The aim of this paper was to propose and test a continuous cobalt recovery process from waste mobile phone batteries. The procedure started with dismantling, crushing, and classifying the materials. A study on leaching with sulfuric acid and hydrogen peroxide was carried out with subsequent selective separation of cobalt by means of liquid–liquid extraction. The best extraction conditions were determined based on a sequence of experiments that consisted of selecting the best extractant for cobalt, then assessing the impact of extractant concentration, pH, and contact time on the extraction yield. With these conditions, an extraction isotherm was obtained and correlated with a mathematical model to define the number of extraction stages for a countercurrent process using the McCabe–Thiele method. Then, a similar study was done for stripping conditions and, as a last step, cobalt electroplating was performed. The proposed process offers a solution for the treatment of these batteries, avoiding potential problems of contamination and risk for living beings, as well as offering an opportunity to recover valuable metal.

In this research, the mechanical properties and fracture behavior of composites based on recycled high-density polyethylene and recycled Tetrapack have been investigated. The matrix and filler were recovered from landfills, ground into flakes of $1.6 cm 2 size, washed and physically mixed before putting the mixture in a cast, introduced in an oven at 250 C, and pressed applying 1 Metric Ton pressure. Mixtures with varying concentration of tetrapack flakes were prepared. Mechanical properties such as Young's modulus, yield stress, and ultimate tensile stress were obtained from uniaxial tensile deformation tests carried out at room temperature. The results showed that the tetrapack flakes were effective reinforcers, increasing the Young's modulus and yield stress relative to neat high-density polyethylene. However, it was also found that the filler acts as stress concentrator where mechanical failure initiates. Scanning electron microscopy showed that fracture of the composite occurred mainly by the lack of adhesion between polymer matrix and filler. Moreover, a percolation threshold was reached at about 5% g/g concentration of tetrapack, beyond which mechanical properties are severely compromised. Interestingly, this investigation also showed that the color of the high-density polyethylene flake, that is, the pigment, strongly influences the mechanical properties of the composite. Thus, boards hotpressed from individual colors were also investigated. The results showed that pigments, like those used in gray color, favored higher degree of crystallinity, as measured by differential scanning calorimetry, and therefore higher Young's modulus.

Button cell batteries are used in clocks, thermometers, remote controls, toys and other devices, and they are usually discarded in the trash once its useful life is over. Some models of these batteries contain silver oxide. In this paper we propose liquid-liquid extraction as separation process to recover the metal. First, silver determination is performed in different models of these batteries and leaching with nitric acid is carried out. Affinity study is done between several commercial extractants for silver. The best performing extractant is the bis(2-ethylhexyl) dithiophosphoric acid (D2EHDTPA). Furthermore, a study of the extraction yields as a function of extractant concentration and time is performed. The distribution isotherm is determined; complex extracted in organic phase and stripping conditions have been identified. With the aim of obtaining industrial application, a number of steps for a countercurrent process were defined by the McCabe-Thiele method. Finally, a study was done in micropilot scale. The results show that it is possible to recover silver from this type of waste.

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