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By Charles F. Johnson

A pulse technique is described for the measurement of bar velocity. A low frequency sine wave pulse is used which allows the wave-length to become much larger than the lateral dimensions of the test specimen. The low frequency pulse method has been tested and compared with the resonant frequency method and the results show that both methods give, on the average, equivalent velocities.

Jan 1, 1971

By Anylmore M, Walker A, Fletcher A

Roasting of sulphide and sulph-arsenide gold ores produces unwanted emission of sulphur and arsenic oxides, and a less than complete recovery of gold. Pyrite loses sulphur and arsenopyrite loses arsenic at a useful rate at temperatures of 600¦C and above in an inert atmosphere. Sulphur and arsenic driven off can be condensed before entering the atmosphere. During the process, solid-solution gold redistributes itself on internal surfaces of the resulting iron sulphide. Two subsequent processing options may be used; direct cyanidation of the porous sulphide resulting from the anoxic pyrolysis, or a second-stage roast to oxidise the remaining iron sulphide. The first option may be viable under certain conditions of pyrolysis. The two-stage option has an environmental advantage over the traditional roast because it reduces oxide vapour emissions by 50 per cent. The second stage may provide nearly enough energy to sustain the entire process.

Jan 1, 1992

By David W. Pasho

The success of a collector vehicle, designed to recover manganese nodules under the conditions which exist in deep ocean mine sites will in part be determined by the effectiveness of pick-up and running gear mechanisms. For the purpose of qualitative comparison, some specific aspects of seafloor interactions with various concepts are reviewed utilizing existing data on seafloor characteristics and running gear/tool interaction with soils.

Jan 1, 1976

By Isiah M. Warner, Philip Oldham, John Kennedy, Bennett D. Lass

A new method for determination of residual flotation oils on beneficiated kaolin clays has been developed The method, which yields qualitative information, is based on fluorescence measurements employing a spatially resolved, polychromatic illumination source for excitation, and a two-dimensional detection scheme using a silicon-intensified, video imaging device The method was used to identify residual oils on a beneficiated, Washington County, Georgia, crude clay The results were compared to a similar qualitative analysis performed via capillary column gas chromatography using a flame ionization detector The video fluorometry was the preferred method of analysis

Jan 1, 1983

By Bennett D. Lass

A new method for determination of residual flotation oils on beneficiated kaolin clays has been developed. The method, which yields qualitative information, is based on fluorescence measurements employing a spatially resolved, polychromatic illumination source for excitation, and a two-dimensional detection scheme using a silicon-intensified, video imaging device. The method was used to identify residual oils on a beneficiated, Washington County, Georgia, crude clay. The results were compared to a similar qualitative analysis performed via capillary column gas chromatography using an FID detector. The video fluorometry was the preferred method of, analysis.

Jan 1, 1983

By S. Kahraman

P-wave velocity measurements were carried out on 22 large limestone blocks in a stone processing plant. In the laboratory, P-wave velocity of core samples was measured to obtain intact rock velocity. The square root of the ratio of the velocity of the large stone block to the velocity of the core specimen was called the velocity ratio index (VRI) and a quality classification for large building stones was suggested. In addition, the applicability of the established classification to stone cutting with gang saws was checked. It was concluded that the quality classification and estimation of slab production efficiency of the building stones can easily be made by ultrasonic measurements. However, the study was carried out only in limestone. Further study must be conducted to check the validity of the obtained results for the other rock types.

Jan 1, 2007

By N. O. Lotter

Studies investigating the evaluation errors in laboratory scale flotation tests for platinum-bearing Merensky Reef in the Bushveld Complex, South Africa, have constructed a quality control model to assure a 95% confidence in the attested data. Specialized knowledge of the mineralogy of the platinum-group elements (PGE), together with acquaintance of evaluation models, validate a systematic checking of the sub-processes of the testwork. These include determination of minimum mill feed sample size, assay head reference distribution, mass balance checks, and specialized sample preparation of flotation test products prior to analysis. A flow schematic of this quality control model is proposed, with an example of test data that produce an error in the metal balance of 0,2% after rejection of outlier data.

Jan 1, 1995

By George G. Goble

The use of augercast piles has been limited by the engineer's concern for the structural quality of the installed pile. The nature of the pile is such that its final structural continuity is very dependent on the skill of the personnel that do the installation. Thus, NDT methods have been used to verify integrity and when problems are indicated the available solutions are usually quite costly. If information were available during the pile installation so that immediate steps could be taken to correct perceived problems, the concerns of the engineer could be addressed and the system would gain increased reliability. Pile Dynamics, Inc. has developed a quality control system, the Pile Installation Recorder for Augered Cast-in-Place piles (PIR CFA). This system consists of the following devices as shown in Figure 1. 1) The Control Unit powers the sensors, conditions the signals from the sensors, records all measurements, takes input information from the operator, displays the results, and stores the recorded data on a flash card for later permanent storage and processing. During the use of the system all of the results obtained during a test are seen during recording and can be reviewed on the screen again after completion of the installation. The ability to review the measured information makes it unnecessary to print a copy in the field. Since printers often give difficulty in the construction site environment the ability to review the results quickly after completion of the installation is an important capability.

Jan 1, 1997

By Regina N. Tempel, Timothy E. Eastep, R. Craig Ford, Bryce R. Roming, Geoff Clothier, Maggy F. Lengke

The Climax Mine, near Leadville, Colorado treats acid drainage in a lime neutralization chemical treatment system. Chemical treatment has been successful in reducing the concentration of metals to below surface water discharge effluent limits, but lime usage has not been optimized. A geochemical modeling approach has been developed to increase the efficiency of lime neutralization. The modeling approach incorporates two steps: (1) calibration, and (2) calculation of amount of lime needed to increase pH and remove metals. Results of our work quantify the lime treatment process and improve our ability to predict overall water quality.

Jan 1, 2000

By J Wei, X Lan, F Wang

This paper presents a quantitative assessment model for the assessment of environmental load in gold production, which is based on environmental ecology, Life Cycle Assessment (LCA) and artificial neural network. In LCA evaluation indexes include resource consumption, energy consumption, gas waste, liquid waste, solid waste and so on. Each item represents an aspect in gold production while their combination reflects the relationship between gold production and environment. In this paper an utility function of evolution index on environmental load is given by linear or non-linear transformation, which changes evaluation indexes with different dimension into an equivalent value in range of [-1, 1]. This paper also provides a new approach to make decision on the weight for quantitative assessment with the help of a three-layered artificial neural network. The proposed approach in this paper has been successfully used to a real synthetic assessment for the environmental load in gold production, which include seven kinds of different operational technologies in China. The applications prove that the new approach is successful and reliable. It provides a new tool for the assessment of environmental load of the gold production.

Jan 1, 2003

By Z. Jin, Q. Yun, C. Lu

This paper presents a quantitative assessment model for the assessment of environmental load in gold production, which is based on environmental ecology, Life-Cycle Assessment and technical conditions of gold production in China. This model can make environmental assessment in terms of a set of indexes and quantitative approach by means of artificial neural network, which also improves the theory of Life-Cycle Assessment. Keywords: Artificial neural networks, Environmental load, Assessment, Utility function, Gold production

Jan 1, 2003

As near-surface underground mines progress deeper, the inevitable question is whether to convert from truck haulage to shaft hoisting. The desire to defer capital expenditure frequently delays investigation of the shaft option, or deferral of a decision to start shaft sinking, unless the shaft option is clearly significantly better than trucking. By the time increasing depth makes trucking uneconomic, there may then be insufficient resource remaining to justify a shaft, and the mine must close. However, had the shaft been built earlier, its lower operating costs would have permitted the mine to continue to greater depths. This paper presents a methodology for investigating the shaft versus trucks decision. As well as the typical analysis of which option is preferable at the time the analysis is conducted, the process presented illustrates how the timing of the decision to sink a shaft is critical. The paper shows how to identify the latest date at which the decision to sink a shaft can be made, after which time the shaft option will not be economic. It also illustrates how to assess the resource that may be required to justify the shaft. Considering this in conjunction with the latest decision date, implications for the companyÆs exploration program are discussed.

Jan 1, 2005

A quantitative chemical model of the rocks of the Broken Hill lode environment is presented to illustrate a stratiform orebody in a meaningful form to scientists interested in environmental control on the chemicalcomposition of sediments.Even though this study was restricted by the narrow range of rock analyses available it is obvious that significant chemical differences exist between the various rock units and also that some association of metallic sulphides with Ca, Mn, Fe, and P is indicated.Correlation of this evidence with that from other mining fields may point out more definite chemical relationships and elucidate the puzzle of the mode of formation of many stratiform orebodies.

Jan 1, 1968

By Armando M. Lago

This paper reviews the postwar changes that have occurred in the expenditure and financial behavior of mineral corporations, and in particular the relative importance of factors that affect the industry's supply and demand for funds. This quantitative statistical investigation of factors affecting sources and uses of funds of mineral corporations is achieved through the formulation of a simultaneous equation model of sources and uses of funds. After a description of the study sample in Section I, the postwar cyclical and secular financial behavior of mineral corporations is analyzed in detail in Section II. Section III formulates an econometric model of mineral corporate financial behavior which is then estimated and reviewed in Section IV. Section V discusses policy issues regarding depletion allowances, investment tax credits, and industrial organization of the mineral sector. Finally, the optimum financial structure of mining firms is discussed in Section VI, which analyzes the effect of corporate financial structure on the mining corporations' average Cost of capital.

Jan 1, 1969

By T. Nishimura, H. Kiyama, K. Wakimoto

Discussion on the load bearing capacity of ground and the stability of tunnel is presented. We derive a simplified solution of a circular lined-tunnel in an elastic ground. The solution results in a better understanding of characteristic curves. Use of DEM allows us to consider effects of possible yield of the overstressed zone around the tunnel and inherent discontinuity of ground on the curves. Diskussion auf der Last Tragfähigkeit Bodens und die Stabilität des Tunnels wird dargestellt. Wir leiten eine vereinfachte Lösung eines kreisförmigen Ausbautunnels in einem elastischen Boden ab. Die Lösung ergibt ein besseres Verständnis der Kennlinien. Um Gebrauch DEM erlaubt uns, zu betrachten Effekte des möglichen Ergebnisses der überbetonten Zone den Tunnel und zugehörige Unstimmigkeit des Bodens auf den Kurven. La discussion sur la portance de charge de la terre et de la stabilité du tunnel est présentée. Nous dérivons une solution simplifiée d'un revêtement-tunnel circulaire dans une terre élastique. La solution a comme conséquence une meilleure compréhension des courbes caractéristiques. L'utilisation de DEM nous permet de considérer des effets du rendement possible de la zone surchargée autour du tunnel et de la discontinuité inhérente de la terre sur les courbes.

Jan 1, 2003

By Clarence E. Sims, Donald W. Williams, George A. Moore

INTRODUCTION DURING the past several years the steel casting industry has made studies of heavy castings in which the test bar has been taken from heavy sections rather than from attached or separately cast coupons. It has been noted that the ductility properties of these heavy sections are often lower than those normally expected. Such lowered ductility is usually accompanied by a spotty test bar fracture and the ductility values often can be greatly improved if a low-temperature aging treatment is given to the casting. A loss of ductility of this type is considered "abnormal," since it is not accompanied by an increase of tensile strength or hardness, and "temporary" when the ductility can be restored by aging. The cure of such an abnormal condition represents a real improvement in the quality of the steel. Some hundreds of previous investigations, largely qualitative in nature, have established beyond reasonable doubt that hydrogen is normally present in newly manufactured steel and that this gas, in small amounts, can cause a temporary abnormal loss of ductility. The commonly observed association of high gas content and low ductility has given strong evidence for the presumption that hydrogen, possibly assisted by other gases, is the primary cause of the low ductility observed. Accordingly, the Steel Founders' Society of America has, since Nov. 1, 1944, sponsored investigations at Battelle Memorial Institute whose primary objective is to obtain quantitative information on the relation of the amount of hydrogen and nitrogen in steel, together with associated methods of steelmaking and treatment, to low-ductility effects and porosity. In order that these investigations might proceed on a quantitative basis, hydrogen analyses of a precision considerably higher than any previously reported in the literature were necessary. The method chosen was selected entirely on the basis that it had the highest probability of freedom from uncontrollable errors and will be described in detail in another publication.1 Briefly, the method used consisted of the hot extraction of solid pieces of steel weighing from 45 to 50 g in a highly evacuated quartz tube maintained at 1050°C (1925°F) for a period 0f approximately 40 hr. The greatest precautions were taken to eliminate blanks and insure a sound gas-collection system. Vacuum and temperature conditions were maintained automatically. Mercury-filled risers were used for the introduction of samples in order that the system could be degassed thoroughly in

Jan 1, 1948

By Clarence E. Sims

DURING the past several years the steel casting industry has made studies of heavy castings in which the test bar has been taken from heavy sections rather than from attached or separately cast coupons. It has been noted that the ductility properties of these heavy sections are often lower than those normally expected. Such lowered ductility is usually accompanied by a spotty test bar fracture and the ductility values often can be greatly improved if a low-temperature aging treatment is given to the casting. A loss of ductility of this type is considered "abnormal," since it is not accompanied by an increase of tensile strength or hardness, and "temporary" when the ductility can be restored by aging. The cure of such an abnormal condition represents a real improvement in the quality of the steel. Some hundreds of previous investigations, largely qualitative in nature, have established beyond reasonable doubt that hydrogen is normally present in newly manufactured steel and that this gas, in small amounts, can cause a temporary abnormal loss of ductility. The commonly observed association of high gas content and low ductility has given strong evidence for the presumption that hydrogen, possibly assisted by other gases, is the primary cause of the low ductility observed. Accordingly, the Steel Founders' Society of America has, since Nov. 1, 1944, sponsored investigations at Battelle Memorial Institute whose primary objective is to obtain quantitative information on the relation of the amount of hydrogen and nitrogen in steel, together with associated methods of steelmaking and treatment, to low-ductility effects and porosity.

Jan 1, 1947

By M. Mostert

Mining companies sponsor a range of non-core, corporate social responsibility projects to adhere to social and labour plans and environmental management prerequisites that form part of a mining licence application. Some companies go above and beyond such projects, sponsoring initiatives that generate renewable energy through solar power, wind energy, natural gas, etc. The challenge for these companies is to choose between a variety of projects to ensure maximum value, especially in times when the economic climate might be less favourable for such projects. The focus of this research was to analyse the concept of sustainability as it exists today, and to apply that to the triple bottom line accounting method in an attempt to quantify the sustainability of a project. Research was done on the methane burn-off project at Sibanye Gold?s Beatrix Mine to establish how such projects are planned and financed, and what impact they have on the triple bottom line of a company. The financial bottom line is, by definition, one that executives understand. This paper also proposes a quantitative method for defining the social and environmental bottom lines as well. By considering the financial, social, and environmental values, the study attempts to determine a monetary value for a sustainable renewable energy project. This monetary value can be compared to similar values obtained for other sustainable renewable energy projects under consideration. The research suggests that monetary value alone is not enough to base a sustainable decision on, and qualitative measures are suggested for use in conjunction with quantitative methods. The selection method proposed should assist the board of a mining company to choose the most sustainable option and the project that will add the greatest value to the company across all three bottom lines. It will also provide increased justification for such renewable energy projects, even in periods of harsh or uncertain economic climates.

Jan 1, 2014

By J. J. B. Rutherford

IT is now well known that troublesome intercrystalline corrosion may occur in austenitic stainless steels following exposure of the metal to a temperature within the range 1000° to 1500° F. (540° to 815° C.). The present paper describes a satisfactory method of estimating the extent of such corrosion, based on the measurement of the electrical resistance of a specimen before and after attack. This new method enabled us to study quantitatively the effect of several factors upon intergranular corrosion in the 18 Cr, 8 Ni type of alloy. The results show that susceptibility to this attack increases with increasing carbon content and grain size and appears to pass through a maximum for certain combinations of temperature of sensitization and period during which the alloy was maintained at that temperature; and are in complete accord with our interpretation of the mechanism of this phenomenon. The method is probably applicable to other metals or alloys subject to intercrystalline attack, such as the aluminum alloys of the duralumin type. The methods hitherto in use for estimating the degree of intergranular attack fall into three types: (1) microscopic examination,1 (2) macroscopic examination of fractures, and (3) determination of the time required for complete failure or disintegration .2 None of these lends itself very well to a measurement of the extent of corrosion. The first two are qualitative in nature and the third provides an arbitrary value largely dependent on individual judgment, since failure is a progressive phenomenon and not a sudden event. Our experience is that weight-loss determinations, although valuable in some types of corrosion investigations, bear no simple relation to intercrystalline corrosion in this type of alloy, as is to be expected since the phenomenon probably involves only the thinnest films between adjacent metallic grains.

Jan 1, 1932

By R. P. King

A class of gravity separation unit operations in ore-dressing relies for its operation on the production of a stratified bed. Heavier material gravitates downwards, and separation is achieved by splitting the ore horizontally, with the recovery of a dense stream and a lighter stream. The important ore-dressing unit operations that fall in this class are the jig, the Reichert cone and the pinched sluice. A new quantitative model based on Mayer's potential theory is developed here. This model is developed completely for the simple case of binary mono-size particulate materials, but the extension to units operating with feed material distributed over particle size and density is discussed in principle. The model can be used to predict the performance of these units and is very suitable for simulation. The model is tested successfully against experimental data obtained from a batch jig and a Reichert cone.

Jan 1, 1987