A specialty silica grade is a silica cut the plant can actually run: a particle size described the way the lab measures it, and an iron level when colour or chemistry depends on iron. It is packed so that cut survives the trip, which usually means big bags and containers. The figures are requested by the buyer and confirmed on the lot. There is no published mesh, no standing d50 and no standing purity to order against. If you need a silica flour supplier for that kind of brief, start from specialty silicas and send the cut, the iron ceiling, the use, the tonnes and the destination.
If the host process was built on calcium carbonate, this is the wrong file. A white powder in a bag is not a mineral. Carbonate and silica behave differently in acid, in heat and in a compound that was approved on one of them. Send a carbonate brief to calcium carbonate and read which brief to send before anyone prices a substitution. Sand and lump for a hold are a third file, covered in silica sand or silica flour.
What buyers mean by a specialty grade
Specialty silica, on this desk, means a tighter cut or a higher-purity silica than a standard sand shipment. Flour is the common case. A narrow sand fraction can also belong here when the size window is too tight for a bulk industrial cargo and the packing follows the grade. Buyers in fillers, coatings, selected glass and ceramics, and some industrial processes use this language when a generic sand will not pass their screen, their colour check or their disperser.
They rarely mean synthetic silica. Fumed silica and precipitated silica are made by other routes and sit in formulations that name those routes. A ground mineral flour will not satisfy a line that was approved on a fumed grade, and we will not relabel one as the other. If the formula says fumed or precipitated, write that in the first email so the file stops before a quarry product is offered against it.
They also rarely mean a 5,000 to 30,000 tonne hold. That bracket is for industrial sand and lump. Specialty tonnes are whatever the grade, the bags and the container plan can carry, confirmed per shipment. Bulk remains possible later, for a grade that has been shown to survive it. It is not the opening assumption.
Mesh words travel with these inquiries and cause the most confusion. "200 mesh" on one site is not the same sieve as "200 mesh" on another, and neither is a grade we list. Send the sieve series, the residue you allow, the top size, or the d50 your formula uses. We treat that as a target for a lot. We do not answer with a mesh from a catalogue, because we do not publish one.
The decision the brief has to make
Three destinations are enough. Pick one before you ask for a price.
- The mineral is silica, and the plant needs a flour or a tight cut. Stay on specialty silica. The controlling items are the cut, iron if it matters, moisture, packing and volume.
- The mineral is calcium carbonate, including a ground or precipitated carbonate the compound already uses. Leave this page. The carbonate file and the comparison note are the brief. Particle size and brightness questions still matter there. They are questions about a different mineral.
- Someone wrote "filler" or "silica" and the formula does not say which mineral. Do not let purchasing guess. Ask the plant. If the plant cannot yet name it, the holding file is industrial fillers, not a specialty silica offer with a blank where the mineral should be.
A silica flour supplier who prices before that choice is selling a bag, not a grade. The offer we will stand behind names the cut that was requested, the iron ceiling if one was requested, the packing, the tonnes and the lot the certificate will describe. A unit price with none of those is a conversation, not a sale.
The same buyer can need both a carbonate filler and a silica cut, in different products. Those are two inquiries, two specifications and two packing plans. Sharing a supplier does not make them one grade.
Specifications that define the grade
Every number below is a request until a lot is tested. We confirm particle size, SiO2, iron, moisture and, where the process measures it, whiteness, on the grade that is offered. A sand analysis from another file does not stand in.
Write the cut in one of these ways, and say which result would fail the goods.
- A d50, with the method your lab uses. The number is yours. We report what the lot measures. We do not publish a house d50.
- A residue on a named sieve, with the sieve standard, or a top size the process cannot exceed.
- A retained band, if the plant needs the mineral inside two screens rather than simply "fine".
- If your lab only has a mesh habit, translate it. Name the aperture or the standard. A bare mesh count will be sent back.
Iron is the second half of most specialty briefs. State it as Fe2O3 unless your method uses another form, and state the ceiling the colour or the chemistry needs. Send the method when two labs have disagreed before. A low iron result on a coarse sand does not predict the iron in a flour ground from another face of the quarry, another day or another plant. The certificate has to be the flour lot.
SiO2 belongs on the brief when you have a floor. Moisture belongs on it because fine silica cakes, and because a container changes the figure between stuffing and opening if the bag and the box are wrong. Brightness or whiteness belongs on it only when the coating or the compound measures them. Name the method. "High white" is not a result.
Do not send a shopping list of every oxide on a glass sand sheet unless those oxides are release tests for this process. Extra limits that the plant will not enforce slow the qualification and create rejections nobody intended. Limits the plant will enforce, and did not mention, create claims. Write the ones that matter.
Two cuts are two grades even when both are called flour. If a paint line takes one residue and a plastic line takes another, they need separate offers, separate marks and separate certificates. Averaging them on one sheet describes neither bag.
Uses, and the product that misses the plant
Coatings use a silica cut when the formula calls for silica: film build, scrub, chemical resistance, or a mill base that was approved on that mineral. The practical tests are the cut, oil absorption if the lab runs it, and iron or brightness if colour is controlled. Oil absorption is requested with the method. It is not assumed from the word flour. A carbonate extender can sit in the same factory and still be the wrong substitution. If the brief is really a carbonate, route it before the trial wastes a batch.
Plastics and rubber use silica flour when the compound says silica. Hardness of the mineral is a reason plants do not casually swap it for carbonate: screws, barrels and wear parts see the difference, and the approved mechanical result was measured on one mineral. We will not quote a wear rate. We will ask whether the compound was signed off on silica. If it was signed off on calcium carbonate, the specialty silica offer is the wrong product even when the bags look similar and the price looks attractive.
Selected glass and ceramic processes ask for a tighter silica than a bulk batch sand. That can be a finer cut, a lower iron ceiling, or both. It is still not an invitation to send flour into a furnace that specified sand. Read the workshop. Batch sand stays on the sand contract. A frit, a glaze or a ceramic body that names a flour stays here.
The wrong product shows up in a few repeatable ways.
A buyer sends "silica flour, 325 mesh, white" and a destination. There is no sieve standard, no iron ceiling, no moisture, no packing and no use. Any bag could be argued to match. We ask for the cut in measurable form, the iron limit if colour matters, and the process. Until those arrive, there is no grade to qualify in Algeria or anywhere else.
A coatings plant attaches a carbonate specification and changes the product name to silica because a trader offered silica as "the same filler". Brightness method, oil absorption and particle size on that sheet were written for calcium carbonate. Running them unchanged against a silica cut does not make the minerals interchangeable. Open the comparison note and decide which mineral the formula contains.
A plastics compounder approves a cut on a sample, then receives a second lot ground coarser because the supplier treated flour as one product. The extruder sees a different dispersion. The contract needed the cut as a range with a method, and the second lot needed its own certificate. "Same as the sample" is not a specification unless the sample's measured cut is written down.
A glass buyer asks for specialty silica to fill a hold that was meant for batch sand, hoping a tighter iron story will also satisfy the furnace size. Iron and size are separate. Meeting one and missing the other is a miss. If both a sand campaign and a fine cut are real, they are two bookings.
Packing and cargo
Big bags and containers are the usual plan. Say how the plant empties the bag. A spout bag and a flat-bottom bag are different operations at the hopper. A liner matters when the cut dusts or when moisture uptake will cake it. The safe working load has to suit the discharger, the pallet or sling, and the warehouse racking. Marks, lot numbers and bag counts go on the packing list so two cuts in one box are not dumped together.
Container choice follows weight, moisture and the receiver's yard. A damp box, nail damage or a previous cargo that dusts will mark a fine silica after the producer’s moisture figure was already acceptable. Stuffing condition is worth an inspection point on a first shipment. Weight is a weighbridge result. A draft survey belongs to a hold, and most of these grades are not in a hold.
The industrial bulk bracket of 5,000 to 30,000 tonnes is not applied here by default. Quoting a specialty cut as if it should fill a handy-size cargo pushes the grade into handling it may not survive, and it pushes the buyer toward a volume the process may not want. State the tonnes you will actually take. A few hundred tonnes in containers is a normal specialty conversation. A larger programme is still planned from the bags upward until bulk has been shown to work for that cut.
Bulk is the exception we will discuss, not a refusal. It requires a grade that keeps its cut and stays clean in bulk handling, a volume that justifies the mode, and a receiver who can discharge a fine product without the bag. If any of those is missing, the offer stays in bags. Switching from bags to bulk mid-contract is a new qualification, because the contamination risk and the sampling point both change.
Misfires on packing are specific. Unlined bags sift, and the loss shows up as a weight claim and as dust in the container. Two cuts stuffed without separate marks become one unknown blend at the hopper. Bags specified without a spout arrive at a plant that only has a spout discharger, and the cut is then shoveled, which is a good way to segregate it. A buyer who copies a sand stem sheet onto a flour inquiry asks for a hold, a draft survey and a previous-cargo clause, and forgets the liner. Send the packing the plant has, not the packing the last mineral used.
Documents, inspection and Incoterms
The contract names the lot, not a generic flour. Expect a commercial invoice, a packing list with marks and numbers, the transport document the Incoterm requires, a certificate of origin from the competent Algerian chamber, a weight certificate, and a certificate of analysis. The analysis lists the cut as agreed, iron if iron is contractual, moisture, any brightness or SiO2 limit that was agreed, the sampling method, the laboratory and the date. A safety data sheet is added when the destination requires it.
Inspection is agreed before stuffing or loading and the inspector is named. Their certificate is theirs. For bags, the plan says how many bags are sampled and whether the sample is taken from the filling stream or from filled bags. A scoop from the top of one bag does not represent a container. For a first lot, keep a reserve sample and write down who holds it. If bulk is ever used, add hold cleanliness and previous cargo, and do not reuse the bag sampling plan unchanged.
Incoterms 2020, with a named place:
- FCA at an agreed point in Algeria is the frequent term for big bags and containers. We hand the cargo to your carrier there.
- FOB at a named Algerian load port applies when the flour is actually loaded on a vessel and you take freight and insurance from there.
- CFR to a named destination port means we arrange ocean freight and you insure.
- CIF adds marine insurance we arrange, and the insurance certificate joins the documents.
Name the place. "FCA Algeria" is incomplete. The port or yard follows the producer and the mode for that shipment. Payment is discussed with the term, because export proceeds are domiciled with an Algerian bank. A grade that is still being qualified should not be given a firm Incoterm and a firm price in the same breath. Qualify the cut first. The term is then attached to a lot that exists.
How the Algerian lot is qualified
We match the brief to a supply that can make that cut, hold the iron level you asked for, and pack it the way the plant receives it. Repeatability matters as much as the first sample. A quarry that loads sand is not assumed to be a grinding plant. If one group offers both, we still separate the installations and the offers.
Qualification asks whether the requested cut is reachable, whether the iron ceiling is reachable on a production lot rather than on a picked stone, and whether the packing is available. Sector authorisations, where this mineral needs them for export, are checked before a quote is treated as firm. If the answer on the cut or the iron is no, we say so. The nearest coarser flour is a different product.
A plant that has never run the source often needs a trial lot at the contractual specification, in the contractual packing, at a volume the lab and the line can test. The trial approves that cut from that supply. It does not approve a second cut, a sand, or a carbonate. Keep the measured results of the trial in the file. The next offer should be written against those results, not against the memory of a bag that "worked".
What to send
Use the trade inquiry. One grade per message.
- Mineral: silica flour or the tight cut you mean. If you are not sure it is silica, say so.
- Use: coating, plastic, ceramic, glass workshop, or the process name.
- The cut as a target, with method or sieve standard. Iron ceiling if you have one, with method. Moisture. Brightness only if you measure it.
- Tonnes now, and whether a programme follows.
- Big bag details you already know: spout, liner, load the discharger accepts. Container or other mode.
- Destination, Incoterm with a named place, window, inspector, and documents the import requires.
If the formula in your hand is calcium carbonate, do not force it into this list. Send it on the carbonate line.
Is there a published mesh we can order?
There is no mesh list. A mesh count without a sieve standard is not a grade, and two buyers using the same mesh word often mean different apertures. Send a residue on a named sieve, a top size, a d50 with a method, or a band between two screens. We will say whether a lot can be offered against that target. We will not invent a mesh to make the inquiry look complete.
How should a d50 be sent?
Send the figure your formula or your lab uses, and the method behind it. Mark it as a target. The offer then either meets it on a named lot or it does not. A d50 without a method is a number two laboratories can miss while both claiming to be right. A d50 copied from a competitor's data sheet is still only a target until your plant confirms that this process needs it. We report the result measured on the lot we ship. We do not keep a public d50 for specialty silica.
The process wants a carbonate filler. Where does the brief go?
It goes to calcium carbonate, and the comparison between carbonate and silica filler is the note that separates the two briefs. Stay off the specialty silica file unless a second product in the plant is genuinely silica. Particle size, brightness and oil absorption can matter for both minerals. They do not make the minerals the same material. A trial that swaps them without a reformulation is a process risk the contract should not be asked to hide.
What does an iron ceiling change in the offer?
It decides which supply can be offered, which lots fail before loading, and what the certificate must show. A brief with no iron limit can be qualified on cut and moisture alone. A brief with an iron ceiling cannot. The ceiling is yours to set, from colour, from a chemical specification, or from the last lot your plant actually accepted. We confirm the tested figure on the lot. We do not publish a typical iron for specialty silica, and we do not copy an iron result from a sand cargo onto a flour.
What do you need to know about big bags and containers?
How the bag is emptied, whether a liner is required, the working load the plant can lift, and how many tonnes move in the window. Also say whether two grades could share a container, because if they might, they need separate marks. Container condition and moisture protection matter as much as the bag. If you only know "big bags", send that, and we will ask the rest before the packing is locked. An assumed bag is how a cut arrives that the hopper cannot empty cleanly.
Can a bulk sand tender be answered with a specialty grade?
Only if the tender is actually for a fine cut and the packing and volume fit a specialty lot. A tender written for sand in a hold, inside the industrial cargo bracket, is a sand inquiry. Offering flour against it because both are silica mismatches the discharge, the sampling and the size. Point that tender back to the sand-versus-flour note and the bulk silica line. If the tender's technical annex quietly specifies a flour residue and an iron ceiling, ignore the word sand in the title and qualify it here, in bags, at the tonnes the annex implies.