Works fine, although you should specify NaturalParticleSystem= as well.
I, for example, have
NaturalParticleSystem=SmallGreySSys
NaturalParticleLocation=125,135,350 on my Ore Purifier.
Are those values FLH, or XYZ? In other words, which value is height, which brings it towards the bottom left of the screen, and which brings it towards the bottom right.
NaturalParticleLocation=
Specifies the location on the BuildingType where the NaturalParticleSystem= will be displayed. Is measured in pixel offsets in X,Y,Z format with 0,0,0 being the exact center of the structure.