PINOSKLO (pina = foam and sklo = glass) is a producer of cellular glass in Ukraine. On their website, they give detailed information about the production process, which is very exceptional in the cellular glass world and for which we are greatful. In the following, I will use some of their pictures to explain the process.
The glass is ground and mixed with carbon black. It is not clear whether the carbon black addition is done during or after grinding.
The powder is put in molds, which are introduced in a foaming furnace. The entrance of the foaming furnace has a door to keep a reducing atmosphere inside to avoid that the carbon black burns before sintering is performed. The website mentions 1000°C which is rather high. The molds have a separate bottom.
The foam is stripped from the molds and introduced in an annealing furnace.
The website mentions that the speed is very critical. They use a method I have never seen. Normally, blocks are annealed like bottles in a hollow ware lehr with forced convection (ZES FOAMGLASS). But this factory pile up the blocks for their travel through the annealing furnace. We observe few yellow lines on the surface of the blocks, probably due to too fast cooling between stripping and entrance of the lehr. The following pictures show the block annealing in this case and a bottle glass lehr. The advantage of this lehr is that draft is almost eliminated.
After annealing, the blocks are finished (ground and sawed) to the requested dimensions. The waste is converted in cellular glass gravel, which is also a very ecologic approach.
A part of the production is coated with hot bitumen.
We learn that block annealing can be done with piles of blocks, which travel very slowly through the lehr, probably without the use of forced convection.
This factory is really a nice initiative in the cellular glass world. They clearly have still a margin to improve and to produce cellular glass, affordable for every individual, who is able to buy high density mineral wool. The published thermal conductivity / compressive strength is the typical value for cellular glass, foamed directly from waste glass without remelting.