PAM Selector

How PAM Selection Actually Works

The tool above narrows the field in three clicks. This section explains the reasoning underneath it, so you can sanity-check the result — or work it out yourself when your situation does not fit a menu.

Step one is charge, not molecular weight

Buyers often open with a molecular weight figure, because that is the number on the datasheet they were handed. It is the wrong place to start. Charge type decides whether the polymer works at all; molecular weight only decides how well it works once the charge is right. Get the charge wrong and no molecular weight rescues it — you will simply feed expensive polymer into the drain.

The rule of thumb: match the polymer charge to the opposite of what you are trying to collect. Most mineral and inorganic suspensions — tailings, coal fines, drilling cuttings, sand-wash slurry — carry a negative surface charge and are bridged by anionic PAM. Most organic solids — biological sludge from a municipal or food-industry plant, paper mill white water, protein-bearing effluent — carry a negative charge that needs neutralising, so they take cationic PAM. Where the suspension is close to neutral, or where salinity would collapse a charged polymer’s coil, nonionic PAM is the safer bridge.

Then charge density, then molecular weight

Once the charge sign is settled, charge density is the dial that matters for sludge. Higher charge density neutralises more surface charge per unit of polymer, which is what a high-solids, highly charged organic sludge needs. Lower charge density leaves more of the chain free to bridge between particles, which is what a dilute suspension needs. Overshoot the charge density on a thin feed and you will re-stabilise the floc — the classic symptom being a jar test that clears beautifully at a low dose and turns cloudy again as you add more. Our charge density explainer works through this in detail.

Molecular weight comes last, and it is a trade-off rather than a maximum. Longer chains bridge further and build larger, faster-settling floc — valuable in a clarifier or a thickener where settling rate is the constraint. But longer chains also make a more viscous make-up solution, dissolve more slowly, and shear more easily. If your polymer passes through a centrifugal pump or a long line before it reaches the feed, some of that molecular weight is destroyed before it does any work, and you are paying for a specification you never receive. Where shear is unavoidable, a mid-range molecular weight delivered intact beats a premium grade delivered broken.

Powder, emulsion, or PHPA

Physical form is a logistics decision more than a chemistry one. Powder ships the most active polymer per kilogram of freight and stores longest, which is why it dominates export orders — but it needs a proper make-up system: a wetting head or eductor, a dissolution tank, and enough ageing time for the chains to hydrate fully. Skipping the ageing step is the single most common cause of “the polymer does not work” complaints, and it looks identical to a wrong-grade problem from the control room. Emulsion dissolves in minutes and suits plants without a make-up rig or with sharply variable load, at the cost of paying freight on the carrier fluid and a shorter shelf life.

PHPA sits apart from the three charge families. It is partially hydrolysed polyacrylamide used as a drilling-fluid additive and in polymer flooding, selected on viscosity behaviour, shale inhibition, and tolerance to brine and temperature rather than on flocculation performance. If your application is downhole, the flocculant selection logic above does not apply and you should start from the reservoir or mud-programme parameters instead.

Where the tool stops and a jar test starts

A selector narrows several hundred commercial grades to a shortlist. It cannot tell you the dose, because the dose depends on your feed solids, your equipment, and the chemistry already in the line — upstream coagulant, lime, ferric, or a competing polymer that has not been flushed out. Anyone quoting you a precise dose without seeing your water is guessing.

The honest sequence is: shortlist by charge and form, jar-test two or three candidates against your actual sample, then optimise the dose and the make-up concentration on the winner. We run that jar test in our applications lab if you send material, and report what we observed rather than what the datasheet promises. The dosage guide covers the PPM arithmetic, and the overdosing note covers how to recognise that you have gone past the optimum — because more polymer stops helping well before it stops costing money.

Once you have a shortlist, our export desk quotes against grade, quantity, and destination port, with TDS, COA, and SDS on every shipment. MOQ is 500 kg for a trial order.