Investigation of an alternative chemical agent to recover valuable
metals from anode slime
· Mehmet Ali Topçu
Received: 10 February 2018 / Accepted: 22 May 2018
© Institute of Chemistry, Slovak Academy of Sciences 2018
Anode slime (AS) including high content of precious metals is a by-product obtained after the electro-reﬁning stage in copper
production. In this study, it is aimed to recover Cu, Au, and Ag from the AS by using 1-butyl-3-methyl-imidazolium hydrogen
) ionic liquid (IL) as a green solvent. The eﬀects of IL concentration, temperature, reaction time and
pulp density on recovery of valuable metals were statistically investigated. A high copper recovery of 87.52% was obtained
under optimum condition as in 60% (v/v) [Bmim]HSO
at 50 °C after 2 h, pulp density at 40 g/L (1/25 solid/liquid ratio).
Also, a remarkable gold recovery as 97.32% has been achieved in 80% (v/v) [Bmim]HSO
at 95 °C after 4 h, pulp density at
40 g/L. Temperature and IL concentration were detected as the most eﬀective parameters for copper and gold recovery from
AS, respectively. Silver could not be recovered from the AS due to the lower solubility in [Bmim]HSO
IL media. According
to experimental results, [Bmim]HSO
could be oﬀered as an alternative leaching agent, instead of conventional solvents, to
recover valuable metals from copper anode slime.
Keywords Anode slime · Recovery · Ionic liquids · 1-Butyl-3-methyl-imidazolium hydrogen sulphate [Bmim]HSO
Today, most of the copper demand in the world is supplied
by the pyrometallurgical treatment of the existing copper
ores in the following order; beneﬁciation, smelting, convert-
ing, ﬁre-reﬁning and electro-reﬁning. Also, in order to pro-
duce copper, considerable eﬀorts are performed by the treat-
ment of copper alloyed scrap with ﬁre and electro-reﬁning
stages. In both cases, copper reﬁnery AS includes valuable
metals such as Au, Ag, Cu, Se, Te, etc. (Kılıç et al. 2013).
In recent years, numerous reviews have been reported on the
treatment processes of AS (Biswas et al. 1998; Hait et al.
2009;Syed 2012; Tokkan et al. 2013; Ranjbar et al. 2014;
Lu et al. 2015), which are carried out by pyrometallurgi-
cal, hydrometallurgical or both of these chemical processes.
Especially, some hydrometallurgical processes such as hot
sulphuric acid leaching, alkali fusion-leaching, thiosulfate
leaching, decopperization, and oxidative leaching stand out
as the main processes to recover the various metals from AS
(Yavuz and Ziyadanoğulları 2000; Li et al. 2015; Xu et al.
2016; Wang et al. 2017; Liu et al. 2014). However, the huge
amount of acid consumption, low metal recovery eﬃciency,
recycling problem of acid waste and releasing the hazard-
ous gases such as acid vapour, volatile organic compounds
and chlorine gas are global diﬃculties of these methods.
For this reason, scientists have focused their eﬀorts to ﬁnd
environmentally sensitive solvents for producing eﬃciently
valuable metals (Hu et al. 2017). Ionic liquids (ILs) are the
most promising chemical solvents for metal production in
hydrometallurgical routes with excellent properties, such as
negligible vapour pressure, non-ﬂammability, thermal stabil-
ity and high conductivity (Tian et al. 2010; Park et al. 2014).
ILs formed fully of organic cations and inorganic/organic
anions have a potential to leach ores and metal oxides
greenly due to having ability to dissolve a wide range of
inorganic and organic compounds (Hu et al. 2017). The ﬁrst
study on metal extraction using ionic liquid was carried out
by Whitehead et al. (2004) with 1-butyl-3-methyl-imidazo-
lium hydrogen sulphate ([Bmim]HSO
) to take out the pre-
cious metals from gold bearing ore. This study was resulted
* Aydın Rüşen
Department of Metallurgical and Material Engineering,
Karamanoğlu Mehmetbey University, 70200 Karaman,