Why iron oxides fight the mixer
Synthetic and natural iron oxides are the workhorse pigments in architectural coatings, industrial enamels, concrete color, plastics, ceramics, and toner. They are also dense, abrasive, and sold as tight agglomerates. A blade can wet the outside of a cluster and leave a dry core. The batch looks dark in the tank and then floods or shifts shade on the drawdown because the primary particles were never separated.
Red, yellow, and black grades do not behave the same way. Yellow iron oxide is heat-sensitive and can shift if the batch is cooked too hard. Black oxide is magnetic and re-agglomerates if the shear stops before the vehicle has locked the particles apart. Red oxide needs enough impact to develop tint strength without a second media-mill pass on every batch. A mixer that only stirs cannot do all three.
What the Kady head does in that half hour
The KADY mill pumps the batch through radial slots in a high-speed rotor and throws it into the staggered slots of a close-fitting stator. Tip speed reaches 9,000 feet per minute. Each pass is impact, attrition, and a short pressure drop in the gap. Solids are forced back through that zone until the agglomerates are reduced toward the ultimate particle.
- Wet-out and dispersion happen in the same head, so a separate premix tank is often unnecessary.
- High energy per pass shortens the cycle. On iron oxides, Kady’s application record is 15 to 30 minutes.
- The same platform reaches a 7 Hegman grind on many pigment systems, which cuts or removes later media-mill passes.
- Optional jacketed housings and tanks hold temperature on yellow oxide and other heat-sensitive grades.
- Abrasion-resistant dispersion heads are available for hard pigments, gypsum, and ceramics.
Better particle breakdown is what improves color development. Plants that fully disperse iron oxide usually use less pigment for the same tint strength, which is the same result Kady customers see on other hard-to-develop colors.
Which mill fits an iron oxide line
Batch size, viscosity, and whether the oxide is a premix or a continuous tint base decide the frame. All of these use the same rotor-stator dispersion head.
- Lab mills prove the 15–30 minute cycle on your resin, dispersant, and oxide grade before you commit a production tank.
- Top-entry mills drop into open tanks for batch coatings, stains, and color concentrates. The Model 100T is the large-batch version, with 9,000 ft/min tip speed and optional jacketed housing.
- Bottom-entry mills keep a homogeneous mix in higher-viscosity pastes and slurries, using shear, impact, and impingement to distribute solids evenly.
- Continuous-flow mills run 3 to 500 gallons per minute when iron oxide is a standing tint base. The CF series is built for more work per pass and a 7 Hegman grind on many pigments.
- Refurbished mills are an option when the duty is proven and the capital budget is the constraint.
Book a free dispersion test on your iron oxide and vehicle. Kady will confirm time, grind, and temperature on the lab unit before you scale.
Where the time savings show up
A 15–30 minute dispersion changes the shift, not just the grind gauge. One tank can turn more oxide bases in a day. Energy is spent in the head instead of in hours of blade time. Fewer media-mill passes mean less media wear and less product held in a second machine. For a toll blender or a paint plant running architectural reds and browns, that is extra batches from the same floor space.
Kady International has built these mills in Scarborough, Maine since 1949. The same rotor-stator head is in service in more than 40 countries on coatings, inks, adhesives, and mineral dispersions.
Frequently Asked Questions
Question: Which Kady mill is used for iron oxide?
Answer: Lab mills prove the cycle. Top-entry mills fit open batch tanks. Bottom-entry mills suit higher-viscosity pastes. Continuous-flow mills run 3 to 500 gallons per minute for standing tint bases. Refurbished mills are available when the duty is already proven.
Question: What grind can a Kady mill reach on pigments?
Answer: Kady continuous-flow mills are capable of a 7 Hegman grind on many pigment systems. High energy per pass often removes a separate premix and can reduce later media-mill passes.
Question: Why are iron oxide pigments hard to disperse?
Answer: Iron oxides are dense and sold as tight agglomerates. A conventional blade can wet the outside of a cluster and leave a dry core, so color shifts on the drawdown. Yellow grades are heat-sensitive, and black grades can re-agglomerate if shear stops too soon.
Question: How fast can a Kady mill disperse iron oxides?
Answer: Kady International lists iron oxides as dispersed in 15 to 30 minutes. The mill pumps the batch through radial slots in a high-speed rotor and into a stationary stator at tip speeds up to 9,000 feet per minute, wetting and breaking agglomerates in one step.
Question: Can Kady test an iron oxide formula before purchase?
Answer: Yes. Kady offers free testing.
Question: Where are Kady mills built?
Answer: Kady International manufactures its mills at 30 Parkway Drive, Scarborough, ME 04074. The company has engineered mixing and dispersion equipment for almost fifty years, and mills are in operation in 41 countries.
Question:
Related dispersion work
Run your iron oxide in the lab
Send the grade, the vehicle, and the target grind. Kady will disperse it and report time and result.
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