182 XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3
however, still does not allow a sufficiently reliable forecast
for a systematic application of this interesting technology.
Therefore, further investigation is required. Some results
achieved with a metal ore of particular complexity are pre-
sented in this paper.
The Polymetallic Schist-Skarn Deposits Hämmerlein
and Tellerhäuser
The polymetallic schist-skarn deposits of Hämmerlein and
Tellerhäuser in Saxony, Germany, shall serve as an example
for a number of similar deposits in Europe. Though they
are smaller in size in comparison with the leading world
class deposits, they may benefit from a number of specific
advantages. They are
• well explored
• located in an area of excellent infrastructure and expe-
rienced work force for restarting mining activities
• close to potential customers
In a recent work, Kern describes the Hämmerlein (and
Tellerhäuser) deposit even as “one of the most promising
and prominent tin exploration targets in the world, with
indium and zinc as potential by-products” (Kern 2019).
As the currently mined easy-accessible and high-grade
tin deposits elsewhere are getting fewer, those complex
tin skarn orebodies have recently become the prime focus
of tin-exploration. Resources and reserves are shown in
Table 1. The deposit contains, however, a number of sig-
nificant by-products such as zinc and indium ores.
The Hämmerlein and Tellerhäuser deposits are closely
linked to each other and shall be considered in this paper
jointly. The Tellerhäuser deposit was exploited already
between 1750 and 1852 for its near surface iron, silver
and zinc ores. Much later, for a few years ending in 1991,
attempts were made to mine the Sn ores of the Tellerhäuser
and the Hämmerlein deposits just to discover that with the
technologies prevailing by then, commercial exploitation
was not viable. Schuppan and Hiller name three reasons for
the poor recovery (Schuppan und Hiller 2012):
• Complex mineralogy, often fine grained
• Variety of Sn-bearing minerals (cassiterite and vari-
ous Sn-bearing silicates)
• Variability of grain sizes of valuable minerals (grain
sizes of cassiterite range from +500 µm to –1 µm)
A revised assessment from 2008 arrives at the conclusion that
“an economic use is potentially possible if the beneficiation
problem is solved” (SMWA 2008). Economic concentra-
tions of Sn are found in metasomatically altered calcium-
silicate rocks called tin skarn, which is the pre-dominant
rock type at Hämmerlein. The major ore mineralization of
the deposit is a cassiterite-chlorite-fluorite-sulfide assem-
blage. Common skarn minerals are garnet, pyroxene, oliv-
ine, pyroxenoid, amphibole, and epidote (Kern 2019). The
main Sn and Zn bearing minerals are cassiterite and sphal-
erite. Cassiterite has a tetragonal structure. It belongs with
a Mohs hardness of 6 to 7 to the hard minerals but it is very
brittle. Its density ranges from ρ =6.3 g/cm3 to 7.2 g/cm3
(Ramdohr 1960). Sn was incorporated into the skarn dur-
ing its formation and was redistributed during the emplace-
ment of the granite along with a new input of Sn into the
skarn. Cassiterite occurs in the amphibole skarn in two dif-
ferent forms, coarse grained cassiterite (up to 10mm) at the
contact between chloritized amphibole and magnetite and
(ii) fine-grained cassiterite (~10 μm) that is disseminated
in the amphibole-quartz assemblage (Lefebvre et al. 2019).
Further cassiterite is to be found in veinlets in the Greisen
in this deposit. The cassiterite beneficiation from Greisen
ore is subject to investigations with Electrodynamic frag-
mentation applying high voltage impulses (Mezzetti et al.
2018) and shall not be further discussed here.
Sphalerite with a Mohs hardness of 3.4 to 4 belongs
to the medium hard minerals. Its density ranges from ρ =
3.9 g/cm3 to 4.2 g/cm3. With a cubical crystal structure, it
can be comparably easily split in the {1,1,0} plane. Those
characteristics will have to be considered with regard to the
behavior in a comminution process.
The exploitation of such deposits is usually challenging
because of their complex mineralogy and fine-grained tex-
tures (Kern 2019). Therefore, the more conventional meth-
ods of grinding and sorting did not work successfully. In
a new attempt, alternative technologies were applied. This
article discusses results of Selective Comminution of coarse
material on impact crusher as secondary comminution step.
Primary comminution was conducted on a jaw crusher,
Table 1. Resources and reserves of the Hämmerlein and Tellerhäuser deposits in Saxony (SMWA 2008)
Deposit
Resources
v Tin Zinc
Tellerhäuser 69.6 kt 6.7 kg/t 31.1 kt 3.0 kg/t 10 Mio t
Hämmerlein 51.6 kt 4.2 kg/t 65.8 kt 9.2 kg/t 12 Mio t
Total kt 96.9 kt 22 Mio t
however, still does not allow a sufficiently reliable forecast
for a systematic application of this interesting technology.
Therefore, further investigation is required. Some results
achieved with a metal ore of particular complexity are pre-
sented in this paper.
The Polymetallic Schist-Skarn Deposits Hämmerlein
and Tellerhäuser
The polymetallic schist-skarn deposits of Hämmerlein and
Tellerhäuser in Saxony, Germany, shall serve as an example
for a number of similar deposits in Europe. Though they
are smaller in size in comparison with the leading world
class deposits, they may benefit from a number of specific
advantages. They are
• well explored
• located in an area of excellent infrastructure and expe-
rienced work force for restarting mining activities
• close to potential customers
In a recent work, Kern describes the Hämmerlein (and
Tellerhäuser) deposit even as “one of the most promising
and prominent tin exploration targets in the world, with
indium and zinc as potential by-products” (Kern 2019).
As the currently mined easy-accessible and high-grade
tin deposits elsewhere are getting fewer, those complex
tin skarn orebodies have recently become the prime focus
of tin-exploration. Resources and reserves are shown in
Table 1. The deposit contains, however, a number of sig-
nificant by-products such as zinc and indium ores.
The Hämmerlein and Tellerhäuser deposits are closely
linked to each other and shall be considered in this paper
jointly. The Tellerhäuser deposit was exploited already
between 1750 and 1852 for its near surface iron, silver
and zinc ores. Much later, for a few years ending in 1991,
attempts were made to mine the Sn ores of the Tellerhäuser
and the Hämmerlein deposits just to discover that with the
technologies prevailing by then, commercial exploitation
was not viable. Schuppan and Hiller name three reasons for
the poor recovery (Schuppan und Hiller 2012):
• Complex mineralogy, often fine grained
• Variety of Sn-bearing minerals (cassiterite and vari-
ous Sn-bearing silicates)
• Variability of grain sizes of valuable minerals (grain
sizes of cassiterite range from +500 µm to –1 µm)
A revised assessment from 2008 arrives at the conclusion that
“an economic use is potentially possible if the beneficiation
problem is solved” (SMWA 2008). Economic concentra-
tions of Sn are found in metasomatically altered calcium-
silicate rocks called tin skarn, which is the pre-dominant
rock type at Hämmerlein. The major ore mineralization of
the deposit is a cassiterite-chlorite-fluorite-sulfide assem-
blage. Common skarn minerals are garnet, pyroxene, oliv-
ine, pyroxenoid, amphibole, and epidote (Kern 2019). The
main Sn and Zn bearing minerals are cassiterite and sphal-
erite. Cassiterite has a tetragonal structure. It belongs with
a Mohs hardness of 6 to 7 to the hard minerals but it is very
brittle. Its density ranges from ρ =6.3 g/cm3 to 7.2 g/cm3
(Ramdohr 1960). Sn was incorporated into the skarn dur-
ing its formation and was redistributed during the emplace-
ment of the granite along with a new input of Sn into the
skarn. Cassiterite occurs in the amphibole skarn in two dif-
ferent forms, coarse grained cassiterite (up to 10mm) at the
contact between chloritized amphibole and magnetite and
(ii) fine-grained cassiterite (~10 μm) that is disseminated
in the amphibole-quartz assemblage (Lefebvre et al. 2019).
Further cassiterite is to be found in veinlets in the Greisen
in this deposit. The cassiterite beneficiation from Greisen
ore is subject to investigations with Electrodynamic frag-
mentation applying high voltage impulses (Mezzetti et al.
2018) and shall not be further discussed here.
Sphalerite with a Mohs hardness of 3.4 to 4 belongs
to the medium hard minerals. Its density ranges from ρ =
3.9 g/cm3 to 4.2 g/cm3. With a cubical crystal structure, it
can be comparably easily split in the {1,1,0} plane. Those
characteristics will have to be considered with regard to the
behavior in a comminution process.
The exploitation of such deposits is usually challenging
because of their complex mineralogy and fine-grained tex-
tures (Kern 2019). Therefore, the more conventional meth-
ods of grinding and sorting did not work successfully. In
a new attempt, alternative technologies were applied. This
article discusses results of Selective Comminution of coarse
material on impact crusher as secondary comminution step.
Primary comminution was conducted on a jaw crusher,
Table 1. Resources and reserves of the Hämmerlein and Tellerhäuser deposits in Saxony (SMWA 2008)
Deposit
Resources
v Tin Zinc
Tellerhäuser 69.6 kt 6.7 kg/t 31.1 kt 3.0 kg/t 10 Mio t
Hämmerlein 51.6 kt 4.2 kg/t 65.8 kt 9.2 kg/t 12 Mio t
Total kt 96.9 kt 22 Mio t