Steel Sinter FGD Gypsum Filter Cloth for Horizontal Vacuum Belt Filters
Many sinter plants desulphurise the gas coming off the sinter strand. Where that is done on a wet lime or limestone route, the sulphur leaves the circuit as gypsum, and where the gypsum is dewatered on a rubber-belt horizontal vacuum belt filter, the filter cloth is a consumable endless belt fabricated to the machine's dimensions.
Where this gypsum comes from, and why it gets its own page
A sinter plant prepares the iron-bearing feed for the blast furnace: ore fines, coke breeze, return fines and flux are laid on a travelling grate, the surface is ignited, and the combustion front is pulled down through the bed by suction. What leaves that bed is a process gas — large in volume, moderate in temperature, and carrying what the bed carried: dust, alkalis, chlorides and, depending on the ore and flux, fluoride. That is industry-level process knowledge, not a measurement of your plant.
Several desulphurisation routes are used on sinter gas, and only some of them end in a wet gypsum slurry. Where the route is wet lime or limestone scrubbing, the captured sulphur is oxidised to calcium sulphate and has to be taken out of the circuit as a cake. Where a belt filter does that job, the machine family it would belong to is the rubber-belt horizontal vacuum belt filter. Public evidence for this duty records vacuum belt dehydrators on sinter FGD duty in China and grades that evidence PARTIAL — see the evidence block below before you assume this page knows your circuit.
The cloth itself is a consumable. It is an endless belt built to your machine's width and circumference, running on the grooved rubber transporter, and replaced on a cycle your duty sets rather than a cycle a catalogue sets.
This one comes off a sinter strand. The gypsum on a power-station wet-lime scrubber comes off a boiler burning fuel, and phosphogypsum comes out of a phosphoric acid plant and brings fluoride with it. Same chemical family, three different gas or process streams feeding three different liquors — so the cloth question is asked from scratch each time.
Phosphogypsum vs FGD gypsum →Process flow across the belt
- 01 Scrubber Bleed Bleed from the sinter-gas desulphurisation circuit is thickened or cycloned before it reaches the filter.
- 02 Filtration Vacuum pulls scrubber liquor through the cloth and the gypsum cake forms on the surface.
- 03 Washing Wash stages displace scrubber liquor, and the salts it carries, out of the cake.
- 04 Dewatering A dry-vacuum zone pulls the washed cake down towards its handling moisture.
- 05 Cake Discharge Cake releases at the discharge roller; where it then goes is a plant-by-plant question.
Operating values for each stage — slurry temperature, pH, chloride load, particle size, solids, cake moisture — are plant-specific. We do not publish typical figures for them; they go on the confirmation list below instead.
What the public record on this duty actually supports
The research this site is built on rates the public evidence for sinter-plant FGD gypsum as thinner than for utility FGD. We would rather print that sentence than write a page that sounds equally sure about both.
| Question | What the record says | Evidence level | Where it comes from |
|---|---|---|---|
| Machine route recorded for this duty | CN vacuum belt dehydrators + others | PARTIAL | 05_Equipment_Map — industry to machine, "Steel sinter FGD" row |
| How the research rates the public record | Thinner public evidence than utility FGD | PARTIAL | 02_Product_Opportunity — PO-0003 counter-evidence column |
| Markets where the duty is documented | China, India, Korea | PARTIAL | 02_Product_Opportunity — PO-0003 geography column |
| OEM named in our register as running this specific duty | UNKNOWN — none | UNKNOWN | Equipment register: no row resolves "FGD" to sinter plants |
| Our own record on this duty | UNKNOWN — no fit record exists yet | UNKNOWN | Site-wide: zero verified fit records at launch |
Earlier this duty was addressed inside the power-station FGD page. Folding it in there implies the two circuits produce the same slurry, and nothing in the record supports that. A sinter-plant engineer should land on a page that says what is known about his circuit and what is not — including the geography note above, which records where the duty is documented in public sources, not where we have business.
What makes this duty hard on a belt
Most of the points below are the difficulties common to horizontal vacuum belt duty. The first two are what make the sinter side its own case: the upstream process is a batch-fed strand rather than a steady boiler, and it carries its own salts into the scrubber liquor.
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A gas stream that moves, and a slurry that moves with it
A sinter strand is not a base-loaded boiler: blend, moisture, coke rate and suction change through the campaign, and the desulphurisation circuit downstream sees that variation.
Cloth implication: A belt picked for one operating point can behave differently at another, so the useful answer to “what is your slurry like” is a range, not a single line off a process sheet.
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Salts carried in from the bed
Ore fines, coke breeze and flux bring chlorides and alkalis onto the strand, and a wet scrubber circuit concentrates what it captures in its own liquor.
Cloth implication: Polymer and finish have to be chosen against the liquor that circuit actually reaches — which is why the chemistry row on this page is a question to you, not a published number of ours.
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Blinding by fines and scale
Free area closes as fines and precipitated solids lodge in the fabric; throughput drifts down well before anything visibly fails.
Cloth implication: Weave geometry and surface finish set how fast the fabric closes and how much of it recovers on cloth wash.
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Tracking and wrinkling
The belt wanders on the grooved rubber transporter, contacts the edge guides, and the vacuum seal starts leaking.
Cloth implication: Fabricated length, seam squareness and edge treatment all feed into whether a belt tracks.
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Seam and joint leakage
A clipper or PAD joint opens, vacuum drops as the joint crosses the box, and the cake wets back.
Cloth implication: Seam type is a specification to be decided against your machine, not a shop default.
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Cake sticking at discharge
Cake does not release cleanly at the discharge roller and carry-over builds up on the return run.
Cloth implication: Surface finish and calendering change release behaviour.
How severe each one is on your machine depends on numbers we do not have. We are not going to guess them from a utility FGD page and present the guess as knowledge of your circuit — that is what the confirmation list is for.
What our equipment register can and cannot tell you here
The rows below are the rubber-belt HVBF families our register records in FGD service of any kind. The fourth column is a check run against the register itself: does the record name sinter plants? Read it before you read anything else in the table.
| OEM family | Industries recorded | Evidence level | Record names sinter? | Next step |
|---|---|---|---|---|
| FLSmidth EIMCO Extractor | FGD, minerals | OBSERVED trade | Not stated | Send brand + model |
| Compositech T-REX / Chemifilter | FGD, chemicals US | OBSERVED | Not stated | Send brand + model |
| EKCP EIMCO-KCP | IN FGD + phosphate | OBSERVED | Not stated | Send brand + model |
| Toncin DU | CN FGD, mining, Li | Company-reported | Not stated | Send brand + model |
| WesTech HBF | Minerals, FGD directories | PARTIAL | Not stated | Send brand + model |
“FGD” in that register is not resolved to power stations or to sinter plants, so none of these rows is evidence that the family runs on your line. They are here because they are the machine family a sinter-plant belt would belong to, and because the nameplate on your machine settles in one line what this table cannot.
Ammonia scrubbing takes the sulphur out as an ammonium salt rather than as gypsum. Semi-dry and dry sorbent routes produce a dry by-product that is handled as a dust, not filtered as a slurry. Adsorption routes recover sulphur in another form again. If your line runs one of those, there is no gypsum cake for a belt to make, and this page does not apply to you — tell us the route and we will say so plainly rather than quote you something.
All OEM names are used for compatibility reference only.
How the cloth is specified for this duty
Selection runs backwards from the liquor. Its chemistry and temperature narrow the polymer; the particle size distribution and the wash requirement narrow the weave and the surface finish; the machine narrows the fabricated dimensions, the seam and the edge treatment. The candidate polymers for horizontal vacuum belt duty are PET monofilament, PET mono/multifilament combinations, polypropylene, double- and multi-layer weave constructions, and hydrolysis- or alkali-resistant specialities.
Which of those belongs on a sinter-plant belt is not something a web page can tell you, and on this duty it is less defensible than usual to pretend otherwise: the published record here is thinner, so the weight that would otherwise sit on precedent has to sit on your liquor analysis and your machine instead. Send those and the specification becomes an engineering conversation rather than a guess.
Specification status
Our factory specification package has not been confirmed in writing yet, so every parameter reads UNKNOWN. Each one is fixed against your machine and slurry during the engineering review, and it is stated in the quotation — not inferred from this page.
| Parameter | Value | Unit | How it is fixed |
|---|---|---|---|
| Polymer | UNKNOWN | — | Confirmed against scrubber liquor chemistry |
| Weave / construction | UNKNOWN | — | Confirmed against cake formation and wash duty |
| Air permeability | UNKNOWN | L/dm²/min | Test method and test pressure will be stated with the value, once the mill confirms them in writing |
| Fabric weight | UNKNOWN | g/m² | Reported with the value, once confirmed in writing |
| Seam type | UNKNOWN | — | Confirmed against machine and seam photo |
| Edge treatment | UNKNOWN | — | Confirmed against machine edge seal |
| Max fabricated width | UNKNOWN | mm | Confirmed against loom and machine width |
| Continuous temperature limit | UNKNOWN | °C | Confirmed per polymer and finish |
| Chemical limit (sinter-circuit scrubber liquor) | UNKNOWN | — | Confirmed per polymer and finish, against your liquor analysis |
Industry reference — not our specification
| Parameter | Industry reference | Source |
|---|---|---|
| Belt width range seen on this machine family | 4.5–4.8 m | Equipment-family observation, third-party machines |
That row describes the machine population, not our capability. Our own width limit is on the UNKNOWN list above until the factory confirms it. Dimensions are taken from the old belt, not from this range — how to measure your old belt →
What we can build for this duty
The parameter table above reads UNKNOWN because our own values are not confirmed in writing yet, and we will not fill that table with industry averages. This section is the other half of the answer: the options this cloth is actually built from, what each one changes, and which piece of your data decides it. Nothing below is a specification — it is the shape of the decision.
Cloth form An endless belt fabricated to your machine dimensions. The cloth form matches the utility FGD duty; the specification behind it does not.
Recommended material direction
This is the third gypsum and it is not the utility one. What a sinter circuit carries into the filter — chlorides, alkalis, and fluoride depending on the ore and the flux — puts alkali on the table. Alkali is the species that changes the polymer answer rather than the joint answer, which is why this duty cannot inherit a specification from the utility page.
This narrows the field; it does not pick. Which polymer goes on your machine is settled against your measured numbers and not on a web page — the same position the selection section above takes. What follows is the reasoning behind that position, not a departure from it.
- Polypropylene PP
Continuous reference up to ~90 °C — a published property of the polymer, not a value of ours
- Acid Excellent
- Alkali Excellent
- Hydrolysis Excellent
- Abrasion Good
Alkali is where polypropylene is strongest, and it is indifferent to chloride. The constraint is the polymer reference temperature above, and creep under sustained load.
- Polyester (PET) PET
Continuous reference up to ~150 °C — a published property of the polymer, not a value of ours
- Acid Good
- Alkali Limited
- Hydrolysis Limited
- Abrasion Excellent
The reference belt polymer on abrasion and dimensional stability, but alkaline hydrolysis is its published weakness and it is the property to check here. The rate climbs with temperature and with concentration, so a liquor that is harmless cold is not automatically harmless hot.
- Polyphenylene sulfide (PPS) PPS
Continuous reference up to ~190 °C — a published property of the polymer, not a value of ours
- Acid Excellent
- Alkali Excellent
- Hydrolysis Excellent
- Abrasion Good
The direction if the duty turns out to be both hot and alkaline. It is a large cost step over PET and PP and has to be earned by a duty rather than by a preference.
- PA Not ruled out on chemistry — polyamide is good in alkali. It is ruled out here on dimensional behaviour: it absorbs moisture and changes dimension with it, which is awkward on a belt that has to hold its developed length between take-up adjustments.
What actually decides it Whether the liquor is actually alkaline at your filter, and how alkaline — that is a measurement, and this page does not have it. Neither does the published record for this duty, which is thinner than for the utility one. Everything above is conditional on that number and on the temperature; two sinter plants do not carry the same species into the same machine.
Everything in this block is reasoning from published polymer behaviour applied to the chemistry described further up this page. It is a direction, not a selection — and the selection is made against your measured numbers during the engineering review, then written into the quotation. The full polymer envelope is on the materials page.
Weave options
If the solids reaching your filter are fines and precipitated material rather than a coarse mineral — which is what the circuit description above points to, not something we have measured on your plant — the structure has to hold retention without closing up.
- Double layer / multi-layer Two or more interlaced fabric layers woven as one. A fine filtering face carried on a coarse structural back — high strength with fine retention, and drainage channels inside the fabric. Watch: Thicker and heavier; more expensive to weave. The usual answer on heavy belt duties.
- Twill The crossing point steps sideways each pick, giving a diagonal rib. More flexible and more permeable than plain at the same yarn count, with better cake release. Watch: Slightly less dimensionally stable than plain.
- Plain One over, one under. The most stable and the most rigid. Tight, uniform pores; lower permeability for a given yarn. Watch: Least forgiving of dimensional movement; can blind faster on fine solids.
A coarse structural back under a fine face gives the drainage channels that a single-layer fabric of the same rating does not have.
Yarn form. Yarn form and weave are chosen as one decision. Where the fines are the problem, surface smoothness and wash-back matter more than the last increment of retention.
Yarn form, weave and surface finish are settled as one decision. The four yarn forms available are monofilament, multifilament, mono + multi combination and staple / spun.
Permeability considerations
Air permeability is the figure everyone compares and the easiest one to quote meaninglessly. It is measured per ISO 9237 at a stated pressure drop — often 200 Pa — or per ASTM D737 (Frazier). A value with no stated pressure and no stated unit is not comparable to anything, including ours. The same applies to a pore or retention rating: on a woven cloth that is a nominal figure and not an absolute cut-off, because woven media do not have a single pore size and the cake quickly becomes the real filter.
Publicly documented data on this duty is thinner than on the utility FGD one, so a permeability figure quoted without its test method and pressure is worth even less here than usual — there is no reference population to compare it against.
How each property is measured, and what to ask any supplier for alongside the number, is set out on the testing and inspection page. Naming the method is a fact about a public standard, not a claim about our laboratory.
Joint options
- Clipper (metal hook) Interlocking metal hooks crimped onto both cloth ends, joined by a pintle wire. Fitted and replaced on the machine without dismantling it. The fastest change-out. Watch: The joint is a discontinuity: it leaks vacuum as it passes the box, and it is where most belt failures start. Hook material has to suit the liquor.
- PAD / welded overlap The two ends are overlapped and thermally fused. A smoother, quieter joint that seals better than a clipper and carries load more evenly. Watch: Made off the machine or with a portable press; a change-out takes longer.
- Spiral Spiral coils on each end interlaced and pinned. Flexible, drains through the joint, distributes load along the full width. Watch: Adds an open line across the belt — not appropriate where the joint must seal.
Seam type is a specification to be decided against your machine, not a shop default. With chlorides and alkalis both present, the hook material of a clipper joint is a chemistry question in its own right.
The four constructions drawn in cross-section: how joints fail and what each one costs you.
Edge treatment
- Cut and sealed The cut edge is thermally sealed against fraying. The baseline. Adequate where the machine edge seal is in good condition.
- Folded / hemmed The selvedge is folded back and secured. Adds thickness and stiffness at the edge where the seal rubs.
- Reinforced edge band A separate band is bonded along the selvedge. For machines that chew edges — the usual answer when a belt keeps failing at the edge while its body is sound.
- Coated / sealed band A polymer band is applied to the edge. Seals the edge against vacuum bypass as well as protecting it mechanically.
- Guide strip / tracking profile A profile bonded to the underside to run in the machine guide. Only where the machine is built for it. Fitting one to a machine that is not is a common and expensive mistake.
Fabricated length, seam squareness and edge treatment all feed into whether the belt tracks — and a belt that does not track loses its edge before it loses anything else.
Relevant equipment
A filter belt is decided at the loom before it is decided anywhere else: what a weaving platform can hold — pick density, tension, width — sets what the finished cloth can be asked to do. Our weaving runs on DORNIER (Germany) and Sulzer (Switzerland) platforms, machines built for technical textiles rather than for apparel.
The dimensional discipline is the point here: this duty is specified from your machine and your liquor, and there is no published population to copy a belt from.
Model designations, working widths and installed quantities are being confirmed against the machine nameplates and are not published until they are. A weaving platform is easy to name and hard to fake, and we would rather you were able to check.
The full platform description, the eleven process stations from yarn to crate, and the nine laboratory checks: manufacturing.
Factory capability for this duty
The rows below are the part of our capability envelope that this duty touches. The last group is the one that makes the rest of it worth reading — a supplier who can do everything has told you nothing.
Machine families
- Rubber-belt horizontal vacuum belt filter Built to your spec
Core family. Endless belt with clipper, PAD or spiral joint and a finished edge.
What decides it Brand and model, measured width and developed length, a photograph of the joint.
Cloth construction
- PET and PP Built to your spec
The two polymers most belt duties are built in.
What decides it Liquor pH, temperature and cleaning chemistry.
- PA, PPS, PVDF, PTFE Engineering review
Available as a direction where the duty genuinely needs them. Cost and lead time are the constraint.
What decides it Whether the duty actually needs them rather than PET or PP.
Operating envelope
- Temperature and pH Engineering review
The polymer is selected so your duty sits inside its envelope, not at its edge.
What decides it Normal and peak temperature, and the cleaning pH as well as the operating pH.
What we do not do
- Quoting from an industry name alone Not offered
Two plants in the same industry run different slurries through different machines. We ask which.
The full envelope, including the machine families and services we decline: what we build to order and what we will not take on. Fifteen pages on how a specification like this is built and read: the filter cloth specification guide.
How these belts come off the machine
A failed belt is usually three-way: something in the cloth, something in the machine, and something in the process. Diagnosing it as purely a cloth problem is the fastest way to buy the same failure twice.
Belt tracking and wrinkling
Often machine-side (roller alignment, edge guides) before it is cloth-side.
Diagnose this →Seam / joint failure
Cloth-side and fabrication-side: seam type, squareness, and how the joint was closed on site.
Diagnose this →Cloth blinding
Process-side (fines, scaling, wash balance) interacting with weave choice.
Diagnose this →Poor cake release
Cloth surface and discharge geometry together; rarely one or the other alone.
Diagnose this →Cloth life on a horizontal vacuum belt filter is duty-specific. Published third-party cases run from weeks to months depending on slurry and machine condition, and none of those cases is a sinter plant. We do not quote a life figure before seeing your duty, and on this duty we have even less reason to.
Measuring the old belt and photographing where it failed is the first step in telling the three causes apart. How to measure your old belt →
What we need from you to quote
This list is the engineering RFQ in plain form — what you gather here is exactly what the form asks for. The first line matters more here than on the other gypsum pages: it decides whether your line produces a filter cake at all.
| What to confirm | How to get it |
|---|---|
| Desulphurisation route on the sinter line | Wet lime / limestone, ammonia, semi-dry, or an adsorption route. This decides whether there is a gypsum cake to filter at all. |
| Machine brand and model | Copy it off the machine nameplate. “Unknown” is an acceptable answer. |
| Belt width | Measure the old cloth across the web, not the rubber transporter. |
| Belt length (circumference) | Measure the endless loop, or give us the machine centre distances. |
| Seam type in use now | Photograph the joint close up — clipper, PAD, or spiral. |
| Photos of the old cloth | Face and back, plus wherever it failed. This is the single most useful thing you can send. |
| What failed | Life, blinding, tracking, seam leak, cake release, or wash quality. Compare against the failure modes above. |
| Slurry temperature, pH and a liquor analysis | From the process sheet or a recent lab analysis. A range across the campaign is more useful than one reading. |
| Where the cake goes | Landfill, cement, or a sold specification — and the specification it has to meet if it is sold. |
Before you enquire
What information do you need to quote a sinter-plant FGD gypsum belt filter cloth?
The desulphurisation route on the line, machine brand and model, belt width and length, the seam type you run now, photographs of the old cloth and its joint, what failed, and a liquor analysis with slurry temperature and pH. If you have all of that, a quotation is straightforward. If you have only some of it, send what you have — we will tell you which missing item actually blocks the quote and which one we can work around.
Get an engineering quote for sinter-plant gypsum duty
Three steps after you submit: an engineer checks what you sent against the machine, we come back for anything missing, and you get a quotation or a sample plan.
Every belt is fabricated to your machine dimensions — we quote per RFQ. No online checkout.
Samples available — freight terms confirmed per request.
Where to go next
Power FGD Gypsum
The wet-lime scrubber duty on a power station. A different gas stream, and a different page.
Phosphogypsum Filtration
Acid-plant gypsum, fluoride-bearing. Not a variant of either scrubber duty.
Phosphogypsum vs FGD Gypsum
The other two gypsum duties side by side, and why one belt does not cover them.
HVBF Filter Cloth
The cloth family this duty uses: weave, polymer, seam, edge and width options.
Vacuum Belt Dewatering Cloth
The sinter-gypsum duty read from the dry zone, where residual cake moisture rather than filtrate clarity sets the cloth choice.