flux that the magnesium content of the slag is excessive.

Jan 1, 1937

By Frank Firmstone

THE indicator cards shown herewith were taken by the writer in June, 1877, from the water-pressure blowing engine of the Longdale Iron Co., at Lucy Selina Furnace, Longdale, Virginia. A description of this engine with figures, and some indicator cards, was published by Washington Jones, Esq., Superintendent of the I. P. Morris Co.,* in the Journal of the Franklin Institute for May, 1877, to which those desiring a full account are referred, but for convenience the principal dimensions, etc., are given below. The machine consists of a pair of horizontal directacting blowing engines, connected at right angles to a common fly-wheel shaft. The blowing cylinders are 4 ft. diameter by 5 ft. stroke; the water cylinders were 18 in. diameter by 5 ft. stroke as built. Both water and blowing cylinders are double acting. The water valves are balanced piston valves, 18 in. diameter, moved directly by eccentrics on the fly-wheel- shaft. Great care was taken to have the areas of the ports and passages at least equal to the area of the working piston. The engine is set about 14 ft. above the tail-race, and the * The engine was built by the I. P. Morris Go., from drawings made by Messrs. Tuws and Hartman.

Jan 1, 1879

By N. M. Raju, B. Singh

The paper seeks to present the results of experimentation in room and pillar stopes with different ground conditions to determine the safe working span. In the experimental stopes, ground movement was monitored with gradual widening of the room span. The field measurements included closure between the stope walls and the extent of ground movement in the hangwall using borehole extensometers. hock bolting was used as an exclusive support system which enabled introduction of scrapers for improving productivity. In one nine, phosphate bed, 3 to 3.5 m thick dipping at 45O and overlaid by weak laminated shale, was worked at shallow depth of cover. h the experimental panel, five s topes were worked with spans varying from 5.5 to 7 m. In the second mine, the chalcopyrite orebody up to 6 m in thickness dipping at 25 - 30" was worked at a depth of 1100 m. The hangwall consisted of fairly competent schistose rocks and therefore 10 to 15 m wide spans could be experimented. The field measurements confirmed that in the phosphate mine with weak shale roof, 7 m span could be safely worked with subsequent caving of the bolted roof. In the copper mine, 15 m span could be worked and the stopes required subsequent backfilling for better ground control.

Jan 1, 1983

By F. Guevara

The paper presents results of physical and turbulent three-dimensional numerical simulation of the gas flow in the wind box and reaction shaft of the concentrate burner of a flash furnace. Physical simulation work was carried out in a 1:5 linear scale model, where the velocity field was measured using a Pitot tube. The mathematical model consists of the three-dimensional averaged Navier-Stokes equations, turbulent kinetic energy and dissipation of turbulent kinetic energy using the Renormalization Group (RNG) theory for the k-e turbulence model. Computations were performed using FLUENT, based in a finite- volume code. The geometry of the concentrate burner was separated in two sections: wind box and reaction tower. Results obtained at the exit of the wind box were used as boundary conditions for the reaction shaft. The effect of boundary conditions on the numerical results was also studied. Results of physical and numerical simulations show an asymmetry of the velocity field at the exit of wind box. This asymmetry is possibly due to existence of a separated flow in the back of the exit ring. The agreement of physical and numerical results assess the capacity of the turbulence RNG k-e model to reproduce correctly the behaviour of the velocity field at the exit of the concentrate burner.

Jan 1, 1999

JAMES DOUGLAS Dr. James Douglas, twice President of the American Institute of Mining Engineers, and one of its principal benefactors, died in New York on June 25, 1918, at the age of 81 years. After a life of extraordinary activity, failure of his health compelled him to retire about 2 or 3 years ago, and in view of his advanced years his death was not unexpected. His funeral was held at the Church of the Mediator, on June 26, and was attended by representatives of the American Institute of Mining Engineers and of the Canadian Mining Institute. His body was then taken to Quebec for burial in the family plot. An extended notice of Dr. Douglas, prepared by Dr. R. W. Raymond, will be presented in the September issue of the Bulletin. LEWIS NEWTON BAILEY Lewis Newton Bailey died of pneumonia at Camp Merritt, N. J., April 30, 1918, at. the age of 34 years. He was Master Engineer, .Senior Grade, in the Fourth Regiment, U. S. Engineers; and although he was offered a commission as First Lieutenant shortly after enlisting, he preferred not to accept it until he had reached France. By those who knew him well, this lack of eagerness for promotion will be recognized as consistent with his whole character.

Jan 8, 1918

By Jay C. Hanson

Various electrical and electromagnetic (EM) geophysical techniques are currently being evaluated by the U.S. Bureau of Mines for their effectiveness in the detection and monitoring of electrically conductive (1 to 5 S/m) lixiviant (leach solution) to depths of 600 m, either above or below the water table. These techniques include magnetotellurics (MT) , controlled source audiofrequency magnetotellurics (CSAMT), resistivity and focused resistivity, ground-penetrating radar (GPR), frequency-domain electromagnetics (FEM), and time-domain electromagnetics (TEM). Of these techniques, TEM may be the most effective, but CSAMT and focused resistivity also hold promise. Geophysical computer modeling of the borehole TEM technique was conducted based on an idealized geoelectric section (layered earth) with characteristics based on the Santa Cruz porphyry copper deposit near Cas a Grande, AZ. Layer resistivities and thicknesses were obtained from geophysical data and geologic logs available from the site. Modeling of borehole TEM in both preleach and during leach situations was conducted. Simulating the TEM method using computer modeling proved to be encouraging since there were substantial differences between leached and nonleached responses. The modeling does not prove the effectiveness of TEM in the field, but does indicate that detection of deep lixiviant zones is theoretically possible.

Jan 1, 1992

By Thomas M. Caruso

Construction of a new ship dock at a major Philadelphia area refinery required geotechnical design and field consultation. The new dock, which consists of a system of mooring dolphins and platforms, will be capable of docking the Stena V-MAX Oil Tanker (V-MAX). The 1100 ft long V-MAX is currently the largest tanker to travel the Delaware River and will induce significant lateral loads on the new ship dock. Lateral loads induced on the dock will be resisted by over 200 pipe piles installed on a batter. The piles used for support of the dock included 20 and 30 in. diameter reinforced, concrete filled pipe piles. Complete construction of each pile included driving of the pile to the design ultimate capacity, flushing the pipe pile casing clean of overburden materials followed by drilling rock sockets into the underlying Wissahickon Formation. Variations in depth to bedrock, rock quality and degree of weathering and presence of very hard quartzite lenses created a complex geologic environment that presented challenges for the pile/rock socket design and installation. The design of the pile system, installation methods, QA/QC and testing (Pile Dynamic Analysis), as well as the challenges that were encountered through the duration of the project are presented and discussed.

Jan 1, 2008

By Noel W. Kirshenbaum, George A. Pouska, James M. Link

Literally millions of words have been written on the subject of mineral slurry pipelining. The sheer bulk of literature on the subject should be enough to convince the interested observer that the method is both viable and widely applied. It is the intent of this paper to examine typical mineral slurry applications. This examination should reveal the reasons that the slurry system was selected over other transport modes and it should provide a framework for determining the applicability of the technique to new projects. Slurry transport involves the conveyance of solid particles by suspension in a moving liquid. Almost any combination of solids in liquids may be imagined, and the conduit may be an open channel or a closed pipe. Historically, the most numerous slurry transport applications consisted of mineral particles in water. However, current research investigations are emphasizing other liquid carriers, specifically those which have greater economic value. Among these are gaseous and liquid fuels and chemical feedstocks. Another area being investigated involves the use of the pipeline as a chemical reactor system. The long residence time and turbulent flow characteristics of the pipeline make it particularly attractive for certain chemical reactions. Because these new systems involve a valuable liquid as well as a valuable solid, there is increased attention to solid-liquid

Jan 1, 1980