Thursday, March 19, 2015

Blast Furnace Overview and Some General Steel Mill Videos

So far, I have avoided the iron and steel industries because I'm still so far behind on other industries. But I came across a diagram of an 1886 Blast Furnace in the CB&Q archives of the Newberry Library that records that blast furnaces where 80 feet tall in 1886. It also records some Newberry links for future reference. The diagram is from a report on steel rails.

I don't have notes on the entire steel making process, so I'm parking this idaillinois flow lines diagram here for now. And a picture story of steel

North Chicago 1885 #1-4 blast furnaces I think this was the precursor to Illinois Steel that was on Goose Island.

And these notes record general information on how a blast furnace works.
10:21 video  Open Hearth era
18:06 video  BOP, EAF and continuous casting era

Diagram from CB&Q Technology from Newberry Railroad Archives
Cross Section of Modern 80 foot Blast Furnace


John Slowikowski shared

Craig Holmberg commented on John's share

Angelo Tessaro posted three diagrams showing the evolution of the blast furnaces at a plant in Belgium. A tonne is a metric ton, so that is 1000kg. The improved efficiency of coke consumption would be one reason why they kept making them bigger.



Metallurgical engineering posted
Blast Furnace Chemical Reactions 
Pankaj Singh shared
Metallurgical engineering posted
Blast furnace: Production of hot metal(Pig iron)
In the Blast Furnaces (BF) liquid iron (popularly termed as ‘Hot Metal') is produced by the process of reduction at high temperature from raw materials like iron ore, base mix, sinter, coke, fluxes (limestone/quartzite), etc. &also air blast / O2. In a blast furnace, the process is also known as the “Countercurrent process” as solid raw material is being charged from the top and hot air is being blown from the bottom. During the process the impurities are removed in the form of slag and hot metal is produced. Coal is being injected to reduce the consumption of the main fuel coke which is a cost reduction measure. Liquid metal and slag are being separated in the area known as the cast house. The liquid Hot Metal is transported in Hot Metal Ladles / Torpedoes to the Steel Melting Shops (SMS) for the production of steel by the process of oxidation of the Hot Metal in specially designed Convertors. Sometimes the Hot Metal is poured in the Pig Casting Machine (PCM) to produce Pig Iron. Slag produced is granulated by high-pressure water jets in the Cast House itself or sent to Slag Dumping in the Slag Pots.
Credit:- Matteo Sporchia
Pankaj Singh shared
Daniel Barron: I worked around EAF's and casters in my career. I have a question. How do you determine the level of liquid and slag in the blast furnace? How do you determine when to tap the slag & hot metal? We used radiation sources to determine the level of molten steel in the molds on the caster.
Bert Pass: Daniel Barron I believe it is done by monitoring blast pressure. If it increases over a normal threshold, they know when to tap.
Metallurgical engineering posted
The blast furnace is a counter-current gas/solids reactor in which the descending column of burden materials [coke, iron ore and fluxes/additives] reacts with the ascending hot gases. The process is continuous with raw materials being regularly charged to the top of the furnace and molten iron and slag being tapped from the bottom of the furnace at regular intervals.
Key steps of the process are as follows:
1. upper part of the furnace - free moisture is driven off from the burden materials and hydrates and carbonates are disassociated.
2. lower part of the blast furnace shaft - indirect reduction of the iron oxides by carbon monoxide and hydrogen occurs at 700-1,000°C.
3. Bosh area of the furnace where the burden starts to soften and melt - direct reduction of the iron [and other] oxides and carbonization by the coke occurs at 1,000-1,600°C. Molten iron and slag start to drip through to the bottom of the furnace [the hearth].
Between the bosh and the hearth are the tuyeres [water cooled copper nozzles] through which the blast - combustion air, preheated to 900-1,300°C, often enriched with oxygen - is blown into the furnace. Immediately in front of the tuyeres is the combustion zone, the hottest part of the furnace, 1,850-2,200°C, where coke reacts with the oxygen and steam in the blast to form carbon monoxide and hydrogen [as well as heat] and the iron and slag melt completely.
Molten iron and slag collect in the furnace hearth. Being less dense, the slag floats on top of the iron. Slag and iron are tapped at regular intervals through separate tap holes. For merchant pig iron production, the iron is cast into ingots; in integrated steel mills, the molten iron or hot metal is transferred in torpedo ladle cars to the steel converters. Slag is transferred to slag pits for further processing into usable materials, for example raw material for cement production, road construction, etc.
Paul Pritchard: What is the time period from when the raw material is placed in the top until it exits out the bottom as molten iron ?
Joost Groen: Paul Pritchard Between 6-8 hours.
Pankaij Singh shared

Interesting comments about dumping the iron during a strike because of the difficulty of properly shutting down a blast furnace

Richard Allison provided a summary of the big blast furnaces built in the US as a comment on a post.
My logic is that ET has continued being inland and profitable as per USS but sending ore a little further to the Bethlehem plants is not much further. Sparrow's Point is a catastrophe in which was not a lost cause but it was bled dry. Ore could have been gotten from Brazil and ore could have also come from Nova Scotia or the Great Lakes. I stood on the casthouse of L Furnace when it was built and was in awe of the magnitude of this furnace. I wish I still had my helmet sticker there but never I thought it would have disappeared in only 30 years. I never made it to Madline No.7 at now CC but did go to the former USS Gary 13 and now 14 and the USS Fairfield No. 8, the most modern furnaces in the US and L Furnace and No.8 did not survive even though all built in the late 1970s. Old furnaces seemed still go on with 120 or so blast furnaces in the 1980s to around 16 or 17 running today. I guess finances do not always follow logic in the steel industry today or in the past.
I need to do more research to find where these blast furnaces existed.

27:01 video of "mighty machines" in a steel mill It is designed for kids, but it is still informative.

Someone posted the question of how does a blast furnace work. John Hawkins provided a succinct answer:
Basically you put a mixture, called burden, of iron ore pellets, coke, limestone in the top.
The blast furnace gas coming off the top is collected, cleaned, cooled and applied to a stove to heat the checker brick inside.
The power plant has a huge steam turbine driven air compressor sucking in air, (cold blast) that is applied to a hot stove in a reverse flow of the heating process. The cold blast pulls the heat out checker brick and this "Hot Blast" is applied to the burden.
You have at least three stoves, while one is "on Blast" applying the Hot Blast to the Fce., the other two are "on gas" reheating the checker brick.
You tap the Fce at the bottom on a regular basis and out comes heavier molten iron with lighter slag floating on top.
There is a dam with a hole in the bottom in the iron trough. The heavier iron goes through the hole into the iron runners and into bricked lined iron ladles.
The lighter slag with the impurities is skimmed off and via slag runners goes into a slag pot or pits for recycling.
The iron ladles go to a BOF to be converted from molten iron into molten steel.
And this 4:15 video was offered as another answer.

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