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By J. M. Figueiredo, A. R. Silva, M. C. Coelho, R. M. Guedes

"With the continuous depletion of conventional sources of non ferrous metals, low grade complex sulphide deposits have been regarded as an alternative source of supply of zinc, copper, lead and also silver and gold. In spite of very important efforts in research in this domain it is still a long way to go in order to achieve reliable technological solutions both in ore dressing and metallurgical treatments which enable these complex materials to be regarded as commodities. The RLE process to treat bulk concentrates such as those obtained from portuguese ores, under development at LNETI and QUIMIGAL premises, combines experienced unit operations and innovative configurations and is an effective contribution for the future use of these materials. The results of three years of experimental work and main conclusions on the overall feasibility of the process are presented.IntroductionIn spite of the very well-known problems associated to the development of complex sulphide deposits, the economical importance of the enormous reserves of these materials, widespread all over the world, is so evident that its future use as source of supply of basic and precious metals and other minor elements is almost unavoidable.Critical steps in that direction are mainly concerned with favourable economical conditions and sound metallurgical practice for the treatment of nonferrous metals concentrates, which are nowadays still considered as non-conventional raw materials.Since Portugal is one of the countries where these orebodies occur more extensively, Portuguese authorities have dedicated since the beginning of the seventies, a big effort on finding economical and reliable processes for the recovery of copper, lead, zinc and also gold and silver, and for this purpose, several alternatives on ore dressing and metallurgical processing were studied, however without full sucess.Five years ago LNETI, a research laboratory, and QUIMIGAL, a chemical company, both state owned, decided to launch a research programme for the development of a metallurgical process for the treatment of NFM concentrates, which received financial support from NATO under its programme ""Science for Stability""."

Jan 1, 1988

By Neil Rowlands

Particle liberation studies are commonly used in the determination of the proportion of locked and liberated phases in ground ores at various stages of mineral processing. These studies may range from a qualitative assessment of a polished specimen in an optical microscope to a full quantitative analysis of the liberation characteristics of fine grained complex sulfide ores using scanning electron microscopy and high level image analysis. However, the conversion of quantitative data to meaningful information on a mill operations level is by no means a simple task. This paper reviews the errors inherent in the SEM/Image Analysis technique and looks at the various methods available to minimize errors in data collection.

Jan 1, 1992

By H. Sieber

Multilayer samples of tantalum and aluminum with the composition of Al-25Ta were prepared by cold rolling of elemental foils. The microstructure and phases were characterized by XRD, SEM and TEMISAED and the reactive phase formation was examined by DSC and DTA measurements in multilayer foils rolled for different deformation levels. The rolling procedure yields a decrease of the Ta particle size in the Al matrix and also results in the formation of a multilayer structure with a thickness of the elemental foils down to 200 nm in average. No phase formation is observed during the cold rolling procedure. While XRD and DSC measurements show no phase formation up to the melting of aluminum for samples rolled up to 40 F&R (fold and rolling) passes, in samples rolled for 50 or more F&R passes a first phase formation reaction yield an interfacial layer of TaAl3. Contrary to former studies in the investigated cold rolled Al- 25Ta multilayers the reaction starts at temperatures as low as about 340°C. The first stages of the reaction are associated with two exothermic maxima, that increase in amplitude and shift to lower temperatures with increasing number of F&R passes. At higher temperature the TaA13 reaction layer thickens very sluggishly and yields a third exothermic maxima at about 600°C. Isothermal DSC scans show the reaction is not finished for samples containing elemental particles larger than 1 pm after annealing at 550°C for 5h. In all the investigated samples no Al- Ta phase other than Tad3 was observed to grow for heat treatments up to 800°C. Multilayer samples heated up to 1400°C show a morphology consisting of small AITa2 particles embedded in a single phase TaA13 matrix. The multilayer microstructure and reaction product morphology are characterized by SEM and TEM investigations in cross-section and plan view geometry.

Jan 1, 1998

By Mitsuhiro Ito

"To allow various wastes containing high levels of chlorine to be used as alternative raw materials for Portland cement, two practical methods of chlorine removal were developed. In the first method, chlorine is extracted from the wastes during the cement manufacturing process. In the second, ash-dust waste with high chlorine content is first washed and then dehydrated to cake before being introduced to the cement manufacturing process. This cake can be used as an alternative for some cement raw materials. By combining the two methods, various wastes previously considered unsuitable for recycling due to their chlorine content can often now be used in cement manufacturing plants. As such, these methods represent a major contribution to environmental protection as well as a solution to problems relating to the diffusion of heavy metals and dioxins from cement plants.1. IntroductionWaste generation levels have risen rapidly in recent years. in both the consumer and industrial sectors and today, the need for effective, efficient waste management is one of the most pressing and serious problem of today's society.The Japanese cement industry has reacted to the increase in waste generation by using certain materials as alternative raw inputs or fuels for cement production, in an effort to contribute to society and conserve energy resources.These wastes often contain non-negligible levels of chlorine and heavy metals, however, both of which are unsuitable for cement production. Depending on the element content, Heavy metals have a particularly negative effect -on cement quality; in addition, they can be released into the environment. Chlorine, on the other hand, is contained in large amounts in incinerated ash from household wastes as well as in certain plastics. Both substances are considered impediments in cement-production, not only because they reduce the quality of the cement produced but also because they impair operating safety on cement production lines.To address this problem, two practical technologies have been established for separation and recovery of chlorine components during cement pre-processing and production. This paper introduces the application of these technologies with a special focus on incinerated ash from urban wastes, a representative form of waste material having notably high concentrations of chlorine, heavy metals, and dioxins. We also outline the technologies enabling this material to be used as an alternative input to cement production."

Jan 1, 2000

By Youqi Fan

Complicated copper oxalate precursor powder was prepared using ammonium oxalate as precipitating agent in the Cu(II)-C2O42--NH3-NH4+-H2O system. The composition and morphology of the powder are characterized by chemical analysis, X-ray Diffraction (XRD), scanning electron microscope (SEM), infrared spectroscopy (IR). The effects of temperature, copper ion concentration, pH value are investigated. It?s indicated by the experimental results that precursor of copper oxalate is prepared below a critical pH value, whereas the precursor turns to be a complicated copper salt combined with NH3 while over the pH value. Probable chemical formula CuC2O4?x(NH3)?yH2O can be assumed which x and y are relation to experimental conditions. Technological parameters, such as temperature, initial copper concentration and solution pH value, have significant effects on particle size, morphology and dispersion of precursor powder. By controlling certain technological conditions, various morphologies of precursor, pie shape, spindle shape and rod shape can be synthesized.

Jan 1, 2009

By Takayuki Watanabe, Yoshiki Shimizu, Yusuke Moriyoshi

"B-C-N nanotubes prepared by a flush evaporation method using a de arc plasma were mainly characterized by transmission electron microscopy (TEM) and electron energy· loss spectroscopy (EELS). The nanotubes obtained· were divided into three types such as carbon boron nitride and carbon or carbon nanotubes surrounded with boron nitride nanotubes. These types of nanotubes were obtained at higher temperatures than about 3000 K, however, these were not formed at lower temperatures than about 3000K. On the other hand, 11anocapsules were· formed at all the experimental temperatures and nanocapsules with a homogeneous phase were obtained at lower temperatures than about 3000 K. The effect of additives on the formation of B-C-N nanotubes was not clear. Based on these experimental data depending on temperatures and corresponding microstructures, the formation mechanisms of both nanotubes and nanocapsules were briefly .discussed 1 Introduction As reported previously, nano tubes have unique electrical properties1, 3) The preparations of nallotupes have been usually carried out by flush evaporation methods using either a de arc plasma or a laser4 -5) By these methods the reaction rate is so rarid that we have no data of intermediate products between initial raw materials and. final products of nanotubes 6-9). So, the formation mechanisms of nanotubes have been mainly speculated only from the microstructures of resultant nanoiubes. In order to have more reliable formation mechanisms, it is particularly important to have the information of intermediate products at the corresponding temperatures. From the viewpoints, we have studied about the effects of temperatures on the preparation of nanolubes. Here we report mi firstly some problems on the preparation of B-C-N nanotubes 10), secondly the effects of temperatures on the preparation of B-C-N nanotubes, and finally the formation mechanisms of nanotubes."

Jan 1, 2000

By O. Nakai

In the copper electrorefining process, the quality of the starting sheet is one of the basic factors for producing high quality copper cathodes. A highly automated and advanced facility for the production of copper starting sheets was constructed at the Toyo Copper Refinery in 1992, bringing various improvements into an automatic stripping system using stainless steel mother blanks. In 1998, the refinery expanded the tankhouse by another 128 commercial cells, and introduced 64 polymer concrete cells in a first stage conversion. As a result, the Toyo Copper Refinery now has the capacity to produce 103,200 t/y of cathode copper. Construction has led to great improvements in the materials handling facilities and computer associated short-circuit detection technology. This report summarizes the improvements made in the quality of the cathodes and in plant productivity.

Jan 1, 1999

By Bernhard J. Ralph

In refractory gold ores much of the gold occurs in sub-microscopic form in sulfide minerals, most commonly pyrite and arsenopyrite Bacterial leaching is being developed as a pretreatment for these minerals to aid the liberation of gold and a variety of extracting reagents. This paper reviews the nature of the principal micro-organisms involved, the effects of various physico-chemical factors on the rate and extent of extraction, and likely mechanisms involved.

Jan 1, 1989

By Bohumír Cech, Jirí Hanika, Václav Veselý

"PET bottles are separated and subsequently crushed into flakes. Except for PET, these flakes contain PE, PVC, paper, adhesives, beverages remainders and mineral impurities. PET itself usually is a glycol and terephthalic and isophthalic acid polymer.The suggested method consists in PET flakes crystallization at 255°C. In the meantime, volatile substances evaporate and PVC disintegrates. Formed crystalline PET is crushed into small particles and then is subject to the basic hydrolysis at an atmospheric pressure. In addition to lye solution, glycol is added in the hydrolysis. Water is eliminated by boiling, which gives rise to suspension of sodium salt of terephthalic acid and glycol. The suspension is skimmed and the filtered glycol is vacuum distilled. Pure glycol is then the distillation product.Crystals are dissolved in water and the solution is filtered, which eliminates PE and impurities. Electrodialysis removes pure terephthalic acid salt from the solution. Glycol solution is returned to the hydrolysis. Terephthalic acid is precipitated by a mineral acid. Subsequently, it is washed and dried. The filtrate is separated through electrodialysis to lye and acid. The lye gets back to the hydrolysis and the acid is used for precipitation. Terephthalic acid and glycol are products in a “polymer grade” quality. The waste is a part of washing waters, distillation residues after glycol regeneration and a filter cake after the terephthalate solution filtration."

Jan 1, 2008

By Jack S. McPartland

Historically, research on thiosulfate leaching of precious metals ores has been focused on processing of difficult to treat ores. Thiosulfate leaching of ores and concentrates containing sulfide minerals, copper, manganese and preg-robbing carbon constituents has been evaluated. Cyanide leaching is generally considered an efficient, environmentally acceptable means for processing of non-refractory precious metal ores, Consequently, commercial processing of finely disseminated, oxidized precious metal ores is normally accomplished using alkaline cyanide leaching. Recent changes in regulatory climate have, however, called into question the acceptability of cyanide leaching in a number of locations worldwide. In some cases where the use of cyanide is being questioned, thiosulfate leaching may provide an acceptable alternative. Developments in thiosulfate leaching of precious metal ores are reviewed in this paper.

Jan 1, 1999

By Patrick F. Mahoney

Each year in the United States over 10 million tons of metal are discarded with our municipal waste. This, includes, not only ferrous metals, aluminum and copper but gold, silver, platinum and every other precious metal. Resource recovery, as an approach to waste management, is replacing disposal and it presents great opportunities for those in the metal refining and recovery industry. Combustion of waste enriches the metal fraction left in the ash to the point where metals can be efficiently recovered. The recovery and quality of metals can be enhanced by good combustion control. Innovative technology is needed to efficiently tap this generous, and renewable mine.

Jan 1, 1995

By Batric Pesic

Adsorption of gold on activated carbon from gold bromide solutions was examined as a function of pH, particle size, carbon amount, initial gold bromide concentration, bromine concentration, temperature, and various cations and anions. pH did not have any effect below pH=6. Above pH=6, pH had dramatically negative effect. The adsorption results satisfied a first reaction order model. The reaction rate constant was proportional to the inverse of carbon particle radius. It was also proportional to the amount of carbon, and independent of initial gold concentration. Temperature had a very little effect at pH=l. At pH=8, the activation energy was a function of the extent of a reaction, increasing with the extent of a reaction. Cu, Fe, Ca, Mg, and Na cations and sulfate, chloride and bromide anions did not have any effect on gold adsorption. Bromine had a very negative effect on gold uptake.

Jan 1, 1991

By R. H. Eric, P. Taskinen, A. Bhalla, P. Halli

Sustainable development requires less energy consumption with lower carbon footprint. In this review the solid state reduction behaviour of three oxide ores using methane gas are briefly summarized based on experimental work conducted in our laboratories. The discussion concentrates mainly on mechanisms of the reduction studied through SEM-EDAX and X-ray diffraction techniques. Limited preliminary kinetic input is also mentioned. Iron ore containing titanium and vanadium could be reduced significantly in the solid state with methane-hydrogen mixture up to 400 °C lower than is needed in ordinary solid state carbothermic process. The reduction of chromite and manganese ores were possible similarly at lower temperatures with potential energy savings lower carbon footprint.

Mar 1, 2017

By Zhou Jiemin

A mathematical model is developed to determine the economic thicknesses of refractories and insulations in rectangular furnaces, Both the heat loss cost and the lining investment are taken into account to achieve a minimum operation cost. For the sake of calculating the heat flux, the paper is particularly concerned with the simulation of the three-dimensional transient heat conduction processes in the lining and a Douglas-Rachford method is used to solve the finite difference equations, The model has been used to design an industrial electric resistance furnace operated periodically. the values of temperatures and power consumption measured from the furnace correspond with the model results.

Jan 1, 1991

By C. Dresen

This paper discussed the reaction kinetics of the reduction of industrial phosphate pellets for P4 production. In the reduction process of various phosphate ores, the following parameters were investigated: Diffusion of the phosphorus oxide and other gaseous products from the reaction mixture after having been reduced on the reductant (coke) surface. Influence of silica on reaction kinetics. Temperature influence. Influence of mineralogy and morphology (different ores). Particle size influence of silica and coke. Experiments were carried out in a vertical tube furnace with 2 ores, 2 types of silica and one type of coke. Selected experimental conditions simulated furnace conditions. The following conclusions could be made: Reaction rate increases with the addition of SiO2 into the pellet. The reaction rate increases above 1350°C (melting temperature of the slag). Mixing different ore types in the pellets leads to differences in reduction kinetics. Particle size of the coke particles influence reduction kinetics. The amount of slag formation is influenced by silica addition, coke size and temperature.

Jan 1, 2002

By Richard D. Hagni

Ore microscopy is a useful technique to detect and study the ore minerals that are associated with sediment-hosted and volcanic-hosted deposits of finely disseminated gold and silver. Ore microscopy can be used to determine the: 1) precious metal-bearing minerals in some ores, 2) associated ore minerals that may form geochemical exploration halos, 3) character of iron sulfide grains, 4) extent of sulfide oxidation, 5) character of oxidized iron minerals, 6) character of original sulfide grains from a study of the hypogene and supergene oxidized ores, 7) relative time of oxidation, 8) character of organic matter, 9) minerals that may consume excessive amounts of cyanide solution, 10) extent of silicification and silica encapsulation, and 11) possibility of salting.

Jan 1, 1987

By Shabnam Sabah, Geoffrey Brooks

In oxygen steelmaking, splashing and droplet formation play a key role in the kinetics of the process. Though splashing has been studied by previous investigators, there is only limited understanding of how different cavity modes affect splashing. Therefore, a cold model study (at various lance heights and gas flow rates) has been carried out focusing on the issue of cavity modes and how it affects splashing phenomenon. Analysis using Fast Fourier Transform (FFT) was carried out on cavity oscillation that showed that frequency and amplitude of oscillation was highest in penetrating mode. Measurements of splashing over a range of conditions showed splashing greatly reduced when cavities went from splashing to penetrating mode. The results were validated and compared with plant data and previous model investigations.

Jan 1, 2014

By M. E. Coleman, G. Money

"Clyde Materials Handling is an established customer-driven solutions provider, which utilizes its knowledge, expertise and technologies to transform the production processes of its customers, who operate in the ferrous and non-ferrous metals industries.With over 30 years experience in the process improvement industry, Clyde Materials Handling has helped their global customer base transform the way in which they operate their processes, which has enabled them to generate sustainable economic benefit and maintain their positions as leaders in their respective markets.Clyde Materials Handling has supported operators within the metals market by developing and deploying pneumatic conveying and pneumatic injection technologies. These environmentally supportive and sustainable solutions have been used to transport raw materials within operating facilities, from storage to silo, as well as injecting these materials directly into the heart of production processes.Clyde Materials Handling has worked closely with their customers, such as Codelco in Chile, where their pneumatic solutions have been used to inject a consistent, pulseless and accurate flow of copper concentrate into a bath smelter, which has helped to fuel the operational capacity, availability and productivity.This paper will discuss and highlight the ways in which pneumatic injection technologies, created by Clyde Materials Handling, and applied in partnership with their customers, have helped to improve the operational performance of the production processes of operators across the non-ferrous metals markets with specific reference to applications in the Peirce Smith Converter.Clyde Materials Handling has applications injecting Electronic Scraps, Dusts, Reverts, and other additives to the Peirce Smith Converter. They also have experience of modified PS Units used for Slag Cleaning. There experience with the Codelco Teniente Converter is also directly related to this area of operation."

Jan 1, 2009

By Massoud Hassanabadi

Filtration using Ceramic Foam Filters (CFFs) is a method widely used to separate inclusions from molten aluminium. In the present work, the specific permeability and form drag coefficients of nominal 50 mm thick commercial Al2O3- based CFFs, of grades 30, 50, 65 and 80, have been calculated from pressure drop experiments using high (60–500 mm s−1) and low (0.2–10 mm s−1) water velocities. Moreover, 2D axial symmetric Computational Fluid Dynamic (CFD) models have been developed, using COMSOL Multiphysics® to validate the experimental results. The empirically obtained values were defined as global parameters used to model the pressure, as well as the velocity fields in the water pipes and in the CFFs. The modelled pressure drop over the filter thickness for the high water velocity experiments showed < ± 1% deviation from the corresponding experimental results for all CFF grades. Moreover, the developed model also showed good agreement with the experimental results obtained from the low water velocity experiments, where the deviation of the pressure drop for the CFF samples of grade 30, 50 and 65 were ≤ ± 4.6% and for CFF samples of grade 80 ≤ ± 13.4%.

By Yusuke Kimura, Ken-ichi Yamaguchi

"Secondary materials have long been processed at the S-furnace of the Mitsubishi continuous copper smelting and converting process at Naoshima Smelter and Refinery. Intensive recycling in the recent years has formed concerns that impurities in the secondary materials may cause drastic changes in the chemical properties of the CL-slag, which is separated from matte in the smelting stage. Among various impurities included in secondary materials, the authors have studied the influences of sodium oxides in the CL-slag because the behavior of sodium oxide has scarcely been studied with respect to the copper smelting slag. The examinations have been applied experimentally on the distribution between slag and matte of arsenic whose acidic characteristics suggest strong affinity to sodium-oxide of basic characteristics in silicate melts. The results have been discussed by thermodynamic evaluations and the results of pyro-tests at the commercial furnace.IntroductionAt Naoshima Smelter and Refinery, the existing line of the Mitsubishi continuous copper smelting and converting process has been operated since 1991. The Mitsubishi Process consists of three furnaces namely the S-, CL- and C-furnace as shown in Figure 1. In the S-furnace, copper concentrate and powdery secondary materials (scraps, sludges, etc) are charged through the top lances with oxygen enriched air. The other secondary materials of lumpy shapes are charged through the chute installed on the furnace roof. Charged materials are smelted by the reaction heat in accordance with the oxidization of copper concentrate. The mixed melt of matte and slag overflows through the launder into the CL-furnace, where the melt is separated into slag and matte by the difference of their specific gravity. Matte is siphoned out and sent to the C-furnace and converted to blister copper continuously. The CL-slag overflows continuously through the slag outlet to be water-granulated. Granulated slag is sold as a raw material used for the cement production and so on. Various secondary materials have been processed at the S-furnace of Naoshima Smelter and Refinery. Intensive recycling in the recent years has formed concerns that the chemical properties of the CL-slag may change drastically due to impurities originating from secondary materials. Among various impurities included in secondary materials, the authors have studied the influence of sodium oxide in the CL-slag because the impact of sodium oxide has scarcely been studied with respect to the copper smelting slag. The examinations have been applied experimentally on the distribution between slag and matte of arsenic whose acidic characteristics suggest strong affinity to sodium-oxide of basic characteristics in silicate melts."

Jan 1, 2012