The HAG is a fully automatic system for fusion, measurement of moisture, and thermogravimetric analysis (TGA)/ loss of ignition (LOI) determination. The system has following components which can be flexibly and individually combined:
Plastic vials with 20 to 50g of sample materials are manually or automatically placed into the tray of the input magazine. All following steps are fully automated:
Input tray magazine
Several options of the sample input magazine are available including 62 position sample magazine and a 200, 300 or 400 vial position tray magazine. The magazine can be connected to the preceding preparation cell or can be manually loaded. There is also a 10 position manual sample input magazine in the weighing unit where samples can be registered.
The tray magazine has an XY gripper transporting the vial inside the unit and into a barcode reading position where the sample ID can be established. The vial is placed on a transport system and transported to the fusion machine. Priorities can be set and changed on the fly. The Prep-Master control system visually indicates the status of each vial like, e.g., ‘to be analyzed’, ‘already analyzed’, ‘in fusion machine’, ‘high priority’ etc. In case that a bead is rejected within the system, the sample is collected from the magazine and automatically re-run on the system.
The dosing unit consists of up to three dosing stations, a sample mixing station, buffer position for TGA and Platinum crucible, and a release agent dosing station. All stations are operated by a small robot. Samples in vials are placed into one of the three dosing units. For the fusion process, flux and sample are alternately weighed into the crucible to achieve an optimal dilution of both substances. Subsequently, the crucible is transferred to the mixing station, where flux and sample are mixed together. Optionally, a release agent can be added. Finally, the crucible is placed on a turntable ready to go to fusion.
For TGA, the sample will be weighed into a TGA crucible and transported to the TGA module for moisture and LOI determination. In every case, the control system allows titrating of different types of flux as well as different sample and flux volume.
According to the sample load, the fusion module consists of 4, 6 or 8 heating stations. Each heating station has two heating positions for the crucible and the casting dish. A linear system transports the sample from the turntable to the heating station, fused bead to the XRF belt, and dirty crucibles and casting dishes to the cleaning station.
The crucible is heated by induction. During this process, the sample can be swirled to aid the mixing. In parallel, the casting dish is heated to a predefined temperature. When the heating cycle is complete, the sample is automatically poured into the casting dish. The bead is allowed to cool within the casting dish. Depending on the sample type different cooling regimes can be used such as fast cooling with compressed air.
The heating station is under control of a pyrometer. Therefore, it is possible to setup individual heating profiles for every sample type like, e.g., 500°C for 2 min, 1000 °C for 3 min and 1100 °C for 1 min. Before transported to the XRF, a special detector confirms that the fused bead is not cracked or moon shaped. Optionally, a camera system can be used to exclude that the bead is crystalline.
The automated cleaning module for dirty crucibles and casting dishes consists of one or two ultrasonic baths, a washing station and a drying station. 14 crucibles and casting dishes can be cleaned simultaneously in the ultrasonic cleaning station. Crucibles and casting dishes are placed in the ultrasonic bath at elevated temperature in citric acid. Afterwards, they are transported to the washing station where they are washed with normal tap and demineralised water. Before being returned to the dosing module they are dried with hot air blowers. All cleaning parameters can be adjusted with the Prep-Master system.
Automatic TGA Module
The TGA module consist of 2 to 4 TGA furnaces each running with a predefined temperature, a cooling station and a cleaning station. The number of furnaces depends from the number of temperatures at which the LOI needs to be reported. Inside the TGA module, a multi arm transports the sample from each furnace to the next as well as to the cooling and cleaning station.
Main Advantages of the Automatic Fusion Process