Amorphous silicon for use in foods, drugs, cosmetics and feed, and production method and production device thereof

A method of manufacturing an amorphous silica by burning rice husks in a combustion apparatus, where the combustion apparatus includes a rotating kiln (2), a combustion chamber (3) for supplying heat to an entire interior of the kiln (2), and a heating source (4) facing the inside of the combustion chamber (3), the kiln (2) having a helical blade (31) and stirring blades (41) disposed therein, a material supply piping (15) having a supply screw (16) disposed upstream thereof, an upstream exhaust gas pipe (22) disposed upstream thereof, a downstream exhaust gas pipe (19) disposed downstream thereof, a water distribution pipe (12) at an end of the kiln (2), a drying section (2a) being set in the inside thereof to evaporate moisture contained in the rice husks, and a combustion section (2b) which is set in the inside thereof to burn the rice husks dried in the drying section (2a), and an atmosphere-oxygen supply pipe (26) for supplying atmosphere gas or oxygen gas into the inside of the kiln (2), the method comprising:

• supplying the rice husks into the inside of the kiln (2) via the material supply piping (15) by the screw (16);
• evaporating moisture contained in the rice husks by indirect heating of the combustion chamber (3);
• burning the rice husks at a temperature range between 500° C. or more and 700° C. or less by introducing atmospheric gas having a mass of 6.7 times or more and 20 times or less of the weight of the rice husks, or oxygen gas having a weight of 1.4 times or more and 4 times or less with respect to the weight of the rice husks into the inside of the kiln (2) through the atmosphere-oxygen supply pipe (26) while stirring the rice husks;
• and
• at the same time as said burning, discharging combustion gas generated at the time of combustion of the rice husks from the upstream exhaust gas pipe (22) and the downstream exhaust gas pipe (19).