Regarding the silicon slag issue in dust removal systems
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The silica slag used in our company’s dust removal system is supplied by external suppliers. In the past, using wet methods for slag disposal posed no problems, but with the adoption of dry methods, there have been several instances where the silica slag caught fire. Actually, it’s not a big issue if the silica slag burns inside the company – it can be extinguished by pouring water on it. However, if something goes wrong during transportation, it becomes quite troublesome. I would like to ask everyone here if there are any ways to prevent the silica slag from catching fire. Thank you!
Why not go straight to a fluidized bed? ? ? Once it returns to the bed, no further treatment is needed; our cyclone system uses a direct return-to-bed method
Reply to 2# aaronzhang: There’s no need to recycle the silica slag from the dust removal system!
Larger TCS synthesis units generally have a system that returns the silicon powder recovered by the dust removal system to the reactor bed, but this process is somewhat complex, involves many pieces of equipment and pipelines, and is difficult to maintain; therefore it is not suitable for small-scale units.
I would like to ask the original poster: what is the purity of your silicon powder, and what is its particle size? After dry dust removal, a wet dust removal system can be added; that would be sufficient
Reply to 4# Farewell to Godot: Haha, I’m quite interested in this. Although the manufacturing process is complex, could you please explain it roughly? It would be great to exchange ideas on this topic. Since several people mentioned it, there must be a reason for the existence of such a system. Please share your insights; thanks! In my opinion, the silica slag produced by the dust removal system consists of particles with quite small sizes and insufficiently reacted silica. If there are indeed many particles of larger size, then it is either due to process issues or an improper design of the synthesis furnace.
Reply to 5# fei841124: Our silicon powder has a particle size of 40–120 mesh, and dry dust removal is used for its purification. The final stage of this dust removal system is a bag filter, which provides fairly good results. In typical dust removal systems, the first cooling unit needs to be replaced every 7 to 12 days per unit, under normal operating conditions. The substances that cause blockages are usually those with high boiling points. Many manufacturers use wet dust removal methods, or even a combination of both dry and wet methods. However, for our first phase, the expansion phase, and even the current second phase, dry dust removal is employed; it’s just that the slag disposal method has changed from wet to dry.
Reply to 7# zw1902: My personal opinion is to add a humidification step and then a pressure filtration step. I only have a preliminary understanding of this; if there are any mistakes, please advise me, haha! !
Reply to 6# zw1902: The process gas coming out of the top of the synthesis furnace first enters the second and third stage cyclone separation systems; particles of larger size can be sent back to the furnace directly or into the waste silicon powder recovery tank. The process gas that has passed through the cyclone separation system then goes through another bag filter system; the silicon powder with a smaller particle size collected in this process is sent to the waste silicon powder recovery tank.
Reply to 8# fei841124: It can only be said that the manufacturing processes are different; there’s no right or wrong, haha! If the existing process can already yield TCS with a purity level that is fairly close to the desired level, then why spend more money to improve a purity level that won’t increase much anyway? Why would the boss do that?
Reply to 9# Farewell to Godot. Haha, I see. Sorry, I didn’t assign any points to you! According to what you say, how can we tell which items are recyclable and which ones are not? Our dust removal system also includes free sedimentation, cyclone separation, and bag filtration. I wonder if the purpose of designing three-stage cyclone separation is to enable the recovery of the solid silicon powder produced by free sedimentation and cyclone separation Of course, all the silica slag from our dust removal system is sourced from external suppliers. In the past, with the wet method, it was believed that the silica slag produced by bag filters could never be recycled, as its particle size was too small; such slag would simply end up as useless ash. However, with the dry method of slag disposal, it was discovered that the particle size of all the silica slag is actually extremely small, and perhaps there is still some silica slag among it that has value for recycling!