Offshore Mining Research Articles

Economic analysis of shipping route planning in deep-sea mining operations under uncertain shipping market

Deep-sea mining is an emerging interdisciplinary and cross-domain research topic. As commercialization of deep-sea mining advances, economic analysis of the maritime transportation of minerals is critical to forming sound commercial plans. This paper proposes an approach for the economic analysis of shipping route planning in deep-sea mining operations, considering the varying capacities of the proposed mobile offshore minerals units (MOMUs) and the limited capacity. Capital expense (CAPEX), operational expense (OPEX), and voyage expense (VOYEX) are taken into account according to the arrangement of mineral transportation vessels (MTVs) with different capacities of MOMUs and fluctuating shipping prices. Monte Carlo Simulation is used to analyze the uncertainties of the total cost for MTVs with respect to CAPEX, OPEX, and VOYEX. A case study of the shipping route from the Chinese contract area in the Clarion-Clipperton Zone to Ningbo-Zhoushan Port is presented to interpret the proposed approach. The derived results demonstrate that 120,000 tons is the most economically viable MOMU size, saving at least 1.9 % of the total cost. These savings are mainly due to better scheduling, speed, and resilience to market prices. The proposed approach can support economic feasibility for deep-sea mining projects and provide investors with more specific operational measures to make well-informed decisions.

The North Sea rift basement records extensional collapse of the Caledonian orogen

Our knowledge of crystalline basement rocks flooring continental rift basins, rifted margin deposits, and foreland basins is poor, yet important for understanding basin evolution, crustal heat production, petroleum maturation, and for offshore mineral exploration. Using the northern North Sea rift as an example, we demonstrate how modern broadband seismic data can be utilized to unravel basement lithology and structure at a previously unprecedented level of detail. In our case study, we have discovered a pre-rift Caledonian basement with a folded structural pattern very similar to Devonian collapse-related structures onshore Western Norway. The data indicate that the collapse-generated Caledonian infrastructure extends >100 km into the northern North Sea, defining a wide zone of Caledonian crust that turned hot and mobilized vertically by upright folding and detachment faulting during the post-collisional stage. This extensive post-orogenic thermally induced collapse makes the south Scandinavian Caledonides unique among Phanerozoic orogens.

Polish Studies on Saturation Diving and Practical Application of Their Findings. Part III a Technical and Organisational Issues of the Implementation of Saturation Diving in Poland from the 1990s Onwards. Part 1

Abstract This article is another in a series of articles on the research and implementation of saturation diving technology in Poland. It discusses the specificities related to the implementation of this technology against the background of economic and historical conditions in our country. In Poland, the issue of saturation diving for the needs of the emerging offshore mining industry has been for over a dozen years dealt with by the Department of Diving Equipment and Technology of Underwater Works (Polish abbr. ZSNiTPP). In parallel, deep diving technologies were developed, in the first stage, as a basic diving technology and, since 1994, as complementary to ensure the full backup for saturation diving. Since 1995, saturation diving has become an everyday occurrence in the Polish economic zone of the Baltic Sea. This article shows the difficult path that the implementation of saturation diving took during a period of economic instability when the scale of the domestic offshore industry's facilities was small compared to global companies. Selected animators and participants in the implementation are recalled for two periods: one marked with the cooperation with the Italian underwater services company RANA and the other one, a period of implementation of long-term underwater works based on national capabilities. The article also considers the technical and organisational conditions for the implementation of saturation diving for the Polish mining industry. In 1990, the Oil and Gas Exploration and Production Company Petrobaltic (today LOTOS) played one of the key roles in the implementation of saturation diving in our country. The implementation of saturation diving in Poland was linked to the only operational diving system of Italian production, the Af-2, which enabled scientific research related to the application of new technical solutions and testing under operational conditions, as well as contributed to the development of scientific, engineering, and medical staff for the Polish offshore industry. The company played one of the main roles in the implementation of saturation diving in our country The 1995 became a landmark year in the history of saturation diving in Poland, as well as in the Baltic Sea. Through this technology, the process of installing the first two underwater exploitation heads on production wells B3-7 and B3-10 was initiated. The saturation diving was possible thanks to the leasing of the Af-2 diving system by Petrobaltic and its subsequent purchase by the Naval Academy in 1998.This system, after a series of upgrades, is still in service today.

Corporate Valuation of Indonesian Drone Service Company: Case Study of PT Kelana Geospasial

Indonesia's drone industry is expanding rapidly, fueled by significant investments and the growing necessity of drone technology in agriculture, offshore mining, and aerial photography. The global and Asian drone markets are also on the rise, with a projected 7.1% CAGR increase driven by industrial use and substantial investments. However, valuing Indonesian drone businesses is difficult due to their intangible assets and the startup nature of many companies, which focus more on value creation than financial stability. Established in 2016, PT Kelana Geospatial (PT KG) utilizes Unmanned Aerial Vehicle (UAV) technology for aerial mapping services and collaborates with sectors like agriculture, offshore mining, and aerial photography. They also offer UAV pilot certification and sell related products and parts. Despite their diverse offerings, PT KG faces stagnant growth and needs to enhance productivity with existing resources. The management struggles with valuing potential mergers, maintaining clear financial records, and addressing industry risks. PT KG's growth is mainly driven by mapping and maintenance services, although product sales have declined. Despite an improving financial situation, high production costs and expenses challenge profitability. While positive GPM and OPM indicate potential, NPM remains negative. Recommendations include expanding services, boosting efficiency, and leveraging technology and partnerships. By utilizing These strategies could foster sustainable growth and increase PT KG's enterprise value, currently estimated at IDR 3.84 billion.

Sea Bed Mining

The seabed is surely one of the last mining frontiers on earth remaining for mankind, to extract economic mineral deposits. It is hence imperative that India with its Obvious Geological Potential (OGP) area on the land surface amounting to 0.57 million km, for which baseline geoscience data has been generated and mineral exploration activities are ongoing, needs to be supplemented with mineral wealth on our sea beds, within our Territorial Waters (TW) and Exclusive Economic Zone (EEZ). Studies by the Geological Survey of India (GSI) and other agencies for mineralized horizons in the terrestrial OGP areas have been a continuous process. The baseline geoscience and mineral exploration data are published regularly by GSI and Indian Bureau of Mines (IBM) and made available to respective stakeholders. India has a 2.02 million km area under its TW and EEZ. Our East and West Coasts of the Peninsular India are endowed with phosphate, manganese nodules, lime mud and monazite sands with rare earth elements (REE) and thorium that have been surveyed by the Marine and Coastal Survey Division (MCSD) of the GSI with their research vessels to establish the potentiality. According to the data available, 1,53,996 million tons of lime mud within the EEZ off Gujarat and Maharashtra coasts, 745 million tons of construction grade sand, off Kerala coast, 79 million tons of heavy mineral placers in the inner-shelf and mid-shelf, off Odisha, Andhra Pradesh, Kerala, Tamil Nadu and Maharashtra, phosphorite in the Eastern and Western continental margins, polymetallic ferromanganese nodules and crusts in Andaman Sea and Lakshadweep Sea have been reported. The CSIR- National Institute of Oceanography has been embarking on research for seabed mineral deposits. The Offshore Areas Mineral (Development and Regulation) Amendment Bill, 2023, passed by Lok Sabha on 01.08.2023, has amendments to the Offshore Areas Mineral (Development and Regulation) Act, 2002, OAMDR Act (Ministry of Mines, Govt. of India, 2002). It envisages major initiatives to allow auction of mineral blocks 45° X 45° (latitude and longitude) in respect of any mineral or prescribed group of associated minerals, under one or more operating rights (taken together). The Act has a provision for setting up of a non-lapsable Offshore Areas Mineral Trust to maintain a fund under the Public Account of India. This fund will be financed by a yet to be determined, additional levy on the production of offshore minerals that will be used for exploration, research, disaster relief and for mitigation of adverse impacts of seabed mining. We have the National Exploration Trust and the District Mineral Foundation Trust funds, to which royalties are paid by stakeholders for onshore mining.

Study on the Numerical Relationship between Dynamic Compressive Strength and Crushing Energy Consumption in Dynamic Point Load Test under Different Corrosion Conditions

Compared with most dynamic tests, point load test is widely used in engineering practice because of its wide requirements for test conditions. In offshore mining engineering, the surrounding rock is affected by dynamic load impact and corrosion of various aqueous solutions for a long time. Therefore, it is of great significance to study the influence of hydrochemical corrosion on dynamic mechanical properties of rock to ensure the stability of surrounding rock. In this paper, a large number of dynamic point load and dynamic uniaxial compression tests were carried out on the granite mined from a large mine by using the Split Hopkinson pressure bar test device after the corrosion of pH values of 2, 5, and 7 solutions, respectively. Based on the energy theory, the crushing energy consumption in the test process is analyzed, and finally the fitting formula of the dynamic compressive strength and the crushing energy consumption in the dynamic point load test is obtained through fitting analysis. The results show that when the crushing energy consumption in the dynamic point load test is used to estimate the dynamic compressive strength, a certain crushing energy consumption (the final value of this test is 70 J in this paper) is more accurate, and it can estimate the dynamic compressive strength under various corrosion conditions under this crushing energy consumption. However, with the change of crushing energy consumption in the dynamic point load test, this transformation relationship is no longer accurate, and it is necessary to modify this transformation relationship with corrosion condition as the influencing factor. This conclusion can provide reference for obtaining the dynamic compressive strength of rocks under different corrosion conditions in engineering field in the future.

Joining of metallic glasses in liquid via ultrasonic vibrations

Joining processes especially for metallic materials play critical roles in manufacturing industries and structural applications, therefore they are essential to human life. As a more complex technique, under-liquid joining has far-reaching implications for national defense, offshore mining. Furthermore, up-to-now, the effective joining of metals in extreme environments, such as the flammable organo-solvent or the arctic liquid nitrogen, is still uninvestigated. Therefore, an efficient under-liquid joining approach is urgently called for. Here we report a method to join different types of metallic glasses under water, seawater, alcohol and liquid-nitrogen. The dynamic heterogeneity and liquid-like region expansion induces fluid-like behavior under ultrasonic vibration to promote oxide layer dispersion and metal bonding, allowing metallic glasses to be successfully joined in heat-free conditions, while still exhibiting excellent tensile strength (1522 MPa), bending strength (2930 MPa) and improved corrosion properties. Our results provide a promising strategy for manufacturing under offshore, polar, oil-gas and space environments.

Computational Oil-Slick Hub for Offshore Petroleum Studies

The paper introduces the Oil-Slick Hub (OSH), a computational platform to facilitate the data visualization of a large database of petroleum signatures observed on the surface of the ocean with synthetic aperture radar (SAR) measurements. This Internet platform offers an information search and retrieval system of a database resulting from >20 years of scientific projects that interpreted ~15 thousand offshore mineral oil “slicks”: natural oil “seeps” versus operational oil “spills”. Such a Digital Mega-Collection Database consists of satellite images and oil-slick polygons identified in the Gulf of Mexico (GMex) and the Brazilian Continental Margin (BCM). A series of attributes describing the interpreted slicks are also included, along with technical reports and scientific papers. Two experiments illustrate the use of the OSH to facilitate the selection of data subsets from the mega collection (GMex variables and BCM samples), in which artificial intelligence techniques—machine learning (ML)—classify slicks into seeps or spills. The GMex variable dataset was analyzed with simple linear discriminant analyses (LDAs), and a three-fold accuracy performance pattern was observed: (i) the least accurate subset (~65%) solely used acquisition aspects (e.g., acquisition beam mode, date, and time, satellite name, etc.); (ii) the best results (>90%) were achieved with the inclusion of location attributes (i.e., latitude, longitude, and bathymetry); and (iii) moderate performances (~70%) were reached using only morphological information (e.g., area, perimeter, perimeter to area ratio, etc.). The BCM sample dataset was analyzed with six traditional ML methods, namely naive Bayes (NB), K-nearest neighbors (KNN), decision trees (DT), random forests (RF), support vector machines (SVM), and artificial neural networks (ANN), and the most effective algorithms per sample subsets were: (i) RF (86.8%) for Campos, Santos, and Ceará Basins; (ii) NB (87.2%) for Campos with Santos Basins; (iii) SVM (86.9%) for Campos with Ceará Basins; and (iv) SVM (87.8%) for only Campos Basin. The OSH can assist in different concerns (general public, social, economic, political, ecological, and scientific) related to petroleum exploration and production activities, serving as an important aid in discovering new offshore exploratory frontiers, avoiding legal penalties on oil-seep events, supporting oceanic monitoring systems, and providing valuable information to environmental studies.

Another Look at Marine Minerals

Abstract Deep-sea mining is taking another step closer to reality. Early leases for exploration in the central Pacific manganese nodule fields and elsewhere in the oceans are coming to an end, and contractors are faced with a choice—extend the licenses to continue exploration or apply to mine the deposits they have found. The first 15-year licenses were originally signed into effect by the International Seabed Authority (ISA) in 2001 and began to expire in 2016. With no operations in a position to commence mining and, more importantly, no regulations in place to allow it, most exploration licenses were simply renewed. Eight of the original licenses were extended for five more years, some twice, and new licenses have been granted. Today, there are 31 contracts for exploration: 19 for manganese nodules, 7 for sea-floor massive sulfides, and 5 for Co-rich crusts. The first contract for massive sulfide exploration expires in 2026; the first for Co-rich crusts expires in 2029. Meanwhile, there is strong interest from a number of countries in the mineral resource potential of their exclusive economic zones (EEZs), particularly Japan and Norway. Against this backdrop of rapidly shifting exploration activity, it may be time to take another look at marine minerals as a resource for the future. In a report entitled “The Future of the Ocean Economy by 2030,” the Organization for Economic Cooperation and Development (OECD) asked, “What new developments could result in a complete revision of offshore mineral potential?” For most parts of the oceans, the answer to this question is plagued by inadequate mapping and a lack of geologic knowledge as a basis for assessing the resources. However, new approaches to exploration are emerging, and recent discoveries, such as on the continental shelf and beneath the cover of sediment, are changing our view of the resource potential.

Gray Uncertain Linguistic Multiattribute Group Decision Making Method Based on GCC-HCD

This article presents a multiattribute group decision-making (MAGDM) method using cloud models to handle decision problems with gray uncertain linguistic variables that contain both subjective and objective uncertainty. In this new method, the new concepts of gray uncertain linguistic variable and gray comprehensive cloud are defined, and a method for converting gray uncertain linguistic variables into gray comprehensive clouds is provided. A gray comprehensive clouds-weighted averaging (GCC-WA) operator is proposed to aggregate the information with multiple gray comprehensive clouds. A distance measure between two gray comprehensive clouds is defined to form the gray comprehensive cloud-hybrid closeness degree (GCC-HCD), which is then applied to rank the alternatives. An example of an offshore mining investment is applied to validate the method. Sensitivity analysis and comparison analysis are carried out with other congeneric methods.

Drivers of Blue Economy in Luzon, Philippines: Status, Threats, and Potentials for Development

Blue economy refers to sustainable economic pursuits done in the marine environment, which include fishing and aquaculture, coastal recreation and tourism, maritime industry, energy industry, and offshore mining and quarrying. In Luzon, marine waters contribute 38.44% to the total national fishery production, host 44.6% of the total domestic trade by water transport, host 3 of the top 5 beach destinations in the Philippines, and has the only productive oil and natural gas fields in the country. Fishery, however, is described as unsustainable brought primarily by depleted fishery resources, degraded fishery habitats, intensified resource use competition, and conflict. The fishery resource side is described to have unrealized potential, with uncompetitive product quality, and inefficient post-harvest technology. The Maritime industry’s potential is challenged by a fragmented maritime administration while the prospects of marine tourism are limited by the skills of local communities to take in tourists. Opportunities include optimization of aquaculture technology, sustainable financing schemes for aquaculture and tourism, infrastructure investments that promote sustainable fishing practices, sustainable financing scheme, enhancement of existing technology for the maritime industry, human resource development, and tapping ocean power potentials. Coordinated and integrated planning, considering skills of human resources, economic status of coastal communities, and scientific data would optimize blue economic development.

Geology of parts of the central and eastern Clarion Clipperton Zone

ABSTRACT The Clarion Clipperton Zone (CCZ) hosts the most valuable deposit of polymetallic nodules yet discovered. International Seabed Authority exploration contractors, such as Tonga Offshore Mining Limited, Nauru Ocean Resources Incorporated and Marawa Research and Exploration Limited, routinely conduct ship-based 12 kHz multibeam echosounder surveys over all or parts of their exploration contract areas. This is often supported by physical seabed samples, side-scan sonar, sub-bottom profile sonar and seabed photographs. Geological maps for seven discrete mapped areas are presented. Basaltic abyssal plains of mid-Eocene to early Miocene age are overlain by 75–100 m of mid-Eocene and younger deep-sea chalks of the Marquesas Oceanic Formation. In turn, the chalk is overlain by up to 27 m of early Miocene to present, often mobile, siliceous clay-ooze sediment of the Clipperton Oceanic Formation. This stratigraphy is crosscut by a very wide variety of mostly volcanic magmatic rock units.

Multi-Objective Optimization of Drilling Trajectory Considering Buckling Risk

Directional drilling involves three sections—vertical, curved, and horizontal—and is used for drilling offshore wells and mining unconventional resources. The initial design of a well trajectory is important because the total length of the well trajectory is associated with the drilling cost; furthermore, the drag force and torque may cause buckling and damage the drill pipe. The well trajectory should be optimized considering the length and load of drill pipes. In this study, a new method of optimizing directional well trajectory is used to formulate the objective function considering the length, drag, and torque. To verify the applicability of this method, we applied it to an actual oil well and a theoretical oil well. The results obtained show that the use of the proposed method in the initial design of drilling trajectory can reduce the torque by up to 15%, drag by 2.6%, and length by 8.5% for the two models used in this study. This method is safer as it reduces the risk of buckling compared to the design that relies on the previous designer’s experience, and it reduces the trajectory length; thus, it can save time and costs of drilling.

DEM study of the influences of the geometric and operational factors on the mechanical responses of an underwater mixing process

Mixing granular materials plays versatile roles in many engineering fields. In this study, we focus on an underwater mixing process as a novel application for offshore mining. We apply the discrete element method (DEM), which was augmented by a lubrication model, to evaluate the mechanical responses of the mixing process under water. Further, a non-dimensional parameter is introduced to evaluate the mixing resistance. The DEM simulation is first calibrated by a mixing experiment involving colored sand immersed in water. A parametric study is then conducted to evaluate the geometric and operational factors involved in the mixing process, including the blade angle, penetration depth, filling depth, container-blade aspect ratio, model scale, and rotation speed. Their influences on the mechanical responses of the mixing process are evaluated, i.e., the resultant torques on the mixer head, the resultant forces on the ground and side wall of the container, the effective particle masses mobilized by mixing, and the proposed mixing resistance parameter. It was found that the influences range from insignificant to highly nonlinear, and vary considerably among the evaluated factors and steady-state responses. Especially, an optimal blade angle range is observed in terms of minimal mixing resistance. These findings can contribute to the optimization of the mixer geometry, selection of the rotation speed, estimation of the motor power, and economic design for numerical and laboratory experiments with scaled-down models.

A Multifaceted Approach to Advance Oil Spill Modeling and Physical Oceanographic Research at the United States Bureau of Ocean Energy Management

The Environmental Studies Program (ESP) at the United States Bureau of Ocean Energy Management (BOEM) is funded by the United States Congress to support BOEM’s mission, which is to use the best available science to responsibly manage the development of the Nation’s offshore energy and mineral resources. Since its inception in 1973, the ESP has funded over $1 billion of multidisciplinary research across four main regions of the United States Outer Continental Shelf: Gulf of Mexico, Atlantic, Alaska, and Pacific. Understanding the dynamics of oil spills and their potential effects on the environment has been one of the primary goals of BOEM’s funding efforts. To this end, BOEM’s ESP continues to support research that improves oil spill modeling by advancing our understanding and the application of meteorological and oceanographic processes to improve oil spill modeling. Following the Deepwater Horizon oil spill in 2010, BOEM has invested approximately $28 million on relevant projects resulting in 73 peer-reviewed journal articles and 42 technical reports. This study describes the findings of these projects, along with the lessons learned and research information needs identified. Additionally, this paper presents a path forward for BOEM’s oil spill modeling and physical oceanographic research.

Multi-purpose high-resolution seismic acquisition: the deep-sea mining case

Summary The oil and gas industry has developed highly sophisticated technology for offshore hydrocarbon exploration. The traditional focus has been on hydrocarbon exploration and production targets. These targets are commonly buried under a few kilometres of sedimentary layers and 3D seismic technology has been the main type of data acquired for characterizing these targets. A secondary focus has been on the shallow section, and it has mostly been driven by shallow hazard investigations to aid the drilling of those targets. This characterization is commonly done with 2D high-resolution seismic referred to as site surveys. In recent years, shallower targets have been sought for carbon capture and storage (CCS). It is best to store carbon dioxide in its critical state which is achieved at burial depths of about 800 m. Thus, the goal is to locate porous rocks with a natural seal at depths of 800 m-1500 m below the seabed. Deeper reservoirs can be used for CCS, but shallower ones are more economical. In addition, offshore mineral exploration is at the point of becoming a commercial activity. To characterize these mineral reservoirs or deposits, the selected type of data needs to resolve the very near surface (first few decametres) at a very high resolution in an efficient way that enables the location of targets with an area extension of 100 to 300 m. Thus, in 2021 3D seismic is aimed at best resolving the very shallow and the very deep. These facts motivated the set of experiments acquired in the AM20-lab in the Norwegian Atlantic Margin in 2020. In this paper, we focus on AM20-lab test 2. While the focus of test 2 is to achieve ultra-high resolution near-surface 3D seismic for mineral exploration, the data provides multipurpose value for medium and deep targets as well. The survey was designed and acquired with a novel signal apparition decasource encoding and was benchmarked against pentasource data from a production multiclient survey which was designed for hydrocarbon exploration

Empirical Application of Generalized Rayleigh Distribution for Mineral Resource Estimation of Seabed Polymetallic Nodules

An efficient empirical statistical method is developed to improve the process of mineral resource estimation of seabed polymetallic nodules and is applied to analyze the abundance of seabed polymetallic nodules in the Clarion Clipperton Zone (CCZ). The newly proposed method is based on three hypotheses as the foundation for a model of “idealized nodules”, which was validated by analyzing nodule samples collected from the seabed within the Tonga Offshore Mining Limited (TOML) exploration contract. Once validated, the “idealized nodule” model was used to deduce a set of empirical formulae for predicting the nodule resources, in terms of percentage coverage and abundance. The formulae were then applied to analyzing a total of 188 sets of nodule samples collected across the TOML areas, comprising box-core samples and towed camera images as well as other detailed box-core sample measurements from the literature. Numerical results for nodule abundance and coverage predictions were compared with field measurements, and unbiased agreement has been reached. The new method has the potential to achieve more accurate mineral resource estimation with reduced sample numbers and sizes. They may also have application in improving the efficiency of design and configuration of mining equipment.

Design and deployment of IoT based underwater wireless communication system using electronic sensors and materials

Underwater wireless communication performs a critical role in tactical surveillance, water pollution control, oil exploration and maintenance, offshore mining, local weather control and oceanography research. It is an excellent operation for the military, industry, and scientific community. To facilitate these applications, wide variety of unmanned motors or units, which require excessive bandwidth and excessive ability to switch data are deployed underwater. Even though some of these goals have been achieved by underwater acoustic communication discipline but constrained by bandwidth. These factors have led to the advent of underwater Wi-Fi connectivity (UWC), which provides higher bandwidth than the usual acoustic contact systems with substantially reduced energy consumption and simplified technological problems for short-range Wi-Fi connexions. This paper under water wireless communication is achieved by using Internet of Things (IoT) an advanced technology along with microcontroller and Wi-Fi. In this study temperature, turbidity and distance between the objects are measured with the respective sensors connected to the transmitter and recorded at the receiver side by using IoT technology for different time intervals. It is concluded that the proposed UWC system based on IoT can be low cost, efficient and can be used for different applications related to underwater.

Green mining: technical study of off-shore tin mining using cutter suction dredger in Bangka Island, Indonesia

According to government regulations regarding good mining practice, PT Timah Tbk and its partners have begun to develop offshore mining techniques using Cutter Suction Dredger (CSD). Therefore there is a need for a technical study of the application of CSD in offshore tin mining. The method used in this research is to observe field activities directly. Observation of mining data of mining design, dredging system and mapping of bathymetri. The process flow, production and tin ore recovery of mineral processing. Observation of the tailings disposal considers the minimal impact on the environment. The result is mining design using CSD applies a long face system with a combination of vertical digging. The opening angle of the two anchors amounting to 90-145° produces width snee of 40-55 m. This method is capable of producing an average rate of soil removal of 250 m3/hour. The floating mineral processing plant uses a three-stage jigging method with Circullar and Pan American types plus a shaking table resulting a washing tin recovery of 66%-90%. Considering bathimetry, the geotube embankment technique can control the spread of tailings. The conclusion is that the mining process using CSD is one step better in terms of implementing good mining practice.

Location of natural gas leakage sources on offshore platform by a multi-robot system using particle swarm optimization algorithm

The offshore platform serves as the infrastructure for offshore mining. In order to guarantee safe operation of the platform and the development of the platform in the direction of intelligence, a natural gas leakage intelligent detection system with fast response is necessary to prevent potential accident when leakage occurs. In this work, a method to locate leaked natural gas is proposed based on the particle swarm optimization algorithm for the multi-robots to achieve. First, the advection diffusion equation is calculated to simulate the leakage gas transmission using finite difference method in different scene layouts. At the same time，a multi-robot collaborative detection strategy for gas detection, gas tracking, and gas source localization is proposed using an improved particle swarm optimization algorithm. After that, the process of multi robots search for leak sources was simulated. In addition, the control algorithm is analyzed, and the results show that the strategy has a high detection rate. Further analysis shows that the number of robots has increased from 2 to 7, the time it takes for the multi-robot system to successfully locate the leak source decreased; when the number of robots is constant, the time it takes for the multi-robot to successfully locate two leak sources is longer than the time to locate a single leak. Finally, search strategies based on particle swarm optimization, ant colony algorithm and cuckoo search algorithm are used to simulate in a single leak source environment. When the number of robots is changed from 3 to 7, compared with the other two algorithms, the accuracy of the search strategy search based on particle swarm is increased by 2%–28%, and the search time is accelerated by 27s–92s.the particle swarm optimization is superior than two others for control of multi-robot system in leakage source location.