I have been planning to build an HO scale Open Hearth furnace and have come to a problem. I can’t figure out how the hot metal gets from the bottle cars to the mixer and from the mixer to the furnace. In case it matters the era is 1940’s. Any help is greatly appreciated. Pics especialy.
CHAD
Your question shows how little I know of the open hearth process, although, in my defence, I never worked in that area. I had never heard of the mixer, and I’m uncertain if the plant where I worked used one. However, common sense would suggest that the torpedo cars would either be emptied directly into the mixer, or they would empty into a ladle, which would then transfer the iron to the mixer. In the first case, the mixer would need to be positioned lower than the track for the torpedo cars, whereas in the second scenario, the mixer could be placed at any reasonable height, with a pit provided for ladle placement for filling from the torpedo car. The second example seems to be the most efficient, as the ladle pit, if properly placed, could also be used to receive hot metal from the mixer, for transfer to the furnace.
In summary: blast furnace to torpedo cars via floor runners, torpedo car to ladle, ladle to mixer, mixer to ladle, ladle to open hearth, then open hearth to ladle, ladle to moulds.
The information that I did have was supplemented by referring to my copy of The Making, Shaping and Treating of Steel, which does mention the transfer of hot metal from the mixer to the furnace by ladle. I’m pretty sure that the plant at which I worked didn’t use a mixer.
Wayne
Having spent my career in the steel industry and several open hearths I have never heard the term mixer before. Iron is poured into a ladle which is carried by crane to a particular furnace. The lip of the ladle is placed in the charge opening and the bottom is raised with a second hook to pour it. Hot metal cars do not make it onto the charge floor. The charge floor is reserved for the charge buggies which are like ingot buggies but hold three or four iron bath tubs like devices that hold the scrap. A machine on the charge floor has a boom which is placed in a slotted connector on the tub and inserts it in the furnace before turning it upside down. It takes hundreds of buggies to charge an open hearth furnace. They always used far more scrap then a BOF. An open hearth is a big building and in real life is 1/4 to 1/2 mile long which in HO would be roughly 15 -30’.
I’m going to take a stab here abiout the mixer and propose that this was an intermediate ladle of some type designed to combine iron from more than one furnace or varying in chemistry to a uniform chemistry before adding to a melt furnace. I’ve never seen that done however as every effort is made to keep blast furnaces producing iron that is uniform in every aspect every time it is tapped. When blast furnaces produce iron that is “sick” people can lose jobs.
There are several diagrams of mixers and storage furnaces in chapter 17 of The Open Hearth. Here’s a link to the book on google: http://books.google.com/books?id=MqE7AAAAMAAJ&pg=PA5&dq=the+open+hearth#PPA201,M1
Thanks to earlier posters, I’m thinking that bottle cars would pour into a ladle below them which would then be poured into the mixer but I’m still confused on how the ladle that the mixer pours into is taken to the open hearth for charging.
Btw, ndbprr, you are right about the purpose of a mixer. It mixes iron from several heats to get the most consistent iron for the open hearth.
Thanks all
CHAD
Anybody who worked open hearths in the 40’s is going to be well up in years at this point and I suspect that if mixers were still in use then that the demands of WW2 pretty much dictated that anything pourable was consumed asap for the war effort. I know that by the time I started my career in the late 60’s they weren’t used. The ladle is taken by overhead crane with a spreader that has two big hooks with basically an I beam between them and a sheave over each hook with about twenty to thirty wraps of a cable up to a pair of drums to wrap it up that are driven together on the crane bridge. They engage two round extension pins with a flange 180 degrees apart on the sides of the ladle. On the back bottom of the ladle is a pair of triangular plates with a horizontal pin that another hook on the crane can engage to tilt the ladle. the ladle is carried to the furnace. The pouring spout is located as close to the charge window as possible. the second hook engages the lift pin and lifts the back of the ladle so it pivots on the two hooks it is hanging from. Hopefully he hits the hole with most of the molten metal. Sometimes they don’t. The melt process can take as long as 16 hours dependent on firing rates and initial chemistry so there is time to adjust to any changes needed in the heat. That is probably why mixers went out of favor since they learned to compensate during the refining of the iron to steel. Shortest heat time I can recall is about four hours but that is really pushing it with everything falling into place. Heat time is also a function of ingot prep and availability so most of the time factors beyond the melt shop control the production rate.
I’m guessing that the mixer is in the same building as the open hearth then. If so then it all makes sense. If not please correct me. I’d rather have it wrong 100 times in planning then to build it wrong once and have to rebuild. Here’s my idea in a crude out of scale sketch:
Edit: Sorry, I forgot to write how the operations in the above layout would work. Bottle cars would come in on the hot metal in track an fill the ladle in the pit. An overhead crane would pour that into the mixer for storage. The mixer would then be tapped into the ladle on the charging floor where the charging crane could lift it into position to charge the furnace.
Thanks for the help so far and any that may come.
CHAD
There’s a photo in the book that I referred to earlier which shows a pair of 800 ton mixers, which are mounted in a large, structural steel stand. According to the caption, they’re installed in a separate mixer building at one end of the charging floor. They look somewhat like big bottle cars, but without the tapered ends. In the photo, it notes that they rotate counter-clockwise to discharge iron into a transfer ladle, which can be seen in a pit, off to one side. The accompanying information states that the ladles can be carried from the mixer to the open hearth for charging either by an overhead crane, or by an electric ladle car running on its own tracks on the charging floor. It states that in the latter case, cranes are used to dump the molten iron into the open hearth, implying that the ladle stays on the transfer car, but is tilted by an overhead crane. No picture, though.
Wayne
Thanks Doctorwayne. I think i’m getting it now. The mixer building is an attached building on one end of the open hearth like the floorplan I drew earlier except it is probably more toward the center. I’m thinking it would be a lean-to of sorts with the craneways from the charging crane coming inside.
Thanks very much to all who helped here. I think I’m ready to start construction after I pick up some styrene at the LHS. I will probably post about it during construction so keep an eye out for it. Again thanks alot.
CHAD
Depending on how big you’re making your facility, you might want to check out plastic suppliers in the Yellow Pages. I buy 4’x8’ sheets of .060" styrene for under $30.00, and many other thicknesses are available. You’ll still need to buy strips and structural shape from a hobby shop, but as ndbprr notes, open hearth buildings (like most stuff in the steel industry) are big.
Wayne
Thanks for the tip Wayne. I’ll have to check that out. Also do you know how to get a corrugated siding pattern onto the plain sheet?
CHAD
I can’t think of any easy way to do that. I’ve used Campbells corrugated aluminum siding, fastened to the plastic with contact cement, but the cost would be prohibitive on a structure of any size. The corrugations are also too small for most of the siding used on steel mills. You could use some heavy-duty aluminum foil to make your own, although you’d first need to find or make a pattern on which to form the foil.
This building has a framework of strip styrene, with Campbell’s siding glued to it with contact cement.
On this one, the roof is Campbell sheets cemented to an .060" styrene sub-roof. The walls are Evergreen styrene corrugated sheets.
Wayne
Chad,
Dunno about the 40’s,but I do know about two different kinds of hot metal mixers.The first one being a stationary below floor type.The other a friggin huge wheeled hot metal car.If you go to “Google patents”,type in hot metal mixer drawings in the search box.Should pull up a bunch of listings.
I noticed your also looking for sheet metal siding in HO. I can tell you how I covered my HO scale 4’ long X 4’ wide X 3’ high basic oxygen furnace. I work for local county goverment…hence a trash man. I find stuff all the time. One day I came across a projection screen TV.Looking closer at it ,I discovered the protective covering looks like HO scale sheet metal siding. I have a ton of this stuff that, I’ve saved up for my buildings.
Shoot me an e-mail off forum and we can discuss this further.I looked for your e-mail and came up dry.
Patrick
Beaufort,SC
Dragon River Steel Corp {DRSC}
Chad,
Heres a link you might want,in fact I’m pretty sure you want it…yup you need it.LOL
http://www.google.com/patents?q=hot+metal+mixer
Patrick
Beaufort,SC
Dragon River Steel Corp {DRSC}
Thanks Patrick. The link will really help when building the mixers. Could you post some pics of the siding and tell me where to get some. Check your PM’s in a minute.
CHAD