Mining technology of seabed manganese nodules
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Manganese nodule seabed mining system is generally divided into three parts: the seabed mining collector means, the vertical lifting device ore and offshore units of three parts. It is also divided into four parts: mining equipment, lifting devices, mining vessels and measuring and control devices. No matter what the points are, their ore collection and field mines are the key to determining the effectiveness of the mining, and the mining part plays the most important role.
First, the drag mining ship
(1) Single bucket mining ship
A single-deck mining vessel is the easiest way to mine deep seabed manganese nodules. As shown in Figure 1. 
The single-bucket mining vessel is dragged on the front end of the cable and falls to the bottom of the sea; then the trailer is towed along with the ship until it is filled with manganese nodules, and the sea surface is unloaded into the funnel of the ship, and then transported from the funnel through the sand pump. Go to the cargo barge. A sound meter is installed on the mining bucket to let the operator know when the bucket is bottomed and equipped with a TV camera to monitor the working condition of the bucket. This type of mining vessel is simple and inexpensive, and is a convenient way to collect minerals at depths of more than 3,000 meters, but mining efficiency is very low. In order to improve efficiency, the mining bucket should be as large as possible. For a 2000-ton class mining vessel, the most suitable bucket volume is 6.0×36×0.9m, the bucket weight is about 3t; if the loading rate is 65%, the material is collected. The bulk density is 738kg/m 3 , then one bucket can hold 13t, and then 25% of non-ore material is deducted. It is estimated that about 10t of manganese nodules can be obtained per bucket.
Generally, in deep sea operation, the single bucket has a slower lifting speed (the single bucket has a lower speed of 182.58 m/min, and the lifting speed is generally 228.6 m/min, which takes a long time, which increases the mining cost. For example, the depth is 1524 m, At a speed of 457.2m/min, the required power is 2893kW, and the production cost is 18.4 US dollars / ton. In mining 3000m deep, the lifting speed is generally 228.6m / min, and the production cost is 30.6 ~ 41.2 US dollars / ton. Therefore, this method is difficult Get better economic benefits.)
(2) Double bucket mining ship
The double-drum type mining vessel uses a propylene cable-lined trailer, a bucket, a bucket, and a "Z"-shaped route to prevent the two buckets from intertwining, and the mining efficiency can be doubled by a single bucket. Figure 2 shows. The double bucket mining vessel can also use the weight of the trailer to reduce the power consumption of the winch, but this method still does not significantly improve mining efficiency.
(3) Continuous rope bucket mining ship
In order to achieve continuous mining, in 1967, the Japanese man Meng Tianxiong invented a continuous rope bucket mining ship, referred to as the CLB method (Continuous line bucket system). Sumitomo Corporation of Japan and Sumitomo Heavy Industries Co., Ltd. were the mainstays. In 1968, the first test was carried out in the Sagami Bay Sea with a water depth of 1410 m using Donghai University Maru No. 2 (load 714t). In 1970, on the island of Tahiti in the South Pacific, the water depth was 3,760 m, and the 2nd Daidai Maru Ship of the Ocean Company (loading 1422t) was used; the test was successful on a scale of 1/10. In 1972, Mengtian and Mero jointly formed the CLB International Development Consortium. In the Hawaiian waters, the water depth was 3,700 to 5,000 m. The second polar pill (loading 16.692 t) was used, and the test was carried out in 1/2 ratio, and the deep sea photography was tested. With the sonar detection device, it proves that the CLB method has certain development prospects.
The CLB method is essentially the development of a chain bucket sand mining vessel, as shown in Figure 3. It is characterized by a high-strength (tensile strength of 7500MPa) nylon material (polypropylene) made of cable, at a certain interval (25 ~ 50m) on the cable, hanging the bucket, the cable bypasses the friction drive on the ship, A cordless cycle is formed; the cable hopper is towed with the ship to scoop up the manganese TB at the bottom of the sea, thereby basically achieving continuous mining operations.
The CLB method has two modes: single-ship operation and double-ship operation. As shown in Figures 4 and 5.
In the case of single-ship operation, the chain buckets are prone to entanglement with each other, and then improved to double-ship operation, so that the rope spacing is increased, so that the winding problem is basically solved.
At present, the following major technical problems in the CLB method are being studied: (1) preventing the ropes from intertwining; (2) improving the efficiency of loading each chain; (3) increasing the rope width as much as possible and increasing the collection area coverage. Rate; (4) easy to control the acquisition trajectory.
Recently, the Japanese Marine Science and Technology Center, Ms. Meng Tian, ​​studied the successful fluid dynamic separator, which can make the ropes expand in the operation and avoid the entanglement of the ropes, so that the CLB type single ship operation is more suitable.
Second, the pipeline upgrades the mining ship
Pipeline lifting can fully achieve the purpose of continuous mining. As shown in Figure 6. From the mining vessel to transport the pipeline to the seabed, the mining machine collects manganese nodules on the seabed and supplies the pipeline for continuous upgrading.
According to different powers, it can be divided into three ways: hydraulic lifting, air pressure lifting and light medium lifting (collectively referred to as fluid lifting mining methods).
DV (Deep Sea Adventures, USA), AMR (Marine Mineral Resources Development Corporation, United Germany), INCO (International Nickel Corporation, Canada), DOMCD (Development of Deep Seabed Manganese Nodules, Japan) and other companies have carried out pipeline upgrading mining methods test. In 1970, DV Company of the United States in the Atlantic Black Sea, 800m water depth, has tested the three gas lifting mining method, the ship weighs 7500t, the pipe diameter is 24.1cm, the wind pressure is 10.6MPa, and the manganese nodules are collected 10~60t in one hour. The Japan Institute of Pollution Resources also began researching the air-lifting system in 1974 and has achieved results. In 1975, the Kennecott consortium, the US Marine Mining Company in 1978, and the Lockheed Group in June 1980 and 1981 all conducted hydraulic upgrading mining system tests, all of which were successful.
(1) Hydraulic lifting mining ship
Deep sea mining hydropower, (also known as suction mining ship). Different from the concept of land pipeline hydraulic transport.
The suction mining ship designed by the Moscow Mining Institute is shown in Figure 6.
Pipes commonly used aluminum alloy material, and a special float suspended from the ship to bear the majority of the weight of the pipe. The pipeline designed by the Moscow Mining Institute has a pontoon device at the upper and lower sides. In the upper pontoon, a high-pressure water pump is installed, and thus the high-pressure water pipe is passed through the lower pontoon to form a U-shaped conveying pipe. The high-pressure water pipe branches in the lower buoy and is connected to the ejector, thereby guiding the manganese nodules to the silo in the lower pontoon, and then being introduced into the conveying pipe by the high-pressure water and raised to the sea surface. In order to improve the conveying efficiency, a magnetic separation device is arranged in the lower pontoon to separate the mineral and the sand. When the mining vessel moves, in order to avoid bending of the pipeline against the resistance of the water flow, a propulsion device is designed on the pipeline and the buoy.
In order to prevent the pump and motor from malfunctioning and block the pipeline, the safety measures of the discharge valve are installed on the pipeline.
In addition, some have installed a vibration damper in the middle of the pipeline to enable the pipeline to slowly vibrate up and down to adapt to the operation of the mining head; some have stabilizers to control the position and state of the pipeline; some designs Libra-style chords can support pipelines and adapt to changes in seabed topography and sea surface fluctuations to adjust pipe length changes.
(2) Gas pressure lifting mining ship
The air pressure lifting is to use high-pressure air to inject the transportation pipeline, so that the tube is filled with compressed air until the specific gravity of the three-phase flow (manganese nodules, seawater and compressed air) in the tube is smaller than the specific gravity of the seawater, and the seawater pressure outside the tube causes the three-phase flow in the tube to overcome the pipe wall. Rub the resistance and rise to the surface. The position of the compressed air inlet is generally 60% of the total length of the sinking pipe.
(3) Light medium lifting mining ship
The light medium lifting mining system is shown in Figure 9. The lifting principle is exactly the same as the air pressure boost. He Biqi J · B · (J, B, Herbich), who designed a light medium lifting system, is the use of coal as a coal oil medium, kerosene separating means fitted in a ship, the seawater and manganese nodules, kerosene under pressure vessels The pipeline and the vertical transportation pipeline, as well as the mixing chamber for injecting kerosene, the subsea mining head is connected to the pipeline by means of a hinge joint head, and can operate with the sea bottom undulation. This method is expensive and kerosene must be recycled.
3. Submersible mining ship
The mining and upgrading of submersible mining vessels is carried out independently. Mining vessels can be manned or unmanned.
The mining ship uses cheap seized materials, borrows from the sinking into the seabed, collects manganese nodules and fills the cabin, and discards the ballast and floats out of the sea. Such mining vessels generally have both self-propelled and non-self-propelled types; Figure 10 shows an airship submersible mining vessel. Two buoyancy tanks are attached to both sides of the hull. The storage tanks are installed under the hull. The mandibles in the seabed are directly observed by the operating room window, and the mining is carried out. After the storage tanks are filled, the buoyancy tanks are expanded to generate buoyancy. To make the ship surface.
Figure 11 - shows a shuttle-shaped submersible mining vessel.
France's CEA (Automation Research Center) has studied the mining ship and later CFD (Dunkirk Shipbuilding Company) and CNEXO (National Marine Development Center) to participate in the test, and this research has been included in AFERNOD (France Manganese) Tuberculosis Research and Development Association) budget. This type of mining vessel can be designed to sneak into the depth of 6000m, and can control several shuttles to collect from the seabed from the offshore platform. However, according to CEA's 1978 study, only 100 kg of manganese nodules can be collected at a time. This approach is continuing to study improvements.