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Evaluation of Bioactive Properties of α and β Wollastonite Bioceramics Soaked in a Simulated Body Fluid

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Journal of Biomaterials and Nanobiotechnology 2018年第3期9卷 263-276页

作者： Luis A.Nunez-Rodriguez Martin A.Encinas-Romero Agustin Gomez-Alvarez Jesus L.Valenzuela-Garcia guillermo C.tiburcio-munive Posgrado en Ciencias de la Ingenieria:Ingenieria Quimica Universidad de SonoraHermosilloMexico Departamento de Ingenieria Quimica y Metalurgia Universidad de SonoraHermosilloMexico

Dense natural wollastonite bioceramics (CaSiO3) were prepared by a sintering method, varying the pressing load and sintering temperature, in order to obtain different phases of wollastonite, and different physical properties in the materials. The products were characterized by TGA-DTA, XRD, FT-IR, SEM-EDS, TEM and XPS techniques. The results indicate the presence of two polymorphic phases of wollastonite, the β-wollastonite and α-wollastonite with a transition temperature of the β phase to α phase at approximately 1250℃. These materials were soaked in a simulated body fluid (SBF) during 1, 2 and 3 weeks, to study their solubility and bioactivity. The effect of different wollastonite phases on the solubility of Ca and Si, as well as the capacity of producing layers of “newly formed apatite” on the surfaces of these materials in SBF solution were analyzed.

关键词： Bioceramics Wollastonite Simulated Body Fluid Bioactivity

Copper Recovery from Barren Cyanide Solution by Using Electrocoagulation Iron Process

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Advances in Chemical Engineering and Science 2013年第2期3卷 150-156页

作者： José R. Parga guillermo tiburcio munive Jesús L. Valenzuela Víctor V. Vazquez Gregorio González Zamarripa Institute Technology of Saltillo Saltillo Mexico

This paper is a brief overview of the role of inducing the nucleated electro winning of copper by using iron electrodes in electrocoagulation (EC) process. Cyanide compounds are widely used in gold ore processing plants in order to facilitate the extraction and subsequent concentration of the precious metal. Owing to cyanide solution employed in gold processing, effluents generated have high contents of free cyanide as well as copper cyanide complexes, which lend them a high degree of toxicity. In this regard, two options for the treatment of cyanide barren solutions has been used;in two ways;first for cyanide destruction by oxidation with the use of the EC process, in theory, has the advantage of decomposing cyanide at the anode and collecting copper simultaneously by a sludge of copper magnetic iron. In both cases excellent performance can be achieved using the high capacity of the bipolar iron EC technology. We found that it is possible to reduce the copper cyanide complex from 720 mg·l-1 to below 10 mg·l-1 within 20 minutes.

关键词： Copper Recovery Electrocoagulation Process Bipolar Iron Electrodes Cyanide

Kinetic Aspects of Gold and Silver Recovery in Cementation with Zinc Power and Electrocoagulation Iron Process

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Advances in Chemical Engineering and Science 2012年第3期2卷 342-349页

作者： Gabriela V. Figueroa Martinez José R. Parga Torres Jesús L. Valenzuela García guillermo C. tiburcio munive Gregorio González Zamarripa Department of Chemical Engineering and Metallurgy University of Sonora Hermosillo México Department of Metallurgy and Materials Science Institute of Technology of Saltillo Saltillo México

The Merrill-Crowe or Cementation process is used for concentration and purification of gold and silver from cyanide solutions. Among other available options for recovery of precious metals from cyanide solutions, Electrocoagulation (EC) is a very promising electrochemical technique for the recovery of this precious metals. In this work first, an introduction to the fundamentals of the Merrill Crowe and EC process are given, then Kinetic aspects conditions and results of the both process, for the removal of gold and silver from cyanide solutions are presented, and finally the characterization of the solid products formed during the EC process with X-ray Diffraction and SEM are shown. Results suggests that The cementation of both gold and silver by suspended zinc particles conforms to well-behaved fist order kinetics and for the EC process the results show that is an excellent option to remove Au and Ag from cyanide solution by using iron electrodes. Finally, 99.5% of gold and silver were removed in the experimental EC reactor, and it was achieved in 5 minutes or less.

关键词： Cyanidation Merrill Crowe Electrocoagulation Kinetics

Recovery of Silver from Cyanide Solutions Using Electrochemical Process Like Alternative for Merrill-Crowe Process

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Materials Sciences and Applications 2014年第12期5卷 863-870页

作者： Víctor Vázquez José Parga Jesús L. Valenzuela Gabriela Figueroa Alejandro Valenzuela guillermo munive Department of Chemical Engineering and Metallurgy University of Sonora Hermosillo Mexico Department of Materials Science and Metallurgy Technological Institute of Saltillo Saltillo Mexico

The conventional processes for recovery of silver from cyanide leach solutions are the carbon adsorption, the Merrill-Crowe zinc dust cementation, the Ion Exchange, and Solvent Extraction processes;among other available options for recovery of precious metals from cyanide solutions, Electrocoagulation (EC) is a very promising electrochemical process that does not require high concentrations of silver in cyanide solutions to yield excellent results and neither pretreatment of cyanide solutions like Merrill-Crowe process (deoxygenating and clarification). The present study has been done for the recovery of silver contained in pregnant solution from the cyanidation process using the electrocoagulation technology with iron electrodes, and therefore develops an alternative technology for Merril-Crowe process. The average silver content in pregnant solution was of 52 ppm, recovery was obtained of 99% of silver, with this optimum operating parameters, pH = 8, residence time = 20 minutes and conductivity by addition of sodium chloride = 4 grs/L. Finally the characterization of the solid products formed during the EC process with X-ray Diffraction and Scanning Electronic Microscope was performed, results suggest that magnetite particles and amorphous iron oxyhydroxides are present (Lepidocrocite).

关键词： Electrochemical Process Silver Cyanides Magnetic Fields Merrill-Crowe