DE2845297A1 - PROCESS FOR CHLORINATING REFINING OF MELT CONTAINING COPPER - Google Patents

Description

Dr.-Ing. Reimer · König ■ Dipl.-Ing. Klaus Bergen Cecilienallee 76 <4 Düsseldorf 3O Telephone 452OOS Patentanwälte

October 17, 1978 32,610 K

INCO LIMITED, 1 First Canadian Place, Toronto, Canada M5X 1C4

"Process for the chlorinating refining of copper-containing stone melts"

The removal of traces of lead, arsenic, bismuth, zinc, antimony and cadmium from copper stones or copper-nickel stones is extremely difficult and time-consuming. All the more so than the permissible residual levels of such impurities are very low, but on the other hand the levels of impurities in the stone as a result of improved dust separation and the reuse of the dust rich in impurities will increase.

In nickel extraction, the impurities can be selectively removed due to their affinity for chlorine. So fall at For example, chlorinating molten nickel stones with chlorine gas or nickel chloride contains chlorides of the impurities Depending on the procedure, either evaporated or in a liquid phase or molten sodium chloride above the melt as described in U.S. Patent 3,802,870. Melt down when removing arsenic from nickel US Pat. No. 3,938,989 shows a sulfur content of at least $ 28> as critical for adequate Removing the arsenic.

It is known to be a low-copper nickel stone subject to chlorinating refining, thereby removing the copper along with other impurities. Problematic is the chlorinating refining of molten stones with a higher copper content such as copper or also Niekelstein smelting with 10% or more copper in the back

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view of the extraordinarily large amount of copper chloride that is produced and insufficient removal of the impurities. Large amounts of chlorine vapors also occur during chlorination. On top of that, the one responsible for removing it of the arsenic required minimum sulfur content can be adjusted in practice with copper stones only with difficulty. The application the well-known process for refining nickel stone "in refining copper stone also fails because of the high solubility of the chlorides in copper stone.

A refining process is also known from US Pat. No. 4,054,446, in which a copper sulphide melt is initially produced by sulphiding from the area of the miscibility gap between Brought copper and copper sulfide and then removed of the impurities as vaporous chlorides is selectively chlorinated while simultaneously increasing the sulfur concentration is monitored to keep the melt outside the miscibility gap.

Proceeding from this prior art, the invention is based on the object of monitoring the sulfur concentration to create an independent process for the refining of stones with a significant copper content, in addition, with regard to does not require such a high sulfur content to remove the arsenic.

The solution to this problem consists in a method in which, according to the invention, a rock melt containing at least 10% copper as well as lead, arsenic, bismuth, zinc, antimony and cadmium individually or side by side as impurities without chlorinating the copper at at least 800 ⁰ C copper and / or nickel chloride and / or a free chlorine entered at least in a stoichiometric amount for the chlorination of the impurities, the chlorine supply interrupted and the melt then preferably at least 10 minutes, for example with a

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is flushed with a fluid containing inert gas.

The method according to the invention can be carried out in the same converter in which the stone is also blown, provided that the converter is provided with an appropriate exhaust gas cleaning system. However, the method according to the invention is preferred carried out in a special chlorination tank, for example in a pan provided with a gas-tight lid. The chlorinating gas can be introduced into the molten stone with the aid of a nozzle protruding through the pan lid. Of the The lid must also have an exhaust gas nozzle for sucking off the reaction gases containing the chlorides of the impurities, which is connected to a Viascher via a line for removing and recovering the chlorides and any chlorine that is still free is.

In the process according to the invention, chlorine gas is preferably used as the chlorinating agent, optionally together with a carrier gas. The primary task of the carrier gas is to ensure sufficient bath movement. Particularly suitable the carrier gas is nitrogen, albeit for cost reasons despite the risk of oxidation of copper, nickel, cobalt and iron Air can also be used as a carrier or purging gas. A certain If the stone has a substantial iron content, oxidation can even be advantageous in order to remove the iron as slag from the molten stone to be able to withdraw.

Instead of gaseous chlorine, however, solid chlorinating agents such as copper and / or nickel chloride are also suitable, which can be stirred into the stone melt or blown into the lower part of the melt.

On the other hand, however, the method according to the invention can also be used with a molten salt layer on the bath surface perform that as a solvent for at least some

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used for the chlorides produced during refining. However, the slag not only absorbs the chlorides of the impurities but also a certain amount of copper and nickel chloride, which makes it necessary to recycle or recycle the slag. The salts in question must of course be able to cope with the bath temperature. The bath or refining temperature is preferably from 900 to 1200 ^° C. In this temperature range, common salts such as sodium or potassium chloride have too high a vapor pressure; In contrast, barium and calcium chloride or fluoride are more suitable individually or side by side. Such a salt layer does not absorb all chlorides, since some chlorides, for example the metalloid chlorides, not only escape from the bath but also from the salt layer because of their high vapor pressure.

Regardless of whether the inventive method with the help of a gaseous or solid chlorinating agent and with or is carried out without a liquid salt layer, this is at least ten minutes, preferably twenty to sixty minutes continuous rinsing after the chlorination stage is essential. This purging can be with an inert gas or, if a certain oxidation of the base metals is not important, for economic reasons this can also be done with air. The duration the flushing gas treatment must ensure sufficient removal of the residual chlorine dissolved in the melt. This is how the Schmelzejiach should the flushing gas treatment do not contain more than 0.1% chlorine to avoid damage to health during subsequent processing to avoid the chlorinated stone.

The method according to the invention is preferably suitable for stones containing at most 596 iron. Leave such stones without difficulty through conventional freshening in one usual converter in the presence of a silicon-containing flux produce. The sulfur content of the stone to be refined is also of certain importance. Of course he needs

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Stone does not do the above in connection with nickel stone refining mentioned to contain at least 28% sulfur; Arsenic and bismuth, however, can be found to be extremely effective Remove wise if the sulfur content is at least that required for a setting of the base metals copper, nickel, and cobalt Iron corresponds to the required stoichiometric amount. However, the starting sulfur content of the stone is preferably the same at least 1.05 times the stoichiometric amount. In individual cases, the sulfur content can easily be stirred in elementary sulfur in the molten stone or by introducing it with the help of a graphite lance or through masonry nozzles set in a conventional Smith converter for the introduction of sulfur vapor or a sulfur-containing gas.

The invention is explained below on the basis of exemplary embodiments explained in more detail.

example 1

To remove the lead, 5 kg of a nickel-copper stone with 48% nickel, 28% copper, 0.56% iron, 0.62% cobalt, 0.16% lead and 21.7% sulfur were inductively melted in an alumina crucible and refined at 1020 to 1090 ⁰ C by blowing in 21 l / h of chlorine gas with the aid of an immersion lance. After 40 minutes or the blowing in of 0 _s, 8% by weight of chlorine, based on the bath weight, the melt contained 0.031% lead and 0.54% chlorine; it could only be shed with heavy smoke development.

After the chlorination, the melt was flushed for 30 minutes by blowing in 30 l / h of nitrogen using the same lance. One Another sample could be poured smoke-free and contained 0.013% lead and 0.04% chlorine.

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If the amount of chlorine increases with regard to a better degree of purity, then the flushing time is also extended. Thus, when 1.0% by weight of chlorine is introduced, based on the Bath weight, a lead content of 0.018%. After a 45 minute With nitrogen flushing at 60 l / h, the metal only contained 0.007% Lead and 0.12 wt% chlorine. Because of the relatively high residual chlorine content, a slight steam formation. On the other hand, flushing a comparative melt with 90 l / h nitrogen for one hour did not result in any smoke development when potting as well as 0.005% lead and 0.06% by weight chlorine.

Example 2

In a comparative test with two stone melts A and B as shown in Table I Composition 5.34 kg batches in the alumina crucibles were each mm with a diameter of 94 and mm at a bath height of 170 inductively melted and at 1020 to 1089 ⁰ C by means of two Lances usually gassed with an opening diameter of 6 mm in a bath depth of about 160 mm below the bath surface. Experiment A was carried out similarly to Example 1, ie the melt was first chlorinated and then flushed with nitrogen using the second lance. During experiment B, nitrogen was blown into the melt continuously, ie also during the chlorination. The test data are given in Table I; they show the beneficial effect of the simultaneous blowing in of nitrogen with regard to the refining time and the residual chlorine content using the example of the data after a test duration of 10 minutes.

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Example 3

In large-scale tests, two 2 t batches C and D were chlorinated in a deck pan with the aid of a dip lance. The at Reaction gases resulting from chlorination were suctioned off and fed to an alkali scrubber. The starting melts contained 44% nickel, 32% copper, 0.63% cobalt, 0.83% iron, 0.049% lead and 22% sulfur. The test results are compiled in Table II below.

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Table 2

after this Beginning Attempt C Attempt D Stone weight (KG) after this end 2120 1700 Bath temperature ( ⁰ C) amount of lead removed {%) 1150 1125 Residual chlorine content (Gevfr-%) 1000 1015 Amount of chlorine gas (% by weight) 0.33 0.50 Chlorination time (min.) 11 12th Amount of nitrogen (wt- ^) Beginning 0.88 1.0 Flushing time (min.) Chlorination 34 32 Lead content (%) Wash - 0.049 0.049 0.036 0.025 0.015 0.010 69 80 0.049 0.036

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Example 4

In two further experiments E and F, according to Example 1, two melts with different sulfur contents were produced treated first with chlorine and then with nitrogen. In both cases, 3 wt .- ^ chlorine, based on the bath weight, blown in and then flushed with 12 l / h nitrogen for 30 minutes. The bath analysis after chlorination and after the rinsing is shown in Table III. Above all, the data in this table shows a significant difference in the arsenic content found in experiment F. was low, while in Experiment E with the less sulfur-containing stone, virtually no arsenic was removed.

Table III

attempt Time Cu
(#) Ni Fe R.A.M Pb As Zn Sb . CD
I 0Δ. ι
ν / 0 J Bi Cl Beginning 48.1 24.0 1.84 21.3 0.84 0.54 0.43 ο, οδε 0.066 0.10 0 E. End of d.
Chlorination _ 0.021 0.62 < 0.002 0.013 0.016 0.05 1.41 End purging gas
plot 48.9 25.8 0.51 21.4 0.004 0.54 <: 0.002 0.002 <0.001 0.02 0.07 en Beginning 46.8 22.5 1.60 25.6 1.01 0.69 0.26 0.085 0.10 0.10 0 098 F. End of d.
Chlorination - - - - 0.052 0.075 0.004 <0.002 0.011 0.029 1.25 End purging gas
plot 48.6 24.2 1.02 24.2 0.011 0.033 ^ 0.003 <0.002 <0.002 0.008 0.13 σ

Example 5

In a further experiment, a stone melt with 48% nickel, 28% copper, 0.036% lead, 0.38% iron and 21.7% sulfur at 1000 ⁰ C under a molten salt layer of 75% calcium chloride and 25% copper chloride in a quantity chlorinated by 10% of the bath weight. In the subsequent flushing gas treatment with 60 l / h nitrogen, the data shown in Table IV below resulted; these show a satisfactory refining result after 15 to 30 minutes of rinsing as well as a reduction in the content of impurities both in the bath and in the molten salt.

Table IV

stone Lead content Iron
(50 ehalt Stirring time 0.036 stone (min) 0.022 salt 0.38 salt 0.018 0.189 0.38 1.15 0 0.017 0.253 0.37 1.19 2 0.014 0.242 0.44 1.31 4th 0.011 0.219 0.37 1.24 6th 0.009 0.185 0.38 1.11 10 0.006 0.131 0.39 1.02 15th 0.105 0.37 1.10 20th 0.063 0.90 30th Example 6

To show that a copper chloride melt is particularly suitable for multiple uses, seven 400 g stone melts were used with the composition according to Example 5, however

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with 0.058% lead in each case with the same 60 g of an initially consisting of 20% copper chloride and 80% potassium chloride existing salt melt at 100O ⁰ C, and then chlorinated l / rinsed for 15 minutes with 1 min nitrogen. The results of this series of tests can be seen from Table V below.

Table V

Molten stone residual lead content

1 0.009

2 0.012

3 0.012

4 0.013

5 0.012

6 0.013

7 0.012

Example 7

That the inventive method is also suitable for refining nickel-free stone melting proves an experiment in which a lead and arsenic-containing copper sulfide melt at 1170 ⁰ C by 20.6 minutes bubbling 3Qew .-% chlorine, based on the bath weight, refined and then flushed with 1.5% by weight of nitrogen, based on the bath weight. The test results are shown in Table VI below; they again demonstrate the importance of purge gas treatment.

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Table VI

Cu Pb As

Stone melt 77 ,8th 0 , 82 0 , 15 20th , 6 after chlorination 0 , 22 0 , 02 18th , 4 after np rinsing 0 , 004 CO , 001 17th ,8th

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Claims (10)

Claims; 1. A method for refining at least 10% copper and as impurities individually or side by side lead, arsenic, bismuth, zinc, antimony and cadmium containing rock melts with chlorine, characterized in that at at least 800 ⁰ C copper chloride, nickel chloride and a gas containing free chlorine individually or introduced side by side in at least the amount stoichiometrically corresponding to the chlorination of the impurities and the melt is then treated with a flushing gas. 2. The method according to claim 1, characterized in that that the purge gas treatment at least Takes 10 minutes. 3. Method according to claim 1 or 2, characterized in that that the molten stone is flushed with an inert gas-containing fluid. 4. The method according to one or more of claims 1 to 3, characterized in that the stone » melt is adjusted to a sulfur content of at least 1.05 times that for the The setting of the copper, iron, nickel and cobalt as sulfide corresponds to the stoichiometrically required amount. 5. The method according to one or more of claims 1 to 4, characterized in that the molten stone is kept at 800 to 1200 ⁰ C during chlorination and rinsing. ORIGINAL INSPECTED 6. The method according to one or more of claims 1 to 5, characterized in that an inert gas ent during the chlorination and the flushing gas treatment holding fluid pearls through the melt. 7. The method according to one or more of claims 1 to 6, characterized in that the
Melt below a barium chloride, calcium chloride
and molten salt containing calcium fluoride individually or side by side. 8. The method according to one or more of claims 1 to 7, characterized in that one
iron-containing molten rock is refined with a gas mixture of chlorine and air. 9 · The method according to one or more of claims 1 to 8, characterized in that the
The melt is flushed with nitrogen. 10. The method according to one or more of claims 1 to 9, characterized in that a
iron-containing molten stone is flushed with air. sghk