The Experts below are selected from a list of 285 Experts worldwide ranked by ideXlab platform
S.r Swarnkar - One of the best experts on this subject based on the ideXlab platform.
-
HydroMetallurgical processing of Lead-bearing materials for the recovery of Lead and silver as Lead concentrate and Lead Metal
Hydrometallurgy, 2000Co-Authors: R. Raghavan, P.k Mohanan, S.r SwarnkarAbstract:Abstract HydroMetallurgical processing of Lead-bearing materials generated at zinc plants is described. Two types of Lead sulphate generated at the smelters of Hindustan Zinc (HZL) have been used, in addition to other types of Lead–silver-bearing residues. Two approaches have been selected in view of the complexities of the material. In the first approach, a simple double-decomposition technique was selected for treatment of one of the Lead-sulphate residues by reacting with sodium-sulphide solution after the removal of acid-soluble Metal values to produce a high-quality Lead concentrate. In the second approach, the Lead-sulphate residue was treated with brine solution and the resultant filtrate was reacted with sodium-sulphide solution to obtain Lead concentrate or cemented-out Lead as Lead sponge using aluminium scrap, which was then briquetted and melted into Lead Metal. Alternatively, the Lead sponge was subjected to roasting to obtain litharge as a value-added product. The processes developed are very simple, easy to implement and cost-effective, eco-friendly with cleaner technology. The recoveries are excellent. The Lead concentrate obtained by the proposed processes can be used directly in the Lead circuit and the Lead sponge obtained can be melted and cast into Lead ingot or roasted to produce Lead oxide. The quality of Lead concentrate, Lead Metal and Lead oxide produced by the processes are also incorporated. Based on the results, conceptual flowsheets have been developed to treat 3–5 tons/day Lead-bearing materials. A similar method was applied to other Lead–zinc–cadmium–silver-bearing materials generated at HZL plants. The results are presented along with the flowsheet.
Shusen Zhao - One of the best experts on this subject based on the ideXlab platform.
-
Microstructural and mechanical characteristics of laser welding of Ti6Al4V and Lead Metal
Journal of Materials Processing Technology, 2012Co-Authors: Shusen ZhaoAbstract:Abstract Titanium alloy Ti6Al4V and Lead Metal were welded using a continuous wave Nd:YAG laser. The influences of laser power, scanning velocity, and laser beam offset on weld morphology were investigated. Microstructure, chemical composition and mechanical properties of the joints were evaluated. Experimental results showed that fusion weld formed at the upper part of the weld and brazing weld with solder of Pb formed at the lower part of the weld under appropriate process condition. Interfaces were formed between mixed fusion zone and liquid Lead zone in molten pool during laser welding of Ti6Al4V and Lead. Reasons for interface formation may be different driving force of various regions in molten pool, and the miscibility gap of Ti and Pb binary system. Ti-Pb interMetallic compound Ti4Pb was detected at the fusion weld zone, which made the microhardness of the weld seam was higher than that of the base materials. The strength of the joint was at least equal to or larger than that of Lead base material.
Annabella Orlandini - One of the best experts on this subject based on the ideXlab platform.
-
Lone pair activity in Lead(II) compounds. X-ray structure of the dimeric complex [(trenMe6)Pb(O2CCH3)]2(BPh4)2, trenMe6=N(CH2CH2N(CH3)2)3
Inorganica Chimica Acta, 2000Co-Authors: Franco Cecconi, Carlo A. Ghilardi, Stefano Midollini, Annabella OrlandiniAbstract:Abstract The reaction of the tetradentate tripod-like ligand N(CH2CH2NMe2)3 (trenMe6) with Pb(CH3COO)2·3H2O in presence of Na(BPh4) allows the formation of the complex [(trenMe6)Pb(O2CCH3)]2(BPh4)2. The complex displays a dimeric structure where each Lead Metal is linked by one trenMe6 ligand and by three oxygens of two bridging acetate groups in a hepta-coordination. The presence of a void in the angular distribution of the ligands around the Metal as well as the values of the PbL distances, with those opposite to the void significantly shorter than the others, are indicative of the presence of a stereochemically active lone pair on Pb(II).
Geoffrey M. Gadd - One of the best experts on this subject based on the ideXlab platform.
-
A New Lead Hydroxycarbonate Produced During Transformation of Lead Metal by the Soil Fungus Paecilomyces javanicus
Geomicrobiology Journal, 2016Co-Authors: Young Joon Rhee, Stephen Hillier, Geoffrey M. GaddAbstract:ABSTRACTPrevious research has demonstrated the transformation of Metallic Lead into pyromorphite in solid and liquid medium by several species of fungi. In this work, the soil fungus Paecilomyces javanicus was found to mediate formation of an unknown Lead mineral phase after incubation in liquid media with Lead shot. After 2 weeks' incubation, precipitated mineral phase particles were collected and X-ray powder diffraction (XRPD) revealed the presence of plumbonacrite (Pb10(CO3)6O(OH)6). After 4 weeks' incubation, the Lead particles that accumulated inside the fungal pellets were transformed into a white Lead-containing secondary mineral phase. Energy dispersive X-ray analysis (EDXA) and XRPD were used to attempt to identify the Lead-containing secondary minerals produced. XRPD showed that Lead oxalate (PbC2O4) and cerussite (PbCO3) were present as Lead mineral species. However, another mineral phase was present that was not identifiable by XRPD. Fourier transform infrared spectroscopy (FTIR) identified h...
-
Pyromorphite formation in a fungal biofilm community growing on Lead Metal.
Environmental microbiology, 2014Co-Authors: Young Joon Rhee, Stephen Hillier, Helen Pendlowski, Geoffrey M. GaddAbstract:Summary Lead is a priority pollutant, and Lead Metal is widely found in the environment as a waterproofing structural component in roofing, fence post covers, venting and flashing, as well as in industrial and urban waste. However, little is known of microbial interactions with Metallic Lead. The objective of this research was to investigate fungal roles in transformations of Lead in a surface biofilm community growing on Lead sheeting. The Lead surface was found to support a diverse fungal community with several members, such as Aureobasidum pullulans, Phoma macrostoma, Penicillium sp. and Botryotinia fuckeliana, probably originating from adjacent phylloplane communities. Many fungal isolates showed tolerance to Lead compounds in growth inhibition assays and were able to mediate production of Lead-containing secondary minerals in the presence of Metallic Lead. These exhibited widely differing morphologies to the Lead-containing secondary minerals produced under abiotic conditions. The presence of pyromorphite (Pb5(PO4)3Cl) (approximately 50 wt%) was detected in the Lead sheet biofilm, and we speculate that animal (bird) faeces could be a significant source of phosphorus in this location. Pyromorphite formation represents biomineralization of mobile Lead species into a very stable form, and this research provides the first demonstration of its occurrence in the natural environment.
-
Lead Transformation to Pyromorphite by Fungi
Current biology : CB, 2012Co-Authors: Young Joon Rhee, Stephen Hillier, Geoffrey M. GaddAbstract:Summary Lead (Pb) is a serious environmental pollutant in all its chemical forms [1]. Attempts have been made to immobilize Lead in soil as the mineral pyromorphite using phosphate amendments (e.g., rock phosphate, phosphoric acid, and apatite [2–5]), although our work has demonstrated that soil fungi are able to transform pyromorphite into Lead oxalate [6, 7]. Lead Metal, an important structural and industrial material, is subject to weathering, and soil contamination also occurs through hunting and shooting [8, 9]. Although fungi are increasingly appreciated as geologic agents [10–12], there is a distinct lack of knowledge about their involvement in Lead geochemistry. We examined the influence of fungal activity on Lead Metal and discovered that Metallic Lead can be transformed into chloropyromorphite, the most stable Lead mineral that exists. This is of geochemical significance, not only regarding Lead fate and cycling in the environment but also in relation to the phosphate cycle and linked with microbial transformations of inorganic and organic phosphorus. This paper provides the first report of mycogenic chloropyromorphite formation from Metallic Lead and highlights the significance of this phenomenon as a biotic component of Lead biogeochemistry, with additional consequences for microbial survival in Lead-contaminated environments and bioremedial treatments for Pb-contaminated land.
Jae-woo Ahn - One of the best experts on this subject based on the ideXlab platform.
-
recovery of copper tin and Lead from the spent nitric etching solutions of printed circuit board and regeneration of the etching solution
Hydrometallurgy, 2003Co-Authors: Man-seung Lee, Jong-gwan Ahn, Jae-woo AhnAbstract:Abstract In order to recover valuable Metals and regenerate the etching solution from the spent nitric etching solutions of printed circuit board (PCB), solvent extraction, stripping, electrowinning, precipitation and cementation experiments have been performed. Nitric acid was selectively extracted by TBP from the spent etching solution and pure nitric acid solution was stripped by distilled water. After extracting nitric acid, pure copper Metal was obtained by electrowinning and tin ions were precipitated by adjusting the pH of solution with Pb(OH) 2 . Lead Metal with purity of 99% was obtained by cementation with iron powder.