Research On Dewatering Conditioning Technology Of Aluminum Processing Sludge

Guangdong Province is a major province in the processing and manufacturing of aluminum profiles in China,as well as a large province in the consumption of aluminum profiles.In the anodizing technology,aluminum profile produces a large amount of waste liquid which is then processed by sedimentation to obtain sludge.Furtherly,the dehydration of the sludge results in the aluminum-containing waste residue.Currently,aluminum profile plants usually use sludge dewatering treatment methods that combine chemical conditioning and mechanical pressure filtration.The moisture content of the settled sludge is yet high,usually about 89%.This high moisture content of the sludge consequents in an expensive transportation cost,along with a negative impact on the comprehensive utilization of the aluminum processing sludge.This dissertation first analyzes the properties of the original sludge,then dehydrates the sludge chemically and physically,before comprehensively examines the changes of the dewaterability of the sludge.Through GC-MS analysis,XRF analysis,XRD analysis,particle size analysis,SEM analysis,thermogravimetric analysis,etc.,a preliminary understanding of the physical and chemical properties of the sludge has been obtained.The results indicate an extremely low organic content,which implies that the aluminum processing sludge is mainly inorganic.The dry base of aluminum processing sludge contains about 40%of the aluminum element and a large amount of O.The large amount of aluminum is the basis for the resource utilization of the aluminum processing sludge.XRD results show that the existence of aluminum in the sludge is in the form of bayerite??₁-Al?OH?₃?,and the presence of bayerite results in the containing of partially bound water in the sludge.The results of particle size analysis show that the sludge has a fine particle size and poor dehydration performance.The SEM analysis of the sludge shows that more pores in the sludge can absorb a large amount of water,while thermogravimetric analysis reveals the binding energy distribution of sludge floc and water.Chemical conditioning the sludge by using PAM flocculant,Fe Cl₃,chitosan,and fly ash.Experimental results show that PAM flocculant can effectively improve the dewatering performance of the sludge.When the dosage of 1 g/L PAM reaches about 6 m L,the water content of the sludge reduces to the lowest point at 84.16%,and the optimal p H of PAM flocculant is 7.Chemical conditioners such as Fe Cl₃,chitosan,and fly ash may not improve the dewatering performance of aluminum processing sludge.Physical conditioning experiments are performed on aluminum processing sludge,using the microwave,ultrasonic,and microwave-ultrasonic combined conditioning and dehydration technologies.The moisture content and loss ratio of the sludge are analyzed and compared under different conditions,from which the following conclusions are drawn.Microwave and ultrasonic conditioning and dewatering technology can significantly reduce the moisture content of sludge to the final rates at 74.87%and 77.57%respectively,and the combined microwave-ultrasonic conditioning furtherly reduces the moisture content to 74.09%.XRD analysis is performed on aluminum processing sludge,and the results show that neither microwave nor ultrasound affects the existence of aluminum in aluminum processing sludge.The concept of sludge porosity is introduced.Matlab is used to binarize the sludge electron microscope image.The analysis of the binarization result of this image suggests that in the case of microwave-ultrasonic conditioning,the pixel ratio decreases from 75.3%to 39.59%.