Malmberget iron ore mine

Concept study for sinking two new shafts

Client

LKAB

Location

Gällivare, Sweden

Execution period

April 2022

until 2024

Expansion of underground mining opportunities in Malmberget, Sweden

Planning new shafts to develop additional deposits
As part of the strategic development of underground mining, the client is planning to construct at least three new shafts between 2028 and 2036 in order to ensure the long-term security of iron ore production at the Malmberget site. REDPATH DEILMANN visited the second largest underground iron ore mine in the world in March 2023 and presented a comprehensive concept study with a technological assessment, schedule and cost estimate in February 2024.

Technological options for Shaft construction

Method	Description	Advantages	Challenges
Drilling upwards (in sections)	sinking from bottom to top	Safe, compact, energy-efficient	Access from underground required, restricted by geology
Raiseboring with mechanized extension	Pilot bore with subsequent mechanical expansion	Safe, precise, efficient	High personnel requirements, geological restrictions
Raiseboring with blast extension	Combination of pre-drilling and blasting	Flexible, proven, robust	Explosives required, increased risk of accidents
Shaft boring and extension method (SBE)	Mechanized process from the surface	No underground access necessary, high work safety	Time-consuming, high personnel and equipment costs

Preferred variants:

Raiseboring with mechanized widening (possibly supplemented by SBE for diameters up to 10.4 m)
Raiseboring with blasting extension (pilot bore Ø 3 m)

Iron ore has been mined in Malmberget since 1741. The iron ore mine is now one of the largest underground mines in the world.

Construction site equipment and logistics

An area of approx. 130 × 70 m is planned for the sinking facility.
The underground infrastructure includes the supply of electricity, water, fresh water, transportation and communication systems.
Employees are transported to the pit at -1,250 m via a ramp by bus.
Central facilities such as administration, canteen and other operating rooms are located at -1,200 m.
The access tunnels are to be driven in stages to enable the work to be carried out in parallel.

Selection of the shaft diameter

Following a detailed technical and economic assessment, a diameter of 10 m was recommended for shaft 3. The decision was based on a significant reduction in project duration through the use of mechanized processes.

Time required

Project duration:
- Sequential execution: 7-8 years
- Mechanized methods (SBE): Reduction of construction time by up to 30 % or 1,075 days
- Potential cost savings: approx. 10%

Raiseboring with blast extension — Raiseboring pilot hole

Raiseboring overview underground with routes — Mechanized shaft extension at the top section of the shaft with simultaneous raiseboring of pilot hole at the lower part of the shaft

Project details

Scope of work

Preparation of a concept study for the sinking with a planned diameter of 8 m. The shaft extends from around -150 m to -1,430 m. In addition, a variant with a diameter of 10 m for a deeper shaft down to -1,780 m is being investigated.
Detailed evaluation of the two most technically and economically promising options, including time and cost planning

Technical data at a glance

The rock consists of leptites and granites with a rock strength of 180-290 MPa.
A water-bearing horizon (-1,000 m to -1,300 m, approx. 20 m thick) requires targeted sealing measures.
Planned shaft end stages:
- Shaft 1: -1,430 m
- Shafts 2 and 3: -1,780 m
Access tunnel:
- Shaft 1 at -744 m
- Shafts 2 and 3 at -940 m
Extensive consolidation and localized grouting are planned to strengthen the shafts. The shaft lining will be reinforced in some areas.

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