Analysis on the development trend of deepwater mining ship technology

The ocean is rich in biological, mineral and power energy. It is a huge "treasure bowl" with enormous inexhaustible wealth that all mankind can't use. With the rapid development of modern science and technology and industry, the demand for marine mineral resources is also increasing. Due to the growing scarcity of terrestrial resources, countries around the world have made the development of marine mineral resources a new strategic goal. After a little ocean, the equipment is the first. This paper introduces the development process of seabed mining vessels and foreign seabed mining vessels, and the development status and gaps of China's seabed mining vessels. Finally, it focuses on the independent design and key technologies of seabed mining vessels, with a view to China's seabed mining technology and equipment. The research and development has reference value and guiding role. 1. The seabed mining ship is a "treasure bowl", which has enormous inexhaustible wealth for all mankind. It is estimated that the total world reserves of manganese nodules ocean seabed of 30,000 tons, only the Pacific have 1.7 trillion tons, of which 400 billion tons of manganese, nickel 16.4 billion tons, 8.8 billion tons of copper, cobalt and 5.8 billion tons. According to the landscape composition and distribution of the position of the world's oceans and ocean floor multi-metallic nodule abundance, composition, geochemical characteristics, the world's oceans are divided into more than 15 metal manganese nodules enclave, which is located in the Pacific Ocean up to eight, distribution There are three in the Atlantic Ocean and four in the Indian Ocean, as shown in Figure 1.

Figure 1 Distribution of seabed oil and manganese nodules in the world's oceans

Subsea mining refers to the collection of solid minerals that are found on the seabed and transported to the surface through a lifting system. In the late 1950s, research on deep sea solid mineral resources mining technology began to be carried out internationally, and research on polymetallic nodule mining technology was emphasized. A submarine mining vessel is a working mother vessel with a certain power and mineral resource storage capacity, and carries a mining machine, a concentrator and a lifting system (mineral conveying system) and its release device, as shown in Figure 2.

Figure 2 Seabed mining ship

Development of foreign seabed mining vessels In the late 1950s, developed countries such as the United States, Britain, France, Germany, Japan, and Canada, as well as the former Soviet Union, began research and development of ocean manganese tuberculosis resource exploration and mining technologies. ●In 1972, Japan conducted a mining test on the continuous chain fighting method, which was to hang a bucket at a certain distance on an 8km long slewing chain, from the bow of the mining ship and the stern. Although these buckets also collected some tuberculosis, the chain was entangled in the operation to terminate the test. ● In 1979, French engineers proposed a shuttle-type mining system solution. The system was conceived by a series of independent collectors (shuttle boats) that could freely sneak into the seabed. After reaching the bottom of the sea, the collectors discharged the ballast and collected the nodules before they floated to the surface. But feasibility studies have shown that the system is too expensive. ● In the 1970s, international research on deep-sea mining technology entered the experimental phase, initially in a traditional wave pool for model testing. The first marine pilot test was followed by the joint venture OMI (Ocean Management Co., Ltd.) , composed of the consortiums of the United States, Japan, Canada, Germany and other countries) successfully completed. ● In 1978, OMI extracted 800 tons of nodules from the 5000 m deep Pacific Ocean. OMI's test used a modified drilling ship as a water surface support mother ship, a 5500m long hoistway, a towed concentrator, successfully tested two lifting systems, namely pneumatic lifting and pump lifting, and tested two ways of collecting ore. : Hydraulic and mechanical means. Immediately thereafter, OMA (Marine Mining Association) and OMCO (Marine Minerals) conducted deep sea mining tests in the Pacific Ocean and successfully collected manganese nodules. ● The MAFUTA mining vessel built in 1983 has a total tonnage of 15,851 tons, a deadweight of 7,935 tons, a length of 169.5 meters and a ship width of 25.7 meters. In the early 1980s, due to the impact of fluctuations in world metal prices and the lack of feasibility studies on environmental impacts of deep-sea mining technologies, the project was finally put on hold, and the focus of the research has since been transferred to deep-sea cobalt-rich crusts. In recent years, the Australian company Nautilus, which is listed in Canada, has conducted commercial exploration and development of deep-sea polymetallic sulphide resources in the exclusive economic zone of Papua New Guinea. In October 2006, Nautilus reached an agreement with the Dutch-based Jan De Nul Company to build special deep-sea mining vessels and cooperate in seabed mining. According to the agreement, Jan De Nul is the owner of the mining vessel, responsible for the construction of the vessel and mining operations, and is responsible for providing a barge, tugboat and other operational equipment, as shown in Figure 3. Nautilus will invest $120 million to build two subsea mining machines, power cables, deep water pumps, 1800 m long pipe and corresponding equipment.

Figure 3 New mining ship

In 2011, Nautilus acquired a 20-year mining lease from Bismarck from Papua New Guinea. The first site, called Solwara1, is about 21 football fields in size, containing 240,000 tons of copper, 25,000 pounds of gold, and silver and zinc , for a total value of $3 billion. To this end, Nautilus prepares the latest deep-sea mining vessel and mining system design for the Solwara1 mine, which will mine precious metals from the world's first large deep-sea mine. Working with a deep-sea excavator specialist, it manufactures three remote-controlled machines: subsea excavators, deep-sea robots and vacuum suction machines that work together to collect ore from the sea floor and pulverize it into particles of appropriate size for transport to the ground. III. Development Status and Gap of China's Submarine Mining Vessels 1. China's licensed manganese nodules mining area China's development of marine mineral resources is later than developed countries, and the development of deep sea mining systems began after the “Eighth Five-Year Plan”. In the late 1970s, China began to conduct exploration investigations on manganese TB in the ocean. In 1990, the State Council approved the application for registration of the mining area to the UN Undersea Preparatory Committee in the name of the China Ocean Mineral Resources Research and Development Association. As a long-term development project of the country, resource exploration and development will be given special investment. In August 1990, China filed a mining application with the United Nations Seabed Preparatory Committee. In 2001 and 2011, it acquired the 75,000-square-kilometer polymetallic nodule resource contract area in the East Pacific International Seabed Area and the Southwest Indian Ocean International Seabed Area. The exclusive exploration rights and priority development rights of the 10,000-square-kilometer polymetallic sulphide resource mining area (see Figure 4).

Figure 4 The Indian Ocean and Pacific Block China Ocean Association applied to the International Seabed Authority for the third mining area located in the cobalt-rich crust area of ​​the Pacific Ocean.

In July 2013, the International Oceans Conference in Jamaica approved the committee's opinion, marking China's official access to the Pacific cobalt-rich crust area, which is the third mining area obtained by the China Ocean Association in the international seabed area. 2. Development status of China's seabed mining vessels China's seabed mining experimental research is still limited to shallow water, and the performance research of deep sea mining systems is not yet mature. Changsha Mining Research Institute, Central South University, Guangdong University of Technology, Wuhan University of Technology and other scientific research institutions have carried out some research work on deep sea mining systems. The main research contents are roughly divided into three parts: mining ship, mining system and lifting system. Regarding the research on mining vessels, there is a small amount of content related to the overall design, and other contents are mainly concentrated on the dynamic positioning system. The research on the mining system is mainly completed by Central South University and Changsha Research Institute of Mining and Metallurgy, involving the development and design of the mining car body, the control of the mining car, and the exploration of obstacle-collecting obstacles. There are also some studies on mining heads. For the analysis of the lifting system, in addition to a small amount of research on economic flow rate, it is mainly carried out for the motion response of the riser. During the 10th Five-Year Plan period, China's deep-sea mining research shallow water gradually moved toward deep water; starting from the "Eleventh Five-Year Plan", China plans to complete the overall design of the 1000m sea trial and its underwater parts such as ore, mining, hydroacoustic, and inspection. Designed and completed a lake test of 300 meters water depth in Fuxian Lake, Yunnan (see Figure 5).

Figure 5 300-meter lake test of Fuxian Lake, Yunnan

In June 2012, China’s manned deep submersible “Zhenlong” 7000m sea trial reached a maximum depth of 7062m, and successfully sat down to create a deep record of China’s manned dive. This shows that China’s deep sea technology is increasingly valued and meaning China has already entered the world in this field (see Figure 6).

Figure 6: Seabed minerals discovered by Xiaolong

The gap between China and abroad in deep sea mining

1 Lack of overall strategic planning China acquired the 75,000 km2 polymetallic nodule resource contract area in the East Pacific International Seabed Area in 2001, and obtained the 10,000 km2 polymetallic sulphide resource mining area in the Southwest Indian Ocean International Seabed Area in 2011, and in July 2013 The exclusive exploration rights and priority development rights of the cobalt-rich crust area of ​​the Pacific Ocean have been obtained. However, China still has no strategic plan for overall exploration and commercial development, and the support of the national ministries is insufficient. 2 Mining technology is not a system Subsea mining technology is the leading industry technology in the future marine industry. We must seize the historical opportunity that the development of the ocean is highly valued by the state, and accelerate the construction of a complete technical system for the exploitation of seabed mineral resources with independent intellectual property rights and technological characteristics. Especially for the breakthrough of key technologies such as mining machines, mining machines, lifting systems and the construction of technical systems. 3 Lagging of the establishment of the seabed mining industry China has already had a certain level of research on submarine mining machines, mining machines and lifting systems. The relevant prototypes have achieved success in the 300m water depth lake test. With the vigorous development of offshore oil and gas exploration and development equipment in recent years, China has made breakthroughs in the design and construction technology of deepwater semi-submersible drilling platforms (such as Offshore Oil 981), deepwater drilling vessels, and deepwater pipelaying vessels. Timely gestation and birth of China's deep-sea mineral resources mining and deep-sea technology equipment manufacturing industry has strategic and practical significance for the formation and development of China's deep-sea industry. 4 Talent mechanism and international cooperation are insufficient. The future of seabed mining will inevitably be placed on a new generation of researchers, strengthen the training of young and middle-aged people, actively learn all aspects of deep-sea mining, and send people to participate in international cooperation research projects to develop international cooperation. In the field of research, we strive to shorten or catch up with the advanced level of international deep-sea mining in a short period of time, and actively carry out technical intelligence research on seabed mining. IV. Research on independent design and key technologies of submarine mining vessels 1. Seabed mineral resources collection technology The cobalt-rich crusts are mainly located on the tops and slopes of seamounts, sea platforms and ridges with water depths of 800m to 3000m, and seamounts with flat tops and steep wings. On the slopes. Submarine polymetallic sulphides refer to volcanic deposits formed by seafloor hydrothermal fluids rich in copper, manganese, zinc and other metals. Polymetallic manganese nodules are mainly distributed in the surface of the Mesozoic or young deep-sea basins, including the Pacific Ocean, the Indian Ocean, and parts of the Atlantic Basin. Subsea mining refers to the collection of solid minerals that are found on the seabed and transported to the surface through a lifting system. The mining technology mainly studies the techniques of positioning, posture, walking, crushing, collecting, measuring and controlling, etc. when the mining operation vehicle is walking on the soft seabed. 2. Submarine mineral production to the surface of the water transfer technology After the collection of submarine minerals, usually using a drag-type mining system, continuous rope bucket (CLB) mining system, automatic shuttle boat mining system and mining combined with pipeline transportation technology. Among them, pipeline lifting is considered to be the most promising lifting method, and pipeline lifting is divided into lifting methods such as hydraulic lifting, pneumatic lifting, pipeline container, light medium and heavy medium. 3. Submarine mining work mother ship technology Submarine mining vessels need to hang large-tonnage underwater equipment (such as mining machines/concentrators, lifting systems, etc.) in the 4,000-6,000 m deep sea and its harsh environment to overcome the heave compensation under wind and wave conditions. Technology; hoisting and recycling of mining machines, conveyor systems and power communication cables, levitation recovery technology and control technology required, and measurement and control technology during this operation; underwater mining during extreme weather such as typhoons during operation Emergency release technology between conveyor system and surface working mother ship; dynamic positioning technology of mining ship under wind, wave and flow; high-precision dynamic positioning technology of mining machine seabed, and navigation and control technology of mining ship dynamic tracking and mining route Monitoring and control technology during collection and transportation; fault diagnosis and repair support technology in mining process. V. Summary mining ship is the working mother ship for mining of seabed mineral resources. The research time of marine mineral resources exploration in China is later than that of developed countries. At present, deep sea mining technology is still in the experimental research stage, and there is a big gap with developed countries. This paper introduces the development process of seabed mining vessels and foreign seabed mining vessels, and the development status and gaps of China's seabed mining vessels. Finally, it focuses on the independent design and key technologies of seabed mining vessels, with a view to China's seabed mining technology and equipment. Research and development has reference value and guiding role.