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By James Stewart

"THAT WHICH WE CANNOT SEE" INTRODUCTION Often it has been stated that the greatest of all fears is fear itself - fear created only by that which we cannot see or by that which we fail to understand. The elimination or minimization of fear can best be accomplished by a thorough understanding of the underlying causes of the fear. As related to the mining industry the omnipresent fear is the dread of acquiring cancer through accumulated exposure to "that which we cannot see" - radioactivity. The understanding of the resulting exposure effects can best be obtained through acquisition of authentic data and the subsequent analysis of the same by a group of highly qualified specialists. I may point out that the nuclear industry and its source, uranium mining, greatly surpass any other industries in the degree of public awareness as to its potential environmental effects. Public out-cry has always influenced major decisions relating to how industries conduct their operations and much of their effort has resulted in many changes. The issues of health and safety in the mining industry have created considerable public concern, but intense concern to those of us directly involved within the industry. Increasing concern regarding the effect of human activity on the quality of the outer environment of air, land, and water has developed within the past two decades. There is now a growing concern about the health and safety of persons at work in their inner environment, of their working-places in industry. Hearings and investigations conducted in Canada by three appointed "Royal Commissions" have all confirmed that this concern is well justified when focused on the health and safety of workers in our mines. REGULATORY CONTROL OF URANIUM MINING OPERATIONS In Canada, the ownership of mineral resources and the control of their extraction, except for uranium, is vested under the "British North America Act" in the provinces. In all provinces the statutory basis for health and safety provisions in the mining industry can be found in the provincial "Mining Acts" with each province assuming the responsibility to produce its own "Mining Act". In particular, all of the Mining Acts in Canada place upon the management of a mine the responsibility to ensure that provincial provisions are met. The "Federal Register" and mining companies parallel this arrangement in the United States. Equivalent legal

Jan 1, 1981

By K. M. Myles

The vapor pressure of palladium over a series of Rlz-Pd alloys has been measured by the torsion-effusion method. The thermodynamic properties of the alloy system at 1575=K have been calculated from the vapor pressure data. The activities and the free energies of formation exhibit large positive deviations from ideal behavior. The enthalpies of formation are endother-mic. The entropies of formation are positive and larger than the ideal entropy of mixing. All of the thermodynamic properties suggest that a strong tendency toward phase separation exists in the solid solutions. The possible origin of the phase instability and the various factors that influence the thermodynamic properties are discussed. RECENT studies of the thermodynamic properties of alloys of palladium with nontransition elements have indicated that a significant contribution to the enthalpy of formation is related to the redistribution of the conduction electrons upon alloy formation.'-' The present work was undertaken to ascertain the importance of this contribution in Pd/transition-metal alloys. The Rh-Pd system was chosen for this investigation for several reasons: 1) The thermodynamics of the system were unknown. 2) Rhodium and palladium are completely soluble at high temperatures; below 1118OK the solid solution becomes immiscible.', 3) The difference in magnitude between the vapor pressures of rhodium and palladium permitted the use of an existing effusion apparatus. 4) Additional information was known about the alloy system that would facilitate the interpretation of the thermodynamic results. EXPERIMENTAL PROCEDURE The thermodynamic properties of the Rh-Pd alloy system were calculated from the vapor pressure of palladium over solid palladium and over several solid Rh-Pd alloys. The vapor pressure was measured by means of the torsion-effusion apparatus that has been described previously. In this method, an effusion cell is suspended from a tungsten filament inside a high-temperature furnace. Two orifices are located eccentrically such that the effusion of the vapor creates a rotational torque in the filament. The angle of rotation is directly related to the total vapor pressure within the cell. As the vapor pressures of rhodium and palladium are approximately five orders of magnitude apart," the total vapor pressure was considered to be effectively equal to the equilibrium vapor pressure of palladium. The effusion cells were made from high-purity alumina since auxiliary experiments indicated that essentially no reaction occurs between alumina and solid Rh-Pd alloys. Unfortunately, because the orifices were irregular, an accurate calculation of the Free- man-Searcy correction factors" could not be made. The constants were determined in an independent experiment where the vapor pressure of copper, as measured in the alumina cell, was compared with an accurate value of the vapor pressure, which had been determined previously.4 Depletion of palladium from the surfaces of the specimens was minimal as the deflection of the cell remained constant, for at least 15 minutes, at each of the experimental temperatures. Lattice parameter measurements of the postrun alloys also indicated that no changes in the composition of the surfaces had occurred. The alloys were prepared by arc melting the requisite amounts of the 99.99 pct pure elements. The four most palladium-rich alloys were remelted in a levita-tion furnace since complete melting of the components had not occurred in the arc furnace. All of the alloys were subsequently homogenized at elevated temperatures in sealed alumina thimbles. After heat treatment, the alloys were analyzed chemically and were in essential agreement with the nominal compositions. The thermal histories and nominal compositions of the alloys are given in Table I. Lattice parameters of the heat-treated alloys were computed, by means of the method described by Mueller et a1. ,I2 from X-ray diffraction powder patterns obtained with filtered copper radiation in a 114.6-mm-diam Straumanis-type Debye-Scherrer camera. The results, which are tabulated in Table I, exhibit a slightly greater negative deviation from Vegards' law than the values reported by Raub et al.13 The diffraction lines were sharp and well-resolved and thus indicated that the alloys were homogenous. RESULTS The logarithms of the individual values of the vapor pressure of palladium were fit, by the least-squares method, as a linear function of the reciprocal of the absolute temperatures. The constants of the equations are given in Table I along with the temperature range over which the data was accumulated. The latent heat of vaporization at 298.15"K for pure palladium, calculated by the third-law method,14 showed no systematic temperature dependence. The average value of 88,920 * 20 cal per g-atom agrees favorably with the average of the results obtained in the most reliable previous investigations.15"19 The activities of palladium were computed from the vapor pressure data at 1525', 1575", and 1625OK. Consistent with the mass spectrometric study of the atomicity of palladium vapor,lg the vapor was assumed to be monoatomic. The activities of rhodium were determined by integrating the Gibbs-Duhem equation with the aid of the a function.20 In the calculations, the activities of the pure solid metals were assigned the value of unity. From the activities, the partial and integral free energies, entropies, and enthalpies of formation at 1575° K were computed; they are assembled in Table 11.

Jan 1, 1969

By Jair Alarcón, Lucas Steffen, Leopoldo Muñoz

Flyrock is one of the most significant hazards associated with blasting in open pit mining, especially for blasting operations near communities. Flyrock can lead to severe injuries, fatalities, and property damage, compromising the license to operate. For this reason, defining exclusion zones is critical to ensure the safety of people and equipment. A very large radius will reduce the risk of flyrock; however, excessive exclusion zones can significantly impact the productivity of the operation and, in some cases, compromise the extraction of ore in critical sectors. Many mine sites use distances derived from pre-established standards, experiences from other mines, or still use simple methods for analysis, like recording blasts with a terrestrial camera and performing deterministic calculations to determine exclusion areas, applying an arbitrarily safety factor for people and equipment. In this paper we present a new approach that allows the calculation of the exclusion zone by measuring critical flyrock parameters with a high degree of accuracy through a new video analytics technology, this data then is used as input to calibrate probabilistic flyrock models to have more robust calculations, allowing optimized and safe exclusion zones. The proposed methodology leverages high-accuracy data and continuous monitoring to dynamically adjust D&B designs and exclusion zones, ensuring maximum safety without unnecessarily restricting operational efficiency. A case study is presented where the application of these new digital technologies allows precise prediction and control of flyrock trajectories, enhancing the accuracy of exclusion zone boundaries. In this case we successfully reduced the exclusion zone radius to 100m, allowing the ore extraction in a critical region close to the community safely. The study shows notable improvements in safety and productivity, including zero flyrock incidents and enhanced protection for nearby communities. The adaptive nature of these digital tools offers scalable solutions for various blasting environments. The paper concludes by recommending the integration of these tools into standard blasting protocols, highlighting the potential for widespread adoption in the industry to mitigate flyrock risks effectively.

Jan 21, 2025

By Xuling Chen, Zhiyun Ji, Min Gan, Wenqi Li, Xiaohui Fan, Zhiyuan Yu

"Specularite and vanadium-titanomagnetite are difficult to granulate, and with the increase of their proportions, the permeability of sintering bed is deteriorated together with the combustion velocity of fuel for the shortage of air through the sintering bed, which can lower sintering speed and specific production capacity significantly. The biomass fuel has a higher combustion velocity than coke breeze, therefore the productivity of specularite and vanadium-titanomagnetite ore can be improved remarkably by replacing coke breeze partly with biomass fuel .The results showed that, when the proportion of biomass fuel replacing coke is 40%,the sintering speed and specific production capacity of 35% specularite were improved from 19.06mm/min, 1.33 t/(m2·h)to 21.45mm/min, 1.47 t/(m2·h),and that of 55% vanadium-titanomagnetite were improved from 17.23mm/min, 1.11 t/(m2·h)to 22.80mm/min, 1.44 t/(m2·h). As a conclusion, biomass fuel is effective to strengthen sintering of refractory iron ore.IntroductionThe iron and steel industry of our country has achieved significant development in the recent years. In 2010, the output of steel has reached to 0.627 billion tons. The increasing scale of iron and steel has led to rigorous domestic iron ore environment, and the reserves of hematite and magnetite that have superior sintering characteristics are on the decline with continually exploiting and utilizing [1]. Therefore, the RIO (refractory iron ores) SP (specularite) and VT (vanadium-titanomagnetite) have to be applied vastly. However, the quality of sinters can be deteriorated when utilizing RIO in high proportion due to their poor granulation and metallogenic performances [2, 3]. Generally, the ratio of SP is 3~5%,which should not exceed 10% in our country currently [4]. Though high rate of VT is adopted in PZH steel for a long time, the productivity is obviously low compared with normal sintering [5]."

Jan 1, 2012

By Jingzhi Liu, Xueping Hu, Huai Wang, Simin Yang, Baoqiang Yu, Deguang Zhan

In this study, response surface methodology (RSM) and Box-Behnken design to improve copper extraction from refractory copper oxide ore were investigated. Based on single factor tests, quadratic polynomial equation to describe the relationship between influencing factors (particle size, leaching temperature, sulfuric acid concentration, leaching time) and copper leaching rate could be obtained by RSM. The optimum parameters determined by the model are as follows: particle size 64.60% − 74 μm, leaching temperature 74.15 °C, sulfuric acid concentration 0.49 mol/L, and leaching time 140.85 min. Under these conditions, experimental copper leaching rate of 85.12% could be achieved, which was very close to the predicted maximum value (85.34%) by the model, indicating the quadratic polynomial model was accurate and reliable. Copper leaching rate increased approximately by five percentage points comparing to the result of single factor tests. This study indicates that response surface methodology is an effective method to optimize experiment conditions and achieve an ideal experiment result.

Aug 17, 2022

By Merete Tangstad, Lars Klemet Jakobsson

"Slag refining is a promising refining method for boron removal from silicon as a part of a metallurgical route for production of silicon for solar cells. There is, however, limited data on the distribution of impurity elements between silicon and different types of slags. In the present study, the distribution of boron and calcium between silicon and slag were determined at 1600 °C for calcium silicate slags with a CaO/SiC>2 ratio between 0.65 and 1.3. An almost horizontal linear trend was found for the distribution of boron between silicon and slag, and the borate capacity was found to follow the relationln(CB0, ) = 30.8 + 2.96-V (1)where V\s the CaO/SiCh mass ratio within the range of the experiments.IntroductionSolar grade silicon feedstock contributes significantly to the total cost and energy required to make crystalline silicon solar cells. A less expensive and less energy requiring method of solar grade silicon production is therefore needed in order to make crystalline silicon solar cells more viable as an energy source. Silicon is an abundant element and the manufacturing cost of solar grade silicon is therefore mainly determined by costs related to purification of metallurgical grade silicon. The Siemens process is the most common process today, but it is an expensive and highly energy requiring process that gives silicon with a higher purity than is needed for crystalline silicon solar cells. A cheaper and less energy requiring method for production of solar grade silicon can either be achieved by modifying the Siemens process or by using a new production method. Purification of metallurgical grade silicon through a metallurgical route is a promising method that is already in use industrially. It has however proven to be hard to lower the boron content to 0.3 mg/kg or less, which is the requirement for most p-type crystalline silicon solar cell manufacturers. Slag refining is seen as one of the most promising approaches that can be used to bring down the boron content to the required level, but there is not much data on how boron is distributed between silicon and binary calcium silicate slags [1-4]. The distribution of boron between silicon and calcium silicate slags at 1600 °C has been studied in this work, and the obtained data has been used to calculate the borate capacity of binary calcium silicate slags."

Jan 1, 2012

By H Bleuler

A new portal and access drift was constructed by Concrete Constructions for BHPÆs Elouera Colliery, south of Wollongong.The portal area at the base of the Illawarra Escarpment is in soft colluvium material, underlain by highly to moderately weathered sandstone. The area has a well documented history of slope movement or slope creep and one of the main criteria for the design was to minimise disturbance to the unstable slope by limiting the excavation for the portal establishment. This was achieved by incorporating a sloped headwall and gabion wingwalls to accommodate the anticipated creep and groundwater seepage.Main features of the design process also included the provision of both primary and secondary support in a single shell application and the use of canopy tubes to provide support ahead of the tunnel face.The active involvement of the designer during the construction phase and the flexibility of the design concept allowed changes to the support methodology to be carried out as excavation proceeded.This paper describes the design process undertaken for portal establishment and access drift to cater for the variability of the exposed ground conditions along the drift alignment.

Jan 1, 1999

By William L. Fink, H. R. Freche

The constitution of the aluminum-cobalt alloys has been the subject of relatively few investigations. Brunckl analyzed the residue which remained after treating the 17 per cent cobalt alloy with dilute hydrochloric acid. The results of the analyses indicated the existence of a compound Co3Al13. Guillet2 published a liquidus for the aluminum-cobalt system which contained two maxima corresponding to CoA16 and CoAl2 and two eutectic points at 30 and 74 per cent Co. The most extensive investigation of the system was carried out by Gwyer13 whose results are summarized in Fig. 1. It will be noted that at the aluminum end there is a suppressed eutectic at 644' C. By extrapolation of the duration of the eutectic arrest to zero, the composition of the compound was placed at Co3Al13. Another thermal arrest was noted at 550" C., which Gwyer attributed to a peritectic reaction. The present investigation of the aluminum end of the aluminum-cobalt system is the eleventh of a series dealing with the constitution of aluminum-rich alloys prepared from electrolytically refined a1uminum.l Preparation of Alloys.—The alloys used in this work were all prepared from electrolytically refined aluminum, the analysis of which is shown in Table 1. In preparing some of the alloys, metallic cobalt (98 to 99 per cent) was used either directly or in the form of an intermediate alloy, the composition of which is given in Table 1. In order to obtain alloys of higher purity, cobalt was introduced into some of the alloys by means of chemically pure cobaltous chloride which was readily reduced by the aluminum. A small electric furnace with nickel-chromium heating elements was used in the preparation of the alloys. Chemical Analysis.—An analysis sample from each melt was chill-cast in the form of a plate 3/16 in. thick. In all cases the casting temperature was well above the liquidus. Cobalt was determined electrolytically in all alloys containing more than 0.05 per cent cobalt and by the nitroso-

Jan 1, 1932

By S. Banisi

Thickening is the most widely applied dewatering technique in mineral processing. Thickeners are used to increase the concentration of suspension by sedimentation, accompanied by the formation of a clear liquid. As the particles get finer the thickening process encounters difficulty due to a significant change in the settling behaviour of particles. The batch settling tests of coal refuse of a coal washing plant which contained 91% particles smaller than 38µm and 0.6% coarser than 75 µm showed that the optimum feed percent solids that provided highest flux (solids handling capacity) was 4%. The flux of the pulp with the plant solids concentration (i.e., 10%) was 60% lower than that of the pulp with 4% solids. A thickener with a diameter of 22m based on the dilution of feed from solids concentration of 10% to 4% was designed. Monitoring of the thickener performance for a period of one month in the plant indicated that on average the feedrate of 25t/h (dry solids) with solids concentration of 10% could be thickened to the underflow concentration of 26.5% with a clear water overflow. It was found that the key component of the successful operation of the thickener is the dilution of the feed without which the overflow loses its clarity and the system ceases to operate under predetermined conditions. Specially designed feeding system which efficiently dissipated the energy of the incoming flow and staged flocculant addition regime are among the main contributing factors in making the design and operation of such thickener possible.

Jan 1, 2014

By R. Drozd

"The Bullmoose Mine is currently under construction in the North East Coal area of British Columbia, and approximately $300 million will be spent to bring this 2.3 million-tonnes-per-year metallurgical and thermal coal mine into production by December 1, 1983.The project is an unincorporated joint venture undertaking, with Teck-Bullmoose Coal Inc., a wholly-owned subsidiary of Teck Corporation, holding 51%, Lornex Mining Corporation holding 39%, and Nissho-Iwai (Canada) Ltd. holding 10%. Bullmoose Operating Corporation will be the manager and operator of the project.This paper will broadly cover the history and exploration work on the property, the geology, open-pit mining plans and equipment, the preparation plant flowsheet from breaker station to clean coal silo, the 35 km highway truck haul, the railroad loadout system, manpower requirements, construction progress, approvals and permits, and general financial arrangements.IntroductionThe Bullmoose Mine Project"" is located about 87 road kilometres south of Chetwynd, B.C. and consists of an open-pit coal mine, a plant facility in the Bullmoose Creek valley below the mine, and a separate rail loadout facility on the British Columbia Railway Branchline near the new town of Tumbler Ridge some 35 road km to the east.The plant will be capable of producing a total of 2.3 million tonnes per year (mty) of washed metallurgical and thermal coal. Long-term metallurgical coal contracts for high quality, medium volatile, bituminous coal have been signed with nine Japanese buyers for 1.7 mty, and the balance of 0.6 mty will be thermal coal production.Plant construction began in the spring of 1982, and in May 1983, preproduction waste and overburden removal in the mine will commence. The plant should be fully operational by December 1983, and first vessel loading at the Ridley Island port is scheduled for January 1984."

Jan 1, 1983

By J. W. Spretnak, J. N. Cordea

The gain boundary relaxation in high-purity aluminum, nickel, copper, and silver was studied by means of a low-frequency torsion pendulum. Both internal friction and creep at constant stress tests were conducted. A lognormal distribution in relaxation times was found to account for the relatively wide experimental internal friction peaks and the gradual relaxation behavior during the creep tests. This distribution was separated further into a lognormal distribution of relaxation time constants and a normal distribution in activation energies. A spread of up to ±6 kcal per mole in the activation energies accounted for the major part of the distribution. A "double-peak" internal friction phenomenon was observed in silver. The activation energies in kcal per mole derived from the grain boundary relaxation phenomena are 34.5 for aluminum, 73.5 for nickel, 31.5 for copper, and 41.5 for silver. It was found that the rain boundary relaxation strength in these metals increases with the reported stacking-fault energy. GRAIN boundary relaxation phenomena have been observed in a large number of polycrystalline metals and alloys. Numerous investigations have been conducted to study the structure of the grain boundary through this relaxation process. One of the first investigators was Ke1-4 who observed that the activation energy for grain boundary relaxation in aluminum, a brass, and a iron was about the same as that for volume diffusion. He concluded that the grain boundary behaved as if it were a thin liquid layer with neighboring grains sliding over one another. Leak5 conducted experiments on iron of a higher purity and observed that the grain boundary activation energy is comparable with that of grain boundary diffusion. He suggested that, in metals where this relationship holds, the damping may be caused by a reversible migration of grain boundaries into adjoining grains. Nowick6 has presented an interesting view of inter-facial relaxation with his "sphere of relaxation" model. A relaxed interface is represented as one where the shear stress is greater than the normal value along the edges and zero in the interior of the interface. The region of the stress relaxation is pictured as a sphere surrounding the interface. From his calculations Nowick concluded that the slip along an interface is directly proportional to its length. Therefore, the time of relaxation, T, depends on the size of the relaxation interface. This means that in the Arrhenius relationship, t = TO exp[H/RT], valid for atom movements, the relaxation time T is predicted to be proportional to the grain diameter through the pre-exponential term, TO. Since the internal friction can be given as Q-1 = ?j wt/(1 + w2r2), where ?J is the relaxation strength and w is the angular frequency, an increase in grain size at a constant frequency will shift the peak to a higher temperature. A great deal of work has been done to determine the exact relationship between the internal friction and grain size.1,5,7,8 In metals, the grain boundary peaks are found to be lower and broader than predicted theoretically.' The above model can explain this by a distribution in the size of the interface areas, represented by a distribution in the parameter tO, and an overlap of spheres of relaxation, represented by a distribution in activation energies. Both these phenomena result in an over-all distribution in the relaxation time, which could affect the internal friction peak height, breadth, and also position. This relationship between the experimental data and theoretical calculations appears very promising in the study of interfacial relaxation mechanisms. THEORY A lognormal distribution in t can sometimes be used to adequately describe the spectrum of relaxation times governing an anelastic relaxation. wiechert9 originally suggested such a distribution to explain the elastic after-effect in solids. This choice is particularly applicable to grain boundary relaxation when considering Saltykov's work.'' He found a lognormal distribution in the grain sizes within a metal. Recently Nowick and Berry11 have introduced a log-normal distribution in T into the theoretical internal friction equations. The form of the distribution function is where z = In(r/rm), and Tm is the mean value of t. The parameter ß is a measure of the distribution and is the half-width of the distribution when is l/e of its maximum, IC/(O). Nowick and Berry have described the methods to obtain the parameters Tm, ß, and ?,J from experimental internal friction and creep test data. In the idealized case, where only one relaxation event occurs with one relaxation time, only ?J and T are necessary to completely describe the event, and 0 = 0. For the broader internal friction curves 6 is some positive number greater than zero. The larger the 6, the greater is the half-width of the distribution in In t.

Jan 1, 1967

By R. Stefanko

Rock bolting as a method of support continues to increase with applications in many other industries in addition to mining. Nevertheless, with nearly 55,000,000 roof bolts installed in coal mines alone last year, this remains as the single greatest use. While bolts have frequently supported ground where conventional timbering could not, there are relatively few design criteria; and trial-and-error procedures prevail. Furthermore, development of suitable instrumentation that is simple to install and readout, sensitive, durable, reliable, safe and economical in evaluating the effectiveness of a bolt over long periods of time lags behind. Therefore, the pull test continues to be the most popular method of evaluating the applicability of a certain type of roof bolt under specific installation conditions. At Penn State in the Department of Mining, research has been conducted for a number of years to measure bleedoff in carefully controlled laboratory experiments as well as in underground investigations.1,2,3,4 Unfortunately, most of the instrumentation developed has been primarily suitable only for research purposes, not possessing all of the aforementioned characteristics desirable for routine underground use. Other groups also have met with restricted success. Therefore, while relatively crude, the torque wrench continues to remain as the most widely used load measuring device. While both field and laboratory tests continue to be conducted, analytical analyses are attempted to discover the more important design parameters in order that more efficient anchorage might be devised.

Jan 1, 1969

By Michael S. Wieland

This report focuses on the U.S. Bureau of Mines research regarding desensitization and malfunction of delay detonators and cap-sensitive explosives. Delay blasting in underground coal generates tremendous shock waves and rifting forces that fracture and heave coal. The shock waves from charge explosions radiate outward in all directions through the coal, impacting neighboring charges with later delays. The impact phenomena have debilitating effects, causing degrees of reduced charge performance ranging from misfires or weak detonations to out-of-sequence detonations. Impaired charges react poorly, fracture less coal, and produce fumes with higher toxicity. Coal-mine, underwater, and simulator tests were conducted to more thoroughly understand the shock damage mechanism. Recently the U.S. Bureau of Mines partially resolved the malfunction problem by demonstrating the feasibility of formulating a rugged explosive. This rugged cap-sensitive candidate passed the requisite tests for certifying an underground coal-mine explosive. With natural aging the formulation rapidly lost initiation sensitivity. The charge formulation had to be rebatched to finish the testing and therefore could not be certified.

Jan 1, 1992

By William S. Gardner

It is certainly an honor to have been invited to address the Deep Foundation's Annual Meeting on such a vast and weighty topic as "Present to Future Design Considerations of Deep Foundations." Acknowledging the enormity of this 30-minute assignment, I hope to at least scratch the surface of the topic deep enough to generate some thought and reflection. Design considerations, be they current or future, bring to mind a number of important subtopics which comprise the design process. As shown by Figure 1, a flow chart of this process describes, in general terms, the sequence of a deep foundation design.

Jan 1, 1991

By AIME

The Taconites Are Ready, the editorial appearing on P. 933 of the September issue, has provoked comment from several informed engineers to the effect that the indicated profit margin was considerably exaggerated. The cost figures in the editorial, taken from the Congressional Record, were characterized as inaccurate by some correspondents. The theme of the story was, however, substantiated in the announcement (P. 1023, October) that Republic and Armco had joined forces in a $160 million project for taconite development. Chief among the dissenters was E. W. Davis, , Director of the Mines Experiment Station at the University of Minnesota. Mr. Davis has worked up the following set of cost figures:

Jan 1, 1950

By P R. Botha

Mining has played a significant role in human development and without the mining sector, society would not enjoy a large number of the benefits that it does today. However, mining has also carried with it some important lessons, which remain the source of ongoing learning. One of these lessons is the poor closure or abandonment of mines, worldwide. This has in many cases resulted in large tracts of unproductive land, representing a source of environmental pollution and a safety hazard to the community. Frequently associated with this is a legacy of mining communities having fallen into economic and social decline, beyond mine closure.Due to this legacy, governments, society and the mining sector pay far greater attention to mine closure planning today, than was done in the past. Typically closure planning has focused on the engineering aspects of a mine, namely decommissioning of the workings and plant; dismantling of unusable infrastructure; and rehabilitation of disturbed land. These are important aspects of closure but a more holistic, long-term approach is required which encompasses environmental and social aspects and aims to leave a positive legacy behind.In planning for a mine closure scenario with a lasting positive legacy, it is critical that the broader receiving environments (social, economic, physical and biological) within which a mine is located, define and drive the closure plan and the mine planning as a whole. This ensures that the broader environment influences mine closure, as opposed to looking at how a closed mine will impact on the environment. The ultimate aim is to first understand the broader environment and then to fit the closure of a mine into it. The earlier this approach is followed in the life of a mine, the greater the operational time frame available, and hence a better chance is presented for planning and managing a mine towards the desired, tested and agreed post closure scenario. Within this broad context, there is tremendous scope to achieve successful mine closure. However, it is critical to note that mine closure is not the sole responsibility of the mining companies, and neither is it possible for said mining companies to achieve mining closure alone. This concerted effort requires a multi-stakeholder approach in which partnerships are created and risks, responsibilities and opportunities are shared and managed. To achieve sustainable closure, a multi-stakeholder approach based on an initial forward-looking closure vision is required. This approach provides an early basis for consideration of alternative land uses and economic options from which specific actions to achieve the preferred option can be defined. The Anglo American plc Mine Closure Toolbox has been formulated and developed around this concept. The Toolbox aims to expand mine closure planning - from financial provisioning for rehabilitation and physical closure, to planning for sustainability beyond mine closure and leaving behind a positive legacy.This paper focuses on the business case for mine closure planning and provides an overview of the Anglo American plc (AAplc) Mine Closure Toolbox.CITATION:Botha, P R, 2012. The business case for mine closure planning and an overview of Anglo AmericanÆs mine closure toolbox approach, in Proceedings Life-of-Mine 2012 , pp 7-10 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 10, 2012

By Paul Hewitt, Aaron Rastall

The New South Wales South Coast rail corridor is key infrastructure for both freight and passenger transport. Geomorphological and geological evidence suggests that land instability has been widespread throughout sections of the rail corridor, long before the first documented record of landslide activity in 1879. Major landslides occurred along a 25-km length of the South Coast Railway connecting Sydney and Wollongong because of significant rainfall events of the late 1980s. Since this time, several sites have been identified as subject to instability and treated progressively under a risk priority and safety management system. Two such sites comprise a station footbridge and overhead wiring structure (OHWS), both founded on high embankments overlying colluvial materials resulting in the structures’ potential movement and associated stability concerns. This paper presents these two sites as case studies, and discusses the project geology, geotechnical models developed, interpretation of monitoring data, and successful remediation of the rail structures using sleeved bored piles. The sleeved pile system was used to isolate bored piles, which separated the bridge foundations and OHWS from the moving soil mass to ensure the piles can carry the rail structure loads, unaffected by downslope soil movements.

Nov 1, 2022

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Jan 1, 1997

By Adrian Brown

Floor heave can be a major problem in large open pit mines. Unrestrained floor heave can lead to flooding, equipment destruction, slope instability and subsidence. It is particularly troublesome in coal mines where the floor is frequently relatively flat, and is often underlain by major water Searing units. This paper examines methods of analysis used in computing floor stability, and sets out a simple rational method of evaluating the required level of water pressure control to maintain acceptable floor stability. The approach is illustrated by reference to the stability of the floor of the Morwell open cut lignite project in Southeast Australia, where this approach has been used successfully for over a decade.

Jan 1, 1982

By L. D. Eccleston

Any man-made structure will eventually decay, but we are basically concerned with the prevention of corrosion within a fairly limited time span. How corrosion can be minimized by design, the removal of oxides and a careful choice of paint systems is discussed, and mention is made of the electrical nature of most anticorrosive systems. Also discussed are the characteristics of certain paint binders and how mechanical properties will differ for various environments. Corrosion of a substrate by acidic breakdown products of some paints is mentioned in conjunction with a discussion on convenience versus ultimate performance. A brief mention is made of the three main components of a paint system, and the principal types of paint are placed in broad categories, with the main strength and weaknesses of each type listed.

Jan 1, 1979