Method used for prolonging initial setting time of circulating fluidized bed combustion flying ash in cement or concrete

Abstract

The invention belongs to the field of solid waste recycling and building material application, and more specifically relates to a method used for prolonging initial setting time of circulating fluidized bed combustion (CFBC) flying ash in cement or concrete. According to the method, cement or concrete is mixed with CFBC boiler flying ash and dihydrate gypsum, and the adding amount of dihydrate gypsum is controlled at a value so as to control the total SO3 mass content of the obtained cement or concrete is 3.0 to 6.5%. The adding amount of dihydrate gypsum in cement or concrete is reasonably controlled, so that a problem of applying CFBC boiler flying ash into cement or concrete directly that initial setting time is relatively short is solved, and large consumption of CFBC boiler flying ash is realized. Silicate industrial solid waste is taken as a part of the raw materials used for adjusting the initial setting time; cost is low; economic benefit is high; and market competitiveness is higher than that of similar products. The method is simple; operation is simple; and practicability is extremely high.

Description

technical field [0001] The invention belongs to the field of solid waste recycling and application of building materials, in particular to a method for prolonging the initial setting time of circulating fluidized bed fly ash in cement and concrete. Background technique [0002] Circulating fluidized bed (CFBC) combustion technology is a new type of combustion technology in which the bed material is burned in a fluidized state. Because it can use low-quality coal as fuel, and can effectively control the emission of sulfur dioxide in the coal-burning process, it has become the main combustion method for boilers in newly-built thermal power plants in my country in the past 15 years, and my country has fully grasped that the operating temperature is strictly controlled at 730-950°C A complete set of system solutions including design, manufacture and control. [0003] However, the use of low-quality coal leads to the amount of fly ash produced by CFBC boilers per unit of power ge...

AI Technical Summary

Problems solved by technology

However, we have found through systematic research that the silicate substance in CFBC boiler fly ash itself is metakaolin (or calcined kaolin), which has excellent pozzolanic activity and can be used as cement and concrete admixtures, but directly added to CFBC boiler fly ash Ash in cement and concrete, its initial setting time is short, generally less than 100 minutes, which limits its extensive application in building materials