Printed circuit boards (PCBs) can be an important source of non-ferrous metals (Al, Sn, Zn, and Ni) and precious metals (Au, Ag, Cu, and Pd). With the continuous increase in demand for metals due to the depletion of ores, recycling of this waste is becoming an attractive alternative. The printed circuits also contain hazardous metals, such as Pb, Hg, As, and Cd. Due to the huge increase in the amount of e-waste, the processing of printed circuit boards for metal recovery and proper handling of hazardous substances has a positive effect on the environment. Pyrometallurgical and hydrometallurgical methods are used for the treatment of this waste. Various oxidizing agents are used in the hydrometallurgical processes, including ozone. PCBs from mobile phones were assessed for the recovery of Cu, Sn, and precious metals. The ground and sieved materials were leached in nitric acid, hydrochloric acid, and sulfuric acid at various process parameters, such as leaching time, leaching agent, and temperature. It was found that the best result was obtained using hydrochloric acid with the addition of ozone at 353 K for a period of 4 h to obtain 68.45 g/dm³ of copper. Preliminary results of electrolysis and cementation are also presented.

Metals such as nickel, cobalt, lithium, and manganese are widely used in lithium-ion batteries (LIBs) in electronic devices and electric vehicles. It is forecast that there will be a strong increase in the number of electronic devices and electric vehicles in the coming years. (1) Background: In this paper, the application of ultrasound waves on improving Li, Co, Mn, and Ni leaching efficiency from mixed active cathode materials from different types of LIBs is presented. (2) Methods: Environmentally friendly, low-concentrated (0.75 M) organic acids (oxalic acid, citric acid) and, additionally, sulfuric acid, were used in sonochemical and chemical leaching (stirring process) at a temperature of 60 °C. (3) Results: The results showed significantly higher leaching efficiency of metals with ultrasound-assisted treatment, especially when using organic acids. An average of 50% better leaching results were obtained for Li in oxalic acid (99.6%) and for Co (93.1%) in citric acid during sonochemical leaching. (4) Conclusions: Based on the theory of hydrogen peroxide formation during ultrasound wave transition in solutions, the role of H₂O₂ as one of the most effective reductants used to enhance cobalt, manganese, and nickel leaching from LIBs is indicated.

The continuous steel casting process is characterised by physico-chemical phenomena that are considered in the macro- and microscale. This paper attempts to assess the impact of local changes in the hydrodynamics of liquid steel flow in a one-strand slab tundish on the behaviour of the alloy addition, and consequently, the chemical homogenisation of the liquid steel entering the mould. Four variants of feeding the alloy addition to the liquid steel were considered. Water glass model was used for laboratory experiments. A tracer was fed into the water using the pulse-step method. Based on the mixing curves, the mixing time was calculated. Based on the laboratory experiments carried out, it has been found that, the alloy addition feeding site affects the mixing time, both for symmetric and asymmetric feeding relative to the longitudinal axis of the tundish.

This study investigates copper(II) ion transport through a polymer inclusion membrane (PIM) containing 1-alkyl-1,2,4-triazole (n = 8, 9, 10, 11, 12, 14), o-nitrophenyl octyl ether as the plasticizer and cellulose triacetate as the polymer matrix. The feeding phase was a solution of 0.1 mol/dm³CuCl₂ and an equimolar (0.1 mol/dm³) mixture of copper, nickel, and cobalt chlorides with varying concentrations of chloride anions (from 0.5 to 5.0 mol/dm³) established with NaCl. The receiving phase was demineralized water. The flow rate of the source and receiving phases through the membrane module was within the range from 0.5 cm³/min to 4.5 cm³/min. The tests were carried out at temperatures of 20, 30, 40 and 50 °C. Transport of NaCl through the membrane was excluded for the duration of the test. It was noted that the flow rate through the membrane changes depending on the length of the carbon chain in the alkyl substituent from 16.1 μmol/(m²s) to 1.59 μmol/(m²s) in the following order: C₈> C₉> C₁₀> C₁₁> C₁₂> C₁₄. The activation energy was 71.3 ± 3.0 kJ/mol, indicating ion transport through the PIM controlled with a chemical reaction. Results for transport in case of the concurrent separation of copper(II), nickel(II), and cobalt(II) indicate a possibility to separate them in a selective manner.