Research On Foam Insulation Materials Prepared By Sludge With Autoclave Technology

The quantity of municipal and industrial sludge has been sharply increased due to the pollution control of the urban and industrial waste water. Accordingly, the development of sludge recycling technologies has been one of the hottest topics because of the complicated compositions of sludge, the difficulty of sludge treatment and its great damage to the environment. The Utilization of sludge as building materials has broad prospect in the aspect of the reduction, harmlessness and recycling of sludge.After analyzing the development and application status of sludge treatment technologies both at home and abroad, this work proposed to produce foam insulation materials from sludge employing the autoclaved curing method, under the support of on the major national science and technology project-water (2010ZX07319-002) and 2014 scientific research of Jiangsu environmental protection (2014028). According to the evaluation indexes of high foam expansion, long half-life period and non-interfering foam stabilizer, the optimum composite proportion was OP of 6% and the cellulose ether foam solution of 3%.One comprehensive evaluation index was established including density, compressive strength and coefficient of thermal conductivity. According to an orthogonal experiment conducted at a test bench designed for specific foam insulation board, the optimum composite proportion is:12.5% of sludge,55.5% of cement,24% of coal power ash,8% of engineering sand and a water-solid ratio of 0.55. A comprehensive evaluation index containing the compressive strength, coefficient of thermal conductivity and water absorption rate was proposed. The optimum operating conditions for producing the sludge derived foam insulation materials are the static placing time of 3d, autoclave temperature of 150? and holding time of 3h based on an orthogonal experimental study. Under these conditions, the density, compressive strength, coefficient of thermal conductivity and water absorption rate of the sludge derived foam insulation material are 626.4 kg/m3,0.572MPa,0.0407W/m·K and 15.9% respectively, which meets requirements of A06, CO.5, A03 and W15 standardized in JG/T266-2011.The autoclaved curing process has played a significant role in shortening the hydration molding time and improving the compressive strength and thermal insulation property of sludge insulation boardThis study explores the effect of the operating conditions of molding and steam pressing on the immobilization of heavy metals. The results show that cement-coal powder ash-engineering sand system after autoclaved curing has played a quite good role in immobilizing the heavy metals in sludge. This work has some referential value for the utilization of sludge containing heavy metals.