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

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

Ten new insights in climate science 2020 – a horizon scan

Non-technical summary We summarize some of the past year's most important findings within climate change-related research. New research has improved our understanding of Earth's sensitivity to carbon dioxide, finds that permafrost thaw could release more carbon emissions than expected and that the uptake of carbon in tropical ecosystems is weakening. Adverse impacts on human society include increasing water shortages and impacts on mental health. Options for solutions emerge from rethinking economic models, rights-based litigation, strengthened governance systems and a new social contract. The disruption caused by COVID-19 could be seized as an opportunity for positive change, directing economic stimulus towards sustainable investments. Technical summary A synthesis is made of ten fields within climate science where there have been significant advances since mid-2019, through an expert elicitation process with broad disciplinary scope. Findings include: (1) a better understanding of equilibrium climate sensitivity; (2) abrupt thaw as an accelerator of carbon release from permafrost; (3) changes to global and regional land carbon sinks; (4) impacts of climate change on water crises, including equity perspectives; (5) adverse effects on mental health from climate change; (6) immediate effects on climate of the COVID-19 pandemic and requirements for recovery packages to deliver on the Paris Agreement; (7) suggested long-term changes to governance and a social contract to address climate change, learning from the current pandemic, (8) updated positive cost–benefit ratio and new perspectives on the potential for green growth in the short- and long-term perspective; (9) urban electrification as a strategy to move towards low-carbon energy systems and (10) rights-based litigation as an increasingly important method to address climate change, with recent clarifications on the legal standing and representation of future generations. Social media summary Stronger permafrost thaw, COVID-19 effects and growing mental health impacts among highlights of latest climate science

Exploring the Roles of Local Mobility Patterns, Socioeconomic Conditions, and Lockdown Policies in Shaping the Patterns of COVID-19 Spread

The COVID-19 crisis has shown that we can only prevent the risk of mass contagion through timely, large-scale, coordinated, and decisive actions. This pandemic has also highlighted the critical importance of generating rigorous evidence for decision-making, and actionable insights from data, considering further the intricate web of causes and drivers behind observed patterns of contagion diffusion. Using mobility, socioeconomic, and epidemiological data recorded throughout the pandemic development in the Santiago Metropolitan Region, we seek to understand the observed patterns of contagion. We characterize human mobility patterns during the pandemic through different mobility indices and correlate such patterns with the observed contagion diffusion, providing data-driven models for insights, analysis, and inferences. Through these models, we examine some effects of the late application of mobility restrictions in high-income urban regions that were affected by high contagion rates at the beginning of the pandemic. Using augmented synthesis control methods, we study the consequences of the early lifting of mobility restrictions in low-income sectors connected by public transport to high-risk and high-income communes. The Santiago Metropolitan Region is one of the largest Latin American metropolises with features that are common to large cities. Therefore, it can be used as a relevant case study to unravel complex patterns of the spread of COVID-19

Chile. Nuevos atributos en los protocolos de emergencia ambiental a considerar en el ámbito de la minería

Reiterados incidentes en faenas mineras sobre la cuenca del río Aconcagua, han generado en la población incertidumbre sobre la calidad del agua lo cual ha profundizado la crisis hídrica en la región de Valparaíso. En este contexto, es necesario que el Estado mejore sus protocolos de manejo de crisis frente a accidentes ambientales, por medio de la inclusión de actores locales. Una respuesta coordinada entre instituciones y comunidades, podría evitar la profundización del conflicto social

Multiperiod Optimisation of Irrigated Crops under Different Conditions of Water Availability

We propose a nonlinear optimisation model which maximises profits by resource allocation on a monthly time scale, considering a monthly crop yield model. The proposed model was applied to six management scenarios (two seasonal and four monthly), nine conditions of water availability, and two situations of resource availability under Chilean conditions. These situations provided the same seasonal amount of resources, but different distributions over time. The model included improvements in water resource management such as water storage and water transactions, being the latter a monthly decision variable that can increase farmers’ profits. According to our results, monthly scenarios gave high profits, even better with appropriate resource distribution. When water costs are high, water transactions allow loss reduction of up to 50%. Regarding labour, the lack of availability is more critical than the wages

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

Simulation of Water-Use Efficiency of Crops under Different Irrigation Strategies

Irrigation management is a key factor in attaining optimal yields, as different irrigation strategies lead to different yields even when using the same amount of water or under the same weather conditions. Our research aimed to simulate the water-use efficiency (WUE) of crops considering different irrigation strategies in the Central Valley of Chile. By means of AquaCrop-OS, we simulated expected yields for combinations of crops (maize, sugar beet, wheat), soil (clay loam, loam, silty clay loam, and silty loam), and bulk density. Thus, we tested four watering strategies: rainfed, soil moisture-based irrigation, irrigation with a fixed interval every 1, 3, 5, and 7 days, and an algorithm for optimal irrigation scheduling under water supply constraints (GET-OPTIS). The results showed that an efficient irrigation strategy must account for soil and crop characteristics. Among the tested strategies, GET-OPTIS led to the best performance for crop yield, water use, water-use efficiency, and profit, followed by the soil moisture-based strategy. Thus, soil type has an important influence on the yield and performance of different irrigation strategies, as it provides a significant storage and buffer for plants, making it possible to produce “more crop per drop”. This work can serve as a methodological guide for simulating the water-use efficiency of crops and can be used alongside evidence from the field