镁硅质防粘渣涂料的防粘渣试验及其应用

Anti-adhesion test and its application of magnesia-silica based slag-adhesion resistant coating mix

为了验证以菱镁矿、石英、黏土、氧化铬微粉及磷酸盐为原料制成的镁硅质防粘渣涂料的防粘渣性能,采用静态坩埚法(1 600℃3 h,空气气氛)对比研究了转炉钢包渣线用普通镁碳砖和VOD钢包渣线用低碳镁碳砖在涂覆该涂料前后的防粘渣性能,分析了试验后涂料的显微结构,探讨了涂料的防粘渣机制,并在宝钢进行了实际使用试验。结果表明:防粘渣涂料在熔渣与镁碳砖之间形成了明显的隔离层,起到了较好的防粘渣作用。这是由于,防粘渣涂料在1 600℃的平衡物相为MgO、M2S及MA与MK的固溶体,无液相出现,隔离了镁碳砖与熔渣的接触,不易被钢渣溶解,也不与镁碳砖发生烧结反应,还在一定程度上保护炭素不被氧化,加之其较大的体积收缩和排气反应,使其容易与粘附在其表面的熔渣一起脱落,从而起到防粘渣的作用。实际使用表明,该涂料大大减轻了钢包的粘渣程度,并延长了渣线和包口镁碳砖的使用寿命,得到了钢厂的认可。

In order to verify the slag-adhesion resistance of a coating mix prepared using magnesite,quartz,clay,chrome oxide,and phosphate as starting materials,slag-adhesion resistance of normal MgO-C bricks used in slag line of converter ladle and low carbon MgO-C bricks used in slag line of VOD ladle before and after painting the coating mix were compared using static crucible method（1 600 ℃ 3 h,in air）.The microstructure of the residual coating mix after the test was analyzed and its anti-slag-adhesion mechanism was discussed.A field test about the coating mix was also carried out at Baosteel.The results show that the coating mix forms an obvious separating layer between the molten slag and the MgO-C bricks,making a good slag-adhesion resistance.It is because the coating mix is finally converted to the equilibrium phase composed by MgO,M2S and a solid solution of MA and MK without liquid phase at 1 600 ℃,which separates the molten slag and the MgO-C bricks and is difficult to dissolve by the molten slag or react with MgO-C bricks.The coating mix can also protect the carbon in MgO-C bricks from oxidation to a certain extent and can easily spall with the steel slag from MgO-C bricks at high temperatures due to large volume shrinkage and gas releasing.The field test shows that the coating mix reduces the slag adhesion degree and prolongs the service life of MgO-C bricks for slag line and ladle mouth.