There was a time when corporations paid little attention to the waste produced by creating their products. Today, however, we understand much more about the impact industrial waste has on the environment — and responsible companies are taking steps to reduce such waste and engage in more environmentally-conscious production practices. If you use printed circuit boards in your business, you may be interested in proper printed circuit board recycling methods. Printed circuit board methods deal primarily with the removal of copper from the board, as copper can be very valuable and it’s easy to find applications for reusing it.
Why You Need Special Printed Circuit Board Recycling Methods
A printed circuit board is made of many different materials, the most valuable of which is copper. When you dispose of a printed circuit board, that copper can bleed into the environment through media like wastewater and solid waste. In addition to being damaging to the environment, this is extremely wasteful, as the copper in a printed circuit board can actually be quite valuable.
What You Can Recycle From Printed Circuit Boards
Some of the valuable material that can be recovered from printed circuit board waste include:
- Copper from the edge trim
- Copper oxide from treatment sludge
- Copper from the etching solution
- Copper hydroxide from the plated through holes process
- Copper from the rack stripping process
- Copper from the solder stripping process
- Tin from the hot air leveling process
How to Recycle Copper and Tin From Printed Circuit Boards
Here are some of the key ways copper can be reclaimed:
- Recycling Copper From Edge Trim: To recycle the copper from the edge trim of your printed circuit board, treat it with a stripping solution. This can dissolve precious metals like gold, silver and platinum, which you can also reuse. Then, use mechanical methods to separate the copper by shredding and grinding the trim and then using a cyclone separator to pull the copper from the plastic resin.
- Recovering Copper From Wastewater Sludge: To get at this copper, simply heat the sludge to 600 to 750 degrees Celsius to create copper oxide, and then use the smelter to turn it into copper metal.
- Recycling Copper From the Spent Basic Etching Solution: Adjust the solution to a weak acidic condition to produce copper hydroxide, then follow the process of removing copper from wastewater sludge. You can recover leftover copper in the filtrate with selective ion exchange resins.
- Recovering Copper Hydroxide From the Copper Sulfate Solution From the Plated Through Holes Process: Put the solution into your reactor and agitate while lowering the temperature to 10 to 20 degrees Celsius with a chiller. Use a centrifuge to recover the copper sulfate crystal and adjust the pH of the effluent to recover the remaining copper hydroxide.
- Recovering Copper From the Rack Stripping Process: To recover copper from the spent nitric acid, use electrowinning with an electric winning reactor to recover the copper ions as metal copper.
- Recycling Copper From the Spent Tin/Lead Stripping Solution From the Solder Stripping Process: Following the etching process, remove the protective solder plate to expose the copper connections. Strip the tin and lead from the solder plate by immersing the printed circuit board in nitric acid or a hydrogen fluoride stripping solution. Use electrowinning to recover the copper and lead, as well as tin oxides, which are precipitated out and can be filter-pressed.
- Recovering Tin From the Hot Air Leveling Process: The hot air leveling process creates tin/lead solder dross that is suitable for recycling. Separate the tin by heating the dross in a reverberatory furnace at about 1400 to 1600 degrees Celsius, deslagging to remove iron, then putting it in a melting furnace with sulfur to remove the copper.
Although these processes may seem time-consuming, once you set up a system for recycling printed circuit board material, you can go through them quite easily and recover some valuable metals to reuse or sell to help your bottom line, all while protecting the environment.
Your Source for Printed Circuit Boards
If you don’t currently have a good source for printed circuit boards, contact Millennium Circuits Limited today, as we can provide you with a wide variety of circuit boards at reasonable prices, which you can learn more about by contacting us online for a fast, free quote.
If you have any questions about printed circuit boards, the printed circuit board recycling process, or anything else connected to PCBs and PCB related products, feel free to give us a call anytime at 717-558-5975.