Elements In Ash Research Articles

Mobility of Elements in Ashes from a Wood-Fired Heat and Power Plant with a Grate-Fired Furnace

Mobility of Elements in Ashes from a Wood-Fired Heat and Power Plant with a Grate-Fired Furnace

Effects of alkaline extraction on behavior of rare earth elements in coal ashes.

The effects of alkaline extraction on the behavior of rare earth elements in coal ashes were investigated in the present study. Independent variables are the concentration of extractant and particle size of coal ashes. Sodium hydroxide was used as an extractant, and the molarity of the solvents varied from 1.0 to 7.0M. The coal ashes used here were fly and bottom ashes. Fly and bottom ashes were classified into four samples by particle size, with each categorized at both 45 and 300µm. The particle size distribution and crystalline characteristics of coal ashes, leaching, and the contents of rare earth elements in coal ashes after alkaline extraction were investigated, and the effects of independent variables on the content of rare earth elements in coal ashes were discussed. The test results showed that the dissolution of amorphous phase in coal ashes mainly occurred when the molarity was not more than 3M, while dissolution and precipitation such as geopolymerization and the formation of zeolite occurred simultaneously when the molarity was more than 5M. The dissolution and formation of precipitates such as geopolymer in the present study affected the variation of the rare earth element contents in the ashes. Besides, the ashes being smaller in size was more favorable for an increase in the rare earth elements in coal ashes.

Characterisation and Hydrochloric Acid Leaching of Rare Earth Elements in Discard Coal and Coal Fly Ash

Rare earth elements (REEs) have been identified as valuable and critical raw materials, vital for numerous technologies and applications. With the increasing demand for and supply gap in REEs, many research studies have focused on alternative sources of REEs. This study involved an elemental and mineralogical characterisation of discarded coal from a coal plant and coal fly ash (CFA) from a power station in South Africa for REE presence. XRD results revealed that the discard coal sample consisted mainly of kaolinite, pyrite, siderite, quartz, calcite, gypsum, and muscovite, whereas CFA contained abundant glassy amorphous phases, alumina silicates, quartz, gypsum, calcite, and minute levels of muscovite and hematite. SEM-EDAX showed REE-carrying grains containing phosphorus in both discard coal and CFA samples. This was followed by investigating the leaching potential of REEs using hydrochloric acid from discard coal and CFA. This research’s potential impact is possibly providing a new and sustainable source of REEs. For that purpose, multiple batch leaching tests were performed to investigate the effects of temperature and acid concentration on the leaching efficiencies of REEs from discard coal and CFA. The experimental results indicated that temperature strongly influences REE leaching efficiency, while acid concentration has a lesser impact. This study identifies the best leaching conditions for the total REE recovery as 1 M HCl and 80 °C for discard coal and CFA.

Pilot study on coke oven flue gas injection desulfurization using highly active modified calcium hydroxide desulfurizer

AbstractCalcium hydroxide injection desulfurization has attracted extensive attention because of its low cost and recyclable characteristics. The modified calcium hydroxide was prepared on the basis of the digestion of calcium lignosulfonate (wood calcium) aqueous solution with ethanol and used in the pilot test of flue gas injection desulfurization of the coke oven. The injection desulfurization experiment was carried out with calcium hydroxide modified by 50% ethanol and 20% ethanol+0.5% wood calcium. It was found that the injection desulfurization efficiency of the two modified calcium hydroxide was better than that of the unmodified calcium hydroxide under the same injection conditions. The desulfurization efficiency of 20% ethanol+0.5% calcium hydroxide modified by wood calcium can reach more than 93.7% under the condition of 2 and 5 times calcium to sulfur ratio. The XRF analysis of desulfurization product showed that the content of S element in unreturned desulfurization ash was only 1.28%, which increased to 4.46% after 5 times of return. BET results showed that the specific surface area of the returned desulfurization ash decreased from 35.115m2/g to 10.256m2/g and the pore volume decreased from 0.103cm3/g to 0.0433cm3/g.

Comprehensive evaluation of bioavailable phosphorus in biochar synthesized by co-pyrolysis of sewage sludge and straw ash

The world's phosphorus (P) resources are gradually depleting. Sewage sludge is an important secondary P resource, and sludge-derived biochar for land use is an effective way to achieve P recovery. However, P in biochar synthesized by direct pyrolysis of sludge usually shows comparatively low bioavailability. In this study, biomass ash from different types of straw was used as an additive for co-pyrolysis with sludge. The distribution of different P fractions in the obtained co-pyrolyzed biochar was investigated. The P bioavailability of the co-pyrolyzed biochar was comprehensively evaluated by three methods, including chemical extraction, diffusive gradients in thin films (DGT) technology and pot experiments. The results indicate that the bioavailable P in co-pyrolyzed biochar is significantly positively correlated with the contents of K, Ca, and Mg elements in straw ash, which facilitate the transformation of P in sludge into forms that are more easily utilized by plants, including monetite (CaHPO4), hydroxyapatite (Ca5(PO4)3OH) and pyrocoproite (K2MgP2O7). Moreover, pot experiments show that the P contents in ryegrass shoots and roots cultivated in co-pyrolyzed biochar-added soils increased by 11.98–114.97 % and 28.90–69.70 %, respectively, compared to the control soil. The DGT technology could better reflect the uptake of P by plants with a Pearson correlation coefficient as high as 0.94. This study provides references for P resource recovery, and the collaborative reutilization of sewage sludge and straw ash.

Application of Torrefaction for Improved Fuel Properties of Sunflower Husks

Sunflower husk (SFH) contributes 45–60% of the total sunflower seed weight and is a by-product of the sunflower oil industry. Among other elements, SFH ash contains K, Na, Ca and Mg. These elements cause rapid growth of ash deposits on convective heating surfaces of the boiler, resulting in reduced efficiency. The aim of this paper is to examine the possibility of producing quality fuel from SFH by its pretreatment with the technique of torrefaction in a fluidized bed in superheated water vapor. Continuous monitoring of the innovative SFH torrefaction process allowed for the determination of optimal process durations. SFH could be converted into a biofuel, having high calorific value and suitable characteristics for co-combustion with coal. Furthermore, the torrefaction in a fluidized bed of superheated water vapor allowed for a 6-fold reduction in the required process duration in comparison with data reported from the literature for the process of torrefaction in a dense bed, along with a 3-fold reduction in the chlorine content in SFH ash. These effects are beneficial to resolve the problem of corrosion on convective heating surfaces of boilers. However, torrefaction in superheated water vapor did not significantly reduce the content of alkaline and alkaline-earth elements in SFH ash. Still, this issue may be alleviated by significantly increasing the duration of SFH pretreatment.

Correlation analysis between Radix Pseudostelariae quality and rhizosphere soil factors of Pseudostellaria heterophylla in a cultivation region, China.

Pseudostellaria heterophylla, known for its significant bioactive ingredients, offers potential health benefits. Amounts of bioactive compounds of the tuberous root of cultivated Pseudostellaria heterophylla are sensitive to environmental conditions. We selected 22 sampling sites in Guizhou Province, China, a primary Pseudostellaria heterophylla planting area. We analyzed polysaccharides, water-soluble extractives, total ash and inorganic elements (Fe, Mn, Zn, Mg and Ca) in Radix Pseudostellariae, and pH, organic carbon (OC), available nitrogen (AN), available phosphorus (AP), available potassium (AK) and inorganic elements in the soil. Our study revealed a substantial presence of polysaccharides (85.00-181.00 mg g-1), water-soluble extractives (47.52-57.63%) and total ash (1.87-3.39%) in Radix Pseudostellariae. Polysaccharides and total ash showed no sensitivity to soil pH. Radix Pseudostellariae collected from soil with pH > 7 exhibited slightly higher levels of water-soluble extractives, Mg and Ca than that from soil with pH < 5. Conversely, soil with a pH less than 5 had higher OC, AN, AP and AK contents. Water-soluble extractives in Radix Pseudostellariae were negatively correlated with soil pH but positively correlated with OC and AN. The results imply that the sequestration of soil nutrients over long-term Pseudostellaria heterophylla cultivation could negatively impact the accumulation of some bioactive ingredients in Radix Pseudostellariae. This study has a profound implication for enhancing the quality of Radix Pseudostellariae of artificially cultivated Pseudostellaria heterophylla. © 2024 Society of Chemical Industry.

Distribution of Rare Earth Elements in Ash from Lignite Combustion in Polish Power Plants.

Rare earth elements are an essential critical raw material in the development of modern technologies and are highly sensitive to both supply chain disruptions and market turbulence. The presented study examines the characteristics of fuel, fly ash, and bottom ash from lignite combustion in power plant units. Also, we attempted to determine the amount of amorphous glass in the ashes and whether and to what extent the glass from the ash samples is bound to REY. The suitability of the ash was assessed as an alternative source of REY. The fuel and ash samples were acquired from power plants in Poland. The tests determined the fuel quality parameters, including the chemical and phase composition, of amorphous glass using ICP-MS and XRD methods, respectively. The study showed that all ash samples dissolved in 4% HF were enriched in REY. The efficiency of REY enrichment varied, and its presence in the residue samples was found to be in similar proportions compared to the raw sample. All ash residue samples were enriched in critical elements. The obtained values of the Coutl prospective coefficient allowed for the classification of some of the analyzed ashes and their residues after dissolution in 4% HF as prospective REY raw materials.

Elemental composition of post-wildfire biomass ashes and partly burned woody species in Bohemian Switzerland National Park, Czech Republic.

The study explored the post-wildfire elemental composition of parts (wood, bark, branch, cone, trunk, litter, twig, needle, sward, fallow, sapling, etc.) and by-products (biomass ashes, partly burnt parts, and char) of different woody species in the Bohemian Switzerland National Park, Czech Republic, and considered their effects on soils. Multi-elemental analysis of the fire by-products of the woody species was determined with inductively coupled plasma-optical emission spectrometry and mass spectrometry and compared with control biomass samples unaffected by wildfire. Most fire by-products were slightly alkaline, with acidic ashes obtained from blueberry wood. The by-products of the wildfire were characterized by varied total contents of macro (P, Ca, K, Mg, and S), micro (Na, Mn, Fe, Cu, and Zn), and other elements (B, Co, Mo, and V) vital to soil fertility and plant growth. The mean content of macro elements in the biomass ashes was up to 4.16 P, 23.5 Ca, 2.48Mg, 63K, and 5.57 S g kg-1. These values were comparatively lower than published data for ashes obtained under optimized conditions, e.g., those combusted in power generation facilities. Conversely, partly burnt parts-an indication of incomplete combustion-had higher 9.22 P, 79 Ca, and 5.99Mggkg-1 contents in spruce needles than in biomass ashes and the control. Variations in woody species and anthropogenic activities in areas of wildfires produced varied As, Cd, Cr, Ni, and Pb contents above EU fertilizer regulation. Caution in applying biomass ashes from wildfires on fields is required due to risk/toxic elements input from anthropogenic activities. Wildfire effects on the elemental composition of woody species can provide information on plant parts most suitable for biomass ashes for soil and ecosystem safety.

Assessing the Potential of Rare Earth Elements in Bottom Ash from Coal Combustion in Poland.

The aim of the research was to assess the potential of bottom ash from Polish coal-fired power plants as an alternative source of rare earth elements (REY). The potential of these ashes was compared with fly ash from the same coal combustion cycle. The phase and chemical composition, as well as REY, were determined using: X-ray diffraction and inductively coupled plasma mass spectrometry. The tested ashes were classified as inert-low pozzolanic and inert-medium pozzolanic, as well as sialic and ferrosialic, with enrichment in detrital material. The phase and chemical composition of bottom ash was similar to fly ash from the same fuel combustion cycle. The REY content in the ash was 199-286 ppm and was lower than the average for global deposits, and the threshold value was considered profitable for recovery from coal. Bottom ash's importance as a potential source of REY will increase by recovering these metals from separated amorphous glass and mullite and grains rich in Al, Mg, K, and P. The industrial value of bottom ash as an alternative source of REY was similar to fly ash from the same fuel combustion cycle.

Microwave-induced plasma optical emission spectrometry (MIP-OES) analysis of the major elements in woody biomass ash following microwave acid digestion

The increasing use of woody biomass for sustainable heat and power is generating large amounts of woody biomass ash (WBA), which needs to be safely disposed of or recycled. In this study, the utility of Microwave-induced plasma optical emission spectrometry (MIP-OES) with microwave-assisted acid digestion for simplifying analyses of the major elements of WBA was investigated. Calibration curves exhibited good linearity (R2 > 0.999). Internal standardization using three emissions lines (324.754 nm of Cu, 451.131 nm of In and 371.029 nm of Y) showed that calibration with Cu (324.754 nm) correction resulted in the best linearity. Physical effects, even the presence of hydrofluoric acid or boric acid in mixed acids used for digestion, were of trivial influence with internal standard recoveries were within 0.95 to 1.05 times those of the blank sample. The limit of detection of MIP-OES for seven measured elements was 0.85–89 μg/L, 0.23–2.8 times higher than that of inductively coupled plasma optical emission spectrometry (ICP-OES). The recovery of elements in a certified fly ash reference material as determined by MIP-OES was 0.80–1.08. Elemental quantification of WBA samples by MIP-OES showed a strong correlation with that by ICP-OES. However, in a Welch's t-test, the MIP-OES values were significantly higher for K and significantly lower for Al and Ca in a majority of the samples. Nonetheless, considering the good correlation between their results, MIP-OES can replace ICP-OES for the analysis of WBA.

Elemental composition of &lt;i&gt;Vaccinium vitis-idaea&lt;/i&gt; и &lt;i&gt;V. myrtillus&lt;/i&gt; (Ercaceae) leaves in green moss pine forests under aerotechnogenic pollution in the Komi Republic

The paper aims at the impact of aerotechnogenic emissions from the largest in the European North pulp and paper production enterprise, namely JSC «Syktyvkar Timber Processing Complex», on the elemental composition (N, S, C, P, K, Ca, Mg, Na, Al, Fe, Mn) of lingonberry and blueberry leaves as the dominant dwarf shrubs in green moss pine forests. The leaves of blueberry and lingonberry growing in pine stands both in the background and contaminated areas were identified to have similar average values of the mass fraction of ash elements in 2009. The content of ash elements in the leaves of dwarf shrubs from the background pine forests was higher than that in leaves collected from the impact zone in 2018. The average values of the mass fraction of ash elements in blueberry leaves were found to access those in lingonberry leaves by 1,5 time both in the background and contaminated areas. There was no regular change in the content of elements in leaves of dwarf shrubs with distance from the source of emission. The differences in the sulfur content in leaves of dwarf shrubs for 2009 and 2018 were within the error limits. No significant differences were found in the values of the mass fraction of nitrogen in blueberry and lingonberry leaves for pine stands located at different distances from the emission source. The nitrogen content in lingonberry leaves was significantly lower than that in blueberry leaves for both observation periods. There was no significant difference in the total nitrogen content in blueberry and lingonberry leaves between 2009 and 2018.

Microbial consortia-driven bioweathering provides new potential for sustainable recovery of rare earth elements (REE) in fly ash: From metagenome exploration to performance verification

This study presents a novel approach to extracting rare earth elements (REE) from fly ash (FA) using environmentally adapted microbial consortia, highlighting a sustainable alternative to traditional extraction methods. Through comprehensive geochemical characterization of FA obtained from a power plant in China, a complex matrix rich in REE was identified. Microbial consortia isolated from both sludge and FA demonstrated distinct and interactive communities with specialized adaptations for REE bioweathering, as revealed by metagenomic analysis and molecular ecological network assessments. These communities exhibited diverse metabolic profiles, emphasizing ion transport, energy production, and carbohydrate and lipid metabolism tailored to their specific environmental contexts. Enzymatic profiling further elucidated the critical roles of siderophore production and redox reactions in the bioweathering process. Ex-situ bioweathering experiments showcased the consortia's capability to efficiently mobilize specific REE. Notably, under optimized conditions (10 % inoculum of Sludge_LB at 30 °C), significant extraction efficiencies were observed, such as 0.119 mg/g for Sc and 0.068 mg/g for Y; similarly, 10 % inoculum of FA_M9 at 30 °C showed an extraction efficiency of 0.036 mg/g for La. Recovery rates for various REE ranged from 29 % to 83 %, were obtained in a short time (48 hours) demonstrates the effectiveness of this method. These results demonstrate the sustainability of microbial consortia for REE extraction, offering reduced environmental impact compared to conventional methods. This research not only provides a viable method for REE recovery from industrial waste but also contributes to broader goals of sustainable resource utilization and environmental protection.

Decomposition of green manure and nutrients release in Subarctic, Kola Peninsula, Russia

In the field experiment, the intensity of decomposition and release of nutrients was studied for six types of plant residues – leaves, panicles and straw of oats (Avena sativa), as well as whole plants of lupine (Lupinus angustifolius), phacelia (Phacelia tanacetifolia) and vetch (Vicia sativa) in the arable horizon of Anthrosols on the Kola Peninsula. Samples in mesh nylon bags were sampled after 8, 12 and 24 months of exposure in soil. The loss of weight, the content of Corg and Norg, as well as ash elements – Si, Al, Fe, K, Ca, Mg, P, S and Mn were determined in all plant residue samples. As the results showed, despite the low temperatures, the decomposition of green manure in soil occurred with a high intensity, comparable to the southern chernozem zone: after a year of exposure in the soil, plant residues lost from 47% (oat straw) to 75% (lupine) of their initial ash-free weight. After 2 years, weight loss reached 68% in oat straw and 90% in lupine. The distribution of losses of Corg, Norg, and P between the types of plant residues and decomposition periods correlated significantly (at p≤0.01) with the distribution of weight losses. Changes in the content of other ash elements did not depend on weight loss: depending on the type of material and the stage of decomposition, the samples could not only lose them (K – by all plant residues; Mn – by lupine; S, Ca and Mg – by all plant residues, except straw and oat panicles), but also accumulate them in quantities exceeding the initial ones (Fe – by all species, Mn – by all species except lupine; Ca and Mg – by straw and oat panicles) at certain periods. The accumulation of elements above initial level means that the transformed plant residues can accumulate additional amounts of elements from the soil solution, while the irregular alternation of increases and decreases in Ca, Mg, S, Fe and Mn indicates the reversible nature of the process. Due to the significant differences between the types of green manure in terms of chemical composition, rate and dynamics of decomposition and release of nutrients, their use provides great opportunities for managing soil fertility and the intensity of elements cycling in agrocenoses through the species selection.

Different drying methods alter the quality parameters of ethnobotanically important Curcuma caesia Roxb. rhizomes

Curcuma caesia Roxb. of the Zingiberaceae family, is an ethnobotanically important rhizomatous perennial herb and is commonly known as “Black turmeric”. Like in other species of Curcuma, the pharmacologically important polyphenol curcumin is also found in C. caesia. In traditional medicine, C. caesia has been used to treat piles, leprosy, asthma, cancer, diabetes, fertility, toothache, vomiting, allergies, etc. Drying is considered the simplest and most cost-effective means of preserving raw plant materials, safeguarding the integrity of nearly all biologically active substances. Medicinal plant materials are primarily utilized in their dried forms in pharmaceutical industries. However, it has been observed that there is a lack of comprehensive information on the effects of different drying methods on quality parameters, and other pharmaceutically important aspects of C. caesia. Hence, here, we investigated the impact of various drying methods, such as direct sunlight exposure, solar drying, shade drying, and conventional oven drying with or without previous boiling, on the quality parameters of C. caesia rhizome, such as moisture, ash, and curcumin content. The results suggest that oven drying at 100 ?C, despite possessing favorable criteria for drug designing like the smallest particle sizes and the lowest moisture content, did not restore the maximum level of ash, curcumin, and essential mineral elements. Nevertheless, boiling in the range of 60 ?C – 80 ?C for 30 minutes before drying restores the pharmaceutically important qualities more favorably. The results of this study will help to formulate better treatment for restoring the market-preferable optimum quality of C. caesia.

Impact of wildfire ash on skin and gut microbiomes and survival of Rana dybowskii

Climate change and human activities escalate the frequency and intensity of wildfires, threatening amphibian habitats and survival; yet, research on these impacts remains limited. Wildfire ash alters water quality, introduces contaminants, and may disrupt microbial communities, impacting gut and skin microbiota; however, the effects on gut and skin microbiota remain unclear. Rana dybowskii were exposed to five concentrations (0 g L-1, 1.25 g L-1, 2.5 g L-1, 5 g L-1, and 10 g L-1) of aqueous extracts of wildfire ashes (AEAs) for 30 days to assess AEAs' metal content, survival, and microbiota diversity via Illumina sequencing. Our results showed that the major elements in ash were Ca > K > Mg > Al > Fe > Na > Mn, while in AEA they were K > Ca > Na > Mg > As > Al > Cu. A significant decrease in amphibian survival rates with increased AEA concentration was shown. The beta diversity analysis revealed distinct shifts in microbiota composition. Notably, bacterial genera associated with potential health risks showed increased abundance in skin microbiota, emphasising the potential for ash exposure to affect amphibian health. Functional prediction analyses revealed significant shifts in metabolic pathways related to health and disease, indicating that wildfire ash exposure may influence amphibian health through changes in microbial functions. This study highlights the urgent need for strategies to mitigate wildfire ash impacts on amphibians, as it significantly alters microbiota and affects their survival and health.

Preparation and Properties of Expansive Backfill Material Based on Municipal Solid Waste Incineration Fly Ash and Coal Gangue

To realize the large-scale utilization of municipal solid waste incineration (MSWI) fly ash in the field of building materials and to reduce the cost of coal mine backfill mining, the effects of the mixing ratio of cementitious materials, the particle size distribution of aggregates, and the amount and mass concentration of cementitious materials on the properties of backfill materials were experimentally investigated, and the microstructure of the hydration products was analyzed. The results showed that as the mass ratio of MSWI fly ash to bottom ash increased, the rate of expansion of the cementitious system continued to increase, and the compressive strength of the cementitious system continued to decrease. The Al (aluminum) and AlN (aluminum nitride) in the fly ash reacted with water to generate gas, causing the expansion of the cementitious materials; NaOH increased the alkalinity of the solution, which promoted the formation of more bubbles, thereby improving the expansion performance of the cementitious material. When the content of NaOH was 0.9%, the sample rate of expansion could reach 15.9%. The addition of CaCl2 promoted the early hydration reaction of the cementitious material, forming a dense microstructure, thus improving the early strength and rate of expansion of the cementitious material. The compressive strength of the backfill body increased as the fractal dimension of the aggregate particles increased, and the particle grading scheme of group S1 was optimal. The 1-day, 3-day, and 28-day strengths of the backfill body of group S1 reached 0.72 MPa, 1.43 MPa, and 3.26 MPa, respectively. It is recommended to choose a backfill paste concentration ranging between 78.5% and 80% and a reasonable amount of cementitious material between 20% and 25%. After the MSWI fly ash was prepared as a backfill material, the leaching of potentially harmful elements in the fly ash was greatly reduced, and the concentration of dioxin was reduced to 13 ng TEQ/kg. This was attributed to the dilution of the cement, the physical encapsulation of gel products, and the isomorphous replacement of Ca2+ in calcium aluminate chloride hydrate.

Агроэкологическая оценка применения нетрадиционных удобрений в посевах овса

The article examines the effect of non-traditional fertilizers on the yield and quality of oat grain, as well as the content of heavy metals in the grain. It is proved that with the combined use of sewage sludge and organic mineral fertilizer HUMITON, the content of heavy metals in oat grain is below the detection limit, and the highest yield of the studied crop is also noted. The maximum content of protein and ash elements in oat grain was revealed when using HUMITON. With the combined use of non-traditional fertilizers, grain quality indicators remain at the level of the control variant. Keywords: NON-TRADITIONAL FERTILIZERS, SEWAGE SLUDGE, HUMITON, HEAVY METALS, OATS, YIELD

Recovery of phosphate from incineration ash of sewage sludge by chlorination and carbo-chlorination

In this study, the volatilization behavior of the constituent elements of sewage sludge incineration ash (SSA) with and without carbon during the chlorination was investigated for recovering P. For chlorination of SSA, Fe and K volatilized from 700 to 800 °C, no volatilization of P was observed. For chlorination of SSA with carbon, Fe, P, and Si volatilized from low temperatures, reaching volatility rates of 80, 55, and 35 %, respectively, at 1000 °C. When chlorinated SSA/C (sample with carbon added to chlorination residue prepared at 1000 °C for 30 min holding), P volatilized from 800 °C (10 %), reaching a volatilization rate of 75 % at 1000 °C. P volatilization increased from 10 to 55 % until 60 min holding at 800 °C without volatilization of Si, Mg, and K. Although P volatilization progressed at 900–1000 °C holding, Al, Mg, and Si also volatilized. These results indicate that combination of chlorination/carbo-chlorination is suitable for selective volatilization of P.

Thermodynamic analysis on the fate of ash elements in chemical looping combustion of solid fuels – Manganese-Based oxygen carriers

Chemical looping combustion (CLC) is an innovative technology suitable for converting waste-derived fuels into heat and power. The process inherently produces pure CO2, which is highly favorable for carbon capture and storage and could be instrumental for achieving negative emissions. CLC operates by utilizing solid oxygen carriers (OCs) to transfer heat and oxygen between two reactors. The OC play a crucial role in achieving an efficient combustion. Manganese-based OCs are particularly interesting, due to their ability to release gaseous oxygen. However, ash components from solid fuels could alter their oxygen transfer capacity, and cause problems related to corrosion and agglomeration. The objective of this work is to obtain in-depth insights about Mn-based OCs for CLC of waste-derived fuels. This is achieved by investigating phase transitions during CLC of solid fuels when utilizing two manganese-based OCs: manganese oxide and a representative manganese ore. For this purpose, thermodynamic modeling is employed, and a specific focus is given to K, Na, Cu, Zn, and Pb, due to their important role in corrosion and/or agglomeration. Thermodynamic databases are expanded by calculating properties from first-principles. It is shown that Mn-based OCs are suitable for effectively converting waste-derived fuels while limiting corrosion. Furthermore, the iron in manganese ores is found to have positive implications for oxygen-transfer reactions. In terms of alkali release to the gas phase, manganese ore seems to be a more promising material compared to manganese oxide. The pathways for the heavy metals Zn, Cu, and Pb were, meanwhile, independent of the OC type.