Processing and production of pellets from poor-grade manganese-containing raw materials

there is a review of current researches in the processing of poor-grade manganese raw materials. The variety of manganese minerals caused by the valent state of metal in compounds is demonstrated. Different processing methods for manganese-containing mineral and technogenic raw materials are considered. The process of extraction of manganese from ferruginous manganese ore using reduction roasting and magnetic separation, beneficiation technology of poor-grade manganese ore to improve the ratio of Mn/Fe; processes of beneficiation and sintering of fine ferruginous manganese ore with low manganese content; production of agglomerate from the concentrate of manganese poor-grade ore to produce ferrosilicon manganese are described. Results of the authors researches intended to obtain concentrate from manganese-containing sludge and to produce hardened pellets suitable for melting into ferromanganese on its basis using a new component of the binder are presented.

Semi-conducting mixed-valent X4TCNQI−/II− (X = H, F) charge-transfer complexes with C6H2(NH2)4

A pair of semi-conducting, charge transfer complexes of composition, [C6H2(NH2)4][TCNQ] and [C6H2(NH2)4][F4TCNQ] is described in which the TCNQ and F4TCNQ species each exhibit a -I/-II mixed-valent state.

Roles of multiple-proton transfer pathways and proton-coupled electron transfer in the reactivity of the bis-FeIV state of MauG

The high-valent state of the diheme enzyme MauG exhibits charge–resonance (CR) stabilization in which the major species is a bis-FeIV state with one heme present as FeIV=O and the other as FeIV with axial heme ligands provided by His and Tyr side chains. In the absence of its substrate, the high-valent state is relatively stable and returns to the diferric state over several minutes. It is shown that this process occurs in two phases. The first phase is redistribution of the resonance species that support the CR. The second phase is the loss of CR and reduction to the diferric state. Thermodynamic analysis revealed that the rates of the two phases exhibited different temperature dependencies and activation energies of 8.9 and 19.6 kcal/mol. The two phases exhibited kinetic solvent isotope effects of 2.5 and 2.3. Proton inventory plots of each reaction phase exhibited extreme curvature that could not be fit to models for one- or multiple-proton transfers in the transition state. Each did fit well to a model for two alternative pathways for proton transfer, each involving multiple protons. In each case the experimentally determined fractionation factors were consistent with one of the pathways involving tunneling. The percent of the reaction that involved the tunneling pathway differed for the two reaction phases. Using the crystal structure of MauG it was possible to propose proton–transfer pathways consistent with the experimental data using water molecules and amino acid side chains in the distal pocket of the high-spin heme.

Molecular structure and spectroscopic properties of a nickel-bridged {Ni(Ph3P)}2(μ2–η2, η2-C60)2 dimer

A nickel-bridged fullerene dimer, {Ni(Ph3P)}2(μ2–η2, η2-C60)2, was obtained and studied by X-ray crystallography. Optical and EPR spectra indicated a zero-valent state of Ni and no charge transfer from Ni to C60.