Patent GB-981781-A (GB)
Title: Process for reducing metal of phosphorus oxides
IPC: C21B13/04
Filed: 1961-04-13
Abstract: <PICT:0981781/C1/1> Phosphorus is obtained from its oxides using a gaseous reducing agent by a process consisting of at least three stages.  In the first stage, a heated reducing gas is mixed with a heated oxygen-containing gas to cause partial combustion of the former, and the resulting mixture is contacted with a charge of oxide which is thereby partially reduced.  The charge is then subjected to a heated gaseous mixture formed from an oxygen-containing gas and a reducing gas richer in reducing components than that employed in the first stage, at a temperature higher than that in the initial reduction whereby further oxide is reduced, and then in the third stage the charge is contacted with a stream of reducing gas, as a result of which further oxygen is eliminated from the charge.  In a particular embodiment, iron oxide is reduced in an apparatus having four reactors which operate cyclically at any time, one being out of circuit for recharging while the other three undergo in turn the three stages of the process.  The reducing gas, which may be natural gas, passes first to the cooling, or final reduction, stage, and then consecutively to the secondary and primary reduction stages.  As illustrated, natural gas entering through conduit 10 is mixed with steam and catalytically transformed in furnace 14 into a mixture of carbon monoxide and hydrogen, which possibly after the addition of natural gas through conduit 50 passes to reactor 52 in the cooling position, where it contacts a charge of oxide which has undergone two reducing operations.  The gases then pass to reactor 54 in the primary position, where they are first partially combusted with preheated air, and are then brought into contact with a charge which has previously undergone one reduction.  Upon leaving reactor 54 the gases pass to reactor 56 in the secondary position, where they are again partially combusted and then used to partially reduce a fresh charge of ore.  The process operates on a twelve-hour cycle, each reactor in turn being disconnected from the circuit for discharging and recharging, and then by suitable operation of the valves and connections being placed successively in the secondary, primary and cooling states.  In the cooling stage, contact of the fresh gases with hot ore causes some cracking of the former, with deposition of carbon which is beneficial in a subsequent melting operation.ALSO:<PICT:0981781/C6-C7/1> Metals are obtained from their oxides using a gaseous reducing agent by a process consisting of at least three stages.  In the first stage, a heated reducing gas is mixed with a heated oxygen-containing gas to cause partial combustion of the former, and the resulting mixture is contacted with a charge of oxide which is thereby partially reduced.  The charge is then subjected to a heated gaseous mixture formed from a oxygen-containing gas and a reducing gas richer in reducing components than that employed in the first stage, at a temperature higher than that in the initial reduction whereby further oxide is reduced, and then in the third stage the charge is contacted with a stream of reducing gas, as a result of which further oxygen is eliminated from the charge.  In a particular embodiment, iron oxide is reduced in an apparatus having four reactors which operate cyclically, at any time one being out of circuit for recharging while the other three undergo in turn the three stages of the process.  The reducing gas, which may be natural gas, passes first to the cooling, or final reduction, stage, and then consecutively to the secondary and primary reduction stages.  As illustrated, natural gas entering through conduit 10 is mixed with steam and catalytically transformed in furnace 14 into a mixture of carbon monoxide and hydrogen, which possibly after the addition of natural gas through conduit 50 passes to reactor 52 in the cooling position, where it contacts a charge of oxide which has undergone two reducing operations. The gases then pass to reactor 54 in the primary position, where they are first partially combusted with preheated air, and are then brought into contact with a charge which has previously undergone one reduction.  Upon leaving reactor 54 the gases then pass to reactor 56 in the secondary position, where they are again partially combusted and then used to partially reduce a fresh charge of ore.  The process operates on a twelve-hour cycle, each reactor in turn being disconnected from the circuit for discharging and recharging, and then by suitable operation of the valves and connections being placed successively in the secondary, primary and cooling stages. In the cooling stage, contact of the fresh gases with hot ore causes some cracking of the former, with deposition of carbon which is beneficial in a subsequent melting operation.