Continuous one-step prepn. of powdered activated charcoal - suitable for use as a decolourising agent in prepn. of pharmaceuticals.

摘要

Continuous one-step process for prepn. of powdered activated charcoal from mature timber hogged chips or wood charcoal (as raw materials) in a blast furnace (with a ratio of height to diameter of 7:1) with carbonisation, activation and post-activation zones, in which the raw materials (contg. less than 5 wt. % of water) are added to the upper part of the blast furnace and diffuse through the furnace at a speed of 0.2-1.5 m/hr from top to bottom (through the action of water vapour, air and hot gas), and exhaust gases are immediately removed, comprises: (a) carbonisation of the raw materials at 700-850 deg.C with introduction of 10-200 kg/hr of water vapour at a height of 70-75% (based on the total height of the furnace) with a flow speed of up to 3.2 m/sec. (b) activation in the activation zone in the presence of water vapour (150-500 kg/hr at a height of 40-45% and with a circulation speed of 2.4-7.9 m/sec) air (50-350 Nm3/hr at a height of 32-38% and with a circulation speed of 0.7-5.5 m/sec.) and process hot gas (at a height of 30-32%), and (c) post-activation by addn. of water vapour (50-300 kg/hr at a height of 15-20% and with a circulation speed of 0.7-5 m/sec) in the absence of oxygen. All heights are based on the total height of the blast furnace. USE/ADVANTAGE - The powdered activated charcoal is useful as a decolourising agent in the pharmaceutical industry. The process gives a prod. with a defined pore volume and has an optimal quality to yield relationship. The prod. is suitable for direct use as a decolourising agent.