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By T. Wang, R. G. Reddy

"The corrosion of stainless steel SS316L in a low melting point novel LiNO3-NaNO3-KNO3- NaNO2 eutectic molten salt mixture was investigated at 695K. After long-term isothermal dipping corrosion experiments, the SS316L samples were analyzed using scanning electron microscopy (SEM) equipped with energy dispersive spectrometer (EDS) to determine the topography and corrosion products. Dense and protective lithium iron oxide scale formed on the surface and prevented the SS316L sample from further severe corrosion. Therefore, SS316L is considered to be suitable construction material for solar thermal energy storage materials containers.IntroductionMolten salt mixtures have been considered as potential candidates for thermal energy storage and heat transfer media in solar energy applications. To apply the molten salt in the energy transfer process, the standard pipes made of stainless steel must be utilized to carry the molten salt mixtures in parabolic trough system of solar power production. The pipes encounter continuous flow of hot and cold molten salt every day. Thus corrosion of stainless steel in molten salt mixtures becomes extremely essential for the long-term utilization of the thermal energy storage media. The corrosion of passivity materials inside high temperature molten salt systems have been studied which gives fundamental understanding of basic mechanism about the corrosion process [1-8].The corrosion behavior of Fe-Ni-Cr alloys in an equi-molar LiNO3–NaNO3–KNO3 mixture was studied [9]. According to the XRD analyses, the major phases in the oxide scales were identified as LiFeO2, Fe3O4 and Cr2O3. A HITEC® salt mixture (NaNO3–NaNO2–KNO3) was also tested as a corrosion medium for stainless steel [10] and the corrosion rate was found to be affected by the protective oxide layer. In most cases, the alloys having more than 10wt% chromium show high resistance to corrosion in molten salts."

Jan 1, 2014

By Esther Carrera Martinez

Caraiba Metals is the sole brazilian copper custom smelter. The sulfur present in the various concentrates processed is recovered as sulfuric acid and oleum ,which are sold in the local market For quality assurance purposes, a study was carried out in order to determine how to control the arsenic content in the acid, allowing the continuous processing of concentrates with high levels impurity, The study was based on the process parameters of the washing towers and mist precipitators, Others process variables were investigated and their effects were used in support to confirm the results, After many analyses performed some interventions to improve the quality of the acid were implemented in the plant, which proved to be successful even by using a conventional purification system,

Jan 1, 1996

By Knut H. Bech, Stein Tore Johansen

"The collision efficiency for small particles relative to 2D spherical bubbles in a developed turbulent flow field were calculated applying an adopted version of the CPD program FLUENT. The turbulence field was related to bubble size and fluid properties. The results were compared with analytical theory. The turbulence intensity was found to be the most important single parameter for collision efficiency. Effects of boundary layer thickness and particle diameter were discussed. IntroductionRemoval of inclusion particles from melted aluminium can be facilitated by means of a rotor system that supplies kinetic energy and gas bubbles to the floating metal. At the surface the inclusions adhere to the surface dross or slagg which is removed at regular intervals by the operators. When applying computational fluid dynamics (CFD) to model such a system, one experiences difficulties with the large range of turbulent length-scales encountered, from the large geometrical scales of the rotor and container, through the bubble size and down to the particle diameter. A mathematical model for the complete system will be both complex and require an extreme spatial resolution. Another way of dealing with the problem is to model the micro-scale phenomena separately and apply the results to create a model for the macroscopic system. In a previous work [12] we addressed these problems and developed a procedure for calculating turbulence enhanced flotation to bubbles. It was found that turbulence may have a profound effect on the collision rate of particles to idealized bubbles. In this study we recognize that only a fraction of the total turbulent kinetic energy generated by the rotor's work on the liquid metal may contribute to enhanced flotation. By using a model spectrum for the turbulence, the fraction of turbulent energy in eddies smaller than the bubble diameter is calculated. A twodimensional CFD model was then constructed to calculate the collision efficiency between particles and bubbles of various sizes."

Jan 1, 1999

Kosaka Smelter & Refinery has a history of more than a century as a metallurgical department belonging to Kosaka mine. It has treated for a long time the "Black Ore" or the complicated concentrates dressed from it. The "Black Ore" is composed of black sulfides. It contains not only valuable metals such as gold, silver, copper, lead and zinc but also some impurities like arsenic, antimony and bismuth. With the development of Kosaka's floatation technology, five kinds of concentrates (copper, zinc, lead, pyrite and barite) have been separated from the "Black Ore" but the separation was not complete and each concentrate contained some unfavorable impuritie. In 1980s the highly appreciated yen and the drop of the metals priees forced many domestic mines to close their operations. Since then Kosaka Smelter has changed its way of operation to a custom smelter. Now more than 95% of copper concentrates are imported to take advantage of this technology of "Black Ore" treatment. It mainly treats the raw materials that contain high gold and silver like the "Black Ore". Recently, Kosaka has been working on the recycling of the metals from the printed circuit board scraps and sludge which contain some precious metals. The volume of the recycled metal is continuously increasing.

Jan 1, 2003

By Guiming Yang, Xiaoxian Huang, Zhiyun Ji, Min Gan, Lishun Yuan, Xiaohui Fan, Zhiyuan Yu

"The roasting characteristics of hematite pellets containing MgO were studied where magnesia powder, serpentine and magnesite were used as magnesium-additives respectively. The mechanical strength of both preheated and roasted pellets decreased when MgO content increased, which implied the addition of MgO had an adverse effect on pellet consolidation. By adding flux containing CaO, the mechanical strength of both preheated and roasted pellets were improved. The addition of calcium flux facilitated the formation of calcium ferrite and provided a certain amount of liquid phase, resulting in faster diffusion ofMg2+ and Fe3+. The result showed that diffusing speed of Mg2+ was enhanced by 1.48 times, and rate constant of Fe203 crystalline growth was enhanced by 62% when basicity was around 0.4. Improvement of mineralization degree and recrystallization of Fe203 assisted in consolidation of hematite pellets containing MgO.IntroductionOxidized pellets are ideal iron-bearing burdens in blast furnace. At present, magnetite is the main raw material for oxidized pellet production in China. However, as the rapid development of iron and steel industry, resources of magnetite have been depleted and cannot satisfy the requirement of pellet production. Using hematite concentrates to produce oxidized pellets has become a trend [1, 2]. Many pellet enterprises abroad nowadays have adopted high proportions of hematite concentrates when producing oxidized pellets, e.g. the percentage is 100% in a lot of Brazilian factories [3, 4]. But high proportion of hematite concentrates will lead to low mechanical strength and high reduction swelling index of pellets. Some studies show that Mg-bearing pellets have excellent metallurgical properties, and the reduction swelling phenomenon can be solved by adding fluxes containing MgO [5, 7]. However, there are problems such as low pellet strength and bad roasting characteristics for MgO-bearing pellets, which remains an obstacle in pellet industry. Hence, it's vital to undertake the study on strengthening measures for indurations of Mg-bearing hematite pellets."

Jan 1, 2013

By Ralph H. Nafziger

The feasibility of smelting a Ni-Co-Cr-bearing laterite ore from southern Oregon was evaluated by the Bureau of Mines. The objective was to prepare a master alloy for subsequent stainless steel production. A mixture of the ore with suitable reductants and fluxes was smelted in a 50-lb-capacity single-phase ac electric furnace under sub- merged arc conditions. The smelting tests produced a metal in which most of the nickel was concentrated. High-chromium recoveries required an excess of carbon. The resulting metal alloys contain sufficient nickel for some stainless steels. Ferrochromium additions would be required to attain suitable chromium levels. This research was conducted under the Oregon Metals Initiative in cooperation with Walter B. Freeman.

Jan 1, 1993

By Y. Maeda

Kosaka Smelter is a copper smelter located at the nothern part of Japan? and has been treating. complex sulfide concentrates using flash smelting technology for a long time. The flash smelting technology has an advantage in the point of controllability of matte grade and heat balance in the reaction shaft. But the disadvantage of this process, is that the dust generation ratio is high compared with other smelting process such as injection smelting technology. This reason why is that the flash smelting process is the oxidation process for the fine sulfide concentrates applying flash reaction in the oxygen enriched stream In addition of this disadvantage, the sulfide concentrates contains much volatile impurities is resulted the dust; eneration ratio more. This paper outlines the recent improvement of the flash reaction in the furnace and the behavior of impurities in Kosaka Smelter.

Jan 1, 1998

By V. M. Paretsky

The basic work conducted by Prof. A.Yazawa has demonstrated that in order to ensure single- stage white metal production by autogenous smelting of copper sulfide raw materials, it is most favorable to use highly basic slags, in particular oxide systems CaO-FeO-Fe2O3-SiO2. The special studies have been conducted in the Gintsvetrnet Institute to investigate the composition and structure of slags produced on a semi-commercial scale when testing the KFP and FBP processes for white metal smelting. as well as the slag obtained in a full-scale KFP furnace at the Almalyk copper smelter. The investigations conducted have demonstrated why production of high-grade matte or white metal is associated with lower loss of copper in slag in a series: silicate slag I silicate-calcium slag I ferrite-calcium slag.

Jan 1, 2003

By C. Lupi

"The energy consumption of copper production by electrowinning, generally represents more than 1/4 of the total energy requirement in hydrometallurgical traditional process (roasting, leaching, purification and electrowinning). The considerable saving can be achieved just in this step that requires about 2.2 kWhlkg of the produced copper. To save energy the cell voltage, or more appropriately its anodic component, can be reduced: that is because the anodic voltage represents the main component of cell voltage and so it is largely responsible for the excessive energy consumption in copper sulphate electrowinning.In this work some ways are studied to lower the anodic voltage. First the cobalt ions were added to the sulphate solution in order to study the catalytic effect on oxygen discharge. Then lead alloys anodes (Pb-Ag, Pb-Sb-Ag and Pb-Ca) were used to promote a better oxygen evolution as a result of a different anodic surface. Their behaviour was compared with the PbSb traditional ones. Finally, as already pointed out by several authors for zinc electrowinning, ethylene glycol was employed as anodic depolariser in order to verify its effectiveness in the case of copper electrowinning. By combining all the above-mentioned ways, energy saving ranging from 20% to 27% is achieved.All the tests were carried out on a laboratory pilot-plant for long time to simulate the industrial conditions. The obtained copper deposits were observed by SEM to highlight their morphology."

Jan 1, 1997

By Shuqiang Guo, Dingsheng Tan, Weizhong Ding, Zunyu Hu

"The mixture of hydrochloric acid and magnesium chloride is a good lixiviant for leaching of laterite. The solution can enhance the leaching ability because of the proton activity deviated positively from ideal. Otherwise, the existence of magnesium chloride in the lixiviant affects the dissolution behavior of magnesia, which may be an advantage of the process with less hydrochloric acid consumption. An investigation of magnesia particle dissolved in strong hydrochloric acid solution has been conducted. Influences of concentration of the magnesium chloride and hydrochloric acid and temperature on magnesia dissolution were studied. The dissolution mechanism was also discussed in this paper.IntroductionThere has recently been much interest in the use of hydrochloric acid leaching processes for recovering metal from ores or secondary resources [l-41_ Compared with sulfuric acid, the use of hydrochloric acid as lixiviant offers significant advantages including faster leaching kinetics even at atmospheric conditions, higher leaching rate and greater solubility for most metal chlorides [5-61 .With the gradual decline of the nickel sulfide supply, the extraction of nickel from laterites has become increasingly attractive [7-s1. Nickel may be co=ercially recovered from laterites both by pyrometallurgical and hydrometallurgical processes. The drawbacks of pyrometallurgical processes include the requirement of high grade ores, substantial energy input and loss of cobalt bound within ores. The extraction of Ni from lower grade nickel laterites ores is suited by hydrometallurgical routes, which play an increasingly important role with depletion of higher grade deposits."

Jan 1, 2014

By Bora Derin

The partial pressure ratios of sulfur and oxygen for several copper flash smelting plants were derived using the Reddy-Blander (RB) model and predicted dissolved sulfur contents available in the literature. The sulfide capacities (Cs) of six different flash smelting plants (FeO-CuOo.5- CaO-MgO-FeOu-AlO15-SiO2) slags were calculated. The log (PO2/PS2) versus matte grades of various industrial processes was determined. The PO2/PS2 ratio increased with an increase of copper grade. The calculated partial pressure ratios for the copper flash smelting are in good agreement with those of the experimental data.

Jan 1, 2003

By J. -S. Park, H. -S. Jeon

This study has been carried out to develop a relatively simple hydrometallurgical process for recovering nickel as nickel sulfate from the spent nickel-cadmium battery residue in which cadmium was removed by vacuum distillation. This residue is composed of 36 % nickel, 20 % iron, and other metals such as cobalt. First, crushing and selective classification were performed to separate iron to produce a nickel-rich product (over 40 % nickel). This product was dissolved in sulfuric acid to obtain a nickel sulfate solution. During the dissolution, nitric acid and air were added to the system to enhance the iron oxidation reaction rate. The free acid remaining in the dissolved solution was neutralized by adding nickel carbonate. Iron was precipitated as iron hydroxide and removed from the solution. The nickel sulfate solution was then fed to a vacuum evaporator to concentrate the solution by evaporation of water and crystallized at around 45°C to obtain nickel sulfate hexahydrate. A recrystallization process could remove other impurities such as zinc and manganese.

Jan 1, 2000

By K. Walanabe

Kosaka Smelter & Refinery has a history of more than a century as a metallurgical department belonging to Kosaka mine. It has treated for a long time the "Black Ore" or the complicated concentrates dressed from it. The "Black Ore" is composed of black sulfides. It contains not only valuable metals such as gold, silver, copper, lead and zinc but also some impurities like arsenic, antimony and bismuth. With the development of Kosaka's floatation technology, five kinds of concentrates (copper, zinc, lead, pyrite and barite) have been separated from the "Black Ore" but the separation was not complete and each concentrate contained some unfavorable impurities. In 1980s the highly appreciated yen and the drop of the metals prices forced many domestic mines to close their operations. Since then Kosaka Smelter has changed its way of operation to a custom smelter. Now more than 95% of copper concentrates are imported to take advantage of this technology of "Black Ore" treatment. It mainly treats the raw materials that contain high gold and silver like the "Black Ore". Recently, Kosaka has been working on the recycling of the metals from the printed circuit board scraps and sludge which contain some precious metals. The volume of the recycled metal is continuously increasing.

Jan 1, 2003

By Minjun Tang, Jianfeng Zhou, Feng Chen, Linjiang Qing, Xiaolei Song, Yufeng Guo, Tao Jiang

"Reduction swellability index (Rsn and low temperature reduction disintegration index (RDI) of vanadium-titanium magnetite oxidized pellets are harmful to the processing of ironmaking, for example, causing serious gas permeability, decreased yield, higher coke ratio and more furnace dust. Thus, the improvements of RSI and RDI of vanadium-titanium magnetite oxidized pellets were investigated in this paper, including the pretreatment of raw material, additives of dolomite or boric acid, pellets treated in chloride solution and so on. The results showed that damp milling as pretreatment and boric acid added in pelletizing were conducive to the RSI which decreased 5% and 7% respectively, while they were not efficient enough in improving RDI. Dolomite was efficient in improving RSI, but had negative effect on RDI. There was no evidence to show that RSI and RDI would be improved when pellets were treated in chloride solution. Pursuing this further, the mechanism of those improvements were investigated.IntroductionIn the world, vanadium-titanium magnetite utilization is investigated around how to recover iron, titanium, vanadium, and divided into blast-furnace method and non-blast-furnace method according to respective characteristics. Blast furnace method [1, 2] can recover iron and vanadium effectively, but Ti02 cannot be recycled. Non-blast-furnace methods include rotary kiln-electric furnace method, pre-reduction electric furnace method, reduction- grinding method and sodium vanadium-rotary kiln-electric furnace method and so on. [3-7]Comparing to the Non-blast-furnace method, the method of blast furnace smelting has been put into industrial applications. And it has the following advantages: First of all, effective recycling iron and vanadium; Second, technical problems of high titanium slag in blast furnace smelting; Third, it has mature technology in blast furnace smelting."

Jan 1, 2013

By Raj P. Singh

Applications of cementation in the recovery of metal ions from process solutions have been known for a long time. Cementation reactions involve electrochemical precipitation of a noble metal from solutions of its salts on a more electropositive metal which, in tum, progressively dissolves. For example, addition of zinc metal powder in a solution containing zinc and cobalt ions would allow for the precipitation (separation) of cobalt according to the following chemical reaction. This paper pertains to the recovery of cobalt from cobalt process solutions via a cementation reaction on aluminum shavings (metal scraps from cans etc). Specifically, we report on the characterization of cobalt process solutions, a by-product obtained from cobalt chemicals, and the kinetics of cobalt, nickel and manganese cementation from process solutions on aluminum shavings.

Jan 1, 2000

By Y. Fukunaka, M. Niinae, E. Kusaka, T. Kuzuya, R. Ishii

"Samarium oxalattr particles was precipitated in oxalic acid aqueous solution from samarium-loaded D2EHPA solution emulsified with a conventional impeller. The calculated fractional precipitation of samarium oxalate was reasonably compared with the value determined by chemical analysis. Morphological variation of oxalate precipitate particles was then examined with H2C2O4 concentration in aqueous solution, Sm(III) and D2EHPA concentrations in organic phase. The needle-like precipitate was identified as Sm2(C2O4)3 10H2O by XRD. Precipitates obtained at higher H2C2O4· or Sm(III) concentration greatly decreased the length of major axis of precipitate, while those at higher D2EHPA concentration increased it. The oxalate was further precipitated under ultrasonic irradiation. However, the morphological variation caused by theses processing variables was not so evident under ultrasonic irradiation as in an impeller or shaking mixer.IntroductionThe materials processing of the rare earth elements must be reviewed from the scope of industrial ecology, since they have the potential applications of magnetic materials as well as secondary battery in developing programs of the electric vehicle. The technological trend to develop the electric vehicle may greatly influence the concept of materials processing, since the global· environmental problem must accommodate with the sustainable development for mankind. The recycle design must be a key issue in the materials science and engineering.Solvent extraction provides a unique separation technology -in this sense. Doyle (1)(2) reported the integrating solvent extraction with processing of advanced ceramic materials, whose chemical composition and microstructure must be precisely controlled. In her paper, the higher productivity inherent to the present process superior to hydrolyzing metal alkoxides was emphasized. Oxalic acid has been used as precipitant for rare earth purification process, since rare earth oxalate has a very small solubility in water and can be easily decomposed to oxide. It is thus suitable for precipitation stripping agent in cationic exchange type extracting system (i.e. D2EHPA, VA-10, PC-88A and so on)."

Jan 1, 2000

By A. D. Damodaran

Batch scale and continuous rotary kiln carbothermic metallisation of ilmenite followed by different down-stream treatments such as catalytic rusting, acidic chloride leaching, oxidation-leaching etc. has given rise to a high grade synthetic rutile (98% TiO2). Rotary reactor metallisation experiments had concurrently given important information with respect to mean residence time, dispersion number, hold-up and axial velocity profiles of the solids bed. A mathematical model based on law of additive reaction times has indicated that Boudouard reaction becomes faster than reduction reaction at higher conversions. A possible use of high grade synthetic rutile in paint industry and metallised ilmenite as welding electrode flux material are discussed.

Jan 1, 1992

By Yang Xianwan, Zhu Xiaoyun, Guo Zhongcheng, Zheng Yanping, Zhai Dacheng

"Corrosion resistance of RE-Ni-W-P-SiC composite coating and 3 l6L stainless steel in corrosion media of H2SO4, HCl, H3PO4 and FeC13 solutions at different concentrations by means of immersion methods and anodic polarization curves obtained by DHZ-1 electrochemical synthetic tester and HDV-7 transistor constant potentiometer. Immersion experiment results show that corrosion rate of RE-Ni-W-P-SiC composite coating as-deposited in HCl solutions increases with the rise of HCl concentrations, on the contrary, the corrosion rate of the composite coating after heat treatment decreases with increasing the HCl concentrations the corrosion rates of the coatings as-deposited and after heat treatment in H2SO4 and H3PO4 solutions respectively decrease with the rise.of H2SO4 and H3PO4 concentrations the corrosion rate of the deposit as-deposited in FeC13 solutions decreases with increasing FeC13 concentrations, while the rate of the composite coating after heat treatment increases .with the rise of FeC13 concentrations.In addition, the corrosion rate of 3 l 6L stainless steel in the corrosion media of H2SO4, HCl, H3PO4 and FeC13 solutions at different concentrations increases with rising of concentrations. Furthermore, the corrosion rate of 316L stainless steel in the corrosion media of H2SO4, HCl, H3PO4 and FeC13 solutions respectively is much greater than that of the RE-Ni-W-P-SiC composite coating as-deposited and after heat treatment in the same corrosion media.1. IntroductionAll the materials and their products, when processed, stored and used, it is inevitable that the corrosion, wear, fatigue and crack occur owing to the actions of surroundings. Those early failure and abrasion, through all kinds of departments and profession that corrosion consumes one percent of tens of the steel products of the whole world; and two or four percent of the GDP is lost because of the corrosion."

Jan 1, 2000

By Seksak Asavavisithchai, Natthida Jareankieathbovorn, Areeya Srichaiyaperk

"Recycling of ADC12 alloy scraps for fabrication of open-cell aluminium foams has been conducted via pressure infiltration method of replication process. The scrap, up to 50 wt.%, was melted with pure aluminium billet, followed by infiltration in a replicated mold of polyethylene foam structure. Compared with the pure aluminium foam, the compressive strength and hardness are higher for the foams with recycled scraps. The increase in foam mechanical properties is due to the presence of Si hard phase in Al matrix. The strength and hardness of the foams also increase with increasing contents of the scraps.IntroductionRecently, open-cell metallic foams have been brought to considerable attention of many industries due to their superior properties; such as large surface area, high specific strength, thermal conductivity, high service temperature and excellent anti-microbial activity, that cannot be found in conventional materials [1, 2]. Typically, open-cell foams are used in functional applications for which a requirement of high strength materials is not demanded. Good examples of such applications include heat exchangers, bone-replacement implants, interconnects, catalyst supports, and sound insulators.Among all types of open-cell metallic foams, aluminium (Al) is the most widely used base metal, due to low material cost, low density, low melting temperature and good corrosion resistance. To improve mechanical properties of Al foam, modification of foam microstructure with addition of alloy elements or ceramic particles is commonly carried out [3, 4]. ADC12 alloy is a typical die-casting Al alloy with high content of silicon (Si) close to the eutectic point in Al-Si binary phase diagram. The alloy is extensively used in the casting industry, due to high wear and corrosion resistance, low coefficient of thermal expansion and excellent castability [5]. The mechanical properties of Al-Si alloy are strongly dependent of Si content."

Jan 1, 2012

By Adriana de Aquino Soeiro da Silva, Joao Alves Sampaioa, Luiz Carlos Bertolino, Francisco Manoel Garrido, Marta Eloisa Medeiros

"Brazil has a large agricultural potential and its production success is related to the chemicaland physical soil characteristics. Therefore, the demand in the use of a great quantity offertilizers to compensate the low amount of nutrients in the soil includes about 40% of foodproduction costs. In order to develop economical alternatives to traditional fertilizers, rockswith potential use in agriculture will be studied. In this work the potassium rock, a greensandslate, will be chemically and structurally characterized for the development of a potassiumthermophosphate. This alternative fertilizer will be obtained based on a fusion of a ponderedmixture of potassium, magnesium and phosphate rocks to be applied in the Brazilianagriculture. Preliminary characterization results indicate that the greensand slate presents ahigh percentage of glauconite, quartz and micas.Keywords: Potassium thermophosphate, alternative fertilizers, greensand slate.IntroductionBrazil has a great agricultural potential and its production success is closely related to thesoil's chemical and physical characteristics. However, the country's soils present lownutrients content and high acidity due to weather conditions. Thus, the use of a high amountof fertilizers makes up for the soils' lack of nutrients and accounts for 40% of food productioncosts. Therefore, research on obtaining new alternative fertilizers is a constant worry due tothe increase on food demand [ 1].The lack of raw material for the preparation of NPK fertilizers in Brazil is a concern and theissue of potassium fertilizers a priority. Such a fact is because in 2008 only 608.000 tons ofKCl were produced, corresponding to just 10% of the Brazilian necessity. Thus, the use ofrocks as agricultural nutrients can contribute to reduce the need for industrial fertilizers.This way, the development of a new agricultural raw material originated from a rock thatalready exists in the country's soil is of great importance for the mineral and agriculturalsectors."

Jan 1, 2011