Before you will set up lava glass production, you have to increase production of marble and sand as lava glass costs coral and glass. Coral costs marble and Glass costs sand.
Lava Glass is often needed mostly at construction, clearing lava debris like blockage, geyser and lava pool and building decos. However, lava production is not easy. It may take many months or even years to complete lava production. Do not worry and do the progress step by step.