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By Jay Rodgers

There has been a longstanding acceptance that burden plays a major role in the magnitude of ground vibration amplitudes generated from surface blasting. Much of the data that this belief is based upon is empirical in nature and may or may not represent an example of false inference. Recent published reports have rightly questioned the influence of burden and confinement on blast vibration amplitude, suggesting that the fracture condition of the rock mass is a better indicator. The increased investment in electronic detonators as a tool to control ground vibration amplitudes demands an understanding of vibration production detailed enough to make use of the vastly improved timing accuracy that they provide. A more accurate relationship may be found if we strip away the assumptions of the past and search for the underlying mechanism of vibration production in surface blasting. We must answer the question: What happens at or near the borehole when an explosive charge detonates that produces ground vibrations?

Jan 1, 2003

Experiment of Improving the Quality and Decreasing the Impurity of Titanium Concentrate in Panzhihua Mine in China

Sep 13, 2010

By Chu E. Ho

Current methods of determining jet grout column diameters are highly empirical and site specific, and do not take into account the jet hydrodynamics and soil parameters explicitly. A theoretical model which describes the jet excavation mechanism is introduced in this paper, with the aim of providing an improved prediction tool that can be used in jetting design. The model is based on the assumption that the velocity distribution in the cutting jet is equivalent to that of a free jet with boundaries corresponding to the dimensions of the cavity excavated in the ground. The shape of the cavity formed depends on the erosional properties of the soil and jet expansion is limited by the resistance at the jet-soil interface. The model predicts that the limit of jet penetration is reached when the average dynamic pressure at the jet tip becomes equal to the ultimate soil bearing resistance. The reliability of the model, evaluated using results from four case histories of jet grouting field trials, is within ±15%.

Jan 1, 2006

By Victor R. Spironello

Applications of three experimental design techniques to smelting operations are explained. The report describes a factorial design using three variables at two levels, a fractional factorial design which investigates seven variables, and response-surface methodology for optimization of electric- furnace smelting processes. These methods may be applied with a minimum of trials and at little expense. Further, the writer knows of no reasons why the same methods could not be applied to other operations as well, such as steelmaking.

Jan 1, 1970

By W. Mbhalati

"Conzal Mine was not meeting production targets in 2013, and it was established that this was caused by the inability of the load haul dump machines (LHDs) to tram the required tonnages. An investigation of the LHD productivity was therefore conducted to identify the inhibiting factors. This was accomplished by carrying out a literature review on LHD operations to gain in-depth knowledge and conducting observations in the working environment. The relevant information and data on the LHD type used at Conzal was also acquired.The major inhibitor was found to be excessively long tramming distances in all the sections of the mine. The one-way tramming distances were all significantly greater than the 90 m set in the mine’s code of practice (COP), with the Main Shafts section having the longest average one-way tramming distance of 260 m. The other inhibitor was LHD utilization, which in 2013 was only 47% against a target of 70%. Simulation of the LHD operation, taking these two factors into account, showed that production could be increased by more than 100%. As a result, it was recommended that conveyor belts should be extended regularly in order to keep tramming distances within the recommended one-way distance of 90 m. In addition, utilization can be improved by minimizing employee absenteeism as well as by modifying the travelling routes such that LHDs do not encounter unnecessary delays.Paper written on project work carried out in partial fulfilment of BSc. (Mining Engineering)"

Jan 1, 2015

By Robert G. Lenz

Control of ground water for construction purposes is an everyday occurrence in the U.S. Thousands of pumps are in service at any given time. Most of these applications simply consist of pumping water out of an excavation, generally with the aid of sumps. Modern hydraulic and electric submersible pumps permit these procedures because of their ability to pump solids and take air without losing their prime. These procedures work fine up to a point and permit the contractor to control his ground water problems adequately and at minimal cost. When that point is exceeded, the ground water problems sometimes are compounded. Over-application of open pumping techniques can result in slope failures, cofferdam instability, bottom heaving, boils, loss of ground, damage to adjacent structures and utilities, and assorted other maladys which could and should be avoided. This paper will deal with the options involved in ground water control, a discussion of the unwanted side effects of dewatering, and examples of ground water control projects in various cities around the U.S.

Jan 1, 1988

By X. Yuan

"The processing behaviours of ores such as their liberation characteristics in comminution and their response in separation processes are affected by their mineralogical characteristics. Key ore characteristics which are relevant to processing, such as mineral proportions, mineral grain size, grain shape and mineral associations are routinely measured at the micro-scale in polished section using optical microscopes and SEM-based automated mineralogy systems. The application of X-ray micro-tomography to mineral processing provides the means to quantify these important micro-textural characteristics in three dimensions, removing the stereological issues encountered when measuring volumetric information in two-dimensional polished sections. In this paper we present several examples of ore textures to illustrate where X-ray micro-tomography can be applied successfully to obtain quantitative measures of ore characteristics which are useful in a variety of process modelling applications.INTRODUCTION X-ray tomography has been used as a tool in medicine for some years and is being applied in a wider range of fields including geology, palaeontology and mineralogy. In this paper we present some applications of X-ray tomography in mineral processing applications being developed at JKMRC. The availability of SEM-based automated mineralogy systems such as MLA and QEMSCAN has seen the increased use of quantitative mineralogical data measured in two dimensions in the design, operation and simulation of mineral processing plants. When the ore is amenable to measurement by X-ray tomography this technique can provide quantitative data for characteristics such as mineral grain size, shape, mineral associations and liberation in three-dimensions. The advantage of measuring these characteristics in three-dimensions is that the stereological issues which bias measurements made on polished sections are removed. X-ray tomography also quantifies the location of mineral grains relative to one another in space - a useful descriptor of ore texture. Like many measurement techniques X-ray tomography has advantages and disadvantages when compared to other techniques. One limitation is that the ability of the X-ray tomography system to discriminate between minerals is a function of the X-ray attenuation of those minerals. While the X-ray attenuation of many common minerals is sufficiently different for X-ray tomography to distinguish between them, there are some where the overlap in X-ray attenuation makes discrimination on the basis of this characteristic alone impossible. An example of this would be chalcopyrite and magnetite. However where the ore mineralogy is suitable to apply X-ray tomography, the technique provides some exciting opportunities to explore the relationship between texture and ore processability."

Jan 1, 2012

By C. F. Weinaug, R. W. Farley, J. F. Wolfe

A rapid, accurate method for predicting the dew points of gas condensate systems and their subsequent normal and retrograde phase behavior with pressure decline has been developed. The method predicts dewpoint pressure, volume percent liquid, condensate content of produced gas, and the liquid and gas compositions at pressures below the dewpoint pressure. Use of a modified form of the BWR equation of state, which was established by regression calculations on experimental data from several gas condensates, provides depletion behavior predictions that are significantly improved over predictions using K-values based on convergence pressures and Standing's correlation for density. INTRODUCTION Prediction of complex hydrocarbon-mixture thermodynamics is fundamental to reservoir and gas process engineering. In particular, accurate descriptions of phase behavior are needed to plan production operations for gas-condensate reservoirs. Although analysis of reservoir behavior during producing and cycling operations can be made for simple reservoir models, extensions of these studies to more complex reservoir systems are still difficult, both with regard to numerical techniques and the phase behavior of the fluids. This report presents a mathematical method for handling the complex phase relationships encountered in retrograde condensates; it represents an advance in reservoir behavior technology in that it will aid the development of closed-form mathematical representations of total production systems. A typical phase diagram for a complex hydrocarbon mixture is shown in Fig. 1. When the reservoir temperature T, is higher than the critical temperature Tc, and lower than the critical-condensation temperature Tct' the mixture is a gas condensate. Decreasing the pressure on a condensate while maintaining nearly constant temperature will result in two phases forming at the dew point. Further decrease in pressure will cause additional liquids to be formed. This phenomenon is called retrograde condensation. As pressure continues to decrease, normal phase behavior regions are encountered (liquid vaporizes as the pressure decreases) until the low-pressure dew point is encountered. When a gas-condensate reservoir is produced, gas is withdrawn and the volume of fluids in the reservoir remains nearly constant as the pressure declines. Heavier components tend to accumulate in the liquid phase as a result of retrograde condensation, while lighter components tend to concentrate in the vapor phase. Thus, as the gas is produced the composition of the gas and the condensate

Jan 1, 1970

By Wenjun Ju, Xiaodong Sun, Jianwei Zheng, Bingding Yi, Zhaorui Ma, Pengfei Jiang, Lingfu Zhu, Yangfa Zheng

The presence of hard roof poses a significant threat to the safety of underground coal mining. In this study, a mechanical model is established for underground stopes to analyze the overburden structure with the advancing of the mining face. It is indicated that the load-bearing arch structure (LBAS) is formed above the stope for roofs with regular hardness, whereas the reversed-basin bearing structure (RBBS) is formed for hard roofs. Compared with the LBAS, the RBBS can induce an additional pressure at the foot of the bearing structure, and this effect becomes less as the distance between the hard roof and stope increases. The ultra-deep borehole hydro-fracturing technique (UHT) is proposed to weaken the hard roof for pressure release, and the associated equipment and procedures are also presented. The UHT is based on horizontal drilling along the axial direction of the roadway in the roof, and then the receding segmented hydraulic fracturing technique is used to achieve the purpose of fracturing (weakening) of the surrounding rocks. Field tests are carried out in 3022 roadway of Daliangwan coal mine in Yulin to assess the developed technique, equipment, and fracturing procedures. To evaluate the fracturing effect, deep borehole stress-meters are installed at different depths of the fractured and un-fractured zones of the roadway, along with hydraulic support pressure sensors placed at the mining face. The results show that compared with the un-fractured zone, the pressure on the wall and pillar sides is lower than that in the fractured zone, and the associated weighting duration and weighting area ratio of the fractured are reduced by 53.23% and 33.59%, respectively. This indicates that the presented UHT can provide a new solution for the prevention and control of mining disasters induced by hard roof failures in underground coal mining.

Nov 2, 2020

By Xiaowen Liu

The DSC/TG, IR and XRD analysis were used to characterize the heating phase transformation of illite, which came from Ouhai deposit, China. It was discovered that the dehydration and de-hydroxylation of illite carried out stage by stage during heating. The adsorptive water and layer-inter water were dehydrated from room temperature to 500°C; and dehydroxylated in the range 500°C~800°C. In these stages of process, illite?s layer structure kept almost unchanged. After 800°Cillite began to change into disorder structure. At about 1100°C, the layer structure of illite had been destroyed, and amorphous SiO2 and mullite crystallite appeared. At about 1200°C the structure of illite completely destroyed and mullite crystal phase had become perfect..

Jan 1, 2006

By Aram Grigoryan

This paper addresses the challenges of designing the underpinning of major sub-way station with 4 operating tracks. No. 7 subway extension crosses under the existing 42nd street subway station on the 8th Avenue line. Understanding the history of the original construction, of the current structures and their condition were instrumental in developing a feasible underpinning design that is integrated with the design of the new tunnels. The existing 8th Avenue subway station has a lower abandoned level. Several alignments and corresponding underpinning schemes were studied. The design allows new tunnel construction under the station without interruption of station operations.

By Enrique Castells

La extracción del mineral es el método más habitual para la explotación minera y se realiza a través de rampas, galerías, y túneles que permitan el acceso hasta la zona de minado. Sin embargo, cuando se da una excesiva profundizaciión del terreno, se emplea el método de pique vertical ya que logra el acceso de los operarios a las zonas más profundas de un modo más rentable y rápido a través de la extracción del mineral por izado de vagones o skip hasta el de nivel de superficie o intermedio. Por ello, es común que las minas replanteen la sustitución de su sistema de extracción habitual por el de izado por piques. En este sentido, el presente trabajo desarrolla la aplicación de los piques verticales en los sondeos de exploracion de la mina Hullera Vasco Leonesa. La primera parte del proyecto describe la ejecución de dos piques verticales (Aurelio y Emilio del Valle), y la segunda, en la ejecución de más de 17.000 m de galerías y obras de infraestructura de diversa índole.

Sep 13, 2001

The corrosion of aluminosilicate refractories by soda from three different sources has been studied by microscopic methods. Sodium sulphate from oil ash, sodium chloride used in glazing structural clay products, and sodium borate from borax-impregnated wood ash have fundamentally the same effect on the refractories. The soda is the chief medium of reaction and fluxing, the sulphur, chlorine, and boron being volatized as sulphuric, hydrochloric, and boric acids.INTRODUCTIONBecause of their strong fluxing action, alkalis are one of the main causes of corrosion and slagging of refractories.The action of potash and soda on refractories follows somewhat similar lines, although it is common for one alkali to be greatly in excess of the other. The course of the reaction in a number of cases of alkali attack has been studied by microscopic and chemical methods. For example, the action of potash on blast furnace refractories was studied by Kraner (1942) and Rigby and Richardson (1947), who described the occurrence of various potassium aluminium silicates. Its action on cement kiln refractories was described by Brisbane, Segnit, and Weymouth (1957). The action of soda on glass tank refractories has been studied by many people, for example Bisby (1956) and Resch (1954). Clews, Hugill, and Green (1940) made a microscopic examination of the attack by soda on silica bricks from a gas retort.Some recent cases of corrosion of aluminosilicate refractories which were brought to the attention of the Division of Building Research, C.S.I.R.O., illustrate phenomena which occur under conditions different from those...

Jan 1, 1964

By David Dardick

Tround International Inc. is developing rock excavation and drilling devices which utilize a simple patented mechanism for firing frangible projectiles. This system launches a salvo of three projectiles with every shot in automatic sequence. Studies conducted by Physics International Inc. have demonstrated that firing projectiles into hard rock such as granite creates fragmentation which is much faster and cheaper than conventional drilling and blasting. The Tround salvo approach enhances this further by a controlled stresswave interaction created by a slight time difference during impact of the individual projectiles. The University of Maryland is conducting additional studies to optimize these parameters.

Jan 1, 1981

By W. P. Johnstone

The computer assisted generation of geological models to represent the geometry of, and grade distribution within, orebodies is a rapidly growing area of the geological profession. Such models are increasingly used as a necessary starting point in determining the mineability of mineral deposits in terms of practical mine design and economic considerations. The transition from traditional techniques such as field or underground mapping and the manual calculation of grade and tonnage estimates, as well as related activities such as the interpolation of cross-sections, the use of stereographic projections, core logging and hand contouring, to computerized applications, is by no means complete. In fact, many geological professionals deliberately avoid the use of computer simulations based on the perception that the resulting models are simplistic and that their construction is not founded on sound geological principles. The purpose of this paper is to assess current thinking on this topic by considering; (a) an overview of advances in the drafting of geological maps, (b) the theoretical basis for multi-dimensional geological modelling, (c) the case for combining traditional and modern techniques, and (d) the benefits to the mining value chain.

Jan 1, 2003

By B. G. Tarasov

This paper proposes the further development of a recently identified shear rupture mechanism (fan mechanism) that elucidates a paradoxical feature of hard rocks ? the possibility of shear rupture propagation through a highly confined intact rock mass at shear stresses that can be significantly less than frictional strength. In the fan mechanism, failure is associated with consecutive creation of small slabs (known as ?domino blocks?) from the intact rock in the rupture tip, driven by a fan-shaped domino structure representing the rupture head. The fan head combines such unique features as extremely low shear resistance, self-sustaining stress intensification, and self-unbalancing conditions. Consequently, the failure process caused by the mechanism is inevitably spontaneous and violent. Physical and mathematical models explain unique and paradoxical features of the mechanism, which can be generated in primary ruptures and segmented faults. The fan mechanism provides a novel point of view for understanding the nature of spontaneous failure processes, including shear rupture rockbursts. The process explains, in particular, features of shear rupture rockbursts such as activation at great depths, generation of new shear ruptures in intact rock mass, nucleation of hypocentres at significant distances from the excavation, shear rupture development at low shear stresses, and abnormal rupture violence.

Jan 1, 2014

By H. Jalkanen, L. Holappa

The main role of slag in oxygen converter processes is to absorb the non-volatile oxidation products of hot metal impurities, Si, P, Mn, Ti, V, etc. The importance of converter slag as deP and de Smedia has ceased with implementation of special pre- and post-converter treatments. The transfer from top blowing (LD) to combined blowing converters has decreased the amount of slagged iron that, together with the tendency towards lower silicon and manganese contents, has decreased slag to steel ratio. Still the control of slag forming and behaviour during the blow is of great importance. In this paper the thermodynamics of the slag forming reactions, the role of slag in the modern oxygen converter process for impurity elimination, splashing, lining wear, dust formation and post combustion are discussed on the basis of common knowledge and experience of Finnish steel plants.

Jan 1, 2004

Geological maps, data, and prospectivity analysis relevant to mineral exploration in New Zealand have recently been released. Regional-scale geological mapping is increasingly available for the country through the QMAP 1:250 000 Geological Map of New Zealand programme. Published QMAP sheets Greymouth, Wakatipu, Waitaki and Dunedin cover large areas of interest for mineral exploration companies. The QMAP geological data are also available in digital form for use with other digital datasets using GIS software. Crown Minerals, in cooperation with GNS, have completed two gold prospectivity studies; the first covering mesothermal gold in the South Island, and the second encompassing epithermal gold in northern New Zealand. These studies have defined areas of interest for these two mineralisation types and assembled geological, mineral occurrence and production, geochemical, geophysical, topographic and cultural data into projects for use with GIS software. Included are the results of prospectivity modeling for gold using these data and specific mineralisation models. The prospectivity studies and relevant data are freely available on CD through Crown Minerals and are intended to encourage mineral exploration in New Zealand.

Jan 1, 2003

By H. Hejny

"The mine of the future will exploit mineral raw materials at greater depths than today, requiring completely different approaches compared to today’s deep mines, in order to get mineral rights. Only these eco-efficient mines will contribute to improved access to domestic mineral resources, secure the sustainable supply of mineral raw materials for Europe and reduce the import dependency. IntelliMine will contribute to realise these concepts of invisible, zero-impact and safe mines. The mine of tomorrow will run an integrated concept in order to guarantee the desired level of sustainability. All operations necessary for the eco-efficient provision of the minerals including waste management will be carried out underground. This will drastically reduce the volumes being transported, minimising above ground installations and thus the environmental impact. IntelliMine will develop necessary innovative methods, technologies, machines and equipment for the safe, eco-innovative, intelligent and economic exploitation of mineral raw materials in the EU, especially at greater depths."

Jan 1, 2011

By W. G. Stevenson

The centennial celebration of the AIME provides an opportunity to review some aspects of developments in mineral exploration since 1871 and to reflect on the changes that have occurred. During this period seven Factors have fundamentally altered the procedures, techniques and philosophy of mineral exploration. Although most of these developed gradually, and unheralded, they have drastically altered the art of exploration and discovery. 1. ADVANCES IN MINING AND MILLING The development of huge shovels, draglines, trucks and track-mounted drills, to replace the wheelbarrow and single Jack has drastically expanded the rate of production for both underground and surface mining. The development of selective flotation has had a far-reaching affect on mineral exploration and has made it possible to extract metals from the metallurgically complex deposits discovered years before. These developments have reduced the costs of mining and treatment, and have transformed material into ore that was considered waste one hundred years ago. These advances have permitted exploration for progressively lower grade and larger mineral deposits.

Jan 1, 1971