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By Roger A. Kauffman, Dean Van Dyk

Feldspar is the earth's most abundant mineral group. The feldspars are aluminum silicate minerals belonging to the tectosilicate class. Feldspars are the most widespread of any mineral group and are estimated to constitute 60% of the earth's crust. They make up a large percentage of the exposed rocks as well as soils, clays, and other unconsolidated sediments. Feldspars are widely used in the glass and ceramic industry and are principal components in rock classification schemes. Feldspar minerals and their production are important contributors to the domestic and world economies and standard of living. In 1990, the United States produced 630 kt of feldspar minerals, and world production was estimated to be more than 5 Mt. Feldspar mineral production in the United States has a long and interesting history (Feitler, 1967, Rogers Jr. et al., 1983). The first commercial production in the United States occurred in about 1825 and came from pegmatite bodies located in Connecticut, where feldspar was mined, hand sorted, and shipped to England. Feldspar production grew during the 19th and 20th centuries with important developments in production location, integrated mine and processing facilities, and the development of the flotation process for feldspar by the US Bureau of Mines and the feldspar industry. The first commercial feldspar flotation plant began operations-in Kona, NC, in 1946, some six years after this process had been developed. In 1990, the domestic feldspar industry consisted of 12 operating companies with mines and processing plants located throughout the United States (see Table 1). During the last 25 years, the domestic feldspar industry has been dynamic, marked by new plant construction and capacity expansion at older plants. The industry has also seen plant closures, changes in ownership of existing operations, the consolidation of the Canadian nepheline syenite industry, and the increase of imported feldspar products. The industry has been affected by contractions in its major end-use markets brought about by economic cycles, product substitution, and environmental effects, such as recycling, land-use controversy, and air and water pollution. Despite problems, the industry remains mature and highly competitive. GEOLOGY Mineralogy The common feldspar group of minerals form a single crystalline phase or solid solution series of minerals. Fig. 1 is a ternary phase diagram that shows the feldspar mineralogy-KAlSi,O8, NaAlSi3O8, and CaAl2Si2O8. The end-member compositions are also referred to as potassium, sodium, and calcium feldspar. The feldspars whose chemistry ranges between the potassium and sodium end-members are known as alkali feldspars, while those between the sodium and calcium end-members are plagioclase feldspars. These feldspar groups can be further subdivided based on structural and compositional features within the alkali or plagioclase feldspar series. The distinction between and the proportion of members of the two feldspar groups are important to the classification of igneous rocks (Deer et al., 1966). Perthites are the exsolution product of an initially homogeneous potassium-sodium feldspar solid solution which forms (in an environment of decreasing temperature) a heterogeneous intergrowth of sodium-rich feldspar lamellae in a host crystal of potassium feldspar. Antiperthites are exsolution products in which the host mineral is sodium-rich plagioclase feldspar and the intergrowths are potassium-rich feldspar.

Jan 1, 1994

By S. Maleksaeedi

On-site evaluation of strength using hardness is common for different materials. The lack of such relation for aluminum alloys has always been felt. In this work, a finite element analysis of plastic deformation and its distribution in Brinell hardness testing is presented. The analysis has been performed for different strength levels of aluminum alloys. By utilizing the Von Mises equivalent strain in hardness, it is tried to derive a correlation between hardness and strength values for the alloys under consideration. The derived correlation is verified using the experimental values available in literature.

Jan 1, 2004

By Philip Nash, Jie Zhou, Joshua Blackketter

"Large ingots tend to have internal defects such as shrinkage cavities and porosities, which have to be closed during the cogging stage to ensure sound internal quality of forged parts. In this work, finite element methods were used to simulate open die forging passes, with varying parameters that affect the void closure behavior profoundly. Numerical models ware constructed in ABAQUS, DEFORM and FORGE using data taken from footage of the forging process and material mechanical data obtained from the Gleeble compression tests. Forging variables such as pass rotation, reduction per pass, and feed ratio were studied with intense attention paid on the special properties of H13 steel, so that this study can be applied to solve real world problem.IntroductionCenterline defect closure is a frequently studied but still challenging topic in open die forging industry. In practice, open die forging is employed as an effective hot forming process to make desired shape of metal products as well as to ensure center consolidation of internal defects which result from the casting process. Nowadays, remarkable large forgings have been more and more required to meet industries demand. However, the increase in ingot size has tended to result in considerable macrosegregations and shrinkage cavities or voids, which need to be worked thoroughly during the forging process; but the size of the products and limitations of manufacturing capacity, such as the press load, make it difficult to achieve adequate local deformation to close those defects. Therefore, choosing optimal forging parameters under given work condition to ensure good internal quality of forged products is critically important."

Jan 1, 2012

By J Meikle

A projected image is not always a true representation of a situation, or indeed an industry. This is often the case of the mining and minerals industry, which has frequently been portrayed in a negative light with a male dominance stigma attached. However, these issues can be combated for both the industry and its future, current undergraduate students, through undergraduate industry experience. In particular, vacation work enables female students to dispel many myths surrounding the industry and realise that the mining and minerals field offers career development for both genders. This paper will discuss how vacation work enables students to make important career decisions even before they have graduated. Industry experience provides undergraduates with the opportunity to gain practical knowledge relevant to their field of study. Additionally it allows students to observe the nature of the industry and the sacrifices necessary to advance careers. The prior insights into an industry are relevant to all students, but particularly female students, who might otherwise be dissuaded from a career in mining. This paper is written from the perspective of two female undergraduate students studying Mining and Minerals Processing Engineering.

Jan 1, 2006

By T. Brozell

"Communities near sand mines and processing facilities in Wisconsin have raised concerns regarding possible exposure to ambient respirable (PM4) crystalline silica. Fenceline PM4 (particulate matter captured with a 50 percent cut size of 4 micrometers aerodynamic diameter) crystalline silica concentration data were compiled at Fairmount Santrol Inc., Mathy Construction Inc. and U.S. Silica facilities. The long-term average PM4 crystalline silica concentrations ranged from 0.05 to 0.45 micrograms/m3 when sample values below the limit of quantification were treated as zeros. All of the long-term average concentrations were less than 20 percent of the Minnesota Department of Health’s and California Office of Environmental Health Hazard Assessment’s PM4 crystalline silica chronic reference exposure level of 3.0 micrograms/m3. The measured concentrations were consistently within the local background concentration range.Air Control Techniques P.C. compiled the sampling data using Thermo Fisher Scientific Inc. Partisol 2000i PM2.5 samplers meeting the requirements of 40 CFR Part 50, Appendix L. These samplers were adapted to capture particulate matter with a 50 percent cut size of 4 micrometers. The use of polyvinyl chloride filters allowed for crystalline silica X-ray diffraction analysis by NIOSH Method 7500. The combined use of adjusted PM2.5 filter-based samplers with Method 7500 crystalline silica analyses provided for a highly sensitive limit of quantification of 0.31 micrograms/m3 of PM4 crystalline silica.BackgroundIn 2005, the California Office of Environmental Health Hazard Assessment (OEHHA, 2005) adopted a 70-year chronic reference exposure level (REL) for PM4 (particulate matter having aerodynamic diameter of 4 micrometers or less) crystalline silica. The REL was extrapolated from occupational hygiene epidemiological studies, essentially all of which were based on in-plant PM4 crystalline silica measurements. No well-established ambient sampling technique for PM4 crystalline silica was available at the time that OEHHA adopted its REL. The personal samplers used for the National Institute for Occupational Safety and Health (NIOSH) Method 0600 in-plant sampling of employee exposure were designed for concentrations higher than ambient levels. The limit of quantification (LOQ) of PM4 crystalline silica on NIOSH 0600 filters was too high for the effective sampling of ambient air."

Jan 1, 2015

By Mark H. Balfe

Over the last decade, Fenway Park has undergone annual improvements to modernize the facility for players and fans. These renovations include the Monster Seats, the Right Field Roof expansion, a new pavilion behind home plate, expansion of the Red Sox clubhouse, additional roof seating, and concourse improvements. Retrofitting the historic ballpark to bring it up to current standards required installation of foundations to support the new structural loads for each of the alteration projects. This required evaluation of existing conditions, and in many cases augmentation of the foundations at existing columns to accommodate the structural changes to the park. New foundations, generally consisting of drilled-in micropiles, were installed in numerous configurations and conditions. Since 2003, a total of 215 drilled-in micropiles have been installed to augment various columns around the park. The micropiles range in capacity between 40 and 70 tons and are installed through Fill and Organic Soils and embedded into the dense Glaciofluvial Sand and Gravel layer. Issues and learning related to the foundation augmentation include schedule constraints (work is typically conducted during the off-season and schedule is very aggressive), encountering old/abandoned utilities or foundations, ventilation of equipment, and management of spoils during micropile installation.

Jan 1, 2011

By Arlei Fonseca Barcelos

Uma das características de qualidade mais importantes das bobinas Full Hard é a planicidade. Essa pesquisa visa confirmar a hipótese de desenvolver e treinar uma rede neural capaz de identificar padrões de planicidade de bobinas laminadas no Laminador de Tiras a Frio#3 da CSN, propiciando o aumento do padrão de qualidade, inovação tecnológica e ganhos econômicos. A metodologia aplicada para alcançar os resultados almejados baseou-se em experimentos realizados com informações de bobinas reais, sendo utilizados softwares distintos para o desenvolvimento do projeto, validando os resultados obtidos através de análises de desempenho, com a correlação entre respostas conhecidas e as obtidas com a utilização da rede neural, assim como, a análise do erro médio quadrático das respostas obtidas com a aplicação, sendo simulados na etapa de treinamento da rede neural ou verificados experimentalmente com a execução da ferramenta desenvolvida.

Aug 17, 2017

By Arnaud-Guilhem de Loze

Este artigo apresenta uma ferramenta de simulação computacional desenvolvida com o objetivo de auxiliar a adoção de melhores práticas de controle do forno durante períodos sem produção. O sistema desenvolvido permite simular as temperaturas do revestimento refratário de um forno de tratamento térmico de tubos em função da evolução da temperatura da atmosfera interna em diferentes cenários. O simulador foi desenvolvido baseado em um modelo matemático dinâmico validado, que utiliza um sistema de equações de transferência de calor discretizadas. Realizou-se a validação desta ferramenta computacional com a utilização de dados reais de uma campanha de medição de temperaturas. A comparação dos resultados apresentou pequeno erro entre simulação e valores reais coletados. A utilização desta ferramenta auxiliou a definição de estratégias de controle do forno durante períodos improdutivos, possibilitando redução do consumo de energia e retomada da produção com garantia da qualidade do produto.

Aug 17, 2017

By Joseph M. Zigich

The Anaconda Minerals Company operates a molybdenite and copper producing mine and mill facility near Tonopah, Nevada. Included with the milling facility is a ferric chloride leach plant for removal of copper mineralization from the molybdenite concentrates. Discussed are the engineering and construction schedules associated with the leach plant. The chemistry associated with the process along with a description of the process flow, equipment, and operating parameters are contained in the paper.

Jan 1, 1983

By W. Hawker, A. M. Ivana

"Pressure oxidation is used to liberate gold from refractory sulphide ore and concentrates with over fifteen autoclaves in operation. Despite the importance of pressure oxidation, the autoclave chemistry and chemical thermodynamics are not well established. For example, there is no consensus on aqueous iron speciation or stability of jarosite phases. Additionally, there remains questions about basic ferric sulphate formation and stability. In addition to a review of the current state of knowledge, a methodology to study the ferric precipitation reaction and relate the results to chemical thermodynamic predictions is presented which will be used to accurately define the phase boundaries of the iron precipitates in the future (hematite, jarosite and basic ferric sulphate).INTRODUCTION With declining availability of orebodies that respond to simple leaching conditions, pressure oxidation has become a prevalent technology to liberate gold locked in sulphide mineral matrices. Gold pressure oxidation was established 32 years ago, with McLaughlin being the first facility in 1985 (Thomas & Pearson, 2016). Pressure oxidation is carried out at elevated temperatures ranging from 180 to 240°C as shown in the summary of operations in Table 1 (Ruonala et al., 2016; Fleming, 2010).A considerable amount of research has been done to study iron solubility and precipitation under autoclave conditions (Tozawa & Sasaki, 1986; Umetsu et al., 1977; Sasaki et al., 1993; Fleuriault, 2016; Cheng & Demopoulos, 2004; Papangelakis et al., 1994; Yue et al., 2003). These reports provide a description of the process chemistry and iron behaviour in the autoclave. However, there remain questions about the type and stability of aqueous species and solid phases. This detailed information is required to build a robust chemical thermodynamic model of the system, allowing for equilibrium and kinetic reaction limitations to be discerned."

Jan 1, 2017

By Masanori Abe, Yoshitaka Kitamoto, Kazuhiro Nishimura

"Ferrite plating is a chemical processing which utilizes Fe2+ - Fe3+ oxidation to synthesizing polycrystalline films of ferromagnetic spinels (MFe20 4, M = Fe, Co, Ni, Zn, Al, Cr, TI, etc:) directly from an aqueous solution at 24 - 100°C. This low temperature process allows us to fabricate new ferrite film devices on · substrates of such non-heat-resistant materials as plastics, GaAs integrated circuits, and biomaterials. Synthesized from an aqueous solution the ferrite plated ·films are highly biocompatible. Thus various magnetic device and biomedical applications have been proposed and realized using ferrite-plated films. Ferrite-encapsulated polymer microspheres are applied to antibody carries for enzyme immunoassay, and also to toners/carriers for photocopying. Perpendicular magnetic recording media utilizing plated CoNi ferrite films are proposed. The low-temperature synthesized films of NiZn and Co ferrites are potentially used as soft-magnetic and/or insulating layers, respectively at high/microwave frequencies.IntroductionFerrite plating is a processing which facilitates the formation of crystalline spinel ferrite films with various compositions, (Fe, M)30 4 (M = Fe, Co, Ni, Zn, Al, Cr, TI, etc.), directly from an aqueous solution at 60 - 100°C [1]. This opened the door to fabricating novel ferrite-film devices using substrates of such non-heat-resistant materials as plastics and GaAs integrated circuits [2-4]; conventional ferrite film preparation techniques such as sputtering, vacuum evaporation, MBE, LPE, etc., require high temperatures(> -600°C) for crystallization of ferrites, which deteriorates the non-heat-resistant substrates. Recently we extended ferrite plating to be preformed at room temperature [5, 6]. This enables us to use as substrates such organic materials as biomaterials (e.g. enzymes) having very low heat-resistance."

Jan 1, 2000

By S Bright, M J. Masamvu, E K. Chiwandika, S Dandi, S M. Masuka

The depletion of high-grade hard and lumpy chrome ores has forced Zimbabwean ferrochrome producers to resort to low-grade friable ores that have an average of 28 per cent fines against a set limit of 12 per cent. Submerged open arc furnaces currently in use are associated with eruptions within the furnace because of the high amounts of fines, high energy consumption, as well as high SO2 and CO2 emissions. Traditionally employed agglomeration methods such as pelletising and the use of coke in the furnace have been discarded because of the pressure to lower operational costs and to achieve higher profit margins. This research aims to develop a method to incorporate lowgrade friable ore fines and unprocessed coal into production while lowering CO2 and SO2 emissions through a closed direct current (DC) arc furnace. The closed DC arc furnace could incorporate the friable ores and coal while maintaining above 90 per cent reduction rates. Preliminary findings also show that energy consumption could be reduced by up to 35 per cent by incorporating a pre-heating and pre-reduction system using the flue gases from the furnace. In the proposed circuit, the cost of production per ton of ferrochrome might be potentially lowered by an average of 30 per cent.

Jun 19, 2024

By R. G. Knickerbocker

A STURDY and consistent expansion of the metal industry occurred in 1947 exemplified by an increase of approximately 30 per cent in steel consumption over 1946. For this major reason, ferroalloy metals have seen their most useful and important peace-time year. The current domestic rate of consumption of high-grade ferroalloy ores, together with added consumption of new foreign producers as well as for eign nationals' restrictions on high-grade exports, makes very evident the increasing difficulties of obtaining sufficient high-grade ores. This accentuates the need for new and less expensive methods of production of ferro-alloy metals of higher purity from lower-grade domestic resources. As an important factor in preparedness, procurement of these high-grade, -critical ferroalloy minerals and metals for our nation's stock piles is a most important task. Also, this stock-piling can be the means of supplying incentive for the industrial development of the new metallurgical processes and plants necessary for the recovery of ferroalloy metals from our domestic low-grade deposits.

Jan 1, 1948

By R. M. Briney

A RETURN to nonwar conditions characterized the year 1946. The acquisition and forced use, under Government auspices, of low-grade and uneconomic ores, both foreign and domestic, ceased in 1945, but there was some carry-over into the early months of 1946. The world shipping situation delayed the procurement of some foreign ores, but conditions were improving by the end of the year. No actual shortage of any important alloy was experienced, hence the industry was able to make prompt shipment of orders placed. Price levels of ferroalloys, which had remained virtually constant through the war years, were forced upward, with increases on specific products as conditions necessitated. Standard ferroman-ganese and low-carbon ferrochrome were notable exceptions in that their price did not change. No new ferroalloy smelting plants were constructed. The Defense Plant Corp.. sold the works at Ashtabula, Ohio, to the Electro Metallurgical Co. A new type of ferroalloy furnace was described at the Birmingham meeting of the Electrochemical Society. Known as the "Elkem Rotary Furnace" it is distinguished by a rotating shell. The whole furnace, including shell, refrac-

Jan 1, 1947

By Yiling Zhang, Paul A. Salvador, Gregory S. Rohrer

"Photocatalysis utilizes solar energy to produce hydrogen by splitting H2O. When a thin film of photocatalyst TiO2 is supported on a ferroelectric BiFeO3 substrate (band gap ~2.5 eV), the TiO2/BiFeO3 heterostructure is capable of photochemically reducing Ag+ to Ag0 in aqueous solutions under blue light with enhanced efficiency. The observation of spatially selective silver patterns on surface of the heterostructure after reaction suggests that photogenerated electrons and holes in ferroelectric BiFeO3 are driven in opposite directions to reduce their chance of recombination. Comparisons of the amounts of reduced silver on TiO2 film grains with distinct phases/orientations show that the reactivity is mildly preferential on anatase TiO2 phase and does not strongly depend on crystallographic orientation of BiFeO3.IntroductionTitania (TiO2) is capable of photocatalytically converting H2O to hydrogen and oxygen under the irradiation of ultraviolet light. [1, 2] One of the limiting factors for titania to be used as an effective photocatalyst is its band gap. Because the absorption edges of rutile and anatase titania are at 3.0 eV and 3.2 eV, respectively, they can only absorb light in the UV portion of the spectrum, which is about 3% of the available solar energy. [3-5] This limitation has motivated attempts to modify the absorption edge of titania so that it can absorb visible light.One strategy is to substitute a portion of the titanium and/or the oxygen with other atoms. There are numerous reports on visible light absorption of titania by doping and co-doping of Cr, V, Mo, Sb, Fe, N, S, C, and F. [6-34] Another strategy is to add an adsorbed molecular species that absorb visible light and donate an electron or hole to the titania, such as organic dyes [33, 35, 36] and Ce3+/Ce4+. [37, 38]The strategy in the present work takes the approach of depositing a pure titania thin film on a visible light absorbing substrate BiFeO3 to induce visible light activity of the heterostructure. BiFeO3 is a semiconductor with a band gap of about 2.5 eV [39-41] and is photocatalytically active in visible light. [42, 43] It is also ferroelectric with spontaneous polarization along pseudo-cubic <111> directions of 6.1 µC cm-2. [44] The spontaneous polarization gives rise to internal electric fields that drive photogenerated charge carriers, namely electrons and holes, in opposite directions to reduce their chance of recombination. [45-47] Additionally, the separation of electrons and holes leads to the spatial separation of reduction and oxidation half reactions so that the back reaction of intermediates is also suppressed. Such charge carrier separation has been reported in TiO2/BaTiO3 heterostructures with UV light illumination. [48-51] The TiO2/BiFeO3 heterostructures in this work combine both advantages of the relatively narrow band gap and the internal fields in BiFeO3 to enhance the overall photocatalytic activity."

Jan 1, 2014

By Natalia Konstantinova, Georgy Novikov, Pavel Rekant, Goergy Cherkashov, Olga Bogdanova

The economic interest of oceanic ferromanganese crusts and nodules is determined by high grades of major, rare and earth rare elements in these types of marine minerals [1]. Modern oceanic ferromanganese deposits have a global distribution with the largest fields in the Pacific Ocean. The Arctic Ocean still remains a poorly explored region. The first ferromanganese deposits from the deep part of the Arctic Ocean were recovered almost at the same time in 2012 both in US and Russian cruises to the Chukchi Borderland (1) and Mendeleev Ridge (2). Preliminary results of mineral deposits from the first area were reported at UMI-2012 by James Hein et al. [2]. We present here the data of ferromanganese deposits from the Mendeleev Ridge.

Sep 1, 2014

By Alton G. Woody

Like so many installations of its type approaching middle age, the ore processing and shipping facilities in Puerto Ordaz, Venezuela, have taken a lot of twists and turns in their lifetime. The object of this paper is to lead you through these twists and turns and some of the reasoning for them. The need for additional sources of iron are in the United States became evident during the time of the second world war. An exploration team from U. S. Steel located further high quality direct shipping iron are in commercial quantities near Ciudad Bolivar, Venezuela in 1947. Basic decisions were made to develop these reserves for export via the Orinoco River through a new shipping port to be built at the confluence of the Orinoco and Caroni Rivers. The basic concept was for the ore to be loaded directly to ocean going vessels. This was something of a gamble since the basic economics depended upon successfully opening up the main channel of the Orinoco River to deepwater vessels, and the Bethlehem Steel mine in the same area was already working with shallow draft river boats and a transfer station on the coast. Always, the basic philosophy has tended to be to plan with expansion in mind. The original conveyor systems were 1.52 m (60 inches) wide with 200 idlers, whereas 1.07 m (42 inches) or 1.22 m (48 inches) wide conveyors could have carried any production foreseen at the time of installation. Stockpiles have been located and designed with room for expansion. Basic designs have had dotted line future expansion blocked in.

Jan 1, 1978

By André Mans, Frans B. Waanders

Current losses of Ferrosilicon (Fe-Si), which is used in the dense medium separation (DMS) of iron ore at Kumba Resources, Sishen, South Africa occur due to adhesion to the separation products and also by being present in the effluent stream, due to abrasion. The losses contribute greatly to the running cost of the plant and the purpose of this project was to determine the characteristics of the unused Fe-Si and then to characterise the changes that occur during storage and the use thereof. A Scanning Electron Microscope (SEM) and Mössbauer Spectroscopy (MS) were used to investigate the characteristics of the fresh and used Fe-Si. It was found that the biggest loss of Fe-Si was due to the abrasion of the particles during the DMS process, which resulted in the liberation of Fe and subsequent formation of an oxihydroxide froth. A possible change in magnetic properties was also observed, leading to further losses that could occur during prolonged use of the medium. No clear changes to the Fe-Si occurred during correct storage methods, as was initially thought.

Jan 1, 2003

By Asmo Vartiainen

Background of Direct-to-Blister Flash Smelting is discussed; especially slag chemistry relating to copper solubility, slag fluidity and impurity behavior. In December, 2000, Mini-pilot Flash Smelting test runs were carried out at Outokumpu Research Oy to produce blister copper from Chilean concentrate and white metal and from a mixture of them. Tested slag types were iron silicate slag, ferrous calcium silicate slag and calcium ferrite slag with different slag compositions and different concentrate/white metal ratios. The test runs were successful. The fluxing effect of copper oxide was clearly demonstrated and ferrous calcium silicate slags remained fluid on a very wide liquidus range. The distribution of arsenic between ferrous calcium silicate slag and blister copper is much higher than between iron silicate slag and blister copper. This successful test run with the new slag type offer new possibilities in Direct-to-Blister process design.

Jan 1, 2003

By Asmo Vartiainen

Background of Direct-to-Blister Flash Smelting is discussed; especially slag chemistry relating to copper solubility, slag fluidity and impurity behavior. In December, 2000, Mini-pilot Flash Smelting test runs were carried out at Outokumpu Research Oy to produce blister copper from Chilean concentrate and white metal and from a mixture of them. Tested slag types were iron silicate slag, ferrous calcium silicate slag and calcium ferrite slag with different slag compositions and different concentrate/white metal ratios. The test runs were successful. The fluxing effect of copper oxide was clearly demonstrated and ferrous calcium silicate slags remained fluid on a very wide liquidus range. The distribution of arsenic between ferrous calcium silicate slag and blister copper is much higher than between iron silicate slag and blister copper. This successful test run with the new slag type offer new possibilities in Direct- to-Blister process design.

Jan 1, 2003