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By L. Becze, S. J. Hock, G. P. Demopoulos

"Regeneration of HCl from chloride solutions is commercially practiced by high temperature (800-900 °C) pyrohydrolysis associated with high energy consumption and capital cost. As an alternative to pyrohydrolysis a novel low temperature ( <200 °C) non-autoclave hydrolytic process has been studied in this research work, which comprises two steps. In the first step, ferrous chloride is oxidized by oxygen at 1;150 °C, followed by hydrolytic decomposition of ferric chloride to coarse hematite particles and superazeotropic hydrochloric acid (8-9M) operated at approximately 180 °C. This paper provides a summary of the laboratory results related to both oxidation and hydrolysis and presents a newly designed conceptual process flowsheet.IntroductionRecovery of base, noble and rare metals from ores and secondary materials (slags, dusts, residues) by chloride-based hydrometallurgical processes holds a lot of promise if a low cost HCl process becomes available. This is particularly so due to the high activity of HCl or more accurately activity of hydrogen ion [1] in concentrated chloride media and the formation of chlorocomplexes allowing for effective leaching under atmospheric leaching conditions and simultaneous ease of metal separation. However, during leaching significant amount of iron, which is associated with most of ores and secondary materials, goes into the solution. Hence, the obtained leach solution has to be treated to convert iron chlorides into easily filterable iron oxide and simultaneously produce concentrated hydrochloric acid. Apparently the critical operation of these processes is the regeneration of the lixiviant (HCl). Currently in the industry, its regeneration is accomplished by high capital and intensive pyrohydrolysis which operates at 700- 900 °C. Aimed at lowering the operational cost of pyrohydrolysis a process called PORI [2] was developed and tested in pilot plant scale in the 1970s for the purpose of treatment of pickle liquors without, however, resulting in industrial application."

Jan 1, 2011

By John ?gren, Martin Schwind, Henrik Larsson

"A new model for internal oxidation, as well as similar processes, has been implemented on computer. It is based upon a combination of random walk and cellular automata and is capable of treating 3-dimensional cases. To model diffusion, it utilises quantised units of matter. All steps of the process are included: nucleation, growth and coarsening. The effect of grain boundaries on diffusion as well as nucleation is taken into account. Further possible development is briefly discussed; especially the treatment of nucleation needs further consideration. IntroductionComplex diffusion-controlled processes may now be simulated on a routine basis when concentration varies along one co-ordinate only. One-dimensional simulations capture much of the information of interest but not all. For the case at hand, especially the spatial and the size distribution of precipitates, as well as the impact of grain boundaries, would be interesting information not accessible from 1-D simulationsSolving the full Fick-Onsager law in three dimensions does not seem feasible with the computers of today. In the model described in this article, random walk by quantised units of matter are considered. The model should be useful for a number of cases involving dispersed systems. With further development, it would indeed seem possible to simulate most types of phase transformations.Previous workWe have previously published two articles [1,2] on the new approach discussed in this work. In those articles we described the basic idea and showed, among other things, that very good agreement with an experimental concentration profile can be obtained, in a single-phase system, using independently assessed thermodynamic and kinetic data. Also, Schwind used the same random walk based concept to model coarsening [3]."

Jan 1, 2001

By Jana Dobrovska

Solidification and cooling of a continuously cast slab and simultaneous heating of a mould is a very complicated problem of transient heat and mass transfer. Nowadays, the solving of such a problem is impossible without numerical models of the temperature field not only of the slab itself, while it is being processed through the whole concasting machine (Caster), but of the mould as well. Two original numerical models have been developed and used in the investigation of a continuously cast steel slab. The first (one of two) 3D model of the temperature field of a concasting is capable of simulating the temperature field of a caster. Experimental research and data acquisition have to be conducted simultaneously with the numerical computation-not only to confront it with the actual numerical model, but also to make it more accurate throughout the process. After computation, it is possible to obtain the temperatures al each node of the network, and at each time of the process. The utilization of the numerical model of solidification and cooling of a concasting plays an indispensable role in practice. The potential change of technology-on the basis of computation-is constantly guided by the effort to optimize, i.e. to maximize the quality of the process. The user can therefore choose any appropriate longitudinal or cross-section of a slab and display or print the temperature field in a 3D or 20 graph whenever necessary. The second numerical model of dendritic segregation of elements assesses critical points of slabs from the viewpoint of their increased susceptibility to crack and fissure. In order to apply this model, it is necessary to analyze the heterogeneity of samples of the constituent elements (Mn, Si and others) and impurities (P, S and others) in characteristic places of the solidifying slab. The numerical model, based on measurement results obtained by an electron micro-probe, generates distribution curves showing the dendritic segregation of the analyzed element, together with the distribution coefficients of the elements between the liquid and solid states. The combination of both models enables the prediction of cracks and fissures in critical points of the continuously cast carbon-steel slab. Both models had been applied in the industrial investigation of a cast low-carbon-steel slab.

Jan 1, 2003

By Christopher Gammons

In developing countries throughout the world, gold ores are being processed by mercury amal-gamation, a technique long banned in the U.S. - unless a retort operation is used for mercury recovery - due to mercury toxicity and its effects on the environment. Amalgamation is a simple process that involves contacting a ground, slurried concentrate or ore with mercury in a slightly agitated vessel, usually for several hours, The amalgamated mercury is separated by gravity and then filtered through a fine cloth to collect the gold amalgam as a sponge, which is then fired to remove the final remnants of mercury and produce high quality gold. However, in Peru and other developing countries in South America and throughout the world, tailings are simply discarded into uncontrolled drainages and ponds and the sponge is fired in the open air. Clearly, in this case, environmental friendly and, to make matters worse, is typically conducted by family members of all ages without proper protection. Furthermore, the technique is inefficient, yielding approximately 50% gold recovery. For the past two years, faculty members from Montana Tech in Butte, MT, USA and the Universidad Nactonal del Altiplano in Puno, Peru have teamed to study the La Rinconada Mine Complex located in southern Peru approximately 100 kilometers north of Lake Titicaca and 25 kilometers west of Bolivia. The mining complex is over 5,000 meters above sea level and exists at the foot of a receding glacier in the Andes Mountains. A suite of soil and water samples collected in 2001 documented extensive Hg contamination in the Rinconada area [1]. The present paper summa¬rizes a follow-up investigation in July-2002, in which water samples were collected at numerous locations along the 200 km length of the Rio Ramis, from the Rinconada mine com¬plex to Lake Titicaca, In addition, we report new results of Hg analyses of fish from Lake Titi¬caca, The results of this study have relevance to safety and health concerns for the miners as well as people in downstream communities.

Jan 1, 2003

By John A. Clark, Danylo Oryshchyn, Casey Carney, Stephen Gerdemann, Cathy Summers, Thomas Ochs

"Limited analysis of combustion gas streams where carbon capture is not of interest is done mainly to ascertain operation parameters. Stringent regulations on acid gases and particulates promote careful flue gas analysis. Unregulated components are typically not analyzed. Typically not more than four points (two in the boiler, and one each in the flue and the stack) are sampled. A successful oxy-fuel process with carbon capture and compression is anticipated to require as many as 12 sample points with analysis for water, nitrogen, oxygen, argon, NOx, SOx, and carbon monoxide. Carbon dioxide captured for beverages produces a high value product and the cost associated with analysis is warranted. However, carbon capture for disposal must keep all costs to a minimum. This paper will compare alternative approaches for cost-effective sampling and analysis of the carbon dioxide product streams from oxy-fuel combustion, through all stages of production through compression and pipeline/vessel delivery.IntroductionAnalysis of gases in an oxy-combustion process with carbon capture is essential to the operations of the oxy-fired boiler and the subsequent collection, compression, and purification of carbon dioxide. The process is charged with pure oxygen and not-so-pure carbon in the form of coal at the front end, generating a product of mainly carbon dioxide with traces of argon, nitrogen, sulfur compounds, nitrogen compounds, oxygen, hydrogen, and mercury. It is possible that hydrogen chloride and hydrogen sulfide may also be present in trace amounts [1]. The trace components primarily come from impurities contained in coal such as water, sulfur, nitrogen, and volatile organic compounds. Coal also contains a good deal of mineral matter that is transformed into ash during combustion, becoming particulates that can complicate the analysis regimes utilizing standard analytical equipment."

Jan 1, 2010

By W. K. Connor, O&apos

The U.S. Bureau of Mines, in cooperation with the Idaho National Engineering Laboratory (INEL), conducted over 30 hours of melting tests to vitrify simulated low-level radioactive wastes from the INEL Radioactive Waste Management Complex (RWMC). Five separate waste compositions were investigated, each consisting of noncontarninated soil from the RWMC and surrogate materials used to simulate the actual buried wastes. The RWMC soil and five waste compositions were melted in a 50-lb, single-phase electric arc furnace with a water-cooled shell. These tests were conducted to determine melting parameters in preparation for a large-scale melting campaign to be conducted in the Bureau&apos;s 1-metric ton (mt), water-cooled-wall, 3-phase electric arc fumace. Bulk chemical composition was determined for each of the feed materials and for the slag, metal, fume solids, and offgas furnace products, and distributions were calculated for the key elements. The material balance for the furnace operation indicates that from 63 to 84 pct of the feed reported to the slag. Cerium, used as the surrogate for the radionuclides in the wastes, demonstrated an extremely strong affinity for the slag product. Although slag temperatures as low as 1250° C were recorded when melting the RWMC soil, temperatures in excess of 1600° C were necessary to achieve the fluidity required for a successful slag tap.

Jan 1, 1994

By Kenneth N. Han

Thermodynamic and kinetic aspects of nickel and cobalt leaching from metals. minerals and ores in various media have been reviewed and discussed in this paper. A kinetic model developed to delineate the leaching mechanisms for these metals has been discussed in view of experimental observations. The current review also includes the dissolution behavior of nickel and cobalt from various minerals such as oxides, sulrides. ocean floor manganese nodules, and laterites. A particular emphasis has been extended to similarities and differences of the dissolution behavior of these two metals in various media. The leaching of nickel as well as cobalt metal in acidic solutions and arnmoniacal solutions exhibits in most part mass transfer controlling. although at some pH&apos;s, chemical controlling or mixed controlling mechanisms seem to prevail. The leaching of nickel and cobalt from oxides in acids and ammoniacal solutions. on the other hand, can be described best by chemical controlling mechanisms.

Jan 1, 1993

By Adam J. Gesing

Eddy current separators are increasingly used by the auto shredder operators to produce higher grade of nonferrous metal concentrate for recycling. While this increases the unit price of the concentrate, metal losses through inefficient metal recovery quickly offset the price differential. We show how to optimize the eddy current separation system at the shredder to maximize mate- rial throughput, nonferrous metal recovery and grade of the nonferrous metal concentrate.

Jan 1, 1998

By K. Prashant Sarswat

Isotopes are critical to a variety of applications including physical science analyses, biology, medicine, pharmaceuticals, and national security. In most cases isotopes must be relatively pure or highly enriched before they become useful. Current isotope separation technologies are relatively inefficient, capital and labor intensive, and often produced by a limited number of suppliers. In the category of isotopes, lithium is among other important candidates. Lithium is found naturally in two isotopes, 6Li which accounts for 7.5% of all lithium, and 7Li which makes up the balance of 92.5%. Each of these isotopes is important to the nuclear industry. 7Li is often used in the form of lithium hydroxide which is used to control pH in pressurized water reactors. The current supply of 7Li is based mostly outside of the United States, and its long-term supply is uncertain. Apart from supply issues, the use of mercury for 7Li separation is also a concern in commercial processing using the most common and efficient approach [1–3]. Hence, a reliable, environmentally friendly, and efficient technique is needed to produce 7Li. In this line of investigations, the authors used a two-compartment system and significant separation was achieved. In this piece of research, some preliminary results are presented including cell design and actual isotope ratio after enrichment. Applying an electro-potential across two electrodes can be used to drive electromigration of Li isotopes. The electromigration is in addition to normal diffusion. Note that 6Li diffuses faster and hence there will be a lowering of the 6Li concentration near the positively charged electrode and an enhancement in 6Li near the negative electrode during the separation process. Similarly, 7Li will be more prevalent near the positive electrode and less prevalent near the negative electrode during the initial separation stage [1].

By Don Ibana

The use of solvent extraction (SX) in process metallurgy is particularly attractive as it is applicable to a wide range of solute concentration and pH, and it allows complete separation of chemically similar metals such as nickel and cobalt and the rare earths among others. It is therefore applicable to the processing of low grade and complex ores, which is increasing and expanding owing to the diminishing reserves of quality ores, and this has driven the increasing and expanding use of SX.The current SX technology, however, has inherent limitations owing to the use of mechanical agitation as it induces high shear mixing. Excessive shear produces very fine droplets, and while this favours mass transfer, it also leads to sluggish phase separation. High shear mixing is also known to favour crud formation. All these factors as well as high power and reagents consumptions contribute to poor process efficiency. Electrostatic solvent extraction (ESX) is similar to conventional SX except that mechanical agitation is replaced with electrostatic agitation. In direct contrast to mechanical agitation, it allows the production of very small droplets that can be made to maintain intense motion, which favours mass transfer, without affecting the phase separation. In addition, as it uses an electrostatic field, the power consumption is minimal. Hence, it promises to be a superior alternative to conventional SX mixing although an application of the technique is yet to be achieved.Our work to develop an application of the technique in process metallurgy has now established that electrostatic field has no effect on either the stability of the reagents or the chemistry of the process. A volumetric flowrate that is comparable to that of a conventional sieve plate pulse column is achievable. We have also established that electrostatic fields can be made to yield much narrower droplet size distributions than those of mechanically agitated contactors, and they allow better control of droplet motions, which include oscillation and linear motion and hence, mass transfer. These are significant advancements toward our goal and shall be discussed in this presentation.

By Flávia Paulucci Cianga Silvas, Otávio da Fonseca Martins Gomes, Viviane Tavares de Moraes, Denise Crocce Romano Espinosa, Jorge Alberto Soares Tenorio, Guilherme Apostólico Bortolini, Stoyan Gaydardzhiev

"Printed circuit boards (PCB) are particularly problematic to recycle because of the heterogeneous mix of organic materials, metals, and glass fiber. PCBs are found in almost every electroelectronic equipment and their recycling process involves a pre-treatment to separate the products which contain targeted metals. In this work, a physical processing involving sequential shredding and hanuner milling were used to obtain a comminuted sample from scrap printers PCBs. The thus prepared sample was analyzed for particle size distribution and by optical microscopy as well was subjected to pyrolysis, leachabilty and chemical composition determination by XRF. The metals concentration was determined by ICP and AAS. The PCBs have been also analyzed by SEM-EDS (micro-analysis and X-ray mapping). The results show that the studied PCBs are lead free, multilayer with 4 copper layers, have 45% of metals and the copper is present in significantly higher concentration than the rest of the metals.IntroductionThe global generation of e-waste (electrical and electronic equipment waste - WEEEs) grows at a rate of about 40 millions of tons per year [ l].Among this e-waste there are PCBs that are present in almost all electronic equipment. Their composition is heterogeneous and varies according to several factors, including: kind of EEE, when and where it was produced, fabrication technology [2], etc. In printers, the PCBs represent about 6.6- 8 wt.% [3].The PCBs treatment may include physical, pyrometallurgical, hydrometallurgical, ectrometallurgical and more recently bio-hydrometallurgical process. Normally there is a combination between these processes [2, 4, 5, 6, 7, 8, 9, 10].The diversity between the different PCBs composition complicates the recycling process since the composition of metal and others materials can vary according to the models. So characterization is an indispensable step before any processing of PCB to begin. Owing to the above said, the main goal of this work has been set to characterize representative samples of PCBs from printers through physical, chemical and microstructural analyses."

Jan 1, 2014

By Ole Rud Bendixen

Topsoe has developed a Wet gas Sulphuric Acid (WSA) process which effectively recovers SO2 in off-gases from non-ferrous smelters and roosters. The product is concentrated sulphuric acid of typically more than 96 wt% irrespective of SO, concentration in off-gas. The process does not generate any waste products or waste water and does not use any absorbents or other chemicals. In the process, up to 99.3% of the SO2 is converted catalytically into SO3, which reacts with water in the gas, hereby forming gaseous sulphuric acid. The acid is condensed in a WSA condenser of proprietary design. Excellent heat economy and practically no sensitivity to the water balance mean that no extra sulphur burning is required at any S02 concentration, The process is especially well suited for treating off-gases where the SO2 content is lower than approx. 5-6%, and it is a good alternative to a complete renovation of a smelter. However, also off-gas from flash smelter may be treated. The process has found good use in both molybdenum and lead roosters. An example from a molybdenum roaster in Chile shows that 97-98wt% acid is produced from a 2.3 % S02 gas. This plant is situated in the outskirts of Santiago and represented a major local source of SO2. The plan was started in May 1993.

Jan 1, 1996

By Mariana H. Staia

Thermodynamic calculations based on the free energy minimization method were performed for the system Ti-Fe-Mn-0-C1-C in order to evaluate the chemistry associated with the chlorination of an ilmenitic concentrate using CCl4. In the calculations various weight ratios of FeTi03/ CC14, a , were considered, which varied between 0.32 to 0.98 at temperatures ranging from 673 K to 1273 K , at atmospheric pressure. The results obtained indicated that the operating conditions for a process in a packed bed reactor, which implies the chlorination of both Fe and Ti, are 0.39 < a < .49 at T 1173 K.

Jan 1, 1993

By Milton Blander

"A review of concepts and theories for predicting thermodynamic solution properties of multicomponent high temperature liquid solutions is reviewed. During the last 50 years the ability to predict such properties for molten salts, silicates and metals based on the generally known properties of the lower order (often binary) systems has been developed and shown to provide predictions which are quite useful in science and technology. There are many gaps in our understanding of these high temperature solutions, especially for metals, and considerably more work is needed.INTRODUCTIONA number of solution theories and concepts have been developed which reliably predict the properties of multicomponent solutions from those of the lower order systems (often only the binaries). Because there is available data for a large fraction of the important binaries, the capability for making predictions for many multicomponent systems used in metallurgical separation processes is broad and potentially very useful. At the very least, the theories greatly minimize the data necessary for predicting properties of complex multicomponent solutions of molten salts, silicates and metals. It is the purpose of this paper to discuss the concepts which are demonstrably useful. We will discuss simple forms of the theories to make the concepts clear but we will refer to the publications which contain the more complex equations needed to treat the large majority of systems.A simple framework for understanding what we need to know in order to make technologically useful predictions is based on well known thermodynamic principles. In technologies and sciences where molten salts, slags magmas or molten metals are used or studied, one must often calculate the extent of a chemical reaction (or separation) or of phase changes. To do this, one must first write an equilibrium constant, K, for the reaction in terms of the standard free energy change of the reaction, ?G°."

Jan 1, 1996

By Shu Bin, Lin Chen, Tian-zu Yang, Wei-feng Liu, Wan-da Bin

"Antimony resources are rich in china, its reserves and productions are ranking the first in the world. The Chinese antimony mineral resources are mainly existed in the form of three types, such as stibnite, antimony-gold ores andjamesonite. The antimonial dust that produced from lead smelting process is an important secondary antimony resource. The different process that was adopted to extract antimony depends on the different raw materials. The process of blast furnace volatilization smelting is mainly used to treat stibnite and antimony-gold ores. But jamesonite is treated by the process of roasting-sintering-blast furnace smelting. And antimonial dust is treated in the reverberatory furnace. Many new technologies that are applied in these traditional antimony smelting processes play important roles, such as deleading agent, antimony white production, air-oxidation method, direct-blowing method, bath smelting technology, and so on. At the same time, the development of antimony smelting technology in china is prospected according to the requirement of the state environmental protection.IntroductionThere are five countries that produce antimony in the world, such as china, Tajikistan, Bolivia, Russia, and South africa, but China is the largest country of antimony production in the world. In the world, the antimony productions of 2008, 2009, and 2010 are 182,000 tons, 154,000 tons, and 167.000 tons respectively, but Chinese antimony productions are 166.000 tons, 140,000 tons, and 150,000 tons respectively. So Chinese antimony production was accounted for more than 89% of the world in 2010. It indicates that China have irreplaceable advantages in antimony resource and production all over the world."

Jan 1, 2013

By Metehan Erdogan, Furkan Özdemir, Ishak Karakaya, Mustafa Elmadaglı

Tungsten is mainly produced by H2 reduction of WO3 which makes its production difficult and costly. A promising method was recently reported for direct electrochemical production of tungsten from CaWO4 (scheelite) which is estimated as the seventy percent of the all tungsten reserves of the world. This paper investigates the application of pulse current in the electrochemical reduction of CaWO4 pellets attached to a current collector. The electrolyte was composed of calcium chloride and sodium chloride salts at eutectic composition (48 pct mol NaCl at 873 K). The reduced samples were cleaned with dilute hydrochloric acid solutions and characterized by X-ray diffraction and scanning electron microscopy. Examination of the results revealed that metallic tungsten was obtained by pulse current reduction.

Jan 1, 2016

By Jan Dabrovska

Solidification and cooling of a continuously cast slab and simultaneous heating of a mould is a very complicated problem of transient heat and mass transfer. Nowadays, the solving of such a problem is impossible without numerical models of the temperature field not only of the slab itself, while it is being processed through the whole concasting machine (Caster), but of the mould as well. Two original numerical models have been developed and used in the investigation of a continuously cast steel slab. The first (one of two) 3D model of the temperature field of a concasting is capable of simulating the temperature field of a caster. Experimental research and data acquisition have to be conducted simultaneously with the numerical computation-not only to confront it with the actual numerical model, but also to make it more accurate throughout the process. After computation, it is possible to obtain the temperatures at each node of the network, and at each time of the process. The utilization of the numerical model of solidification and cooling of a concasting plays an indispensable role in practice. The potential change of technology-on the basis of computation-is constantly guided by the effort to optimize, i.e. to maximize the quality of the process. The user can therefore choose any appropriate longitudinal or cross-section of a slab and display or print the temperature field in a 3D or 2D graph whenever necessary. The second numerical model of dendritic segregation of elements assesses critical points of slabs from the viewpoint of their increased susceptibility to crack and fissure. In order to apply this model, it is necessary to analyze the heterogeneity of samples of the constituent elements (Mu, Si and others) and impurities (P, S and others) in characteristic places of the solidifying slab. The numerical model, based on measurement results obtained by an electron micro-probe, generates distribution curves showing the dendritic segregation of the analyzed element, together with the distribution coefficients of the elements between the liquid and solid states. The combination of both models enables the prediction of cracks and fissures in critical points of the continuously cast carbon-steel slab. Both models had been applied in the industrial investigation of a cast low-carbon-steel slab.

Jan 1, 2003

By Gus Van Weert

Solvent extraction of iron from zinc refinery liquors has been investigated before, mainly on the MEHPA / HC1 stripping combination. Leakage of chloride into the zinc electrolyte and the costs of handling the ferric chloride eluate have prevented this option from being adopted. This work explores the stripping of the ferric loaded organic phase with nitric acid to take advantage of the possibility of regenerating up to 6N nitric acid, and clean spheroidal hematite production by autoclave treatment of ferric nitrate solution. The work was carried out with DEHPA (di 2-ethyl-hexyl phosphoric acid) in kerosine. Degradation testing proved the DEHPA to be very stable, when exposed to nitric acid solutions up to 6N and temperatures up to 70" C over a period of five days. Ferric iron was removed completely froma synthetic hot acid leach liquor, irrespective of the DEHPA concentration. Stripping the ferric turned out to be the problematic step. Although the stripping efficiency was considerable better at 50 than at 20° C, it decreased with increasing DEHPA/Fe ration in the organic phase. Eluates of no more than 5-10 g/l ferric nitrate were produced. surprisingly, nitric acid was found to be a less efficient stripping agent than sulphuric at equivalent normality and its efficacy levelled off above 4N. It was concluded that DEHPA does not appear to be the S.X. reagent to take advantage of the low cost autoclave decomposition of ferric nitrate opportunity in zinc hydrometallurgy and that another S.X. reagent, also resistant to nitric acid, but based on weaker compound formation is needed.

Jan 1, 1998

By I. G. L. Sinclair

The Selbaie deposit is located in northern Quebec. It is comprised of three distinct, but genetically related, Cu-Zn-Ag ore bodies which also contain economically significant amounts of Au. The deposits are Archean in age and volcanogenic in origin. At Selbaie, ore microscopy has been employed to aid in planning of ore beneficiation methods and to monitor the ongoing performance of the concentrator. Examples of both types of study are described. Early in the life of the mine, excessive amounts of Zn appearing were found to be appearing in the Cu concentrate. Microscopic examination of concentrates showed that this was being caused by the presence of coatings of supergene chalcocite on sphalerite grains. Fine coatings of supergene galena and chalcopyrite were also observed on some sphalerite grains. The presence of Ag and Au in the ores makes an important contribution to the revenue of the mine. The various modes of occurrence and mineralogical relationship of these two metals are described and discussed. Monitoring of the ongoing concentrating process at selbaie is done by qua-litative and quantitative examination of products collected at various points along the circuit. Causes of such problems as excessive loss of metals to the tailings or inefficient recovery of individual metals, can often be identified and possible solutions proposed.

Jan 1, 1989

By José R. de Tenorio

The aim of the present work was to investigate the reduction process of MnO~FeO-Si02 slags by carbon-saturated liquid iron. The effect of the initial Mn content in the bath was explored. The initial Mn content was in the range of 0 up to 40 wt. %. The MnO content in the slag was kept constant at 40 wt. %. Tests were performed in laboratory apparatus. Samples of slags and bath were taken. In the first 5 minutes, it was observed a very strong reduction of FeO. This first step promoted a MnO-Si02 enrichment of the slag and a formation of CO bubbles, which increases the slag level. The increase ofMn content decreases the MnO reduction rate.

Jan 1, 1996