Influence of waste brake oil on the rheological properties of coal-sludge water slurry

In this work, the effect of waste brake oil (WBO) on the dispersion property of coal-sludge oil slurry (CSOS) was investigated and comprehensively analyzed. Apparent viscosity of CSOS decreases from 997 to 276 mPa.s with the increasing of SS content from 0 to 12% under the calorific value (CV) of 17.70 MJ/kg and oil/sludge ratio (O/S) of 2.0. The combination of sewage sludge (SS) and WBO could decrease the apparent viscosity of CSOS, and SS content and O/S are two important parameters to affect the apparent viscosity. WBO mainly contains the hydrocarbon compound and a lot of oxygenated functional groups according to its GC/MS results. WBO could cover on the surface of SS and coal particle, and reduce their hydrophobic character and the adsorbance amount of dispersant based on the FTIR, XPS and adsorption performance results. In addition, the mechanism of WBO on slurry characteristics of CSOS was investigated. With the low content of WBO, the liquid bridges from WBO force the solid particles to adhere together and form a stable network structure, thus reducing the flow ability of the suspension. With the increasing of WBO, the network structures could be broken into cells, resulting in a dramatic decrease in viscosity. This research provides a potential way to dispose the SS and waste industry oil.

Automated summary

In this study, the effect of waste brake oil (WBO) on the dispersion property of coal-sludge oil slurry (CSOS) was investigated. It was found that WBO could significantly reduce the apparent viscosity of CSOS and by adjusting the sewage sludge (SS) content and oil/sludge ratio (O/S), the viscosity of CSOS could be effectively improved. WBO mainly consists of hydrocarbon compounds and oxygenated functional groups, which could form a covering layer on the surfaces of SS and coal particles, reducing their hydrophobicity and the adsorption of dispersant. This research provides a potential method for the disposal of waste sludge and industry oil.