Composite insulators have been widely used in transmission lines. After being removed from transmission lines

their housing silicone material cannot degrade naturally. To tackle this problem

this paper proposes an effective method to recycle waste insulators by pyrolysis to obtain mullite

$(\mathbf{3}\mathbf{Al}_{2}\mathbf{O}_{3}\cdot \mathbf{2}\mathbf{SiO}_{2})$

with high purity and compact structure. The recycling process studied will not generate toxic products. The thermal degradation process of housing material is investigated by analyzing its degradation products including the gas and residues in detail. The experimental results indicate that the colorant agent Fe

2

O

3

inside the housing material is beneficial for the generation of mullite by decreasing the temperature of mullitization. Besides

since the transitional alumina generated by the dehydration of aluminum hydroxide (ATH) has a smaller diameter and can better dissolute into the silica phases

ATH is a better choice as the additional aluminum resource. By comparing the components

structure

and particle size of grains formed at different calcination temperatures

the proposed py

rolysis temperatures of the two stages are 1400°C and 1600°C

respectively.