Table 1.
Type and number of airborne fiber samples collected in tungsten refining plants listing buildings, manufacturing processes and process temperatures
| Plant | Building | Process | Temperature | Sample type |
|
| AS | PS | ||||
| 1 | Metal separation | APT | H | 1 | 0 |
| Metal separation | Calcining (blue) | H | 4 | 0 | |
| Metal separation | Calcining (yellow) | H | 3 | 0 | |
| Carbide | Carburizing | H | 5 | 1 | |
| Reclamation B | Reclamation (ball mill) | L | 2 | 0 | |
| Metal separation | Reclamation (barrel dry) | H | 1 | 0 | |
| Reclamation B | Reclamation (crushing) | L | 1 | 0 | |
| Metal Separation/reclamation A | Reclamation (screening) | L | 2 | 0 | |
| Reduction | Reduction | H | 9 | 1 | |
| Autoreduction | Reduction (automated) | H | 1 | 0 | |
| 2 | Building B | Ball mill | L | 0 | 1 |
| Building A | Charging | L | 3 | 1 | |
| Building A | Reprocessing (crushing) | L | 1 | 0 | |
| Building A | Reprocessing (screening) | L | 3 | 1 | |
| Building A | Screening | L | 6 | 1 | |
| Building B | Spray drying | H | 5 | 1 | |
| 3 | Manufacturing | Pressing/molding | L | 7 | 0 |
| Manufacturing | Sintering | H | 8 | 0 | |
| Total | 62 | 7 | |||
AS, area air sample collected at stationary locations in work areas to capture airborne fiber concentrations during specific process activities; PS, personal breathing zone air sample collected to characterize airborne fiber exposure during the course of normal employee work activities; H, process was heated and L, process was not heated.