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By Zhou Lu-Jian

The Port of Shekou is situated at Shenzhen Bay on the east bank of Lingding Ocean. Its coastline is about 6 km long and the water depth near the shore is Favourable. Across the bay is the ' New Territories " of Hong Kong. The port is at a distance of 22-23 seamilesaway from center of Hong Kong and 80 seamiles to Huangpu Harbour of Guangzhou, its highway links with Shen-Guang Highay. Since 19 79 China Merchants Group of the Transportation Department, began to set up Shekou Industrial Zone, the port has been developing and flouri­shing in business. With 15 large or small berths in all, the present portline is 2600 m, and the annual cargo throughout is over 3,000,000 tons and the annual passenger traffic is about 2,000,000 persons. Equalling a medium-scale seaport, it has been officially approved as an oceangoing transit port by the ministry of Transportation. The construction of Shekou port is chara-terized by the self-collected funds and the short construction period. In view of this, the optional plan of the port structure must serve the requirements of simplicity in struture, economy in mate­rial and speed in construction. That accounts for the most application of the sheet piling type to the port in Shekou. Once the project was approved, the cons­truction started. Only within an average period of 7-8 months, a deep water pier was completed and put into operation, which covered series of processes from exploration, designing, tender for con­struction to completion.

Jan 1, 1991

By Neil T. Davie, Thomas K. Blanchat, Thomas C. Togami, Joe R. Weatherby, Dale S. Preece, Robert A. Benham, James J. Calderone

"Geotechnical structures ,such as underground bunkers, tunnels, and building foundations aresubjected to stress fields produced by..the gravity load on the structure and/or any overlyingstrata. These stress fields may be.. reproduced on a scaled model of the structure byproportionally increasing the gravity field through the use of a centrifuge. This technology canthen be used to assess the vulnerability of various geotechnical structures to explosive loading.Applications of this technology include assessing the effectiveness of earth penetrating weapons,evaluating the vulnerability of various structures, counter-terrorism, and model validation. Thisdocument describes the development of expertise in scale model explosive testing ongeotechnical structures using Sandia’s large scale centrifuge facility. This study focused onburied structures such as hardened storage bunkers or tunnels. Data from this study was used toevaluate the predictive capabilities oft existing hydrocodes and structural dynamics codesdeveloped at Sandia National Laboratories (such as Pronto/SPH, Pronto/CTH, and ALEGRA)."

Jan 1, 1998

By J. Gummer, M. Williams, S. J. Hawksworth

A common problem encountered in British coal mines is bearing failure on conveyor system idler rollers, which on occasions has led to fires. The UK Mines Inspectorate initiated a study of such failures to assess the potential for ignition of explosive atmospheres. As part of this study HSL have developed a system to measure the temperatures generated within the bearings during controlled failure. Temperatures are measured using both infrared thermal imaging and contact thermometry. The work to date has shown that temperatures well in excess of the auto-ignition temperature of methane can occur.

Jan 1, 2003

By Sri C. Sawmliana, P. Pall Roy

Damage to underground roof and pillars in blasting gallery (BG) panels has been an increasingly important area of study in recent years due to the invention of new explosives and cord systems which has led to the modification and alteration of the design aspects developed by Charbonnage de France (CdF). According to extensive mine experiments conducted by Indian and foreign experts, it has been established that the induced peak particle velocity (PPV) is predominantly related to the emanated seismic energy of a source and the distance from the source. With that concept in mind, nearly 160 experimental blasts were carried out in four BG panels in India under varying geomining conditions. Based on the results obtained thus far, the authors have established predictor equations correlating explosive energy (in Joules) and distance from the shot to that of induced peak particle velocity received at the sensor point. Good correlation was obtained between the actual and the predicted values. It is realized that this equation may be used as an efficient tool to determine the size limit of blasts in BG panels so that the induced particle velocity does not create damage in underground workings as per the established Blast Damage Index (BDI) and other available safety norms.

Jan 1, 2004

By Conny Postupack

The first principle one usually learns about blasting is that competence in this field is best gained by experience in making blasts rather than by reading a book or by listening to a lecture. The reason for this is that there are a large number of variables affecting blasting results and not all of these can be accounted for by a few rules or a few sets of equations. Even an experienced in a new area, may have co make one or two himself to the new conditions with which he blaster when operating shots just to acclimate is faced.

Jan 1, 1991

By S. Möllerherm

"The evaluation of data and information provided by the existing traditional indicators in sustainability assessments is most important. Therefore the Institute of Mining Engineering I from the RWTH Aachen University developed indicators and an assessment system for the mineral raw materials industry on operation, company and sector level on behalf of the Federal Ministry of Economics and Labour (Bundesministerium für Wirtschaft und Arbeit, BMWA) and the Federal Institute for Geosciences and Natural Resources (Bundesanstalt für Geowissenschaften und Rohstoffe, BGR). In the course of the development of indicators for the raw materials industry quality indicators on different levels of the sustainability assessment procedure have been identified and developed. The following paper describes some of the results focussing on the development and integration of quality indicators into sustainability assessment systems."

Jan 1, 2005

By M. Ahrens, J. Gonser

Gearless mill drives are a well established solution for grinding applications in the minerals and mining industries. The paper describes the functionality and technical features of such drive systems as well as their advantages compared to other drive solutions. Due to the variable speed operation the grinding process can be optimized for ores with varying grinding properties. This leads to significant optimization potential for the plant design as well as for its operation. Furthermore, energy and cost savings due to optimized operation, high system efficiency and high system availability are shown.

Jan 1, 2007

By Michael Wieland

The resolving capacity of the thermodynamic work-principal model has been seriously refined over its twelve year history, so a review of the innovations, wrong turns and their rectification is warranted to help future researchers. The work-principal model rests upon the four laws of thermodynamics that drive the universe and relatively few other assumptions: like the removing and imposing of constraints on the quasi-potential to yield trapped minimum key-states that represent the wanted process. The formative research was concerned with the role of ingredient changes, the removal of booster influence and the quench temperature with which to reckon toxic fumes. The transfer of reaction-zone energy as work upon the surrounding rock/water/fixture was not fully rationalized until the notion of reversed-inertial pressure was formulated and determined (for water) with underwater trinitrotoluene (TNT) shots. The rock-water-jelly model incorporated that term into its dynamic pressure formula as a way to represent rock blasts or underwater shots, while the zone of reaction gases remained trapped. The real irreversible thermodynamic process, which yielded the total expansion work, was later complemented with a wholly reversible imaginary process, to form a closed thermodynamic loop, with a remarkable consequence – the determination of the theoretical heave and hence, the undissipated-shock by difference from the total work. With the wholly developed model, it was recently possible to quantify the time retardation of reaction chemistry for non-molecular (mining) explosives, as compared to the rather negligible time-retardation found for the molecular (military) explosives in underwater tests.

Jan 1, 2009

By K. Hanumantha Rao, A. Nayak, K. S. Narasimhan, S. N. Mahapatra

B.A. Hancock It is not at all surprising that causticized potato and potato derived amylopectin starch solutions performed much better than their parent starches. Some preparation is required to rupture the starch granules to effect the polymeric adsorption and interparticle bridging necessary for selective flocculation. In laboratory work comparing the deslime performance of causticized and autoclave cooked laboratory corn starch solution preparations, it was found that higher deslime weight rejections, with attendant proportionally greater iron unit losses, occurred with the causticized starch. These results may be specific to the ore involved but they do suggest that cooking and causticizing cause different starch granule rupture and/or starch breakdown, which have an effect on desliming response. I calculated from the data in the article that the slimes product grades were high - 24.3% and 20.3% Fe when 53.7% and 54.5% Fe concentrate products were obtained, respectively, in Table 4, and 21% Fe with a 62.6% Fe concentrate in Table 5 - using the natural tailings sample, which had a head of 34.3% Fe. It may be advisable for the authors to consider different starch preparations in future investigations. The combination of upgrading and selectivity results presented in Table 4 are not as good as the authors suggest. The authors' claim that a system has been developed to produce saleable concentrates from the Kudremukh tailings is quite disconcerting. There are many hurdles yet to be crossed before commercial application of selective flocculation becomes possible because differences between the very small-scale laboratory tests conducted and commercial application are rather large. Among the many differences are varying circuit feed grades that will occur from use of tailings, the apparent face that much lower tailings grades will be encountered in practice (it is much easier to achieve a high concentrate grade with reasonable recoveries using 34.3% Fe tailings as in the study rather than 25.3% Fe tailings grades that the plant apparently averages), the hydraulic nature of the thickeners used in operations compared to the static system used in laboratory tests, the different size distributions that will be obtained from a plant closed grinding-classification circuit, and differences in water used in a plant operation and the laboratory. The authors wrote that it was necessary to overgrind to be sure that the coarse gangue would not settle with the iron oxide floccules. This situation is likely to be exaggerated in commercial operations where it is assumed cyclones would be used for classification. Because cyclone classification is greatly influenced by particle densities, there will probably be an even greater difference in size between the iron and gangue particles in the plant, which would make the gangue slightly coarser still in relation to the iron. This would make the selective flocculation-desliming separations using the procedure employed by the authors even more difficult and, using the dispersant system the authors employed, greater overgrinding would be required. To grind finer to minimize the coarse gangue in the flocculated iron oxides is quite inefficient and appears not to broach the problem. The actual problem appears to be insufficient dispersion of the ground pulp. In this situation, addition of a dispersant would likely be required to attain a sufficiently high pulp dispersion level to efficiently effect a selective flocculation-desliming separation. Although the very coarse particles would still have a tendency to settle with the floccules, it probably would be found unnecessary to overgrind as much as indicated. Use of an optimum combination of dispersant and pH modifying reagents may also significantly improve the selectivity of desliming. Additionally, although it is possible that sufficient dispersion may be obtained by pH control alone in some situations, it is quite probable that added dispersity was obtained in the reported work from using distilled water. It is research experience that distilled water enhances dispersion. In commercial operations it may not be expected that sufficient dispersion will be obtained by pH control alone, unless the water used in the process is by nature quite dispersive. Overall, a change in the Kudremukh tailings dispersant scheme appears necessary where a dispersant is used in conjunction with a pH modifying reagent. With this change, different dispersion-flocculation responses will result that would have to be further evaluated. Therefore, it is still an open question whether an efficient and effective selective flocculation separation using Kudremukh tailings may be obtained that will produce saleable concentrates.

Jan 9, 1986

By Alastair Grogan

In October of 2002, the author was retained by Public Works and Government Services Canada, on behalf of the Department of National Defense, to design, construct and test the effectiveness of a bubble curtain system at an underwater demolition range, near Victoria, BC. The purpose of the bubble curtain was to reduce the potential for fish mortalities at the site. This paper presents some of the elements of the design, along with the results of overpressure monitoring during blasting and compares the results of fish mortality and animal behaviors with and without the bubble curtain in operation.

Jan 1, 2005

By Christopher Mark

The first International Conference on Ground Control in Mining opened with the topic of pillar design. Two classic papers were presented, one by Bieniwski and the other by Wilson. Unfortunately, the two methods were so radically different from each other that it was nearly impossible to reconcile them. Adding to the confusion were the many other pillar strength formulas (such as the Salamon-Munro, the Holland-Gaddy, and the Obert-Duvall, just to name a few) that were also available. Little wonder that discussions of pillar design in those days often ended with anguished cries of “but which formula is the right one?” The past 25 years have seen substantial progress in the science of coal pillar design. Indeed, one testament to the improvement is the relative scarcity of papers on the topic at recent Conferences. Two factors have been largely responsible for the progress that has been made. The first has been the collection of large data bases of actual case histories of pillar performance in a variety of settings, from shallow room-and-pillar mines through deep cover longwalls. These have made possible the development of empirical design procedures that are closely linked to real world experience. The second important factor is the development of sophisticated computer models that can accurately simulate pillar behavior and roof/pillar/floor interactions. Together, these two lines of research have led to a new understanding of pillar mechanics that identifies three modes of pillar failure: • Sudden, massive collapse, accompanied by airblast, for slender pillars (width/height<4) • Squeezing, or slow, non-violent failure, for most room and pillar applications (4<w/h<10) • Entry failure or bumps for deep cover and longwall applications (w/h>10) It is particularly satisfying that the insights gained from numerical models broadly support those obtained from the empirical studies. While far less controversial than in the past, pillar design problems continue to arise. One recent example is pillar design for highwall mining. NIOSH has just released a software package, called ARMPS-HWM, which employs a number of modern pillar design concepts. Since highwall mining web pillars are long and slender, the greatest danger is that of a sudden collapse. ARMPS-HWM suggests two possible prevention strategies, one which

Experimental results are presented for the anode overvoltage as a function of current density for different alumina concentrations in an alumina reduction cell. Voltage changes due to the electrolyte resistance and also the decomposition voltage, have been evaluated as a function of alumina concentration and anode current density. From these values of voltage, changes in the total cell voltage have been derived for changes in alumina concentration for different anode current densities. The results show that for each operating current density there exists a discrete alumina concentration that defines a minimum reduction cell voltage. Discussion is made about potential savings in power consumption when the alumina concentration is controlled.INTRODUCTIONThe standard procedure in the aluminium industry when analysing the cell-voltage required for the Hall-Heroult process for reduction of alumina, is to subdivide the total voltage into the following components (e.g. Pearson, 1955; Maritell, 1960).1. ohmic drop through busbars and joints2. ohmic drop through cathode lining3. ohmic drop through anode4. ohmic drop through electrolyte5. overvoltage at anode6. electrolytic decomposition voltage.(Overvoltages ,at the cathode are of negligible magnitude at all practical current densities.)It is understandable that the voltages assigned for each factor invariably differ for different workers...

Jan 1, 1965

By Jan Pru?ka

This paper describes the sheet pile design for the Line C extension from Ládví station to the North of Prague. The first part of the paper describes the geological conditions and structural configuration of the project. Typical cross sections, the description of the construction stages, and monitoring are discussed. The second part of the paper focuses on the sheeting design method. It describes the method of dependent pressures, that is, how the pressures acting upon a structure depend on the deformation. The design process and verification methodology are described in detail with comparison of the results with in-situ monitoring.

Jan 1, 2011

By Oliver Bowles

Accidental explosions in coal mines are due to various causes, but many of them can be directly attributed to coal dust; others that probably in no way depend on dust as a primary cause are propagated, greatly intensified, and made more disastrous by the presence of coal dust. The fact that coal dust in a bituminous mine will explode as a result of a fire-damp explosion has been generally accepted for many years, but the belief has also been held by many that coal dust is not in itself dangerous when unmixed with an explosive gas. Therefore, in past years little attention was given to dust in mines free from fire damp, and many disastrous explosions have resulted from lack of knowledge of the danger from coal dust. In the explosives gallery and experimental mine of the Bureau of Mines experiment station, Pittsburgh, Pa., it has been proved repeatedly and conclusively that coal dust will explode violently when no inflammable gas is present. PROPAGATION OF DUST EXPLOSIONS A coal-dust explosion is an extremely rapid burning or combustion of the coal particles. Their burning consists essentially of the combination of the hydrocarbons in the coal with the oxygen of the air, a process that generates heat and flame and produces hot gases and water vapor. These gases and vapors have a volume many times that of the original coal particles; thus they exert an outward motion and pressure which constitute the explosive wave. When fine particles of coal are suspended in the air, each particle is surrounded by the oxygen of the air, and thus is well placed to oxidize or burn rapidly whenever the temperature is high enough. If some particles are ignited from any cause they will fire others, and the combustion will extend from particle to particle with extreme rapidity wherever enough coal dust of sufficient purity is present.

Jan 1, 1925

By Rob Farnfield, William Birch, Douglas A. Anderson

In the blasting industry, even to the most safety conscious shotfirer, misfires are a constant source of concern. In the United Kingdom, there are two types of misfire, as classified by the Health & Safety Executive. Type A occurs when testing a shot before firing reveals broken continuity that cannot be rectified. However, due to the fact that a majority of quarries use non-electric initiation [i.e. shock tube] that cannot be tested, this type of misfire is very unusual.

Jan 1, 2016

By Gao Dazhao

This paper presents some research results of pile foundation performance. Measurements on the bearing behaviour and driving effects of piles have been carried out during pile testing and pile driving. It has been found that the ratio of end resistance to the ultimate load depends on the pile length, and the ratio in general is less than 40% for single piles. However for pile group, the end resistance seems to be greater than skin friction. The characteristic curves of skin friction and end re­sistance appear as interaction between soils and pile. The contribution of skin friction to the pile bearing capacity not only depends on soil properties but also on the relative position of the soil layer. The pore pressure and the lateral pressure in ground have been observed during the stage of driving piles. Based on the available data, the radius of plastic region and the coefficient of pore pressure A can be found analytically. The pore pressure time process curves which may be used for practice have been predicted by means of numerical method.

Jan 1, 1991

By Alan J. Lutenegger

Some years ago, a method was developed to incorporate a grout column around square-shaft helical screw-piles and anchors to increase shaft buckling resistance under compression loading. An additional benefit of this grouted shaft is to increase the load capacity in both compression and tension, depending on the geometry of the lead helical section and the soil conditions. Because of the unique construction procedure, the contribution of the shaft to the total capacity has largely been unknown. The behavior of grouted shaft helical anchors in clay was investigated by performing full-scale axial uplift (tension) load tests on a series of anchors installed at the University of Massachusetts Geotechnical Test Site. In order to isolate the contribution of the grouted shaft to the total load capacity, anchors were installed with a wooden dowel connection between the lead helical section and extension sections on three of the four anchors so that only the shaft resistance would be measured during the load tests. The grouted shafts ranged in length from 10 to 30 ft (3 to 9 m). Initial tests were performed approximately 5½ months after installation. Nearly four years after the initial tests were performed, the tests were repeated to evaluate any significant change in capacity with time and/or repeat testing (preshearing). The soil conditions at the site are presented along with the load-displacement curves for both the initial and repeat teats and a discussion of the analysis of the results. Repeat load tests showed an increase in capacity from the initial testing, however the percent increase was not the same for all depths. The results demonstrate that considerable shaft resistance can be developed in clays from the grouted shafts as might be expected. Depending on the L/D ratio of the shaft and the contribution of the lead helical section, at working loads the shaft capacity can dominate the behavior.

Jan 1, 2011

By I. Gombköto, G. Földing, G. Mucsi, B. Csoke, J. Faitli, B. Kovács

This paper summarizes the main achievements of our previous project entitled "Development of a technological system producing quality guaranteed fly-ash based binder". Furthermore, this study deals with the laboratory experience of lignite fly ash utilization for two different goals. On the one hand the fly ash was tested as a binder; on the other hand it was investigated as an underground mine backfill material. Considering the first goal, the utilization of a mixture of mechanically activated fly ash and lime for producing an independent binding composition has been assessed involving determination of relationship between the degree of activation of fly ash and the strength of the obtained concrete. The results confirmed that this hydraulic binder is suitable for construction of stabilization and capping layers or base layer. Regarding the backfilling application, this paper presents laboratory experiments, their results including settling tests, hydraulic permeability and strength measurements and dense slurry technology related results.

Jan 1, 2011

By Healy T. W, Dixon D. R

The present study &apos;of pure ZnS and NiS and ZnS (marmatite) by detailed electrokinetic methods has shown that by careful control of experimental parameters much new&apos; information on sulphide-water interfaces can be obtained. Time-dependent processes of alteration of sulphide surfaces are foHowed by electrokinetic methods and indicate that the isoelectric point of the surface depends on elemental sulphur coverage, oxidation product coverage, and the conditions which promote or minimize such reaotions in the presence and absence of activator.

Jan 1, 1977

By Jacob Masliyah, Zhiang Zhou, Tshitende Kasongo, Jianjun Liu, Zhenghe Xu, Jeawon Choung

"Slime coating is a recognized challenge in fine particle flotation, not only in decreasing recovery, but also in reducing the selectivity and hence froth quality. In this presentation, a novel method based on electrophoretic mobility distribution measurement to study slime coatings is described. By measuring electrophoretic mobility distribution of individual minerals and their mixtures, the interactions between these minerals can be evaluated.For illustrative purposes, a model system of fine coals, or oil sands with two different types of fine clays was studied. Flotation tests showed a significant decrease in coal (bitumen) flotation recovery with montmorillonite but not with kaolinite clay addition. When electrophoretic mobility distribution of a fine coal/montmorillonite clay mixture was measured, a single modal zeta potential distribution was obtained, in contrast to a bimodal distribution for fine coalkaolinite clay mixture. This finding suggests a stronger adhesion of montmorillonite than kaolinite clays on fine coal surfaces. In the case of bitumen, the bimodal zeta potential distribution was measured for the mixture of bitumen emulsion and kaolinite or montmorillonite, indicating a weak attraction of the clays by bitumen. In the presence of calcium, however, a single modal zeta potential distribution was obtained in the mixture of bitumen emulsion with montmorillonite but not kaolinite clays. These findings are in excellent agreement with bitumen flotation results, demonstrating that the electrophoretic distribution measurement is a powerful tool to study slime coating phenomenon in a complex fine particle flotation system."

Jan 1, 2002