The Quincy Mine’s first foray into placing a rockhouse into its shafthouse was at the old Pewabic No.6, a shaft Quincy had acquired when it purchased its old neighbor in 1891. Known as the “North Quincy”, this shaft was far removed from the rest of the mine’s surface plant including its already established rockhouse. That distance made it nearly impossible to haul its rock down to Quincy’s rockhouse for processing, and even if it could the old rockhouse was already at its capacity serving the mine’s No.2 and No.4 shafts. Instead any rock brought up from the No.6 would have to be processed on site and then transported to the mine’s mill directly. Since the aging shafthouse of the No.6 had to be rebuilt anyway, Quincy simple placed the necessary rock crushers and sorting equipment directly into the new building and erected its first combination shaft/rockhouse in the process.
Quincy was not the first to do this, but from that point on it would be an industry leader in the concept. The mine quickly found that the rock handling capacity at the No.6 far outstripped the mine’s old rockhouse and did so with far less men and far less cost. In the years that followed the company would upgrade No.2 shaft in the No.6’s image, building a duplicate shaft/rockhouse there as well. Over the next several decades both rockhouses would be fine-tuned and adjusted to maximize their efficiencies and capacities. As the new century dawned the company was sure they had perfected the formula and erected a brand new shaft/rockhouse above the No.2 to showcase their improved rock handling methodolgyThat methodology can be seen above, with rock movement indicated in red arrows. As we noted in the last installment, the Quincy Method utilized gravity to move copper rock through several stages of sorting and crushing, working like a giant child’s sand toy as the rock tumbled its way into a series of large storage silos at the structure’s base. Before even entering the rockhouse, however, the rock received an initial sorting underground, where trammers filled skips with either poor rock or copper bearing rock. Those skips loaded with poor rock would be treated on a lower level in the structure, while those skips loaded with copper rock would be brought high up into the building’s upper reaches to be processed in the building’s rockhouse level. It is that level that is the subject of our post today.
A rockhouse’s purpose – be it an independent structure or built into the shafthouse itself – was to convert the copper rock brought up from the underground into rock suitable for stamping, rock known as stamp rock. This stamp rock had to be small enough to fit into the stamps – about 3″ in diameter. At the Quincy No.2 that conversion process began by first sorting the copper rock coming up from he underground by size: pieces small enough to fit into stamps already, medium sized pieces that could be crushed into smaller sizes, and large masses too large to be worked in neither the stamps or the crushers. Each of these sizes would take a different path through the rockhouse, but would all end up eventually in one of the holding silos found at the structure’s base.The rockhouse level can be easily identified as the large protruding cube set atop the shaft/rockhouse’s massive stamp rock silo. The cube is roughly 50 feet on all sides, rising three stories in height to its sloped roofline. Inside are two floors, an upper auxiliary floor marked by the single window up top and the main rockhouse floor located behind the trio of windows at the bottom. Also marking that main rockhouse floor is the large wooden door and iron balcony seen to the left. But before we get to that point of interest, we turn upward to the top of the cube and the first step in the sorting process – the grizzlies.
Grizzlies were essentially large iron grates laid flat and placed at a slight downward angle. The grate would consist of round bars placed an equal distance apart with gaps between them. Copper rock would be dumped upon the grizzlies and due to their angle would slide down along their length. Rocks smaller then the width of the bars would slip through while those of a larger size would slide down and fall off the grizzly’s end. The end result was the rock would be sorted by size, a group consisting of rock smaller than the gap between the bars and another consisting of rock larger than that gap.
After decades of trial and error the Quincy Method would utilize two sets of grizzlies placed one on top of the other – as seen to the left. The top grizzly was 16 feet long and was set at a downward angle of 16º. The bottom grizzly was set at a steeper 20º angle but was far shorter in length, running for only 6 feet. Along the top grizzly the bars were set 20″ apart, while the bottom grizzly had narrow spacing of just 3″. While these numbers may seem arbitrary, they were culled from several years of trial and error as Quincy tried various configurations of length, bar spacing, and slope until rock handling was at its most efficient.
As a result rock entering the grizzlies first took a ride along the upper grate. There any rock smaller then 20″ fell through to the next grizzly, while those pieces of a larger size slid off the bars and dropped off their end. Rock of this larger size was almost always mass copper – pieces of pure copper only marred slightly by some clinging pieces of poor rock on their surface. Not only were they too big to fit into the stamps, they was also too hard and large to be crushed by the crushers. These large pieces of copper had to be dealt with separately from the rest of the rock coming off the skip, and as such were dropped into their own storage bin located at the far end of the grizzlies.
Meanwhile the rock of a size smaller than 20″ that fell through the bars would land on the second grizzly and take a second ride along its length. Here the space between bars was far narrower, only 3″. This size happened to be the same size required by the stamps, so any rock that could slip through the bars were considered stamp rock and were dropped directly into the stamp rock storage silo.
That would leave only the Goldilocks rocks behind – those pieces of copper rock too small to drop off the top grizzly but too large to pass through the second. This would make up the majority of the rock brought up from the underground and was the prime material the rockhouse dealt with. This rock would have to be broken down into a size suitable for the stamps, which required a trip into the No.2 rockhouse’s pair of rock crushers. But before that could happen it would have to be sorted one last time – this time by hand. Thus the Goldilocks rock slid off that second grizzly and dropped into a cylindrical iron rock bin on the rockhouse floor.
At this point the mechanical sorting was complete, the grizzlies having separated the copper rock coming off the skip into three groups. Except for the smallest sized rock which was already safely at home in the stamp rock silo, both the mass and the Goldilocks sized rocks would have a few steps left to go before they too could rest easy in their perspective storage silos. From here on, however, it was man that would take control of the process. More specifically a trio of men who made up the entire workforce of the Quincy Method’s super efficient and productive rockhouse.
These workers toiled here on the rockhouse level – seen in all its dusty and dirty glory as photographed by Jet Lowe, photographer for the government’s Historic American Engineering Record. This shot was taken in 1968, but with no copper worked here for over a century it stands to reason that the view today is largely the same. The floor is not incredibly large with only around 2,000 square feet of space to work with. While that may seem like a lot, it was space that was chocked full of equipment and machinery least of which was the massive cylinder stamp rock bin occupying the floor’s back third.
Joining that bin are a pair of rock crushers embedded into the floor, one to the right and another hidden off to the left. Further to the left is a steam powered hammer, while back to the far right can be seen a small winch powering the small crane seen on the building’s exterior. At the very top of the photo can be glimpsed the bottom of those sorting grizzlies, the iron chute heading off to the left carrying the large sized rocks from the grizzly over to a storage bin located just off camera. The skip road, meanwhile, would be found to the far back end of this photo, behind the dark doorway seen in the background.
The real star of the show however was that large rock bin, as it was within its shadow that most of the work in the rockhouse was performed.Mr. Lowe provides us with a closer view of that bin, centering on one of the chutes protruding from its base. The chutes are 5 feet long and drop at a 30º angle from the rock bin down to the rock crushers embedded into the floor. At both ends of the chute are pneumatically controlled doors, one at the rock bin to allow copper rock to enter the chute and another at the chute’s terminus to allow that rock to pass on to the adjacent rock crusher. Before it could do that, however, the rock would have to be inspected to insure there wasn’t any pieces that couldn’t or shouldn’t be worked by the crusher – this included pieces of rock absent of any attached copper, or pieces of copper absent of any attached rock.
This inspection was carried out by a pair of attendants who stood alongside the chutes – one per chute. The attendant would close the gate at the bottom of the chute and then open the bin door to allow rock to tumble down into the chute. Once the chute we filled he would close the bin door and began picking through the rock in the chute. Any poor rock he found would be dropped into a small hole at his feet while those large pieces of copper would be thrown onto the metal pan to his left to await their turn at the steam hammer. Once the rouge items were removed, the attendant would then the gate at the chute’s end, allowing the rock to slide into the crusher to be crushed. Once the chute was empty he would once again close the gate and began the process yet again. This was his job for the entirety of his shift.At the Quincy No.2 only two crushers are used, which differs substantially from earlier incarnations of the company’s rockhouses. In the early days Quincy would utilize as many as six crushers, which would work the rock in two stages. The first set of crushers would do a preliminary amount of crushing to shrink the rock to one size, while a second group would work the rock again but this time break it into an even smaller size. Quincy realized that this two-stage process was not only labor intensive – as each crusher would need an attendant to insure its smooth operation – but the energy requirements to power that many crushers at one time was prohibitive. After some trial and error it was determined that a single crusher was all that was required, and the two stage approach was unnecessary. Thus when the No.2 rockhouse was built, only one set of crushers were installed – crushers that deposited their work directly into the stamp rock silo located below them.
Those crushers were relatively simple machines, consisting of a pair of iron plates that came together at their bottoms to form a “V”. One plate was stationary while the other was allowed to pivot around its upper point. That pivotable plate was repeatable forced opened and closed, smashing any rock that happen to rest between it and the stationary plate. The crushers used at the Quincy No.2 had a maw of 22×36″ at their widest point. They were driven from an overhead pulley system by means of a belt connected to an overhead drive shaft. While no longer present in the photo, the belt would have wrapped around the wheel seen to the crusher’s far left.That belt and pulley system was itself powered by a dedicated Corliss engine – the very same model seen in the photo above. This engine is also housed on the same rockhouse level as the crushers, residing within a makeshift “room” taking up the north-west corner of the room. The room probably served as protection from any flying pieces of rock or copper from the crushers or hammers next door. Steam arrived from the nearby boiler house, and its power was used to spin a large belt pulley that also served as the engine’s flywheel. Though absent here, a large belt would have wrapped around that pulley and strung up to another large pulley found up along the rockhouse’s upper floor. From there a series of adjacent pulleys and drive shafts would transfer that motion to the crushers and other pieces of equipment found throughout the building.
Besides when first getting started or for routine maintenance, this room would remain largely empty during the day with no full-time attendant. Besides the two chute attendants only one other person could be found on the rockhouse floor but his workstation was at the opposite corner of the room attending the last set of machines to be found on this level – the hammers.
Once again thanks to photographer Jet Lowe we find ourselves looking out across the rockhouse floor, this time with a view out towards the hoist-facing facade of the building. Like the opposite side of the room, this side is also taken up largely by a storage bin. In this case the bin is for mass copper, dropped off the first level of grizzlies whose end ramp can be glimpsed up within the rafters. To the left of the bin sits a piece of equipment known as a drop hammer, while directly in front of it can be found another hammer – though this one was powered by steam. Both of these machines were tended to by a single operator, the last man on the rockhouse floor’s three man team. His job was to operate both hammers, the majority of his time being spent on the steam powered version.The steam hammer was used to work any large pieces of copper that couldn’t be fed into the crushers. Traditionally these large pieces of copper were known as “barrel copper”, since early mines would simply load them into barrels for transportation to the mill. These pieces of barrel copper were picked out of the copper rock chutes by the rockhouse crew, who then would drop the copper pieces atop the large iron dish found in front of the hammer. The hammer man would then “clean” that barrel copper, which meant breaking off any remaining poor rock still clinging to its surface. It was a job best suited to the steam hammer, basically a large iron sledgehammer which was driven repeatedly down upon the barrel copper smashing away any clinging poor rock in the process. The removed poor rock would be dropped down a nearby chute for delivery to the poor rock silo, while the cleaned copper pieces were dropped down a second chute that brought them to a separate mass copper storage silo.
Meanwhile for any large pieces of copper rock landing in that mass-copper bin found behind the steam hammer, they had to be treated a bit differently. These were rocks of the largest variety – over 20″ in size. These pieces were not only too large for the stamps or crushers, they also couldn’t fit under the steam hammer to be worked. Instead they would have to be worked under the drop hammer. Seen just to the left of the bin, this piece of equipment was even simpler then the crushers. It was basically nothing more than just a large weight hung from a string. It gets its name from the way it was operated – by dropping it. A winch up on an upper floor would be used to pull the heavy weight high up into the rafters. The piece of copper rock would be placed below it and the winch disengaged to allow the weight to drop onto the rock, kept on target by wooden guide sleeve.
While it would seem such a device would have little effect, its blow was forceful enough to require a tower of concrete to be placed below it to absorb the blow – the top of which you can see peeking up from the floor in the interior photo above. While copper would resist the blow, any attached poor rock would easily be blasted off. What remained was a large piece of mass copper, a prize that would be dropped into a chute leading to the mass copper silo. Unless it was too large to fit into that chute, in which case it would be brought out an adjacent loading door to be taken care of outside.Once outside that door the copper rock would be loaded onto this small derrick attached to the shaft/rockhouse’s exterior. The derrick would swing the copper out away from the balcony and lowered down to ground level to be loaded onto a truck or rail car. The crane was operated by means of a winch found inside the rockhouse, whose cable was routed under the floor and outside via a pulley seen just below the crane itself in the photo above. As that mass copper was lowered down to the ground it would pass by the shaft/rockhouse’s most prominent features – its collection of iron silos making up the structure’s lower third. With our tour of the rockhouse level we move onto where all the copper rock ended up, and what happened to it after that.
To Be Continued…