Experimental Study On The Desulphurization Characteristics Of The Alkaliferous Industry Wastes

At present, coal-burning thermal power generation has a dominant position in the electric power industry because coal is the main and primary energy sources in our country. Hence, coal combustion has always been a main contributor to our national environmental pollution, and emission controlling of the sulfur oxides is an important item to cure the increasing pollution. With the development of the Chinese industry, economy and society, a mass of industry wastes had been exhausted. The industry wastes had not only occupied space but also polluted environment. Base on the industry application aim, the desulphurization abilities of the alkaliferous industry wastes were studied in the different temperature characteristics in this thesis.Several kinds of the alkaliferous industry wastes such as alkali slag, salt slurry, white clay, carbide slag and solid waste in water treatment of the chemical industry; smelting iron slag, red mud and magnesium dross of the metallurgy industry; fly ash and coal-burning slag of the electric power industry were selected which all came from Shandong province. The limestone and the magnesite were selected to be the contrast material. This article experiments unified the different temperature characteristics to study desulphurization abilities of experimental materials. The surface area and the hole structure analyzer, the XRD diffraction technology and the thermogravimetry analytic method were used to research the desulphurization mechanisms of the experimental materials.First, ask for the sulfur capacities method, experimental material desulphurization abilities were tested and selected in 800℃. The results show that: the desulphurization abilities of salt slurry, alkali slag, red mud, white clay and carbide slag, solid waste in water treatment were better than limestone. The desulphurization abilities of smelting iron slag, magnesium dross, fly ash and coal-burning slag were worse.The sulfur capture characteristics and the temperature characteristics of the selected alkaliferous industry wastes were studied in 800-1100℃. The results show that: the sulfur capacities of alkali slag, salt slurry and red mud were strong in 800～850℃. In the high temperature the sulfur capacities were loss because of nodulize. The sulfur capture abilities of white clay and carbide slag are better than other experimental materials. The sulfur capture ability of solid waste in water treatment is almost not influenced by temperature. The influence of the coal-burning sulfur emission characteristics by experimental wasters was studied. The results show that: red mud, alkali slag and salt slurry could effectual capture the release of sulfur at first stage. But in 1000℃ their sulfur capture abilities depress. White clay and carbide slag could effectual capture the release of sulfur in 800-1000℃ .In order to analyse the desulphurization mechanism of the experimental wasters, based on the method of XRD the sulfation products in 800℃ and 1100℃ were researched. In 800℃ the mostly sulfation product is CaSO₄. That shows the Ca-based material take part in the desulfurating reaction. The sulfation product of alkali slag and salt slurry include MgSO₄. That shows the Mg-based materials take part in the desulfurating reaction. In 1100℃ the mostly sulfation product is Ca₃Al₆O₁₂·CaSO₄, Ca₅(SiO₄)₂SO₄ and little CaSO₄. That shows CaSO₄ react with monox and aluminium oxide. Based on the method of nitrogen adsorption, pore-structure of the experimental wastes were researched. The result shows that: the specific surface area, specific pore volume and total porosity of experimental wastes are higher than that of the experimental limestone except smelting iron slag. This makes the sulfation reaction goes further.Secondly, the desulphurization characteristics of the alkaliferous industry wastes were studied in 400～800℃. The results show that: the sulfur capacities of all the experimental wastes increase with higher temperature. Salt slurry, alkali slag and red mud have good sulfur capture abilities in this temperature section. Based on the method of XRD the sulfation products in 500℃ and 800℃ were researched. The results show that: the sulfation products of white clay, carbide slag and limestone include many CaCO₃ that shows the carbonization reaction is very serious in 500℃. The Ca-based materials taking part in the desulfurating reaction reduce. The Mg-based material of alkali slag and salt slurry take part in the desulfurating reaction in 800℃. Based on the thermogravimetry, the sulfation products of the experimental wastes were researched. The carbonization reactions of limestone, white clay and carbide slag were large. While the desulfurating reactions of alkali slag, salt slurry, red mud and solid waste in water treatment are almost not affected by carbonization reactions. The magnesit taking part in the desulfurating reaction were less in 500～600℃. Most of MgO react with SO₂ above 700℃ .Lastly, based on the iodometric method, the desulphurization abilities of the experimental alkaliferous industry wastes were studied in the wet simulation flue gas desulfurization. In the experimental condition, the desulphurization ability of magnesite is the best. The following is carbide slag, limestone, white clay, magnesium dross, salt slurry, red mud and alkali slag. The desulphurization abilities of fly ash, coal-burning slag, smelting iron slag and solid waste in water treatment are bad. Based on the method of XRD the solid sulfation products of experimental materials were researched. The results show that: the main solid sulfation products of white clay, limestone, carbide slag, alkali slag, magnesium dross, red mud and salt slurry are CaSO₄, hydration-CaSO₄ and hydration-CaSO₃. The main solid sulfation product of magnesite is hydration-MgSO₃ and hydration-MgSO₄.