Development of a differential pressure sensor for intelligent control of deep-sea mining applications

Due to continuously increasing globalization, digitalization and electrification, the demand for valuable raw materials such as copper, rare earth elements and other metals keeps on rising. Although these are usually won onshore, deposits are limited, mining becomes increasingly costly and it can have a considerable environmental and social impact. Hence, new methods of extracting raw materials are needed to meet their steadily growing demand. Deep-sea mining is a promising alternative and is currently pursued worldwide. Yet, current conventional methods are considered to cause dramatic environmental damage by creating huge clouds of turbidity. To overcome this issue, we develop a new platform for detecting, exploring and mining ore deposits in the deep sea that meets the highest standards. Despite the extreme conditions, this enables energy-efficient and environmentally friendly extraction of raw materials from the deep sea using a minimally invasive process. One component of the monitoring sensor system is a differential pressure sensor for the piping system. The pressure sensor will be part of an intelligent, self-learning control system. The sensor measures the differential pressure over the length of the feed hose and allows conclusions to be drawn about the amount of solids conveyed and the associated milling progress, but also about faults such as blockages or changed fluid properties due to high loading of the feed fluid with ultra-fine particles. This information is essential for the operation of both an autonomous and remotely controlled device. Such a sensor is not yet available on the market. To overcome this issue, we develop a new system based on a commercial differential pressure sensor. To expand its applicability to deep-sea environments, all components aside the measuring chamber are carefully encapsulated to protect the electronics from the detrimental effects of pressure and water. For this purpose, we aim for a method that leads to maximum robustness while avoiding complicated processes and components that are prone to error. This is a promising way to obtain a robust and reliable measuring system for long-term use under harsh deep-sea conditions that is easy to manufacture. We have carried out numerous tests to validate the functionality and reliability of the encapsulated sensor. Both, resistance to high pressures and functionality during and after a compressive load, have been demonstrated by carrying out tests in a high-pressure vessel. In this contribution, we will detail the encapsulation procedure and report preliminary validation results. Overall, this new sensor shows improved capabilities. It combines existing measurement technology with the new property of deep-sea conditions and hence new applications.