Studies of Selective Recovery of Zinc and Manganese from Alkaline Batteries Scrap by Leaching and Precipitation

Recovery of zinc and manganese from scrapped alkaline batteries were carried out in the following way: leaching in H2SO4 and selective precipitation of zinc and manganese by alkalization/neutralization. As a result of non-selective leaching, 95.6–99.7% Zn was leached and 83.7–99.3% Mn was leached. A critical technological parameter is the liquid/solid treatment (l/s) ratio, which should be at least 20 mL∙g−1. Selective leaching, which allows the leaching of zinc only, takes place with a leaching yield of 84.8–98.5% Zn, with minimal manganese co-leaching, 0.7–12.3%. The optimal H2SO4 concentration is 0.25 mol∙L−1. Precipitation of zinc and manganese from the solution after non-selective leaching, with the use of NaOH at pH = 13, and then with H2SO4 to pH = 9, turned out to be ineffective: the manganese concentrate contained 19.9 wt.% Zn and zinc concentrate, and 21.46 wt.% Mn. Better selectivity results were obtained if zinc was precipitated from the solution after selective leaching: at pH = 6.5, 90% of Zn precipitated, and only 2% manganese. Moreover, the obtained concentrate contained over 90% of ZnO. The precipitation of zinc with sodium phosphate and sodium carbonate is non-selective, despite its relatively high efficiency: up to 93.70% of Zn and 4.48–93.18% of Mn and up to 95.22% of Zn and 19.55–99.71% Mn, respectively for Na3PO4 and Na2CO3. Recovered zinc and manganese compounds could have commercial values with suitable refining processes

Scanning electron microscopy and transmission electron microscopy <i>in situ</i> studies of grain boundary migration in cold-deformed aluminium bicrystals

International audienceThe crystallography of recrystallization has been investigated in channel-die deformed pure aluminium bicrystals with {100}/{110} orientations. The microstructural and microtextural changes during the early stages of recrystallization were followed by systematic local orientation measurements using scanning and transmission electron microscopes. In particular, orientation mapping combined with in situ sample heating was used to investigate the formation and growth of new grains at very early stages of recrystallization. Grain boundary migration and 'consumption' of the as-deformed areas was always favoured along directions parallel to the traces of the {111} slip planes that had been most active during deformation

Determining the Mechanical Properties of Solid Plates Obtained from the Recycling of Cable Waste

In this article, the possibility of obtaining a solid plate from waste cable sheaths, by mechanical recycling, i.e., grinding, plasticising and pressing, is discussed&mdash;waste cable sheaths being pure PVC with a slight admixture of silicone. Press moulding was carried out under the following conditions: temperature 135 &deg;C, heating duration 1 h and applied pressure 10 MPa. The yield point of the obtained solid plate obtained was 15.0 + &minus;0.6 MPa, flexural strength 0.94 MPa, yield point 0.47 MPa and Charpy&rsquo;s impact strength 5.1 kJ/m2. The resulting solid plate does not differ significantly from the input material, in terms of mechanical strength, so, from the point of view of strength, that is, from a technical point of view, such promising processing of waste cables can be carried out successfully in industrial practice