EP0193976B1 - Apparatus for the pyrometallurgical treatment of fine-granular solid materials to obtain fused products - Google Patents

Description

The invention relates to a device for the pyrometallurgical treatment of fine-grained solids resulting in products which are molten at treatment temperatures.

DE-PS-2 253 074 (= US-PS-3 915 692) discloses a process for the pyrometallurgical treatment of fine-grained solids which result in products which are molten at treatment temperatures, in which the solids suspended in oxygen-rich gases run at a high rate and prevent reignition be reacted in a vertical burning path. The suspension formed, which contains predominantly molten particles, is introduced into a horizontally arranged cyclone chamber. In the previously known arrangement, hot gas with melting drops from the vertical cylindrical firing section enters tangentially at one end of the lying cylindrical cyclone chamber and centrally at the opposite end through a collar into a downstream secondary chamber. The separated melt flows to the secondary chamber at the outlet end of the gas flow through a high, narrow slot, which is embedded below the collar in the vertical central plane of the end face.

The melting cyclone chamber used in a similar process known from DE-AS-2 010 872 (= CA-PS-926 631) has an approximately horizontal axis which is inclined downward by a maximum of approximately 30 ° with respect to the horizontal. Solid and preheated gas are blown into the cylindrical cyclone chamber from above along a secant without their own burning path. The entry is made over almost the entire length of the cyclone. The gas flows to a secondary chamber through a collar inserted centrally in the end face. The melt flows under the collar through a hole in the deepest part of the end wall also into the secondary chamber.

The cyclone chambers used in the previously known processes lead in many cases, depending on the type of solids to be treated, to malfunctions in the operating sequence. At higher throughputs, there is a strong build-up in the gas outlet openings, since the melt separation within the cyclone chamber is no longer sufficient.

The object of the invention is to provide a device, in particular a cyclone chamber, for pyrometallurgical treatment of fine-grained solids, which avoids the disadvantages of known devices and in particular the aforementioned disadvantages.

The invention solves the problem with a device for the pyrometallurgical treatment of fine-grained solids suspended in oxygen-rich gases, with a horizontally arranged cylindrical vessel and the associated burner shaft opening vertically into the vessel, as well as with a gas discharge opening and discharge opening for melts. A device of the type mentioned is designed according to the invention in such a way that the tangential opening of the combustion shaft extends the circular cross section of the cylindrical vessel in the form of a partial spiral and opens into a discharge slot, the discharge slot being open at the bottom and the outer jacket of the essentially cylindrical vessel breaks through substantially parallel to its longitudinal axis.

With the device according to the invention, a practically complete separation of the pyrometallurgically treated particles from the gas phase (gas stream) is achieved, in particular when the gas stream is heavily loaded with e.g. B. J.1 "" 7 kg of melt particles per kg of gas.

The measures of the invention are based on the knowledge that with a high solids load (melt particles) of the gas stream emerging from the combustion shaft, the melt particles are almost completely flung and in the first curve of the inlet bend against the container wall, where a closed and rapidly flowing film on the immediately steep cylinder wall.

The film's high flow rate drops to a fraction when the gradient in the lower area of the cyclone wall becomes smaller. That is, in such an undesirable case, the melt film is accumulated in waves in conventional cyclones, while a part of the gas flow on the waves or on the surge is deflected in the direct direction of the gas outlet as at a baffle. The part of the flow which is deflected upward by the surge then disadvantageously tears large drops from the liquid wave which, due to the dynamic pressure of the escaping gas flow, pulsates and bubbles considerably. The torn drops fly slowly and almost vertically upwards into the very restlessly rotating and oscillating vortex core of the cyclone flow, where they increasingly wobble axially towards the gas outlet. Faster and circling drops are just about to be separated, a part bakes in the gas outlet on the inner wall and a part is carried along with the flow through the gas outlet (Fig. 1 and 2).

With the inventive arrangement is now advantageously achieved that in the tangential inlet spiral (14) practically in the first spiral section or arc, the molten particles from the gas stream and on the spiral wall as a film (4) and almost completely in the discharge slot or slot-like discharge channel (16) are transferred. The melt runs as a jet through the discharge slot into a melt collecting container (19) (FIG. 3). From the collecting tank, the melt can possibly reach a forehearth, where the melt mixture is separated into the components if necessary. A small part of the gas flow can - if arranged accordingly - e.g. B. exhaust gas opening (20) in the melting tank (19) - escape through the discharge slot (16) over the melting tank.

The walls of the cyclone chamber are designed in a manner known per se as steam-cooled, pinned tube walls (17) lined with refractory material, whereby they are solidified by a thin layer Melting products secure wall protection is achieved.

In the lower area of the cyclone chamber, the wall surface (15) of the inlet spiral (14) runs flat, runs tangentially and forms the lower surface of the discharge slot (16). This flat surface has a downward slope of approximately 20 to 45 ° to the horizontal. The other (upper) surface delimiting the discharge slot starts at a point on the wall which lies on the continuation of the original wall spiral, which is interrupted by the discharge slot.

The discharge slot is generally equipped with parallel walls. However, at least one wall expediently diverges in the direction of the melt collecting container.

The burner shaft has a generally circular cross section. In the device according to the invention, the cross section of the tangential opening of the combustion shaft into the cyclone chamber is expediently elliptical. In many cases, a rectangular cross section is advantageous. From the inlet cross-section, the inlet spiral expands steadily and reaches approximately the length of the discharge slot. The length of the discharge slot (in the direction of the cyclone axis) is approximately up to 3 times the width of the inlet of the spiral.

According to an advantageous embodiment of the device according to the invention, a groove is located in the lining of the cyclone jacket at the lowest point and starting in the area of the gas outlet opening. This channel (Fig. 3a; 18) runs with increasing depth to the discharge slot and is a kind of return for the melt film, which comes from the remaining melt particles still separated from the main gas stream. The return channel begins with increasing depth at a distance of approximately 1/3 to 2/3 of the diameter value of the gas outlet opening and ends at the discharge slot. The channel end has a width "B" of approximately 1/4 to 1/2 the diameter of the gas outlet opening. The depth "T" of the return channel corresponds approximately to the width "B". With this arrangement, a reliable separation of the last portions of molten particles from the gas stream and a complete return of the separated melt components through the channel into the discharge slot is ensured.

According to a particularly advantageous embodiment of the device according to the invention, part of the cylindrical cyclone arranged horizontally is angled upwards; that is, a cylindrical section of the cyclone can be angled upwards as a whole, or only the lower half of the jacket can be angled upwards, so that a cyclone section is in the form of an asymmetrical cone. The angling (a) of the longitudinal axis upwards is approximately 15 to 30 °, and the length of the angled cyclone section corresponds approximately to the length of the return channel installed in the lower cyclone jacket. Finally, the entire cyclone jacket in the region of the angled longitudinal axis can be designed conically towards the gas outlet.

A large number of solids can be treated pyrometallurgically in the device according to the invention. Non-ferrous metal ore concentrates and sulfidic ores are particularly suitable. However, the device according to the invention is also suitable for the treatment of oxidic, optionally pre-reduced iron ores or iron ore concentrates and also for the treatment of metallurgical intermediates.

The advantage of the device according to the invention can be seen in the fact that a large number of solids can be used at a high gas loading density and can be treated pyrometallurgically and that the melting particles in the cyclone can be separated practically completely and above 95%. At high throughput, the device according to the invention has practically no susceptibility to failure.

The invention is explained in more detail with reference to the drawings and the examples.

• Fig. 1 einen Schnitt durch eine liegende Zyklonkammer herkömmlicher Bauart.
• Fig. 2 einen Längsschnitt durch die Zyklonkammer der Fig. 1 entlang der Schnittlinie A - A' - A".
• Fig. 3 einen Schnitt durch eine Zyklonkammer gemäß Erfindung mit nachgeschaltetem Schmelzenbehälter.
• Fig. 3a einen Schnitt gemäß Fig. 3, jedoch mit Rücklaufrinne und Öffnungen zur Sekundärkammer.
• Fig. 4 einen Längsschnitt durch die Zyklonkammer der Fig. 3 bzw. 3a entlang der Schnittlinie B - C - D.
• Fig. 4a einen Schnitt gemäß Fig. 4, jedoch mit Rücklaufrinne.
• Fig. 5 einen Schnitt durch eine Zyklonkammer mit abgewinkelter Längsachse, in Richtung Gasaustritt gesehen.
• Fig. 6 einen Längsschnitt durch die Zyklonkammer der Fig. 5 entlang der Schnittlinie E - F - G - H.
• Fig. 7 einen Längsschnitt durch die Zyklonkammer der Fig. 5 entlang der Schnittlinie I - K.
• Fig. 8 einen Schnitt durch einen Brennschacht mit Einmündung in den Zyklon gemäß Erfindung.

It illustrates:

• Fig. 1 shows a section through a horizontal cyclone chamber of conventional design.
• Fig. 2 shows a longitudinal section through the cyclone chamber of Fig. 1 along the section line A - A '- A ".
• Fig. 3 shows a section through a cyclone chamber according to the invention with a downstream melt container.
• 3a shows a section according to FIG. 3, but with a return channel and openings to the secondary chamber.
• 4 shows a longitudinal section through the cyclone chamber of FIGS. 3 and 3a along the section line B - C - D.
• 4a shows a section according to FIG. 4, but with a return gutter.
• Fig. 5 seen a section through a cyclone chamber with an angled longitudinal axis, in the direction of the gas outlet.
• 6 shows a longitudinal section through the cyclone chamber of FIG. 5 along the section line E - F - G - H.
• 7 shows a longitudinal section through the cyclone chamber of FIG. 5 along the section line I - K.
• Fig. 8 shows a section through a combustion shaft with a confluence with the cyclone according to the invention.

• 1 and 2 of a cyclone of conventional design show in detail: the combustion shaft 1 with inlet cross-section 2, separation of the droplets 3 that are carried in the hot gas, wall film 4, melt surge 5, large drops 6 torn out of the surge, axially displaced partial flow 7, radially deflected main flow 8, gas outlet or collar 9, wall extension 10, secondary chamber 11, boiler tube wall 12 and central melt outlet 13.
• 3 and 3a mean:
  • 1 burner shaft, 2 inlet cross-section, 9 gas outlet, 14 semi-spiral, 4 fast melt film on the wall, 15 the inclined plane leading to the discharge slot 16, 17 boiler tube wall of the cyclone, 18 the return channel, 19 the melt collection container with openings 20 and subsequent channels to the secondary chamber.
• 4 and 4a show:
  • 22 the contour of the spiral channel, which is continuously changed in its width, in the top view, 18 the return channel, also in the top view, 2 the inlet cross section of the combustion shaft, 9 the gas outlet, 17 the boiler tube wall of the cyclone.
• 5 mean:
  • 6 discharge slot, 15 the flat wall part leading to the discharge slot 6, 21 the gas outlet opening at the end of the asymmetrically conically narrowed cyclone chamber, 19 melting tanks with openings 20 for gas outlet, 18 return channel.
• 6 mean:
  • 21 the gas outlet opening at the end of the conical cyclone housing and 22 the contours of the spiral channel widened on both sides, running from the mouth 2 of the combustion shaft, 17 boiler tube wall, 18 return channel.
• 7 mean:
  • 22 the angled () cyclone axis, 23 the asymmetrically tapered part of the cyclone chamber, 20 gas outlet of the melt container, 21 gas outlet for the main gas flow, 18 return channel.
• 8 shows a section through a combustion shaft 1 with an inlet cross section 2 and burners. The
  • Burning shaft opens into the cyclone according to the invention. With 16 the discharge slot is designated, from which the melt 4 emerges on the wall of the semi-spiral 14. 17 denotes the boiler tube wall of the cyclone and 9 the gas outlet.
• In the example below, the device according to the invention is explained in more detail and by way of example on the basis of the processing of fine-grained solids resulting in molten products at pyrometallurgical treatment temperature.

example

• Cu = 21 - 23 %
• Fe = 22-25%
• S - 30-33%
• Zn = 9-11%
• Pb = 6-8%
• Si0₂ = 1%

einer Korngröße zwischen 0,5 und 100 µm und einem Anteil von 53 % im Bereich zwischen 15 und 100 µm besitzt eine Restfeuchte von 0,1 bis 0,3 %. Als Schlackenbildner wird Si0₂ in Form von Sand in einer Menge von 1,3 t/h dem Konzentrat-Luftstrom vor Eintritt in den Brenner zugeführt, um das sich bildende Eisenoxid in einer Schlacke abzubinden. Hierzu wird Sand mit einer Restfeuchte von 0,1 % und einer Korngröße bis 0,7 mm verwendet. Der Primär-Fluidstrom, bestehend aus 7.000 kg/h Konzentrat, 1.300 kg/h Sand und 380 m³/h Förderluft, wird mit Sekundärstromgemisch aus 600 m³/h Luft und 1.800 m³/h Sauerstoff zusammengeführt. Der homogenisierte und wirbelfreie Fluidstrahl wird nach dem Eintritt in die vertikale Brennerstrecke gezündet (deutsche Patentanmeldung P-3 436 624, (EP-A-0 177 090).7,000 kg / h of a complex copper concentrate according to the analysis below are fed to the burner (FIG. 8) from upstream bunker, drying, distributor and mixing systems with 390 m ³ primary air as carrier gas via a delivery pipeline. The concentrate with a composition of

• Cu = 21-23%
• Fe = 22-25%
• S - 30-33%
• Zn = 9-11%
• Pb = 6-8%
• Si0 ₂ = 1%

a grain size between 0.5 and 100 µm and a share of 53% in the range between 15 and 100 µm has a residual moisture content of 0.1 to 0.3%. As a slag former, Si0 ₂ is supplied in the form of sand in an amount of 1.3 t / h to the concentrate air stream before entering the burner in order to bind the iron oxide that forms in a slag. For this, sand with a residual moisture of 0.1% and a grain size of up to 0.7 mm is used. The primary fluid flow, consisting of 7,000 kg / h concentrate, 1,300 kg / h sand and 380 m ³ / h conveying air, is combined with a secondary flow mixture of 600 m ³ / h air and 1,800 m ³ / h oxygen. The homogenized and vortex-free fluid jet is ignited after entering the vertical burner section (German patent application P-3 436 624, (EP-A-0 177 090).

As the reaction progresses, the temperature rises rapidly and reaches the maximum temperature of approximately 1,640 ° C. at the end of the cylindrical part of the burner section (1) (FIG. 8). The gas stream loaded with melt particles is introduced into the cyclone through the tangential inlet spiral (14) (FIG. 3). The molten particles are practically separated from the gas flow on the spiral wall (4) in the first spiral section and almost completely transferred into the discharge slot (16). The melt runs as a jet through the discharge slot (16) into a melt collecting container (19). The walls of the cyclone chamber are designed in a manner known per se as steam-cooled, pinned and lined with refractory tube walls, a reliable wall protection being achieved by a thin layer of solidified melting products.

In the present example, the process is autogenous. In the case of processing mixtures which provide less heat of reaction, fuel is additionally supplied in gaseous, liquid or solid form.

The heat of reaction dissipated via the cooled walls of the reactor system results in a steam production of approx. 1 t steam (60 bar) per t concentrate.

• Kupferstein der Zusammensetzung
• Cu = 74
• Pb = 2,2
• Fe = 1,8
• S = 21,7
• Zn = 0,6

The products discharged from the cyclone are:

• Copper stone of the composition
• Cu = 74
• Pb = 2.2
• Fe = 1.8
• S = 21.7
• Zn = 0.6

• Cu = 1,8
• Pb = 1,8
• Zn = 9,3
• Fe = 35,8
• Si0₂ = 28,8

Slag with a content of

• Cu = 1.8
• Pb = 1.8
• Zn = 9.3
• Fe = 35.8
• Si0 ₂ = 28.8

Copper stone and slag are removed together at a melting temperature of approx. 1,320 ° C through the slot discharge of the lying cyclone vessel.

The exhaust gas emerging from the cyclone vessel in the axial direction (FIGS. 3; 9) has a temperature of 1,320 ° C. and contains approx. 56 vol.% SO ₂ .

• Cu = 2,3 %
• Pb = 22,0 %
• Zn = 26,0 %
• S = 14 %
• Fe = 2 %

The exhaust gas entrains oxidic-sulfatic fly dust of the following composition:

• Cu = 2.3%
• Pb = 22.0%
• Zn = 26.0%
• S = 14%
• Fe = 2%

This flue dust is separated in the waste heat boiler and gas cleaning systems downstream of the cyclone system.

The method of operation of the cyclone according to the invention, which is superior to conventional cyclones without a slot discharge, can be seen from the following comparison of metallurgical data (method of operation as described above).

Claims (9)

1. Apparatus for the pyrometallurgical treatment of fine-grained solids suspended in oxygen-rich gases, with a horizontally arranged cylindrical vessel and a combustion shaft combined therewith and vertically opening into the vessels well as with a gas outlet opening and a discharge opening for molten material, characterised in that the tangential opening of the combustion shaft extends tangentially into the circular cross-section of the cylindrical vessel in the form of a part spiral and opens into a discharge slot, the discharge slot being open underneath and intersecting the outer shell of the substantially cylindrical vessel substantially parallel to its longitudinal axis.

2. Apparatus according to Claim 1, characterised in that the lower surface of the slot is a continuation of the lower shell surface of the entry spiral and lower surface being planar and running tangentially at an inclination of 20 to 40° (to the horizontal).

3. Apparatus according to Claim 1 to 2, characterised in that the length of the discharge slot (along the longitudinal axis of the cylinder) substantially corresponds to the width of the inlet spiral.

4. Apparatus according to Claims 1 to 3, characterised in that the entry cross-section of the tangential opening of the combustion shaft is elliptical to rectangular.

5. Apparatus according to Claims 1 to 4, characterised in that the width of the inlet spiral increases continuously along the length of the discharge slot and this length is up to about three times the width of the entry of the spiral.

6. Apparatus according to Claims 1 to 5, characterised in that the lower portion of the shell of the vessel is provided with a return groove for the reception of molten material, which groove runs with increasing depth from the gas outlet opening to the discharge slot.

7. Apparatus according to Claims 1 to 6, characterised in that the return groove begins at a point which is spaced 1/3 to 2/3 of the diameter "D" of the gas outlet opening from the discharge slot and terminates at the discharge slot, the end of the groove having a width "B" of D/4 to D/2 and a depth "T" of T = B.

8. Apparatus according to Claims 1 to 7, characterised in that for the region of the length of the return groove the cyclone section is angled upwardly, the angling of the longitudinal axis being from 15 to 30° to the horizontal.

9. Apparatus according to Claims 1 to 8, characterised in that the lower half of the wall of the cylone formed with the return groove extends as an asymmetric cone toward the gas outlet opening.

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