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By A Grigg, L Hackett

Alcoa operates two bauxite mines at Huntly and Willowdale, located within the jarrah forest south-east of Perth in Western Australia. Ore reserves are shallow but extensive, and mining pits averaging around 20 ha in size are distributed across a mining region in a mosaic pattern, linked to a centrally-located crusher by a radiating network of haulroads. A mining or crusher region is defined partly in terms of economic haul distances, and new regions are opened once the current regions’ reserves have been mined. Since commencing in 1973, the Huntly mine has constructed and progressively closed three previous mining regions and is presently in a transition from the fourth and current region of McCoy to the new region of Myara. At present rates of production, approximately 450 ha is cleared, mined and rehabilitated each year.The value of topsoil in returning a diverse mix of native jarrah forest plant species and supplying nutrients, organic matter and soil biota to rehabilitated areas has long been recognised. Managing the topsoil resource is therefore a critical element in the success of rehabilitation outcomes, but the distribution and dynamic nature of mining operations pose significant planning and logistical challenges. The regionalised approach to mining at Huntly also presents a range of issues for what are, in effect, soil management plans for episodic mine closure. The nature of mining and rehabilitation operations are described, together with the planning processes that Alcoa follows to quantify, track and report on soil movement. A case study of the Huntly mine demonstrates that an integrated operational and life-of-mine planning process is essential for successful and cost-effective mine rehabilitation.CITATION:Hackett, L and Grigg, A, 2014. Topsoil management for long-term mine operation and closure – a case study from Alcoa's bauxite mining operations in south-west Australia, in Proceedings Life-of-Mine 2014 , pp 609–614 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 16, 2014

By Rick Deschamps

A reoccurring problem with support of excavations in urban areas involves the placement of external support components like anchors or nails in right-a-ways, subway and utility setbacks, in areas occupied by adjacent structures, and within the property of non cooperative neighbors. Such a situation occurred for a project in Arlington, Virginia, which ultimately resulted in the preliminary design of a large footing supported cantilever retaining wall that was extremely costly and impractical to build. An innovative design alternate consisting of a series of vertical concrete elements (VCEs) supported by post tensioned tiedowns was proposed to the General Contractor and accepted by the owner. The VCEs were designed to serve as the main structural elements for both the temporary support of excavation system and the permanent wall. The VCE?s were constructed using single bite diaphragm wall panels oriented perpendicular to the excavation face including a rebar cage and tremie concrete. Threaded inserts were placed within the rebar cage to attach the cast in place exterior wall. Overall stability and lateral movement of the VCEs were controlled by high capacity vertical anchors embedded within the VCE. A detailed instrumentation program was installed to monitor the movements of the VCEs with relation to the excavation depth. The paper present the project case history by discussing the design concepts of the VCE, the construction approaches used to install them, the construction challenges encountered, and the performance of the unique system.

Jan 1, 2008

By John Vynne

BHP’s Navajo coal mine installed drill monitoring and high precision navigation systems on their three overburden drills during 2002 and 2003. Details of the DrillNav system hardware and reporting system will be discussed, as well as the significant benefits Navajo has achieved since the systems were installed. Navajo is not satisfied with the current results and plan additional upgrades to the systems. In addition, Navajo plan to integrate the data from their drill systems with data from other systems to achieve even greater increases in drill productivity and to reduce overall mining costs.

Jan 1, 2007

By Fredrick C. Kruger

Introduction This surprisingly little-known group of minerals, the nonmetallics, so-called for their lack of metallic luster, is the largest group of the mineral kingdom, and cinstitutes perhaps 75 percent of all mineral species. For the most part, these minerals are compounds of the common acids, oxides, hydroxides, and two elements, carbon and sulfur. The list of the non- metallic minerals, therefore, is very long. It includes the borates, carbonates, chlorides, fluorides, nitrates, phosphates, silicates, sulfates, and less commonly, arsenates, chromates, molybdates, suliides, tungstates, and vanadates, the latter groups, and many of the oxides, being sought principally for their metal content. Those nonmetallics used commercially are generally called the industrial minerals, although in addition this term also includes a considerable group of rocks. The list of industrial minerals and rocks is continually growing as new uses are found, and it now numbers over 300 commodities. The industrial minerals industry has developed since about 1920. There- fore, the development has been fast, and it has been more or less parallel with the development of the art of minerals beneficiation. General Discussion of the Group This group is so heterogeneous that it has defied logical, or widely accepted, classification, whether by origin, composition, or end use, and perhaps for this reason the industrial minerals generally have received short shrift in both teaching and research. Except for those involved with asbestos, cement, fertilizers, gypsum, salt, sand and gravel, few large companies have deigned to enter the field, and consequently most industrial minerals have been developed for the most part by the small operators or entrepreneurs. Yet surprisingly, except for one war year, the nonmetallics have always surpassed the metals in value and tonnage (Fig. 1). One main characteristic that most of the nonmetallics have in common is direct sensitivity to labor and transportation. In other words they are characterized by large bulk and low-unit value, and hence have what might be termed a "place value".

Jan 1, 1971

During the past three years Lurgi's Circulating Fluid Bed (CFB) technology has been successfully applied to roasting of refractory gold ores and con- centrates. In comparison with the so-called Stationary Fluid Bed roasting systems, a considerable improvement of gold recovery, to around 95 per cent, has been demonstrated and achieved on many occasions in pilot CFB units and in commercial CFB roasting plants as well. The major reason for such improved gold recoveries is the excellent controllability of the roasting process in the CFB reactor system. Here, temperature, gas atmosphere and solids residence time are more precisely controllable at optimal values during roasting operation in order to achieve the highest possible gold recovery in the subsequent leaching process step. Further dominant benefits of CFB roasting systems are their flexibility with regard to feed material, throughput capacity, dry or slurry feed, almost unlimited oxygen enrichment, direct fuel addition and in situ capture of SO2 in the presence of limestone and dolomite. The system will accept 50 per cent turndown ratio, large variations in feed composition and particle size, as well as a variety of different fuel types. The commercial applications of CFB roasting systems for gold con- centrates have been realized so far at Fimiston, Kalgoorlie/Westem Australia and for whole ores at Cortez, Nevada/USA.

Jan 1, 1991

Sailing westward from the Society Islands in the fall of 1774, England's noted explorer Captain James Cook discovered New Caledonia-that long, linear island that has played such an important and varied role in the history of nickel. Upon his return to England the following year, Cook's announcement of this uncharted island generated governmental interest, but its distance from the Island Empire, the troubles in the colonies, and the difficulties with France combined to keep English interest indirect and in the background of the then-current events.

Jan 10, 1968

By Rajasekar Subbian, Jessica Oudhof

In the Netherlands pile foundation design is done using CPTs in accordance with EC7 national annexure. The capacity per tip level is calculated for every CPT followed by zonation to find the tip level per zone. The correlation factors are used to take into account the variability in ground across the zone and they depend upon the number CPTs within the zone. The CPTs and pile tip levels selection for zoning is an iterative process that can demand significant manual effort to produce an economical pile plan. This often leads to the use of conservative correlation factors in order to accelerate the design process. Thus, it has been automated in a tool with CPTs, pile location and loads, and capacities as input. The tool has also been employed in two case studies and the results are compared to the current design practise.

May 1, 2022

By Jorge Cárdenas, José Luis Hurtado

The critical distance determination test through direct recording for the mine in Phase 03 was carried out in January 2024, and in it the vibration and pressure models were obtained for the Sedimentary breccia unit. The method of obtaining the records is based on the capture of individual pressure waves generated by distant loads, sequenced in periods of 600 ms for easy identification. The test set up corresponds to a variation of that used to obtain the vibration model, and uses 08 wells for loads and 04 for instrumentation. The results apply a safety factor of 1.2 and 1.5, being 16,000 PSI and 13,250 PSI respectively. The values are valid for any distance greater than 5.5 m, this being the minimum established between wells for loads according to the configuration defined in the field, also considering that in 5.0 m of instrumentation the section of the drill hole with the sensor called S1 collapsed. The results of the analysis of the test, generated with Heavy Anfo 82 explosive, with a final density of 1.15 g/cc, are presented. The results of the modeling and generation of the graphs and tables presented show behavior in line with the concept of scaled distance. It is important to consider that in water conditions there is a high impact by the condition, which causes the records to be higher than those expected in dry conditions and present less variability. It is for the above reason that the row corresponding to distance with safety factor 1.5 is declared valid. The results are only valid for the rock analyzed, whose medium is homogeneous and constant in terms of lithological composition and that present similar resistance characteristics, fracture frequency and water table levels. As future steps, the objective is to quantify the increase in pressure generated between wells by analyzing time and sequence factors. This analysis aims to explain the occurrence of dynamic pressure events in areas where critical safety distances are observed.

Jan 21, 2025

By Ethan Steward, Kyle Perry

Blast resistant structural design continues to be a research area of major concern for governments around the world due to explosive threats from both state and non-state actors. Glass and aluminum curtain wall systems are commonly used to clad the exterior of government and commercial structures, allowing light into the building, regulating the interior environment, and providing an aesthetically pleasing exterior. These systems are likely to fail when exposed to sudden, high-pressure events such as the purposeful or accidental detonation of explosives. Engineers have designed blast resistant curtain walls and structural elements to reduce the likelihood and severity of failure, but the design tools and testing mechanisms commonly used in the process may not accurately model or simulate actual blast conditions at all ranges. In blast resistant structural design, the origin of a shock wave is typically assumed to be in the far-field, creating a wave that is nearly planar and parallel to at least one face of the target. Shock is applied evenly and immediately across the entire impacted surface. However, the source of real-life blasts is often very close to the target structure, and the assumption of far-field planar shock does not always apply. Mid-field blasts exhibit qualities different from those assumed about far-field shocks, specifically a hemispherical shock that produces different peak pressures, impulse curves, oblique reflections, and Mach stems across a target. This paper will examine mid-field shock effects from scaled distances of 2.5 to 4 13 (6.3 to 10.1 13) on a tall, scaled target by measuring reflected and incident pressure, impulse, and shock velocity across the target. Results will be compared to theoretical blast parameter equations and empirical data used by the industry. Possible effects of mid-field blasts on structures and further research ideas will be suggested.

Jan 21, 2025

By B Vorster, T Medhurst, A Huey

Roof conditions at Oaky North Mine can be prone to stress related damage and/or time dependent degradation. The ability to identify these areas prior to mining has proved challenging using traditional methods. To help alleviate this situation, a study was initiated to investigate methods for roof characterisation using geophysical logs. This involved the use of neutron log data to provide an indirect measure of the proportion of carbonaceous/micaceous laminae present in the immediate roof strata. Detailed analysis of the shale–porosity inter-relationships arising from this analysis provided a means to estimate the proportion of laminations for a given roof interval. This paper outlines the process and how it was used to improve the current GSR modelling and hazard mapping process.

Nov 29, 2022

By A B. Jahed, Ö Aydan, T Ito

In this study, the authors compiled some case history data and present some typical examples of rock slope stability issues in Afghanistan with a special emphasis on Kandahar region and categorise rock slope failures according to the principles of modern rock slope engineering. The slopes considered involve rock-cut, natural rock slopes mainly. The effect of structural geology and discontinuous nature of rock mass on both slope-cuts and natural rock slopes is taken into account and some preliminary assessments on the stable and unstable rock slopes are presented. Furthermore, the seismic effect on their stability is also considered. It is also pointed out that similar issues could be observed in open pit mines, which may be exploited in years to come.

Nov 29, 2022

By Y K. Leong

Occasionally additives are used in the wet processing of iron ore tailings and slurries, for examples, in the thickening of tailings with flocculant to recover process water, and in the smooth pumping of concentrated slurries. They can mitigate slurry behavioural issues that could significantly affect the plant operation and production. The nature of iron ore business requiring the plant to have a high throughput to be economical, large amounts of slurries are therefore processed every day. The quantity of additives needed will correspondingly be large and so are the associated costs. This could have a significant impact on the plant profitability. If additives are used they must be very costeffective. NaOH is among the lowest cost chemicals available, at ~US$400 per ton. In this paper we will look at use of composite additives involving phosphate compounds with NaOH added to reduce the cost, for the control of iron ore slurries rheology. The NaOH worked synergistically with the phosphate compounds. The effectiveness of these composite additives in viscosity reduction can be neutralised by another cheap additive such as lime or a Ca(II)-based salt turning the slurries back to being a paste. Tailings paste is an ideal material for safe storage in the dam. These composite additives can also be used to facilitate the recovery of iron ore at commercial grade from tailings (Leong, 2020a, 2021a).

Sep 18, 2023

By K. T. Stafford, N. A. Iverson, V. T. McLemore

Southwestern New Mexico is part of a large belt of Late Cretaceous to Eocene copper porphyry deposits found in Arizona, New Mexico, and Mexico. These deposits are the result of arc magmatism that occurred during the Laramide orogeny. Recently, attention has been brought to other commodities that can be extracted as by- and co-products, many of which are critical minerals. A new compilation of the geochronology of these deposits shows two main pulses of magmatism that produced mineralized deposits and, along with new dates by the author, shines new light on the geologic history of these deposits and the role it plays in critical mineral abundance.

Feb 1, 2024

By Boyd Eisenbraun, Dennis Murr, Milton Rojas

Approximately since 1925, the phenomena of grinding and classification of minerals with screens have been studied. In the U.S. iron ore mining operations located in the so-called “Mesabi Iron range,” magnetite processing plants have made progress in the application of high-frequency screens that have allowed them to process low-grade Taconite ores and successfully achieve the economic benefit of these minerals. In the particular case of magnetite minerals disseminated in the siliceous matrix, the main objective is to reduce the generation of particles called “middlings” with high silica contents. Commonly the primary challenge of the metallurgical task is to achieve high recoveries and iron concentrates with low impurities. To achieve this, several studies and industrial applications have shown success in this regard and not only in iron ores, but also in other minerals around the world. The study described in this paper attempts to describe some key aspects that helped develop an effective solution and list the benefits associated with this modern process design by using industry-proven technologies for minerals in Chile that have similar characteristics to the minerals of the iron belt in the United States.

Feb 1, 2025

By Carlos Maurício Fontes Vieira, Sergio Neves Monteiro, Diogo Neves Henriques

"This work evaluates the effect of incorporation of an ornamental rock waste into an industrial clayey body used for roofing tiles fabrication. Formulations with 0, 10, 20 and 30 wt.% of waste were prepared by replacing the sand in the industrial clayey body. The plasticity of the formulations was determined by the Atterberg limits. Specimens were fabricated by 18 MPa press-molding and then fired from 850 to 1100oC. The specimens were tested to determine the water absorption, linear shrinkage and three points bending flexural strength. The results indicated that the waste improves the extrusion performance of the clayey body by decreasing its plasticity. The use of the waste was beneficial to the water absorption and mechanical strength of the fired clayey ceramic at temperatures above 1000 ° C.IntroductionOrnamental rock is a natural resource available in the municipal area of Santo Antônio de Pádua and located 150 km from the city of Campos dos Goytacazes, northe of state of Rio de Janeiro, Brazil. Intense industrial activity related to ornamental stones, especially gneisses, is traditionally occurring in the region. After mining, the flagstone is submitted to sawing to obtain blocks and then, after a manual operation, the final products are small flagstones [1,2]. During the sawing operation, a sludge composed of water and fine particles of rock is generated. A monthly production of 1000 tons of ornamental rock waste is estimated to be produced at Santo Antônio de Pádua. The final disposal of this waste has brought serious environmental problems. Since most industries do not have an adequate sludge treatment, the waste is contaminating the soil and underground waters as well as obstructing rivers and lakes.Ceramic bodies industrially fabricated in the municipal area of Campos dos Goytacazes, 280 km from the city of Rio de Janeiro, are still empirically elaborated using a mixture of local clays. These clays are predominantly kaolinitic mineral, associated with high plasticity. Due to the excessive plasticity of the ceramic bodies, it is common to have dimensional defects in the final products after the drying and firing processes. Moreover, the kaolinitic structure and the presence of aluminum hydroxide confer a refractory behavior to the local clays. This impairs sintering during the firing operation. In the case of clay ceramics for civil construction, this results in greater porosity associated with elevated values of water absorption and low mechanical strength [3,4]. To avoid these problems, it is necessary to reformulate the ceramic body composition. The addition of both non-plastic materials to reduce plasticity and fluxes to condition the refractoriness is a possible alternative."

Jan 1, 2008

By Antonio Kodsy, Lutful Khan

A research was carried out to test the possibility of reducing the pullout resistance of metal sheet piles driven in clay soils using Electrokinetic (EK) conditioning. The hypothesis was applying an electric gradient for a certain period of time should reduce the adhesion between the clay soil and the sheet piles. Tests were conducted on bench scale thin stainless-steel metal plates embedded in pure kaolinite clay, and mixtures of kaolinite clay and sand. The pullout resistances were determined after 20, 40, and 60 minutes residence times of steel plates in the soils before and after EK conditioning under an electric gradient of 1500 V/m. In kaolinite clay, the pullout resistance showed linear reduction with the duration of EK conditioning and about 60 % reduction in pullout resistance was observed after 60 minutes EK conditioning. For the kaolinite-sand mixtures, the pullout resistances were reduced by about 70% and 80% for 20% and 30% sand contents respectively after 20 minutes EK conditioning and showed no significant improvement with the increase in conditioning duration. It was concluded that the proposed electrokinetic conditioning process could potentially reduce the pullout resistance of metal plates embedded in clay and clayey soils. SHEET PILE WALLS Sheet pile walls are typically used at waterfronts as retaining structures or during the construction phase to shore the soil and avoid collapse of the excavations. When used as permanent structures, sheet pile walls are not removed after the completion of the project. However, as temporary support, they are extracted after the completion of the project and reused. In pure clay soils the extraction processes often becomes a challenge requiring very large pullout forces which could damage the sheet piles. There is a research need for developing an efficient method of sheet pile extraction from clay soils addressing the issue of pullout force reduction. However, very few researches have been conducted regarding the extraction techniques of sheet piles and their economic effect on the cost of a project. In this study a novel method for reducing the pullout resistance of sheet piles in clayey soils using electrokinetic conditioning was explored. The hypothesis of this research is that the electrokinetic process in soil/water system, specifically electrophoresis and electroosmosis, could be used to loosen the sheet pile walls embedded in cohesive soil and hence reduce the required force of extraction. The aim of this study was to test this hypothesis through laboratory tests carried out on steel plates embedded in cohesive soil samples. The pullout forces of the steel plates before and after varied duration of electrokinetic (EK) conditioning were evaluated and compared. The process was also investigated for clay-sand mixtures.

Jan 1, 2019

By Remo Grandori

"INTRODUCTIONDouble Shield TBMs were introduced in the market in the early seventies with three main targets:• Increase the TBM performances in term of advance per day thanks to the ability to erect a segmental lining simultaneously with the excavation phase.• Be able to advance through unstable and disturbed rocks under the protection of the shields• Provide a finished tunnel by installing a precast lining as the TBM advance.In 2003 SELI developed the design of the Double Shield Universal (DSU) TBM as an evolution of the original Double Shield TBM design.This new TBM design was targeted to improve: the TBM capability to advance through squeezing/converging rock formations under high cover, the telescopic joint design (allowing by such to operate the machine in double shield mode in very weak rock), the capability of the TBM to investigate and treat the ground around and ahead of the tunnel face.In the same lapse of time Single Shield TBMs, originally utilized for soft ground tunnelling, extended progressively their range of application to mix rocks and finally to hard rock tunnelling with increasing performances.This also thanks to the substantial reduction in the installation time of the segmental lining ring that contributed to minimize the TBM stand by time between two consecutive boring strokes.Today the choice between the two types of TBMs needs to be carefully evaluated project by project since one type of TBM may “prevail” in certain geologies and diameters and vice versa.THE VISHNUGAD PIPALKOTI TUNNELThe Vishnugad Pipalkoti Tunnel is part of the 444 MW Vishnugad Pipalkoti Hydro Electric Project (VPHEP) on Alaknanda river in Uttarakhand (India).The Owner is the Indian electric company “Tehry Hydro Development Corporation” (THDC) and the World Bank finances the project.The Headrace Tunnel total length is 13.4 Km and a section of about 12,3km will be excavated by TBM by SELI Overseas (Italy) in subcontract to HCC (India) the General Contractor for the project. The TBM will be delivered ex workshop in March 2016 and it is foreseen to start boring in the second half of 2016.Figure 1 below shows the location of the project and the following Table 1 summarizes the geometrical characteristics of the TBM tunnel."

Jan 1, 2016

By Susan Fredholm, Randolph Kirchain, Jeremy Gregory

"Jurisdictions across the world have struggled to create and finance systems that can effectively collect and process electronics waste (e-waste). Many different system architectures have been proposed and implemented, but it is difficult for policy-makers and system architects to compare the costs and benefits of different systems, particularly when the systems operate in different contexts. This paper presents a systematic methodology that seeks to address this challenge and uses data from several existing electronics recycling systems across the world to illustrate its implementation. The methodology characterizes three main system characteristics: architecture (e.g., financing and collection methods), context (e.g., jurisdiction population, density, and wages), and performance, both economic and materials collection. A comparison of systems in Europe and North America with different system architectures and contexts illuminates the importance of using the methodology to discern the extent to which architecture and context drive system performance.IntroductionElectronic waste (e-waste) recycling offers several environmental benefits when processing is done responsibly. The controversy around e-waste recycling systems rarely debates such benefits; rather, it focuses on the characteristics of an effective system and whether benefits outweigh costs. Historically, the costs of recycling most electronics have outweighed the value of the scrap recovered. Thus, in the absence of legislation, e-waste recycling systems have been limited to private recycling of high-value waste with minimal consumer participation. E-waste recycling systems now exist in many locations worldwide including Asia, the European Union, Canada and the United States and the amount of related legislation continues to increase. Numerous approaches have been proposed including landfill bans, extended producer responsibility (EPR) and consumer advance recovery fee (ARF) funded recycling systems."

Jan 1, 2008

By Pedro Etchevarne, Santiago Margot, Oscar Baglivo, Roberto Musante, Daniel Costoya, Maria Soledad Oreggioni

Durante 2017, a operação do AF#2 da Ternium Argentina exigiu alterações da basicidade binária em uma ampla faixa entre 2.0 a 2.7 e no teor de MgO. Esta faixa de trabalho motivou o estudo das propriedades metalúrgicas do sinter e sua interação com outros componentes materiais da carga do Alto-Forno. Além disso, foi testado e analisado a influência de duas qualidades diferentes de granulado. Para entender os efeitos da composição química, um conjunto de testes de redução-desintegração foram desenvolvidos. Aliando com perfis isotérmicos (ISO 4696-1), perfis variáveis de temperatura e composição de gás, com intuito de simular a redução no AF. As propriedades sob alta temperatura também foram avaliadas por meio de ensaios de amolecimento e fusão, compondo a carga sinter, pelota e minério granulado. Utilizando amostras de sinter de diferentes basicidades e teores de MgO. Os resultados obtidos e sua influência no comportamento dos altos-fornos são analisados no presente trabalho.

Oct 1, 2019

By J. B. Gayle

Many investigators have reported studies of size distributions for particulate solids ; usually , these have involved the fitting of size distribution data to a particular mathematical function . Such studies are of unquestioned value and have contributed much worthwhile information regarding the breakage mechanisms for a variety of brittle materials . In connection with a Bureau of Mines study of the size distribution of coke , which has been subjected to the standard American Society for Testing Materials (ASTM) tumbler test , attention was focused on the relation between the 1 -inch tumbler index (usually considered to be indicative of the ability of coke to resist degradation by impact ) and the 1 /4 - inch tumbler index ( indicative of the ability to resist degradation by abrasion ) . Specifically , it was noted that for certain sets of data the correlation coefficients denoting the relation between these indexes were positive ; for other sets of data , these coefficients were negative . Preliminary consideration of this problem indicated that the usual interpretation placed on correlation coefficients was erroneous in this particular instance because the variables being correlated were necessarily related . The work described in this report was undertaken to clarify the interpretation of results of correlation studies for variables of this type .

Jul 1, 1960