Utilization Of Iron Tailings And Lead-zinc Tailings For The Preparation Of Geopolymer

In China,95% of energy and 85% of raw materials come from mineral resources, the exploitation and utilization of which will bring a series of environmental problems. As a primary type of solid mining wastes, tailings are also a major source of pollution. In the exploitation of mineral resources, considerate amount of tailings are thrown away, which would not only cause pollution but waste the exploitable resources in the tailings. Therefore, for the protection of environment resources, an experimental investigation on the comprehensive utilization of tailings is of great significance.Thanks to their superior physicochemical properties, low energy consumption in preparation, abundance and ease of processing,geopolymer has attracted great attention from researchers and been under intensive study in the field of inorganic materials.We used the tailings of rare earth element-containing iron ore from Bayan Obo, Inner Mongolia and Lead-zinc tailings from Fujian Jindong Mining Co., Ltd in the preparation of and mechanism study on this geopolymer.First, analyses were conducted on the chemical composition, phase and microstructure of the tailings. Though the tailings had some salic content, its activity was low. So some activation measures were taken in order to ensure the effective utilization of useful components during the process of alkali excitation. After a lot of experiments, we decided to activate the tailings by calcination with alkali and made an all-round analysis on the tailings before and after activation with X-ray diffraction, infrared spectroscopy and scanning electron microscope. Then, experimental factors and performance of preparation of inorganic mineral polymers with tailings were studied in orthogonal test and single factor test. The properties of geopolymer and the differences between the two were investigated. Finally, great attention was devoted to the investigation of preparation and properties of foamed geopolymer..Based on the above experiments, we draw the conclusions:(1) activation by calcination with alkali can improve the activity of tailings; the compressive strength of thegeopolymer made of activated tailings is stronger and the performance of this material is improved in every aspect. (2) based on mechanical properties, the order of influences (in declining trend) of the factors on geopolymer is:proportion of tailings in solid powder> liquid-solid ratio> modulus of alkali-activator> added quantity of water glass (in Na2O). (3) the optimum value of each factor is:addition of tailings 20%, modulus of water glass 1.2, proportion of water glass (in Na2O) 5%, liquid-solid ratio 0.55. (4) a contrastive experimental analysis on the properties of geopolymer made of tailings and that of ordinary Portland cement was conducted. The results indicate that in terms of mechanical property, freezing and thawing resistance, acid resistance, alkali-aggregate reaction and high temperature resistance, geopolymer made of tailings surpass ordinary Portland cement. (5) based on a lot of preliminary experiments, hydrogen peroxide and stearic acid were chosen as foaming agent and foaming stabilizer of foaming materials. The results show: optimum proportion of hydrogen peroxide is 0.5%, optimum proportion of stearic acid is 1%. (6) heat conductivity coefficients of foamed materials reached 0.0511w/(m·k) and 0.0524 w/(m·k) respectively.This paper is innovative in the following aspects:(1)The use of iron ore tailings and lead-zinc tailings as raw materials to produce geopolymer for realization of effective and comprehensive utilization of mineral resources.(2)Mechanism of polymerization of geopolymer.(3)the combination of preparation of foaming materials and production of geopolymer.Results of the aforesaid research suggest that those two types of tailings can be used to produce geopolymer and that through the control of experimental factors, products with improved performance could be produced. The combination of the reutilization of tailings and the great properties of geopolymer not only addresses environmental pollution and waste of resources, but diversifies the usage of geopolymer materials and turns tailings into a resource.