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By PEILIN LAN, LEONARD HILL, SIMON TIMBILLAH, BERNARD FOSU, CESAR SOSA-BLANCO

The use of sodium hydrosulfide (NaHS) in most of the operations in by-product molybdenum flotation comes with safety concerns and, in some instances, a high reagent cost. Engineered solutions at the various operations where NaHS is used have reduced the possibility ofH2S gas evolution immensely. However, the threat of exposure remains, and this, coupled with the high dosages of NaHS consumed, supports the continued search for alternative depressants. This paper focuses on efforts to study the applicability of disodium carboxymethyl trithiocarbonate (DCMT), an organic depressant, as an alternative to NaHS. Benchscale rougher flotation results for samples from the Sierrita Cu–Mo plant showed the best DCMTperformance at 8 kg/t of DCMT and pH=10.5 with 30 min of shear conditioning and 10 min of flotation conditioning time. The Aminpro plant model simulation confirmed that DCMT with 4–8 kg/t under certain shearing and conditioning times achieved superior or equivalent Mo–Cu separation efficiencies when compared to NaHS.

Apr 19, 2021

By Angelo Ferreira Costa

O laminador a frio de inoxidáveis LB1 da Aperam South America é um laminador Sendzimir reversível que produz materiais alta exigência de qualidade superficial destinados a aplicações nobres como baixelas, mesas de fogão e portas de geladeira de alto luxo. O rendimento físico destes materiais passou a ser comprometido com a identificação de um defeito caracterizado por pequenas marcas, sem presença de óxidos ou inclusões que ocorrem ao longo da bobina, nas duas faces e na borda do lado de acionamento do laminador. Nos anos de 2009 a 2010 o defeito ocorria em 45% da produção de materiais finos de aços 430 processados no LB1. O defeito passou a ser codificado como S163 – Marca Mecânica Laminada. Para abordagem ao problema foi reunida equipe multifuncional com representantes das áreas de Operação, Manutenção, Metalurgia, Inspeção, dentre outras, utilizando a metodologia de Domínio Integrado do Processo (DIP). Após a análise das causas e a implantação dos planos de ação do projeto, houve o decréscimo acelerado da ocorrência do defeito. A causa fundamental do defeito foi caracterizada como o desalinhamento da desbobinadeira, provocando um efeito de empeno lateral no material durante a laminação do primeiro passe. Em Agosto de 2012 houve a primeira intervenção de correção na desbobinadeira do LB1, reduzindo os índices de ocorrência do defeito para 11% no mês de Setembro de 2012 e posteriormente reduzindo para percentuais inferiores a 1% a partir de Janeiro de 2013, superando as metas propostas para o projeto.

Jul 30, 2018

By Amélia de Santana Cartaxo

A pedra cariri, devido a sua extração, produz um alto teor de formação de sobras, o qual polui muito os arredores dos municípios, prejudicando rios e relevos da região. O presente trabalho tem como objetivo caracterizar o resíduo da pedra cariri, juntamente com uma argila para propor seu uso na formulação de blocos de vedação. Inicialmente a pedra cariri e a argila foram beneficiadas. Estes materiais foram submetidos a um ensaio de plasticidade pelo método pfefferkorn, e posteriormente á analises de difração de raios-x e de fluorescência de raios-x, para saber suas composições mineralógicas. Através da fluorescência e da difração de raios-x comprovou-se que a pedra cariri possui um teor elevado de CaO(89,0%), que ajudará na densificação da peça e no abaixamento da temperatura de queima, e que a argila tem um percentual bom de sílica livre, que ajudará na eliminação do gás CO2 decorrente da decomposição térmica do carbonato presente na pedra cariri, ajudando também na estabilidade dimensional da peça. Pelas analises feitas, percebe-se um potencial de uso da pedra cariri na formulação de massas para fabricação de blocos de vedação.

Aug 16, 2017

By G. V. Theja, V. B. Maji

Large infrastructure projects like tunnel excavations, underground constructions face innumerable risks. For successful completion of these projects, it is essential that we foresee and understand risks that could occur during different phases of the project. One of the risks affecting underground excavation projects is the inaccurate performance prediction of TBMs. As this could severely affect the project, resulting in lower advance rates and could also result in changing the excavation machine or method, due to difficulties in excavation, thereby increasing the overall cost of tunnelling. This makes performance prediction of the TBMs as one of the crucial aspects in tunnelling, as a precise estimation of its performance is required for planning and estimation of time and cost of the tunnelling projects. This performance prediction of TBM is a challenging geotechnical problem that is intricate and complex in nature, this is possibly due to the fact that TBM performance prediction involves understanding the rock fragmentation process in wide range from micro-scale (i.e. the interaction of surface of rock material and cutter tip) to macro-scale (including the interaction of rock mass and TBM). Thus in order for the performance prediction model to be efficient, parameters of both TBM specifications and ground conditions have to be considered. Various models have been proposed by researchers since the early phases of TBM application, these studies resulted in the development and improvement of numerous penetration prediction models. Most of these models consider the geotechnical parameters that are input to the model to be consistent along the TBM drive and neglect the uncertainties in parameters that occur. And so to improve the predictive capability of these models and to incorporate the above uncertainties, the penetration rate is modeled as a stochastic variable depending on the geotechnical and TBM parameters, its statistical distribution is determined and is used to characterize the penetration rate instead.

Jan 1, 2015

By J. G. A. Stevenson

"IntroductionDURING the past quarter of a century diamond drilling, in all its phases, has increased in Canada to a very impressive total of more than 10,000,000 feet annually. Since the art of diamond drilling became recognized, some seventy-five years ago, there has been considerable improvement in both equipment and technique. The steam-powered drill rig and the hand-set diamond bit are things of the past.The purpose of this paper is to review some drilling trends •and practices over the past few years. In the preparation of the paper, the author wishes to acknowledge kind assistance of Mr. J. D. Cumming, Dr. C. H. Hitchcock, Mr. Robert H. Quintal, and many others, including staff members of the Longyear organization.Figures provided by the Dominion Bureau of Statistics for the year 1954 show that Canadian production of metallic and non-metallic minerals and structural materials had a value of $1,454.2 million, excluding radioactive products for which figures are not available. Approximately 61 per cent of this valuation comprised production of nickel, copper, gold, coal, asbestos, zinc, lead, and iron. It is certain that diamond drilling played a major role in the discovery and development of the orebodies from which these minerals were obtained.After the surface examination of an ore deposit, diamond drilling will automatically follow, in order to determine structure, grade, and tonnage.Footage drilled by mining companies and contractors on mineral exploration and blast-hole work since 1945, as reported by the Do-minion Bureau of Statistics, is shown in Figure 1."

Jan 1, 1955

By J. C. Heter

Industrial Mineral Fillers, LLC. is in the initial stages of mining and processing Anorthosite (CASPAR TM) at its CASPAR mine located in Soledad Canyon, Los Angeles County, California The CASPAR is being mined from the Precambrian San Gabriel Anorthosite Complex of the western San Gabriel Mountains. Preliminary results suggest that CASPAR is a desirable alternative to silica sand used in construction applications, such as, stucco, grout, abrasives, and other uses including filtration and golf course recreation sands. With the use of standard ore dressing techniques, CASPAR is suitable for use as a filler in paint, plastics and rubber. Environmentally, CASPAR has advantages over silica sand, in that, there is no detectable Free Silca.

Jan 1, 1997

By P. Dinham, G. C. Summerton, N. McCulloch, S. Dowling, D. C. Craig

"Development of a process for the treatment of a nickel copper matte rich in the minerals heazlewoodite, chalcocite and bornite has demonstrated significant base metal recoveries and metal separation efficiencies. The determination of chemical and mineralogical changes occurring in the individual leaching stages in laboratory experiments has enabled a better understanding of the complex leaching chemistry. The chemistry and mineralogy of the piloting and laboratory processes are discussed.INTRODUCTIONThe nickel-copper sulfide ores of the South African Bushveld Complex are among the most important Platinum Group Metal (PGM) bearing ores, and contain the world’s largest reserves of platinum. The treatment used in the recovery of PGMs from these ores includes three types of processes, namely ore concentration using physical techniques such as flotation and gravity separation, concentration by pyrometallurgical means, hydrometallurgical extraction of the base metals followed by the PGMs. Following milling of the ore, flotation involves the separation of high value minerals from gangue by taking advantage of the differences in their hydrophobicity. These differences are generally maximized through the use of a surfactant or wetting agent. Concentrates are then thermally treated and melted which brings about physical and chemical changes that enable the recovery of base metals and PGMs. The main aim of the smelting and converting process is to separate and eliminate the valuable metals from the bulk of the unwanted gangue and essentially all of the iron and to concentrate the metal VALUES (into a high grade converter matte. The matte can be further enriched by magnetic separation, producing a PGM-rich magnetic fraction and a base metal-rich non-magnetic fraction. The magnetic fraction is treated by hydrometallurgical processes to produce a PGM concentrate which is further refined to separate and purify the individual metals. The non-magnetic fraction is treated to produce marketable metal VALUES (such as nickel, copper, cobalt and to a lesser extent PGMs. The principal objective of any hydrometallurgical extractive process is to leach the desired elements selectively into an aqueous phase so as to separate them from the bulk of the material. (Crundwell, Moats, Ramachandran, Robinson and Davenport, 2011; Hundermark, Mncwango, de Villiers and Nelson, 2011)."

Jan 1, 2012

By J. Kretschmann, H. Mischo, O. Drusche, S. Krause

Mining is and will be inevitable in spite of the increasing implementation of circular strategies. The energy transition and population growth will boost the demand for critical raw materials. It is the opportunity for miners to reinvent their business models. Generating attractive new business cases with sustainability-oriented innovations meets investor and stakeholder expectations from the beginning. This contribution guides managers on their pathway towards sustainable success. Contextual sustainable business model patterns will be presented that can be adjusted individually, regardless of actor’s size. It will also point out, how sustainable value creation can be measured on business model level.

Feb 1, 2023

By K. H. Nimerick

Laboratory data and field tests indicate that substantial losses of valuable coal can be caused by wind erosion. Wind tunnel tests show the effects of wind velocity and particle sizing on the amount of coal lost while in transit. Different coals were evaluated to determine the variables associated with wind erosion. The erosion losses can be substantially reduced by using a binder, or crusting agent, to consolidate the surfaces of the coal into a solid mass which resists erosion. This not only reduces economic loss but minimizes pollution.

Jan 1, 1977

By Jon A. Carlson, W. Scott Williams

The EKATI"" Diamond Mine commenced operation in October 1998. It is operated by BHP Diamonds Inc., which is a part of the Non-Ferrous and Industrial Materials Division of BHP Minerals, a business unit of BHP Company Ltd. of Melbourne, Australia. The EKATI"" Diamond Mine is a joint venture of BHP Diamonds Inc. (51%), Dia Met Minerals Ltd. (29%), Charles E. Fipke (10%) and Dr. Stewart L. Blusson (10%). In December 1993, an office was opened in Yellowknife, Northwest Territories specifically for the then Northwest Territories Diamonds Project (EKATI"" Diamond Mine) development. EKATI"" Diamond Mine is located 300 kilometres northeast of Yellowknife and 200 kilometres south of the Arctic Circle in the Northwest Territories of Canada (Figure 1 ). The site is located in a remote tundra area of continuous permafrost, north of the tree line, which is part of the Canadian Shield. Wekweti (Snare Lake), a Dogrib community approximately 180 kilometres southwest of the project, is the closest neighbour. The mining area and facilities lie within the 10 960 hectares land leases held by the joint venture. The total claim block (core zone and buffer zone joint ventures) covers 344 000 hectares. To date, more than one hundred kimberlite pipes have been identified within the claims. Five of these provide the basis for the present mine plan. Total capital investment in the project is over C$700 million. At full production employment will be about 600, including employees and long-term contractors, with over 33% being Aboriginal from the Northwest Territories.

Jan 1, 2001

By W. M. Myers

"The continued expansion of modern industry broadens the markets for minerals and their product. With these increasing demands new uses are being found for minerals that heretofore were considered as possessing no commercial possibilities. This tendency is reflected in the nonmetallic field in a constantly increasing demand for minerals formerly considered to be of scientific interest only, Furthermore, nonmetallic minerals of established commercial importance are used in new ways in various products, and this tends to expand the markets for these minerals. Some recent outstanding developments in applications of minerals are given in the following pages.The Andalusite GroupAmong the minerals that until recently were considered of scientific interest only, may be listed those of the andalusite group. This group is composed of the three minerals, andalusite, cyanite (or kyunite), and sillmanite, which are all forms of the compound Al2SiO5 (A1203, S1O2), and are therefore identical in chemical composition, but differ in physical properties,"

Mar 1, 1924

By C. C. Merrill

Studies were made to determine the amenability of yttrium to fused-salt electrorefining in a controlled atmosphere. Tests were conducted in a LiCl- YCl3 electrolyte system at 710° C. The major variables studied were the YCl3 content of the electrolyte, from l.7 to 13.4 mol percent, and the initial cathode current density, from 410 to 1,630 amperes per square foot. Vacuum distillation was employed to remove salt from the deposited metal. Metallic impurities, except for lithium, could be reduced to near or below their lower analytical limits, ranging from 10 ppm for Cu to 300 ppm for Ta; reduction of oxygen content, however, was accomplished only in metal produced from electrolytes with 5.4 mol percent YCl3 or less. Initial cathode current density had little effect on the purity of the product.

Jan 1, 1967

By R. H. Lien

The Bureau of Mines investigated nitrous oxide (N20) stability when used as a solvent for organic removal from metal powder surfaces. Both supercritical and subcritical conditions were studied. This investigation was prompted by the occurrence of a violent reaction when supercritical N20 was being used to deoil a metal powder grinding waste sample that contained 20 to 25 wt pct cutting oil. Tests were conducted to determine the cause of the reaction and to define stability limits. Test data showed that the waste's oil fraction reacted violently with N20 acting as an oxidizer; the metal powder acted as a promoter to reduce the ignition temperature. Although the data were scattered, this temperature appeared to reach a minimum at a certain pressure (dependent on vessel and sample size). The minimum ignition temperature for a 0.64-g sample in a 72-cm3 vessel was 360° C at 200 psig. As the sample size increased, the ignition temperature decreased. For example, when the sample size was increased to 10 g, a reaction occurred at 240° C and 600 psig. Because of the variability of ignition temperature with pressure and sample size, safe operating conditions were not established. Overall, this research showed that extreme caution should be exercised when using N20 in an organic or organic-metal system.

Jan 1, 2011

By Keli Vanessa Salvador Damin

Este trabalho apresenta uma nova abordagem sobre o emprego sequencial dos tratamentos termoquímicos de superfície utilizando a tecnologia de plasma. No trabalho são avaliados tratamentos de superfície, individuais e sequenciais, de nitretação/cementação. Os tratamentos foram realizados no campo ferrítico com o objetivo de manter as tolerâncias dimensionais. Amostras de aços AISI 1005 foram tratadas em descarga luminescente anormal sendo realizados ciclos únicos de cementação e nitretação e também ciclos conjuntos de nitretação + cementação. Todos os tratamentos foram realizados a 500°C com um tempo de patamar de 3 horas para cada tratamento. A composição da mistura gasosa variou de acordo com o tratamento: nitretação - 5%N2 + 95%H2 ou 3%N2 + 97%H2; cementação - 5%CH4 + 95%H2. A caracterização microestrutural das amostras foi realizada por microscopia óptica e MEV além de difração de raios-X. Análises de microdureza também foram realizadas. As analises de raios-X mostraram que ocorre a estabilização de uma camada de cementita nos tratamentos de cementação. Nas amostras nitretadas em atmosfera contendo 5% de N2 foi observada a presença de camada de compostos. Já em atmosferas contendo 3% de N2 não houve a formação da camada de compostos. A maior profundidade de endurecimento foi obtida para a amostra nitretada + cementada.

Aug 16, 2017

By V. Vakiloroaya

The paper aims at developing a hybrid solar-assisted air conditioner system for performance enhancement and energy efficiency improvement. To increase sub-cooling of the refrigerant at partial loads, we propose a new discharge bypass line together with an inline solenoid valve, installed after the compressor to regulate the mass flow rate of the refrigerant vapour passing through a hot water storage tank. For control design, a lumped parameter model is first developed to describe the dynamics of the system in an explicit form of input-output relationship. The system has been fully-instrumented to examine its performance under different operation conditions. The system model is then validated by extensive experimental tests. The predictions from the models exhibit a good coincidence with experimental results, judging by an RMS error less than 15%. Based on the obtained dynamic model, a linear quadratic regulator (LQR) is applied to optimize a cost function of the output errors and control efforts. The key challenge is to regulate the refrigerant temperature entering the condenser by controlling the valve opening. The design approach is then tested in a transient simulation tool to predict the system performance in transient conditions. The experimental results obtained from implementation with PLC demonstrate that the proposed system delivers higher system efficiency owing to the higher refrigeration effect in the direct expansion evaporator. Thus, the novel development is promising for improvement of energy efficiency, enhancement of the system performance while fulfilling the cooling demand. Consequently, between 25 and 43% of monthly electricity can be saved on average.

Aug 1, 2013

By Ariel José Assayag do Lago

O presente trabalho teve por finalidade analisar as tensões residuais, através da técnica de difração de raios-X, em amostras de cobre submetidas à laminação em temperatura ambiente. Foram obtidos e comparados os resultados de um software comercial com um software projetado pelos autores. O comportamento das tensões principais das amostras laminadas foi comparado com o resultado do material no estado recozido. Uma tendência de aumento de tração trativa no interior da amostra foi identificada. Os resultados obtidos seguiram um comportamento dentro do previsto pela bibliografia e os dois softwares utilizados acusaram valores similares, ratificando a aplicabilidade do método de difração assim como a funcionalidade do software desenvolvido.

Oct 30, 2017

By Shuren Wang, Wenbing Guo, Paul C. Hagan, Yanhai Zhao

"The overlying strata is often destroyed in large scale during shallow coal seam mining, and the sliding instability of the caved roof seriously threatens the safety of the mining field. The typical shallow coal mining in Shendong Mining Area in China was used as engineering background; the load distribution characteristics of the overlying strata were analyzed based on the monitoring data of the support resistance. Through theoretical analysis and numerical simulation, the formation and changing process of the pressure-arch in the overlying strata were studied, and the instability mechanism of the overlying strata was revealed by focusing on the accumulation and release law of the elastic energy in the pressure-arch. The results show that the continuous pressure-arch was formed when the horizontal stress exceeded the primary vertical stress of the mining field, and the elastic energy of the roof was released by the mining unloading effect. The elastic energy was accumulated in the pressure-arch, and the energy arrived the highest at the front arch foot. The accumulated energy at the arch foot was released by coal mining, and the shear zone could be formed. Therefore, the sliding of the caved zone along the shear zone induced strong roof weighting. The concentrated stress and the released energy during each mining increased with the panel advancing, and the height of the shear zone also increased. The conclusions obtained in the study are of important theoretical value to direct similar engineering practice.INTRODUCTIONThe instability of overlying strata during shallow coal mining, such as the large-scale roof falling and step-like ground subsidence, is a key problem that can restrict the safety mining in the mines (Ju and Xu, 2015). The self-bearing structure of the pressure-arch can form in the overlying strata after coal mining, and this structure can support the load of the upper strata and soil layer, so the weighting intensity of the panel is determined by the caved rock in the unloading zone under the inner boundary of the pressure-arch. A large amount of elastic energy is accumulated in the pressure-arch under the concentrated stress, and the released energy for mining is the internal cause of rock failure (Wang et al., 2017). It is an important problem to reveal the distribution characteristics of the stress and energy fields in the mine and to analyze the stability of the overlying strata during shallow coal mining based on the evolution characteristics of the pressure-arch."

Jan 1, 2018

By Wilbur I. Duvall

A linear array of shot and gage holes 30 feet deep in a granite outcrop was used to compare the size and shape of radial strain pulses produced in the rock when short cylindrical charges of cast composition B were detonated axially or at one end. The axially detonated charges produced radial strain pulses that had shorter rise times and larger peak strain than the strain pulses produced by end detonated charges.

Jan 1, 1965

By M. E. Huckman

In this paper, we review the equations needed to construct an ion exchange column model. These models contain three major components: 1) a differential material balance around the colunm, 2) a differential material balance around an ion exchange particle, and 3) a constitutive equation for diffusive flux We then examine the ability of a fairly simple mathematical model to predict ion exchange column experimental data. This model contains the traditional absorption theory equations and is used to predict the behavior of a column filled with a hydrous crystalline silico-titanate and which is removing trace amounts of Cs+ from a high pH, complex electrolyte solution. Finally, we propose replacing Fick's law with the Nernst-Planck equation as the constitutive equation for diffusive flux We use a Nernst-Planck type model to predict batch experimental data, then evaluate it by comparing it's ability to predict experimental data to that of a more traditional Fick's law type model? The data from this comparison suggests that the Nemst-Planck type model yields better results.

Jan 1, 1996

By Baozhong Ma, Qian Li, Yonggang Wei, Shiwei Zhou, Bo Li, Chengyan Wang, Hua Wang

The magnesium-rich nickel oxide ore (w (Ni) =1.09 %, w (MgO)=29.08 %) mixed with 6 % and 8 % anthracite were roasted at different temperatures. XRD and SEM/EDS techniques were utilized to characterize the phase and microstructure transformation of the ores. The results show that lizardite and chrysotile of raw ore were converted into forsterite and enstatite during reduction roasting process. Simultaneously, iron and nickel oxide were reduced and migrated from the initial magnesium silicate. Fe3Si were formed when the roasting temperature went up to 1300 ℃ and 1350 ℃, and a small amount of Ni was observed in it. Temperatures got too high were not benefit to the polymerization of ferronickel.

Jan 1, 2015