USE OF BIOSOLIDS AS FROTH REAGENT IN FLOTATION PROCESS: CHEMICAL AND PHYSICAL CHARACTERIZATION

Indexación: Web of Science; ScieloRESUMEN: La flotación espumosa usa diversos reactivos, orgánicos e inorgánicos, para aumentar el rendimiento y selectividad del proceso. La flotación utiliza sustancias tensoactivas que se adsorben en la interfase aire/agua. Como potenciales sustitutos de los espumantes usados actualmente, se consideran los residuos orgánicos de origen animal, como los biosólidos. Este estudio, evalúa el uso de biosólidos y ácidos húmicos como agentes espumantes para flotación espumosa, cuantificándose su capacidad tensoactiva y para formar y estabilizar espumas. Biosólidos son capaces de cambiar la tensión superficial de una solución, crear y estabilizar espumas. Dosis menores a 4 g L-1 muestran un afecto tensoactivo mayor comparado con reactivos espumantes, tipo MIBC. Para un uso efectivo de biosólidos, se requiere realizar una etapa de preacondicionamiento, que permita separar la fracción soluble y coloidal que tiene la capacidad tensoactiva. El uso de biosólidos a gran escala necesita investigación adicional para escalar los resultados obtenidos en laboratorio.ABSTRACT: Froth flotation uses various organic and inorganic reagents to increase performance and selectivity of the flotation process. Froth flotation takes place mediated by tensioactive substances that are adsorbed on the air/water interface. Potential substitutes for the currently used frothers, organic wastes of animal origin, like biosolids are found. This study was to evaluate biosolids and humic acids as foaming agents in froth flotation by quantification of their tensioactive capabilities, foam-forming potential and foam stability. Biosolids was able to change the surface tension of a solution, creating and stabilizing foams. Dosages under 4 g L-1 of flotation reagents showed a better tensioactive effect using biosolids instead of conventional flotation reagents, type MIBC. For an effective use of these substances as frothers, it is recommended to consider a preconditioning stage. That stage will permit separating soluble and colloidal fractions that show a tensioactive effect. Further research will be needed in order to scale-up current laboratory assays to operational mining scales.http://ref.scielo.org/y9j24

CO2 adsorption on agricultural biomass combustion ashes

Carbon capture and storage has become an alternative means of confronting global warming. Further research and development into adequate and low-cost materials is required for CO2 adsorption technologies.Samples of fly ash, bottom ash and their respective pellets, produced from wheat bran combustion, were characterized and tested to assess their capacity for CO2 adsorption at different temperatures. Neither the ashes nor their pellets were subject to prior thermochemical activation.The bottom ash sample and its pellets showed a higher adsorption capacity for the majority of the temperatures studied. The pelletized bottom ash reached the maximum adsorption capacity (0,07 mmol CO2/g), followed by the non-pelletized bottom ash (0,06 mmol CO2/g); both at an adsorption temperature of 25°C.CO2 adsorption of bottom ash, from the combustion of wheat bran (agricultural biomass), by a physical adsorption mechanism was demonstrated whereas with the fly ash sample, CO2 adsorption by both physical and chemical adsorption mechanisms was identified

Two-dimensional computational modeling of the electrokinetic remediation of a copper-contaminated soil part i: model validation

A two-dimensional computational model for the electrokinetic remediation of copper from a contaminated soil is presented. The model is an adaptation of the original code developed by one of the authors, in which the chemical composition and transport of the copper species in solution were incorporated. The model includes electromigration, electroosmosis, ordinary diffusion, and convection transport mechanisms, it assumes local chemical equilibrium and unsteady state conditions. An artificially contaminated soil from Cananea, Mexico was used as an example. The model predictions were compared with experimental data collected in a laboratory, circular-shaped soil in which a central anode and four cathodes in the periphery were inserted. A reasonable agreement between the predicted and the experimental values was obtained in terms of the spatial distributions of pH and copper concentration. The potential applications of the computational model are discussed

Assessment of the flotability of chalcopyrite, molybdenite and pyrite using biosolids and their main components as collectors for greening the froth flotation of copper sulphide ores.

Biosolids and representative compounds of their main components ? humic acids, sugars, and proteins ? have been tested as possible environment-friendly collectors and frothers for the flotation of copper sulphide ores. The floatability of chalcopyrite and molybdenite ? both valuable sulphide minerals present in these ores ? as well as non-valuable pyrite was assessed through Hallimond tube flotation tests. Humic acids exhibit similar collector ability for chalcopyrite and molybdenite as that of a commercial collector (Aero 6697 promoter). Biosolids show more affinity for pyrite. The copper recovery (85.9%) and copper grade (6.7%) of a rougher concentrate obtained using humic acids as main collector for the flotation of a copper sulphide ore from Chile, were very similar to those of a copper concentrate produced by froth flotation under the same conditions with a xanthate type commercial collector. This new and feasible end-use of biosolids and humic acids should be new environment-friendly organic froth flotation agents for greening the concentration of copper sulphide ore. Now, further research is needed in order to scale current laboratory assays to operational mining scales to determine efficiencies to industrial scale

Adsorption of biosolids and their main components on chalcopyrite, molybdenite and pyrite: Zeta potential and FTIR spectroscopy studies

Zeta potential measurements were used to assess the electrokinetic characteristics of chalcopyrite, molybdenite and pyrite in the presence of biosolids and their main components (humic acids, glucose and serum albumin) as well as a commercial collector (Aero 6697). Fourier transform infrared spectroscopy (FTIR) was then used to gain a deeper understanding of the interaction of these compounds with these sulfide minerals. It aims to achieve a better understanding of the surface chemistry of sulfide–water interfaces that improve froth flotation at industrial scale in the step of copper sulfide ore concentration. Zeta potential results show that hydrogen and hydroxide ions are potential determining ions for each sulfide mineral studied. The addition of 50 g/t biosolids or all the other chemicals used in this investigation shift the isoelectric point of chalcopyrite. Under the same conditions, only humic acid significantly affects the zeta potential of molybdenite, making it more negative in the pH range investigated, and shifting its isoelectric point about 6 pH units. These compounds seem to have a poor affinity with pyrite surfaces because their zeta potential is slightly modified. FTIR spectroscopy characterization shows that biosolids and their main components can interact with chalcopyrite, molydenite and pyrite surfaces through a complex mechanism involving chemical or physical linkages. The results reported here seem to indicate that biosolids may be used as new environment-friendly froth flotation agents to concentrate copper and molybdenum sulfide mineral

Uso de biosólidos como reactivo espumante en procesos de flotación: caracterización física y química

La flotación espumosa usa diversos reactivos, orgánicos e inorgánicos, para aumentar el rendimiento y selectividad del proceso. La flotación utiliza sustancias tensoactivas que se adsorben en la interfase aire/agua. Como potenciales sustitutos de los espumantes usados actualmente, se consideran los residuos orgánicos de origen animal, como los biosólidos. Este estudio, evalúa el uso de biosólidos y ácidos húmicos como agentes espumantes para flotación espumosa, cuantifi cándose su capacidad tensoactiva y para formar y estabilizar espumas. Biosólidos son capaces de cambiar la tensión superficial de una solución, crear y estabilizar espumas. Dosis menores a 4 g L¯¹ muestran un afecto tensoactivo mayor comparado con reactivos espumantes, tipo MIBC. Para un uso efectivo de biosólidos, se requiere realizar una etapa de preacondicionamiento, que permita separar la fracción soluble y coloidal que tiene la capacidad tensoactiva. El uso de biosólidos a gran escala necesita investigación adicional para escalar los resultados obtenidos en laboratorio

Two-dimensional computational modeling of the electrokinetic remediation of a copper-contaminated soil part ii: Sensitivity analysis for a triangular soil field

The computer model described in the first paper of this series was used to perform a sensitivity analysis for the electrokinetic remediation of a triangular, copper-contaminated soil field in which one anode and two cathodes are placed in the vicinity of the triangle vertices. The input variables included the initial concentration of copper in the soil, the electrical potential applied between electrodes, and the absence or presence of wash water. The output variables included the cleanup efficiency and the fraction of copper eliminated from the soil . Overall, the larger the electrical potential applied between electrodes, the shorter the time to achieve steady state. When no wash water is used, the cleanup efficiency may fluctuate over time before reaching steady state. When wash water is used, the final obtained depends on the initial concentration of copper in the soil.El modelo computacional descrito en el primer artículo de esta serie se usó para realizar un análisis de sensibilidad del proceso de eliminación electrocinética de un campo de suelo triangular contaminado con cobre, en el cual se colocan un ánodo y dos cátodos en la proximidad de los vértices del triángulo. Las variables de entrada incluyeron la concentración inicial de cobre en el suelo, el potencial eléctrico aplicado entre los electrodos, y la ausencia o presencia de agua de lavado. Las variables de salida incluyeron la eficiencia de limpieza y la fracción de cobre eliminado del suelo. En general, a mayor potencial eléctrico aplicado entre los electrodos, menor el tiempo requerido para alcanzar el estado estacionario. Cuando no se usa agua de lavado, la eficiencia de limpieza puede fluctuar en el tiempo antes de alcanzar el estado estacionario. Cuando se usa agua de lavado, el valor final de depende de la concentración inicial de cobre en el suelo

CO2 adsorption on agricultural biomass combustion ashes

Carbon capture and storage has become an alternative means of confronting global warming. Further research and development into adequate and low-cost materials is required for CO2 adsorption technologies.Samples of fly ash, bottom ash and their respective pellets, produced from wheat bran combustion, were characterized and tested to assess their capacity for CO2 adsorption at different temperatures. Neither the ashes nor their pellets were subject to prior thermochemical activation.The bottom ash sample and its pellets showed a higher adsorption capacity for the majority of the temperatures studied. The pelletized bottom ash reached the maximum adsorption capacity (0,07 mmol CO2/g), followed by the non-pelletized bottom ash (0,06 mmol CO2/g); both at an adsorption temperature of 25°C.CO2 adsorption of bottom ash, from the combustion of wheat bran (agricultural biomass), by a physical adsorption mechanism was demonstrated whereas with the fly ash sample, CO2 adsorption by both physical and chemical adsorption mechanisms was identified

Two-dimensional computational modeling of the electrokinetic remediation of a copper-contaminated soil part i: Model validation

A two-dimensional computational model for the electrokinetic remediation of copper from a contaminated soil is presented. The model is an adaptation of the original code developed by one of the authors, in which the chemical composition and transport of the copper species in solution were incorporated. The model includes electromigration, electroosmosis, ordinary diffusion, and convection transport mechanisms, it assumes local chemical equilibrium and unsteady state conditions. An artificially contaminated soil from Cananea, Mexico was used as an example. The model predictions were compared with experimental data collected in a laboratory, circular-shaped soil in which a central anode and four cathodes in the periphery were inserted. A reasonable agreement between the predicted and the experimental values was obtained in terms of the spatial distributions of pH and copper concentration. The potential applications of the computational model are discussed.Se presenta un modelo computacional en dos dimensiones para la eliminación electrocinética de cobre de un suelo contaminado. El modelo es una adaptación del código original desarrollado por uno de los autores, al cual se incorporaron la composición química y el transporte de las especies de cobre en solución. El modelo incluye los mecanismos de transporte por electromigración, electroósmosis, difusión ordinaria y convección, se supone equilibrio químico local y régimen no estacionario. Un suelo natural de Cananea, México se utilizó como ejemplo. Las predicciones del modelo se compararon con datos experimentales obtenidos a nivel laboratorio en un suelo circular con un ánodo central y cuatro cátodos insertados en la periferia. Las predicciones del modelo concordaron razonablemente bien con las distribuciones espaciales de pH y concentración de cobre. Se discuten las aplicaciones potenciales del modelo computacional