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By Jing Zhan

The fibrous precursor can be obtained by coordination precipitation process, using oxalate, cobalt chloride and ammonia. The composition and morphology of fibrous precursor were characterized by XRD, IR, DTA/TGA and SEM analysis. The results show that XRD pattern and composition of the precursor with fibrous morphology precipitated at pH=9.0 were different from that of ß-CoC2O4?2H2O precipitated at pH=1.0. The mechanism on the thermal decomposition of fibrous precursor was addressed. The influences of various conditions in pyrolysis, including the temperature, time, atmosphere, and the morphology of the precursor, on the morphology, average size and specific surface area of the Co powders were investigated in detailed. At last, the final product, fibrous cobalt powders with diameter about 0.3~0.5µm in size and 40~60 in aspect ratio, were produced by thermal decomposition at 400~500? in the weak reducing atmosphere. The structure of pores in cobalt powders was capillary tube with open ports and the majority was mesoporous.

Jan 1, 2009

By L. A. Harris

In the present study the open gradient magnetic separation' (OGMS) method has been used to beneficiate the -30 + 100 mesh fraction of two high volatile bituminous coals. The evaluation of the effectiveness of the magnetic separation for cleaning these coals is the subject of this paper. Coal petrography in combination with scanning electron microscopy (SEM) and x-ray diffractometry (XRD) were used to characterize the magnetically separated coal fractions. These analyses revealed that the majority of the pyrite and non-pyrite minerals were concentrated in the positive magnetic susceptibility fractions. The bulk of the starting samples (-80 weight percent) were located in the negative magnetic susceptibility fractions and showed significant reductions in pyrite and non-pyritic minerals. The magnetic separation appears to effectively split the samples into relatively clean coal and refuse.

Jan 1, 1981

By Chris Doyle

From 1997-2000. PT INCO undertook the Fourth Line Expansion Project (FLEX) to increase annual production rates from 90-100 to 150 Mlbs Ni/year (68,000 MT Ni/yr). In 2003, PT INCO nickel production underwent a major sustainable step jump that finally exceeded the targeted rate. This paper presents the changes that led to this achievement. The focus of mining changed. Improving Ni grade was important but only if electric furnace feed met target chemistry so that on-specification slag could be produced. The intensity of diamond core drilling for exploration was dramatically upgraded, mine planning strategy was totally re- vamped and an ore chemistry quality assurance team was formed. In the processing plant, measurement systems were upgraded for better control. Teamwork between sections vastly improved. The final step jump in production occurred when the fifth hydro-electric power generator was added to the furnace grid to allow the power-starved furnaces to cruise in operation at 70+ MW. Keywords: Free cash flow, Ore Chemistry, Measure, Control, Improve

Jan 1, 2004

By Jong-Ren Tarng, Gin-Hwa Chen, Wen-ku Chang, Ke-Ming Lin, Yuan-Haun Lee

"The majority of early studies used X-ray diffraction, but this requires a model to interpret the diffraction processes. A turbostratic model has been applied by Warren, Franklin and Bacon to a wide range of materials including both soft and hard carbons. Maire and Mering applied the same methods to the interpretation of the (001) lines of a series of graphitic carbons. In our case, graphitic carbons undergone high temperature and high pressure graphitization processes have been evaluated by the same methods. It were found that most technological XRD data were obtained by a Rietveld method with the least-squares refinements could be in the simplest way since the full correction technique is very laborious. The behavior of carbon materials as it proceeds through the graphitization process is characterized by changes in the measured interlayer spacings (d) a~ a function of temperature. A series of graphitic carbons including the transformation of diamond to graphite through the process under high temperature and high pressure have been evaluated. A simple calibration equation has been established. IntroductionRecently, in battery industry, carbon materials are used as cathode in lithium ion batteries. However, graphitization of those carbon materials is concerned as if lithium ion intercalated into those carbon cathode. Both high-graphitization and low-graphitization carbon materials are suitable for this kind of application.As for graphitization, the starling materials from which carbons may be prepared vary extensively from pure chemical compounds, to mixtures containing II wide range of molecular weights, such as pitches. So its graphitizing, perhaps the most notable feature of the process, is the very wide range of temperature over which the perfection increase, unlike the more common transformations of solid state materials which occur in a narrow temperature range. The variables involved in the conversion of the initial hydrocarbon to a carbon residue, which may vary widely in final perfection, are time, temperature, stress and impurity content"

Jan 1, 1996

By Dai Xi

In the present work, the viscosities of molten FenO-MgO-Si02 and FenO-MgO-CaO-Si02 semi-synthetic slags for nickel flash smelting were measured in the temperature range from 1473 to 1723K by a rotational viscometer. The ratio of Fe to Si02 was fixed at 1.2, calcium and magnesium oxide contents varied in the range from 2 to 8 mass% and 9 to 12 mass%, respectively. The results showed that silicate anions became smaller by increasing CaO content, which results in a decrease of the viscosity of the slag. In the case of MgO addition the viscosity behavior was complicated. At MgO content below 11 mass%, the viscosity increased with the increase of MgO at all temperatures tested. However, when the MgO content was above II mass%, the viscosity decreased slightly for FenO-MgO-CaO-Si02 system. At higher MgO contents, low-viscosity slags can be obtained by adding CaO. At a given composition, the viscosity decreased with increasing temperature. The higher the temperature, the more MgO can be added before saturation. The effect of Fe304 on the viscosity was quite significant. The viscosity of slag increased by 300mPa's at l573K when Fe304 content varied from 3 to 9 mass%. The viscosity values are presented as the functions of temperature and composition. A comparison between FenO-MgO-Si02 and FenO-MgO-CaO-Si02 systems is given in this study.

Jan 1, 2003

By Tae-Hyun Kim, Kang-In Rhee, Jeong-Soo Sohn

The synthesis of Mn-Zn ferrite powder from spent zinc-carbon batteries was investigated using a series of physical treatment, sulfuric acid leaching and coprecipitation. Physical separation methods such as crushing, magnetic separation and sieving were applied to generate a non-magnetic material of 8- mesh undersize for subsequent leaching process. The 8-mesh undersize of the spent zinc-carbon batteries was assayed 23.9% Mn, 14.9% Zn, and 4% Fe. Metal extractions obtained in sulfuric acid leaching at the solid/liquid ratio of 1:10, 2 M H2SO4, and 60? with 6 vol.% H2O2 addition were 97.9% Mn, 98.0% Zn and 55.2% Fe. The leach liquor was finally adjusted to the Mn:Zn:Fe mole ratio of 1:1:4 suitable for producing MnZnFe4O8 ferrite powder by the addition of Mn, Zn and Fe sulfates followed by pH control. A co-precipitation test for Mn-Zn ferrite powder was performed at 80?, O2 gas flowing at 1.3 L/min. As a result of co-precipitation, Mn-Zn ferrite nanoparticles in 20 nm size with spinel structure were successfully synthesized. The saturation magnetizations of Mn-Zn ferrite powder (Mn1-xZnxFe2O4) were determined to be 39-91 emu/g with various zinc contents (X=0.2-0.8).

Jan 1, 2008

By T. A. Venugopalan

The 'Hall-Heroult' Process of reduction of Alumina to Aluminium has remainded basically the same for over 100 years, but the technology has been undergoing drastic changes with respect to selection of materials for Cathode and Anode, and also energy consumption. The latest generation pots have a working life of about 1800-2000 days normally. After the failure of the pots, the Cathode Lining is dug out and disposed of on land. Since the lining contains objectional materials causing pollution, various processes have been tried for re-processing of this waste. However, most of the processes have been unsuccessful from the techno-economic point of view. At Hindalco a new chemical process for converting the fluorine values of the dug out material to Cryolite was developed in 1988 and a" one ton per day Cryolite production plant has been operating since 1989. This process is especially applicable where the integrated Alumina and Smelter Plants exist side by side. The experience in operating this Plant is discussed in detail in the paper.

Jan 1, 1992

By Hang Goo Kim

A computer simulation has been carried out to predict the distribution behavior of minor elements such as Pb. Zn, Bi, Sb and As in recently proposed copper smelting and converting processes with submerged oxygen injection in which tonnage oxygen is used with a shielding gas. In this study the technique of stepwise equilibrium modeling was employed and some of the thermodynamic data were updated or reassessed. The volatilization and slagging of undesirable elements were investigated in copper smelting (steady-state) system, copper matte converting (batch) system, and the combined (smelting + converting) system at extremly high oxygen-enrichment levels. The predicted minor-element behavior under high oxygen- enrichment was compared with that in the Noranda process (normally 42% oxygen-enrichment in smelting and 24% in converting) and the reverberatory process using air. The effects of various operating parameters such as temperature, the final matte grade in smelting, the initial matte grade in converting and the O/Fe ratio in slag on the behavior of minor elements are discussed.

Jan 1, 1991

By Bora Derin

This work deals with the recovery of valuable metals from the ancient copper smelting slags located in Küre-Turkey. In this process, copper and cobalt were recovered in metallic form and/or as their compounds, whereas iron was recovered as magnetic oxide or pigment. Abrasive grit material was produced using reduced final slag. The process stages involved carbothermal reduction in a DC arc furnace, granulation, leaching, chemical precipitation, selective sulfidizing roasting and product preparations. In this paper, the process stages were described as theoretically and experimentally whereas slag and products were characterized in detail.

Jan 1, 2003

By Liyuan Chai, Qin Liu, Bing Peng, Jia Wang, Qiang Zhang

"Electrolytic Manganese Residue (EMR) was used as the main material to prepare cementing material activator for the utilization of the residue from electrolytic manganese dioxide (EMD) or electrolytic metallic manganese (EMM) production. The effects of chemical activation, thermal activation and mechanical activation on retarding activity and excitation activity of EMR were investigated according to the setting time and activity index of EMR-slag cementing material. The results showed that the EMR exhibited good activating performance after being ball-milled for 18 min and then treated for 1-2 hours at temperature range of 350-450 ?. The optimal properties of cementing material activator were achieved at the weight percent ratio 30 : 3 : 5 of EMR/Ca(OH)2/cement clinker.IntroductionMany hazardous industrial solid wastes such as blast furnace slag, fly ash, steelmaking slag, chromic slag and electrolytic manganese residue [1] are generated n China and their amounts increases every year. The accumulation of the solid wastes during past years is very huge and they could be hardly recycled effectively as a sustainable resource. 2.35 billion tons of industrial solid wastes have been produced up to now [2]. It is estimated that they would exceed 3.3 billion tons by the end of 2015 [3]. On the other hand, the quick development of Chinese infrastructural construction needs more cementing materials. The production of traditional building materials consumes lots of natural resource such as clay and limestone and discharges at least 1 ton CO2 and other pollutants per ton clinker [4]. Therefore, it is necessary to develop new types of cementing materials instead of clinker [5,6]."

Jan 1, 2012

By Jean-François Boulanger

The production of rare earth elements from ore usually consists of three steps; the separation of a concentrate of REE bearing minerals; the cracking of the REE minerals to liberate the REE into an aqueous solution and separation of REE into individual elements. This paper describes the results of laboratory tests conducted on a carbonate-rich REE ore containing bastnaesite and monazite. The tests cover the whole processing sequence of beneficiation, preparation of the REE solution using a caustic leach followed by acid leach to break monazite and bastnaesite and liberate REE into an aqueous solution and the partial separation of the REE using solvent extraction. Details on the product quality and process performances (recovery and impurities removal) are given for each studied step. The paper also discusses the economic advantage of separating the REE rather than producing a mixed REO product to be sold to a refinery for REE separation. A mini-pilot plant version of the process is currently planned.

By I. Peerawattuk

Growing demand for Li-based battery technologies is leading to an unprecedented growth in the lithium industry. Although innovation in battery technologies has pushed lithium into the spotlight, lithium was not always known for its application in batteries. The primary use of lithium—prior to the introduction of commercial lithium-ion batteries in the early 2000s—was in the ceramics, glass, grease, and the medical industry. Before being converted into usable forms, lithium products must be upgraded from the raw material. Processes for recovering lithium may involve: thermal treatment, water leaching, solar evaporation, ion exchange, carbonation, and electrodialysis. Presented, is a historical review of lithium applications and the different techniques of converting lithium-rich minerals and brines into usable products with additional discussion on future lithium extraction processes.

By Bingyi Bai, Lifeng Yang, Yanling Guo, Jieyu Zhang, Guoding Gao

In terms of special resources with iron, niobium and rare earth coexisting in Baiyuneboite, the new smelting technology of ferrocolumbite was studied. Reduction experients for the Baiyuneboite and explores ore phase change of Baiyuneboite in the process of reduction was conducted with graphitic carbon as the main reducer and a temperature below 1000 ℃. Moreover, it studies the influence of reducer, roasting temperature and grind fineness on the reduction as well as focuses on the evolution course of iron phase. Through the analysis on in-situ XRD of the raw ore and carbon addition ore, it also develops microstructure change rules of Fe ore phase and ore phase of paragenetic elements for composite ore(Ca, Si, Nb, F) in the process of reduction roasting. In addition, the impacts of temperature on the reduction process are also discussed. With regard to minerals of different particle sizes, the thesis will explore their ore phase changes and microstructures after 10 hours’ reduction under 900 ℃.

Jan 1, 2015

By W. G. Davenport

Changes in copper extraction from 1960 till today are documented. The top ten changes have been: (a) replacement of reverberatory smelting by high intensity oxygen rich smelting (b) growth of the Outokumpu flash smelting to over 50% of the world's smelting capacity (c) successful development of single furnace coppermaking but only for low slag fall concentrates (d) replacement of the batch Peirce-Smith converter by continuous converting, but only in a few cases (e) increased SO2 capture throughout the industry, mainly-as sulfuric acid (f) development of low initiation temperature `big bight' Cs catalysts for treating the continuous high-SO2 strength gases from continuous smelting/converting (g) complete replacement of reverberatory anode scrap and cathode melting furnaces by the Asarco shaft furnace (h) adoption of stainless steel permanent cathodes and automated stripping technology for electrorefining and electrowinning (i) complete elimination of wire bar casting by continuous bar casting/rod rolling (j) development and adoption of extractants for turning weak impure leach solutions into strong pure electrolytes. It is postulated that the biggest possible change over the next 20 years would be complete replacement of smelting/converting by hydrometallurgical processing. However, this seems unlikely due to copper purity, precious metal recovery, and economic concerns. The increasing value of sulfuric acid to many copper companies gives chalcopyrite smelting/oxide-supergene leaching a nice synergy especially with the energy credits now coming from continuous smelters, and their acid plants.

Jan 1, 1999

By Jean-Christophe Gebelin, Mark Jolly, Samantha Jones

"The de-waxing process in investment casting is truly a black art which is carried out in a black hole - the autoclave. The process involves exposing wax, coated by a porous ceramic shell, to steam at a pressure of 10 bar and a temperature of about 180°C. The processes which then occur are truly multi-media and multi-physics. Steam condenses in the porous ceramic, wax melts and flows, the shells expand and sometimes crack. Why the shells crack is one of the most difficult questions asked in the industry.Modelling and validating the de-waxing process is not simple. The IRC at the University of Birmingham is attempting to model this process using Physica+ a code developed in the UK. This paper will present the latest results in this attempt to model one of the casting industries most intractable problems.IntroductionThe de-waxing process using an autoclave involves the following physical phenomena:· Flow of the steam in the autoclave;· Heat transfer from the steam to the wax, possibly through the shell;· Melting and flow of the wax.At the same time, other phenomena may occur, such as the flow of the steam through the shell, the condensation of the steam on the shell surface and on the wax pattern surface, the flow of wax the through the shell, etc ...This shows how complex the de-waxing process is from a physical point of view. The main defect that appears during this process is the cracking of the shell. Previous modelling work carried out by Snow [1] has shown that it is possible to predict the stress in the shell, making numerous assumptions. In this paper, the modelling to predict the state of stress in the shell that is currently in development at the University of Birmingham is presented together with the presentation ofthe physical phenomena to model and the assumptions used. The parameters that are needed in such models will also be discussed, and some experimental work undertaken at the moment presented."

Jan 1, 2001

By L. A. Harris

The formation of coke during coal liquefaction can eventually result in catastrophic failure of the conversion system. Coking typically proceeds by the formation of liquid crystals (mesophase) and the subsequent separation of these crystals from the plastic phase formed during heating of coal. The anisotropy of the mesophase makes it readily detectable in the optical microscope under polarized light. This study examines the solids formed during coal liquefaction processing by optical and electron microscopy. Observations on the relationships between the coke morphology, minerals and inert macerals are presented.

Jan 1, 1982

By Muhamad Firdaus

There is a growing interest in Magnetoelectric (ME) materials in view of both fundamental understanding and novel desirable applications. The application potential for multiferroic materials with the possibility of reversing the magnetization by applying an electric field (or vice versa) is quite promising especially in data storage application. The rare earth ortho-ferrites (REFeO3), such as NdFeO3, have been studied extensively in recent study in the context of discovery of magneto-electric (ME)/multiferroic nature materials. In this paper a potential high temperature recovery of rare earth elements in the form of REFeO3 from waste permanent magnets using direct oxidation in air was investigated. It was found that REFeO3 (NdFeO3) phase can be separated from the other oxide phases by thermal treatment of NdFeB magnet waste at 1100 °C in air atmosphere. The REFeO3 also found to have different physical characteristic (density) from the other layers and can be separated physically. This paper will include a proposed flowsheet to recover Nd as NdFeO3 through powder separation. The technique can be beneficial and favourable for RE recycling and recovery from waste permanent magnets.

By Evgueni Jak

Pyrometallurgy is an important sector of modern industrial society actively participating in solving current environmental, economic, materials scarcity and other challenges. Recent advances in analytical methods, experimental techniques, thermodynamic, phase equilibria and process modelling tools provide new opportunities to increase the productivity of pyrometallurgical reactors, the treatment of complex feeds and metal recoveries. Fundamental theoretical models can now be used to make a significant next step towards the development and implementation of computerised models describing real industrial processes—Virtual Reactors, and computer-aided smart-decision-making systems that may be called Pyro-GPS by analogy to GPS; these developments can facilitate knowledge-based improvement and optimisation strategies. The implementation of these improvements require ongoing collaboration between researchers, industry and government.

By Honggang Zhong, Xin Cao, Qijie Zhai, Hongmei Song, Congsen Wu, Cheng Zhang, Jingzheng Ye

"The influence of superheat on the solidification structure and ferrite/austenite phase transformation of a novel lean duplex stainless steel (DSS) was investigated on a setup, which designed to thermally simulate the continuous casting process. The results showed that the macrostructure of the samples all exhibited chill zone, columnar zone and equiaxed zone. The distance from chill zone to position of columnar to equiaxed transition (CET) moved from 51.0 mm to 39.8 mm with an decrease of superheat from 70 °C to 10 °C, and that the grains in the chill zone tended to be finer. In equiaxed zone, the fme and uniform grains were observed when superheat higher than 40 °C; while, coarse grains were found in samples poured at low superheat. Generally, the volume fraction of ferrite increased along the dendritic growth direction, and stabilized in equiaxed zone. The high superheat decreased the volume fraction of ferrite in equiaxed zone, while it had indistinctive influence on chill zone and columnar zone.IntroductionDuplex stainless steel with approximately equal volume of ferrite and austenite, offering an attractive combination of corrosion resistance and mechanical properties. [ l]. The production of DSS, worldwide application in structural engineering[2] and petrochemical industry[3], have increase by more than 100% in the latest decade[4]. But due to the sharp prices increase of nickel and chromium, lean duplex stainless steels which have lower contents of alloy elements were developed. They perform well in both mechanical and corrosion resistance[S, 6] and even have TRlP(Transformation Induced Plasticity) effect[?]. Nonetheless , the mechanical properties of DSS was affected greatly by the solidification structure, such as columnar to equiaxed transition (CET), grain size and phase content[8]. So, the solidification behavior of stainless steel was investigated widely"

Jan 1, 2014

By J. Y. Foley

Platinum-group elements (PGE) are preferentially associated with chromian spinels, including high-iron chromite, magnesian-chromian hercynite, and chromian magnetite in clinopyroxene-rich upper stratigraphic portions of the Tonsina ultramafic complex in southern Alaska. Ratios of Pt:Pt+Pd are proportional to chromium content in the associated chromian spinels. The maximum PGE content of geochemical rock samples from Dust Mountain is greater than 20.000 ppb (>0.6 oz/ton) with minor gold values. The maximum PGE content of tabled chromite concentrates is 3.430 ppb (0.1 oz/ton) at Dust Mountain. 1.029 ppb (0.03 oz/ton) at Sheep Hill, and 1,749 ppb (0.051 oz/ton) at Bernard Mountain. High-iron chromite at Dust Mountain yields tabled chromite concentrates with Cr:Fe ratios between 0.5 and 1.2. Lower PGE contents are found in more chromium-rich chromitites from Sheep Hill and Bernard Mountain that yield concentrates with Cr:Fe ratios between 1.0 and 2.8. Platinum-group minerals include amalgams. arsenides. PGE alloys, and sulfides. These minerals are between 3 and 40 microns in size and are concentrated along grain boundaries and fractures of metasomatically and hydrothermally altered chromian spinel grains.

Jan 1, 1987