Research On The Foaming Phenomenon In Blast Furnace Process Treating Vanadium Titanium Magnetite

As one of the three biggest major iron ore production base in China, Panxi region possesses more than 95% of the total vanadium titanium magnetite reserves resources. Due to the complexity of the ore itself, it has experienced a long and tortuous process for Panzhihua Iron and Steel Corporation to realize comprehensive utilization of this ore by employing blast furnace-converter process. To ensure the blast furnace process successfully with better various index, about 35% of full vanadium titanium magnetite was substituted by ordinary ore addition to reduce the content of Ti O2 in slag. However, the addition of ordinary ore will cause a decline of vanadium content in molten iron. Moreover, the difficulty in source of ordinary ore will increase the cost, which is not a permanent solution for efficient and comprehensive utilization of the resources and for the promotion of the competence of enterprises in the current situation. Therefore, under the premise of maintaining the existing blast furnace smelting index, it is of vital significance to continue to improve the ratio of vanadium titanium magnetite, even to achieve full vanadium titanium magnetite smelting again. Nevertheless, implementation of smelting with high vanadium titanium ore proportion or full vanadium titanium magnetite smelting will lead to the increase of Ti O2 content in slag by more than 25% or 30% or so, thus generating serious problem of foaming in the furnace. In order to solve this problem, based on the analysis of a large number of previous studies, the cold experimental simulation combined with a high temperature experiment method was adopted here to investigate the foaming problem in the blast furnace smelting process of vanadium titanium magnetite. From the experimental results, the following conclusions were drawn:① Under the condition of external gas source, the variation of foaming with viscosity is not monotonous, namely, the lower viscosity has a promotion on foaming phenomenon, while higher viscosity will inhibit this phenomenon. With increasing the solid particle content, the foam height presents a trend which increases firstly and then decreases, that is to say, with the increase of particle concentration, the foaming phenomenon was strengthened firstly and then weakened.② Under the condition of endogenous gas source, with increasing the viscosity of the solution, the foam height is gradually reduced. Bigger viscosity will give rise to more difficulty in eliminating foaming and longer time for defoaming. However, The influence of solid particle content on foaming exhibits a similar pattern with that observed under the condition of external gas source.③ The influences of the size, shape and wettability of the solid particles on foaming are summarized as follows: smaller particle size brings about a stronger promotion on foaming. Compared to spherical and elliptic spherical particles, rodlike and strip-type solid particles make it more easier to restrain foaming phenomenon. In addition, particles with better wettability can enhance the foaming phenomenon of the solution. At the same time, both of the gas generation rate and air volume will have an impact on the foaming phenomenon, the greater the amount of gas bubble level, the more serious foaming phenomenon will be. Faster gas superficial velocity for foam formation leads to the foaming in the furnace more likely to happen quickly in a short time and continue to strengthen gradually, but the lifetime of the foam is relatively the short.④ Under the condition of high temperature, both of the slag basicity and Ti O2 content in slag will affect the foaming phenomenon. When the Ti O2 content in slag is 15%, 20% and 25% respectively, the variation of slag foaming is not obvious. When Ti O2 content increased to 30% and 35%, a more notable change of slag foaming will be observed than that under lower Ti O2 content, but the overall change is smaller.⑤ According to the results from the influence of slag basicity and Ti O2 content in slag on foaming, in contrast to slag basicity, the effect of Ti O2 content in slag can be ignored. With increasing of slag basicity, the foaming in the furnace is gradually enhanced. When the slag basicity is 0.95 and 1.15, the relationship between the slag electric current and the reaction time basically meets the law of general polynomial. When the slag basicity increases to 1.35, the relationship between the current and reaction time is complicated, the changes mainly lie in the longer lifetime of foaming. The whole foaming process can be obviously divided into blistering, persistent and defoaming stage, the largest foam height decreases, etc.⑥ Efforts can be devoted from two aspects for the aim of suppressing or eliminating foaming phenomenon in the furnace. For slag composition concerns, on the one hand, ensure lower alkalinity of the smelting. On the other hand, reduce the content of titanium content in the treatment process ahead of the ore charging. In the respect of smelting condition, for one thing, promote the reduction of iron in the top of blast furnace to reduce Fe O content in primary slag, simultaneously, control the gas production between slag-coke and slag-hot metal. For another, adopt appropriate methods to promote the transformation of slag-particles, hot metal–particles from wetting to non-wetting.