Sardon International Ltd


Sardon International has been offering a personal touch to process engineering projects since 1980. Over that period, its Saxifrage® pulverising and drying equipment has provided a low cost, low maintenance, and very reliable means for the production of dry powders. The name Saxifrage® is derived from the Latin for 'rock breaker'.

The Saxifrage® has been produced for 38 years and is available in 8 different sizes which can from process 300 Kilos to 40 tonnes per hour depending on the material. It provides:

  • A ground material of close size distribution ideal for either a selfcontained pulverising facility or for the firing of coal and other volatile fuel in boilers, furnaces and kilns.
  • A drying facility of high thermal efficiency.

Saxifrage Machine News

A No.7 Saxifrage machine has just been successfully commissioned at a cement plant in Ireland.

Two more No.5 Saxifrage machines have just been shipped to a  Lime Works in South Africa to complement the one already there as the Works is expanded.

Saxifrage Machine News

Additional benefits


Operating Principle

There is an airswept hammer mill incorporating an innovative classification system. Whilst developed firstly for the production of pulverised fuel for direct or indirect firing, it will grind any friable material not excessively abrasive. Airflow through the Saxifrage® is generated externally and in direct firing systems provides primary air to the burner(s).

Feed material up to 40 or 75mm, according to mill size is metered into the top of the pulverising chamber, and as it becomes smaller is carried by the airstream to a static vane system through which it is drawn spirally inwards. Leaving these vanes, the spinning motion tends to throw large particles outwards back to the grinding hammers. Small particles are drawn to the central discharge. There a multibladed classifier rotor effects final cleaning of the product.

Deliberate adjustment of product fineness is usually achieved by modulation of the mill speed, so an inverter drive is recommended.




The mill is totally lined inside using specially hard steels in those areas where wear occurs most vigourously. All wearing parts can be replaced very quickly and easily, and many can be reversed for increased life. Production scale test facilities are available allowing trials with customers' own materials.

Pulverised Fuel Firing

As the rate of feed to the mill is increased, the rising density of material in the airflow effectively increases its viscosity, enhancing air drag forces in the classification zone and allowing coarser material to leave the machine. On a direct firing application therefore, as the firing rate is increased and the flame becomes larger, allowing extra time for burn-out, the pulverised fuel becomes coarser, conserving power and minimising wear. When the firing rate is decreased the P.F. automatically becomes finer, intensifying and stabilising the flame, and allowing maximium turn-down.

In a grinding facility, a constant product size distribution is easily achieved by control of the feed rate according mill load, but the above effect still prevents product contamination by coarse nibs when the feed is stopped or started as can happen with other types of mill.

As the time spent by material in the mill is measurable in seconds, a direct-fired system can accurately follow load fluctuations in boilers and the like. Passing the air through a cyclone and re-entraining the P.F. after the fan saves energy and avoids fan wear.


Drying is achieved by heating the air supply to the mill. Particles of the material being ground are fully dispersed in that air by the grinding hammers. As small, easily-dried particles are removed from the mill as soon as they are formed, the material is not itself overheated, and extremely efficient drying is possible. Product moisture content is adjusted by control of the mill outlet temperature, modulating the heat input accordingly. Recycle of a portion of the airflow enhances drying efficiency and can inert the atmosphere in the system.


Typical materials which can be processed include:

  • Limestone
  • Chalk
  • Gypsum
  • Anhydrite
  • Kaolin
  • Ball Clay
  • Bentonite
  • Coal
  • Lignite
  • Petroleum coke
  • Sludges
  • Filtercakes.

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Please contact us using the details at the top of this page.

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