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By Larry Ng, Keith McDonald

The benefits of controlled blasting techniques have gained increasing recognition by the mining industry in recent years. The utilization of an effective controlled blasting programme can result in a safe work environment with less loose rock and a reduced level of scaling and ground support.

Jan 1, 1994

By A. Boucher, D. Marcotte

"Abstract- The accepted practice for the estimation of thin (2D) vein deposits recommends the use of the grade x thickness service variable (i.e., the accumulation). Grade estimates are obtained indirectly by the estimated accumulation/estimated thickness ratio. This practice stems from the varying support (thickness) problem and the resulting non-additive nature of the grade variable. We compare the actual performance of the direct grade estimation approach used by some practitioners to that of the indirect approach using accumulation. Our simulated and real data indicate that the direct approach is more accurate for point grade estimation where the grade-thickness correlation coefficient is positive (and vice-versa). Moreover, the relative gain of the direct method increases with the (positive) correlation coefficient. This finding contradicts common thinking that the indirect approach should be the preferred method where grade-thickness correlation is strongly positive. Also, for a given positive grade-thickness correlation, the relative gain of the direct method increases with the coefficient of variation of the grade and thickness. Résumé - L’estimation de veines minces (2D) minéralisées est normalement réalisée à l’aide de la variable auxiliaire épaisseur x teneur (i.e., accumulation). Les estimés des teneurs sont alors obtenus indirectement du rapport accumulation estimée/épaisseur estimée. Cette pratique découle du problème du support variable pour la teneur, l’épaisseur de la veine, qui fait que la teneur est alors une variable non-additive. Nous comparons les performances de l’estimation directe de la teneur, utilisée par certains praticiens, à celle de l’approche indirecte. Pour l’estimation ponctuelle des teneurs, nos données simulées et réelles indiquent une meilleure justesse de l’approche directe quand la corrélation teneur-épaisseur est positive (et vice-versa). De plus, le gain relatif de la méthode directe s’accroît avec la valeur de cette corrélation (positive). Ce résultat contredit l’opinion répandue que l’approche indirecte devrait être utilisée en présence de forte corrélation positive de la teneur et de l’épaisseur. Nous montrons également que pour une corrélation positive teneur-épaisseur donnée, le gain de l’approche directe augmente avec les coefficients de variation de l’épaisseur et de la teneur."

Jan 1, 2001

By Earl Bardwell

(Butte Meeting, August, 1913.) THE structural relations existing between cuprous oxide and copper were first systematically studied by Heyn1, who suggested that a study of the microstructure of refined copper might be substituted for the analytical methods in vogue for determining the oxygen content of copper coming .;from the refining furnace. Hofman, Green and Yerxa,2 in their paper A Laboratory Study of the Stages in the Refining of Copper, working along the lines suggested by Heyn, showed that a study off the microstructure could be made to yield a correct estimate of the oxygen content of the specimen of refined copper under examination. In order to determine the oxygen content of the specimen of refined copper under examination a photomicrograph was first made. From the relative areas of copper and eutectic, the percentage of cuprous oxide and the corresponding percentage of oxygen were then readily calculated. It was found that the values for oxygen thus obtained corresponded closely with the analytical results. With the idea of utilizing, this method of determining the oxygen content of each charge dipped from the refining furnaces at the Boston & Montana Reduction Plant, the physical testing laboratory was equipped with suitable apparatus for carrying out the work. It may be of interest to describe certain of the methods which have been worked out in, this connection and give such data as have been obtained bearing on the effect of the oxygen content of refined copper upon its conductivity.

Jan 7, 1913

By Albert Burch

AN analysis of this subject demands a study of the theory and practice of the present system, conclusions as to its merits, and recommendations for remedying its defects if any be found. Theory of the Present Law The theory of the present law with reference to lode locations contemplates the existence upon the surface of mineral-bearing veins which have clearly marked boundaries, and which can be so readily traced that a locator may immediately mark the boundaries of his 600 by 1,500 ft. claim in such a way that the vein will pass through both of its end-lines. It also supposes that, having discovered such a mineral-bearing vein, the locator will at once post a notice upon such discovery, mark the boundaries of his location in such a manner that they can be readily traced, and from that time forward have absolute title to the ground embraced within such boundaries, as against every person except the United States. For initiating title to placer ground, the law presupposes the discovery of a valuable mineral deposit; but not necessarily in place, as in the case of lode claims; and the location must be made to conform "as nearly as may be" to the legal subdivisions of the United States public land survey. When the placer law was extended to include the acquisition of title to oil lands, no exception was made as to the necessity for the discovery of valuable mineral in advance of location!

Jan 6, 1914

By John S. Rinehart, Norman Ahlquist

The model which Birkimer has developed to explain the increase in fracture strength of brittle, rock-like materials with increasing rate of loading may have some applicability. It should be noted that since his analysis presupposes elastic behavior he could equally well express his result as an increase of stress to fracture with increasing strain rate, a fact which is well known. Certainly his experimental results do not contradict his strain rate to the one third power law. On the other hand, we do feel that the data are insufficient and inadequate to establish the relation- ship definitely. 'In metals, the whole fracture picture is greatly complicated by concomitant plastic flow and, in rocks, by the presence of macroscopic flaws and inhomogeneties. Both lead to uncertainties as to the state of stress during the fracture process. He quotes in support of his theory Rinehartfs results on rock in which the latter found that under impulsive loading by explosives, rocks appear to be many times stronger than under static loading. We suspect that the observed increase has little specific relevance to the theory which Birkimer puts forward. Rinehart's measurements were made by spalling rocks using a sawtooth shaped stress wave of known intensity and duration. The rise time of such a pulse is essentially zero, certainly less than 0.1 microseconds, so that it is not possible to apply Birkimerfs theory quantitatively. We favor attributing the increase in fracture strength to two factors. First, the action takes place very quickly in an exceedingly thin region so that statistically the probability is small of encountering one or more of the large flaws that contribute so significantly to the reduction of strength of most rocks under tension. It is also conceivable that the compressive wave that has just passed by the region of fracture has strengthened the rock by collapsing some of the larger flaws. Second, the state of stress obtaining at the time of fracture is not all that existing when the

Jan 1, 1971

By Y. Tao

The features of the teeter bed separator and its application in the coarse slime separation of Chengjiao coal preparation plant were discussed. The relationship between the coarse slime separation efficiency by TBS and the particle size were studied, and the influence of using TBS on dense medium consumption and oil consumption were investigated, it increased the clean coal yield and the comprehensive recovery of the whole plant, and brought huge economic benefits to Chengjiao coal preparation plant.

Jan 1, 2011

By David Ellis

The next generation of Reusable Launch Vehicle (RLV) will utilize regeneratively cooled combustion chamber liners in the engines. The current design calls for using a new Cu-8 at. % Cr-4 at. % Nb (Cu-8 Cr-4 Nb) alloy for the liners. Work is ongoing to characterize the thermophysical and mechanical properties of the alloy from - 253 to 800°C, the temperature range to which the alloy will be subjected during service. The alloy has been commercially produced in quantity for NASA. The powder size has been characterized and the microstructure examined. The powder was extruded into bar using a commercial extrusion press. In addition, samples have been hot isostatically pressed (HIPed) at NASA Glenn Research Center. Both processing methods produced fully consolidated material. Transmission electron microscopy (TEM) revealed highly faulted Cr2Nb and some elemental precipitates. Cryogenic tensile testing showed the extruded specimens had significantly higher strengths than NARloy-Z (Cu-3 wt % Ag-0.5 wt % Zr) even after being subjected to a simulated braze cycle. The Young's moduli (Cu-8 Cr-4 Nb) were lower than NARloy-Z. The lower moduli is highly beneficial for reducing thermally induced stresses in rocket engine combustion chamber liners and similar applications.

Jan 1, 1999

By Brian Stump, Chris Hayward

Blasting operations at one copper mine are studied in detail to examine the relation between blast design parameters and near-shot, in-mine, and regional seismic and acoustic observations. Five observational experiments, namely collection of blast design data, near source recordings, GPS synchronized video, near mine recordings and distant regional observations were performed during one week in August. A variety of seismic and infrasound instruments were installed near the shot, on the perimeter of the open pit mine, and at several locations up to 500 km distant. Time tagged video recordings were taken of several shots. Three shots were used in the preliminary analysis, a 350,000 lb pattern with long delays, a 60,000 lb pattern with short delays, and a 256,000 lb pattern with short delays. Maximum peak-to-peak amplitudes of the seismic signals in the mine are not a simple function of the total size of the shot, but are related to the pattern timing. Peak pressures have a less clear relation to peak pressure but match the relative amplitudes of spectra modeled from the pattern design. The predicted spectrum based upon a simple impulse model fits the observed spectrum for ground acceleration measured near the pattern and explains why in this case a pattern of 60,000 lb results in the same seismic disturbance as the 350,000 lb pattern.

Jan 1, 2002

By G. B. Richardson

WHILE examining a number of curves showing the production of petroleum, the author was impressed by the rather uniform relationship between the cumulative production from the beginning of development FIG. I.-ACTUAL' AND COMPUTED PRODUCTION OF PETROLEUM IN WEST VIRGINIA. down to the time the peak was attained and the estimated total production. The curves examined showed an average ratio of cumulative peak production1 to total production of approximately 30 per cent. FIG. 2.-ACTUAL AND COMPUTED PRODUCTION OF PETROLEUM IN CAT CREEK FIELD, MONTANA. These relations were discussed with C. E. Van Orstrand, geophysicist of the Geological Survey, who investigated the subject mathematically.

Jan 3, 1925

By P Cotton, N Cox

The Brisbane City Council has implemented a program of continual improvement at its Mount Coot-tha Quarry in the heart of Brisbane, Australia. The program has been underway for the past 6 years, and has resulted in very significant improvements in terms of both the cost effectiveness of its operation, and in terms of its environmental impact on nearby residents. The work has included a focus, amongst other things, on blasting efficiency, and has challenged conventional thinking in terms of the size of blasts fired, the frequency of firing, the diameter of blastholes, and the use of bulk emulsion or slurry explosives.

Jan 1, 1995

By L. G. Austin, R. C. Klimpel

Batch breakage kinetic tests were performed in a mill of 0.3 m diameter for a range of mill conditions. Accurate simulation required the measurement and use of factors which accelerated the specific rates of breakage of the top sizes as finer material accumulated in the slurry. These factors depended on the size distribution expressed relative to the top size, not the absolute size, suggesting that they are due to a packing effect not a rheological effect. The data simulated correctly a series of steady-state continuous tests in a mill of the same diameter providing values were corrected to the hold-up, ball load, slurry density, and size distribution measured in the continuous mill tests.

Jan 1, 1990

By James F. ` King

This paper reviews the changes which have taken place in the supply of smelter-grade alumina and refinery-grade bauxite over the past twenty years. It highlights the current situation and identifies some trends which are to be expected in the medium- and longer-term future.

Jan 1, 1986

By W. A. Hockings, G. W. Lower, K. A. Smith

The kinetics of dissolution of metallic copper in aqueous cupric ammonium carbonate solutions were investigated. The major variables studied were temperature, agitation, and the cupric, cuprous, ammonia and carbonate concentrations. The rates of copper dissolution from rotating discs were determined by measuring the weight loss. The dissolution rate increased with the square root of the disc rpm and doubled when the temperature was increased from 20°c to 40°C.

Jan 1, 1973

By M. King Hubbert

DURING the past summer the writer was asked by the Illinois State Geological Survey to make a study of some of its economic geological problems with regard to the applicability of geophysical methods of prospecting to their solution. The following four problems were sug-gested for investigation: (1) the fluorspar area of Southern Illinois, (2) oil structures in the south central part of the state, (3) the lead and zinc-bearing area of northwestern Illinois, and (4) the water supply and gravel deposits of the glacial drift. The prime requirements were to find a means of obtaining a maximum of useful information with a fairly modest outlay of expenditure for technical staff and equipment. The method of procedure adopted was that of making a preliminary study of each of the problems named by means of available office data and published reports with supplementary field reconnaissance where necessary.

Jan 1, 1932

By J. M. Sands

THE state of Kansas had a daily average crude-oil production of about 87,000 bbl. at the beginning of the year. This showed a steady but consistent decline during the 12 months, so that the daily average production at the end of the year was slightly over 68,000 barrels. GREENWOOD COUNTY THE most active development in Kansas during the year was in Greenwood County, in a line from near Sallyards in T 25-R 9 to east of Madison in T 22-R 11. The main part of this development has been in a succession of pools beginning at the south with the Polhamus pool in 34-24-9 and 3 and 4-25-9; Thrall pool in 28, 29, 32 and 33-23-10; Burkett pool in 13, 23, 24 and 26-23-10; Seeley and Wick pool in 22, 27, 28,. 32 and 33-22-11 and 5, 6, 7, and 8-23-11; Frohm pool in 11, 14 and 15-22-11; Madison pool in 31 and 32-21-12 and 6, 22, 12 and 1-22-11. Some of these pools have two or more sands, locally called Bartlesville and Burgess Sands. They range in depth from 1850 ft. near Madison to 2450 ft. near Sallyards, the general dip being to' the west. The thickness of these sands run from 20 to 100 ft., the initial production of the wells being 50 to 1000 bbl of 40-gravity oil or better.

Jan 3, 1924

By J Cook, S Pike, D Pridmore

"An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation. The application of high-resolution seismic reflection to map structure and/or mineralisation in hard rock environments has progressed significantly in the last decade. Improvements in equipment, field practice, processing and understanding has seen the seismic reflection technique emerge as a cost-effective tool for high-resolution three-dimensional structural and lithology mapping to depths far greater and with superior accuracy than other more conventional geophysical techniques.This paper outlines results and preliminary interpretation of 2D and 3D seismic reflection surveys aimed at defining fault zones and locations for quartz load development in favourable host lithologies at the Cracow low-sulfidation epithermal gold system in Queensland, Australia.As this is possibly the first time that high-resolution seismic reflection data has been used to define the structurally-controlled location of low-sulfidation epithermal gold mineralisation, an important aspect of this work was the derisking or due diligence steps taken prior to commissioning the full 3D surveys at each site. This included full wave sonic logging, vertical seismic profiling and trial 2D lines. Interpretation of the 2D profiles and the drilling of interpreted structure provided the confidence to proceed with the full 3D survey.The advantage of collecting 3D data extends beyond ensuring that the received reflections are located correctly in 3D space. The final 3D data cube can potentially map the entire fault network, thus highlighting flexures and changes in orientation of the structures both vertically and along strike, which is an important aspect in the deposition of gold and for direct targeting.CITATION:Smith, R, Cook, J, Pike, S and Pridmore, D, 2015. Application of high-resolution seismic reflection surveys to exploration for blind vein systems at the Cracow low-sulfidation epithermal field, in Proceedings PACRIM 2015 Congress, pp 77–84 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Mar 18, 2015

The process of resource estimation of large precious metal deposits is illustrated by reference to major deposits now being mined or developed by Placer.The estimation procedure commences with building an appropriate model of the mineralization and proceeds through steps of data validation and geostatistical studies. It is important that the geologists most familiar with a deposit be involved with all stages of the estimate, and also prepare a manual estimate used to validate the kriged resource.Resource estimates are major exercises taking many man-months of work. The most time consuming part of this is usually construction of an appropriate three dimensional geological model. The data base for the resource calculations must be complete and checked for accuracy. The most appropriate estimation method must be selected.

Jan 1, 1990

By E. W. Dewing

ROLIN1 in 1961 published a phase diagram for the CaF2-Na3AIF6 system in which substantial (-20 wt pct) solid solubility of CaF2 in Na3A1F6 at the eutectic temperature (945°C) was indicated. The evidence was that the halt in cooling curves associated with the eutectic was lowered progressively on the Na3AlF6 side. H olm2 has recently confirmed the experimental fact, but attributes it to evaporation losses shifting the composition into the ternary NaF-CaF2-Na3A1F6 system with a consequent lowering of the eutectic temperature

Jan 1, 1970

By Norman Brown, Victor V. Damiano

ThE present paper proposes a mechanism of dislocation multiplication at internal inclusions or cavities and presents experimental evidence of such sources in zinc. Using an etching technique recently described by Damiano, Tint, and Herman1 to study the three-dimensional aspects of dislocations in bulk zinc crystals, an investigation was made of helically shaped and closed-loop etch patterns found to be associated with inclusions. Crystals containing 0.1 pet Cd and grown from the melt were deformed slightly by bending and then aged at room temperature to precipitate cadmium at the dislocations. The crystals were cleaved along the (0001) plane and then etched with Gilman's2 etch. Crystals were continuously viewed on the (0001) plane while the etching was in progress and numerous helical and closed-loops etch patterns were continuously recorded as shown in the sequences printed directly from the cine film in Fig. l(a) and (6). These etch patterns are not to be confused with the etch patterns previously reported by Damiano and Herman3 which revealed dissolution spirals on the (0001) plane of high-purity zinc crystals. In the present case, precipitates arranged in the form of closed loops or helicies are progressively uncovered by etching after suitable aging of cadmium doped zinc crystals. Viewed with dark-field illumination as shown in Fig. 2, portions of a helical figure and subboundaries were revealed simultaneously. Continuous viewing while the etching was in progress revealed in Fig. 1(b) that the short line segments observed on single photomicrographs were in fact continuous and described a helix which had its terminus at an inclusion. The observations suggested that a dislocation once nucleated at the interface between the inclusion and matrix may act in such a way as to produce ad-

Jan 1, 1964

By James Veri, Andrew H. Stern, Gerald N. Torbert

When mining coal, the occurrence of high methane liberation rates can often overwhelm the existing ventilation capabilities of the working place and result in elevated levels of methane gas. These “gas-off/stand-by condition" events often limit the production of the section and increase the potential opportunity for the occurrence of an ignition. This paper investigates the potential effectiveness of using a continuous miner equipped with an integral dust scrubber which was modified to provide high flow rates to reduce these events during active coal mining. Work was undertaken to quantify various adaptations of the mining system, by simulating site parameters in the controlled environment of an instrumented "full-scale" test facility. Monitoring (in real-time) of velocities and gas concentrations at many fixed points was also undertaken in an attempt to learn the effective limits of the system at high release volumes of gas.

Jan 1, 1997