Process for making a detergent composition
A continuous process for making a particulate detergent composition or component is provided. The process comprises feeding starting materials comprising a surfactant acid precursor and a particulate alkaline neutralising agent into a mixer/granulator to produce a granulated product stream, characterised in that a fraction of the product stream is cooled and recycled into the mixer/granulator.
1 . A continuous process for making a particulate detergent composition or component which comprises feeding starting materials comprising a surfactant acid precursor of an anionic surfactant and a particulate alkaline neutralising agent into a mixer/granulator to produce a granulated product stream, characterised in that a fraction of the product stream is cooled and recycled into the mixer/granulator, the recycle stream being from 30 to 50% of the mass flow rate of the product stream and wherein the recycle stream immediately after separation from the product stream contains particles which have a number average particle size which is less than that of the product stream.
2 . A process according to claim 1 , wherein the temperature of the recycle stream is at least 10° C. below, preferably at least 20° C. below, more preferably at least 30° C. below, more preferably at least 40° C. below, most preferably at least 50° C. below that of the mixer/granulator.
3 . A process according to claim 1 or claim 2 , wherein the recycle stream immediately after separation from the product stream contains particles which have a number average particle size which is less than 50% of that of the product stream, more preferably less than 30% of that of the product stream.
4 . A process as claimed in any preceding claim, wherein the recycle stream has a surfactant concentration which is within 5%, preferably within 3%, ideally within 2%, of that of the product stream.
5 . A process as claimed in any preceding claim, wherein the product stream enters a fluidised bed and an exit stream from the fluidised bed is the recycle stream.
6 . A process as claimed in any preceding claim, wherein the temperature in the mixer/granulator is no greater than 100° C., preferably no greater than 80° C.
7 . A process as claimed in any preceding claim, wherein the starting materials comprise a first feed stream comprising at least 10 wt % of surfactant acid precursor and a second feed stream comprising a particulate alkaline neutralising agent and optionally an additional feed stream in addition to the recycle stream.
8 . A process as claimed in any preceding claim, wherein the starting materials comprise a heat-sensitive surfactant or acid precursor thereof.