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HISTORY
Glaerum
limestone mine lies on the north side of the Surnadalsfjord in Nordmore. This
fjord lies almost due east – west and is a continuation of the Halsafjord.
Geologically, most of the Surnadal area belongs to the strata of the
Trondheim field with heavily folded Cambro-Silurian slate. The
Surnadal area is an outcrop from the Trondheim- field, and
Surnadalsynklinalen (the Surnadal syncline) is a well-known geological term
In the green slate in Surnadal there are several parallel limestone veins,
and of particular importance is that which runs from Aarnes at the western
end of the Surnadalsfjord, and up into the valley of Rindalen. The thickness
varies from 0 up to 20 meters and more. Limestone has been found
at level – 100z by diamond drilling. It is this part of the limestone vain
which runs along the Surnadalsfjord which today is of mining interest. The
vein slopes towards the south at an angle varying from 40 to 70 degrees.
It seems clear that the limestone
in Surnadal has been known and used in the valley, at all events locally, for
many years. Old place names indicate this and further remains have been found
of small limekilns of early date. Around the turn of the century (19th to 20th)
industrialists started securing for themselves limestone deposits in
Surnadal. Some exploration was carried out towards the end of First World
War, but operations did not start until 1927.
Practically all the limestone is extracted by underground mining, which adds
to the cost. Three mines have been in operation in this limestone seam.
Further to the west lays Aarnes Limestone mine, which did belong to the
Electric Furnace Products Co. Ltd., Sauda. The mine has been closed in many
decades.
Further east lays Sjoflot Limestone mine, last owned by Aardal og Sunndal
Verk, the mine was shut down in 1960.
East of this there is Glaerum Limestone mine, Until 2002 the mine was owned
by the employees. The mine was taken over by the employees in
1991, from Hydro Aluminium Ltd. In 2002 the Belgium company Lhoist
purchased the mine. Finally in December 2009, the Norwegian company Norock
& Co purchased the mine from Lhoist, and is now running the production.
The limestone in Surnadal is among the best we have in this country. The
following is an average analysis:
Undissolved
........................................................... 0,50 %
Fe2O3
......................................................... 0,06 %
Al2O3
......................................................... 0,25 %
MgCO3
..........................................................1,10 %
CaCO3
........................................................98,09 %
When the Germans during the
occupation (1940/41) were preparing to embark on the expansion of their
aluminium production in Norway, they needed large quantities of limestone for
the planned production of alumna. The mines and quarries which were being worked at that
time were too small to provide the necessary quantity, and it was decided
that Nordag themselves should start their own quarrying or mining operations.
The choice fell on Glaerum in Surnadal. The first plans aimed at an annual
production of limestone of 1,2 mill tons, but this was later reduced to
500,000 tons per year of metallurgical limestone. The plant cost 16 mill. NOK
and was almost ready when the war finished. It has since been partly rebuilt
and expanded in 1957, 1970 and 1972.
Sales have been, and are, to carbide factories, cellulose factories, smelters
and the building industry as granular additive and as filler. In recent years
there has been a large increase in sales for agricultural purposes. 
The deposit is extracted in two main adits at levels 86z and 10z (meters
above sea level). The first years, some of the deposits were
quarried, but this system has been abandoned, to avoid harm to the scenery,
and also to avoid flooding.
Until 1987 shrinkage stoping has proved to be the most suitable method. A
1-metre thick layer of limestone was left on hanging walls and a half metre
thick layer on footwalls, to avoid contamination to the
limestone with slate. Bolting was carried out on both hanging walls and
footwalls.
Loading was from mechanized chutes
into 6 and 8 tons Granby cars, which automatically tip their loads into a
mine silo on level 86, where most of the operations take place today. An
accumulator-driven locomotive provided the traction.
The stopes are about 75 meters long and about 80 meters high. A regular
pattern of pillars is left. The
chutes were built with a centre-to-centre distance of 15 meters, and were
operated by compressed air.
The entire crushing plant and production silos for the old facility are
underground, and use the full height from 10z to 86z.
In 1987, the production in the stopes was stopped. Instead it was started
conventional tunnelling with modern tunnel-rigs. The transportation is now
based on dumpers, and wheel-loaders take care of loading.
In 1972 a new fine fraction plant was built on the surface to supply
limestone to the industry and for agricultural purposes. Here there are five
silos, each with a capacity of 500 tons for the following fractions: 0-1 mm,
1-4 mm, 3-8 mm and 8-16 mm.
Most of the finished product is
shipped from our own 60 meters long quay with a draught of 8 m. Agricultural
limestone is transported by truck to the nearest district. Around
1950 there were a good 100 men employed by the three mines. Today only
Glaerum Limestone mine is operating, with 3 employees.
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