Continuous Expansion of GGBS Slag Grinding Plants
GGBS is now recognized worldwide as a green construction material capable of producing durable concrete structures. Apart from cost reduction the most important technical benefits, which GGBS imparts to concrete, include:
(a) Lower temperature rise in concrete, reducing the risk of thermal cracking in massive concrete structures.
(b) Elimination of the risk of damage caused by alkali-silica reaction (ASR).
(c) High resistance to chloride ingress, reducing the risk of reinforcement corrosion.
(d) High resistance to attacks by sulphate and other chemicals.
As reported, China's top 62 steel mills produced a total of 277.63Mt of pigiron in 2005, accounting for 86% of the total pig iron production of the whole country. This figure is projected to be 299.84Mt for 2006 (accounting for 84% of the total amount produced by the country). Therefore, based on a very conservative estimate, total raw slag generated by these 62 steel mills in 2005 is approximately 83.29Mt, and this figure is projected to be around 89.96Mt for 2006. Due to the rather high investment capital required for each VRM slag grinding plant, (average costs for a plant with 600,000t/year designed capacity is approximately US$11.57m or Euro8.88m), in order that a reasonable return on investment may be realized, it is almost a prerequisite that the plant is supported by a steel mill generating at least 300,000t/year of slag.
According to market information collected, there will be a total of 45 slag grinding plants in operation among the top 62 steel mills in China. By then, about 73% of the top 62 steel mills will have either their wholly owned or associated companies engaged in slag grinding and together producing up to 29.9Mt/year GGBS (i.e. utilizing about 36% of the raw slag generated by this group in 2005). Therefore, expansion of slag grinding capacity in China is expected to continue at least for the next 5 years if the huge slag resources are to be fully utilized to churn out high quality and value-added GGBS.