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By A. C. Fieldner, G. W. Jones

Tests were made at the Government Fuel Yard , operated at Washington , D. C. by the Bureau of Mines , Department of the Interior , in order to determine and improve the adjustment of the carburetors on the trucks used for transporting coal from the Fuel Yard to the different Government buildings in Washington . The tests were made possible through the hearty cooperation of G , S. Pope , engineer in charge of the Fuel Yard . Joseph Burrows and A. E. Foote of the garage department assisted during all the tests and supplied information on the mileage obtained by the trucks for the months preceding and succeding the time the tests were made . The Mack trucks used range in capacity from 2-1/2 to 7-1/2 ttoonnss .. The majority of the carburetors were Stromberg G- 3 type , as shown in Table 2. During the winter months , when the demand for coal is heavy , from 30 to 35 trucks are used . At the time the tests were made , only about ten of the trucks were in daily use , owing to the small demand for coal during the summer months , and scarcity due to labor conditions . Samples of the exhaust gas were taken on the trucks kept in service for summer hauling in order to determine the carburetor adjustment as used . Changes were then made to a more economical adjustment wherever possible , without sacrificing flexibility of operation and power . In every case the adjustments were maintained for maximum power , but were adjusted to the leanest position to give that power . In all but one case the carburetors were found to be adjusted too rich for maximum power and economy . These results are considered in detail in a later part of this report .

Jun 1, 1923

By Michael G. Zabetakis, Israel Liebman, Henry E. Perlee

Flammability studies conducted to date on stratified methane - air and pentane - air mixtures in air indicate that location and extent of a flammable layer are affected by molecular diffusion , gas motion , and propagation of flame . In initially quiescent mixtures , the lower limit - of - flammability zone may be determined by assuming molecular diffusion alone governs mixing rate . The upper limit - of - flammability zone can be predicted in this manner only for stratified layers with small concentration gradients ( less than 0.2 volumepercent per inch ) ; where large concentration gradients are encountered ( for example , as much as 30 volume - percent per inch ) , the initial - mixture methane concentrations that yield flammable mixtures are larger than anticipated . Flames propagating through heterogeneous quiescent methane - air atmospheres in the direction of the concentration gradient exhibit flame speeds at any point that corresponds to the flame speed of the homogeneous gas mixture having the same gas composition as that of the point in the heterogeneous system . In flowing mixtures with large concentration gradients , the degree of mixing prior to ignition does not appear to affect the flame velocity and emitted radiation appreciably in a 6.5 - ft - diameter gallery .

Jan 1, 1964

By Yanxu Shen, Cheng Liu, Zhijie Chen, Hao Chen, Huimin Gao, Zijie Ren

Fluorite, a kind of critical non-metallic minerals, is the primary source of industrial fluorine. Sodium oleate (SO) is commonly used as the collector of fluorite ores. However, because of its some features (such as the low solubility, high solidifying point, and poor dispersion of SO) at low temperatures, it profoundly inhibits its collecting ability as well as the flotation performance. Herein, we have developed a low-temperature-resistant collector for the efficient flotation separation of fluorite from quartz. The advantages and disadvantages of the SO and sodium petroleum sulfonate (SPS) were analyzed by comparing the performance under different temperature conditions. The results of flotation tests suggest that SPS exhibited much better collecting performance than SO under low temperature. The flotation mechanism of the two collecting agents were further analyzed by contact angle measurements, zeta potential measurements, Fourier-transform infrared spectroscopy (FT-IR), and flotation kinetics. The results indicated that both collectors can selectively undergo electrostatic and chemical adsorption with fluorite, with no adsorption on quartz surface. The sulfonic acid group in SPS is a hydrophilic functional group, which has a relatively higher solubility in water. Therefore, the water solubility of SPS is better at low temperatures.

Sep 30, 2021

By Zhian Liang, Xiong Huang, Weixin Wu, Lifeng Cui, Zhuanhua Wei, Guoyao Li, Xiao Ni, Junrong Wang, Shuiping Zhong

ZJ 201 (modified starch) is a non-toxic, odorless, and biodegradable polymeric depressant, which selectively depressed galena in batch flotation tests while chalcopyrite was not significantly affected. In a plant trial, copper-lead separation was successful for the first time without using dichromate. Moreover, the plant process could be changed to sequential Cu-Pb flotation using ZJ 201 for higher grade lead concentrate. A copper concentrate was obtained with a Cu grade of 24.91% and a Pb grade of 5.11%, which recovered 76.6% of the copper from the original ore; a lead concentrate was also obtained with a Pb grade of 21.90% and a Cu grade of 5.31%, which recovered 52.6% of the lead. In addition to the effective copper-lead separation observed in the plant trial, another improvement observed is that gold was recovered mostly in copper concentrate, which could be sold for higher prices. Au grade reached 230.64 g/t, and its recovery reached 65.8% in the copper concentrate. Au grade in lead concentrate was only 18.90 g/t.

Aug 27, 2021

By Alen Shibu Joseph, Arvind Rajnarayan Singh, Mudila Dhanunjaya Rao, Kamalesh K. Singh

In this article, the cementation of major impurities from zinc sulphate leach solution by the addition of zinc dust was studied by considering different parameters including time, mesh size, and percentage of excess zinc dust. The output obtained from various experiments was utilized for the design of experiments. A multi-level categorical factorial design with a quadratic model was employed during this study. Results were predicted to minimize the concentration of impurity metals in the solution by altering the parameters. Furthermore, these predicted results were validated by performing another experiment. Successfully, it showed that the predicted and experimental data values were close to each other. The predicted optimized values were 40 min, 100% excess zinc dust, and 300 mesh size for copper; 42 min, 100% excess zinc dust, and 300 mesh size for cobalt; 37 min, 100% excess zinc dust, and 300 mesh size for cadmium; and 34 min, 100% excess zinc dust, and 300 mesh size zinc dust for nickel. At these optimized values, the experimental results showed 99.99%, 55.7%, 99.6%, and 76.6% cementation efficiencies for copper, cobalt, cadmium, and nickel respectively. The statistical design of experiments for the effective cementation of impurities corroborates the economic feasibility of optimizing parameters for the proposed process.

Jul 18, 2022

By S. H. Ash

The Pennsylvania anthracite-mining region is the only one in the world of major magnitude. As the deposits of anthracite in the United States are limited virt113.lly to Pennsylvania, the difficulties of this industry have been commonly considered a State rather than a national problem. However, there is also national interest in the conservation and wise utilization of all fuel resources and in the control of interstate waterways. The anthracite industry is confronted with the very se:;-ious :problem of accumu.lation of water in many of the mines. This problem must be solved soon if progressively higr-er mi~ing costs are to be avoided. The water proble~ cannot be solved by the operating compa,nies without State or Federal aid, or both, owing to the magnitude of the work requir~d, diversity of interests of the coal ana surfa.ce ovmerships, hazard to the whole mining community, and interests affec~ed outside the mining region. The cost of abati~ the ever-increasing_surface seepage to mine workings and of handling this seepage once it }3s occurred is beyond the economic resources of most ope~ating ma.'18.gements. The data in this paper giving the high lights of the water problem and indicating what appears to be a step in the right direction are based upon observations made during the past year that the industry desires and believes it is to the npublic interesttr to keep mine workings free of flood end surface waters.

May 1, 1941

By P. L. Ngwenyama, W. W. deGraaf

South Africa is one of the leading producers and exporters of coal globally. A significant amount of the country’s production is obtained from previously mined underground bord and pillar workings. This coal is in the form of pillars and remnants on the roof and floor of the old workings. The good quality coal pillars were left behind as primary support during underground bord and pillar mining operations. Due to the depletion of virgin coal reserves, the pillars and remnant coal are now removed using opencast mining rather than underground methods. However, the secondary extraction of pillars and remnant coal from the old workings using opencast methods entails some serious challenges that have a negative impact on the safety and productivity of the operations, affecting both personnel and machinery. If these risk factors and challenges are managed properly, then the opencast mining operations could remove the pillars safely at recoveries competitive with those of virgin coal operations. In this study we review the recurring challenges affecting opencast pillar mining by means of field investigations and consultations with experts at five opencast pillar mining operations, and evaluate the best practices used to combat these challenges. It was found that each mine has its own unique conditions and challenges.

Dec 1, 2021

By V. Thangadurai

The critical problems in commercialization of the present solid oxide fuel cells (SOFCs) and useful electrical and physical properties of IT-SOFCs electrolytes are discussed briefly. The conductivity behavior of the perovskite-type and perovskite-related structure metal oxides are summarized. Perovskite-type La0.9Sr0.10ao.8Mgo.203_8 (LSGM) exhibits high ionic conductivity of 0.1 S/cm at 800 °C. In order to improve the electrical conductivity of LSGM and the In analogue of LSGM, substitutions have been made at the A-and B-sites. Substitution of trivalent La3+ by isovalent Pr3+ in LSGM and La09Sro ilno.sMgo.202.85 (LSIM), yield new mixed conductors. Among the investigated compounds in the present study, La0APro.4Sro.21no sMgo.2028 exhibits the highest total electrical conductivity of 3.2 x 10-5 S/cm at 200 °C in air with the lowest activation energy of 0.44 eV (200-700 °C). LSIM and Pr-substituted LSGM and LSIM perovskites show p-type electronic conductivity in the oxygen partial pressure range 10-5 ? 0.21 atm at 750 °C. The perovskite-type solid solution SrSn1-xFex03 exhibits compositionally driven phase transitions. For example, compound of the composition x = 0 to 0.3 crystallizes in an orthorhombic GdFeO3-like perovskite structure, where as that of x = 0.4-0.9 crystallizes in simple cubic SrTiO3-like, and that of x = 1 in orthorhombic structure. The electrical conductivity of SrSn1_xFex03 increases with the increasing Fe content and reaches a value of about 10-1 S/cm at 25 °C in air for x = 1. Compounds with low Fe content exhibit both ionic and electronic conductivity, while the higher Fe content 0.5) perovskites are electronic conductors over a wide range of oxygen partial pressure of 10-22? 0.21 atm at 750 °C.

Jan 1, 2005

By P Jones

Fosterville Gold Mine is an underground operation located approximately 20 km northeast of Bendigo and 170 km north of Melbourne. Fosterville is the most productive gold mine in Victoria, producing over 100 000 ounces of gold annually. Access to the underground is via two portals cut into previously mined open pits. Fosterville is 100 per cent owned and operated by Northgate Minerals, a gold and copper producer with mining operations, development projects and exploration properties in Canada and Australia. (Northgate Minerals Corporation, 2010).Underground operations commenced in 2006 with ore production focused on three orebodies – Phoenix, Ellesmere and Falcon. Primary ventilation to the existing operation is provided by wall mounted exhaust fans located underground. This system provides approximately 220 m3/s of primary ventilation to the operations with intake achieved through the portals. Exploration drilling during recent times has uncovered another lode, the Harrier orebody, located 2.2 km to the south of the existing workings. Due to the location of the new Harrier orebody, vent analysis revealed the requirement for a separate source of primary ventilation to service Harrier. Figure 1 shows a current underground long section and the location of Harrier in relation to the existing workings. A number of options were considered, including a parallel decline from one of the existing two portals, however, a 4 m diameter, 350 m deep surface ventilation shaft was selected as the most suitable and feasible option for the mine.In December 2009, geotechnical drilling commenced to determine the most suitable location for the shaft. Site locations were constrained by a number of factors including interaction with current and planned surface infrastructure as well as proximity to nearby community members at the southern end of the mining lease. Results from the geotechnical drilling indicated that the majority of the proposed shaft would be suitable for a 4 m raise bored shaft. However, the top 40 m of the proposed shaft were deemed unsuitable for raiseboring due to zones of weakness that would likely influence the stability of a 4 m diameter shaft (Robinson, 2010). Following independent geotechnical advice and input from experienced raiseboring contractors, it was decided to construct a 40 m presink prior to raiseboring activities.A crane mounted auger was chosen as the preferred method to construct the presink. This method differs substantially from traditional blind sinking methods which are highly labour intensive. The auger, or drill, is designed and built to be attached to a crane base using engineered pivoting cradles. The auger is suspended from the crane jib by pennant ropes attached to hydraulic rams. The auger applies rotation and axial loads to the drilling tools via a telescopic steel bar (Kelly Bar). Drill tools are attached to the bottom of the Kelly Bar and comprise an assortment of drilling buckets and reaming barrels. Drilling buckets cut in situ material and collect the spoil for removal and are used for the excavation of the ‘pilot hole’. Reaming barrels are used to expand the diameter of the excavation by directing cuttings into the pilot hole which are then removed by the drilling bucket. In June 2010, the presink was constructed utilising a crane mounted auger with support to the shaft walls applied via a remote fibrecrete unit. The excavation method involved cutting a series of smaller diameter holes (2.4 m wide) before reaming out to the final diameter (4.7 m wide) in 4 - 5 m vertical increments. Fibrecreting activities were carried out on the backshifts, to ensure the stability of the excavation and minimise interaction between the two units. The presink was completed on time and offered many advantages compared to traditional blind sinking methods, including safety, costs and timing. This paper will examine the benefits of this method as well as lessons learnt and future applications in the mining industry.

Mar 21, 2011

By Tiago Ramos Ribeiro

A redução do ferro é a etapa da produção de aço que mais consome energia e emite CO2. Os processos de redução direta são uma alternativa ao tradicional alto forno devido ao uso de H2 no gás de redução e consequente menor emissão de CO2. Existem duas tecnologias principais, Midrex e Energiron (ou Hyl) que representam 80% da produção mundial de ferro esponja. Uma revisão das patentes publicadas por estas duas empresas foi realizada e foi possível descrever o funcionamento dos processos, os desenvolvimentos ao longo dos anos e evidenciar as diferenças. Ambos os processos são baseados em fornos de cuba onde os gases de redução fluem em contracorrente ao minério aquecendo-o e reduzindo o ferro. Os gases de redução são gerados pela reforma catalítica de metano. A reforma no processo Midrex é realizada principalmente pela reação com CO2, e no processo Energiron com H2O. Há uma versão sem um reformador separado, o processo Energiron ZR. Neste processo o gás natural é injetado conjuntamente com H2O e CO2 no reator de redução e o ferro recém reduzido funciona como catalizador das reações de reforma.

Aug 16, 2017

By Matheus Teixeira Fraga

Esse trabalho teve como objetivo avaliar os fenômenos termoplásticos de carvões coqueificáveis e sua relação com o tamanho de partícula. Para isso, dois carvões americanos e um de origem nacional foram amostrados, caracterizados e separados em três tamanhos de partículas. Após a preparação das matérias-primas, ensaios termogravimétricos, de dilatometria e plastometria foram realizados a partir dos diferentes tamanhos de partícula. Os ensaios termoplásticos mostraram que o carvão nacional apresentou propriedades plásticas extremamente desenvolvidas e que a granulometria não afeta essas propriedades. No entanto, para os carvões americanos de alto e médio volátil diferenças importantes foram observadas, que indicam uma redução das propriedades termoplásticas com a diminuição do tamanho de partícula.

Oct 30, 2017

By André Luis de Oliveira

O Alto Forno 3 (AF3) da Companhia Siderúrgica Nacional (CSN) é o equipamento muito importante no processo siderúrgico da Usina Presidente Vargas (UPV), situada em Volta Redonda (RJ), por responder por mais de 70% da produção de gusa da UPV. Na produção de gusa é gerado o Gás de Alto Forno (GAF), subproduto de alta relevância, pois este gás sai do topo do AF3 com grande pressão e cinética, energia essa passível de utilização. Em 2007 a CSN, optou por adquirir um equipamento denominado “Top Pressure Recovery Turbine” (TRT), capaz de aproveitar tal energia para gerar energia elétrica. Em 2013, a equipe de supervisores da KHI – Kawasaki Heavy Industrie, fabricante da turbina, veio para o Brasil para realizar no equipamento os testes a frio e a quente para na seqüência vir a operá-lo. Ocorre que fatores alheios ao objetivo desta apresentação impediram a equipe da KHI de partir o equipamento no tempo previsto, bem como de retornar ao Brasil para dar seqüência nas atividades. Em novembro de 2013 a CSN definiu por partir o equipamento com recursos próprios, sendo este o foco do trabalho. A presente contribuição técnica vem mostrar o trabalho desenvolvido internamente pelo grupo técnico a fim de finalizar o projeto e colocar a Turbina de Topo (TRT) em operação, fato este dado total ênfase pela direção da empresa devido ao cenário nacional de crise energética em que os valores de energia estavam no limite máximo permitido pela legislação e impactando diretamente nos custos da empresa.

Sep 25, 2017

By Hui-bin Wu, Rui Yuan, Yang Gu, Peng-cheng Zhang, Zheng-zhi Zhao

The corrosion behavior of three kinds of medium-Cr rolled steel pipeline steels in carbon dioxide collecting and transporting environment at different temperatures was studied. The results shew that the 5Cr sample was most affected by temperature. When the temperature rised from 30 °C to 90 °C, the corrosion rate increased from 0.12 mm/a to 1.87 mm/a, which was increased 15.6 times. The corrosion rate of 7Cr steel at 30 °C was similar to that of 5Cr steel. However, as the temperature increased, the corrosion rate rised slowly, increasing by 2.4 times at 90 °C. The corrosion rate of 9Cr steel was not obvious with temperature, and it was always below 0.06 mm/a. The thickness of the corrosion product film of the three samples gradually increased below 70 °C, and suddenly increased above 70 °C. This was related to the negative temperature coefficient of the solubility of FeCO3, and the thickening of the product film also affected the ion exchange of the cathodic reaction. An increase in the Cr content contributed to grain refinement and increased the proportion of the small-angle grain boundaries. More fine grains mean an increase in the total length of the grain boundaries, which could provide a diffusion channel for the free Cr element; on the other hand, the low-angle grain boundary structure was more orderly, with a lower free volume and lower interface energy. Under the combined effect of both, 9Cr steel and 7Cr steel had high volta potential and better corrosion

Oct 1, 2019

By James D. Bamburak

Total mineral production in Manitoba has averaged C$1 billion over the past ten years. Industrial mineral production has comprised almost 10% of the total, with more than half coming from the aggregate sector. In southeastern Manitoba, tantalum, spodumene and amblygonite concentrates, cesium and rubidium ores, cesium formate, dimension stone and sphagnum peat moss are produced. Gypsum, high-calcium limestone and lime are produced in the Interlake area. Early industrial mineral production consisted of tools and implements, salt and pottery. Historical production has included: salt, building stone, aggregate, lime and dolime, lignite coal, gypsum, natural and Portland cement, calcium bentonite, brick, light-weight aggregate, caustic soda and soda ash, and silica sand. Future industrial mineral production may come from reactivated quarries, pits and wells or from new producers of current commodities. Newproducts may include: stainless steel master alloy, silicon metal, titanium and magnetite, lithium carbonate, float-plate glass and ferrosilicon, "marble" dimension stone, magnesium metal, potash and kaolin.

Jan 1, 2001

By Rozbeh Moghaddam, William D. Lawson, Priyantha W. Jayawickrama, Hoyoung Seo, James G. Surles

"This study provides calibration of resistance factors (?) for design of driven piles to implement Load and Resistance Factor Design (LRFD) for bridge foundations using Texas Cone Penetration (TCP) Test data. The basic research approach was to compile a database of published full-scale load tests including projects from the Texas Department of Transportation’s (TxDOT) historical archive and projects from neighboring state DOTs. Load test results from neighboring states were leveraged by performing new geotechnical borings with TCP tests at the project sites. The final dataset consisted of 30 load tests performed on precast square concrete piles, with pile widths ranging from 356 to 508 mm and penetration depths ranging from 5.2 to 25.5 m, driven in soils. Ultimate capacities for each load test were interpreted based on Davisson, 5%, and 10% settlement criteria. These measured ultimate capacities were compared against predicted capacities estimated from TCP blow count values (NTCP) and design charts following the procedures outlined in TxDOT’s Geotechnical Manual. From the comparisons, statistical parameters of the biases (??= measured capacity/predicted capacity) such as mean and coefficient of variation were obtained. Resistance factors (?) for LRFD were then determined using Monte-Carlo simulations for each ultimate capacity criteria with the target reliability indices of 2.33 and 3.00.INTRODUCTIONThe Texas Department of Transportation (TxDOT) has used the Texas Cone Penetration (TCP) test since its development in the 1940s. The TCP test is an in-situ penetration test to characterize the materials encountered during geotechnical exploration. Texas currently maintains over 53,000 bridges in the National Bridge Inventory (FHWA 2016), and most of these bridges plus other transportation infrastructure in Texas are supported by foundations designed using the TCP test and its associated foundation design method. The Oklahoma DOT adopted the TCP test and foundation design approach in the 1970s, so the foundations for most of the 23,000 bridges in Oklahoma’s inventory were also designed using the TCP method. With this significant body of experience, the TCP method has been viewed as a straightforward, relatively easy-touse foundation design method that consistently yields safe, serviceable, economical, and maintainable foundations. TxDOT’s deep foundation design method is documented in the TxDOT Geotechnical Manual (TxDOT 2012) and currently employs the allowable stress design (ASD) approach. However, the Federal Highway Administration (FHWA) has mandated that the states begin to implement the LRFD method in place of the older ASD approach (Densmore 2000). This paper presents resistance factors at ultimate limit state (ULS) for design of driven piles using the TCP test, resulting from efforts to be in compliance with the FHWA policy."

Jan 1, 2017

By R. Burrell, N .. L. Lapp

"Except for asthma and pulmonary infections, the types of lung disease that have been of immunologic interest the longest are the various mineral pneumoconioses. Because of their chronicity, type of pathology produced, and well-known immunotoxic properties associated with the dusts inciting them, the pneumoconioses have long drawn attention to the possibility that the immune system has not only been modulated but that its effectors have possibly contributed to their pathogenesis. All of the mineral dusts reviewed here have definite immunomodulating properties and act on various cellular and molecular components of the immune system. Further, each has an immunotoxic potential to induce either hypersensitivity (as in the case of beryllium) or other types of immune injury. This article reviews the immunologic aspects of the four major occupational minerals that have an immunologic impact on the lung: asbestos (particularly chrysotile), silica or quartz, beryllium, and coal mine dust.These agents have many things in common, yet each is distinctive. Although the possibility still exists that these mineral particles can adsorb intrinsic tissue antigens or extrinsic organic antigens to their surfaces and initiate immune responses to the adsorbed antigens, only one, beryllium, can act as an antigen itself. Silica is a profound macrophage toxin and thereby exerts many effects on those factors controlled by macrophages. Asbestos has undergone the most immunologic studies resulting in a much dearer picture of how it may contribute to immunopathology. Coal mine dust is the agent about which least is known immunologically, partly because there is no such thing as purified coal mine dust or a standard by which coal mine dust can be defined. Indeed, there are studies that use only the dust from the ground coal itself, whereas other studies use the total dust collected from air samples of a working mine in the belief that other types of dusts (e.g., silica from roof bolt drilling, from sand ground on the rails by cars, and from surface drilling) contribute to the disease (Figs. 1 to 5). This properly is coal mine dust and is poorly characterized. Yet, workers exposed to these dusts share similar reactive characteristics and they may be considered collectively as well as individually."

Mar 1, 1992

By D. E. Keeley

Introduction Gunite is a mixture of sand and cement applied to any surface by being shot by compressed air through a nozzle, where it is wetted just before leaving the orifice. The mixture is transported through a hose from a machine called a 'cement-gun'(l). Guniting of rock surfaces has been standard practice at the Mcintyre Porcupine Mines, Limited, for several years. Where used on walls and backs of cross-cuts; shaft stations, and other rock openings, as an air seal, gunite has eliminated the necessity of constant scaling to keep rock from falling from these places, and, under worse conditions, it has been used in place of timber supports. This has been of definite help in reducing costs, promoting safety, and minimizing fire hazards. During the past year guniting has been quite extensively used here in the rock head-works of the new internal shaft, No. 12, sunk from the 3,875-foot level. Gunite is at present being applied to the stations of that shaft well below a mile from the surface. This paper describes the method of guniting as carried out at the McIntyre, and illustrates how, by the adoption of this process, mining problems connected with scaling and loose ground have been completely solved. It is hoped that the information presented may stimulate discussion and assist in the use of gunite in this and other mines. The guniting method of applying cement was first developed by Carl E. Akeley (2), Curator of the Field Museum, Chicago, in 1907, and was exhibited in New York at the Cement Show in 1910. The museum was located in one of the old World's Fair buildings, built of roughcast and in bad repair. Mr. Akeley, who was a man of inventive nature, set about devising means of applying cement to repair the walls. The cement-gun was the result. Mr. Akeley was a taxidermist of note, a sculptor, and also the inventor of the Akeley camera. In his work, he was in the habit of using fast setting materials to build up foundations for statues, etc.

Jan 1, 1934

By Aline Maria dos Santos Teixeira

Serpentinite is an ultra basic and metamorphic rock consisting mainly of magnesium, calcium and silicon oxides. The rock under study is a host rock of chromite mine located in Andorinha, BA. The objective of this paper is to evaluate the rock's physical and chemical characteristics to be used as an additional fertilizer of acid soils. After comminution, rock samples were submitted to chemical analysis, XRD, SEM-EDS and TGA. Afterwards, particle size distribution was determined. Result analysis confirms that our rock consists mainly of dolomite, calcite and diopside. According to the result obtained, it can be said that the serpentinite rock has promising applications in agriculture for the correction and additional fertilization of acid soils. However, it is necessary to study the characteristics of the rock such as its dangers and toxicity as well as evaluate them according to the legislation for corrective acidity.

Jan 1, 2010

By S. Y. Tan

The thermal stability of fully silicided NiSi with arsenic doping on silicon was investigated. The aims of the work were to investigate the Ni silicide phase-related issues associated with arsenic dopant and thermal annealing on Ni-FUSI/HfO2/Si and Ni-FUSI/HfSiO/Si gate stacks. It was found that arsenic-incorporation demonstrated some improvement in both morphology and phase stability of nickel silicided films at high processing temperatures regardless underlying gate dielectrics. The correlations of Ni-Si phase transformation and arsenic doapnt with their electrical and physical changes were established by sheet resistance measurements, X-ray diffraction (XRD), atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS) analysis. Furthermore, the modulation of the work function (WF) of Ni fully silicided gates by arsenic impurity is presented, comparing the effects of dopant (As) on the WF and silicide phases (NiSi and NiSi2). It confirmed that the work function of NiSi can be tuned by implanting arsenic dopant, but it ineffective for NiSi2 phase.

Jan 1, 2010

By Igor Zh. Bunin

A model for developing electric discharges between sulfide mineral (pyrite) particles under high-voltage nanosecond pulses in a liquid medium (water) is considered. A possibility of electrical breakdowns of liquid gaps between particles under nanosecond pulses is shown. This probability and the energy released in discharge channels depend strongly on the sulfide conductivity.

Jan 1, 2010