The main technical characteristics of producing of fly ash ceramsite

The main technical characteristics of the production of fly ash ceramsite by rotary kiln are:
1. Disc granulation process:
Before Powder material enter into the disk granulator, first it need to spray wet in the twin-axis mixer, by uniform mixing, form the ball core. After moisture content of the mixture should not be greater than 10%, both form less than 3mm the ball core, but also does not produce massive phenomenon. And then they load into the disc pelletizing machine. The process requirements are as follows:
A. Ensure that the mixed powder material is uniform, mixed powder fineness should be ≤ 0.1mm;
B. Material ball size uniform, the general requirements of 5 ~ 12mm;
C. The strength of material ball can meet the requirements of crushing and rolling in the process of feeding, feeding and kiln calcining. It will not lead to rupture and crushing and produce large amount of powder. The general requirements of the impact strength of the material in the distance from the steel platform 2m height, free fall is not broken for the degree. Thus, after the disk granulation, the film was cured at 70 to 80C for 1 hour.
D. The moisture content of the material ball should be determined according to the performance and fineness of the mixture, the general control in 10% to 12%.

2. Sintering process
In accordance with the kiln material temperature and reaction conditions, ceramic rotary kiln can be divided into dry, preheating, firing and cooling four bands.
A. Curing drying zone: The material was heated from room temperature to 200 ° C. This stage is mainly the evaporation of physical water in the material. The key point of the process control is to control the proper drying speed, according to the moisture content of the raw material ball and the explosive property of the material when heating, so as to prevent or reduce the raw material ball.
B. Preheat zone: the material from 200 ℃ to 950 ℃. This stage is mainly the remnants of physical water and some chemical combination of water discharge, oxidation of organic matter, carbonate, sulfide decomposition, quartz crystal transformation.
C. Firing zone: The material was heated from 950 ° C to the firing temperature and held at that temperature for a period of time. During this stage, a series of reactions such as decomposition of carbonate, coexistence of iron oxide with reducing substances such as carbon and hydrogen were carried out except that a part of the minerals in the preheating zone were oxidized and the decomposition reaction continued. (Such as 2CaCO + SiO2 → Ca2SiO4 + 2CO2), the material at 950 ℃ before and after the gradual liquid phase, solid phase gradually dissolved in the liquid Phase, the formation of a new crystalline phase (such as 3Al2O3 • 2SiO2 → mullite) and so on.
D. Cooling zone: from the firing temperature of the material down to about 950 ℃. This phase of the material in the liquid phase continue crystallization, the rapid increase in viscosity due to the material gradually solidified. Materials stay the time not too short in the cooling zone, otherwise on the liquid crystal growth and adverse growth, and may affect the product strength.