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By Donald Barton

THE theory of gravitation is based on Newton's law that any two bodies exert a mutual attraction which is proportional to the product of their masses and inversely proportional to the square of the distance between them; i. e., A =KRM/R2 (1) where K is a constant, M and m are the respective masses of the two bodies, and R the distance between them. In the earth's gravitational system, the earth is one of the bodies; the other may be any body within or without the earth. In theoretical dis¬cussions and calculations in regard to gravity, that other body usually is taken as a unit of mass: in the C. G. S. system, a body of one gram in mass. GRAVITY AND LEVEL SURFACES Gravity is defined in geophysics as the force of attraction exerted by the earth, towards itself, on a body of unit mass. The intensity of gravity is usually expressed in dynes of force or in centimeters of acceleration. In geophysical work in America, most commonly it is expressed in dynes (per gram) with the "per gram" understood and not directly expressed. In geophysical work in Europe, most commonly it is expressed in centimeters per second per second (cm./sec.2) and less commonly merely as centimeter-gram-second units (C. G. S.). At sea level, the intensity of gravity amounts very nearly to 980 dynes. The vertical is the direction along which the attraction of gravity is exerted at any point. . In most cases, it is very nearly, but not quite, per¬pendicular to the earth's surface. The path that would be taken by a body falling freely through space toward the earth is vertical at each point and may be spoken of also as "the vertical," or as the line of the vertical, or as a line of force of gravity. At the earth's surface it com¬monly is very nearly, but not quite, a straight line.

Jan 1, 1928

By E. A. Roux

As the first mine-to-metal zinc operation utilising atmospheric leaching, solvent extraction and electrowinning, Skorpion Zinc faces unique challenges and opportunities. One of these challenges is found in the solvent extraction circuit, in which di-ethylhexyl phosphoric acid (D2EHPA) is used as the organic extractant. Although D2EHPA is an excellent extractant for zinc, it suffers from the co-extraction of ferric iron, which is produced during leaching and by the corrosion of the grinding media. This situation is partially mitigated by iron precipitation in the neutralisation step prior to solvent extraction. Unfortunately, some ferric iron still reports to the solvent extraction process. This leads to a slow build up of iron in the organic phase. Chemical stripping is used to maintain the Fe concentration at an acceptable level. In this paper, the efficiency of the iron removal process is discussed.

Jan 1, 2006

By A. T. Yu

As the first loads of Noamundi iron ore rumbled into the new 54-in. Gyratory Crusher on March 30, 1968, one of India's largest and most modern iron ore processing complexes began operations. The completion of the $13 million mining and processing complex brought to a successful conclusion the second chapter of a phased expansion program initiated in 1958 by India's gigantic Tata Iron and Steel Co. The completed complex will yield annually 2.5 million tons of washed, sized ore and sinter fines destined for Tata's furnaces at Jamshedpur. Hewitt-Robins Div. of Litton Industries was awarded the turnkey project on the basis of world- wide competitive bids. Eighty miles southwest of the city of Jamshedpur, Noamundi lies on an approximate geographic grid of 22º-5' latitude north and 85º-30' longitude east. The mine is approximately 600 ft above sea level.

Jan 11, 1968

By Dilek Kirgöz, Onuralp Yücel, Murat Alkan

"In this study, Mo containing Fe-based alloys, such as Fe-Ni-Cr-Mo, were synthesized using a mixture of Fe203-NiO-Cr203-Mo03 powders reducing with Al powders by metallothermic process which is a high energy efficient, fast and low-cost production technique for synthesis of cast alloys and advanced ceramics. Detailed thermochemical studies were simulated by using FactSage 6.2 Thermochemical software in order to calculate adiabatic temperature of the reactions and effects of initial molar composition on the final products. In the metallothermic processes, effects of stoichiometric Al addition and addition of the oxide powders (Alz03, Si02, CaO, MgO) on the metal recovery and compositions of final alloys were carried out. Final products were characterized by using chemical analysis (AAS), XRD, XRF and SEM/EDS techniques.IntroductionSelf Propagating High Temperature Synthesis (SHS) has significant advantages compared to the high technology furnace applications, such as very short processing time, simple operation, low energy requirement and low cost [l, 2]. In a SHS process, the ignition starts the combustion and propagates throughout the reactant mixture yielding the desired product. However, the disadvantages of the process such as inhomogeneous or unreacted products due to undesirable reaction rates needs to be overcome by changing some parameters such as ignition temperature, particle size, additive, atmosphere etc. [3, 4]. This work aims to establish a scientific and engineering background in the production of some cast Fe based alloys (Fe-Ni-Cr-Mo) which are used as surface coatings, wear-corrosion-oxidation resistive applications via SHS (Self Propagating High Temperature Synthesis) metallurgy which is attractive process technique regarding fast and low-cost production ability of cast alloys."

Jan 1, 2013

By Justin Carl, Aliuddin Mohammad, Gordon Evans, Steven Bealby, Carlton Ray

"The District of Columbia Water and Sewer Authority (DC Water) is implementing the $2.2-billion DC Clean Rivers Project (DCCR) to control combined sewer overflows (CSO) to the Anacostia and Potomac rivers and Rock Creek, and to provide flood relief to the Bloomingdale and LeDroit Park neighborhoods in the District of Columbia. The long-term control plan complies with the requirements of a Federal Consent Decree entered into by DC Water, the District of Columbia and the United States, as represented by the U.S. Environmental Protection Agency and the Department of Justice. The Northeast Boundary Tunnel, a design-build project, will store combined sewage and deliver it to a system of downstream tunnels and ultimately to the Blue Plains Advanced Wastewater Treatment Plant (Blue Plains), where it will be treated. In addition, the Northeast Boundary Tunnel (NEBT) is a major project associated with the mayor’s task force to alleviate extreme flood events in Bloomingdale and LeDroit Park. The Northeast Boundary Tunnel Utility Relocations (NEBTUR) design-bid-build (DBB) project is an accelerated component of the Anacostia River System, as shown in Fig. 1. During dry weather conditions, the entirety of the sewage in the combined system is conveyed to Blue Plains.During storm events, when sewer pipe capacity is exceeded, the flow, which is a mixture of sewage and stormwater runoff, overflows into receiving waters through outfalls. There are a total of 47 active CSO outfalls along district waterways.The influx of storm runoff into the combined sewer has an additional impact on the communities of Bloomingdale and LeDroit Park. The sewer system is outdated and undersized. In these neighborhoods, when the capacity of the sewer is exceeded, localized flooding occurs and backups into adjacent residences are prevalent. In any given year, there is a 50-percent chance that flooding will occur in these neighborhoods."

Jan 9, 2017

By W. E. D. Jr. Stokes

THE application of aviation to mining and petroleum operations, on the basis of economy and attainment, has become a demonstrated fact. According to Dominion Government records, 30. Canadian companies engaged in air transportation with northland mining camps, carried 13,000 tons of freight in 1935, and in 1936 carried 16,000 tons. In addition, many mining companies used planes to transport prospectors with canoes, outboard motors, gasoline drums and supplies to remote locations, and one company maintained a plane to take radium-bearing ore from its mine on Great Bear Lake nearly 1000 miles south to the rail-way at Waterways, Alberta. Heavy pieces of mining machinery weighing 2 tons are being carried by Ford trimotor planes over the Andes, at an altitude of not less than 15,000 feet. At Bulolo, New Guinea, 17,500 tons of disassembled gold-dredging equipment has been flown over inaccessible terrain, while supplies and building materials for a, community of 1000 whites have been transported by airplane. A 3 1/2-ton shaft was carried on one notable trip, while at another time an automobile, 2 tons of rice and a large safe went over the mountains in one plane. Fig. 1 shows an electric generator that was carried by plane to Bulolo.

Jan 1, 1937

By P. Kim, M. Tangstad, T. Larssen, R. Kawamoto

The reduction rates of MnO and SiO2 were investigated for various charge compositions. The empirical activation energies of MnO and SiO2 reduction from SiMn slags were calculated between 1500 and 1650 °C under CO atmospheric pressure. The amounts of metal produced at different temperatures were compared, and the Arrhenius plots were described for each slag A, slag B and synthetic slag, which shows that the raw material have significant influence on the reduction rate. The rate of Mn-produced in slag A was faster than slag B despite of the relatively lower driving force. The lower rate constant in slag B implies that other kinetic factors, such as viscosity, affects the reduction rate. The estimated activation energies of MnO were 920, 304 and 975 kJ/mol MnO for slag A, slag B and synthetic slag, respectively. The rates of Si-produced were similar and slow for all slag types. However, the different activation energies of SiO2 between industrial ores and synthetic materials implied that the trace elements can have catalytic effects toward SiO2 reduction in SiMn slags. The estimated activation energies of SiO2 reduction were around 800 kJ/mol for slag A and slag B.

Mar 1, 2017

By Paul H. Johnson

A new system for leaching many types of ores has recently been developed on a commercial basis by J and J Research and Development, Inc. of Hanover, New Mexico. This revolutionary new leaching system consists principally of three new leaching reactors; viz, (1) a large, air-agitates, column-like reactor for leaching crushed ores that is constructed in an underground environment and has the inherent ability to do a very efficient job of leaching, (2) a vat-like, air-agitated vessel for leaching an rinsing finely ground ores and , (3) an air-agitated copper precipitation column that is built underground and utilizes an inexpensive dense or heavy scrap iron as a copper precipitant. Each of these new reactors have been used in a large leaching plant near Hanover, New Mexico.

Jan 1, 1973

By Ken MacLeod

A development at 83 Queens Road in Melbourne, Australia required construction of a three level basement. The normal geotechnical constraints of excavating adjacent to an existing relatively new building were challenging enough for the complicated soils profile occurring at the site. An additional significant challenge faced by the designers, was the requirement to excavate underneath the entire footprint of an existing heritage listed building, known locally as the Mansion, in the centre of the site. Maintaining the structural integrity of that building was afforded the highest priority during the 10m excavation. This paper describes geotechnical aspects of the analysis, design and construction of the secant retention system adjacent the new building and support of the Mansion enabling the 10m excavation to proceed without causing damage to the structure. The secant wall comprised hard-soft interlocking piles constructed using CFA methods. CFA piles along the length of the Mansion provided short term support, with the building load being transferred to the piles by large steel beams jacked under the building. Survey results confirmed that movements of the retaining wall and also the load bearing piles were minimal and well within design expectations.

Jan 1, 2006

By Heitor Cristo Clem de Oliveira

O objetivo deste trabalho é estudar a reação de dessulfuração, envolvidas no processo de pré-tratamento de ferro-gusa. A princípio, as misturas utilizadas foram caracterizadas e estudadas através do software de termodinâmica computacional (FactSage 7.1). Em seguida, os resultados obtidos através do estudo termodinâmico computacional foram comparados com aqueles obtidos mediante os testes experimentais a 1400°C. As misturas dessulfurantes tiveram como base a CaO com três tipos de fundentes, fluorita, sodalita e barrilha, além da utilização de alumínio como elemento desoxidante. Os testes experimentais permitiram identificar que a adição de 0,1% em massa de alumínio no gusa, eleva a taxa de remoção de enxofre principalmente no instantes iniciais do processo. Com a utilização da termodinâmica computacional pode-se mostrar que a reação de dessulfuração no ferro-gusa é exotérmica para os teores de silício encontrados no processo. Além disso, a termodinâmica computacional também contribui, em alguns casos, para a análise de compostos sólidos que podem se formar na escória e limitar as reações de dessulfuração.

Oct 30, 2017

By Demetrius Da Rós Ruy

O lingotamento contínuo é uma das etapas mais importantes na produção de aço, sendo um método rápido e eficiente na fabricação de placas ou tarugos através de processos de resfriamento onde o aço líquido é moldado e solidificado. Contudo, têm sido historicamente observado problemas de processo corrosivo acentuado na câmara de exaustão e na estrutura das máquinas da ArcelorMittal Tubarão. Os mecanismos deste processo corrosivo em máquinas de lingotamento contínuo, em geral, são variados e diretamente relacionados às condições operacionais da máquina, conduzindo a elevados custos de manutenção, diminuição da vida útil das máquinas, causando insegurança e interferindo na qualidade do produto. Este trabalho objetiva descrever as causas principais deste processo corrosivo e mostrar o desenvolvimento de testes que foram conduzidos visando a minimização deste fenômeno na máquina de lingotamento de placas #1 da ArcelorMittal Tubarão no ano de 2017.

Oct 30, 2017

By Tenney, J. B.

DEVELOPMENT of complex ores in the south- western part of the Rocky Mountain region has been retarded by the prohibitive distance to the nearest suitable zinc treatment plants. In the north- western and central Rocky Mountains the building, cluring tlie past decade, of electrolytic zinc plants at Anaconda, Great Falls, Trail, and Burke has tremendously stimulated the mining and exploiting of such .ores, greatly increasing the production of lead, zinc, copper, gold, and silver. Selective flotation permits the making of high-grade led, copper, and zinc concentrates. If the zinc concentrates could be made free from lead, copper, gold, and silver, they could be shipped economically to Mid- Western retort plants designed for such concentrates. Unfortunately a considerable proportion of the precious metal content accompanies the zinc blende in the ores of this region. Although some of it is saved in 'retort residues, the treatment cost is thereby increased so materially and the proportion saved so small, that .concentrates of ordinary grade cannot stand treatment charges and freight.

Sep 1, 1928

By C. F. Wingquist

As part of an ongoing study to determine how the wear of mining tools affects dust generation, the Bureau of Mines has measured bit tempera-ture rise during cutting of abrasive rock. Radial bit wear-flat tem-peratures generated by linear cutting in Berea Sandstone were measured as a function of cutting depth and speed. Depths of cut (DOC) were 1/8, 1/4, and 1/2 in, and cutting speeds were 10, 40, and 80 in/s, respectively. Temperature sensing was accomplished by emplacement of a miniature thermocouple into the center of the wear flat. Temperatures observed ranged from 2000 to 5000 C. Correlation between depth and temperature was weak. Temperature increased linearly with speed at 1/2-in DOC, but data taken at 1/8-and 1/4-in DOC produced inconclusive results. The results indicated that at least for deeper cuts (1/2 in), bit temperature, and therefore wear, can be reduced by lowering the cutting speed.

Jan 1, 1987

By T D. H McGrath, W P. Staunton

Benchmarking, comparing an operation or process with the industry standard, is known to be a useful method for identifying plant optimisation opportunities, and in many cases providing the pathway to realise the benefits. The difficulty is generating the database of plant data necessary for a benchmarking exercise. Larger companies can benchmark internally; this option is not available to smaller companies, and the full value can only be realised with a comprehensive “industry wide” approach.The Gold Technology Group at Curtin University through the AMIRA P420 series of projects has undertaken several comprehensive metallurgical industry surveys in the gold industry over the last two decades. Analysis of these surveys has demonstrated areas where many operations can benefit from re-assessment of their operating practices.This paper will review the work undertaken by the Group in this area, in particular the 1999 surveys of gold companies in the Australasian region, and the 2012 international survey of the industry. The challenges of, and opportunities arising from these surveys will be discussed. Some of the highlights from analysis of these databases will be presented as well as noting changes in processing practices observed by the Group over the last 20 years.CITATION:McGrath, T D H and Staunton, W P, 2018. Keeping up with the Joneses – the value of industry surveys and benchmarking, in Proceedings 14th AusIMM Mill Operators' Conference 2018, pp 509–516 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 29, 2018

By BO HYUN KIM, MARK K. LARSON

The floor-heave and no-floor-heave phenomena at a western U.S. coal mine could not be properly simulated in numerical models using conventional shear-dominant failure criteria. Although the previous numerical study using FLAC3D very reasonably demonstrated these phenomena, 3DEC modeling in conjunction with the discrete fracture network (DFN) technique was performed to better understand the true behavior of floor heave associated with underground mining in an anisotropic stress field. As a result, the latter models predicted floor heave that agreed with relative amounts of observed heave from each gateroad system, but the cause of heave was mainly related to the degree of anisotropy instead of the size of the pillar.

Sep 1, 2022

By T. J. Fenner

Surface and underground mining operations are often hindered by unknown tunnels and stopes and the precise locations of adjacent workings. Mine safety and planning are adversely affected especially in previously undermined areas where historical records are incomplete or non-existent. The results of several Ground Penetrating Radar (GPR) studies for the detection of known mine tunnels in underground coal; salt, and gold mines are presented. A case study to locate unknown, abandoned mine workings at a surface gold mine successfully located all workings to a depth of 11 meters.

Jan 1, 1992

By Pengfei Wang, Guorui Feng

With increase of cover depth, dynamic incidents, such as large gateroad convergences and coal bursts, are frequently encountered when mining deep longwall panels. It would be more adverse due to large inclination of the coal bed. Because of the shearer and armored face conveyor (AFC) sliding downhill, toppling of shields, disconnection of AFC to the stage loader are related to it. Tangshan coal mine is a typical deep, inclined coal mine situated in the east of China. The split-level longwall panel layout is being adopted for mitigating problems above, where tailgate entries of longwall panels are driven below gob edge and along the floor, while headgate entries are driven along the roof. Wire mesh and steel sets have been used empirically for support for tailgates for about a decade, which reduces the tunneling speed. In view of this fact, the paper serves to investigate the proper adjustment of the tailgate locations and to analyze the resulting stress and yield conditions according to support strategy. First, field measurements and observations were carried out. Stress data distributed within surrounding rock mass were obtained, especially within the roof since the roof consists of only a coal sheet with a thickness of 2–4 m. Roof pressure of the tailgate represents the pressure at the gob edge since it is below the gob edge. The convergence data were also collected. Numerical modelling using FLAC3D™ was conducted and validated by side abutment stress data. The double-yield constitutive model was used to simulate the gob. The finalized tailgate layout and design were determined through comparison of three scenarios. The research in this paper can help engineers choose the proper tailgate layout and support strategies for coal mines that are going to adopt a split-level longwall panel layout for mining deep, inclined longwall panels.

Jan 1, 2018

By M. Melih Demirkan, Jared Deible, Michael Rosenmeier, Mazen Elias Adib, Juan J. Gutierrez, Raghav Ramanathan

Dewatering and groundwater control is required frequently for construction projects and needs to be accounted for and dealt with care during design and construction to complete the project successfully. Dewatering can cause changes in porewater pressure, which changes the effective vertical stress in a soil mass. Dewatering can also cause changes in groundwater chemistry which in turn can cause changes in porewater pressure and also dissolution of soluble minerals in the soil and rock. The Guideline developed in this study addresses the engineering issues, approaches to lessen the potential risks associated with construction dewatering, and presents dewatering practices to support dewatering applications regulated by the Municipality of Abu Dhabi City (ADM) in the United Arab Emirates (UAE). The subsurface condition within the city presents significant geotechnical problems due to presence of shallow subsurface cavities and soluble minerals in the soil and rock. Therefore it is critical to develop standards for dewatering practices to provide information for local dewatering engineers and contractors with special emphasis to control and to eliminate the subsidence/collapse problems related to dewatering projects within the Abu Dhabi city. The ADM is also responsible for approval of permit applications for projects that involve dewatering. In order to minimize the risk related to subsidence/collapse problems due to dewatering, construction companies and dewatering contractors need to be informed about possible mitigative measures that can be employed to reduce risks. The guidelines were developed as part of this study based on detailed analysis of the local subsurface conditions. A set of rules and regulations are developed for geotechnical and hydrogeological investigations, dewatering design and monitoring criteria depending on the hazard zones, proximity of excavation to critical structures, excavation depth. The Guidelines include examples of permit application packages for three types of dewatering projects; one involving shallow dewatering, one involving intermediate depth dewatering, and one involving deep dewatering. These Guidelines are considered as living document and will be updated as required, as additional information is collected and additional local experience is gained.

Jan 1, 2016

By Stênio Cavalier Cabral

O diboreto de titânio (TiB2) é um material cerâmico de alta dureza com uma grande potencialidade de aplicação tecnológica. Neste trabalho, foi empregada uma técnica de processamento em altas pressões e altas temperaturas para produzir compactos de TiB2 com AlN. Os pós utilizados foram misturados manualmente em quantidades de 70%p TiB2 + 30%p AlN. Amostras cilíndricas, com 5 mm de diâmetro e 7 mm de altura, foram processadas durante diferentes intervalos de tempo compreendendo os ciclos de sinterização, cada ciclo de sinterização consistiu em aumento de pressão a aproximadamente 7 GPa a uma temperatura aproximada de 1500°C por um tempo de 180 segundos, para cada ciclo. O número de ciclos variou de 1 a 5. O objetivo do trabalho foi a identificação do efeito da quantidade de ciclos sobre a microestrutura e sobre as propriedades mecânicas dos compactos. Para estas observações foram realizadas analises de Difração de Raios X, Microscopia Confocal a Laser, Microdureza Vickers e ensaio de flexão. Os resultados obtidos apresentam perspectiva de utilização do processamento em alta pressão e alta temperatura para produção de compactos de alta qualidade como o TiB2- AlN.

Aug 16, 2017

By R. E. Burleigh

'Gold-telluride mineralization was deposited in quartz veins which cut a Late Cretaceous tonalite pluton emplaced near the southern margin of the Peninsular tectono-stratigraphic terrane in south-central Alaska. The gold-bearing veins formed shortly after the development of a widespread Cu-Mo sheeted quartz vein system. Early mineral assemblages consist of quartz, white mica, pyrite, and arsenopyrite (wall rock only). Subsequently, pyrite. sphalerite, chalcopyrite, zoned tetrahedrite and gold precipitated within multiply fractured veins. Late stage galena, tellurides (altaite, nagyagite, coloradoite), and Pb-Sb or Pb-Cu-Bi sulfosalta with gold constitute bonanza ore assemblages that are variably associated with quartz, white mica, ankerite, and calcite. Fluid inclusion evidence coupled with mineral assemblage paragenesis suggests the depletion of volatiles (C02, H2S) and cooling resulted in the precipitation of high grade gold mineral assemblages.

Jan 1, 1988