Search Documents

By Vladimir I. Skorohodov

The technology for copper utilization from circuit boards etching is proposed. The technology is based on combination of electrochemical and sorption methods. The conditions of copper electroextraction from ammonia-chloride solutions with obtaining of cathode copper are defined. The stage of electrolysis is destined for copper recuperation from etching process. Due to the electrochemical processes are unacceptable for cathode precipitation of the copper from diluted solutions such as rinse waters, the concentration on the strong-based cationites are used. After filtration throw the sorption columns solution is directed to the stage of circuit boards washing. It allows organizing close loop water recirculation. After saturation. resin is 'regenerated by chloride ammonium solutions. Obtained eluate directed to the etching stage, Generally. the technology provides copper recuperation and minimize wastes amount.

Jan 1, 2001

By Russell E. Clemons

Coarse-crystalline granite, quartz syenite, syenite, meladiorite, and anorthosite in the Florida Mountains, southeast of Deming, New Mexico, were originally mapped as Precambrian. They were remapped in 1971 and some of them described as Mesozoic intrusives. Several subsequent papers presented Precambrian and Ordovician ages. Zinc, lead, copper, silver, gold, manganese, fluorite, and barite mineralization in the Florida Mountains invite more extensive exploration. Clarification of ages of rocks and periods of alteration and mineralization are necessary for efficient exploration. Field observations combined with petrographic studies strongly suggest that all the coarse plutonic rocks are Precambrian and most were altered extensively by late Tertiary hydrothermal activity.

Jan 1, 1982

By Joachim Ulrich

The spreading and splashing behaviour of single tin, lead, copper, aluminium and steel droplets impacting on a solid surface were experimentally examined. The droplet impact was observed using a high speed video imaging technique. The onset of splashing and the mass of the secondary droplets of impacting tin and lead droplets was quantified by the weight difference of the droplets before melting and the splat after the impact. The spread factor and the mass of the secondary droplets in dependence of the impact velocity is shown for different droplet materials, initial droplet diameters, target temperatures in ambient air and inert gas atmosphere. An empirical found correlation predicting the transition from spreading to splashing is presented by means of dimensionless numbers.

Jan 1, 1999

By Dan A. Mackie

Continuous leaching of precious metals ores in a vat is possible using a jigging technique. This patented method promises to be competitive with heap leaching, particularly in northern climates, difficult terrain, high precipiptation regions, and environmentally sensitive areas. The paper discusses test work to date, plans for pilot plant testing and basic economics

Jan 1, 1990

By Jian Li, S. Penttila, W. Zheng

"Materials selection for Gen IV supercritical water reactor in-core components faces major challenges due to severe operating condition. Beside high-temperature mechanical properties, SCC and general corrosion resistance of commercially available materials are also major focuses in recent research. Recent reports suggest that certain types of surface modifications are beneficial to SCW corrosion resistance. In this study, the effects of surface modifications are investigated, and possible mechanisms for improved corrosion performance are discussed.IntroductionThe current Canadian pressure-tube supercritical water reactor (SCW) design specifies a core outlet temperature of 625°C under 25 MPa of pressure, with peak cladding temperature as high as 850°C. Challenges in materials selection include high-temperature mechanical properties, corrosion resistance, SCC resistance and radiation damage. Most of the SCW corrosion test results available are below 730°C. Early work by Allen [1] summarized the corrosion resistance of alloy groups including Ni-based super alloys, stainless and ferritic/matensitic (F/M) steels that can potentially be used for SCW reactors. F/M steels can only be used at low temperature sites (e.g. down stream piping). At 500°C and 25 MPa, F/M steels develop a thick but mechanically stable oxide layer. However, the long term stability of the surface oxide layer is largely unknown. Ni-based alloys appear to form very thin surface oxide, however pitting was observed in the vicinity of some intermetallic precipitates [2-5], and dissolution of major alloying components could pose significant problems for down stream piping [6]. In addition, concerns of Helium formation due to Ni transmutation prevented this alloy group to be used as fuel cladding. The corrosion resistant austenitic stainless steels (e.g. 316L) are found to be susceptible to localized corrosion such as pitting, intergranular attack and stress corrosion cracking (SCC) [7]."

Jan 1, 2012

By Núbia Suely Silva Santos, Alexandre da Silva Crespo, Frederico Muylaert Margem, Sergio Neves Monteiro, Anderson de Paula Barbosa, Michel Picanço Oliveira

"Environmental considerations in addition to technical, economical and societal benefits are increasingly promoting the substitution of natural fibers for glass fiber in polymer matrix composites. However, natural fibers are heterogeneous in their dimensions, specially the cross section, which plays an important role in their mechanical strength. The fibers extracted from the petiole of the buriti palm tree is a relatively unknown but promising natural fiber for composite reinforcement. In this work, a statistical analysis of the density of buriti petiole fibers using the Weibull methodology was performed. An attempt to correlate the fiber density with the diameter, precisely measured by means of a profile projector, was carried out. The results revealed an inverse dependence between the buriti petiole fiber diameter and corresponding density. Fracture tip observation by SEM suggested a possible mechanism that could justify this inverse correlation.INTRODUTIONIn the past decade polymer composites reinforced with natural fibers obtained from cellulose-based plants, known as lignocellulosic fibers, have been applied in several engineering sectors, specially the automobile industry as both interior and outside component [1-4].Environmental benefits as well as economical, social, and technical advantages are actually promoting the substitution of these lignocellulosic for the traditional glass fiber in polymer matrix composites [5]. Today several lignocellulosic fiber are being extensively investigated [6-11] and considered for reinforcement of polymer composites. Some relatively unknown lignocellulosic fiber with reinforcement potential, however, still need to be characterized aiming at future application in composites. This is the case of the fibers stripped of from the petiole of the buriti palm tree, which is endemic in the central and northern regions of South America [12,13]. Preliminary works on the possibility of using the buriti petiole fibers as composite reinforcement, has shown favorable results [14,15]."

Jan 1, 2012

By Thomas Brynjulfsen, Merete Tangstad

"Manganese ore fines, generated during mining and transportation, can not be added to the submerged arc furnace directly as they will prevent even gas flow through the burden. Low gas permeability in the burden will lower the degree of pre-reduction of ore and subsequently increase the carbon and energy consumption of the process. In order to utilize manganese ore fines in the furnace they are agglomerated into sinter, pellet or briquettes. The agglomeration process will however change the reduction properties of the ore. In this work the melting and reduction properties of sinter has been investigated.The melting temperature and melting mechanisms has been studied. The mineralogy of the raw ores and agglomerated has been found using XRD, and the composition established using EPMA(WDS). The effect of adding fluxes such as dolomite and quartz has also been investigated.IntroductionManganese metal is produced in a submerged electric arc furnace or in blast furnaces. The reduction of manganese oxide in blast furnace has in the recent years become more unusual due to the high consumption of reducing carbon material[5]. Manganese metal for alloying in steel usually contains silicon and iron, and are therefore called ferro manganese and silicomanganese.During mining, transportation and handling the manganese ore is broken up into different size fractions. The larger lump are used directly in the electric arc furnace, but the finer materials can not be added without treatment. The fine ore can disrupt the flow of CO and CO2 gas through the burden, subsequently reducing the degree of pre-reduction. The fine fractions must therefore be agglomerated into larger lumps, in order to promote gas flow. This can be achieved through a number of different processes. The agglomerate used in this work has been sintered, which means that is has been partly molten and reduced, in order to create bigger lumps."

Jan 1, 2012

By Ricardo Ponce

In recent years, ENAMI implemented modernisation plans at its two smelters in order to meet the government's environmental regulations introduced in the early 1990s. The modernisation plans defined the new SO2 and particulates emission targets, deadlines for compliance, and the revised treatment capacities of the smelters. At Las Ventanas smelter, the principal process change consisted of eliminating the reverberatory furnace. All the smelter feed is currently processed in a 4m diameter, 14m long Teniente Converter, using up to 34% oxygen enriched air. Dry concentrate is injected into the bath through tuyeres. A fuel oil burner compensates for any process heat deficiency. The Teniente Converter high copper content slag is cleaned in an electric furnace. This furnace is also used to melt internal reverts. This paper will discuss the successful operation of the slag cleaning electric furnace.

Jan 1, 1999

By Sergio Neves Monteiro, Nuã Simonassi, Helvio Pessanha Guimarães Santafé Jr.

"Thermoset polymers, like the polyester, become harder with increasing temperature owing to molecular crosslink formation, which is a thermal benefit for composite matrix applications. Natural lignocellulosic fibers, however, have low thermal resistance and tend to degrade with increasing temperature. Therefore, the combination of a lignocellulosic fiber, as reinforcement, with a thermoset polymer, as the matrix, results in a composite material with complex thermal behavior. In the present work, a thermal analysis was conducted on polyester composites with different amounts of coir fibers. Both TGA and DTG curves were analyzed to determine the effect of the coir fiber on the thermal resistance of the composites. It was found that the coir fiber sensibly affects the thermal behavior of the polyester matrix for fiber amounts above 10% in volume. This effect is associated with an increase in thermal degradation.IntroductionIn recent years, there has been an increase application of natural fibers as reinforcement of polymer matrix composites in several industrial sectors, with special participation in automobile components [1-3]. Figure 1 illustrates the different components of a modem BMW sedan that are fabricated with lignocellulosic reinforced polymer composites."

Jan 1, 2012

By M. M. Monte

A method for removing metallic mercury from contaminated tailing, using the flotation process, is described. In order to define some relevant parameters for the mercury flotation system, microflotation and electrophoretic mobility tests were carried out on (pure) metallic mercury in the presence of several surfactants. Based on the results obtained from fundamental studies a series of bench scale flotation experiments with mercury containing tailings from two wetland sites in Brasil were done. The results of microflotation tests with mercury showed that by using cetyl trimethyl ammonium bromide, an increase in mercury flotability is observed in the acid pH range, whereas in the presence of potassium oleate the highest mercury flotability was found in the alkaline pH region. The mercury flotability using potassium amyl xanthate was improved by the addition at sodium dithionate as an activator. The bench scale flotation tests with contaminated tailings from Poconé (brazilian wetland site) showed a recovery of 70% when sodium dithionate was used as activator and potassium amyl xanthate as collector. The resulting coefficient of separation is around 60%. However, the results of the flotation experiments with fine fractions from amalgamation tailings from Peixoto de Azevedo (brazilian wetland site) showed a low mercury recovery (32%).The results from this work suggest that since in the Poconé site tailings, the metallic mercury is not completely associated to the finer particles, the flotation process to recover the metallic mercury seems very promisor.

Jan 1, 1996

By E. Oshilna

The Mitsubishi process has many advantages pertaining to economical and environmental matters. These advantages have led to the installations of the Mitsubishi process in constructing new smelters: The Mitsubishi process utilizes highly oxygen enriched blast air and uses a special lime slag in the C?furnace. These characteristics change the . distribution of Impurities from other processes which use P.S. converters, Recently an Increased amount of secondary materials which contain impurities Is being treated at Naoshima Smelter. In order to cope with an Increment of the Impurities load and maintain the cathode quality, many Improvements have been Implemented. This paper discusses the impurities behavior In the Mitsubishi process and describes the measures taken to treat an Increased ?amount of secondary materials:

Jan 1, 1998

By Anne Kvithydl

Printed circuited boards contain considerable quantities of valuable metal, while also containing many environmental pollutants making them unsuitable for landfill. In this study the decomposition of common plastics used in printed circuit boards were studied. Polytetrafluoroethylene (PTFE), polyvinyl chloride (PVC) and polyethylene (PE) were heated in both CO, and argon atmospheres using a thermo-gravimetric furnace (TG) coupled to a mass spectrometer (MS). Soda ash Na,C03 and baking soda NaHC03 were used as reactants. The degradation temperatures and evolved gases are presented for single plastics and mixtures. Mixed plastics are shown to behave as a sum of the individual plastics. The mass loss temperature is the same in CO, and argon. However, less residue is formed when heated in CO,.

Jan 1, 2008

By W. L. Cornell

Ore microscopy was used in support of both bench-and large-scale continuous beneficiation testing programs. Reflected light microscopy and Vickers hardness measurements were utilized to help identify problems relating to mineral identification, mineral association, mineral liberation, mineral distribution in product streams, and froth entrainment. Specimens studied were size fractions of concentrates and tailings resulting from Bureau of Mines research to recover a siegenite-enriched product by beneficiating chalcopyrite concentrates. Other specimens were size fractions of bulk sulfide concentrates recovered during the enhanced amine scavenging of final tailings by froth flotation. The findings from studies directly affected flowsheet development.

Jan 1, 1987

By Jose Bengoa

Low metal prices and environmental restrictions are always a challenge for copper smelters operation and its productivity. Thus, in order to reduce production costs and control gas emissions, improvements of the Teniente Converter (CT) operation were made at 110 Smelter Plant of Southern Peru Copper Co., 110, Peru, and the main objective was to increase its capacity for smelting copper concentrates without affecting normal operation. The present work corresponds to a recent study conducted during the normal industrial operation of the Teniente Converter in this plant and, it shows the effect of increasing air oxygen enrichment from 28 to 34% on its productivity. The results show an increasing of concentrate smelting rate from 800 to 1370 tpd and hence a notorious improving in copper production, and practically no effect on the refractory consumption. The increment of the concentrate throughput, increases also the SO2 concentration and the sulfuric acid production, showing the effort done by this operation in order to accomplish the environmental Peruvian regulation.

Jan 1, 2003

By Chao Zhang, Kexin Jiao, Yi Qian, Jianliang Zhang

Now low-grade iron ore were widely used. However, one prominent problem is that the content of trace elements is higher than that in high quality iron ore. For the requirement of the content of Mn, Cr, Ni, Cu, and Ti in hot-rolled steel sheet and strip, the upper limits of these elements in sinter will be studied in this paper. Using the activity model of aggregation of electronic phased slag composition, the distribution ratio of each element in converter is analyzed and the content of each element in hot metal is calculated. Furthermore, through the thermodynamics method, the distribution ratio of each element in BF is analyzed and the content of each element in raw material is calculated. The upper limits of Mn, Cr, Ni, Cu, and Ti in sinter can be determined by calculating, the values are as follows: Mn 0.767%; Cr 0.552%; Ni 0.055%; Cu 0.159%; Ti 0.108%.

Jan 1, 2015

By N. Y. Ma

Solid wastes produced in ironmaking and steelmaking off-gas cleaning systems often contain zinc. The zinc level in these solid wastes is generally too high to recycle the wastes for iron through blast furnaces, but too low to economically treat the wastes for zinc through zincrecovery facilities. The behavior, status, and distribution of zinc in the ironmaking and steelmaking off-gas cleaning systems have been analyzed from three aspects: thermodynamics of zinc condensation, oxidation and deposition, correlation of zinc concentration with particle size and density, and aerodynamics of dust particles in the off-gas cleaning systems. Theory and supporting data show that spontaneous separation of zinc from iron-bearing dust occurs in the ironmaking and steelmaking off-gas cleaning systems. Dry off-gas cleaning systems provide the most favorable conditions and environments for zinc to separate from the dust. If highefficiency dry separators were applied and appropriately arranged in the off-gas cleaning systems, zinc would be concentrated, and the majority of the solid wastes could be recycled for iron recovery through blast furnaces.

Jan 1, 2008

By Tang Chaoho

Laboratory research on the reducing and matte smelting of Jamesonite concentrate has been carried out. The influence of the process conditions such as the smelting temperature, the amount of pyrite cinder (the agent of fixed sulfur) and the amount of additives on the smelting process have been studied. Under the optimum condition the direct recovery ratios of antimony and lead are 83.26% and 68.50% respectively. The ratio of fixed sulfur is 98.97% but more than 15% lead and 30% silver remained in the ferrous matte. The key problem to be solved of this new process is how economical and effective is the recovery of silver and lead in ferrous matte.

Jan 1, 2003

By M. I. Kalashnikova

Results of investigations concerning precipitation of heavy non-ferrous metals from solutions using precipitators based on elemental sulphur and lime with gypsum transfer to a separate product are given.

Jan 1, 2003

By Peter M. DiGiacomo

In situ leaching technology requires information about how injected fluids flow in the rock in relation to the localization of the valuable minerals to be leached. In oxidative leaching of sulfide copper ores, flow channels can be determined by the observation of residual iron oxides. In contrast oxide copper ores do not leave a detectable residue after leaching. Method is developed that allows a selective labeling of the leach residue with fluorescent compounds. The fluorescent zones can be detected in corings after the leaching operation.

Jan 1, 1981

By M. Wu, A. Kharicha, A. Ludwig

"The droplet formation during melting of a 400 mm diameter electrode is simulated with a multiphase-MHD approach. The computational model includes a layer of slag and a layer of liquid steel. A VOF approach is used for the interface tracking and a potential formulation is used for the electric and the magnetic field. The Lorentz force and the Joule heating are recalculated at each time step in function of the phase distribution. The first results provided by this model are presented.IntroductionThe Electro-Slag-Remelting (ESR) process is an advanced technology for the production of components of e.g. high quality steels [ 1-9]. An alternating current (Figure 1) is passed from a conventionally melted and cast solid electrode through a layer of molten slag to the baseplate. Because of the electrical resistivity of the slag, Joule heating is generated and the slag transfers this energy to ingot and mould surfaces and to the melting electrode tip. The molten metal produced in the form of droplets passes through the slag and feeds a liquid pool from where directional solidification takes place. The slag and the ingot are contained in a water cooled copper mould. As also the baseplate is water cooled, a heat flow regime is imposed that gives controlled solidification, and this results in improved structure characteristics of ESR ingots.This process involves two liquids, a liquid metal and a liquid slag. Each liquid is subject to a phase change due to melting and/or solidification. From a fluid dynamic point of view, the ESR process is clearly a multiphase process, with free interfaces (slag/pool, gas/slag), and with a mixed area (slag and falling steel droplets) [ 10-15].Physically, the development of the heat and mass transfer at the slag/droplet interface is important for the final ingot quality, composition and cleanliness. Visual observations of the droplet formation just under the electrode being melted is almost impossible. Due to the presence of high temperatures, opacity of the materials, and the presence of the mould it is not possible to directly observe the behaviour the slag/pool interface. Although usually assumed flat [1-9], a previous work [10] using a Volume of fluid (VOF) model has shown that the interface shape between a layer of slag and steel layer in a cylindrical cavity is highly coupled with the distribution of the electric current. A full scale simulation of the ESR process using a VOF model has shown that the shape of the pool interface is likely to be non flat."

Jan 1, 2011