High-basicity aluminum chlorohydrate (ACH) plays two distinct roles in the paper industry: as an efficient sizing agent and as a coagulant that clarifies process water, and both matter to Australian pulp and paper mills facing tight trade waste and EPA limits. With more than 23% Al2O3 and 82-85% basicity, ACH delivers strong charge neutralisation and sizing performance at low dose, with a negligible effect on pH and low sludge generation. For mills under pressure to cut fresh-water use, recover fibre and keep effluent within load limits, that combination is valuable. This guide explains what ACH is, why high basicity benefits sizing and process-water treatment, and how to select, dose and apply it. From recycled-fibre packaging mills to fine-paper operations, correctly applied ACH improves sheet quality, water clarity and compliance. Mills that get their wet-end and effluent chemistry right gain on quality, cost and compliance all at once. That is the case for high-basicity ACH in the mill.

Aluminum chlorohydrate (ACH) is a highly polymerised, water-soluble aluminium compound with the formula Al2(OH)5Cl·2H2O. It carries the highest Al2O3 content (over 23%) and the highest basicity (82-85%) of any commercially available aluminium-based solution, and it is supplied as a ready-to-use liquid.

Two jobs in one chemical. In papermaking, ACH acts both as a sizing agent and as a coagulant for process water. As a sizing agent it helps control how the sheet interacts with water, improving water resistance and printability. As a coagulant it neutralises the negative charge on fibre fines, fillers and colloidal material, clearing process water and helping retain fibre in the sheet.

Why pre-polymerised matters. Conventional aluminium salts consume alkalinity and shift pH as they react. ACH is already neutralised, so it works immediately and barely changes pH, which is important in a wet-end where pH affects sizing, retention and machine runnability.

Blend flexibility. ACH can be combined with organic polymers such as PolyDADMAC or polyamine to sharpen retention and drainage performance in demanding furnishes.

As a sizing agent, ACH helps a mill control the sheet's water resistance and surface behaviour without the pH swings of conventional salts, while in the process-water circuit it delivers the strong charge neutralisation that clears fines, fillers and colloids. Supplied as a ready-to-use liquid, it is metered with standard pumps and holds its properties in storage.

How it compares with conventional salts. Alum and aluminium chloride consume alkalinity and depress pH, forcing mills to compensate and risking upsets to sizing and retention. ACH is already neutralised, so it works immediately, barely changes pH and performs reliably in variable process water and recycled fibre, often at a lower dose and with less sludge.

Australian pulp and paper mills operate under pressure on three fronts: raw-material cost, water use and effluent quality. Recycled-fibre packaging mills, newsprint and fine-paper producers all face trade waste agreements with their local water utility and EPA licence conditions on suspended solids, colour, COD and nutrients. A well-chosen coagulant addresses all three pressures at once.

Better sizing and sheet quality. ACH delivers consistent sizing performance, helping mills hold sheet specifications while using less chemical and tolerating variability in furnish and process water.

Clearer process water and fibre recovery. By coagulating fines, fillers and colloids, ACH improves water clarity, supports fibre retention and reduces material lost to the effluent.

Low dose, low sludge. ACH's high Al2O3 content means less product is required, and its low water-insoluble content produces less sludge, cutting dewatering and disposal costs.

Negligible pH impact. Because ACH is heavily neutralised, it barely moves wet-end pH, so sizing and retention chemistry stay stable and alkali correction is rarely needed.

Water and compliance economics reinforce the case. Mills that reuse clarified process water draw less from the grid and discharge less to sewer, easing both utility costs and effluent load. Where trade waste charges are levied on load - the mass of solids, COD or colour per day - more efficient coagulation directly lowers the bill and creates headroom within licence limits.

Total cost of ownership should guide the choice. A concentrated, predictable ACH that cuts dose, lifts clarity and reduces sludge often lowers the annual cost of both sizing and effluent treatment, even before the reduced compliance risk is counted.

Recycled-fibre mills, in particular, face highly variable furnish and carry more colloidal stickies and fines, which a strong, pH-stable coagulant such as ACH helps control.

Operational reliability matters too. Paper machines run continuously, and any change in wet-end chemistry can cause breaks, deposits or off-spec sheet. ACH's stable, pre-polymerised chemistry avoids the swings that conventional salts can cause, so mills gain not only lower chemical cost but also fewer unscheduled stops and less broke.

Environmental expectations from customers and regulators are rising. Brands increasingly demand responsibly produced paper and lower effluent loads, and mills must demonstrate continuous improvement. Efficient coagulation that reduces solids, colour and COD in discharged water supports that goal while protecting the local receiving environment.

Logistics are straightforward: ACH ships as 275 kg drums, 1,350 kg IBCs or a 25 MT flexitank, suiting both small specialty mills and large integrated sites.

ACH is simple to use, but the wet-end and effluent plant reward a structured approach. Follow these steps.

Clarify what ACH must achieve: sizing performance in the sheet, process-water clarification, or both. Record furnish type, wet-end pH, water hardness, fines and stickies load, and the effluent plant's discharge limits.

For process water and effluent, test ACH dose against settled turbidity, colour removal and sludge volume. For sizing, trial it at the wet-end and measure sheet water resistance and printability against your current chemistry, starting with a low dose and bracketing upward.

Dose ACH at the wet-end or ahead of clarification under good mixing. Where you also use organic polymers, add ACH first for charge neutralisation, then the polymer under slower shear for bridging. Keep shear within the polymer maker's limits.

Calibrate metering pumps and set control ranges. Monitor sheet quality, machine runnability, process-water clarity and trade waste parameters on an ongoing basis, and review the setpoint whenever furnish or production changes.

Keep ACH sealed in a dry, ventilated place away from rain, heat and sunlight, and never store it with alkaline chemicals such as lime or bleach. Follow the safety data sheet and site WHS practice, and use corrosion-resistant dosing equipment.

Consider a recycled-fibre packaging mill whose process water carries a heavy load of fines and stickies, and whose trade waste charges are rising. ACH is dosed ahead of dissolved-air flotation and the effluent clarifier. Jar tests set the dose, and operators see settled turbidity, colour and COD fall while sludge volume drops. Because ACH barely shifts pH, the wet-end chemistry stays stable and there is no need for alkali correction. The mill reuses clearer water, discharges a lower pollutant load and reduces both its sewer charges and its fresh-water intake.

Do not apply ACH without first matching the dose to the current furnish, which can change daily. Introduce it gradually so the machine stays stable, and validate both sheet quality and effluent parameters before a full changeover. Because sizing and clarification interact, review the whole wet-end when you change coagulant, not just the effluent plant, so that sheet quality and machine runnability are protected. Keep dose points and shear within the polymer maker's limits where organic additives are used, and store ACH away from alkalis such as lime or bleach.

Where effluent limits include colour or COD, extend the jar testing to cover these parameters as well as turbidity, so the chosen dose protects every consent condition. Keep spares and corrosion-resistant dosing parts on hand so a change of grade never stalls the machine.

In papermaking, ACH serves two purposes: it is a sizing agent that helps control the sheet's interaction with water, and a coagulant that clarifies process water by neutralising the charge on fines, fillers and colloids. Because it is highly concentrated and pH-stable, it improves both sheet quality and water clarity at low dose.

ACH is far more concentrated and more highly polymerised than alum or aluminium chloride. It works at lower doses, produces less sludge and barely changes pH, so sizing and retention chemistry stay stable. It also performs reliably in cold or variable process water, where conventional salts can be sluggish or unpredictable.

The dose must be set by jar testing on the actual process water, because furnish, hardness and fines load vary. Because ACH is so concentrated, doses are low. Operators judge performance on settled turbidity, colour and sludge volume, starting from a small dose and increasing until clarity targets are met.

Yes. ACH is effective at removing suspended solids and associated COD, colour and phosphorus, which are the parameters most trade waste agreements and state EPA licences regulate. Lower solids and COD mean lower load-based charges and more headroom within discharge limits.

Very little. ACH is already heavily neutralised, with basicity of 82-85%, so it consumes almost no alkalinity and produces a negligible pH change. That stability protects sizing and retention chemistry and usually removes the need for alkali correction in the wet-end.

ACH ships in 275 kg drums, 1,350 kg IBCs, or a 25 MT flexitank in a 20-foot container. Store it sealed in a dry, ventilated place away from rain, heat and sunlight, and never with alkaline chemicals such as lime or bleach, which would cause it to fail. Follow the safety data sheet at all times.

For Australian paper mills balancing sheet quality, water use and effluent compliance, aluminum chlorohydrate is a rare dual-purpose tool. Its high Al2O3 content and 82-85% basicity deliver efficient sizing and coagulation at low dose, with negligible pH impact and low sludge, while its stable chemistry suits variable furnishes and recycled fibre. Define the duty, jar-test the dose, fix the sequence and store it correctly, and ACH helps mills improve sheet quality, recover more fibre, reuse more water and keep every discharge parameter inside trade waste and EPA limits.