Metallurgical properties of CaO–SiO_(2)–Al_(2)O_(3)–4.6wt%MgO–Fe_(2)O_(3)slag system pertaining to spent automotive catalyst smelting

The metallurgical properties of the CaO–SiO_(2)–Al_(2)O_(3)–4.6wt%Mg O–Fe_(2)O_(3)slag system,formed by the co-treatment process of spent automotive catalyst(SAC)and copper-bearing electroplating sludge(CBES),were studied systematically in this paper.The slag structure,melting temperature,and viscous characteristics were investigated by Fourier transform infrared(FTIR)spectroscopy,Raman spectroscopy,Fact Sage calculation,and viscosity measurements.Experimental results show that the increase of Fe_(2)O_(3)content(3.8wt%–16.6wt%),the mass ratio of CaO/SiO_(2)(m(CaO)/m(SiO_(2)),0.5–1.3),and the mass ratio of SiO_(2)/Al_(2)O_(3)(m(SiO_(2))/m(Al_(2)O_(3)),1.0–5.0)can promote the depolymerization of silicate network,and the presence of a large amount of Fe_(2)O_(3)in form of tetrahedral and octahedral units ensures the charge compensation of Al^(3+)ions and makes Al_(2)O_(3)only behave as an acid oxide.Thermodynamic calculation and viscosity measurements show that with the increase of Fe_(2)O_(3)content,m(Ca O)/m(SiO_(2)),and m(SiO_(2))/m(Al_(2)O_(3)),the depolymerization of silicate network structure and low-melting-point phase transformation first occur within the slag,leading to the decrease in melting point and viscosity of the slag,while further increase causes the formation of high-melting-point phase and a resultant re-increase in viscosity and melting point.Based on experimental analysis,the preferred slag composition with low polymerization degree,viscosity,and melting point is as follows:Fe_(2)O_(3)content of 10.2wt%–13.4wt%,m(CaO)/m(SiO_(2))of 0.7–0.9 and m(SiO_(2))/m(Al_(2)O_(3))of 3.0–4.0.This work provides a theoretical support for slag design in co-smelting process of SAC and CBES.

Effects of long-term fertilization with different substitution ratios of organic fertilizer on paddy soil

In recent years,the abuse of chemical fertilizers has caused numerous environmental problems,such as soil acidification and compaction.Replacing chemical fertilizers with organic fertilizers can effectively alleviate these problems.However,the effects of alternative organic fertilizers remain unclear.To explore the effects of organic fertilizer substitution on rice yield and paddy soil physicochemical properties and bacterial community structure,we conducted a 5-year experiment using different proportions of organic fertilizer substitution in a double-cropping rice field in Jiangxi,China.Our results showed that replacing chemical fertilizers with organic fertilizers can reduce soil acidification,increase soil organic matter content,nutrient contents,and enzyme activities,improve soil physicochemical properties and microbial community,and enhance soil metabolism.Appropriate organic substitution also had positive effects on rice production.These findings enhance our understanding of the effects of different alternative organic fertilization methods and have important theoretical significance for the promotion of the use of organic fertilizers in the future.

Advanced rechargeable lithium-ion batteries based on bendable ZnCo2O4-urchins-on-carbon-fibers electrodes

A novel class of ZnCo2O4-urchins-on-carbon-fibers matrix has been designed, characterized, and used to fabricate high-performance energy storage devices. We obtained a reversible lithium storage capacity of 1180 mA＇h/g even after 100 cycles, demonstrating the highreversible capacity and excellent cycle life of the as-prepared samples. Tested as fast-charging batteries, these electrodes exhibited a considerable capacity of 750 mA＇h/g at an exceptionally high rate of 20 C （18 A/g）, with an excellent cycle life （as long as 100 cycles）, which are the best high-rate results reported at such a high charge^discharge current density for ZnCo2O4-based anode materials in lithium rechargeable batteries. Such attractive properties may be attributed to the unique structure of the binder-free ZnCo2O4-urchins-on-carbon-fibers matrix. Full batteries were also developed by combining the ZnCo2O4 anodes with commercial LiCoO2 cathodes, which showed flexible/wearable and stable features for use as very promising future energy storage units.