Dissertation > Environmental science, safety science > Processing and comprehensive utilization of waste > General issues > Solid waste disposal and utilization

Experimental Study on Resource Utilization of Ash

Author ZhouWanZuo
Tutor ShiZhengLun;LuoZhongZuo
School Zhejiang University
Course Engineering Thermophysics
Keywords Vanadium residue Gasification ash Raw material formulations Cement clinker Cement admixture Utilization
CLC X705
Type Master's thesis
Year 2010
Downloads 167
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Coal resources as the main body of China's energy consumption structure, centralized distribution, north little more south, and the high ash content, which leads to a large number of ash emissions. Our coal resources are relatively poor southern regions, but with a more extensive low-carbon low-calorific stone coal resources. But no matter what kind of technology, vanadium extraction will generate a huge amount of residue after most of the ash pile field, both to occupy the land, but also pollute the environment. On the one hand, in cement production, silicon aluminum material commonly used clay, but clay higher activation energy, resulting in high energy consumption of cement production and mining damage vegetation, destroying farmland, resulting in many developed countries have banned the use of clay firing cement . On the other hand, cement production can consume a large amount of ash, therefore, ash used in cement production can not only save resources, but also to improve environmental conditions, which is consistent with sustainable development strategic thinking. In order to avoid the traditional presence of vanadium extraction process vanadium recovery rate is low, pollute the environment, small-scale problems, we use calcium circulating fluidized bed roasting processes to calcium-based raw materials for the feed additive Dunhuang stone coal ball for the roasting raw materials, In the heat input power of 1MW circulating fluidized bed combustor test rig pellet containing vanadium from stone coal vanadium circulating fluidized bed roasting pilot study on the combustion characteristics and ash ash vanadium leaching characteristics were analyzed. Experimental results show that the circulating fluidized bed stone coal vanadium minerals have good oxidation roasting: calcined product with fly ash, accounting for about 70% and V2O5 content was 1.38%, compared with stone coal increased 23.2% as ; the liquid-solid ratio 2, 15% sulfuric acid concentration, leaching temperature of 90 ℃ under the conditions of the V205 ash leaching rate of close to 70%. It is foreseeable that in Dunhuang stone coal pellet fired circulating fluidized bed boiler actual oxidation effect will be better to make ash leaching rate of vanadium further improved. Residue on vanadium and gasification ash for physicochemical characterization. Analysis showed that vanadium gasification ash residues and the chemical composition and mineral composition are associated with cement production clayey material very similar, and contains a lot of oxygen-rich minerals and trace elements, activity is very good, the ingredients can be used as a raw material promote the clinker burning; used as cement admixture, but also conducive to the cement hydration effect on the compressive and flexural strength is improved greatly. In addition, the gasification fly ash carbon content 29.53%, the heat can reach 8967kJ/kg, can be used as low-quality coal to provide heat, shaft kiln cement batching applications, to achieve the purpose of saving energy. Reference NSP kiln cement calcining process, the intermediate acid leaching of vanadium salt method residue raw material formulation design, descending trial and error method formulated 15 raw material formulations, and then were at 1250 ℃, 1300 ℃, 1350 ℃, 1400 ℃ and 1450 ℃ five temperature calcination. By clinker free lime, XRD, SEM scanning electron microscopy analysis and static analysis of plasma compression test and compare with the clinker plant, you can see the residue of vanadium and vanadium-containing stone coal ash as a cement raw material , clinker burning temperature decreases 50 ℃, reducing calcination time, reduce cement burning energy consumption and improve raw material easy to burn, improve clinker quality, so the use of vanadium and vanadium-containing residues stone coal ash calcined cement raw material preparation Clinker is completely feasible and meaningful. Reference kiln cement calcining process of ash agglomerating gasifier fly ash for cement raw material for formulations. Clinker ratio setting value KH = 0.93 ~ 0.95, SM = 1.8 ~ 2.2, IM = 1.1 ~ 1.5, according to the different proportions of fly ash and anthracite to different fly ash replacement rate behalf of clay, in accordance with the method of solving equations formulated 91 raw material formulations, which indicates that the gasification ash rate in a certain range of values ??for raw material preparation process kiln cement clinker raw material, and can greatly reduce the outside with anthracite, to save energy. The intermediate acid leaching of vanadium salt residue method for mixed material were studied. Respectively 10%, 15%, 25%, 30%, 35%, 40% and 45% of the mass ratio of the vanadium slag residues and plant stone separately doped single blending of different ingredients of the cement test samples physical examination, the results showed that: the residue of the active vanadium good cement admixture material, whether alone or mixed with cement and cinder doped stone, cement stability, setting time and other performance indicators are in line with composite portland cement requirements, intensity strength requirements to meet the 32.5 grade cement, cement performance indicators all meet GB175-2007 requirements. And vanadium residue 28d compressive and flexural strength are much higher than the cinder cement stone, it may become a special cement admixture products sold, which will greatly enhance their social status, to dramatically improve stone coal polygeneration utilization of the economic and environmental benefits. For the secondary firing residue admixture were studied. Respectively 10%, 20%, 30% and 40% of the mass ratio of the vanadium and plant stone coal residue 2 were blended for single doped for different ingredients of the cement test samples for physical testing, were found to cement strength strength grade cement 32.5R meet the requirements of cement performance indicators all meet GB175-2007 requirements. R28 determination that it is a good cement admixture active material. When the residue was mixed with 40% by volume, the residue applied gypsum plaster composition is sufficient to substitute, and the residue was not fully utilized, will also reduce the cost of cement plaster. Finally, the ash agglomerating gasifier slag by circulating fluidized bed boiler bottom ash after burning for mixed materials were studied. Respectively 10%, 15%, 25%, 30%, 35%, 40% and 45% of the mass ratio, the bottom ash and site 2 are for single stone coal blended doped for different ingredients of the cement test samples Physical examination revealed its flexural and compressive strength grade cement 32.5R at least meet the strength requirements, the vast majority have reached grade 42.5R cement strength requirements. R28 The tests showed that bottom ash is a good cement admixture active material.

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