FI73741B - FOERFARANDE FOER KONTINUERLIG FRAMSTAELLNING AV RAOKOPPAR. - Google Patents

Description

: 73741

This invention relates to the continuous production of crude copper and, more particularly, to a process in which a pair of crude copper is produced autogenously in stages from shore and sulfur-containing copper rock.

In recent years, environmental and economic pressures have forced a sharp departure from the methods used in the copper smelter for several decades. As those skilled in the art know, the first step in the production of crude copper is usually the smelting of the copper concentrate from the concentrator.

Several methods are used in industry for this purpose. In this context, it is recognized that autogenous methods for smelting copper concentrates are the most economical in terms of energy demand. For example, the Inco process described in "The Winning of Nickel" by Boldt and Queneau, Longmans Canada Limited, 20 Toronto 1967, pages 245 and 246, produces copper rock as well as concentrated SO 2 gas, which is recovered and converted to liquid sulfur dioxide. The autogenous smelting process is thus very advantageous both economically and environmentally. An additional advantage is that the slag generated in the 25 Inco autogenous smelting process can be discarded while causing only very low copper losses when producing metal rock containing up to 55-60% copper. However, even if a metal stone of satisfactory quality is produced, the problem 30 is still its conversion into raw copper. For many years, copper converters have been used on a batch basis, periodically loading metal rock into the converter and melting it into raw copper in one process step by blowing air or oxygen-rich air into it. In such a process, the composition of the molten bath converted to raw copper 2,73741 is constantly changing in terms of iron and sulfur content, and it proved very difficult to recover the sulfur dioxide generated because huge amounts of gas had to be treated and the sulfur-5 dioxide content in the gas changed constantly.

As Biswas and Davenport's article entitled "Continuous Production of Blister Copper - Single Step and Multistep Processes", Extractive Metallurgy of Copper, Pergamon Press, 1976, Chapter 11, 10, pages 217-241, explains both single and multistage processes. processes for the conversion of copper rock on a continuous basis have been studied. This invention relates to a multi-stage process in which the initial smelting of copper concentrate to produce metal rock is carried out separately from the continuous production of crude copper in a converter. Like

Biswas and Davenport point out, the Mitsubishi process described in CA patents 952,319 and 954,700, as well as T. Nagano and Γ. Suzuki’s article, “Commercial Operation of Mitsubishi 20 Continuous Copper Smelting and Converting Process,” published in Extractive Metallurgy of Copper, Volume 1, Chapter 22, 197, 1976, pages 439-457, is a commercially viable process for producing raw copper by continuous principle. While the Mitsubishi process-25 is indeed commercially viable, it does have its drawbacks. The most significant disadvantages include the recycling of all-all ferrite slag from the converter to the smelting stage. This process requirement, in turn, results in the need to perform the smelting step in a high energy demanding manner. Thus, the highly oxidized basic converter slag, which contains about 15 or 20% CU 2 O and about 10-20% CaO, with the remainder being mainly magnetite, is returned as a cold addition to the melting furnace. In addition, the quality of the melting furnace stone is kept 35 high, i.e. copper content of about 65%, converted

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3,73741 to limit the amount of lime-ferrite slag generated, to limit the need for lime-containing flux, and to limit the fuel requirement for smelting. Returning the lime-ferrite converter slag to the 5 smelting furnaces provides a fairly solid relationship between the quality of the metal rock and the amount of converter slag produced and recycled. These factors make it impossible to produce discarded slag directly from the melting furnace. Thus, the Mitsubishi process uses 10 slag cleaning furnaces between the melting furnace and the converter.

In addition, the Mitsubishi process is not suitable for copper rock slags that contain relatively high nickel contents because it has no nickel separation. Therefore, most of the nickel in the nickel-containing copper rock treated by this method would be oxidized and lost with the discarded slag, or the nickel content of the crude copper would be undesirably high, or both. There would also be an accumulation of nickel oxide mass in the converter, which would lead to obvious operational difficulties.

Those skilled in the art know that in continuous conversion, a metal rock is fed to the converter at a constant rate and an oxygen-containing gas is blown into it to oxidize the iron and sulfur it contains. This feature of the 25 continuous converters means that sulfur dioxide is generated at a constant rate that depends directly on the rate of addition of the metal rock. Thus, standard compositions form a gas, and the sulfur dioxide content of the gas can be adjusted so that the economical recovery of sulfur dioxide as sulfuric acid is easy.

According to the invention, crude copper is produced from copper rock on a continuous basis using lime-ferrite slag which dissolves the iron oxides formed in the oxidation of the iron in the metal rock and which is slowly cooled and separated into a ferromagnetic fraction containing a large proportion of oxidised iron and a non-magnetic contains most of the lime and copper contained in the lime-ferrite slag and can be returned to the process. The metal rock to be treated can be from any source, but preferably, in order to avoid energy loss, it is produced by autogenous smelting of sulphide-containing materials, e.g. sulphide-copper concentrates. When producing slag in a converter, the non-magnetic fraction can be recycled in a closed circuit containing the converter, and it is not necessary to return 10 slag to the melting furnace. Alternatively, the metal rock to be converted to raw copper may be flame retardant. Autogenously charged, preferably using oxygen and slag-forming agents intended to produce lime-ferrite slag in smelting. The process steps are described in detail in claim 1.

According to the invention, the copper rock is fed at a controlled rate to a melt bath of the converter, which contains a raw copper mass and on top of it a layer of lime-ferrite slag. The amount of oxygen required to oxidize the iron and sulfur contained in the metal rock to be fed is also supplied to convert the iron content to iron oxides and to convert the sulfur content to sulfur dioxide within a specified time. The iron oxides formed dissolve in the slag, and a lime-containing flux is added to maintain the good flowability of the slag, which slag contains not only iron and calcium oxide but also copper (I) oxy dia Cu 2 O. The slag and crude copper are continuously or periodically removed from the converter, and the slag is recovered, e.g. in large molds, and cooled slowly. The slowly cooled slag is ground and magnetically separated to give a ferromagnetic fraction containing a large amount of iron and a low copper and calcium content and a non-magnetic fraction containing most of the lime (CaO) and copper and some of the iron contained in the slag. The ferromagnetic 5,73741 fraction contains at least about 40% and usually about 50-70% of the iron contained in the slag and is discarded to separate the iron without any significant loss due to copper or lime losses. The non-magnetic fraction can be returned in its entirety to the converter, in which case only small additions of lime (CaO) or limestone (CaCO 2) are needed to replace the small amount of lime removed by the magnetic fraction. If necessary, a combination of magnetic separation and flotation can be used to improve the separation of magnetic and non-magnetic and kee. As used herein, the term "slow cooling" means that the slag is cooled from a temperature of about 1250 ° C to a temperature of about 1000 ° C at a rate of approximately 0.5-5 ° C / min. Preferably, the cooling rate is less than 2 or 3 ° C / min.

The lime-ferrite slag on the surface of the crude copper contains mainly lime (CaO), iron (III) oxide (Fe 2 O 2), iron (II) oxide (FeO) and Cu 2 O. The weight ratio of total iron (FeT) to calcium oxide is from about 2 / l to about 3 / l and can be as high as 4/1. The weight ratio of trivalent to divalent iron should be between about 3 and 10, while the copper content of the slag can be between 10% by weight and about 30% by weight. Typically, the composition of the slag in 25% by weight may be 12-22% CaO, 45-55% Fe 2 O 3, 5-15% FeO 2 and 10-25% Cu 2 O. At a given temperature, a high Cu 2 O content generally corresponds to a high ratio of trivalent to divalent iron.

The crystallization and solidification event of the converter slag is complex and not fully known, but it has been found that during slow cooling and solidification, the slag forms crystals belonging to three different main phases suitable for separation by conventional mineral enrichment methods. The phases are ferromagnetic 35 oxide spinel type crystal lattice, dicalcium ___ - ·! L.

6 73741 ferrite (Ca 2 Fe 2 O 2 -) and cuprite. It has been found that virtually all of the iron (II) oxide is bound to the iron (III) oxide Fe2®3 to form very clear spinel crystals close in composition to the magnetite Fe 2 O 3. As a result of this Spinell crystallization, the lime content (CaO content) of the remaining liquid increases. This in turn initiates the crystallization of dicalcium ferrite, and then cuprite crystallizes. Spinel is found to contain very little 10 copper or calcium, usually less than 1% and 2%, respectively, while instead accumulating approximately 50-70% of the total iron in the slag. It is also observed that during slow cooling, the spinel crystals grow to large sizes, which promotes the separation of the spinel 15 from the non-magnetic phases. This makes it possible to remove iron from the slag without losing significant amounts of calcium or copper. In practice, a wide variety of deviations from the ideal crystallization event described above can be encountered, mainly in the composition of the slag 20, especially in the ratios of Fe 2 O.j / Fe0 and

Fe 2 O / CaO, as well as the presence of some other constituents such as SiO 2. For example, when the FeO content of the slag is lower than that required solely to obtain magnetite, dicalcium ferrite, and copperite, some calcium ferrites other than Spinell, dicalcium ferrite, and cuprite may be found in the solid phases, and the same may occur if the FeT / CaO ratio is too high. When the FeO content is too low, and especially when the FeT / CaO ratio is too high, copper ferrite CuFeO 2 and a complex ferrite containing both CaO and C 2 O 3 are formed. Small amounts of metallic copper can also be detected in slowly cooled slags. It has been found that the silica content of the lime slag should be carefully controlled 35 and preferably kept as low as practically possible. In any case, the silica content of the slag must be less than 5% by weight and preferably less than 2.5%. The reason for limiting the silica in the slag is that the silica, even in small amounts, crystallizes as dicalcium silicate Ca 2 SiO 2, which silicate formation takes precedence over the formation and crystallization of Ca 2 Fe 2 O 3. As a result of the primary formation of Ca 2 SiO 2, dicalcium ferrite may not be obtained at all because one unit of weight of silica is associated with almost two units of weight of lime, and therefore

Crystallization of Ca 2 SiO 2 leads to considerable wear of the slag matrix for lime, thus making crystallization of Ca 2 Fe 2 O 3 impossible. Wear also means an increase in the FcT / CaO weight ratio of the slag, which in turn leads to the formation of non-magnetic phases containing iron, calcium and copper, other than the dicalcium ferrite and cuprite described above. However, the alumina contained in the slag does not change the phase composition of the slowly cooled slag, as long as the alumina-20 content remains below 5% by weight because it crystallizes into spinel and other ferrites isomorphically with Fe 2 O 2.

Thus, it follows from the above that the non-magnetic fraction contains, at room temperature, mainly 25 dicalcium ferrite, cuprite and small amounts of metallic copper. When this fraction is returned to the converter, dicalcium ferrite acts as the main lime-containing flux required for conversion. The copper contained in the non-magnetic fraction, which is mainly copper, is also returned directly to the converter, making it unnecessary to produce this copper oxide, as one of the main constituents of the lime-ferrite slag, from the metal rock fed to the converter.

As most of the lime and copper is recovered from the 35 slowly cooled slags and returned to the 8,73741 conversion furnace, the operation of the melting furnace becomes independent of the conversion stage, the total amount of smelting furnace slag decreases, the consumption of fluxes required for the conversion stage as well as the smelting stage .

As will be appreciated by those skilled in the art, the amount of spinel formed during the slow cooling of the slag is controlled primarily by the FeO content of the slag.

It has been found that the amount of iron converted to spinel can also be controlled by adding small amounts of MgO to the liquid slag. The solubility of MgO in copper oxide-containing lime-ferrite slag has been found to be well below 1% by weight at the conversion temperature. Upon addition of magnesium oxide to the liquid slag, a solid solution of magnesium ferrite and iron ferrite forms primary spinel crystals of MgFe 2 O-Fe 2 O 2.

These crystals may tend to separate from the slag and settle, and thus good mixing of the slag is desirable to keep the spinel precipitate suspended. By adding MgO in amounts of about 1-3% by weight of the slag, the desired results are obtained. Dolomite is the most suitable source of MgO to be added. In the converter, the spinel crystals obtained by the addition of MgO can contain up to 10-30% of the total iron contained in the slag. Lime-ferrite slag is sufficiently fluid despite the solid particles suspended in it.

As is known, copper rock may in some cases contain more than about 0.5% or 1% by weight of nickel. It is desirable that this nickel be recovered in a marketable form and separated from the crude copper, as it may have undesirable effects in the anode furnace and subsequent electrolytic purification. It has been found that the solubility of the nickel oxide formed in the conversion in calcium ferrite slag 9,73741 is low. For example, at 1250 ° C, the solubility of NiO in liquid slag (in the absence of primary Spinel may be 1% by weight of said slag. At higher concentrations, nickel oxide forms the same types of ferromagnetic, primary spinel crystals suspended in liquid-like slag as Mgg. and NiO is present, the ferromagnetic Spinelli is essentially a solid solution of three components, iron, nickel and magnesium ferrite (Fe 2 O 2, NiFe 2 O 4 and MgFe 2 O 2).

When cooling the slag slowly, nickel accumulates to an increasing extent in the spinel phase, where it may be present at about 5-15%, while the nickel concentrations in the non-magnetic phases are much lower. For example, dicalcium silicate and dicalcium ferrite usually contain less than 0.1% and 0.5% nickel, respectively, whereas monocalcium ferrite and some other ferrites may contain up to 0.5-1.0% nickel.

The great advantage of the invention is that the lime-ferrite slag used in the converter can be recycled in a closed circuit in the converter. Lime-ferrite slag forms the way to separate iron and nickel from the metal rock fed to the converter. In addition, the accumulation of iron and nickel in the low magnetic phase with a low lime content allows the recovery of almost all the lime in the slag leaving the converter in the non-magnetic phase. This contributes to the economics of the process, as only additional amounts of lime or dolomite are needed to slowly return the non-magnetic fraction of the chilled slag to the converter.

Moreover, the fact that the alkaline slag from the converter can be treated in a closed circuit containing the converter means that the melting furnace can be independent of the requirements of the converter itself. Since 35 slag does not need to be returned from the converter to the melting furnace, the conditions in the melting furnace can be controlled independently of the converter. This means that, in general, smaller amounts of slag are generated in the smelting furnace and the smelting step can be autogenic, leading to a significant reduction in the energy content of the entire raw copper production process. In some cases, it may be found advantageous to recycle part or even the entire fraction back to the melting furnace, especially when it is autogenous. The separation of the power-10 of the melting furnace and the converter is a significant practical advantage, since interference in one stage does not necessarily lead to interference in the other.

The following are examples.

Example 1 1400 tonnes per day of sulphide material containing 32.4% by weight of Cu, 1.35% by weight of Ni, 30.1% by weight of Fe and 33.4% by weight of? S, in an oxygen flame melting furnace, and autogenous flame melting was performed by adding 285 tons per day of quartz powder as well as 112 20 tons per day of unmagnetized fraction containing 31.0 wt.% Of Cu, 0.5 wt. -% Fe, 23.5% by weight CaO and 2.2% by weight SiO2;

The final molten products of the concentrate smelting are: 740 tonnes of discarded silicate slag 25 and 875 tonnes per day of metal stone with the following composition, as a percentage by weight:

Cu Ni Fe s SiO 2 CaO

metal rock 54.8 2.1 18.4 23.4 0.35 30 slag 078 0.13 39.5 1.4 32.0 4.0

The molten metal rock is then converted on a continuous basis and autogenously using oxygen-rich air (30% O 2) and adding 208 tonnes per day of the non-magnetic fraction of the above composition and adding 40 tonnes per day of the additional 11,73741 lime required for concentrate to replace the CaO contained in the non-magnetic fraction recycled to the flame melting furnace and the CaO contained in the magnetic fraction. Continuous conversion results in 436 tonnes of crude 5 copper and 550 tonnes of lime ferrite slag per day, and their compositions, in weight percent, are as follows:

Cu Ni Fe S CaO SiO 2, MgO

crude copper 98.1 0.5 0.02 0.2 10 lime-ferrite slag 20.0 3.0 40.0 to 15.5 0.55 2.3

Lime-ferrite slag is slowly cooled in large molds and then crushed, ground and magnetically separated. The result of the magnetic separation is 320 tonnes per day of the above-mentioned non-magnetic fraction and 230 tonnes per day of the magnetic fraction, the composition of which, as a percentage by weight, is:

Cu_ Nj _ Fe CaO MgO SiO 2 4.5 6.5 55.0 3.5 5.0 0.20 20 x The magnetic fraction contains about 78% of the iron and 81 s of the nickel originally present in the metal rock and forms thus a very good way to remove these metals from the copper production cycle. In addition, the recycling of a certain part of the non-magnetic fraction back to the oxygen flame smelting furnace is of great advantage, as it allows the quality of the autogenous metal rock to be raised to the desired level and therefore reduces the total conversion work and lime-ferrite slag treatment work. However, if the non-magnetic fraction is not recycled to the melting furnace, the above-mentioned concentrate can be flame-melted autogenously to a metal rock having a copper content of up to about 40-45%. Continuous conversion of this metal stone, combined with 100% 35 recycling of the non-magnetic fraction of the converter slag, back to the converter produces about 1100 - ___ Τι .....

12 73741 1200 tonnes per day of lime-ferrite-converter slag. Recycling 112 tonnes of non-magnetic fractions (ie 35% of the total fraction) back to the converter results in the production of 11 i-converter slags, which is only 550 tonnes per day.

In addition, the recycling of a certain portion of the non-magnetic fraction back to the oxygen flame melting furnace of the concentrate provides the necessary way to separate the SiOn that would otherwise accumulate in the converter slag above the upper limits defined above.

In the above example, it was shown that the nickel content of the magnetic fractions can be quite high, and therefore they can be suitably treated to obtain a nickel refractive index. The following example shows that the nickel content of the magnetic fraction can be increased.

Example 2

Molten metal rock containing 63.7% by weight

Cu, 2.2 7% by weight of Ni, 11.6% by weight of Fe and 20.8% by weight of S, 20 were blown with oxygen from above and a non-magnetic fraction of 7% by weight of Cu was added. 27% by weight

Fe and 27% by weight CaC. The result was crude copper and lime-ferrite slag in a weight ratio of approximately 1: 1.

The composition of the products, in% by weight, was as follows:

2 5 C u_ Ni Fe S CaO MgO

crude copper () 9.0 0.41 0.02 - - - ka 1 month i-hot it11 - slag 34.4 3.20 27.0 0.10 12.4 1.38

The nickel was distributed so that about 88% of it was in 30 slag and 12% in crude copper. The slag was cooled slowly at a rate of about 0.5 ° C / min, from 1250 ° C to HCO 0 ° C and at a rate of about 1 ° C / min from 1100 ° C to 1000 ° C.

It was then ground and subjected to magnetic separation to give products with a composition of 35% by weight: 13,73741

Cu Mi Fe CaO MgO SiO2

Non-magnetic verse 43.0 0.81 22.3 15.3 0.36 1.56 Magnetic verse 8.82 11.6 44.4 2.71 5.14 0.28

The magnetic fraction was then re-ground and magnetically purified, and an additional batch of the non-magnetic fraction thus obtained was combined with the previous non-magnetic fraction. The final weight ratio of magnetic to non-magnetic fraction was 18.2: 81.8, respectively. The composition of these final fractions, in% by weight, was as follows:

Cu Ni_ Fe CaO MgO SiO 2 non-magnetic fraction 42.7 0.84 22.4 15.1 0.37 1.52 magnetic fraction 3.82 13.0 47.9 1.85 5.70

The distribution of the constituents among the final fractions obtained in the slag separation was as follows (o):

Cu Ni Fe CaO MgO SiO 2 non-magnetic fraction 98.0 22.5 67.7 97.3 22.6 94.7 magnetic fraction 2.0 77.5 32.3 2.7 77.4 5.3

Oxygen Flame Smelting Process i__ 20 The invention has been described above by means of a continuous conversion process n, the sulfur contained in a copper rock which can be produced using oxygen flame smelting and the oxidation of iron in the presence of molten crude copper and running lime-ferrite slag. It has also been found that the continuous production of 25 crude copper can be realized by oxygen flame smelting using solid finely divided copper rock in the form of lime-ferriite slag. In the oxygen-flame bonding process, the oxidation of iron and sulfur to form their oxides and crude copper occurs very rapidly in a high temperature flame. The separation of the raw cake pair and the lime-ferrite slag takes place in the bath at the bottom of the flame melting furnace. Slag and crude copper can be removed continuously or with limited limits, such as n n h α1 u t a a n.

The lime-ferrite slag 14 73741 separated from the crude copper is slowly cooled, crushed, ground and then separated using mineral enrichment methods such as magnetic separation to give a magnetic and non-magnetic fraction, as described above for continuous production in a crude copper converter.

The process of converting the copper concentrate to crude copper is preferably carried out in at least two separate autogenous melting furnaces using oxygen to effect combustion. In the first autogenous reactor, the copper concentrate is melted with quartz powder to form a metal rock whose copper content allows the slag to be discarded. The metal liquor is then granulated to meet the requirements of autogenous flame smelting, usually 100%, into particles smaller than 0.15 mm. The ground metal rock is then autogenously melted using oxygen and slag-forming agents in a second furnace to form crude copper and lime-ferrite slag.

20 Since the amount of metal rock produced in the first furnace can be quite small in relation to the corresponding amount of concentrate to be processed, only one metal stone flame smelting furnace may be necessary per two or even three concentrate flame smelting furnaces.

25 Example 3

Copper Cliff's copper concentrate was flame melted autogenously using oxygen and quartz powder to remove discarded iron silicate slag and metal rock containing 43.7 wt% Cu, 3.54 wt% 20 Ni, 25.6 wt% Fe , 24.4% by weight S and 0.94% by weight

SiO 2 - This metal rock was wet granulated, dried and then ground 100% to particles smaller than 0.15 mm (less than 100 mesh). Ground metal rock, mixed with added, previously recovered and recirculated non-magnetic fraction, flame retardant

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15 73741 was then melted using oxygen. The recycled material contained 17.8% by weight of Cu, 32.1% by weight of CaO, 31.0% by weight of Fe and 0.41% by weight of MgO, and according to X-ray diffraction analysis its main phase was Ca 2 Fe 2 O 4 and 5 as the side phase C ^ O. This recycled material was added in an amount of 57.8% by weight of the metal stone. The flame smelting of the metal stone was carried out in a small-scale plant, keeping the temperature of the flame room at about 1350-1450 ° C. At the end of the experiment, the only molten products in the collection hood made of magnesium oxide were crude copper and lime-ferrite slag, having the following composition, in weight percent:

Cu Ni Fe S_ CaO SiO2 MgO

crude copper 97.13 1.39 0.02 0.89 - - - 15 lime-ferrite slag 13.4 2.24 41.6 0.059 16.5 2.13 2.72 Virtually all sulfur originally present in the metal rock , with the exception of the sulfur contained in the crude copper and slag, was removed as SO 2 and quenched by washing the degassed gases with an alkaline solution.

About 75% of the nickel was divided into slag and 25% into crude copper. The slag was then cooled at a controlled rate of about 1 ° C / min. Examination of the cooled slag 25 showed that the three main phases it contained were nickel-magnesium-iron-spinel, dicalcium ferrite (Ca 2 Fe 2 O) and calcium iron ferrite (Ca ). The slag was already 30 and separated magnetically, resulting in a non-magnetic fraction and a magnetic fraction with a weight ratio of 50.6: 49.4, respectively. The composition of these fractions was as follows (% by weight): ___- ΤΓ ^ 16 73741

Cu Ni Fe CaO Mc [0 SiO 2 non-magnetic fraction 24.2 0.17 27.1 26.7 0.24 3.82 magnetic fraction 3.05 4.17 56.4 5.17 5.45 0.46 Ignoring crude copper The distribution of the essential 5 constituents among the fractions obtained in the slag separation was as follows (%):

Cu Ni Fe CaO MgO SiO 2 non-magnetic fraction 88.7 4.7 33.5 84.1 4.5 89.3 magnetic fraction 11.3 95.3 66.5 15.9 95.5 10.7 10 Example 4

The process of Example 3 was otherwise repeated under the same conditions, except that the oxygen feed rate was increased by 13% from that used in Example 3. The composition of the crude copper and lime-ferrite slag, in% by weight, was as follows:

Cu Ni_ Fe S_ CaO SiO 2 MgO crude copper 98.4 0.83 0.02 0.16 Lime-ferrite slag 24.0 2.10 36.5 0.08 15.1 1.65 2.74 00 Slow-cooled slag the study showed that the three main phases it contained were nickel-magnesium-iron-Spinelli, dicalcium ferrite, and cuprite, while the side phases were metallic copper, di-calcium silicate, and, as in Example 3, calcium-25 ferrite ferrite. The weight ratio of the non-magnetic and magnetic fractions was 64.5: 35.4, respectively, and their composition, in weight percent, was as follows:

Cu Ni Fe CaO MgO SiO2 non-magnetic fraction 29.0 0.20 28.8 20.5 0.27 2.14 30 magnetic fraction 4.20 5.99 51.6 2.99 7.66 0.26

The distribution, excluding crude copper, was as follows (%):

Cu Ni Fe CaO MgO SiO 2 non-magnetic fraction 92.6 5.8 50.5 92.6 6.0 93.8 3'5 magnetic fraction 7.4 94.2 49.5 7.4 94.0 6.2 17 73741 These examples show that, in accordance with the present invention, slow cooling and magnetic separation of lime-ferrite slags allow good recovery of the copper and lime contained in the non-magnetic fraction, while a substantial proportion of iron as well as most nickel and magnesium oxide accumulate. to the magnetic fraction. The non-magnetic fraction is suitable as a lime-containing flux, which also contains one of the main constituents of the lime-ferrite slag, copper oxide, since it does not have to be produced from the copper contained in the sulphide material to be fed. These examples also show that crude copper can be efficiently produced by flame smelting of fine solid metal rock, thereby achieving many technical, economic and other environmental benefits. On the other hand, the results of Examples 3 and 4 show that nickel and sulfur are better removed from the crude copper by lime-ferrite slag with a higher copper oxide content, and that the silica originally contained in the metal rock accumulates for the most part in the non-magnetic fraction.

It will be appreciated by those skilled in the art that this invention may be used in many ways in combination with some other processes. For example, the metal rock first obtained from the smelting furnace can first be partially converted into quartz powder, and the iron silicate slag thus produced can be recycled back to the smelting furnace. The copper- and nickel-rich secondary metal rock can then be treated in accordance with the present invention as described in Example 2 above. In this case, the primary concentrate smelting step may also be autogenous, after which the metal rock is converted using quartz powder to a complaint metal rock, which is converted on a continuous basis according to the present invention, while the iron silicate 35 can be recycled hot or cold ( granulated), which further helps to improve the quality of the metal rock in the primary concentrate smelting.

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Claims (8)

A process for making blister copper on continuous base from ferrous and sulfur-containing copper stones, characterized in that the process comprises the following steps: a) converting copper, sulfur and iron into the blister with oxygen to blister copper, sulfur dioxide and iron oxide; b) feeding a flux which is a mixture which mainly consists of ethereal dicalcium ferrite and copper oxide and which in addition also contains a calcium-containing melt-promoting agent, the total weight ratio (Fe: CaO) between iron and calcium oxide flux mixture -ing is substantially below 7; C) converting the iron oxides with the flux mixture to a copper oxide-containing slag on the lime ferrite base, the total weight ratio (Fe: CaO) of iron to calcium oxide in the slag being more than about 2 but less than 3; d) separating the slag from the blast copper; E) casting and slowly cooling off at least part of the slag, crystallizing: (1) a ferromagnetic oxide rich in iron and poor in calcium and copper, and (2) non-magnetic oxides including dicalcium ferrite and copper oxide and other non-magnetic phases; F) decomposing the crystallized slag and separating it (1) into a magnetic fraction mainly comprised of the ferromagnetic oxide, and (2) to a non-magnetic fraction containing most of the calcium and copper in the slag. on lime ferrite base; and g) regenerating the at least part of the non-magnetic fraction for use in the flux mixture. 2. A method according to claim 1, characterized in that the conversion and slag formation are carried out by feeding the cutting stone, oxygen and the flux mixture into molten blister cups.