The behaviour of phosphorus in the smelting reduction process was investigated in this paper. Experiments were carried out under the conditions of smelting reduction: the phosphate reduction in molten slag by solid carbon, liquid iron saturated with carbon and CO gas, respectively. Furthermore, experiments on the phosphate reduction in pre-reduced iron ore by liquid iron saturated with carbon were carried out respectively when liquid iron was in permanent contact with molten pre-reduced iron ore, and when powders of the pre-reduced iron ore were injected into the iron bath from the bottom. The results showed that there was considerable un-reduced P 2 0 5 in the slag. Part of the reduction product of phosphorus escaped from the bath, while the other part was absorbed by liquid iron. The pig iron with low content of phosphorus can be obtained by smelting reduction in comparison with blast furnace. In the process of liquid iron bath with coal-oxygen-ore injection, the phosphorus content in liquid iron could be kept constant in 100 kg scale tests. Untersuchung desPhosphorverhaltens wahrend der Schmelzreduktion. In dieser Arbeit wurde das physikalisch-chemische Verhalten van Phosphor wahrend der Schmelzreduktion untersucht. Die Versuche wurden unter den bei der Schmelzreduktion herrschenden Bedingungen durchgefuhrt, also Phosphatreduktion in der flussigen Schlacke mit festem Kohlenstoff, kohlenstoffgesattigtem Eisen und CO-Gas. Weitere Versuche beschaftigten sich mit der Reduktion des Phosphates in vorreduziertem Eisenerz durch flussiges, kohlenstoffgesattigtes Eisen, das standig mit dem aufgeschmolzenen vorreduzierten Eisenerz in Kontakt war. Dabei wurde auch das Einblasen van vorreduziertem Feineisenerz durch den Boden mitberucksichtigt. Die Ergebnisse zeigen, daB unter den Bedingungen der Schmelzreduktion eine betrachtliche Menge an unreduziertem Phosphat in der Schlacke zuruckbleibt. Zurn Teil entweicht der reduzierte Phosphor aus dem Bad, der Rest wird vom flussigen Eisen absorbiert. Verglichen mit dem Hochofen liefert die Schmelzreduktion ein Roheisen mit niedrigem Phosphorgehalt. Versuche im 100-kg-MaBstab mit Bodeneinblasen van Gemischen aus Kahle, Sauerstoff und Erz zeigen, daB der Phosphorgehalt der Schmelze konstant gehalten werden kann.

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In this paper, a new process for directly making phosphoric acid from phosphorus ore by smelting reduction with postcombustion is presented based on the experience in smelting reduction for iron-making. Theoretically, the new process can save energy when compared with the traditional pyro-process for the manufacture of phosphoric acid. Laboratory simulation shows that it is possible to make phosphoric acid by smelting reduction with postcombustion process. Fundamental research on phosphate reduction in molten slag is carried out. Experimental results show that the reduction rate increases with the increase of temperature, basicity of slag, and stirring intensity of the molten slag. Carbon dissolved in the liquid Fe-P-C alloy has a greater reduction potential than solid carbon. Under the condition of slag basicity (CaO/SiO 2 ) equal to 1•1, and the concentration of Al 2 O 3 at 8•3%, the reduction rate constant by solid carbon can be expressed as k = 1•1 × 10 3 exp(-217 360/RT). The rate constant for reduction by carbon in liquid Fe-P-C alloy is about 10 times larger than that for solid carbon under similar conditions. The reduction by bubbling CO gas is close to the thermodynamic equilibrium assuming that bubbles escape from the slag bath.

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