Abstract: There is disclosed a process for producing a polyarylene sulfide (PAS) which comprises reacting a sulfur source with a dihalogenated aromatic compound in the presence of an aprotic organic solvent, characterized in that the process comprises at least one polymerization reaction step wherein a polymer phase as a dispersed phase is in the form of spherical droplets. It is made possible by the continuous polymerization process to discharge the polymer phase and solvent phase from a polymerization vessel at a constant ratio and as a result, to maintain PAS composition (concentration) at a constant level at all times, and thus to provide a continuous PAS production process which is effective for enhancing its molecular weight and stabilizing the same.

Abstract: There is disclosed a process for treating a by-product salt of a polyarylene sulfide which comprises subjecting solid matter containing an aprotic organic solvent and the by-product salt that is formed in the case of producing a polyarylene sulfide by polymerization condensation reaction of an alkali metal sulfide and a dihalogenated aromatic compound in the aprotic organic solvent to a drying treatment followed by a firing treatment of the resultant dryingly treated matter at a temperature in the range of 500 to 1000° C. The above process is capable of enhancing the solubility in water, of the by-product salt comprising sodium chloride as the principal component in the production of polyarylene sulfide, and affording waste water which is lowered in SS and COD in the case where the by-product salt is dissolved in water and is discharged as waste water.