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Geographic Information Technologies for the Study of Mass Wasting Hazards

International Journal of Geosciences 2014年第5期5卷 519-526页

作者： Henry Pacheco Carlos Suárez universidad pedagógica experimental libertador Instituto Pedagógico de Caracas Departamento de Ciencias de La Tierra. Centro de Investigación “Estudios del Medio Físico Venezolano” Venezuela

The purpose of the research was to obtain the mass wasting hazard map for the state of Vargas, central coast of Venezuela, using GIS technology. The work was developed through the heuristic method with the generation of thematic digital maps, univariate statistical treatment, weighting of each variable and quantifying the relationship of each parameter unit regarding mass wasting processes. The algorithm designed to perform map algebra was designed using the variables: surface geology, slope, slope orientation, terrain curvature, moisture topographic index, power index surface flow rate and capacity sediment transport and the rate normalized difference vegetation. The results show a distribution of landslide hazard with the highest values in the west central part of Vargas state, where the dominant lithology is incompetent, and combined with topographic elements, determining high instability, meanwhile the lower hazard areas were found in specific areas such as the middle watershed areas east of the state. The calibration of this model shows a reliability of 80%, so it is highly advisable to use the information generated in this work by governmental and non-governmental organizations in the planning, management and use of land.

关键词： Mass Wasting Hazards GIS Vargas State Venezuela

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Dissolution Behavior of Gold in Alkaline Media Using Thiourea

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International Journal of Nonferrous Metallurgy 2019年第1期8卷 1-8页

作者： Cristian Vargas Patricio Navarro Daniel Espinoza Jorge Manríquez Erica Mejía Departamento de Ingeniería Metalúrgica Universidad de Santiago de Chile Avda Libertador Bernardo O′Higgins Santiago Chile Grupo de Investigación GIIAM Facultad de Ingeniería Institución Universitaria Pascual Bravo Medellín Colombia

In this work the dissolutive behavior of gold in alkaline medium using thiourea (TU), under different variables, was studied in a theoretical and experimental way, in order to determine the conditions under which it is feasible to dissolve gold in thiourea-alkaline medium. A thermodynamic study was conducted by chemical speciation using the method of Ro-jas-Hernández, together with an electrochemical study where the electric potential was swept in the anodic direction. The main results of the thermodynamic study were that formamidine disulfide (FDS) and sulfinic compounds (S.C.) prevail at alkaline pH;by increasing the initial concen-tration of thiourea at alkaline pH, the presence of the gold complex is al-most zero for any initial concentration of thiourea. By including sodium sulfite in the gold-thiourea system, it was possible to obtain the Au(I)-TU complex at alkaline pH, with a presence of 95.13%. Electrochemical tests allowed verifying that in the absence of sodium sulfite the dissolution of gold in an alkaline medium is very slow but adding sodium sulfite im-provements become evident in the dissolution of the metal. Therefore, sodium sulfite catalyzes the gold dissolution process and stabilizes the thiourea. With this study it was possible to establish the feasibility of using thiourea in an alkaline medium for the dissolution of gold, and the conditions under which it is possible to dissolve the gold in that medium. With these fundamentals and conditions, it is now possible to move forward to test this system for minerals and/or concentrates containing gold.

关键词： Gold Alkaline Thiourea Dissolution Behavior Sodium Sulfite

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