Research and development of recycling utilization of used refractories:A review

Due to thermal stability and excellent resistance to slag erosion,the used refractories can be recycled as the main raw material for some refractories.In this article the latest developments about used refractories in metallurgical industry has been reviewed,focusing on the results reported in the past decade.The research and reutilization methods of used refractories were discussed.For the research of used refractories,the results of two aspects,the performance and surface corrosion characteristics,are summarized.Then,the advances in research on recycling technology of several main kinds of used refractories,such as MgO-C,Al2O3-SiC-C,Al2O3-MgO-C,magnesium-chrome,and corundum-spinel refractories were summarized and discussed in detail.Some results of the author’s group were reported等线accompanied by these comments.The microstructure and chemical composition were studied by scanning electron microscopy and energy dispersion spectra,and the properties of the refractories were analyzed.Afterwards,the scope of application of materials was determined according to the classification and analysis of refractories.Finally,the large-scale application of used refractories and an outlook is given to future developments of the entire recycling industry.

Recycling and utilization of coal gasification residues for fabricating Fe/C composites as novel microwave absorbents

Under the background of a transformation of the global energy structure,coal gasification technology has a wide application prospect,but its by-product,the coal gasification residue(CGR),is still not being efficiently utilized for recycling.The CGR contains abundant carbon components,which could be applied to the microwave absorption field as the carbon matrix.In this study,Fe/CGR composites are fabricated via a two-step method,including the impregnation of Fe^(3+)and the reduction process.The influence of the different loading capacities of the Fe component on the morphology and electromagnetic properties is studied.Moreover,the loading content of Fe and the surface morphology of the Fe/CGR can be reasonably controlled by adjusting the concentration of the ferric nitrate solution.Meanwhile,Fe particles are evenly inserted on the CGR framework,which expands the Fe/CGR interfaces to enhance interfacial polarization,thus further improving the microwave-absorbing(MA)properties of composites.Particularly,as the Fe^(3+)concentration is 1.0 mol/L,the Fe/CGR composite exhibits outstanding performance.The reflection loss reaches-39.3 dB at 2.5 mm,and the absorption bandwidth covers 4.1 GHz at 1.5 mm.In this study,facile processability,resource recycling,appropriately matched impedance,and excellent MA performance are achieved.Finally,the Fe/CGR composites not only enhance the recycling of the CGR but also pioneer a new path for the synthesis of excellent absorbents.

New technology for recycling materials from oily cold rolling mill sludge

Oily cold rolling mill （CRM） sludge is one of metallurgical industry solid wastes. The recycle of these wastes can not only protect the environment but also permit their reutilization. In this research, a new process of ＂hydrometallurgical treatment ＋ hydrothermal synthesis＂ was investigated for the combined recovery of iron and organic materials from oily CRM sludge. Hydrometallurgical treatment, mainly including acid leaching, centrifugal separation, neutralization reaction, oxidizing, and preparation of hydrothermal reaction precursor, was first utilized for processing the sludge. Then, micaceous iron oxide （MIO） pigment powders were prepared through hydrothermal reaction of the obtained precursor in alkaline media. The separated organic materials can be used for fuel or chemical feedstock. The quality of the prepared MIO pigments is in accordance with the standards of MIO pigments for paints （ISO 10601-2007）. This clean, effective, and economical technology offers a new way to recycle oily CRM sludge.

A compartment model and numerical analysis of circulatory economy

This paper describes an industrial structure and its equation system of a circular economy for material circulation and builds a system dynamic model for resources recycling utilization based on Compartment Model Theory.A circulation multiplier and its computational formula are defined for measuring the efficiency of resources recycling utilization.The simulated results indicate that the resources recycling utilization can not only realize the amount accumulation of natural resources and improve the resources recycling efficiency but can minimize discharges into natural environment by means of adjustment to each compartment parameter in the circular economy.