Mill Scale

Dunno, though it's probably good stuff to build roads with.

Recycling it into steel is first thought. Since it's a waste product most likely getting it cheaper then ore.

Per Wiki, it contains iron(II,III) oxide, hematite, and magnetite.

Mill scale is a rust coating that forms on the surface of newly cast or poured steel. In some cases the steel mill will encourage it to form a protective coating on the casting. The mill scale then is taken off during or before sent to the rolling mill, normally collected with roll coolants and greases. Historically it has been collected and sold to cement plants as an additive agglomerate and as the iron requirement.

Over the last several years the Chinese have been importing it to add to sinter feed, as it has been done in the US and in Europe, to enhance the quanitity of Fe in the feed stock and to utilize lower quality (less total iron iron ore). In China it is also added to pelletising feed stock for the same purposes.

Using mill scale should be carefully observed, however as the mill scale represents the product a steel mill is producing and will contain what ever is in the steel, good or bad, so care must be given to ensure procedures are taken to remove during melting or during treatment any material not wanted in the melt.

Mill scale is almost totally an oxide, Fe2O3, by the time it is collected and sent to the user. However it can be extremely high iron content Fe3O4 and perhaps FeO if it is collected dried and sent to the user immediately or agglomerated to reduce access to air or moisture.

will contain what ever is in the steel, good or bad
Yes! i did a XRF PMI on some mill scale and it was almost the exact duplication of that heat. The only element i cannot detect was carbon.

how does addition of mill scale to iron ore fines in sintering and pelletising help? what is the purpose can you explain in terms of calculations. say for example fe 50 iron ore fines and mill scale say fe 70 is added then what would be the outcome?how does it effect the fe(t)?

Because it is superior to Ore -- no other impurity except Oxygen! Bypasses the Iron making processes altogether.

They are just Cleverer.

Alternate filler for baby food and cat food instead of melamine!

In the 50's and early 60's I worked at US steel in Youngstown and they would take their Mill Scale off of Blast Furnace and send it to Alaska to make Concrete for USAF Runways ??

<would take their Mill Scale off of Blast Furnace>

Puzzled : Mill Scale OFF Blast Furnace ?

I meant to say slag not mill scale that is left in runs after the pour sorry

There have been some problems in the past if slags are used without control or treatment, in terms of chemicals. When using the term "mill scale" we need to know if only a hot rolling mill scale is considered or also minimill scale from EAF furnaces is considered. EAF "black" scale (fusion) is suitable for roads when used as filler (if crushed) or aggregates at certain percentage (15%), for making cement, and other, while "white" scale from the secondary treatement (deoxidation / kill) is just suitable for making cement but care must be taken for chemical composition more than using the black one. The rolling mill scale has several uses, not all of them openly known but used without treatment, just washed and pressed.

I'm a little surprised for reading blast furnace (and aditionals to EAF) scale being used without treatment, where the only direct use I know there, is just for making glass, because other direct uses have serious problems with chemicals and it's not posible in the EU. Maybe I didn't understand it well.

I'm not totally sure what practices the Chinese are employing in the use of mill scale. There first encounter with importing it was from South Korea and from what I could gather it came from the intergrated mills, therefore the steels in South Korea were made from Australian iron ore.

Then everyone got in on the activity and called everything that was left over from iron making or steel mills mill scale, until I started publishing what it was and where it came from and normally the general specs of what to expect when you bought it. It wasn't until about a year or two ago that US mill scale started to be a commodity worth more than $10 per ton to export it. Prior to that the only recycling of mill scale in the US was in the steel mills that had a sinter plant or as the Fe requirement in cement. The price soon went up to $50 at the plants then the cost of packaging and transport to China, around $100 delivered, based on Fe content. I think the price is still about that.

How the Chinese beneficiate it has not been published to my knowledge, but I would imagine they have all the grinders or roll presses and mag separators to go from there. Too bad we can't prepare it here as it would then be a very high quality feed and we could recycle a product that we have invested a few hundred dollars into.

From what I've seen the exporters are money people so they don't know the difference of mixing all the mill scale in one basket and sending it as a bulk material. That would sure beat the cost of transport instead of separating and putting it in drums. The amount from one mill is peanuts compared to a regional accumalation.

I believe there are a couple trains of thought about how to use mill scale in a submerged arc fce. One would be as a source of oxide to reduce carbon instead of oxygen. Another would be a source of Fe if it were combined with a carbon and self reduced in the melt. either way it could serve the purpose as a cheaper source of high quality Fe as compared to the price of scrap or DRI. The latter is the subject of a famous US patent. In this case other ingrediants could also be added to the mill scale/carbon particle. (also covered by the famous patent)

The yield of the mill scale addition would end up being about 90% +, the same as DRI/HBI.

The 3rd thought is: Cleverer Chinese using an enhanced version of Clever Romelt with just mill scale+coal dust .Amazing!

"In this case other ingrediants could also be added to the mill scale/carbon particle. (also covered by the famous patent)" in your above comment which other ingredient you are trying to highlight covered by the famous patent?

We came to know that in China mill scale is being recycled by the following process. They first grind the mill scale to some specific grain size then pass it to magnetic separator and then mix it in mixture with coal powder and some binder then make briquettes using hydraulic press and then these briquettes being used by foundries casting cast iron components in their coke fired cupola furnace called smelting reduction process. How about doing this in sub merged arc furnace along with sintered Iron Ore fines or non sintered and mill scale to make cast iron. If this can be done in what ratio must be sintered iron ore fines and mill scale should be use?

It would be interesting to know at what plant in China this is being done. As to the previous question what other ingrediants are added, the answer is whatever you want or need in the melt that can be added at the time.

And the answer to, this is the Romelt process, it is NO, it is not, as the Romelt process has been compared to other direct smelting process like Ausmelt or Hismelt, all those processes are very inefficient both in yield and in use of fuels they have not become commercially viable, of course in my view. No this is good ole American developed.

so smelting of iron ore fines and mill scale with reductants like pearl coke, steam coke , charcoal fines ,coke fines of fc around 55-56.can this be some what like romelt process. can this be put in submerged arc furnace ,if yes, then what mva of saf is best suitable ?

Need appoint Consultant :

China Russia SAIL India to start .

china russia india sail to start???

What in the world does that mean?

#22 ASKED:

• can this be put in submerged arc furnace ,
• if yes, then what mva of saf is best suitable ?

THESE need First hand Experience

Who are Best Experienced?

China-- we are all discussing them

Russia -- they were the 1st Announcers of the Process

SAIL of India ? see http://pib.nic.in/archieve/lreleng/lyr2002/rfeb2002/01022002/r010220026.html

I have not had first hand experience with a SAF but one of my colleagues does and he assures me that it will be no problem,

Why are we discussing China as the area to do this? They still can't make good tin cans. And as someone says they have already copied it and are doing it?

Russia-you say they were the first-to do what? Let me know the dates of smelting reduction technology and I will show you who has done it first.

Sail? Don't get me started.

Note that Mr Anonymous#22 <I have not had first hand experience with a SAF but one of my colleagues does and he assures me that it will be no problem>,

China-- you please note that too

Russia-- <http://www.metal2012.com/files/proceedings/metal_02/papers/100.pdf--- which says"The main suggested smelting reduction technologies without pre-reduction of burden
materials are Romelt, HIsmelt, AusIron. The Romelt process was the first of them to appear
and be developed [1,2]. The other technologies were declared later. Now they are approaching

the Romelt process principal scheme, keeping some individual peculiarities"

Re SAIL tcinc002 SAID IT ALL

The Romelt process was first published in 1993. I was working with some people from CRA evaluating their Hismelt process in 1990 when they were looking at combining my development to make the Hismelt more efficient. They went another way.

I later signed respective agreements with Ausmelt to evaluate both together. They also went another way. Both Hismelt and Ausmelt have not really commercialized since.

My patents were issed in 1989 and prior to that there was no real interest in smelting reduction. other than Corex. After 1989 everyone got on the bandwagon. You will find, I believe no publications until after 1989 that I know of.

The only development that included smelting reduction, but in steps and stages was Corex, developed jointly by Midrex and Korf and later sold to VAI by Korf. Corex was developed in the early 1980's.

Will you please send a link for us all to see the good work you had already done and published.

I wish you pushed it hard enough way back in 1990.

You can't keep such good work under wraps!

There is still time to Perfect it Brother!

Thanks for the thoughts. I don't have a link or website, too spendy for SS. I do have blank secrecy agreements and an email address. Google me and you will find a paper I published with some of the stuff in 2005 in Europe. Got lots of responses from that: Wonderful work, should revolutionise the steel industry, Doe people said it is the best thing since sliced bread, but DOE had no interest in a grant unless I was an academic or worked for USSteel. It showed AISI that their process wasn't going to do it so they poo-pooed mine, even with US Senator asst.

Built a plant in Venezuela at the FIOR plant. Had rave reviews. Don't know what it is doing now-Chavez owns it.

And I built it in 1990.

Did some work on making stainless directly from as-mined laterite and charcoal from forest fires, again rave reviews.

Broke my back, had 2 TIA's, a dozen heart attacks and open heart and 11 stents and 22 abdominal colon surgeries-look like hell but not in a wheel chair yet. Live on nitro.

And where have you been all my life? Got any money? Want to buy some stock? I'm not selling beachfront in AZ.

God Bless you

You saw it all ---- way back in 1990

Never Regret not being RECOGNIZED

We all suffer from this kind of Apathy from moneybags

They say "Nothing Succeeds like success"

How wrong !

SAIL ALONG WITH NMDC NEVER WENT AHEAD IN IMPLEMENTING THE PROJECT AND IT STILL IN THE PAPERS. THE PROJECT HAS BEEN SHELVED. SO WHAT DOES IT GOES ON SAY...ROMELT PROCESS... WHEREAS WE ARE SEEING SAF BEING USED FOR MANUFACTURING OF PIG IRON LIKE PRODUCT IS BEING MANUFACTURED FOR CAPTIVE USE. ANY TAKE IN THIS....

Yes, I am aware of the outcome of that Sail activity and romelt. It doesn't make any difference to me who did what first. As far as I am concerned the Romelt, Ausmelt and Hismelt are all the same technologies, using iron ore fines and coal fines directly by injection into a smelter, using too much carbon, excess offgas energy and other problems. And too much money spent on development with no commercialization as yet. Costs are too high, which also brings in Corex, with costs too high and power generation required to make it look good.

Using the SAF for making pig for inplant use means that perhaps there is a subsidy for power use. I don't know the details of the process or what the feed is. Would be interesting to find out.

well the details of making pig iron like product for captive use is by charging iron ore fines of fe 54-55 grade along with mill scale fe-68 along with pearl coke,steam coal fines ,char fines...in the saf and tapping it to use in induction furnaces directly.furnaces are kept smaller in size to avoid gas formation say 6.5 mva furnaces. power seems to b at around say 5 INR/kwh. to make it more efficient sinter the fines and charge them. What do you all say friends about this?....

to make it more efficient sinter

How Will Sintering make it more efficient. Please explain.

<furnaces are kept smaller in size to avoid gas formation say 6.5 mva furnaces. >

Gas can be controlled Recirculated

Heat loss can be Recuperated

What needs doing is trying out bigger bigger sizes after thorough Simulation and Computerised trend analysis by Thermodynamics , Solid/Liquid/Gas Phase change experts for months .Need a dedicated DO-OR -DIE teamwork!

Any Nation around??

Can you indicate the ratio of carbon to iron? And the ratio of slag to hot metal? Slag analysis? Do you get a lot of boiling? Any idea as to the off gas analysis?

can any one tell me who is the serious buyer of mill scale in china??

Good Day

I'm looking to source large quantities of mill scale if anyone on here can supplly.

peter@jittek.com