Influence of hot air sintering on dioxin emission

Sintering pot tests with hot air were conducted. Air recovery from exhaust gas from the sintering plant. The effects was heated by using a resistance furnace to simulate heat of the process parameters, such as temperature of hot air, oxygen enrichment, coke consumption and bed depth, on quality of products, energy consumption and dioxin emission were investigated. Good results were obtained under the following conditions ： 200℃ hot air, no oxygen enrichment, lime with high CaO, thinner bed and addition of accelerant.

Gas-particle partitioning of polychlorinated dibenzo-p-dioxins and dibenzofurans in the sintering process

The distribution of seventeen gaseous and particle-bound 2,3,7,8-substituted chlorinated PCDD/Fs in the flue gas of different windboxes of the sintering machine was analyzed. The influence of temperature change on the PCDD/Fs emission from the sintering process and the formation mechanism of PCDD/Fs were discussed. The result has shown that among the seventeen gaseous and particle-bound PCDD/Fs in the flue gas of different windboxes, furans occupied the major place. The proportion of the gaseous PCDD/Fs in most windboxes is from 40% to 60%. The change tendencies of the concentration of both the gaseous and particle-bound PCDD/Fs were similar, with a higher level at the end of the sintering bed. The PCDD/Fs concentration＇ s change tendency in the windbox was very consistent with the change of temperature of the flue gas in the windboxes. More than 60% PCDD/Fs of the total PCDD/Fs emission amount was emitted at the end of the sintering bed. Only this part of the waste gas accounted for 12% of the total waste gas volume.

Influence of oxygen-rich hot air composite gas medium on sintering performance and function mechanism

Hot air sintering technology is used to improve the quality and production efficiency of sintered ore.However,the current thick layer condition highlights the disadvantage of the low oxygen potential of the hot air sintering layer.Therefore,it is considered to use oxygen enrichment sintering to improve the environment of hot air sintering.Traditional sintering,hot air sintering,and oxygen-rich hot air sintering were compared through sintering cup experiments,and the influence of hot air and oxygen-rich hot air on sintering indexes was clarified.Hot air reduced the vertical sintering velocity,while improved the yield and tumbler index.Oxygen-rich hot air sintering contributed to improving the vertical sintering velocity while ensuring the quality of sintered ore,thus comprehensively improving production efficiency.Under the action of hot air,the highest temperature of the sintering layer increased and the high-temperature holding time was prolonged.After oxygen enrichment,the combustion efficiency of fuels in the upper layer of materials was promoted,which optimized heat distribution in the middle and lower layers of materials and increased the content of calcium ferrite in the sintered ore,thus strengthening the sintering process.

热风烧结对二噁英生成的影响研究

二噁英类物质是目前已知的化合物中毒性最大的物质之一,主要来源于固体废物的燃烧过程和含氯工业产品的生产过程。本文利用烧结杯中试装置模拟热风烧结过程,研究了烧结料中焦粉含量、烧结热风温度和热风含氧量三个因素对二噁英生成的影响,利用高分辨色谱/高分辨质谱(HRGC/HRMS)测定气相以及飞灰中的二噁英。试验结果显示,二噁英生成量随焦粉含量减少而增加;随热风温度和含氧量的升高,二噁英生成量先增加后减少。在本试验条件下,减焦10%、200℃热风、含氧量19%时,二噁英生成量最小。

烧结过程二噁英的生成机理与减排途径

烧结过程二噁英形成方式以“从头合成”为主，其主要生成区域位于干燥预热带（200～450℃），其同系物中以PCDFs为主，PeCDFs和HxCDFs分布比例较高。烧结过程二噁英的减排方法主要分为源头控制、过程控制和末端治理三种。源头控制和末端治理容易受到原料和成本的制约，而过程控制具有良好的减排效果，尤其是在烧结过程中添加以尿素为代表的含氮抑制剂的减排效果最为明显。该工艺具有成本低、效果好、工艺简单和多种污染物可协同减排等优点，是未来烧结过程二噁英减排及烟气综合治理技术的发展方向。