Critical Metals? Mine them from Michigan Landfills

Do you know how much copper, nickel, chrome and zinc is buried in landfills within 100 miles of Detroit? (Hint: Lots. Like, millions of pounds)

I can still remember seeing the greenish (an indication of the Nickel content) gelatinous putty-like consistency semi-solid that was our plating sludge slowly sliding out of the dump trailer at the nearby (municipal) landfill. It was the late 70’s. The landfill was 2 miles up the road from the auto plant that was my first job out of college. We cast engine blocks on one end drove cars off the other and did everything in between.

Sludge from plating bumpers typically had higher concentrations of metals than do raw ores today

Including plating 12,000 bumpers a day. Copper, copper cyanide strike, bright nickel, hard chrome.

We sent 40 yards (tons) of sludge from our wastewater treatment plant offsite for disposal per day. We neutralized the general plating waste stream, oxidized the cyanides, reduced the Cr+6 to Cr+3, then formed a hydroxide precipitate which we filtered out.

I found an old EPA Wastewater in Metal Finishing guide (dated 1977), that estimates 8 percent copper dry weight percent and 21 percent nickel. I’m thinking those might be (quite) a bit high, but the Waste Profile Sheets at the secure landfills that took the sludge once the RCRA Resource Conservation and Recovery Act regulations of the 1970’s kicked in would give better numbers. Even at 1 percent, times 50 weeks per year 5 days per week, that’s 100,000 pounds of metal. Times 30 years? More? You’d need to cross reference to auto production etc. to get better numbers. That’s just 1 car plant.

Oldsmobile plated all their own bumpers in Lansing, Chevy plated bumpers in Livonia. I don’t know where Ford plated their bumpers but if anywhere near Detroit the waste would have gone into the secure landfill in Belleville that Ford owns. Don’t know about Chrysler but easy enough to find out.

I also remember seeing some aerial photos showing how much land had been built out into the river near the Jeep Toledo plant, allegedly some of which was plating sludge.

According to Badell’s Collision article The Evolution of Bumpers: An Auto Safety Apparatus, bumpers were first chrome plated in the 20’s.

Pontiac had been treating their plating wastewater since 1954 at the latest, not sure when the last chrome plated bumpers came out.

Bottom line, there’s a lot of plating sludge in probably about 10 landfills.

Before the RCRA regulations came out in the 70’s, many of the landfills used for industrial waste were unlined. The one used by the plant I worked at had a river/creek running through the middle that was routed through a culvert.

So in addition to nearby metals, close to some of the new EV battery initiatives, we have both the Environmental and Social components to mining these metals for reuse (groundwater cleanup anyone?)

We always said that one day we would be mining landfills for their materials. There was talk for a time about “monofills”, where cells would be dedicated to specific industrial wastes for easier mining in the future, but I don’t know that ever came about. Methane recovery is already being done. We’re hearing about community solar projects being sited on landfills.

Inflation Reduction Action funds? American sourced materials for sure.

Help me figure out who else or what other entities might be interested in this!

When I first started at the auto plant, the head of Maintenance (who was getting ready to retire) asked me “Do you want to know what we used to do with it?” Of course I said Yes. “We used to dig a pit behind the plant and light it on fire”. (Since the plant sat on 180 feet of blue clay and could have been a hazardous waste landfill, no serious harm done, but still…) I’m probably one of the last people to know that story.

I may be one of the few people around who was deeply involved in the automotive bumper plating technology and waste management “back in the day” (there are some amazing stories around it, ask me about the chicken salad sandwich sometime). I hand the baton of the knowledge about where the sludge went to YOU, dear reader.

This one is interdisciplinary, and hard, Hard HARD tech.

Til next time…