XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 1437
as thesis works by students in collaboration with numerous
Universities globally, supervised by process mineralogists.
The composition of iron oxides and apatite are of particu-
lar interest for LKAB as they infer future product qualities
and potential deleterious elements. Furthermore, mineral
chemical analysis by EPMA and LA-ICP-MS in combi-
nation with textural variability of iron oxides obtained by
OM and SEM-QEMSCAN are used for understanding ore
formation and emplacement environments of IOA deposits
(Krolop 2022, Krolop et al. 2022, Schulz 2022, Miles et
al. 2023). Furthermore, studying textural variability from
macro-to micro-scale will benefit future comminution cir-
cuits coping for variation ranging between banded, massive,
disseminated, skeletal and impregnation style for the asso-
ciation of iron oxides and apatite as can be seen in Figure 2.
Additionally, the target minerals of such investigations
may not be the only minerals of expected economic inter-
est. They can include common minerals closely associated
with the iron oxides and contributing to higher concentra-
tions of deleterious elements in iron ore concentrates such
as Si, K, Na, Mg, S, Ti etc. (e.g., Aupers 2014, Beher 2021,
Kalmbach 2022) or minerals that may be interesting in the
future such as sulfides (Krolop et al. 2023). Currently, sev-
eral studies have been initiated to investigate ore-gangue
associations and mineral chemistry of main phases for the
Leveäniemi, Gruvberget and Mertainen deposits in the
Svappavaara area and the Per Geijer deposit in the Kiruna
area which are under extensive exploration activities.
PROCESS MINERALOGICAL TEST
WORKS
Process mineralogical test works are carried out exclusively
at laboratory scale, mostly in internal laboratories in Kiruna
and Malmberget. Some bench scale test works on composite
samples are also conducted by external partners to develop
preliminary flow-sheet designs. Noteworthy, at LKAB
composite and variability samples are distinguished based
on the purpose of testing and material weight per sample.
Composite samples commonly consist of 15 to 20 merged
rejects to reach sample masses of 80 to 100 kg. They are
used mostly in external test campaigns to establish prelimi-
nary flow sheet designs and comprise one or two samples
per ore domain, e.g., magnetite domain, hematite domain,
mixed iron oxide domain. The domains are commonly pre-
sented in the geological model and reflect the main min-
eral for production. Composite samples target the average
Fe grade for the respective domain as documented in the
recent PERC reports. Contrary, variability samples rather
reflect the entire suite of Fe grade in the respective deposit/
mineral domain based on the reported cut-off grade, cur-
rently 15% Fe for all LKAB deposits. Test works with vari-
ability samples will reflect the actual beneficiation behavior
and allow to predict variation in energy consumption and
achievable degrees of liberation and subsequent quality
variations of concentrates. Sample selection for both com-
posite and variability tests reflects the spatial distribution of
the deposit/mineral domain by selective drill core interval
(reject) sampling.
Depending on the scope, timeframe and prioritization
of the study, comminution and subsequent separation test
works are either conducted by the research engineers (pro-
cess mineralogists) themselves or by quality engineers of
supporting departments such as quality service. Commonly
used equipment for comminution test work are crushers
and steel mills that are operated with rods or balls. Almost
all test works are subject to investigation of ores that are
envisaged to be mined in more than five years from now
and relate to current near mine or field exploration activi-
ties. Therefore, sample material used in process mineral-
ogical investigations originates exclusively from exploration
drill core. Drill cores are subject to chemical assaying for
ore sections and analysed by external certified laborato-
ries. In the process, the core gets cut in half. One half is
used for the aforementioned analyses and the other half
for archiving purposes as required by law. As not all mate-
rial of the crushed half core is used for chemical assaying,
the rest of the material is sent back to LKAB as rejects and
used for geometallurgical (process mineralogical) test works
(Figure 3). The general test work procedure for magnetite
ore is described by dry low-intensity magnetic separation
with a Sala Mörtsell separator, mimicking the sorting pro-
cess at LKAB’s plants, followed by grinding and wet low-
intensity magnetic separation with Davis tube (DT) or
Blue Ribbon. In some cases, flotation test works are con-
ducted to lower phosphorus concentrations in the concen-
trates. However, flotation tests are currently not carried out
Figure 2. Textural variation observed in iron ore from LKAB’s mines with respect to magnetite, hematite and apatite association
as thesis works by students in collaboration with numerous
Universities globally, supervised by process mineralogists.
The composition of iron oxides and apatite are of particu-
lar interest for LKAB as they infer future product qualities
and potential deleterious elements. Furthermore, mineral
chemical analysis by EPMA and LA-ICP-MS in combi-
nation with textural variability of iron oxides obtained by
OM and SEM-QEMSCAN are used for understanding ore
formation and emplacement environments of IOA deposits
(Krolop 2022, Krolop et al. 2022, Schulz 2022, Miles et
al. 2023). Furthermore, studying textural variability from
macro-to micro-scale will benefit future comminution cir-
cuits coping for variation ranging between banded, massive,
disseminated, skeletal and impregnation style for the asso-
ciation of iron oxides and apatite as can be seen in Figure 2.
Additionally, the target minerals of such investigations
may not be the only minerals of expected economic inter-
est. They can include common minerals closely associated
with the iron oxides and contributing to higher concentra-
tions of deleterious elements in iron ore concentrates such
as Si, K, Na, Mg, S, Ti etc. (e.g., Aupers 2014, Beher 2021,
Kalmbach 2022) or minerals that may be interesting in the
future such as sulfides (Krolop et al. 2023). Currently, sev-
eral studies have been initiated to investigate ore-gangue
associations and mineral chemistry of main phases for the
Leveäniemi, Gruvberget and Mertainen deposits in the
Svappavaara area and the Per Geijer deposit in the Kiruna
area which are under extensive exploration activities.
PROCESS MINERALOGICAL TEST
WORKS
Process mineralogical test works are carried out exclusively
at laboratory scale, mostly in internal laboratories in Kiruna
and Malmberget. Some bench scale test works on composite
samples are also conducted by external partners to develop
preliminary flow-sheet designs. Noteworthy, at LKAB
composite and variability samples are distinguished based
on the purpose of testing and material weight per sample.
Composite samples commonly consist of 15 to 20 merged
rejects to reach sample masses of 80 to 100 kg. They are
used mostly in external test campaigns to establish prelimi-
nary flow sheet designs and comprise one or two samples
per ore domain, e.g., magnetite domain, hematite domain,
mixed iron oxide domain. The domains are commonly pre-
sented in the geological model and reflect the main min-
eral for production. Composite samples target the average
Fe grade for the respective domain as documented in the
recent PERC reports. Contrary, variability samples rather
reflect the entire suite of Fe grade in the respective deposit/
mineral domain based on the reported cut-off grade, cur-
rently 15% Fe for all LKAB deposits. Test works with vari-
ability samples will reflect the actual beneficiation behavior
and allow to predict variation in energy consumption and
achievable degrees of liberation and subsequent quality
variations of concentrates. Sample selection for both com-
posite and variability tests reflects the spatial distribution of
the deposit/mineral domain by selective drill core interval
(reject) sampling.
Depending on the scope, timeframe and prioritization
of the study, comminution and subsequent separation test
works are either conducted by the research engineers (pro-
cess mineralogists) themselves or by quality engineers of
supporting departments such as quality service. Commonly
used equipment for comminution test work are crushers
and steel mills that are operated with rods or balls. Almost
all test works are subject to investigation of ores that are
envisaged to be mined in more than five years from now
and relate to current near mine or field exploration activi-
ties. Therefore, sample material used in process mineral-
ogical investigations originates exclusively from exploration
drill core. Drill cores are subject to chemical assaying for
ore sections and analysed by external certified laborato-
ries. In the process, the core gets cut in half. One half is
used for the aforementioned analyses and the other half
for archiving purposes as required by law. As not all mate-
rial of the crushed half core is used for chemical assaying,
the rest of the material is sent back to LKAB as rejects and
used for geometallurgical (process mineralogical) test works
(Figure 3). The general test work procedure for magnetite
ore is described by dry low-intensity magnetic separation
with a Sala Mörtsell separator, mimicking the sorting pro-
cess at LKAB’s plants, followed by grinding and wet low-
intensity magnetic separation with Davis tube (DT) or
Blue Ribbon. In some cases, flotation test works are con-
ducted to lower phosphorus concentrations in the concen-
trates. However, flotation tests are currently not carried out
Figure 2. Textural variation observed in iron ore from LKAB’s mines with respect to magnetite, hematite and apatite association