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By Alessandro Blasi, Massimo Morgana, Corradino Sposato, Pietro Garzone, Giuseppe Devincenzis

A comparison among (2-ethylhexyl)-mono (2-ethylhexyl) ester Phosphonic acid (P507), Secondary-octyl phenoxy acetic acid (CA-12) and Bis(2,4,4-trimethylpentyl) phosphinic acid (Cyanex272), in heavy rare earths separation via hydrometallurgical processes has been investigated. The separation coefficients, , were obtained and the extraction selectivity has been evaluated using a mixture of heavy rare earths from Samarium to Ytterbium. The experimental results indicated that P507 and Cyanex 272 display a greater affinity for heavier rare earths while CA12 proved to be more effective for the lighter rare earth metals.

Jan 1, 2014

By Chao Du, Xiaohui Ning, Hongmin Zhu, Qiuyu Wang, Shuqiang Jiao

"TiCxOl-x solid solutions were synthesized by sintering a mixture of titanium carbide and titanium monoxide at 1600 °C. The corresponding structures and morphologies of the TiCxOl-x solid solutions were characterized by XRD and SEM. A series of tests has been performed on the electrochemical dissolution behavior of TiCxOl-x solid solutions in NaCl-KCl molten salt. The influences of synthesis time and electrokinetic parameters on the anodic dissolution behavior were also investigated. The results showed that TiCxOl-x solid solutions can dissolve as Tin+ into alkali chloride melt. Titanium ion species dissolved from TiCxOl-x solid solutions changes between Ti2+ and Ti3+ depending on the applied potential. The tail gas on the anode was monitored by a mass spectrometer. It was found the synthesis time significantly affects the components of the anodic gas.IntroductionTitanium and titanium alloys have been desired greatly because of their many uses. The critical factor that restricts the range of uses for Ti is its high cost of extraction. The primary titanium metal, sponge titanium, is still produced industrially worldwide by a process invented by Dr. Kroll in the 1940s[1] •Since the early 1970s, the research focus of the titanium industry has been directed towards developing a continuous process to produce high purity titanium at low cost. [2-10] Of the many alternative methods that have previously been investigated, the electrolytic process has been considered a promising method for titanium metallurgy [4-10]. Recently, several electrolysis and related methods such as the PFC-Cambridge process[11-15], calciothermic reduction[16-18], USTB [19,20] and MER[21] process were extensively investigated.The USTB process is a new approach where the pure titanium can be directly obtained by the electrolysis with an anode of titanium oxycarbide in molten salts[19, 20]. The titanium oxycarbide was produced by carbothermal reduction of titanium dioxide under vacuum at a temperature"

Jan 1, 2011

By C. Pichler, A. Ressler, D. Gregurek, A. Spanring

In order to improve the refractory lining life at one of the RHI key customer test procedures were developed within a two years collaboration project. In the first year of cooperation detailed refractory corrosion work in the rotary kiln with Ca-ferritic slag was performed. The main results of the second year of cooperation, reported in this article, involve a detailed testing work with nickel matte and pre-selected refractory brands which was performed in TBRC. A first part of this work was a complete chemical and mineralogical characterization as well as FactSage calculations carried out on provided matte samples. According to these results testing in the TBRC was realized at different process temperatures with several magnesia-chromite bricks. Based on the mineralogical investigation a high chemothermal load caused by sulfidic matte resulted in a deep reaching infiltration of the brick microstructure and partly corrosion of main brick components.

Jan 1, 2015

An iridium oxide coated titanium electrode was tested as anode in copper electrowinning. Initial results confmed that the DSA-type anode was significantly more active for oxygen evolution than traditional lead anodes. However, during longer runs, the anode potential was observed to increase linearly at a rate of 220 mV/year. Scanning elecuon microscopy (SEM) and energy dispersive spectroscopy (EDS) showed that the anode passivation could be attributed to elecuochemical dissolution of the coating. The effect on the anode potential of organic additives (glue and thiourea) and lead in solution was also examined. A preliminary economic evaluation of the anodes is given.

Jan 1, 1992

By Timothy W. Ellis

"This paper presents the basic theory of operation, physical chemistry and phase equilibria which allow the development of liquid-liquid extraction circuits based on metallic solvents. The incorporation of reduction and reduction/diffusion processes into the process scheme is discussed and a detailed description of several liquid-liquid extraction schemes are developed. A synopsis of experimental results obtained using this method to separate rare earth and other metal based materials will be given.IntroductionConcerns over the effects of waste materials in the environment has been one of the significant social hallmarks of the late 20th century. Essentially every industrialized country has had to incorporate the cost of waste material into the equation of production. Legislative initiatives have led to the passing of very tough laws, by historical standards, which govern the environmental impact of materials processing.Liquid-Liquid extraction is a very common unit operation normally using aqueous and/or organic based solvents. Early work at the Ames Laboratory focused on the use of this technique for the reprocessing of spent fuel from liquid metal breeder reactors by the use of metallic solvents. Recently, we have revisited this area as a means to recycle/reprocess several emerging rare earth based materials, although this method has a much wider range of application. The reinvestigation of this technology is particularly timely as hydrometallurgical based processes are coming under increasing scrutiny in the U.S.A. by the Environmental Protection Agency (EPA). Although technology currently exists to remove contaminants from aqueous based waste streams, often the application of such methods is expensive. With proper design and judicious selection of reagents liquid metal extraction can achieve a high recovery along with a benign waste stream.This process has several possible advantages over other technologies. First is the elimination of aqueous solvents. Therefore, problems associated with disposal or reprocessing of the aqueous carrier are eliminated. Second, with proper system design, very high separation coefficients can be obtained thus limiting the number of stages required. Third, metals are extracted from metals with a metallic product, thereby eliminating the need to re-reduce metal for oxides or other compounds which are the common output for aqueous based extraction procedures."

Jan 1, 1996

By C. Isaac Garcia, Sihai Jiao, Anthony J. DeArdo

"A practical model based on the Hill analysis has been developed to calculate the Lankford value of interstitial free (IF) steels and its distribution in different rolling directions, by considering only a few selected texture components. The Texture Intensity Ratio (TIR), i.e. (111 ) /(100), was used in the model to describe texture. By using the new TIR parameter, the texture-based prediction models can be used more easily to predict the Lankford value in a rather straightforward way.IntroductionThe deep drawing capacity of sheet steels is generally indicated by the Lankford value, which is mainly determined by the texture in steels1. Traditionally, various models derived from the Taylor model are employed to calculate the Lankford value from the texture2-4. In such models, the plastic deformation of steel is assumed to be the result of the slip of dislocations in certain slip systems, i.e., by either pencil glide or restraint glide. The slip direction is the <111> direction. In the case of pencil glide, the slip is thought to be possible in all crystal planes with the <111> crystal direction. Assuming the material is elongated in the X1-direction by d n and compressed in the X2 and x3-direction by qd n and (l-q)d n, respectively, corresponding to a deformation tensor"

Jan 1, 2001

By Xuefeng She, Qingguo Xue, Jingsong Wang, Guang Wang

Iron nugget could be got at high temperature using carbon composite pellet, which were made by the mixture of ludwigite and reducing agent. In order to reduce sulfur content in the nugget, effects of additives on the desulfurization was investigated. The sulfur content could be dramatically reduced if the CaO was introduced into the pellet and the sulfur content was as low as 0.046wt.% when the addition amount of CaO was 5wt.%. However, the melting separation of pellet became increasingly difficult and the yield of iron decreased when CaO content in the pellet gradually increased. Na2CO3 could also reduce the sulfur content in the iron nugget and made the iron and slag separate difficultly as well. When 6wt.% Na2CO3 was added into the pellet, the pellet was too difficult to melt separation and the sulfur content in the nugget was 0.084wt.%, which didn’t meet the need of steel making.

Jan 1, 2015

By A. Bilodeau

A new hydrometallurgical process for the production of refined gold and the recovery of palladium and platinum from silver anode slimes has recently been developed and installed at the, CCR Division of Noranda Inc. The process, which facilitates the production of gold of >99.99% purity in the face of increasing palladium receipts comprises; leaching silver anode slimes with hydrochloric acid and hydrogen peroxide at 95°C to solubilize gold, palladium, platinum and base metals while simultaneously rejecting silver as insoluble silver chloride; precipitating gold from the leach solu¬tion with sulphur dioxide gas in two stages to produce a first-stage high purity gold product and a second stage impure gold which is recycled to the leach; washing, melting and casting of the pure gold; precipitation of a palladium-platinum concentrate from the gold-free solution by reduction with sodium formate at pH 4 and 95°C; and neutralization of the palladium precipitation effluent to pH 10 with lime. The results of laboratory and pilot plant studies leading to the adop¬tion of this process are discussed, and data are presented for each of the unit operations. Details of the engineering of the commercial plant are given, and plant start-up experience is described.

Jan 1, 1987

By Gerardo H. Achurra

During the last years, the Caletones Smelter, like others copper smelters in the world, has evolved from the conventional, inefficient, pollutant and expensive technologies, to modern, environmentally friendly and efficient ones. For this reason&apos; as well as to improve its competitive position this Smelter shut down the reverberatory furnace, started up two big acid plants and has developed some pyrometallurgical technologies. The main facilities of the Caletones Smelting and Converting Process, in the present and the future, are the Teniente Converters, the reactors with a high operational availability that have reached concentrate top process capacities near to 2,400 tpd. These reactors operate in most of Chilean smelters as well as in other smelters in the world such as in Zambia, Peru and Mexico. Since 2000, the Caletones Smelting and Converting Process, has been adapted in two Teniente Converters, four Slag Cleaning Furnaces and four Pierce -Smith Converters. These facilities, together with the operation of two Fluidized Bed Dryers and two Oxygen Plants have allowed to reach concentrate smelting capacities and copper productions of 1,250 ktpy and 380 kfipy, respectively. Associated to EI Teniente Division Expansion Plan, Caletones Smelter, in the first stage, will increase its capacity to 1,440 ktpy in 2004. In the long term, Caletones has different options, such as the processing of 1,600 to 2,000 ktpy of concentrate, producing anodes, white metal or a mixture of them. These options are connected with CODELCO&apos;s Smelters & Refineries Strategic Plan, including Mejillones Project. The main challenges of Caletones Smelter are associated to the development and the consolidation of the Continuous and Environmental Friendly Processes, automation and control of different processes and to the improvement of its leadership between other Copper Smelters in the world.

Jan 1, 2003

By Gerardo H. Achurra

During the last years, the Caletones Smelter, like others copper smelters in the world, has evolved from the conventional, inefficient, pollutant and expensive technologies, to modern, environmental1y friendly and efficient ones. For this reason as wel1 as to improve its competitive position this Smelter shut down the reverberatory furnace, started up two big acid plants and has developed some pyrometal1urgical technologies. The main facilities of the Caletones Smelting and Converting Process, in the present and the future, are the Teniente Converters, the reactors with a high operational availability that have reached concentrate top process capacities near to 2,400 tpd. These reactors operate in most of Chilean smelters as well as in other smelters in the world such as in Zambia, Peru and Mexico. Since 2000, the Caletones Smelting and Converting Process, has been adapted in two Teniente Converters, four Slag Cleaning Furnaces and four Pierce Smith Converters. These facilities, together with the operation of two Fluidized Bed Dryers and two Oxygen Plants have allowed to reach concentrate smelting capacities and copper productions of 1,250 ktpy and 380 kftpy, respectively. Associated to El Teniente Division Expansion Plan, Caletones Smelter, in the first stage, will increase its capacity to 1,440 ktpy in 2004. In the long term, Caletones has different options, such as the processing of 1,600 to 2,000 ktpy of concentrate, producing anodes, white metal or a mixture of them. These options are connected with CODELCO&apos;s Smelters & Refineries Strategic Plan, including Mejillones Project. The main challenges of Caletones Smelter are associated to the development and the consolidation of the Continuous and Environmental Friendly Processes, automation and control of different processes and to the improvement of its leadership between other Copper Smelters in the world.

Jan 1, 2003

By Vincent Canaguier

Methane is increasingly considered as a promising reductant for metal oxides, including chromite. To assess the possibilities of such reduction route, the gas-solid reactions between Ar–CH4–H2 gas mixtures and synthetic chromites are studied between 950 and 1050 °C. The influence of Mg and Al additions on the reduction-caburization of (Fe,Mg)(Cr,Al)2O4 solid solution is investigated thermodynamically, structurally and kinetically. The product phases are examined by x-ray diffraction (XRD), scanning electron microscopy (SEM), and electron probe microanalysis (EPMA). The reaction rate is derived from real-time exhaust gas measurements and post-reaction product analyses such as oxygen analysis. Kinetic models are proposed based on the product phase morphologies and confronted with the empirical data.

By Guo Xueyi

The morphological characteristics of the nickel particles electrodeposited from chloride dominant aqueous solution was investigated. The effects of the electrolyte constituents, the parameters for the electro-deposition on the morphology of the nickel particles were addressed. It is evidenced that not only the particle size but also the morphology of the deposited nickel particles strongly depend on the electrolyte constituents and technical operation conditions. The electro-crystallization mechanism of the metallic nickel particles deposited at high current density was elucidated. The ultra-fine nickel particles with flake, nodular or dendrite shape may be produced by controlling the duration for electro-deposition.

Jan 1, 2003

By Anja Pfennig, Axel Kranzmann, Phillip Zastrow

"Properties of pipe steels for CCS technology require resistance against the geothermal corrosive environment (heat, pressure, salinity of the aquifer, CO2-partial pressure). To predict the reliability of two different injection pipe steels with 13% chromium and 0.46% carbon (1.4034, X46Cr13) as well as 0.20% carbon (1.4021, X20Cr13) steel coupons were heat treated by comparable routines prior to long term corrosion experiment (60°C, 100 bar, artificial brine close to a CCS-site in the Northern German Basin, Germany). In general higher carbon content exhibits better corrosion resistance with respect to corrosion rate, amount of pits and maximum intrusion depth in the case of local corrosion. At 100 bar hardened steels with martensitic microstructure have the lowest corrosion rates with an average of 0.003 mm/a after 2000 h exposure time. At ambient pressure normalized steels show the lowest corrosion rates, indicating that the corrosion is driven by grain boundaries.IntroductionEngineering a geological on-shore saline aquifer CCS-site (CCS Carbon Capture and Storage [1-3]) corrosion of injection pipe steels may become an issue when emission gasses, e.g. from combustion processes of power plants, are compressed into deep geological layers [4-8]. Typically 42CrMo4 (1.7225, AISI 4140) is used for casing, and for injection pipe the steel X46Cr13 (1.4034, AISI 420 C) or X20Cr13 (1.4021, AISI 420 J) is used. Saline formations are the most favorable storage sites in Germany [9], because of their large potential storage volume and their common occurrence. Leakage of CO2 back into the atmosphere may be a problem in saline aquifer storage, especially around the water level within the borehole. Carbon dioxide corrosion may cause failure of pipelines and wells as known from the oil and gas industry [4,6,10,11, 12].From thermal energy production it is known, that the CO2-corrosion is sensitively dependent on alloy composition, contamination of alloy and media, environmental conditions like temperature, CO2 partial pressure, flow conditions and protective corrosion scales [6-8,13- 20]. Considering different environments, aquifer waters and pressures, the analyzed temperature regime between 40 °C to 60 °C is a critical temperature region well known for corrosion processes as shown by Pfennig et al. [21-23] and various other authors [10,24-28] (figure 1). Here a maximum around 4.7 mm/year was found for the pit intrusion depth of 13% Cr steel X46Cr13. Still this may be predicted by the rather conservative Norsok-Model used in the oil and gas industry to calculate surface corrosion rates of carbon steels [29]."

Jan 1, 2014

By Kumar Ganesan

Elevated mercury levels are expected in aged gold mine tailings due to residual mercury from the amalgamation process, The fate of mercury in tailings is not well understood, Its potential health risk depends mainly on the degree to which mercury is mobile in soil. Mercury is re-moved from soil by evaporation, plant uptake, microbial activities, leaching, and other physico-chemical processes. In this research the amount of mercury lost by evaporation was evaluated. Several aged gold mine tailings in Montana were sampled for total mercury and its flux into the atmosphere. Mercury levels in tailings were higher than the general background levels in most sites. The mercury levels in some cases were as high as 10,000 ug/g. The field measurements using flux chambers indicated a wide range of mercury flux from aged gold mine tailings. The mercury flux ranged from 0-11,000 ng/m2/hr. The mercury loss by evaporation helps rid the soil of mercury but the mercury vapor then will participate in the atmospheric mercury cycle, The low solubility of elemental mercury in water helps to minimize mercury leaching from tailings, however, conversion of elemental mercury to more soluble forms by bio-geo-chemical processes can enhance its mobility posing increased health risk.

Jan 1, 2003

By Kazuki Morita

A new route to produce solar grade silicon (SOG-Si 6N) from metallurgical grade (MG-Si 98%) has been developed in Japan, which may satisfy the increasing demand for solar cells in the near future. Since some elements such as P and B have very large segregation coefficients, solidification refining is not effective for their removal and costly processes, such as electron beam vacuum melting and oxidation plasma refining, are required. According to our previous results which showed the effectiveness of leaching procedure with Ca addition for Fe and Ti removal, possibility of P and B removal by acid leaching was focused expecting that their affinities for Ca in molten silicon might be considerable. Hence, the effects of Ca addition on the thennodynamic properties of P and B in molten silicon alloys have been investigated for overall control and optimization of the SOG-Si production process in the present study. The interaction parameters between Ca and P, and Ca and B were determined by chemical equilibration techniques at 1723 K. Although the interaction parameter between Ca and B was slightly negative, that between Ca and P showed a large negative value. Also, the results for the leaching test with various amount of Ca addition revealed that the removal fractions of both elements, especially P, drastically increased with increase in the Ca content, which showed very good agreement with the prediction from the interaction parameters derived in the present work. The present results suggest that the preliminary leaching procedure can reduce the processing time and energy for SOG-Si refining. Keywords: Silicon, Solar Cell, Refining, Acid Leaching, Thennodynamics. Interaction, Phosphorus, Boron, Calcium

Jan 1, 2003

By E. T. de Groot, D. L. Verhelst

With the successful start-up of Cominco's new KIVCET smelter, the final key component is now in place for Trail Operations to operate efficiently as a modern integrated zinc-lead facility. Unique metallurgical, operational, planning and management issues apply to this operation. Along with presenting the current flowsheet for Trail Operations, this paper discusses issues such as the impact of recycles, operational re-stabilization following significant process changes, plant operation with just-in-time inventories, real-time process optimization, and management philosophy.

Jan 1, 2000

By Hiroyuki Sano

A closed recycling process for the low-grade scrap of Al-based composite materials was developed. In this process flux treatment with water-soluble halide is a key technique. In the present work, flux treatment conditions were discussed from the viewpoint of the separation and the recovery of the base material, reinforcement and flux. Optimum separation condition was obtained for the NaCl-KCI-KF flux treatment. The recovered aluminum alloy can be recycled for various usages. The recovered SiC particles cannot be reused as reinforcement because of the coexistence of the contamination, therefore it is necessary to eliminate these contaminates or to find another use. The recovered flux is reusable with supplemental addition of fluoride.

Jan 1, 2003

By S. B. Bortnikova

This paper presents the results of an investigation of the gold-silver oxidized ores at the Salair mine. West Siberia. High losses of precious metals during primary ore processing are the result of outdated technology that is not suited to treat the present ore compositions. The main mineralogical forms of gold and silver and their confinement to different grain size fractions have been determined. About 50% of gold in the slime fraction and 60% of the silver in the form of acanthite that are scattered from the secondary minerals are lost to the waste. The results of these investigations have provided the basis for the recommendation of a new technological process to upgrade the current practice of the gold extraction plant and for methods to reprocess the concentrates.

Jan 1, 1995

By M. Kobashi, T. Choh, N. Kanetake

"A new processing route, which enables the cost-effective and energy- saving fabrication of metal matrix composites, have been proposed. The pressureless infiltration of the reactive powder blend with molten aluminum was investigated in this work. The molten aluminum infiltrated into the [Ti + C] powder blend spontaneously, whereas the spontaneous infiltration into the TIC powder phase did not occur under the same experimental condition. The processing time was shortened and· the processing temperature was .lowered by adding the aluminum powder in the [Ti + C] powder. The differential thermal analysis revealed that the aluminum powder in the powder blend melted at 933K and then ignited the reaction between titanium and ·carbon. However there was an .optimum additional amount of aluminum in the powder blend. The TiC formed in situ had three-dimensionally continuous morphologyIntroductionThe squeeze casting process has been used as one of the processing routes for aluminum matrix composites. [1, 2]. Non-reactive metal-ceramic systems have been, generally, used in this technique in order to prevent the degradation of the ceramic phase. Materials obtained by this process basically consist of a continuous metal matrix and discontinuously dispersed ceramic particles. Reactive systems have begun to be introduced into the infiltration process· recently [3A]. Since the ceramics are synthesized in-situ, this process can provide a continuous ceramic matrix [5]. This is one of the outstanding features of this technique in that a bulk ceramic-can be synthesized at relatively lower temperatures in a short time. Another advantage is that the highly reactive combination of a ceramic with a molten metal is in many cases wettable [6], which enables a spontaneous infiltration."

Jan 1, 2000

By P. Peczak

A Monte Carlo simulation technique has been used to study dynamic recrystallization in polycrystals. A continuum microstructure of the polycrystal is modeled employing a discrete lattice. The response of the material to hot deformation is simulated by adding stored energy and recrystallization nuclei continuously with time. The experimentally observed nonuniform character of deformation substructures is modeled by employing a phenomenological expression for inhomogeneous distribution of the stored energy. All simulations were performed on HP-Apollo 9000 Series 700 workstations. A program written in FORTRAN with use of PHIGS graphics library calls was used to interactively monitor the current state of the matrix and all relevant parameters: deformation stress, average grain size and effective nucleation rate. Visual analysis of the simulated microstructure allows a better understanding of the data developed by averaging over a number of very long Monte Carlo runs. Since the essential features of dynamic recrystallization are accurately reproduced by the model, it is used to discuss the role of the controlling mechanisms of the dynamic recrystallization in real polycrystal.

Jan 1, 1993