Flotation kinetic tracking of sand contaminated with hydrocarbons: image analysis of pulp color changes in time

Abstract

Hydrocarbon contamination in the environment represents a significant challenge. Soil remediation by flotation has been proposed as an effective approach to address this issue. This method entails the separation of hydrophobic compounds, such as soil hydrocarbons, by introducing air into a stirred reactor containing the soil pulp designated for remediation. Experiments were conducted using a 5 L Batch flotation cell to evaluate operating conditions. These experiments focused on obtaining flotation kinetics with different organic mixtures, including fine sands measuring under 150 µm. The experimental design encompassed airflow, hydrocarbon concentration, and surfactant dosage. The research utilized a diluted pulp (3% solids) with a high organic concentration (8 and 17 g/L). Flotation kinetics were measured by developing an innovative technique based on pulp colour and image processing software. This technique facilitated the tracking of concentration changes over time under Beer-Lambert's Law. Subsequently, the results were adjusted using kinetic models commonly employed in mineral flotation, including the First Order, Kelsall, and Klimpel models. This comprehensive analysis sought to elucidate the underlying phenomenology and assess the potential for industrial-scale implementation. The laboratory findings indicate the possibility of achieving recoveries of up to 86.9%, with a first-order kinetic constant of 0.73 (1/min). It is noteworthy that both the gas flow rate and the addition of surfactant exert substantial influence on this constant, consistent with the observed phenomenology of this study. Additionally, the research unveiled the impact of hydrocarbon concentration on kinetics, suggesting an additional mechanism governing hydrocarbon transport.