Iodine 1000 vs 1100: feedstock, steam and yield
Going from iodine 1000 to 1100 is a trade of yield for surface area: about 0.3–0.5 t more steam and 0.3–0.4 t more shell per tonne, output down 7–10%, roughly USD 60–90/t in total. Includes a feedstock ceiling table, a per-tonne cost build-up and the premium threshold that decides the order.
The short answer: you are buying iodine with yield
Moving from iodine 1000 to 1100 adds roughly USD 60–90 per tonne of product, which is 5–8% of a USD 1,200/t selling price. Below a 6% premium the order loses money on every tonne; 8–10% is where it becomes worth scheduling.
The mechanism is simple. Iodine number measures how much iodine the pore system takes up. To reach 1100 you have to burn more carbon away. The carbon that leaves opens new pores, and it also leaves as CO and H₂ in the off-gas. Every point of iodine is paid for in yield — there is no free tier.
Rank the three accounts by size: feedstock decides whether 1100 is reachable at all, yield and throughput dilution decide what it costs to make, steam and power decide the running bill. Get the order wrong and the usual mistake is quoting on steam alone while missing the two larger items.
All figures below follow the ranges published on this site: activation zone 850–1100 °C, product iodine 950–1150 mg/g, steam consumption 1.5–2.2 kg/kg, carbonization yield 28–34%. The per-item breakdown of consumption is in power and fuel per tonne.
Account one: the feedstock decides whether you can offer 1100 at all
| Feedstock | Published iodine range | Verdict on 1100 | What to do |
|---|---|---|---|
| Coconut shell | 950–1100 mg/g | Ceiling sits right at the line; possible, but only at the top of the operating window | Trial first; sign only if it holds above 1080 |
| Hazelnut shell | 900–1050 mg/g | Not reachable on a normal recipe; needs temperature and steam pushed hard, with a bigger yield penalty | Quote only if the buyer accepts ±50 |
| Palm kernel shell | 900–1000 mg/g | Not reachable from a single feedstock; this is not a tuning problem | Change or blend the feed, never promise 1100 on PKS alone |
| Coconut blended with PKS | Moves with the ratio | Adjustable, but batch stability gets noticeably worse | Fix the ratio, keep retention samples, write the ratio into the contract |
Account two: 0.3–0.5 t of extra steam buys you a 7–10% output cut
Raising steam from the middle of the band (1.5–1.8 kg/kg) to 2.0–2.2 kg/kg is the cleanest lever: temperature stays put, the lining is untouched, you simply burn more steam. On a 1 t/h line, a 0.4 kg/kg increase means 0.4 t/h of extra steam, which usually pushes the boiler up one size and lands straight in the per-tonne cost.
The real price is residence time. To keep the carbon in the activation zone longer, the same furnace has to produce less: a 1 t/h line making 1100 typically runs at 0.90–0.93 t/h (depending on furnace type, fill level and feed size). That loss never shows up on the power bill — only on the monthly output sheet — so it is the item most often left out, and it is usually the largest of the three.
The third route is temperature, walking up from 850–950 °C toward 1050–1100 °C. Iodine climbs fast, but three things climb with it: thermal shock on the lining, ash content, and a drop in strength and bulk density. A rotary kiln lining normally lasts 3–5 years; running permanently at the top of the window pulls that toward 3 years, and a reline takes 10–15 days. The lost production usually costs more than a full year of extra steam. Furnace differences are covered under rotary activation furnace.
The three accounts on one per-tonne sheet
| Cost item | Iodine 1000 | Iodine 1100 | Delta per tonne | Example unit cost |
|---|---|---|---|---|
| Shell consumed | 6.1 t | 6.5 t | +0.4 t | USD 125/t → +USD 50 |
| Steam | 1.7 t | 2.1 t | +0.4 t | USD 20/t → +USD 8 |
| Power (fans, drives) | baseline | +3–5% | +3–5 kWh | USD 0.09/kWh → +USD 0.4 |
| Throughput dilution | 1.0 t/h | 0.90–0.93 t/h | −7–10% | fixed cost USD 180/t → +USD 15 |
| Total | — | — | — | +USD 73/t (range 60–90) |
Account three: does the price cover it? Two numbers decide
- Premium threshold: USD 60–90/t on a USD 1,200/t product is 5–8%. Quote at 8–10% to leave room for test disputes and batch variation. At 6% you are betting the entire margin on the buyer not rejecting the lot.
- Retest three properties: strength, bulk density and ash, every time iodine goes up. If any of them falls outside the specification, the 1100 is wasted — customers use strength and adsorption rate in the column, not the number on the label. Which tests belong in acceptance, and how to write tolerances, is in which tests belong in acceptance.
- Contract tolerance: write ±50 mg/g, not ±30, unless your furnace holds the same point for three shifts straight. A 1100 batch reading 1050 in the customer's lab is normal; a hard 1100 in the contract is a rejection clause you wrote against yourself.
- Run both grades: one line making 1000 and 1100, volume on the high-yield grade and premium on the low-yield grade, with grade changes batched. Plants that switch entirely to 1100 usually earn less — they gave the volume business away.
Do not use temperature as a substitute for steam
Temperature is the fastest knob and the most expensive one. Every 50 °C buys iodine quickly, but it also buys lining wear, ash and strength loss — and none of that appears on the monthly cost sheet. Move steam and residence time first, keep temperature in the middle of the 850–1100 °C window, and the line will survive a full lining campaign.
Five steps before you accept the order
1. Lock the feed batch
One supplier, one origin, one moisture band. Run a 200 kg trial. Do not trial on mixed stock — the number you get will not reproduce.
2. Change one variable at a time
Add steam first without touching temperature. If that is not enough, extend residence time. Temperature last. Change all three and you will not know which one caused the result.
3. Log three consecutive shifts
Steam, output and iodine every shift. What matters is the standard deviation, not the peak. Peaks make samples, not shipments.
4. Recalculate with your own data
Put measured steam and output into the table above. Quoting from the example values in this article will almost always come out low.
5. Sign tolerances before scaling up
Tolerance, sampling method and arbitration go into the contract first, volume second. Reverse that order and you finish the negotiation by cutting price.
The trade-off in one line
1000 is a commodity grade; 1100 is a specification grade. Commodity competes on cost and delivery, specification competes on consistency and paperwork. Running both on one line is a scheduling discipline, not a process secret: keep grade changes to a minimum and the USD 60–90 increment comes back.
There is also a more common case: you cannot yet hold 1000 consistently. When batch variation exceeds 50 points, raising the specification only raises the reject rate — the customer returns the lot, not the average. Fix sampling and testing first. On a plant where the measurement is not stable, process discussions are noise.
Related notes
Send the raw material, target tonnage and finished spec. You get a configuration, a utility schedule and a budget range — not a brochure.