【作者】 张汉泉；

【导师】 朱德庆；

【作者基本信息】 中南大学 ， 矿物加工工程， 2001， 硕士

【摘要】 随着我国高炉炼铁技术的不断进步，要求入炉矿品位升高，冶炼渣量减少，焦比下降，喷煤比增加，相应对入炉精料的要求越来越高。而随着烧结矿品位升高和SiO₂含量降低，烧结矿强度将下降。为保证烧结矿的质量，必须生产高碱度甚至超高碱度烧结矿。但对于我国大多数钢铁厂而言，烧结矿占入炉矿石的80％以上，由于酸性炉料供应短缺，入炉熟料比高，反过来使烧结矿碱度限制在1.6-1.8范围内。对于铁品位为58～62％、SiO₂含量4.0～4～4.5％、碱度为1.6～1.8的烧结矿，提高其产质量存在很大难度。 在当进口矿粉约为43％、国内矿粉约为22％、国产精矿22～25％、混合料水分为6.5％、焦粉配比为5.5％、碱度在1.8倍条件下，制备TFe含量为58～62％、SiO₂含量为4.1～4.5％的高铁低硅烧结矿，采用常规烧结工艺，烧结杯试验取得如下指标：烧结矿转鼓强度为60.53％，利用系数为1.894t·m^-2·h^-h，成品率为79.82％，固体燃耗为54.07kg·t^-1，FeO含量为8.99％。，而且结果表明，随着含铁品位的升高、SiO₂含量的降低，烧结矿强度下降，利用系数降低，烧结矿产质量明显下降，无法实现现代高炉冶炼的要求。为此，必须开发适合我国原料条件的烧结新工艺、新技术。 本文对一种新的分流制粒烧结工艺进行了研究，即将含铁精矿和粉矿分别制粒，形成低碱度内核、高碱度外壳的准颗粒进行烧结。通过考查分流制粒时间、水分分加、燃料分加等多种措施及相应工艺参数对烧结矿产质量的影响，试验结果表明，采用分流制粒工艺后，烧结混合料中细颗粒比常规工艺明显减少（-3mm粒级含量由48％减少32％），中间粒级明显增多，准颗粒的加权调和平均粒径增大，混合科层气体阻力减小，烧结过程透气性得到改善。分流制粒工艺强化烧结取得如下指标：烧结矿转鼓强度达到65～70％，利用系数在1.9t·m^-2·h^-1以上，成品率在82～85％，固体燃耗为51～52kg·t^-1，FeO含量在7.2～8.8％。与常规烧结试验相比，烧结矿转鼓强度可提高近10个百分点，利用系数和成品率也有所上升，固体燃耗下降了3.6～4.8％，而烧结矿中FeO含量明显降低，烧结矿产质量得到改善。 运用烧结过程气体力学、液相形成热力学和动力学及成矿机理对分流制粒强化烧结的机理进行了研究。该工艺的的实质就是利用选定的高效制粒设备，对添加25％左右的高品位铁精矿粉内配一定量的生石灰做粘结剂（也是熔剂）进行强化分流制粒，制备出理想的准颗粒结构，使局部碱度达到3.0以上（烧结料的总碱度仍维持在1.8左右），以增强亲水性差的铁精矿的粘附性能，改善烧结料层透气性。通过熔剂和固体燃料分加技术，控制烧结温度和气氛，生成局部高碱度且残余赤铁矿比例高、具有高强度和高还原性、以针状铁酸钙为主要粘结相且伴有一定量的钙铁橄榄石的非均质烧结矿。由于高碱度部分CaO含量较高，生成的液相总的表面张力因子增加，故表面张力较大，且粘度较低，易于促使气孔由不规则大孔变为总体分布较为均匀且大小适中的规则球形，改善了烧结矿的还原性和强度，提高了烧结矿的成品率。为高炉提供铁品位为58.5％、SiO₂ 中力人学硕士学位论文 右晋学权优秀青年汰师基金汾助项目 含量4．5％、R为1．8、强度高、还原性好的烧结矿，为高炉精料、节约成本、改善环境 创造有利条件。更多还原

【Abstract】 Along with the progress of the ironmaking techniques by blast furnace in our country, high iron grade charges are loaded for the BF, resulting in the higher productivity and coal injection rate, lower coke ratio and BF slag. But with the increase in iron grade and the decrease of SiO2, the quality of the finished sinter including the mechanical strength, RDK RI will deteriate, which can be cured by the production of sinter at high or even super-high basicity. The basicity of sinter, however, has to be limited to the range from 1.6 to 1.8 in most ironmaking plants because of the shortage of acid charges in China. So it is difficult to improve the sinter quality and increase yield of sinter with 4.0-4.5% SiC>2 content at 1.6-1.8 basicity.The sinter containing 58~62% iron and 4.0~4.5% SiC>2 was produced by raw mixture consisting of 43% imported ore fines, 22% Chinese ore fines and 22~25% domestic concentrate. Under the conditions of granulating moisture 6.5%, coke rate 5.5% and the basicity l.8?the stumble index of the sinter was 60.53%,the productivity is l.894t -m"2 *h~’, the solid fuel exhaust was 54.07kg ?t"1, the FeO content was 8.99%, and the results of the conventional sintering process also indicates that with the increase of total iron content and the decrease of SiC>2 content, the mechanical strength and yield of sinter decreases, and can’t reach the demand of morden BF. So we have to develop new technique to meet with the development of our BF and to utilise raw material of our country.A new process-separated granulating sintering was developed in this article,-i.e..concentrate fine and ore fines are granulated respectively first and then mixted. The ideal pesaudo-grain with low basicity core and high basicity’ shell is formed. Many parameters such as separated granulating duration, moisture and proportioning ratio of burnt lime and basacity were researched to improve the granulation process and the correspondly separated of coke breeze was performed. It is shown that small size fraction in sintering blends is lowered by using this new technique, and the average size of blend is increased, the permeability of the sinter bed is improved. The result of this new process were as following: the stumble index of the sinter was 65~70%, the productivity is above 1.90 t -m"2 -h"1, the solid fuel exhaust was 51~52kg ?t"1, the FeO content was 8.2~8.8%. Compared with the conventional process, the stumble index of the sinter was increased by 10 percent, solid fuel exhaust was decreased by 3.6~4.8%, and the productivity of sinter is increased too. The FeO in the sinter was decreased obviously. The quality and the yield were greatly improved by this new technology.Pneumatics knetics of sintering process, thermodynamic and knetics of the formation of liquid phase and agglomeration mechanism were used to analysis mechanism of the new sintering technology. It is shown that the essence of this new technology is to granulate high iron grade concentrate separately by using high effective granulating equipment and producing ideal pesaude-grain. The adhering fines in shell of granulate is acid and the basicity of granulate core is beyond 3.0, In this way, the adhesive property of concentrate which has poor affinity to water will be enhanced, and the bed permeability is improved. Heterogeneous sinter with local high basicity and acicular calcium ferrite accompanied withsome kirschsteinite as its main binding phase and high primary hematite content is manufactured. With the increase of CaO content, the surface tension factor increases, so the surface tension is stronger, on the other hand, the apparent viscosity of melt is lowered, so the irregular pore in the sinter became regular spherical and well-distributed. The strength and the metallurgical properties of high iron grade and lower silica containing sinter were improved, the production yield rate was increased. So high quality sinter containing 58.5% iron and 4.5% SiO2 and R=1.8 could be supplied to the BF, the aim to cut the cost and protect of environment o更多还原