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H. B. Wang et al.
Introduction
Jarosite residue is a solid waste slag produced in the process of iron removal in
hydrometallurgical zinc plants [1, 2]. It usually contains valuable metals such as
iron, lead, zinc, and copper and contains high value-added metals such as indium
and silver, which have certain economic recovery value. Jarosite residue can exist
stably under certain acidic conditions but it will decompose or hydrolyze and dissolve
heavy metal ions under conditions of environmental pH or temperature rises, resulting
in soil and water pollution [3, 4]. Therefore, jarosite residue is not easy to be piled up
for a long time. It should be treated and utilized in time, otherwise causes waste of
resources and brings potential pollution risks to the surrounding environment. There
are millions of tons of jarosite residue stored in Serbia [5]. The slag storage facilities
for storing jarosite residue are very simple. There are no anti-seepage measures and
no obvious dam construction and protection embankment. The slag reservoir is a
local river and nearby water bodies. The residents face huge potential threats. Next
to the slag bank is a river which poses a huge potential threat to the water area and
residents.
The main purpose of comprehensive treatment of jarosite residue is to solidify and treat priceless substances harmlessly while extracting valuable metals from
jarosite residue. There are two kinds of processes: pyrometallurgy and hydrometallurgy. Pyrometallurgy mainly includes high temperature roasting-magnetic separation method and chlorination roasting method. For example, the roasting-magnetic
separation process proposed by Lu et al. [6] after high temperature reduction roasting
and magnetic separation resulted in an iron grade magnetic separation concentrate
reaching 58.99–58.72%, and the sulfur content is low. Hydrometallurgy mainly uses
sodium hydroxide or ammonia water to decompose jarosite residue. For example,
the ammonia water decomposition jarosite residue process is proposed by Beijing
General Research Institute of Mining and Metallurgy. Ammonia water can decompose 95% jarosite residue, about 60% zinc and copper enter the solution, and 75%
silver remains in the slag. In addition, there is a method of leaching jarosite residue
with concentrated sulfuric acid or hot acid and a combination of pyrometallurgical
and hydrometallurgical treatment. For example, Lan et al. [7] proposed the iron slag
acid leaching–roasting–acid leaching process. The medium–low temperature roasting–NH 4 Cl leaching–alkali leaching process was proposed by Xue et al. [8]. The
pyrometallurgy–hydrometallurgical combined process can select the combination of
processes according to the composition and properties of the materials to achieve
effective leaching of valuable metals.
Jarosite residue is a kind of pollutant and a resource. It adopts an environmentally
friendly treatment method to recover the associated rare precious metals such as lead,
zinc, copper, indium, and bismuth and realizes the resource utilization of valuable
elements. Fixed disposal of invaluable and harmful elements is the trend of jarosite
residue treatment. A new process of calcification, chlorination, and volatilization of
jarosite residue has been developed in this paper. It can not only convert jarosite
residue into general solid waste, but also comprehensively recovers valuable metals
H. B. Wang et al.
Introduction
Jarosite residue is a solid waste slag produced in the process of iron removal in
hydrometallurgical zinc plants [1, 2]. It usually contains valuable metals such as
iron, lead, zinc, and copper and contains high value-added metals such as indium
and silver, which have certain economic recovery value. Jarosite residue can exist
stably under certain acidic conditions but it will decompose or hydrolyze and dissolve
heavy metal ions under conditions of environmental pH or temperature rises, resulting
in soil and water pollution [3, 4]. Therefore, jarosite residue is not easy to be piled up
for a long time. It should be treated and utilized in time, otherwise causes waste of
resources and brings potential pollution risks to the surrounding environment. There
are millions of tons of jarosite residue stored in Serbia [5]. The slag storage facilities
for storing jarosite residue are very simple. There are no anti-seepage measures and
no obvious dam construction and protection embankment. The slag reservoir is a
local river and nearby water bodies. The residents face huge potential threats. Next
to the slag bank is a river which poses a huge potential threat to the water area and
residents.
The main purpose of comprehensive treatment of jarosite residue is to solidify and treat priceless substances harmlessly while extracting valuable metals from
jarosite residue. There are two kinds of processes: pyrometallurgy and hydrometallurgy. Pyrometallurgy mainly includes high temperature roasting-magnetic separation method and chlorination roasting method. For example, the roasting-magnetic
separation process proposed by Lu et al. [6] after high temperature reduction roasting
and magnetic separation resulted in an iron grade magnetic separation concentrate
reaching 58.99–58.72%, and the sulfur content is low. Hydrometallurgy mainly uses
sodium hydroxide or ammonia water to decompose jarosite residue. For example,
the ammonia water decomposition jarosite residue process is proposed by Beijing
General Research Institute of Mining and Metallurgy. Ammonia water can decompose 95% jarosite residue, about 60% zinc and copper enter the solution, and 75%
silver remains in the slag. In addition, there is a method of leaching jarosite residue
with concentrated sulfuric acid or hot acid and a combination of pyrometallurgical
and hydrometallurgical treatment. For example, Lan et al. [7] proposed the iron slag
acid leaching–roasting–acid leaching process. The medium–low temperature roasting–NH 4 Cl leaching–alkali leaching process was proposed by Xue et al. [8]. The
pyrometallurgy–hydrometallurgical combined process can select the combination of
processes according to the composition and properties of the materials to achieve
effective leaching of valuable metals.
Jarosite residue is a kind of pollutant and a resource. It adopts an environmentally
friendly treatment method to recover the associated rare precious metals such as lead,
zinc, copper, indium, and bismuth and realizes the resource utilization of valuable
elements. Fixed disposal of invaluable and harmful elements is the trend of jarosite
residue treatment. A new process of calcification, chlorination, and volatilization of
jarosite residue has been developed in this paper. It can not only convert jarosite
residue into general solid waste, but also comprehensively recovers valuable metals