PROCESS AND FACILITY FOR THERMAL TREATMENT OF A SULFUR-CONTAINING ORE

Abstract

A process for thermal treatment of a sulfur-containing ore in which the ore is calcined at temperatures of between 600 and 1200? C. in the presence of oxygen in a reactor so that between 1 and 90% by weight of sulfur contained in the ore is burned to sulfur dioxide and impurities contained are driven off in gaseous form. The exhaust gas being produced and containing the sulfur dioxide is fed into a gas purification comprising at least one component and/or the calcined ore is fed into at least one further process stage. An exhaust gas from the gas purification and/or the process stage and/or a gas used for cooling within the gas purification or for cooling within a further process stage is at least partially returned back into the reactor as recycling gas having a temperature of >100? C.

Claims

1.-17. (canceled)

18. A method for thermal treatment of a sulfur-containing ore comprising: calcining the ore at temperatures of between 600 and 1200? C. in the presence of oxygen in a reactor so that between 1 and 90% by weight of the sulfur contained in the ore is burned to sulfur dioxide and impurities contained are driven off in gaseous form; feeding exhaust gas produced containing the sulfur dioxide into a gas purification comprising at least one component wherein an exhaust gas from the gas purification is at least partially returned back into the reactor as recycling gas having a temperature of >100? C.; and operating the reactor in an autothermic manner.

19. The method according to claim 18, wherein the calcined ore is fed into at least one further process stage, and that an exhaust gas from the process stage and/or a gas used for cooling within the further process stage is at least partially returned back into the reactor as recycling gas having a temperature of >100? C.

20. The method according to claim 18, wherein the driven off impurities including arsenic and/or antimony are contained in amounts of between 1 and 10% by weight, based on their content in the sulfur-containing ore used, and/or that the ore contains at least 70% by weight of copper, cobalt, gold and/or nickel.

21. The method according to claim 18, wherein the oxygen content of the recycling gas is used as command or control variable for controlling or regulating the temperature in the reactor.

22. The method according to claim 18, wherein the recycling gas is used as fluidization gas in the reactor being designed as a fluid bed reactor or as combustion air in the reactor being designed as a rotary kiln.

23. The method according claim 18, wherein the recycling gas has a temperature of between 100 and 600? C.

24. The method according to claim 18, wherein the recycling gas has a proportion of oxygen of between 3 and 20% by weight.

25. The method according to claim 18, wherein the recycling gas is a mixture of several exhaust gases and/or gases which are used for cooling.

26. The method according to claim 18, wherein the ore after the reactor is fed into a melt and exhaust gas from this melt and/or a gas from a cooling downstream of it is returned back into the reactor as recycling gas or constituent of the recycling gas.

27. The method according to claim 18, wherein the gas purification comprises a process for producing sulfuric acid from the sulfur dioxide contained in the exhaust gas and from this process gas is returned back into the reactor as recycling gas or constituent of the recycling gas.

28. The method according to claim 27, wherein the SO.sub.2 with addition of air is reacted to SO.sub.3 and a gas which is poor in oxygen and that the gas which is poor in oxygen is returned back into the reactor as recycling gas or constituent of the recycling gas.

29. The method according to claim 28, wherein the SO.sub.3 is absorbed with sulfuric acid in at least two stages, that the sulfuric acid between two series-connected stages is guided through at least one heat exchanger, that in this heat exchanger air is used as heat transport medium and that this air is returned back into the reactor as recycling gas or constituent of the recycling gas.

30. The method according to claim 29, wherein the gas which is poor in oxygen from the reaction of SO.sub.2 to SO.sub.3 and heated air from the at least one heat exchanging between both absorption stages are mixed such that a specific oxygen content of between 3 and 20% by weight is adjusted with which the temperature in the reactor is controlled or regulated.

31. A facility for thermal treatment of a sulfur-containing ore, comprising a reactor for operating a process according to claim 18, wherein the ore is calcined at temperatures of between 600 and 1200? C. in the presence of oxygen, so that from sulfur contained in the ore SO.sub.2 is formed, further comprising a gas purification comprising at least one component and/or at least one further process stage treating the ore, wherein a return line for an exhaust gas from the gas purification into the reactor is provided and that the reactor is an autothermal reactor.

32. The facility according to claim 31, wherein at least one further process stage is treating the ore and that a return line for an exhaust gas from the further process stage into the reactor and/or a return line for gas which is used in a cooling within a further process stage into the reactor is provided.

33. The facility according to claim 31, wherein the reactor is designed as a fluidized bed reactor.

34. The facility according to claim 31, wherein the reactor features coils for a gaseous or liquid cooling medium.

Description

[0032] In the following, the invention is explained in more detail by means of a FIGURE. Here, all described and/or depicted features form on its own or in arbitrary combination the subject matter of the invention, independently from their summary in the patent claims or their back reference.

[0033] FIG. 1 shows a procedure according to the present invention in a schematic manner.

[0034] In FIG. 1 via line 1 an ore is introduced into the reactor 10 which has the following composition:

TABLE-US-00002 TABLE 2 composition of the introduced ore. Element % by weight Cu 28.1 Fe 12.9 S 24.5 As 3.3 Sb 0.1 Pb <0.1 Zn 0.6 Ag <0.1

[0035] But similarly the described process is also possible for each ore composition mentioned in table 1.

[0036] In reactor 1 the ore is thermally treated in a so-called calcining process at temperatures of between 550 and 1000? C., preferably 680 and 720? C. under autothermal conditions. Here, on the one hand, sulfur contained in the ore is burned so that SO.sub.2 and heat are formed. On the other hand, at the prevailing reaction temperatures impurities, in particularly arsenic and/or antimony, are evaporated which is an energy consuming process. Exhaust gases consisting of the introduced air, the produced SO.sub.2 and gaseous impurities are subsequently drawn off via line 11 and are fed into a cyclone 20.

[0037] In this cyclone 20 the particles entrained by the exhaust gas flow are separated from the gas flow. The so purified gas from which dusts and small particles (<20 ?m) have been removed is then fed into a gas purification 22.

[0038] The gas purification 22, preferably, comprises a hot filtration and/or a quench, preferably with water, and/or a wet filtration and/or a mercury removal and/or a gas drying, particularly preferably in this arrangement. Exhaust gases which are produced so and/or a gas which is used for cooling of one of the mentioned gas components or between the mentioned gas purification components can then be returned back into the reactor 10 via lines 23, 41 and 40 as recycling gas, wherein this recycling gas has a temperature of higher than 100? C., preferably 300 to 450? C.

[0039] Furthermore, the gas from the gas purification facility 22 or also directly from line 21 is fed into a sulfur trioxide reactor 30 via line 23 for reacting SO.sub.2 to SO.sub.3 in a heterogeneously catalyzed reaction. The oxygen required for this reaction is introduced via line 31. Similarly, also an introduction into lines 22 or 23 would be imaginable. The exhaust gas which is produced and which is oxygen-depleted, since oxygen from air has been used for the reaction of SO.sub.2 to SO.sub.3, is fed as recycling gas into reactor 10 via line 42 and line 40.

[0040] Via line 32 the produced SO.sub.3 is fed into at least one absorption stage 33. Into this absorption stage 33 via line 34 sulfuric acid is introduced and via line 35 drawn off again. In the sulfuric acid SO.sub.3 and H.sub.2SO.sub.4 form disulfuric acid H.sub.2S.sub.2O.sub.7 which in contact with water decomposes into two molecules of sulfuric acid. This product is drawn off via line 35.

[0041] Preferably, as shown, the absorption is characterized by a design of at least two stages so that line 35 does not immediately withdraw the end product, but does it fed into a second absorption stage 36 from which then the end product is drawn off via line 37. In line 35 a heat exchanger 39 is located which also uses a gas, preferably air, as a heat carrier medium. So the air fed via line 38 into the heat exchanger 39 can be heated and it can be fed into recycling line 40 via line 44, 43. Similarly, also the use of a process gas which is poor in oxygen instead of air would be imaginable.

[0042] Preferably, gas which is poor in oxygen, thus gas with an oxygen content of between 5 and 20% by weight, preferably 8 to 14% by weight is drawn off from the sulfur trioxide reactor 30 via line 42. This step of drawing off can also be realized via a chimney (not shown), thus after passing both absorption stages. By mixing the gases in lines 42 and 44 the oxygen content in lines 43, 40, optionally also by further admixing via line 41, can be controlled or regulated. A definition of the oxygen content also results in the stoichiometrically possible conversion of sulfur in reactor 10, whereby in this manner also the amount of heat generated by the burning of sulfur and thus finally the temperature in reactor 10 can be controlled.

[0043] The ore is drawn off from reactor 10 via line 12. Preferably, into it the particles and fine dusts separated in cyclone 20 are fed by means of line 24. Then, the ore can be used elsewhere or it can be directly further processed in a cluster of production plants.

[0044] In an alternative or in addition to the described recycling gas guidance from the gas purification, when the further processing is conducted on-site, it is possible to recover recycling gas also in a downstream ore processing stage. Preferably, in this case, the ore is fed into a melting furnace 50 via line 51 in which the ore is further purified. Exhaust gases which are produced here and originate either directly from the melting furnace 50 or also from a cooling downstream of the melting furnace 50 (not shown) can be fed into reactor 10 via a recycling gas line 60.

[0045] Similarly, also other stages for further processing the ore are imaginable from which either directly gas and/or cooling gas used in a corresponding cooling can be used as recycling gas or as constituent of the recycling gas. In the shown process, at the same time, the melting furnace is cooled and via the same recycling gas line in its function as a heat carrier medium also heated gas is returned back into reactor 10.

[0046] Furthermore, generally, it is also imaginable to mix the recycling gas from recycling gas line 60 independently from its origin with the recycling gas from line 40.

[0047] Preferably, reactor 10 is designed as a fluidized bed reactor so that the recycling gas is used completely or partially as fluidization gas. In this case, both, a stationary fluidized bed and also a circulating fluid bed are possible.

LIST OF REFERENCE SIGNS

[0048] 1 line [0049] 10 reactor [0050] 11, 12 line [0051] 20 cyclone [0052] 21 line [0053] 22 gas purification stage [0054] 23 line [0055] 30 sulfur trioxide reactor [0056] 31, 32 line [0057] 33 absorption stage [0058] 34, 35 line [0059] 36 absorption stage [0060] 37, 38 line [0061] 39 heat exchanger [0062] 40-44 line [0063] 50 melting furnace [0064] 51 line [0065] 60 line