Choice of recarburiser
The selection of a recarburiser always depends on the produced iron alloy. Ductile graphite iron (GGG / GJS), cast iron with vermicular graphite (CGI) and special steel grades require a low sulfur content.
For grey iron (GG / GJL) normally a recarburiser with a medium sulphur content is fully sufficient (see enclosed table). To determine the carbon content, at least one sample should be extracted from the molten iron for chemical analysis.
Overview
| Type of recarburiser | Field of application | Properties / Advantages / Disadvantages | Solubility 1 – 6 |
|---|---|---|---|
| Graphite – crystalline carbon | |||
| High purity, synthetic raphite (i.e. Ultra High Power-E-Graphite) | all iron alloys | High C content, very good solubility, low N and H content | 1 |
| Synthetic graphite E-graphite graphitised Petroleum coke | all iron alloys | High C content, very good solubility, low S, N, ash content | 1 |
| Natural graphite | iron alloys with an elevated tapping temperature | The higher ash content results in a slower solubility, S and N content is generally low, varying analysis (depending on the storage facility) | 4 |
| Coke – amorphous carbon | |||
| Acetylene coke Granular and pellets | all iron alloys | High C content, slower solubility, low S, N content | 5 |
| Low sulphur petroleum coke (Needle coke) | all iron alloys | High C content, good solubility, low S, N, ash content | 1 |
| Medium sulphur petroleum coke | grey iron, steel casting and steel production | High C content, acceptable solubility | 2 |
| High sulphur and nitrogen petroleum coke | grey iron and steel production | High C, S, N content, slower solubility with higher saturation levels | 3 |
| Metallurgical Coke Breeze | steel production | High ash content, requires high melting temperatures and a low C saturation of the molten metal | 6 |
| Pellets | |||
| Carbon pellets | all iron alloys | High C content, with an elevated content of volatile matter, ideally suited for the base iron carburisation. Also suitable for rotary furnaces. Pellets are available with different chemical compositions | 4 |
| Anthracite – amorphous carbon | |||
| Electrically calcined anthracite | iron alloys with a high tapping temperature | The higher ash content results in a slower solubility, S and N content depends on the storage facility | 5 |
| Gas-calcined anthracite | iron alloys with a high tapping temperature | The higher ash content leeds to a slower solubility. S and N content depends mainly on the geological deposit. | 5 |
| Dried Anthracite | iron alloys with a high tapping temperature | Similar to ECA and GCA, but with higher volatile components | 5 |