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Study on the mechanism and kinetics of sulfuric acid leaching scandium from rich scandium anatase

He Fei, Gao Likun, Chen Long, Rao Bing, Shen Hairong, Peng Kebo, Gao Guangyan

Physicochemical Problems of Mineral Processing

2022

Vol. 58, iss. 3

art. no. 146171

Scandium and its compounds have excellent properties, and are widely used in cutting-edge fields such as optics, electronics, and alloys. Thus, scandium is an important strategic metal. However, scandium is extremely sparsely distributed in the earth's crust, rarely occurs as an independent mineral, and requires a complex recovery process. Therefore, the study of the extraction of scandium is of great practical significance. This study examined the leaching test and kinetics of scandium under the acid leaching system of refractory anatase ore. Under appropriate two-stage countercurrent leaching conditions, the first stage of the particle size of fraction of -0.074 mm 82.6%, initial H2SO4 concentration of 6 mol/L, leaching temperature of 100 °C, acid/solid ratio of 3 ml/g, stirring speed of 300 rpm, and leaching time of 50 min; and the second stage of the initial H2SO4 concentration of 11 mol/L, leaching temperature of 150 °C, acid/solid ratio of 4 ml/g, stirring speed of 300 rpm, and leaching time of 50 min, a scandium leaching rate of 96.98% was achieved. The kinetics of scandium leaching conformed to a shrinking-core model, and sulfuric acid concentration and temperature were the most important parameters affecting the scandium leaching rate. The kinetic analysis of scandium leaching at different sulfuric acid concentrations showed that as the concentration increased, the sulfuric acid leaching of scandium changed from being chemical reaction-controlled to internal diffusion-controlled, and the apparent reaction order was 1.2429. The kinetics of scandium leaching at different temperatures showed that the sulfuric acid leaching of scandium was reaction-controlled and the apparent activation energy was 42.21 kJ-mol-1.

Stretchable optical fibre sensor for soft surgical robot shape reconstruction

He Yanlin, Gao Likun, Bai Yuchen, Zhu Hangwei, Sun Guangkai, Zhu Lianqing, Xu Haidong

Optica Applicata

2021

Vol. 51, nr 4

589--604

Soft robotics presents several advantages in the field of minimally invasive surgery. However, existing methods have not fully addressed problems related to soft robot shape sensing due to the complex motion of soft robots and the stretchable nature of the soft materials employed. This study demonstrates the shape sensing of a soft robot with a helically embedded stretchable fibre Bragg grating (FBG)-based optical fibre sensor. Unlike straight FBG embedding configurations, this unique helical configuration prevents sensor dislocation, supports material stretchability, and facilitates shape detection for various soft-robot movements. The proposed soft-robot design principle and FBG sensor are analysed and their fabrication process, which includes an FBG-written optical fibre sensor, is described. Bending experiments are conducted with the soft robot, the wavelengths of FBG sensors at different bending and telescopic movement states are obtained, and the soft-robot shape is reconstructed. Experimental results demonstrate that the maximum error between FBG sensing and the actual bending state is less than 2.5%, validating the feasibility and effectiveness of the proposed helical stretchable FBG sensing method for the shape measurement of soft robots. These results indicate the potential and applicability of this shape-sensing approach in biomedical research.

Kinetics of sulphuric acid leaching of titanium from refractory anatase under atmospheric pressure

Gao Likun, Rao Bing, Dai Huixin, Xie Haiyun, Wang Peng, Ma Fangtong

Physicochemical Problems of Mineral Processing

2019

Vol. 55, iss. 2

467--478

Anatase, as an important titanium resource, is attracting more and more attention in research and application. In this study, an efficient process of comprehensively extracting the titanium and other valuable elements from the anatase mineral was proposed. The effect of particle size, stirring speed, initial sulphuric acid concentration, solid-to-liquid ratio, and reaction temperature on the leaching rate of titanium from anatase was investigated. Under appropriate two-stage countercurrent leaching conditions, with the first stage of the liquid-to-solid ratio of 1/3 g/cm3, reaction temperature of 120 °C, initial acid concentration of 11 mol/dm3, residence time of 30 min, stirring speed of 200 rpm, and the second stage of the liquid-to-solid ratio of 1/3 g/cm3, reaction temperature of 200 °C, initial acid concentration of 13 mol/dm3, residence time of 30 min, and stirring speed of 200 rpm, over 99% TiO2, 99% Al2O3, and 97% Sc2O3 were extracted respectively with quartz still remained in the residue. X-ray diffraction, X-ray fluorescence spectrometer, and scanning electron microscopy/energy-dispersive spectroscopy were used to characterize the anatase samples before and after the leaching. Additionally, the leaching kinetics analysis indicated that both acid concentration and temperature were the most significant parameters for the leaching process. And, the titanium leaching reaction rate was controlled by the diffusion of reactants through the residual layer.