CA1044470A - Process for recovering cobalt - Google Patents

Abstract

A PROCESS FOR RECOVERING COBALT

Abstract A process is described for recovering cobalt as cobalt sulfate solution from low-grade cobalt-containing materials. The process comprises (a) reductively smelting oxidized cobaltiferous material rich in iron to extract cobalt as an alloy by selective reduction of oxidized cobalt in preference to oxidized iron, (b) converting the cobalt and iron in the alloy into sulfate by treating the alloy with copper sulfate and water, (c) calcining the resultant mixture containing the sulfates to decompose the iron sulfate selectively into oxide, and (d) leaching the resultant calcine with an aqueous medium to extract cobalt as cobalt sulfate solution, leaving iron as a leach residue.

Description

The invention relates to a process for recovering cobalt from low-grade cobalt-containing materials.
Cobalt can occur in nature as a minor constituent in copper ore. It is sometimes recovered as cobalt concentrate through differential floatation, but its economical recovery is often difficult, and it is lost as waste along with iron as copper smelting slag.
~ part of the cobalt is extracted into matte in copper smelting, extracted into converter slag along with iron, and reverted to the primary smelting. It is eventually lost as waste in the slag from the primary smelting. An example of commercial extraction of cobalt is well-known in which a slag as rich as 5 - 10% Co was produced which was reductively-smelted to recover an ` alloy containing 15% Cu, 40% Co, and 45% Pe. However, the slag was produced from copper concentrate and cobalt concentrate of especially high cobalt grade, such as ; 0.7% Co and 2.8% Co. Recovery of cobalt was very low, for slags as rich as 0.46% Co and 0.77% Co, for example, -` had to be dumped in large amounts.
` The high grade cobaltiferous alloy was dis- -solved, in the said example, with sulfuric acid, iron - -was eliminated as voluminous precipitate by neutralization, and cobalt was finally recovered through precipitation. -However, when cobalt is to be recovered from a low-grade ~-q-coba~t-containing material, it is quite uneconomical -~ commercially to eliminate iron that is present in an amount nearly five times that of cobalt by such a process.
It i9 one of the commercial operations to ,, .

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sulfation-roast cobalt concentrate, separated from cobaltiferous copper ore, for example, and extract cobalt sulfate as leach solution. Iron can be converted into oxide while cobalt is converted into sulfate through sulfation-roasting, and iron can easily be separated from cobalt by leaching. However, cobalt cannot be sulfated through sulfation-roasting of an alloy. Besides, cobalt concentrates usually contain large amounts of copper which is leached out along with cobalt as sulfate. The copper is separated and extrac-ted through electrowinning or precipitation by neutral-ization, but this is more expensive than extraction of copper through an ordinary smelting process. Thus, electrowinning consumes a large amount of power and the copper precipitated by neutralization is highly hydrated and is expensive to smelt.
Cobalt occurs in nature in small amounts often accompanied by nickel, but it is partly lost as slag along with iron in nickel smelting. Recovery of cobalt from such slag is as difficult as from copper smelting slag.
~res containing nickel or copper besides cobalt, asbolite or manganese nodules, for example, are left unutilized. It is proposed to treat manganese nodules, for example, by preferential reductive-smelting and recover cobalt, nickel and copper as alloy; but the alloy would contain a large amount of iron which is -very éxpensive to eliminate through hydrometallurgical means as already explained with cobalt alloys.
Cobalt also occurs in nature as arsenides.
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~OA~ 7() Extraction of cobalt from arsenide minerals through elim-ination of arsenic by roasting is another difficult pro-blem in extractive metallurgy. All such processes yet developed are prohibitively expensive for commercial purposes. A process for vaporizing arsenic with chlor-ine is commercially operated, but it is also expensive.
It is well-known that arsenic can be easily eliminated when an arsenide is smelted along with a large amount of sulfide ore, but this would dilute cobalt with a large amount of iron and/or copper. This again is not economical unless some means for separating cobalt from a large amount of iron and/or copper is provided.
Accordingly, it is the general object of this inven-tion to provide a process for separating and extracting cobalt economically from low-grade cobalt-containing materials, thereby solving the said difficulties. -`
Generally stated, the present lnvention is a pro-cess for recovering cobalt from cobaltiferous copper-containing material comprising reductively smelting oxidized cobaltiferous copper-containing material rich in iron to extract cobalt as an alloy, either by itself or -dissolved in matte, through reduction of oxidized cobalt in preference to oxidized iron into metal as the first step; converting the cobalt and iron in the alloy into sulfate by treating the alloy with copper sulfate and water as the second steop; and calcining the resultant ~
mixture containing the sulfates to decompose the iron ~ --sulfate selectively into oxide, leaching the resultant calcine to éxtract cobalt as cobalt sulfate solution, and leaving iron as leach residue as the third step.
It is desirable to extract cobalt with a : ',, ' "' , , ', ' ,,', "' "` '.', ' ' ' ," i '"" ' ' " ' ' .' " ' ' ' ` " ';' 11~)44~70 minimum of iron accompanying into al~oy in reductively smelting oxidized cobaltiferous material rich in iron, such as cobaltiferous copper smelting slag. However, it is difficult to prevent a small part of the iron~ which still can be much greater than the amount cobalt, from entering into the alloy and hindering the recovery of the cobalt.
Copper or nickel, but not cobalt, can effectively be separated from a large amount of iron as matte in smelting of raw material. However, a still larger amount of iron than that in the alloy would accompany cobalt if extracted as matte. Therefore, it --is necessary to extract cobalt as alloy. It has also -been found that cobalt can be extracted into an alloy dissolved in matte as effectively as into a free alloy, i.e. an alloy not dissolved in matte.
Accordingly, cobalt is extracted as a free alloy or an alloy dissolved in matte from an oxidized cobaltiferous material rich in iron as the first step of -the present process.
Since production of a free alloy, through i smelting of an oxidized cobaltiferous material with addition of a limited amount of reductant, for example, . -i8 a well-known process, the following explanation will be directed to the production of an alloy dissolved in matte.
A copper smelting process is usually an oxidizing process and the resultant matte consists, especially when it 18 rich in iron, of sulfides and oxldes and does not contain metallic iron. However, ~q7 ., ". , . , , , , ", ", ~,, , ,, . ,` , ~

~04~70 under more reducing conditions, a matte can be produced that contains metallic iron and metallic cobalt to a considerable extent. Therefore, molten converter slag may be fed onto a bath of molten copper matte with addition of a reducing agent, carbon and~or metallic iron, for example, with heating and agitation. Hest may be applied electrically, or chemically by addition of calcium carbide or ferro-silicon, for example, when other reducing agents may be dispensed with. Magnetite and oxidized cobalt in the slag, and a part of the ferrous oxide depending on the case, are reduced. The resultant metallic cobalt and metallic iron are dissolved into the bath of matte. Since the amount of alloy extracted from a batch of slag is small, the treated slag is discharged to treat the next batch of slag and this is repeated.
It is, of course, desirable to stop the treatment before ~:;
the limit of the matte's ability to dissolve metallics is reached.
The alloy dissolved in matte can be separ-ated by carburizing the mixture in the molten state, by pouring the mixture through a column of red hot lump coke, for example, where a free alloy settles at the bottom while the mother matte stays at the top. The , alloy contains most of the cobalt in the original mixture while the mother matte contains most of the copper, and `~ -the latter may be reverted to the said treatment of the slag or to the converter to be bessemerized to extract copper as metal and cobalt as slag again.
The free alloy produced by any of the above `
mentioned procedures is granulated, e.g. by running into ~6)4~47~
water. A large excess of the alloy is treated with copper sulfate and a small amount of water, e.g. in a tumbler, to convert metallic cobalt and metallic iron in the alloy into sulfates and the copper in copper sulfate into cement copper. The resultant slurry is separated from the remaining alloy which is further treated in the following batches.
The resultant slurry is filtered to separate the cement copper and the resultant filtrate containing sulfates may be evaporated. The resultant mixture of sulfates may be calcined by well-known means so that the iron sulfate is decomposed into oxide while cobalt sulfate is kept intact. The calcine may be leached with water, and cobalt is extracted as cobalt sulfate solution while -iron is separated as leach residue. -Alternatively, the solution containing sul-fates of cobalt and iron may be roasted along with ore containing a large amount of iron sulfide for evaporation of water and calcining of the mixed sulfates. This opera-tion may be combined with recovery of cobalt fromcobaltiferous pyrite by roasting and leaching.
The copper sulfate for treating the alloy can be used as a concentrated solution, a leach solution from sulfation roasting or leaching of sulfide copper concentrate. Since cobaltiferous pyrite concentrate often contains a considerable amount of copper, the copper obtained by roasting and leaching can be used as a part of copper sulfate for the purpose with advantage.
The alloy dissolved in matte is brittle on coollng and can be comminuted to be treated with nearly lQ4447~
the stoichiometric amount of copper sulfate for the cobalt and iron in the alloy along with a small amount of water. The resultant slurry may be filtered, and the filtrate may be treated similarly to the said treatment of the solution of sulfates.
The solution of cobalt sulfate produced by the present process contains iron in a small amount, and it contains also copper if it is produced by roasting and leaching along with cupriferous pyrite. The iron, or iron and copper, if any, may be precipitated, with addition of milk of lime, for example, as basic salt to be separated by filtration; and the cobalt may be recov- , ered by well-known means.
The resultant precipitate of basic salt of copper may be dissolved with sulfuric acid into copper sulfate solution which may be used for treating the alloy. It is desirable to use a small amount of sulfuric acid in order to enhance extraction of copper in leaching cupriferous calcine and a part of the acid remains uncon-sumed in the resultant leach solution containing copper `~
sulfate; and the remaining acid may be utilized for the purpose. -The present process may be used in combina-tion with a copper smelting process for recovering cobalt from the slag resulting from smelting of cobaltiferous material along with cupriferous material. The inter-mediate cupriferous products produced from the present process, the cement copper or the mother matte remaining after dissolving the accompanying alloy into aqueous solution, for example, can easily be treated by simply ~i' .
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1~)44470 reverting them to copper smelting; and the cobalt con-tained in the intermediate products can be extracted by applying the present process again to the resultant cop-per smelting slag. Thus a high overall recovery of cobalt can be expected although the direct recovery of cobalt is low.
The present process can also be applied to a material containing cobalt and nickel along with a large amount of iron.
According to an alternative embodiment, nickel in the alloy can also be converted into nickel sulfate to be extracted as a mixed solution of sulfates of cobalt and nickel, if copper is not contained in the alloy. A large part of the nickel is left as leach residue in treating the alloy with copper sulfate and water if the alloy contains sufficient copper, and this effects a separation of cobalt from nickel while the copper and nickel in the residue can be extracted as nickeliferous crude copper after smelting the residue by copper smelting. Manganese nodule, for example, can -be reductively-smelted to extract cobalt, nickel and copper into alloy and manganese as slag; and the resul-tant alloy is treated to extract cobalt as cobalt sulfate solution and nickel and copper as leach residue. -The present process may also be applied in combination with a copper smelting process to treat a ~ -material containing cobalt and nickel and extract them separately. A material of low cobalt grade, asbolite, ~ -~
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~04~470 manganese nodule, converter slag from nickel smelting, for example, may be smelted along with cupriferous material to extract cobalt as copper matte of low cobalt grade. Sulfide, oxide, or alloy of high cobalt grade or of cobalt and nickel content may better be smelted along with copper matte to extract cobalt, nickèl and copper into matte; and the resultant copper matte is bessemer- -ized to extract most of the cobalt as slag which is treated by the present process into cobalt sulfate solu-tion and most of the nickel as crude nickeliferous metallic copper which is electrorefined to recover nickel -~
sulfate from the spent electrolyte.
The present process may also be applied in combination with a copper smelting process to a cobalti-ferous material containing arsenic for recovering cobalt.
Cobalt arsenide concentrate, for example, may be smelted along with a large amount of sulfide copper ore or copper matte when arsenic is eliminated as flue dust while cop-per is slagged off to be extracted by the present process from the slag. A small part of arsenic is extracted as slag and hence as alloy, but it is eliminated as flue dust eventually after the leach residue from the alloy -treatment is reverted to copper smelting process.
As has been explained, it is one of the advantages of the present process that a large amount of iron accompanying cobalt can easily be eliminated. This ~ -is achieved by combining the two steps for efficient separation of cobalt from a large amount of iron, i.e.
extracting cobalt as an alloy, with a more efficient ~-elimination of iron than as matte, and selective thermal ,-.

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16~4~47~) -decomposition of iron sulfate. Sulfuric acid is not required in large amounts for conversion of the cobalt and iron in the alloy into sulfates by the present pro-cess, and the iron oxide formed by the thermal decompo-sition of iron sulfate is not hydrated. Moreover, this iron oxide has a very small volume relative to the ordi-nary iron precipitate formed by neutralization in solution, and is easy to filter.
It is another advantage that copper in the cobalt concentrate can easily be recovered by treating cobaltiferous alloy by the present process in combination with ,treatment of sulfide cobalt concentrate. Copper is extracted mostly as cement copper of high grade and of a small volume to be economically smelted for its recovery, and this is achieved through utilization of the metallic -iron in the alloy to be wasted.
It is a further advantage that the economy of recovering cobalt is improved greatly by the present process through production of the copper sulfate 901u-tion required for treating the alloy from sulfide copper concentrate by sulfation roasting and leaching, for this saves not only the cost for treating the alloy but also ~ -enables one to extract copper from copper ore inexpen- -sively as a byproduct of cobalt extraction.
It is a still further advantage that cobalt associated with nickel can be separated and recovered.
It can be recovered from the slag of copper smelting or -nlckel and copper smelting as a byproduct. ~;
It is a stlll further advantage that cobalt assoclated wlth a large amount of arsenic caD be recovered a8 a byproduct of copper smelting. ~ -: ' . ' ~g7 :
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It is a still further advantage that cobalt can be recovered collectively from several minor sources as a byproduct of copper smelting. Cobalt often occurs in nature on a small scale as materials of various compo-sition which have hitherto been treated by various pro-cesses, which proved to be uneconomical, or have been left unutilized. However, the present process makes it possible to treat these materials and intermediate products there-from collectively on a large scale.
It is a still further advantage that the cost for reductive smelting for production of cobaltiferous alloy,is saved through treating molten slag by a combined process of the present process with copper smelting.
Especially, extraction of cobalt as an alloy dissolved in matte enables one to treat the slag at a lower temperature than as a free alloy.
This invention will be further illustrated by way of the following examples.
Example 1 A cobaltiferous slag from a copper converter was pulverized into a size of less than 3 mm and melted in an electric furnace with addition of powdered coke.
The resulting alloy was crushed to a size --ranging from 1 to 2 cm and cupric sulfate and water were adted thereto. The mixture was treated in a tumbler for one hour. The resulting slurry was discharged from the tumbler, and was filtered, and the filter cake and the remnant alloy were washed with water.
The filtrate and wash solution were combined to be evaporated to dryness. The resulting mixed sulfates .

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~04~70 were heated in an electric furnace at about 600C for 30 minutes. The calcined product was leached with water, filtered and the residue was washed with water to separate a solution of cobalt sulfate from the residue. The com-positions of feeds and products are shown in Table 1 to 3.

SMELTING PROCESS
MaterialAmount, Kg Composition, %
(Kg) Cu Co Fe SiO2 Co/Fe Slag from converter10 4.5 2.7 53.2 22.6 1/19 Powdered coke 0.5 Alloy, 218.611.6 58.1 1/5 Discharged slag 70.6 0.4 50.8 1/127 TUMBLING PROCESS
MaterialAmount Composition, %
(g,cc) Cu Co Fe SiO2 Co/Fe Alloy 1,200g 18.6 11.6 58.1 1/5 Blue vitriol 300g 24.8 Water 400cc ~
Precipitated copper 125g 73.6 1.2 11.2 - -.: , Remnant alloy 1,070g Solution1,000cc Trace 11.9 58.2 1/5 ,''. ' ' r, ;

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lQ44470 CALCINING AND LEACHING PROCESS
MaterialAmount Composition %
(g,cc) Cu Co Fe SiO2 Co/Fe Charged solution800cc Trace 11.9 58.2 1/5 Mixed sulfates160g Calcined product90g Water 250cc Co sulfate solution250cc Trace 32.6 2.0 1/0.06 Leach residue72g Trace 1.1 60.3 1/55 The yields in each step were calculated from these results and the overall yield was calculated as 58%.
Since iron was contained in the final solution only in an -amount of 1.9%, it is obvious that the intended separation of iron has been achieved. Because of-the small scale run with much handling loss, the yield of cobalt is unduly small. However, the total amount of the cobalt in the discharged slag as shown in Table 1 and that in the pre- '~
cipitated copper as shown in Table 2 amounted to 19% of that in the feed. This shows the importance of combining the present process with copper smelting in order to treat these intermediate products in copper smelting and to reclaim cobalt.
~xample 2 , A molten copper matte was kept in a ladle and a molten slag containing cobalt from a converter was poured onto the matte bath. Calcium carbide was added ; -to the latle, the mixture was stlrred by inserting green wood for 3 minute~ and the slag wa~ discharged. These operations were repeated 10 times by charglng fresh slag 1~)4~47~
from the converter after discharging the treated slag.
The discharged temperature of resulting slag was about 1300C.
A portion of the resul~ing mixture of matte and alloy was percolated through a column of red-hot lump coke heaped into a height of about 2 meters and the oper-ation was repeated three times by recycling the discharged mixture.
The treated mixture was poured into a number of crucibles. After cooling, the contents of the crucible were separated into tops and bottoms by impact. The bottoms alloys were combined, remelted and then granulated by pouring the melt into a deep water bath.
The alloy grains having a size from 1 to 2 cm were treated in similar procedure as disclosed in Example ;
1. The resulting filtrate had a cobaltiferous sulfide -concentrate added thereto and the mixture was heated to dryness, followed by roasting at about 600 C in a til~ing ~-rotary tube. The calcined product discharged from the tube was repeatedly charged into the tube until substantially no sulfur dioxide was liberated. The final calcinated ' product was leached with water, filtered off and the residue was leached with dilute sulfuric acid and then filtered off. The residue was washed with water. -The leach solution and wash solution were combined and added with milk of lime to precipitate ~
copper and iron. The resulting slurry was filtered off -to obtain a cobalt sulfate solution.
The precipitated copper and iron were dissolved in the acid leach solution with addition of a -~4~470 small amount of sulfuric acid to prepare cuprice sulfate solution, which was used as a part of cupric sulfate for the next tumbling process. Tables 4 to 7 show the amounts and compositions of feeds and products.

SMELTING PROCESS
MaterialAmount, Kgs Composition, %
(Kg) Cu Co Fe S C Co/Fe Copper matte1,30039.2 0.7 31.120.3 1/45 Slag from converter10,000 4.0 0.954.4 2.1 1/61 Carbide 250 Produced mixture1,800 43.8 3.731.6 17.4 1/8.6 -Discharged slag 9,500 1.1 0.352.6 1.3 1/175 Treated mixture 1,000 43.8 3.731.6 17.4 1/8.6 Top 700 57.2 0.6 15.923.7 1/27 Bottom 260 8.7 11.6 70.80.9 2.5 1/6 . . .

TUMBLING PROCESS
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Material Amount Composition, % or g/l (g,cc) Cu Co FeCo/Fe Granulated alloy 1,200g 8.7 11.6 70.8 1/6 Blue vitriol 300g 24.8 Water 400cc Precipitated copper llOg 70.6 1.3 13.2 Filtrate 350cc Trace23.0 126.5 1/5.5 Wash solutlon 200cc 8.2 45.6 1/5.5 Resldual alloy l,lOOg ':

, ~7 104~470 ROASTING PROCESS
Material Amount Composition?_~O or g/l (g,cc) Cu Co Fe S CotFe Cobaltiferous sulfide 300g 6.8 3.8 28.1 32.2 1/7.4 concentrate Filtrate 300g Trace 23.0 126.5 1/5.5 Calcined product 380g Water 600cc Water Leach solution 500cc 20.529.5 3.3 1/0.1 :
Sulfuric acid 20g Acid Leach solution 200cc 28.7 8.6 4.8 1/0.6 Wash 'solution 500cc 7.1 1.8. 1.3 1/0.8 `~:
Residue 270g 0.2 0.2 42.7 1/214 ~-TABLE 7 i, ~-TREATING STEP OP LEACHED LIQVOR
Material Amount Composition, ~ or g/l (g,cc) CuCo Fe Co/Fe Water leach solution400cc 20.5 29.5 3.3 1/0.1 Wash solution400cc 7.1 1.8 1.3 Ca (OH)2 14g ~ ~:
Co sulfate solution800cc 2.2 14.6 0.2 1/0.01 : :
Cake of Cu and Fe 6.4 0.7 1.4 1/2 -precipitate Produced 175g Treated 150g Acid leach solution140cc 28.7 8.6 4.8 1/0.6 ~:
Sulfuric acid 5g Cupric sulfate solution 240cc 53.9 8.8 11.0 1/1.2 ~.. ........ .

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1~4~4'~0 These results show that the copper and cobalt contents in the intermediate products such as the tops as shown ln Table 4 were much more than in the case of Example 1, and the importance of their treatment is far greater. It is obvious, however, that the intended separation of cobalt from iron and copper has been achieved.
Example 3 A portion of a mixture of matte and alloy obtained by the reductive smelting of converter slag in Example 2 was cooled and pulveriæed so as to pass through 100 mesh screen. The pulverized mixture had added thereto copper sulfate and water and was ground at about 70C for 30 minutes in a mortar. The ground mixture had added thereto additional water and was heated to 50C under agitation, filtered and washed with water. A solution similar to the mixture of filtrate and wash solution pro-duced from the tumbler treatment in Example 2 was obtained.
Table 8 shows the amounts and compositions of feed and products. The filtrate and wash solution were treated in accordance with the procedure as disclosed in Example 2 to prepare cobalt sulfate solution.

Material Amount Composition, % or g/l (g,cc) Cu Co Fe Mixture 200cc 43.8 3.7 31.6 Blue vitriol 215g 24.8 Water 60cc ~' Piltrate plus wash 400cc 2.6 14.2 98.7 solution Residue 220g 62.9 0.7 10.2 al Example 4 1~4~470 , A copper matte containing nickel and cobalt was melted in a tilting electric furnace with tuyères and was bessemerized at about 1300C with addition of silica sand. When most of the iron has been oxidized, the smelting operation was stopped and the content was dis-charged. Table 9 shows the amounts and compositions of feed and discharged products.

! 1, , Material Amount Composition, %
(kg) Cu Fe Co Ni S SiO2 Co/Ni Coppe,r matte20034.730.1 4.2 1.0 20.4 4/1 Silica sand 20 White metal 9566.2 7.9 2.5 1.8 19.6 1.4/1 Slag 97 3.8 50.5 5.5 0.2 16.1 27/1 ~ ~ -. ~.

Example 5 While metal having a similar composition to that obtained by Example 4 was melted in the same furnace as employed in Example 4 and was bessermiæed at about ~-1250C for about 50 minutes until the matte almost disap- --peared and the resulting slag was discharged. After the melt was bessemerized further for 5 minutes, the crude copper was discharged. Table 10 shows the amounts and compositions of feeds and discharged products. - :-' ' "'~

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MaterialAmount Composition, %
_ _ _ (kg) Cu Fe Co Ni S SiO2 Co/Ni White matte150 68.3 4.9 1.4 1.5 20.40.9/1 -.
Silica sand5 Slag 25 6.5 33.5 7 6 0 3 29.7 40/1 Blister copper 105 95 1 0 o.l 1.7 0.06/1 Example 6 The slag from the copper converter obtained in Example 4 and containing nickel and cobalt was treated in a ,similar procedure to that in Example 1 to obtain pre-cipitated copper, cobalt sulfate solution and residue containing mainly iron oxide. Table 11 to 13 show the amounts and compositions of feed and products in this operation.

SMELTING PROCESS
MaterialAmountComposition, ~ ~ :
(kg) Cu Fe Co Ni SiO2 Co/Ni Converter slag 95 3.8- 50.55.5 0.2 16.1 28/1 Powdered coke 6 Alloy 21 13.4 62.6 20.5 0.8 26/1 Discharged slag 70 0.7 47.6 0.7 Trace ~, .
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~ ' 1~44470 TUMBLING PROCESS
Material Amount Composition, ~ or &~1 (g,cc) Cu Fe Co Ni Co/Ni Alloy 1,200g 13.4 62.620.5 0.8 26/1 Blue vitriol 400g 24.8 Water 400cc Precipitated Cu 130g 72.012.9 3.6 0.4 9/1 Residual alloy 1,050g Solution1,200cc Trace 62.821.0 0.3 70/1 . . .
, ~ TABLE 13 MaterialAmount Composition, % or g/l (g,cc) Cu Fe Co Ni Co/Ni ;. Charged solution 1,000cc Trace62.821.0 0.3 70/1 Sulfate mixture 240g Calcinated product 150g ` Water 400cc j Co sulfate solution500cc Trace 0.938.6 0.5 77/1 ~ ' Residue after leached 95g Trace 62.51.7 Trace :.
- 20 These results show that the separation between S cobalt and nickel is insufficient solely by any one of procedures as shown in Example 4, 5 and 6. However, when `
these procedures are combined, cobalt sulfate solution containing nickel in a small amount can be prepared from copper matter containing cobalt an`d nickel.

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Example 7 1~ 70 A cobalt arsenide concentrate and copper matte were smelted in the same furnace as employed in Example 4 and was bessemerized at about 1300C with addition of silica sand until most of iron was slagged off. Then the bessermerization was stopped and the con-tent was discharged. A small amount of the flue dust was taken as a sample.
The slag was treated by the steps up to treating the alloy in a similar manner as in Example 1.
` The removal of arsenic was substantially complete. Table 14 and 15 show the amount and compositione of feeds and products.

SMELTING PROCESS
Material Amount Composition, %
-~ (kg) Cu Fe Co S As SiO2 f, Copper matte10036.932.2 20.6 Co Consentrate 20 9.2 10.6 12.3 20 White metal48 67.05.2 1.2 20.6 0.5 Slag 594.548.9 2.2 0.3 26.2 Flue dust 48.6 ~ Powdered coke 3 'J Alloy 1021.4 58.7 10.9 0.8 -Discharged slag50 0.6 46.2 0.3 27.3 '.
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--TUMBLING PROCESS
MateriaI Amount Composition, % or g/l (g,cc) Cu Fe Co As Alloy 1,200g 21.4 58.7 10.9 0.8 Blue vitriol 300g 24.8 Water 400cc Remnant alloy 1,050g Precipitated Cu 135g 68.9 12.2 1.1 0.7 (g/l) (g/l) (g/l) :.
Solution 1,000cc 0.2 62.1 10.6 Trace .

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Claims (15)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PRIVILEGE OR PROPERTY IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A process for recovering cobalt from co-baltiferous copper-containing material comprising:
(a) reductively smelting oxidized cobaltiferous copper-containing material rich in iron to extract cobalt as an alloy by selective reduction of oxidized cobalt in preference to oxidized iron;
(b) converting the cobalt and iron in the alloy into sulfate by treating the alloy with copper sulfate and water;
(c) calcining the resultant mixture containing the sulfates to decompose the iron sulfate selectively into oxide, and (d) leaching the resultant calcine with an aqueous medium to extract cobalt as cobalt sulfate solution, leaving iron as a leach residue.

2. A process according to claim 1 wherein said alloy is extracted as a free alloy.

3. A process according to claim 1 wherein said alloy is extracted as an alloy dissolved in copper matte.

4. A process according to claim 3 wherein the said alloy dissolved in matte is separated as a free alloy by carburization in molten state.

5. A process according to claim 3 wherein the reduc-tive smelting is effected by addition of at least one com-ponent selected from metallic iron, carbon, calcium carbide and ferro-silicon to a molten bath containing copper matte and slag.

6. A process according to claim 5 wherein the bath is heated by exothermic reactions between calcium carbide and oxidized metals.

7. A process according to claim 5 wherein the bath is heated by exothermic reactions between ferro-silicon and oxidized metals.

8. A process according to claim 3 wherein said alloy dissolved in matte is comminuted along with matte.

9. A process of claim 1 wherein the copper sulfate is a concentrated aqueous solution obtained by sulfation roasting sulfide copper ore and leaching.

10. A process according to claim 1 wherein the calcining of the mixture is effected by roasting the mixture along with ore or concentrate rich in iron sulfide.

11. A process according to claim 1 wherein copper and nickel are left in the insoluble residue in treating the alloy with copper sulfate and water, while cobalt in the alloy is dissolved and separation of cobalt and nickel is effected.

12. A process according to claim 1 wherein cobalti-ferous material is smelted along with cupriferous material and cobalt is extracted from the slag(s), produced in recovering copper, by reductive smelting.

13. A process according to claim 11 wherein cobalt is extracted as copper-rich matte which is bessemerized to extract cobalt as slag.

14. A process according to claim 11 wherein material containing cobalt and nickel is treated and nickel is extracted as nickeliferous crude copper.

15. A process according to claim 1 wherein material containing cobalt and arsenic is smelted along with sulfide cupriferous material and cobalt is extracted as an alloy while arsenic is eliminated as flue dust.