Modification Research On Semi-dry Method Desulfurization Ash

The calcined oxidative desulfurization technology is widely spread due to its properties of less investment and smaller occupation. However, the calcium sulfite attachment hardly can be used efficiently and causes waste of resources and environmental pollution. It will make great contribution to the society and economics to improve the performance of desulfurization ash and get lots of high added value desulfurization ash.Based on study of the physical and chemical properties of desulfurization ash, a new method to modify gypsum based self-leveling material with the calcination oxidative desulfurization ash was put forward. The influences of addition method, addition contents of modifiers and calcination temperatures were studied with orthogonal methody. Results showed that the modified desulfurization ash gypsum gelling material prepared with the mixture of desulfurization ash and modifiers was the best, and the 28 days compressive strength reached 16.98 MPa. Ca(OH)2 and sulfate promoted the activity of coal ash efficiently, and enhanced the strength of gypsum based self-leveling material. The influences on the gypsum based self-leveling material strength of the addition contents of water-retaining agent, water reducer and defoamer were also studied based on a brilliant ratio of raw materials. Results showed that gypsum based self-leveling material matched the standard request of the <JCT/1023-2007 gypsum based self-leveling material> was prepared successfully with 46% modified desulfurization ash gypsum gelling material, 15% concrete, 15% sulphate aluminium cement, 20% fine sand, 4% semi-hydrated Gypsum and 0.1% super absorbent polymers, 6% compound water reducing agent and 0.05% defoamer, which performed better stable properties.A new method was put forward to oxidate modification desulfurization ash and prepare α-half water gypsum desulfurization ash in the brine solution in the ordinary pressure. It could be divided into two processes of calcium sulfite oxidation and dihydrate gypsum transition to α-hemihydrate gypsum in the mixture of Ca Cl2 and Mg Cl2 solution. The influences of Zn Cl2, citric acid and p H of procedure was also studied. Results showed that when the Zn Cl2 content was 1×10-3mol/L, p H was 5 and citric acid content was 0.02%, the shape of α-hemihydrate gypsum samples was short rod-like, uniform particle size and the draw ratio was 1.5:1~3:1, and the time of oxidation process shortened to 7.5h. Besides, the 2h fracture resistance strength and compressive strength of the α-hemihydrate gypsum samples were 3.52 MPa and 15.86 MPa respactively, which were 2.9 times and 4.3 times compared to the ordinary building half water gypsum.