Influence Study Of Material Characteristics Of Iron Tailings On Preparing The Aerated Concrete

The discharge of iron tailings is huge in China. It has long been in the tailings stacking way, but the utilization rate is not high. Low-poor iron tailings has the characteristic of complicated chemical composition and mineral composition, fine disseminated extent, clay. But most has the high silicon content to be helpful for the comprehensive utilization. Aerated concrete has the characteristic of large tailings utilization, saving energy and reducing consumption, heat preservation and heat insulation, light earthquake, and etc. It is a new way opened for the comprehensive utilization of iron tailings that iron tailings is prepared for aerated concrete block, which can make use of huge tailings, reduce costs, save land resource and reduce environment pollution.Based on low-lean vanadium and titanium iron tailings from JinSheng company of HeBei PingQuan as raw material, the technology of aerated concrete block was developed. The silica content of iron tailings was 52.59%, and the proportion of-0.074 mm was 13.21%. The experimental materials was analyzed, including chemical composition, mineral composition, granularity composition ananlysis and other related performance index analysis in this paper. Finally, the technology parameters of the preparation of aerated concrete used by low lean vanadium and titanium iron tailings was determined: 65% iron tailings content,-0.074 mm particle size of iron tailings for 93.43%,-0.074 mm particle size of river sand for 96.66%, iron tailings and river sand mixing ratio of 45% and 20%, 0.09%Al, water to material 0.06, lime and cement dosage was 19% and 14%, respectively, gypsum dosage was 2%. The compressive strength and dry bulk density of aerated concrete block prepared was 3.52 MPa and 620.8 kg/m3. The main indeses of products was slightly more than the national standard autoclaved aerated concrete block(GB/T11968-2006) of A3.5B06 grade qualification requirements. The influence of material properties, such as silica content, material particle size, mix proportion on aerated concrete was studied. The aerated concrete was prepared by iron tailings without river sand and iron tailings with 20% river sand. The reasons of the differences of the two through microcosmic analysis: SiO2 content of iron tailings without river sand was relatively small, which led to very little amount of tobermorite and bad crystallinity in autoclaved curing conditions. Instead, aerated concrete joinning river sand had a lot of good crystallinity of tobermorite.The compressive strength, dry density, the vibration of the functional group, microstructure, phase transformation process of aerated concrete block was tested by X-ray diffraction, Fourier transform infrared spectroscopy, Thermogravimetric and Differential scanning calorimeter, scanning electron microscope and other modern analysis test method. It was shown that under atmospheric pressure, the iron tailings was a kind of inertia industrial waste residue, and only a small amount of active component in iron tailings participated in the chemical reaction, and small amounts of the hydrated calcium silicategel and ettringite arised in the hardened body. Under the autoclaved curing condition, the activity of iron tailings can show the good. Active SiO2, active Al2O3 and mixture of Ca(OH)2 took place chemical reaction to generate tobermotite, a good dense mesh structure formed by hydration products of crystal cluster fit and aggregate together, had positive effect to improve the strength of the products.