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Advances in Chemical Engineering and Science 2013年第3期3卷 171-177页

作者： Alejandro Valenzuela Jesús L. Valenzuela josé R. parga Department of Chemical Engineering and Metallurgy University of Sonora Hermosillo México

The majority of the refractory gold and silver occurs in occlusion in sulphides, then precious metal dissolution is possible by first oxidizing auriferous sulfide concentrate using sodium hypochlorite-sodium-hydroxide solution followed of pressure cyanidation of the oxidized concentrate, for the extraction of precious metals. This process was conducted and evaluated under cyanide and oxygen pressure. This versatile approach offers many advantages, including low temperatures, low pressure and less costly materials of construction than conventional pressure oxidation. In this study, the effect of oxygen pressure, concentration of sodium hypochlorite, temperature, and initial pH, in precious metals recovery and As removal were evaluated using a 24 factorial design. Characterization of the ores showed that pyrite and arsenopyrite were the main minerals present on the concentrate. The best results for gold extraction were obtained with oxygen pressure of 80 psi, 10% (w/w) sodium hypochlorite, temperature of 80℃, at pH = 13, and a constant stirring speed of 600 rpm. These conditions allowed an approximated 60% of gold and 90% of silver extractions in 1 hr.

关键词： Refractory Gold Concentrate Hypochlorite Oxidation Pretreatment Pressure Cyanidation

Removal of Aqueous Lead and Copper Ions by Using Natural Hydroxyapatite Powder and Sulphide Precipitation in Cyanidation Process

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Materials Sciences and Applications 2013年第4期4卷 231-237页

作者： josé Refugio parga Jesús Leobardo Valenzuela Víctor Vazquez Mario Rodriguez Héctor Moreno Departament of Chemical Engineering and Metallurgy University of Sonora Hermosillo Mexico Department of Chemistry Institute Technology of Laguna Torreon Mexico Department of Metallurgy and Materials Science Institute Technology of Saltillo Saltillo Mexico

Mining, ore processing, and smelting activities have contaminated soil and water resources with cyanide and heavy metals throughout the world. In-situ chemical immobilization is a remediation technology that decreases the concentrations of dissolved ions of copper cyanide and lead hydroxides by adsorption or precipitation. This study deals, with a process to recover lead hydroxides with natural hydroxyapatite powder and copper cyanide ions with sulphide precipitation from solutions of the cyanidation process. This technology is based on inducing nucleated precipitation of copper and silver in a serpentine reactor, using sodium sulfide as the precipitator, and sulfuric acid for pH control. Results show that pH value has a significant effect on copper cyanide removal efficiency, and it was determined the optimal pH range to be 2.5 - 3. At this pH value, the copper cyanide removal efficiency achieved was up to 99% with 60 percent of copper purity and the cyanide ions associated with this complex the recovery was 90%. For the elimination of lead hydroxides ions from the aqueous cyanidation process with natural hydroxiapatite powder the recovery was 99%. The abundance of cow bones, its low price and non-aggressive nature towards the environment are advantages for its utilization in point of view of wastewater cleanup and Dore with higher quality.

关键词： Natural Hydroxyapatite Sulphide Precipitation Zinc Cementation

Copper and Cyanide Recovery in Cyanidation Effluents

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Advances in Chemical Engineering and Science 2011年第4期1卷 191-197页

作者： josé R. parga Jesús L. Valenzuela Héctor Moreno Jaime E. Pérez 不详

Cyanidation is the main process for gold and silver recovery from its ores. In this study, a process is proposed to recover copper and cyanide from barren solutions from the Merrill-Crowe cementation process with zinc dust. This technology is based on inducing nucleated precipitation of copper and silver in a serpentine reactor, using sodium sulfide as the precipitator, and sulfuric acid for pH control. Results show that pH value has a significant effect on copper cyanide removal efficiency, and it was determined the optimal pH range to be 2.5 - 3. At this pH value, the copper cyanide removal efficiency achieved was up to 97 and 99%, when copper concentration in the influent was 636 and 900 ppm. respectively. In this process (sulphidization-acidification-thickening-HCN recycling), the cyanide associated with copper cyanide complexes, is released as HCN gas under weakly acidic conditions, allowing it to be recycled back to the cyanidation process as free cyanide. Cyanide recovery was 90%. Finally, this procedure was successfully run at Minera William in México.

关键词： Precipitation Cyanide Removal Copper Recovery Cyanidation

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

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

New Approach for Lead, Zinc and Copper Ions Elimination in Cyanidation Process to Improve the Quality of the Precipitate

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Materials Sciences and Applications 2015年第2期6卷 117-129页

作者： josé R. parga Jesús V. Valdés Jesús L. Valenzuela Gregorio Gonzalez L. María de J. Pérez T. Francisco Cepeda Department of Materials Science and Metallurgy Technological Institute of Saltillo Saltillo M&eacute xico Departament of Chemical Engineering and Metallurgy University of Sonora Hermosillo M&eacute xico Faculty of Metallurgy University of Coahuila Monclova M&eacute xico

The Merrill-Crowe zinc-precipitation process has been applied worldwide on a large number of operations for recovering gold and silver from cyanide solutions. However, in some of the large plants this precipitate is of low quality, because copper and especially lead are precipitated along with gold and silver resulting in a higher consumption of zinc powder, fluxes in the smelting of the precipitate, formation of mate and short life for crucibles. In this research, a method is proposed to recover lead, zinc and copper cyanide ions from barren solutions, from the Merrill-Crowe process with hydroxyapatite before the filter press. This technology is based on inducing nucleated precipitation of zinc, copper and silver ions in a serpentine reactor, using sodium sulfide as the precipitator and sulfuric acid for pH control. This procedure was successfully applied at WILLIAM Mining and BACIS Mining Group in México.

关键词： Gold-Silver Recovery Hydroxyapatite Merrill-Crowe Sulphide Precipitation

Combined cell-based therapy strategies for the treatment of Parkinson's disease:focus on mesenchymal stromal cells

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Neural Regeneration Research 2023年第3期18卷 478-484页

作者： Jannette Rodríguez-Pallares María García-Garrote Juan A.parga joséLuis Labandeira-García Laboratory of Cellular and Molecular Neurobiology of Parkinson´s Disease Research Center for Molecular Medicine and Chronic Diseases(CiMUS)IDISDepartment of Morphological SciencesUniversity of Santiago de CompostelaSantiago de CompostelaSpain Networking Research Center on Neurodegenerative Diseases(CIBERNED) MadridSpain

Parkinson’s disease is a neurodegenerative condition characterized by motor impairments caused by the selective loss of dopaminergic neurons in the substantia *** is an effective and well-tolerated dopamine replacement ***,levodopa provides only symptomatic improvements,without affecting the underlying pathology,and is associated with side effects after long-term ***-based replacement is a promising strategy that offers the possibility to replace lost neurons in Parkinson’s disease *** studies of transplantation of human fetal ventral mesencephalic tissue have provided evidence that the grafted dopaminergic neurons can reinnervate the striatum,release dopamine,integrate into the host neural circuits,and improve motor *** of the limiting factors for cell therapy in Parkinson’s disease is the low survival rate of grafted dopaminergic *** factors could cause cell death of dopaminergic neurons after grafting such as mechanical trauma,growth factor deprivation,hypoxia,and *** factors play an essential role in the survival of grafted ***,direct,timely,and controllable delivery of neurotrophic factors into the brain faces important *** types of cells secrete neurotrophic factors constitutively and co-transplantation of these cells with dopaminergic neurons represents a feasible strategy to increase neuronal *** this review,we provide a general overview of the pioneering studies on cell transplantation developed in patients and animal models of Parkinson’s disease,with a focus on neurotrophic factor-secreting cells,with a particular interest in mesenchymal stromal cells;that co-implanted with dopaminergic neurons would serve as a strategy to increase cell survival and improve graft outcomes.

关键词： brain repair cell replacement co-grafts dopaminergic neurons fetal ventral mesencephalic tissue mesenchymal stem cells neural grafting neural transplantation neuroblasts neurotrophic factors