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By Margarete Kalin

Mine abandonment is associated with the securing of access to underground workings, shafts, raises and adits. Waste rock piles and tailings are generally contoured and revegetated. When the waste materials contain pyritic material seepages can often emerge long after the physical reclamation work has been carried out. Their extent and origin has to be delineated to facilitate remedial measures. The depth to which the seepages extended can be determined with an electromagnetic (EM) survey. This paper reports on the experience gained using a winter and a summer EM survey correlated with measurements of specific conductivity at the sediment water interface. Lake sediments and ponds which represent a homogenous background material are good media, where specific conductivity and electromagnetic conductivity can be correlated. The origin of the seepage within the recontoured mine site requires detailed site knowledge, as many anomalies in heterogenous materials such as represented by a mine site are evident.

Jan 1, 1994

Four slag types covering the range of Fe-Ca-Si-O compositions and two iron blast furnace slags were melted at 1300 °C and doped with 1% of arsenic, antimony, cadmium, zinc and chromium. The melts were either slow cooled or quenched and the solidified slags were leached according to TCLP procedures. The morphology of the solidified slags was characterised using XRD, optical and electron microprobe techniques. Theoretical considerations showed that the capacity of the molten slag to hold the above toxic elements depended upon slag basicity and this was confirmed in practice. The experiments showed that the leaching of the toxic elements was a function of surface area and the phases present, both of which were affected by the mode of cooling. Iron silicate slags produced in nonferrous smelting operations and blast furnace slag from ferrous smelting operations both show promise of being suitable media for immobilising low levels of toxic elements and complying with current regulatory requirements.

Jan 1, 1994

By C. W. Whitten

Solis from an abandoned Pb battery processing facility were characterized prior to the selection of the extraction technique. Reflected light microscopy and electron beam methods were used to locate Pb-bearing phases and to quantify the compositions of the phases. It was found that the soils are composed primarily of quartz and feldspars with minor amounts of iron and titanium oxides. Lead is primarily present as an oxide or sulfate that is associated with the silicate minerals. Specific phases identified were PbO; Pb02; cerrusite, PbCO3; angleslte, PbSO4; galena, PbS; and magnetoplumbite, 2PbO3Fe2O3; or plumboferrite PbO2Fe2O3?

Jan 1, 1989

By Rodríguez M. Esperanza

The efficient performance of Pachuca tanks is strongly linked to the suspension of mineral particles, which results from the motion of the liquid caused by injected gas rising, in general, through a central draft tube. This study reports a computational investigation on the effect of operating and design parameters on the suspension of particles. By extending the classical 2-phase drift-flux model to compute the gas hold-up, the three-phase (water-air-particles) system was simulated as consisting of a variable-density liquid plus the solid particles. These two phases were treated as interpenetrated continua using an Eulerian approach to set a turbulent recirculating flow model in 2-D and transient state. The model predicted adequately the measured critical superficial air velocity, uc, needed for maintaining particle suspensions, in pulps with 10-50 wt% solids. Additionally, the model was used to investigate the operation of industrial size reactors, obtaining results that agree well with the general trends reported in the literature, and highlighting important differences with respect to laboratory-scale reactors.

Jan 1, 2009

By Xu Zhang, Xuewei Lv, Guibao Qiu

Slag foaming phenomenon is of vital importance to the mass and energy transfer in metallurgical processes. A considerable extensively studies carried out via out-gas in the past cannot simulate well the foaming phenomenon formed in the blast furnace where high TiO2 iron ore is used. A gas reaction was designed in the water-glycerol system to simulate the inner-gas system. This study investigated the influences of solution viscosity, particle concentration and particle size on foaming caused by endogenetic gas. The results show that the foaming height decreases with the increase of solution viscosity, which means reduced foaming ability, more difficult foaming elimination process and prolonged time for natural defoaming. With increasing the solid particle content, the foam height presents a trend which increases firstly and then decreases. Under a certain solid particle content, foaming height decreases with the increase of solid particle size, indicating a weak foaming ability.

Jan 1, 2015

By S. Yin, A. Bogno, H. Henein, P. Natzke

Impulse Atomization (IA) (a single fluid atomization technique) was used to rapidly solidify Al- 4.5wt%Cu and Al-4.5wt%Cu-0.4wt%Sc under argon atmosphere. In addition to the IA-generated droplets, the same technique was used to produce strips by Spray Deposition (SD) of the same alloys on a copper substrate with and without oil coating. The rapid solidification microstructures were analyzed using Scanning Electron Microscopy (SEM). From the SEM images, the amount of eutectic and the secondary dendrite arm spacing (SDAS) were measured. These SDAS results lead to the estimation of cooling rate. The eutectic fraction coupled with the metastable extension of the solidus and liquidus lines of Al-Cu (Sc) phase diagram lead to the estimation of primary and eutectic undercoolings. A comparison of the solidification path of the droplets and the strips was done as well as the analysis of the effects of scandium.

Jan 1, 2015

By A. Onozaki

The Iijima Refinery was put into operation in 1972 and today has an annual production capacity of 156,000 tons of SHG electrolytic zinc. At the Iijima Refinery, the recoveries of gold and silver are 98.0% and 98.2%, respectively. Gold contained originally in the zinc concentrates reports in the Cu-Pb-Ag residue produced in the residue treatment process. Silver contained in the concentrates is distributed between the Cu-Pb~Ag residue and the copper cake produced in the purification process. The Cu-Pb-Ag residue, which contains gold and silver, is sent to the Oyachi flotatfon plant of the Kosaka Smelter; about 82% of the gold and about 85% of the silver are recovered in the copper flotation concentrate.. In this paper, the distribution of gold and silver in the Iijima. Refinery is discussed and operational results of the Oyachi flotation plant are presented.

Jan 1, 1990

By Liyuan Chai, Bing Peng, Ji Peng, Di Yu

"Electric arc furnace (EAF) stainless steel dust has been classified as a hazardous waste by various government regulatory agencies as it releases heavy metals to environment. The solidification of EAF dust is to stabilize the hazardous components to the amorphous silica-alumina-based clays. The process of solidification is investigated and the softening temperatures of dust and additive clay mixtures are measured for economical thermal treatment. The results indicate that the mixture of dust and local clay with the ratio of 1:1 has the lowest softening temperature 1100 °C and it could pass the toxicity characteristics leaching procedure (TCLP) test for the environmental regulatory limits after thermally treated at softening temperature for 15 min. Major phases of thermal solidification product clinker are CaAl2Si2O8, (Fe, Cr)2O3, (Fe, Mg)(Cr, Al)2O4 and Al6Si2O13.IntroductionThe yield of stainless steels in China arrived to 10 million tons in 2006 and more than 0.2 million tons of stainless steel dust are produced annually. Approximately 1-2 wt.% of scrap charged to an electric arc furnace (EAF) enters the off-gases and then is converted into the dust and reported to the bag-house. The disposal or landfill of the dust becomes a serious environmental problem in China due to the increased production of stainless steels in recent years. The dust contains elements such as chromium (Cr), nickel (Ni), lead (Pb), zinc (Zn), cadmium (Cd) and their solubility in leaching media exceeds the environmental regulatory limits [1]. Even though easily feasible for low-grade MgO, it is not appropriate to stabilize the heavy metals from the heavily contaminated soils after the dust landfill [2]. Several dust treatment technologies have been developed and they can be divided into two types. One is to recover the metals from the dust [3, 4] and another is to stabilize hazardous components present in the dust [5, 6]. Recycling of the dust generated in EAF is a remediation option for cleaner production. Direct recycling of EAF stainless steel dust was developed to recover the metal value from the dust and protect the environment [7], but it was only suitable for the dust with high contents of Ni, Cr and Fe. As for the dust with low valuable metal content, thermal solidification is an appropriate choice for the dust treatment."

Jan 1, 2012

By Laurence Whitty-Léveillé

Proper handling of the radioactive fraction associated with the production of rare earth elements (REEs) in the mining industry is essential for a sustainable environment and human health. Actinides, such as uranium and thorium, have similar chemical properties to REEs, and are often co-dissolved in current hydrometallurgical processes. This causes radioactive contamination of the infrastructure through the extraction cycle. The present study optimizes, through experimental design, a sequential leaching procedure with Na2CO3/NaHCO3 and HCl for the rapid and selective dissolution of REEs and actinides. Optimization focuses on the main operating parameters (time, temperature, and concentration); different types of minerals, REE composites, and ores; on achieving maximal leaching yield; and on minimizing dissolution of the gangue metals (Fe, Si, and Ca). The final sequential procedure was rapid (1 h), effective, and led to the segregation of Th, U, and REEs with limited dissolution of the gangue metals.

By Bart Blanpain, Muxing Guo, Zhuangzhuang Liu

In order to stabilize free lime in the basic oxygen furnace (BOF) slag to achieve high value products, quartz sand and other additives are injected into slag. However, the current hot stage slag stabilization does not work in case of slag (before treatment) with a liquid fraction lower than 90%, where the slag containing solid particles is too viscous. Therefore, it is essential to understand how solid phases affect the viscosity of the slag system. In this study, the industrial BOF slags were investigated with respect to the correlation between volume fraction of solid phases and its viscosity. Slag viscosity was measured with a rotating type viscometer at temperatures below the liquidus. The volume fraction of solid phases was quantitatively calculated with FactSage. The Einstein-Roscoe equation was employed to predict the viscosity of BOF slag.

Jan 1, 2016

By M. Misra

Acid mine drainage from reactive sulfide tailings is a major environmental concern facing the mining and mineral industries. A preventive technique to control acid mine drainage by agglomeration and encapsulation process is presented in this paper. The reactive tailings are agglomerated using Portland cement type I1 as binder. The cold bonded agglomerates after specified curing period are, strong and resistance to weathering. The leaching and weathering experiments have shown that a significant reduction in the concentration of dissolved metals can be observed with the agglomerates as compared to as- received tailings. Addition of small amount of sodium silicate during agglomeration increases the strength and develop good resistance to weathering by forming a glassy coating and elongated crystals within the agglomerates.

Jan 1, 1993

By F. Shahbazian

attempt to systematize the knowledge on slag viscosities, the present work was carried out. The Among the physical properties of slags, viscosity is very important in understanding the mass out in the temperature range 1438-1762 Q The rotating cylinder method was used in the viscosity measurements. Crucibles and spindles made out of pure iron were employed. The transfer phenomena in metallurgical processes. The viscosities of fayalitic slags are of great interest in the non-ferrous metal industry, with special reference to copper production. In an slags were prefused before the measurements. In order to take into account the vaporization reactions involving CaF2, pre- and post measurement samples of the slags were chemically analysed and the compositions were ascertained. The results show that in the case of the CaO-SiO2 system, CaF2 additions tend to decrease the viscosity, in accordance with the expectations. In the case of the "FeO"-SiO2 system, at higher "FeO" / SiO2 ratios in the slags, a reverse trend was observed. The results are discussed on the basis of a viscosity model for silicate melts developed in the present laboratory as well as the structural considerations of silicates.

Jan 1, 2000

By Kang-In Rhee

Nonferrous metal recycling not only provides energy saving and environmental benefits but also is a significant factor in the supply of various types of metals used in our society. Recycling plays an important role in establishing the sustainability of materials. The total amount of recycled nonferrous metals by weight accounts for less than 5% but their value is larger than 50% compared to ferrous metal recycling which consists of about half of the total metal recycling in weight. This paper describes trends and typical achievements in nonferrous metal recycling and overviews the present and future of nonferrous metal recycling technology and business in Korea.

Jan 1, 2006

By Jie Li, Shu Yang, Zhongliang Tian, Xun Hu, Yanqing Lai, Shaolong Ye

The electrolyte with high solubility for Sc2O3 is very important to realize the preparation of Al-Sc master alloy by the molten salt electrolysis. The solubility of Sc2O3 in K3AlF6- Na3AlF6-AlF3 melts is determined with an isothermal saturation method. The effects of KR (ratio of K3AlF6 to K3AlF6+Na3AlF6), the concentration of Al2O3 and the temperature on the solubility of Sc2O3 are also investigated. The results indicate that the solubility of Sc2O3 in K3AlF6-Na3AlF6-AlF3 melts increases and then decreases with KR increasing. The solubility of Sc2O3 is 8.698 wt.% in (K3AlF6-Na3AlF6)(KR25%)-18 wt.%AlF3 melts at 940℃. The effect of temperature on the solubility is little, and the values are 8.575 wt.% and 8.762 wt.% respectively when the temperatures are 930℃ and 960℃. The solubility decreases from 8.809 wt.% to 7.058 wt.% as the concentration of Al2O3 increases from 1.5 wt.% to 5.0 wt.% at 950℃.

Jan 1, 2015

By C. -S. Jiang

In most copper refineries, addition agents are added at predetermined rates with no further monitoring of their activity or concentration in the electrolyte. Increasingly stringent cathode quality requirements, and a desire for better process control in tankhouse operations, have recently directed a number of refineries to search for a better addition agent control strategy. Extensive development work has been carried out at the Noranda Technology Centre for the monitor in of glue and thiourea in copper refinery electrolyte using cyclic voltammetry (cv~. Data from both synthetrc and commercial electrolytes are presented, showing the ability of CV to produce reliable and easily identifiable fingerprints of addition agent concentrations in copper refinery electrolyte.

Jan 1, 1991

By Gong-yi Guo, Yu-li Chen

"A partially-stabilized zirconia powder was prepared by metalorganic precipitation process from technical-grade zirconium oxychloride and the effluent of an acrylic acid plant. The effluent contained low molecular weight carboxylic acids, i. e., acrylic acid and acetic acid. The· developed process is based on the selective precipitation of acrylic acid at suitable pH values by the addition of zirconium oxychloride to the effluent. The resulting precipitate is a precursor that can yield a pure, ultrafine, and partially-stabilized zirconia powder. The evolution of formation of the partially-stabilized zirconia in the present process was investigated using thermal analysis, infrared spectroscopy, and X-ray diffraction technique. Environmental, technological and cost advantages will make the present process feasible for manufacturing advanced zirconia ceramics.IntroductionIn recent years the superior mechanical, thermal, electrical and chemical properties of stabilized zirconia have become the focus of growing scientific and technological interest, and hence resulted in various structural and functional applications. The great potential of the material has given rise to numerous preparation approaches to obtain the material with the excellent properties; nevertheless, an extensive number of programmes are underway worldwide aimed at understanding and improving both the preparation and behavior of stabilized zirconia ultrafine powders. (1 – 8)."

Jan 1, 2000

By Guo Xueyi

The environmental impact assessment of the Imperial Smelting Process for metallic zinc and lead production in Shaoguan Smelter, China, was carried out by the life cycle assessment method. The detailed inventory analysis of the Input/Output in the process during 1998-2000 was conducted and the allocation was done among the main products of zinc, lead and sulfuric acid, according to the system expansion and substitution principle, The environmental impacts were assessed by using the following five Eco-indicators: Gross Energy Requirement (GER), Global Warming Potential (GWP), Acidification Potential (AP), Heavy Metal Toxicity (HMT) and Solid Waste Burden (SWB). The results from this study are useful to address the environmental situation of the technology practice in this smelter, and provide a scientific basis for the further improvement.

Jan 1, 2003

By Ehsan Khajeh

In this study, the permeabilities of Al-15.5wt%Cu and Al-19.5wt%Cu have been determined by solving the full Navier-Stokes equations on 3D geometries of interdendritic channels obtained by X-ray microtomography (XMT). The samples for XMT were sectioned from different positions in directionally solidified cylinders in order to obtain a variety of microstructures for each composition. The flow has been solved using a 2nd-order accurate Finite Volume Method (FVM) approach. The effect of employing uniform or unstructured mesh on the calculated permeability has been studied. The Marching-cube triangulation method was necessary to extract accurate surfaces for unstructured volume meshing. Calculated values of permeability for this range of solid fractions show partial agreement with previous experiments. Observed deviations are attributed to the difficulties of experimental permeability measurements.

Jan 1, 2009

By D. M. Fermino, C. G. Bastos Andrade, V. F. Justo, F. R. Valenzuela-Diaz, M. G. S. Valenzuela, C. Volzone

The present paper presents the study of light green smectite clay, from Paraiba, Brazil, submitted to mild acid attack under moderated conditions. Usually, clays are subjected to treatment with strong inorganic acids at temperatures near the boiling point and at high acid concentrations and then, widely used as bleaching agents. The treatment occurred under bellow boiling temperature and at short times of reaction (90°C, reaction times of 1, 6, 12, 18 and 24 hours in close reactor, concentration of the aqueous solution of hydrochloric acid 1.5 M, clay/acid solution ratio of 1g/10mL). The purpose of these attacks is to reduce the concentration of impurities providing color, with minimal change in the clay minerals structure, aiming at use in products of high value such as cosmetics and polymer/clay nanocomposites. The raw clay and the attacked samples were characterized by X-ray diffraction (XRD), cation exchange capacity (CEC), stereomicroscopy, scanning electron microscopy (SEM) and energy dispersive X-ray detector (EDS).

Jan 1, 2015

By Lei Wang, Jianjun Wang, Lingen Luo, Zhengbang Li

Dearsenication in molten steel was studied by adding Ca-Fe Alloy-based arsenic removal agent. In order to improve the utilization rate of Calcium Iron Alloy and improve arsenic removal ratio, [O] is less than 0.0005% and [S] is less than 0.0035%, Al is added into the molten steel. In the processes of adding CaO-Al2O3 based alkalinity slag for arsenic removing in molten steel (initial arsenic content is 0.0080%), arsenic removal ratio reaches 50% when Ca-Fe Alloy addition amount is 18%. During the arsenic removal experiment, adding Rare Earth promotes the arsenic removal reaction and makes the arsenic removal more effectively.

Jan 1, 2015