Solar thermo-chemical process assisting a pressure oxidation process for co-production of electricity and metal

The mining industry is looking at the use of solar energy to address issues related to highly variable energy prices, falling ore grades, and increasing concern about the industry’s carbon footprint. The pressure oxidation of ore sulfides is an economic alternative to the smelting process because it has the potential to reduce energy consumption and treat low-grade ores. In the pressure oxidation of ore sulfides, the purity and utilization of oxygen are key factors. Indeed, oxygen production and consumption constitute the major operating cost of the pressure oxidation process. Solar thermo-chemical looping processes have been identified as one of the most efficient pathways for the production and storage of oxygen. This study investigates the integration of a solar thermo-chemical looping process with a pressure oxidation process to treat ore sulfide and produce electricity. The analysis shows that the temperature of the cold storage tank has a strong influence on the performance of the complete system. The increase in the cold tank temperature results in a sharp decrease in the size of the receiver. This reduce the investment costs for both the solar receiver and the heliostat field. For the considered case, the useful heat of the solar receiver is 3.7 MWth when the cold tank temperature is set at 100°C. If the cold tank temperature is set at 400°C, the required useful solar heat is about 3.1 MWth and the nominal output of the gas turbine is 0.56 MWe. The analysis showed that about 80% of the useful solar heat can be used to generate oxygen when the temperature of the cold tank is as high as that of the reduction reactio

Influence of the geographical parameters on the performance of hybrid solar gas turbine

This study aims to investigate the influence of the geographical and climate parameters on the performance of the hybrid solar gas turbine with a pressurized air receiver. A number of sites located in South America (Chile, Bolivia, and Peru) and North Africa (Algeria and Libya) are considered. The geometric design parameters of the solar receiver and the tower are calculated using an in-house code. The layout and the optical performance of the heliostat field are carried out using SolarPILOT software. The simulation of the complete hybrid solar gas turbine is carried out using TRNSYS software. A 50 MWe hybrid solar gas turbine is chosen in this study. Results show that a hybrid solar gas turbine installed in North Africa performs better than that installed in South America. This is mainly due to the optical performance of the heliostat field, which are better in North Africa are than in South America. The highest annual optical efficiency of a solar field is observed at Bechar (Algeria) 56.8% while the lowest annual efficiency is observed at Antofagasta (Chile) 48.1%.The solar-to-electric efficiency at Atacama Desert is lower than in the Sahara Desert. Indeed, in Atacama region the solar-to-electric efficiency varies from 17% at Antofagasta to about 18% in Arequipa while it is above 19% at Sabha and Bechar

A survey of UAV-based data collection: Challenges, solutions and future perspectives

Internet of Things (IoT) generates unlimited data, which should be collected and forwarded towards a central controller (CC) for further processing and decision-making. Nevertheless, the unique features of IoT devices, such as their limited energy capacity, large-scale deployment, and prospective mobility, introduce new challenges and constraints, resulting in unoptimized data gathering. Therefore, as a forthcoming solution, Unmanned Aerial Vehicles (UAVs) could be dispatched as auxiliary devices, and the benefits of their potential are fully exploited, such as movement flexibility, mitigation of IoT communication burden, minimization of data collection (DC) delay, powering IoT devices, and efficient delivery of collected data. The current state-of-the-art has a noticeable gap that hinders the systematic reviews of UAV-based DC schemes. To bridge this gap, this survey provides an extensive analysis of UAV-based DC schemes to light up the topic. We first outline the main characteristics of UAV networks, which have to be considered when designing an efficient UAV-based DC scheme. Also, we highlight the main challenges that, if considered during the data gathering process, can significantly enhance the assistance of UAVs to IoT devices. We then describe various UAV-based DC applications with their key features. Next, our paper comprehensively discusses UAV-based DC schemes according to a proposed taxonomy. Finally, we discuss current problems, difficulties, and potential future directions for UAV-based DC research

UGV Charging Stations for UAV-Assisted AoI-Aware Data Collection

International audienceMeeting the stringent requirements of real-time Internet of Things (IoT) is a bit challenging than expected. Indeed, IoT devices generate massive amounts of data through their sensing features and face some constraints in timely transmitting sensed data to collectors. To overcome this problem, Unmanned Aerial Vehicles (UAVs) are deployed to act as data collectors for IoT devices as they significantly improve the freshness of collected data in real-time applications. Nevertheless, IoT devices and UAVs have limited energy capacity. In this paper, we tackle the energy concern of IoT devices by utilizing UAVs as data collectors and energy transmitters and by promptly charging IoT devices whenever necessary. As for the energy concern of UAVs, we deploy a set of Unmanned Ground Vehicles (UGVs) to energy supply UAVs, allowing them to complete their tasks successfully. Our objective is to employ a multi-agent reinforcement learning method for optimally controlling the trajectories of both UGVs and UAVs so that it jointly decreases their energy consumption, reduces the Age of Information (AoI) of IoT devices, and timely charges UAVs and avoids their failures. We conducted a series of tests using a simulation tool to validate the effectiveness of the approach

Aluminium-induced acute neurotoxicity in rats: Treatment with aqueous extract of Arthrophytum ( Hammada scoparia)

Objective: To study the antioxidative and protective properties of aqueous extract of Hammada scoparia (H. scoparia) against the effects of sub-chronic aluminium (Al) intoxication on mnemonic process and some neurochemical markers. Methods: Al was administered intraperitoneally (50 mg/kg body weight, three times a week), and H. scoparia and malic acid were given orally by gavage at a daily dose (100 mg/kg body weight) to rats for 90 days. Results: Al caused significant short-term and long-term memory disturbances, a decrease in locomotor activity, a significant inhibition of acetylcholinesterase activity in brain and a significant depletion of antioxidant enzymes (catalase, glutathione reductase and glutathione peroxidase) and glutathione. It significantly increased lipid peroxidation levels in cerebrum and cerebellum. However, treatment with H. scoparia extract protected efficiently the neurological functions of intoxicated rats by considerably increasing antioxidants levels and decreasing production of thiobarbituric acid reactive substances by 4.26% compared to untreated group. We noted some controversial results with malic acid. It showed some positive results but it was not as efficient as H. scoparia extract. Current results were consistent with histopathological observations including neurodegeneration and vacuolated cytoplasm (spongiosis) in Al treated sections when H. scoparia and malic acid treated sections showed marked neuroprotection signs. Conclusions: This study strongly suggested that H. scoparia extract could possibly restore the altered neurological capacities and antioxidant power in rats, and it could even be a good alternative to chelating agents or other chemical medicines against Al-induced neurotoxicity

Optimization of the activity of Mo7-Zn3/CaO catalyst in the transesterification of waste cooking oil into sustainable biodiesel via response surface methodology

An enriched basic site CaO-supported bimetallic Molybdenum-Zinc (Mo7-Zn3) catalyst was successfully synthesized via wet-impregnation and evaluated for the transesterification of waste cooking oil into biodiesel. The physicochemical characterization of the Mo7-Zn3/CaO catalyst demonstrated good dispersion of CaMoO4 and ZnO oxides on CaO support, with a mesoporous structure allowing for better mass transfer between reactants. The Mo7-Zn3/CaO catalyst exhibited high transesterification activity (95 ± 0.3 FAME conversion), owing to the large density of strong Brønsted basic sites (conjugated O2–) generated from simultaneous interaction among Ca2+, Zn2+ and Mo6+ metal species. Response Surface Methodology (RSM) and Box Behnken Design (BBD) were used to optimize the reaction and indeed, the utmost FAME conversion of 95 is achieved using 3.37 wt catalyst loading, 12:1 methanol to oil molar ratio within 2.27 h at 62.7 °C reaction temperature. The model reliability in predicting the FAME yield using the established catalyst under varying operational conditions was excitedly validated with a reasonable accuracy error of 0.5 . The catalyst exhibited good stability, maintaining a high FAME conversion (95–85 ) during 5 reusable cycles without significant loss in catalytic activity. A closer look for a detailed approach and a heterogeneous mechanism for the reaction using Mo7-Zn3/CaO catalyst was proposed. The physical and chemical properties of the produced biodiesel were carefully compared with the standard for biodiesel, and were found to majorly comply with ASTM D6751 and EN 14214 biodiesel properties. An investigation into the economic competitiveness and industrial applicability of biodiesel production using Mo7-Zn3/CaO from WCO reveals significant potential for sustainable and efficient biodiesel synthesis