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By Kouichi Nakano

Austenitic stainless steel, which includes nickel for stabilizing austenitic structure, is used for various purposes, for example, for structural material, corrosion-resistant material, biomaterial etc. Nickel is set as one of the rare metals and economizing on nickel as the natural resources is required. On the other hand, nickel is one of the metals that cause metallic allergy frequently. Therefore, high nitrogen stainless steel, where nitrogen stabilizes austenitic structure instead of nickel, has been developed in Japan and some of the foreign countries for the above reason. When high nitrogen stainless steel is fused and bonded, dissolved nitrogen is released to the atmospheric area, and some of the material properties will change. In this study, we bonded high nitrogen stainless steel by stud welding process, which is able to bond at short time, and we evaluate joint performance. We have got some interesting results from the other tests and examinations.

Jan 1, 2016

By Saynbaatar, Gangping Ma, Jianhua Fu, Qiqige, Jinghua Wang

The influence on the performance of foam concrete made by replacing cement with some industrial waste residues was researched in this paper. The result shows that the 7d and 28d compressive strength of foam concrete increases firstly and then decreases with the increasing amount of industrial waste residue. The proper added range is 10%-20% for steel slag, blast furnace slag and coal ash, but, 8% for desulfurized fly ash. With the proper adding ratio, the compressive strength of foam concrete always increased comparing with the pure cement foam concrete. When adding 48% of the compound industrial waste residues, the 28d compressive strength of the foam concrete reached the 2.9MPa which could match the pure cement foam concrete. The results indicates that there is a synergistic effect among the compound industrial waste residue, and this effect is benefit to improving the compressive strength of foam concrete.

Jan 1, 2015

By Bhavani Kedika, Venkatagiri Noole, Krishna Thotla, Krishna Reddy Chepyala

Cationic lipids are attractive candidates for transgene delivery and expression and are safer alternatives to viral delivery vehicles. Here, we report the design, synthesis, characterization and transgene expression efficacies of a series of chrysin derived cationic lipids. A series of ten lipids of chrysin was synthesized by treating the 7-hydroxy group with dibromoalkane and further substitution of the bromo derivative with alkyl amines. The synthesized lipids were characterized spectroscopically. Parallel screening of the synthesized lipids for in vitro plasmid delivery expressing luciferase led to identification of several leads that demonstrated higher transgene expression when compared to the standard. Transgene expression efficacy was dependent on the chain length of the lipid. The influence of the various physicochemical properties on transgene expression efficacies was investigated. This study indicates that lipids derived from chrysin results in high levels of transgene expression and may be attractive for gene therapy applications.

Mar 1, 2017

By Rick Honaker

Rare earth elements (REEs) contained in coal and associated mineral matter exist in several forms including micro-dispersed minerals, ion adsorption onto clay surfaces, and chemically bound. Tests found that REEs can be effectively recovered from certain components of three coal sources by leaching under mild conditions followed by solvent extraction. A range of pH values were evaluated at solution temperatures of 25 and 75 °C. When using 1.2 M of sulfuric acid, nearly 85% recovery of the REEs was extracted from the middlings material collected from an operating plant. Acid leaching of a second middling source from another plant resulted in 60% of the total REEs being recovered under the same leaching conditions. Solvent extraction treatment of the leachate produced from six different coal sources resulted in products containing up to 50% total REEs from feedstocks starting with around 300 ppm.

By Gen Kamimura, Hiroyuki Matsuura, Wonjin Choi

Control of non-metallic inclusions in terms of morphology, number density or composition is essential to produce steel products having the desired mechanical properties.Though many studies have been conducted to clarify various properties and evolution mechanisms of inclusions at steelmaking temperature, it has been reported that the states of inclusions in final products are significantly different from those in crude steels for some steel grades. The present study has focused on the evolution of oxide and nitride inclusions in solid Fe–Al–Ti–N alloys during heating to increase the understanding of inclusion evolution in a simplified metal system. Compositional and morphological change of initial inclusions, as well as precipitation and growth of new inclusions have been observed even when the alloy was in a solid state.This behavior has been observed due to the change of thermodynamic stability and solubility of existing phases in inclusions.

Mar 1, 2017

By Lucio Fabio Cassiano Nascimento, Luis Henrique Leme Louro, Sérgio Neves Monteiro, Jheison Lopes dos Santos, Fernanda Santos da Luz, Fábio Oliveira Braga, Rubens Lincoln Santana Blazutti Marçal, Hugo Concolato de Oliveira Freitas, Édio Pereira Lima Júnior

Epoxy matrix composites reinforced with up to 10, 20 and 30 vol% of continuous and aligned natural mallow fibers and 30 vol% of mallow and jute hybrid fabric were for the first time ballistic tested as personal armor against class III 7.62 mm FMJ ammunition. The ballistic efficiency of these composites was assessed by measuring the dissipated energy and residual velocity after the bullet perforation. The results were compared with that in similar tests of aramid fabric (Kevlar™) commonly used in vests for personal protections. Visual inspection and scanning electron microscopy analysis of impact-fractured samples revealed failure mechanisms associated with fiber pullout, rupture and layers delamination. When compared to Kevlar™, the mallow fiber and hybrid fabric composite displayed practically the same ballistic efficiency. However, there is a reduction in both weight and cost, which makes both, mallow fiber and hybrid fabric composites, a promising material for personal ballistic protection.

Mar 1, 2018

By Jun Miao, Kang Liu, Jilai Xue, Jun Zhu

CO2 emissions must be reduced by at least 50 % by 2050, and hence the technical solutions to capture and convert CO2 into value–added products should be considered. A Cobalt(III) Schiff base complex (Salen–Co(III)) has been investigated as a catalyst for synthesis of cyclic carbonate from CO2 and epichlorohydrin(ECH) with tetrabutylammonium bromide (TBAB) as co–catalyst. To recover Salen–Co(III) for the next cycling operation, it was immobilized onto zeolite 13X through excessive impregnation method. The immobilized catalyst was characterized using XRD, SEM, BET and ICP–AES techniques. Catalytic tests showed that yield of cyclic carbonate reached 90 % using 0.5 mol % Salen–Co(III) at ambient conditions. The immobilized Salen–Co(III) exhibited better catalytic activity than the homogenous one when used at the first cycle, but the yield decreased by some 20 % after five cycles.

Jan 1, 2015

By Liuyin Shi, Kang Liu, Fengqi Zhao, Yan Song, Zhiping Yang, Xing Fan

Due to the high energy consumption, long technical process, low usage rate of vanadium during the traditional smelting vanadium steel process, a new method for decarburization by CO2 to directly smelt vanadium-containing steel in blast furnace was proposed. In this paper, the thermodynamics of CO2 decarburization in molten iron process was calculated out by FactSage. The thermodynamic calculations indicated that in standard state, the transformation temperature of C and V was 1357 °C; the oxidation order of element was Si, C, V, Mn and S when using CO2 as oxidant. The experiment of blowing CO2 temperature showed that decarburization reaction temperature was 1550 °C, carbon content could be decreased to 0.676%, the decarburization rate was 88%. There was no effect on vanadium content in molten iron during the decarburization process, vanadium content was 0.323%, which meets the request of vanadium mould steel.

Mar 1, 2018

By F. Tailoka

In order to decrease the voltage required for electrorefining, a recessed electrode cell has been developed in which the anode and cathode have recesses machined into their faces. The anode and cathode plates are separated by a thin refractory cloth and the cell is filled with fused salt. Bismuth containing 10 to 90 % lead with copper and silver as minor impurities has been electrorefmed at a current density of 10,000 to 20,000 Am-2. The cell voltage was between 285 and 635 millivolts and the bismuth was refined to a purity of 99.9 %. Flow patterns were observed in a room temperature model of the recessed channel cell using water and mercury to simulate molten metal and the fused salt electrolyte. The flow in the electrode recesses is characterized by discrete droplets when the liquid flow rate is low and thin streams and rivulets at higher flow rates.

Jan 1, 1995

By D. N. Wilson

The potential risks of working with lead have been recognised for centuries, but it is only with the development of sensitive measuring techniques in relatively recent years that it has been possible to establish effective approaches for the monitoring and control of lead exposure. This paper examines the principal control measures employed today - lead in air and lead in blood - and reviews the evolution of numerical standards, with particular reference to the latest understanding of health effects. In addition to lead, a large number of other metals are commonly encountered when producing lead and zinc - both primary and secondary - and the health effects of many of these are discussed. Modern hygiene practices and technologies, which have proved successful in reducing worker exposures, are reviewed. The paper concludes with a look at how exposure standards are likely to change in the near to medium future

Jan 1, 2000

By Jung-Ah Kim

Precipitated Calcium Carbonate (PCC) is obtained through calcination, hydration, and carbonation. Thus, the change in each process condition determines the particle size or morphology of PCC. To date, studies on precipitated calcium carbonate have mainly focused on process manufacturing PCC, aimed matter. Still, few studies on calcination or hydration have been conducted. Therefore, this study sought to investigate the effect of hydration condition on the synthesis characteristics of aragonite PCC. Results showed that the particle size of calcium hydroxide changed based on the variation of the initial hydration temperature. In particular, higher initial temperature resulted in the larger particle size of calcium hydroxide used in synthesis. The particle size and yield of aragonite also increased when calcium hydroxide made at high temperature was used. The water/solid ratio or total amount at the hydration time had no effect on the manufacturing process of aragonite, however.

Jan 1, 2006

The presence of clay adversely affects the floatability of copper and molybdenum during processing porphyry copper/molybdenum ores. In addition, reagent consumptions are much higher than when treating clay-free ores. Ores containing kaoline, brammollite, illite and montmorillonite were examined in the laboratory to determine how clay minerals affect the floatability of copper and molybdenum, and to find a possible solution to alleviate the harmful effect of clay slimes. It was demonstrated that the presence of clay mostly affects floatability of coarse and middling particles, and reduces selectivity. The results of the research work showed that there may be several possible ways of reducing the detrimental affects of clay slimes on flotation, some of which include a) use of alternative flowsheets, b) flotation at reduced pulp density, and c) the use of special frothers. The applicability of the findings in plant practice are discussed.

Jan 1, 1999

By Michael S. Moats

As commercial copper electrorefineries look to expand their capacities by increasing their operating current density, the likelihood of anode passivation intensifies. To improve the industry?s understanding of the passivation phenomena, the role of anode composition was evaluated. While previous studies have focused on studying one impurity element at a time, this study was conducted using forty-four commercial electrorefining anode samples supplied by ten copper companies The passivation response of each sample was evaluated under accelerated galvanostatic conditions in synthetic copper electrowinning electrolyte at 65°C. This information allows for correlations between composition and passivation tendencies over a wide range of impurity elements and concentrations. It was found that selenium, tellurium, silver, lead and nickel accelerated passivation. It appeared that oxygen accelerated passivation when increased from 500 to 1500 ppm, but further increases did not have an effect. Arsenic was the only impurity found that inhibited passivation.

Jan 1, 2006

By M. A. S. Siraa

A program of work was undertaken at the Kennecott Smelter and Refinery to model the complex. This effort contributed a total of eight models of the plant: flash smelting furnace, flash converting furnace, slag concentrator, anode furnace, offgas scrubbing system, acid plant, hydrometallurgical dust treatment plant, and the precious metals plant. Some of these models have been used in a variety of investigations ranging from offgas capacities for a steam generation analysis to an examination of impurities. The culmination of this enterprise has resulted in an on-line control scheme for the flash smelting and flash converting furnaces. These two process control schemes incorporate their respective steady-state heat and mass balances that are executed in response to feed changes while a feedback loop calculates when product grade and temperatures deviate from setpoints. This system has been put into place to improve furnace control and on- line time.

Jan 1, 1999

By Xiyun Yang

Magnetite was prepared by hydrogen reduction method. For a conversion to cobalt-modified magnetite, magnetite particles were suspended into a solution containing Co2+ and Fe2+ to precipitate a cobalt ferrite layer on the surface. pH value influences the particle composition directly, the desirable CoFe2O4 is obtained when pH value is 12. The coercivity increases with the increase of cobalt content, cobalt efficiency reaches a maximum value at cobalt content of 2.71wt%. With cobalt modification, magnetite particles have similar lattice constant and squareness ratio to that without cobalt modification. TEM and XPS analyses indicate that acicular morphology is retained during the coating process, the epitaxial growth layer consists of CoFe2O4and 0.3Co2O3CoFe2O4 at cobalt content of 2.71wt% and 5.03wt%, respectively.

Jan 1, 2006

By O. A. Bascur

Applying the latest information technologies in mining and metallurgical complexes has become a serious challenge to management and technical teams. Emerging component design is changing the way the user relates to the desktop. Connectivity between mining and metallurgical process operations and their business systems has become a reality. Expanded use of plant information on the desktop is a standard tool for revenue improvement, cost reduction and adherence to production constraints. The industrial component desktop support access to information for continuous improvement and innovation by staff personnel and engineers. Collaboration between groups enables the implementation of an overall process effectiveness index based on losses due to equipment availability, production recovery and quality rate. The integration of information from mining, mineral processing and metallurgical performance monitoring increases production efficiency, even when many elements cannot be measured directly. Three case studies of large mining/metallurgical complexes are highlighted.

Jan 1, 1999

By Matthew Jeffrey

Leaching, cementation, electroplating and flotation are all electrochemical phenomenon. They are also key processes in the hydrometallurgical treatment of metals. Unfortunately electrochemical methods tend to be under-utilized when studying these processes and one possible reason for this is the confusion surrounding the large number of electrochemical techniques available. In this paper four former PhD students of Professor Ian Ritchie present an insight into how one electrochemical technique can be used to compliment rate/kinetic studies. The paper details how to perform the experiments, interpret data, and recognize complications with the results. Examples where this approach has been highly successful are presented, and include: cementation of zinc by aluminium, cementation of copper by nickel, cyanide leaching of gold and the cementation of gold thiourea by mild steel. The examples illustrate that this universal approach adopted by Ian Ritchie provides the key to understanding the mechanism of many hydrometallurgical reactions.

Jan 1, 2003

By Hongyang Cao

The iron constituents selectively separated from the modified copper slags by magnetic separation and flotation.were studied. The results of magnetic separation for modified copper smelting slags show that the grinding size, current intensity and dispersant agent had great influence on grade, and recovery ratio of TFe in preparation concentrate; The results of flotation for magnetic concentrate show that the positive flotation of sodium oleate negatively upgrade the grade of magnetic concentrate, but the reverse flotation of lauryl amine and soluble starch are effective. The grade of TFe can reach 54% and the recovery ratio can reach about 90% in magnetic concentrate, when the grinding size is 45.8µm and the current intensity is 2.5A. The optimal effect is obtained by using lauryl amine as collector and soluble starch as depressant to reverse flotate magnetic concentrate, and the grade of TFe is upgraded 2.37%.

Jan 1, 2009

By Carl W. Lam

The increased obsolescence rate of electronic products has made it evermore pertinent to understand the potential environmental impact of materials choices to help guide electronic waste (e-waste) management and promote awareness of high burden materials. Methods for screening for the performance of materials and their potential burden on human health and the environment can be used to comparatively select constituents of present and prospective electronic products. These methods should be able to yield more robust information when linked to other decision-making strategies where integrated data on consumer preferences, production quantities, and regulatory initiatives are sparse or unavailable. A framework is presented here for generating metrics of ecological toxicity, human health toxicity (cancer and non-cancer categories) and global resource consumption for evaluating environmental impact of materials (specifically metals) in electronic products. The time-dependent impact trends of United States? printed wiring board (PWB) metals usage, principally derive

Jan 1, 2010

By Jin Qiu

Experiments were performed to determine the extent of minor element elimination that occurred when mixtures of copper smelter dust and copper concentrate, were calcined under vacuum. Almost complete removal of the As, Sb, Bi and Pb occurred due to the conversion of the minor element compounds of these elements into their highly volatile sulphides by reaction with sulphur from the concentrate. Heat and mass balance calculations of the slag-blow in a copper converter found that ~30 tonnes of the vacuum calcine could be used to produce 100 tonnes of copper as white metal. The use of dirty concentrate as the sulphidizing agent in the vacuum calcination means that the minor element treatment capacity of the smelter complex could be increased by 60 %. Also the productivity of the converters may be increased by up to 8 % due to the supply of copper values and oxygen in the calcined mixture.

Jan 1, 2005