Atritor Limited of Coventry has recently commissioned two new 18A Dryer-Pulveriser systems for Colin Stewart Minchem of Winsford Cheshire. The new facility, with a maximum evaporative capacity of 4,800 kg/h of water, is a fine mineral drying and de-agglomeration operation for fluorspar and represents the latest dedicated contract processing facility for ICI Klea. ICI uses the fluorspar in the production of Fluoric acid.

The Atritor 18A machines, with a maximum installed power capability of 160 kW, are fed with wet fluorspar material at the rear inlet, where the material is immediately flash dried as it mixes with the incoming hot air. They have a maximum capacity of 20,000 m3/h of air, at up to 600°C produced by induction through a natural gas burning, direct-fired heater system - one per machine.

The fluorspar is generally already in specification from a particle size distribution point of view, so the Atritors are set up for a drying and de-agglomeration duty only. Although, inevitably, a small degree of primary particle size reduction does occur, by careful adjustment of the air flow, machine internals and speed, the dryer-pulveriser maintains a consistent quality product.

The 18A is one of a range of eight machines, varying in power from 5.5 - 250kW, developed originally over 80 years ago for the drying and pulverising of wet lump coal and simultaneously firing the resultant fine pulverised fuel into burner systems with its integral blower system. These applications have generally disappeared with the reduction in the use of PF, but   the  Atritor  Dryer-Pulveriser

continues to find applications as a trusted workhorse in the mineral, chemical and food industries for the high efficiency drying of filter cakes, slurries, sludges and wet agglomerated granulates. "The Atritor is a most predictably reliable process machine when the end product is required as a powder" says Neil Telfer, technical manager, Colin Stewart Minchem, " The robust nature of the construction combined with easily replaceable high chrome iron internals, is a maintenance manager's dream come true!"

Although Atritor have a regular champion in the 'A' Series machines, they have not rested on these particular laurels; the new 'B' Series offers a potential 50% increase in evaporative capacity throughout the range, a lighter construction, and is also available in stainless steel. For much finer end products such as ground calcium carbonate, with a potential for highly homogenous surface modification, as well as ultra fine milling and classification, the Multirotor  Cell  Mill  has  been

developed, with a range available up to 500kW drive power. All these machines are available for test at Atritor's Coventry test facility with the original Dryer-Pulveriser also available in Austria and Colorado, USA.

Meanwhile for Colin Stewart Minchem, growth is a welcome feature of Cheshire life with the fluorspar plant representing only 20% of last years total investment in new process equipment.