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By Dong Liang, Qijie Zhai, Zhichen Zhang, Qixin Li, Zhishuai Xu

"The formation, distribution and survival of pure Al nuclei under surface pulsed magneto oscillation (SPMO) treatment were investigated with thecombination of experiments and numerical simulation. The results indicated that the nuclei originated from the whole top surface of melt owing to the oscillation of top surface induced by SPMO. The temperature field significantly affected the survival of the nuclei The electromagnetic force and flow field of the melt with SPMO treatment were simulated by finite element software ANSYS. The electromagnetic force mainly distributed below the top surface near the mould wall. The electromagnetic farce not only made the melt oscillate but also increased the convection of meh below the top surface vigorously. The oscillation near the top surface of the melt promoted the nucleation largely, and the convection increased the uniform of the temperature distribution in the whole meh which favored the survival of nucleiIntroductionAs we all know, fine equiaxed grains are beneficial fur the improvement of the mechanical property, process ability and the uniformity of metallic materials [1-2]. With the researches of recent decades, people discovered that the electromagnetic field is an efficient method to refine the solidified structure of metals [3-7]. Pulsed magnetic field technology obtains more and more attentions in recent years due to its smaller power consumption, bigger instantaneous magnetic field intensity, non-contacting with the meh and simple convenient equipment manufacturing [8-9]. However, the melts would splash fiercely when pulsed magnetic field is applied with a slightly higher power. Thus, based on the understanding of the solidification refinement mechanism of electric current pulse (ECP) [10], Gong et al [11] developed a novel technology called pulse magneto-oscillation (PMO) to refine the solidification structure. The technology can be easily applied in the solidification structure refinement of continuous casting slab. But fur aluminum continuous casting, the sump is very shallow, which greatly limits the application of pulse magneto-oscillation technology."

Jan 1, 2014

By A. A. Iranzadeh

The performance of a tunnel boring machine (TBM) depends on the efficiency of the cutters, which can be influenced by geological conditions and rock mass properties. In this study, a three-dimensional numerical model, based on a discrete element method, was used to evaluate the effects of joint orientation and its spacing on the fragmentation process by a TBM cutter. Several models were constructed to study the effects of variable orientation; these models incorporated different spacing, variable spacing, different orientations on the fragmentation process, and different sections of the block model. Three parameters, consisting of induced tensile stress, induced shear stress and maximum displacement, were calculated. The stress in each section that forms chips was considered as critical stress; critical joint spacing and orientation in each section were determined. Results show that the critical orientation was in the range of 45 to 60º, where there was a possibility to achieve the maximum penetration rate. The critical joint spacing was 200 mm and, by increasing joint spacing, the value of critical stress decreased significantly. Furthermore, joint orientation could influence more than joint spacing in the rock cutting process.

Jan 1, 2009

By G Wyartt

In the Pilbara region of Western Australia, an iron ore mine is undertaking a high wall cut-back to improve stability and allow access to deeper ore deposits. Several sections of the wall have been classified low factor-of-safety due to unstable localised geology, and therefore an engineered approach to vibration critical blasting was required. The use of electronic detonators allowed multiple signature (seed) holes to be incorporated into a production blast adjacent to the low factor-of-safety area, therefore providing baseline vibration data to be used for future modelling with the added advantage of eliminating unnecessary pit closure downtime typically associated with a signature hole program. All subsequent blast patterns also incorporated multiple signature holes to provide additional data and allow continual updating – and therefore improved accuracy - of the blast prediction model. Electronic detonators and blast initiation systems were combined with advanced blast vibration modelling software to produce optimal timing sequences with predictable vibration outcomes. Although minimising vibration was the primary focus, blasting induced frequency was also a concern for the project team and therefore initiation sequencing was optimised to also avoid undesirable frequencies. Minor variations in ground factors (vibration transmission and attenuation) were noted, and therefore justified the inclusion of regular signature holes which allowed continual vibration model updates. Blasting results produced vibration and frequency measurements within allowable limits and closely resembled the predictive model. These positive results were achievable through the combination of electronic detonators, advanced modelling software and good onsite practices by engineering and on-bench teams alike. This project will remain ongoing as the pit progresses to deeper benches, and therefore the same methodology will be applied; quality and continual data collection, the use of electronic detonators, and optimisation via advanced vibration and frequency modelling software. CITATION:Wyartt, G, 2018. Vibration control blasting for low stability final walls, in Proceedings The Fourth Australasian Ground Control in Mining Conference (AusRock), pp 504–510 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 30, 2018

By G. Pahomova

"It developed an alternative to traditional flotation enrichment refractory of complex lead-zinc ores to obtain conditional lead and zinc products. The scheme involves the use of the processing method of gravitational enrichment of the primary cycle and the combined gravity-flotation-hydrometallurgical in finishing. The method has a high level of comprehensive utilization of mineral raw materials in relation to the elements that are extracted in the process of enrichment in lead concentrate, and the increase in recoverable value of processed ores. INTRODUCTION The primary source of lead are complex sulphide lead-zinc ore, lead ore actually rarer. The value of lead and zinc ores (except lead and zinc) is determined by the presence in them of a wide range of associated components: silver, contained mainly in galena; gold; bismuth in the form of its own minerals, but is associated with galena; cadmium contained mainly in the sphalerite; indium, thallium and gallium contained in sphalerite and galena; selenium and tellurium are present as impurities in the sulfide, tellurium is also found in the form of its own minerals. Of note harmful impurities antimony, which is often associated with lead sulphosalts and arsenic, having a substantially own minerals. By quality (content of lead, or the total content of lead and zinc) lead-zinc ores are divided into rich, ordinary and poor; by oxidation - to sulfide (with a lead oxides content less than 15% and zinc oxide content less than 10%), mixed and oxidized (50% oxide); the latter have a subordinate importance as a source of zinc and lead. Traditionally, the most contrasting technological properties of sulfide ores of nonferrous metals considered flotation properties, which determines the priority in the selection of flotation technology of their enrichment. Other methods of enrichment - gravity (jigging and enrichment in heavy suspensions), radiometric sorting (separation) are used as preliminary operations whose main purpose is to increase the content of lead and zinc in the ore sent to flotation, as well as the removing of part of empty rock in dumping tails prior to flotation. Effective implementation of these methods is possible at large size emphasizing in the ore of lead and zinc minerals, which is typical of the rich ores and which so far mainly worked. At the same time, non-ferrous metal ores (polymetallic, lead-zinc, copper-zinc, etc.) have a sufficiently high contrast to gravitational properties since ore minerals have a higher density compared with a rock minerals. But the gravity of the practice of non-ferrous ores enrichment is not widely used, despite its high degree of environmental safety and lower cost expensive."

Jan 1, 2018

By G van Niekerk, M Wortley

Screening is a critical part of many mineral processing circuits and keeping the aperture of the screening media within specification is vital to ensure efficient performance of the processing plant. Typical ways of estimating and/or measuring the wear of the screening media vary from very subjective methods (for instance, using the human eye) to manually checking the width of a few of the more severely worn gaps with a measurement device. Subjective methods can be flawed by human error while manual checking can distort the polyurethane or rubber materials that are used in several types of screening media. All of these errors can cause either premature replacement of panels or, even worse, poor screening of the material.Metso Process Technology and Innovation (PTI) and Metso Screening Media Solutions (SMS) have developed an innovative method that measures screen aperture using advanced image processing techniques. Field trials of the device are presented in this paper, which shows the comparison between the different methods of measuring apertures. Case studies demonstrate how the system, when combined with ScreenTrack, MetsoÆs industry leading maintenance system, and screening media, is providing users with the best possible screening solutions.

Sep 26, 2011

By Bruno Miranda Ribeiro

Foi verificado que em uma das prensas de rolos (HPGR, High Pressure Griding Rolls), das usinas de pelotização de Tubarão, estava ocorrendo escorregamento do minério entre os pinos (studs) ocasionando um desgaste excessivo no rolo e desprendimento dos pinos. Este fato levou ao desenvolvimento de uma solução para eliminar o problema através da utilização de um produto que contivesse as características necessárias para conter o desgaste e prolongar a vida útil do rolo, sem comprometer a performance da prensa. As etapas para solução do problema passou por uma definição da escolha do produto, preparação da superfície do rolo e método de aplicação. Após implantada a solução, foram comparados os resultados antes e depois da aplicação do produto. Os resultados mostraram que o objetivo foi alcançado quanto a retenção dos pinos, controle do desgaste e manutenção da performance de processo desta prensa.

Aug 16, 2017

By Paulo de Tarso Rossi Haddad, Eric Valmir Spósito, Cristiane Sales Gonçalves

The heat treatment is a process that acts as a key factor in the tool life of tools made with hot work tool steels. Due to their applications, the main desirable metallurgical properties of this material class are toughness and hot resistance, without which the tools may suffer premature failure, and may lead to increases in the cost of producing articles made using such tools [1, 2]. Therefore, special attention must be given to the heat treatments practiced in these steels, whose operations involve quenching and tempering. The present work carried out the effects of the austenitizing and tempering temperatures on the microstructural condition, hardness and impact properties of TENAX300IM®, modified AISI H11 with lower silicon content. Hardness was measured by the Rockwell method, C scale; the toughness was evaluated by the Charpy-V impact test; and the microstructure for each condition was evaluated by optic microscopy. It was shown that higher austenitization temperatures resulted in increased grain size and hardness; higher tempering temperatures resulted in reduction of hardness, and secondary hardening peaks were observed for some austenitization conditions. The impact resistance showed an inverse behavior to that of the hardness, remaining initially constant, up to ~ 550 ° C of tempering temperature, and then increasing with the tempering temperature. The microstructures presented great dissimilarity, mainly due to the dissolution of carbon and alloying elements in the matrix.

Nov 22, 2018

By D Pearce

The 15-year long debate between the industry, Government and Aboriginal people about the rights and wrongs of Land Rights, the right of Aboriginal people to control development on their land and the relationship between the parties, has been long and often bitter. It has so far been a war of words and often the truth has been the first casualty. This paper looks at the debate and presents the perspective of Aboriginal people, as well as looking at how the industry and Aboriginal people can work together for everyone's benefit. It addresses such matters as: ò why Aboriginal people believe they have the right to control development on their land; ò the perception that Aboriginal people are anti-development; ò the perception that Aboriginal land is 'locked-up'; and ò how companies can negotiate with Aboriginal people.

Jan 1, 1994

By Qingguo Xue, Jingsong Wang, Guang Wang, Yuanyuan Zhang

Due to complicated structure and composition of high-phosphorus iron ore, pure substances were used to simulate the chemical composition of high-phosphorus iron ore to study the reaction of fluorapatite at different temperatures and effect of additives. The gasification process of P during carbothermic reduction process was investigated using a quadrupole mass spectrometer gas analysis. It is found fluorapatite was reduced to phosphorus which diffused into iron and gas phase. From the gas analysis, it was observed that PO and P gas species were vaporized around 800 °C. As the reduction temperature increased, the diffusion of phosphorus into iron was enhanced. The presence of Ca(OH)2 as additives not only promoted the reduction of iron oxide, but also decreased the degree of fluorapatite reaction to inhibit P into iron.

Mar 1, 2018

By Greg Sanders, Michael Gilbert, James G. Shaughnessy

"A new raw water intake from the South Holston River to the Kingsport water treatment plant is under construction. The exploration for the 335 meter long horseshoe shaped tunnel design took advantage of the site topography along the alignment to better define the complex geology consisting of Knox Limestone and Sevier Shale formations separated by a fault zone. To assess the geological conditions and to determine the extent of the fault zone, a 183 meter long horizontal boring and geophysical investigation was performed along a portion of the tunnel’s horizontal alignment. Explorations defined the fault zone width at approximately 5 meters and packer testing along the alignment provided a means of estimating groundwater inflows. As the tunnel excavation advances, comparisons of exploratory data versus encountered conditions will be made. This paper provides details on the geotechnical investigation, lessons learned, and the influence of the geology on the tunnel design. PROJECT OVERVIEW The Kingsport WTP is supplied with raw water via the South Holston River. The City of Kingsport (City) owns and operates the Kingsport Water Treatment Plant (WTP). The existing raw water intake system, consisting of pumps, power supply, raw water piping and appurtenant facilities has been determined to be vulnerable to failure. The original Raw Water Pump Station (RWPS) was constructed in 1928 as part of the original Kingsport WTP project. The 1928 RWPS operated until 1970 when it was replaced by the existing RWPS. This existing system still utilizes the 1928 piping and piping tunnel. Improvements to the RWPS hydraulics and capacity are required to meet the City’s future water treatment needs. The system extracts water from the South Fork of the Holsten River and coveys it via three pressure pipelines to the WTP. The conveyance piping exits the RWPS, ascends approximately 23 m up a near vertical rock outcropping then enters a 120 m long tunnel. Upon exiting the tunnel the piping continues underground to the WTP. The drill and blast tunnel is horseshoe shaped and nominally 3.3 m high by 3.3 m wide. The easternmost 62.3 m of the tunnel is without any type of support. The remainder is lined with concrete. According to the City of Kingsport, the concrete lining was installed in the 1970’s as part of upgrades to the facility. An evaluation of the current facilities concluded that the conveyance piping was in poor condition and required replacement."

Jan 1, 2016

By Isadora Maria Oliveira Anício Costa

Desenvolvimentos recentes no emprego de ligas NiTi superelásticas (SE) na confecção de instrumentos endodônticos rotatórios envolvem a aplicação de tratamentos térmicos nos instrumentos inicialmente produzidos a partir de ligas SE. Neste trabalho foi estudado o efeito de tratamentos térmicos e sua contribuição para a evolução das propriedades funcionais de um fio de NiTi SE. Os fios comerciais de NiTi, aproximadamente equiatômicos, foram ensaiados após o tratamento de recozimento por 1 hora, em temperaturas de 300°C a 500°C, e então temperados em água. A caracterização física do material foi realizada por calorimetria exploratória diferencial e as propriedades mecânicas foram obtidas em ensaios de tração e de recuperação de forma. Os resultados apontaram aumento nas temperaturas de transformação dos fios com o recozimento, o aparecimento da dupla transformação austenita - fase R - martensita B19’ durante o resfriamento. Observou-se também diminuição do módulo de elasticidade aparente e aumento da deformação residual com o aumento da temperatura de recozimento, indicando, em concordância com a variação nas temperaturas de transformação, que o material passou a apresentar o efeito memória de forma.

Aug 8, 2018

By C. Zhou, R. Jacksha

This paper reports measurement results for radio frequency (RF) propagation around 90° corners in tunnels and underground mines, for vertically, horizontally and longitudinally polarized signals. Measurements of signal power attenuation from a main entry into a crosscut were performed at four frequencies — 455, 915, 2450 and 5800 MHz — that are common to underground radio communication systems. From the measurement data, signal power loss was determined as a function of signal coupling from the main entry into the crosscut. The resultant power loss data show there are many factors that contribute to power attenuation from a main entry into a crosscut, including frequency, antenna polarization and crosssectional entry dimensions.

Jan 1, 2016

By Braden Lusk

A typical rural house surrounded by a surface coal mine was instrumented in 2008. Information regarding ground vibration, airblast, and sounds inside the house was collected. Previous publications have included conclusions about this data with regard to blasting source (far-field or near-field) and results as to how the residents experience the blast were made. Several events were also recorded that were not related to blasting due to the nature of the trigger system. The trigger of the monitoring system was attached to one of the mid walls of the house, thus other normal daily events produced vibration levels significant enough to trigger the monitoring system.

Jan 1, 2011

By Takefumi Takuma, Tsunenobu Nozaki, Masashi Nagano

Using sheet piles and pipe piles for permanent earth retaining is one of the most economical methods for constructing basement walls since they can also work as temporary shoring during construction. A major mixed-use redevelopment project in the UK, encompassing two to three large city blocks, utilized both sheet and pipe pile walls for a two-level subterranean parking structure. The 290m (950ft) x 100m (330ft) basement’s steel walls were designed to temporarily support excavation during construction and eventually to become a load carrying permanent structure in order to expedite the construction process and to achieve cost reduction. Two types of press-in piling machines, one for sheet piles and the other for pipe piles, were used for the job because of their abilities to press in sheet and pipe piles within tight tolerances for finished walls, for difficult installation conditions with very hard soil, and for its very low noise and practically zero-vibration operation; an essential factor for the job in close proximity to other businesses and residents. BACKGROUND Steel sheet pile and pipe piles have been used for many purposes including earth retaining. They are produced at steel mills and spirally welded at a fabrication yard to their corresponding specifications under strict quality control measures. Therefore, they can form highly reliable walls to its design capacity with proper installations. Their advantages as underground walls are:  They can form a high level of water cut-off function with their interlocks sealed by welding or with hydrophilic materials. See Figure 1 for a few examples for a sheet pile application.  They can carry vertical loading in addition to horizontal load and bending moment.  They can be a self-standing and temporary/permanent wall with flexible design and construction processes; bottom-up, top-down or hybrid sequences can be chosen per the project’s needs.  They can form a thinner wall than other wall types, creating larger inner space. See Figure 2.

Jan 1, 2019

By A Annor, L J. Chen

The production of paste backfill has typically been accomplished through the adaptation of existing technology. Thickeners and disc filters have several drawbacks when applied to production of tailings paste backfill. Personnel at CANMETÆs backfill research laboratory in Sudbury, Ontario, Canada have been carrying out research into and development of methods to produce paste backfill using total mill tailings since 1991. Using a silo for production of paste is not a new concept but has been refined to a marketable level. This technology is based on a fluidization principle that assists in settling the tailings to an homogenous state in a silo. Other developments include patented de-watering technology for use in the silo to speed the settling of the solids to a suitable solids content, optimisation of silo geometry, and instrumentation related to paste backfill production and transportation. The advantages to fluidisation technology are in reduced capital cost, reduced operating costs and in the environmental benefits of using full plant tailings over classified tailings or alluvial aggregates. Another major advantage is in the ability of this technology to be retrofitted to existing hydraulic backfill plants to further reduce capital cost. This paper details the development of the new technology as well as the associated cost savings over other technologies. It will also look at the research and development of unique components that make this technology work.

Jan 1, 1998

By Fabrício Domith Rodrigues, Marcelo Moreira Furst Gonçalves, Leonardo José Silva de Oliveira, Luiz Fernando Andrade de Castro

Eventualmente é necessário ajustar a largura de placas via processo de oxicorte. Contudo, o processo de corte convencional a frio não é recomendado para algumas qualidades de aço por gerar susceptibilidades às trincas na seção de corte. Para contornar a ocorrência de trincas no corte convencional foi desenvolvida e aplicada na Usiminas uma nova técnica de oxicorte em placas com base na utilização de duplo maçarico. Após otimização dos parâmetros de velocidade e posição dos maçaricos foi possível obter temperaturas da ordem de 200°C, homogeneamente distribuídas ao longo da seção de corte, favorecendo o ajuste dimensional sem trincas. Com a implementação industrial, verificou-se índices superiores a 85% de aprovação de placas e, consequentemente, o aproveitamento de placas que anteriormente não eram destinadas a geração de produtos laminados.

Oct 1, 2019

By W. A. Jacob, E. W. Dean

The Pittsburgh petroleum laboratory of the Bureau of lines has recently developed an improved method for the determination of water in pctroleum emulsions. It has been described in detail in an article entitled "A convenient method for the determination of water in petroloum and other organic emulsions" by E. W. Dean and D. D. Stark (Jour. Ind., and Enc. Chem. Vol. 12, ſay, 1920, page 436). It is essentially a modification of the familiar procedure of "distillation with an iniscible solvent", the improvement consisting in the use of apparatus that is rºck more convenient than any previously employed. The method has been used with marked success in the Bureau's laboratories for a period of about a year and has also been tried with equal satisfaction by a number of other laboratories. It has been most extensively employed for determining the water content of heavy fuel oils but has been applied also to several other types of emulsions, including shale oils, tars derived from coal, greases, and mixtures of powdered coal, oil and water. The Bureau has received a number of requests for information regarding commercial sources for the apparatus used, and having been assured of the value of the method, has taken steps to render it available for general use. - The equipment is, with the exception of two items, made of parts that are obtainable from the ordinary stock of chemical supply houses. The two exceptions are (1) the so-called "distilling tube receiver" and (2) the electric heater. The former is an essential part of the equipment; the latter is a convenient ac cessory but it can if necessary be roplaced by a gas burner. Efforts on the part of the Bureau staff to ronder these two items of apparatus available for purchase from supply houses, or for production by the user are hero described.

Sep 1, 1920

By E. Marè, D. R. Groot, R. Engelbrecht, T. Coetsee

Hydrogen peroxide is often used as an oxidising agent in experimental waste electronic equipment (WEE) leaching work. However, the high cost of peroxide is a negative factor in its consideration in further process development. A few studies have reported on the efficient application of peroxide addition schedules to ensure optimum reagent consumption. Large quantities of unleached substrate material contained in WEE feed material result in a large dead volume of material in the leaching reactor. This factor necessitates fast reaction rates to enable the use of a high feed material throughput reactor to enhance overall project viability via hydrometallurgical processing. In this study the effects of hydrogen peroxide addition schedules on base metal leaching efficiency and solution temperatures were tested at laboratory scale. The results showed that overall peroxide consumption can be optimised to lower levels by matching peroxide additions to the particular feed material’s leaching behaviour. A simplified integrated model for peroxide decomposition is used to explain its effect on solution temperatures and leaching rates. Keywords: Peroxide consumption, waste electronic equipment, copper leaching, integrated model

Jan 1, 2020

By Walter Gervásio Ladeira

O quartzito Taboões é uma fonte potencial de matérias-primas de sílica (areias industriais), e precisa ser adequadamente caracterizado para se definir metodologias de beneficiamento que visem o seu melhor aproveitamento possível. Dois litotipos foram classificados nos quartzitos intemperizados da Formação Taboões presentes em São Joaquim de Bicas – MG: quartzito argiloso e quartzito. A principal diferença entre eles é a abundância relativa de argilominerais. Em uma amostra representativa do quartzito argiloso foram caracterizados quatro tipos de contaminações com auxílio de análises granulométricas e químicas, microscopia (óptica e eletrônica de varredura), e difração de raios-X. Estas contaminações são: incrustações no quartzo; películas de argilominerais e minerais de ferro aderidas ao quartzo; partículas de minerais de ferro liberadas em meio ao quartzito; e partículas liberadas de rochas estranhas ao quartzito. A caracterização realizada é um ponto de partida para se planejar rotas de processamento mineral visando obtenção de matérias-primas para a indústria.

Aug 8, 2018

By P Stewart, S Cowie, A Offer, J Carpenter, E Jones

The Ban Houayxai Gold-Silver Operation is a producing asset for Australian-based copper and gold producer, PanAust Limited. The Operation lies within PanAust’s 2600 square-kilometre Phu Bia Contract Area in northern Laos. Commencing production in 2012, Ban Houayxai is operated by PanAust’s Lao-registered company, Phu Bia Mining. PanAust owns a 90 per cent interest in Phu Bia Mining. The Government of Laos owns the remaining 10 per cent. The Operation mines an intermediate sulphidation epithermal gold-silver deposit and comprises an open-pit feeding ore to a conventional carbon-in-leach process plant. Metallurgical recoveries for gold and silver are approximately 75-85 per cent and 55 per cent respectively. To year-end 2017, the Operation had poured 0.65 million ounces (oz) of gold and 4.7 million oz of silver. The Ban Houayxai Ore Reserve supports a mine life of approximately four years from the end of 2017. The Ban Houayxai deposit is in an early Permian volcano-sedimentary unit which is part of a late Carboniferous to early Permian (310–270 million years ago) volcanic-plutonic sequence of the Truong Son Fold Belt. The deposit formed when hot saline (240–415°C, 2.7–13.0 weight per cent NaCl equivalent) fluids ascended from a geologically fertile island arc porphyry into overlying volcanics along a fault or faults in the early Permian (290–256 million years ago) (Manaka et al, 2014). CITATION: Carpenter, J, Cowie, S, Stewart, P, Jones E, and Offer, A, 2018. Machine learning at a gold-silver mine: a case study from the Ban Houayxai Gold-Silver Operation, in Proceedings Complex Orebodies Conference 2018, pp 82–85 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 21, 2018