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Technical Paper
Figure 9: Wassmer Triple Head Grinder and tunnel kilns. All these factors add to cost.
DSF has been able to turn these weaknesses into strengths. The rural location makes it difficult to recruit people; but retention and therefore skill level is high. The location is not suitable for housing and therefore past parent companies have not been tempted to close the operation for building land.
The production of tens of thousands of standards shapes may not be as economic as others, so this has created a focus on difficult to make shapes and specialised materials.
The absence of a tunnel kiln has ensured a wider product range as firing schedules can be made optimum.
Specifically the size of the company has allowed easy communication and rapid decision making; a plot of sales by industry (Figure 11 below ) demonstrates how important this has been to the evolution of the company.
For the near future; that which is palpable, DSF is witnessing continued success and growth in several glass market sectors. The “mullite” solution for long campaign regenerators; a design concept promoted by DSF and traditionally accepted by glass container manufacturers is gaining momentum and has been incorporated in the most recent float furnace
Figure 10: 1700°C Intermittent Kiln
designs. Product development has been integral to this; products which out perform their predecessors whilst remaining cost effective.
The two most pertinent factors for selecting a (Frisil) “mullite” regenerator rather than one based on “magnesite” are:- i) a significant decrease in heat flow through the regenerator; raising thermal efficiency and saving hundreds of thousands of £/Euros and ii) stability, both thermally and chemically as magnesite based structures can distort through temperature/ load and through forsterite formation.
Other expanding markets relate to niche applications; examples are CAZ20, a cast AZS composition with phenomenal resistance to thermal shock (DIN test >30 cycles 1300°C to water). This product is being utilised for glass furnace doghouse items; replacement arches and batch shear bricks.
Calcium Aluminate (DSF Calex Range) in both pressed and cast shapes are replacing sillimanite compositions in alkali rich
applications and
have the potential to replace costly Fused Cast materials in glass melter superstructure.
Spinel (
MgO.Al2O3 ,DSF Frimax range) has completed long campaigns in
oxy-fuel glass melter superstructure (18 years) and will continue to be the optimum choice for melter contruction where alkalis create specific refractory degradation.
DSF evolves and whilst glass is the dominant current market sector, it is acknowledged that the company history is characterised by change; there are many factors that can influence direction and it is envisaged that an aspiration “not to rest on your laurels” will ensure many more decades of refractory supply whatever their application may be.
To provide a firm foundation for the future all kilns are now fired on natural gas, a project of ~£2 million involving a 10km new pipeline.
Minerals processing is a key component of the business accounting for ~35% of turnover; bauxite; chamotte, andalusite, insulating aggregate, flint clay, alumina (calcined, reactive,fused and tabular), spinel (sintered,fused) and volatilised silica are all supplied.
125 years after John West decided to build a factory at Friden, we’re still in business and still looking to the future.
Figure 11 September 2017 Issue ENGINEER THE REFRACTORIES 23
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