tdmidget "Somebody with more experience can probably correct me" That might be me. I spent 25 years in the scrap business. Contaminants do not "burn" out but most can be removed. Carbon, of course, is critical but nowadays can be added by coke injection or removed by blowing air or oxygen through the melt. Sulfur, Phosphorous, and Chromium can be removed by fluxing with limestone. The problem contaminants are copper and nickle. To reduce the level the mill must dilute it. The best practice is to buy from reliable sources such as large scrap procesors. These yards will be equipped to shred mixed items such as electrical appliances , switch gear and the like so that the metals are separated and recovered.The most common problem, electric motors, are worth enough that they can be separated and sold as an item. Nickle might come from aaaaarmor plate, not that common, and some tool steels. Again the sophisticated yard will separate these for sale as a more valuable item. High scrap prices bring all kinds of wannabes into the business and their lack of experience and priciples lead to low quality. In addition since the mid 1980s when the length restrictions were removed on trucks some new product moved to trucks. previously 50 and 60 foot items moved almost exclusively by rail. Mills wanted scrap by rail as that assured a supply of eqiipment for their products. That coupled with the ridiculous PSR fad were the name of the game is drive customers away leads to these newbies and amateurs being able to deliver by truck and so lower quality scrap will get in. Melt shop people know what they are doing so I doubt that it is a big problem.
"Somebody with more experience can probably correct me"
That might be me. I spent 25 years in the scrap business. Contaminants do not "burn" out but most can be removed. Carbon, of course, is critical but nowadays can be added by coke injection or removed by blowing air or oxygen through the melt. Sulfur, Phosphorous, and Chromium can be removed by fluxing with limestone. The problem contaminants are copper and nickle. To reduce the level the mill must dilute it. The best practice is to buy from reliable sources such as large scrap procesors. These yards will be equipped to shred mixed items such as electrical appliances , switch gear and the like so that the metals are separated and recovered.The most common problem, electric motors, are worth enough that they can be separated and sold as an item. Nickle might come from aaaaarmor plate, not that common, and some tool steels. Again the sophisticated yard will separate these for sale as a more valuable item.
High scrap prices bring all kinds of wannabes into the business and their lack of experience and priciples lead to low quality. In addition since the mid 1980s when the length restrictions were removed on trucks some new product moved to trucks. previously 50 and 60 foot items moved almost exclusively by rail. Mills wanted scrap by rail as that assured a supply of eqiipment for their products. That coupled with the ridiculous PSR fad were the name of the game is drive customers away leads to these newbies and amateurs being able to deliver by truck and so lower quality scrap will get in. Melt shop people know what they are doing so I doubt that it is a big problem.
tdmidget - Thank you for your insightful reply. I was thinking of those processes when I said "burned out", but I also see how that is absolutely the wrong way to describe it. I was thinking of removing impurities like you described, but nickel and copper hadn't occurred to me. That really does emphasize how important good scrap dealers are.
I recall once there was concern about radioactive scrap making it's way into steel. Is that still a concern?
Also, with your experience, do you know why the large variance between scrap prices and new steel? The round solid I bought from a fellow blacksmith for $0.40/lb was quoted at $1.60/lb new, but the local scrap yards are only offering $0.08/lb for the same if I tried selling it.
Paul F
MidlandMike Murphy Siding When they start with iron ore, don't they have weed out stuff they don't want? The iron ore is milled to a powder finer than talcum, and then goes thru a flotation process that separates the metalics from the country rock. The concentrate can be mixed with clay in a kiln to form taconite pellets. Knowing the composition of the mines output, steel companies can choose which mine to buy from.
Murphy Siding When they start with iron ore, don't they have weed out stuff they don't want?
The iron ore is milled to a powder finer than talcum, and then goes thru a flotation process that separates the metalics from the country rock. The concentrate can be mixed with clay in a kiln to form taconite pellets. Knowing the composition of the mines output, steel companies can choose which mine to buy from.
Thanks to Chris / CopCarSS for my avatar.
I guess American steel producers don't get much scrap from the Alang shipbreakers in India. I would guess the scrap from shipbreakers would be of a rather high quality. Maybe even higher quality if it war vessels being scrapped.
Never too old to have a happy childhood!
Murphy SidingWhen they start with iron ore, don't they have weed out stuff they don't want?
ClassAbut from what I understand, even with recycled scrap, the process burns out most additives in the scrap metal
"burns out" is where my confusion comes in. That explanation might make sense as far as the body that got cubed into the Lincoln in James Bond's "Goldfinger"....
What I find myself wondering most about are property determining alloys. Some alloys are added to enhance threadability for example, while others to create hardness. At the temperatures necessary to melt the work, it's not like you can just pick the right solvent, as you can in a chem lab, to wash out the undesirables.....at least I don't think you can.
Somebody with more experience can probably correct me, but from what I understand, even with recycled scrap, the process burns out most additives in the scrap metal. They have to then add back elements to get the alloys they desire from the melt. It is then poured and rolled to final stock.
Which is why the disparity between scrap prices and new steel is interesting to me. It implies to me that the bottleneck is in the mills, not in feedstock.
NYC-Ohio bogie_engineer Both American Steel Foundries and Bradken (formerly Atchison Castings, Rockwell, and LFM) make all their steel castings for freight car trucks, couplers, draft gear end sills, and locomotive truck frames and all their other products by melting scrap. They are selective what they use and produce high quality alloys of whatever chemistry is required by the customer. A lot of the scrap is railroad wheels. Dave I spent 3 years working at a cast iron foundry, the primary customers were rail (including ASF). 99% of the raw material was scrap, but EVERY single melt was analyzed via spectrograph as to content and adjusted as needed. I would suspect it is the same for every steel producer as well.
bogie_engineer Both American Steel Foundries and Bradken (formerly Atchison Castings, Rockwell, and LFM) make all their steel castings for freight car trucks, couplers, draft gear end sills, and locomotive truck frames and all their other products by melting scrap. They are selective what they use and produce high quality alloys of whatever chemistry is required by the customer. A lot of the scrap is railroad wheels. Dave
Both American Steel Foundries and Bradken (formerly Atchison Castings, Rockwell, and LFM) make all their steel castings for freight car trucks, couplers, draft gear end sills, and locomotive truck frames and all their other products by melting scrap. They are selective what they use and produce high quality alloys of whatever chemistry is required by the customer. A lot of the scrap is railroad wheels.
Dave
I spent 3 years working at a cast iron foundry, the primary customers were rail (including ASF).
99% of the raw material was scrap, but EVERY single melt was analyzed via spectrograph as to content and adjusted as needed. I would suspect it is the same for every steel producer as well.
I had the opportunity to watch an electric steel mill in Lemont IL. start a "melt" and it is impressive. Carbon rods that are below a "lid" fed by about 12 large (4" dia.) cables that start dancing like junp ropes as the lid is lowered into the crucibe and contact is made with the scrap metal. and the sound and vibration is fear inspiring.
The Mesabi Nuggets plants in Minnesota were shut down during the last Iron Ore price crash. Even though Iron Ore prices have rebounded I haven't heard that the plants have reopened.
Add the word 'processing' to your 'iron nugget' search and all sorts of things appear.
https://www.energy.gov/eere/amo/itmk3-high-quality-iron-nuggets-using-rotary-hearth-furnace
Ten or 15 years ago I heard about iron nuggets as an alternative to taconite pellets. They were also processed near the iron mines. They could be used in mini-mills, and seemed to be set to remake the steel industry. However, that doesn't seemed to have happened. Now when I google "iron nuggets" I find there is a computer game involving iron nuggets, and it's hard to find links to actual industrial topics.
UlrichNucor as a whole is a top notch company in terms of how they operate.
I suspect that it is crucial for a responsible recycler to understand both his sources as well as his customer's needs.
Many of us likely think of recycled metal as a product of those free lance scrappers who drive their pickups down our alleys a half hour ahead of the garbage trucks, piling high everything from bicycle frames to bed posts.
When in reality many are sourced directly from machine shop mill tailings and such, where the composition is fairly reliable.
Convicted One CSSHEGEWISCH only common courtesy kept him from getting profane about the quality of their product. I was always of pretty much the same opinion, believing that the recycled steel was good mostly for lawn furniture and the sort. But I soon gathered critics who claimed that considerable effort was put into classifying and sorting the scrap, by content. I still don't think that I would relish having my motorcycle frame made from someone's old swingset.
CSSHEGEWISCH only common courtesy kept him from getting profane about the quality of their product.
I was always of pretty much the same opinion, believing that the recycled steel was good mostly for lawn furniture and the sort. But I soon gathered critics who claimed that considerable effort was put into classifying and sorting the scrap, by content.
I still don't think that I would relish having my motorcycle frame made from someone's old swingset.
We move about 15 thousand loads a year for various Nucor mills. Beams, channel steel, and of course coils. Its a very high quality product.. which explains why they're the largest steel producer in the US albeit steel made from recycled scrap. Nucor as a whole is a top notch company in terms of how they operate.. how they treat their employees and vendors.
I recently was pricing steel for a power hammer build and the costs for new steel are outrageous. But what's really interesting is that scrap prices haven't risen along with the cost of new steel. So it does seem that there is a demand for new steel produced from ore and that scrap steel isn't able to make up the difference in demand.
Why not? Some people would make a motorcycle frame from swing set tubing straight away - without recycling/remanufacturing it through a steel mill. There are people that think exhuast tubing is suitable for safety cage construction in race cars. I am not one of those people.
There are a multitude of grades of steel that each have specific uses. Use the wrong grade for the wrong purpose and disaster is not far behind.
Iron ore can't be much used in an arc furnace because the furnace depends on the contents to electrically connect the electrodes. Iron ore is not a conductor. Scrap iron and steel are. So is "fresh" iron and steel.
Arc furnaces were first used to make the highest quality steel.
The one that was around here was closed in 1991. I know they produced rebar. I don't know what else.
Ed
CSSHEGEWISCHonly common courtesy kept him from getting profane about the quality of their product.
Many years ago, I mentioned Nucor Steel to the father of the woman I was dating at the time. He was a structural engineer and only common courtesy kept him from getting profane about the quality of their product.
Some integrated steel producers (primarily Republic Steel) had electric furnaces at their mills which produced steel from carefully selected scrap. It's not a new procedure.
It likely depends on what the metalurgist wants. I don't pretend to be a metalurgist, but I believe that even using recycled steel allows for making some adjustments in the final product.
Larry Resident Microferroequinologist (at least at my house) Everyone goes home; Safety begins with you My Opinion. Standard Disclaimers Apply. No Expiration Date Come ride the rails with me! There's one thing about humility - the moment you think you've got it, you've lost it...
I understand that there are some grades of steel that require blast furnace produced iron. Taconite pellets from a single source can be fairly uniform and of known composition. Scrap may contain many alloys.
I believe there is more demand for steel than just processing scrap can provide.
NUCOR mini mills are based on extensive use of scrap metal in electric arc furnaces. Cleveland Ciffs just bought a huge stake in AK Steel and plans on using its Minnesota Irom money to create a all American vertical intrigrated operation. I was always assumed that Virgin iron ore was better aka Taconic pellets. But perhaps scrap metal takes less energy to process.I still saw long trains of ore in Duluth-Superior when I was there last year so some mills still use it and I hear that China is buying out our metallurgical coal & scrap metal
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