Some New Technologies for Steel Reinforcement Bars

Ministeel Plants in India are comparatively of small capacity with an average annual production capacity of 100000 TPA to 300000 TPA. The capital cost and running cost are very high for these plants because the technology available in India for converting the liquid steel to final products are still expensive.

There are many smaller plants in India with 5 to 6 T melting furnaces which can produce about 60 TPD. These are closed mainly because production costs are high and. With the proposed process here, we can make these small plants profitable.

Reinforcement bars (TMT bars) – a comparison conventional vs proposed process

Conventional process	Proposed process	Remarks
Liquid Steel	Liquid Steel	Consider the process of melting and getting the metal ready for continuous casting the same.
50000 - 60000 TPA	50000 - 60000 TPA	Consider production capacity same.
Continuous caster – 100 mm sq billets	Continuous caster – 20 mm dia rounds The casting is a double process of casting and rolling. Effective casting starts with 36 x 36 square. But the process is such that the output size is 20 mm dia round.	Cost of casting is more in conventional process mainly because of cost of mould. The saving will be about Rs. 50 per T. The 20 mm dia round has already undergone hot rolling with 4 times reduction.
Reheating in most plants , but in some new plants direct rolling without reheating is being done.	No reheating	Complete reheating cost will be saved – almost to the tune of about Rs. 2000 per T. Many plants use pulverized coke for reheating which cost them about Rs. 700 to 800 per T
Hot Rolling from 100 mm sq to 8 to 12 mm	Hot  rolling from 20 mm to 8 to 12 mm Effective hot rolling is from 36 mm sq to 8 to 12 mm round	Electrical energy saving will be about 70 kwh per T, which is about Rs. 400 per T
Since the hot billet is cut to 6 m or 3 m, each billet will have head cut and tail cut twice during rolling.	Since it is continuous endless rolling, no head or tail cut is required	Yield improves tremendously
There is scale loss in the furnace and more exposure	Practically no scale loss	Yield improves further
TMT	TMT – less water required since speed is less.

Almost 4 million units of electricity and 1.5 million litres of fuel oil per annum is saved. Plants with 5 to 6 T furnaces which are closed due to non-profitability can be restarted and made into profitable ventures. Considering the savings involved, this is definitely worth pursuing.

If more production is needed, we can have two strand or 3 strand caster and two or three strand rolling mills.

One doubt being expressed is whether we can get the qualities required by rebars or other applications, because the area reduction in hot rolling is less. But in this process, part of the rolling takes place during casting itself. As we pour the metal to the caster rolls, when the solidified section above what we call the kissing point of the rolls, is around 36 x 36, and after that to 36 x 15 oval and then to 20 mm round, it is getting rolled. So the actual reduction for a 12 mm dia rebar is 36 x 36 / 108 = 12 times and for 16mm dia rebar is 36 x 36 / 192 about 7 times. This reduction is actually enough for the bar to get the required properties. On a crude pilot machine for trials, we have already made 36 x 15 oval.

Apart from TMT bars, this process can produce plain round bars upto 16 mm dia for making bright bars.

The same machine can produce strips as thin as 3 to 6 mm, about 40 to 60 mm wide. These strips have many applications such as GI earthing strips, cable trays etc.

Further Development works

We do not intend to stop here. There is much more work that can be done. Our next plan is to develop a high reduction rolling mill stand to roll 20 mm to 6 – 16 mm dia in just one stand. Adding another finishing stand can get a finished product in just 2 stands. There are mills like the planetary mills which reduces 55 mm thick slab to 3 mm thick sheet in one stand, and if we sensibly apply this technology to rounds, it looks a real possibility.

Anybody who is interested may please contact A K Narayanan at akn@nyanzengg.com or call +91 7895623546. We have a detailed project report with all the preliminary drawings and techno economic feasibility, ready with us.

Engineering Education

When did one start learning engineering?

My theory is, almost immediately after you are born, I think. Shaking your hands and legs is a starting point of learning motion control. Crying out loud, you start learning about sounds.

Then slowly you start learning about cause and effects. Manipulating the motion controls, you learn to flip over, move crawling, and then move on your hands and knees. Then you graduate to stand on your two legs, walk and run. You know you can cause your elders always on their toes to keep certain things out of your reach and then you start to learn to go and get them, either by jumping up or climbing on a chair. Then you learn that the chair can trip and you can fall.

From sound also, you start relating the cause and effect. If you need something you know you can get it by shouting, howling or simply crying out loud. You can use both motion control and the howling together to get me the result.

A little further grown up, you learn about gravity by jumping up and find that you do fall down. You learn about projectiles when you throw stones and you learn how to control them to bring down the mangoes from tree.

You run and learn speed; you kick a ball and learn force, distance and power; you kick a wall and learn about action and reaction; you swim in water and learn buoyancy.

All right, you don’t know all these names at that time – but one of the major points that is learnt is the cause and effect.

Then in the school and through college you start learning physics and mathematics and start relating whatever engineering principles you have learnt from experience to the physics and mathematics you are learning.

Until this time, the learning of engineering was exciting. But when precision works and mathematical equations enter into it and when you start engineering ‘education’, it starts getting a bit beyond your liking and understanding.

Then some start learning all those in the earnest and some start mugging up – because examinations are to be passed and they cannot be wished away.

All engineering colleges are not equally equipped to learn things practically and relate it to the theory that you have learnt. So there is actually a gap between the knowledge gained over the years and the employability.

So, it is necessary to have a refresher course to cater to the exact requirement of your employer specializing to the needs of the plant.

My joining a course of engineering diploma after my matriculation was quite accidental. Just join any course and learn a skill to get a job was the only thought in my mind and just landed up this course.

After I passed my engineering diploma, I did teach in a polytechnic – incidentally the same  as I had passed from - as an instructor for about 8 months, but soon I realized that before teaching anyone you must have a fairly good knowledge of what you are teaching. When your student asks you a question other than from the notes, you should be able to know at least where to look for the answer.

So I gave up teaching for the time being and joined the industry – it just happened to be the steel industry.

ENGINEERING MUSINGS

Just to introduce, this is intended to be a blog to get engineering ideas discussed for improving performances in all types of industries. Personally, I would be talking more about steel industry, I suppose. But I will try to cover other industries as well. 

Sometimes a good discussion would also help and I would request readers to participate.

Again, to introduce myself, I am Narayanan, basically an electrical engineer, with some experience in mini steel plants - all in all, a little more than 50 years - in India as well as a couple of other countries.

I feel pleased and I am looking forward to share my experiences, which hopefully would help some engineers