Extraction of lithium from coal fly ash by low-temperature …
The glass phase in coal fly ash was converted to water-soluble fluoride salts after the salt activation process, which was followed by the extraction of lithium from the glass phase via water leaching. ... The leaching efficiency of lithium increases gradually from 32.56 % to 90.82 % when the mass ratio of SiO 2 /NH 4 F increases from 1:0.75 to ...
Engineering and Leaching Behavior of Lime-Treated Fly Ash …
Furthermore, the addition of m-NC to fly ash led to increased compressibility but in same time, it reduces for lime-treated fly ash. However, the permeability of untreated and lime-treated fly ash decreased with the addition of m-NC. The leaching potential of metal ions decreased significantly with the addition m-NC to fly ash.
Leaching of fly ash
The environmental impact of coal ash production has at least two aspects: (a) emission and deposition of enormous amounts of coal ash, polluting air, water and soil with ash particles (including the problem of huge ash dumps); (b) leaching of microelements (including toxic heavy metals), but also major cations and anions from ash by atmospheric and surface waters …
Immobilization of heavy metals from MSWI fly ash …
Herein, long-term leaching behaviors of Pb, Zn, and Cd in MSWI fly ashes solidified by a novel cementitious material (MSCM) containing phosphoric acid sludge were investigated.
Solidification of heavy metal in municipal solid waste incineration fly
The main raw materials for this research were fly ash, slag, and MSWIFA. The fly ash was Class F fly ash with a specific surface area of 430 m 2 /kg and a density of 2.42 g/cm 3. The slag was S95-grade slag powder with a specific …
Sequential alkaline-organic acid leaching process to …
The optimum alkaline leaching conditions (10 mol/L NaOH, temperature of 65 °C, L/S ratio of 10 mL/g, and t of 90 min), resulting in Si and Al leaching efficiencies of 28% and 32%, respectively. Sequential alkaline-organic acid leaching process results in an overall REEs recovery of 77.6%, much higher than that of alkaline leaching process (32.2%).
Gypsum-Enhanced Red Mud Composites: A Study on …
The strong alkalinity of red mud and the heavy metals it contains pose a serious threat to the environment. This study investigated the possibility of applying red mud as a solid waste material in road construction to mitigate the problem of red mud accumulation. Red mud was modified using titanium gypsum and phosphogypsum as curing agents. The effects of …
Characteristics and leaching behavior of MSWI fly ash in …
Specifically, pH value of MSWI fly ash was 12.37, and it was noncorrosive. The density of MSWI fly ash was up to 2350 kg/m 3, and surface area of MSWI fly ash was as high as 766 m 2 /kg, which was beneficial to leaching of heavy metals, and it also increased the risk of contamination to the environment (Pan et al., 2013, Weibel et al., 2016).
Geotechnical and Leaching Properties of Municipal …
leaching behavior. The MSWI fly ash was produced from a refuse derived fuel process in which only the light fraction of municipal solid waste was utilized in a fluidized bed combustion process. The
The occurrence of gold in fly ash derived from high-Ge coal
We present the first data on the mode of occurrence of Au in fly ashes from the Wulantuga and Lincang power plants in China, which burn high-Ge coal. Gold occurs as fine-grained drop-like particles with a size of n*0.01–0.2 μm on the surface of the glass globules. These features of the Au particles are proof for Au condensation from the gas phase and …
Metal removal from Municipal Solid Waste Incineration fly ash…
The leaching behaviour of MSWI fly ash was investigated as a function of pH (e.g., Astrup et al., 2006) by testing the sample material subjected to several stages of pH and by analysing leaching solutions at specific pH intervals.
Removal techniques for heavy metals from fly ash
Considering the alkaline nature of fly ash, fungal leaching seems to be a better option as compared to bacterial leaching owing to the ability of fungus to grow at high pH. …
The formation of gold in woody biomass combustion ashes
Three stage leaching of ashes significantly enriched the gold concentration. This paper investigates the enrichment of gold through combustion and ash-leaching techniques …
Heavy Metals Removing from Municipal Solid Waste …
After the electric field-enhanced washing, the leaching toxicity of MSWI fly ash is greatly reduced when compared with the original samples, and metal leaching toxicity of all the elements is below all their thresholds.
Characterisation and Hydrochloric Acid Leaching of Rare …
Rare earth elements (REEs) have been identified as valuable and critical raw materials, vital for numerous technologies and applications. With the increasing demand for and supply gap in REEs, many research studies have focused on alternative sources of REEs. This study involved an elemental and mineralogical characterisation of discarded coal from a coal plant and coal …
Mechanical and durability assessment of phosphogypsum
Similar results have been observed by Gupta and Siddique, indicating that the lower sorptivity of fly ash-based concrete is 5.6 × 10 −3 mm/sec 1/2 [78]. Sharma and Khan, on the other hand, found that the minimum sorptivity for fly ash based concrete was 1.0 × 10 −2 mm/s 1/2 [79]. The sorptivity coefficient obtained for AAC falls within ...
Leaching mechanisms of heavy metals from fly ash stabilised …
Fly ash is an industrial waste material that is repurposed as a soil stabiliser worldwide. In Thailand, many ground improvement projects utilise mixtures of cement and fly ash to stabilise weak soils. In this study, leaching mechanisms of arsenic, chromium, lead, and zinc from cement and fly ash stabilised soils were investigated in the laboratory.
Distributions and Leaching Behaviors of Toxic Elements in Fly Ash
Fly ash usually contains a considerable amount of toxic elements that can be leached into the environment, thereby easily leading to serious contaminations. In this work, the leaching behaviors of poisonous elements including boron (B), phosphorus (P), vanadium (V), chromium (Cr), arsenic (As), selenium (Se), molybdenum (Mo), antimony (Sb), and tungsten (W) from fly …
Strengthening desilication of coal fly ash by alkaline leaching …
Coal fly ash (CFA) as a kind of solid waste is mainly produced in the coal-fired power plant. In the world, approximately 800 million tons of CFA is generated annually and its resource utilization attracts many researchers' attention (Chen et al., 2023, Shoppert et al., 2020, Peng, 2019).CFA consists of a predominant aluminum–silicon matter with minor and variable …
Early mechanical strength, hydration mechanism and leaching …
Effects of water/powder ratio, mixing ratio of fly ash, and curing temperature on pozzolanic reaction of fly ash in cement paste Cement Concr. Res., 31 ( 2001 ), pp. 31 - 39
Analysis of Heavy Metal Leaching in Fly Ash from One …
The characteristics and leaching behavior of heavy metals in fly ash, sampled from one MSWI (municipal solid waste incineration) plant in Shanghai China, were investigated. The results indicated that the main elements of fly ash were Fe, K, Na, Cl, Si, Ca, Al, and the total fraction of heavy metals was in the range of 0.8 % - 2.0%. Hence, MSWI fly ash was considered to be …
The formation of gold in woody biomass combustion ashes
Pure gold particles in the size of 1–2 μm are presented in the after heat exchanger ash; meanwhile, gold in fly ash is primarily associated with potassium, sodium, sulfur, and oxygen. ... Therefore, this study investigates the enrichment of gold by combustion and ash leaching techniques utilizing pelletized woody biomass used as fuel, while ...
Alkali leaching features of 3-year-old alkali activated fly ash …
Alkali-activated material (AAM) is regarded as a promising greener cement that is attracting worldwide attention. This paper reports an investigation on the leaching behaviour of a series of 3-year-old AAMs that are manufactured from fly ash-slag-silica fume. The leaching percentages of sodium from the binders consist of 45–60% fly ash, 30–40% slag and 0–15% …
Distributions and Leaching Behaviors of Toxic …
In this work, the leaching behaviors of poisonous elements including boron (B), phosphorus (P), vanadium (V), chromium (Cr), arsenic (As), selenium (Se), molybdenum (Mo), antimony (Sb), and tungsten (W) from fly ash were …
A study on selective leaching of heavy metals vs.
The leaching of Cu, Fe, Ni, Pb, and Zn from fly ash using a variety of lixiviants at a constant temperature of 33 °C was investigated to observe the leaching behavior of various valuable, impure, and minor metals present in …
Recovery of Alumina from Coal Fly Ash by CaCl …
Keywords: Coal fly ash; Calcination; Leaching; Alumina recovery. Introduction. Coal-burning power plants consume pulverized solid fuels and . produce a large amount of coal fly ash (CFA) as residues. The coal-fired generation accounted for 41% of the world electricity supply in 2006, while the share is projected to be 43% in 2030 [1]. In 2015, the
Experimental Study of Strength of Leachate Sludge Solidified …
The leachate sludge is solidified by sulphoaluminate cement (SAC) combined with municipal solid waste incineration fly ash (MFA). The unconfined compressive strength (UCS) test, microscopic observation test, and leaching toxicity test …
Rare earth elements recovery and mechanisms from coal fly ash …
As shown in Fig. 8, the whole column leaching process can be divided into the following three stages: early leaching period (0–12 h), middle leaching period (12–72 h), and late leaching period (72–168 h) according to the concentration of REEs in the lixivium. The content of LREEs in the lixivium was significantly higher than that of HREEs.
Leaching behavior of heavy metals from municipal solid …
The correlation of leaching concentration and leaching time is better. Immobilization effect of cement on MSWI fly ash is good. Even if MSWI fly ash-cement hardened pastes were damaged, the leaching toxicity is still in a safety range. The long-term resistance to heavy metals leaching capability of MSWI fly ash-cement hardened pastes is better.
Lithium activation pretreatment mechanism and leaching …
At present, most of the studies on lithium in fly ash focus on the leaching process, while there are fewer studies on the activation mechanism of roasting. In view of the above problems, the roasting activation mechanism of fly ash in the Pingshuo mining area (northern China) is investigated, and the leaching process of lithium is optimized.