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By N N. Viswanathan, D Kumar, S Kumar

In secondary steelmaking, calcium treatment is practised to modify the solid alumina or spinel inclusions into liquid or partially liquid calcium aluminates. It has been seen that the dissolved calcium reacts with sulfur or oxygen present in the steel to form CaS or CaO type of transient inclusions. Post-calcium treatment these transient inclusions further react with pre-existing alumina or spinel inclusions and modify them. In addition, direct modification of pre-existing inclusions is also reported in the literature. In the present study, laboratory-scale induction furnace-based experiments are carried out to melt electrolytic iron in an alumina crucible followed by deoxidation with aluminium. The CaS-based composite material, prepared in-house, is added after the aluminium deoxidation to study the stability of CaS at the steelmaking temperature. Multiple steel samples were also taken to track the dissociation of CaS by means of sulfur pick-up in steel. Additionally, inclusion analysis of these steel samples was also performed to track changes in the chemical composition of inclusions in response to CaS addition. It has been seen that the CaS dissociates leading to a gradual pick-up of sulfur in steel. The scanning electron microscope – energy dispersive X-ray spectroscopy (SEM-EDS) analysis reveals that the alumina crucible and floated alumina inclusions are modified into calcium aluminates and the extent of modification depends on the contact time of CaS with the two sources of alumina mentioned earlier. However, the modification of alumina inclusions in the bulk steel did not occur during these experiments.

Jun 19, 2024

By Theodore James Kurela

Analysis of adverse technical issues has traditionally relied on a snapshot of the state of the operation complemented with both the melt shop’s archived data and eyewitness accounts of adverse events. The GrafTech ArchiTech System is helping EAF shops solve problems faster by combining continuous analysis of information with statistically based alerts of process deviations. After one year of system implementation, a number of cases have been detected and communicated to melt shops worldwide. The objective of this paper is to examine a few of these cases; the early detection, statistical analysis, deviation reporting and the resulting countermeasures implemented.

Aug 17, 2017

By A. Mainza, I. Govender, J. Waters

"The study of the properties of mineral processing suspensions is important in understanding how a circuit might behave. As soon as the predominantly dry ore enters a wet milling stage the ore properties undergo changes as a ‘slurry’ is created. Slurries can be classified in terms of their physical properties (particle density, solids concentration, particle size and size distribution, particle shape), and their flow properties such as rheology. Slurry flow regimes are classified into true homogeneous, pseudo homogeneous, heterogeneous and fully segregated, and only true homogeneous and pseudo homogeneous suspensions can be characterized by their flow structure. A class of the heterogeneous regime are the so-called dense phase or settling slurries - those which result in a clear water surface on standing, although they may approach a pseudo homogeneous state if suspended for a sufficient period of time. They are usually extremely difficult to characterize by their rheological properties alone and the rheological characterization of these slurries has always posed a problem, especially at higher concentrations. Previous rheological studies have focused on the individual concentrator units dealing with milling, classification, pumping, flotation, fine grinding, thickening.In this work an attempt was made to characterize two ore types (copper and a Platreef platinum ore) using a custom built Paterson and Cooke tube rheometer, at concentrations up to 43% by volume. After applying a turbulence correction, results showed Bingham plastic behavior. A conventional vane rheometer was then used to compare the rheological behavior of platinum concentrator streams. A size criteria was used to identify any rheologically dominant streams."

Jan 1, 2014

By S. Martins

The aim of this work is to compare three different results of charge motion in a modified 5ft diameter lab mill and to identify differences and similarities in these results. The lab mill is modified from tumbling a ball charge to tumbling a charge of disks. This modification replicates 2D motion. This 2D condition is measured using an instrumented disk (iDisk) and analysed using a video imaging system. The iDisk is equipped with a 3D accelerometer array and rotation rate sensors. With the help of a video system, some measured quantities are also determined externally. The results of these three predictions or measurements are presented. A discussion is included.

Jan 1, 2014

By Longjiang Li, Mao Jiang, Zhihui Shen, Guizhou University, Yin Pan

This paper aims to study the influence and action mechanism of collector Y-89 on the flotation of auriferous pyrite. The measurement to identify adsorption quantity, IR and XPS spectrum analysis and flotation experiment made on the pure mineral were conducted. The research results show that when the dosage of MIBC is 20 mg/L, and pH of 8, the dosage of Y-89 over 60 mg/L, the pyrite recovery rate is greater than 80%.And when the dosage of Y-89is 60 mg/L, dosage of MIBC 20 mg/L, the pH in a wider range (pH=4~9), the recovery is greater than 75%. When the pH is above 10, the pyrite is depressed and its recovery rate is found to be dramatically dropping. Adsorption quantity measurement also shows that the strong alkaline conditions inhibit the adsorption of Y-89 on the surface of auriferous pyrite. IR measurement indicates that chemisorption of Y-89 occurs on the surface of auriferous pyrite. XPS spectrum analysis indicates that without adding Y-89, oxidation reaction occurs on the surface of pyrite. But when Y-89 is added, the chemical environment of Fe on the surface of pyrite has changed. Such findings indicate that with Y-89, chemisorption occurs on the surface of auriferous pyrite.

Jan 1, 2014

By Maycon Athayde

O processo de pelotização consiste na aglomeração e posterior tratamento térmico das pelotas, ajustando as propriedades químicas e mecânicas para o transporte ao reator siderúrgico. A otimização e aperfeiçoamento do processo no forno pode ser realizado experimentalmente utilizando um pot grate. Trata-se de um equipamento no qual uma carga de pelotas cruas é submetida a condições similares às encontradas no processo industrial. Contudo, um projeto de experimentos em um pot grate pode levar semanas. Além disso, alguns parâmetros como: taxas das reações e balanço de energia são difíceis de serem monitorados. Tendo em vista isso, o presente trabalho buscou desenvolver um software de simulação para avaliar o comportamento das pelotas em um pot grate de maneira rápida e prática. Os resultados mostram uma interface amigável para a avaliação da temperatura de pelota, umidade da água, queima do carbono e balanço de energia. Os modelos implementados foram comparados e validados com trabalhos publicados na literatura. O modelo também serve como uma ferramenta de Projetos e Experimentos no Pot, uma vez que permite testes mais rápidos e de custo mais baixo.

Aug 16, 2017

By Kai Kang, Jun Bao, Shouping Liu, Xiao Sun

Powder characteristics have a significant influence on selective laser melting (SLM) process. In this research, particle size, surface contour and the microstructure of IN718 powder used in SLM were tested, and the physical and chemical changes during heating process of the powder were investigated as well. The shape characteristic and fluid properties of IN718 powder were defined and measured. It is shows that most particles of IN718 powder exhibited nearly spherical shapes, and the particle size is about 22.95μm. On this basis, IN718 sample was fabricated by SLM process using the powder and the microstructure of the fabricated sample was investigated. The results indicated that the sample has a dense microstructure, no macro-defects but a few micropores and porosity. Compared with the powder, there was no new phase formed in the sample and melting point of the sample was little less than that of the powder.

Jan 1, 2015

By Xiang-dong XING, Zhen-yang wang, Jian-Liang Zhang

Distribution behavior of titanium between CaO-SiO2-MgO-Al2O3-TiO2 and hot metal was studied between 1350 °C to 1600 °C. Experimental results indicate that the reaction temperature influenced the activity coefficients of titanium and resulted in the variation of equilibrium constant. Finally, the Gibbs free energy formula of titanium carbothermic reduction was fit out using the thermodynamic model of Wagner and congregated electron phase models.

Jan 1, 2015

By Stênio Cavalier Cabral

O diboreto de titânio (TiB2) é um material cerâmico de alta dureza com uma grande potencialidade de aplicação tecnológica. No entanto, existe uma grande dificuldade de se produzir corpos bem sinterizados desse material, quando são usadas técnicas convencionais de sinterização. Neste trabalho, foi empregada uma técnica de processamento em altas pressões e altas temperaturas para produzir compactos de TiB2 com 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. O principal objetivo do trabalho foi à realização do ensaio de torneamento para a avaliação de desempenho dos compósitos produzidos e sua relação com a quantidade de ciclos de sinterizaçãos em condições reais de trabalho. Os resultados obtidos apresentam perspectivas interessantes de utilização do processamento em alta pressão e alta temperatura para produção de inseros para aplicação na usinagem do ferro fundido nodular.

Aug 16, 2017

By J. Awmack, M. A. Tomlinson, P. J. Lind

"Peñasquito is a complex polymetallic deposit containing gold, silver, lead, zinc, and copper and is one of the largest producers of gold in Mexico. Mining activity is currently transitioning to a second open pit, Chile Colorado, which will be mined concurrently with the existing open pit, Peñasco. The ore bodies are located within diatreme pipes and into the surrounding sediment formation. In the coming years, mining will be carried out in more sedimentary zones, which are significantly higher in organic carbon content. Organic carbon in the feed influences both flotation and leaching operations. Several changes are being implemented to the Peñasquito flowsheet to mitigate the effects of increased organic carbon in the plant feed. These include the use of alternate reagent schemes, construction of a carbon pre-flotation circuit, implementation of a pre-leach flotation circuit ahead of pyrite leach, and evaluation of a tertiary process for separation of carbon and precious metal minerals.INTRODUCTION Goldcorp’s Peñasquito operation is located in the Mexican state of Zacatecas, approximately 200 km from the city of Zacatecas in the Mazapil municipality (Figure 1). Peñasquito has been in operation since 2009, with mining carried out by open-pit methods. Oxide ore has been processed in a heap leach facility and sulfide ore is treated in the sulfide processing plant. The processing capacity of the sulfide plant is 130,000 tonnes of ore per day and in 2016 production amounted to 465,000 ounces of gold, 17.6 million ounces of silver, 109 million lb of contained lead in lead concentrate, and 263 million lb of contained zinc in zinc concentrate (Goldcorp Inc., 2017). To recover more of the contained gold and silver and to mitigate the impact of increasing organic carbon content in the ore, a number of significant changes are being made to the operation."

Jan 1, 2018

By Stephen L. Chryssoulis, Stamen Dimov

"Preg-robbing has been known for many years, where increased losses are suffered because dissolved gold is removed from solution by adsorption onto carbonaceous matter. In direct cyanidation circuits it is reasonable to conclude that the preg-robbed gold is either in a gold cyanide [Au(CN) - 2, AuCN] or metallic [Au°] form. However, in circuits with a pre-oxidation step possibilities increase and multiply even further because of water recycle streams containing apparent and not-so-apparent gold ligands. It is in these circuits where speciation of sorbed gold, i.e. the identification of the gold compound, is useful. The importance arises from the fact that proper identification of the sorbed gold species can be used to determine how, when, where and why gold was removed from solution, thereby identifying the exact cause of the problem and providing clues as to how it may be rectified.INTRODUCTIONTo the best of our knowledge, this is the first attempt ever to speciate gold preg-robbed by carbonaceous matter using a surface sensitive microbeam technique. This approach enables the direct determination of gold species sorbed on carbonaceous particulates, opening an entirely new field in the understanding of the chemistry of gold sorption on carbon. The reasoning behind this effort was to add to the current knowledge of the detrimental effect chloride ions have on gold recovery by the pressure oxidation and in particular why in the ensuing CIL step, gold is not being desorbed from the surface of the carbonaceous particles (Table 1)."

Jan 1, 2004

By Robert Mensah-Biney

The loading characteristics of gold-tetrabromide species onto a weak-base resin, PAZ-4, were evaluated using a completely mixed batch reaction system. The time. to attain equilibrium loading was substantial, on the order of several days. However, abnormally high loading capacity values of 15 to 20 meq Au/g dry resin (1000 to 1300 kgAu/tonne) were attainable in 24 hours. The loading of gold-bromo species by P AZ-4 was visualized as consisting of two processes: (i) the rapid adsorption of [AuBr4r species by simple ion exchange mechanisms and (ii) reduction of [AuBr4r to metallic gold by an electron exchange mechanism. Elution of gold from loaded resin was feasible provided the resin had not been loaded to high capacity values. If loading is carried to high levels, complete elution becomes impractical and the gold may be recovered by ashing the loaded resin. For the high loading capacities observed this option would appear to be cost effective.

Jan 1, 1991

By D. H. Platt

Gypsum and gypsite, used in the manufacture of plaster and plaster products, have been mined from deposits near Acme, Hardeman County, Tex., for more than 30 years. The Certain-toed Products Corp., 120 East Lancaster St., Ardmore, Pa., operates the Acme, Tex., mine. Underground hauling was done with storage-battery and Diesel-electric-powered shuttle cars. Many mining companies and individuals have manifested interest in all types of equipment powered by Diesel or Diesel-electric units, as attested by the recent increase in use of Diesel-powered equipment in underground metal and nonmetal mines. The purpose of this paper is to describe the manner in which a storage battery-powered Joy Model 60D2 shuttle car was converted to Diesel-electric power. The conversion was made, at the instance of the operating company, by Stewart & Stevens on Services, 4801 Lemon Ave., Dallas, Tex. This is believed to be the only such converted shuttle car in use.

Jan 1, 1950

By F. E. Pawlek

Copper concentrates can be comminuted in an attritor within a very short time to a particle size of 1 - 0.1 um. Addition of sodium hydroxide enhances commninution. The concentrates, suspended only in water, can be completely dissolved under oxygen over pressure and temperatures ranging from 120 - 180°C (248 - 356°F), because the surface area of the concentrate has been significantly increased by the ultra fine grinding. Addi¬tion of a small amount of silver ions to leach liquor containing sulfuric acid acted as a catalyst for the dissolution of chalcopyrite, because of the formation of local elements on the surface. The addition of C1- ions was also catalytically very effective. With this method it is possible to completely dissolve the copper contained in chalcopyrite concentrates after ultra fine grinding within 30 min at 110°C (230°F) under an oxygen partial pressure of 1 atm (14 psig). Several flowsheets demonstrate the industrial feasibility.

Jan 1, 1976

By Steven W. Schmauch

In 1985, at the request of the U.S. Bureau of Land Management, the U.S. Bureau of Mines studied 27,930 acres of the 52,000 acre East Fork High Rock Canyon Wilderness Study Area, CA-020-914/NV-020-006A, in order to evaluate the mineral resources. The study area is located in Humboldt and Washoe Counties, NV, about 45 miles east of Cedarville, CA. Bureau of Mines personnel reviewed pertinent literature and county mining records and examined prospects or mineralized areas. There are no organized mining districts and no historical or active claims in the study area; one small pit lies in the southwest corner of the study area. Based on published literature, sample results and field observations, there are no recognized mineral, geothermal, or fossil fuel resources. Epithermal mineralization indicators are not present or exposed. Sand and gravel deposits in the study area are not likely to be developed as other deposits are closer to market areas.

Jan 1, 1986

By Guilherme Corrêa Soares

Deeper understanding about the strain hardening behavior of steels has become necessary due to its importance in industrial processes such as mechanical cold forming, rolling and drawing. In this work, the strain hardening behavior of AISI 304, non-grain oriented electrical (NGO) and dual phase steels was investigated. Tensile tests were performed and the strain hardening behavior of each steel was studied by the Hollomon’s equation. X-ray diffraction measurements and hardness tests were also carried out in order to characterize the specimens. Different work hardening stages were observed in each steel during the deformation process. The results obtained are discussed in terms of the relationship among the instantaneous strain hardening coefficient, hardness and eventual phase transformations. The instantaneous strain hardening coefficient of dual phase and NGO increases after the yield point, rapidly reaching its maximum and then steadily decreases until tensile strength is reached. In AISI 304’s case, the strain hardening coefficient keeps raising to high values in response to a large strain and then rapidly decreases before reaching the tensile strength. In comparison to the other steels, AISI 304 shows higher instantaneous strain hardening coefficient value, which persists even in large strains. This is a consequence of its strain hardening mechanism based on stress-induced martensite transformation.

Aug 16, 2017

By Jack Young

U. S. Steel Canada Inc.’s Lake Erie Works is the last green field integrated plant to be built in North America. The plant was designed using the best available environmental technology to develop an environmentally friendly production facility. A summary of the technology and measures used in the construction of the plant are summarized in this paper.

Jan 1, 2015

By J. A. Finch, R. R. Cunningham

The amount of foam volume generated in relation to the gas flowrate has long been used to define the foaminess of a solution and to characterize surfactants. The vessel geometry and gas flowrate range can affect the foam volume results. A fixed area column was tested alongside a variable area conical vessel with two surfactants. It was found that the fixed area vessel will cause foam volume to expand or contract which masks the effect of the surfactant. The conical vessel showed two regimes of foam volume production dependant on gas flowrate. The low gas flowrate regime revealed the physiochemical nature of the surfactant while a high gas flowrate revealed kinematic properties. Foaming properties of a surfactant is best determined with a variable area vessel at low gas flowrate.

Jan 1, 2009

By D. H. Lynch

This paper is a general description of current Central Florida phosphate mining, beneficiation and product transportation. It is directed and believed to be of interest to engineers not familiar with this industry.

Jan 1, 1978

By Donald M. Liddell, G. C. RIDDELL

THE cosmic ray continues to engage the attention of the physicists, and according to Millikan and Compton, experiments of the past summer indicate that these rays must come from interstellar space, but not from the stars themselves. According to press reports of the International Congress of Physicists at Rome, the view was given there that these rays have an initiating potential of over 750,000.000 volts. In the field of spectrographic investigation great strides have been made. The U. S. Naval Research Laboratories (R. F. Mehl and G. E. Doan of Lehigh) have just finished a year's work with a "radium torch" or "shadowgraphic apparatus" in the field of the X-ray, that bids fair to displace the latter to a great extent. The torch is more powerful., easier to operate and cheaper. Penetration of 10 in. of steel has been accomplished, which. is much -beyond the- -scope-, of the X-ray..

Jan 1, 1932