With an ore body four kilometers long, 80 meters thick and reaching a depth of two kilometers, LKAB’s Kiruna is the world’s largest, most modern underground iron ore mine. Since exploitation began at the site over 100 years ago, LKAB has produced over 950 million tons of ore, yet only one-third of the ore body has been extracted. Since 2008, Sika is the main supplier for admixtures and underground construction technologies at Kiruna.
Located in Swedish Lapland, north of the arctic circle, the challenges in terms of logistics, admixture storage, and concrete production are manyfold. Sika, together with its partner LKAB took on the challenge many years ago. Today, the LKAB operations are a showpiece of best mining practice for many, large, block cave projects all around the world.
Kiruna is one of the largest, underground sub-level cave operations on the globe. Fast mine-cycle times are key to maintain high productivity and ore throughput rates. Hence, an efficient in-cycle shotcrete set-up is required to install fast, primary support of the newly opened drifts and stopes, providing fast re-entry times into the freshly blasted and secured perimeters. A reliable supply of consumables such as Sika Sigunit®, Sika plasticizers and retarders, as well as a range of other products, are absolutely critical to keep this operation going on a daily basis and to secure the large throughput rates of the concrete batch plants on the surface.
Sprayed concrete must have:
Early strength of 4 MPa at 4h (Hilti method)
28 days strength > 40 MPa
A maximum dosage of accelerator of 10%
A product stability of minimum six months
Open time > 4h
Energy absorption according to ASTM 1550-05 of 490 J
Sika's world-leading Sigunit® and ViscoCrete® technology are among the key elements for the shotcrete and concrete works at Kiruna. Special SCC designs for shaft and ore pass linings were tailored for the specific needs of the ore handling infrastructure and together with LKAB, we developed an easy to handle retardation system for the Atlas cable bolters.
Sika not only offers products that meet all the requirements but also provides continuous customer support on-site for shotcrete production and application. Sika works closely together with the customer, performs experiments on-site, supports the testing and implementation of new technologies and is exploring innovations with the aim of continuous operational improvements.
Sika® ViscoCrete® EVO 36S superplasticizer (HRWR)
SikaTard®-932 consistency stabilizer
SikaAer®-S air entrainer
Sika® Retarder P42 grout retarder for cable bolts
SikaRapid®-1 concrete accelerator
Sikaflex®-11FC i-cure Sealing
Sigunit®-L2712 AF shotcrete accelerator
Sika® Crackstop®, 12 mm fibers
Sika® FastMix® 225 HRWR powder
Sika® Intrapast®-A expansion aid
Sika® NeatCrete concrete remover
Sika® Control®-50 shrinkage reducer
Sikalastic®-841 ST protective coating
Sikaquick®-506 repair mortar
Luossavaara-Kiirunavaara Aktiebolag (LKAB)
LKAB Berg & Betong AB
Sika Sweden SE