PROCESS FOR PREPARING A HYDRAULIC BINDER AND DEVICE FOR CARRYING OUT THE PROCESS

Abstract

A process for preparing a hydraulic binder, wherein a slag melt containing P.sub.2O.sub.5 and iron oxide and further containing CaO and SiO.sub.2 are subjected to a cooling step by adding an oxidizing agent for the iron oxide for granulating the slag melt to form amorphous slag glass.

Claims

1-16. (canceled)

17. A method for producing amorphous slag glass, comprising: cooling a slag melt containing P.sub.2O.sub.5 and iron oxide, and also containing CaO and SiO.sub.2, and with the addition of an oxidizing agent for the iron oxide, the cooling configured to granulate the slag melt to form amorphous slag glass; wherein the slag melt has a P.sub.2O.sub.5 content of 7.5 wt. % to 30 wt. %, and in that the slag melt, before the cooling step, is supplemented with elemental aluminum and in that P.sub.2 and CO formed thereby is drawn off from the gas phase.

18. The method according to claim 17, wherein the slag melt has a P.sub.2O.sub.5 content of 12.5 wt. % to 20 wt. %.

19. The method according to claim 18, wherein the slag melt has a P.sub.2O.sub.5 content of 17 wt. % to 19 wt. %.

20. The method according to claim 17, wherein the basicity (CaO wt. %/SiO.sub.2 wt. %) of the slag melt is set to a value of 0.85 to 1.3 before the cooling step by adding a lime carrier or an aluminum carrier.

21. The method according to claim 17, wherein calcium carbide is added to the slag melt before the cooling step, and that P.sub.2 and CO formed thereby is drawn off from the gas phase.

22. The method according to claim 17, wherein the slag melt is subjected to an electrochemical reduction of P.sub.2O.sub.5 before the cooling step and that the P.sub.2 formed thereby is drawn off as cathode gas.

23. The method according to claim 22, wherein the slag melt is subjected to the electrochemical reduction of P.sub.2O.sub.5 at an electrode voltage of 16 V to 24 V.

24. The method according to claim 17, wherein the cooling step consists in dispersing the slag melt in a water bath.

25. The method according to claim 24, wherein the water bath for the slag melt being at a temperature between 80 C. and the boiling point.

26. The method according to claim 23, wherein vapors from the water bath arising during the cooling step are collected, condensed, and fed back to the water bath.

27. The method according to claim 26, wherein, the condensation being carried out in a form of an adiabatic compression for a recovery of waste heat from the vapors.

28. The method according to claim 21, wherein vapors from the water bath produced during the cooling step are collected, condensed, and fed back to the water bath, the vapors being brought to a temperature between 180 C. and 220 C. by compression and the heat of the vapors is used to dry mechanically dewatered sewage sludge.

29. The method according to claim 17, wherein an oxygen carrier is used as the oxidizing agent.

30. The method according to claim 29, wherein the oxygen carrier is at least one of air, O.sub.2, CO.sub.2, water and steam.

31. The method according to claim 17, wherein the granulated slag glass is ground.

32. The method according to claim 31, wherein iron components are magnetically separated from the ground slag glass.

33. A device for producing amorphous slag glass, comprising: a granulation chamber with a basin and a water bath accommodated therein; a feed device for the slag melt in the form of an immersion tube reaching into the basin and comprising a rotatably drivable rotor in the basin below the immersion tube to rotate the water bath to form a vortex; wherein the feed device comprises a melt container for the slag melt, which in its base has an opening arranged concentrically to the immersion tube and configured to be closed by a plunger displaceable in an axial direction relative to the immersion tube; wherein the slag melt containing P.sub.2O.sub.5 and iron oxide, and also containing CaO and SiO.sub.2, and with the addition of an oxidizing agent for the iron oxide is cooled, the cooling configured to granulate the slag melt to form amorphous slag glass; and wherein the slag melt has a P.sub.2O.sub.5 content of 7.5 wt. % to 30 wt. %, and in that the slag melt, before the cooling, is supplemented with elemental aluminum and in that P.sub.2 and CO formed thereby is drawn off from the gas phase.

34. The device according to claim 33, wherein a supply line for a gaseous oxidizing agent is guided axially through the plunger.

35. The device according to claim 33, wherein the granulation chamber has a discharge area for granulated slag glass downstream of a weir for withdrawing vapors into a vapor outlet being arranged in the discharge area.

36. The device according to claim 33, wherein the vapor outlet forms a siphon which communicates with the basin.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The invention is explained in more detail below with reference to an exemplary embodiment schematically illustrated in the drawing.

[0033] FIG. 1 shows a lateral sectional view of the device according to the invention and

[0034] FIG. 2 shows a vertical section transverse to the axial direction at the level of the weir and thus at the level of the discharge area from the granulation chamber.

DETAILED DESCRIPTION

[0035] In FIG. 1, the device according to the invention for carrying out the method according to the invention is designated by the reference numeral 1. The device 1 comprises a granulation chamber 2, which forms a basin 3 for receiving a water bath 4. The granulation chamber 2 is closed at an upper end by a cover 5 so that vapors formed during the granulation of the slag melt cannot escape in an uncontrolled manner. A feed device for the slag melt 6 is designated by the reference numeral 7. The feed device 7 consists essentially of an immersion tube 8 extending into the basin 3, a melt container 9 for the melt 6, and a plunger 11 that is displaceable in the axial direction 10 and can close or open an opening 12 arranged in the base 9a of the melt container 9. A supply line 27 for the oxidizing agent is guided axially through the plunger 11. When the opening 12 is opened by the plunger 11, a hollow cylindrical film 13 of the slag melt 6 enters the immersion tube 8 and subsequently strikes the surface of a vortex 15 formed in the water bath 4 by the action of the rotor 14, where it is immediately dispersed and comminuted. In this way, an extremely rapid cooling of the slag melt to form amorphous slag glass takes place in the water bath 4, and the solidified slag glass floats on the surface of the vortex 15. With a corresponding adjustment of the rotational speed of the rotor 14, the slag glass formed reaches the height of the weir 16 and is discharged via the weir 16. During discharge, the slag glass runs over a dewatering device in the form of a sieve surface 17, where vapors can be drawn off directly from the slag glass, the vapors being drawn off from the vapor outlet 19 by the action of a suction fan 18. Any vapors condensing in the vapor outlet 19 are again fed to the water bath through a siphon 20 formed by the vapor outlet 19 and interacting with the water bath 4. The vapor can then be supplied to a compressor 21, in which an adiabatic compression of the vapor takes place, so that condensate can be formed and returned to the water bath 4 via a line 22. Thermocompression also produces waste heat in quantities of approximately 460 kWh/t of initial slag melt. Furthermore, non-condensable gases can be drawn off downstream of the compressor 21. Water can additionally be supplied via a line 23 to compensate for losses in the water bath.

[0036] In FIG. 2, the same parts are provided with the same reference numerals, and it can be seen that the granulation chamber 2 has a substantially rotationally symmetrical cross section, which is suitable for forming a vortex by the action of the rotor 14. The amorphous slag glass enters the discharge area 24, which discharges tangentially from the water basin, wherein the weir 15 shown in section in FIG. 1 is arranged in the region marked with the reference numeral A in FIG. 2. In the region of the basin 3, a guide element 26, adjustable in the direction of the double arrow 25, can be arranged downstream of the discharge into the discharge area 24 in the direction of rotation of the vortex 15, indicated by the circularly drawn arrows in FIG. 2, by means of which the slag glass floating on the vortex can be dammed up towards weir 16. For this purpose, the guide element 26 may also be designed in the form of a rake in order not to excessively impede the formation of the vortex 15. A dewatering device in the form of a sieve surface is again provided with the reference numeral 17. As already mentioned, however, the dewatering device can also be designed as a hydrocyclone or as a pusher centrifuge.