Design and Observation Tests of an Experimental Nodule Collection Vehicle

Abstract Authors have been conducting development studies on the ocean mining collector which has a newly developed gathering mechanism using a cutting blade and a plurality of water jet nozzles. Since the nodule gathering mechanism is one of the most important components in the collector system, is very significant to understand its gathering behavior on the seafloor. Therefore, authors constructed a test vehicle and conducted observation tests of the developed mechanism in an indoor test tank and in shallow water. The test vehicle was designed for towing on the sediments with a towing line, because the prime objectives of these tests were to observe and understand the gathering behavior and to obtain in formations for further studies on the mechanism. Both the indoor testing the shallow water tests showed satisfactory results in the function of the nodule gathering mechanism. In the indoor tests, however, sometimes good results could not be obtained. These results were due to a large amount of sediments which was introduced around the cutting blade and ineffectiveness of jet water to carry away the sediments. This shows that it is necessary to perform further studies in order to obtain a suitable design specification of the mechanism. Unsteady jerky motion of the test vehicle was observed on the collection process in the shallow water tests. This suggests that it is also important studies to understand the behavioral pattern when the collector system is towed by the lift pipe string. Introduction The hydraulic mining system for deep sea manganese nodules is the mining method to transport manganese nodules collected by the collector system on the sea floor to the mining ship through the lift system. While the collector system is traveling on the soft sediments of the deep sea floor, collecting manganese nodules and removing unnecessary objects, the desirable nodule size and delivery rate are supplied to the lift system. Therefore, it is one of the most important components to determine the efficiency of whole mining system. The collector system, in general, is consisted of the following mechanism;NODULE GATHERING MECHANISM is to gather nodules, which exist on or partly buried in the sediments, to the system.NODULE SEPARATION MECHANISM is to separate into the desirable size of nodules for lifting, and to remove unnecessary sediments.NODULE FEEDING MECHANISM is to feed collected and separated nodules to the lift system.RUNNER MECHANISM is to support and travel the system. For the self-propelled type collector system, the propelling mechanism is included.FRAME STRUCTURE is mounting structure for each mechanism including buoyancy packages which control the weight in the water. Other than above mentioned mechanism, motor which supplies required power for the collector system, and instrumentations to monitor and control operating status are mounted generally. If necessary, nodule crushing mechanism would be mounted as well. Amongst these components on the collector system, the most influencing mechanism to the efficiency of system is the nodule gathering mechanism. Because of this point, it is important to invest this mechanism as to develop the collector system.