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By Yuanbo Zhang, Zhixiong You, Guanghui Li, Peidan Wen, Tao Jiang

Sn-bearing iron ore containing small amount of Zn, Pb and As is one of the typical complex polymetallic ores in China. This kind of ore is not extensively utilized due to the complicated relationships between iron and other associated nonferrous metal minerals. Excessive contents of these elements would adversely affect the metallurgical operation as well as the quality of steel products. In this study, reduction behavior of Sn was detailedly investigated using H2 or mixed H2/CO as reductant. The results revealed Sn volatilization was improved in the presence of H2 than individual CO/CO2 atmosphere. Simultaneous volatilization of these elements was realized by roasting under weak H2/CO reducing potential, and metallization reduction was advantageous for further Zn volitilization. A metallic pellet (DRI) with Fe metallization greater than 90%, residual Sn, Zn, Pb and As content of 0.054%, 0.012%, 0.0045% and 0.09% was prepared via a simulated reducing gas of coal gasification.

Jan 1, 2015

By Daniella Gomes Rodriguesr

"As mudanças que ocorrem ao longo do recozimento na microestrutura e textura foram observadas no aço inoxidável ferrítico estabilizado ao nióbio, tipo ASTM 430 por meio de Difração de Elétrons Retroespalhados. As amostras deformadas foram recozidas com uma taxa de aquecimento de 23,5°C/s. O recozimento foi interrompido nas temperaturas de 780, 830 e 880°C para acompanhar a evolução da microestrutura e textura. Os resultados mostraram que a nucleação dos novos grãos ocorre preferencialmente nos contornos de alto ângulo. No estágio inicial da recristalização a fibra g é dominante na fração recristalizada, com as componentes 111121, 1111 ,1 2 mais intensas. Na fração não recristalizada a fibra a foi mais intensa. No progresso da recristalização as componentes 11112 1 e 1111 ,1 2 permanecem predominantes, a fibra g torna-se dominante em detrimento da fibra a."

Jan 16, 2018

By Marcos Aurélio S. Costa, Nilton F. Nagem, Andreia B. Henriques, Herman S. Mansur, Alexandra A. P. Mansur, Antonio E. C. Peres, Valeria G. Silva

The superfine material generated in the Bayer process was used in one innovatively way as a precursor to geopolymerization techniques because of the presence of Gibbsite. Gibbsite can play a role in system adjustment because of the SiO2/Al2O3 ratio. Furthermore in the geopolymeric system it was studied the influenceof the additives such as kaolin, metakaolin and sodium trisilicate in an alkaline media. Others conditions to form the geopolymer were also evaluated such as solid/liquid ratio, SiO2/Al2O3 ratio and total alkaline. The raw materials and geopolymeric products were characterized by several techniques e.g. XRD, DSC, FTIR and SEM. Through the FTIR technique it was observed an increase in intensity and bandwidth in the region centered at 1010 cm-1, which is related to the asymmetric vibration Si(Al)-O, this is an indicating of the possible geopolymer formation This broadening of the band promotes a relative disappearance (overlapping) peaks at 965 and 935 cm-1 associated with raw material (ESPDust).

Jan 1, 2015

By André Rosiak

No processo de forjamento a quente, devido aos ciclos térmicos e mecânicos a que o material é submetido, diversos fatores influenciam e ampliam a gama de propriedades mecânicas que podem ser obtidas nas peças metálicas produtos deste processo. A proposta deste artigo é estudar a influência dos fatores tempo de austenitização, temperatura e deformação sobre a variação da dureza do aço ABNT 4140. Para isso, o material foi mantido em diferentes temperaturas, durante diferentes períodos de tempo e, posteriormente, forjado e tratado termicamente em patamares semelhantes aos de recozimento direto e revenimento. Esta pesquisa corresponde a uma das etapas do projeto BRAGECRIM (Iniciativa Brasil-Alemanha para Pesquisa Colaborativa em Tecnologia de Manufatura).

Aug 17, 2017

By Q. Li

"The precursor of In2O3 was prepared by hydrolysis precipitation/hydrothermal method using In(NO3)3 solution as the feed material and ammonium hydroxide as the neutralizing agent. The crystallinity, morphology and particle size of the products were characterized by SEM, XRD, BET and LPSA. The results showed that the hydrolysis product consists of an aggregate of cubic In(OH)3 particles with a short rod morphology. In the hydrothermal process, the structure, morphology and size of the particles changes through the mechanisms of Ostwald ripening and phase transition, respectively. When the hydrothermal temperature was less than 280 ?, the Ostwald ripening process took place, which changed the morphology of the particles from short rods to cuboids through dissolution-recrystallization. When the hydrothermal temperature was higher than 280 ?, the processes of Ostwald ripening and phase transition took place successively. Firstly, the morphology of the particles changed from short rods to cuboids through Ostwald ripening, and then, the phase transition from cubic In(OH)3 to orthorhombic InOOH occurred and the morphology of the particles changed from cuboids to polyhedron. INTRODUCTIONDue to its excellent electrical conductivity and optical transparency, indium tin oxide (ITO) film has been wildly used in flat-panel display, solar cell, antistatic coating and EMI shielding (Medvedovski et al., 2008). Indium oxide powder is one of the fundamental materials for preparing ITO film. Along with the development of ITO targets of both high density and large size, high quality indium oxide powders, such as single phase, nano-size, spherical morphology and mono-disperse, have been in high demand (Nakashima and Kumahara, 2002; Betz et al., 2006; Kim et al., 2007). The main preparation methods for indium tin oxide or indium oxide powders include chemical precipitation (Nam et al., 2001; Xu and Yu, 2007), melt atomizing-combustion (Chen et al., 2000) and spray pyrolysis (Ogi et al., 2009). Among them, chemical precipitation has been preferred, since it is simple, easy to control and suitable for industrial scale-up. In chemical precipitation method, indium oxide powders were prepared through the following steps: firstly, indium hydrate precursor was precipitated from an indium salt solution by neutralization using an alkali, such as ammonia; and then, indium oxide (In2O3) powders can be obtained from the precursor through calcination (Li et al., 2006), or solvothermal method (Lee and Choi, 2005), or hydrothermal processing/roasting (Xu et al., 2005; Chen and Li, 2007), respectively. However, the indium oxide powders obtained by direct roasting are polycrystalline, dispersable with a wide size distribution (Liao, 2006). The disadvantages of the solvothermal method are high cost, complicated after-treatment processes, as well as bad performances of the powders (Udawatte and Yanagisawa, 2000). Therefore, among three methods of obtaining indium oxide from the hydrolysis precursor, the hydrothermal process/roasting method is the most feasible to synthesize high quality In2O3 powder with uniform crystallinity and size (Kim et al., 2002; Zhu et al., 2004; Xu et al., 2005; Xu et al., 2005; Chen and Li, 2007; Seetha et al., 2009). However, current research on hydrothermal process-roasting method has been limited to the synthesis of a certain ITO or In2O3 powders under specific conditions. A systematic study on the phase transition, as well as the change of the morphology and size of the particles in the hydrothermal process is still missing. In this paper, the effects of hydrothermal processing on the mineralogy, morphology and size of products were investigated. The results showed that the evolution of crystal structure, morphology and size in the hydrothermal process was affected through the mechanisms of Ostwald ripening and phase transition successively. These results are novel and have guidance for improving the hydrothermal process for In2O3"

Jan 1, 2012

By Blaycock. S. C.

WE should indeed feel proud and satisfied with the accomplishments of our great mining and metallurgical. industries during the past quarter of a century, for they have vastly exceeded those of any previous period of like duration. 1 feel that Canadians, and particularly those in the mining industry, should know more concerning the important role our industry will be called upon to play in the present war. Our Empire metals will be an outstanding factor in this conflict. Every man connected with the industry, from the lowest paid labourer to the highest official, can feel proud that his every effort results in more and more production of those metals which will help to give the Empire supremacy. He can feel assured that, by sticking to his job and by putting his whole heart into his work, he is making a contribution towards winning the terrible struggle in which our Empire and our gallant French allies are engaged. These two great peoples will have ro bear the brunt of the task of ridding the world of the menace of those who would set up force. and might in the place of right and justice in the settlement of international affairs. As the present European crisis developed, it became evident that they, alone, would have to accept the challenge and fight the enemies of Democracy to ensure the survival of the small nations of Europe and, indeed, of the great democratic powers themselves. The acquisitive eye of the German leaders had looked far ahead and they had realized that the eastern European states, already reeming with population, were no solution to Germany's space problem; but they thought that these states could be gobbled up one by one, each in turn strengthening Germany's might until it could successfully challenge France and England. No glimmer of doubt dimmed their vision. The two great democracies once subdued, they could proceed to seize Canada and the United States. This clone, they would have an abundance of room to expand, as well as those resources-grain, timber, cotton, nickel, iron, lead, zinc, copper, gold, silver, sulphur, oil-which German statesmen have always coveted. Von Ribbentrop, von Alvensleben, Bernstorff, and many others have made exhaustive studies of our resources. German rulers had been told that the French would not fight and that the British could not. They knew of the rust on the British war machine. There was no cloud in the sky; their fond dream was at last robe fulfilled.

Jan 1, 1940

By Paulo César Lemes de Almeida

No projeto da usina da VSB, em Jeceaba – MG estão contemplados dois altos-fornos de 350 m3 de volume útil e uma máquina de lingotar gusa (MLG) com capacidade de 150 t/h. Um destes altos-fornos já está pronto para o início de operação. Visando realizar os testes a quente da MLG a aciaria da VSB tem produzido aço com alto teor de carbono para testar o equipamento. Realizaram-se 07 etapas de testes que possibilitaram a implantação de algumas melhorias na MLG, coletar dados sobre a logística de movimentação de panelas, estimar perdas térmicas do gusa e treinar o pessoal para a operação. Nesta contribuição técnica descrevem-se os testes realizados e as modificações decorrentes.

Aug 1, 2018

By C. Leticia Hernández, P. Martín Reyes, D. Iván Alejandrox Reyes, L. Miguel Pérez, T. Julio Cesar Juárez, G. Mizraim Uriel Flores, T. Raúl Moreno, R. Aislinn Michelle Teja

This study shows the characterization of tailings from the mining district of Coscotitlán, State of Hidalgo, Mexico. Chemical analysis by Spectroscopy of atomic absorption (AAS) allowed to quantify the concentration of Fe, Mn, Zn, and Pb as the most abundant elements in the mineral sample; in addition to the presence of Sn, Te, Bi, Ni, Co, and Cd. The presence of precious metals as the Ag (64 g ton−1) and Au (0.65 g ton−1) were identified. The greater distribution of Ag was detected in particles with diameter of 74 lm. Species as pyrite (FeS2), galena (PbS) and hematite (Fe2O3) were observed in a matrix of quartz (SiO2) by Polarized Optical Microscopy (POM), these species were also identified by X-ray Diffraction (XRD). Both the elemental and mineralogical composition of tailings was corroborated by the technique Scanning Electron Microscopy - Energy Dispersive Microanalysis (SEM-EDS).

Mar 1, 2018

By Liugen Sun, Xingming Jiang, Weijiao Yang, Yihang Hu, Yongqiang Yang, Hua Wang

During the past decades, cyclone electrowinning (CE) has been regarded as a novel separation technology, which can be used for direct electrowinning of metals from low concentration solution. Recently, CE was proven effective for the treatment of antimonic gold concentrates. The experimental results of cyclone electrowinning of antimony show the current efficiency increases from 43.8 to 72.2% with the increasing current density (from 254.8 to 647.3 A/m2), and on the other hand, power consumption per ton antimony decreases from 6100 to 4200 kWh with the aforementioned increasing current density. The grade of the obtained cathode antimony could reach 98.6%. Compared with the traditional electrowinning using parallel-board electrodes, the economic profit of CE was 33.1% higher attributed to the high current efficiency of CE. In addition, CE could adapt to high current density. All these characteristics indicate the CE method can be implemented commercially for processing antimonic gold concentrates.

Mar 1, 2018

By Carrie Smith

Leaders from the U.S. government and the global mining industry opened the MINEXCHANGE 2026 SME Annual Conference & Expo with a keynote session centered on restoring U.S. critical mineral production and strengthening domestic supply chains. The session, titled “Regaining America’s Mineral Dominance,” featured remarks from Ned Mamula, director at the U.S. Geological Survey (USGS), Utah Governor Spencer J. Cox and Vicky Peacey, president and general manager of Resolution Copper, along with opening comments from industry leaders and conference organizers. The speakers emphasized that renewed government attention to critical minerals, combined with industry investment and technological innovation, will be necessary to meet rising demand for materials such as copper, zinc and rare earth elements. The session opened with remarks from Pat Risner, president of South32 Hermosa, followed by a safety share from 2025 SME President Bill Hancock. Hancock then introduced moderator Debra Struhsacker, who emphasized the importance of strengthening domestic mineral production and reducing reliance on foreign supply chains. Struhsacker, who is SME’s government and public affairs consultant, noted that decades of policy decisions have weakened the U.S. mining sector, leaving the country increasingly dependent on imported minerals. She pointed to declining domestic capacity, a shrinking number of mining schools and the closure of the U.S. Bureau of Mines in 1996 as factors that contributed to the current supply challenge.

Apr 1, 2026

By V. Reiter, K. Reinharter, C. Wenzl, D. Gregurek, A. Spanring

The refractory linings in lead furnaces are exposed to several stresses rather complex in their interaction. In the present study the magnesia-chromite brick out of a lead recycling furnace suffered from a high chemical attack by the process slag. The high CaO, BaO and sulfur bearing silicate slag, as well as a high NaO2 supply from soda resulted both in a deep-reaching infiltration of the brick microstructure and a severe corrosion of the brick components. Both the sintered magnesia and chromite were attacked chemically. The FactSage calculations showed the formation of high amounts of liquid phase in the infiltrated microstructure. Further phenomena affecting the refractory performance such as iron oxide attack, redox effects, and boron attack are also discussed in the paper. The obtained information and insights serve as a basis for improving refractory materials (i.e., choice of refractories for individual process and new developments) and consequently furnace operations.

Mar 1, 2017

By Jung-Joo Kim, Jong-Uk Kim, Turab H. Jafri, Han-Kyu Yoo

"INTRODUCTION Steel sets such as H-type and lattice girders are often installed in the tunnels before the hardening of shotcrete to ensure the stability of conventional tunnels in soft ground conditions. In practice, while designing the tunnels with the help of numerical analysis, steel sets are generally considered only as temporary support elements. Only a few studies propose the direct application of composite support in the tunnel design, based on large-scale experiments and numerical analysis. In order to assess the structural performance of the composite support consisting of shotcrete and steel sets, large-scale experiments were performed on two types of arch-shaped specimens by applying the combined effects of axial forces and bending moments. Based on the experimental results, numerical analysis was performed to assess the application of composite support in tunnel design. The crown settlement, axial forces, bending moments, and load distribution in the composite support were analyzed in the light of different structural patterns. LARGE-SCALE EXPERIMENTS USING COMPOSITE SUPPORT Preparation and Procedure of the Experiments The preparation setup as well as the organized procedure of the large-scale experiments using composite support is shown in Figure 1. An appropriate geometry of the specimens was selected by considering the standard cross-section of a two-lane highway tunnel in South Korea. Under the loading conditions meant to develop the axial forces and bending moments simultaneously, arch-shaped specimens were assembled with the ends of the specimens subtending a 60° arc angle at the center of the arc circle as shown in Figure 2. The fabrication of six specimens was completed in two groups based on the dimensions of steel sets, with the first group of three specimens being reinforced by H100 (No.1, No.2, No.3) and the other three by H125 (No.4, No.5, No.6). In order to reduce the voids on the boundary of the shotcrete and steel sets, concrete was casted over the steel sets instead of using shotcrete. The specimens were designed to incorporate the uniaxial compressive strength of 21 MPa. Shear keys and steel plates were installed at the ends of the specimens, so that shear failure could be avoided at the ends and the specimens could also be protected from detachment at the fixation. Translational and rotational movements at the ends of specimens were fixed."

Jan 1, 2016

By Tsisana Gagnidze

A processing of technogenous wastes, which involve a gold-containing sulphide minerals, is a potential source to supplement the gold reserves. Hence, searching of ecologically safe and economically reasonable methods for processing of gold-containing technogenous wastes is a topical problem. To increase a parameters of gold extraction and to simplify a technology of the processing of above-mentioned wastes of sulphide minerals, an investigations have been carried out in the direction of the use of the method of electrochemical leaching without any preliminary processing of the mineral. It was established experimentally that an introduction of nitrogen containing organic additive into chloride solution favours to reduce a Red/Ox potential of the solution from 0,8÷1,2 V to 0,35÷0,5V, which permits to conduct the process of direct electrochemical leaching at ?soft? oxidation regimes at temperatures 20-300C C without an environmental contamination by molecular chlorine and with a high degree of a gold extraction up to 80-90%.

Jan 1, 2008

In the March/April 2006 issue of the Journal, we published an ethical dilemma called “Blowing the Whistle.” We received many interesting responses to the article as requested. Some of the responses are printed here. We’ve also included “Blowing the Whistle” again in this issue as a refresher on page 37. Dear Editor, It is in my own personal belief that it would be extremely important if I were the blaster to take the following steps. 1. Hold an immediate emergency meeting with the contractor to convince them to stop work at this point.2. This meeting would need to be held with all powers that be in this construction company. This helps eliminate the hearsay (excluding the farmer). 3. Explain the entire situation to the contractors as it has been presented to the blaster by the farmer. 4. Recommend calling in an engineering or geological firm with the expertise to investigate this matter immediately, and take all immediate action based on findings. 5. Follow up with farmer allow him to speak, (a.k.a. vent) and assure him proper steps are being taken to come to resolve this matter. 6. Be a good listener, and communicator with the farmer while investigation is being conducted. 7. Should the contractor not want, or take any of these recommendations, the blaster himself and his company should question even working for this company ever again. This in itself would not be the class of people we would want to be associated with EVER.

Jan 1, 2007

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 AIME AIME

IT its annual meeting on Oct. 21 and 22, the Engineers' Council for Professional Development announced the selection of J. P. H. Perry. vice-president of the Turner Construction Co. and prominent civil engineer of New York City as its new Chairman. He succeeds C. F. Scott, who becomes Chairman of its Committee on Professional Recognition. S. L. Tyler, Secretary of the American Institute of Chemical Engineers, succeeds A. B. Parsons as ECPD Secretary. R. E. Doherty is Vice-chairman. C. E. Davies remains as Assistant Secretary, as do R. L. Sackett as Chairman of the Committee on Student Selection and Guidance, O. W. Eshhach as Chairman of the Committee on Engineering Training, and Karl T. Compton as Chairman of the Committee on Engineering Schools.

Jan 1, 1938

By C Young

In the vast expanse of Western Australia’s mining sector, a critical issue has come to light: many mining operations overlook the power of a Broad-Brush Risk Assessment (BBRA) to uncover their critical risks. This oversight has led to a cascade of challenges, where some mining endeavours find themselves grappling with: - Unidentified and unmanaged fatal risks, casting a shadow of uncertainty and heightened compliance risks. - A bewildering landscape where the concept of critical risks remains enigmatic, with some mistaking the risk register for the BBRA. - A fog of confusion surrounding the guardianship of these critical risks, leaving safety responsibilities blurred and undefined. Yet, the solution lies within our grasp. An effective BBRA empowers organisations to: - Pinpoint with unwavering certainty every ‘true’ critical risk. - Clarify ownership for each critical risk, ensuring accountability and swift action. - Create a prioritised roster of critical risks, illuminating the path to safer operations. - Lay the foundation for essential follow-up actions like bow-tie analysis, the identification of critical controls, and the fortification of the safety and health management system. Join us in this presentation, where we delve into the heart of an industry-leading BBRA process. Discover practical insights that will enable your organisation to craft and implement BBRA strategies, bridging the gaps in your journey toward preventing fatalities and fortifying safety protocols.

Apr 16, 2024

By Sibin Zhang, Shengli Wu, Youhao Yin, Yuandong Pei, Zhixing Zhao, Jiangshan Shi, Zhengyun Fan

Spraying medium to achieve an energy-saving and emission reduction for iron ore sintering has been researched, such as spraying natural gas, coke oven gas, oxygen, sintering flue gas and gas from annular cooler. This paper focuses on effect of spraying steam on sintering surface on reduction of NOx and dioxin emissions in practical sintering production in Shougang Jingtang. It can be found that, with the increase of sintering bed spraying steam amount, NOx and dioxin of flue gas showed a decreasing trend. As spraying steam 1 t/h for 550 m2 sintering machine in Jingtang, NOx content decreases 2.6–9.5 mg/Nm3, and dioxin decreases 0.007–0.014 TEG ng/Nm3.

Mar 1, 2018

By E. J. Duggan

In the course of the grinding experiments conducted at Climax over the past twenty years one interesting phenomenon was discovered. This was that balls made of certain types of steel grind more ore than some others. The most significant variation was found in the results secured with a hard alloyed forged bail compared with the forged carbon ball supplied by most ball manufacturers These findings were confirmed in many repeated controlled tests. The value of these tests depends on the methods used, the facilities available and the care with which the investigations were conducted. These are described in the following. This testing has largely been done in eight 91 x 81 low discharge ball mills in closed circuit with 7811 duplex screw classifiers. The mills run at 20 RPM on a feed approximately minus 3/8 inch. The ore is ground through 28 - 35 mesh in one stage. Each mill and auxiliary classifier is in a separate, parallel grinding and flotation section The, ore to each: section is the same in every particular and is fed to each mill bin from a common conveyor tripper. The ore from the bin to the ball mill is weighed on a conveyor scale. The power input to each mill motor is determined with a watt hour meter which measures the power to the mill motor only. Both the scales and meters are checked periodically by standard methods and have been found to give consistent readings. Automatic samplers are employed on each section to obtain accurate measurement of the size reduction. A size analysis of the classifier overflow is made each shift and a composite size analysis is obtained from a weighted average of the various shift analyses. The mills are driven by 450 horsepower synchronous motors so that there is no speed variation and shell liner age is kept as nearly the same as possible in mills under test. The same set of operators is assigned to a mill under test as to the control mill. In all other particulars such as ball load, mill density, liner design, etc., the mills are operated in precisely the same manner. This is an ideal arrangement for plant testing. From observations of ball mill performance over the past twenty years, it is the opinion of the operating staff that variations of as little as one to two percent in mill capacities may be determined if sufficient operating hours are devoted, to a test. Relations between mill capacities, fineness of grinds and power consumptions have been established with a high degree of accuracy. In Table I are given the figures for one test. These show that while the grind with the hard ball was slightly coarser, the tons ground per hour was 5.4 percent greater with the soft ball, and 6.1 percent greater on the basis of minus 100 mesh produced. The power consumed per ton with the hard ball was 4.4 percent greater on a tons per hour basis. The soft ball was inferior in wearing qualities and steel consumption per ton of ore was 24 percent greater with it. In this test the mills were charged with the two different balls for a period of three months to allow the ball loads to come to equilibrium. In Table II are given the specifications of the two balls. The difference in grinding rates may be accounted for by the nature of the ball surfaces. The surfaces of the soft balls after being worn a while are rougher to the touch. Enlarged photographs of the worn-in surfaces of hard and soft balls are shown in Figure I. These show the presence of scratches or skid marks on the hard ball surface which indicates less nipping effect. The Climax ore pulp has a pH of 6.0 and is in a dispersed state. The viscosity is low compared with most ores especially those that are conditioned with lime. This would lower the tendency of the pulp to adhere to the balls with a lower grinding efficiency as a result. It was also thought that the relative rates of wear from surface to center might affect the make-up of an equilibrium ball charge. This probably has little effect on capacity as shown by the size analyses of the two ball charges in Table III. This hypothesis was subsequently investigated by the use of rationed charges. The rationed charge did not overcome the advantage in

Jan 1, 1958

By Sebastian Lobo-Guerrero

Welcome to DFI45! our first on-line annual meeting. We cannot deny the severe impacts that the COVID19 pandemic is having in our industry and our lives. We extend our support to all of our members that have been impacted in many different ways. But through the middle of this difficult and challenging times, our beloved annual conference emerges, trying to re-unite our industry and remind us why we love what we do so much. DFI45 was not originally planned to be delivered virtually, but as our world changed, we adapted. Adversity became an opportunity to re-invent our annual conference. Thanks to the vision of our Organizing Committee, we saw the amazing new possibilities and DFI45 is today a reality. Our theme for this year is People + Purpose + Passion. This theme was decided before the COVID 19 pandemic started, but today it is more relevant than ever before. We are a group of very diverse people at DFI. Our organization includes Contractors, Consultants, Suppliers, and Academics just to name a few sub-groups. But we all have a common purpose and try to find common ground. We are all extremely passionate about what we do, and this excitement is really what makes this organization what it is today. This conference celebrates this passion as you can see in our three main Keynote Sessions. On a local scale, we want to go back and remember the contribution of our industry to our beloved National Monuments in Washington D.C. On a national scale, we want to explore and recap the development of Government Guidelines and Specifications that became the world standards. And finally, we want to close the conference with a session celebrating the family legacy and share amazing stories of families with multiple generations working in our industry. Besides our Keynote Lectures, the conference is full of exciting content such as several case histories, experimental research in deep foundations, applications of new technologies, business aspects and risk management considerations for deep foundations, just to list a few. We also have our now traditional events such as the Hal Hunt Lecture, Awards Reception, DFI Educational Trust 5K Fundraiser, etc. For the first time, all this content will be delivered using different virtual formats, including on-demand presentations, plenary sessions, interactive chat rooms, etc. We are excited about these possibilities. To conclude, we need to recognize the people that against all odds made this conference a reality. First our sponsors, they adapted to the most abrupt change never thought before, and they always stayed there with us, providing unconditional support. Without them no conference is possible. Next, our Organizing Committee that re-invented the concept of an annual conference and found new and exciting ways to make this happen! Our Technical Program Committee led by our Technical Program Chairs, Jennifer Nicks and Gregg Piazza, showed us that nothing is impossible. And last, but not least, the amazing DFI staff that make dreams reality. It has been an honor to serve as the Conference Chair for DFI45. It is an experience that will stay with me for the rest of my career. Conference Chair: Sebastian Lobo Guerrero, Ph.D., P.E. American Geotechnical and Environmental Services (A.G.E.S.)

Oct 27, 2020