Ash Sintering Behavior Research Articles

In-situ analysis of the sintering behavior of coal ash and a phosphorus-rich biomass ash under gasification condition

The relatively high contents of some ash-forming elements (Na, K, Ca, Mg, P) in biomass ash can cause serious ash-related problems (deposition, slagging, corrosion, etc.) during the co-gasification of coal and biomass, influencing the stable operation of gasifier. The sintering behavior of Jincheng coal ash (JCA) and a phosphorus-rich Jatropha seed cake ash (JSCA) were investigated by in-situ heating stage microscopy, while the sintering mechanism was revealed by phase studies employing X-ray powder diffraction and thermodynamic modelling. Results indicated that the sintering temperature of blended ashes reached the minimum at the 20 wt% blending ratio of JSCA in the coal-biomass ash mixture. The high sintering temperatures of JCA and JSCA were due to the extensive mullite and quartz crystallization in the high acidic JCA system and the widespread formation of K–Ca phosphate and K–Mg phosphate in the high basic JSCA system, respectively. The transition of the phosphorus from fluxing effect to refractory effect on the sintering of ash mixture was identified at the 20 wt% blending ratio of JSCA. It was also found that the role of mullite and quartz decreased, while the role of anorthite, gehlenite, leucite, and calcium phosphate increased with increasing JSCA content, leading to the lowest sintering temperature. Finally, the variation trend of sintering temperatures against the JSCA additions was in accord with the change of the liquidus temperatures that was calculated by thermodynamic modelling. These observations can be used for the potential prediction of the ash sintering temperature in the coal-biomass gasifier.

The sintering analysis of biomass waste ash based on the in-situ exploration and thermal chemical calculation in the gasification process

The plentiful biomass wastes are promising fossil energy alternatives to generate indispensable energy. Biomass gasification is an effective way of producing high-value-added productions and reducing CO2 emissions. However, some ash-related issues, especially ash sintering, restrict the wide utilization of biomass energies. To minimize the negative effect of the sintering problem, this work studied the ash sintering process of typical cornstalk waste ash by in-situ experimental methods, including high-temperature stage microscope (HTSM) and thermomechanical analysis (TMA). Then the thermochemical calculation was combined to clarify the sintering mechanism. The result indicated that sintering was the first step during the ash fusion process. The initial sintering temperature (624 °C) was lower than the ash deformation temperature (919 °C), which was the first characteristic temperature of ash fusion tests. The chemical reaction of the inherent ash-related components was the main reason for the appearance of the initial sintering temperature. From the element perspective, the chemical reaction of alkali and alkali earth metals (AAEMs) was mainly involved. The alkali metals tended to react with SiO2 while alkali earth metals were prone to combine with P2O5. Except for ash sintering behavior during the heating process, the TMA trace showed another two stages, swelling and melting. Massive bubbles would be generated from the inside melts at the swelling stage and cause the drastic fluctuation of the ash-melting system until the end of the melting range. Moreover, the high heating rate was beneficial for alleviating the initial sintering temperature while having a tiny influence on changing the total range of sintering and swelling zones.

Progress in physicochemical properties of ash/slag from co-gasification of agroforestry waste biomass and coal

Co-gasification of agroforestry waste biomass and coal realizes energy-saving, low-carbon emission, clean and efficient raw material conversion by taking advantage of their similarities and complementarities. The physicochemical properties of ash slag for raw materials are one of the key factors affecting the stable operation of co-gasification. It is the focus of co-gasification research. This paper reviews the research status of physicochemical properties of ash slag from co-gasification of agroforestry waste biomass and coal. It mainly includes the similarity and difference between agroforestry waste biomass ash and coal ash, the fusion and viscosity-temperature characteristics of mixed ash, the effect of alkali/alkaline earth metals in mixed ash on co-gasification reactivity, and sintering behavior during the slagging process. The influence mechanism of adding agroforestry waste biomass on the melting flow and sintering behavior of mixed ash is discussed. The prediction models and methods of fusion characteristics, viscosity-temperature, and slagging characteristics of mixed ash are also summarized. Finally, the future research directions of ash slag from co-gasification of agroforestry waste biomass and coal are proposed.

Effect of phosphorus-based additives on the sintering characteristics of cornstalk ash

Combustion of agricultural residues for heat and electricity production is an efficient way to reduce amount of such waste source and emissions due to inappropriate treatment of them. However, unlike other biomass materials, agricultural residues often have high content of ash and certain ash forming elements with low meting temperatures, resulting in sintering and slagging during combustion processes. It complicates combustion of agricultural residues and restricts further utilization of this renewable energy source. In this work, sintering of a typical agricultural biomass cornstalk and effect of two phosphate additives, Ca(H2PO4)2·H2O and NH4H2PO4, were investigated by a combination of various techniques. Results indicated that the addition of Ca(H2PO4)2·H2O increased the initial melting temperature of cornstalk ash by 64–209 °C. The ash sintering behavior was greatly improved as a result of formation of high melting temperature K–Ca phosphates, Ca9MgK(PO4)7 and Ca2KP3O10 upon addition of the Ca(H2PO4)2·H2O. It is accompanied with reduced generation of low melting temperature K-rich silicates and the formation of large ash aggregates. Addition of NH4H2PO4 increased the initial ash melting temperature by 28–116 °C, but it had slight influence on the cornstalk ash sintering characteristics. The analysis revealed that, although the addition of NH4H2PO4 resulted in the formation of high melting temperature K2CaP2O7, certain amount of K phosphates and silicates eutectics were still formed, initiating and promoting sintering of ash from mixture of cornstalk and NH4H2PO4. Reactions between Ca(H2PO4)2·H2O and potassium salts under different conditions were also studied. It was found that reactions between Ca(H2PO4)2·H2O and potassium salts might already start as the temperature higher than 300 °C. K2CaP2O7, Ca2P2O7, Ca(PO3)2 and KCa(PO3)3 were identified as main products from these reactions and amounts of them considerably depends on the heat treatment temperatures and mixing ratios between Ca(H2PO4)2·H2O and potassium salts. Compared to KCl, K2CO3 had a higher reactivity toward the Ca(H2PO4)2·H2O under same study conditions. The current work shows the addition of Ca(H2PO4)2·H2O is a promising approach to alleviate the ash sintering issues and assure efficient and smooth combustion of cornstalk.

Low-temperature sintering behavior of fly ash from hazardous waste incinerator: Effect of temperature and oxygen on ash properties

Hazardous waste incineration fly ash (HFA) is high risk for the environment due to heavy metals leaching and other pollutants. Sintering treatment potentially reduces the mass and volume of HFA and immobilizes heavy metals in ceramic-like bodies. However, HFA contains a large amount of heavy metals, thus sintering at too high a temperature will lead to the volatilization of heavy metals. The low-temperature sintering behavior of HFA at different temperature (450 °C, 670 °C and 900 °C) and different atmospheres (21% O2, 47.3% O2, 60.5% O2 and 100% O2) was investigated in this study. The mass loss, morphology, bulk density, elemental composition, heavy metal leaching rate, and mineral phase transformation of sintered ash were experimentally tested. With increasing sintering temperature, more mass of HFA was lost and the leaching rate of heavy metals decreased. For instance, sintered at 450 °C, 670 °C and 900 °C under air, the mass losses were 4.30%, 6.58%, and 17.96%, the leaching rate of Pb were 19.37%, 2.74%, and 0.65%, respectively. Sintered ash became denser and formed ceramic-like particle due to thermal agglomeration and chemical reactions. The bulk density significantly increased, which was favorable to reduce space occupancy for fly ash landfill. Oxygen-rich atmosphere could make the fly ash denser and inhibit the volatilization and leaching of Pb. The obtained findings are beneficial for deep understanding of the sintering behavior of HFA at low-temperature.

In-situ analysis of the effect of CaO/Fe2O3 addition on ash melting and sintering behavior for slagging-type applications

Slagging-type technologies, particularly entrained-flow gasification, have been quickly developed and industrialized due to their inherent advantages. The ashes of many feedstocks are rich in SiO2 and Al2O3. Therefore, a high operating temperature is required, making the process less efficient. The use of pure additives such as limestone does not meet the requirements. In consequence, binary additives of CaO/Fe2O3 are studied to improve the fusibility. The CaO/Fe2O3 ratio is varied in order to optimize cost efficiency and the operation and control of processes. Ash fusion temperatures (AFTs) and X-ray diffraction (XRD) combined with in-situ methods of thermomechanical analysis (TMA) and high-temperature scanning electron microscopy (HT-SEM) are used to explore the effect of CaO/Fe2O3 on ash fusibility. The CaO/Fe2O3 ratio affects the ash fusion behavior due to changes in the mineral phase composition. The AFTs reveal an optimum combination for the joint addition of CaO and Fe2O3 compared to blends with the same amount of one single additive, while sintering is less strongly affected. Based on the in-situ analyses, the blends of ash and additive are categorized into two or three regimes of sintering, swelling, and fusion in the high temperature range. Depending on the applied additive ratio, different regimes of ash fusion are detected, which affect the slag properties.

Influence of Fly Ash Properties on Characteristics of Manufactured Angular Fly Ash Aggregates

This paper presents the influence of fly ash properties on angular fly ash aggregate (AFAA) and its manufacturing process to be used as a replacement of natural aggregate in concrete. Characteristics of fly ash play an important role in quality of AFAA as fly ash is the major constituent of the raw materials that are used in manufacturing of AFAA. Ample of studies have already been done on production and utilization of round fly ash aggregate (FAA) by pelletization process, but this study deals with innovative work of manufacturing of AFAA by crushing sintered briquettes into required sizes. Unlike round fly ash aggregate, AFAA possesses rough surface that enhance interlocking of these aggregate with paste in concrete. Four different types of AFAA were manufactured in laboratory by using two different samples of fly ash and two different binders. Performance of AFAA showed that specific surface area and chemical composition of fly ash affects sintering behavior of ash and as a result internal microstructure of aggregate also gets affected. Later, eight types of concrete were produced using four types of manufactured FAA at two different water cement ratio 0.45 and 0.50. It was concluded that strength of concrete depends on properties of manufactured AFAA and nature of bond between cement and aggregate at Interfacial transition zone. AFAA used concrete is found to be lighter in weight compared to the concrete of natural aggregate and is economical for use in construction purposes which in turn can save our depleting natural resources and environmental pollution.

Multilateral approaches for investigation of particle stickiness of coal ash at low temperature fouling conditions

Particle stickiness is a key parameter for increasing ash deposition in gasification process. We conducted multilateral investigations to evaluate particle stickiness of coal ash at low temperature fouling conditions through Watt and Fereday’s viscosity model, dilatometry (DIL) and laser flash apparatus (LFA) technique. Seventeen coals were employed for ash deposition experiments under gasification condition through drop tube furnace (DTF). The low viscosity not only led to increasing ash deposition behavior, but also increasing the particle size of deposited ash. From DIL analysis, the ash sintering behavior increased with increasing temperature due to increase of particle stickiness. The high amount of Fe2O3, CaO and MgO components resulted in low sintering temperature and high reduction of physical length. Through LFA analysis, the thermal conductivity increased with increasing temperature, because of increasing particle stickiness. In addition, its value was correlated with the propensity of common fouling indices.

An experimental study on the effects of adding biomass ashes on ash sintering behavior of Zhundong coal

This study investigated the effects of adding biomass ashes on the sintering behavior of ash from Zhundong coal (ZD) in a horizontal-chamber furnace. The ashes were prepared from corn stalk pellets (CS), rice hull (RH), and wood pellets (WP). The operating temperature was set as 1 573K. A charge-coupled device (CCD) camera was used for online evaluation of the morphological changes of ash samples during the sintering process. A range of analytical techniques were applied to the sintered ash samples including scanning electron microscopy (SEM), energy-dispersive X-ray spectrometry (EDX), and X-ray diffraction (XRD). Base-to-acid ratio analysis and chemical equilibrium calculation were conducted to reveal the influence of adding biomass ashes on the fusion characteristics of ZD ash. Results showed that CS and RH ashes promoted sintering behavior of the ZD coal ash, whereas, WP ash inhibited it. The smallest shrinkage in height of the ash block is 0.55 for the RH 10% blend, and the smallest area is 0.45 for the CS 10% blend. Higher blend ratio reduced the positive effects on sintering behavior of ash blends. XRD analysis revealed the interaction between coal and biomass ashes, and showed that alkalimetals and calcium play significant roles during the sintering process. Base-to-acid ratio analysis and chemical equilibrium calculation agreed with the experimental results.

Sintering Characteristic in Catalytic Gasification of China Inner Mongolia Bituminous Coal Ash

To determine the ash characteristics, catalysts transformation and the sintering mechanism during catalytic coal gasification, the investigation of the effect of ashing temperature, K2CO3 and CaO catalysts addition on the ash sintering behavior of bituminous coal was conducted under catalytic gasification conditions. The ash sintering temperature was determined at 3.5 MPa using a pressure-drop sintering device with H2O, H2, CO inlets. The ash morphology was analyzed using a scanning electron microscope-energy dispersive X-ray spectrometer (SEM-EDS). An X-ray diffractometer (XRD) in combination with FactSage were used to predict the reactions occurring between minerals as well as the mineral transformation and slag formation. The results showed that different ashing temperature affected both ash transformation reactions and volatilization amount of added catalyst, which influenced the ash fusion temperatures and the sintering temperature. The ash-550 °C was chosen to investigate the sintering behavior. The...

Effect of Five Different Additives on the Sintering Behavior of Coal Ash Rich in Sodium under an Oxy-fuel Combustion Atmosphere

This paper was addressed to investigate the influence of different additives on the sintering behavior of coal ash under an oxy-fuel combustion (O2/CO2 combustion) atmosphere. A lignite (Zhundong coal) rich in sodium has been used as the fuel material. The raw ash mixed with additive was heat-treated at 1350 °C under an oxy-firing (30 vol % O2/70 vol % CO2) atmosphere. In this study, five kinds of oxides have been applied as the additive: Al2O3, SiO2, kaolin, CaO, and Fe2O3, while the pure ash acts as a reference. At the same time, the shape shifting of the sintered ash samples during the sintering process was monitored by a charge-coupled device (CCD). The image processing system was used for analyzing the photos captured by the CCD to obtain the shrinkage of area and height of sintered samples. Moreover, the microstructure of the sintered samples was observed by scanning electron microscopy (SEM) equipped with energy-dispersive X-ray spectrometry (EDX), which can analyze the chemical compositions. In addition, the distribution of mineral phases in the sintered samples was identified by X-ray diffraction (XRD). It turned out that SiO2 obviously promoted the melting process, but CaO suppressed the sintering and melting processes greatly. Furthermore, Al2O3, Fe2O3, and kaolin also affected the quantity of molten substances to some extent. Meanwhile, all of the samples are characterized by a layer structure with different colors. The results also show that the mineral phases and microstructure changed dramatically with different additives from the XRD and SEM analyses.

Investigation of rye straw ash sintering characteristics and the effect of additives

The understanding of ash sintering during combustion of agricultural residues is far from complete, because of the high heterogeneity of the content and composition of ash forming matters and the complex transformation of them. In order to make agricultural residues competitive fuels on the energy market, further research efforts are needed to investigate agricultural residues’ ash sintering behavior and propose relevant anti-sintering measures. The aim of this work was to investigate the ash characteristics of rye straw and effects of additives. Three additives were studied regarding their abilities to prevent and abate rye straw ash sintering. Standard ash fusion characterization and laboratory-scale sintering tests were performed on ashes from mixtures of rye straw and additives produced at 550°C. Ash residues from sintering tests at higher temperatures were analyzed using a combination of X-ray diffraction (XRD) and scanning electron microscopy–energy dispersive X-ray spectrometry (SEM–EDX). High sintering and melting tendency of the rye straw ash at elevated temperatures was observed. Severe sintering of the rye straw ash was attributed to the formation and fusion of low temperature K–silicates and K–phosphates with high K/Ca ratios. Among the three additives, calcite served the best one to mitigate sintering of the rye straw ash. Ca from the calcite promoted formation of high temperature silicates and calcium rich K–phosphates. In addition, calcite may hinder aggregating of ash melts and further formation of large ash slag. Therefore, the chemical reactions and physical restraining effects arose by calcite addition contributed to reduction of ash melts and sintering degree. Upon addition of kaolin, compositions of rye straw ash shifted from low temperature melting K–silicates to high temperature melting K–Al–silicates. The changes of ash chemistry were favorable for reducing sintering of the rye straw ash. As the Ca-sludge was added, reduction of sintering of the rye straw ash was less pronounced. Only K4CaSi3O9 and a small amount of KCaPO4 were identified in the rye straw ash as Ca-sludge was added.

Ash Sintering Behavior of Lignite in Catalyzed Steam Gasification with Kaolin as Additive

An investigation of the ash sintering characteristics of LLI lignite with kaolin additive during K2CO3-catalyzed steam gasification was conducted in this study. The ash samples were prepared using a catalytic gasification system at 1073 K under steam atmosphere. Experiments on the sintering behavior were performed using a pressure-drop sintering device under inert N2. Results showed that when increasing the concentration of K2CO3 from 0 to 10 wt %, the ash sintering temperature decreased and the ash molten degree become more serious. The potassium-containing compounds arcanite and kaliophilite can trigger the occurrence of sintering on reactions with other minerals to facilitate the formation of liquid phases and then result in a lower ash sintering temperature. Besides, kaolin can increase ash sintering temperature and ease the melt degree of ashes. Kaolin can react with other minerals to generate more refractory silicon oxide and decrease the fluxing arcanite and amorphous materials in ashes.

Effect of temperature on the sintering behavior of Zhundong coal ash in oxy-fuel combustion atmosphere

This paper was addressed to evaluate the sintering behavior of coal ash at different temperatures under oxy-fuel combustion (O2/CO2 combustion) atmosphere. A lignite (Zhundong coal) characterized by high sodium level has been applied as the fuel material. The raw ash was heat treated at four different temperatures: 1350, 1300, 1250, and 1200°C, respectively. In addition, two atmospheres has been applied to as the reaction atmosphere: (1) 30vol.% O2/70vol.% CO2 (oxy-firing); (2) air (reference). Meanwhile, the shape of the sintered ash samples during the sintering process was monitored by charge coupled device (CCD). The shrinkage of height and area of sintered samples can be obtained by the image processing system. In addition, the microstructure and chemical compositions of the sintered samples were analyzed by a scanning electron microscope (SEM) equipped with energy dispersive X-ray spectrometry (EDX). Moreover, the distribution of mineral phases in the sintered samples was identified by X-ray diffraction (XRD). The results show that the sintering degree of the samples increases with temperature. In addition, all the samples are characterized by layer structure with different colors. Meanwhile, the XRD results reveal that the oxy-fuel combustion atmosphere did not change dramatically the kinds of mineral phases, but did influence the relative amount of crystalline phases.

Fusion characteristics of volcanic ash relevant to aviation hazards

The fusion dynamics of volcanic ash strongly impacts deposition in hot parts of jet engines. In this study, we investigate the sintering behavior of volcanic ash using natural ash of intermediate composition, erupted in 2012 at Santiaguito Volcano, Guatemala. A material science procedure was followed in which we monitored the geometrical evolution of cylindrical-shaped volcanic ash compact upon heating from 50 to 1400°C in a heating microscope. Combined morphological, mineralogical, and rheological analyses helped define the evolution of volcanic ash during fusion and sintering and constrain their sticking potential as well as their ability to flow at characteristic temperatures. For the ash investigated, 1240°C marks the onset of adhesion and flowability. The much higher fusibility of ash compared to that of typical test sands demonstrates for the need of a more extensive fusion characterization of volcanic ash in order to mitigate the risk posed on jet engine operation.

EFFECT OF CHEMICAL COMPOSITION ON SINTERING BEHAVIOR OF JINCHENG COAL ASH UNDER GASIFICATION ATMOSPHERE

In order to obtain detailed understanding of coal ash sintering behavior, a series of experiments have been done on the effect of Jincheng coal ash composition on sintering temperature under gasification atmosphere by the pressure-drop technique. The mineral transformations within its sintering temperature range are simulated by the thermodynamic equilibrium calculation module of FactSage to better understand the experiment results. These results show that the sintering temperature decreases initially, and then rises with increasing SiO2. On the whole, the sintering temperatures decrease with increase in Fe2O3, CaO, Na2O, and K2O. Their effects are quite similar, but the degrees are different. As MgO increases, the sintering temperature decreases. However when MgO is increased above a certain limit, the effect of MgO on the sintering temperature is not obvious.

The sintering behavior of coal ash under pressurized conditions

In order to obtain a detailed understanding of the effect of reaction atmospheres on the sintering temperature of coal ash under elevated pressure (0.7–1.0MPa), a series of experiments have been conducted on the pressurized pressure-drop measuring device, together with analyses using X-ray diffractometer (XRD) analyzer. The results show that the sintering temperatures decrease under the single gas and the atmospheres of mixed reaction gases with increasing in pressure (0.1–1.0MPa). However, the extent of the decrease is not obvious in the pressure range from 0.7 to 1.0MPa. The sintering temperatures of coal ash under the reducing reaction atmospheres (H2, CO and gasification atmosphere) are lower than under oxidizing atmospheres (N2, O2, CO2 and combustion atmosphere). In addition, the XRD patterns show that some minerals in coal ash, such as muscovite and anhydrite, are present as fluxing minerals that can reduce the sintering temperatures; while some feldspar minerals may react with other minerals to produce the low temperature eutectics with the rise in pressure, thus reducing the sintering temperatures.

The effect of iron-bearing mineral melting behavior on ash deposition during coal combustion

Mineral matter in coal is one of the most important sources of problems in coal combustion, including fouling, slagging and corrosion, etc. Mineral matter transformation and slag formation are specific properties of coal that provide more information on the suitability for coal combustion or gasification. In this research, the sintering behavior of Chinese pulverized coal (PC) ash as well as mineral transition mechanism under various atmospheres, especially iron-bearing minerals, was studied by heating microscopy, X-ray diffraction (XRD), Scanning Electron Microscope (SEM) combined with EDX (SEM-EDX). Furthermore, the molecular chemical characteristics of iron-bearing minerals, fayalite (2FeO·SiO 2), were also calculated using quantum chemistry theory to provide an insight into the mineral reaction mechanism at molecular level in detail. The results showed that the different states of iron (Fe 2+ or Fe 3+) are the dominant reasons for different sintering behaviors of coal ash under different conditions. The iron-bearing minerals in ash, such as wustite (FeO), almandite (3FeO·Al 2O 3·3SiO 2) and fayalite, etc., are the most important factors influencing the initial sintering behavior of coal ash in the temperature range from 1273 to 1373 K under reducing condition during coal combustion. In fayalite molecular cluster, it is because that the highest occupied molecular orbital (HOMO) and the lowest occupied molecular orbital (LUMO) are mostly constituted by Fe atoms and the minimum energy difference between HOMO and LUMO in fayalite cluster (1.659 eV) is much lower than that of mullite (3Al 2O 3·2SiO 2, 6.8 eV) and kaolinite (Al 2O 3·2SiO 2·2H 2O, 3.49 eV), the thermal stability of fayalite is relatively low and Fe atoms (especially Fe(6), Fe(8) and Fe(3)) have relatively higher reactivity than any other atoms in fayalite molecular cluster. That is the reason why fayalite starts to melt at relatively low temperature during ash sintering behavior.

The effect of BaCO 3 addition on the sintering behavior of lignite coal fly ash

The effect of BaCO 3 (witherite) addition on the sintering behavior of lignite coal fly ash taken from the Seyitömer power plant of Kütahya/Turkey was examined at temperatures of 1100, 1150 and 1200 °C in air atmosphere. Bloating of the fly ash samples sintered at 1150 °C was prevented, that is, the decomposition temperature of CaSO 4 in the fly ash is shifted to a higher temperature, and their physico-mechanical properties (porosity, water absorption, bulk density and bending strength) were improved with BaCO 3 addition. Positive effects of BaCO 3, however, were not seen on the fly ash samples sintered at 1100 °C. All the fly ash samples sintered at 1200 °C were bloated due to the gas evolving and also they melted. During the thermal treatment at 1150 °C a phase transformation from CaSO 4 (anhydrite) to BaSO 4 (Barite) occurred in the fly ash with BaCO 3 addition as seen from the X-ray diffraction (XRD) patterns and the bar shaped fly ash samples with BaCO 3 saved their structural integrity up to 1150 °C.

Thermal treatment of the fly ash from municipal solid waste incinerator with rotary kiln

Reuse of the fly ash from the municipal solid waste incinerator (MSWI) is a policy of Taiwan EPA. However, the fly ash is often classified as a hazardous waste and cannot be reused directly because the concentrations of heavy metals exceed the TCLP regulations. The main objective of this study is to investigate the continuous sintering behavior of fly ash with a rotary kiln and seek a solution to reduce the concentrations of heavy metal to an acceptable value. The partitions of the heavy metals in the process are also considered. The results of TCLP showed that among the metals of Cr, Cd, Cu and Pb, only the concentrations of Pb in raw fly ash exceeded the regulation. At sintering temperatures of 700, 800 and 900 °C, the concentration of Pb decreased in sintering products, however, the concentration of Pb still exceeded the limitation at 700 and 800 °C. Additionally, the water-washing was used to pre-treat the fly ash before sintering process. The washing treatment effectively reduced the leaching concentrations of Pb to agree the regulations. Therefore, water-washing followed by a sintering treatment is an available process for detoxifying the fly ash of MSWI.