Primary Raw Materials Research Articles

Real-Time Control of Sintering Moisture Based on Temporal Fusion Transformers

The quality of sintered ore, which serves as the primary raw material for blast furnace ironmaking, is directly influenced by the moisture in the sintering mixture. In order to improve the precision of water addition in the sintering process, this paper proposes an intelligent model for predicting water-filling volume based on Temporal Fusion Transformer (TFT), whose symmetry enables it to effectively capture long-term dependencies in time series data. Utilizing historical sintering data to develop a prediction model for the amount of mixing and water addition, the results indicate that the TFT model can achieve the R squared of 0.9881, and the root mean square error (RMSE) of 3.5951. When compared to the transformer, long short-term memory (LSTM), and particle swarm optimization–long short-term memory (PSO-LSTM), it is evident that the TFT model outperforms the other models, improving the RMSE by 8.5403, 6.9852, and 0.453, respectively. As an application, the TFT model provides an effective interval reference for moisture control in normal sintering processes, which ensures that the error is within 1 t.

Circular economy as applied to refractory materials.

The closed-loop economy concerning refractory materials is implemented through systematic involvement in post-operational usage in thermal, including metallurgical, units as secondary (by-product) raw materials. This is one of today's trends in resource and energy economics, reducing carbon footprint and CO2 emissions, decreasing waste with subsequent disposal in landfills. Purified scrap of refractory materials is used as supplementary materials in metallurgical processes, commonly referred to as scrap utilization when used as fluxes to adjust slag composition in metallurgical units, molded materials for welding in converters, refractory fillers in the production of unformed materi-als for sections lining working outside the aggressive influence of molten metal and slag, etc. For these purposes, the scrap is sorted into grades, crushed and screened, occasionally incorporating other products. Refractory scrap after ser-vice in metallurgical units usually has higher impurity content, higher porosity, and contains fragmented remnants of the refractory structure. Recycling refractory scrap may additionally involve technological methods for extracting impurities (enrichment) with subsequent use of the recyclate directly in refractory production, partially replacing primary raw materials. In this case, research work with involvement of qualified specialists and the entire body of knowledge in creating new refractory materials is necessary. Practice has shown that qualified involvement of recyclate in manufacturing processes of high-quality refractories is accompanied by solving non-standard tasks and requires a special approach, including the issue of removing introduced or formed foreign materials in refractory material during its operation. Enrichment is an effective direction for cleaning refractory scrap, extracting quality materials during processing of waste from mining enterprises, materials of technogenic origin to obtain recyclate of necessary quality. The enrichment technology is selected based on the set tasks. Recyclate quality for use alongside primary raw materials must guarantee refractory manufacturers meet the corresponding requirements of end-users. An original technology of recyclate enrichment during its selective grinding with product separation using air-gravitational and centrifugal-air classification has been developed

Circular economy as applied to refractory materials

The closed-loop economy concerning refractory materials is implemented through systematic involvement in post-operational usage in thermal, including metallurgical, units as secondary (by-product) raw materials. This is one of today's trends in resource and energy economics, reducing carbon footprint and CO2 emissions, decreasing waste with subsequent disposal in landfills. Purified scrap of refractory materials is used as supplementary materials in metallurgical processes, commonly referred to as scrap utilization when used as fluxes to adjust slag composition in metallurgical units, molded materials for welding in converters, refractory fillers in the production of unformed materi-als for sections lining working outside the aggressive influence of molten metal and slag, etc. For these purposes, the scrap is sorted into grades, crushed and screened, occasionally incorporating other products. Refractory scrap after ser-vice in metallurgical units usually has higher impurity content, higher porosity, and contains fragmented remnants of the refractory structure. Recycling refractory scrap may additionally involve technological methods for extracting impurities (enrichment) with subsequent use of the recyclate directly in refractory production, partially replacing primary raw materials. In this case, research work with involvement of qualified specialists and the entire body of knowledge in creating new refractory materials is necessary. Practice has shown that qualified involvement of recyclate in manufacturing processes of high-quality refractories is accompanied by solving non-standard tasks and requires a special approach, including the issue of removing introduced or formed foreign materials in refractory material during its operation. Enrichment is an effective direction for cleaning refractory scrap, extracting quality materials during processing of waste from mining enterprises, materials of technogenic origin to obtain recyclate of necessary quality. The enrichment technology is selected based on the set tasks. Recyclate quality for use alongside primary raw materials must guarantee refractory manufacturers meet the corresponding requirements of end-users. An original technology of recyclate enrichment during its selective grinding with product separation using air-gravitational and centrifugal-air classification has been developed

A study on composite carbonaceous reducing agent pellets based on low-order unbonded coal

To minimize the cost of carbon-reducing agents and reduce the waste of powder in production, a novel composite carbonaceous reducing agent pellet was prepared through cold pressing, utilizing low-rank unbonded coal (NC) as the primary raw material and incorporating petroleum coke (PC) and high-bonding coal (HVC). This study investigated the influence of different material composition ratios, the addition of organic binder (OBD) and inorganic binder (IBD) (water glass solution), forming moisture ranging from 2 to 12 %, holding temperatures of 60 to 100 ℃, holding times of 2 to 6 h, and material particle sizes ranging from 40 to 250 mesh (0.063–0.420 mm). Additionally, forming pressures of 5 to 30 MPa were analyzed concerning their impact on the cold consolidation strength (CCS) of the resulting pellets. The primary and secondary effects of forming pressure, forming moisture, binder content, and raw material size on pellet strength were examined. According to the actual production situation, the optimum technological conditions were determined. The primary and secondary effects on CCS were ranked as follows: forming pressure > particle size of raw material > binder ratio of 4 % content > forming moisture. External morphology and internal structures of different carbon materials were characterized via FESEM, BET, FTIR, XRD, and XPS. Mechanisms affecting the pellet strength were analyzed. The newly developed composite carbon-reducing agent pellets were suitable for industrial silicon production. This study presented a pathway for the clean and efficient utilization of low-rank unbonded coal and low-viscosity coal, offering substantial economic and social benefits.

PGPB Consortium Formulation to Increase Fermentable Sugar in Agave tequilana Weber var. Blue: A Study in the Field.

Agave tequilana Weber var. Blue is used as the primary raw material in tequila production due to its fructans (inulin) content. This study evaluates the formulation of a plant-growth-promoting bacteria (PGPB) consortium (Pseudomonas sp. and Shimwellia sp.) to increase sugars in A. tequilana under field conditions. A total of three doses were tested: low (5 L ha-1), medium (10 L ha-1), and high (15 L ha-1), with a cellular density of 1 × 108 CFU mL-1 and one control treatment (without application). Total reducing sugars (TRS), inulin, sucrose, glucose, fructose, and plant growth were measured in agave plants aged 4-5 years at 0 (T0), 3 (T3), 6 (T6), and 12 (T12) months. Yield was recorded at T12. The TRS increased by 3%, and inulin by 5.3% in the high-dose treatment compared to the control at T12. Additionally, a low content of sucrose, glucose, and fructose (approximately 1%) was detected. At T12, the weight of agave heads increased by 31.2% in the medium dose and 22.3% in the high dose compared to the control. The high dose provided a higher inulin content. The A. tequilana plants were five years old and exhibited growth comparable to the standards for 6-7-year-old plants. This study demonstrates a sustainable strategy for tequila production, optimizing the use of natural resources and enhancing industry performance through increased sugar content and yield.

Effects of Different Carbon and Nitrogen Ratios on Yield, Nutritional Value, and Amino Acid Contents of Flammulina velutipes.

The carbon-to-nitrogen (C/N) ratio in the cultivation medium significantly influences the growth rate, vigor of mycelium, yield of fruiting bodies, and their nutritional composition. Recently, agricultural and forestry wastes have been increasingly used in cultivating Flammulina velutipes. However, systematic research on how these materials affect the nutritional and functional properties of the fruiting bodies is lacking. This study investigated the effects of different C/N ratios on F. velutipes cultivation. We evaluated the agronomic traits, nutritional composition, and flavor compounds of the fruiting bodies. Our findings reveal that an optimal C/N ratio of 27:1 in the composted substrates enhances the total yield of fruiting bodies, with 25.1% soybean straw as the primary raw material. This ratio also significantly increases the levels of crude protein, total amino acids, and essential amino acids in the fruiting bodies (p < 0.05). Fruiting bodies from the high-nitrogen (HN) treatment showed the highest content of umami amino acids and equivalent umami concentration value. Additionally, we employed an untargeted liquid chromatography-mass spectrometry (LC-MS)-based metabolomics approach to analyze the metabolite profiles of fruiting bodies cultivated in high-nitrogen (HN), medium-nitrogen (MN), and low-nitrogen (LN) substrates. We found that the carbon-nitrogen ratio can affect the flavor and quality of fruiting bodies by regulating amino acid biosynthesis and metabolism and other related pathways. Our results suggest that a C/N ratio of 27:1 offers numerous benefits for the cultivation of F. velutipes with comprehensive analyses and has promising application prospects.

Development of sustainable alkali-activated slag bricks with high content of carbonated recycled concrete fines: Strength, microstructure and environmental benefit

This research presents a novel method of recycling construction waste while capturing CO2 through the formation of mineral carbon. The technology uses carbonated recycled concrete fines (CRCF) as the primary raw material to produce sustainable, high-performance alkali bricks with high replacement rates. Firstly, a general assessment of the physical and chemical properties of CRCF was carried out, which revealed the formation of silica gel encapsulating the surface of CRCF during carbonation. Subsequently, alkali bricks were prepared utilizing CRCF. The study investigated the impact of various mix proportions, water-to-cement ratios, and manufacturing process parameters on brick strength. Additionally, an in-depth analysis of reaction products and brick microstructures was carried out. The results showed that the bricks produced from CRCF were stronger than those from RCF, indicating enhanced reactivity after carbonation. Finally, an analysis demonstrated that utilizing RCF from construction waste can significantly reduce carbon dioxide emissions, thereby mitigating the environmental impact associated with cement production.

Influence of structure-forming recipe ingredients on the quality of pumpkin marmalade

Analyzing the assortment of the market for marmalade products, it is worth noting that there is a tendency to introduce natural products in the form of vegetable or fruit puree into the recipe composition, as the demand for confectionery products for therapeutic, prophylactic, and functional purposes, as well as for products with dietary properties, is growing. This work aims to study the influence of structure-forming recipe ingredients on the quality of pumpkin jelly marmalade. Pumpkin puree was used as the primary raw material for producing jelly marmalade, food agar was used as a gelling agent, and natural honey was used as a sweetener. During the study, organoleptic, physicochemical, and microbiological quality indicators of semi-finished pumpkin products and finished marmalade samples were determined. The color assessment of the finished products was carried out using a colorimeter NR-UO (China). Pumpkin semi-finished and finished products meet regulatory documentation requirements regarding organoleptic, physico-chemical, and microbiological quality indicators. When food agar is used as a gelling agent, the degree of color increases due to the transparency of the structure, and the red (+a*) and yellow (+b*) components in samples containing food agar are successfully combined and give the finished product an attractive orange color. To increase the nutritional -value, it is proposed to use cinnamon or coconut flakes, which have beneficial properties, to sprinkle the surface of finished products. The price for 1 kg of pumpkin jelly marmalade was: control sample - 335.46 rubles, “Məkhəbbət” with cinnamon - 748.85 rubles, “Məkhəbbət” with coconut flakes - 725.36 rubles. For a new type of confectionery products, regulatory and technical documentation STO, TI, RC 00493497-005-2022 “Halal” pumpkin jelly marmalade “Məkhəbbət” has been drawn up.

Preparation of coal gangue based foamed ceramics with SiC as blowing agent and study on its thermal insulation performance

The main objective of this study was to utilize coal gangue as the primary raw material and SiC as the foaming agent to successfully prepare foamed ceramics using the high-temperature foaming method. The study investigated the composition and crystal phases of the foamed ceramics formulation, the influence of sintering parameters on the microstructure and physical properties of the samples, as well as the reaction mechanisms during the foaming process. The experimental results showed that when the SiC addition amount was 2.5 wt%, the sintering temperature was 1230°C, and the sintering time was 60 min, the bulk density of the foamed ceramics reached as low as 0.414 g/cm3, with a compressive strength of 1.64 MPa and a closed porosity as high as 74.86%. Additionally, the water absorption and thermal conductivity were simultaneously reduced to 1.48% and 0.1968 W/(m·K), respectively. Besides maximizing the utilization of coal gangue, foamed ceramics also demonstrated excellent porous structure and physical properties, making them suitable for use as thermal insulation materials.

Effect of Addition of Seaweed (Sargassum sp) Charcoal with Pure Graphite on the Electrical Properties of Graphene Oxide Synthesized by the Modified Hummer’s Method

Graphite is the primary raw material used to create graphene oxide. However, other biomass sources can also be used to create or combine the carbon source. Seaweed (Sargassum sp.), which has a decent carbon content, was used in this study as the biomass used as a carbon source for mixing. The objective of this research is to ensure how adding seaweed charcoal will affect the electrical characteristics of graphene oxide. The modified Hummer process was used to create the materials. There are four different compositions available: pure graphite (100%), 70:30 (graphite and seaweed), 60:40 (graphite and seaweed), and 50:50 (graphite and seaweed). The product of graphene oxide variations made from other compositions will be compared to those of 100% graphite composition. The result demonstrated that the addition of seaweed charcoal to the graphene oxide synthesis was successful. It can be seen from some of the characteristics of graphene oxide at an angle of 2Ɵ by XRD testing. In the FTIR test, it was discovered that the graphene oxide sample contained C-O, C=O, C=C, and O-H functional groups, and in the SEM test, peeling was discovered on the sample surface as a result of the oxidation process. The addition of seaweed charcoal with pure graphite synthesized by the modified Hummers method affects the electrical properties of the resulting graphene oxide. The material's conductivity value and the area capacitance value of the graphene oxide material both drop in the LCR Meter characterization instrument.

ANALYSIS OF COST OF GOODS PRODUCED AND VALUE-ADDED AT UMKM TEMPE "TROSOBO" TUBAN

Soybeans are a food commodity that contains high vegetable protein and is generally used for food consumption. To meet the demand for tempeh agroindustry that uses soybeans as the primary raw material, agroindustry players increase soybean production. However, they still need to meet this demand. Therefore, the government meets this demand by importing. The research was conducted at UMKM Tempe Trosobo, located in Jl. Brawijaya, Gang Yudistira No. 641, Kebonsari, Kec. Tuban, Kab. Tuban, East Java. This study aims to calculate the cost of goods produced using the Full Costing method and analyze the added Value generated by UMKM Tempe "Trosobo" Tuban from soybean processing. The methods used are the Full Costing method and the Hayami method. The results showed that the calculation of the cost of goods produced in the temple agroindustry of Tempe Trosobo UMKM using the complete costing method was IDR 4,300/piece with the total production of tempe produced as many as 22,500 pieces, and the selling price was IDR 5,100/piece. Processing soybeans into tempeh has a value-added result of IDR 11,925 / kg of raw material or 49%, and the added Value of tempeh is classified as high

Variations in Composition and Size of Red Sand in Pinang City, North Sumatra to Improve Concrete Quality

This study further explores the problems in the concrete material studied in terms of variations in the structure of the constituent materials and the grain size of red sand on the compressive strength test of quality concrete material with code K-350. The primary raw material uses red sand with compositions ranging from 0%, 2%, 4%, and 6% with sizes ranging from 120, 100, and 80 mesh. After all the ingredients are mixed, printing is carried out according to the predetermined sample size; after the sample is deposited for one day and one night, the sample is opened from the mold mall. To see the quality of the sample, testing was carried out by testing the concrete structure through the SEM test, and the sample elements were looked at by testing XRD, compressive strength, and water absorption. The results obtained were a successive decrease in water absorption in red sand samples with a composition of 4%. In addition, the maximum compressive strength value was obtained at the proportion of 120 mesh material, and 6 percent of the material composition obtained a compressive strength value of 35.27 MPa. When viewed from the size of the concrete structure using the scanning Electron Microscope test, it was found that the size of the red sand mixture concrete structure has a much smaller pore structure when compared to other mixtures. and in the X-Ray Diffraction test, it was found to contain elements in the form of SiO2, CaO3, Ca (OH)2 with the highest intensity of silicon.

Xylene adsorption behaviors of Co-MOF-74(X) synthesized from Co(II) salt with different anions

Xylene, a typical volatile organic compound (VOC) and primary raw material in the chemical industry, has been found to be a key component in ozone formation. Metal organic frameworks (MOFs) containing open metal sites are capable of binding to xylene. To recover xylene from waste solvent and to mitigate the environmental risks associated with it, three 1D coordination polymers (CPs), Co-MOF-74(X) (X = OAc–, Cl–, or NO3–), were synthesized using various cobalt salts of Co(OAc)2·4H2O, CoCl2·6H2O and Co(NO3)2·6H2O to investigate the influence of anions. Moreover, the liquid phase adsorptive performance for xylene was evaluated. The morphology features and structure differences of the resulting Co-MOF-74(X) were determined by SEM-EDS, XRD, N2/CO2 adsorption, FTIR and XPS. In situ DRIFT was applied to further distinguish the adsorption performance of Co-MOF-74(X) for xylene. The results indicated that Co-MOF-74(X) exhibits a different morphology. Co-MOF-74(OAc–) is flaky and agglomerated severely, while both Co-MOF-74(Cl–) and Co-MOF-74(NO3–) are hexagonal rod–like crystals. All of Co-MOF-74(X) showed microporous structures with high specific surface areas. A small amount of Cl– was retained in Co-MOF-74(Cl–), forming a Co–Cl bond with Co(II), and the active site of adsorption increased. Co-MOF-74(Cl–) shows the highest adsorption capacity of 1317.65 mg/g for the xylene mixture with excellent cyclic stability reported so far, which is 2.17 or 2.78 times more than Co-MOF-74(NO3–) or Co-MOF-74(OAc–). Therefore, it is anticipated to be a highly efficient adsorbent for removal or recovery of xylene.

Carbonation of Recycled Concrete Aggregates for New Concrete and Concrete Fines to Make Cement-Free Hollow Blocks

Mineral carbonation provides a way to increase the recycling of concrete waste in added-value products, and contributes to the principles of the circular economy. At present, most concrete waste is still downcycled. The high water absorption of recycled concrete aggregates, among other factors, impedes their recycling in the concrete industry. The quality of coarse recycled concrete aggregates (RCA) can, however, be enhanced by carbonation. Even when starting with high-grade RCA obtained from a selective demolition process, the carbonation process can decrease the water absorption of the RCA to as low as 3.0%. Concrete with a 50% replacement rate of carbonated RCA can be produced without a significant compressive strength reduction. The research further shows that carbonation can be performed at atmospheric pressure and low CO2 concentrations (e.g., 10%). The recycled concrete fines (RCF, 0–4 mm) in combination with 25% stainless steel slag were used to make zero-cement hollow blocks (39 × 19 × 9 cm) by carbonation curing without using any hydraulic binder. The hollow blocks have a compressive strength of 15.4 MPa at the lab scale. Both technologies were demonstrated on a pilot scale. In both processes, CO2 is immobilized in the resulting construction product. The developed production processes use less primary raw materials and cause less greenhouse-gas emissions than the production of traditional concrete products.

Hybrid modeling for carbon monoxide gas-phase catalytic coupling to synthesize dimethyl oxalate process

Ethylene glycol (EG) plays a pivotal role as a primary raw material in the polyester industry, and the syngas-to-EG route has become a significant technical route in production. The carbon monoxide (CO) gas-phase catalytic coupling to synthesize dimethyl oxalate (DMO) is a crucial process in the syngas-to-EG route, whereby the composition of the reactor outlet exerts influence on the ultimate quality of the EG product and the energy consumption during the subsequent separation process. However, measuring product quality in real time or establishing accurate dynamic mechanism models is challenging. To effectively model the DMO synthesis process, this study proposes a hybrid modeling strategy that integrates process mechanisms and data-driven approaches. The CO gas-phase catalytic coupling mechanism model is developed based on intrinsic kinetics and material balance, while a Long Short-Term Memory neural network is employed to predict the macroscopic reaction rate by leveraging temporal relationships derived from archived measurements. The proposed model is trained semi-supervised to accommodate limited-label data scenarios, leveraging historical data. By integrating these predictions with the mechanism model, the hybrid modeling approach provides reliable and interpretable forecasts of mass fractions. Empirical investigations unequivocally validate the superiority of the proposed hybrid modeling approach over conventional data-driven models and other hybrid modeling techniques.

Compressive strength assessment bricks manufactured with Phosphogypsum in different dosages

This research studies soil-compacted bricks using Phosphogypsum (PG) in their dosage. PG is the subproduct of the primary raw material used by the fertilizer industry, and its disposal is a challenge for the industry because of its large generation. Laboratory tests were performed to assess these bricks' physical characteristics. To obtain the bricks, two dosages were used: 4 and 7% of Phosphogypsum (PG) concentration. Bricks with no Phosphogypsum (PG) in their mixture were also assessed as a benchmark. The brick's physical characteristics were obtained for non-fired and fired bricks (900ºC for 96 hours in the oven). The results of the laboratory tests were analyzed through statistical analysis to explore the differences between the means for each studied condition (dosage and drying method). Furthermore, there was no statistical difference between the compressive strength of bricks manufactured with 4 and 0% PG, pointing out that until this percentage, the studied bricks did not show strength reduction with PG increasing. The fired bricks showed higher strength for all dosages than the non-fired ones. However, according to the Brazilian Technical Standards, all studied bricks presented enough strength for regular construction. Phosphogypsum (PG) for brick manufacturing can be an alternative way for its disposal, which can help mitigate the civil construction environmental impacts.

Porous carbon-coated silicon composites for high performance lithium-ion batterie anode

With the rapid development of silicon-based lithium-ion battery anode, the commercialization process highlights the importance of low-cost and short-flowproduction processes. The porous carbon/silicon composites (C/Si) are prepared by one-step calcination using zinc citrate and nano-silicon as the primary raw materials at a temperature of 950 °C. In this composite, silicon nanoparticles are coated with a porous carbon shell with an average pore diameter of 4.49 nm, which improves the structural stability and electrochemical performance of the anode. Density-functional theory calculations show that the porous carbon enhances the electrical conductivity, facilitates the interlayer migration of Li-ion, and strengthens the gain effect of stress on conductivity. Additionally, stress further reduces the diffusion barriers of Li-ion. The porous C/Si anode demonstrates outstanding specific capacity and rate capability, maintaining a stable specific capacity of 1170 mAh/g at a current density of 0.2 A g−1 after 100 cycles and retaining a reversible specific capacity of 944 mAh/g even at a charging current density of 2 A g−1. The carbon/silicon anode materials prepared using this strategy present a streamlined manufacturing process and exceptional performance, as well as avoiding the post-washing step, providing a pathway toward the scalable application of silicon-based anodes.

Development and Physicochemical Characterization of Edible Chitosan-Casein Hydrogel Membranes for Potential Use in Food Packaging.

The increasing global concern over plastic waste and its environmental impact has led to a growing interest in the development of sustainable packaging alternatives. This study focuses on the innovative use of expired dairy products as a potential resource for producing edible packaging materials. Expired milk and yogurt were selected as the primary raw materials due to their protein and carbohydrate content. The extracted casein was combined with various concentrations of chitosan, glycerol, and squid ink, leading to the studied samples. Chitosan was chosen due to its appealing characteristics, including biodegradability, and film-forming properties, and casein was utilized for its superior barrier and film-forming properties, as well as its biodegradability and non-toxic nature. Glycerol was used to further improve the flexibility of the materials. The prepared hydrogels were characterized using various instrumental methods, and the findings reveal that the expired dairy-based edible packaging materials exhibited promising mechanical properties comparable to conventional plastic packaging and improved barrier properties with zero-oxygen permeability of the hydrogel membranes, indicating that these materials have the potential to effectively protect food products from external factors that could compromise quality and shelf life.

South Cuidrach

A new site in north Skye has revealed evidence of human occupation from the Late Upper Palaeolithic as well as the Early and Late Mesolithic periods, suggesting repeated visits by humans for at least 5,000 years from the Late Glacial Interstadial through the Loch Lomond Readvance and up to the mid-Holocene, a time of dynamic climatic and sea-level change. South Cuidrach is one of several sites in the north of the Isle of Skye and around the Inner Sound with lithic (stone tool) evidence diagnostic of a human presence before the mid-Holocene. These sites currently represent a unique concentration of pre-Late Mesolithic sites in Scotland. The lithic evidence which forms the backbone of the cultural and temporal characterisation of the site at South Cuidrach is outlined here. This includes characteristic points and microliths, burins, cores and other items diagnostic of specific cultural groups. Additionally, it has become evident that Rum bloodstone, a raw material well known from the Late Mesolithic period in the region, may be absent before the Early/Late Mesolithic transition, with baked mudstone from Staffin in North Skye being the primary raw material used before this time. The need for detailed knowledge of the region’s lithic technology and typology is well illustrated here, as small details frequently reflect important chronological differences.

Study on magnesia alumina spinel heat storage ceramics for solar thermal power generation

AbstractSolar thermal storage ceramic materials use photothermal power generation technology to store heat energy, which is an important way to use clean energy and reduce carbon emissions. In this paper, MgAl2O4 ceramics were prepared by pressureless sintering with fused magnesia and α‐Al2O3 as the primary raw materials and TiO2 as the additive. The phase composition, microstructure, physical properties, thermal shock resistance, and thermal physical properties of MgAl2O4 thermal storage ceramics were studied. The results show that the main crystalline phase of B4 is MgAl2O4 and the secondary crystalline phase is MgTi2O5. Ti4+ is dissolved into MgAl2O4 lattice, which distorts the lattice, reduces activation energy, and promotes sintering. The sample B4 (69.73 wt% α‐Al2O3, 30.27 wt% fused magnesia, and 7 wt% TiO2) sintered at 1510°C had the best comprehensive physical properties, and its bending strength and bulk density were 89.41 MPa and 3.27 g/cm3, respectively. After 30 thermal shock cycles, the bending strength of the sample B4 is slightly lost. The thermal stress generated during the expansion and contraction of the grain volume led to the decrease of the bending strength. From room temperature to 1000°C, the specific heat capacity of sample B4 is .44–1.25 J/(g·K). The heat capacity increases with the increase of temperature, and the heat storage density increases. The heat storage density is 1218.75 kJ/kg (1000°C). Heat capacity increases with temperature due to intensified lattice vibration at high temperatures. Therefore, magnesia alumina spinel ceramics show great potential in solar thermal energy storage.