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In this work, nano-sized manganese ferrite (MnFe2O4) was synthesized through the decomposition of the mixed oxalates. The formation of the spinel manganese ferrite was confirmed by X-ray diffraction analysis. The morphology of the ferrite products was studied by scanning electron microscopy. The particle size, which was determined using the Scherrer formula, ranged from 25 to 30 nm. Magnetic properties of the manganese ferrite were analyzed using a vibrating sample magnetometry technique; a narrow hysteresis loop indicated the MnFe2O4 obtained was a soft ferromagnet. Magnetic properties of the manganese ferrite produced were in agreement with those reported in literature for MnFe2O4 nanoparticles prepared by conventional methods, including co-precipitation and mechanochemical processes. By plotting a series of literature data determined by different authors and techniques, a correlation between saturation magnetisation and particle size has been noted regardless of the synthesis methods. In general, the oxalate method seems to be able to produce nano-manganese ferrite in a shorter time (2–3 h) as compared to other conventional techniques reported in literature (up to 54 h).

Gasifiers are reaction vessels used to process carbon feedstock such as coal and/or petcoke at elevated temperature, high pressure, and in a reducing atmosphere (low oxygen partial pressure) to form CO and H2, called synthesis gas or syngas. Syngas is used as a fuel in power generation or as a feedstock material in chemical production. By-products of the gasification process include unreacted carbon, gases such as CO2 and H2S, and slag formed from mineral impurities or organic metallic compounds in the carbon feedstock that liquefy during gasification. In the gasifier, slags interact with the high chrome oxide refractory liner, causing wear and eventual failure of the refractory lining by two primary means - spalling (structural and chemical) and chemical dissolution. Failure of the refractory lining causes the gasifier to be shut down for repair, with increased service time identified by users as important for greater usage of gasification as an industrial process. Phosphate additions to high chrome oxide refractories have been found to increase service life during commercial service by reducing spalling and lowering chemical dissolution of the refractory liner. The mechanism of how they improve service life is not well understood. The microstructure and physical properties of high chrome oxide refractories with and without phosphate additions removed from a commercial gasifier after approximately eight months of exposure to a coal slag are evaluated in this report, with the emphasis on evaluating slag/refractory interaction in refractory pores. Details of the investigation are presented and possible mechanisms of how phosphate additives improve wear resistance discussed.

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