What Problems Do Grinding Aids Face in Production?

In cement and other industries, grinding aids effectively improve grinding efficiency and reduce energy consumption, but in practice a series of problems arise from changes in operating conditions, formulation limits or equipment mismatches. Below are the common problems and their solutions.

01. Common problems

1. Unsatisfactory or fluctuating output gains

Change in raw material grindability: clinker comes from many sources, and strength and grindability vary between batches, easily causing hourly output fluctuation.

Mill-feed temperature too high: high temperatures (above 200 °C, for example) rapidly evaporate the volatile components before they adsorb onto particle surfaces, so they are lost and the aid stops working; heat also increases electrostatic adhesion, coating the grinding media and reducing efficiency.

High mill-feed moisture: excessive moisture causes ball coating and mill choking, which current grinding aids generally cannot solve.

Changes in grinding process and equipment: replacing grinding media or fans alters material flow in the mill. If flow is too fast, the grinding aid shortens residence time and the finished-product yield drops.

2. Grinding aid failure (malfunction or loss of activity)

Adsorption competition (sites occupied): cement is complex, and high-surface-area materials such as slag and fly ash preferentially adsorb grinding aid molecules like magnets, leaving the clinker particles that need grinding unprotected and wasting mill power.

Molecular deactivation (structural breakdown): inside the mill the environment is hot, alkaline and highly impacted, so some chemical bonds (such as ester bonds) saponify or degrade, destroying the molecule and its effect.

Formulation imbalance (synergy turning into antagonism): excess electrolyte salts in a compound grinding aid raise ionic strength and compress the double layer, flocculating particles; or poorly matched surfactants form micelles and consume the active ingredients.

3. Conveying difficulties and lower shipping efficiency (spillage and backflow)

As a surface-active substance the grinding aid adsorbs an air film on cement particles, lowering bulk density and acting as a lubricant. On inclined belts the sliding force then exceeds friction, causing spillage and backflow that sharply reduce conveying capacity.

4. Unstable dosing and metering errors

Start/stop not synchronised: when the mill suddenly stops feeding, the grinding aid is not stopped in time, causing overdosing that wastes cost and may push cement chloride content over the limit.

Metering affected by environment: the viscosity of liquid grinding aids varies greatly with temperature, so flow is fast and over-dosing occurs when hot and slow with under-dosing when cold; powder grades absorb moisture, stick in bins and arch, making the actual dosing ratio highly unstable.

02. Solutions and optimization measures

1. Formulation optimization for output and failure issues

Build a targeted adsorption system: for complex materials, components with different adsorption preferences work as a group so that key particle surfaces always carry enough grinding aid molecules, solving the adsorption competition problem.

Improve environmental tolerance: optimize the molecular design, avoid easily saponified ester bonds in favour of more stable ether linkages, and choose thermally stable backbones for the hot, alkaline mill environment.

Fine-tune synergy ratios: find the golden ratio between components through experiments and identify the threshold between dispersion and flocculation to achieve spatiotemporal synergy.

Adopt new low-carbon grinding aids: molasses modification, polyol activation and organic acid salt enhancement overcome the retarding effect of multi-component sugars, activate supplementary cementitious materials and improve adaptability to various raw materials.

2. Technical upgrades for conveying and shipping issues

Equipment additions and adjustments: fit frequency vibration units to the horizontal shipping belt idlers to densify the cement; reduce homogenizing air volume and pressure to increase inter-particle friction; fit bar gates in long chutes to soften material impact.

Adjust the grinding aid composition: reduce dispersing and air-entraining components, improve particle grading, raise bulk density and angle of repose to curb excessive flowability.

3. Automation upgrades for dosing and metering

Interlock control: link grinding aid start/stop with the clinker belt scale so that the metering pump stops automatically when the mill stops feeding or trips.

Variable-frequency drive and piping improvements: convert the metering pump motor to a VFD three-phase asynchronous motor so speed is set automatically according to mill output, and improve the piping to prevent deposits on the inner wall from affecting flow measurement.

Optimize spraying: replace traditional trickle feeding with a spray-gun type nozzle that atomises the grinding aid with compressed air into the first chamber, increasing contact area and preventing inlet clogging and wall build-up.

4. Source control of mill feed conditions

Strictly control the clinker temperature at the mill inlet and cool it if necessary to prevent evaporation and static agglomeration.

Strengthen raw material control and keep mill-feed moisture within the capacity of the grinding aid.

In lab-mill trials, fully consider the high temperatures of continuous full-scale operation and raw material variation so that the data truly reflects industrial performance.