Abstract
An activate pretreatment of zinc-containing metallurgical residues were proposed by adding CaO and introducing microwave heating approach into the CaO activation pretreatment process to realize the conversion of refractory ore phases into pre-treated ore phase. Thermodynamic characteristics analysis indicated that adding CaO can realize the conversion of refractory ore phases, with the same effect as the carbon additives. Thermal conductivity properties analysis denoted that the thermal conductivity properties of ZnS and ZnFe2O4 were relatively poor. Meanwhile, the thermal conductivity properties of the residues sample added with 25% CaO were significantly superior to the residues added with other CaO contents, with the maximum specific heat value of 1.348 J/g·K at 350 °C. Dielectric properties analysis highlighted that adding CaO with the dielectric constant properties significantly higher than that of other substances can enhance the microwave absorption capacity of zinc-containing residues. The decrease in dielectric loss and loss tangent value with the increase of temperature and the residues having large microwave penetration depth guaranteed to obtain better uniformity of microwave heating. Furthermore, adding 25% CaO promoted the microwave penetration depth of the residues sample increased in the range of 300–500 °C. This work can lay a theoretical research foundation for solving the key difficulty for efficient Zn recovery from complex zinc-containing metallurgical residues.
Highlights
Zinc (Zn) endows superior calenderability, corrosion resistance, and wear resistance; thereby it is widely applied in the fields like non-ferrous metallurgy, batteries, automobiles, and building materials [1,2,3]
This study proposed an activate pretreatment of zinc-containing residues by adding low-cost and widely-sourced calcium oxide (CaO), and intended to introduce microwave heating technology into the CaO activation pretreatment process of zinc-containing residues to realize the conversion of refractory ore phase into pre-treated ore phase, further to improve Zn extraction rate
A activate pretreatment approach was proposed with calcium oxide (CaO)
Summary
Zinc (Zn) endows superior calenderability, corrosion resistance, and wear resistance; thereby it is widely applied in the fields like non-ferrous metallurgy, batteries, automobiles, and building materials [1,2,3]. Sphalerite (ZnS) is the main mineral used in industrial preparation of zinc, via an oxidization roasting approach. With the prosperous development of society, the demand for zinc-based materials has increased year by year, which has exacerbated the increase in the mining volume of sphalerite and the decline in grade [4]. Considering the increasing mining volume of zinc ore resources and the importance of processing other zinc-containing hazardous waste resources environmental-friendly, developing and utilizing other zinc-containing hazardous waste resources such as metallurgical residues has significant and sound research value. The residues are produced from the smelting process of metals such as zinc (Zn), lead (Pb), iron (Fe), and copper (Cu), and its output is huge and rising sharply [5,6]. There is an urgent need to develop a clean, efficient and economical method for recovering Zn from metallurgical residues
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