Patent ID: 8734749

Claim:
A phosphorous pentoxide producing method comprising: forming green feed agglomerates from a homogeneous blend of water, lignin sulfonate, phosphate ore particles, carbonaceous material particles, and silica particles, the green agglomerates containing about 0.1 to 4 wt % lignin sulfonate; forming a reducing kiln bed using the feed agglomerates below an oxidizing freeboard of a counter-current rotary kiln, the bed having a length; the agglomerates containing the phosphate ore particles, the carbonaceous material particles, sufficient silica particles for the agglomerates to exhibit a calcium plus magnesium-to-silica mole ratio of less than 1.0, and the lignin sulfonate both inside the agglomerates and coating a surface of individual agglomerates; maintaining a bed temperature at or above 1180° C. along a portion of the bed length; generating freeboard particulates from the agglomerates, an amount of particulates generated being less than would occur in the method with no lignin sulfonate; and generating kiln off gas and collecting phosphorous pentoxide from the kiln off gas, the kiln discharging a residue containing processed agglomerates, less than 20% of the agglomerates' phosphate input to the kiln remaining in the residue, and the percentage of input phosphate that remains in the residue being less than would occur in the method with no lignin sulfonate.