Calcined dolomite for steel is a burned product. The shop is asking for dolomite that has already lost its carbon dioxide, so the charge is an oxide rather than a carbonate. A refractory buyer is usually asking for the same family taken further: a dead burned grain that will hold up in brick, doloma, or a gunning mix. Raw stone cannot meet either brief. It still carries the carbonate, and the loss on ignition, the mass, and the way the material behaves in the vessel or the press are not what those sheets describe.
The comparison between the stone and the burned product is in calcined dolomite or raw dolomite. This note stays with the buyers who already know they need the calcined side: steel mills and refractory plants. Lime is a different flux. Quicklime is calcium oxide from limestone. It does not fill a dolomite specification, and a calcined dolomite lot does not fill a lime order.
NAGTAR does not publish a steel assay, a refractory grain size, or a loss-on-ignition ceiling. Those are questions the shop has already answered in its own practice. We qualify a lot against the answers you send. If you do not have them yet, the inquiry is early, and we would rather wait than invent figures that a melt shop will reject.
What buyers mean by calcined dolomite in a steel shop
In steelmaking the phrase usually means a magnesium-bearing flux that has been calcined, used in slag practice and around basic linings. Shops also use graded calcined dolomite as a fettling or gunning material. "Dolomite for the converter" can mean any of those, or the raw stone another plant would calcine. The brief has to close that gap.
Refractory buyers mean something narrower still. Dolomite refractory grain is typically dead burned: a hard burn, a controlled size, and impurity ceilings tight enough for a brick or a monolithic that will see steelmaking temperatures. A lightly calcined, reactive product that a flux practice might tolerate can be useless in that press. Dead burned is not a catalogue code on our side. It is the description you confirm when the lot’s loss on ignition, size, and chemistry are in hand.
"Dolomite refractory" on a tender is a use, not a packing list. It should say grain or brick feed, the size band, the burn, and whether the plant also buys a fettling grade under the same name. One name for two sizes is how the wrong fraction arrives in the right bags.
A trading desk that buys for a steel group it does not operate still has to carry the shop’s sheet. We cannot replace a steelworks metallurgist. We can refuse a cargo that the sheet would refuse, and we can say when Algerian supply has no lot that meets it.
The decision the brief has to record
Three decisions sit in front of price. First, calcined rather than raw. If the shop has no kiln step for this material, the stone is the wrong nomination even when the carbonate chemistry looks close on paper. Second, the burn: dead burned where the product must stay comparatively inert, or a lighter calcination where the shop’s own words say so. Third, the duty: flux, fettling, or refractory grain. Those duties do not share one size or one impurity panel.
Lime is the decision that gets skipped. Calcined dolomite cannot cover a lime voyage unless the shop has a written calcium-magnesium practice and has accepted the magnesia. Quicklime cannot cover a dolomite gap either. The lime page is the calcium flux. Keep the inquiries apart.
There is a decision about trial versus campaign. A refractory formulation change and a new steel supplier are trials. They need a defined lot, a defined test list, and a statement of who may reject. They are not an invitation to ship a convenient size because the plant is curious. Once the shop has accepted a lot, the repeating specification should stay still. Moving the burn or the size between cargoes restarts the trial.
Commercial terms come after the sheet. Volume, packing, destination, and Incoterm are meaningless against an unnamed burn. Nothing is firm until the lot matches the questions below and the contract is accepted.
Specifications as questions, not as a published assay
Loss on ignition is the first question. What ceiling does the shop enforce, and by which method and temperature? Steel flux and refractory grain often use LOI as the practical check that the burn went far enough and that the product has not already recarbonated or taken up water. We will report the lot against your method. We will not propose a percentage to fill a blank. If your lab and the loading lab do not share a method, agree the method before the sample is drawn. Two LOI figures from two temperatures are not a dispute about the cargo. They are a dispute about the clause.
Size is the second question. Lump or a coarse fraction for a converter practice is not a graded grain for brick, and fines that help one gunning mix can ruin another. Name the lower and upper sieves, and say whether oversize and undersize are each capped. "Millimetre size on request" is not a specification. If the shop has a retained works sample, say whether the new lot must match its grading or only its chemistry.
Impurity ceilings are the third question. Ask the shop which elements it actually caps. Silica, iron, alumina, and sulfur are the names that recur in steel and refractory sheets. Your ceilings may be tighter or looser than another plant’s, which is why we do not print market maxima. Send the numbers you will reject on. A lot certificate that omits a capped element is incomplete, not "generally fine."
Lime and magnesia are the fourth question, and they are windows rather than slogans. If the shop needs a minimum magnesia, or a balance between the two oxides, write the window and the basis (as-received, or another basis you define). Do not send a target you copied from a textbook and have never used. The qualified lot either falls inside your window or it does not. We do not adjust the words after we see the analysis.
Moisture at sampling, reactivity where you use it, and a note of whether the product is dead burned or lightly calcined complete the sheet for most files. Add a test only if rejection depends on it. A long list that nobody will run delays loading and does not protect the shop.
Uses, and the cargos that will not do
Steel flux is the use where calcined dolomite is charged for magnesia in the slag practice and for basic linings. The shop’s procedure already says how much, in what size, and with what lime beside it. We match that description. If the procedure still says raw dolomite, this is the wrong page.
Fettling and gunning are closer to a refractory use than to a bulk flux stem. Size, burn, and the way the grain holds together matter to the crew that maintains the lining. A flux lump that happens to be calcined dolomite is the wrong delivery against a gunning specification. Say which duty you are buying so the packing and the size follow it.
Dolomite refractory covers brick makers and monolithic plants that need dead burned grain. They care about LOI because a residual carbonate or a recarbonated surface is a defect in the fired product, and they care about impurities because the brick has a specification of its own. Send the grain specification. Do not send a steel flux sheet and expect the refractory plant to "make it work."
Raw dolomite fails these uses when the process has no calcining step of its own. The stone can be the right feed to a kiln. It is not a substitute parcel for a shop that wrote calcined into the purchase conditions. Offering it because the tonnes are easier is a product error, not a commercial alternative.
Lime fails them for a different reason. It is the calcium flux many of the same shops also buy, on a separate contract, with available lime, reactivity, and residual CO2 judged on a lime basis. A vessel of quicklime does not become calcined dolomite if dolomite is late. A vessel of calcined dolomite does not become lime if the lime kiln is down. Split the forecast. Place each product on its own inquiry.
Packing, moisture and the cargo you can actually take
Calcined product for steel and refractory is packed as bulk, big bags, or containers. The mode follows the grade and the store, not a standard hold. A refractory plant taking graded grain often wants big bags it can keep closed. A steelworks with a bulk flux berth may take bulk when the lot is large enough and the product can be discharged under cover. A small trial is a container. None of those is the default we apply before you write.
Moisture pickup is the operational risk on all three modes. An open hold, a torn bag, or a container that sat in weather can move loss on ignition before the shop samples. Dead burned grain resists that better than a light burn. It still should not be wetted and then defended with a works certificate from the week before. State how long the lot may remain in the open, who provides covered storage at discharge, and whether wet bags are a rejection.
There is no published parcel in tonnes for this product. Tell us what the shop can receive in one delivery without breaking the storage rule. We will say whether that volume matches a lot that can be qualified. We will not inflate it to resemble a raw mineral cargo, and we will not refuse a correct bagged lot because a bulk broker finds it small.
Weight on bags follows the bag specification. Weight on bulk is a draft survey or a belt figure, written next to any moisture rule. Do not mix the two methods in one sentence.
Previous cargo and cleanliness matter more on bulk. A hold that last carried a contaminant the refractory lab will see is a failed nomination. Say who inspects. On bags, the equivalent check is the bag integrity, the marking, and the lot number that ties them to the certificate.
Documents, inspection and Incoterms
The certificate has to read as calcined dolomite for the duty you named. Loss on ignition by the agreed method, size, the impurity results you capped, and the lime and magnesia window if you set one. A generic "dolomite, suitable for steel" sheet will not pass a refractory incoming inspection, and it should not pass a steel one either. Safety data belongs in the set when the destination asks for it on a burned oxide. Commercial invoice, packing list or weight ticket, and the bill of lading or waybill follow the Incoterm. Origin documents follow the importer’s file, not a habit.
Inspection is best fixed at the loading point you will actually argue from. Calcined material can change in a yard. A sample drawn from a closed bag at stuffing, or from the bulk stream at the hold, with retains sealed, is the sample that matches the risk. A discharge sample can still be agreed, as a claim tool or as acceptance, but only one of them should govern. Write which. If the shop’s own LOI method differs from the inspector’s, the contract names the referee method before the dispute, not after.
Incoterms: FOB at the named loading port or terminal leaves the buyer to nominate carriage and to protect the cargo once risk has passed under that term. CFR places freight with the seller to the named place. CIF adds insurance under the term. Bagged and container shipments often need a term that names a container yard or a plant gate rather than a bulk laycan. Use the term the mode can perform. A steelworks that unloads its own bulk flux berth should not be sold a CIF container story, and a refractory plant with a bag store should not be sold a bulk FOB story.
The claim window has to be long enough for the shop to run LOI and the impurity panel, and short enough that a weathered stock is not presented as a loading defect. Say how samples are kept. A letter of credit should name the certificate’s tests if the bank document is what procurement will file as compliance. "Certificate of analysis" alone is a blank page with a stamp.
How Algerian supply is qualified
Qualification is against your steel or refractory sheet, on a real lot, from a supply path that can issue documents in the name of that lot. Algerian origin is not a grade, and it is not a promise that every burn exists on demand. If we cannot show LOI, size, and the impurities you named, we do not fill the gaps with industry averages. The answer is that the lot is not qualified.
Raw stone is not used as a standby. If the calcined path is not available for your window, we say no or we tell you the file belongs on raw dolomite only when your process can actually take the stone. Lime is not offered as a bridge. A shop that can accept either lime or calcined dolomite under two different procedures should send two procedures.
Dead burned language is checked, not assumed from the product title. If your refractory specification requires that burn and the lot’s LOI does not support it under your method, we stop. We do not rename a lighter burn to hold the order. The same rule protects a steel buyer who wrote a lighter calcination and is then offered a dead burned grain that will not do the duty.
A first cargo for a new shop is marked as a trial in the contract: volume, tests, packing, and the rejection rule. Acceptance of the trial does not silently create a yearly tonnage. The repeat is a new confirmation that the same limits still describe the next lot.
What to send with the inquiry
One duty per message. Flux, fettling, and refractory grain can all be calcined dolomite and still be three specifications.
- Steel or refractory, and the duty in the shop’s words
- Dead burned or the lighter burn you mean
- LOI ceiling, method, and temperature if your lab states one
- Size, with sieves
- Impurity ceilings, and any CaO or MgO window
- Volume, packing, destination, Incoterm, and window
- Who samples, and which result governs
- Whether lime is a separate purchase you do not want mixed into this file
The practical address is the trade inquiry. You can start from calcined dolomite if you want the product named correctly before you write. Attach the shop sheet even if some cells are empty. Empty cells are questions. Invented cells are worse.
Can raw dolomite cover a steel flux brief if the tonnes are easier?
Only if the shop’s procedure is written for the stone, or the plant will calcine it before use. A brief that already says calcined dolomite for steel is describing the oxide. Raw stone still has to lose CO2. The loss on ignition, the available oxides, and the mass the crane thinks it is charging will not match the procedure. Easier tonnes are a logistics fact about a different product.
If you are unsure which document the melt shop signed, send both wordings and ask them which one is current. We will qualify only the current one. We will not ship stone against a calcined order and call the difference a moisture adjustment.
Is lime an acceptable stand-in for calcined dolomite?
No. Lime is a calcium flux. Calcined dolomite is a calcium-magnesium product. Steel shops that use both do it on purpose, in proportions their slag practice allows, under two specifications. Substituting one for the other changes the magnesia the practice was counting on. It is not a late-week replacement when one ship slips.
Place lime on the lime inquiry, with the form, quicklime or hydrated, stated in the first line. Leave this file for the dolomite burn you actually need. A sentence in the purchase order that allows "lime or dolime" should be struck before nomination, unless the shop has signed that alternative in the operating procedure, with limits for each.
Which LOI figure should we put in the inquiry?
The figure your shop already uses, with the method. If the incoming standard says a maximum loss on ignition at a stated temperature, copy that. If the shop has never written a number, do not borrow one from another works or from a seller’s old sheet. Tell us the duty and ask for the qualified lot’s LOI by a method you are willing to adopt. Then put that method in the contract before the next cargo, so the second shipment is not argued on a different temperature.
A blank LOI with a strong size and impurity panel can still be enough to start qualification. It is not enough to accept the cargo. The burn has to be checked by something you will sign.
What size language does a refractory buyer use?
The language of the grain specification: a top size, a bottom size, and the percentage allowed outside the band, on named sieves. Brick feed, doloma, and gunning grains are not one band. If the plant says "0 to 10" or a works code, attach the code’s sieve table. A code without the table is a private language the loading inspector cannot apply.
Steel flux can be coarser, and it should say so in millimetres the crane and the hopper actually see. Do not reuse the refractory band for the converter, or the converter lump for the press. Two duties, two sizes, two lines on the order.
Who samples, and where?
Agree an independent inspector when the lot is large enough to argue about, or whenever the contract allows rejection on LOI and impurities. Draw the governing sample at loading, from the packed lot or the bulk stream, and seal retains for both sides. Discharge sampling is reasonable as a check for damage in transit. It is a poor way to discover that the burn was never what you ordered, because weather on the way confuses the result.
Name the laboratory and the LOI method in the same clause. A shop that will only believe its own furnace test should say that the loading sample is acceptance and the shop test is information, or the reverse. Silence is what produces two certificates and no rule.
What goes in the first message to NAGTAR?
The duty, the burn, the LOI question, the size, the impurity ceilings you already enforce, the volume, the packing, the destination, and the window. Say if this is a trial. Say if lime is a separate need so we do not merge the files. Attach the sheet.
Send that to the trade inquiry. If the sheet is still only the words "calcined dolomite for steel" or "dolomite refractory," send it anyway and mark the missing limits as open. We will list what has to be filled before a lot can be accepted. We will not answer with a fictional analysis to make the message look complete.