Zinc recovery from spent ZnO catalyst by carbon in the presence of calcium carbonate

Abstract

Zinc recovery from the spent zinc oxide catalyst by carbon in the presence of calcium carbonate was studied using an X-ray diffractometer (XRD), an atomic absorption spectrometer (AAS), and a scanning electron microscope (SEM). The spent zinc oxide catalyst was determined to be composed of 87.5 wt pct zinc oxide and 3.1 wt pct zinc sulfide. The results of X-ray diffractometry revealed that calcium carbonate decomposed to calcium oxide and carbon dioxide; zinc oxide and zinc sulfide were reduced to zinc vapor and carbon monoxide evolving from solid sample; and sulfur content was scavenged as calcium sulfide remained in the solid. Steps involved in this reaction system were summarized to explain the overall reaction. The experimental results of atomic absorption spectrometry showed that the initial rate of zinc recovery and final zinc recovery can be increased by increasing either the sample height, the reaction temperature or the initial bulk density. Furthermore, they were found to increase with decrease in either the argon flow rate, the molar ratio of Zn total /C, the molar ratio of Zn total /CaCO 3 , the grain size of the spent catalyst, the agglomerate size of carbon, or the agglomerate size of calcium carbonate. Empirical expressions of the initial rate of zinc recovery and final zinc recovery have been determined.

Energy harvesting and conversion mechanisms for intrinsic upconverted mechano-persistent luminescence in CaZnOS

“…However, this material will further accelerate these decompositions, as found by Hsu et al 46 Because of the reversible reactions described in eqn (1), the four binary compounds are relatively interacting and competing with each other. Meanwhile, the element S is more active than O 2 at 1200 K, and it will quickly partially transform CaO into CaS after the extraction of pure S through the decomposition of ZnS.…”

Kinetics of the carbothermic reduction of zinc sulfide in the presence of calcium oxide

“…Recently, this carbothermic reduction was found to be an effective method to recover zinc from spent zinc oxide catalyst (Hsu et al, 2004). The spent catalyst, containing zinc oxide and zinc sulfide, was normally generated in a steam reforming process after adsorption of hydrogen sulfide.…”

Growth and optical properties of ZnO nanorods prepared through hydrothermal growth followed by chemical vapor deposition

“…During the synthesis, the reactor pressure was maintained to 10 Torr by adjusting the orifice to the pumping line. The substrate was placed in a position where the temperature is maintained at 580 • C. The overall reactions during the CVD process for the ZnO nanorod growth can be expressed as follows [15]:…”