Mini Blast Furnances

At the risk of proving robert heinlein right, (experts will tell you why it can't be done) I would like to clarify the advantages of minimills and blast furnaces. and then ask you why you think that, metaphorically speaking, putting iron boots (blast furnace) on your racer (electric furnace) will help it win the race.

Minimll's chief advantage are low cost production of steel using recycled materials. These shops are in line processes, and require a minimum of infrastructure, transport, labor, and inventory on hand. They are flexible, can be stopped and started rather agilely, and require a minimum of infrastructure for support.

Blast furnaces require large quantities of raw materials, thus large investments in infrastructure, bulk transport, and labor.They cannot be easily throttled, and so must run continuously, and their product taken upon production. If you are proposing casting into pigs, you are giving up (waste) a lot of heat. If you are proposing a liquid metal connection, you are requiring a lot more capital and labor and tying your entire works to 24/7 365 production.

Economies of scale are taught in Economics, and the hybridization that you propose, in the absence of some local absolute advantage like High iron content ore at the site, and free coke, etc, will be cost disadvantaged by lack of scale. Just looking at lab analytical costs, the smaller batch size will mean that lab costs for analysis per ton will be higher than for a regular scale BF shop. Same for amortizing costs of stockyard (Land to hold all your raw materials), stockhouse, trestle, etc. etc.

The problem with coal injection is typically high sulfur pick up in the iron. Adding scrap to the burden typically results in decreased refractory life, plus can drive the residual chemistry out of control. Why do you think that adding scrap to the blast furnace will be cheaper than melting it directly in the EF? And if not, why do you want to do this?

Environmental protection costs- I won't even begin to broach that subject.

An advantage of having blast furnace iron available is the ability to dilute residual elements in the minimill electric furnace allowing the EF to run cheaper grades of scrap. But if you are adding the same high residual scrap in the Blast furnace, whats the point except a bit better dilution? What is your proposed burden regime?

If you are proposing a hot connection for blast furnace to electric furnace, you have just increased costs once again, and now will require 24 hour production at the electric furnace and caster... that means more crews and more expense for steel making, and expensive transport from blast furnace to electric furnace. Will you hold hot metal in mixers? Cost cost cost.

It will take a lot of cheap scrap savings to pay for the miniblast furnace.How much do you think you will save on scrap by being able to buy the cheapest grades because you will dilute residuals using iron? how does that compare to operating cost (not even capital cost!) of the mini blast furnace?

In an integrated works, the advantage of having a blast furnace with a sinter plant was the ability to recycle process metallic losses- scale- through beneficiation as sinter. This adds yet another huge cost to the proposal if undertaken, and it is doubtful that the minimill will produce sufficicient scale to make sinter production worth while.

I would ask you to to dollarize the proposed Benefits of having the blast furnace iron available, and then see how much of the needed investment that savings would cover. Figure then on 70% usage, as with the Chinese and everyone else in the world trying to dump steel in everyone else's market, you willprobably not ever get to 80% operating rate.

Much cheaper to buy DRI or other iron units from elsewhere where they have both absolute and comparative advantage, low cost natural gas, and economies of scale.

Your project just seems to be high cost- unless you have local advantages that make a compelling case like free coke, free labor, free iron ore, existing sinterplant and infrastruture etc. If you look at variability of steel market pricing and demand you will see the cost problem immediately.

You are looking at this as a technical problem, which is well and good, but the real problem is economics at both macro and micro level. Not Engineering.

My 2 cents. I have spent my lifetime in the steel industry and manufacturing. from sinter plant/ blast furnace labor to bar mill manager to pipemill lab manager and director of quality and technology for major integrated steel company here in the US.

It's costs, not technology.

milo