1. Enriching heavy metals: Fly ash contains a lot of heavy metals, such as lead, cadmium and chromium. Excessive application will lead to excessive heavy metal content in soil, which will affect plant and human health.
2. Changing soil pH: Fly ash contains a certain amount of alkaline substances such as calcium oxide. Excessive application will make soil reactivity alkaline and affect the growth and function of soil microorganisms.
3, nitrogen, phosphorus and other nutrients imbalance: after excessive application of fly ash, the proportion of nitrogen, phosphorus and other nutrients in the soil will change, leading to nutrient imbalance and affecting plant growth.
4. Impact on groundwater quality: Heavy metals, nitrogen, phosphorus and other substances in fly ash penetrate into the groundwater layer through the soil layer, which will have an impact on groundwater quality and threaten the safety of water resources.
Fly ash is fine ash collected from flue gas after coal combustion. Fly ash is the main solid waste discharged from coal-fired power plants. The main oxides of fly ash in thermal power plants in China are silica, alumina, iron oxide, iron oxide, calcium oxide and titanium dioxide. With the development of electric power industry, the emission of fly ash from coal-fired power plants has increased year by year, and it has become one of the industrial waste residues with large emissions in China.
If a large amount of fly ash is not treated, it will produce dust and pollute the atmosphere; If it is discharged into the water system, it will cause river siltation, and the toxic chemicals in it will also cause harm to human body and biology. However, fly ash can be used as a resource, for example, as an admixture for concrete.
Main source:
The main sources of fly ash are coal-fired power plants and urban central heating boilers, of which more than 90% are wet discharged ash, and its activity is lower than that of dry discharged ash, which consumes water and electricity, pollutes the environment and is not conducive to comprehensive utilization.
In order to better protect the environment and benefit the comprehensive utilization of fly ash, considering the maturity of dust removal and dry ash transportation technology, dry ash collection will become the development trend of fly ash collection in the future.