Effect of walnut shell ash on pore structure characteristics during Zhundong coal sintering

Abstract

This paper aims to reveal the effect of walnut shell (WS) ash on the pore structure characteristics during Zhundong (ZD) coal sintering process. The working temperature was set as 1200 °C. The internal three-dimensional models of samples were obtained based on X-ray computed microtomography (XCT) technology while the pore evolution process and mechanism in the ash sintering process were studied, which has not been studied in previous work. The X-ray diffraction (XRD) results showed that adding 10% WS promoted the formation of gehlenite which inhibited the sintering of ash samples. A large amount of K was converted into gas and significantly promoted the formation of pore structures. Besides, the macroscopic change, pore structure, pore parameters were studied. The XCT results showed that the porosity of ZD samples was maintained at 5.46%–40.92% in the whole sintering process. The internal pore structures in ZD samples were mainly constructed of small pores (De < 0.3 mm, where De is the equivalent spherical diameter). After adding 10% WS ash, the porosity was increased to 42.50%–50.30%, and the overall pore size distribution also shifted to the direction of large pores. In particular, there was a super large pore inside the 10% WS samples.