Biomass contains a high content of alkali metal elements

which can cause serious slagging problems during the combustion process. Coal gangue is a kind of bulk solid waste

and its resource utilization is an urgent need. In order to solve the problem of biomass combustion slagging and coal gangue utilization

coal gangue was used as an additive and mixed with sunflower straw for combustion. Physical and chemical characterization of the burned ash samples were carried out using thermogravimetric analysis(TG-DTG)

inductively coupled plasma spectrometry(ICP-AES)

and ash melting point tester. The effects of temperature and ratio on the combustion performance and slagging of mixed fuels were also investigated. The research results show that

during the combustion of sunflower straw

the addition of a small amount of gangue significantly increased the alkali metal content in the ash. More of these metals were converted into high-melting-point silica-aluminates

which were fixed in the ash samples

while the gaseous alkali metal content decreased. As a result

the tendency for slagging during combustion was reduced. At the same time

the sunflower straw reduced the ignition point and burnout temperature of the gangue

thereby promoting its combustion. The synergistic effect was obvious. When the proportion of coal gangue was 20%

the flammability index of the fuel reached 9.36×10~(-4)%/(min·℃)

and the comprehensive combustion characteristics index reached 42.6×10~(-7)%/(min~2·℃~3). The combustion performance was optimal

with a softening temperature of 1 470 ℃

and the tendency for slagging was significantly reduced.