Current Research Topics

Refractory concretes are used today in a wide variety of industrial applications where pyro-processing or thermal containment is required [60]. Calcium aluminate cement (CAC)-based monolithics represent the most important chemical category, and the fundamental properties and behavior have been recently summarized (production, uses, CAC clinker, mineralogy, microstructure and hydration, and environmental issues) [61]. The general current working topics are depending on economic trends of the industry. The demand for refractories in the US is projected to increase 2.2% per year to $2.4 billion in 2007 [62]. The demand is expected to improve the steel market since steel manufacturing consumes about 60% of total refractories. Preformed shapes (shapes manufactured with refractory castables) and castables (for in situ monolithic manufacturing) are expected to be the fastest growth segment. Table 5 summarizes the expected refractory demand in the US.

A common trend seen today in this industry is plant integration through the merger and alliance of refractories companies. In general, the global refractory production has increased, due in part to process optimization (better usage of refractories) or to improved refractory materials with better performance. Monolithic refractories con­sumption, however, has markedly increased and represents today a large portion of the total. For instance, it is about 60% of the total production in Japan [63].

Current issues on refractory monolithics include no-cement castables, self-flow and free-flow mixes [64], and special compositions such as spinel-based [65], place­ment techniques [66], new applications (i. e., crown superstructures for glass melters [67]), characterization [68, 69], and basic castables [70, 71]. Specialized publications have compiled and reproduced most of the most important topics [i. e, 72-74], which include the following:

• Development of high performance castables (i. e., high-strength under corrosion

conditions at high temperatures)

• Application, installation issues; drying and firing equipment; development of very

large shapes

Table 5 Refractory product demand in the US (US$ million [62])

1997

2002

2007

Total demand

2,518

2,180

2,430

Bricks and shapes

1,480

1,210

1,345

Monolithics

652

575

635

Other

386

395

450

• New binders for castables without affecting refractory properties; new dispersants and rheology studies

• Study of thermo-mechanical properties, chemical behavior, theoretical predictions, and computer simulation

• Development of basic castables: for instance, use of MgO, CaO, and dolomite for making high-temperature basic castables; coating of aggregates (i. e., silanes) for preserving clinkers

• Study and optimization of drying and firing: experimental and theoretical simula­tion of drying and its effects on mechanical strength and refractoriness.