Using fly ash from waste incineration power plant to make cement
According to the principle of waste incineration, there are two main types of incinerators in domestic waste incineration power plants, namely mechanical grate furnace and circulating fluidized bed. The amount of fly ash produced by the mechanical grate furnace is about 3% of the total amount of incinerated garbage, and the circulating fluidized bed is about 10% of the amount of incinerated garbage due to the addition of coal powder and other combustion-supporting substances during the incineration process. According to relevant statistics, the total amount of domestic waste incineration in China in 2020 will be about 170 million tons, and the amount of fly ash will be about 5.1 million tons.
At present, about 80% of fly ash in the country is treated with stabilized landfill technology. Although this technology solves the problem of fly ash treatment, it takes up land resources and at the same time stabilizes the stability of the flocculated sediment formed by landfilling, which still needs further exploration. Stabilized landfill refers to completing the stable solidification of fly ash by adding stabilizers, and then burying the solidified fly ash.
Cement production technology after fly ash washing
The main component of fly ash is similar to limestone, and it can be used as a substitute for fired cement clinker. Cement kiln co-processing technology uses fly ash as cement raw material to completely decompose dioxins and solidify heavy metals in cement clinker. The salt in the fly ash gradually transforms into a solid state as the temperature decreases, and continuously transforms between the gas-liquid-solid phase, which is easy to cause skin blockage.
At present, the fly ash is washed with water before it enters the kiln, which can effectively inhibit the skin blockage. Since the national policies to encourage the co-processing of solid waste and hazardous waste in cement kilns have been introduced, the attention of the technology of co-processing fly ash in cement kilns has increased sharply.