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By C. S. Ek

As a continuation of previous work, further tests have been carried out to recover silver from the residues obtained in a zinc jarosite process. Selective flotation has been performed with different reagents, and ?cleaning steps have been introduced to upgrade the silver concentrate. Leaching of crude residues, as well as flotation tailings, has been carried out with cyanide and thiourea. Finally, the different beneficiation methods are compared, and the industrial aspects? of their application are reviewed.

Jan 1, 1990

By Joner O. Alves

The disposal of scrap tires has been a serious environmental problem. The treatment of this waste by pyrolysis and combustion has advantages since the landfill space is dwindling and the production of fuel becomes of technological interest. However, that processes needs a rigid control of emissions. This work presents a study of the light hydrocarbon gases (HC) generated during the burn of waste tire chips in a two-stage laminar-flow horizontal furnace. Different temperatures in the primary and secondary stage of the furnace were tested, and the oxygen/nitrogen percentage was also varied during the combustion process. A gas chromatograph was used to identify and quantify the components of the gaseous products of combustion and pyrolysis. The results showed the behavior of the gases during the burn of tires, providing valuable information to the control of hydrocarbon emissions.

Jan 1, 2010

By Augusto Viana Leandro Teixeira

Rare Earth Elements (REE) are fundamental for modern life products and green technologies. Supply constraints and the price peak of 2011 boosted intensive research for alternatives for processing and separation. Complex monazite- type, rare earth ores usually contain high acid consumption impurities, such as iron and aluminum, and radioactive thorium in their composition. These impurities are not removed by conventional concentration processes due to fine, micro-level association between the REE carrying minerals and the gangue minerals. This work presents a selective process route for REE extraction from iron-rich, monazite ores. The process involves sulfation by addition of concentrated sulfuric acid and pyrohydrolysis at temperatures of approximately 700–750 °C. Experimental results show REE extraction higher than 70% and low iron (below 5%) and thorium extraction (below 10%). A method based on thermogravimetric analyses was shown to be adequate to predict the behavior of a given ore sample in the sulfationselective pyrolysis-leaching process.

By Nan Wang

Based on the commercial computational fluid dynamics software, Fluent, the fluid flow and temperature field in an iron-bath reactor were simulated numerically, and the effects of top-blown and side-blown operating parameters on the mixing time of iron bath, distribution range of oxygen in top space, and post-combustion ratio were investigated. The simulated results showed that the mixing time of iron bath increased initially and then decreased with the increase of inclined degree and immersion depth of side-blown lance. The distribution range of oxygen became wider as pulling the top lance away from the iron bath. Furthermore, post-combustion ratio was reduced given the top lance was too close the bath. The simulation results provide theoretical base for the process optimization of iron-bath reactor and further development of new type iron-bath smelting reduction process.

Jan 1, 2009

By Mukesh Jain

The liquor from potroom wet scrubbers is treated with lime to precipitate the soluble fluorides. The solids after filtration, referred to as scrubber mud, contain in addition to calcium fluoride, alumina, carbon, tars including polyaromatic hydrocarbons (PAH), cryolite and pachnolite and are considered hazardous. This communication deals with the pilot plant scale calcination of scrubber mud with a rotary kiln to obtain non-hazardous fluoride raw materials. Air classification was performed to separate the mudinto aluminarich andcalcium fluoride rich fractions which were then calcined. With proper control of calcination parameters and addition of lime, the carbon and tars were destroyed and hydrogen fluoride emissions were controlled. The calcined products could be used in the steel indusny as a fluxing agent or as a substitute for fluorspar in the production of aluminum fluoride.

Jan 1, 1994

By Yan Beygelzimer, Alexander Spuskanyuk, Victor Varyukhin

"A cellular model of the plastic deformation of polycrystalline aggregate is proposed and comprehensively described. Representative volume element (RVE) of a solid body, that is being deformed, is described as a population of interconnected units that, in turn, can consist of lower scale level units. Sliding along the various allowed sliding systems deforms simple units, which do not have an internal structure. For consideration of stress distribution within the limits of components, the approach of self-consistent field is used. Rotation of units and moment stresses connected with it are taken into account. Results of computer experiments are analyzed.1. IntroductionMicromechanical models of polycrystals are a link between the research of plastic deformation on micro and macro levels. Computer simulation of inelastic strain of polycrystals has found a great deal of interest as well. Despite the fact that this approach does not allow to obtain macroscopic constitutive relationships that are used in deformed solid body mechanics, it clarifies essential features of the phenomena in many aspects. First of all, it concerns effects stipulated by interdependence of micro-level and macro level of plastic deformation processes. Also, with the computing mechanics, instead of constitutive relationships, the adequate computer models can be used. Broad possibilities for computer simulation of various processes are opened by cellular automata approach. By means of numerical experiments, the cellular automata allows to study the macro behavior of the whole ensemble of cells depending on the local microscopic laws that define evolution of each cell and its interaction with the closest environment.We propose a mathematical model of a polycrystalline aggregate (the cellular model) based on a self-consistent scheme and on the interaction law similar to the one by Berveiller and Zaoui [1]. Our original solution is the self-similar structure of cellular automata that allows modeling of the fractal nature of real materials (Figure 1). The goals of this work are to present the major structures and relations of cellular model of polycrystal and to test this model for its adequacy as for describing known effects and dependencies. Identification of the model and its application for studying of concrete polycrystals are put aside for the future research."

Jan 1, 2001

By Satu Strömberg

A single-particle laminar-flow technique was used to study oxidation of two nickel concentrates and a granulated nickel matte (43 wt% of Ni). Experimental conditions were: reaction gas from N2 to N2 + 75 vol% O2; gas preheating temperatures ranging from 500 to 1100°C. The major nickel-bearing minerals in the two concentrates were pentlandite and violarite, respectively. Chemical analysis of the particles was used to determine the oxidation degree of the materials, and optical and scanning electron microscopy were used to detect their morphology and mineralogy. Total desulfurization of the nickel concentrates was achieved under the most oxidizing conditions, while the sulfur removal from the nickel matte was not as efficient, especially with the coarse size fraction. Pentlandite-based concentrate was found to be less reactive than the violarite-based.

Jan 1, 1995

By Denis Shishin

The pyrometallurgical production and recycling of non-ferrous metals involves the use of complex feed stocks, having awide range of chemical compositions from sources that include mineral sulphide concentrates, high value obsolete materials and process wastes. The commercial viabilities of these operations hinge on the ability to extract value from these materials. Increasingly, modern computer-based tools are used to describe and predict process outcomes, including mass and heat balances, the partitioning of elements and phase equilibria. At the heart of these predictive tools are thermodynamic databases that describe the fundamental chemical properties of a system and all the components present. A comprehensive research program has been established to develop an accurate, self-consistent thermodynamic database describing all gas-slag-matte-metal-speiss-solid phases in the system Cu2O-PbO-ZnO-Al2O3- CaO-MgO-FeO-Fe2O3-SiO2-S-(As-Bi-Sb-Sn-Ag-Au). The database can be used in conjunction with the FactSage computer platform. The accuracy of the database and its application to industrial practice is demonstrated.

By M. B. Sizgoric

Quantitative mineralogy is used in a study done on an Inco Metals Company nickel sulfide occurrence from 'the Thompson area in Northern Manitoba. The study included: a) determination of the variations in chemical composition of the ore minerals; b) determination of the liberation of the ore minerals for the various types of ore and for different feed grinds; c) assessment of the preliminary mill test results by comparing the mineral distribution in the different tailings. Preliminary mill test results had outlined three main problem areas: 1) unacceptabiy low grade concentrate with, 2) very high weight recovery and, 3) low pyrrhotite rejection resulting in a high sulfur concentrate. The mineralogical study readily explained these results by showing that: 1) between 20 and 40% of the nickel in the feeds and 55 and 75% of the nickel lost in the tailings is associated with pyrrhotite. This accounts in part for the low grade of the concentrates obtained at high recoveries: 2) hexagonal nonmagnetic pyrrhotite constitutes over 90 percent of pyrrhotite. Since hexagonal pyrrhotite floats more readily than monoclinic pyrrhotite, this could be part of the reason for the undesirable high pyrrhotite recoveries into the concentrates. Further test work to establish both the optimal grind and the best conditions for pyrrhotite rejection is therefore mandatory.

Jan 1, 1981

By Kazuya Koyama

The leaching of copper from a printed circuit board (PCB) and the electrodeposition of copper from a cuprous solution in ammoniacal alkaline solutions were examined in order to develop an energy-saving hydrometallurgical process for copper recovery from electronic scrap. In the leaching experiments, copper in the PCB was oxidized by Cu(II), and Cu(I)-ammine complex ions were formed. The copper(I)-ammine complex slightly depressed the leaching rate, while Cu(II)?ammine markedly enhanced it. During the electrodeposition experiments, the current efficiency of copper deposition was approximately 100% in the current density range of 200 to 1000 Am-2. The electrodeposition of copper from the Cu(I)-ammine complex solution favored the production of plates rather than powders.

Jan 1, 2003

By A. Iván, Patiño C. Francisco, Flores B. Javier, Peréz L. Miguel, Hernandez A. Juan, Trapála P. Norma, Salinas R. Eleazar, Rivera L. Isauro, G. Flores, U. Mizraim

"Tills work is related with the production of tiles using wastes from mining and metallurgical industry of Hidalgo State, as raw material. These wastes present a majority particle size (60 %), minor than 53 m (mesh 270, in Tyler Series) with the following composition; 70.01 % wt. of Si02, 12.82 % wt. of Ah03, 3.80 % wt. of Fe, 0.70 % wt. of Mn, 3.98 % wt. ofK20, 3.34 % wt. of CaO, 2.50 % wt. ofNa20, 0.04 % wt. of Zn, 0.026 % wt. of Pb, 56 grams per ton of Ag and 0.6 grams per ton of Au. In this work, the partial results and experimental conditions for the preparation of some composites to produce tiles are shown. The composite that offers the best results in productions of tiles was that with 66.67 % wt. of mining waste, 26.67 % wt. of red mud and 6.67 % wt. of black mud.IntroductionTo now, mining activities carried out during more than 457 years in Hidalgo State, Mexico; has lead a great volume of wastes; which can be classified into different types, having among the more common; Acid mining water, solid transport water, elements in radical form, abandoned minerals without processing and processing minerals wastes known as burrows, being these the most abundant in the region counting with an approximated volume of 110 million of tons, presenting a fine particle size that can affect population health during windy epochs [1 -4].Form metallurgical point of view, is well known that a fundamental characterization study it is necessary to know the viability of reusing or recycling of these wastes. According this, these residues can also be considered as raw materials in other economical activities, due its Si, Fe, AI, Ca, Na and P oxides contents, its mineralogy and the distribution of chemical elements in the primary and secondary phases [1,2,5,6]."

Jan 1, 2012

By E. W. Lithgow

Commercial volumes of nickeliferous laterite ores overlie part of a 90 km long belt of peridotites in central Dominican Republic. Protores are serpentinized harzburgites and dunites, with lesser serpentinite. The ore mineralogy consists mostly of goethite, serpentine-group minerals, quartz and poorly crystallized, x- ray amorphous materials. Minor constituents are hematite, gibbsite, olivine and enstatite. In the Ore Dressing plant the mine feed is subjected initially to proper sizing and blending to produce a homogenized mix. Subsequent drying and upgrading, by selective crushing and screening of rock fragments through a Barmac circuit, complete preparation of the ore for pyrometallurgical processing.

Jan 1, 1993

By Jiang Feng, Li Chuanhua, Zhang Libo, Peng Jinhui, Ju Shaohua

Solvent extraction of Cu2+ from the leaching liquor contain Cu and Fe use a microfluidic technology. Currently, the conventional copper extraction process has many problems such as long distance and small driving force of mass transfer. In order to solve the problems, studies are carried out on the extraction process of low grade copper leaching liquid using Lix984N as an extractant with a new microfluidic solvent extraction technology. The effects of flow rate on the separation and extraction efficiency between Cu and Fe are studied, and the results show that a steady liquid-liquid interface of laminar flow is form in the micro-extractor, and extraction efficiency is 78 % and 2.5 % for Cu and Fe at the contact times of 0.84s respectively. Besides, the separation coefficient between Cu and Fe is as high as 140.04. The studied microfluidic technology has the advantages like improving extraction efficiency and reducing reaction time and providing the potential application in the hydrometallurgy extraction of Cu.

Jan 1, 2015

By cheng Peng-fei, TANG Hai-yan, guo Xiao-chen, LI Jing-she, Liang Yong-cang, Zhao Baojun

The origin and evolution of non-metallic inclusions for Al-killed casing steel during EAF-LFVD- CC process were studied by industrial tracer experiments. The formations of Al2O3 and MgO·Al2O3 micro- and macro-inclusions from ladle slag were analyzed by theoretical calculations. The results show that micro-inclusions were formed during deoxidation and temperature decreasing in the process of casting, most of the macro-inclusions come from entrapped ladle and mold slags. In addition, most of the Al2O3 formed were modified into 12CaO·7Al2O3 and 3CaO·Al2O3 inclusions which are liquid at steelmaking temperature. MnS cannot be fully modified to CaS and it was only wrapped outside the alumina or calcium aluminate in the form of (Ca,Mn)S with the amount of Ca-Si wire fed during the test.

Jan 1, 2016

By J. W. Matousek

Cobalt behavior in pyrometallurgical processes is traditionally analyzed using slaglmatte distribution coefficients as functions of matte grades or matte iron contents. L(s/m) = (%Co) I [%Co] = f [%CuNi] or f [%Fe] The method is inconvenient to use in predictive mass balance work because of the interdependence of assays and mass quantities. An alternative procedure is proposed based on cobaltliron ratios for slags and mattes: Js = (%Co) / (%Fe), Jm = [%Co] / [%Fe], and J, = b + m [Jm]

Jan 1, 1993

By Yousef Mohassab, Manoranjan Misra, Monalisa Panda, Eman Wahbah

This work studies the removal of arsenic (V), arsenate, and arsenic (III), arsenite, from aqueous solution using calcined Quintinite-3T. The two adsorbents Quintinite-3T was prepared, calcined at different temperatures, and characterized by XRD, BET, and SEM. The surface area of the calcined Quintinite-3T was 193.4 m2/g. The particles size ranged from 12 to 56 nm for the uncalcined Quintinite-3T and from 24 to 42 nm for the calcined Quintinite-3T. Kinetic analysis, adsorption isotherm, and factors affecting the adsorption were investigated. Calcined Quintinite- 3T retained As(v) and did not release it back to water even after an entire month.

Jan 1, 2016

By Lin Li, Wen Shi, Hua Wang

"Specimens of the ultra-low carbon bake hardening steel were soaked for 1 min to 5 min, and then cooled by water quenching. The internal friction experiments were carried out to detect the spectra of the specimens. Results show that Snoek peaks are present in all the specimens, however, an obvious Snoek-Koster peak is found only in the 5 min-annealed specimen. Besides, tensile results indicate that the bake hardening values increase with the annealing time prolonging from 1 min to 3 min, but decrease as the annealing time prolongs further to 5 min. The solute distributions in the specimens were characterized by three dimensional atom probe. Some segregated C and V are found in the 1 min-annealed specimen, and the C and V contents decrease as annealing time prolongs to 5 min.1. IntroductionAs an excellent member of automotive body panel materials, various types of bake hardening (BH) steels have been developed since 1980s. Bake hardening property, as one of the most important mechanical properties, has been studied by many researchers [ 1-5]. As is known, BH phenomenon is generally controlled by the interaction between solute C and dislocations. The Snoek peak of internal friction (IF) is very popular in the investigation of solute C [6-9]. However, result of internal friction cannot suggest the distribution pattern of solute C as well as its influence on BH phenomenon.Three dimensional atom probe (3DAP) can diagnose solute element atoms as well as nano-sized precipitates, and it is the only instrument that currently can identify the identities of individual atoms in a material and measure their spatial coordinates with the resolution close to 0.3 nm [10]. There have been a number of studies about using 3DAP to detect solute elements as well as nanometer sized precipitates [11-19]. For example, Hono et al. [16] used 3DAP to determine the solute elements in an age-hardened Mg-Ca-Zn alloy, and they also obtained the distribution patterns of the observed elements."

Jan 1, 2011

By Jared Ball, Darren Snashall, Paul Telford, Pengfu Tan, Ben Hogg

"The foamed converter charges were up to 3 8 per month in Xstrata Copper Smelter at Mount Isa. The issue of high converter foamover frequency had remained unsolved for many decades in Mount Isa. A thermodynamic model of copper P-S converter and a viscosity model of converter slag have been developed to simulate the slag blow and copper blow, in order to understand the mechanism of converter foamover. The model predicts the chemistry and viscosity of slag during slag blow and copper blow. The effects of oxygen potential, charge of dirty reverts, slag carryover, under-blowing, over-blowing, and temperature on the foamover and viscosity of slag in copper blow have been discussed. A theory has been developed to understand the mechanism of converter foamover. The practical solutions have also been developed and implemented in Mount Isa Copper Smelter. Some improvements of the industrial operations have been presented. After a series of improvements, the number of foamed charges per month in the converter operations has been decreased significantly from 35 in Aug 2008 to only one per month in 2009/2010.1. IntroductionThe Copper Smelter in Mount Isa receives the concentrate containing about 25% copper and produces anode copper that contains about 99% copper. There are several stages in the process. The first stage carries out in the ISASMELT™ furnace. The ISASMELT™ process produces a molten copper matte containing about 60% copper. An iron-silica slag and a sulfur dioxidebearing off-gas are the by-products of the process. The slag is taken to the slag dams for cooling before it is recycled through the Mount Isa Copper Concentrator.The matte is sent to Peirce-Smith converters. The converters further remove iron and sulphur to produce blister copper which contains about 97% copper. The anode furnaces remove any remaining sulphur and oxygen to produce anode copper that is about 99. 7% pure. This is cast into anodes and sent to the Xstrata Copper Refinery in Townsville for final refining.In the copper pyrometallurgical industrials, slag foaming is an important phenomena which occurs when the gas bubbles have stability and not rupture. Foaming greatly increases the interfacial area between matte, slag and gas and is essential for the operation of high intensity smelting processes. However, foaming or foamover is undesirable in P-S converter since it can damage the equipment and injure the operators. Figure 1 shows that the whole process of a foamover development in a converter."

Jan 1, 2011

By A. Mezei

A process has been developed to recover cobalt, gold and bismuth from the NICO deposit in Canada. The process consists of a bulk rougher flotation followed by an optional separation by flotation to produce a bismuth concentrate and a cobalt concentrate, grading on average 12.8 % Bi and 1.8% Co, respectively. Cobalt is leached by pressure oxidation at 97% efficiency, producing a pregnant solution suitable for further processing. Before optimization, about 38% of the bismuth is recovered in the selective concentrate, wherefrom it is recovered by ferric chloride leaching followed by cementation, at overall efficiencies exceeding 98%. The gold is recovered from the cobalt and bismuth leach residues by cyanidation, at 95% efficiency. Previous work described the results of the leaching of the concentrates, recovery of gold (Part I) and the recovery of bismuth (Part 11). This work describes the results of the cobalt recovery testwork and the resulting conceptual flowsheet. The sulfur dioxide-oxygen system was the most efficient for the oxidationlprecipitation of iron and arsenic from cobalt bearing pregnant leach solutions, producing purified solutions assaying <1 mg/L As and <8 mg/L Fe. The efficiency of cobalt solvent extraction (from the resulting purified PLS containing about 1 g/L Co) ranged from 9 1 to 98%; the co-extractions ranged from 88 to 100% for copper, from 28 to 33% for magnesium, from 6 to 7% for calcium and from 96 to 98% for zinc. Sulphide precipitation processes (using either sulfur dioxidelelemental sulfur or sodium sulfide) produced residual copper concentrations in the cobalt strip solution ranging from 0.1 to 2 mg/L Cu. About 90% of the calcium and magnesium were separated by scrubbing the organic with cobalt sulfate, producing residual concentrations of 12 mg/L Ca and from 180 to 330 mg/L Mg in typical feed solutions directed to cobalt carbonate precipitation tests. Cobalt carbonate precipitation efficiencies ranged from 75 to 78% when calcium and magnesium co- precipitations were restricted from 8 to 17% and 0.3 to 0.4%, respectively. The limits required by most stringent specifications on commercial grade cobalt carbonate products were met or exceeded.

Jan 1, 2002

By Neale R. Neelameggham

"Ferrous and non-ferrous metal industries are used to handling several billion tons a year of ore bodies, fuel and fluxing agents by mineral processing techniques and varieties of extractive metallurgy ""Reduction"" processes. Metal industry know-how can be applied to meet the challenge of Reducing CO2 in the atmosphere. Processes for generating alloys of carbon and hydrogen by Reducing the CO2 and water mixture, [carbonated water or water vapor] called Soda, to easily stored fuels are normally endothermic. The processes are similar to generation of hydrogen alone from water which is also endothermic. But hydrogen is more difficult to store than compounds [or alloys] of carbon and hydrogen. This recycling of CO2 and water are possible by using other forms of energy by innovative carbon capture methods.Thermodynamic Diagrams developed for Soda [CO2 and H2O] - metal reactions provide hints for using low cost unused stored energy in un-recycled metallic waste for thermal conversion. Choices for conditions for the electrochemical approaches [using solar - wind - hydropower] are also discussed.INTRODUCTIONIn 2006, I was reading some of the arguments put forth by learned scientists on the benefits and lack of benefits of bio-fuels. I found that the arguments rose partly from the differing system boundaries that were chosen by one versus the other. Some part of the argument may have been based on political climate or atmosphere rather than the analytical science. This situation is seen when scientists discuss which came first - the chicken or the egg, the fuel or biological matter, the oxide or the element, and so on.Then I thought –[just like many of the learned persons participating in this symposium] that common fuels - regardless of them being simple hydrocarbons or oxygenated hydrocarbons or carbohydrates - can all be made from the respective oxides of carbon and hydrogen by simple chemical reductions efficiently carried out in an economical fashion. This is the systematic approach we take when designing a chemical or metallurgical process facility."

Jan 1, 2008