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By Torma A. E.

Biotechnological processes are considered to be cost effective especially for situations where the recovery of metals from 'Very large volumes containing trace metal concentrations (less than 10 ppm) is concerned. Microorganisms, alive or dead, or their products can be highly efficient and selective biosorbents for metal concentration. It is important that the metal bound to the biosorbent can be stripped by suitable agent(s) and regenerated for repeated use. The stripped solution should be concentrated enough to be introduced into the common metal recovery circuit. The industrial acceptance of biosorption processes is dictated by increased competitive advantage over other processes. This paper reviews the pertinent literature?, regroups the information, and points out future possibilities for the mineral and metal processing industries.

Jan 1, 1992

By Heikki Tuovinen

The total utilization of raw materials and energy is the most important criterion when planning. industrial processes. The main goal is clearly to use the raw materials and energy as effectively as possible in order to make the desired products directly in the primary process itself', or to recycle unused materials and energy either as such, or after cleaning back into the process. However, few industrial processes are so straightforward. Most processes generate by-streams of materials and energy, which cannot be recycled directly and it is namely these by-streams which tend to remain as wastes. These by-streams are slags, dusts, vaporized metals, liquids, slurries, sludges, gases etc. Most base metal processes produce all these by-products. Waste water and gas emission controls and regulations are tightening all the time, so new processes must be developed to keep pace with these requirements. These processes generate more solid wastes, which must be utilized or at least processed into a harmless form landfilling. Municipal and hazardous wastes also contain valuable materials and energy, which must be used to minimize landfilling. The development of processes for these purposes places even greater demands on research and development. The same principles and methods developed for mining, ore dressing and metal refining processes can also be adapted for research and development work on processes for waste minimization. However, the problems encountered are much more complicated and less familiar, demanding more versatile and accurate tools and equipment. This paper presents principles, examples and some references of R & D work on processes for waste minimization.

Jan 1, 1992

By John W. Ahlrichs

Microscope, electron microprobe and x-ray diffraction have been used to provide quantitative evaluation of products from the mill, smelter, refinery and other metallurgical processes. Phase compositions and their quantities are necessary for an adequate understanding of the various products obtained throughout an operation and in laboratory testing. By careful evaluation, important information can be gained in improving recoveries and increasing grades at various stages of processing. Four case histories are discussed in this paper. Quantitative microscopic counting techniques are applied to mill products to determine degrees of locking and liberation of the economic minerals. Rapid, but accurate evaluation aids the metallurgist to develop or improve the grinding and flotation circuits. In the smelter, the identification and quantification of the phases are important for predicting reaction mechanisms and kinetic trends. Mineralogic techniques have been applied to conventional smelter products, and to those obtained in laboratory tests for newly developed innovations to smelting. Small, but important, values of gold occurrences in ore are difficult to determine. Evaluation of gold usually requires special separations into various mineral concentrates, followed by assays and mineralogic determinations of the products. Numerous occurrences of solid solution constituents can be treated as by-products, but often they are deleterious to metallurgical treatment. Most solid solution problems can be unraveled by the mineralogist's tools.

Jan 1, 1981

By D. B. Dreisinger

The zinc pressure leach process developed by Sherritt Gordon, Ltd. permits the direct leaching of sulphide concentrates according to the overall reaction, ZnS +H,zS04 +402.+ZnS04+H20 +S0 The kinetics of the leach are affected by three rate controlling steps; ( l) oxygen mass transfer from the gas to the leach solution, (2) homogeneous oxidation of ferric ion to ferric ion by dissolved 011.ygen and (3) ferric ion leaching of zinc sulphide in the presence of a sulphur dispersing detergent (lignin sulphonic acid). Fundamental studies have been conducted to identify the factors that influence the kinetics of each individual rate controlling step. Oxygen mass transfer studies have been directed toward optimization of the agitator configuration for solids mixing and gas pumping from the atmosphere above the leach slurry. The rate of ferrous oxidation by molecular oxygen and the rate of zinc sulphide leaching by ferric ion have been studied over a wide range of temperature and solution compositions. The study of zinc sulphide leaching by ferric ion was supplemented by a series of interfacial tension measurements in the liquid sulphur - zinc sulphate solution system. The various kinetic studies have been summarized in terms of the importance of each rate to the performance of the process.

Jan 1, 1990

By Elizabeth Carvalho L. Cardoso, Ademar B. Lugão, Sandra R. Scagliusi

This research investigated how gamma-radiation affected PP/HMSPP structural foams filled with biodegradable synthetic polyester PLA in terms of thermal properties, biodegradability and infrared spectrum. Polymers are used in various applications providing enormous quantities of wastes in environment and contributing with 20–30% of total volume of solid residues. Besides, shortage of plastics resins obtained from fossil base is addressing research and development toward alternative materials; environmental concerning in litter reduction is being directed to renewable polymers for manufacturing of polymeric foams. Biodegradable polymers, a new generation of polymers produced from various natural resources, environmentally safe and friendly, can contribute for pollution reduction. PLA (poly(lactic) acid)) was chosen to be blended with PP/HMSPP. Blends thereof were subjected to gamma radiation at 50, 100, 150, 200 and 500 kGydoses.Soilburialtestpointedtowardapartialbiodegradationofirradiated PLA-PP/HMSPP foams; other characterizations involved TG/DTG technique and FTIR assessments.

Mar 1, 2017

By Moto Goto

Onahama Smelter of Onahama Smelting & Refining Co., Ltd. has two green- charge reverberatory furnaces; the old furnace was constructed in 1965 and the new one in 1973. This paper discusses the use of oxygen-oil burners in a green-charge reverberatory furnace and also compares the copper loss in slag between the two furnaces at Onahama Smelter. During the past ten years of operation, no shutdowns of the old furnace were necessary and the smelting capacity was increased by 25% by the use of two oxygen-oil burners. These burners are suitable for a green-charge reverberatory furnace to in- crease the smelting capacity without causing an increase of the exhaust gas volume and refractory erosion. After two years of operation of the old furnace, a bottom build-up in the charging zone of approximately 50 centimeters was experienced, and this build-up has stayed at this level since then. In 1973, a new additional reverberatory furnace was put into operation. Copper content in slag of the new furnace was lower by approximately 0.15% than that of the old one during the first several months after the start-up. Investigations were then made on the effect of the bottom conditions in the charging zone on the copper content in slag.

Jan 1, 1976

By F. Baldini, M. S. Borges

"The proposed method emphasizes the optimization of waste management with regard to the exploitation of raw materials incorporated in the remains of industry, as well as the economics of natural resources as an environmental impact assessment. This system [tool] allows: (a) the conversion of an environmental liability into an asset by finding a line of appropriate research for each type of waste and the development of new materials applicable to other industries, (b) the performance of internal control of the waste generated (production, storage, final destination) as well as legal conformity.Objectives:1.1 General objective:To design a collaborative system for socio-environmental management of industrial waste.1.2 Specific objective:Develop evidence of concepts;Evaluate the deployment of the inventory of waste in an industry;Enable the conversion of an environmental liability into an asset by finding a line of research appropriate to the waste: a case study;Evaluate the environmental legislation in the legal mechanisms that influence company decisions.IntroductionThe global economy is undergoing major changes, among these changes; it should be highlighted those related to technological progress and environmental quality.While the industrialized countries and higher levels of economic growth dominate modem technology, developing countries are identified by a different growth pattern, using the annual growth rate of Gross Domestic Product per capita [3, 18].Growth is when the GDP grows, in percent, over the previous year. Development, on the other hand, is when the countries change their technologies and improve their internal structure. Thus, the growth considers the accumulation of wealth, while the development is concerned with the distribution of wealth, improvement of the quality oflife and environmental quality [3, 18].As the UNESCO report shows (1999), the biggest problem is between consumption and development, what is produced and the end that is given to the product. Therefore, product and by-product have equal importance in the quantity produced [29].On one hand there is a positive relationship between indicators of economic growth and technological progress, however, on the other hand, these transformations are a paradox, confirmed by the dramatic use of environmental resources and the lack of technologies for recycling of industrial scrap."

Jan 1, 2011

By Zhao Hengxian

We studied the phase diagram of Na3AlFe-ZrO system, reduction of ZrO2 by aluminium and electrochemical behaviours of ZrO2 in the system. The results show that Na3ALF6-ZrO2 system is a simle eutectic one, that the velocity of reduction of ZrO2 in the system is rapid al 960'C and that the Zr content in the alloy abtained can reach as high as 2.5wt%. Potential scanning shows that there exist new current peaks on the potential scanning plats except for the cuurent peaks corresponding to the oxidation of aluminium. The method of making Al-Zr alloy in our paper has advantages over the traditional method of mixing metals.

Jan 1, 1992

By Bowen Li, Canhua Li, Mingsheng He

Steelmaking slag is a by-product in considerable volume and a valuable material for various applications. In general, steelmaking slag is an alkaline compound of CaO, Fe2O3, and SiO2. However, its characteristics varies depending on the feedstocks, steelmaking process and cooling method of the slag. To utilize this by-product effectively, this study investigated the characteristics of steelmaking slags taken from Wuhan Iron & Steel Co. Ltd. The results showed that the slags mainly consist of the oxides of calcium, iron, and silicon, with low contents of magnesia, alumina, and manganese oxide with a feature of high alkalinity and lime saturation factor. The major mineral phases include belite, calcium ferrite, calcium hydroxide, wustite, quartz, and small amount of elite. Thermogravimetric analysis indicated the weight loss from ambient temperature to 800 °C is 8% in total. Melting test showed the glass transition temperature is between 1300 and 1350 °C, flow temperature is about 1400 °C. The slag samples investigated in this study can be considered as a typical glass-ceramic composite.

Mar 1, 2018

By Alice Barreto Bevitori, Felipe Perissé Duarte Lopes, Denise Cristina Oliveira Nascimento, Sergio Neves Monteiro, Isabela Leão Amaral da Silva

"The piassava fiber is one of the most rigid natural lignocellulosic fibers, which has since the last decade been investigated as possible reinforcement for polymeric composites. In the present work, the tensile properties of polyester composites reinforced with piassava fibers with thinner diameters were investigated. Composites with volume fractions up to 30% of continuous and aligned piassava fibers were tensile tested at room temperature to evaluate the ultimate strength, elastic modulus and total strain. For each volume fraction, individually separated fibers with the smaller diameters were tested. The results indicated that the tensile properties tend to improve with increasing volume fraction of the thinner piassava fibers. The role played by the fiber/matrix interaction was analyzed by scanning electron microscopy.IntroductionA significant change in the transportation sectors mainly the aerospace and automotive, occurred last century with the introduction of stronger and lighter materials. The most relevant example was the polymer composite reinforced with synthetic fiber. They are nowadays replacing conventional materials such as the aluminum alloys in airplane body owing to superior specific strength. in recent years, however, environmental problems in a global scale are imposing a reversion in the use of synthetic fiber specially the glass fiber. In spite of its higher specific strength, this fiber and its polymer composites can neither be recycled nor incinerated in a thermal plant to generate electricity [1]. Moreover, the fabrication, processing and transportation of a glass fiber composite are associated with C02emission, the major responsible for global warming [2].A possible substitute for glass fiber without the above-mentioned environmental problems, could be a natural fiber. In fact, natural fibers obtained from cellulose-rich plants, also called lignocellulosic fiber, are already being used in several engineering fields, particularly the automobile industry [3-6]. Figure 1 illustrates an automobile and its many components made of lignocellulosic fiber composite [7]."

Jan 1, 2011

By G. Mark Aylmore

Various processes have been developed using a combination of elevated temperature and chemical treatment processing to recover Li from silicate minerals. To facilitate further process development, a comprehensive understanding of the deportment of Li and associated minerals in ore bodies is essential to allow the industry to predict the response of ore reserves to metallurgical treatment options. This paper describes results from the integrated use of the John de Laeter Centre’s state of the art analytical and mass spectrometry techniques to characterise a selection of Li bearing ore bodies and determine their amenability to potential processing options for the extraction of Li. The mineralogy, mineral associations, and liberation characteristics of ore-bearing and gangue minerals were characterised using a combination of the TIMA and XRPD studies. The Li content and distribution within minerals were defined using LA-ICPMS and field emission scanning electron microscopy techniques (EBSD, ToF-SIMS) and atomic probe microscopy.

Proposed by outstanding electrochemist and electrometallurgist Prof. Raphael Agladze (191 1- 1989), process of copper and manganese co-electrowinning was enhanced to the pre- electrowinning stages: low,temperature co-leaching of copper and manganese containing materials, and to high-temperature co-roasting of the same materials with consecutive leaching. The report presents results of experimental investigations of the processes mentioned above, as well as results of thermodynamic investigations of co-roasting processes, and co- leaching processes computer modeling.

Jan 1, 1997

By Qiang Zhong, Bin Xu, Qian Li, Wei Gao, Yongbin Yang, Yaxuan Wang

Lump coal with high volatility is used for providing heat and reductive gas, and ensuring permeability in COREX. However, it is apt to be pulverized in transport and storage process. Therefore, comprehensive utilization of the pulverized coal to produce coal briquettes with appropriate binders is significant, among which the molasses binder cannot meet the technological requirements. In this paper, coal tar pitch binder and BJ additive were used in briquetting and carbonizing process of coal powder. The results showed that BJ effectively activated cold state cohesiveness of the pitch and make it bond the coke particles to a firm briquette at room temperature .Carbonizations of coal and coal tar pitch achieved obvious constriction and formed a carbonized skeleton. The drop resistance of wet briquettes reached over 50 times/1meter. When cured at 1000 °C for 1h under nitrogen atmosphere, the compressive strength of carbonized briquettes came to 6.43 Mpa.

Jan 1, 2016

By F. Kongoli

Viscosity is an important parameter of copper smelting and converting processes. It affects the settling of matte or metal droplets in the slag, distribution of elements etc. Despite this importance, confusion exists on the viscosity of copper smelting slags as a result of disagreements found among the measured viscosity data of several authors especially in the slags of high ferric iron content and close to magnetite precipitation. In this work a critical review of the existing data on the viscosity of copper smelting slags has been first carried out and the effect of oxygen potential on the viscosity of copper smelting slags has been clarified through a coupled quantification of viscosity and liquidus temperature. The confusion in the literature has been clarified and the importance of the relation between the viscosity and the liquidus temperature is discussed.

Jan 1, 2003

By Reza Kamali, Mohsen Bashiri, Hadi Fanisalek

"Half of the input energy to aluminum reduction cell will be lost as waste heat which could be studied for possible recovery. Since price of energy is increasing and the main production cost in primary aluminum industry is energy, so waste heat recovery consideration will be interesting. One of the possible choices for recovering is from aluminum exhaust gases that needs minimum modifications for reduction cell and has no influence on cell heat balance which is vital for the operation. By using heat exchangers with in-line and staggered tube arrangements which placed before fume treatment plant (FTP) we will be able to recover enough amount of heat. The main challenging problem which is necessary to overcome will be the heat exchanger material and its design because of corrosive and dusty exhaust gases from potroom. In this paper, a desalination system with six effects of evaporator is proposed for producing distilled water by using recovered heat from hot exhaust gases. The calculated amount of produced distilled water is around 27,000 / in this specific suggested desalination plant. The suggested desalination plant is based on Hormozgan Aluminum Company data (Hormozal) in Bandar Abbas, Iran which is constructed by the Persian Gulf.IntroductionWaste heat losses arise both from equipment inefficiencies and from thermodynamic limitations on processes. The exact quantity of industrial waste heat is poorly quantified, but various studies have estimated that as much as 20 to 50% of industrial energy consumption is ultimately discharged as waste heat [1]. In order to achieve a final decision for establishing the waste heat recovery plant in any type of industry, a strong feasibility study is mandatory. Also, we need to remember that the possible amounts of energy and suggested process plant for recovery have to be investigated before starting any feasibility study. This kind of study which is important to be finished before moving to feasibility step is mainly a theoretical study, and was done for the Hormozgan Aluminum Company (Hormozal). In addition to the exhaust gases from the potroom, the exhaust gases from anode baking plant appear to have a better potential for waste heat recovery compared to potroom exhaust gases. The average temperature of exhaust gases from anode baking kiln is 120°C higher than the exhaust gases temperature in the potroom. This needs further investigation in a different study, because this study is just focusing on potroom exhaust gases."

Jan 1, 2011

By Ahmet Haxhiaj, Jaroslaw Drelich

"Both composition and porosity of pellets are the main parameters influencing the reductive melting process in water-jacket furnace during the roasting of sulfide lead concentrate. Roasting in a smelter located in Trepçë is done at about 9000C, for pellets which are composed of PbS, CaCO3, Fe2O3, and SiO2. In order to faciltiate the formation of slag in the reductive melting, the pellets must have the proper content of CaO, SiO2, and FeO, and porosity. The plant’s practice indicates that pellets with porosity of 18% do not melt adequately in the water-jacket furnace. The optimum porosity for the proper melting of pellets needs to be 32-40% and can be achieved when pellets are loaded with more than 10 wt.% CaO. Pellets with less than 10% CaO have a limited network of pores, such that reactive gases cannot reach the entire ore structure. Also, the composition of the pellets must satisfy the ratio of CaO : SiO2 : FeO = 1 : 1.2 : 1.8 to facilitate the formation of slag in the reductive melting process.IntroductionAgglomeration roasting of sulfide lead concentrate is an important phase in the production of lead by reductive melting [1-6]. The reductive melting process is a complex process with contradictory effects of several technological indexes which many times are hard to measure and determine. In this process, loading the water-jacket furnace with pellets of optimized composition and structure can reduce the consumption of coke, and achieve high level of lead recovery. Pellets (agglomerates) should be porous, but at the same time they should have necessary mechanical strength. ‘Self-melting’ ability of pellets is controlled by the types and quantities of fluxes blended into the pellet composition. Three major additives and their role are:"

Jan 1, 2011

By Liow Jong-Leng

A survey of the interactions of large gas bubbles formed from top and bottom injection of gases into melts was carried out. Spherical cap bubbles were found not to produce much splash when they break through the bath free surface except for that formed by plunging of the-spout at its edges. In contrast, the bursting of balloons produces cavities which give rise to liquid jets being ejected from the bath free surface. The position of the balloons relative to the bath free surface is an important parameter in the formation of the liquid jet. It is found that the interactions of multiple bubbles close to the free surface is important in determining the splash behaviour of gas injected systems.

Jan 1, 1996

By Jianguo Yin, Xuejiao Zhou, Xiaoyan Xiang, Wenqiang Yang, Xiaoli Yuan, Juan An, Wentang Xia

Low grade phosphorus-containing iron ore (LGPIO), a raw and wasted industrial solid material was used as an adsorbent to remove Cd(II) ion from wastewater. The effects of initial pH value, adsorptive time, initial Cd(II) ion concentration, adsorptive temperature and LGPIO dosage on the Cd(II) ion removal efficiency were studied. The results show that the Cd(II) ion removal efficiencies exceed 99.8% and Cd(II) ion concentrations are less than 0.10 mg/L under the pH value 6, temperature 20 °C, adsorptive time 90 min, initial Cd(II) ion concentration 50 mg/L, particle size <0.15 mm, adsorbent dosage 50 g/L and stirring speed 290 r/min. After Cd(II) ion removal reaction, the Cd(II) ion concentrations completely complies with the requirement of national discharge standard of water pollutants for cadmium and zinc industry (GB 20466-2010) (TCd(II) = 0.1 mg/L) in China. Therefore, it can be concluded that LGPIO is a new low-cost adsorbent which is suitable for the adsorption of Cd(II) ion from wastewater.

Mar 1, 2017

By Dirk Verhulst, V. I. Lakshmanan

Why Chloride Hydrometallurgy?The most available, cheapest and best known reagent for treating ores and other raw materials for the metallurgical industry is sulfuric acid. Hydrochloric acid is second in line. What often happens is that a process is developed on the basis of sulfuric acid, and that at some point the question arises: wouldn't hydrochloric acid do this better?Considering hydrochloric acid immediately opens a very interesting field of research. To summarize a few comments from another paper presented at this symposium [1]: chlorides are far more soluble than sulfates (with a few interesting exceptions); the hydrogen ion activity is greater in chloride than in comparable sulfate solutions; higher oxidative conditions are possible; regeneration is more straightforward; more diversity is possible and better conditions for the separation of species can be found for solvent extraction and ion exchange; sulfur in the ore can be separated as elemental S; higher metal concentrations in solution and more flexibility in the chosen oxidation state means significantly lower energy costs.Also, the volatility of many chlorides at higher temperature allows further separation without the need to go to a different system. Chlorides also form molten salts with a low melting point, providing another means of separation and purification in the same chloride medium.

Jan 1, 2011

By Joseph Gambogi

In 1998, approximately 57,000 tons of titanium metal was consumed in the form of mill products (1). Only about 5% of the 4 million tons of titanium minerals consumed each year is used to produce titanium metal, with the remainder primarily used to produce titanium dioxide pigment. Titanium metal production is primarily based on the direct chlorination of futile to produce titanium tetrachloride, which is then reduced to metal using the Kroll magnesium reduction process. The use of titanium is tied to its high strength-to-weight ratio and corrosion resistance. Aerospace is the largest application for titanium. In this paper, we discuss all aspects of the titanium industry from ore deposits through extraction to present and future applications. The methods of both primary (mining of ore, extraction, and purification) and secondary (forming and machining) operations will be analyzed. The chemical and physical properties of titanium metal will be briefly examined. Present and future applications for titanium will be discussed. Finally, the economics of titanium metal production also are analyzed as well as the advantages and disadvantages of various alternative extraction methods.

Nov 26, 1999