With US pricing at $30 per tonne in 1970, in 2006 up to $90 per tonne for salt cake quality and $130 for better grades, sodium sulfate is a very cheap material. The largest use is as filler pass4sure 4A0-103 in powdered home laundry detergents, consuming approx. 50% of world production. This use is waning as domestic consumers are increasingly switching to compact or liquid detergents that do not include sodium sulfate.[12] pass4sure 642-972 Another formerly major use for sodium sulfate, notably in the US and Canada, is in the Kraft process for the manufacture of wood pulp. Organics present in the "black liquor" from this process are burnt to produce heat, needed to drive the reduction of sodium sulfate to sodium sulfide. pass4sure 650-180 However, this process is being replaced by newer processes; use of sodium sulfate in the US and Canadian pulp industry declined from 1.4 Mt/a pass4sure 1Y0-A06 in 1970 to only approx. 150,000 tonnes in 2006