For most of the Copper Country’s history the milling process has been very inefficient. For every ton of copper recovered, dozens of pounds more slipped past and found its way to the waste launders. At the Quincy mills the process was so inefficient that the company was able to live off of recovered copper from its tailings for decades after the mine itself closed down. Those tailings might have yielded a decade more of copper if it wasn’t for the single most revolutionary machine ever to find its way to copper mills: the Wilfley Table.
The Wilfley table was designed by Arthur R. Wilfley in 1896, and was first used that year in his mill in Colorado. The tables made their way to Quincy in 1901, replacing all of the mills original Buddles that previously had been the preferred method for washing the copper slime. Copper output at the mill increased dramatically and Quincy never looked back. The tables were here to stay. At the Quincy Mill we were surprised to discover a large amount of these tables scattered about on the second floor of the addition, some of them still attached to their concrete mountings. We take a closer look at these tables here.
The Wilfley Table is simply a large wooden table, on top of which are a series of parallel “riffles”. These riffles increased in length incrementally from the top of the table down to the bottom. The entire table is set at an angle, and the slime is poured onto it from the top corner. The heavier particles (copper) would be held up along the riffles, while the lighter particles (the non-copper) would roll over them. The whole table is oscillated back and forth over 200 times a minute, which works the copper particles down the riffles and towards the opposite end of the table. From there they are removed. The rest of the slime simply floors off the table at the opposite end and is carried away in a waste launder.
At the Quincy Mill these tables have been left scattered all about, some neatly stacked on top of the other while others were simply thrown to the side. Still sitting along the floor, however, remains the concrete foundations on which those tables one sat. Using clues found at the mill ruins, I attempted to reconstruct how these Wilfley tables might have worked. Above you see an exploded view of what these tables based on this reconstructed. Lets take a tour.
At the end of each table are these metal brackets that were once attached to the table’s drive motor. It appears that the engine would push against this bracket moving the table forward. A large spring attached to the tables underside would then snap the table back to its original position. This process was repeated over 200 times a minute, oscillating the table back and forth along its length.
The redwood table was covered in a linoleum covering, on which these wooden riffles were mounted. The rocks and debris you can still see hung up on these ridges mimic what would happen to copper when the slime was poured over this surface. The oscillation from the engine would shake the table toward and away from the camera, jogging the copper along with it.
Underneath the table are a series of these mountings. I’m not sure how the whole thing worked, but the grooves along the mountings face might be a clue. Since the table moved it could not of been bolted down in any way. It most likely rested on some sort of gimbal.
Underneath the tables is mounted a large spring, still attached to most of the tables scattered about. On this table which was still mounted (somewhat) to its foundation, you can see that the spring rest on this metal bracket. I think this spring returned the table to its rest position after being pushed by the drive engine.
Sitting at the end of the table was this engine mount. The engine is gone, but the pulleys from the belt drive that once drove it are still hanging from the celling above here. Here on this level the tables sat in pairs, toe to toe. This motor mount sat on the east end, mirrored by another mount at the opposite end of the line.
The table surface rests on six mounts, three of which are of this type. Unlike the mounts on the opposite side, these are not adjustable and make up the “high” end of the table. From here the table slopes downward towards the waste launder running on the left side of the photo.
On the opposite side of the table are these mounts. These appear to be adjustable, enabling the table to be tilted at various angles. The top photo shows them still attached to the table, while the bottom photo give a closer look at what might be the adjustment components.
Here is a wider look at the mounting system for the table. These steel boards on which the mounts are attached sit atop the concrete foundations – three in total. This table was broken in half, which explains the odd tilt. In reality the table would be flat from left to right, but tilted from the top to the bottom of the photo.
The last mount on which the table rest is this angled bracket, which sits on the opposite end of the engine foundation. This bracket was attached to the spring of each table, as seen on the bottom photo. I think this bracket kept the spring in tension as the table was moved by the motor, forcing the table back to position once the engine stopped pushing on it.
A couple of final looks at the foundations on which the Wilfley tables were mounted. Tomorrow we’ll take a closer look at what this floor might have once looked like during its life, and then move on to yet one more mill machine we found remains of. Until then…