Metal finishing Q&As since 1989

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Copper Brazing Paste Waste Disposal

I am an intern from Iowa State University working for the Iowa Department of Natural Resources working at a factory in Iowa for the summer. Due to certain laws and agreements in place I cannot mention what company I am working at.

We have a copper brazing operation for one step in the assembly process. My problem is not with the brazing process, but rather with the disposal of the copper brazing paste buckets. A very small amount of copper residue is present in each bucket even after the copper brazing paste has been physically removed from empty buckets by hand. Washing the buckets transfers copper to city storm sewer and results in a fine from the city. The practice of washing used buckets has since been stopped. We do not want to simply send the buckets to the landfill because of concerns that the small amounts of copper paste will leach out into the environment over the next 10-20 years and create a liability for us.

What we are looking for is a way to dispose of the buckets at a reasonable price. This may include finding someone who would take the buckets from us in order to salvage any left over copper. Another possibility includes finding a product or process that turns the material in the bucket into a non-soluble solid that will not leach out of a bucket and into the environment after it has been sent to a landfill. Ideally this product would form cement like material.

We use a Copper Brazing Paste that is 90% Copper, 10% Copper Oxide, and contains a water based fluxless binder. Talking with the manufacturer yielded a conversation that mostly has the manufacturer telling me that my concerns about copper entering into the environment did not matter anyway with the large amounts of copper entering the environment from other sources. His opinion is contrary to the opinion of the company I am working at and contrary to what I am trying to accomplish, which is the safe disposal of a waste product.

Thank you to anyone who can help me on this matter. It is greatly appreciated.

John Dostart
- Ames, Iowa
2001

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We have a somewhat analogous situation in the electroplating industry because some of the processing solutions (for example, electroless nickel) are difficult to treat. The resolution that has developed over the years is that the suppliers of the electroless nickel solution have gotten into the business of taking back the solutions from the users and treating them.

Your supplier isn't going to want to hear it, but what he is probably going to have to do in the near future is to take back these buckets from his customers and recover the copper. The sooner he starts, the better off he'll be, so encourage him to bite the bullet and do it.

As for the laws, I'm not sure who is right, because industries are 'categorically regulated'. For example, electroplaters cannot discharge nearly anything because the laws covering their category forbid it. But whether you or he falls into any regulated category and have any current legal obligation to treat this waste I wouldn't know. Copper metal is a very different thing from soluble copper salts and it is not inconceivable that there are no regulations covering this material.

But your suspicion that there is future liability associated with this waste is undoubtedly true. As we speak, the courtrooms are jammed with environmental suits trying to reassign liability for things that happened in the 40's and 50's. Based on hearing only your side, I think your supplier has his head in the sand and that you should be shopping around for a more forward-thinking supplier.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
2001

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Properly managing empty containers that may contain a small amount of hazardous or non-hazardous residue is a problem many company's face. I would recommend you call a handful of environmental company's in your service area. They are used to cleaning empty pails, drums, totes, etc... prior to proper disposal or recycling. Look for a company that will clean the pails, treat the rinsewater and potentially recycle the container. Another option, though less desirable, would be to offer the containers to an environmental company that operates a permitted subtitle C or D landfill.

You are doing your company a favor by researching the best handling and disposal option for these containers. Much of the environmental liability industry faces today is from being held responsible for the clean up of local landfills. Even if those landfills accepted "industrial waste," that was not regulated at the time of disposal.

Jim Sullivan
- Butler, NJ
2001

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As others have mentioned, this is a common problem when dealing with packaging that contains potentially harmful components.

While encouraging your supplier to take back the packaging to recycle the material is a good course of action, it may not bear fruit in the short term. Often, the cost of shipping the material back and refining it into a usable product is cost-prohibitive (while certainly ethically commendable!). It is definitely a good idea to pursue this course, or to consider the use of reusable shipping containers (ie, return and refill). But both ideas will cost additional money which will ultimately be passed on to the customer (you).

There is an alternate solution which will work well based upon the product you are using. Since the paste is water-based, it is relatively simple to remove the binder from the copper powder by soaking/rinsing the pails in water. Using a suitable sized container (30 gal drum, 5 gal bucket, etc), you can wash all of your used buckets by reusing the same quantity of water. Dump all of the rinse water into one container. Over time, the copper solids will settle out into the bottom of the container. The container can be decanted after it has fully settled, and the remaining copper powder can be sent out as scrap metal (or returned to the supplier).

Obviously, you want to use the minimal quantity of water possible. The decanted water can be evaporated to virtually eliminate any discharge to the environment.

Michael McCoy
- Union, NJ, USA
July 9, 2009