ChemStone BT-90 is an ethylene glycol mixture used to reduce the viscosity of heavy black liquor in the Recovery area.

A reduction in black liquor viscosity has the potential to help mills improve liquor flow from the concentrator to the boiler. Also an improvement in black liquor firing rate has been measured.


  • Modifies Rheology of heavy black liquor


  • Improves black liquor flow
  • Improves heat transfer
  • Increases total solids in recovery boiler

Physical Properties



ChemStone BT-90 can be used in direct contact evaporators in which the black liquor is cascaded over a large heated surface area. It can also be used in liquors above 50% solids in standard evaporator trains to assist in flow properties of heavier black liquor. Black liquor viscosity for liquors above 50% is often times the limiting factor in heat transfer in evaporator bodies. Improvements in black liquor flow to the boilers can be expected.

Containers and Shipping

ChemStone BT-90 is available in non-returnable bulk bins (250 gal).