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By Dan Preston, Shane Yanagisawa, Robert Marshall, Don Deere

Geotechnical Baseline Reports often estimate the number of cobbles that will be encountered in terms of volume or weight. These estimates are practically impossible to verify in the field. ClaroVia Holdings in conjunction with Frontier Kemper Constructors Inc. developed Digital Geologist 2.0 to classify and count cobbles discharged from an EPB TBM at the RSC7 project in Burbank, CA. The system worked by using two stereoscopic laser sensors with a global shutter to scan and count cobbles at 12 frames per second. Results of the effort are revealed along with lessons learned and paths for improvement.

Jun 13, 2023

By Walter E. Vanderpool

Three drilled foundations for an elevated water-tank were instrumented, tested and monitored during construction and the first two years in service. One shaft was load tested by the Osterberg method. A void was detected in one shaft by cross-hole sonic logging, pulse-echo logging and concrete coring. The void was instrumented, hydrostatically tested and pressure grouted. The shaft was ?abandoned? and replaced by two smaller shafts with a straddle beam cap. One of the replacement shafts and the cap were instrumented. The strain that appeared in the abandoned shaft, the replacement shaft and the cap were monitored during the remainder of the construction, through the commissioning test and the first two years of service. The results demonstrate the precision and sensitivity of the vibrating wire strain gage.

Jan 1, 2004

By Alfred Bodenlos

El presente artículo describe la historia geológica pre-cretácica de la Cordillera Negra. En algunos intervalos predominaron los pantanos que dieron lugar a la formación de carbones. Luego, en el Valanginiano superior, la región estuvo sumergida, depositándose calizas delgadas. Los tufos que yacen sobre la secuencia de elásticos indican que hubo actividad volcánica a fines de este intervalo. Parte apreciable de los depósitos marinos del Cretácico medio está formado por calizas bituminosas obscuras.

Jul 1, 1957

By Ryan C. Linthicum

A system of steel sheeting and multiple levels of high capacity double corrosion protected soil anchors were used to restrain a major slope failure that occurred at the base of the Watchung Mountains mid-way through construction of a 650,000 SF retail center along Route 22 in Watchung, New Jersey. The implementation of a design-build earth retaining structure was necessary to stabilize and repair the disturbed mountainside in a timely fashion to permit completion of the retail center on a fast track schedule. The tied back steel sheetpile wall was approximately 2,000 feet long and varied in height from 12 to 25 feet. The hillside extended approximately 350 feet above and 600 feet beyond the wall with the main failure scarp extending 50 feet above and 90 feet beyond. The wall was constructed in a top-down manner and required the installation of 475 anchors to resist loads of up to 70 kips/ft produced by the creeping hillside and groundwater flows from both a series of springs and steady state seepage through an inclined zone of fine sand. Incorporation of a unique tie point connection eliminated the need for a waler, facilitating and simplifying modifications to anchor locations based on anchor load test results and conditions encountered during construction. Post grouting also proved to be an essential element in the successful construction. This paper presents the design and the construction methods used to restrain the significant earth lateral loads produced by a slope failure using steel sheeting tied back with high capacity soil anchors with anchor loads distributed to the sheeting through a unique tie point connection on a fast track schedule. Installation techniques, testing programs, and construction quality control are also discussed.

Jan 1, 2003

During the extensive research which has been conducted in the Metallurgy Department of the University of Melbourne, into the properties of lead and its dilute alloys, the Brinell test has been used for the determination of hardness.The work described herein represents part of an investigation into the influence of various factors on such determinations, particularly when carried out on different qualities of "pure" lead. It is intended to publish the more theoretical and controversial aspects of this research elsewhere.MATERIALS USED AND THEIR PREPARATION FOR TESTINGThe tests to be reported have been conducted on a specially pure electrolytic lead, and several brands of commercially "pure" lead. The analyses of the samples upon which most of the work has been carried out are given in Table 1.Note: Oxygen was not determined, but from the work of H. W. Worner, in the Rosenhain Memorial Laboratory, it appears probable that it was approximately 0-0003% in all samples.

Jan 1, 1940

By John W. Fredland

Many accidents occur in the mining industry as a result of the instability of material during handling and processing operations. Accidents due to dump point instability at stockpiles, and at spoil or waste piles, for example, occur with alarming frequency. Miners must be trained to be better aware of these hazards. Information on safe working procedures at stockpiles and surge piles is provided. Mine operators must review their training and operating procedures regularly to ensure that hazardous conditions are avoided.

Jan 1, 1993

By R. H. Pemberton

"THE Mattagami district of Quebec has, during the past few years, experienced intense exploration by virtually every mining company operating in Canada. As a result of this activity, a number of well-mineralized zinc-copper bearing bodies have been found, some of which will almost certainly go into production. Much of the area has undergone what is now termed ""Saturation Prospecting"" or intense and detailed geological and geophysical surveying, followed by the drilling of nearly all possible bets. Considering only the airborne geophysical surveying, some blocks of ground have been flown by virtually every geophysical instrument which has to date been installed in an aircraft. A list of these different geophysical instruments would include: l. Fluxgate-type total field magnetometers 2. Vertical field magnetometer ,3. Nuclear-precession magnetometers 4. Single-frequency out-of-phase electromagnetometers 5. Dual-frequency out-of-phase electromagnetometers 6. Horizontal component measuring electromagnetometers 7. In-phase and out-of-phase electromagnetometers8. Dip-angle measuring electromagnetometers."

Jan 1, 1961

By Primak. George J.

"In the development of a new product as well as during its introduction on the market, it is very important to give due consideration to problems involving patents, licenses and trade marks. At the very beginning of the research and development program, it is obviously essential to ascertain, through a suitable patent search, that the product in question will not infringe any patents which are still in force. Then, a possibility of achieving one's own patent or proprietary position on the product or the process of its manufacture should be carefully explored. Licensing arrangements that one may reach with respect to patents and know-how covering such new product may, in the final analysis, determine its over-all success or failure. If one can count on licensing revenues or some favourable cross-licensing arrangements with respect to a newly developed product, this may go a long way to achieving profitability and success. The selection of a good trade mark is probably one of the most important acts that one has to perform once the product is developed, as customers will identify the new product by such a trade mark. In many instances, successful marketing and widespread acceptance of a product are largely due to its appealing name or trade mark, accompanied by proper promotion and advertising. Once the trade mark has been adopted, it should be registered in the Trade Marks Office to provide the protection afforded by federal statute. If the product is to be manufactured, sold or licensed in some other countries, similar considerations should be made with regard to each such country."

Jan 1, 1973

By L Semenyna, W Douglas

Gold is often present in solid solution with pyrite in the Carlin Trend. The presence of organic carbon along with gold hosted in sulfide, referred to as double refractory ore, requires that ore with high carbon-in-leach (CIL) preg-robbing potential and poor leach recovery is routed to a roaster. During roasting, the pyrite is oxidised to (ideally) form hematite (Fe2O3), and the gold that was present as solid solution in the pyrite forms colloids within the hematite. The ideal texture of the produced hematite is porous to allow for the penetration of cyanide for gold dissolution. Temperature and other conditions of roasting, as well as ore characteristics (pyrite mineral associations, arsenic) can affect the texture and the type of iron oxide formed. Many of these alternate iron oxide minerals result in incomplete leaching. Comprehensive gold deportment studies have proven that the majority of the gold losses in Barrick GoldstrikeÆs roaster leach tailings occur within the iron oxides created through the roasting process.The iron oxide phase that hosts the majority of the gold in tailings is in the form of by-product maghemite (?Fe2O3), which is highly magnetic. Barrick Goldstrike has designed a magnetic recovery circuit to capture these iron oxides, and with subsequent reprocessing, recover the lost gold. Pilot plant results and analysis using scanning electron microscope mineral liberation analyser (SEM MLA) shows that up to 30 per cent of the gold in tailings can be recovered with a three per cent overall mass pull to magnetic concentrate. This magnetic concentrate can be economically reprocessed, resulting in a three per cent improvement in roaster recovery.CITATION:Douglas, W and Semenyna, L, 2013. Magnetic recovery of gold-bearing iron oxides at Barrick GoldstrikeÆs roaster, in Proceedings World Gold 2013 , pp 79-86 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 26, 2013

By Kefton H. Teague

This paper deals with the practical application of the Dutch State Mines cyclone separator for fine-coal cleaning. The more important operating variables are discussed, and results of a number of continuous-scale tests on various fine coals with a 6-in. cyclone separator are given. Descriptions of the Cyanamid Pilot Plant and the 50 tph Cyclone Separator Plant at the Emma Washery in Holland are included.

Jan 1, 1950

By LUDWIG VOGELSTEIN

WE are indebted to Mr. Barbour for his valuable contribution to the literature on copper statistics; it is to my knowledge the only intelligent attempt to throw light on a much misunderstood subject. If I should appear to criticize some of his findings and arguments, I do not want to leave the impression that I do not appreciate the article; I think Mr. Barbour has been painstaking, and even where one might not agree with his conclusions, he has opened our eyes and stimulated us in our search for the truth.' It might be well to define the term "secondary copper" and to make a few remarks about the origin and the reasons for the variation of the supply. Mr. Barbour has touched on these points, but not sufficiently to make them clear to those not in the business.

Jan 1, 1931

By J. R. Alldredge

This Bureau of Mines report presents a computer code that has been developed for describing and testing the statistical distribution of general continuous data sets. The statistical distributions used include the normal, lognormal, exponential, chi square, gamma, and uniform. Histograms for observed and expected values are plotted for each distribution. An example using geologic data obtained from a study of the geometric properties of natural fractures in oil shale rock illustrates the use of the computer program, GDIST.

Jan 1, 1977

By R. J. Charles

F. C. Bond: This is an outstanding paper on comminution theory and represents a considerable advance in mathematical formulation. It clears the way for a discussion that should ultimately decide whether the work index should be considered as a parameter according to the Third Theory or as a constant. In the empirical differential equation dE = —Cdx/x [1] either Corn must be treated as a variable to satisfy known crushing and grinding conditions. The author has chosen the exponent n as the variable, with C as a constant. According to the Third Theory, in the general case n is a constant equal to 3/2, and C is a variable related to the work index Wi. If x is placed equal to P (the size in microns which 80 pct of the product passes) and F is the size 80 pct of the feed passes, then C equals 5 W1, and dE = 5 -5 Widx/x = 10 Wi 10 Wi w = vP vF which is the basic equation of the Third Theory. It is apparent that this integration involves the error of treating the parameter Wi as a constant, just as the author's treatment involves the error of integrating his variable n as a constant. These errors are probably relatively unimportant, considering the small range of the variables. When more is known about the factors contained in the work index, Eq. 1 can be revised as a partial differential equation. The Third Theory exponent of 1/2, or n = 3/2 in the Charles' differential equation (Eq. l), was not chosen primarily because it is the average between the Kick and Rittinger exponents; this may be merely fortuitous, since it is illogical to define truth as the average between two errors. It was first discovered from the study of a large mass of crushing and grinding data and confirmed by laboratory testing. The general correspondence of the Third Theory equation to actual crushing and grinding results over the entire size reduction range argues strongly that a fundamental phenomenon is involved. The a posteriori theoretical explanation of the constant Third Theory exponent is that the work done in breaking rock is proportional to the length of the crack tips formed. Compressive force applied to the rock results in deformation and strain energy. When this locally exceeds the breaking strength a crack tip forms, the surrounding strain energy flows to the crack tip and extends it to split the rock, with release of the energy as heat. Under rapid impact the crack tip may form before the strain has reached equilibrium, resulting in less energy expenditure and probably a coarser product. In any case, the elastic limit of a brittle material is practically the same as its breaking strength, and the work necessary to form the crack tip is the work required to break. The crack length of a ton of broken rock cannot be measured directly. However, the particle shapes of feed and product are similar, and the crack length is considered equal to the square root of one half of the new surface area formed. It is, therefore, proportional to 1/vD, where D is the equivalent product particle diameter. This is the basis of the Third Theory equation. Many secondary factors can be imposed upon the crack length breakage. These may cause the Third Theory work index to increase or decrease somewhat as the product size becomes finer. The work index is properly a parameter rather than a constant, making it an increasingly valuable practical criterion of the work input required in crushing and grinding.

Jan 1, 1959

By J. N. Van der Merwe

The paper provides an overview of subsidence research which was done by the Sasol Company in South Africa over a period of more than six years. The magnitudes of subsidence elements in South Africa are largely similar to those in the U.S.A. and Australia, as opposed to Europe. The research resulted in a subsidence prediction method with a new approach to the prediction of ground strain. The paper also describes the effects of subsidence on various commonly occurring surface structures such as roads, overland conveyor belts, pipe lines and power pylons. It is concluded that while most structures are not specifically designed to accommodate mining induced displacements, they can nontheless be undermined safely and economically with only minor precautions.

Jan 1, 1986

By R K. W Merkle, S Madoom Hussain, T Yellappa

Cr-Ni-Cu¦PGE deposits are known to occur in early Archaean mafic-ultramafic rocks. Early Archaean mafic-ultramafic (MUMF) rocks occur in the western Dharwar craton and range in size from small pods to schist belts. These MUMF pods consist mainly of meta-peridotites, tremolite-actinolite schists, serpentinites, amphibolites and metabasalts. Spinifex, nodular and ocelli textures are also present. The rocks have been subjected to greenschist and amphibolite facies metamorphism. Geochemical studies were undertaken to evaluate the possible occurrence of economically important elements in the mafic-ultramafic enclaves around the major Arsikere-Tavarkere lineament and surrounding gneissic terrain adjoining local shear zones that occur as discontinuous pods between Arsikere and Chennagiri. Talc-serpentine and tremolite- actinolite schists contain chromite which is rimmed by ferrit-chromite. A notable feature of these MUMF rocks is that they exhibit high MgO (22 - 40 per cent), total iron (8.34 - 10.01 per cent), Ni and Cr (~3000, 2800 ppm) contents, with some samples showing komatiitic affinity. The rare earth elements (REE) data show slightly fractionated patterns with enriched LREE (LREE/HREE ~5.0) and negative europium anomalies. The Pt and Pd values reach 6500 and 191 ppb. The MUMF rocks, especially those exhibiting high chromium contents and occurring near shear zones, are potential hosts for economic platinum group element (PGE) deposits.

Jan 1, 2008

By E. G. King

The Bureau of Mines made experimental determinations of the heats of formation of forsterite and chrysotile at 298.15° K. The heat capacities of two polymorphs of serpentine, chrysotile and antigorite, were measured over the temperature range from 50° to 298° K and the entropies at 298.15° K were evaluated. The heat content of antigorite above 298.15° K was measured to 850° K. These thermochemical data were combined with other pertinent data to give heat and free energy of formation values at high temperatures. Free energy values are given for the reaction, forsterite + water = brucite + serpentine at different temperatures and pressures.

Jan 1, 1967

By Taghi Sherizadeh, Kutay E. Karadeniz, Dogukan Guner, Samuel Nowak

Seals and build-in-place (BIP) refuge alternatives (RAs) are two main underground structures to isolate an area from the active working zones with different purposes. While seals are used to prevent methane gas that seeps from coal seams and blast pressures from a possible detonation of the contained gas, RAs are used to provide a safe haven for miners who are unable to escape their working locations after an accident like an explosion or fire. The recommended BIP RA designs can be similar to seals constructed with steel-reinforced concrete. Both seal and BIP RA are constructed in different locations of the mines for a period of time, exposed to a certain convergence due to stress redistribution which can change their responses during an explosion. In this study, a steel-reinforced concrete wall to be used in such applications is simulated to examine the structural performance during an explosion for a coal mine model with different strata conditions using dynamic analysis by a 3D distinct element method (DEM) code. The main purpose of this study is to reveal any possible effects or trends on the wall deformation with changes in strata conditions by implementing different combinations of roof, seam, and floor material properties. The model is calibrated by the experiment conducted on a steel-reinforced concrete wall by the NIOSH researchers in the Lake Lynn Experimental Mine. The results show that strong adjacent rock and coal units are the least favorable condition for the survival of the wall subjected to a simulated explosion pressure. The results indicate that changes in the roof and seam conditions can have dramatic effects on the deformation characteristics of the wall when compared to the floor conditions. The results of this study might be enlightening for future BIP RA and seal applications.

Feb 8, 2023

By J L. Mauk

The Martha epithermal Au-Ag deposit contains multiple generations of quartz veins with a range of textures. We examined: +        vein textures, +        crosscutting vein relationships, and +        the paragenetic sequence within the pit walls as well as a wide range of hand specimens. Samples include host rock, breccia, and veins, but these groups are not distinct; instead, they form a continuum.   Veins at Martha mine show a wide range of textures on a local scale; these textures also change significantly over both the lateral and vertical extent of the pit. Common textures include crustiform bands, comb quartz, colloform bands, platy quartz, massive quartz, drusy quartz, sedimentary textures and brecciation.   Vein grades relate to textures. Many textures, including crustiform, platy, cherty, and sedimentary textures display predominantly low grades, but some textures are linked with high grades, such as ginguro, massive and comb quartz where they are associated with visible base metal sulphides and/or electrum. Host rocks and most breccias are low grade, as most samples contain <2 ppm Au.

Jan 1, 2006

By K. M. Tompson, R. L. Armstrong, C. I. Godwin

"Tungsten skarn deposits on the Clea property in the Selwyn Mountains, Y. T., are related genetically to a quartz monzonite stock, about 500 metres in diameter at the surface. Lower Paleozoic sedimentary rocks are metamorphosed for a distance of 3 km from the stock. Tungsten-bearing skarn mineralization within the altered sedimentary rocks is of two types: sulphide-rich pods and calc-silicate beds. The most significant scheelite concentration is in calc-silicate beds near or adjacent to the quartz monzonite stock. Discordant K-Ar and Rb-Sr isotopic dates indicate that the stock is probably of early Late Cretaceous age, 94 Ma or slightly older, and that it cooled slowly. High initial 87Srl86Sr ratios and disequilibrium relationships between K-jeldspar phenocrysts and groundmass minerals in the porphyritic phase of the granitic rock , and between different granitic rock specimens, indicate contamination of crystallizing magma by old sialic continental crust which extends westward under the Selwyn Basin.This study is significant to regional tungsten exploration. Granitic rocks associated with tungsten deposits, in this part of the Canadian Cordillera at least, appear to have specific isotope characteristics that indicate they were generated at a specific time and in a particular way.IntroductionThe Clea tungsten skarn property (Fig. I) is owned by Canex Placer Limited, and lies in the Selwyn Mountains (Bostock, 1948) near the eastern margin of the Selwyn Basin (Wheeler and Gabrielse, 1972), Yukon Territory. The property covers a 20-square-mile area centered near latitude 62°47 ' north and longitude 129°52' west, and is accessible by helicopter. An airstrip and the terminus of a summer-use gravel road at MacMillan Pass, Yukon, are about 20 miles to the northnorthwest.This paper deals mainly with the geochronemetry of granitic rocks from a stock associated with tungsten mineralization on the Clea property. We show that these rocks have specific characteristics that not only define the genesis of this stock, but also have significance for regional tungsten exploration around plutons in the Canadian Cordillera."

Jan 1, 1980

By H. E. James

Much has been said and written about the need to reduce South Africa's dependence on gold. To compensate for the decline in the country's foreign-exchange earnings resulting from the phasing out of gold, which must inevitably occur at some future date, a far higher priority will have to be placed on the mining, beneficiation, and export of the 59 other mineral commodities produced in South Africa. The basic strategy of the mining and metallurgical industries should be to move from the traditional approach of establishing a resource base to the establishment of a market base; to turn from production orientation to market orientation; and to rely less on exploration and economies of scale and more on process innovation and product development. The enthusiasm, entrepreneurial spirit, and commitment of the leaders in the mining and metallurgical industry will clearly be of decisive importance in the establishment of new industries for the beneficiation and export of added-value mineral-based products. The State can make a significant contribution by the provision of a welldeveloped and efficient infrastructure, including rail and harbour facilities, communications and health services, roads, and of electricity and water supplies. In our search for a new development strategy for the beneficiation and export of South Africa's minerals, we need to recognize that no one nation has all the mineralresources that it needs. Commercial and strategic manipulation of mineral supplies should no longer be tolerated. The future of the human species lies in international cooperation and in a greater understanding of the limitations of the world we live in.

Jan 1, 1985