Method for producing chlorosilanes

A process for producing chlorosilanes of the general formula HnSiCl4-n and/or HmCl6-mSi2, where n=1-4 and m=0-4, in a fluidized bed reactor, comprising:

• reacting a hydrogen chloride-containing reaction gas with a contact mass which comprises silicon as a granulation mixture composed of a coarse grain fraction and a fine grain fraction, wherein the average particle size of the fine grain fraction d50,fine is 5 to 400 μm and the average particle size of the coarse grain fraction d50,coarse is 125 to 600 μm, with the proviso that d50,fine is smaller than d50,coarse and the difference d50,coarse−d50,fine is greater than 1 μm, wherein d50,fine and d50,coarse are present in a grain size ratio d50,fine/d50,coarse of 0.02 to 0.9, the fine grain fraction and the coarse grain fraction are present in a mass ratio m(fine)/m(coarse) of 0.05 to 20, and wherein the granulation mixture has a span of particle size distribution d90−d10/d50 of 1 to 100.