Search Documents

By Jorge Alberto Soares Tenório, Flávia Paulucci Cianga Silvas, Bianca Medeiros, Denise Crocce Romano Espinosa, Ivo André Homrich Schneider, Daniella Cardoso Buzzi, José Roberto de Oliveira

"AMD is one of the main problems associated with mining activities and the techniques used in their treatment may be the biosorption. The aim of this work was to study the rice husk as a biosorbent for the AMD treatment keeping constant: pH (2.6), biomass concentration (1g.L-1), temperature (25°C) and agitation (175rpm). And varying the contact time of 5, 20, 60 and 240 minutes. Rice husk samples will be characterized before and after the biosorptives tests through analysis of SEM and IR. The micrographs indicate the occurrence of micro-precipitation and changes in biomass physical structure. Since the infrared spectra indicate changes in functional groups present in the biomass before and after the biosorptives tests. AMD synthetic solutions will be analyzed by ICP in order to quantify the metals concentration captured by biomassIntroductionThe preoccupation for the environment has led the industry in general, to treat their waste. As the only industrial activity is increasing, the pollutants generated must undergo treatment processes aimed at reducing pollution, and therefore, less aggression ecosystems.In mining there is waste water with accumulation of heavy metals, and these are harmful to health of living beings, thus being one of those industries responsible for some pollution of the environment. These wastewater in contact with oxygen to generate an acidic water is called acid mine drainage (AMD). This aqueous solution has a pH below 3 and varieties of dissolved metals. When this solution comes in contact with water, generates a series of environmental problems, so there is a need to recover the metals present in the DAM."

Jan 1, 2012

By W. M. Cross

Bubble attachment time measurements for the rare-earth phosphate minerals monazite and xenotime were made as a function of oleate concentration, sodium fluoride addition, and temperature. Results indicate that the rare-earth phosphates behave similarly to other phosphate minerals, notably collophanlte and fluorapatite, which have been studied previously. The addition of sodium fluoride yielded a modest decrease in bubble attachment time with fluoride additions below the apparent fluoride surface precipitation point, while at fluoride additions greater than the apparent precipitation point a significant decrease in attachment time occurs. Increasing the temperature or the system gave a slight decrease in bubble attachment time in the absence or sodium fluoride. With sodium fluoride addition and below the apparent fluoride surface precipitation point, an increase in temperature actually increased the attachment time. For sodium fluoride additions above the apparent fluoride surface precipitation point, a temperature increase significantly decreased the attachment time.

Jan 1, 1989

By Pengfu Tan

A thermodynamic model has been developed to model the desilverising process of lead by the addition of zinc during lead refining, whereby silver-zinc solid solutions are formed, and floats out of the dissolved zinc/silver in the lead bath. The solubility of silver-zinc solid solutions in lead decreases with falling temperature. A number of variations and modifications of the desilverising process are modeled, and applied to a wide range of silver contents in lead bullions in the industry.

Jan 1, 2005

By P. S. Arthur

The ISASMELT? process is a submerged lance smelting technology operating in smelters in Australia, the USA, Belgium, India, Germany, Malaysia and China. Further plants are under construction in Peru and Zambia. Following the invention of the Sirosmelt lance technology Mount Isa Mines recognised the commercial potential in the novel top blown bath smelting process and embarked on a development program that has lasted more than 25 years. After successful operation of pilot plants and demonstration plants producing copper and lead, Mount Isa Mines decided to license the technology to external companies. Since the purchase of Mount Isa Mines by Xstrata in 2003, Xstrata Technology has assumed responsibility for transferring the technology to ISASMELT? licensees. In the 15 years since the first commercial furnaces started operation plants have been constructed (or are under construction) with a combined annual smelting capacity of more than six million tonnes of concentrates or secondary raw materials. Process development continues on the commercial scale plants at Mount Isa and elsewhere. Many of the improvements implemented by plant operators have been passed on to, and adopted by, other licensees. Exchange of ideas and technical improvements occurs through ad hoc visits to fellow licensee sites and through regular licensee workshops arranged by Xstrata Technology. This paper updates the reader on the status of various ISASMELT? plants either operating or under construction. It highlights the important role that the technology provider?s operational experience plays in ensuring that new smelting plants ramp up quickly to nameplate capacity.

Jan 1, 2006

By Toshio Kurikami, Koichi Yamazaki

"Toho Zinc Co., Ltd Chigirishima Refinery has the production capacity of electrolytic lead for 95000t/y by sintering- blast furnace electrolytic process. Lead raw materials are lead concentrates, spent batteries and dusts that contain lead from other companies, and these are handled by existing smelting process. There are many circulation materials in the process, because the system has been constructed with improving the recovery rate and protecting the environment. This report describes material balance in each process, distribution of the lead and various components, and it examines present state of the processing. In addition, we report the result that we have tried to improve the work environment.IntroductionThe Chigirishima Refinery of the Toho Zinc Co., Ltd. is located in Chigirishima, an island 4km off the coast of Takehara-city, Hiroshima, Japan. The Chigirishima Refinery began lead smelting operations in 1951.The Chigirishima Refinery adopted the sintering-blast furnace-electrolytic process and has an electrolytic lead production capacity of 95,000 tons/year. The existing smelting process handles raw materials from lead concentrates, spent batteries, and lead-bearing dust from other companies. This system was constructed with the intentions of improving material recovery ratios and protecting the environment; therefore, there are many materials recirculating throughout the smelting process. This report describes the material balance in each process and the distribution ciflead and various components, and it examines the present state of processing. In addition, we report the results of our attempts to improve the work environment."

Jan 1, 2000

By Mike Adams

Comprehensive pilot testwork has been conducted on BHP Billiton's Ravensthorpe nickel laterite deposit over a fifteen-month period at Lakefield Oretest. Some 228 tonnes of ore were processed in a beneficiation pilot-plant comprising scrubbing, attrition scrubbing, screening and thickening over sixteen pilot runs with an average mass closure of 99.2%. This produced a suitable feed for hydrometallurgical piloting over seven runs covering 1,680 hours of operation. The integrated EPAL® (enhanced pressure acid leach) circuit comprised a limonite pressure acid leach front end discharging into a saprolite atmospheric leach circuit and subsequently to induced jarosite precipitation, counter-current decantation, iron removal, mixed hydroxide precipitation, and manganese removal. The pilot plant met its key objectives in demonstrating the flowsheet's technical viability, and generating raw data inputs for the project feasibility study. Rapid, intensive data capture, collation and reporting helped solve key flowsheet issues. The pilot plant also demonstrated its value as a risk management tool in the resolution of numerous engineering, metallurgical and materials selection issues at a manageable scale. A disciplined approach to experimental planning, operation and management was a significant contributor to the overall success of the campaign. Keywords: Ravensthorpe, Nickel, Piloting, Beneficiation, Pressure, Leach

Jan 1, 2004

By Carlos Maurício F. Vieira, Giulio R. Altoé, Maria Carolina A. Teles, Sergio N. Monteiro, Maycon A. Gomes, Frederico M. Margem, Gabriel O. Glória

Due to growing concern about the ambient impacts, the society is demanding for materials that are environmentally friendly. The lignocellulosic fibers, like PALF fibers, appears like an option to replace the synthetic ones in composites with polimerics matrices. Besides the environmental advantages, the lignocellulosic fibers have economical and some properties advantages like the low density in comparison with the synthetic fibers. Nowadays the lignocellulosic are used in industries, like the automobile and aerospace. This objective of this study was to analyze the absorbed impact energy of the composites reinforced with PALF fibers. The fibers were incorporated into the polyester matrix with volume fraction from 0 to 30%. The results showed increase in the absorbed impact energy with the increase of the percentage of fiber incorporated. The fracture surface of the specimens were analyzed by SEM (scanning eléctron microscope) and indicates that the PALF fibers act as reinforcement for the polyester matrix.

Mar 1, 2017

By Chengyi Ding, Xuewei Lv, Changyang Ji, Rende Zhang, Xiangwei Zheng

The fraction of liquid phase in sintered ore can be the most important factor to determine the sinter quality and yield in sintering process. The generation ability of liquid phase for mixture of iron ore powders is determined by basicity, roasting time, roasting temperature and chemical composition of iron ores. Five different iron ores were selected in this study and the dried powders of iron ore and CaO reagent (<200 mesh) were homogeneously mixed together at their required proportions, then 15g of the mixture was pressed under a pressure of 20MPa to make a cylindrical sample with a diameter of 20mm. The sintering temperature in this study was kept at 1280℃, the gas phase is air, the holding time was varied with its three levels of 5min,10min and 15min. After that, the sample was cooled under room temperature in the air, and the cooled sample was analyzed by using zeiss optical microscope. The mineral phase compositions were quantitatively determined with an open source image processing software, Image J whicn can calculate the fraction of liquid phase. Besides, the study on how to estimate the sintering behavior of the raw materials in different conditions by the theoretical calculation is of vital importance, and the development of this will greatly improve the sintering production. Factsage will be used to calculate the liquid phases formulation during the sintering. Comparing the experimental results and the theoretical calculation shows that the mass of liquid phase increases with increasing basicity during the sintering, besides, the mass of calcium ferrite increases with increasing basicity. The generation ability of liquid phase of iron ores can be predicted through the experiment verification.

Jan 1, 2015

By Nobuo Takahashi

Effective solvent extraction media have been investigated for purification of rare earths. At first, a quaternary ammonium compound was studied. The counter anions of rare earths and organic dielectric substances were tested to improve separation factors,. And second, crown ethers were selected for extractant. Several diluents of crown-adducts were tested to improve solubility and distribution coefficient as well as the counter anions of rare earths. Especially, in the presence of strong reducing agents, highly selective extraction of europium from other rare earths was observed. The third extactnts were ß -diketones. Presence of organic dielectric substances was very effective to improve separation factors. Though those. three groups of extractants were suitable for mutual separation of light rare earths, alkyl esters of alkyl-phosphonic acids were suitable for mutual separation of heavy rare earths because of their high separation factors. To keep proper pH value was necessary for acidic extractants, so control method of the solution pH was studied with high molecule insoluble amines or salts of those.

Jan 1, 1995

By Zhongning Shi, Ramana G. Reddy, Min Li, Zhaowen Wang

Electrodeposition of cobalt from cobalt tetrafluoroborate (Co(BF4)2) was investigated using 1- butyl-3-methylimidazolium tetrafluoroborate (BMIMBF4) ionic liquid. The experiments were conducted at 353 K. Chronoamperometry experiments confirm that the electrodeposition of cobalt on tungsten electrode proceeds via three-dimensional instantaneous nucleation with diffusion-controlled growth process. The average diffusion coefficient of Co(II) was found to be 7.5 × 10-8 cm2s-1 at 353 K, which is in good agreement with the estimated value from cyclic voltammetry. The electrochemical deposit was characterized using SEM-EDS and XRD methods. The SEM image shows formation of a dense and compact deposit at - 0.75 V. The EDS and XRD analysis confirm that the obtained deposit is pure cobalt metal.

Jan 1, 2015

By J. M. Tourre

1995 have seen a continuation of a positive trend in the Rare Earth industry The availability of a greater diversity of Raw Material has brought additional flexibility to the Producers permitting better economics China remains the major raw material source; Chinese concentrate producers have increased capacity in 1995 (Baotou, Sichuan, etc) China&apos;s role in the Rare Earth industry will continue to evolve; the acquisition of a majority equity position by San Huan/CNNC will have a significant impact on both the Rare Earth and Magnet markets Chinese producers are increasing the quality of their products and realize their true values Chinese market, itself, is also changing as the internal needs for separated rare earth&apos;s grow Already already producer of Lamps, Loudspeakers, Magnets, and TV tubes, China is in an unique position where the potential of its internal market might be more promising than the prospects outside China 1995 has also seen the application market become more diverse and complex. There are new applications growing at a very strong pace (such as battery alloy), applications that are now penetrating their target markets with significantly increased growth rates (such as bonded NdFeB), and some applications that became more complex requiring much more sophisticated products (such as catalysis). Rare Earth producers have to spend significant ressources in order to monitor the market trends in order to predict the demand and then adjust their raw material mix. Even though there is a greater diversity of raw material available, there is still some Rare Earth elements that are in excess, while other are just in balance. As a consequence rare earth producers invest heavily in R&D in order to develop new applications for these excess elements.

Jan 1, 1997

By Sadegh Safarzadeh, Anne-Marie Suriano, Stanley Howard

The electrodeposition of metal ions from aqueous electrolyte solutions has been a well-known process for the last half century. With numerous industrial applications such as electroplating, electrowinning and electrorefining, the kinetics of electrochemical reactions involved in the process has been extensively researched. Arrhenius-type rate equations, the Butler-Volmer equation, and the empirical Tafel equation are among the most important models to explain the rate of electrochemical reactions. The study of the kinetics of metal deposition is critical to understanding the underlying mechanisms through which a certain morphology of metal deposit is formed on the cathode. The purpose of this paper is to elucidate the influence of experimental parameters such as pH and additives on the rate and the reaction mechanism determining the rate limiting step of the electrodeposition reactions.

Jan 1, 2015

By Chikabumi Yamauchi, Mitsuru Tanahashi, Toshiharu Fujisawa

"Thermodynamic properties of impurities in molten silicon are of prime importance in developing economical production methods of solar grade silicon. In the present research work, thermodynamic properties of boron, the most difficult element to remove from molten silicon, were measured by chemical equilibration techniques at 1723 and 1773 K. Activity coefficients and self-interaction parameters of boron in molten silicon were determined by equilibrating the melt with solid BN under controlled nitrogen partial pressures. Interaction parameters between boron and nitrogen in molten silicon were also determined by equilibrating the molten Si-B alloys with solid Si3N4• Based on the data obtained, the stability diagram of the Si-B-N system was established.IntroductionPhotovoltaic power generation using a silicon solar cell is expected to be the most promising energy source, because it is inexhaustible, cleaner and more safety than conventional energy sources, such as thermal or atomic power generation. At present, expensive off-grade silicon for semiconductor (SEG-Si) is used for a solar cell production. However, if a large-scale photovoltaic energy conversion using silicon solar cell comes into wide use in the near future, silicon will be sure to be in short supply for the cell. Therefore, a development of a new large scale process for solar grade silicon (SOG-Si) production is definitely necessary, which can remove contained impurities from silicon.Among the impurities contained in silicon, boron is one of the most difficult ones to remove by a zone melting or an unidirectional solidification, because its segregation coefficient in silicon is close to unity (0.8). In addition, boron behaves as a p-type silicon semiconductor dopant and, therefore, its content in SOG-Si must be severely controlled. Although some attempts to remove boron by various metallurgical methods have been carried out [I -4], quantitative analysis has not been made due to lack in the information on the thermodynamic properties of boron in molten silicon. From this view point, the activity of boron in molten silicon was determined in the present study by chemical equilibration techniques at 1723 and 1773 K."

Jan 1, 1998

By Fuxing Yin, Akira Sato, Yoshiaki Ohsawa, Kohji Kawaharai

"INCRAMUTE alloy (nominally 45Mn-53Cu-2Al wt. %) has a specific damping capacity as high as 0.4, through a solid-solution and aging treatment. The damping behavior of the alloy is highly temperature-dependent and shows a peak near room temperature. The inadequate strength in the high damping condition restrains the practical application of the alloy, as structural components. Ferromagnetic MnB particles are dispersed in the alloy during induction remelting the matrix alloy in an argon atmosphere. Surface modification of the MnB particles by mechanical alloying (MA) and suitable control of the addition process cause a homogeneous distribution of MnB particles in the alloy. In the composite containing 2 wt. % MnB particles, temperature dependence of damping capacity is improved, and higher damping capacity is still retained in the temperatures over 60 °C. Meanwhile, the Young's modulus and tensile strength were also increased by about 20%. The roles of the MnB particles in improving both damping behavior and mechanical properties were also discussed.IntroductionMany viscoelastic materials, such as rubbers, polymers and plastics, have the superior ability to damp vibration and noise. However, in the applications as structural materials the high damping capacities of materials are pursued upon the satisfactory mechanical properties, especially those at elevated temperatures. Damping alloys are finding more and more applications in structures where noise and vibration ·should be ·eliminated. Specific damping capacity (SDC), defined as the ratio of the energy dissipated to the maximum vibration energy stored per cycle, is usually used to evaluate the damping capacity of alloys. INCRAMUTE damping alloy, developed by the International Copper Research Association, Inc., has a nominal composition of 45Mn-53Cu-2Al in weight percent. The high damping· microstructure of this alloy is obtained through the solution treatment at 820 °C followed by a water quench and aging at 400°C for 10 hours followed by cooling to room temperature [1]. With the heat treatment, a SDC peak ·vs. temperature of as high as 0.4 was observed in the alloy at the strain amplitude of about 10-3 while a tensile strength of about 500MPa was sustained."

Jan 1, 2000

By Nan Zhang, Lei Zhang, Gai-feng Xue, Lina Wang, Pu Liu

"A novel ß-diketone modified silica gel was synthesized by a simple reaction. The prepared material was characterized by diffuse reflectance FTIR spectroscopy and it was used for the adsorption of heave metal ions in the industrial waste water. The main parameters affecting the sorption of heavy metal ions, including pH, water flow rate, and elution, have been investigated in detail. Under the optimized operating conditions, most of the targeted heavy metal ions could be removed. The material could be simply regenerated by hydrochloric acid solution. The method is rapid, selective, economic and applicable to the removal of heavy metal ions from industrial waste water.IntroductionToxic organic pollutants and heavy metals ions mainly from industrial activities such as plating, metallurgy and dyeing industries, are a threat to human health and the surrounding environment, because of their toxicity and persistence after being released into the natural environment [1]. These pollutants must be removed or degraded to an acceptable level, before being discharged to the receiving waters. Therefore, detection and determination of heavy metal ions in industrial waste water is very important.Inductively coupled plasma optical emission spectrometry (ICP-OES) is the most used technique for the determination of heavy metal ions because of its capability for rapid multi-element detection over a wide concentration range and with relatively low detection limits. Compared to other techniques such as neutron activation analysis (NAA), X-ray fluorescence spectrometry (XRF) and inductively coupled plasma mass spectrometry (ICP-MS), ICP-OES has the above advantages. Some constituents in industrial waters, such as organic compounds and inorganic salts, may cause matrix effects. In order to achieve accurate and reliable results, an efficient preconcentration of heavy metal ions and their separation from the matrix are usually required."

Jan 1, 2012

By Esperidiana A. B. Moura, Michelle Gomes, Cordelia M. F. Escanhoela, Francisco R. V. Diaz, Angel Ortiz, Rene R. Oliveira

"This work evaluates changes in morphological, mechanical and thermo-mechanical properties of electron-beam irradiated HDPE/nanoclay and HDPE/Piassava fiber/nanoclay. Material samples irradiated with 100 and 200 kGy using a 1.5 Me V electron beam accelerator (room temperature, presence of air) were submitted to tensile, flexural, and HDT tests. MFI, SEM and XRD analyses were carried out. Correlation between properties was discussed. Results showed that incorporation of piassava (Attalea funifera Mart) fiber and nanoclay, followed by irradiation represented significant gain in thermo-mechanical properties. Changes in surface morphology and reduction in MFI were observed. In conclusion, it may be claimed that the incorporation of piassava fiber in small size particles and nanoclay in the HDPE followed by electron-beam irradiation effectively improved the polymer properties and led to materials with superior properties suitable for several industrial applications.1. IntroductionIn recent years, the preference for using natural fibers instead of synthetic ones in polymer composites has been growing significantly. In Brazil, due to the great diversity of woody and fibrous plants of our forests, a vast potential of natural fibers is found, presenting good mechanical strength properties, chemical and biological stability, fire resistance, abrasion resistance, shear strength and lightness, among other which may contribute to the development of new materials for different applications such as automotive, aerospace, construction, food segment, cosmetics and others [ 1]."

Jan 1, 2013

By Brian R. Green

Resin-in-pulp (RIP) technology has been developed for recovery of gold. It is now time to look forward to the potential for application of the technology to other situations. Some cases have been identified and have merited preliminary testwork. Four examples, which illustrate the potential of RIP, are dealt with in this paper. These include removal of metal-cyanides from pulps, recovery of manganese that is difficult to wash from filter cakes, recovery of nickel from low grade pulps, and recovery of zinc from process residues. The discussion includes descriptions of the problems, factors that affect the choice of resin, and factors that will affect the economics of the process.

Jan 1, 1998

By Runsheng Xu, Haiyang Wang, Pengcheng Zhang, Tengfei Song

Semi coke, a byproduct in the chemical industry, is a new fuel for blast furnace injection in China. In this study, semi coke and bitumite were milled into different size, ranged from 0.147mm to under 0.074mm. The content of volatile matter and ash, which affect the combustibility of semi coke, were measured using muffle furnace. The mixture, in which the proportion of coal in different sizes changed, was blend by semi coke and bitumite with different size. Activation energy calculation and the comprehensive combustion characteristic index of all kinds of blends was also discussed. The result obtained by Thermogravimetry –Derivative Thermogravimetry curves indicates that the smaller the size of mixture is, the lower for the characteristic temperature, and the better for its combustibility, Semi coke can be a substitute for anthracite in blast furnace injection.

Jan 1, 2015

By C. L. Lin

Transformation of linear grade distribution to volumetric grade distribution has been used to estimate the actual mineral liberation during wet, batch, ball mill grinding of a copper ore. The degree of liberation based on the multicomponent-multisize grinding liberation model using volumetric grade is lower than the apparent degree of liberation estimated from using King&apos;s linear intercept model.

Jan 1, 1987

By Chai Liyuan

Chromium-containing slag was detoxified by the method of microbial treatment using Ch-1bacteria isolated from nature by our research group, belonging to achromobacter sp. and with the characteristic of reducing high concentration of Cr(VI) in alkaline solution. The detoxifying process of Ch-1 to chromium-containing slag was studied by column-leaching techniques respectively. The results indicate that Cr(VI) in leachate can not be detected when chromium-containing slag has been column-leached for 7 days, and Cr(OH)3 content in precipitate is up to 32.8% with great value of resource recycling. Flowchart of engineering experimentation was ascertained based on the parameters of column-leaching experiments. Using the technique of pelletization of chromium-containing slag heap-leaching by Ch-1,the leaching rate of water-soluble Cr(VI) existing in chromium-containing slag reaches up to 100%, while the leaching rate of full chromium is up to 90%, when the process has been operated for 7-10 days under the conditions of 25-40C and consecutive spray by circular leachate. The content of Cr(VI) in chromium-containing slag after detoxified meet the national identification standard for extraction procedure inxicity for hazardous wastes(GB5085-1996) in China, moreover approximately 90% of Cr(VI) existing in chromium-containing slag has been recycled.

Jan 1, 2006