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Everything plant and maintenance teams ask us, answered properly by a manufacturer and service provider with 30+ years and 500+ vessels behind it.
There are two methods that do not require anyone to enter the vessel. A whipping system is lowered through the existing top hatch — a hydraulic boom carrying rotating chain or hammer whipsets that clean hardened material off the wall as the vessel empties beneath. Where material has set beyond what any mechanical head will move, the Cardox CO2 System is used: a steel tube of liquid CO2 is fired through a socket in the wall, the gas expands to 600 times its volume and the blockage breaks in milliseconds. Most jobs use both. The alternative — sending people inside with rods and hammers — is slower, more expensive and the most dangerous job in the plant.
Cement is hydraulic, so it does not simply cake against the wall — it reacts with moisture and hardens. Whipping cleans the coating off the wall and off the buried aeration pads so the silo can fluidise again; the Cardox System then opens the cone, gates and extraction points where cement has set solid. Nothing wet is used, because water is what set it in the first place. Full detail on cement silo cleaning.
Yes, and it should be. Machine cleaning through the top hatch removes the confined-space entry entirely — no permit, no breathing apparatus, no rescue standby team, and nobody positioned beneath a suspended mass of material. It is also far faster: manual clearing of a kiln ring can take up to 8 days and as many as 30 workers, against hours with one or two operators.
It depends on what is actually blocking it. A bridge or arch across the outlet, a rathole through set material, and a compacted plug in the cone are three different problems. We survey through the top hatch first to establish which it is, then clear it — mechanically from above, or with a CO2 tube fired through the wall at the blockage. Adding more aeration or vibration to a vessel that has genuinely set rarely achieves anything.
A rathole is a narrow flow channel through otherwise stuck material — the vessel appears to be working while most of its capacity sits welded to the wall. The stuck annulus has to be physically removed, which is what the whipping system does, working down the vessel as material falls away. Aeration will not shift it, because the air simply follows the existing channel.
A bridge is a self-supporting span of material across the outlet, and it can collapse without warning — which is exactly why nobody should be underneath it. The Cardox System breaks it from outside the vessel wall in milliseconds. Where the vessel has a top hatch and the bridge is reachable from above, whipping can be used instead.
Rotating whipsets on a boom, lowered through the top hatch. The whipset — steel chain, bronze chain or rope with abrasion-resistant knuckles — is chosen for the material and for the condition of the wall. The action is non-destructive: it removes coating without gouging concrete, steel liners, coatings or welds, which is why it is accepted on vessels where hammering or chipping would not be.
Through the top hatch, with whipsets cleaning caked coal off the wall, and the Cardox System for hang-ups that have set solid at the throat or outlet. See coal bunker cleaning.
Hoppers are usually blocked at the cone or the outlet rather than up the wall, so most hopper work is done with the Cardox System — a tube fired through a wall socket, aimed into the blockage and away from the wall. It clears in seconds and the hopper returns to free flow.
Through sockets welded onto the cyclone or preheater shell. The tube is inserted to a pre-set depth and direction and fired remotely. Critically, this is done at operating temperature — there is no need to shut the line down and wait for it to cool. See the Cardox System.
Cardox tubes fired through the kiln shell break the ring without anyone entering the kiln and without cooling it down. Manual ring removal means a shutdown, a cool-down period, a gang inside and then a re-heat. The CO2 method removes all of that.
It depends on vessel size, the material, how hard the build-up has set and how much access you have — which is why we survey before quoting rather than giving a blind number. What we can say is how the economics compare: manual clearing of a kiln ring can run to 8 days and 30 workers plus a shutdown and cool-down. The same job done from outside is hours with one or two operators. Send us the vessel and material and you will get a real figure.
From a few hours to a few days, depending on size and how hard the material has set. As a reference point, we cleaned three 380-tonne coal bunkers in five days total, with zero confined-space entry.
Most plants clean reactively — when flow stops. That is the most expensive moment to do it. Build-up compacts and hardens with age, so a vessel cleaned on a planned outage costs far less than the same vessel cleared in an emergency. For hygroscopic materials in India, cleaning before the monsoon rather than after it makes a measurable difference.
Often, yes. Where permanent sockets are fitted to the vessel wall, blockages can be cleared with the Cardox System during production — the tube goes in, the charge fires, the material moves, and the plant keeps running. Full whipping of a vessel does need it emptied and isolated.
For whipping, the vessel is worked as it empties — the boom follows the material down. For Cardox blockage clearing through sockets, no: the point of the method is that it works on a vessel that will not empty.
Manual silo cleaning is one of the most dangerous jobs in industry. The hazards are a confined space, respirable dust, and an unstable mass of material overhead that can collapse onto whoever is beneath it. Every serious incident in this category follows the same pattern — someone went inside to break a blockage loose. Cleaning from outside the vessel removes the hazard rather than managing it.
Yes. That is the whole basis of how we work. The whipping system operates through the existing top hatch and the Cardox System is fired from outside the wall. No confined-space permit, no breathing apparatus, no rescue standby team, no gas testing regime.
Not for the cleaning itself, because nobody enters the vessel. You need standard equipment isolation and lock-out, top access, and a shutdown window. No internal scaffolding is required.
No. The whipsets are flexible chain, hammer or rope heads that remove build-up without gouging concrete, steel liners, coatings or welds. With the Cardox System, the discharge head is set to a pre-determined depth and direction so the energy is aimed into the blockage and away from the wall — which is what protects refractory.
No. The Cardox System is classified non-explosive. There is no blasting licence, no magazine, no police notification and no special storage or transport permits. The discharge is carbon dioxide, an inert gas — no toxic fumes and no product contamination.
Yes. The rapid gas release cools the discharge rather than heating it, so nothing is added to the vessel, and bronze whipsets are used where a softer contact against the wall is wanted. The same system is used underground and on grain, sugar and fine powders.
Describe the vessel and the material. We will tell you whether we can clear it, how long it takes and what it costs — usually the same day.
Cement, clinker, raw meal, blending silo material, gypsum, limestone, lime, fly ash, bottom ash, coal, pet coke, lignite, biomass, coke, sinter, DRI and sponge iron, slag, iron ore fines, flux, dolomite, laterite, murram, soda ash, rock phosphate, urea and fertilisers, salt, potash, catalyst, pigments, plastics, talcum powder, bauxite and alumina, sand, gravel, clay, ores and concentrates, wood chips, sawdust, paper pulp, grain, flour, maize, soya, sugar and feed-grade powders. See materials and applications.
From small hoppers and bunkers of 100–200 MT right up to 25,000 MT storage silos, at heights of up to 60 metres. Vessel height is not a limitation — we work from the roof down.
Material that has stopped moving and has effectively become part of the structure. It still occupies volume, it is still insured and maintained, and it may still appear on your stock figures — but it is not available. In a badly ratholed vessel, deadstock can account for more than half the rated capacity.
Yes, cell by cell. It is common to find one cell of a multi-cell cement silo written off as "the bad cell" and left that way for years. That cell is usually recoverable.
Top access to the vessel, standard equipment isolation and lock-out, and a shutdown window. No internal scaffolding is needed. Dislodged material discharges through your normal outlet, so there is no separate removal operation to arrange — you recover saleable product rather than paying to dispose of it.
We are based in Mumbai and serve plants across India. We have also worked in Saudi Arabia, the UAE, Egypt, Bangladesh and Vietnam, and we supply equipment worldwide.
A hydraulically driven boom assembly that enters through the vessel's top hatch, carrying rotating chain or hammer whipsets that run at 800–1,000 rpm and clean hardened material off the wall. The operator controls speed and position from the roof. It is also known in the industry as silo whipping, bin whipping or whip cleaning. See the whipping system.
A blockage-removal system. A reusable high-strength steel tube is filled with liquid CO2, a chemical heater and a rupture disc. A small electrical charge converts the liquid to gas; pressure builds until the disc bursts and the gas — now 600 times its original volume — discharges through a shaped nozzle at up to 40,000 psi. One tube can shift over 3 tonnes. The whole event takes milliseconds.
Air cannons apply energy at the surface and rely on the material still behaving as a bulk solid. Once material has genuinely set and keyed to the wall, surface energy does not reach it — plants often add more air cannons and get less flow. The Cardox tube is inserted into the blockage and its pressure is regulated between 1,200 and 3,000 bar to suit the vessel. Cement plants also report air blaster efficiency losses of up to 75% over time; a Cardox tube delivers full pressure every time.
Yes. There are three ways to work with us: purchase a complete system, hire the equipment for a campaign, or hire our service team to do the work. We manufacture the whipping systems ourselves and ship them internationally with commissioning, operator training and spares. See equipment and export.
No. The steel tubes are reusable, with a working life of over 15 years. They are recharged in under a minute. There are no continuous running costs — the system is only used when build-up accumulates — and virtually no maintenance cost.
Almost always moisture meeting a material that reacts to it, plus time. Fine material packs under its own head; hygroscopic material pulls moisture out of humid air; hot product against a cold wall creates condensation. Once a bond forms at the wall, every subsequent layer keys onto it. Vessels that are never fully emptied never shed the coating, so it simply ages in place.
Three usual causes. A bridge — a self-supporting arch across the outlet, so the vessel weighs full but nothing comes out. A rathole — flow through a narrow channel that has finally closed. Or a compacted plug at the cone or extraction point. They need different treatment, which is why we survey before quoting.
Cement is hydraulic: it reacts with water rather than merely absorbing it. Any moisture path — humid air, a leaking roof, condensation from hot cement against a cold wall — starts hydration at the wall, and what forms is not a cake but a set layer bonded to the surface.
Wall coating reduces the effective diameter, and capacity falls with the square of the radius — so a modest-looking layer costs far more volume than it appears to. A 12 m silo with 250 mm of coating has lost roughly 8% of its volume before you count any rathole.
Because coating buries them. Once the pads are covered, fluidising air goes into the wall instead of the product, and the silo loses the only tool it had to keep material live. Cleaning recovers the pads as well as the wall.
Yes, measurably, for any hygroscopic material — cement, fly ash, gypsum, soda ash, rock phosphate, salt, urea. Material that was manageable before the rains is often set solid by the end of them. Cleaning ahead of the monsoon rather than after it is the cheaper decision.
Describe the vessel and the material. We will tell you whether we can clear it, how long it takes and what it costs — usually the same day.
Whipping for the wall coating and buried aeration pads, then Cardox at the extraction point where ash has compacted. Fly ash is fine, abrasive and hygroscopic, so nothing wet is used. See fly ash silo cleaning.
Clinker is stored hot, and residual heat plus condensation hydrates free lime against the wall. Whipsets are chosen for the state of the liner — which on a clinker silo is usually already worn — and Cardox handles the cone and extraction gates. See clinker silo cleaning.
This one is a quality problem as much as a capacity one: dead zones destroy the flow pattern the silo was designed around, and the symptom appears downstream as kiln feed chemistry that will not hold. Whipping recovers the wall and the aeration pads. See raw meal and blending silos.
Gypsum plates rather than cakes — calcium sulphate given moisture does what plaster does. Whipping delivers repeated impact along the bond line between plate and wall, which is the only place a set layer will fail. See gypsum silo cleaning.
Soda ash re-crystallises into a solid mass keyed to the wall — aeration, vibration and washing all fail on it, and washing makes it worse. Mechanical energy at the wall plus Cardox in the cone. See soda ash silo cleaning.
Phosphate is hygroscopic and abrasive at once, and the vessel wall is usually already worn, so the whipset is matched to the vessel rather than to the material alone. See rock phosphate cleaning.
Mostly with the Cardox System — steel plant hoppers are smaller and blockages sit at the cone and outlet, which suits a tube fired through a wall socket better than a boom from above. See sinter, DRI and slag hoppers.
The same CO2 tube used for blockages is placed in a drilled hole. The gas expands and produces a controlled heave rather than a detonation — pressure begins at the back of the hole and pushes forward, fracturing the rock along its natural planes. See CO2 rock breaking.
The system is classified non-explosive, which means no blasting licence, no magazine, no police notification and no special storage or transport permits. That classification is the reason it can be used on sites where conventional blasting is refused.
It depends on strata and hole pattern. As planning figures: general quarrying 3–6 m³ per tube, dimensional stone 5–20 m³, open-cut hard and medium rock 3–5 m³, tunnel excavation 0.5–1.5 m³, mass concrete 2–4 m³ and heavily reinforced concrete 0.75–1 m³. We confirm against your geology before quoting.
Yes — that is the main reason projects use it. There is no ground vibration transmitted to neighbouring structures, no shock wave, no noise and no fly rock, so work can proceed metres from an occupied building or beneath live gas, electricity and water mains.
Yes. Because there is no shock wave, divers can remain in the water during activation and it can be used close to ships and structures — harbour deepening, seabed routes for cable and pipeline, and riverbed work.
Tubes are placed in drill holes and the heave fractures the concrete in a controlled direction. It is used on mass, lightly reinforced and heavily reinforced concrete in locations where blasting would never be approved. See civils and infrastructure.
There are a handful of specialist contractors. What separates us: we are the manufacturer as well as the service provider for both systems we use, we have been doing this for over 30 years across 500+ silos, bunkers and hoppers, and we work for ten of India's largest cement producers — UltraTech, ACC, Ambuja, Dalmia, Shree, Ramco, JK, India Cements, Heidelberg and Chettinad. What to ask any silo cleaning contractor →
Yes. A plant-down blockage is a different conversation from a planned clean and we treat it that way. Mark your enquiry EMERGENCY, or call +91 93211 12606 directly rather than waiting on email.
Yes — ISO 9001:2015 for quality management and OHSAS 18001 for occupational health and safety. For work adjacent to confined spaces, the safety certification is the one that matters to a plant's HSE department.
Send the vessel type and capacity, the material stored, how long it has been a problem, whether the plant is running or down, and your available shutdown window. Photographs through the top hatch help. We reply to every enquiry within one working day. Contact us.
Yes. We have worked in Saudi Arabia, the UAE, Egypt, Bangladesh and Vietnam, and we supply whipping equipment worldwide with commissioning, operator training and spares.
Yes. If you buy a system, commissioning and operator training are included — we set it up on your vessel, not in a warehouse, and your crew runs it under supervision until they are confident.
It discharges through your normal outlet and conveying system. For cement, coal and ore that means recovered saleable product rather than a disposal cost.
Send the vessel type and capacity, the material, and how long it has been a problem. Photographs through the top hatch help. We reply to every enquiry within one working day.
Plant already down? Call rather than email — we mobilise for emergencies.