Ash Desulfurization Research Articles

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.

Carbothermal reduction of flue gas desulfurization ash through the utilization of waste heat from steel slag: Investigating performance and mechanism

Flue gas desulfurization ash is a significant solid waste generated by the steel industry, leading to environmental pollution. In response to this challenge, this study proposes a novel method for preparing CaS from desulfurized ash through carbothermal reduction using steel slag waste heat. Thermodynamic analysis using FactSage and non-isothermal thermogravimetric testing were conducted to confirm the feasibility of carbothermal reduction. The experiment successfully prepared CaS, with a molar ratio of C to CaSO3 of 1.5 or higher leading to complete reduction. The presence of reducing agent C replaced the decomposition reaction of CaSO3 with reduction, occurring at a temperature 60 K lower. Large scale thermogravimetric analysis experiments demonstrated that as the mass percentage of pulverized coal increased, the reduction reaction of CaSO3 shifted to a lower temperature zone, expanding the temperature range and achieving the theoretical value. Reduction rates of CaSO3 were 43.12 %, 76.9 %, and 99.3 % with ratios of CaSO3 to reducing agent C of 1:0.75, 1:1.5, and 1:3, respectively. Kinetic study results showed that the activation energy of CaSO3 reduction ranged from 90.669 kJ/mol to 136.059 kJ/mol within the conversion rate range of 0.2 to 0.9. When CaSO3 and carbon powder are mixed and subsequently added, the thermochemical decomposition reaction of CaSO3 is inhibited. This inhibition leads to the formation of stable CaS through the reduction of desulfurization ash by carbon.

A novel and clean utilization of flue gas desulfurization ash coupled with converter sludge to produce calcium ferrate

To address the environmental pollution from industrial wastes like desulfurization ash (DA) and converter sludge(CS), this study introduces a novel method for synthesizing calcium ferrate. This method involves reacting converter sludge with desulfurization ash at high temperatures, facilitating the concurrent elimination of toxic elements. The solid byproduct is suitable as a sintered ore additive, while the gaseous SO2 serves as a precursor for sulfuric acid production. Additionally, the metal-rich secondary dust offers a source for valuable metal recovery. This research employs simulation software (FactSage 8.1) and thermal analysis to explore the high-temperature reaction dynamics of converter sludge and desulfurization ash. Subsequent in-situ experiments and coupled high-temperature tube furnace-infrared flue gas analysis further elucidated the phase transitions, morphology changes, flue gas emissions, and migration of harmful elements (e.g., S, K, Na, Pb, Zn). Analysis using the Predom dominant zone module calculation indicates that low SO2 concentration and reduced oxygen levels promote the stability of Ca2Fe2O5. Infrared flue gas analysis reveals high concentrations of CO2 and SO2. Sulfur removal rates rose from 62.15 % to 98.48 % between 800 °C and 1100 °C. Removal efficiencies for alkali and heavy metals, namely K, Na, Pb, and Zn, improved significantly, reaching 99.95 %, 99.49 %, 99.71 %, and 86.7 % respectively. At 1100 °C under an N2 atmosphere, the main reaction products from Flue Gas desulfurization ash (FGDA) and converter sludge were CaFe3O5 and Ca2Fe2O5. This study’s comprehensive analysis of synthesizing calcium ferrate from Flue Gas desulfurization ash and converter sludge introduces a novel waste utilization method, offering substantial environmental and economic advantages.

Study on the micro-rheological properties of fly ash-based cement mortar

Aiming at the shortcomings of poor rheological properties and low strength of tailings filling mortar, solid waste materials such as fly ash, steel slag, and desulfurization ash were introduced to improve the filling mortar. The Response Surface Methodology (RSM) was used to design the test ratios to determine the significance of the effect of fly ash, steel slag and desulphurization ash on the physical properties of the mortar. The rheological characterization law of filling mortar was studied based on macroscopic L-tube test. The mechanism of filling mortar improvement was analyzed by Scanning Electron Microscopy (SEM), and Energy-Dispersive X-ray Spectroscopy (EDS) and other microscopic tests. The results show that the response-factor model fit regression is significant, with the highest model satisfaction at 12 % fly ash dosing, 15 % steel slag dosing, and 10 % desulfurization ash dosing. The self-flowing extension diameter of the mortar is 15.34 cm, and the 3d and 28d strengths are 0.58 MPa and 3.24 MPa, respectively. Fly ash has effectively improved the phenomenon of mortar segregation and precipitation, and the yield stress of mortar is reduced by 35.1∼64.9 % when the dosage is 8∼12 %. The fractal dimension and mortar workability are positively correlated with fly ash admixture. Fly ash incorporation will gradually consume the calcium hydroxide (CH) to generate alumina ferrite (Aft) and calcium silicate hydrate (C-S-H), which reduces mortar porosity and promotes long-term strength growth. The research results not only realized the effective utilization of solid waste resources, but also significantly improved the performance of the filler and ensured the safe production of the mine.

Study on the basic properties of iron tailings powder-desulfurization ash mine filling cementitious material

Abstract To realize the recycling of iron tailings powder (IP) and desulfurization ash (DA) and reduce the high preparation cost of mine filling cementitious materials (MCs), this article adopts sodium carbonate (SC) as an activator to prepare iron tailings powder-desulfurization ash mine filling cementitious materials (IDMC). The effects of IP content, DA content, SC content, and mirabilite content on the mechanical properties and setting time are experimentally investigated. The micromorphology and phase compositions of the hydration products of IDMC are analyzed and characterized by scanning electron microscopy and X-ray diffraction. The results show that the initial setting time of the IDMC is reduced by 0.87 and 21.83% when the mirabilite content is increased from 0 to 1% and 2%, respectively, and the compressive and flexural strengths of the IDMC are increased by 24.01 and 86.25% when the IP content is increased from 0 to 20%, respectively. The IP not only participates in the hydration reaction but also plays an aggregate filling effect, significantly improving the mechanical properties of the IDMC. The pozzolanic effect is gradually enhanced with the increase of the DA content, and the hydration degree of the IDMC increases. The SC as an activator can moderately reduce the shrinkage rate of the IDMC. Based on the multi-index optimization analysis, the optimal mix proportion of the IDMC is obtained, which provides an effective reference for the preparation of the novel MC.

Environmental sustainability of closed-loop regeneration of NaHCO3 in CO2 utilization-driven desulfurization ash: From the perspective of integrated hybrid life cycle assessment

The closed-loop regeneration of NaHCO3 by treating sodium-based desulfurization ash (SDA) using CO2 in flue gas and ammonia by-products demonstrates an attractive perspective of low-cost sodium-based dry desulfurization (SDD) application. To push generation reuse of desulfurization ash into more practices, taking the application in coking plants as a case, this study first compares the environmental and economic performance of four scenarios of flue gas desulfurization (FGD) and desulfurization ash disposal by integrated hybrid life cycle assessment (IHLCA) with life cycle costing. Compared with process-based LCA, IHLCA captures more environmental impacts through the economic input-output (EIO) system, especially 36.40–67.89% of terrestrial ecotoxicity comes from the EIO system. Based on evaluation results of four scenarios, among the ten environmental impact categories (excluding photochemical oxidation), the SDD scenario with NaHCO3 regeneration by CO2 and ammonia (S2) is not only the most environmentally friendly route, but also has the lowest total hourly operating cost. These are mainly due to the offsetting effect of by-products replacing traditional chemicals on the total impact and avoiding landfill and raw material transportation. Furthermore, sensitivity analysis also shows that when technical parameters change, the environmental and economic performance of S2 still remains the best, except for the case when the NaHCO3 regeneration rate is 60%. The findings will be valuable for the selection and optimization of FGD in coking plants, incineration plants, and others.

Fe/Mn-MOFs with monocarboxylic acid-induced defects enhances the catalytic oxidation of calcium sulfite in desulfurization ash

The application of catalysis is an effective way to enhance calcium sulfite oxidation reactions, which is essential to the calcium-based wet flue gas desulfurization and the handle and/or utilization of the solid by-product from semi-dry desulfurization process, i.e., desulfurization ash. In this report, we present a method for constructing Fe/Mn(BDC)(DMF,OA) bimetallic catalysts with defect engineering by using monocarboxylic acids with varying chain lengths as regulators. After removing the monocarboxylic acid, the unsaturated coordinated iron and manganese active sites in Fe/Mn(BDC)(DMF,OA) become more abundant. This makes it easier to adsorb O2 and activate it into reactive oxygen species (O2–), which in turn activates the radical chain reaction and promotes the production of sulfur-oxygen free radicals(SO5−). Density functional theory (DFT) calculations show that the synergistic effect of Fe-Mn bimetallic catalysts reduces the energy barrier for SO42− formation, thereby accelerating the oxidation of sulfite. Upon addition of Fe/Mn(BDC)(DMF,OA), the oxidation rate of calcium sulfite within 3 h increased from 2.76 % to 96.09 %, compared to non-catalytic oxidation. After five cycles, the 3 h oxidation rate of calcium sulfite decreased by 10.42 % compared to the first cycle, and the higher leaching rate of Mn element was the main reason for the decrease in catalytic performance. The catalyst is non-toxic and economical, showing significant potential for resource utilization of CaSO3-containing desulfurization ash.

Efficient calcium sulfite oxidation treatment by a highly active iron-manganese bimetallic metal-organic frameworks (MOFs)

Calcium sulfite (CaSO3) oxidation is the key step in the resource utilization of flue gas desulfurization (FGD) ash waste. However, under natural conditions the oxidation rate of CaSO3 is very low, limiting its conversion into calcium sulfate, an acceptable product for construction material. This study was devoted to the investigation of the synthesis and performance of a bimetallic MOFs with potential catalytic activity, namely, Fe/Mn(BDC)(DMF,F) catalysts. A combination of techniques including SEM, EDS, XRD, FT-IR, etc. were used to characterize the catalysts. The excellent catalytic performance examined in a gas-liquid-solid three-phase oxidation system are due to the special flexible respiratory architecture and homogeneous distribution of active sites, which allows the reactants to fully contact with the catalyst. Mn incorporated in the backbone of the metal-organic framework significantly enriches the catalytic active species that participate in a radical chain reaction with activated SO32- as ·SO3-, which in turn generates the key radical ·SO5- that reacts with SO32- to form SO42-. In the presence of Fe/Mn(BDC)(DMF, F)-13, the oxidation ratio of CaSO3 could reach 90.71%, which is more than 30-fold compared to non-catalytic oxidation and almost 5 times the effects of the single metal Fe(BDC)(DMF, F) catalyst. In addition, the study of kinetics shows that the oxidation rate of Fe/Mn(BDC)(DMF,F)-13 can reach 0.042 mmol·L-1·s-1 with an apparent activation energy of 10.86 kJ/mol. The oxidation rate is mainly affected by reaction temperature, pH value, catalyst concentration, and air flow rate. This study provides a potentially sustainable way for utilization of CaSO3-containing desulfurization ash.

Oxidation Study and Mechanism Analysis of Desulfurization Ash in Dense-Phase Tower

Dense-phase-tower desulfurization technology is an emerging semi-dry flue-gas desulfurization ash process, i.e., the flue gas is allowed to enter the desulfurization tower from the bottom up and, at the same time, is sprayed with a desulfurizing agent that undergoes an acid–base reaction with the flue gas in the ascent process. The calcium sulfite and calcium sulfate produced by the reaction and the part of the desulfurization agent that is not involved in the reaction will enter the subsequent dust removal system, and what is retained is the by-product desulfurization ash. This desulfurization ash contains a large amount of calcium sulfite, which leads to its unstable nature; it is easily oxidized and expands in volume, and, if used in the field of building materials, it will lead to cracking and other problems, so it is difficult to effectively use it. In order to solve this problem, XRF, XRD, and iodometric and other analytical methods were used to determine the specific composition of desulfurization ash, and the muffle furnace and vertical tube furnace were used to study the thermal oxidative modification of calcium sulfite in desulfurization ash, to investigate the effects of the oxygen content, reaction temperature, medium flow rate, and chloride content on the oxidation of calcium sulfite, and to analyze the thermodynamics in the high-temperature oxidation reaction. The results showed that the oxidation rate of calcium sulfite increased with higher reaction temperatures. Increased oxygen content promoted the oxidation rate, particularly at low oxygen levels. The oxidation rate of calcium sulfite correlated positively with the medium flow rate until a rate of 75 mL·min− was reached. At a reaction temperature of 420 °C and a gas flow rate of 85 mL·min−1, the oxidation conversion efficiency exceeded 89%. Chloride content significantly reduced the oxidation rate of calcium sulfite, although this inhibition weakened at temperatures above 500 °C. Kinetic analysis suggested that the oxidation reaction of calcium sulfite predominantly occurred below 500 °C. These findings have both theoretical and practical implications for the thermal oxidation treatment and disposal of desulfurization ash.

Feasibility Analysis of Resource Application of Dry Flue Gas Desulfurization Ash in Asphalt Pavement Materials

To verify the feasibility of applying dry flue gas desulfurization ash (DFGDA) to asphalt pavement materials, the asphalt mastic (filler and asphalt composition) prepared by adding different proportions of DFGDA and LSP (limestone powder) into 70# matrix asphalt was studied experimentally. The asphalt mastics were subjected to the penetration test, the softening point test, and the ductility test. Moreover, the rheological properties of asphalt mastic were evaluated with dynamic shear rheometer (DSR) tests and bending beam rheometer (BBR) tests. An interaction ability index C-value based on the Palierne model was proposed to evaluate the interaction ability between DFGDA and asphalt. The influence of DFGDA asphalt on the interaction ability of matrix asphalt was observed and evaluated using Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The results showed that with the increasing proportion of DFGDA, the penetration of asphalt mastic gradually decreased, the softening point increased, and the ductility slightly decreased. At the same temperature, the dynamic shear modulus G* of the asphalt mortar significantly increased with increasing DFGDA content. The incorporation of DFGDA negatively affected the low-temperature plastic deformation resistance of asphalt, but the impact was weakened with the growing DFGDA amount and the powder mastic ratio. The combination mode of DFGDA and matrix asphalt depends on the physical blending, and their interaction ability mainly depends on the miscibility between DFGDA and matrix asphalt. In conclusion, DFGDA can be utilized as a novel filler in asphalt pavement materials.

Data-driven analysis of product interactions during biomass pyrolysis

Pyrolysis technology, crucial for sustainable energy in light of the energy crisis and environmental concerns, was studied using a model compound method involving desulfurization ash with cotton straw and a model compound. This study focused on the catalytic effects of desulfurization ash on the pyrolysis product formation from cotton straw. Key findings include a negative correlation between tar yield and the yields of carbon, water, and syngas, but a positive correlation with other pyrolysis products. Specifically, in the DFA/CE combination, tar and carbon yields were positively correlated, but negatively correlated with syngas and water yields. In DFA/LG, however, tar yield negatively correlated with water and carbon yields. Analysis using visual charts indicated that the H2 yield in DA/CS significantly fluctuated and positively correlated with the mixing ratio. In DFA/CE, a negative correlation existed between H2 yield and the combination ratio. For DFA/LG, the trends of CO and CH4 were consistent with C2H6 and H2, with a stable C2H6 rate and CO positively correlating with CO2. The Lilliefors test, ANOVA, and Spearman's correlation coefficient revealed no significant difference in the yields of pyrolysis products and gases between CE and LG under the same desulfurization ash proportions.

Fabrication of Silane and Desulfurization Ash Composite Modified Polyurethane and Its Interfacial Binding Mechanism

Fabrication of Silane and Desulfurization Ash Composite Modified Polyurethane and Its Interfacial Binding Mechanism

Preparation and properties of high blending phosphogypsum-desulfurization ash-waste soil based functional prefabricated autoclaved aerated concrete slabs

There is a huge stock of industrial solid waste piles such as phosphogypsum (PG), desulfurization ash (DA), and waste soil (WS) in China, and their utilization rate is insufficient. These have potential risk for environmental safety due to pollutants contained in them. In this study, after proportioning design, raw material pretreatment, bubble regulation and multi-temperature section maintenance process, successfully prepared a high blending solid waste based functional prefabricated autoclaved aerated concrete slabs (FPAS) with excellent functional performance, and the optimal ratio of each raw material is PG: WS: DA: cement: lime = 8:50:20:10:12, and the dry mass ratio is up to 75%, the compressive strength of the slabs is up to 5.2 MPa, the standard dry density is 606 kg/m3, the dry shrinkage value is 0.36 mm/m, and the post-freezing strength is 4.0 MPa, which is in line with the basic requirements in the standard “Autoclaved aerated concrete slabs” (GB/T15762), and at the same time, its fire-resistant integrity is qualified for 240 min, and the coefficient of thermal conductivity is 0.15w(m.k), airborne sound-weighted sound insulation is 46 dB, also can show different functional characteristics. In order to investigate the environmental safety of heavy metals (HMs) in the slabs, the simulation experiment of HMs leaching from outdoor stacking of slabs was carried out. The results show that the HMs in the slabs do not pose obvious risks to the natural environment and human body, but three of the characteristic HMs, Cr, Cd and Hg, have significant leaching patterns, which can be expressed by a second-order kinetic model. Finally, the life cycle assessment and cost analysis of the high blending PG-DA-WS based FPAS and the conventional aerated slabs were carried out. The main environmental damage category of the high blending PG-DA-WS based FPAS is land ecological risk, and it has obvious environmental and economic benefits compared with the conventional aerated slabs.

Removing residual chlorine in water using carbon-based material derived from co-pyrolysis of cotton stalk and desulfurized ash

Herein, an environmentally friendly and low-caste absorbent has been studied to perform with high efficiency and fast removal rate of residual chlorine from wastewater. The chlorine removal absorbent was prepared in situ by co-pyrolysis of desulfurization ash (DA) and cotton stalk (CS) in a tube furnace at 600℃. Compared with CS pyrolysis alone, DA promoted the CS decomposition during co-pyrolysis of DA/CS. The maximum yield of pyrolysis gas was 188 mL/g with 11.33 MJ/Nm3, occurred in the DA/CS blending ratio of 50/100. Moreover, DA also catalyzed the well-developed micropore and mesoporous of cotton-stalk base carbon loaded with DA (CBCDA). The CBCDA with 38.62 wt% DA content had a pore volume of 0.0165 m3/g and a maximum specific surface area of 6.890 m²/g, which 1.96-fold and 1.50-fold higher than that of cotton-stalk base carbon, respectively. The further analysis of adsorption revealed that CaSO3 scattered on the surface of CBCDA fast and efficiently converted hypochlorite ion into chloride ion. The absorbent purified 90.02% residual chlorine from 12 mg/L wastewater within 30 min. Therefore, CBCDA absorbent offers a promising approach for fast and highly efficient purification of residual chlorine in wastewater.

Resource utilization of semi-dry flue gas desulfurization ash by thermal treatment on sintering machine

Semi-dry flue gas desulfurization ash (SFGDA) is an abandoned Ca and S resource that is currently stacked without appropriate disposal methods. A technology with industrialization potential, SFGDA, and iron ore thermal processing is an effective approach to obtaining calcium ferrite and industrial sulfuric acid. This study investigated the thermochemical reaction mechanism of SFGDA during high-efficiency pyrolysis employing Fe2O3 and coke powder for self-heating. The results showed that the addition of coke powder enhanced the thermal efficiency and reduced the decomposition temperature, while the reaction is accelerated by the lightning-fast combination of Fe2O3 with the CaO produced during pyrolysis to generate calcium ferrite products. The optimal conditions were determined to be a coke powder dosage of 10% and Fe2O3 dosage of 50%. In semi-industrial experiments, the SFGDA achieved a desulfurization rate of 99% and a calcium ferrite content of 85%. The calcined product CaO from CaSO4 and CaSO3 in the form of calcium ferrite products, with a minimal amount of CaSO4. In addition, during the high-temperature calcination process performed by the sintering machine, the majority of the sulfur within the raw materials migrates as SO2 and is subsequently emitted into the flue gas. Following, this SO2 is captured and utilized for the production of commercially valuable sulfuric acid. When the yield of enabled to calcined product corresponds to 1 ton, it could potentially dispose of 882 kg of SFGDA, culminating in a high-value, harmless, and large-scale SFGDA treatment in steel industry.

Large-scale application of coal gasification slag in nonburnt bricks: Hydration characteristics and mechanism analysis

Coal gasification slag (CGS) is a typical solid waste from the coal gasification process. Reusing CGS into building materials is a key means of realizing its large-scale utilization. This study aims to utilize CGS at a large dosage for the preparation of nonburnt bricks. The CGS, red mud, fly ash and desulfurization ash were utilized to synergistically prepare nonburnt bricks. The mechanical, durability and environmental performance of nonburnt bricks were analysed. Moreover, XRD, thermogravimetric analysis, FTIR, MIP and SEM were conducted to analyse the hydration products and microscopic morphology. The results revealed that when the CGS dosage reached 60%, the best performance of prepared nonburnt bricks was achieved. The unconfined compressive strength was 8.3 MPa at 3 d, 18.2 MPa at 7 d and 24.0 MPa at 28 d. Undergoing 25 cycles of freeze-thaw, the mass loss ratio was 0.9% and strength loss ratio was 10.67%. The alkaline solid wastes (red mud) have a promoting effect on the dissolution of active components in CGS, and the calcium content in blast furnace slag and desulfurization ash, as well as the sulfate in desulfurization ash, can enhance the formation of hydration products. The microstructures displayed the formed clustered C-S-H gels and reticulated C(N)-A-S-H gels tightly wrapped unreacted particles and filled the interstitial spaces of the materials, causing to an elevation in the compactness and a decline in the number of harmful pores. In addition, heavy metals (Cr, As, Cd and Pb) in CGS were well solidified. This study provides a rationale for the harmless and resourceful utilization of CGS.

The production of artificial aggregates with flue gas desulfurization ash: Development of a novel carbonation route

Using solid waste to absorb CO2 in the production of aggregates is an efficient approach, which can reduce CO2 emissions and improve the recycling of solid waste. However, a challenge lies in addressing the cracking issues of aggregates prepared by the calcium oxide (CaO) system, particularly those containing flue gas desulfurizati ash (FGDA), during the direct carbonation process. This study presents a novel carbonation route combining air curing (AC) and CO2 curing (CC) under industrial flue gas conditions that effectively resolves the cracking problem of FGDA. The results show that under the optimized conditions (6 % CaO, 2 % Na2SO4, 3 days of AC, and 12 h of CC), the FGDA can be used to produce the flue gas desulfurization ash artificial aggregate (FGDAA), with pellet strength and water absorption of 3.11 MPa and 16.87 %, respectively. The CaCO3 forms during the carbonation, which improves pellet strength and decreases water absorption, except for the high CaO content (8 %) or AC age over 3 days. This shows that this method has clear requirements for the CaO content in solid waste. By developing a low-cost and energy-efficient carbonation process, FGDAA offers significant advantages in the construction field. With a production cost of only $5.14 per ton and a shorter curing time, it is environmentally sustainable and has a low global warming potential of 52.68 kg CO2-Eq. Although its compressive strength of 32.52 MPa is slightly lower than some conventional aggregates, FGDAA is still suited for applications such as road construction and mine backfill.

Effect of dry desulfurization ash as a filler on asphalt pavement performance

This study aims to explore the feasibility of using dry flue gas desulphurization ash (DFGDA) as a filler in asphalt pavements. Two DFGDA materials were added into the base asphalt with different mineral powder proportions to prepare asphalt mastic and mixture, and the pure mineral powder asphalt mastic and mixture were used as the blank control group to evaluate the properties of DFGDA-doped asphalt mastic and mixture. The results show that the addition of DFGDA can improve the high-temperature rheological property and reduce the low-temperature rheological property of asphalt mastic; similarly, the high-temperature stability of asphalt mixture can be greatly improved, while its low-temperature performance and water stability are reduced; despite these decreases, all outcomes still meet the requirements of relevant specifications. No chemical reactions are observed between DFGDA and asphalt, indicating that the physicochemical properties of fillers are responsible for the change in the properties of DFGDA-doped slurry and mixture. Notably, the DFGDA-added asphalt mixture does not bring additional negative effects to the environment. Based on cost analysis, the high-quality use of DFGDA in asphalt mixture can save direct material costs of about $920,000 per 100 kilometers of asphalt road construction. In summary, the application of DFGDA in the asphalt mixture can not only meet the basic performance requirements of asphalt pavements but also greatly save material costs and protect the environment.

Life-cycle assessment of sustainable pavement based on the coordinated application of recycled asphalt pavement and solid waste: Environment and economy

To achieve efficient use of recycled asphalt pavement (RAP) produced during the maintenance and expansion of old roads and to solve the problem of low utilization of steel slag and desulfurization ash generated in the production process of the steel industry, this study designed a sustainable pavement using RAP and waste rubber powder-modified asphalt to form a matrix skeleton with large voids and injects grouting materials prepared with desulfurization ash and steel slag. It was found that the designed sustainable pavement has excellent high-temperature permanent deformation resistance and durability. Compared to traditional asphalt pavement, sustainable pavement's energy consumption and emissions can be reduced by about 45% within a single life cycle, while the economic benefits exceed about 500%. Moreover, sustainable pavement's excellent fatigue resistance will make its energy-saving, emission-reduction effects, and economic benefits more significant than traditional asphalt pavement during the same analysis period.

Mechanical enhancement of epoxidized natural rubber by flue gas desulfurization ash as the sole reinforcing filler

AbstractFlue gas desulfurization facilities produce flue gas desulfurization ash (FGDA), which has ecological and economic benefits. In this article, we explored the possibility and impact of using FGDA as the sole reinforcing filler to mechanically improve epoxidized natural rubber (ENR). The influence on the properties of the composites was examined. FGDA exhibits good interfacial interaction and compatibility with ENR, which improves the mechanical properties of ENR. When 15 phr FGDA was added, the tensile strength of the composites increased by approximately 41.4% compared with that of pure ENR. This work demonstrates the possibility of using FGDA as an effective and sole reinforcing material to enhance the properties of rubber materials.Highlights FGDA improves the mechanical properties of ENR as a sole reinforcing filler. FGDA reacts with ENR during vulcanization, enhancing compatibility. Adding 15 phr FGDA to ENR increases the tensile strength by 41.4%.