Abstract: Realized is a solid substance concentration managing method which allows quick detection of an abnormality in a chemical reactor. The present invention is an invention of a solid substance concentration managing method of managing a concentration of a solid substance which is contained in a residue that is discharged in a reaction product gas processing step included in a trichlorosilane producing method, the solid substance concentration managing method including a concentration measuring step of measuring the concentration of the solid substance which is contained in an after-crystallization residue that is obtained by crystallizing part of aluminum chloride.

Abstract: Provided is a method for producing polycrystalline silicon at a lighter environmental load and at low production cost. A method in accordance with the present invention for producing polycrystalline silicon includes: a silicon deposition step; a separation step; a hydrogen chloride removal step; a hydrogen refining step; an activated carbon regeneration step; and a circulation step.

Abstract: Realized is a solid substance concentration managing method which allows quick detection of an abnormality in a chemical reactor. The present invention is an invention of a solid substance concentration managing method of managing a concentration of a solid substance which is contained in a residue that is discharged in a reaction product gas processing step included in a trichlorosilane producing method, the solid substance concentration managing method including a concentration measuring step of measuring the concentration of the solid substance which is contained in an after-crystallization residue that is obtained by crystallizing part of aluminum chloride.

Abstract: Provided is a method for producing polycrystalline silicon at a lighter environmental load and at low production cost. A method in accordance with the present invention for producing polycrystalline silicon includes: a silicon deposition step; a separation step; a hydrogen chloride removal step; a hydrogen refining step; an activated carbon regeneration step; and a circulation step.

Abstract: Disclosed is a process for the preparation of an anorthite sintered body, which comprises preparing a formed body of at least one powder selected from the group consisting of (i) a calcium type zeolite having an SiO.sub.2 /Al.sub.2 O.sub.3 molar ratio lower than 3, (ii) an amorphous calcination product obtained by calcining said calcium type zeolite and (iii) a mixture of said calcium type zeolite or said amorphous calcination product and an alkaline earth metal compound, and sintering the formed body at a temperature lower than 1000.degree. C.