FROM A STONE IN THE GROUND TO YOUR FURNACE LINING
Eight chapters in plain English — how a quartzite rock becomes the lining that holds back 1,650 °C of molten steel, hour after hour, campaign after campaign. No jargon. No diagrams you need a metallurgy degree to read.
QUARTZ. NOTHING FANCY.
The story begins in the hills of Jharkhand and Rajasthan. We pick a stone called quartzite — one of the purest forms of silica (the same thing as sand and glass) found anywhere on earth.
Quartz happens to have a superpower: it can survive temperatures hotter than the surface of the sun's outer atmosphere and not melt. That's why steel plants line their furnaces with it. But not every quartz works — only the right purity. Below 97.5% silica, you start trading lining life for iron and impurities that ruin a campaign.
- What we look forSiO2 > 97.5%
- Iron contentBelow 0.20%
- AluminaBelow 0.30%
- Sourced fromJharkhand · Rajasthan
ONE STONE, THREE SIZES
The stone is crushed, washed, and sorted into three precise size ranges. Each one has a job.
Think of building a brick wall. The coarse grains are the bricks — they hold the shape. The medium grains are the mortar between bricks. The fine powder is the cement dust that fills the last tiny gaps. Together they pack so tightly there's almost no air left.
- Coarse · 3–5 mm15 – 18%
- Medium · 1–3 mm30 – 40%
- Fine + Powder · 0–1 mm45 – 55%
THIS IS RAMMING MASS
Mix those three sizes in a precise ratio and you get silica ramming mass — the product PSM Orechem makes and ships in 50 kg bags. It looks like coloured sand. It is, in fact, an engineered powder where every grain has been measured.
Why ratios matter: a wall built only of bricks falls down. A wall of only cement powder washes away. Get the ratio wrong and you waste a tonne of material to seal one small gap. We get it right before the bag leaves our plant.
WHY THREE GRADES, NOT ONE
Pure silica is brilliant at handling heat. But it needs a tiny push to fuse together on the first firing. That push is called a binder. The amount of binder you add changes everything — how forgiving the first heat is, how long the lining lasts, how much you can push the furnace.
We make three grades, each with a different binder strategy. There is no "best" — only the right one for your plant.
No binder added. The sintering happens naturally from heat and pressure. Cleanest material, but the operator must control the first heat carefully — if you rush it, you regret it for the rest of the campaign. Best for plants with deep furnace expertise.
A small dose of boric acid is added. On the first heat, the boric melts at a lower temperature and forms a glass film that bonds the silica grains together. Easier to sinter, more forgiving on the first heat. The go-to grade for most plants running mild and carbon steel.
A boron compound that gives the strongest, most uniform glass-phase bond. The lining sinters into a denser, tougher body that resists slag attack better. Result: more hours per campaign, less downtime, lower cost per tonne of steel. Best for high-output and high-frequency furnaces.
RAMMING THE LINING
An empty induction furnace is just a steel shell wrapped with a copper coil. To melt steel, the inside needs a protective barrier — that's the lining.
Workers lower a steel template (called a former) into the furnace and pour our ramming mass between the former and the casing. They ram it down with pneumatic tools — pour, ram, pour, ram — until it's a single monolithic body. Thickest at the floor, around 6 inches at the lower walls, tapering to 4 inches near the top.
The former stays in place. On the first heat (you'll see it next), the furnace cures the lining around the former. Only after sintering is complete is the temperature raised further — and the former itself melts away, becoming part of the very first batch of steel. The lining is now hollow, perfectly shaped, and ready to work.
THE FURNACE COOKS ITSELF
Before the furnace can ever touch steel scrap, it has to cure its own lining. This is called sintering. It's the most important step of the entire campaign — get this wrong and the whole lining is compromised.
The temperature is raised slowly over several hours. As it climbs, the binder melts and forms a glass film that bonds the silica grains. The loose powder turns into a single rock-hard ceramic body. Boron and boric binders make this stage smoother — the glass film forms earlier and more uniformly. By the end of sintering, the lining is no longer powder. It's stone.
- Ramp time4 – 8 hours typical
- Peak temperature1 500 – 1 650 °C
- What happensPowder → ceramic body
- If rushedCracks, short campaign
THREE FACES IN ONE WALL
Silica is a chameleon. Its atoms rearrange themselves at different temperatures. In a working furnace, all three states exist at the same time — stacked like layers of a sandwich, each one doing a different job.
The face that actually touches the molten steel becomes glass. Silica atoms break out of their crystal pattern and lock into a smooth, dense, glassy surface. This is what holds the metal back. It is also self-healing — minor cracks fuse shut at operating temperature.
Behind the glass face, the silica has rearranged into tridymite and cristobalite — two crystal forms that pack tighter than ordinary quartz. The grains have fused into a single dense ceramic with almost no porosity. This zone gives the lining its mechanical strength.
The back of the lining stays cooler and stays as α-Quartz — the original loose-packed grains. This zone is the thermal-flex buffer. When the furnace heats and cools between heats, the lining expands and contracts. The buffer absorbs that movement so the rigid sintered shell doesn't crack.
HOUR ONE. HOUR FIFTY-FIVE.
Now the furnace is alive. Hour after hour, steel scrap goes in, melts, gets tapped — poured out into a ladle and onto the casting line. The empty furnace gets charged again. Repeat.
Each hour wears the lining a fraction of a millimetre at the slag line — where the floating slag chemically attacks the silica. A quality PSM Orechem lining gives you up to 55 hours of campaign life. After that, the slag line has thinned enough to be risky. Time to drop the bottom and re-ram. Watch the counter tick below.
TRACK IT ALL WITH FURNEX
Every hour of sintering. Every heat after that. Every kWh and rupee per tonne. FURNEX — our AI-powered intelligence platform — tracks the lining of every furnace in your plant, calculates true cost per heat, and predicts the number of heats you'll get for any given supplier and charge mix — trained on real Indian plant data. Stop guessing. Start acting.
- See
Live overview of every furnace in your plant, on web and mobile. - Measure
True cost per tonne & kWh per tonne, calculated every heat. - Predict
AI tells you how many heats you'll get from any supplier & charge mix.