Phosphorous Pentoxide Producing Methods

A phosphorous pentoxide producing method comprising:

• co-grinding a mixture containing phosphate ore, carbonaceous material, and silica and forming feed agglomerates from the co-ground mixture;
• forming a kiln bed using the feed agglomerates in a counter-current rotary kiln, the bed having a length;
• the agglomerates containing phosphate ore particles, carbonaceous material particles, and sufficient silica particles for the agglomerates to exhibit a calcium-to-silica mole ratio of less than 1.0;
• maintaining a bed temperature at or above 1180° C. along a portion of the bed length without exceeding 1380° C. along the entire bed length and establishing a bed surface-to-volume ratio multiplied by a time for bed heat up to 1180° C. of less than 50 minutes-ft2/ft3;
• and
• generating kiln off gas and collecting phosphorous pentoxide from the kiln off gas.

A phosphorous pentoxide producing method comprising:

• forming a kiln bed using feed agglomerates and, initially, from about 1 to about 2 wt % bedding coke or coal in a counter-current rotary kiln, the bed having a length and having a surface-to-volume ratio of less than about 1.15 ft2/ft3 and the kiln having an inner diameter of at least about 6 feet;
• the agglomerates containing phosphate ore particles, carbonaceous material particles containing from about 8 to about 12 wt % volatiles, and sufficient silica particles for the agglomerates to exhibit a calcium-to-silica mole ratio of from 0.5 to less than 1.0, at least about 80% of all particles exhibiting a size less than 200 mesh;
• individual agglomerates substantially exhibiting a same elemental composition, a same calcium-to-silica mole ratio, and a same proportion of excess fixed carbon at least about 1.3 times a theoretical carbon requirement for reduction of all phosphate in the ore;
• adding over bed air and/or oxygen through a plurality of ports along the bed length, the ports being of sufficient location, number, and throughput to decrease a time for bed heat up to 1180° C. compared to otherwise identical processing without the over bed air and/or oxygen;
• blanketing the bed with volatiles evolving from the bedding coke or coal during bed heat up from about 100 to about 650° C.;
• blanketing the bed with volatiles evolving from the carbonaceous material during bed heat up from about 600 to about 950° C.;
• maintaining a bed temperature at or above 1180° C. along at least 50% of the bed length without exceeding 1310° C. along the entire bed length;
• and
• generating kiln off gas and collecting phosphorous pentoxide from the kiln off gas.