Journal of Chemical Engineering of Japan, Vol.49, No.6, 503-510, 2016
A Novel Mixer with a Hollow Spiral Structure for Preparing Inorganic Solidified Foam
Plugging leaks and controlling winds are the most effective approaches for preventing coal/oxygen-compounded reactions and spontaneous combustion of coal. Inorganic solidified foam (ISF) is an effective material for preventing spontaneous coal combustion, and the mixer used in formulating ISF is important for improving the homogeneity and expansion ratio. In order to prepare an ISF with a good performance, a novel mixer was designed for mixing aqueous foam with composite slurry. The mixer had a hollow spiral structure that reduced the breakdown of the aqueous foam and increased the foam slurry contact area. We analyzed the mixing mechanism and the process by which the composite slurry particles combined with the aqueous foam to form ISF. We found that there was an optimal relationship between the rotational speed of the mixer, homogeneity, and expansion ratio. The performance of the mixer was investigated experimentally using various rotational speeds and aqueous foam flow ratios. Experimental performance testing and evaluation showed that for different aqueous foam flow ratios, and for the rotational speeds of 100 rpm or 150 rpm, the relative standard deviation of the pore area was minimal and exhibited good homogeneity. Simultaneously, the value of the expansion ratio reached a maximum, and the breakage of aqueous foam was minimal. The results of this experiment provide the basis for coal mine field applications for ISF.