Studies On The Release Of Sulfur And Desulfurization During Sintering Process Of Ash-shale Sintered Brick

Ash—Shale sintered brick is a new wall material by added certain amount shale fly ash through crushing, mixing, shaping and roasting. This products which mainly materials are fly ash and shale are widely used in business because its good economic returns, energy saving and environmental protection features. However, compared to ordinary clay fired brick in terms of environmental efficiency, it still has some environmental problems, the most obvious of which is sulfur dioxide pollution. This subject adopts sulfur-fixed methods in bricks, so as to reduce sulfur dioxide emissions in the process of ash-shale sintered brick..In this dissertation, calcium-based desulfurization as the main sulfur agent , we studied a number of factors on its desulfurization rate, including the sintering time, sintering temperature, air flow, types of additives ect. Using the method of standard titrating potassium iodate solution. This experiment uses x-ray diffraction (XRD) technology to discuss the sulfur capture mechanism of composite sulfur capture agent. The major experiment results are as follows:(1). Total sulfur is 5mg/g when the ratio of fly ash and shale is 7:3. And optimal dosage of CaO is 0.3%. The desulfurization effect of calcium- based agent is efficacious when the temperature is below 900℃, but due to the decompose of calcium sulfate, it much poorer at high temperature.(2).The desulfurization effect is significantly affected by the temperature, time and air flow of sintering, the effect of desulfurization turns out worse at the higher temperature, longer time, faster air flow.(3). The desulfurization effect can be improved by annexing agent like SiO₂, Al₂O₃ and BaSO₄. The amount of them is 0.1%.(4). SiO₂ can form more Al - Si - O compounds; it can be wrapped in CaSO₄, reduce its decomposition rate and improve solid sulfur efficiency.(5). Al₂O₃ as calcium-base solid sulfur additive agent, because in high temperature conditions, it can be reacted with CaO, CaSO₄, and generated 3CaO·3Al₂O₃·CaSO₄, it also can reduce calcium sulfate decomposition, increase sulfur rate.(6). The desulfurization mechanisms of barium nitrate are as follows according to XRD analysis: firstly, barium nitrate and SO₃ reacts as a substance surviving in high temperature, barium sulfate. Secondly ,the additive barium sulfate impels the row material to produce Ba-Al-Si-O ,a new kind of stable compound in high temperature which wraps up calcium sulfate or becomes an append age to it, holding back or even preventing the decomposition of it, thereby improving the desulfurization efficiency of CaO.