Disposing of Waste Powder

Q. We generate waste powder in our spray-to-waste powder booth. We have been throwing it into the dumpster, but our waste hauler has asked us to stop disposing of it this way. He says the colored dust blows around when he dumps it and gets all over his truck and the equipment used to spread the waste around at the landfill. He does not want the dry powder and the landfill does not want it either. Is there some way to use the over-sprayed powder instead of throwing it out? Are there any alternative ways to dispose of waste powder? Thanks in advance for your help. F.N.

A. Getting rid of powder is much like any other waste stream today. Follow the three Rs before resorting to disposal: Reduce, Reuse or Recycle.

The amount of powder you dispose of can be reduced by practicing good first pass transfer efficiency (FPTE) or by reclaiming. FPTE is influenced by various methods of control over the application process. Control of heat and humidity, gun positioning, proper electrostatic settings, the correct powder output and velocity of the powder from the gun tip are examples of variables that need to be in proper ranges to obtain optimum FPTE. Review your application practices and improve your TE to the highest possible number.

You can reclaim powder for reuse by practicing good scheduling and having the right equipment. For many companies, the schedule is based on orders, and batching by color is not practical. Even in operations with short runs, every effort should be made to reclaim over-sprayed powder. Some companies that cannot collect the over-spray for reuse do use waste powder for internal parts that need rust prevention where the color is not important. If you have parts that need protection but the color does not matter, you may be able to use your scrap powder for those parts.

As far as disposal options, one of the more common ways to dispose of waste powder is to bake it into a block and throw the block away. You can use a non-flammable container (aluminum roaster pans work well) and set the powder in the vestibule area of the oven to expose it to the oven heat. Do not set a cardboard box in the oven because it can ignite. The block is often easier to get rid of than dry powder. If the volume is too high for this technique, you may have to pay more to have the dry powder waste hauled.