442
J. Antrekowitsch and G. Hanke
The second strategy is to remove gangue compounds like silicon oxide, calcium
oxide, etc. and/or gypsum, which can be often found in higher amounts, due to the
addition of lime, which was done in the past for neutralization.
After investigation of different beneficiation methods, the following conclusions
could be drawn.
– Most of the valuables are evenly distributed over the grain size fractions, produced
by screening. There is a certain concentration in the bigger grains. However, this
fraction is less than 10% of the overall material and its separation does not lead
to an economic benefit. This leads to the fact that no concentration via separation
into different corn fractions is possible.
– Standard magnetic separation was without any effect on concentration.
– The use of a high gradient magnetic separator (HGMS) allowed a certain concentration of copper and zinc but left lead and silver in the remaining fraction. Due
to high costs for the facility itself and the necessity to have all valuables in one
concentrate, this option has not been pursued.
– Flotation showed the option to remove gangue material, and in case the jarosite
mineral itself does not contain too much valuables, a separation between the
jarosite mineral and the rest could be possible.
Flotation—Tests
Flotation tests were performed on different samples out of various dumps.
Due to the fineness of the jarosite precipitates, flotation is seen to represent
the most promising beneficiation technique. To successfully apply flotation, several
challenges must be overcome, such as
– operating flotation in an extremely high ionic strength environment. It is known
that high salinity of the pulp significantly affects the flotation process
– due to the fine particle size distribution of the solids, long residence times might be
required to achieve a satisfying recovery of the material to be floated. The application of pneumatic flotation cells might increase the overall flotation performance
and in particular the grade of the froth product
– due to the complex chemistry in the pulp, changes of the surface chemistry of the
particle are very likely to appear by the forming of layers of undefined structure
and chemistry on the “mineral” surface caused by precipitation
– the forming of microflocs is an issue as non-floating particles will be locked in
flocs built up by hydrophobic particles resulting in a depressed concentrate grade
– the development of a reagent regime which allows to achieve the highest possible
selectivity between “gangue minerals” and “ore minerals” and which is applicable
for a process being fed with a highly variable feed in terms of “mineralogy” and
taking place in an aqueous phase of undefined chemistry.
J. Antrekowitsch and G. Hanke
The second strategy is to remove gangue compounds like silicon oxide, calcium
oxide, etc. and/or gypsum, which can be often found in higher amounts, due to the
addition of lime, which was done in the past for neutralization.
After investigation of different beneficiation methods, the following conclusions
could be drawn.
– Most of the valuables are evenly distributed over the grain size fractions, produced
by screening. There is a certain concentration in the bigger grains. However, this
fraction is less than 10% of the overall material and its separation does not lead
to an economic benefit. This leads to the fact that no concentration via separation
into different corn fractions is possible.
– Standard magnetic separation was without any effect on concentration.
– The use of a high gradient magnetic separator (HGMS) allowed a certain concentration of copper and zinc but left lead and silver in the remaining fraction. Due
to high costs for the facility itself and the necessity to have all valuables in one
concentrate, this option has not been pursued.
– Flotation showed the option to remove gangue material, and in case the jarosite
mineral itself does not contain too much valuables, a separation between the
jarosite mineral and the rest could be possible.
Flotation—Tests
Flotation tests were performed on different samples out of various dumps.
Due to the fineness of the jarosite precipitates, flotation is seen to represent
the most promising beneficiation technique. To successfully apply flotation, several
challenges must be overcome, such as
– operating flotation in an extremely high ionic strength environment. It is known
that high salinity of the pulp significantly affects the flotation process
– due to the fine particle size distribution of the solids, long residence times might be
required to achieve a satisfying recovery of the material to be floated. The application of pneumatic flotation cells might increase the overall flotation performance
and in particular the grade of the froth product
– due to the complex chemistry in the pulp, changes of the surface chemistry of the
particle are very likely to appear by the forming of layers of undefined structure
and chemistry on the “mineral” surface caused by precipitation
– the forming of microflocs is an issue as non-floating particles will be locked in
flocs built up by hydrophobic particles resulting in a depressed concentrate grade
– the development of a reagent regime which allows to achieve the highest possible
selectivity between “gangue minerals” and “ore minerals” and which is applicable
for a process being fed with a highly variable feed in terms of “mineralogy” and
taking place in an aqueous phase of undefined chemistry.