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By Jianhua Xin, Min Chen, Jin Xu, Hui Li, Nan Wang, Ming Chen

The kinetics study of blast furnace dust (BFD) recycling with flash reduction process at high temperature has been carried out using a high temperature drop tube furnace in laboratory scale. A combination characterization methods of chemical titration and SEM-EDS were used to track the reduction kinetics. The experiments using CO and CO2 mixtures with range of CO/CO2 (1:0, 1:1) at different temperature (1623–1723 K) and at different reduction time (1560– 2340 ms) were conducted. It was found that the reduction degree increases with the increase of temperature and reduction time as well as CO concentration. The carbon contained in the original BFD has weak in fluence on the reduction potential in the form of gasification. The unreacted core model was adopted based on the observation of the cross section and the measurement of iron element content, the effective diffusion coef ficient and reaction rate constant were determined and the rate controlling step was also analyzed.

Mar 1, 2018

By H. A. F. de Souza, Dana S. Mills, P. E. Burgener

"ICP-MS has moved from a laboratory curiosity to a functional analytical tool. This paper discusses how ICP-MS has been used to solve difficult analytical problems encountered when analyzing various mine materials. Comparisons between analytical techniques applied to the analysis of gold and the platinum group metals illustrate the advantages and problems of ICPMS when. applied to trace levels of some metals iri the presence of ore grade metals. Interferences and matrix effects are compared to ICP, AA and Neutron Activation. The necessity to select chemical extractions which are compatible with ICP-MS are also discussed.The ICP-MS techniques explained in the examples on Au and precious group elements (PGE) have validity in analytical problems encountered in testing of trace metals in the presence of major elements found in mine materials. Exploration and environmental testing are other areas that require the same analytical approach to quantify trace levels in the presence of major interfering elements normally associated with mining environments."

Jan 1, 1999

By H. C. Roland Kammel

Stannous sulfate electrolytes are widely used nowadays in electrolytic tin production. Characteristic features of this electrolysis process are that dense cathode deposits can only be obtained by additions of organic additives and that so called ?black mud is formed on the anode surface which leads to an increase in cell-voltage. In order to prevent excessive cell-voltages or oxygen evolution the black mud has to be removed periodically. Studies in laboratory scale have been performed about the effect of different organic additives on electrolytic tin deposition and the formation of surface layers on pure and industrial tin anodes. Results reveal that organic addition agents are effective in reducing cathode roughening as well as extending the covering time of the anode ?by black muds.

Jan 1, 1985

By R. W. Harnmack

Hydrogen sulfide generated by the anaerobic respiration of sulfate-reducing bacteria was used to treat pH 2.2 water from the abandoned Rio Tinto copper mine in Nevada. The untreated water contained 550 mg/L Fe, 140 mg/L Al, 90 mg/L Cu, 80 mg/L Mn, 60 mg/L Zn, 4 mg/L Co, and 2 mg/L Ni. The bench-scale treatment system examined consisted of a bioreactor for H2S generation and three precipitator/clarifier units for metal sulfide precipitation and recovery. The treatment system reduced the concentrations of all metals except Mn to less than 0.1 mg/L. Manganese concentrations were reduced by 96 percent to 3.3 mg/L. A CUS/SO concentrate (33 pct Cu) and a ZnS/5° concentrate (28 pct Zn) were produced that may be suitable for metal recovery at existing smelters

Jan 1, 1994

By Richard D. Hagni

The United States is dependent upon foreign sources for more than 93% of its bauxite and alumina supply. Domestic production of bauxite, which comes from Alabama, Georgia and Arkansas, is limited to those bauxite ores containing less than about l ½ % iron. Bauxites with higher iron contents are generally not utilized because they cause problems in bauxite calcining and especially because they produce undesirable brick discoloration and cracking. In order to improve beneficiation and expand the utilization of high-iron or ferruginous bauxites, a mineralogical and textural study has been conducted on selected samples from the Eufaula, Alabama, bauxite district. Reflected light microscopic, petrographic, and X-ray techniques have shown that a variety of iron minerals are present, including hematite, goethite, lepidocrosite, siderite, pyrite, marcasite, and ilmenite. Although the iron minerals may be locally concentrated into concretions and pisolites, most occur as very fine grains that are disseminated and show a variety of intergrowths. Mineralogical and textural observations indicate that the fine-grained iron mineral grains may be amenable to high gradient magnetic separation.

Jan 1, 1981

By C. G. Bastos Andrade, F. R. Valenzuela Diaz, S. M. Toffoli

The climate change observed in the last decades, the increase of global warming, the melting of the polar ice caps, and the sea level rise have in common the non-sustainable development as causative agent. Different nations have mobilized joint efforts with the objectives of minimizing the impact of greenhouse gas (GHG) emissions, investing in the research and the development of new technologies in recycling, in biomaterials, environmentally friendly processes, and new fuel alternatives. This paper evaluates the efficiency of a Brazilian bentonite modified by acid attack, in the purification step of a waste oil to be used for biofuel production, that is, diesel from waste cooking oil (WCO). The following characterization test swere performed: XRD, CEC, XRF, SEM/EDS, specific surface area (BET), stereomicrography, kinematic viscosity, and spectrophotometry at 440 nm. The modified bentonite exhibited good purification capacity for WCO when compared to a commercial product.

Mar 1, 2018

By J. G. Zafiratos

The leaching of a Greek low-grade manganese dioxide ore, not amenable to conventional mineral processing operations, was studied using a mixed culture of Thiobacillus sp. bacteria. The experiments were carried out in specially designed continuously aerated and stirred tank reactors arranged in two-tank series. The first tank of each series was loaded with an elemental sulfur culture suspension while the second was loaded with a manganese ore high density slurry. The bacterial culture had been previously adapted to grow on elemental sulfur and also in the presence of manganese ore and dissolved manganous ion. A two level full factorial design was constructed in order to study the effects of the ferric ion concentration in the leach solution, the "elemental sulfu weight to ore weight" ratio, the ore pulp density and the composition of the dispersed gas. The responses which were investigated included percentage manganese recovery, co-dissolution of iron and manganese dissolution rate. Parameters with constant values throughout the experiments were the leach solution pH, the nutrient medium composition, the dilution rate and the ore and sulfur grain sizes. It was found that the ferric ion concentration was the most significant factor and had a positive effect on the final percentage extraction of manganese from the ore and also on the rate of manganese solubilization from the ore. The effects of the other factors studied are discussed in detail.

Jan 1, 1997

By Mohammed A. Tayeb, Narottam Behera, Raja Mathu

With the struggling steel market nowadays, steel producers are under intense pressure to reduce their operational cost. Therefore optimization in the melt shops becomes not only preferable, but mandatory. A continuous dynamic process model for scrap-DRI EAF process was developed. The model was then used to propose a new carbon profile, implemented successfully to decrease (%FeO) in the slag and improve the yield. While this work is continued at HADEED, this article reviews the basics of the model and presents a summary of the preliminary plant findings.

Mar 1, 2017

By W. W. Albrecht

I. Introduction Refractory metals like tungsten, molybdenum, rhenium, tantalum and niobium and their compounds are essential ingredients of our modern technology. Especially in purified form, they are used in special alloys, electronics, optics and ceramics. The processing route from raw material to high purity refractory metals and their compounds includes, as a prime option, the following steps: - dissolution of raw materials. - liquid liquid extraction. - precipitation of high purity intermediate compounds. - calcination/reduction to high purity oxides/metals. Especially in the first three steps, major amounts of chemicals like acids or sodium hydroxide are used and, as by-products, substantial quantities of residues and effluents are generated. The impact of environmental regulations on these by-products and the attempt to reduce or minimize the amount of residues and effluents produced will be discussed in this presentation using Ta/Nb chemistry as the example. The basis of our considerations will be the way these by-products are handled at HCST, a major, and in some cases, the biggest producer of refractory metals (tungsten, molybdenum, rhenium, tantalum, and niobium).

Jan 1, 1992

By M Kolbe

Co-Cu exhibits a metastable miscibility gap in the region of the undercooled melt. Specimens have been undercooled and solidified containerlessly into the metastable miscibility gap in an electromagnetic levitation facility (EML) and in drop tube (DT) experiments. Due to the high undercooling the velocity of the solidification front is very high and the microstructure is frozen in instantaneously. The microstructure of samples processed in the EML is influenced by the electromagnetic stirring due to the induction of electrical currents into the melt. A variety of microstructures has been observed. After undercooling below the binodal the liquid melt separates into the Co-rich L1-phase and the Cu-rich L2-phase. Two basic morphologies of the L1-phase can be observed, they can be attributed to the transition in dendrite growth from diffusionally and thermally controlled to only thermally controlled growth. Transient microstructures are observed after solidification in the vicinity of the binodal. Drop tube experiments, which lead to a rapid solidification of a distribution of droplets under reduced gravity conditions, in contrary allow for the observation of the early stages of demixing: the microstructure shows a homogeneous distribution of spherical particles of the minority phase in the droplets. The cooling rate of the droplets and its dependence on the droplet radius has been calculated. The solidification velocity as a function of undercooling has been measured in the EML for the composition Co-lB.Bat%Cu. The data are analysed in the framework of the LKTlBCT model with a velocity-dependent distribution coefficient as well as within a model of Galenko and Danilov using a kinetic growth coefficient of u=0.22 m/Ks.

Jan 1, 2002

By Federico Chavez

The process for recovering lead from battery residues used in several Mexican Plants include lead blast furnace and rotary furnaces. The formers are basically fed with recycled batteries together with the necessary additives to produce metallic lead. One of the by-products generated in the blast furnace is a dust mainly formed by lead sulfide. The rotary furnace is used to recover lead .from lead batteries, dross from the refining-alloying process and the leady fines produced in the blast furnace. This paper describes thennodynamic analysis made to the rotary furnace process to understand the effect that each component of the system has upon the lead recovery. In order to enhance the process, the influence of iron chips composition and excess coke on slag viscosity is discussed. A computer optimization program . has been developed to design the furnace charge based on material and energy balances, .together with the thennodynamic equilibrium calculation.

Jan 1, 1995

By M. K. Mohan

During the processing of metals like Cu, Ni, Co, large quantities of solutions, which contain co- products such as Sb, Cd, Pb etc. are generated. These solutions if processed to recover the metals help in conservation of metals as well as environment preservation. The present study was taken up to recover antimony from process solutions using zeolites. The effect of pH of the solution, time and type of zeolite viz., chabazite, mordenite, erionite and clinoptilolite on the sorption of antimony was investigated. Rate of sorption increases with pH and about 77-pct. antimony sorption was observed with chabazite at a pH of 6. Optimal conditions were established for the maximum recovery of antimony fiom process solutions. The mechanism of sorption for Sb was proposed in terms of adsorption and intraparticle diffusion. The calculated adsorption constants from Langmuir and Freundlich equations indicated that the adsorption of antimony on chabazite was strong.

Jan 1, 1999

In low carbon TRIP steels, the formation of carbide-free bainitic ferrite is crucial for the stabilization of austenite. Based on experimental investigations modeling the bainite reaction is examined adopting diffusional and displacive mechanisms, as well as the semi-empirical JMAK approach. Transformation tests were carried out to study the isothermal austenite decomposition into bainitic ferrite for a model steel containing 0.6wt%C, 1.5wt%Mm and 1.5wt%Si which replicates the composition of remaining austenite at the start of the bainite reaction in a classical C-Mn-Si TRIP steel. In the diffusional approach, classical nucleation theory is employed and subsequent growth of bainite plates is modeled using the Zener-Hillert theory. In the displacive approach, the autocatalytic nucleation of bairtite plates is assumed to be rate controlling. The predictive capability of all models is evaluated for temperature ranges where different morphologies of bainitic ferrite have been detected, The shortcomings and inherent challenges associated with either of these modeling approaches will be delineated.

Jan 1, 2003

By Keith M. Axler

This report addresses issues specific to the generation of hydrogen fluoride via reaction of calcium fluoride with sulfuric acid. This process has been established on a commercial scale and is under consideration for treatment of calcium fluoride residues from uranium processing. Magnesium fluoride slags are also available as a product of uranium processing. The technique of using sulfuric acid for the production of hydrogen fluoride from magnesium fluoride is also under consideration as a residue processing scheme. In the current study, thermodynamic modeling was used to investigate these chemical processing systems. The results presented herein reveal information relevant to the selection of processing temperatures and conditions. Details include predicted effects in system composition based on operating temperatures for both the calcium fluoride and the magnesium fluoride systems.

Jan 1, 1996

By Gavin Lind

The Minerals Council of Australia (MCA), through its Minerals Tertiary Education Council (MTEC), builds capacity in higher education in the core disciplines of mining engineering, metallurgy and minerals geoscience. Over the past fourteen years, this all-of-industry approach in securing the long-term supply of these critical skills (which remain a chronic skills shortage for the Australian minerals industry) through nationally collaborative programs across sixteen Australian universities delivers spectacular and sustainable results for the industry. These unique, world-first programs are built on a healthy platform of dedicated industry funding and in-kind support and forms part of the MCA’s broader uninterrupted, sustainable education and training pathway to increase workforce participation, workforce diversity and workforce skills, regardless of the business cycle in the industry. This paper will highlight the origins, iterations and current successful programs of MTEC, including its future vision, and presents a mechanism for industry and academia to collaborate to address future professional skills needs in the minerals industry globally.

Jan 1, 2014

By Mikiya Tanaka, Mikio Kobayashi, Mansour A. S. A1Ghamdi, Kenji Tatsumi, Yukinori Saiki, Hirotaka Senba

"In order to recover nickel ion in a spent electroless nickel - phosphorus alloy plating bath and, at the same time, to remove impurities such as iron and zinc, the applicability of solvent extraction with LlX84I as the extractant has been investigated using actual spent solution. Although the extraction efficiency of nickel from the spent solution is considerably lower than that from the nickel sulfate-nitrate solution, nickel in the spent solution is selectively extracted with high efficiency at the pH of 6 - 7. The extracted nickel is effectively stripped by sulfuric acid at a pH of less .than· 3. On the basis of these results, a· flowsheet for recovering nickel from the spent solution is proposed Chemical equilibrium calculations of the spent solution has shown that the complex formations of nickel with anions such as lactate and phosphonate ions become predominant in the pH range between 2 and 6. This results in the depression of nickel extraction efficiency from the spent solution as compared with that from the .nickel sulfate-nitrate solution. By combining these aqueous equilibrium calculations with the· extraction model considering the extraction stoichiometry and the aggregation of the extractant in the organic phase, the extraction behavior of nickel is quantitatively predicted.IntroductionElectroless plating is indispensable for the recent advanced industries such as the electronic and mechanical industries. Electroless plating baths are repeatedly used by supplying the metal salts; however, the accumulation of the counter anions of the metal ions, the components formed by the oxidation of the reducing reagents in the plating baths, and the metal ions as impurities dissolved from the surface of the objective materials degrades the· quality of the plating. Thus, the baths are finally treated by a precipitation method to form a large amount of metal sludge, which is disposed in dumping sites. Therefore, from the standpoints of environmental protection and resource preservation, it is highly desired to establish a recycling process of the plating baths with minimum emission. Solvent extraction seems to be one of the 'suitable methods to recover metals from the spent electroless plating baths, because the concentration of the metal ion in the baths is relatively high, which is advantageous to solvent extraction as compared with the ion-exchange and adsorption methods. Some studies about the application of solvent extraction have already been carried out using simulated spe11t electroless plating baths [1-3]."

Jan 1, 2000

By Ruixuan Zhang, Yan Li, Shusen Cheng

The high temperature distribution of the blast furnace raceway plays an important role in continuous and steady production. There are a number of techniques which have been developed for flame temperature measurements, but most of them have considerable errors and instability. To obtain more accurate results, an efficient optimization algorithm is necessary. This paper presents a novel measurement approach based on the two-color method and an optimization algorithm using images of raceway flame captured by the RGB CCD (Charged-couple Device) camera to calculate the projection temperature distri- bution. Furthermore, both the back-propagation neural network and the principal component analysis are applied to calibrate the correlation between blackbody temperature and the gray-level intensity. Experimental results obtained from the blast furnace raceway demonstrate that the proposed optimization approach performs well in the measurement offlame temperature compared with the measured temperature.

Mar 1, 2017

By T. R. A. Davey

A simple model for metal solution behaviour may be derived, on the basis of dilute solution solubilities (where? log concentration of solute varies linearly with reciprocal temperature) and not-so-dilute region solubilities (where the log of the alpha-function at saturation frequently varies linearly with reciprocal temperature) and assuming activity to vary according to the quadratic formalism in between. Matte binary systems usually exhibit regular .solution behaviour when the constituent species are chosen appropriately. In many recent papers, metal solubilities in .slags are expressed as the sum of several different and supposedly independant molecular species (e.g. oxides, sulfides, chlorides), Such a view is untenable because of the now proven ionic nature of slags. Some possible reasons for the great effect of sulfur on copper solubilities in slags are discussed.

Jan 1, 1985

By S. K. Wu, Ray Y. Lin, Sunil Annaji

Infrared joining of TiAI using aluminum foils as the filler material was investigated at temperatures between 1050 °C and 1350 °C in a flowing argon environment for times varying between 15 and 60 seconds. Using aluminum foils, the attempt was to form the Al3Ti phase in the joint as a result of reaction between Al and TiAI at temperatures above the melting point of Al. It has been found based on X-ray diffraction and TEM analysis that, Al3Ti, indeed is the product of infrared joining of TiAI using Al as the joining alloy. Al3 Ti was detected even in the joint processed at 1050 °C for only 15 seconds. Since the aluminum foil used in this study contains 27 at% Si, the t 2 phase in the Ti-Al-Si ternary system is believed to have also formed at the joint/base TiAI interface. Cross sectional studies on the joined specimens have shown different degrees of reaction depending on the temperature and time of joining. Micro hardness evaluations across the joint show that the hardness near the center of the joint is typically smaller than that near the joint edge next to the base material. However, as the joining temperature and time increase, the increment of the hardness at the center of the joint is faster than that around the periphery of the joint.

Jan 1, 1996

By N. Voennann

Stillwater Mining Company operates an electric furnace at its smelter in Columbus, Montana to treat a Ni-Cu-platinum group metal concentrate along with secondary PGM bearing materials. Hatch Associates has designed several improvements to this furnace, which was originally built by others. Implementation of these relatively low cost improvements has resulted in substantial increases in furnace availability and capacity, along with reduced unit costs. ? The improvements included: ? Installation of water-cooled copper cooling elements to stabilize refractory wear and increase furnace life.- ? Improved furnace 'bindings, to enhance the furnace's structural integrity by improving the contact between the refractory and cooling elements, and by promoting tight brick joints resistant to matte or slag leaks. ? Adjustment of the electrode regulator to allow higher furnace power levels. ? Installation of an automated air-slide (aeration conveyor) feed system to evenly distribute the furnace feed in an insulating layer on the bath surface. This "black-top" practice reduces unit energy costs and makes available additional smelting capacity.- ? Electrode seals to reduce ingress of air that absorbs heat before exiting the furnace in the off-gas stream. The saved energy can be used to smelt additional concentrate. This paper describes the above furnace modifications, and the benefits derived from their implementation.

Jan 1, 1998