Ferrovanadium production from heavy fuel oil fly ash and BOF dust

Ferrovanadium production from heavy fuel oil fly ash and BOF dust

Lai, A.

Yang, Y. (mentor)
Xiao, Y. (mentor)

Civil Engineering and Geosciences

Section Resource Engineering

2010-06-25

Vanadium is an important industrial metal that is mostly used as an alloying element in steel and to a lesser extent in titanium. It is generally produced in combination with other metals such as iron, titanium, and uranium. The typical production method begins with salt roasting of the ore or concentrate to produce a water soluble form of vanadium. Then the vanadium is leached, purified and precipitated as vanadium pentoxide. Most of the vanadium pentoxide produced is then combined with iron to create a ferrovandium alloy, via aluminothermic reduction, that is suitable for the iron and steel industry for alloying. Vanadium is also found in crude oil in a range that can vary from 10 to 1400ppm depending on the location. As the oil is processed and refined the vanadium becomes enriched. Specifically it is enriched in the fly ash of heavy fuel oil power plants. While the original concentration of vanadium in oil is very small the amount of oil extracted from the earth is very large and this makes fly ash a significant source of vanadium. The vanadium that is contained in the heavy oil fly ash can be recovered by two general methods: hydrometallurgical and pyrometallurgical. The hydrometallurgical route usually involves leaching, purification, and precipitation to produce V2O5. This V2O5 can then be used to produce ferrovanadium. The developmental pyrometallurgical route directly uses the fly ash in combination with a reductant (C, Al, or Si) and a source of iron to produce a ferrovanadium alloy. This thesis investigates one pyrometallurgical method, which uses two industrial waste products, heavy fuel oil fly ash and basic oxygen furnace dust, to produce a ferrovanadium alloy. The carbon contained within the fly ash is used as the reductant so only fluxing agents must be added to the charge. The result is a very efficient process that requires very few virgin raw materials. The results show that a ferrovanadium alloy with 15% vanadium can be produced by high temperature smelting of heavy oil fly ash and basic oxygen furnace dust. There are some impurities that remain in the metal, mainly nickel (~4%), sulfur (~5%), and carbon (~1.5%). The carbon to metal ratio had the largest effect on the final metal quality. The slag quality is also important to the final quality but more work must be done in this area. Simple water leaching tests were done on the as-received fly ash and the slag produced from smelting. The leach solution produced from the slag contained 100 times less metals than the solution produced from the as-received fly ash.

ferrovanadium
heavy fuel oil fly ash
BOF dust
recycling

http://resolver.tudelft.nl/uuid:d09a3aa8-93b4-46e9-af3b-eac8701badf3

Student theses

master thesis

(c) 2010 Lai, A.