---
title: "Build-up / coating / accretion"
description: "Build-up, coating and accretion are interchangeable terms used in cement-industry vocabulary for accumulated deposits on the gas-path surfaces of a cement plant — preheater cyclones, calciner, kiln inlet, tertiary air duct, bypass system. Build-up is the leading single cause of unplanned cement-kiln stops."
canonical_url: "https://sylio.co/glossary/build-up-coating-accretion"
last_updated: "2026-06-28T02:29:26.767Z"
---

**Build-up**, **coating** and **accretion** are interchangeable terms used in cement-industry vocabulary for accumulated deposits on the gas-path surfaces of a cement plant — [preheater cyclones](/glossary/preheater-cyclone), [calciner](/glossary/calciner), [kiln inlet](/glossary/kiln-inlet-riser-duct), [tertiary air duct](/glossary/tertiary-air-duct), bypass system. Build-up is the leading single cause of unplanned cement-kiln stops.

## Composition

Cement-plant build-up is dominated by:

- **Alkali sulphates** (K₂SO₄, Na₂SO₄)
- **Alkali chlorides** (KCl, NaCl)
- **Calcium sulphate** (CaSO₄)
- **Sticky pre-calcined meal** trapped in the matrix

The exact composition depends on raw-material chemistry, fuel chemistry, and where in the preheater-kiln system the deposit forms.

## Why build-up matters

- **Kiln stops** when build-up blocks the gas path
- **Lost clinker** during the outage
- **Operator hours** to remove with hammer, lance, water
- **Refractory damage** from the cleaning operation
- **HSE risk** to operators working in the hot, confined gas-path

## Active prevention

[Sonic horns](/glossary/sonic-horn), [air cannons](/glossary/air-cannon-air-blaster) and operator vigilance combine to prevent build-up from consolidating into kiln-stop conditions. The acoustic approach is the dominant preventive technology because it works continuously and causes no structural damage.

## Related terms

- [Preheater tower](/glossary/preheater-tower)
- [Kiln-inlet ring / snowman](/glossary/kiln-inlet-ring-snowman)
- [Sulphur / chloride / alkali cycles](/glossary/sulphur-cycle-chloride-cycle-alkali-cycle)
- [Sonic horn](/glossary/sonic-horn)