Method and apparatus for secondary enrichment and recovery of germanium from low-grade lignite germanium concentrates with by microwave heating in vacuum

A method for secondary enrichment and recovery of germanium from a low-grade lignite germanium concentrate with microwave heating in vacuum, comprising:

• transferring a low-grade lignite germanium concentrate into a material crucible and placing the material crucible containing the low-grade lignite germanium concentrate in a heating chamber of a microwave heating device for vacuum volatilization;
• and closing the heating chamber and connecting pipes of each part of the heating chamber;
• starting a vacuum device to reduce pressure in the heating chamber to be lower than 1,000 Pa;
• starting the microwave heating device to increase temperature to 900-1,100° C. at a rate of 20-50° C. per minute;
• opening a valve of an inert gas to supply the inert gas at an influx of 1-3 liters per minute;
• after reacting for 1-3 hours at a constant temperature, when germanium and other volatile substances volatize into smoke and into a dust collecting system, stopping heating;
• supplying the inert gas to the heating chamber to cool the heating chamber to room temperature;
• and
• after stopping vacuum, starting a settling and collecting chamber and a bag dust collecting chamber for collecting dust;
• combining the dust to obtain a germanium concentrate.