The coffee grounds are then brewed in boiling water in a giant vat (think: giant French-press). Then liquid brew is then extracted out of the vat - for instant coffee, the liquid is the part that is used. The remaining coffee grounds can be recycled and used as a fuel source (similarly to burning coal, the coffee grounds can be burned!). https://disqus.com/by/disqus_FC4z7JLiqo/about/