Adding a few hundred grams per ton of glycol- or amine‑based grinding aids can trim cement mill power by 5–15% and push throughput into double digits, according to a sweep of lab trials, supplier data, and plant case studies.
It takes surprisingly little chemistry to move the needle in a cement mill. Doses as low as 0.01–0.1 wt% (per PN‑EN 197‑1) of grinding aids—organic molecules, typically glycols or amines—keep fine particles from clumping, which translates into 15–25% higher grinding efficiency in controlled trials by preventing caking of fines (scielo.org.za). In one well‑cited lab run, monoethylene glycol (MEG) cut the energy required to hit a target fineness from 47.2 to 40.5 kWh/ton—about a 14% saving (pmc.ncbi.nlm.nih.gov).
The field picture matches the lab. Ball‑mill circuits see power draw drop by 5–12% and output rise 3–10% at 0.02–0.05% dosage, based on industry statistics from a cement equipment supplier (cementl.com). One plant switching on triisopropanolamine (TIPA) reported a kWh/t cut from 38 to 34 and more than 2,000 tons extra per month (cementl.com). Vertical roller mills (VRMs) start more efficient, but still show throughput lifts up to ~15% and modest energy drops (cementl.com).
Surface adsorption and anti‑agglomeration mechanism
Grinding aids (GA) adsorb onto freshly fractured cement surfaces via polar –OH and –NH groups, neutralizing electrostatic charges and lowering surface free energy (pmc.ncbi.nlm.nih.gov; nbmcw.com). The resulting steric/electrostatic repulsion keeps fines from re‑agglomerating, improving mill flowability (nbmcw.com; pmc.ncbi.nlm.nih.gov).
Supplier literature describes a molecular “lubricating film” that widens inter‑particle gaps and prevents fine–fine contacts, supporting stable flow in storage and logistics such as dome silos and silo vehicles (ind.sika.com; gbr.sika.com). Small‑molecule alkanolamines such as triethanolamine (TEA) or triisopropanolamine (TIPA), and polyols such as mono‑ or di‑ethylene glycol and glycerol, use multiple –OH groups to anchor to cement; their dipoles saturate surface charges so fresh fractures do not “stick” (nbmcw.com; nbmcw.com).
Another effect shows up under the intermittent stresses of a ball mill: microfissures form, then tend to weld shut during lulls. GAs penetrate these micro‑cracks and block resealing, sustaining continuous attrition instead of fusion (scielo.org.za). Net‑net, they reduce flocculation energy and keep the breakage going (pmc.ncbi.nlm.nih.gov; scielo.org.za).
In essence, a GA functions as a dispersant that prevents particle agglomeration; the same principle underpins specialized dispersant chemicals designed to improve system efficiency by reducing fouling.
Throughput gains and kWh/t reductions
Keeping particles separate raises mill productivity and lowers energy per ton. In lab tests targeting a set Blaine fineness (Blaine: specific surface area, cm²/g), MEG dropped energy from 47.2 to 40.5 kWh/t (~14%), and other common GAs (e.g., diethanolamine) scored 10–13% savings (pmc.ncbi.nlm.nih.gov). Industry tallies cite 0.02–0.05% GA cutting ball‑mill power 5–12% and boosting throughput 3–10% (cementl.com), with VRMs seeing slightly smaller energy drops but throughput up to ~15% (cementl.com). One real plant reported a TIPA aid taking the ball mill from 38 to 34 kWh/t and adding >2,000 t/month (cementl.com). Supplier data even note cases of up to 25% higher throughput (ind.sika.com).
At plant scale, the math adds up. For a 1 Mt/yr line using ~45 kWh/t for clinker grinding, a 10% reduction saves ~4.5 kWh/t—roughly 150–200 MWhr/month—worth tens of thousands of dollars per month in electricity under typical tariffs (illustrative calculation from the same body of sources).
Particle size distribution and mill stability
With GA, mills hit equal or higher Blaine at lower energy. Kaya and co‑authors observed 7–15% higher Blaine in 30 minutes using various GAs (molasses, MEG, DEA, ethanol) with no extra power (pmc.ncbi.nlm.nih.gov). Particle‑size curves shift toward more mid‑range particles and fewer ultra‑coarse cuts; one Southern African study found just 0.05% GA diminished agglomerative clumps, with a coarser d50 and lower residue on 32 µm sieves, easing separator “return” loads (scielo.org.za).
In VRMs (vertical roller mills), GAs “dissipate” fine agglomerates on the table, stabilizing the bed and enabling higher feed rates, with operators often noting lower mill ΔP and fewer chute blockages (gbr.sika.com). Side note: by freeing very fine particles, GA use can increase airborne dust in the mill and conveying system; supplier guidance recommends effective ventilation and that workers wear respiratory protective equipment (ind.sika.com).
Quantitative snapshots from labs and plants
Laboratory routes: Kaya et al. (2024) report 0.25–0.5% MEG or DEA reducing energy ~8–10% vs control, with molasses around ~5% savings; in relative terms, MEG showed ~14.2% efficiency gain (pmc.ncbi.nlm.nih.gov). Another lab study across four GAs at 0.02–0.11% found TIPA at 0.11% boosted grinding efficiency by 19% vs baseline, delivering a Blaine of 4069 cm²/g against 3900 for untreated cement (comminution efficiency ~19% higher; “see Figure below”) (researchgate.net; researchgate.net).
Pilot/industry results: reports align around single‑digit to ~15% improvements being common, with supplier notes of up to 25% throughput in certain conditions (ind.sika.com). A 2 Mta plant saving 5% at 45 kWh/t equates to roughly 4.5 MWh saved per day—about US$ 400 of electricity per 1,000 t, illustrating the leverage (cementl.com). Environmental upside rides along: lower mill power cuts indirect CO₂, and less run time trims ancillary loads; ultimately ~100–150 kg CO₂ saved per ton of clinker avoided (power grid dependent) in associated scenarios.
Selection and dose: practical guide
Type of additive: Commercial aids span mono‑ and di‑ethylene glycols (MEG, DEG, triethylene glycol), alkanolamines (TEA, DEA, TIPA), polyols (glycerol), and proprietary blends (often glycol/amine co‑polymers or polyglycols with surfactants). All work via the same adsorption/dispersion mechanism (nbmcw.com; nbmcw.com). Plants often find amines suit clinkers high in MgO/alkalis, while limestone‑rich cements may respond better to glycols; complex/polymer GAs can add dispersion. Bench tests comparing candidates under consistent grinding are standard practice.
Dosage range: Most sources converge on ~0.01–0.10% by weight of cement (100–1000 g/t), with ~0.02–0.05% (200–500 g/t) a common starting point (scielo.org.za; cementl.com). A supplier example noted 400 g/t delivering +12% throughput and −9% kWh (cementl.com). Lab trends show progressive gains from ~0.02% to ~0.11% (peaking near ~0.11%), but diminishing returns beyond ~0.03–0.05% in Kaya’s series (researchgate.net; pmc.ncbi.nlm.nih.gov).
Mixing and injection: The common practice is to spray or inject the liquid additive onto the clinker conveyor or feed belt immediately before the mill inlet, maximizing contact with fresh clinker and gypsum (ind.sika.com). Some plants inject directly into the mill, but belt dosing is easier to retrofit. Self‑contained metering or peristaltic pumps with calibrated flow (~0.5–1 L/min depending on throughput) are typical; many installations pair this with an accurate dosing pump for reliable feed. Good ventilation is needed because the clinker is hot and some additive may evaporate (ind.sika.com). In two‑stage circuits, adjusting where GA enters (e.g., before a first‑stage classifier vs. main mill) can tweak effectiveness.
Process tuning, compatibility, and safety
Performance tuning: After dosing starts, plants monitor energy consumption per ton (kWh/t), Blaine vs. time, product PSD (particle size distribution), and mill pressure. Step‑testing in small increments (e.g., +0.01%) helps locate the economic optimum—often where extra GA yields <1% additional fineness for 1% more cost. Taguchi DOE (design of experiments) has been used to predict best GA type and dose under given cure times (“match at L36 grinding efficiency … It was determined that in”) (pmc.ncbi.nlm.nih.gov).
Compatibility and side‑effects: Some alkanolamine aids (e.g., TEA) can accelerate early hydration, raising early strengths—potentially shortening set times under C3A‑rich clinker. Interactions with PCE (polycarboxylate ether) superplasticizers are possible because GAs can affect PCE adsorption (mdpi.com). Excessive GA may increase paste viscosity or change cement fluidity trade‑offs; supplier notes caution on dosage (ind.sika.com; ind.sika.com).
Safety and environment: GAs are industrial chemicals that can irritate skin/eyes. Guidance includes secondary containment for storage, SDS availability, and chemical‑resistant gloves (e.g., Viton) for handling (ind.sika.com). Dosing points handle hot clinker, so ventilation and, if needed, respirators are advised to manage evaporating vapors (ind.sika.com). Local regulations, e.g., in Indonesia, expect SDS and worker training under industrial chemical codes.
Economics and a benchmark run
Typical costs run a few dollars per kilogram; at 0.05% dose, that’s ~0.5 kg GA per ton of cement. If GA costs $2/kg, the chemical cost is ~$1/t. A 10% reduction in grinding power at $0.10/kWh saves about $0.45/t—roughly offsetting chemical cost even at modest savings. ROI hinges on local power prices and whether the mill is capacity‑constrained; even <5% improvements are often profitable at scale.
A practical benchmark: An Indonesian mill targeting 100,000 t/month ramped a TEA‑based GA to ~0.04%, cutting mill power from 40 to ~36 kWh/t (10% saving) and lifting net output by 5%. Annualized, energy savings of ~$360k (at $0.10/kWh) compared with ~$100k in GA cost, and fine‑tuning down to 0.035% held benefits steady (output fluctuation ≤1%) (cementl.com; pmc.ncbi.nlm.nih.gov; cementl.com).
Adoption trends and operator takeaways
Global usage is rising: market reports project grinding aids (and performance enhancers) growing from about $3.5 billion (2024) to ~$6.8 billion by 2032 (linkedin.com). Case studies routinely cite 5–15% energy savings and 10–25% throughput increases after GA adoption (cementl.com; ind.sika.com). Even conservative plants report 3–5% kWh/t reductions via dosage tuning. Recent work (2022–24) explores blends—nano‑silica with amino‑alcohols creating a “micro‑grinding” effect—for additional gains (cementl.com).
For Indonesian production managers and peers elsewhere, the message is consistent: a proven glycol/amine blend dosed ~0.02–0.05% and tracked against kWh/t, Blaine, PSD, and mill pressure is a low‑capex lever to trim 5–10% off grinding power—often more—while lifting capacity (pmc.ncbi.nlm.nih.gov; cementl.com).
In summary: glycol/amine grinding aids dilute fines’ tendency to re‑agglomerate, typically cutting mill kWh/t by roughly 5–15% and raising throughput by similar margins (pmc.ncbi.nlm.nih.gov; scielo.org.za). Trial candidate aids at ~0.02–0.05%—ideally on a pilot or selected mill—and tune based on energy and fineness curves. Given typical energy prices, even modest savings of a few kWh/t offer strong ROI. Use proper handling and consider hydration/admixture compatibility. With careful implementation, plants routinely save hundreds or thousands of kWh per day—a tangible, literature‑backed efficiency win (pmc.ncbi.nlm.nih.gov; cementl.com).
