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By C. Lupi

Zinc impure solutions as spent electrolytes, leach liquors coming from aqueous treatment of both minerals and solid waste, need to be purified before undergoing the treatment to obtain the final product. Solvent extraction is one of the most selective operations particularly when many metallic ions are present in solution. Zinc pure solutions are frequently obtained using DZEHPA as extractant. In this work an investigation on zinc extraction effectiveness of naftenic acid was carried out. After determining the best diluent and the optimal extractant concentration, the partition coefficient was determined as a function of temperature, equilibrium pH and zinc concentration. Finally same batch tests to determine the equilibrium curves at room temperature on exhausted electrolyte coming from zinc cell were carried out by using naftenic acid, D2EHPA and TBP. The pH giving, for each extractant, the best extraction yield was selected in order to compare the equilibrium curves. Experimental results show that all the examined extractants are very effective in zinc extraction if the process conditions are appropriately selected. In order to avoid an impure solution pre- treatment and to obtain the maximum ertraction yield the appropriate solvent can be chosen.

Jan 1, 1998

By Atul Kurnar

In the present research a two-cell polymer electrolyte membrane fuel cell stack (PEMFCS) with SS-316 bipolar plates has been tested. Different flow field designs were studied and a modified multi-parallel channel design is proposed. The stack is stable within ±3 mV even after 1000 hours of continuous operation, indicating efficient water management and effective removal of any metal ions from the stack. Also no iron is detected in membrane electrode assembly (MEA) by EDAX analysis after 1000 hours of cell operation. Results indicate that high operating pressures beyond 138 kPa didn't significantly increase the performance of cell, however added much to the pressurization cost of the system. Tests at different temperatures showed that at temperatures below 80°C, external humidification could be completely removed. The prototype stack is also tested under variable load conditions simulating highway-driving schedule. The experimental efficiency of PEMFCS is 48%, which is in good agreement with the model predicted efficiency of 53.8 %. Results show that 59% of the total losses are due to ohmic polarization in the cell. Further analysis on applications of the stack in automotive transportation system is in progress.

Jan 1, 2002

By Li Ma, Shaoguo Chen, Gele Qing, Qihang Liu, Keng Wu

Olivine contains higher MgO element, which can be added into blast furnace burden to improve slag stability and fluidity. Effect of calcined olivine and untreated olivine on low silicon pellet production process and quality was studied in this paper. The results shows, calcined olivine has no effect on bursting temperature of green pellet, however the bursting temperature of green pellet will decrease with increase of untreated olivine ratio. Untreated olivine has slight effect on green pellet strength than calcined olivine while the ratio is higher than 2%. The compressive strength of low silicon pellet will increase first and decrease afterwards with increases of calcined olivine ratio under firing temperature of 1250°C, whereas, the changing sequence is reverse fired under 1280°C. The result of untreated olivine pellet compressive strength is same as calcined olivine pellet. However, the compressive strength and metallurgical property of calcined olivine pellet is slightly higher than that of untreated olivine pellet under same condition.

Jan 1, 2015

By Xuemei Zheng, Aiyuan Ma, Yonggang Zuo, Jinhui Peng, Shiwei Li, Libo Zhang

The effect of moisture content on the dielectric properties and microwave drying behavior of zirconium hydroxide was studied by using an open-ended sensor dielectric measurement system at the frequency of 2.45 GHz. The experimental results showed that moisture content can significantly influence the variation of dielectric properties. Dielectric constant, loss factor and loss tangent all increase with the increasing moisture content. Compared with the conventional drying method, the microwave-assisted drying method resulted in a substantial decrease (81.8%) in the drying time, and the drying effect was better at the lower power level of 600 W. This study offers the useful information on dielectric properties of zirconium hydroxide, which can be used for developing microwave drying applications in mineral processing and designing better microwave sensors for measuring zirconium hydroxide moisture content.

Jan 1, 2015

By Peter Sylvén, Darwin Morales

Despite being crucial for the smelting process, furnace tapping using oxygen lances has not been considered an operation that brings value. Therefore, these important tools have not seen a significant change in over 100 years. Problems related to the use of oxygen lances include: • Inaccurate tool: causing damages shortening the life of the taphole refractories. • Safety: extended exposure to the operator in an unsafe area of the furnace. • Cost: high oxygen consumption & high lance consumption. • Time consuming and frustrating to connect one lance to another. This paper will suggest a very good solution; new concept thermal lances. We will show how these provide an outstanding performance for a more efficient, faster and cost-effective furnace tapping operation. These new lances are very accurate tools that enable the operator to perform a more controlled operation; resulting in longer taphole life, fewer repairs and less down-time.

Jan 1, 2016

By Yuanbo Zhang, Qian Li, Helei Zhang, Heng Yu, Guanghui Li, Tao Jiang

"Large reserves of specularite iron ores have been found all over the world, which is characterized by high total iron grade, low gangues content, as well as low commercial price. However, it has not been widely used in sinter or pellet production due to its inferior sintering and roasting behaviors. It has shown that the proportion of specularite ores was increased as high as 40%~50% and good results was achieveed by using Composite Agglomeration Process (CAP), an innovative agglomeration process invented by Central South University. But the mineralization of specularite is still unknown during composite agglomeration processing. In this paper, the induration characteristic of specularite ore is studied by simulating CAP in laboratory, as well as microstructure analysis of CAP product. The results show that specularite pellet is mainly indurated through recrystallization of Fe2O3, calcium ferrite within high basicity sinters matrix interweaves with the recrystallized Fe2O3 on the surface of the pellet, which forms an integral microstructure, and ensures high strength of CAP product for ironmaking.IntroductionLarge reserves of specularite iron ores have been found all over the world, especially in Minas Gerais of Brazil, Xuanhua city and Anshan city of China, Elba island of Italy, St.Gotthard of Switzerland, Cumberland of Britannic, and so on. The specularite ores have a smooth surface, as well as a good crystallization and dense texture. When specularite is used to produce pellets, the specularite ore grains are difficult to adhere onto green ball due to its poor ballability. Moreover, specularite pellet requires high roasting temperature over 1300°C [1]. When specularite ore is used in sintering, the permeability of sintering bed gets bad and the quality of sinter is diminished. The practice in a few sintering plants finds that the output and strength of sinter decrease with the increase of specularite proportion, and the consumption of coke increases [2-4]. Therefore, the utilization of specularite has been limited. Composite Agglomeration Process (CAP) is an innovative technology invented by Central South University [5-7]. The process has the following merits: making reasonable utilization of different iron ore resources; improving the quality and output of sinters; manufacturing sinters with low basicity; significantly reducing energy consumption, etc[8-9]. It has been shown that large proportion specularite ores, as high as 40%~50% can be used well by CAP [10], but the mineralization of specularite pellet is still unknown during composite agglomeration processing. In this investigation, the induration characteristics of specularite ore pellets is studied by simulating CAP in laboratory, and the phase composition and microstructure of CAP product are also characterized by using microscope and Leica image analyzer (Germany, Leica DM RXp)."

Jan 1, 2011

By Grant Wallace, Rod James, Larry Twidwell, Ed Rosenberg, Courtney Young, Sean Dudley, Hsing-Hsin Huang, William Gleason, Jerome Downey

The use of applied chemistry in the production and optimization of leach solutions from Rare Earth Element (REE) ores and concentrates is being investigated. Ore and concentrate samples were characterized using scanning electron microscopy/mineral liberation analysis (SEM/MLA), X-ray diffraction (XRD), and Atomic emission inductively-coupled plasma spectroscopy (ICPAES). Multiple leach tests were performed to analyze the effects of temperature, residence time, and reagent concentration on the leaching of REEs. Analysis of leach solutions was carried out using ICP-AES. Modeling and statistical analysis of extraction behavior was carried out using DesignExpert 9. Modeling data for cerium extraction indicates that extraction is greatly influenced by temperature and reagent concentration, while leaching time plays a much less important role. Experimental design techniques are being utilized to optimize REE recovery. Results, conclusions, and directions for future studies will also be discussed.

Jan 1, 2015

By P .. R. Ammann

A two-stage pyrometallurgical process has been developed for the recovery of copper (and other non-ferrous metals) from copper smelter slags. All types of slags, including highly oxidized, converter-type slags, are cleaned in an electric furnace which employs mechanical mixers to promote magnetite reduction and copper extraction at high rates. In a 10-ton pilot furnace, it has been demonstrated that slags can be cleaned to 0.2-0.3 per cent copper with economically acceptable usage of raw materials and energy; copper is recovered as a high-grade matte. Pilot plant data have been scaled up to a commercial furnace and engineering designs have been made for a furnace to treat 60 tons per hour of slag from a Noranda Reactor and the associated converters. Plans are being formulated for the construction of a prototype slag cleaning furnace.

Jan 1, 1976

By Frank R. Field, Randolph E. Kirchain, Elisa Alonso

"There are a number of environmental incentives for increasing recycling, including the reduction of waste, energy and resource use. Recycling can also be advantageous for manufacturing firms in both the short and long term. Secondary material can substitute for primary material, potentially dampening primary material price increases and reducing the pressure for greater primary extraction. This paper examines the potential for and dynamics of recycling for the case of platinum using a dynamic, behavioral simulation model of the primary and secondary markets. Since the secondary supply of platinum depends on a supply chain separate from primary extraction, recycling can diversify the risks of primary supply instabilities. Over time, recycling can cut primary consumption, reduce overall costs to firms, and possibly reduce the impact of price fluctuations upon firms.IntroductionThe benefits of recycling, from the perspective of the environment, are many, and the environmental benefits of increased recycling are considered a step towards increased sustainability [1, 2]. Life cycle assessments indicate that obtaining materials from secondary sources generally requires less energy and has fewer environmental impacts than extraction and refining of primary materials [3]. Analyses of materials flows show that, in addition to landfill volume reduction, recycling reduces primary material consumption, affecting long term materials scarcity [4, 5].The benefits of recycling are not limited to the environmental. Firms can benefit from the lower energy costs of recycling, especially that of metals whose primary extraction and refining are particularly energy-intensive (e.g., aluminum). The routine participation by firms in secondary materials markets (e.g., www.recycle.net) shows that this advantage has not gone unnoticed.Recycling can also benefit firms whose costs can be significantly affected by changes in material prices resulting from material shortages and material scarcity, with potentially permanent effects upon firms [6-8]. This paper focuses on the impact of recycling in the face of platinum scarcity for supply chain downstream firms."

Jan 1, 2008

By Frank A. Vonesh

In order to reduce the amount of visible, airborne emissions in the Metals Industry, a new Industrial Gas Technology was developed by Air Liquide. This patented technique is called ALECT?, Air Liquide Emission Control Technology. Demonstrations have been conducted for many cutting and lancing operations as well as for hot metal transfer from vessel to vessel. Fume reductions of 90% and greater have been achieved in actual practice. Air Liquide continues to improve the process and the associated control equipment.

Jan 1, 1994

By Cindy L. Williams

"The Blue Star subdistrict in the Carlin Trend, Nevada, includes multiple mines with 33.9 t Au in reserve and past production totaling 89 .1 t Au. The deposits are characterized by zoned alteration mineralogy and gold grades. From orebody centers outward the zones include: 1) a silicified core with erratic gold grade; 2) adjacent mill-grade (> 1.37 Au git) intense quartz-sericite-pyrite alteration; 3) enveloping leach-grade (0.21 Au g/t to 1.37 Au git) weaker sericite-kaolinite-quartzpyrite alteration; 4) surrounding decarbonatized and intensely argillized waste and leach grade ore; 5) pervasively decarbonatized waste rock; and 6) peripheral waste with weak decarbonatization and local propylitic alteration. Zoned alteration extends as much as 1500 m beyond orebodies.Understanding Blue Star subdistrict zoned alteration assemblages and gold grades has increased geologists' ability to provide practical and economically significant information to geotechnical engineers, mine planners and drill and blast personnel. Alteration influences geotechnical pitslope design because each assemblage has distinct rock strength. Geotechnical engineers use three-dimensional models of incompetent alteration types as a foundation for pit-slope design. In the drill and blast cycle, hard and soft alteration types require modified practices (powder column, blast hole spacing, delay design etc.) for optimum blast energy distribution. Further, geotechnically instable alteration types require careful blast procedures to prevent backbreak whic~ damages ultimate walls. In addition to mine planning and mining applications, zoned alteration assemblages extending beyond orebodies provide a useful exploration guide. Metallurgical character also varies with alteration type. Intensely quartz-sericite-pyrite altered or silicified ore has relatively high partical-size dependency and poor leach recoveries. Moderately sericite-kaolinite-quartz-pyrite altered rock, in contrast, shows little size dependency and good leach recoveries.The author sincerely thanks L. Schutz, P. Williams, C. Clode, W. Trudell, P. Herrera, M.DKunkel, M. Goings and numerous other Newmont geologists, metallurgist, engineers and support staff who made this paper possible."

Jan 1, 1997

By I. M. Ritchie

Cyanide owes its great success as a lixivant for gold to the great strength of the Au-CN bond. A replacement for cyanide must similarly be a strong complexant for gold (I) or gold (III). The various alternatives are briefly considered and it is concluded that only thiosulfate has a reasonable chance of replacing cyanide as a relatively non-toxic lixivant at the present time. However, there are considerable technical problems to be overcome before thiosulfate can be considered to be a realistic alternative to cyanide. Firstly, the leaching of gold using aerated ammoniacal thiosulfate with copper as a catalyst is a complex process which needs to be understood and controlled carefully in order to achieve maximum recoveries with minimum reagent losses. Secondly, there needs to be an option similar to the CIP process for recovering and concentrating the dissolved gold thiosulfate complex from pulps produced in the processing of low grade gold ores. The prospects for overcoming these technical' challenges are evaluated and discussed.

Jan 1, 1998

By Mingchun Lu, Yunjin Yan

"This paper describes a new type of bell-less top installed on two relined blast furnaces at Tianjin Iron Works and another new-built at Echeng Steel Works in China. A compact installation was presented for existing furnace top innovation with the least reformation of existing top structure. A water cooling and sealing gearbox used for driving the chute discards completely the traditional idea about necessity of continuous supply of cooling gas for the gearbox. A multiring spreader and its dozens of selectable charging patterns enables an operator to achieve optimal burden distribution easily under the condition of a minimum investment of control equipment. Some useful conclusions have been made through a small-size model and a full-scale model tests. The excellent characteristics and the superiority of the new top have been fully proved at both works.IntroductionIt is known that there are some advantages with the bell-less top of a blast furnace: suitable for furnace to operate at high top pressure, capable of realizing optimal burden distribution, less investment and maintenance costs, etc. But why do most of blast furnaces in the world still remain using conventional bell top. One of the concerns is that current bell-less tops still have some shortcomings:1) The height of a current bell-less top might be lower than three or four-bell top or two-bell plus valve seal top, but still much higher than an ordinary two-bell top.2) The gearbox for driving the rotating chute is positioned onto the lip of the furnace. It is subject to attack by crude hot bf gas. Continuously pumping cooling gas (pressurized nitrogen or clean bf gas) into the gearbox is indispensable to withstand such a harsh working environment. Therefore, a plant furnished with blower8 and its ancillaries has to be built, It involves a large sum of investment and much expense in its annual running costs.3) Although the current bell-less charging device as a means of controlling burden distribution possesses a wide range of freedom, it is difficult to realize optimal burden distribution. There are some large blast furnaces realized better burden distribution, but sophisticated control means is indispensable so that the investment of control means is much higher."

Jan 1, 2000

By Joel Anderson

Allvac 718Plus is a newly developed superalloy with a good potential for use in fabricated aircraft engine structures when service temperatures exceed 650°C; the limit for standard alloy 718. Fabrication involves welding, where cracking usually is a prohibitive factor. Comparison of the solidification cracking behavior between these two alloys was made by Transvarestraint testing. It was shown that the total amount of cracking was significantly lower for 718Plus alloy, which was associated with a lower amount of ?/Laves or ?/NbC eutectic-type constituents. This in turn is believed to be due to the lower iron content of the Allvac 718Plus material. The analysis of alloying element segregation both within primary dendrite and interdendritic constituents clearly indicates that the segregation of Nb is the controlling factor in determining the final solidification microstructure in these alloys. The Nb concentrations of these constituents are significantly higher compared to the bulk alloy concentration. This was confirmed by the SEM-EDS analysis and calculations assessed with JMatPro, the latter also indicated that alloy 718 is more prone to form Laves and NbC eutectic-type constituents compared to Allvac 718Plus material.

Jan 1, 2008

By Dirk van Zyl

As part of the North American regional activities during the Mining, Minerals and Sustainable Development Project (MMSD) one project focused on the development of sustainability evaluations at the operations level. Engagement was identified as one of the seven important questions to be addressed. Engineers and scientists employed in the mining, minerals and materials production arenas must understand the importance of stakeholder engagement, both within and outside the operations as it is essential in the ongoing activities required to contribute to sustainable development. After developing the awareness that a social license can only be contemplated if engagement is in place, they also have to develop skills in engagement processes. This presentation will present the business case for engagement as well as an approach to motivate undergraduate mining engineers to embrace it. The presentation will also review some recent and ongoing research to improve the engagement process.

Jan 1, 2010

By Ted H. Eyde

Natural Zeolites are a less expensive and in certain applications a superior alternative to organic ion exchange resins. Mining and metallurgical waste streams are difficult to treat because the effluents which contain potentially valuable heavy metals such as copper, lead, and silver are often highly acidic and contain significant quantities of suspended solids. Under rigorous operational conditions, certain natural zeolites can remove the metals, which if desired can be recovered by either elution or conventional smelting techniques. There are significant differences in cation exchange rate, selectivity and capacity as well as resistance to either high or low pH, blocking cations and tolerance to elevated or depressed temperature and pressure not only between different zeolite minerals but between the same mineral from different deposits. Applying natural zeolites to the treatment of mining and metallurgical waste streams depends on matching the specific zeolite to the effluent by characterization of the zeolite minerals.

Jan 1, 1993

By Tang Chaoho

Laboratory research on the reducing and matte smelting of Jamesonite concentrate has been carried out. The influence of the process conditions such as the smelting temperature, the amount of pyrite cinder (the agent of fixed sulfur) and the amount of additives on the smelting process have been studied. Under the optimum condition the direct recovery ratios of antimony and lead are 83.26% and 68.50% respectively. The ratio of fixed sulfur is 98.97% but more than 15% lead and 30% silver remained in the ferrous matte. The key problem to be solved of this new process is how economical and effective is the recovery of silver and lead in ferrous matte.

Jan 1, 2003

By Tang Chaoho

Laboratory research on the reducing and matte smelting of Jamesonite concentrate has been carried out. The influence of the process conditions such as the smelting temperature, the amount of pyrite cinder (the agent of fixed sulfur) and the amount of additives on the smelting process have been studied. Under the optimum condition the direct recovery ratios of antimony and lead are 83.26% and 68.50% respectively. The ratio of fixed sulfur is 98.97% but more than 15% lead and 30% silver remained in the ferrous matte. The key problem to be solved of this new process is how economical and effective is the recovery of silver and lead in ferrous matte.

Jan 1, 2003

By S. N. Monteiro, C. M. F. Vieira, M. M. Ribeiro

"This work has as its objective to evaluate the effect of incorporation of the powder waste retained in the eletrostatic precipitator of the sintering stage from an integrated steel making plant on the physical and mechanical properties of a red ceramic. Formulations were prepared with incorporation of the waste in amounts up to 20 wt.% into a kaolinitic clay. Rectangular specimens were prepared by uniaxial mold-press at 20 MPa and then fired at 750, 900 and 1050°C. The evaluated physical and mechanical properties were: linear shrinkage, water absorption and flexural rupture strength. The results showed that the waste has a potential to be used into red ceramics. The incorporation of the waste enhanced the properties of the ceramic, decreasing the water absorption and increasing the mechanical strength at all investigated temperatures.IntroductionThe sintering stage of an integrated steel-making plant is dedicated to the agglomeration of a mixture of iron ore, coke or coal, fluxes and water [1]. It is a common practice in this stage to use of solid wastes with great amounts of iron in the form of sludge and powder. One of the atmospheric pollutants generated during the sintering process is the particulate material, which is normally retained in an equipment denote as electrostatic precipitator. This equipment retains very small particulates, present in the gaseous emissions by application of an electrical potential difference in between the plates that the fluid is forced to go through. [2]."

Jan 1, 2011

By S. C. Grund

In secondary copper smelting as it is performed at Hüttenwerke Kayser plant in Lünen, tin-and lead-containing flue dusts are produced as intermediate products. These flue dusts are further processed in a hearth furnace. Followed by certain refining operations a saleable tin-lead-alloy is produced. Even though the hearth furnace technology has been in use for this purpose for a long time still its performance undergoes changes in search for optimum processing conditions regarding to the increasing complexity of the raw materials and tightening economical and ecological boundaries. The use of modern statistical tools for the calculation of accurate mass balances is demonstrated for the tin-lead hearth furnace. These reliable mass balances are the basis for any further modelling of the process with the aim of optimization. Incorporating metallurgical knowledge and experience as well as different mathematical modelling techniques, further studies are planned in which the recoveries of valuable and minor elements and their dependency from various process parameters are examined. The aim of this modelling is to optimize the recoveries of the valuable elements, to minimize the energy consumption and the processing costs and thus to keep the process competitive in a harsher economical and ecological surrounding. The modelling principles are transferable to other metallurgical operations and are especially suited for ill-defined pyrometallurgical processes.

Jan 1, 1999