Dissolution behavior of Caldag lateritic nickel ore subjected to a sequential organic acid leaching method

The dissolution behavior of Caldag lateritic nickel ore subjected to a sequential organic acid leaching method was investigated. The effects of the type of organic acid, acid concentration, leaching time, and leaching temperature on the lateritic nickel ore were examined. Organic acids were used individually prior to sequential leaching. Citric acid was more effective than the other two acids for the selective leaching of nickel and cobalt. An increase in the citric acid concentration negligibly affected the dissolution of the metals, whereas temperature exhibited a strong beneficial effect. Oxalic acid was determined to be the most appropriate organic acid for the second leaching step. After 8 h（4 h ＋ 4 h） of leaching with organic acids（0.5 M citric ＋ 0.5 M oxalic） in sequence at 90°C, 89.63% Ni, 82.89% Co, and 69.63% Fe were leached from the lateritic nickel ore. A sequential citric ＋ oxalic acid leaching method could represent a viable alternative for the dissolution of metals from lateritic nickel ore.

Template-free preparation of porous Co microfibers from spent lithium-ion batteries as a promising microwave absorber

In order to take full advantage of the secondary resources,in this paper,we reported a template-free process to prepare porous Co microfibers from spent lithiumion batteries(LIBs).First,the waste LiCoO_(2) powders were leached by oxalic acid at a suitable temperature,and rodlike cobalt oxalate powders were obtained.Second,the porous Co microfibers were prepared by using the cobalt oxalate as precursors through a thermal decomposition at420 ℃ under nitrogen atmosphere.The prepared Co microfibers possess diameters of 1-2 μm,and each microfiber consists of small particles with size of100-200 nm.The Co microfibers(25 wt%)/paraffin composite exhibited excellent microwave absorption performance.When the sample thickness is 4.5 mm,the reflection losses reach-36.14 and-38.20 dB at 4.16 and 17.60 GHz,respectively,and the effective bandwidth reaches up to 5.52 GHz.This indicates that the Co microfibers can be used as a promising microwave absorber.Therefore,this paper demonstrates a novel process to make a high value-added product through recycling from the spent lithium-ion batteries.In addition,it is advantageous to eliminate the hazard of spent lithium-ion batteries and electromagnetic radiation to environment and human health.