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By Maíra de Paula Pereira de Lucena

Revestimentos de conversão nanocerâmicos são obtidos pela imersão de peças metálicas em soluções contendo íons de titânio, zircônio, cério entre outros. Esses revestimentos vêm sendo estudados como uma alternativa a outros processos de conversão que possuem inconvenientes ambientais, como a cromatização e a fosfatização. No presente trabalho foram formuladas diferentes soluções a base dos ácidos hexafluorozircônio e hexafluortitânio para a deposição de revestimentos nanocerâmicos sobre substratos de aço galvanizado. O objetivo é mapear os efeitos dos parâmetros de processo de obtenção do revestimento quanto ao desempenho contra corrosão. Os parâmetros estudados foram a concentração, o pH e o tempo de imersão nas soluções formuladas. Para avaliar os revestimentos obtidos foram realizados ensaios eletroquímicos de espectroscopia de impedância complexa. Os resultados indicam uma forte interação entre o pH e a concentração dos ácidos em solução e que concentrações mais baixas geram uma proteção mais eficaz O melhor conjunto de parâmetros foi para menor pH, concentração e tempo de imersão.

Aug 7, 2018

By Marcos Paulo Kohler Caldas

Após a edição da RoHS Directive 2002/95/EC, diretiva que entrou em vigor em 1º de julho 2006 proibindo a utilização de seis substâncias perigosas: chumbo, mercúrio, cádmio, cromo hexavalente, bifenilos polibromados e éteres difenil-polibromados, fabricantes de equipamentos eletroeletrônicos passaram a utilizar soldas livres de chumbo (lead free) para montagem de suas placas de circuito impresso. A SAC 305 é um tipo de solda muito utilizada pelas empresas fabricantes de placas de circuito impresso. O presente trabalho visa caracterizar este tipo de solda verificando sua composição e identificar se a mesma se encontra livre de elementos perigosos ao ambiente. Avaliou-se a extração de metais como Ag e Sn através de digestão ácida em água-régia e rota HNO3 a temperatura ambiente. A composição do licor lixiviado foi caracterizada por espectrometria de emissão óptica com acoplamento de plasma induzido (ICP-OES). Os resultados indicam que a solda SAC 305 atende a RoHS, possui 2,7% Ag, 96,4% Sn e 0,9% de outros metais e a melhor rota para extração de Ag foi a HNO3 e para Sn foi a água-régia.

Aug 7, 2018

By Ana Paula de Matos Silva

A recuperação de metais presentes em equipamentos eletroeletrônicos tem atraído interesse em virtude de novas e diferentes tecnologias que visam a reutilização desses elementos químicos em novos processos produtivos. A recuperação de prata de placas de circuito impresso na forma de nanopartículas é uma alternativa para reutilização deste metal nobre. Este trabalho teve como objetivos: recuperar a prata presente em placas de circuito impresso e separar a prata dos demais metais através de rota hidrometalúrgica. A rota hidrometalúrgica para recuperação da prata envolveu a lixiviação em meio ácido a 75ºC, por 18 horas. Após o processo de lixiviação a prata será isolada dos demais metais através de rotas hidrometalúrgicas. A composição do licor lixiviado foi caracterizada por espectrometria de emissão óptica com acoplamento de plasma induzido (ICP-OES). Os resultados indicaram a possibilidade de recuperação de 96,6% de prata.

Aug 8, 2018

By Afonso Garcez de Azevedo

As primeiras argamassas utilizadas em construções pelo homem continham em sua composição, materiais argilosos. Porém, por ser um material com muitas cargas elétricas livres, as argilas reagem constantemente com a água, ocasionando grande variação linear que acaba causando fissuração nas argamassas feitas com esse material. Assim, para solucionar esse problema, passou-se a utilizar cal hidratada no lugar dos materiais argilosos. Dessa maneira, mesmo não sendo composta por argila, a argamassa mantém sua trabalhabilidade. Nesse cenário, o presente trabalho teve como objetivo balancear estequiometricamente a cal hidratada e as argilas estudadas, para utilizar essas quantidades em argamassas para revestimento, barateando assim o material. Para encontrar esse balanceamento estequiométrico calculou-se a massa molar para um mol de cal hidratada e para um mol teórico de argila. Assim foram estipuladas algumas proporções possíveis de balanceamento da equação de reação cal+argila. Além disso, foram confeccionados corpos de prova, variando as quantidades de argila e cal, para realização de ensaios de capilaridade, a fim de comprovar a eficácia dos resultados encontrados no balanceamento teórico.

Oct 30, 2017

By R. Bryce, T. J. Doughty, K. Stoll

Sulfate-impacted mine waters are under regulatory scrutiny to reduce total dissolved solids (TDS). There are several options to reduce TDS. One option is transforming the soluble sulfate into insoluble ettringite. The Water Company LLC (TWC) patented a process for sulfate removal through ettringite formation by reacting directly with metallic aluminum. Freeport-McMoRan (FMI) and TWC have collaborated to design, build and operate a 10-gallon-per-minute (gpm) ettringite pilot plant to establish reagent consumption, plant availability and full-scale design criteria. Using metallic aluminum as the primary aluminum source for ettringite precipitation eliminates the addition of other ions, resulting in significant demineralization. The pilot plant achieved greater than 98% water recovery, greater than 90% reagent efficiencies and maintained reactor sulfate levels below 250ppm. BACKGROUND Ettringite is a hydrated calcium, aluminum, sulfate mineral with the following formula: Sulfate-impacted mine waters are under regulatory scrutiny to reduce total dissolved solids (TDS). There are several options to reduce TDS. One option is transforming the soluble sulfate into insoluble ettringite. The Water Company LLC (TWC) patented a process for sulfate removal through ettringite formation by reacting directly with metallic aluminum. Freeport-McMoRan (FMI) and TWC have collaborated to design, build and operate a 10-gallon-per-minute (gpm) ettringite pilot plant to establish reagent consumption, plant availability and full-scale design criteria. Using metallic aluminum as the primary aluminum source for ettringite precipitation eliminates the addition of other ions, resulting in significant demineralization. The pilot plant achieved greater than 98% water recovery, greater than 90% reagent efficiencies and maintained reactor sulfate levels below 250ppm. BACKGROUND Ettringite is a hydrated calcium, aluminum, sulfate mineral with the following formula: Ca6Al2(SO4)3(OH)12•26H2O Ettringite readily precipitates in high pH water and by doing so, removes sulfate from impacted waters. The SAVMIN process, piloted in South Africa, is one method to produce ettringite. In this process, aluminum hydroxide is the aluminum source. The Cost Effective Sulfate Removal (CESR) process is similar to SAVMIN, but uses a proprietary aluminum source instead of aluminum hydroxide. Outotec and Veolia also have their own versions of the process using their specialized process equipment. TWC patented a version of ettringite precipitation using metallic aluminum as the aluminum source for ettringite formation. The benefit of using aluminum metal is that no additional ions are added to the process. At high pH, the raw aluminum corrodes in water causing hydrogen gas generation as the water is chemically reduced. This reaction is shown below:

Jan 1, 2019

By J. C. Marchand, M. A. Berube

"L'objectif principal recherché lors du broyage d 'un minerai est de libérer adéquatement ses valeurs utiles en vue de leur concentration ultérieure. La pratique courante consiste à tenter d'obtenir un produit de broyage d'une granulométrie constante. Malheureusement, les propriétés texturales des minéraux utiles varient naturellement dans un gisement et une telle stratégie n'entraine pas toujours pour ces minéraux un degré de libération constant. Pour un rendement optimal du procédé de concentration, cette variable très importante doit donc être périodiquement vérifiée.Jusqu'à maintenant, la plupart des études de libération des minerais se font en examinant des sections polies de particules du minerai broyé. Le GRAAIM a récemment assemblé un système modulaire d'analyse d'images qui servira en grande partie à des mesures automatiques du degré de libération des minéraux. Le système s'avère relativement peu coûteux comparativement à la plupart des analyseurs de texture conventionnels si l'on considère que plusieurs de ses composantes, par exemple le miniordinateur, sont utilisées à une foule d'autres applications, et il permet de plus une grande souplesse d'utilisation puisque l'on a qu'à construire des algorithmes de mesure et de calcul en fonction de l'objectif recherché. Des programmes particuliers permettant des études automatiques de libération sur des sections polies de particules ont ainsi été élaborés. Ils permettent également des mesures de teneurs et de distributions granulométriques apparentes des particules. Des résultats obtenus dans le cas de minerais de fer sont brièvement présentés afin d'illustrer la technique."

Jan 1, 1983

By Matthew Clay, Colin Chambers, Susan Hookham

Opencast (quarries) and underground mines around the world use blasting methods to mine valuable ore. Traditional blasting systems use technologies such as electric delay detonator systems (developed in the 1950s) and non-electric detonator systems (developed in the 1970s) to initiate a detonation train to blast rock more effectively, and so retrieve valuable product more efficiently. However, the lack of precise control over blast timings with these approaches can result in undesirable outcomes such as significant flyrock, excessive ground vibration, uneven grade of rock and misfires (in which sections of the blast can remain unfired). The development of Electronic Initiation Systems (EIS), first used in the 1990s, introduced a higher level of control over the blast. These systems greatly reduce the negative issues associated with blasting. However, this precision introduces complexity, and with this complexity comes difficulty in demonstrating the predictability, safety and reliability of such systems.

Jan 1, 2017

By Roberto Folchi, Hans Wallin, Mara Battocchio

An understanding of explosives science and technology, and the competence to harness it is central to maintaining Explosives capability, national security, and in sustaining a competitive industry. A consequence of eroding this competence is the increased likelihood of explosives accidents. These are often catastrophic as demonstrated by accidents in Nigeria, Russia, Toulouse and Enschede. In addition to the serious loss of life there was the very significant damage to houses, domestic and industrial infrastructure and to the environment at a cost of many millions of Euros.

Jan 1, 2013

By David, Levinger

THESE observations of the metal-working industries of Europe are based on a three months' tour of eight countries of Europe, in which 75 industrial establishments were visited in England, France, Germany, Belgium, Holland, Italy, Austria and Switzerland during the summer of 1927. Since the Western Electric Co. is a large consumer of copper and brass, these industries were of particular interest and differences in practices were of keen interest to us.

Jan 1, 1928

By James H. Taylor

"Titanium is a widely distributed, dark grey metal1ic element found in small quantities in many minerals. It has no important uses." Happily, this early quotation proved to be wrung; titanium has, on the contrary, found a large number of very important uses. The error in the 1926 quotation illustrates the problems associated with forecasting the future development of any metal. 'The paper will nevertheless attempt to estimate what will happen to the European titanium industry over the coming decade with slightly more accuracy. It was not until 1955 that anything other than pilot plant facilities were installed in Europe. In 1955 IMI's plant in England, two plants in Germany, one in France and one in Sweden came into operation. All the companies associated with titanium installed melting furnaces but only IMI Titanium has forging and rolling facilities devoted solely to the production of titanium. The other firms rely on the use of equipment of their parent steel companies for processing the me1 ted titanium ingots.

Jan 1, 1982

By M Donatelli, E Grazio, A Heissenberger

The distribution of a contaminant in a bulk mass greatly influences the effectiveness of sampling procedures. Most currently used sampling guidelines for genetically modified organisms (GMO) testing have stringent distribution requirements. Specifically, all these protocols are based upon the assumption that GM material, if present, is randomly distributed. Yet, assuming randomness is risky because the applied sampling plan may not provide an accurate estimate of the content of the contaminant. Despite the general consensus that an evaluation of the possibility of non-random distribution of GM materials within lots is a pre-requisite for the definition of effective sampling protocols, no experimental data on the distribution of GMOs in kernel lots are available anywhere in the world. Additionally, to date there is no distribution-free statistical model to estimate sampling errors, thus making the theoretical definition of optimal sampling technique impossible when randomness cannot be assumed. Here we present preliminary results of the KeLDA project, which is the first study investigating the distribution of GM materials in large soybean lots imported within the European Union. The extensive variability of GM content, observable both within and among soybean lots, indicates that heterogeneity issues cannot be overlooked when defining sampling strategies for large lots of particulate material and that randomness cannot be assumed a priori. A new statistical model free from any distribution assumptions, developed in order to estimate the sampling error associated with different sampling protocols together with the risk of false-negative results, is also presented. The new model, which is applicable to any consignment of particulate material with respect to any kind of contamination, presents two novelties: first, freedom from any distribution assumption; second, the possibility of estimating the magnitude of the sampling error associated with different sampling protocols as a function of specific distributional properties.

Jan 1, 2005

When the Middle Ages were drawing to an end and Rotterdam, then still a small fishing port, began to extend its trade relations to continental ports handling general cargo, a development was initiated which was to give Rotterdam a predominant position in maritime traffic in Europe 300 years later. Despite many setbacks and the silting up of the mouths of the Rhine and Meuse rivers, the port experienced a new rise towards the end of the previous century after the dunes at Hook of Holland had been cut through as planned by Dutch engineer Caland. With its favourable location in the mouth area of the Rhine and a hinterland opened up by waterways it was merely a matter of the city council pursuing a far-sighted policy to make the best of these natural advantages. Thus new port installations were erected on the southern bank of the Meuse in the first quarter of this century, which were expanded in the course of the subsequent decades. The New Waterway became the main artery for industrial enterprises, in particular oil industries, which sprang up along its banks (picture 1). Whereas 30 years ago Rotterdam's Waalhaven, with its new jettees for general cargo and mainly bulk goods, was still one of the most modern terminals, the growing size of ships, which increased by leaps and bounds for tankers, in particular towards the end of the 'fifties, necessitated much larger harbour facilities built further and further towards deep water.

Jan 1, 1972

By Carlos Almeida, Bruno Matias, Stef Kapuskiak, Eduardo Silva, José Miguel Almeida, Alfredo Martins

Underwater intervention operations have been supported by robotic systems such as remotely operated vehicles (ROV) for a long time. In particular challenging scenarios such as the deep sea, the use of ROV systems for environment awareness is in fact the main tool of choice. With the technical advances in autonomous robotics, there is an increased effort in substitute ROVs whenever possible for autonomous underwater vehicles (AUV). These systems don't have tether and thus provide large advantages from the operations and logistic point of view. However the limited options for underwater communications render them impracticable for many tasks were real time environment awareness and direct human control is needed. Emerging applications in underwater mining, both at sea [1] and in inland flooded mines [2] pose additional requirements in terms of operation support needs and environment restrictions. Two main tasks are to be addressed by assisting robots in these underwater mining operations: providing adequate environment awareness for human operators and obtain precise realtime 3D environment modelling (particularly relevant for the mining planning). The use of ROVs with umbilical cable, has in this case large limitations due to the nature of the mining cutting (performed by dedicated systems) that limit manoeuvrability and pose high risk of cutting the cable or damaging the vehicle. In this paper we present EVA (Exploration VAMOS AUV) an innovative hybrid ROV/AUV system developed for operations support in inland underwater mining operations. This robot is always operated without tether, and the can be used in a wireless ROV tele-operation mode using very short range high bandwidth underwater communication systems and in autonomous AUV mode.

Jan 1, 2018

By Lawrence D. May, Harry Mudgett

"In the course of developing a new industrial process, information produced at the Research and Development (R&D) stage is critical to determining the technical and economic feasibility of the project. Understanding the fundamental operating parameters for each unit operation in a flowsheet typically comes from historical knowledge of similar systems or by technical development through a robust research program. This approach holds true for processes incorporating fluidized-bed technology. In this paper, the authors will present a practical approach for performing a research study that will allow a process owner to determine if the concept of using a fluidized-bed system can become a reality. Included are discussions of key steps required at each level of the R&D program, and the critical information required for advancing the project to the next stage.IntroductionThe conduct of a research and development program typically starts with a process owner identifying a new industrial need or modification to an existing operation. The owner can pursue this need through multiple routes, including initial in-house development, coordination through an engineering firm, contacting suppliers of key equipment envisioned for the process, or through direct contact with research and development organizations. Where and when the project is conducted is as variable as the number and types of owners who pursue them. Factors that can influence the decision of where to conduct a research program can include the type of process desired, the scale and scope of the project, the location of the project site relative to the R&D options, the experience, capability, and availability of the potential research sources, and the costs to conduct the program. Often, the owner may choose a combination of the available resources to achieve their objectives. In the end, the owner's choice should be based on a thorough understanding of their goals and objectives for the program, and a good understanding of how to measure success while achieving those objectives. Herein, the authors will describe the methods we have typically used to develop the information an owner needs to make an educated decision for investing in a new or modified process."

Jan 1, 2014

By Arthur L. Crawford

PLAGER gold is perhaps the most difficult of the common mineral deposits to evaluate. Not only are the erratic pay streaks a source of never-ending uncertainty, but the spotty distribution of the gold in iso¬lated nuggets is a perpetual source of error and disappointment to the sampler. Experienced engineers have long realized this difficulty and have been wary in predicting assay values except in the most general terms, and then only after extensive and usually expensive sampling. During the past year I have had the opportunity of checking a number of gold placers, and from the results obtained I believe that the microscope may be employed to advantage in placer sampling.

Jan 1, 1933

By Jon Huff, Jeffrey Donville, Hannah Iezzoni, Dan Stevenson

Occasionally, in the design of deep foundations for a structure, a single deep foundation element may be used to support a building column. The most common type of element used in such cases is a drilled shaft (also referred to as a drilled pier, caisson, or bored pile). However, as installation capabilities have improved, large diameter augercast piles are increasingly more common. While drilled shafts and augercast piles differ significantly in construction methods, in the eyes of the International Building Code (IBC), both are treated as cast-in-place deep foundations and must comply with many of the same code provisions. Deep foundations are required to be braced such that lateral stability is provided in all directions, however isolated, cast-in-place elements that have a diameter (D) of at least 2-feet and a length (L) not more than 12 times the diameter can be an exception. In response to the concerns raised by some member professionals, the Deep Foundations Institute’s (DFI) Augered Cast-in-Place Pile and Drilled Displacement Pile Committee took a closer look at the code and its applications, the historical development of the code language through the years and performed analytical modeling to evaluate the impact of this ratio on a pile’s stability. The question is whether the limiting ratio included in the IBC 2018 code provisions is justified, or whether different criteria should be used to determine when isolated deep foundation members are allowed.

Sep 8, 2021

By I Govender, T L. Moodley

Tumbling mills are grossly inefficient, using only 5 per cent of the total energy supplied for actual breakage. A significant proportion of this inefficiency is unavoidable owing to geometric limitations; rotating drum systems are prone to exhibiting certain regions (energy barriers) that resist particle entry thereby restricting the transfer of energy. Though such systems are inherently inefficient, improved modelling schemes may lead to slightly enhanced efficiency through better microscale predictions of key breakage drivers (stress, force). Central to achieving such incremental advances is the development of a universally accepted rheology for dense granular flows. Armed with a better understanding of these macro-scale ingredients, classical process modelling offers an efficient, spreadsheet friendly framework for recovering the spatial distributions of the comminution drivers. At this real-time level of process control, it should be possible to tune comminution operations towards more energy efficient configurations – the ultimate goal of this research. The present work employs validated DEM data to recover the full continuum field which will ultimately serve as a basis for calibrating process model outputs based on different rheological hypotheses. Such a continuumbased approach captures tensor properties like the shear stress and strain rate – both of which are necessary to developing a dense granular rheology. Moreover, DEM captures this data at the momentum transfer timescale of 10-6 s – no other measurement technique is capable of this level of spatial and temporal resolution. Importantly, the confidence in this DEM data is strengthened because it has been validated at the continuum scale using Positron Emission Particle Tracking (PEPT) kinematic measurements. Validated DEM data is derived from batch experiments conducted within a 300 mm ID laboratory drum using three and five millimetre glass beads at 60 and 75 percent critical speed; such mill speeds are typically encountered in the tumbling mill industry. Dimensional analysis is conducted using critical rheological parameters (shear rate, shear stress, granular temperature etc), which are key to not only developing a granular rheology but ultimately will be used to tune our mechanistic models.

Aug 24, 2022

By Gamal Rashed, Tim Miller, Nicole Evanek

High horizontal stress has been identified as a critical factor affecting roof stability in underground mines, particularly when the immediate roof consists of weak or laminated rock. Numerical models were employed to better understand the influence of caprock thickness, cutting sequences, and the orientation of driving direction relative to maximum horizontal stress on roof stability in underground stone mines. These models were calibrated based on field observations of roof falls from the study mine. The findings of this study enhance our understanding of roof stability under high horizontal stress and contribute to reducing the risk of roof falls in underground stone mines.

Feb 1, 2025

By A. Takala, B Nielson, J. Schunicht

"Pre-concentration in minerals processing presents clear advantages in energy efficiency, water efficiency, reduction of consumables and minimization of capital and operating costs. Outotec’s sorting solutions are powered by Tomra Sorting in order to achieve pre-concentration of concentrator feed in a variety of mineral processing applications. Sensor based sorting combines advanced sensors with rapid computational evaluation and mechanical separation of valuable material from waste and/or gangue. Modern sensor based sorting machines typically use fine air jets to propel individual rocks, thus optimizing recovery and minimizing “mis-sorting”.Gold is generally present in such low concentrations that sensors suitable for ore sorting cannot directly detect it. Therefore, in order to sort gold ore, properties of associated host rock are used. Free and sulphidic gold is often hosted on the quartz-host rock contact zone. Laser scattering effect can be used to detect the surfaces of quartz and composite quartz-host rock particles for subsequent sorting with very high recovery of 95 to 99%. In addition, ore often preferentially fractures along the quartz-host rock contact zone in the crushing circuit. This behavior helps because it liberates more quartz for detection.The feasibility of sorting is investigated for four gold projects in Northern Europe with similar mineralogy. This includes geometallurgical evaluation, amenability testing, small scale “mini-bulk” factory testing in full scale sensor based sorting. The results of the various tests are presented and basic feasibility demonstrated with information on flow sheet development. In addition, the amenability process is evaluated and recommendations made for future projects."

Jan 1, 2017

By Z. M. Beiranvand, M. Moghaddasi, A. Naeimi, Y. Naami, M. Raoufi

Titanium iron oxide and nickel-chromium coatings were applied on low-carbon steel substrates using the high-velocity oxygen fuel thermal spraying process. The microstructure, phase composition, and hardness of the coatings were analysed using scanning electron microscopy, x-ray diffraction, and microhardness tests. The phase analysis confirmed the formation of oxide compounds in the coatings. The average microhardness values for titanium iron oxide and titanium iron oxide-nickel-chromium coatings were measured at 580 HV and 970 HV, respectively, under a 100 g load. The corrosion resistance of the coatings was evaluated in a 3.5% sodium chloride solution using electrochemical impedance spectroscopy (EIS) and polarisation tests. The results indicated that the nickel-chromium composition exhibited superior corrosion resistance, which was attributed to its low porosity, preventing solution diffusion into the substrate. Wear behaviour was assessed using a pin-on-disk test with a tungsten carbide pin as the counterbody. The incorporation of nickel-chromium into the titanium iron oxide coating resulted in an 80% reduction in weight loss, indicating significant improvement in wear resistance. These findings suggest that nickel-chromium-modified titanium iron oxide coatings enhance both corrosion and wear resistance, making them promising candidates for industrial applications.

May 8, 2026