DE1301583B - Process for melting a column made of shaped copper pieces - Google Patents

Description

1 2

The invention relates to methods for is. The combustion of the fuel is thus melted a column of copper fittings in regulates that at least 25% of the oxygen in a little Shaft furnace in a reducing atmosphere at least 75% of the mixture is consumed before by direct contact of the column with hot injuries more than about 15 cm from the furnace wall in combustion gases migrated through the furnace to produce molten 5. A variety of copper is used made with less than 0.05 weight percent sour-separated mixtures, each by material by removing hot combustion gases, which are burned in rows on the furnace shell by several of them gaseous or liquid fuel is blown into the furnace, one of the most important advantages of the invention is one of the most important advantages of the invention

Substance inadequate amount of oxygen-containing io that it is possible, copper fittings, ins-gas were obtained, in the lower part of the furnace, special copper cathodes, in a vertical position can be blown in and onto the fittings - fuel-fired furnace without contamination of the meet and wherein the mixture of fuel and copper with undesirable amounts of oxygen oxygen-containing gas before blowing into the melt. Another important benefit is that The furnace is ignited. 15 possibility of melting without impurities

So far there have been many attempts in technology against copper with undesirable amounts of made, copper fittings can be executed in a plumbing sulfur. Another Right-hand fuel-heated shaft furnace to melt the important advantage is that copper cathodes too Zen. However, these attempts to melt commercially available copper metallurgically were unsuccessful, since the copper during the smelting with 20 nes, which without bubbles or poles today's unacceptable amounts of oxygen and sulfur oxygen and sulfur requirements has been contaminated. In order to make a better product, he met sulfur content. This is how molten is supposed to hold up, copper fittings were either in the usual pure copper for casting less than Irish stoves or conventional reflective stoves contain about 0.05 percent by weight of oxygen, ovens melted that use radiant heat. 35 and in most cases it should be Oxygen That Molten copper was blowing and content was less than 0.35 weight percent. Poles subjected to sulfur and oxygen before molten copper, which the requirements after pouring the copper. fulfilled and less than 0.01 percent by weight,

The invention is particularly useful in melting, preferably 0.002 percent by weight or less, zen of copper cathodes. 30 contains oxygen, is followed by the procedure

Although the cathodically deposited copper of the invention produces. It can also be melted is commercially pure, apart from the unavoidable copper of low oxygen content small amounts of sulfate that are physically generated, this being a particularly important one adhering to the surface of the cathode or in it is an advantage, since it is possible to obtain relatively uniform are closed, the copper cathodes are cast as 35 copper products. That way you can such generally not used because of their z. B. easily and evenly with phosphorus desform and physical properties, in particular oxidized copper, which is 0.005 Gedere the grain structure of the cathodically deposited weight percent contains phosphorus, around the deoxydienes Copper. In order to bring them into usable form the last traces of oxygen in the gen, the cathodes need to be melted and the 40 copper to effect.

molten metal e.g. B. to wire bars, circuit boards In a similar way, molten copper

and rods and similar shapes are cast that are less than 0.001 weight percent from which semi-finished products such as sheets, wire, tubes, and percent or 0.0003 weight percent sulfur entanderes more is produced. Furthermore, it is when holds. Furthermore, the method according to the invention For some reason the copper with impermissible 45 in practice can be executed to a desired gen amounts of oxygen and sulfur while forming the surface of the cast copper of melting, it is necessary to create which are concave, convex or flat the sulfur and oxygen in the melted can. This feature is particularly beneficial in Copper to allowable quantities by blowing and pouring copper in conventional closed Poland is reduced before the molten metal 50 bottom forms into wire bars, which is a so-called is poured. Have a level education, d. H. a flat or

According to the invention, an increased (slightly convex) training is provided before the injection.

Mixture in the oven the difference between the Another very important advantage of the process

for the mixture provided average according to the invention is that copper in Oxygen content and the highest oxygen content, 55 in a vertical fuel-fired furnace in the which in at least 75% of a direction transverse to the flow without the generation of slag or direction of the mixture running level found the need to add slag which is kept at a value that is lower or to slag-forming materials in the furnace

than the value K of the equation: is melting. Also, the copper is little or no

0 0632.4 ^6o ü ^Dernau Pt- not contaminated by iron that comes from

K = .. - _? _ -— _._-. ₅ comes from the refractory oven lining, and it can

B + ϋ, υΙΑ copper to be melted that is less than

in the A contained in the oxygen-containing gas 0.001 percent by weight, e.g. B. 0.0003 weight percent tene volume percentage of oxygen and B contains the iron.

stoichiometric oxygen volume at 20 ° C and 65 Another significant advantage brought about by the Atmospheric pressure is created for complete invention is that of a desired combustion of the fuel mixture based on a stream of molten copper minutes after Gas can be obtained at 20 ° C and atmospheric pressure, required to start up the furnace.

The copper flow can be stopped just as quickly. This latter characteristic signifies one Another important advantage over known melting processes, since it is the case with the known processes It is necessary to completely melt a relatively large amount of copper first before the Metal can be tapped from the melt supply as required. This practice has serious ones Drawbacks and dangers arising from the need to hold one result in a relatively large amount of molten metal for relatively long periods of time. Another major advantage of the method according to the invention is that the manufacturing costs of the molten copper can be lowered.

When a column of shaped copper pieces is melted in the furnace, part of the copper is added down against or in close proximity to the oven walls. There is a gas atmosphere which contains unburned oxygen. These factors are of critical importance in terms of Contamination of the molten copper with undesirable amounts of oxygen. It was found, that this unburned oxygen can be reduced or essentially eliminated when the in The gas atmosphere to be blown into the furnace is controlled prior to blowing.

In order to develop the method according to the invention, attempts were made to use copper fittings to melt in a furnace by direct contact with hot combustion gases that pass through Combustion of natural gas in an insufficient amount to completely burn the fuel of oxygen-containing gas. The hot combustion gases were through into the furnace several burners arranged in rows on the furnace shell are blown in.

In the method according to the invention, the mixture of fuel and oxygen-containing gas can may be blown into the furnace as one or a plurality of streams.

The following table lists various values for "K" in the equation given above for various fuels used with air or pure oxygen as the oxygen-containing gas and the corresponding values for "ß".

The value of "A" for air is 21% (ie the percentage by volume of oxygen contained in air). The stoichiometric volume of oxygen required to completely burn a volume of natural gas is given by the equation:

CH ₄ + 2O ₂ -

CO ₂ + 2H ₂ O

Therefore, the value of "B" is 2. Accordingly, the value of "K" is given by the equation:

K = °> ^0632A ₌ 0.0632-21

B + 0.01 Λ 2 + (0.01 · 21) '

This equation is further illustrated by the following determination of the value for "K" given in the table above, using a liquid fuel consisting of a mixture of kerosene and air. The value for "A" is

ao again 21%, as indicated in the preceding examples. The value for "ß" from the following equation is 18.5:

2 C ₁₂ H ₂₆ + 37 O ₂ - ». 24 CO ₂ + 26 H ₂ O

* ⁵ Accordingly, the value for "K" is:

K = °> ^0632A 0.0632 2 1 _

B + 0.01 Λ ~~ 18.5 + (0.01 · 21) ~

0.071.

fuel

CO

H ₂

Methyl alcohol

(CH ₃ OH)

Natural gas (assumed

CH ₄ )

Ethyl alcohol

(C ₂ H ₅ OH)

Propane (C ₃ H ₈ )

Kerosene (assumed

C ₁₂ H ₂₆ )

Gasoline, diesel, oil,
Containing gas oil or other natural or synthetic liquid hydrocarbons
Fuels

1.87
1.87

0.776
0.60

0.414
0.255

0.071

0.07

for
oxygen

4.21
4.21

2.53
2.11

1.58
1.05

0.324

0.32 It has been found that the degree of combustion for any given ratio of fuel and increased oxygen by preheating the mixture or the oxygen-containing gas will.

Cause relatively small changes in the ratio of fuel to the oxygen-containing gas relatively large changes in the degree of combustion, especially if liquid and gaseous hydrocarbons Fuels and especially natural gas are used.

During the operation of the furnace for carrying out the method according to the invention, it was found that at predetermined reducing conditions before blowing the mixture into the Furnace the oxygen contained in the molten copper thereafter by the strength of the furnace atmosphere prevailing reducing conditions is determined. The furnace atmosphere preferably contains at least 0.5 percent by weight hydrogen or 0.5 percent by volume carbon monoxide, if

a hydrocarbon-containing fuel is used V ₂ .

V ₂ The shaft furnace may be a generally vertically arranged furnace of a desired 1- ¹ Z ₂ 55 shape or size that supports a column of any desired size and shape of the copper to be melted that moves downward in the furnace, when the copper is melted.

It is Z. B. when melting copper cathodes 6o advantageous to introduce the cathodes into the furnace so that they are in it in an arbitrary order

18.5 are arranged.

It has been found that solidification of the

molten metal in the furnace and clogging of the furnace tap hole or eliminated Can be largely reduced by putting hot combustion gases in the lower part of the

18.5 furnace directs.

The invention is explained in more detail below using an exemplary embodiment with reference to the drawing. In the drawings shows

F i g. 1 is a side view of a partially shown shaft furnace for carrying out the invention Procedure,

F i g. 2 is a sectional view taken along line 2-2 in FIG

The in F i g. 1 shown shaft furnace 1 has a

heated for about 15 to 30 minutes to preheat the refractory oven lining. Then it will be like that put a lot of copper in the furnace to make a column that extends to the top of the furnace. 5 The cap stones 40 are placed on the tapping channel 3 again. The furnace is then heated, whereby the molten copper in the furnace runs down onto the sloping floor, from where it is flows through the tapping hole 8 into the tapping channel 3.

Shaft 2, a tapping channel 3 and a pipeline io Before there, the molten copper can be used, for example The burner 4 is fed with a mixture of wise direct to suitable Gießvorrich fuel, not shown and an oxygen-containing gas. services are delivered. While melting As shown in Fig. 2, the furnace shell 6 and is copper intermittently or continuously in the the furnace floor has a refractory lining 5. Given the gas furnace. The pressure of the furnace becomes impermeable as well Oven jacket 6 consists of a spherical 15 held so high that the oven gases cause suitable material, such as steel. The furnace jacket 6 and that the liquid copper through the tap hole 8 the chuck 5 have channels 7 for the burners 4. flows and at least part of the tapping channel 3 The lower inner furnace surface 9 is inclined inwardly, fills.

and the furnace bottom 10 is against the tap opening 8. The following are examples of the after

inclined, which merges into the tapping channel 3. The ao invention carried out method specified. Shaft 2 has an opening 15 for loading. ■,,

of the furnace, this opening 15 being replaced by example 1

a door 16 is lockable. For water cooling, an oven as shown in Figs. 1 and 2 was used

of the shaft bottom a tubular frame 17 is provided, type used with conventional refractory which was lined with cooling water from a not shown aluminum silicate brick. The Bo source is fed. At the upper end of the shaft the furnace was inclined to ensure that A flap 18 is provided to allow upright molten copper from the furnace without holding it together a desired pressure during the development as a melt pool flows in it. Neither that Fusion is closed. The part of the fuel still contains the oxygen-containing gas was shaft Above the door 16 serves as a preheating 30 which is preheated.

section and is provided with an annular channel 20 Natural gas was used as fuel and oxygen

made of steel, the gas containing air on its outer surface was used. That on the stove is surrounded by insulation 21. One supplied fuel mixture contained 18.85 volume fans 19 becomes air at the desired pressure through percent oxygen. The oven was on for about 30 midas Pipe 22 led to the junction 23, from where 35 grooves are preheated to the refractory furnace lining heat them down between the channel 20 and the. Then copper cathodes were placed in the Shaft 2 flows into branch 24, which furnace is given, so that a column was formed. While is also surrounded by insulation. During the melting process, further cathodes were added, the air is heated and flows from the branch around the top of the column at the level of the top supply 24 through insulated pipes 25 and 26 to keep the iso- 40 parts of the furnace. Then the lated branches 27 and 28, from which it heats the burner.

with a desired pressure to the individual within 5 minutes after the start of heating

Burner 4 is passed through insulated tubes 29. the burner started to its operating capacity. The preferably gaseous fuel from a molten copper from the tap hole 8 to source not shown will flow _{by a fan 37 45;} In two and a half hours after the start of this heating at a desired pressure through the insulated one, the furnace delivered an average of 121 molten pipe 30, which is provided with the heater 31, copper per hour. Thereby were pressed at time intervals. The heater can, for example, take samples of the furnace atmosphere. Analyzes included a heat exchanger showing either of these samples that the furnace atmosphere contained electrically generated heat or hot combustion 50 2.07 volume percent hydrogen. Used on the products. From the fuel tap hole thus preheated, samples of the molten material were then taken through insulated pipes 32 and 33 to iso-copper, whereby it was found that branched branches 34 and 35 and is then taken
through insulated pipes 36 at the desired pressure
to the individual burners 4, which are also part of the 55th
Can be insulated to avoid heat loss.

Each burner 4 is gas-tight in a shaft furnace
used. This prevents air from entering the

Furnace interior can flow through the channels 7. It's taken 60 from each burner, a number of burners in this manner in the furnace - the samples contained oxygen levels of 18.58

jacket arranged in a number of rows. At up to 19.02 percent by volume. The relationship of the burner Preparing to start up the furnace will be fabric to be delivered to the individual burners the capstones 40 were partially removed, and all air was then adjusted so that the gas samples The inner surface of the tapping channel 3 is oxygenated by gas burners 65 from each burner to 18.80 percent by volume heated to ensure that initially contained. After this setting, the water-molten metal remained out of the furnace without solidifying the furnace atmosphere at the top and bottom ren, can flow away. The furnace itself is also essentially unchanged from the bottom of the furnace

these samples contained more than 0.05%, namely 0.069% by weight oxygen.

Example 2

The procedure described in Example 1 was followed
repeated and the results were the same
obtain. Samples of the gas mixture were also taken

at 2.17 percent by volume. However, it has been found that the oxygen content of the molten copper increased to 0.083%.

Gas samples were then taken at various points in each burner. The analysis the samples showed wide variation in total oxygen content. The lowest total oxygen content was 18.62 percent by volume, while the highest total oxygen content was 19.6 percent by volume was established.

Then a perforated plate in each burner was moved across the path of the air flow, and that The ratio of fuel to air delivered to the burners was set at 18.80 percent by volume. Subsequently, the amount of natural gas and air supplied to the furnace remained essentially unchanged, wherein the hydrogen content of the furnace atmosphere at the top and bottom of the furnace is substantially remained at 2.04 volume percent. However, it was found that the oxygen in the molten Copper was reduced so that it contained 0.0079 weight percent oxygen. It also contained Copper less than 0.0007 weight percent sulfur and less than 0.001 weight percent iron. Even No slag was formed during the melting process.

Example 3

A small oven with a single burner was used. The mantle and bottom of the furnace were lined with conventional refractory aluminum silicate bricks and a steel casing surround. The furnace floor was inclined slightly towards the tap hole. During the melting process the stove was partially covered.

The burners were discontinued, with heating using a mixture of natural gas as fuel and air as an oxygen-containing gas took place. Samples of the gas mixture taken across the flow path in the burner showed a difference in total oxygen content of less than 0.01.

The furnace was then heated and a copper cathode was placed in the furnace so that it was 30 cm from the furnace wall in which the burner was arranged was removed. The burner was then full Heating provided, with unheated natural gas and air supplied to the burner. This fuel mixture contained 18.80 percent by volume oxygen. Melting started in less than 5 minutes Copper to flow through the tap hole. During the experiment, samples of the molten Copper removed at the tapping hole. Analysis of the samples revealed an oxygen content in the Copper of less than 0.01 weight percent.

This experiment was repeated with a cathode placed in the furnace so that it could be removed the cathode was 15 cm from the furnace wall. The analyzes showed in the molten Copper 0.039 weight percent oxygen.

The experiment was repeated with the copper cathode placed 30 cm from the furnace wall became. In this case, the mixture of unheated natural gas and air contained 18.6 percent by volume Oxygen. Analyzes of the molten copper showed an oxygen content of 0.035 percent by weight.

Example 4

The procedure described in Example 3 was repeated in a series of experiments, with various Ratios of natural gas to air have been set, which are listed in the following table are. The cathode parts in each experiment were placed 30 cm from the furnace wall. at Experiment No. 6 was the cathode portion inside the furnace in the upright position in front of the burner and 23 cm from the furnace wall. In each experiment, a gas sample was placed 15 cm inside the Taken from the furnace in the longitudinal axis of the burner. These gas samples were based on unburned oxygen analyzed; the degree of combustion was also determined. There were also samples of each melted Copper removed and analyzed for oxygen content. The results are off The table below shows the oxygen and hydrogen contents in percent by volume are.

Attempt 1 Attempt 2 Attempt 3 Attempt 4 Attempt 5 Trial 6 O ₂ before ignition%
Unburned O ₂ , 15 cm from the
Furnace wall% 18.90
1.70
91 18.78
2.16
88V2 18.67
5.59
70 18.62
4.38
76Vg 18.61
5.24
72 18.55
13.4
27V2 Degree of burn, 15 cm from the
Furnace wall% 0.01
1.0 0.005
2.55 0.015
4.00 0.029
4.80 0.035
5.00 0.047
5.65 Oxygen in copper, according to Ge
weight% Furnace atmosphere, hydrogen ..%

Example 5

An oven according to Example 1 was used. It was evenly distributed in the furnace wall Burner arranged.

The fuel used was propane that was not preheated and air that was not preheated as oxygen Gas used. Before ignition, this mixture contained 19.90 percent by volume of total oxygen. before During the melting process, the aforementioned perforated plate in each burner was shifted until the maximum Total oxygen content found in the plane transverse to the direction of flow is less than 19.95 percent by volume.

The oven was heated for about 20 minutes to heat the oven lining. Then there were copper cathodes placed in the oven at an angle of about 60 ° to the horizontal became. Cathodes were refilled during melting. The copper was in an amount of

909534/320

41 melted per hour. Samples of the molten copper emerging from the furnace in graphite molds. The analyzes of the Samples showed that the oxygen content was less than 0.005 weight percent.

Example 6

Copper exiting the furnace contained 0.002 weight percent oxygen.

The iron in the copper in the previous ones

Examples were determined by a spectrographic method. Gas samples that are less than about Oxygen by volume were analyzed with a mass spectrograph.

The furnace shown in drawing 2 was constructed so that it had 18 burners that were uniform distributed in four rows. The two lower rows each contained six Burner. The center line of the lower burners was 18 cm above the highest point of the inclined furnace floor. The distance between the first and the second row was 50 cm, the distance being 60 cm between the second row and the third row and between the third and fourth row was also 60 cm.

It was natural gas as fuel and air as ao oxygen-containing gas is used. The air was preheated in the duct 20 and the natural gas in the heater 31. The fuel mixture contained 18.82 percent total oxygen by volume prior to ignition. before During the melting process, the aforementioned perforated plate in each burner was shifted until the maximum The total oxygen content found in the plane transverse to the direction of flow of each burner is lower than was 18.90 percent by volume.

The furnace was loaded with copper cathodes. The burners were then heated for about half an hour, to heat the refractory material. After that, the burners were at full heating capacity drove. The furnace atmosphere contained 1 volume percent hydrogen, with the pressure in the range of the furnace floor was so large that the molten copper through the tap hole 8 into the covered channel 3 raft. The furnace reached its full melting point in 15 minutes.

Samples of the molten copper showed that it was less than 0.005 weight percent oxygen and contained less than 0.0005 weight percent each of iron and sulfur.

Example 7

45

The process of Example 3 was repeated, using kerosene as the fuel and air as the oxygen-containing one Gas was used. The furnace atmosphere contained 2.64 percent by volume hydrogen. The degree of burn during the time in which the fuel mixture migrated from the furnace wall 15 cm into the furnace interior was more than 99%. It was no difference was found in the total oxygen content across the direction of flow. The melted one

Claims (2)

Patent claims: 1. A method for melting a column of copper fittings in a shaft furnace in a reducing atmosphere by direct contact of the column with hot combustion gases to produce molten copper with less than 0.05 percent by weight oxygen by using hot combustion gases produced by combustion of gaseous or liquid fuel an insufficient amount of oxygen-containing gas for complete combustion of the fuel were obtained, are blown into the lower part of the furnace and hit the fittings and wherein the mixture of fuel and oxygen-containing gas is ignited before blowing into the furnace, characterized in that before blowing the mixture into the furnace, the difference between the average oxygen content intended for the mixture and the highest oxygen content found in at least 75% of a plane extending transversely to the direction of flow of the mixture is maintained at a value, d it is less than the value K of the equation: K = 0.0632Λ
B + 0.01 A in which A is the Volumprozentgehalt contained in the oxygen-containing gas of oxygen and B is the stoichiometric volume of oxygen at 2O ⁰ C and atmospheric pressure, for the complete combustion of the fuel mixture, based on a gas at 2O ⁰ C and atmospheric pressure, is required, and that the Combustion of the fuel is controlled so that at least 25% of the oxygen in at least 75% of the mixture is consumed before the latter has migrated more than about 15 cm from the furnace wall into the furnace. 2. The method according to claim 1, characterized in that a plurality of separate mixtures each by several of them arranged in rows on the furnace shell Burners is blown into the furnace. 1 sheet of drawings