Sintering of Lunar and Simulant Glass

Most oxygen‐extraction techniques are temperature‐dependent, with specific temperatures resulting in optimized oxygen yield. An example is hydrogen reduction, in which the optimum process temperature is 1050 °C. However, glass‐rich lunar soil begins to show the effects of sintering at temperatures of 900 °C or lower. Sintering welds particles together due to viscous relaxation of the glass in the sample. One approach to avoid problems related to sintering, such as difficulty in removing waste material from the reactor, is to keep the soil in motion. One of several methods being studied to accomplish this is fluidized‐bed processing techniques, in which the grains are kept in motion by the action of flowing reductant gas. The spent material can be removed from the chamber while still fluidized, or the fluidizing motion can continue until the material has cooled below ∼500 °C. Until end‐to‐end prototypes are built that can remove the heated soil, the most practical option is to keep the bed fluidized while ...