Phosphorus Gasification from Sewage Sludge during Carbothermic Reduction

Abstract

The gasification process of phosphorus from municipal sewage sludge during carbothermic reduction process was investigated using a quadrupole mass spectrometer gas analysis and thermo-gravimetric analysis. Two types of sludge, with high and low Fe 2 O 3 content, were used to evaluate the possible effect of Fe 2 O 3 on the gasification behavior of phosphorus from sewage sludge during incineration processes. The gas species vaporized during the carbothermic reaction were measured by the quadrupole mass spectrometer with comparison to the ion currents for the respective molecular gas species. From the gas analysis, it was observed that PO and PO 2 gas species were dominantly vaporized around 1 073 K. Metallic phase phosphorus gas of P 2 vaporized in the 1 273-1 700 K temperature range. The evolution of another metallic phase phosphorus gas of P 4 was found to be negligibly small. Fe 2 O 3 in the sludge has an important role in the phosphorus emission from the sludge during carbothermic reduction reaction, since metallic phosphorous gases react with the reduced iron and form Fe-P alloy.

Metal/Slag Separation Behavior of CCA with Various Slag Systems and Effect of Slag Composition on the Content of Sulfur and Phosphorus in Iron Nugget

“…P2 can be dissolved into the iron nugget quickly. The formation of Fe3P by gaseous phosphorus producst was well studied by Sasabe et al 22) and Matinde et al 23) In such a case, the phosphate capacity itself cannot explain the behavior of phosphorus since the reaction between slag and metal is not the only route for the partitioning of phosphorus. The partitioning mechanism of phosphorus between slag and metallic Fe produced in the reduction progress of CCA should further be investigated in future work.…”

Dephosphorization Treatment of High Phosphorus Iron Ore by Pre-reduction, Air Jet Milling and Screening Methods

“…1,2) The reduced iron ore phases were characterized according to their behavior under uni-axial mechanical loading. Mechanical crushing of the reduced iron ore resulted in the elongation of the ductile reduced iron particles and the entrapment of the gangue within the elongated reduced iron particles, thereby hindering effective separation by screening methods.…”

“…Mechanical crushing of the reduced iron ore resulted in the elongation of the ductile reduced iron particles and the entrapment of the gangue within the elongated reduced iron particles, thereby hindering effective separation by screening methods. 1,2) Therefore, the application of uni-axial direct mechanical pressure was avoided in the present investigation. The main objective of this work is to investigate the dephosphorization treatment of high phosphorus iron ore pre-reduction, air jet milling and screening methods.…”

Slag/Metal Separation from H₂-Reduced High Phosphorus Oolitic Hematite

“…hematite ore. During the carbon-based reduction, the apatite will be reduced to P 2 or PO vapors to be removed at the temperature of 1 471 K or 1 771 K, respectively. 14) Moreover, sodium salts were added in the reduction process, such as Na 2 CO 3 and Na 2 SO 4 , which were beneficial for enhancing the dephosphorization and the reduction of iron oxide. 15) However, the phosphorus content of the obtained magnetic concentrate was still high, owing to the inevitable migration of phosphorus into the metallic iron by the reduction of apatite during the carbon-based reduction.…”