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Abstract:Manganese is an element of interest in metallurgy, especially in ironmaking and steel making, but also in copper and aluminum industries. The depletion of manganese high grade sources and the environmental awareness have led to search for new manganese sources, such as wastes/by-products of other metallurgies. In this way, we propose the recovery of manganese from anodic lodes and scrapings of the zinc electrolysis process because of their high Mn content (>30%). The proposed process is based on a mixed leaching: a lixiviation-neutralization at low temperature (50 • C, reached due to the exothermic reactions involved in the process) and a lixiviation with sulfuric acid at high temperature (150-200 • C, in heated reactor). The obtained solution after the combined process is mainly composed by manganese sulphate. This solution is then neutralized with CaO (or manganese carbonate) as a first purification stage, removing H 2 SO 4 and those impurities that are easily removable by controlling pH. Then, the purification of nobler elements than manganese is performed by their precipitation as sulphides. The purified solution is sent to electrolysis where electrolytic manganese is obtained (99.9% Mn). The versatility of the proposed process allows for obtaining electrolytic manganese, oxide of manganese (IV), oxide of manganese (II), or manganese sulphate.

This manuscript contains an investigation about the influence of the chromium content on the properties of novel graphite–chromium composites obtained by spark plasma sintering (SPS), with great potential application in heat dissipation. Green compacts of 40 mm in diameter were first obtained by uniaxial pressing at 60 MPa, and then the composite was sintered at 1800°C in SPS under vacuum conditions and a pressure of 30 MPa. These sintering conditions involved local liquid phase, which promoted the densification of the composite up to values close to 90%. Different chromium contents were studied, 0, 1, 2, 5, 7, and 10 vol.%, where the best properties (densification, young modulus, electrical conductivity, thermal conductivity, and flexural strength) were obtained in the case of the composite with 7 vol.% Cr: 86.22%, 52.7 GPa, 0.79 MS/m, 264 W/m K, and 38.97 MPa, respectively, measured in the in‐plane direction due to the anisotropic behavior of the composite.