A hopper apparatus (100) provides a conveyance passage (150) equipped with a nitrogen purge system. In operation, the hopper apparatus (100) is installed over an opening of a process vessel (200). Chemical matter may be conveyed through the conveyance passage (150) to land within the process vessel (200). The hopper apparatus may have a flap valve (141) that serves to isolate the interior space of a process vessel (200) from the ambient environment outside the process vessel (200). The hopper apparatus (100) may also inject nitrogen at various rates into the falling stream of chemical matter as it is conveyed into a process vessel (200). The hopper apparatus (100) may also provide a ventilation sleeve (180) providing ventilation and extraction of dust and vapors emitted from the falling stream of chemical matter.