SUPPLYING REFRACTORY MATERIALS AND SOLUTIONS IN THE KILN SYSTEM OF CEMENT INDUSTRY
General Requirements on refractory
The desirable characteristics of refractory which must be achieved by careful selection are:
- Refractoriness – i.e. the ability of the brick to retain its physical properties at the operating temperature;
- Volume stability – i.e. no excessive expansion;
- Chemical resistance – i.e. resistance to the attacking species in the feed and kiln atmosphere in the zone in question;
- Abrasion resistance;
- Low thermal conductivity;
- Coatability – in general a porosity or surface texture allowing the clinker liquid to “glue” coating to the surface.
Today’s challenges on refractory
Increased usage of AFRs and Petcoke
- Higher load on circulating elements (Cl, SO3, alkalis) in the kiln system
- Less favorable combustion conditions (local reducing conditions, fluctuations in heat input, less stable kiln operation,…)
- More variable flame (shape) due to a more variable fuel mix (AFRs) resulting in shifting burning zone and less stable coating
Decreasing clinker / cement factor requires a more reactive clinker, having higher LSF and SR targets
- More burning effort required
- Less protective coating in the burning zone
Forced operation above nominal rate
- High thermal load in the burning zone or calciner
Holcim Objectives regarding Refractories
Net Kiln availability of ³ 90%:
- Maximum one kiln stop per year for refractory replacement (required downtime: 21 + 6 + 10 days)
Acceptable variable cost from refractory:
- Specific refractory consumption (g / kg cli) according or below best practice:
< 400 g/t for calciner kilns
< 800 g/t for preheater
< 1200 g/t for long kilns
Acceptable fixed cost from refractory:
- Installation of a durable refractory quality at a reasonable cost for all new kiln lines and kiln upgrades
- Fast and efficient installation methods
(Source : Holcim)
Materials list and usage
Compiled by Cost Solutions Company Limited