Treatment and Recycling of Steelmaking Slags and Dusts by Microwave Heat

1995年，进行了一些初步试验。研究了CaO、SiO_2、Al_2O_3、FeO、Fe_2O_3等氧化物在微波（2.45GHz, 500W）照射下的温度行为。在建立了1.6kW微波处理装置后，对合成的炼钢渣（CaO-SiO_2-Fe_tO体系）进行了微波处理，研究了炉渣组成对焙烧效果的影响。加热速率强烈依赖于Fe^<3+>/Fe^<2+>的比值，CaFe_3O_5的存在似乎是加热机理的关键，并且发现其具有较高的介电损耗。1996年，研究了微波辐照下与碳共存的炼钢渣的铁和磷的行为以及温度变化。本实验的目的是阐明从炼钢渣和粉尘中提取铁和磷等资源的可能性，这些资源很少作为有益材料回收利用。在4 ~ 6 min内升温至1700℃，升温速率随碳加入量的增加而增大。形成铁碳熔体，回收炉渣中90%以上的铁。当碳当量（我们定义为通过一氧化碳的形成将炉渣中的氧化铁还原为纯铁所需的碳的分数）大于1时，炉渣中50-60%的磷被带入金属相，约20%可能消失在气相中。结果表明，利用微波辐照法可以有效地加热与碳共存的炼钢渣，并可回收铁和磷。提出了一种有效的炼钢炉渣和炉灰回收利用新工艺。

In 1995, some preliminary experiments were carried out. Temperature behaviors of some oxides, such as CaO,SiO_2, Al_2O_3, FeO,Fe_2O_3, with microwave (2.45GHz, 500W) irradiation were investigated. After a new apparatus for 1.6kW microwave was built up, synthesized steelmaking slags (CaO-SiO_2-Fe_tO system) were exposed to microwave and the effect of slag composition was investigated. The heating rate was strongly dependent on Fe^<3+>/Fe^<2+> ratio and the existence of CaFe_3O_5 seemed to be the key of the heating mechanism, which was also found to have high dielectric lossesIn 1996, the behaviors of iron and phosphorus of the steelmaking slags coexisting with carbon under microwave irradiation as well as temperature change have been investigated. The aim of this experiment is to clarify the possibility of extracting some resources such as iron and phosphours from steelmaking slags and dust, which are seldom recycled as beneficial materials. Temperature was raised up to 1700ﾟC in 4-6 min. and the heating rate was shown to increase with increasing amount of carbon mixed with the slags. Iron-carbon melts were formed and more than 90% of iron in the slags were recovered. When the carbon equivalent which we defined as the fractional amount of carbon required for the reduction of iron oxide in the slags to pure iron with the formation of carbon monoxide is more than unity, 50-60% of phosphorus in the slags was brought into the metal phase and about 20% disappeared probably into gas phase.Accordingly, steelmaking slags coexisting with carbon were found to heat up effectively by means of microwave irradiation, and iron and phosphorus could be recovered from the slags. This new process is proposed as an effective one for recycling steelmaking slags and dust.