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，500 W）辐照下的温度行为。建立了一套1.6kW微波炉实验装置，对合成钢渣（CaO-SiO_2-Fe_tO系）进行了微波辐照实验，研究了炉渣成分对微波辐照效果的影响。1996年，我们研究了微波辐射下钢渣中铁、磷与碳共存时的行为及温度变化。本实验的目的是阐明从炼钢炉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物质回收。在4-6分钟内将温度升高到1700 ℃，并且显示加热速率随着与炉渣混合的碳量的增加而增加。形成铁碳熔体，渣中铁的回收率达90%以上。当碳当量大于1时，渣中50-60%的磷进入金属相，约20%的磷可能消失在气相中，因此，在还原过程中，渣中的铁氧化物被还原成纯铁所需的碳的分数为1。研究发现，利用微波辐射可以有效地加热与碳共存的炼钢炉渣，并可以从炉渣中回收铁和磷。该工艺是一种有效的钢渣、烟尘资源化新工艺。

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.