The Preparation Of New Types Of Flocculants From Aluminum Waste Solids

Two kinds of flocculants (PAS and PASS) were prepared respectively using aluminum dross from surface pretreatment process of aluminum iindustries and waste catalyst from petroleum industry. At first, the aluminum dross as raw material instead of aluminum hydroxide was dissolved by sulfuric acid, and then additives were added to the aluminum solution. Under high shear mixing, the flocculants was made through polymerizing and ageing reaction. The optimum reaction conditions were selected. The flocculating results show that PAS have a better performance on the removal rate of turbidity, COD, SS and color for treating simulated sewage, headriver and industrial wastewater than that of PAC (polyaluminum chloride). The waste catalyst was dissolved under the condition: 1.2 times of theoretical amount of sulfuric acid was needed, the concentration of sulfuric acid was 70%, the reaction temperature was 120℃, and reaction time was 2.5 hours. The recovery rate of aluninum reaches 94%. Under high shear mixing condition, water glass and other additives were added to the aluminum solution, then after polymerizing and ageing, the flocculants of PASS was produced. The flocculation of PASS on diatomite suspension of different turbidity was investigated. The results show that PASS can cause much more effective flocculation of diatomite suspension, especial for low temperature and low turbidity water. The mechanism of flocculation is related to absorption, bridging and sweeping of PASS on diatomite particles.There are few simply and inexpensive methods that can be used to study the species distribution of flocculants. Al-Ferron timed complex colorimetric method is a simple method to be used to analysis aluminum species. First, A series of PASS with different basicities(B) and Si/Al molar ratios were prepared using aluminum sulfate. water glass and sodium carbonate as raw materials. The species of PASS were studied by Al-Ferron timed complex colorimetric method. The results show that the Si/Al molar ratio, basicity (B) and ageing time have effect on the reactivity of Alb and the species distribution of PASS. The Al-Ferron complex colorimetric reaction of Alb in PASS solution follows the pseudo-first order kinetics. The reactivity of Alb and the amount of Ala, Alb and Alc are related to the stability of PASS.