WO1996006195A1

WO1996006195A1 - Process for blowing non-ferrous metal scrap and intermediate products from smelting works

Info

Publication number: WO1996006195A1
Application number: PCT/EP1995/003340
Authority: WO
Inventors: Peter Fischer; Jean-Paul Nepper; Georg Gospos
Original assignee: Metallgesellschaft Aktiengesellschaft
Priority date: 1994-08-24
Filing date: 1995-08-23
Publication date: 1996-02-29
Also published as: DE4429937A1

Abstract

According to the invention oxygen-enriched air is blown into the melt through compound underbath nozzles, oxygen or oxygen-enriched air being blown in through the inner pipe and air through the outer pipe. The flow rate of the two gases blown into the melt is set to ensure that the two gases can mix only at a distance from the mouth of the nozzle. The oxygen content of the gas mixture is 23-80 % by volume.

Description

Process for blowing non-ferrous metal scrap and smelter intermediate products

Description

The invention relates to a method for blowing non-ferrous metal scrap and metallurgical intermediates in the molten state by blowing in oxygen-enriched air by means of under-bath nozzles to produce a refined metal or stone phase.

The processing of non-ferrous metal scrap and sulfidic or metallic smelter intermediate products is carried out by blowing with oxygen-containing gases. Such substances are e.g. Cu alloy scrap, Cu stone, CuNi stone, CuPb stone, Ni stone, PbAg alloys, copper containing S or Fe or lead containing S, As, Sb or Sn.

When blowing, certain accompanying metals and impurities are volatilized or slagged. The use of oxygen-enriched air as a blowing medium brings advantages in terms of heat balance, the necessary reaction time and the resulting exhaust gas volume. However, the service life of the nozzles is generally reduced and there is increased wear of the refractory masonry of the reactor at the nozzles. The reason for this is, on the one hand, the increasing heat concentration in the focal spot in front of the nozzles, which leads to local temperature increases in the melt and the masonry, and, on the other hand, the increasing reactivity of the oxygen-containing gas with the metallic nozzle material.

In "Erzmetall", Volume XIX (1966), pages 609-614 it is described that when copper stone is blown in the Peirce-Smith converter when using O-enriched blowing wind with 28 vol .-% 0_ content near the side a strong masonry wear occurred in the arranged single substance under bath nozzles. EP-A-0 020 186 describes the blowing of non-ferrous metal stones with air or oxygen-enriched air, the gas being passed through

Single substance under bath nozzles is blown into the melt. The gas is injected at a pressure such that the flows are maintained up to a certain distance from the nozzle orifices. A 0_ enrichment of up to 40% by volume 0 ₂ can be carried out to maintain an autothermal process.

GB-PS 1 414 769 describes the blowing of Cu-containing materials, such as Cu scrap, Cu ores and Cu stone, using multi-component underbath nozzles. A gas is blown through the central tube of the nozzles, the O ₂ content of which is higher than that of air, preferably technically pure oxygen. A protective gas is blown through the tube arranged coaxially around the central tube. In the case of propane as protective gas, the volume flow ratio of protective gas to oxygen is below 4% and in the case of natural gas, the ratio is below 8%.

The invention has for its object to keep the wear of the nozzles and the masonry as low as possible in the method mentioned above and to create favorable operating conditions.

This object is achieved according to the invention by a process for blowing non-ferrous metal scrap and metallurgical intermediates in the molten state by blowing in oxygen-enriched air by means of sub-bath nozzles to produce a refined metal or stone phase, which is characterized in that by inner tube of multi-component nozzles oxygen or oxygen-enriched air is blown into the melt, through the outer tube of the multi-component nozzles air as cooling gas is blown into the melt, the blowing rates of the two gases into the melt are adjusted so that a mixture of the two Gases in the melt only at a distance from the Nozzle orifices occur, and the oxygen content in the mixed gas is 23 to 80 vol .-%. The term "multi-component nozzles' ¹ means nozzles which consist of coaxial tubes, one medium flowing through the inner tube and another medium flowing through the outer tube, which is formed from the annular space between the two tubes; or the nozzle has a solid central tube coaxially surrounded by two tubes, one medium flowing through the inner tube formed from the inner annular space and another medium flowing through the outer tube emerging from the outer annular The mouth of the nozzle is aligned with the lining of the reactor or protrudes about 2 to 5 cm above the lining into the interior The reactor can be a converter which is arranged in a rotating or stationary manner, a propellant furnace or a refining furnace.

The multi-component nozzles are preferably arranged vertically upwards in the bottom of the reactor, but they can also be arranged in any position up to the horizontal or downward inclined blowing into the melt. The most favorable distance between the mixing of the two gas streams from the nozzle orifice depends on the respective operating conditions and can be determined empirically. The mixed gas is the mixture of the two gas streams. A mixture of air and nitrogen or another non-combustible gas can also be blown through the outer tube. The reactor can be operated continuously or batchwise. If necessary, material can be added.

The advantages of the invention are that only a part of the amount of gas injected has to be highly compressed, no or little costly cooling gas is required, a relatively high oxygen content can be set and a long service life of the refractory lining of the reactor and the nozzles is nevertheless achieved. Oxygenation can be within wide limits can be varied, an oxygen content in the mixed gas of 50 to 80% by volume being particularly advantageous. Only one type of nozzle is required on the reactor.

One embodiment of the invention consists in that a mixture of air and nitrogen or another, non-combustible gas is blown through the outer tube of the multi-substance nozzles. If pure air is blown through the outer tube, an oxygen content of the mixed gas of a maximum of about 65 vol.% Can be set without the nozzle and the surrounding masonry wearing out prematurely. If, on the other hand, the air flowing through the outer tube is partially replaced by nitrogen or another non-combustible gas, the oxygen content of the mixed gas can be increased to over 75% by volume, since the gas volume flow required for cooling the nozzle is considerably reduced compared to pure air can be.

An embodiment of the invention is that the speed of oxygen or

Oxygenated air in the inner tube is Mach 0.1 to 0.8, the velocity of the gas in the outer tube Mach is 0.4 to 1.0, and the velocity of the gas in the outer tube is at least Mach 0.1 higher than the velocity of the gas in the inner tube. Very good results are generally achieved with these parameters.

An embodiment of the invention is that the speed of oxygen or

Oxygenated air in the inner pipe Mach is 0.4 to 0.6, the speed of the gas in the outer pipe Mach is 0.6 to 1.0, and the speed of the gas in the outer pipe is at least Mach 0.2 higher than the speed of the gas in the inner tube. Particularly good results are generally achieved with these parameters. One embodiment of the invention is that, depending on the oxygen content of the mixed gas, a gas volume is blown through the outer tube, which is 10 to 50% of the gas volume blown through the inner tube.

One embodiment of the invention consists in that, depending on the oxygen content of the mixed gas and the inert gas content of the cooling gas, a gas volume is blown through the outer tube which amounts to 10 to 25% of the gas volume blown through the inner tube. Particularly good results are achieved in this area.

One embodiment of the invention is that gas is blown into the melt with atomized water through the outer tube. About 10 to 200 1 / h of water, preferably 20 to 50 1 / h, of the air are mixed in, the amount of water depending on the degree of oxygen enrichment and the volume flow of the air blown through the inner tube. The required cooling air volume can be kept considerably smaller.

One embodiment of the invention is that a central tube is arranged in the inner tube and fuel is blown into the melt through the central tube. In this case, the nozzle consists of a central tube around which two tubes are arranged coaxially. Fine-grained, solid fuel is blown in with a carrier gas, which can consist of air, inert or flammable gases. Liquid or gaseous fuel can be introduced without carrier gas. Missing heat can be generated in a favorable manner in the melt by the introduction of fuel.

The invention is explained in more detail by means of examples. Example 1:

A Peirce-Sraith converter, 7.00 m long and 3.45 m long

Diameter is usually 30 nozzles of 48 mm

Equipped inner diameter by the total

₃ 12,000 Nra / h enriched in approx. 24 vol.% Oxygen

Air with a pre-pressure of approx. 1.7 bar corresponding to one

Discharge speed of approx. 40 m / s.

For experimental purposes, 6 of the aforementioned nozzles were replaced by double-tube nozzles with a 42 mm wide central tube and a narrow annular gap, which were connected on the central tube side to the existing low-pressure network for air enriched to approx. 24 vol.% Oxygen and were treated with pure high-pressure air on the annular gap side. 300 Nm / h of oxygen-enriched air was blown through the central tube of each double-tube nozzle at an exit speed of approx. 40 m / s, and 100 Nm / h of pure air were blown through the annular gap at an exit speed> 200 m / s. The remaining 24 nozzles were operated as usual, so that the total volume remained practically constant at 12,000 N / h and the oxygen content.

Molten copper-lead stone with an average of approx. 61% Cu, 11% Fe, 5% Pb and 20% S was blown in the newly delivered converter with the addition of quartz sand to blister copper. After 71 batches, the converter had to be shut down because the conventional nozzles had burned down to below the permissible minimum length and the adjoining ff. Masonry was correspondingly worn (ff. = Fire-proof).

The double-pipe nozzles still had between 50 and 70% of their working length, the adjacent wall, which was worn down accordingly, was still usable.

In operation, it was also found that the double tube nozzles had to be cleaned less frequently than the conventional nozzles. PCI7EP95 / 03340

Example 2:

For a further experiment, the converter described in the first example was equipped with 15 conventional nozzles with an inner diameter of 48 mm, the total of

6,000 Nm / h of air were operated as usual. For this purpose, 6 double pipe nozzles with a 26 mm wide central pipe and a narrow annular gap were installed.

₃ A mixture of 1,050 Nm / h was passed through the central tubes

Air and 950 Nm / h oxygen with a pre-pressure of

3.1 bar, which corresponded to an exit speed of approx. 120 m / s. The ring gaps were with a total

₃ 450 Nm / h of air, which was so highly compressed that the exit speed was> 250 m / s.

The mixed gas clearly contained approximately 51.5% by volume of oxygen.

In the newly delivered converter, molten copper-lead stone with a composition similar to that in the first example was blown onto blister copper. Due to the use of oxygen, an average of 7.5 t / h copper scrap could be melted. After 63 batches, the converter had to be stopped because the conventional nozzles had burned down to below the permissible minimum length and the adjacent masonry was worn out accordingly.

The double-pipe nozzles still had an average of 50% of their working length, the adjacent masonry was worn out accordingly, but it was still usable.

In contrast to the conventional nozzles, the double tube nozzles did not have to be cleaned during operation. Example 3:

As part of the QSL process for continuous

The production of lead from sulfide concentrates is technically pure oxygen with the help of nitrogen-cooled

Double-tube nozzle is blown into a molten bath consisting of metallic lead and lead oxide-containing slag and a temperature ^* C has about 1,200. The

Cooling nitrogen is often mixed with a small amount of atomized water. Typical flows for.

₃ such a nozzle are, for example, 800 Nm / h oxygen, 200 Nm / h

Nitrogen and 20 1 / h water. The nozzle burn rate is typically about 0.1 mm / h or less.

In order to save cooling nitrogen, a double tube nozzle with a 16 mm wide central tube and a narrow annular gap was used on a QSL reactor and operated as follows:

A mixture of 650 Nm / h of oxygen and 150 Nm / h of air at an admission pressure of 3.6 bar was passed through the central tube, corresponding to an exit speed> 150 m / s. A mixture of 100 Nm ³ / h nitrogen and 100 Nm ³ / h air was passed through the annular gap and was compressed to such an extent that the exit velocity reached a value> 250 m / s.

The oxygen content of the mixed gas was evidently approximately 70.2% by volume.

The nozzle burned at a medium speed

<0.1 mm / h and worked completely maintenance-free.

Example 4:

In a further experiment with the double tube nozzle described in the third example, cooling nitrogen was completely replaced by air to which a small amount of atomized water was added. The following operating conditions were selected: ₃ 750 Nm / h of oxygen with a pre-pressure of 4.5 bar corresponded to one through the central tube

Exit speed> 200 m / s directed. By the

An annular gap was passed through a mixture of 250 Nm / h air and 25 1 / h water, which was compressed to such an extent that the exit velocity reached a value> 250 m / s.

The oxygen content of the moist mixed gas was evidently approximately 78.0% by volume.

The nozzle burned at a medium speed

<0.1 mm / h and worked completely maintenance-free.

Claims

claims

1. Process for blowing non-ferrous metal scrap and metallurgical intermediates in the molten state by blowing in oxygen-enriched air by means of under bath nozzles to produce a refined metal or stone phase, characterized in that oxygen or oxygen is passed through the inner tube of multi-substance nozzles oxygen-enriched air is blown into the melt, air is blown into the melt as cooling gas through the outer tube of the multi-substance nozzles, the blowing rates of the two gases in the melt are adjusted so that mixing of the two gases in the melt is only at a distance from the nozzle mouth, and the oxygen content in the mixed gas is 23 to 80 vol .-%.

2. The method according to claim 1, characterized in that a mixture of air and nitrogen or another non-combustible gas is blown through the outer tube of the multi-substance nozzles.

3. The method according to claim 1 or claim 2, characterized in that the speed of the oxygen or oxygen-enriched air in the inner tube Mach is 0.1 to 0.8, the speed of the gas in the outer tube Mach 0.4 to 1.0 and the velocity of the gas in the outer tube is at least Mach 0.1 higher than the velocity of the gas in the inner tube.

4. The method according to claim 3, characterized in that the speed of oxygen or oxygen-enriched air in the inner pipe Mach is 0.4 to 0.6, the speed of the gas in the outer pipe Mach is 0.6 to 1.0, and the velocity of the gas in the outer tube is at least Mach 0.2 higher than the velocity of the gas in the inner tube.

5. The method according to any one of claims 1 to 4, characterized in that a gas volume is blown through the outer tube, which is 10 to 50% of the gas volume which is blown through the inner tube.

6. The method according to claim 1, characterized in that a gas volume is blown through the outer tube, which is 10 to 25% of the gas volume which is blown through the inner tube.

7. The method according to any one of claims 1 to 6, characterized in that gas is blown into the melt with atomized water through the outer tube.

8. The method according to any one of claims 1 to 7, characterized in that a central tube is arranged in the inner tube, and fuel is blown into the melt through the central tube.