PAM for Mining

Tailings Thickening & Settling

PAM dramatically accelerates tailings settling in thickeners and ponds. For acidic ore tailings (gold, copper, molybdenum), nonionic PAM is preferred as it remains stable at low pH. For neutral-to-alkaline tailings (iron ore, coal), anionic PAM provides faster settling rates.

Coal Washing

In coal preparation plants, anionic PAM flocculates fine coal slurry in thickeners, enabling clean water recovery for reuse. Typical dosage: 20-50 g/ton of coal. Our medium-molecular-weight APAM achieves 90%+ water recovery in closed-loop systems.

Gold & Copper Mining

Nonionic PAM handles the acidic conditions in gold CIL/CIP circuits and copper heap leach operations. It settles fine particles without interfering with cyanide or acid leaching chemistry. Also used in CCD (counter-current decantation) circuits.

Iron Ore Processing

High-molecular-weight anionic PAM is the standard flocculant for iron ore tailings. It works in both wet magnetic separation circuits and pelletizing plant effluent treatment. Dosage: 30-80 g/ton of ore processed.

Thickener, pond, or filter: the equipment decides the grade

Ore type sets the charge and pH window, but the equipment downstream decides molecular weight and how the polymer must be dosed. The same tailings stream needs different handling in a high-rate thickener, a tailings pond, and a filter press, and a grade chosen only from the ore name will disappoint in at least one of them.

High-rate and paste thickeners run on short residence time, so floc has to form fast and survive the rake. High-molecular-weight anionic PAM is normal here, dosed into the feedwell where mixing energy is available, often split between two points so the second addition rebuilds floc broken by the first. The controlled variables are rise rate, bed depth, underflow density, and rake torque — and rake torque is the one that punishes over-dosing, because an over-flocculated bed becomes stiff enough to stall the mechanism.

Tailings ponds and conventional thickeners are more forgiving on floc strength and more sensitive to cost per tonne, since residence time does the work that polymer does in a high-rate unit. Dosage sits at the lower end of the range and the objective shifts from throughput to supernatant clarity for water return.

Filters and presses want a floc that releases water rather than one that settles quickly. A large open floc that performs well in a thickener can blind filter cloth, so grades are often selected shorter-chain than the settling duty would suggest, and the useful bench measurement is filtration rate rather than settling velocity.

Water recovery is where the economics sit

On most sites the flocculant budget is justified by returned process water rather than by clarity itself. Water that leaves in the underflow has to be replaced from a licensed source, pumped, and in arid regions paid for at a rate that dominates the polymer line. Raising underflow density even slightly changes the volume of water recovered per tonne of ore, which is why thickener performance is usually tracked as recovered water rather than as settling rate.

This is also why polymer consumption per tonne is a weak comparison between sites. A mine running a closed loop in a dry region and one discharging to a large pond will rationally dose differently on identical ore. When comparing supplier quotations, convert to cost per cubic metre of water recovered, or per tonne of dry solids thickened, before comparing cost per tonne of powder.

Dosing systems and make-up on a mine site

Mine sites consume polymer in tonnes per month, which changes the make-up problem from a laboratory task into a plant one. Dry PAM needs full hydration before it reaches the feedwell, typically 0.1-0.3% stock solution with 30-60 minutes of gentle ageing, and at site volumes that means a properly sized wetting head, ageing tank, and dilution loop rather than a mixing drum. Powder introduced too fast forms gel lumps that pass through the circuit unused, so a plant can appear to be dosing at specification while delivering far less active polymer than the invoice suggests.

Two site-specific factors are worth checking early. Make-up water quality matters: hard or saline process water screens anionic charge and reduces effective viscosity, so a site preparing polymer in recycled water may need a different grade from one using fresh water on the same ore. Temperature matters at altitude and in winter, where cold water slows both dissolution and floc growth and the fix is usually longer ageing time rather than a different product.

Supplying PAM to a mine site

Mining volumes and locations shape the commercial side more than the technical side. Sites consume in tonnes per month against a production schedule, so after a trial most move to a standing monthly quantity rather than reordering as stock runs down, and remote sites carry buffer stock sized to their inland transport time rather than to sea freight. Standard export packaging is 25 kg bags — kraft paper with plastic liner, or PE — and jumbo bag options are worth discussing where site handling equipment suits them.

For a trial, send ore type and process route, slurry pH and solids concentration, the thickener or filter type with its rise rate or throughput, make-up water quality, target underflow density, monthly tonnage, destination port and inland leg, and the documents your site requires. That is enough to propose a starting grade and a bench test plan. Our terms are MOQ 500 kg for trials, free samples before bulk confirmation, 7-10 day lead time for common grades, and T/T or L/C payment. Ore-specific detail is in our guides for gold, copper, iron ore, and coal washing, and the factory background is on our China PAM supplier profile.

Four signals that tell you the dose is wrong

A thickener gives continuous feedback on the flocculant programme, and most sites already log the numbers that matter. Overflow turbidity rising while underflow density holds usually means underdosing or a floc too fragile to survive the feedwell — the fines are simply not being captured. Underflow density falling while overflow stays clear points the other way: flocs are large and open, trapping water inside the bed rather than releasing it, which is the normal signature of overdosing or of a molecular weight too high for the duty.

Rake torque climbing over a shift is the expensive signal. Over-flocculated beds compact into a mass the rakes have to shear through, and the operating response — slowing the rakes or raising the bed — tends to make it worse. On paste and deep-cone thickeners this is the practical ceiling on dose, not cost. The fourth signal is a bed level that will not hold steady at a constant feed rate, which normally means the polymer is arriving at inconsistent strength; that is a make-up problem rather than a grade problem, and the place to look is the wetting head and ageing time rather than the product.

Treating these four readings as a set is what separates a controlled circuit from a dosed one. A site that only watches overflow clarity will drift upward in consumption for months without anything looking wrong, because clarity keeps improving as dose rises long after underflow density has started to suffer. Setting an acceptance band on both ends — a clarity target and an underflow density floor — gives operators a reason to reduce dose, which is usually where the savings on a mature circuit actually are.

PAM Selection by Ore Type

Mining PAM FAQs