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By Richard W. Smith

THERE are three distinct varieties of phosphate rock, in Tennessee, known commercially as: (a) the "brown" rock, which is the residual pro- duct of the weathering and natural concentration of certain phosphatic Ordovician limestones; (b) the "blue " rock, which is an unaltered phosphatic stratum of Mississippian or Devonian age; and (c) the "white" rock, which is the result of chemical replacement and deposition. Before 1894, South Carolina and Florida had supplied most of the phosphate of the United States, South Carolina leading until that date and Florida from then until the present time. In December, 1893, the blue phosphate of Tennessee was discovered almost simultaneously on Swan Creek, in Lewis County, by two independent parties-by one as the result of a careful and systematic search for a workable deposit of the long known kidney phosphate, and by the other through mistaking it for a "bloom" of coal. Leases were taken and, with further prospecting disclosing other deposits in the region, the development progressed as rapidly as 'could be expected without railroad transportation

Jan 1, 1924

By Richard Giffen, Boris CARO VARGAS, Terrence Carroll

"This paper takes an in-depth look at the $72 million design-build Norris Cut project, which includes the replacement of an existing 54-inch waste water sewer main to Fisher Island under the Norris Cut Channel. Tunneling through one of the country’s most unpredictable geologies created unique challenges in both the design and construction phases of the project. The paper presents the geotechnical and structural design considerations for the 100-foot deep secant piled TBM launch shaft in the highly permeable Fort Thompson formation limestone and sands. The structural design effort also included the design of the tremie slab, thrust wall and design of the largely unreinforced launch shaft to resist asymmetric loading from partial ground freezing. The retrieval shaft was designed as a deep soil mixed shaft and is thought to be the deepest soil-mixed shaft in Miami. From a construction perspective, this paper discusses the unique challenges of building two shafts with two different techniques and will compare some of the constructability aspects, costs and equipment schedule-considerations related to the use of two separate techniques. INTRODUCTION Nicholson Construction Company (NCC) was awarded a $72.1 million Design-Build contract to replace an existing force main from the Virginia Key Central District Wastewater Treatment Plant (CDWWTP) under the Norris Cut Channel to Fisher Island. The location of the project is shown in Figure 1. The project involves replacing an existing 54-inch diameter pre-stressed concrete sewer force main with a 60-inch diameter fiberglass force main. Arup USA, Inc. (Arup) is the lead designer for Nicholson on this design-build project. Arup is providing design services for the TBM launch and retrieval shafts, segmental tunnel lining, the fiberglass pipe, and the horizontal directional drill component. Miami-Dade Water and Sewer Department currently owns and operates the existing 54-inch sanitary force main that transmits sewage collected from Miami Beach and Fisher Island to the CDWWTP for treatment and disposal. The existing force main was subject to a condition assessment in December 2011 which revealed structural deficiencies in the pre-stressed concrete pipeline."

Jan 1, 2016

By P. K. Hofmeyr

Traditional fire assay dates back over 3000 years and has changed very little over that time. The only improvement is to replace the gravimetric finish with dissolution of the Precious Metal bead followed by AA or ICP analysis of the solution. The newly developed FIP A (Fast In-line Fire Assay) method allows full automation of the fire assay process from sample preparation to spark analysis of the Pb button. This results in fully quantitative analyses for Pt, Pd, Rh, Ru, lr, Au and Ag in typically less than an hour after a sample is entered into the system. Detection limits are theoretically Pt 0.08 ppm, Pd 0.002 ppm, Rh 0.002 ppm, Au 0.08 ppm and Ag 0.002 ppm but in practice the lower measurable limits are about double these figures. Few opportunities have been available to present data obtained using the FIFA system as all FIFA laboratories have been in the domain of a Pt mining company which prefers to keep all Pt analytical matters confidential. However, IMP has recently participated in the round robin exercise to establish recommended values for a new series of Merensky Reef and UO-2 Layer reference materials produced by African Mineral Standards. The precision of the results was excellent being on average Pt 2.05%, Pd 1.25%, Rh 4.08% and Ru 4.94% being expressed as Relative Standard Deviation. The excellent precision is a reflection of the efficient collection of POEs in the Pb buttons and the homogeneity of the Pb buttons. However, the accuracy was not as good. The poorer accuracy is interpreted as the calibration of the spectrometer not being as good as desired due to the difficulty in acquiring a suitable range of standards with reliable recommended values for the PGEs. The most recent spectrometer was calibrated with the greatest care and produced slightly better results for Pt, Pd and Rh and slightly worse for Ru.

Jan 1, 2014

By Eugene Fry

The Huber-Rydalch manganese property is in the Erickson mining district of Tooele County, Utah. The district covers the southern part of Simpson Mountains, a block rising abruptly above the surrounding desert floor (fig. 1). The Ruber-Rydalch deposits and other deposits in the Simpson Mountains manganese area were examined by Bureau of Mines engineers during 1940 and 1942 under the strategic minerals program. J. T. Pardee visited the district briefly in 1918. A. E. Granger and A. F. Shride, of the Federal Geological Survey, mapped the geology of the area in 1942 and 1943. The manganese deposits occur as veinlike masses in brecciated fault zones that traverse Cambrian and pre-Cambrian quartzite, quartzite conglomerate, and phyllite. The deposits now exposed near the surface represent the oxidized portions of primary mineralization originally containing rhodochrosite and rhodonite associated with quartz and calcite and small quantities of pyrite, galena, sphalerite, and chalcopyrite. The oxide ore is composed of manganite, pyrolusite, psilomelans, and wad in a gangue of quartz, calcite, and brecciated quartzite.

Jan 1, 1949

This paper describes the back analysis of the Pavoncelli tunnel, an hydraulic tunnel which was excavated between 1904 and 1915 in South of Italy and experienced severe damages during the 1980 Irpino-Lucano earthquake. A numerical simulation which is intended to study the behaviour of the tunnel during this seismic event is presented, also accounting for the swelling phenomenon that took place during and after construction.

May 1, 2009

By Andrea Lisjak

The mechanical behaviour of Opalinus Clay, an indurated over-consolidated argillaceous rock, is heavily influenced by the presence of preferably oriented bedding planes. The objective of this study is to illustrate a new modeling approach aimed at capturing the bedding-induced anisotropy of Opalinus Clay as observed in the laboratory and in situ. The combined finite-discrete element method (FEM/DEM) is employed as the main simulation tool. FEM/DEM is a numerical method that models material damage processes by explicitly considering fracture nucleation and propagation. A transversely isotropic elastic constitutive law is used to account for different elastic property values in the direction parallel and perpendicular to the layering, while strength anisotropy is captured using a directional cohesive fracture model. Quantitative calibration and validation of the model is based on laboratory results of indirect tensile tests and uniaxial compression tests. Emergent strength and deformation properties, together with the simulated damage mechanisms, are shown to be in good agreement with experimental observations. Preliminary results relative to the analysis of a circular tunnel show that the approach is able to reproduce the main Excavation Damaged Zone (EDZ) formation mechanisms as observed in the field.

Jun 1, 2012

By J. A. Pontius

The Cresson Deposit is located in central Colorado within the historic Cripple Creek Mining District. The deposit has moved from its initial discovery in 1990 to full production in less than five years (current reserve nearly two million ounces). This accomplishment required a great deal of cooperative teamwork between the exploration, development, permitting and corporate groups. Nowhere was this cooperation more evident than in the construction of the geologic block model. The detailed modeling of gold and its metallurgical characteristics formed the foundation upon which critical financial and design decisions were based.

Jan 1, 1995

By Rainer Fackert

3D-Measurements for slabs and heavy plate are now available and close the gap in the production chain. The measuring systems described in this presentation must be seen as high-tech solutions in the field of casting and rolling technology. The measuring systems were developed taking into consideration the harsh casting and rolling mill environment in which they are to be used, with the aim of achieving high operational reliability and eliminating disturbances. Interconnected quality management systems enable optimization across the complete production process. New limits are being defined constantly for all these developments. What is technically feasible today becomes normal practice tomorrow, and will probably be replaced by completely new technologies the day after.

Aug 16, 2017

By B. Leonard

As of November 2012, the Alberta government listed 53 oil and gas, oil sands, and mining construction projects either proposed or currently under construction. These industrial plant construction projects have an estimated value greater than 105 million dollars. A common construction method employed for industrial plant projects is fast-track construction, which is used to reduce construction time. Contractors begin fast-track construction with highly generic scheduling information. This high level schedule turns into a lower level schedule as more detailed information becomes available. From a contractor?s perspective, a challenge faced using fast-track construction is the visualization of generic and constantly changing project schedules. This paper discusses the use of a Plant Information Modeling (PIM) system, designed to create a 4D animation to visualize project schedules for fast-track industrial plant construction projects. The proposed PIM system creates a modified project schedule by obtaining specific information from a generic construction schedule. Obtaining the information involves grouping schedule activities in accordance with the level of detail in a 3D model, and the level of detail in a project schedule. The modified project schedule is then used in conjunction with a 3D model to simulate the construction sequence in the form of a 4D animation. This allows for 4D visualization of project activities, installation dates, and crane movements. Furthermore, as engineering reaches completion, the PIM system creates a streamlined channel for schedule information updates to be easily uploaded into the model for a more accurate 4D visualization. Through analyzing a nonmodular construction case study, this paper discusses the successes and benefits of the PIM system for 4D visualization, such as increased productivity, shortened construction time, increased constructability, and decreased field costs.

Aug 1, 2013

By E. Ghali, B. Arsenault

Aluminum alloys play an important role in the manufacturing of air and ground vehicles. However, with such alloys, corrosion damage is often found on structural components subjected to fatigue loading. The alloying provides large benefit in terms of the high specific tensile strength (ultimate strength/density ratio) to the aluminum alloy but causes the aluminum alloy to be more sensitive to localized corrosion due to complex microscopic heterogeneities such as secondary phases. This paper investigates thermal spray coating namely arc spraying to evaluate the protection against environmentally assisted cracking (EAC) and localized corrosion on Aircraft structural 7075 T651 aluminum alloys. In particular, EAC and pitting corrosion at the interface coating-substrate are a challenge for thermal spray protective coatings on aluminum alloys under cyclic load and immersion. To address these issues, different surface preparation techniques prior to arc spraying were considered such as chemical de-oxidation, laser ablation, shot peening and grit blasting. Results indicate that surface preparation and improved coating process parameters play an important role to provide a coating conferring a protection against both localized corrosion and EAC.

Jan 1, 2006

By S. V. Ulianov, A. Y. Senchenko, A. A. Shvets, A. V. Aksenov

Development of an efficient technology to process complex ores containing gold and antimony as well as silver is described in the paper. The results from the testwork aimed at the valuables recovery by means of flotation are presented. A process sample of antimonite gold-bearing ore was studied in TOMS institute aiming at development of a technology to process such an ore with generation of antimony concentrate and sulphide gold-containing concentrate. Material composition study indicated that the ore included 5.3% of sulphides: arsenopyrite – 2.4%, pyrite -2.4%, and antimonite – 0.5%. Gold is present as an isomorphic dissemination in arsenopyrite. At sighter testing stage a direct selective flotation flowsheet was chosen to process the ore. Antimonite flotation was activated due to addition of lead nitrate. A single cleaning of a rougher flotation concentrate resulted in antinomy concentrate with 30% Sb content and 71% recovery. Au recovery into antimony concentrate did not exceed 1%. Sb flotation tailings were used to float the remaining sulphides and gold. The resulted sulphide concentrate was characterized by Au content of 20 g/t at about 80% recovery, arsenic content - 10% at ~80% recovery, and sulphur content - 18% at ~81% recovery. The sulphide concentrate can be forwarded to further processing aiming at gold recovery. Given that the concentrate is highly refractory it should be pretreated (bacterial or pressure oxidation, Albion process) prior to cyanidation in order to liberate gold from sulphides. The proposed technology allows one to solve the problem of precious metals recovery from antimonite ores.

Jan 1, 2016

By Zay Jeffries

A SURVEY of rare metals and minerals for the past year places uranium as one of two partners, the other being the neutron, in what historians will probably say is the greatest discovery in physics at least during the year and probably for a consider- ably longer period. The uranium atom has been made to divide into parts somewhat after the style of reproduction of the amoeba. When an amoeba divides into two parts, however, it produces two amoebae substantially alike and each substantially like the parent: furthermore, there is no considerable change of energy when this happens. When the uranium atom divides it yields other atoms such as barium and krypton with the complete destruction of the original uranium atom but with the liberation of a tremendous amount of energy. This will be discussed more at length later.

Jan 1, 1940

By K. J. Boser

"Medium Voltage (MV) metal clad switchgear is referred to as the voltage class from 2.4 kV to 38 kV. Technological advances in circuit breaker designs over the last 20 years have given rise to retrofit options in lieu of complete replacement for older outdated circuit breaker technology. This paper examines the four MV breaking techniques that exist in industry and investigates various retrofit versus refurbish options for switchgear modernization and life extension. IntroductionThe life extension and upgrade of medium voltage circuit breakers is becoming an increasingly important issue in today’s modern industrial facilities from both a reliability and safety standpoint. Unscheduled downtime, loss of production, and plant safety issues are just some of the concerns that need to be addressed with aging switchgear. A thorough examination of the available breaking mediums allows an informed decision to be made when the time comes to assess equipment performance. If you look back over the history of medium voltage breakers, you will find that there have been four breaking techniques developed and widely used:• air magnetic;• minimum oil;• vacuum; and• SF6.Many facilities that were constructed 25 to 30 years ago relied on air magnetic or minimum oil circuit breakers in their distribution systems. At the time, these were the only “tried and tested” options and they afforded good service. Since then, however, newer technology has given us the vacuum and SF6 mediums which have both proven their reliability and monopolized the market. All the methods have their particular place in industry and what follows is a summary of the advantages, disadvantages, and chronological development of each breaking technique."

Jan 1, 1998

By M. K. Roberts

The approximately 2800 Ma old Ventersdorp Contact Reef is a unique Witwatersrand orebody, from which about 6% of the world?s gold production is derived. A major portion of this production is mined at depths exceeding 2500 m and deepest levels of mining are at about 3600 m. The orebody?s hangingwall consists of volcanic rocks. This differs from the older Witwatersrand orebodies, which have quartzitic hangingwalls. The thickness of the Ventersdorp Contact Reef is generally about 1.20 m, but is highly variable, at an average dip of about 18°. A pronounced unconformity beneath this orebody is also expressed by varying footwall rock type characteristics and frequent rolling of the reef plane. These rolls follow topographic variations of the palaeo-surface. More geological than rock mechanics studies were performed on the Ventersdorp Contact Reef prior to 1992. Recently, however, a multidisciplinary team comprising various rock engineering and geological disciplines has delineated geotechnical areas by a novel technique. Geotechnical areas are defined by distinct footwall/hangingwall rock assemblages. The presence of three footwall and two hangingwall rock types results in the definition of six geotechnical areas across a distance exceeding 60 km, including about 10 gold mines. Distinct rock mass behaviour has been documented in three of the six geotechnically defined areas. Different rock mass behaviour is expressed by features such as mining-induced fracturing, closure rates, fall of ground characteristics and seismic character. Some geological features override the rock mass behaviour as defined for the individual geotechnical areas. These are undulations of the orebody or the frequency, characteristics and attitude of major discontinuities. It is concluded that the concept of geotechnically subdividing orebodies is not only important for facies delineation and the associated grade, but also needs to be considered for safety aspects, in determining factors such as the appropriate support to be employed.

Jan 1, 1999

By Vladimir Mindin

This paper presents results of thermodynamic investigations and experimental' studies of some essential for pyrometallurgy of sulfide concentrates topics. Among them: 1. Thermodynamic simulation and experimental investigations of roasting process, 2. Thermodynamic investigations of sulfur dioxide off-gases treatment technologies. 3. Investigations on "Mind in -Kiknadze" effect of suppression of sulfur dioxide formation during sulfide concentrates roasting in the vapor containing atmosphere. 4. Thermodynamic simulation and experimental investigations of sulfide concentrates and manganese containing materials co-roasting processes. Some essential aspects of thermodynamic simulation techniques are also discussed.

Jan 1, 1998

By Z. Y. Lan

Bioleaching of marmatite with various mixed cultures of microorganisms was investigated. The experiments were carried out in shaking flasks with iron-free nutrient and the pulp density of 10% wt/vol at the temperature of 30?. The results show that zinc is preferentially leached before iron. The leaching rate of zinc with the mixed culture of Acidithiobacillus ferrooxidans, Acidithiobacillus thiooxidans and Leptospirillum ferrooxidans is 62% in 18 days. The leaching rate of zinc with the mixed culture of Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans is nearly the same as that with the mixed culture of Acidithiobacillus ferrooxidans and Leptospirillum ferrooxidans (45% versus 50%). SEM and EDX analysis of the leaching residues indicate that a solid product layer composed of iron sulfide, elemental sulfur and jarosite accumulates in the mineral surface and becomes a barrier to the dissolution of marmatite. The bioleaching of marmatite follows the shrinking core product layer model. When the product layer increases and becomes insoluble, the leaching rate is controlled by the diffusion through the product layer and slows down. When the product layer decreases or becomes a porous layer, the leaching rate is controlled by chemical reaction and enhanced dramatically.

Jan 1, 2014

By Renan Bueno Wojciechowski, Yukio Shigaki

The quality of flat rolling process depends highly on multiple factors such as applied forces, materials involved for both strip and rolls, roll geometry and its positioning. To calculate the strip shape, a mathematical/numerical model can be applied, showing the final product and how the equipment behaves when changing some parameters. This is usually a time-consuming task for both user and computer, especially when it involves thin and hard strips. By coupling a quick rolling load calculation method as Bland-Ford and Finite Element Method (FEM) for roll stack deformation, it is possible to create an accurate and user-friendly rolling simulator. This paper presents the improvements done in the 3D FEM/multi-slab method and its actual capabilities by simulating two cases of a 6-High rolling mill. Different analysis in this equipment can be easily done in about 10 minutes by using the developed an electronic spreadsheet program interface and the folder generated with relevant results and logs. An operation manual and a commercial FE program plugins were made to aid construction of a completely new model. The code was created in a modularized way to assist the application of this simulator for other operational conditions.

Oct 1, 2019

By Gil Ribeiro Vilela Neto

Na busca por se tornar cada vez mais sustentável, a indústria mineral vem recorrendo às soluções tecnológicas que minimizem o impacto ambiental gerado pela disposição dos rejeitos resultantes dos processos de beneficiamento de minérios. Neste cenário, umas das soluções é a aplicação de tecnologias de separação sólido-líquido com o objetivo de maximizar o desaguamento dos rejeitos e, consequentemente, diminuir o volume ocupado por eles quando dispostos e aumentar a recirculação de água. Este trabalho tem como objetivo, determinar a influência da concentração de sólidos em polpas de rejeitos denominados de “lamas” no desempenho do espessamento e a determinação da concentração de sólidos ótima para atingir o melhor desempenho do espessador.

Aug 16, 2017

By Paulo Henrique da Silva Gomes

A melhoria contínua dos processos é fator fundamental para o sucesso do negócio. Avaliar as melhores práticas e propor soluções que equilibrem os custos e o uso consciente dos recursos naturais transformará o negócio sustentável e sólido. Com esse ideal foi realizado um estudo de viabilidade econômico-financeira e operacional para a implantação de uma nova metodologia na gestão de paletes do negócio cimentos. O estudo objetivou a implantação de um sistema integrado de paletes que permitiu uma gestão eficiente do negócio, sendo possível controlar os índices de paletes disponíveis para a produção, paletes em reparo, paletes sucateados e balanceamento de estoque entre fábricas e centros de distribuição, contribuindo para uma redução da necessidade de compra de novos paletes. Além disto, propôs também a implantação de uma oficina de paletes dentro das fábricas garantindo um melhor processo de triagem de paletes que contribuiu para a redução do tempo de parada das linhas produtivas por problemas de paletes fora de padrão operacional.

Aug 17, 2017

By Tiago Seixas Bittencourt

A carga metálica do Forno Elétrico a Arco (FEA) representa bem mais que a matéria prima da rota semi integrada, representa o ponto de equilíbrio financeiro de uma operação siderúrgica sustentável. O fiel da balança econômica de uma operação baseada em um FEA baseia-se no custo do emprego metálico. Deste modo é razoável pensar que, escolher a combinação de sucatas que irá compor o mix de metálicos que abastecerá o FEA é uma tarefa que vai além das limitações técnicas do fenômeno de fusão e refino primário no referido reator. O emprego de resíduos metálicos diversos representa uma medida de sustentabilidade para a indústria siderúrgica, tanto sob a ótica ambiental, dado o reaproveitamento do resíduo, como na perspectiva econômica, haja vista a redução substancial nos custos de transformação. Testes realizados no FEA da CSN UPV possibilitaram avaliar os aspectos positivos e negativos do emprego de um resíduo metálico descartado durante a produção de cimentos. Os resultados encontrados demostram que, sob a perspectiva técnica, os aspectos positivos sobressaem aos negativos e, portanto, O FEA representa uma ótima alternativa para o consumo sustentável do referido resíduo. Uma avaliação econômica aponta uma redução de custo do emprego metálico da ordem de 17%.

Aug 15, 2017