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Background
Aluminium dross is a valuable resource that is often redirected to landfill as there are no real viable solutions for the utilisation of this industrial waste. A study has been conducted to provide a recycling process where the dross is reacted with an alkaline solution in order to generate hydrogen with bayerite and gibbsite products. M...
Contexts in source publication
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... the available alterna- tive forms of energy. However, these technologies do not provide the necessary amount of energy that could be produced from conventional forms of utilising fossil fuels. This is one of the many reasons why hydrogen is being considered as a viable fuel to take up a significant percentage of energy demands. As can be seen in Fig. 1 through the use of hydrogen as a resource, there is a po- tential renewable energy that possesses a substantial amount of energy per kilogram in comparison to other fuels ...
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... there is a level of uncertainty, so that the LD provides more surface area than RD due to uneven granules. Figure 10 shows an accumulation of the amount of hydrogen generated over the period of 1 h. It shows that the rate at which the hydrogen is generated varies be- tween the two samples at 0.5 mols. ...
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... From around the 30th minute, the rate of hydrogen generated using the RD sample becomes lower than that of the LD sample. The RD sample's reaction rate eventually settles at around 96% of the rate of the LD sample. Throughout the first hour, the recorded re- action rate of the LD sample stays relatively steady. When observing the trends in Fig. 10 in conjunction with the trends of the reactions' flow rates shown in Fig. 9, it can be seen that the RD sample is able to pro- duce much higher flow rates and generally shows much more promising kinetics in the first hour. The difference in the reactivity between the two samples can be attrib- uted to the difference in the aluminium ...
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... the histogram shown in Fig. 11, we can see the com- parison between the actual volume and the calculated the- oretical volume of each sample for the corresponding amount of moles of aluminium used. There is a visible dif- ference between the theoretical and actual volumes re- corded. The difference may be due to a possible leak coming from the apparatus, although ...
Citations
... Recycled Al dross contains a higher percentage of Al than Al dross from landfills. Higher rates of hydrogen production are produced by reusing dross [56]. Peng Li et al [57] investigated the production of hydrogen through the hot skimmed dross-water reaction. ...
Recycling plays an important role in today's world due to its considerable contributions to mitigating energy concerns and environmental challenges. One of them is dross recycling from aluminum(Al) cast houses. Unlike other recyclable materials, dross has an abundance of components, including rare earth elements, heavy metals, ferrous, and recycled Al. These features make dross a useful commodity within the recycling sector. It is harmful to the ecology and human health to land fill the dross. Recycling dross is economically advantageous and yields products with added worth. This article consolidates the current methods for extracting Alumina from dross. The processes of plasma dross processing, acidic and alkaline leaching are critically examined. Dross is used in numerous applications, including the production of hydrogen as a renewable energy source, the manufacture of refractories, composites, ceramics, reductants, catalysts, and absorption agents, as a result of its multi-utility advantages. In construction applications, dross serves a unique purpose by Providing greater strength, thermal insulation and less water absorption increased the desirability of materials in this industry. This study explores the applications that maximize the utilization of dross and the associated advantages.
... To produce hydrogen gas, 0.5 grams of aluminum chips were added with 250 ml of NaOH 0.5 M, 1.5 M, and 3 M into four-neck flask. Reaction that occur for hydrogen production from aluminum is shown on Eq (2) [4]. ...
Utility of aluminum series AA5XXX, 6XXX, and 7XXX emerges. However, scrap waste remains unrecycled and ends up in municipal solid waste landfills. It is known that aluminum related reactions maybe problematic for landfill operations by generating undesired heat, liquid leachate, and gases. Aluminum produces hydrogen as it reacts readily with water at room temperature to form aluminum hydroxide. In most cases, it may not conventionally take place due to the presence of aluminum oxide that naturally coats the materials preventing it from direct contact with water. The layer can be detached using an acidic solution, such as HCl. HCl solution is prepared to remove the Al 2 O 3 protective layer under acidic conditions. NaOH solution is added into the water to promote hydrogen production afterward. Aluminum scrap with a constant mass of 0.5 grams added to 250 ml of NaOH solution in which the concentrations varied by 0.5 M, 1.5 M, and 3 M. As the pretreatment, it was soaked into 1 M, 2 M, and 3 M HCl solutions for 1 minute. The measurement result shows that aluminum treated with 3 M HCl and reacted in 3 M NaOH yielded 532 ml of hydrogen gas. However, hydrogen concentration in total produced gas volume decreases as NaOH and HCl increase. This result is also confirmed using FTIR spectroscopy which shows the reaction with less NaOH concentration yielded more bayerite form.
... Instead of using chemical promoters, such as hydroxides, oxides, or salts, the authors of [5] dealt with ball milling as a pretreatment and carried out the reaction in hot water. In [6], the difference between Al dross obtained from an aluminum recycling facility (RD) and Al dross directed to landfills (LD) was studied. The authors reported that, with NaOH as the promoter, the RD and LD samples generated 0.50 and 0.15 L of H 2 per 1g of Al, respectively. ...
This work aims to explain aluminum hydrolysis reaction kinetics based on a properly chosen theoretical model with machined aluminum waste chips as well as alkali solutions up to 1M as a promoter and to estimate the overall reaction profit. The purpose of this work is to assess the optimal alkali concentration in the production of small-and medium-scale green hydrogen. To obtain results with better accuracy, we worked with flat Al waste chips, because a flat surface is preferable to maximally increase the time for the created hydrogen bubbles to reach the critical gas pressure. Describing the reaction kinetics, a flat shape allows for the use of a planar one-dimensional shrinking core model instead of a much more complicated polydisperse spheric shrinking core model. We analyzed the surface chemical reaction and mass transfer rate steps to obtain the first-order rate constant for the surface reaction and the diffusion coefficient of the aqueous reactant in the byproduct layer, respectively. We noted that measurements of the diffusion coefficient in the byproduct layer performed and discussed in this paper are rare to find in publications at alkali concentrations below 1M. With our reactor, we achieved a H2 yield of 1145 mL per 1 g of Al with 1M NaOH, which is 92% of the theoretical maximum. In the estimation of profit, the authors' novelty is in paying great attention to the loss in alkali and finding a crucial dependence on its price. Nevertheless, in terms of consumed and originated materials for sale, the conversion of aluminum waste material into green hydrogen with properly chosen reaction parameters has positive profit even when consuming an alkali of a chemical grade.
... Landfilled aluminum-and magnesiumrich materials coming into contact with landfill leachate may react vigorously to generate pockets of hydrogen that can result in combustion. Therefore, these materials are classified by European regulations as special hazardous wastes and should not be dumped as they are [57][58][59][60][61]. Aluminum dross and scrap can be utilized with hydrogen evolution by its treatment with aqueous alkaline solutions [62,63], while the oxidation of magnesium waste can be performed by saline solutions, natural seawater or a simulated one (3.5 wt.% NaCl solution) [64-66]. ...
In this investigation, composite materials were manufactured of mixed scrap of Mg-based alloys and low melting point Sn–Pb eutectic by high energy ball milling, and their hydrogen generation performance was tested in NaCl solution. The effects of the ball milling duration and additive content on their microstructure and reactivity were investigated. Scanning electron microscopy (SEM) analysis indicated notable structural transformations of the particles during ball milling, and X-ray diffraction analysis (XRD) proved the formation of new intermetallic phases Mg2Sn and Mg2Pb, which were aimed to augment galvanic corrosion of the base metal. The dependency of the material’s reactivity on the activation time and additive content occurred to be non-monotonic. For all tested samples ball milling during the 1 h provided, the highest hydrogen generation rates and yields as compared to 0.5 and 2 h and compositions with 5 wt.% of the Sn–Pb alloy, demonstrated higher reactivity than those with 0, 2.5, and 10 wt.%.
... An alternative to importing green H2 to the plant would be the in-house H2 generation by using recycled Al [50]. Such approaches have already found practical applications, with new plants enabling the generation of approximately 5 kg/h H2 [51]. ...
With an annual global CO2 emission of 34 billion tonnes due to fossil fuel usage, the need for a worldwide gradual decarbonisation plan is urgent. To meet the environmental milestones of 2050, the world needs to contribute an annual 6 % decrease in fossil fuel use, accounting for 73 % of global CO2 emissions. For achieving these goals, Energy Intensive Industries should examine establishing alternative energy supply routes and circular system processes to minimise the need for fossil fuel external energy sources, wastes etc. Hydrogen is widely used in Extractive Industries as a reduction agent for numerous metal oxides, such as iron or cobalt, producing metal with improved environmental footprint. In the aluminium industry, the H2 reduction is not applicable till now, mainly due to the need for very high temperatures and energy demands required for the reduction process. However, H2 shows great potential as a very efficient and environmentally beneficial fuel for heat and electricity cogeneration, which can also be easily produced inside the aluminium production and process line. Additionally, the innovation potential for exploiting H2 for the reduction of primary aluminium production wastes, such as bauxite residues enables their valorisation of wastes transforming them into high added value materials. This paper aims on reporting state-of-the-art H2-based technologies for green electrification and medium / high-grade heat production and proposes a utilisation scheme for secondary aluminium smelting, presenting also the environmental advantages in comparison with conventional fossil fuel-based technologies. The proposed scheme enables a reduction of 49 %, 81 % and 61 % in global warming potential, acidification potential and photochemical oxidant formation respectively.
... This process becomes attractive due to the abundance of aluminum in the earth's crust, greater transport security as a solid fuel and the theoretical gravimetric capacity of H 2 , up to 11.1% in an aluminum -water system (Wang et al. 2012), that exceeds what is established by the United States Department of Energy (US-DOE) for the year 2025 (Abe et al. 2019). In addition, using recycled aluminum is an effective way to reduce the cost per kilogram of hydrogen, below US $2/kg (Buryakovskaya et al. 2017;Elsarrag et al. 2017;Salueña et al. 2021) that the US-DOE establishes as a goal. The aluminum hydrolysis reaction is expressed as follows: ...
This work presents for the first time an integrated hydrogen generation system with storage based on aluminum waste from soda cans to supply hydrogen on-demand to a PEM (proton exchange membrane)-type fuel cell for reliable electricity generation. The raw material that feeds the hydrogen generator consists of distilled water, aluminum from soda cans and sodium hydroxide to remove the oxide layer that passivates the aluminum, a technique known as alkaline activation. The design of the generator was done based on the analysis of the mass and energy balance and its experimental verification. The stainless-steel prototype consisted of a vessel with a capacity of 2.1 L batch reactor, which delivers the gas produced to a column of water to scrub the gas. The three components function as a temporary gas storage system while the fuel is delivered at a regulated pressure. The NaOH container has a maximum storage capacity of 0.45 L, enough for 21 g of aluminum to react and produce 25.7 L (at 0 °C and 10⁵ Pa) of hydrogen; the reaction yield in the generator was 97%. Through the evaluation of the electrical performance at a home-made 9 cm² PEMFC and extrapolation to 45 W, it was calculated that the generator can supply H2 to the cell for 53 min at that power.
Graphical abstract
... It served as an alumina source for the clinker burning process in the production of calcium aluminate cement with high refractory characteristics [8]. In an alkaline solution, the dross can generate hydrogen [9]. Oxide and nitride components were valorized in ceramics, glasses, and glass ceramics [7,8,[10][11][12]. ...
Aluminium dross is a hazardous industrial waste generated during aluminium production. It contains metallic oxides of aluminium and magnesium, other phases (aluminum nitride), and residues of fluxes and salts from the melting process of aluminium. Discarding this by-product is considered an environmental and economic challenge due to the high reactivity of dross with water or even air humidity. After removing the hazardous components from the as-received dross, one of the optional approaches is to incorporate the treated dross into construction materials. Dross is applied in several types of research as a secondary raw material source for alumina, clinker, cement or glass-ceramic production, but only a few papers focus on the usage of dross as a foaming agent for foams. Even fewer research are reported where dross was applied as a basic component of foam glasses. In this work, foam glasses were produced completely from waste materials: Aluminium dross, container (SLS) glass, and cathode ray tube (CRT) glass. The research holds several specificities, i.e., combining two industrial waste materials (CRT glass and dross), and adding an increased amount from the wastes. The physical and mechanical characteristics were examined with a special focus on the effect of the foam glass components on the microstructure, density, thermal conductivity, and compressive strength.
... Therefore, H 2 gas generation from the hydrolysis of SC in MSW landfills poses a particular concern from an engineering control perspective. On the other hand, it became a useful approach and opportunity to generate hydrogen from aluminum wastes as a new source of energy (David and Kopac 2012;Elsarrag et al. 2017;Hiraki et al. 2007;Huang and Tolaymat 2015;Li et al. 2017;Shkolnikov et al. 2011). ...
A systematic approach to understanding the hydrolysis of salt cake from secondary aluminum production in municipal solid waste landfill environment was conducted. Thirty-nine (39) samples from 10 Aluminum recycling facilities throughout the USA were collected. A laboratory procedure to assess the gas productivity of SC from SAP under anaerobic conditions at 50 oC to simulate a landfill environment was developed. Gas quantity and composition data indicate that on average 1400 µmol g−1 (35 mL g−1) of gas resulted from the hydrolysis of SC. Hydrogen was the dominant gas generated (79% by volume) followed by methane with an average of 190 µmol g−1 (21% by volume). N2O was detected at a much lower concentration (1.2 ppmv). The total ammonia released was 680 µmol g−1, and because of the closed system nature of the experimental setup, the vast majority of ammonia was present in the liquid phase (570 mg L−1). In general, the productivity of both hydrogen and total ammonia (the sum of gas and liquid forms ammonia) was a fraction of that expected by stoichiometry indicating an incomplete hydrolysis and a potential for re-hydrolysis when conditions are more favorable. The result provides substantial evidence that SC can be hydrolyzed to generate a gas with relative long-lasting implications for municipal solid waste landfill operations.
https://link.springer.com/article/10.1007%2Fs13762-018-1820-x
https://rdcu.be/V1sb
Hydrogen is the cleanest fuel among the existing with high calorific value ranging from 120 to 140 MJ/kg. It is being considered as ‘a fuel of the future’ from the global warming perspective due to very low or zero carbon emissions. Hydrogen energy is becoming a key component in bringing about the energy transition to ensure a sustainable future. Due to its very high potentials to capture the market in several fields, including automobiles, power generation, chemical, petrochemical and steel industries, and domestic uses, a lot of research has been going on and several innovations have been made in the technologies related to hydrogen production. It can be generated using fossil fuels as well as renewable sources which include natural gas, coal, nuclear, biomass, solar, wind, hydroelectric, and geothermal energy. This book chapter explores the potential of green hydrogen energy generation using renewable energy sources, including solar, wind, and hydroelectric power. It discusses the advantages of making use of renewable energy sources for green hydrogen generation, including the elimination of carbon emissions associated with traditional methods. This chapter also explores the challenges and opportunities associated with green hydrogen energy production with the help of renewable sources of energy, including the need for infrastructure development and investment in their research and development. Overall, this book chapter provides a comprehensive overview of the advantages of green hydrogen energy generation using renewable sources of energy and highlights its role in the gradual shift to a carbon–neutral economy along with future prospects.
