Seafloor massive sulphides are a valuable mineral raw material found at the bottom of the deep sea. The ‘Vertical Approach’ is a method for extracting seafloor massive sulphides using the trench cutter method, an established technique in specialist foundation engineering that is operated and supported in the deep-sea environment from a ship on the open sea. As a relatively small-scale intervention with a minimal ecological footprint, this approach is an ideal method for test mining and exploration of deposits up to a depth of 3,000 m.
The approach was conceived in discussions between BAUER Maschinen GmbH and the Harren & Partner Group concerning opportunities to combine the expertise of both companies and to develop new strategies for sustainable mining approaches in accordance with the standards of the International Seabed Authority (ISA). On August 26, a joint venture agreement was signed between the two companies and Seabed Mineral Services GmbH was established. The first stage is to determine the economic viability and, in particular, the environmental compatibility of this Vertical Approach.
“We are thrilled to have found an expert partner in Bauer who is willing – just like us – to seize opportunities and take on a pioneering role in the field of deep-sea mining. Our joint approach for this venture is based on a combination of established technologies. This enables us to minimise the technological risk while at the same time keeping costs down,” says Heiko Felderhoff, Managing Director of Harren & Partner.
Leonhard Weixler, head of the Diaphragm Wall Equipment division at BAUER Maschinen GmbH, adds: “The chemistry between us is very good; we share a similar spirit. This partnership is an ideal union of specialist knowledge and experience in the afield of offshore technologies and services with expertise in the development and production of specialist foundation engineering equipment for onshore and offshore customers around the world.”
Heiko Felderhoff and Leonhard Weixler act as Managing Directors of Seabed Mineral Services GmbH.
The concept behind the Vertical Approach
Deep-sea sampling undeniably has an impact on sensitive deep-sea ecosystems. “Nevertheless, the Vertical Approach makes the utmost effort to minimise the ecological footprint. A serious concern when it comes to deep-sea mining is the stirring up of sediment and the potential impact on sensitive deep-sea species. To prevent fine material from escaping the cutting area, a protective collar is positioned around the cutting wheels at the start and the actual cutting process is protected by the surrounding ore. As a result, fine material from the cutting process remains within this area, while the water mixed with fine sediment and cutting chips is pumped into the ore container.”
The separation process is carried out within the ore container to separate the particles from the sea water via sedimentation. After this treatment, the water is fed back to the cutting wheels and reused in the cutting circuit. This closed system minimises the volume of sea water that is impacted by the cutting process.
Sampling is selective: the template and trench cutter are lowered using a cable winch instead of being initially positioned then moved horizontally along the seafloor. This restricts the sphere of influence to the base area of the template feet and trench cutter. Zones with ore can be clearly separated from zones without ore.
Another aspect of the Vertical Approach that reduces the environmental impact of this method compared to other methods is that only one ‘tool’ is used for extracting material. The soil does not need to be crushed later for transport to the ship. Only the raw material is extracted, with minimal impact on the environment.
