METHOD FOR REMOVING ELEMENTAL PHOSPHORUS FROM IRON OXIDE-CONTAINING AND PHOSPHATE-CONTAINING SUBSTANCES

Abstract

A method for separating elemental phosphorus from iron oxide-containing and phosphate-containing materials includes at least the following steps: providing at least one iron oxide-containing and phosphate-containing material, adding at least one aluminum carrier to the at least one iron oxide-containing and phosphate-containing material and melting the at least one aluminum carrier together with the at least one iron oxide-containing and phosphate-containing material to form an aluminum-containing and optionally aluminum oxide-containing phosphate slag melt, reacting the aluminum-containing and optionally aluminum oxide-containing phosphate slag melt to elemental, gaseous phosphorus, iron and Al.sub.2O.sub.3-containing slag in a melting vessel, withdrawing the elemental, gaseous phosphorus and tapping off the iron and the Al.sub.2O.sub.3-containing slag.

Claims

1-22. (canceled)

23. A method for separating elemental phosphorus from iron oxide-containing and phosphate-containing material, comprising: providing at least one iron oxide- and phosphate-containing material; adding at least one aluminum carrier to the at least one iron oxide- and phosphate-containing material and melting the at least one aluminum carrier together with the at least one iron oxide- and phosphate-containing material to form an aluminum-containing phosphate slag melt; reacting the aluminum-containing phosphate slag melt to elemental gaseous phosphorus, iron and an Al.sub.2O.sub.3-containing slag in a melting vessel; drawing off elemental, gaseous phosphorus and tapping off the iron and the Al.sub.2O.sub.3-containing slag; wherein a tin bath is arranged as a cathode body in the melting vessel under the aluminum-containing phosphate slag melt and at least one anode body is arranged to be immersed in the aluminum-containing phosphate slag melt and one of: a direct current is applied to the cathode body and the at least one anode body; and a direct current is taken from the cathode body and from the at least one anode body.

24. The method according to claim 23, wherein the at least one iron oxide- and phosphate-containing material is provided as a phosphate slag melt in the melting vessel and the at least one aluminum carrier is added to the phosphate slag melt.

25. The method according to claim 23, wherein a solid material is provided as the iron oxide- and phosphate-containing material and that solid, metallic aluminum is added as the at least one aluminum carrier.

26. The method according to claim 23, wherein an Al.sub.2O.sub.3 carrier is added to the aluminum-containing phosphate slag melt.

27. The method according to claim 23, wherein the basicity, being the weight ratio of CaO/SiO.sub.2, of the aluminum-containing phosphate slag melt is adjusted to a value of 0.65 to 1.4.

28. The method according to claim 23, wherein: the cathode body is arranged in a first region of the melting vessel in a depression arranged in a partial region of a bottom in the melting vessel; the at least one anode body is arranged in a second region of the melting vessel different from the first region; gaseous phosphorus is withdrawn from the first region; and oxygen is withdrawn from the second region.

29. A device for separating elemental phosphorus from iron oxide-containing and phosphate-containing material, comprising: a melting vessel formed by a refractory-lined housing; a phosphate slag melt containing aluminum arranged in the melting vessel; a gas chamber closed off by the refractory-lined housing above the phosphate slag melt, and a feed device for iron oxide- and phosphate-containing substances and at least one extraction device for gaseous, elemental phosphorus; a cathode body arranged below the aluminum-containing phosphate slag melt; and at least one anode body immersed in the aluminum-containing phosphate slag melt; wherein the aluminum-containing phosphate slag melt is formed by adding at least one aluminum carrier to the at least one iron oxide- and phosphate-containing material and melting the at least one aluminum carrier together with the at least one iron oxide- and phosphate-containing material; and wherein the device is further configured to: react the aluminum-containing phosphate slag melt to elemental gaseous phosphorus, iron and an Al.sub.2O.sub.3-containing slag in a melting vessel; draw off elemental, gaseous phosphorus and tapping off the iron and the Al.sub.2O.sub.3-containing slag; and one of: apply a direct current to the cathode body and the at least one anode body; and take a direct current from the cathode body and from the at least one anode body.

30. The device according to claim 29, wherein the feed device comprises a first tube passing through the housing, in which a conveying device for at least one aluminum carrier is arranged.

31. The device according to claim 29, wherein: the feed device comprises a first tube passing through the housing, a second tube being arranged in the first tube and forming an annular gap; one of the first tube and the second tube is configured to feed iron oxide and phosphate-containing substances and the other of the first tube and the second tube is configured to feed aluminum carriers; and the first tube projects beyond the second tube at its end penetrating the housing.

32. The device according to claim 29, wherein: the cathode body is arranged in a first region of the melting vessel in a depression arranged in a bottom of the melting vessel; the at least one anode body is arranged in a second region of the melting vessel laterally spaced from the first region; and a further extraction device is arranged in the second region.

33. The device according to claim 32, wherein between the first region and the second region a separating wall dividing a gas space into two sections separated from each other is immersed in the aluminum-containing phosphate slag melt.

34. The device according to claim 29, wherein the cathode body is formed by a tin bath.

35. The device according to claim 34, wherein the tin bath is received in a carbon-containing body disposed in the depression.

36. The device according to claim 29, wherein the at least one anode body is formed of graphite, platinum or magnetite spinel.

37. The device according to claim 29, wherein the at least one anode body is formed of a high-alloy steel.

38. The device according to claim 29, wherein the at least one anode body is designed to be coolable.

39. The device according to claim 29, further comprising means for applying a direct current to the cathode body and the anode body.

40. The device according to claim 29, further comprising means for taking a direct current from the cathode body and from the anode body.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0045] The invention is explained in more detail below with reference to an example of an embodiment shown in the drawing. Therein,

[0046] FIG. 1 shows a schematic representation of a first device according to the invention,

[0047] FIG. 2 shows a representation of a device according to the invention with a cathode body and several anode bodies,

[0048] FIG. 3 shows a feed device according to a first embodiment of the device according to the invention, preferably for the device according to FIG. 1, and

[0049] FIG. 4 shows an embodiment of the present invention in which a direct current can be taken at the electrodes.

DETAILED DESCRIPTION

[0050] In FIG. 1, the device according to the invention is indicated by the reference numeral 1. The device 1 comprises a housing 3 made of mild steel sheet and fed with a refractory material 2 to form a melting vessel 11. A refractory material suitable for the present invention was found to be magnesium spinel in an Al.sub.2O.sub.3 matrix, which material is known as sintered refractory concrete. Corundum bricks are also suitable as refractory material. Phosphate slag melt 4 is arranged in the housing as the iron oxide-containing and phosphate-containing materials. A feed device 5 of the device 1 passes through the housing 3 with a first tube 6. Aluminum carriers 7 or Al.sub.2O.sub.3 carriers containing metallic aluminum can be fed through the first tube 6 of the feed device 5, which is accomplished by a conveying device 8 in the form of a screw conveyor. The feed device 5 is immersed in the phosphate slag melt 4, whereby the aluminum carriers 7 directly reach the depth of the phosphate slag melt, where they are melted together with the iron oxide- and phosphate-containing materials, namely the phosphate slag melt 4, and rapidly converted to elemental phosphorus and iron. The phosphorus is drawn off via the draw-off device 9 and the iron collects at the bottom 10 of the melting vessel 11. There the iron can be tapped. The phosphate slag melt 4 converts to phosphate-free cement slag without the addition of further starting materials.

[0051] In FIG. 2, the same parts are marked with the same reference numerals. The device 1 according to FIG. 2 has a cathode body 15 arranged under the aluminum-containing phosphate slag melt 4 and a plurality of anode bodies 13 immersed in the aluminum-containing phosphate slag melt 4, the cathode body 15 being formed by a tin bath. In this case, the tin bath is arranged in a depression 14 in the bottom 10 of the melting vessel 11 and is undercoated by the iron formed as the reaction progresses. The tin bath is contained in a graphite body 18 located in the depression. An iron layer forming under the cathode body 15 is designated by the reference numeral 12. The current is then introduced through the graphite body 18, the iron layer 12 and the tin bath 15. The anode bodies 13 may be formed of graphite or high-alloy steels and may be provided with a coating 16.

[0052] The cathode body 15 is disposed in a first region A of the melting vessel 11, the first region A being separated from a second region B laterally spaced from the region A by a separating wall 16a which is immersed in the phosphate slag melt 4. Elemental phosphorus in the form of P.sub.2 is extracted at the extraction device 9, and oxygen (O.sub.2) escapes at a further extraction device 17 associated with the second area B in the case of coated anode bodies. A direct current is applied to the cathode and the anode in a known manner.

[0053] The feed device 5 according to FIG. 3 has a first tube 6 penetrating the housing 3, in which first tube 6 a second tube 19 is arranged concentrically to the first tube 6, forming an annular gap 20. The first tube 6 projects beyond the second tube 19 at its end 6a which passes through the housing 3. Two solid components, namely the iron oxide- and phosphate-containing material 21 and the starting material 21, respectively, and an aluminum carrier 7, in this case metallic aluminum, which are fed together to the device, come into contact with one another, which leads to the formation of an autothermally maintained reaction front 22 at which the aluminum carrier 7 is melted together with the iron oxide- and phosphate-containing material 21. The resulting phosphate slag melt 4 containing aluminum and aluminum oxide is symbolized by droplets and hereupon enters the interior of the melting vessel and the already existing phosphate slag melt, where the complete conversion to iron and elemental phosphorus takes place. In the region of the end 6a of the second tube 6, an ignition device 23 may be provided for the aluminum carrier 7 and the iron oxide- and phosphate-containing substance 21.

[0054] In the embodiment shown in FIG. 4, the anode body 13 is arranged around the first tube 6 of the feed device 5 and means are provided for taking a direct current from the cathode body 15 and the anode body 13.