Metallurgical silicon containing impurities of carbon and/or carbon-containing compounds is classified and subsequently used selectively for chlorosilane production. The process comprises the steps of: a) determining the free carbon proportion which reacts with oxygen up to a temperature of 700° C., b) directing metallurgical silicon in which the free carbon proportion is ≤150 ppmw to a process for producing chlorosilanes and/or directing metallurgical silicon in which the free carbon proportion is >150 ppmw to a process for producing methylchlorosilanes. As a result of the process, metallurgical silicon having a total carbon content of up to 2500 ppmw can be used for producing chlorosilanes.

Chlorosilanes are produced in exalted yield in a fluidized bed process when the reactor hydraulic diameter, Sauter particle diameter, and superficial gas velocity are used to define a parameter space as a function of Reynolds number and Archimedes number.

The present disclosure relates to a process for producing chlorosilanes in a fluidized bed reactor by reacting a hydrogen chloride-containing reaction gas with a particulate contact mass containing silicon and optionally a catalyst. The chlorosilanes have the general formula H.sub.nSiCl.sub.4-n and/or H.sub.mCl.sub.6-mSi.sub.2. The reactor design is described by an index K1, the constitution of the contact mass without catalyst is described by an index K2.sub.uncat, the constitution of the contact mass with catalyst is described by an index K2.sub.cat, and the reaction conditions are described by an index K3.

The invention relates to a process for converting polychlorosilanes into hexachlorodisilane, by one or more trimeric polychlorosilanes or a trimeric polychlorosilane in a mixture with higher molecular weight polychlorosilanes being exposed to a gas discharge and hexachlorodisilane being formed and isolated.

Chlorosilanes and methods of producing chlorosilanes. The process for producing chlorosilanes includes the step of selecting a chlorosilane having a general formulae (1) H.sub.nSiCl.sub.4-n and (2) H.sub.mCl.sub.6-mSi.sub.2 wherein n is 0 to 3 and m is from 0 to 4. The chlorosilane selected is then placed within a fluidized bed reactor. A hydrogen chloride-containing reaction gas is reacted with a particulate contact mass containing silicon at temperatures of 280° C. to 400° C. Where the operating granulation, understood as meaning the granulation or granulation mixture introduced into the fluidized bed reactor, contains at least 1% by mass of silicon-containing particles S described by a structural parameter S and wherein S has a value of at least 0 and is calculated as follows

[00001]$S=\left({\phi }_s-0.70\right).Math.\frac{{\rho }_{SD}}{{\rho }_F}$

Wherein φ.sub.S is symmetry-weighted sphericity factor, ρ.sub.SD is poured density [g/cm.sup.3], and ρ.sub.F is average particle solids density [g/cm.sup.3].

Generally unusable or difficultly useable dusts of ultrahigh purity silicon can be used to produce chlorosilanes under reasonable reaction conditions by employing a catalyst containing one or more of Co, Mo, W. The process may be incorporated into an integral plant for the production of polycrystalline silicon.

Provided is a method for stably conducting a process for producing chlorosilanes by a chlorination reaction of metallic silicon. When producing chlorosilanes by the chlorination reaction of the metallic silicon, metallic silicon having a sodium content of 1 ppm or more and 90 ppm or less in terms of element and an aluminum content of 1000 ppm or more and 4000 ppm or less in terms of element is used as the metallic silicon. An average particle diameter of the metallic silicon is preferably about 150 μm to 400 μm.

The content of boron compounds in a composition containing at least one halosilane is reduced by bringing the composition into contact with at least one phenylsilane and removing the at least one halosilane. The invention further relates to the use of phenylsilanes for removing boron compounds from halosilane-containing compositions.

The present disclosure relates to a process for producing chlorosilanes in a fluidized bed reactor by reaction of a hydrogen and silicon tetrachloride-containing reaction gas with a particulate contact mass containing silicon and a catalyst. The chlorosilanes have the general formula H.sub.nSiCl.sub.4−n and/or H.sub.mCl.sub.6−mSi.sub.2. The reactor design is described by an index K1, the constitution of the contact mass is described by an index K2 and the reaction conditions are described by an index K3.

When producing chlorosilanes by a reaction between metallic silicon and hydrogen chloride, as the above metallic silicon, a metallic silicon powder having an oil adhering amount of 5 ppmw or less is subjected to the reaction as the metallic silicon.