The kilns primarily produced dolime to meet the increasing demands of the Hartlepool Magnesia Works but later expanded the range to produce the following range of products:

Dolime ----- calcined dolomite, a raw material for hartlepool Works
Dolomet --- a calcined dolomite flux for steelmaking
Lime ------ calcined limestone, from high purity stone purchased externally

 

Gradually as the dolime tonnages to Hartlepoool reduced because of increased international competition in a declining refractory market, the Dolomet tonnages became more important to Thrislington Works. This resulted in a conflict of interest. Dolomet needed to be of a higher fired density than dolime to meet steelmaking requirements and survive the journey to the end users as far away as Wales. To reduce the 'undersize' material in the dolomet, the product was screened prior to despatch and in the interest of overall efficiency the screened fines sent as part of the dolime supply to Hartlepool. Eventually Hartlepool Works received more screened fines than run of kiln product which gave rise to both quality and processing problems.

The dolomite reserves were managed to maximum effect and different qualities were blended to meet customer specifications. This helped to conserve the higher quality stone in the quarry. Several levels generating stone for magnesia production, metallurgical applications and civil engineering. In 1982 after a public enquiry, Thrislington Works was granted permission for a major extension to the east of the existing quarry.