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By E. C. T. Chao

Micro-optical and synchrotron radiation-induced X-ray fluorescence (SXRF) techniques have been used to study unoxidized and oxidized samples of Carlintype sedimentar,y rock-hosted disseminated gold ore. In these samples, Where much of the gold is submicroscopic, the SXRF technique, which has a spatial resolution of about 20 ~m and a minimum detection limit (MDL) in the ppm range, is an ideal and necessary tool for precisely locating gold-rich areas in a sample. Gold-rich areas pinpointed by SXRF were later studied in detail by micro-optical methods, principally optical microscopy and scanning electron microscopy with energy-dispersive X-ray analysis (SEM-EDX). In two unoxidized and one oxidized ore samples, SXRF analyses have shown gold to be present predominantly in discrete clay-rich and silicified areas. Gold was not detected by SXRF in association with pyrite or carbonaceous materials. SEM-EDX examination of the gold-bearing areas in the unoxidized samples succeeded in identifying only two free gold particles, 0.2 and 0.5 ~m in size. In the oxidized sample, gold particles appear to be larger (but still submicroscopic) in average size and more evident in micro-optical examination after SXRF location of goldbearing areas. The findings of these studies may help to improve the efficiency of processing and recovery of gold from unoxidized ores.

Jan 1, 1987

By H. H. Kellogg

The thermochemical properties of molten solutions in the binaries Cu-Bi, Cu-Sb and Bi-Sb, as well as the ternary Cu-Bi-Sb, have been correlated and described in mathematical form by use of the associated species concept combined with the three-suffix Margules equations to account for the non-idea 1 behavior of the solution species. Agreement of the correlations with experimental data is excellent (relative deviation of less than 2.5% in the values of the activity coefficients) in most cases. The correlations are applicable over the entire composition range of each system, and in the temperature range 700°-1250°C.

Jan 1, 1985

By A. Galvan

High rate compressible media filter (CMF) tests produced exceptional total suspended solids (TSS) removal at hydraulic loading rates ranging from 97.8 to 122.2 m/h. The compressible media is manufactured from a robust resin fiber that can withstand low pH and temperatures up to 149 °C. The media porosity can be varied by applying compression onto the media. At 40% compression, the CMF can remove particles greater than 4 μ. Three synthetic test-samples were generated by Hazen Research Inc., (Golden, Colorado) to simulate the copper Pregnant Leach Solution (PLS), Raffinate and Electrolyte solutions used for the testwork conducted at their facility. The preliminary results showed that the CMF was very effective in removing TSS without the use of chemical conditioning from the above test-solutions with efficiencies of 98%, 97%, and 96%, respectively. Given the remarkably high hydraulic loading rates, the industrial equipment footprint would be minimized appreciably over conventional clarification and alternative filtration systems.

By J. L. Jambor

Previous crystal-structure determination of magnesian annabergite (Ni,MgMAsO4)2 8H2O indicated that ordering of Ni and Mg occurs in non-equivalent octahedral sites; such ordering supports the possibility of miscibility gaps on the Ni3(AsO4)2 8H2O -MgiAs04)2 8H2O. (annabergite-hornesite) join. In a predecessor study based on analyses of natural specimens, it was proposed that solid solution is incomplete both for annabergite-hornesite and annabergite-erythrite [Co, (AsO4)2 8H2O]. In the current study, syntheses by use of a slow-addition technique and aging of the precipitates indicated that the annabergite-erythrite solid solution is complete, and that no miscibility gap is present on the annabergite-hornesite join to at least 58 mol % Mg. Thus, interpretation of the compositions of these phases in oxidized mill-tailings impoundments can be done with the normal precautions for homogeneity, and without the added concern of the possible presence of miscibility gaps in the ternary system.

Jan 1, 1995

By Yasushi Sawada

An experimental investigation was carried out to study the rates of reduction of iron oxides dissolved in liquid Ca0-SO2-A203 slags by Fe-C droplets at temperatures ranging from 1325 OC to 1550 OC. The %FeO in the slag was varied from 5.5 to 18. Flash X-ray images were employed to observe the behavior of Fe-C droplets in the slags during the reactions and for determining the slag-gas-metal interfacial area. Effect of P205 in the slag and sulfur in the droplet was also investigated. The reduction rates were determined by measuring the volume of CO evolved as a function of time and the estimated slag-gas- metal interfacial area. The reduction rates have increased with increasing %FeO in the slag and the slag temperature. The experimentally established relationship between the reduction rates and FeO (wt%) in slag is given by

Jan 1, 1992

By D. Gregurek

In non-ferrous metal furnaces the installed magnesia-chromite refractory lining is exposed to several stresses, rather complex in their interaction. Therefore, a detailed investigation and understanding of wear mechanisms through “post mortem studies” is an important prerequisite for refractory producer. Additionally, in order to determine the most suitable refractory products and to improve the lining life of refractories, practical corrosion testing with processing slags is performed. For this purpose the test-facilities, such as induction furnace, rotary kiln but also cup test and drip slag test, allow the best possible understanding of chemothermal brick wear on pilot scale. Prior to testing a complete mineralogical investigation, thermo-chemical calculation via FactSageTM of the slag was carried out. Based on such research results, combined with specific process knowledge RHI Magnesita can recommend appropriate brick lining solutions for non-ferrous metal furnaces.

By Stéphane Bourg

The SCRREEN project gathers more than 50 European initiatives, associations, organisations or independent experts working on Critical Raw Materials (CRM) into a long-lasting network including stakeholders, public authorities, and civil society representatives. SCRREEN contributes to improve the CRM strategy in Europe by (i) mapping primary and secondary resources and substitutes of CRMs, (ii) estimating the expected demand of various CRMs in the future and identifying major trends, (iii) providing policy and technology recommendations for actions improving the production and the potential substitution of CRM, (iv) addressing specific waste electrical and electronic equipment (WEEE) and other End-of-Life (EoL) product issues related to their mapping and treatment standardization, and (vi) identifying the knowledge gathered over previous years and making the data accessible to those beyond the project. As a first step, SCRREEN worked at providing stakeholders with a comprehensive analysis of the current use of the CRM, the mapping of potential primary and secondary resources, and identification of the key technologies used in their production. Substitution profiles, analysis of European business and policy issues pertinent to CRMs, and an identification of the standards, policies, and regulatory frameworks concerning these CRM was also completed. In a second step, to be conducted between mid-2018 and mid-2019, SCRREEN will provide guidance for improving the CRM market in Europe by identifying opportunities from research, development, and innovation (R&D&I) that could reduce the supply and/or economic risks around the most relevant CRM for Europe.

By Vinicius Alves Gomes, Jean Igor Margem, Thallis Cordeiro, Frederico Muylaert Margem, Roberto Faria Jr., Sergio Neves Monteiro, Marina Rangel Margem

Natural fibers are attracting the interest of engineering sectors owing to specific advantages such as lightweight and lower cost as well as for their inherent condition of being renewable, biodegradable, recyclable and neutral with respect to CO2 emission. In particular, the fiber extracted from the malva plant stem is nowadays recognized as one of the strongest lignocellulosic fibers. However, the thermal properties of the malva fibers have yet not been fully investigated. The present work had as its objective to investigate, by photoacoustic spectroscopy and photothermal techniques the thermal properties of diffusivity, specific heat capacity and conductivity of a pressed malva fibers sample. The results revealed that these fibers showed a superior thermal insulation capacity.

Jan 1, 2015

By K. D. Peaslee, V. L. Richards, C. H. Rawlins, S. N. Lekakh

"Steel-making processes generate carbon dioxide air emissions and a slag co-product. The aim of this project was to develop a functional sequestration system using steelmaking slag to permanently capture carbon dioxide emitted in steelmaking offgas. A possible parallel benefit of this process would be rapid chemical stabilization of the slag minerals with reducing swelling or leaching.This paper summarizes the original results of the project, including mineralogical and structural features of carbon sequestration with steel making slag, mathematical modeling of reaction phenomena using a modified shrinking core model, METSIM modeling of several possible industrial applications, a thermo-gravimetrical study of the reaction between slags and different gases, and design and testing for a lab scale apparatus consisted of two reactors.1. IntroductionThe U.S. produces 9-14 Mt of steelmaking slag annually, which represents approximately 10-15 wt. % of crude steel output.1,2 Primary uses for steelmaking slag include high quality mineral aggregate, Portland cement, unconfined fill, soil conditioning, and pH neutralization of abandoned mine drainage.3,4 The key factor prescribing slag use is the alkaline-earth metal (e.g. Ca and Mg) oxides content, which contribute to overall basicity and cementitious strength. However, as-produced steelmaking slag is chemically unstable. Calcium and magnesium oxides readily form hydroxides and carbonates through reaction with atmospheric gases. Both hydroxide and carbonate formation produce substantial mechanical swelling leading to heave failure in confined construction applications, thus many states dictate stockpile aging for 3-6 months prior to commercial use.5,6 Sequestration of carbon dioxide is a natural corollary to forced carbonation. The conversion of CaO/MgO to carbonates serves both to stabilize the slag, and permanently capture and store the CO2."

Jan 1, 2008

By Ana E. Bohé, Fabiola J. Alvarez

"The separation of nickel from the aluminum present in spent catalysts and different metallic industrial residues, is proposed in the following systems: alloy Al2Ni and the mixtures 50 wt% Ni + 50 wt% Al, 10 wt% Ni + 90 wt% Al2O3 and 12 wt% NiO + 88 wt% Al2O3. The experiments were carried out in a tubular reactor with a flow of 2 l/h of gaseous chlorine and from 200 ° to 800 °C. The final products of the reaction, extracted from the hottest zones of the reactor where characterized by XRD, SEM, EDS, AA and XRF, as NiCl2 y NiCl2.6H2O while in the coldest regions AlCl3 was deposited in the first two cases and in the other there was a residue of ?, a- Al2O3, sometimes mixed with some remainder of Ni and NiO. The procedure attained different separation factors which showed the optimun conditions for the recovery of both metals. Introduction Some studies of nickel corrosion were carried out in chlorine gas at temperatures above 950ºC, and suggested that nickel is not corroded below 538ºC. [1] However, in a previous work it was shown that the chlorination allows the separation of nickel from aluminum and the formation of NiCl2 was detected from 200ºC in binary mixtures Ni-Al 50 wt%, for isothermal conditions in chlorine flux. [2] Other researchers obtained selective chlorination above 650ºC of a fly ash containing 1.4 wt% of Ni and other metals (V, Mg, Al and Fe). The Ni was separated from the Mg and NiCl2 started to vaporize at 550ºC and was after condensed in a zone of the reactor above 380ºC with 90% of purity. [3]"

Jan 1, 2008

By Ilija Ilic

Recovery of tin from tinplate and production of good-quality detinned-plate for further processing in ironworks has been the subject of interest for many years. Tinplates are mostly used for production of tin containers for food industry and consumer goods. The research carried out so far included determination of the parameters of dissolution of tin from tinplates by alkaline solution of NaOH and electrochemical recovery of tin from the alkaline solutions. During leaching, NaNO3 and methanitrobenzoic acid (MNBA) as oxidants were studied. By leaching the waste tinplate which contains 0.31 % of tin with a solution of 1.12 mol/dm3 NaOH, 0.26 mol/dm3 Na2CO3 and 0.09 mol/dm3 MNBA at temperature of 70°C for 60 mm, a degree of tin leaching of 97 % was attained. MNBA facilitates oxidation of Sn2+ into Sn4+ suitable for obtaining compact, and not spongy, Sn cathode deposit, as it was the ease earlier. Recovery of tin by electrolysis from solutions obtained by leaching was studied to determine the effect of electrolyte composition on the quality of cathode deposit and the degree of electric current efficiency. Experimental results obtained at a laboratory level were checked on an enlarged laboratory set up where continuos leaching of tin from waste tinplate and its electrolytic recovery from the solution obtained were carried out. The experimental set-up -operated under semi-industrial conditions, and about 500 kg of waste tinplate was processed yielding about 1.160 kg of tin (99 % Sn).

Jan 1, 2000

By Patrick R. Atkins

Energy issues will have increasing impacts on decision making in all facets of society over the next few decades. Industrial users of energy and producers of products that affect energy use must be fully aware of the implications of their processes and products on the energy situation. This paper describes a model that has been developed for the aluminum industry that allows scenarios to be evaluated to gain improved understanding of possible implications for our businesses. A brief overview of the model is provided.

Jan 1, 2006

By Lucas L. da Costa, Sergio N. Monteiro, Romulo L. Loiola, Tammy G. Rodrigues Portela

"The fibers extracted from the petiole of the buriti palm tree are relatively strong as compared to other lignocelluloses fibers, with a potential for composite reinforcement. In this work, polyester matrix composites incorporated with these fibers were investigated for their flexural behavior. Specimens with up to 40% in volume of continuous and aligned buriti petiole fibers were bendtested until rupture. The results showed an increase in both the composite mechanical strength and the stiffness with incorporation of these fibers. A fractograph analysis by SEM disclosed a moderate adhesion mechanism between the buriti petiole fiber and the polyester matrix. This mechanism is apparently responsible for the improved performance of the composites.IntroductionIn recent years, the substitution of energy-intensive synthetic materials for natural ones is being considered in many industrial sectors including automobile, packing and textile [1]. A typical case is that of natural fibers, mainly those obtained from cellulose-based plants also known as lignocelluloses fibers. They have being investigated in the past two decades, aiming to replace synthetic fibers, particularly the glass fiber, commonly used as polymer composite reinforcement [2-8]. From the engineering point of view, lignocellulosic fibers present today important environmental, economical, societal and technological advantages already discussed [7-8]. Moreover, several lignocellulosic fibers are known since the beginning of our civilization and still cultivated or naturally extracted all over temperate and tropical regions of the world. According to Kalia et al [1 ], these fibers can be classified by their origin, as shown in Table 1."

Jan 1, 2011

By Leonardo Mota, Felipe Perissé Duarte Lopes, Marcelo Gomes da Silva, Sergio Neves Monteiro, Helion Vargas

"Natural fibers, as a class of material, are attracting the interest of engineering sectors owing to specific advantages such as comparatively reduced cost and lower density as well as environmental benefits associated with renewability and biodegradability. For industrial applications, thermal properties, among others, are required. These are major requirements, especially in the case of an insulating natural fiber. In the present work, thermal properties of the curaua were investigated by photothermal techniques, i.e., the open photoacoustic cell and a method based upon the monitoring of the temperature evolution as a function of time. This investigation, in tum, permitted to evaluate two important thermal properties: the thermal diffusivity and the specific heat capacity of the curaua fibers. Indirectly, by means of simple mathematical relations, the thermal conductivity was also obtained. The results were compared with other materials and characterize the curaua fiber as an efficient insulator.IntroductionMaterials are gaining attention in recent years owing to their benefits for the environment as compared to synthetics. Being biodegradable, yearly renewable and recyclable, the natural planted-based are considered fully sustainable [1]. In particular, their life-cycle, from growing to industrial processing, absorbs as much C02 as it is emitted and makes them neutral with respect to greenhouse gases responsible for global warming [2]. Typical examples of these environmentfriendly materials are the lignocellulosic fibers that have been used in simple items such as ropes, baskets, textile, modest roofing, etc, since the beginning of our civilization [3]. In the past few decades, these natural fibers have been extensively investigated [ 4-1 O] as a possible reinforcement phase of polymer composites in substitution for synthetic fibers. In fact, engineering application of lignocellulosic composites are today in the market, especially in the automobile industry [11-13]. Out of the hundreds available natural fibers, only part of them exhibits superior properties to be qualified for composite reinforcement."

Jan 1, 2011

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 Uchil Jayagopal, P. V. Krupakara, S. Manjunath

"This paper deals with the corrosion characterization of quartz particlate ZA-27 alloy metal matrix composites (MMCs). Quartz particles of size 50-80 microns are used as reinforcement. MMC's are prepared according to ASTM standards. Composites containing. 2, 4, and -6% by weight of quartz and unreinforced matrix were tested using 1 -N hydrochloric acid: The composite was found to be more corrosive resistant than matrix alloy. In each test the corrosion resistance of both alloy and composites were found to decrease with the exposure time.1. IntroductionMetal matrix composites- (MMCs) offer designers many added benefits, as they are particularly suited for applications requiring good strength at high temperature, good structural rigidity, dimensional stability, and light weight 1-5. The trend is towards safe usage of the MMC parts in the automobile engine, which work particularly at high temperature and pressure environments Particles reinforced MMCs has been the most popular over the last two decades.ZA alloy MMCs have most popular families being represented by. ZA-27 alloy reinforced with ceramic particulate. Although the incorporation of the second phase into a matrix material can enhance the physical and mechanical properties of the base metal, it could also significantly change the corrosion behavior.ZA alloys have been used extensively in industry. This is attributed to their excellent fludity, castability and good mechanical properties. Among the zinc-based foundry alloys, the ZA family of alloy have been widely used during the past few years. ZA alloys have many advantage over aluminium based ones, especially high strength with a low casting temperature 8."

Jan 1, 2000

By Patrick R. Atkins

Energy issues will have increasing impacts on decision making in all facets of society over the next few decades. Industrial users of energy and producers of products that affect energy use must be fully aware of the implications of their processes and products on the energy situation. This paper describes a model that has been developed for the aluminum industry that allows scenarios to be evaluated to gain improved understanding of possible implications for our businesses. A brief overview of the model is provided.

Jan 1, 2006

By Patrick R. Atkins

Energy issues will have increasing impacts on decision making in all facets of society over the next few decades. Industrial users of energy and producers of products that affect energy use must be fully aware of the implications of their processes and products on the energy situation. This paper describes a model that has been developed for the aluminum industry that allows scenarios to be evaluated to gain improved understanding of possible implications for our businesses. A brief overview of the model is provided.

Jan 1, 2006

By Patrick R. Atkins

Energy issues will have increasing impacts on decision making in all facets of society over the next few decades. Industrial users of energy and producers of products that affect energy use must be fully aware of the implications of their processes and products on the energy situation. This paper describes a model that has been developed for the aluminum industry that allows scenarios to be evaluated to gain improved understanding of possible implications for our businesses. A brief overview of the model is provided.

Jan 1, 2006

By Hongli Wen, Guangkun Shen, Qiong Deng, Xuling Chen, Min Gan, Xiaohui Fan

"In this research, pyrite cinder which contains 53.51% Fe and 0.54% Pb was processed by magnetic roasting separation to obtain a concentrate with 64.62% Fe and 0.56% Pb. The concentrate was then leached with hydrochloric acid to remove lead. Several technological parameters which may influence the removal efficiency were investigated: the mass fraction of hydrochloric acid, pulp density, the leaching time and temperature. On the conditions that the mass fraction of hydrochloric acid of 5%, pulp density of 30%, the leaching time of 30 minutes and leaching temperature of20°C, the lead content in the concentrate was reduced to 0.19%. The product was suitable for agglomeration and pelletization. Through the analysis of the lead distribution and phase change during the whole process, the mechanism of lead separation from pyrite cinder was analyzed.IntroductionPyrite cinder is rich in iron, which defines its most extensive and effective use as raw materials for iron making. However, some pyrite cinders contain much non-ferrous metals, which is detrimental for the iron making process. Lead, one of the harmful elements, will destroy the blast furnace lining. Besides, it causes pollution of the environment[1]. Therefore it is necessary to remove excessive lead before entering the blast furnace. To separate the lead from pyrite cinder, much research was done, including flotation, high temperature evaporation and leaching. High temperature evaporation consumed too much energy. The flotation was difficult to obtain high- grade iron ore concentrate[2]. Majority of the leaching was direct leaching of pyrite cinder, which was also difficult to get high-grade iron ore concentrate[3]. This article explored the magnetic roasting method to get high-grade iron ore concentrate, acid leaching method of the concentrate to remove excessive lead, providing guidance for the efficient utilization of pyrite cinder."

Jan 1, 2013