Reaction kinetics of roasting high-titanium slag with concentrated sulfuric acid

A novel method of roasting high-titanium slag with concentrated sulfuric acid was proposed to prepare titanium dioxide, and the roasting kinetics of titania was studied On the basis of roasting process. The effects of roasting temperature, particle size, and acid-to-ore mass ratio on the rate of roasting reaction were investigated. The results showed that the roasting reaction is fitted to a shrinking core model. The results of the kinetic experiment and SEM and EDAX analyses proved that the reaction rate of roasting high-titanium slag with concentrated sulfuric acid is controlled by the internal diffusion on the solid product layer. According to the Arrhenius expression, the apparent activation energy of the roasting reaction is 18.94 kJ/mol.

Recovery of scandium from silicate minerals by high-pressure leaching in sulfuric acid

This study investigated the leaching of scandium from a Sc-bearing silicate ore.The Sc concentrate obtained by beneficiation pre-enrichment has 1.03×10^(−4) wt%Sc and 14.66 wt%Fe.The main Sc-bearing minerals are limonite,chlorite,sericite,and hornblende,in the form of isomorphism.High-pressure leaching(HPL)with sulfuric acid(98 wt%)and NaF was used to dispose this samples.The Sc leaching efficiency of 91.82%was obtained under the optimum conditions,which are pressure of 5.0×10^(5) Pa,A/O value of 1.1,L/S value of 1.8,NaF dosage of 2 wt%,at 130℃ for 6 h.The X-ray diffraction(XRD)and scanning electron microscopy(SEM)results show that the residue is mainly quartz phase in the multihole shape.Compared with ordinary leaching for silicate,high-pressure leaching has significant advantages in saving acid and energy consumption.

Recovery of titania from high titanium slag by roasting method using concentrated sulfuric acid

By means of energy-dispersive X-ray spectroscopy (EDX) and scanning electron microscope (SEM) analysis, the phase structure characteristics of high titanium slag were analyzed. Through the single factor and the orthogonal experiment methods, the effects of material particle size, mass ratio of acid to ore, roasting temperature, and roasting time on the acidolysis ratio of TiO2 during the process of roasting high titanium slag with concentrated sulfuric acid were systematically investigated. The results show that the sequence of each factor affecting the acidolysis ratio of TiO2 is: mass ratio of acid to ore, roasting time, and roasting temperature. The optimum technological conditions are obtained as mass ratio of acid to ore of 2.1, roasting temperature of 310°C, roasting time of 75min, and material particle size of 45–53μm. The acidolysis ratio of TiO2 is over 96% under the optimum conditions. The roasting process is proved to be significant in the exploitation and utilization of high titanium slag. The advantages of the proposed roasting process are of high efficiency, low power consumption, and minimum pollution.

One-step synthesis of c-caprolactam via the liquid phase catalytic nitrosation of cyclohexane in the presence of concentrated sulfuric acid

A simple and efficient approach for the synthesis of e-caprolactam via the liquid phase nitrosation of cyclohexane and nitrosyl sulfuric acid in the presence of concentrated sulfuric acid has been developed. A series of novel A1VPO composites were prepared by an impregnation method and the composites were then employed to catalyze the nitrosation reaction of cyclohexane and nitrosyl sulfuric acid. Compared to the reaction using fuming sulfuric acid, the selectivity for the desired product was significantly improved using this one-step catalytic process. This method affords a shortcut to prepare ecaprolactam and its analogs from cyclohexane.