More information is required in order to help you sorry.

Are you talking about the main baghouse after a VRM or some other type of mill or are you talking about the collector located on top of the cement silo?

The filter on top of the cement silo is a matter of air in equals air out. If you are using pneumatic transport to feed the silo you need to remove the transport air with a safety factor. If you are using a bucket then common dedusting practices are applied as elsewhere. You do not usually need more than one filter. Interconnect all your silos with grass-hopper vents and as long as this is not specialty cement drop collected cement into one silo using a bin vent type collector

For the main bag house it all becomes a function of the equipment you are using to grind the clinker and the fans being used in the process. Basically it is the same concept though. Find your air supply volume and design to remove your cement from it.

Your cement is very abrasive so you need to keep the velocities in the collectors low. You typically like to see a 4:1 air to cloth ration (imperial units i believe acfm/ft2). Other factors such as can velocity, maintenance access etc need to be addressed but the most important factor is the air to cloth rato. On a bin vent dust loading should be lower are some of it should settle out before reaching the bags

If anyone tries to sell you a cartridge filter for the application on cement kindly show them the door. Use bags, size them right and all will go well.

Liam ■

Good advice Liam,

I would add:

If the cement is being delivered by road tanker, beware of the driver/operator who wants to leave in a hurry after the load has been discharged. The residual compressed air in the tanker has to be released gradually to avoid mechanical damage to the bin filter, the filter bags and the piping and its fittings. This is a common occurrence and strict instructions should be displayed at the unloading point to try to avoid it.

To anticipate non-compliance, I would over-size the bin filter (by even 50%). The relatively small cost increase is justified by longer filter life and reduced maintenance.

Michael Reid. ■

Tanker drivers, like me, are legally obliged to shut off both the outlet valves to prevent material running back into their vehicle. Then the vent valve is opened after the compressor has been shut down. This is standard safety procedure under ADR Certification and should be applied on cement tubs as well. Residual pressure exists in any tank if it is to be emptied at all. Isolating the pressurised tanker from the silo enables the tanker driver to open the tanker vent as quickly as he prefers while he disconnects, cleans and stows the hoses. A bin filter can hardly be over pressurised from the tanker which was there to start the ball rolling in the first place. I suspect the issue described was due to the tanker driver leaving his post and allowing clean/thin air to whistle through the bags. Either situation is cause for dismissal. This guy earned more as a tanker driver than he ever did as an engineer in the UK so the responsibility is there and if there is negligence the penalties should be severe: which they are! ■