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By Qian Li, Honggui Han, Jun Wang, Shichao Yu, Chunxiao Zhao, Maoxing Hong, Rui Liao, Xingxing Wang

In this study, bioleaching experiments, synchrotron X-ray Diffraction (SR-XRD), X-ray absorption near edge structure (XANES) and X-ray Photoelectron Spectroscopy (XPS) were conducted to investigate the intermediates and surface species of bornite leached by mesophilic mixed bacteria of Leptospirillum ferriphilum, Acidithiobacillus caldus and Sulfobacillus thermosulfidooxidans. CuS, Cu9Fe9S16 and S8 were the main intermediate species during bornite bioleaching by mesophilic mixed bacteria, and CuFeS2 was also detected. The surface species of S2− and S2 2− would be polymerized to Sn 2− during bioleaching. The formation of element sulfur and the increase of its content were confirmed by the fitted results of XPS spectra. The presence of polysulfide and element sulfur did not inhibit the bornite bioleaching. The formations of CuS and CuFeS2 were confirmed by the results of Cu K-edge XANES spectra.

Mar 1, 2018

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 André L. B. Bittencourt

The copper content in the waste slag represents the greatest loss in the process of Caraíba Metais' Smelter. By identifying the variables responsible for copper stabilization in the slag, a minimization on these losses is expected, producing a granulated waste slag with a copper content lower than 0.7%. Statistics resourses such as control charts, Pareto's diagram and correlations curves were applied for the data obtained in the first semester of 1992. The magnetite and the calcium oxide contents in the slag of the Flash Smelter Furnace were most prominent variables. Some operational changes introduced during and after this investigation have shown good results.

Jan 1, 1994

By Liangying Wen, Feng Xia, Chenguang Bai

"The situation of the Ti-V-Magnetite samples reduced with microwave has been investigated in laboratory. Firstly, the paper focuses on the heating behaviors of vanadium-titanium magnetite and characteristics of carbothermic reduction of V-Ti-magnetite in the microwave field. The effect of concentrate's size, quality on heating behaviors and reduction processes were researched. Results show that microwave heating may be a new heating resource replace of carbonic combustion reaction in reducing reaction. When the allocation of carbon is (16.7-30)%, carbothermic reduction of V-Ti-magnetite in the microwave field can proceed; with the increasing of carbon mixed, the metallization rate increases; and Fe, V can be reduced from their oxides in the microwave field; Titanic low oxide can be reduced from TiO2.1. IntroductionThe resource of Ti-V-Magnetite is abundant in the western area of Panzhihua in China, so far a mineral deposit of 4.64 billion tons have been proved up, it contains 14.75 million tons of V2O S which accounted for 87% of the vanadium and 5.93 hundred million tons of TiO2 accounted for 94% of the titanium resource respectively in China. The previous study proved that the major composition of mineral of the Ti-V-magnetite are Ti-magnetite, limonite, iron spinel, magnesium spinel etc, and the main elements of the Ti-V-magnetite in this area are Fe, Ti, V, Cr, Co, Ni, Ga, Sc etc[1] Due to the restrict of the BF-BOF process technical, during the smelting of the iron, the level of extracting the vanadium, titanium as well as other metal elements is limited. This results serious wasting of resources. To develop a new reduction process of Ti-V-magnetite is on the agenda, the microwave assistant reduction could meets this need, based on its characteristic of easy controlling of heating rate. To make use of the microwave energy to substitute the released heat sources of carbon combustion with air, use the solid phase state reduction at a relative lower temperature, make the beneficial element in Ti-V-magnetite transferred into the metal phase, then separated from the impurity. It is well worth to point out that once the microwave based reduction method has its industrial scale, it will take an outstanding position by its less release of carbon dioxide. This new environment-friendly process will play a vital role in the development of social industry and economy."

Jan 1, 2008

By Muammer Kaya, Sait Kursunoglu

"The aim of this study was to investigate the effectiveness of ascorbic (C6H8O6) / oxalic (C2H2O4) acid as a reductant for the simultaneous recovery of zinc and manganese from a spent and mixed zinc-carbon and alkaline battery powder in sulphuric acid leaching. The effects of sulfuric acid concentration, ascorbic/oxalic acid dosages, reaction temperature and leaching time on the zinc and manganese dissolutions were investigated according to 2k full factorial experimental design; then, a simple optimization study was carried out for the best reductant. The optimum reductive acid leaching conditions were determined at 3 hours leaching time, 70°C leaching temperature, 0.5M sulfuric acid concentration, 13 g/L ascorbic acid dosage, 1/20 g/mL solid/liquid ratio and 200 rpm stirring speed. Under these conditions, the dissolution efficiencies were 99.9% for Zn and 99.3% for Mn. When our results were compared with the previous results, our findings were better than previous studies.In addition, the manganese dissolution kinetics was undertaken, and the activation energy was found to be 7.04 kJ/mol. Selective precipitations of Zn and Mn from acid solutions were carried out using NaOH and KOH. Using 3M NaOH as precipitating agent at room temperature and at pH 8; 95.4% of Zn and at pH 10; 93.7% of Mn were precipitated from the leaching solution. Under the same conditions, using 3 M KOH at pH 8; 91.6% of Zn and at pH 10, 96.4% of Mn were precipitated. Based on the experimental results obtained, an appropriate flow sheet was proposed to recover zinc and manganese."

Jan 1, 2012

By Mohammad Mokmeli, Colin Oloman, Rod McElroy, William McWilliam, Bruce Downing, David Trueman, David Dreisinger

Lithium is anticipated to be a key, strategic material in the clean tech- nology economy. The majority of lithium reserves are contained in continental brines and sea water (>60%). Currently the most economical approach to recover lithium from such resources is through selective adsorption. Spinel type lithium manganese oxide and lithium titanium oxide have demonstrated to be excellent candidate materials (after de-lithiation). However, due to the small size of the powders, they have limited industrial application and require immobilization. In this work, we examine the application of novel manganese oxide nanowire composites for the extraction of lithium from dilute solutions. Manganese oxide nanowires were synthesized and simultaneously immobilized on diatomaceous earth via hydrothermal method. Lithium manganese oxide were then formed by solid-state reaction, de-lithiated and tested for lithium ion adsorption.

Mar 1, 2018

By Li. Jiarong, Zuojian Liang, Qingyan Xu, Baicheng Liu, Shizhong Liu, Hailong Yuan

Single crystal solidification of turbine blades is a key technology for the production of reliable and high efficiency gas turbines. The solidification process of single crystal investment castings causes a number of problems that have to be solved such as the increase of casting defects and complexity of production process. Computer modeling and simulation is helpful to predict the defects and improve the process design. In the paper, a mathematical model for three dimensional simulation of solidification and single crystal growth of investment castings was developed based on CA, mechanism of crystal growth and basic transfer equations such as heat, mass transfer equations. Many factors including constitutional undercooling, curvature undercooling and anisotropy, which had vital influences on microstructure evolution, were considered in the model. Temperature, crystal growth interface and structure defects of investment castings of single crystal superalloy were investigated at withdrawal rates of 4.5mm/min and 7mm/min. Simulated results showed that microstructure evolution and structure defects were predicted reasonably and calculated results were coincident with experimental ones. The study indicated that three dimensional solidification simulation technique is a powerful tool for understanding the fundamental of solidification and the formation of structure defects in single crystal investment castings and finally for optimizing process design.

Jan 1, 2004

By T. S. Montgomery

The performance of carbon-magnesia brick in electric arc furnaces (EAF) is interpreted in light of their observed optical microstructures. Features at the bricks' hot faces were protruding periclase grains, metal globules, graphite-metal contacts and linear void patterns. These features were com-pared to similar features previously seen from microstructures of basic oxygen furnace (BOF) refractories. Modes of formation were sought; an attempt was made to interpret their influence related to wear mechanisms.

Jan 1, 1982

By Xiao-hui Fan, Xu-ling Chen, Xiao-xian Huang, Gui-ming Yang

Grate-kiln-cooler is a predominant process of producing iron ore pellets in China. Since this process is of multi-variant, strong coupling and large hysteresis characteristics, a reliable performance monitoring is thus essential to ensure product quality and economic benefits. Aiming to efficiently monitor the pellet induration within this process, this study proposed an approach that combines statistical analysis and quality soft-measurement. Soft-measurement of pellet quality was accomplished based on the predicted time-temperature profile, and the soft-measured indices were on-line monitored using statistical control charts. Based on the proposed approach, a monitoring system for grate-kiln-cooler thermal process was developed for a domestic pelletizing plant. Running results demonstrate that our system can assist in the detection or diagnosis of abnormal thermal state and finally helps to stabilize the pellet production.

Jan 1, 2016

By G. A. Irons, D. Guo

"The average spout height and width produced by bottom gas injection in a water model of a steel ladle were measured with an image processing technique. It was revealed that the spout height could be described by a Gaussian curve. A combined SIMPLE -VOF model was developed to simulate the liquid surface and flow. The results showed that, though the model produced reasonable velocity distributions and free surface positions, the spout height due to the dynamic head of the rising liquid was substantially lower than observed, indicating that the bubble dynamics at the bath surface play an important role in spout height.IntroductionDue to the enormous importance of gas injection and stirring in metallurgical processes, there have been numerous publications on water and numerical modeling of such vessels. The free surface of the bath has received considerably less attention, despite its importance. At the free surface there are often important chemical phenomena occurring that require a good understanding of the fluid flow; these would include reoxidation of steel, metal splash and fume formation. Furthermore, to understand the details of slag-metal interactions such as slag entrainment, metal losses to slag and the transport phenomena associated with refining reactions, it is necessary to understand the plume and spout interactions first.There have been few experimental studies of the free surface of liquid in gas-injected ladles [1- 3], and even fewer on numerical modeling. Brimacombe and co-workers [1] studied the gas void fraction in the spout region, using a double-tip electrical resistance probe. This sensor cannot distinguish between gas in bubbles about to break and gas in the freeboard. Thus, it is a matter of judgement as to the position of the free surface. Schwerdtfeger and co-workers [2] used a single probe configuration with a wire and a counter electrode in the liquid, so that the height of the continuous liquid phase was unambiguously determined. Irons and co-workers [3] measured the spout height by ultrasonic and electrical capacitance techniques. These techniques were as reliable as the resistance techniques, but were restricted to low flow rates."

Jan 1, 2001

By Preben Ingerslev

Control of the reheating of ingots is based either on surface temperature measurements using optical pyrometers or on furnace set points and reheat time determined empirically. This paper presents a real-time mathematical heat flow model, named BESTT, which calculates the temperature distribution in an ingot cross section when reheated or cooled. The model runs on a 486 PC in less than one minute for a variety of ingot cross sectional shapes such as circular, square and with some considerations octagonal and heavy-cornered square. Initial temperatures can either be uniform or nonuniform while accounting for temperature dependent thermophysical properties. The model was developed and verified using 718 alloy ingots in box type furnaces. When integrated with on-line pyrometric measurements, BESTT can provide for improved feed back in the reheating control loop. The use of BESlT will assist in reducing energy costs, and improving product quality and consistency. EPD Congress 1994 Edited by C. Warren The Minerals, Metals k Materials Sodety, 1993

Jan 1, 1994

Several processes are now available for the recovery of free and WAD cyanide from gold plant solutions and pulps. In the past, the incentive for evaluating cyanide recovery in gold plant flowsheets has been economic. In many cases, it has been possible to demonstrate (at least in the laboratory and on paper), an improvement in process economics by; (i) reducing the costs of tailings detoxification, (ii) recycling cyanide at lower cost than the purchase/delivery price of new cyanide, and (iii) generating additional revenue via by¬product sales. Despite these convincing arguments, few cyanide recovery plants have been built at operating gold mines. Also, there is arguably an even more compelling reason for mining companies to consider cyanide recycling. With the growing storm of negative public opinion that the use of cyanide in the mining industry is attracting - following several highly publicized spills over the last couple of years - the time has come for the gold industry to demonstrate environmental diligence and stewardship in the use of this commodity that is so vital for their industry. There is no doubt that the widespread implementation of cyanide recycling will reduce the impact of the cyanidation process on the environment, both by reducing the risk of spills (with less cyanide being transported from manufacturing plants to gold mines), and by reducing the loading of toxic and non-toxic metals and ions in the tailings. In this paper, the various processes that are available for cyanide recovery are discussed, along with the process chemistry. Results of several laboratory and pilot plant trials that have been conducted over the last few years are also presented.

Jan 1, 1998

By Phillip A. Armstrong, Charles A. Lewinsohn, John H. Gordon

"This paper describes the opportunity offered by employing systems based on mixed conductive ceramics, in particular, ceramics conductive to oxygen ions and electrons, in reducing CO2 emissions from metallurgical production. Membranes based on these mixed conducting properties enable commercial viability of several attractive metallurgical processes. One of these processes utilizes modular, ceramic-membrane structures for the generation of pure oxygen, in tonnage quantity. The membrane-based systems offer significant capital savings and operating efficiencies in various metallurgical processes. The current status of this technology is summarized below.IntroductionCryogenic oxygen supply technology is currently the state-of-the-art for applications that require large quantities of oxygen (hundreds to thousands of tons per day). Cryogenic technology, however, requires substantial energy inputs and, hence, adds significant costs and emissions to processes. Furthermore, cryogenic oxygen supply technology is mature and there is relatively little potential for substantial capital cost reduction or efficiency improvement in coming decades. Non-cryogenic technologies offer a means to reduce the environmental footprint and cost of the oxygen supply facility in various applications.Ion Transport membranesCommercially available non-cryogenic air separation technologies, such as adsorption-based and polymeric membrane-based methods, do not afford the economies of scale that the cryogenic distillation enjoys. Therefore, industrial gas industry researchers began searching for alternatives to the relatively inactive and unselective polymeric membrane materials available. In the late 1980’s, Air Products began developing a new class of highly selective membrane materials with exceptionally high activity for oxygen transport. The materials constitute a class of oxide ceramics, and conduct both oxygen (as oxygen ions) and electrons in the same membrane, separating oxygen from air electrochemically. Numerous detailed process economics studies have shown that, based on these ion-transport membranes (ITM’s), the cost of oxygen can be reduced by approximately one-third relative to that obtained from state-of-the-art cryogenic oxygen supply technology, through a combination of capital cost savings and efficiency improvements. [1,2,3]"

Jan 1, 2008

By Zeng Zheng, Liu Chen, Yu Xing-Fu, Tian Su-Gui, Zhang Chao

"Single crystal nickel-base superalloy is prepared by using the various withdrawing rates. By measuring creep properties and microstructure observation, the influence of the element segregation on creep properties of the superalloys is investigated. Results show that the dendrite spacing and the segregation extent of the elements decrease with the enhancing withdrawing rate. The superalloy with smaller dendrite spacing has lower segregation of the elements and better creep resistance. The dislocations climbing over the rafted y’ phase is thought to be the deformation mechanism of the alloy during steady state creep. In the later stage of creep, the fact that some dislocations shear into the rafted y’ phase may twist the rafted y’ phase. As the creep goes on, the initiation and propagation of the cracks occur up to occurring creep fracture, which is thought to be the fracture mechanism of the superalloy during creep.1. IntroductionSingle crystal nickel-based superalloys consist of high volume fraction of ?? strengthening phase and ? matrix, and possess the excellent high-temperature mechanical and creep properties, therefore, they have become the main material to make the blades of the advanced aeroengines[1-3]. Some literatures report that the temperature-bearing and creep-resistance properties of the single crystal nickel-based superalloys can be remarkably improved as the increases content of the refractory elements, such as W and Re[4-6]."

Jan 1, 2012

By Stephen K. Pave1

Over 1,100 tons per day of Fluid Catalytic Cracking Unit (FCCU) catalyst is used worldwide. During the cracking reaction, catalyst is contaminated by deposited metals including nickel, vanadium, potassium, copper, iron, sodium, etc. To compensate for contaminants, a portion of the circulating catalyst inventory is withdrawn for disposal and fresh catalyst is added. The DEMETR process takes spent FCCU catalyst and removes a portion of the metal contaminants, enabling the refiner to recycle demetallized catalyst, thus reducing the solid waste from the refinery. Through August, 1993, the operation of one unit for one refiner has resulted in the recycling of over 7,500 tons of spent catalyst.

Jan 1, 1994

By E. vanHuyssteen

A method of establishing the relationship between the mineralogy of a sinter and its subsequent processing behaviour in a lead blast furnace is demonstrated. It involves: 1) analyzing the Zn-spinels, hardystonite, larsenite, Pb-silicates, Pb-arsenates, Pb-(Ca)-sulphates and other femtes with an electron microprobe; 2) determining the extent of elemental substitutions in various mineral structures; 3) establishing a sequence in which the various phases formed during sintering. In this manner the relationship between the bulk chemistry of a sinter formulation and the speciation of elements into various phases in the sinter can be established. Specifically, the-substitution of Mg for Zn in hardystonite significantly influences sinter production. Mg substitution releases Zn into the surrounding matrix. This Zn reacts with the Pb-silicate to form larsenite thereby reducing the amount of Pb-silicate available for anhydrite digestion. Excessive amounts of residual anhydrite thus result if the sinter formulation is based solely on the CaO/Si& ratio.

Jan 1, 1993

By James R. Myers

A source of clean gas containing sulfur dioxide and sufficient oxygen for convers.ion to sulfur trioxide ?is essential to the production of sulfuric acid. S02 containing gases obtained from roasting sulfide ores are heavily contaminated with inorganic dust and volatile impurities. If not removed, these contaminants will reduce product acid quality, foul the catalyst beds and mist eliminators, and accelerate equipment corrosion. This paper reviews conventional gas cleaning systems for metallurgical acid plants, followed by a discussion of modern systems utilizing DynaWave Scrubber technology. This technology is based on a unique approach to? gas scrubbing that can concurrently accomplish several gas cleaning/processing tasks scrubbing liquid is injected into the gas stream to create. a "Froth Zone". This is a region of extreme turbulence, with a very high rate of liquid .surface renewal. It efficiently removes both particulate matter and gas contaminants, and is also a cost effective quenching device for gases as hot as 1250º C. Smelter

Jan 1, 1992

By B. G. Thomas

"Mathematical process models can be applied in several different ways to serve industry by inducing beneficial changes to process operation. This paper attempts to summarize the different uses, types, and attributes of these models, and to offer some ideas to consider when developing, using, and reporting on them. Process models range from empirical to mechanistic in nature and vary in complexity from simple analytical solutions to coupled, 3-D transient numerical simulations. They are classified here according to the way in which they are implemented in practice, viz. fully-online models, semi-online models, off-line models, and literature models. The purpose of the model should dictate how choices are made during its development. Ways to validate and compare the model with experiments are suggested. Examples are taken in the context of the author's experience in modeling the continuous casting of steel.IntroductionThe objective of this paper is to provide a partial introduction for this symposium by discussing some basic aspects of the application of mathematical process models in industry. Essentially, the aim is to explore how process models are used to benefit industry, and to offer some general comments and suggestions, based on the experience of the author, on how models can best meet this goal.This work is concerned with process models, which consist of systems of mathematical equations and constants that are solved on a computer to make quantitative predictions about some aspect(s) of the process. The specific variables required as input data and generated as output data are important features of the model. The equations often derive from a numerical solution to one or more differential equations and their boundary conditions. The model also includes the constants, which represent material properties, empirical relationships, and other knowledge about the process, and usually require considerable effort to obtain. Thus, general purpose commercial software packages, (ie. finite-element or finite-difference based codes), are not models in this context. They are useful tools, however, serving as frameworks for the development of process models."

Jan 1, 1994

By Hong Yong Sohn, Miguel Olivas-Martinez

"Different approaches are used for calculating the ‘energy requirement’ of a process. The determination of energy requirement becomes confusing for a process in which a fuel is also a reactant. The key issue is which heat of chemical reaction should be included in the ‘energy requirement’ value. We will use the example of ironmaking processes to illustrate the problem. The different approaches essentially boil down to the question: does one include the combustion heat of the reductant used in the reduction reaction or just the heat of the reduction reaction? Depending on the viewpoint, either approach can be accepted; it is a matter of convention. There is a need, however, to select a standard approach because the absolute value of ‘energy requirement’ of a process depends on the choice. The energy requirement of a novel flash ironmaking process will be compared with that of an average blast furnace operation.IntroductionDifferent approaches are used for performing energy balance calculations and perhaps more significantly in presenting the ‘energy requirement’ of a process. The question becomes more involved for a process in which one or more reactants are also used to generate the process heat by combustion. Often the key issue is which heat of chemical reaction to include in presenting the ‘energy requirement’ of the process.It is worthwhile to note at the outset that the difference in energy requirements between different processes for converting similar raw materials to the same desired product is largely unaffected by the choice of chemical reactions to be included. However, the absolute value presented as the ‘energy requirement’ of a process can be different by a large amount depending on the approach. We use the example of ironmaking processes to illustrate the problem. In these processes, as currently practiced or under development, carbon and/or hydrocarbons (including hydrogen) are used as the fuel as well as the reactant for reducing the iron oxide mineral.The different approaches in this case essentially boil down to the following question: does one include the combustion heat of the reductant used in the reduction reaction or treat the reductant portion as just a reactant? Depending on the viewpoint, either approach can be considered acceptable. It is a matter of convention. There is a need, however, to select a standard approach because the absolute value of ‘energy requirement’ of an ironmaking process (e.g., the currently dominant blast furnace process) depends on such a choice. It is particularly important to clearly state the specific approach used when the energy requirement of ironmaking is compared with those of other industrial processes such as petrochemicals production."

Jan 1, 2014

By Chikabumi Yamauchi

The comprehensive scientific development of conventional industrial technologies stimulates the creation of new ones in the next generation. Prof. Akira Yazawa has just accomplished such an important work in the non-ferrous pyrometallurgical field. The results of his successful research are immortal. The research group of the author has conducted since 1985 fundamental studies on the application of sodium carbonate slag to copper fire refining. In the present paper, a calculation method for the distribution ratios of impurity elements between sodium carbonate slag and molten copper will be shown. The specific treatment by sodium carbonate slag will also be presented as an effective way for reducing each impurity content in the molten copper to 0.1 mass ppm, which is the level required for the production of high purity copper. The thinking-out of this evaluation method gets a hint from the Equation (2) in the text which was proposed by Prof. Akira Yazawa.

Jan 1, 2003