Dechlorination of pentachlorophenol by grinding at low rotation speed in short time

In order to apply grinding method for degradation of pentachlorophenol(PCP) to an industrial scale,the proportion of different materials[CaO,SiO_2 and CO(NH_2)_2]and the size of grinding balls were examined.For saving energy and increasing dechlorination efficiency,the rotation speed and grinding time were maintained at relatively low values.At a mass ratio of grinding balls to materials(40:1),PCP was added into a big steel jar(300 ml) with other materials to grind at 300 r ·min^(-1)for 5 h.The results indicated that when PCP was mixed with CaO and SiO_2in a molar ratio of 1:60:60,the best dechlorination of 58.4%was achieved.CO(NH_2)_2 could not be used as hydrogen donor in the dehalogenation by mechanochemical reaction,since it restrained the dechlorination process.The size of grinding balls has significant effect on the reaction.The experiment with 5 mm steel balls indicates that the weight is too light to provide appropriate energy for the reaction,while steel balls of 10 and 15 mm could give better dechlorination reaction.It indicates that dechlorination depends on the mass of balls and fill rate.

Sensitivity analysis of the surface integrity of monocrystalline silicon to grinding speed with same grain depth-of-cut

Mechanisms for removal of materials during the grinding process of monocrystalline silicon have been extensively studied in the past several decades.However,debates over whether the cutting speed significantly affects the surface integrity are ongoing.To address this debate,this study comprehensively investigates the effects of cutting speed on surface roughness,subsurface damage,residual stress,and grinding force for a constant grain depth-of-cut.The results illustrate that the changes in the surface roughness and subsurface damage relative to the grinding speed are less obvious when the material is removed in ductile-mode as opposed to in the brittle-ductile mixed mode.A notable finding is that there is no positive correlation between grinding force and surface integrity.The results of this study could be useful for further investigations on fundamental and technical analysis of the precision grinding of brittle materials.

Heat Transfer Characteristics outside the Condenser of a Rotating Heat Pipe Grinding Wheel with a Lateral Air Impinging Jet

This study numerically analyzed the heat transfer characteristics outside the condenser of a rotating heat pipe grinding wheel(RHP-GW).The goal of this investigation is to determine the optimal structure and parameters for the condenser section of RHP-GW.Different fin height(f=0-7 mm),rotational Reynolds number(Rer=1602-6408)and jet Reynolds number(Rej=42379-108302)were analyzed under input heat flux of 4000 W/m2.A fully developed flow was imposed at the outlet of the nozzles.Results showed that the optimal heat transfer rate was obtained for fin height of 5 mm,which improved the average Nusselt number by 84%compared to the structure without fins.A critical Rej for each Rer that the impinging jet can reach the condenser section was found.The critical Rej value increases with Rer,which is in the range from 42379 to 61215 and 61215 to 80050 for Rer=6408 and Rer=9610,respectively.