Biosorption is a variant of sorption techniques in which the adsorbent is a material of biological origin. It has become an economic and ecological alternative for the treatment of effluents. Among the biomasses employed in biosorption, algae have emerged as a sustainable solution for producing environmentally friendly adsorbents due to their abundance in seawater and freshwater, profitability, reuse and high metal absorption capacities. Although the research on the use of biosorbents is extensive and has grown in recent years, there are not many cases of their use for the treatment of real industrial solutions, which are more challenging due to the complex composition of metals that results in interference or competition over the functional sites of the biomass. This review aims to highlight the current state of research, focusing on the application of algae biosorption to remove copper from effluents. The most studied metals are those with the most significant health connotations, such as Cd, Cu and Pb. Regarding copper, only 2% of the biosorption works using seaweeds have been applied to real effluents, which leaves a relevant gap to advance the technology in the treatment of polluted solutions.

Due to the progressive fall of the ore grades and the increasingly refractory composition of minerals, concentrating plants have increased which has led to an increase in the generation of tailings. Tailings, especially those obtained in the past, have remaining copper and other valuable species in quantities that can potentially be recovered, such as gold, silver, vanadium, and rare earth elements which transforms this abundant waste into a potential source of precious or strategic metals for secondary mining. One of the techniques of solid–liquid separation that processes solutions with low concentrations of metals corresponds to adsorption, and more recently biosorption, which is based on the use of biological matrices that do not constitute an environmental liability after application. Biosorption occurs as a consequence of the wide variety of active functional groups present in different types of biomass. Bacterial, fungal, plant, and algal biomasses have been described as biosorbents, mainly for the treatment of diluted and simple solutions. This work aims to recover copper from leached tailings using biomass of the red algae Gracilaria chilensis as a biosorbent. The tailing samples were taken from an abandoned deposit, in the north of Chile, and after an acid leaching copper was biosorbed, kinetics of adsorption and the equilibrium isotherms were studied, applying the Freundlich and Langmuir models. Operational parameters such as adsorbent dose, pH, and initial metal concentration were studied.

Leaching is a hydrometallurgical activity widely used in mineral processing, both for metallic and non-metallic ores, and in soil remediation. The dissolution of valuable species by heap leaching is strongly dependent on the design and operating variables, so the study of the influence of these variables on recovery and their optimization for the best performance are attractive tasks for the development of the mining industry. In this work, a methodology is developed that enables the planning and design of leaching systems. This methodology uses a proposed superstructure and a mathematical model to analyze the system behavior and determine the optimal design and operating conditions. The model was generated with a Mixed Integer Nonlinear Programming (MINLP) approach and solved by different solvers under GAMS® software (General Algebraic Modelling System). The Spatial Branch-and-Bound (SBB) solver obtained the global optimum in the shortest times. Based on a case of study for copper leaching, it is demonstrated that the procedure allows achieving optimal design and operational conditions.