In view of severe slagging problems occurred during combustion of blending coals of high sodium coal and iron-rich coal from Xinjiang area

the potential of Ca_3(PO_4)_2 additive for relieving the slagging propensities was studied by using a drop tube furnace in this article.Moreover

the composition

mineral phase and morphology of slag samples collected on an un-cooling probe were analyzed in detail by various characterization methods.The results show that

the melting temperature of blending coal ashes can be significantly increased after adding 3%Ca_3(PO_4)_2 into the blending coals.The softening and deformation temperatures can be increased by 200℃and150℃

respectively.For the blending coals with mass ratio of high sodium coal to iron-rich coal of 40:60 without additives

the slags adhered to the surface of the uncooled probe at 1 200℃showed to be molten.The main components inducing ash particles into be melted

are mainly comprised of Fe_2O_3 and low temperature eutectic system of Si-Al-Ca containing mineral phases.While for blending coal with 3%Ca_3(PO_4)_2 addition

the ash particles adhered to the probe at 1 200℃presented to be granular and the melting degree for the whole collected samples decreased.The ash particles on the probe at 1 000℃became loose and easy to be blown off.After adding3%Ca_3(PO_4)_2 into the blending coals

the main reason for a sharp decrease in the melting degree of ash particles is that Ca_3(PO_4)_2 combining with Na-or Ca-containing components can transform to Ca_5(PO_4)_2Si O_4 and Na_3Ca_6(PO_4)_5 with a high melting point.This reaction pathway can effectively transfer the gaseous Na-containing component into solid form.It also inhibits the condensation of gaseous alkali metal/alkaline earth metal components and the possibility for low temperature eutectic reaction taking place between gaseous Na-containing component and Si-Al bearing minerals.Therefore

this additive has a good effectiveness in term of reducing the slagging propensity for blended coal with a characteristic of high sodium and iron-rich.