Abstract: A pneumatic chisel includes a housing having a double-acting pneumatic cylinder in which a piston including a chisel is movably arranged along a longitudinal axis. The cylinder has a work-side section and a return-side section. The return-side section includes a damping portion and a pressure-equalization opening. The work-side section includes an end-position damping member and a compressed air connection. A compressed air reservoir is connected to the return-side section of the cylinder. A chisel guide housing includes a sealing air chamber. The piston is constructed as one piece with the chisel.

Abstract: Comminuted polysilicon with reduced contamination is prepared using multi-step comminution employing comminution with comminution tools of differing tungsten carbide content and/or grain size.

Abstract: A method for mechanically classifying polycrystalline silicon chunks or granules with a vibratory screening machine, involves setting silicon chunks or granules present on one or more screens each comprising a screen lining in vibration such that the silicon chunks or silicon granules perform a movement which causes the silicon chunks or silicon granules to be separated into various size classes, wherein a screening index is greater than or equal to 0.6 and less than or equal to 9.0.

Abstract: Foreign objects in a conveyed product stream of granular or chunk polysilicon is effected by identifying the foreign objects by eddy current sensors in the conveyor by which the granular or chunk polysilicon is being conveyed.

Abstract: A method for mechanically classifying polycrystalline silicon chunks or granules with a vibratory screening machine, involves setting silicon chunks or granules present on one or more screens each comprising a screen lining in vibration such that the silicon chunks or silicon granules perform a movement which causes the silicon chunks or silicon granules to be separated into various size classes, wherein a screening index is greater than or equal to 0.6 and less than or equal to 9.0.

Abstract: Foreign objects in a conveyed product stream of granular or chunk polysilicon is effected by identifying the foreign objects by eddy current sensors in the conveyor by which the granular or chunk polysilicon is being conveyed.

Abstract: An apparatus is disclosed for comminuting a polycrystalline silicon rod, which apparatus includes a base, at least one movable comminuting tool and optionally at least one immovable anvil. A silicon rod to be comminuted lies on a longitudinal axis oriented parallel or virtually parallel to the surface of the base and can be adjusted between the comminuting tool and anvil. Also disclosed is a method for comminuting a polycrystalline silicon rod.

Abstract: A method for mechanically classifying polycrystalline silicon chunks or granules with a vibratory screening machine, involves setting silicon chunks or granules present on one or more screens each comprising a screen lining in vibration such that the silicon chunks or silicon granules perform a movement which causes the silicon chunks or silicon granules to be separated into various size classes, wherein a screening index is greater than or equal to 0.6 and less than or equal to 9.0.

Abstract: Comminuted polysilicon with reduced contamination is prepared using multi-step comminution employing comminution with comminution tools of differing tungsten carbide content and/or grain size.

Abstract: The invention relates to a polycrystalline silicon portion having at least one fracture surface or cut surface, which includes metal contamination of from 0.07 ng/cm2 to 1 ng/cm2. The invention also relates to a method for breaking a silicon body, preferably a rod of polycrystalline silicon, including the steps: a) determining the lowest natural bending frequency of the silicon body; b) exciting the silicon body in its lowest natural bending frequency by means of an oscillation generator, the excitation being carried out at an excitation point of the silicon body such that the silicon body breaks at the excitation point; so that a silicon portion having a fracture surface results which includes metal contamination of from 0.07 ng/cm2 to 1 ng/cm2.

Abstract: An apparatus is disclosed for comminuting a polycrystalline silicon rod, which apparatus includes a base, at least one movable comminuting tool and optionally at least one immovable anvil. A silicon rod to be comminuted lies on a longitudinal axis oriented parallel or virtually parallel to the surface of the base and can be adjusted between the comminuting tool and anvil. Also disclosed is a method for comminuting a polycrystalline silicon rod.

Abstract: Polysilicon is crushed with a minimum of manual and machine crushing steps by utilizing a large diameter roll crusher, the circumferential crushing surface of which is formed of a plurality of reversibly mounted, close fitting hard metal plates. Reproducible crushing along with such low metal contamination that subsequent cleaning of the crushed polysilicon is not necessary are both obtained.

Abstract: Polysilicon is crushed with a minimum of manual and machine crushing steps by utilizing a large diameter roll crusher, the circumferential crushing surface of which is formed of a plurality of reversibly mounted, close fitting hard metal plates. Reproducible crushing along with such low metal contamination that subsequent cleaning of the crushed polysilicon is not necessary are both obtained.

Abstract: A mechanical crushing apparatus for comminuting a polycrystalline silicon ingot, has a base and opposed comminuting and mating chisels, the chisels having longitudinal axises oriented at right angles to a longitudinal axis of the base and parallel to the surface of the base, and being movable in such a manner that a silicon ingot to be comminuted and which rests on the surface of the base can be positioned between the chisels such that all the chisels in the region of the silicon ingot are in contact with the silicon ingot, and comminution chisels in front of and behind the silicon ingot can be moved in the direction of their longitudinal axis to within a safety distance of the respective mating chisel, and the comminution chisels act on and break up the silicon ingot by means of sudden movement(s) in the direction of their longitudinal axes.

Abstract: A mechanical crushing apparatus for comminuting a polycrystalline silicon ingot, comprises a base and opposed comminution and mating chisels, the comminution chisels and mating chisels having longitudinal axises oriented at right angles to a longitudinal axis of the base and parallel to the surface of the base, and being movable in such a manner that a silicon ingot to be comminuted and which rests on the surface of the base can be positioned between the chisels such that all the chisels in the region of the silicon ingot are in contact with the silicon ingot, and comminution chisels in front of and behind the silicon ingot can be moved in the direction of their longitudinal axis to within a safety distance of the respective mating chisel, and the comminution chisels act on and break up the silicon ingot by means of sudden movement(s) in the direction of their longitudinal axes.