US3775099A - Method of winning copper, nickel, and other metals - Google Patents

Abstract

The invention is a process for winning nickel by treating an aqueous ammonium salt solution of nickel salts with a carbon monoxide-containing gas under reducing conditions to produce nickel carbonyl and subsequently recovering nickel therefrom. Optionally, the production of nickel carbonyl can be catalyzed, for example, by cyanide. Also, an essentially water-immiscible solvent for nickel carbonyl can optionally be employed. The aqueous ammoniacal solution is typically an aqueous ammoniacal ammonium chloride, carbonate, sulfate, hydroxide, or mixture thereof. The valuable metals associated with nickel, e.g., copper, cobalt, iron, and precious metals, are also separated and recovered by this process. The general nature of the process allows a wide variety of primary and secondary sources of nickel to be utilized by combining this process with a number of known ore-treatment steps.

Description

United States Patent [191 Coffield et al. v

[ Nov. 27, 1973 METHOD OF WINNING COPPER, NICKEL,

AND OTHER METALS [75] Inventors: Thomas H. Coffield, Orchard Lake; Kestutis A. Keblys, Southfield, both of Mich.

Related U.S. Application Data 1 Continuation-in-part of Ser. No. 717,034, Mar. 28,

1968, abandoned, which is a continuation-inpart of Ser. No. 807,987, Mar. 17, 1969.

[52] U.S. Cl 75/119, 75/103, 75/108,

75/117, 423/150, 423/143, 423/141 [51] Int. Cl C22b 3/00 [58] Field of Search 23/203 C; 75/119,

615,822 3/1961 Canada 23/203C 706,316 3/1965 Canada 23/203 C' 323,332 l/l930 Great Britain 23/203 C OTHER PUBLICATIONS Blanchard, Chemical Reviews, Vol. 21, 1937, pp. 3, 10-12.

Primary Examiner-Herbert T. Carter I Attorney-Donald L. Johnson [5 7] ABSTRACT The invention is a process for winning nickel by treating an aqueous ammonium salt solution of nickel salts with a carbon monoxide-containing gas under reducing conditions to produce nickel carbonyl and subsequently recovering nickel therefrom. Optionally, the production of nickel carbonyl can be catalyzed, for example, by cyanide. Also, an essentially waterimmiscible solvent for nickel carbonyl can optionally be employed. The aqueous ammoniacal solution is typically an aqueous ammoniacal ammonium chloride, carbonate, sulfate, hydroxide, or mixture thereof. The valuable metals associated with nickel, e.g., copper, cobalt, iron, and precious metals, are also separated and recovered by this process. The general nature, of the process allows a wide variety of primary and secondary sources of nickel to be utilized by combining this process with a number of known ore-treatment steps.

24 Claims, 9 Drawing Figures AQUEOUS AMMINE SOLN. OF METAL IONS Ni-(co) 1'o RECOVERY co CONTG GAS-i REDUCTIVE CO COMPDS IN CATALYST --b CARBONYLATION SOLN o RECOVERY MAKE-UP a RECYCLE STREAMS- METAL a RESIDUEJF ANY FIGURE I INVENTORS T. H. COFFIELD K.KELBLYS PAIIEIIIEIIIIIII21 I975 3.775.099

SHEET 2 BF 9 A VENT GAs Pi, CRUSHINGBI I DRYING REDUCING GRINDING ORE NH :23 COKE,OIL,OR

3 2 T v 02 H2O REDucING GAs AMMONIA I OxIDATIvE COOLING sTRIPPING LEACH (NoN-OxIDIzING) REsIDuE SEPARATION Nio OF SOLID SINTER PRODUCT Ni CO3 B VENT GAS MU ORE ORE REDucING COOLING- PREPARATION COKE OR OII.,REDDOING GAs NI REDucTIvE OxIDATIvE 2: RECOVERY CARBONYLATION LEACH H S 1 AIR OR RESIDUE' I 2 Co RECOVERY FIGURE 2 INVENTORS T. H.COFFIELD K.KEBLYS PATENIEDnnvzv ms SHEET 30F 9 A I COKE LATERITE CRUSH a KILN DRY SMELTING oRE SCREEN a PRE-HEAT REHEAT 29 NI Co CAST O2 BLOW DESULFURIZE FERRONICKEL WITH 2 3 B COKE LATERITE CRUSH a KILN DRY ORE SCREEN .8|PREHEAT SMELT'NG GRANULATE Ni Ni REDUCTIVE OXIDATIVE RECOVERY CARBONYLATION LEACH NH co HO RESIDUE 212 AIR OR 0 Co.- Co

RECOVERY FIGURE 3 INVENTORS I. H.COFFIELD K.KEBLYS PAIENIEDNUVZ! I975 3.775.099 SHEET I SF 9 A COKE COKE,GYPSUM,

l l LIMESTONE LATERITE CRUSH a SINTER SMELTING p ORE SCREEN BLAST FURNACE IRON-NICKEL MATTE NICKEL- AIR H RoAsT cRus a CONVERTER FLUID BED GRIND SULHDE 5mg MATTE N02 s0 CAST ANODES TO CALCINE ELECTRO WINNING CHARCOAL r L OXIDIZING NiO BRIQuETTE I ROAST a DRY REDUCE NICKEL YRONDQELLES COKE coI E,sYPsuM,

l LIMESTONE LATERITE CRUSH a SINTER SMELTING ORE scREEN NH3,CO2 H2O AIR OR 0 I AIR OX'DATIVE 1 GRANULATE coNvERTER LEACH NICKEL- z SULFIDE Nc| S0 MATTE REDUCTIVE Ni ME A CARBONYLATION REcovERY T L 00 METAL RECOVERY INVENTORS F|GURE 4 T. H. COFFIELD K. KEBLYS PATENTEDiinv 27 I975 3. 775 O9 9 SHEET 5 OF 9 NH3 AIRYOR A co o SULFIDE CRUSHBi OXIDATIVE p GRIND BENEFICDATE LEACH ORE CONCENTRATE RESIDUE COPPER J 10% Ni O CONCENTRATE 2 Cu H280 AlRl 30.7%Cu,O.5%Ni H S 4 J OXYDROLYSIS c c PPER COPPER STEAM 425 OF SOLN STI IPPING BOIL i 600 PSIG Cu s To SMELTER NICKEL A H Ni Ni amou- H Riz o fififoN oiv BR'QUETTE 2 POWDER POWDER ETTES SLURRY B 7 H2O AIR,NH3, COZIHZQ SULFIDE CRUSHB: OXIDATIVE GRIND BENEFICIATE LEACH NSIDUE METAL Ni REDUCTIVE RECOVERY CARBONYLATION- Cu 8 Co TO RECOVERY FIGURE 5 INVENTORS 'r. H.COFF|ELD K.KEBLYS PATENTEDIIIIV 27 I975 3.775.099 SHEET 8 UF 9 SULFIDE CRUSH a NICKEL FLASH r BENEFICIATE ORE GR'ND CONCENTRATE SMEVLTER COPPER J 35 Ni CONCENTRATE 0.5 A Cu 2% Cu 25 /0 CU,I.2 /o 63 /0 NI 0 8 28% Cu Cu RESIDUE 7/ 3 LEACH CRUSH a CONVERTER TO SMELTER TWO'STAGE GRIND MATTE L H2 so v II II BLACK NICKEL COBALT ELECTRO NICKEL M. M)

HYDROX'DE PRECIPITATION WINNING CATHQDES CO(0HI3 SULFIDE CRUSH BENEFICIATE FLASH ORE GRIND SMELTER lNH AIR OR 2 2 I I, Co a Cu REDUCTIVE OXIDATIVE CONVERT'ER To RECOVERY CARBONYLATION LEACH NICKEL RECOVERY NICKEL METAL FIGURE 6 INVENTORS T. H. COFF'IELD K. KEBLYS PATENTED NOV 2 7 I973 3.775.099 SHEET 7 BF 9 A CRUSH a N'CKEL TOP BLOWN p BENEFICIATE SULFIDE GRIND CQNCENTRATE CONVERTER R 0 E COPPER CONCENTRATE 27% Cu Fe(CO) NWCODI CARBONYL PREssuRE DRASTIC To FERRO SEPARATION CARBONYLATION QUENCH NICKEL SOLID Ni CO3 RESIDUES T NICKEL CAR- PRESSURE Ni,Co, C0 BONYL LEACH F SOLN PURIFICATION e COMPOSTION POWDER Cu g Fe TO WASTE SOLN.

Ni METAL SULFUR F REMOVAL UR souo PRECIOUS cu ELIECTIRO LEACH SMELTING W RESIDUES METALS l SLAG B SULFIDE CRUSH & Top BLOWN GRIND BENEF'C'ATE CONVERTER NH3 AIR OR [00 0 REDUCTIVE OXIDATIVE DRASTIC To RECOVERY CARBONYLATION LEACH QUENCH RESIDUE TO PRECIOUS METALS RECOVERY NICKEL -NICKEL METAL RECOVERY INVENTORS 7 T. H.COFFIELD K.KEBLYS PAIENTEBnuv 27 ms 3.775.099 SHIFT 8 CF 9 A Fe CONCENTRATE 60% Fe SULFIDE Ni CRUSH BENEFICIATE ROAST ORE GR'ND CONCENTRATE Cu CONCENTRATE SLOW VE R COOL CON RT SMELTE CRUSH BENEFICIATE ROAST GR'ND CONCENTRATE PRODUCT Co(OH) Cu CONCENTRATE NICKEL ELECTRO- CAST TO SMELTER METAL WINNING ANODES COKE l RESIDUE TO PRECIOUS Ni o METAL RECOVERY Ni(co) MONO REDUCE To DECOMPO CARBONYLATION SITION B SULFIDE c H a a, 223 BENEFICIATE ORE NH3 AIR 0R C0 2 OX'DATIVE CONVERTER SMELTER LEACH Cu 8 C0 REDUCTIVE NICKEL a N|cKE| METALI CARBONYLATIO TO RECOVERY N RECOVERY FIGURE 8 1 NVENTORS T. H. CQFFIELD K. KEBLEYS PATENTEDHUVZ? I975 3,775,099 -151 9 BF 9 AIR NH3 A CO2 H2O SCRAP Cu 8 Co 22w mszazimiw METAL TO RECOVERY RESIDUE NICKEL METAL 4 NICKEL RECOVERY FIGURE 9 BACKGROUND OF THE INVENTION Winning metals has been a human activity since time immemorial. Civilization has grown with this art; and it is safe to say that the production of metals is the genesis and sustenance of many aspects of modern technology. At the present time, mankind utilizes metals at a large and rapidly increasing rate. For this reason, improvements in techniques for obtaining metals have immediate interest.

The above facts are adequately illustrated by the history of copper. Mankind emerged from the Stone Age upon discovery of copper in its native form. The dawn of the Bronze Age was circa 8,000 BC. when it was discovered that this copper-tin alloy could be readily shaped into implements and weapons. Copper deposits on Cyprus were worked as early as 3,000 B.C. by the Egyptians and these deposits became the chief source of the metal for the Roman Empire. In 1556, Agricola recorded the history of copper. In 1963, world refined copper output exceeded 3,800,000 short tons.

Nickel was isolated by Cronstedt in 1751. By 1804, the properties of the pure metal were known with reasonable accuracy.

Referring to the section on copper in Kirk-Othmer Encyclopedia of Chemical Technology, second edition, volumn 6, page 131, and The Winning f Nickel, by Boldt, Jr., et al, D. Van Nostrand Co., New York, N. Y. (1967), the production of copper and nickel from ores are tedious, complex processes. Clearly, commerce could not bear the cost of such multi-step processes if these metals were not so important. A detailed discussion of all ramifications of art-known methods for the production of copper and nickel would be out of place here. It is sufficient to relate the following facts.

Copper and nickel are both present in some ores worked today. Since 1899 nickel has been refined by the Mond process which comprises reacting nickel with carbon monoxide to form nickel carbonyl and subsequent decomposition of this product to carbon monoxide and nickel. In the section on nickel in Kirk-Othmer (supra), second edition, volume 13, page 735, (739) there is described a hydrometallurgical refining process for nickel (practiced by Sherritt Gordon Mines Limited of Toronto, Canada). In this process, concentrates of pentlandite, (Ni, Fe) S are dissolved in an aerated ammoniacal solution. The nickel, copper and cobalt sulfides dissolve as ammines, with iron remaining in the residue as hydrated ferric oxide. Subsequently, copper is precipitated, and the remaining nickel solution is oxidized to destroy sulfamate. The resultant solution is treated with hydrogen at 35 atmospheres and 190C. to yield 99.9 percent nickel which is sintered into briquettes.

The Sherritt Gordon process is described in more detail in Boldt, Jr. (supra), page 299 ff. As described therein, the copper is removed from the ammoniacal solution by boiling off ammonia to precipitate cupric sulfide. The last traces of copper are removed by adding H 5. This must be done before nickel is precipitated with hydrogen, to avoid contamination of the nickel with copper.

In general, nickel and associated metals are recov-' ered and separated by pyrometallurgical, hydrometallurgical, or electrolytic refining techniques. For sulfide ores, the general operations of roasting, smelting, and converting produce a nickel matte product which is suitable for refining to pure metal electrolytically. In contrast to sulfide ore processing, the oxide ores may be more economically processed by hydrometallurgical or carbonyl processes to produce very high purity nickel. However, this is not true in all cases since one commercial operation utilizes pyrometallurgical techniques to prepare ferronickel from a laterite ore. A roasting operation decreases the sulfur content of a sulfide ore concentrate by about one-half. Previous processes have used multiple hearth furnaces, sintering machines, or fluidized bed reactors. When followed by smelting operations using shaft furnaces, reverberatory furnaces or electric arc furnaces to slag off siliceous and other oxide compounds, a typical nickel sulfide matte containing about 15 percent nickel-copper, 50 percent iron, and 25 percent sulfur is produced. This nickel-sulfide matte is then charged to a converter and air is blown through the charge to oxidize iron sulfide selectively. Usually, horizontal converters are used. Recently a process using a top-blown rotary converter in which an oxygen lance is blown onto the surface of the molten charge has been placed in successful commercial operation. The nickel sulfide matte essentially free of iron produced in the converting operation, typically contains about 48 percent nickel, 27 percent copper, 22 percent sulfur, and less than 1 percent iron. This matte is sulfur deficient and, therefore, contains a metallic phase which must be processed to separate the nickel sulfide and copper sulfide. In one process, a slow coolingstep is used whereby the sulfur deficient matte cast from the converter is cooled slowly over a period of several days. The nickel sulfide, copper sulfide, and copper-nickel metallics separate, allowing regular ore dressing operations to be used to separate the solidified matte into its components. Thus, the nickel-copper alloy is removed magnetically and the nickel and coppersulfides are then separated by flotation. The nickel sulfide can then be either sintered to provide percent nickel for direct use by steel producers, or roasted to the oxide, smelted and cast into anodes for electrorefining. Alternatively, the nickel sulfide matte can be cast directly into anodes for electro-refining.

In electrolytic refining, metallic nickel of high purity is produced. A major portion of the worlds nickel production includes this process as a last step in winning nickel. In addition, the recovery of precious metals and other elements such as cobalt is practiced. A divided electrolyticcell with a porousdiaphragm separating the anode and cathode is used in the electrolytic process. The diaphragm prevents impure anolyte from directly contacting the nickel cathode starting sheet. The impure anolyte obtained by solution of the anode is pumped away from the cell to another area where impurities are removed. The nickel cathodes containing 99.9 percent nickel are removed after about l0 days operation of the cell.

In addition to the Sherritt Gordon process described above, other hydrometallurgical refining processes are commercially employed to win nickel by gaseous reduction of nickel salt solutions derived from both sultide and oxide ores. Preparatory ore-dressing treat ments provide a uniform feed for the reduction and leaching process. Leaching procedures vary depending on the particular ore treated. However, the nickel carbonates produced from the aqueous solution are calcined to marketable nickel oxide, or further sintered to upgrade the nickel metal content to about 88 percent. A process to recover nickel and cobalt from a limonitic-type laterite ore from Cuba treated the ore with sulfuric acid at elevated temperature and pressure to dissolve nickel and cobalt preferentially. The iron remained essentially undissolved. The liquid separated from the residue contained 95 percent of the nickel found in the ore. After further purification of the aqueous phase, the nickel sulfate is reacted with hydrogen at high pressure and at about 190C. to recover most of the nickel as a 99.8 percent pure product.

Nickel is also produced in the form of ferronickel and nickel rondelles. Ferronickel is produced by a pyrometallurgical process of melting, reduction, and refining. One commercial process in New Caledonia reduces the ore with coke in electric furnaces. Another commercial process in Oregon involves mixing molten ore with ferrosilicon and crude ferronickel. By pouring the molten materials back and forth in special ladles, the molten ore is reduced and the resulting ferronickel product contains about 48 percent nickel. This crude product is further refined to lower the impurity level. Nickel rondelles are produced by reacting the ore with coke and gypsum in blast furnaces, blowing the nickel-iron matte and a siliceous flux with air and converting to produce a low-sulfur nickel matte, roasting to the oxide, grinding, compacting, and reducing to the metal with charcoal. The resulting nickel rondelles contain 99 percent nickel.

Data on the reduction of copper (II) salts with carbon monoxide has been published; Byerley et al., Met. Soc. Conf., 24, 183 (1963); Chem. Abs. 64, [3441 h (1966). Conversion of aqueous nickel to nickel carbonyl has been disclosed in Chem. Abs. 53, 12606 h (1959).

SUMMARY OF THE INVENTION Discoveries on which this invention is based are as follows:

1. The reduction of copper (II) salts to copper metal with carbon monoxide is promoted by the presence of nickel carbonyl,manganese carbonyl, or cobalt carbonyl.

2. With ammoniacal solutions of copper and nickel salts, it is not necessary to separate copper before winning the nickel.

3. Cupric salts can be reduced to copper metal simultaneously and in the same reaction zone wherein nickel carbonyl is produced from nickel (II) salts, via use of carbon monoxide or synthesis gas treatment.

4. The reduction of nickel (II) salts to nickel carbonyl with carbon monoxide is promoted in the presence of a ligandselected from cyanide, sulfide, cysteinc, and tartrate.

5. Practically complete conversion and separation of nickel, copper, and cobalt is possible by treating ammonium salt solutions of those metals prepared from an ore, an ore concentrate such as a beneficiated raw ore concentrate, a nickel-iron or a nickelsulfur matte, or a ferronickel product, with carbon monoxide or synthesis gas under conditions whereby the nickel and cobalt values are reduced to form metal carbonyl compounds, and the copper is reduced to metallic copper.

Based on these discoveries, this invention is a process for winning nickel by treating a nickel-containing solution of various metal ions with a carbon monoxidecontaining gas and forming a nickel carbonyl compound which can be easily separated from the solution and from other metal compounds or metals. Moreover, valuable metals associated with nickel, e,g., cobalt and copper, may be simultaneously converted to carbonyl compounds or reduced to the metallic state and, thereafter, be easily separated and recovered.

In part, this invention also resides in new improved processes for separation of nickel, cobalt, copper, and iron from ores (or other materials) containing these metals. Such processes are outlined below as follows.

A source of nickel, copper, cobalt, and iron, such as a sulfide-type nickel ore concentrate, is treated with aqueous ammonia and aerated. The resulting aqueous ammonia solution after removal of the precipitated iron contains nickel, copper and cobalt values as ammine sulfates. This solution is put in a reaction zone having a surface suitable for subsequent copper deposition or alternatively, the solution can be seeded with finely divided copper. In either event, the ammoniacal solution is thereafter treated with carbon monoxide or synthesis gas under pressure. As reduction proceeds, nickel ion is reacted to nickel carbonyl. This can be removed and decomposed thermally to nickel powder. During the reduction step, copper ion is reduced to the metal and deposited. The copper is removed from the reaction zone. During the reduction step, cobalt ion is reduced to the cobalt tetracarbonyl anion which remains in the solution. As such, it can be separated from nickel and copper. The cobalt can be recovered by injecting an oxygen-containing gas into the solution whereby cobalt is oxidized to hydrated cobalt oxide. It is then filtered from the solution and heated to remove the waters of hydration. After cobalt removal, the solution contains ammonium sulfate, which is isolated as a by-product.

Another process for winning nickel is to prepare an ammonium salt solution of a laterite ore by crushing and grinding the ore to a fine uniform feed of approximately constant composition, roasting the ore in a reducing atmosphere typically with producer gas, cooling the reduced ore under non-oxidizing conditions, leaching the reduced ore with an aqueous ammonium salt to solubilize nickel and cobalt. The ammonium salt solution is treated with carbon monoxide under conditions to form nickel and cobalt carbonyl compounds, each of which may be separated and recovered.

Still another process contemplated by this invention is the oxidative leach and carbon monoxide or synthesis gas treatment of a ferronickel product produced from either an oxide or sulfide ore. Recovery of nickel and cobalt proceeds as before from the carbonyl compounds produced.

A still further process for winning nickel is the oxidative leach and reductive carbonylation of a furnace or converter matte produced by conventional procedures from a convenient source of either sulfide or laterite ores. After the matte is produced, it is treated by an oxidative leach with an ammonium salt solution to dissolve the desired metals. Treatment of the resultant solution with a carbon monoxide-containing gas reacts nickel and cobalt, and if present, copper, to the abovestated forms which can be separated and recovered from the solution.

In addition, nickel may be recovered from scrap metal containing a recoverable quantity of nickel by comminuting the scrap, dissolving the nickel values selectively, using an oxidative leach with an ammonium salt solution and treating said solution with a carbon monoxide-containing gas. The nickel is reduced to a carbonyl compound and separated and recovered from the solution. Other metal values such as copper and cobalt associated with the scrap metal may also be recovered according to this process.

Nickel may also be recovered from manganese nodules found on the deep sea floor. The nodules are comminuted, subjected to a reducing roast, cooled under non-oxidizing conditions, and leached with an aqueous ammonium salt to solubilize the nickel values, as well as copper and cobalt. The solution is treated with a carbon monoxide-containing gas under conditions to form metal carbonyl compounds or the metal itself in the case of copper. The valuable metals are then recovered as previously described.

In each case, briefly described above, a promoter may be employed to accelerate the formation of the carbonyl compounds.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic representation of the production of nickel carbonyl from a solution containing nickel ions by reacting said solution with a carbon monoxide-containing gas in the presence of a catalyst.

FIG. 2 shows in Part A a schematic representation of the Nicaro process for producing a nickel oxide product from ore by a process of. drying, reducing and cooling under non-oxidizing conditions, leaching the reduced ore, stripping ammonia from the leach solution, separating nickel carbonate from the solution, and sintering to produce nickel oxide. Part B of FIG. 2 represents the combination of a Nicaro process with reductive carbonylation wherein the schematic representation shows a reductive carbonylation step after the oxidative leach with subsequent metal recovery.

FIG. 3 shows in Part A the preparation of ferronickel from a nickel ore by smelting the ore,'desulfurizing the molten ore with sodium carbonate, blowing the desulfurized melt with oxygen to produce a ferronickel product. Part B shows the combination of the smelting operation with an oxidative leach and reductive carbonylation and recovery of nickel metal instead of the ferronickel product.

FIG. 4 is a schematic representation in Part A of the production of nickel rondelles from a nickel sulfide matte. In this process after a laterite ore is sintered and smelted in a blast furnace, the blast furnace matte is converted to a nickel sulfide matte by blowing with air. The converter matte is then roasted in a two-stage process to nickel oxide briquets which are then reduced to nickel rondelles. Part B shows a schematic representation of a process combining the nickel sulfide matte process with an oxidative leach solution and reductive carbonylation to produce nickel metal.

FIG. 5 is a schematic representation in Part A of the Sherritt Gordon process for obtaining nickel briquets from a sulfide ore using a hydrometallurgical process. Part A shows the beneficiation of a sulfide ore and oxi dative leach of the nickel concentrate produced with subsequent copper removal and oxydrolysis of the nickel to nickel sulfate. Reduction of this solution with hydrogen produces a nickel powder which is dried and briquetted. Part B of FIG. 5 represents the combination of the Sherritt Gordon process with reductive carbonylation wherein reductive carbonylation is carried out on the leach solutionand nickel metal is recovered.

FIG. 6 is a schematic representation in Part A of the production of nickel by a process of flash smelting a nickel concentrate, converting the molten metals to a nickel sulfide matte, leaching the matte in a two-stage process to separate nickel from copper, reacting the leach solution with black nickel hydroxide to precipitate cobalt, and electrolysis of the nickel-containing solution to produce highly pure nickel cathode sheets. Part B of FIG. 6 schematically represents the combination with reductive carbonylation of the above process wherein an oxidative leach step is carried out after either the flash smelting operation or the converting operation. The leach solution is carbonylated and nickel metal recovered.

FIG. 7 represents in Part A a schematic process for production of nickel from a sulfide ore by a process of converting a nickel concentrate in a top-blown rotary converter to produce a molten nickel sulfide 'melt which is drastically quenched in water. The granulated melt is subjected to carbonylation under high pressure, and the carbonyls are separated to produce nickel metal and ferronickel. The solid residues from pressure carbonylation are leached and purified to produce other metals. Part B of FIG. 7 shows the combination of reductive carbonylation with the top-blown rotary converter operation described above. After converting a nickel concentrate to a low-sulfur molten nickel matte and quenching, the granulated nickel matte is ox- I idatively leached and subjected to reductive carbonylation. Nickel metal is recovered.

FIG. 8 is a schematic representation in Part A of a process for winning nickel by roasting a nickel concentrate, smelting the roasted concentrate, and converting the matte produced to a nickel sulfide matte. The nickel sulfide matte is allowed to cool slowly and separates into its various metallic phases. The solid matte is again beneficiated, roasted, and smelted, and the high nickel matte is cast into anodes for electro-winning of nickel metal. In Part B, the combination of oxidative leach and the reductive carbonylation is added after the nickel is roasted, smelted and converted to produce a nickel matte. The matte is leached and carbonylated to produce nickel metal.

FIG. 9 is a schematic representation of a process for recovery of nickel metal from scrap metal. The scrap is comminuted and then oxidatively leached, subjected to reductive carbonylation, and nickel metal is recovered.

DESCRIPTION OF PREFERRED EMBODIMENTS The invention is a process for recovery and separation of nickel and metal values associated therewith derived from a sulfide or laterite source of nickel ore. The process comprises establishing a solution or slurry containing nickel and the metal values associated therewith from which iron has been removed and contacting said solution or slurry with a carbon monoxidecontaining gas to form carbonyl compounds of the metal values. The nature and properties of the carbonyl compounds allow easy and complete separation of the metal carbonyl compounds from the solution or slurry.

As a convenient source of metals for the process of this invention, materials rich in nickel such as sulfide or laterite ores and the processed materials derived therefrom such as concentrates, mattes, and leach solutions, and scrap metal, and ocean nodules may be treated. The treatment of the source of nickel and metals associated therewith is largely a matter of choice, depending upon the type of ore, its situation in the natural state, or the economics of obtaining a convenient source of metal values to be treated by the process of this invention.

Establishment of a solution or slurry from the source of ores described above can be by solubilization, selective leaching, or physical separation of metallic constituents, as for example by flotation. In short, any art recognized method of obtaining a solution or slurry of nickel and associated metals may be used to prepare a solution or slurry suitable for subsequent carbonylation. The concentration of metals in the solution or slurry may vary widely. Indeed, any concentration conveniently obtained may be used to produce nickel and associated metals by the process of this invention. Diluted solutions, saturated solutions, or super-saturated solutions, for example slurries, may be used in the separation and recovery of nickel and associated metals in this process.

Any means which the art has recognized as sufficient to dissolve nickel and its associated metals may be used to prepare a solution or slurry of said nickel and associated metals. The only requirement is that the nickel be in a form that has at least some water-solubility or that it is rendered soluble by the action of a coordinating agent such as ammonia. The anion associated with the nickel is not critical. For example, the nickel may be in the form of the water soluble nickel salts such as nickel acetate, nickel ammonium chloride, nickel ammonium sulfate, nickel bromide, nickel chloride, nickel fluoride, nickel iodide, or nickel sulfate. The nickel may be in a normally insoluble form which is rendered at least partially soluble by an agent such as ammonia. These nickel compounds would include nickel carbonate, basic nickel carbonate, nickel oxide, nickel phosphate, nickel hydroxide, and the like.

The aqueous reaction media may be water or watercontaining an ammonium salt. The function of the ammonium salt is to at least partially solubilize the nickel compound. Useful ammonium salts include ammonium chloride, ammonium carbonate, ammonium sulfate, ammonium phosphate, ammonium bromide, ammonium iodide, ammonium phosphite, ammonium sulfite, ammonium cyanide, ammonium fluoride, ammonium sulfide, and the like, including mixtures thereof. The reaction media may also be aqueous ammonium hydroxide.

The concentration of the ammonium salt solution is not critical. As stated above, it is not even required when the nickel compound has some water solubility. When required, a preferred concentration range is from about 0.1 wt. up to a saturated ammonium salt solution. In general, good results are obtained using a 2-20 wt.% aqueous ammonium salt solution. A most preferred range is from about 3-10 wt. ammonium salt.

Most preferred aqueous reaction media are ammoniacal ammonium salt solutions. These are solutions of ammonium salts such as the above containing dissolved ammonia. The amount of excess ammonia can range up to complete saturation of the aqueous media. A preferred amount of ammonia is from about l-40 wt. NH A more preferred range is from 2-20 wt.% NH;,, and a most preferred NH concentration is from about 2-10 wt.%.

The amount of ammonium salt in the aqueous reaction media should be at least sufficient to provide on an equivalent basis an amount of anions equal to the amount of metallic nickel, copper, or cobalt present. Preferably, the amount of anions provided by the ammonium salt should be in excess of the equivalents of metallic nickel, copper, or cobalt present. A useful range based on the equivalent of nickel, copper, and cobalt present is from stoichiometric to about equivalents of anion per equivalent of the above metals. It is apparent from the above, for example, that a low sulfur matte will require more ammonium salt in the aqueous reaction media than a high sulfur matte because it will contain more metal inthe metallic state requiring more anions to be supplied by the ammonium salt to dissolve or leach the matte into solution.

When the nickel is at least partially dissolved, the resultant solution or slurry is treated with a carbon monoxide-containing gas. An amount of the carbon monoxide-containing gas at least sufficient to combine with nickel and its associated metals is introduced into the solution by a wide variety of methods. The particular method of introduction is not critical. The only requirement being that intimate contact of the solution and carbon monoxide-containing gas is established. A preferred carbon monoxide-containing gas is carbon monoxide. However, synthesis gas, a combination of hydrogen and carbon monoxide, may also be used. A preferredmethod of treating the solution is to introduce the carbon monoxide-containing gas under superatmospheric pressure. Pressures of carbon monoxide from 50 to about 3,000 psig. may be employed. A preferred rane of carbon monoxide pressure is from 50 to about 1,800 psig.

One skilled in the art will readily see that pressure is not an entirely independent variable but depends upon the system being treated. That is, the type of ore and the type of salt solution will affect the pressure required to carry out efficient carbonylation.

Temperatures at which the carbonylation process is can'ied out are those which facilitate a desirable rate of reaction and also allow convenient processing equipment to be utilized. Temperatures depend on the type of feed and the aqueous reaction media used in the carbonylation process. Thus, the temperature is in many instances dependent upon the pressure, feed and rate of reaction desired. A general range of temperatures under which carbonylation can be carried out are from 50 to about 250C. A preferred range of temperatures is from about 100 to about C.

It has been found that the reaction of the carbon monoxidecontaining ammoniacal salt solution is accelerated in the presence of certain promoters. The method by which such acceleration takes place is not fully understood. However, the rate of carbonylation is markedly increased by addition of certain promoters. It has been found that such promoters are ligands selected from alkoxide anions, organic acid anions, inorganic acid anions, and inorganic anions. A preferred group of ligands found to be useful in promoting the carbonylation process are cysteine and tartrate, sulfide and cyanide. A preferred promoter ligand is cyanide ion. The manner of introducing the promoter into the reaction medium is not critical and the only requirement is that the catalytic species be soluble in the reac tion medium. A preferred amount of the promoter or catalyst ligand is a catalyst-to-nickel ratio of 0.0l1 mole of promoter per mole of nickel. A preferred range is from 0.010.5. It should be'understood that the particular catalyst concentration useful in the process of this invention depends on the reaction system employed and the feed material being carbonylated.

The duration of the reaction is a function of the system being carbonylated and may vary depending on the pressure, temperature, the type of feed, and the solubilizing agent and the use of a catalyst. Under the broad range of conditions employed, carbonylation reaction times of up to about ten hours have been noted. However, under preferred conditions, the reaction is essentially completed after about two hours. In fact, the major portion of the reaction is completed within the first one-half hour when a catalyst is employed. Completion of the reaction is shown by a sharp decrease in I rate of pressure drop in the reaction vessel. It should be understood that the reaction time is not a completely independent variable and can be varied according to reasonable requirements of the individual reaction system.

In a preferred process, the nickel and associated metals, after being taken into solution, are carbonylated in an ammonium salt solution. A most preferred embodiment is the use of an aqueous ammoniacal ammonium carbonate solution wherein ammonia and carbon dioxide are added to an aqueous media which is used to leach the nickel and associated metals from their source material. In general, the solutions use a ratio of ammonia-to-metal in the ammonium salt solution of from zero to 1 to about 100 to 1 moles of ammonia per mole of metal. A preferred amountof ammonia in such a system is from to 50 moles of ammonia per mole of metal in the solution. A most preferred range is from 0 to 10 moles of ammonia per mole of metal in solution.

The nickel carbonyl formed by the reaction of the carbon monoxide-containing gas and the nickel may be separated from the reaction solution by taking it up in a water-immiscible, substantially inert solvent for nickel carbonyl or by sweeping out the reaction vessel with additional carbon monoxide-containing gas. The exact nature of the solvent is not critical so long as it is immiscible with water, dissolves nickel carbonyl, and is substantially inert under the reaction conditions. In a preferred embodiment, a solvent less dense than water is used. Nickel carbonyl is soluble in many organic solvents such as paraffins, mixtures thereof, benzene, toluene, and carbon tetrachloride. Preferred solvents are paraffin fractions such as ligroin, gasoline, kerosene, and paraffinic materials such as cyclohexane, heptane, octane, nonane, and the like. Normal or branched chain paraffins can be used as well as mixtures thereof. A most preferred solvent is a saturated aliphatic hydrocarbon such as hexane, heptane, octane, nonane, decane, dodecane, their branched chain derivatives, mixtures of these, and the like.

The amount of solvent which is used is not critical. It is only necessary to use the amount of solvent required to dissolve the desired amount of nickel carbonyl. There is no real upper limit on the amount of organic solvent, this being defined by such considerations as economics, size of the reaction vessel, ease of separation of nickel carbonyl therefrom, and the like. Generally from 0.1 to 2 volumes of organic solvent are used per unit volume of aqueous reaction media. Preferably from 0.1 to 0.5 volumes are employed.

As stated above, the nickel carbonyl may also be separated from the reaction media by passing a carbon monoxide-containing gas through the solution, allowing the nickel carbonyl to vaporize into the carbon monoxide-containing gas. When the reaction is completed, nickel carbonyl is present both in the vapor phase above the reaction solution and dissolved in the solution itself. As the pressure is released, the vapor phase containing the carbon monoxide-containing gas and vaporized nickel carbonyls is vented to a nickel carbonyl recovery zone, for example, a thermal decomposition zone. Additional carbon monoxide-containing gas is introduced through the solution and nickel carbonyl vaporizes into the gas and it is passed out of the reaction vessel into the recovery zone. Thus, substantially complete removal of nickel carbonyl is obtained. The carbon monoxide-containing gas used to sweep out the nickel carbonyl may be the same as that employed to react with the nickel. As stated above, preferred carbon monoxide-containing gases are carbon monoxide and synthesis gas. The amount of sweep gas is not critical and depends on the reactor size, temperature, and pressure of the system. Generally, from about 1 to 1,000 volumes of the carbon monoxide-containing gas is sufficient.

Referring again to the drawings, FIG. 1 is a schematic representation of the general process of this invention. The block labeled reductive carbonylation represents a suitable reactor in which the process is carried out. Any convenient reaction vessel may be utilized within the limitation of sound engineering and economic principles. A feed of aqueous ammine solution containing metal ions; e.g., nickel, copper, cobalt, and the like, is charged to the reactor. Catalyst (e.g., cyanide ion) is added and the reactor is pressurized with a carbon monoxide-containing gas. Any recycle stream containing recovered metal ions from the solution or residue, if any, or additional ammine solution required will be deposited in the reactor and can then be recovered. If other impurities in the solution are presenna residue may form and the copper must be separated therefrom.

This general process can be varied as appreciated by one skilled in the art, without departing from the scope of the invention. For example, as described above, a solvent for nickel carbonyl may also be added to the reaction mixture. lts purpose is to selectively solvate the nickel carbonyl formedand provide a means for removing it from the system. The reaction may also be run on a continuous basis with appropriate modifications for maintaining the pressure, temperature and reaction rate. In such a case, the reaction solution withdrawn must be processed to remove unreacted metal ions and recycle them to the reactor if required.

The process is further illustrated by the following examples. All parts are by weight unless otherwise stated.

EXAMPLE 1 A glass lined rocking autoclave was charged with 5.0 g. of copper sulfate pentahydrate, 5.25 g. of nickel sulfate hexahydrate, 21 ml. of concentrated ammonia, 25 ml. of water, and ml. of heptane. The autoclave was pressured with 640 psig. hydrogen and 1,200 psig. carbon monoxide, then heated 2 hours at 150C.

The resultant mixture consisted of a colorless heptane phase, metallic copper, and a light blue aqueous solution. The heptane phase was siphoned off and combined with subsequent heptane extracts of aqueous phase. The nickel carbonyl and heptane solution was treated with excess bromine in carbon tetrachloride. The resulting mixture was filtered, washed with carbon tetrachloride and dried. This gave 2.55 g. of nickel bromide. This corresponds to a 58 percent yield of nickel carbonyl based on starting nickel sulfate.

The copper metal was filtered, washed and dried in vacuo, yielding 0.90 g. of copper metal. This corresponds to a 71 percent yield based on starting copper sulfate.

This example illustrates that cupric salts present in an ammoniacal aqueous solution can form metallic copper in the presence of hydrogen and carbon monoxide even though nickel salts are present in the pregnant solution. It also illustrates that nickel (II) and salts in aqueous ammoniacal solution form nickel carbonyl in the presence of copper ammines. There is another facet to the example, Specifically, the copper metal and nickel carbonyl were separable in the absence of an overt contamination of either product; even though hydrogen gas was present in the reducing atmosphere. This example also illustrates that it is possible to extract nickel carbonyl with an essentially water-immiscible solution while reductions are taking place.

EXAMPLE 2 A pregnant aqueous solution contains in grams per liter:

nickel 45 cobalt 0.7

copper 7 ammonium sulfate 150 free ammonia 95 This solution is treated with 0.05 gram per liter of cop per powder (finely divided) and then fed into a pressure vessel. The reaction vessel is charged with heptane so that the ratio of volume of pregnant solution to heptane is 10 to 1. i

The pressure vessel is equipped with a stirrer which is activated. Then, the sealed vessel is charged with 800 psig. of synthesis gas at 175C. The vessel contents are maintained at this temperature for 2 hours. After that time, the stirrer is turned off and the vessel contents allowed to cool to ambient temperature.

Thereafter, the aqueous layer is drawn off and the copper metal removed by filtration. The filtrate is sent downstream for recovery of cobalt values and ammonium sulfate by-products.

The heptane layer is drawn off and the nickel carbonyl separated by distillation. in this example, ninetenths of the nickel carbonyl is decomposed to form nickel metal powder. The remaining one-tenth is reacted with bromine to form nickel bromide.

This nickel bromide is used to form nickelocene according to US. Pat No. 2,680,758. The nickelocene can be further reacted according to procedures in US. Pat. No. 3,054,815, to form other ogano nickel compounds. In addition, it is appreciated by a skilled practitioner that nickel carbonyl, nickel bromide, or nickelocene can be directly or ultimately used to form antiknock compounds such as those described in US. Pat. Nos. 3,086,035, 3,086,036, 3,086,037, 3,086,034, 3,086,984, 3,088,962, 3,088,963, 3,097,224, 3,097,225, etc.

The process of Example 2 can be used to treat solutions having in grams per liter:

nickel 4O 5O cobalt 0.7 1

copper 5 10 ammonium sulfate 120 180 free ammonia Likewise, solutions having greater or lesser quantities of these substituents can be so treated.

Likewise, the process of the preceding example can be used to treat concentrates having nickel 10 percent, cobalt 0.5 percent, copper 2 percent, iron 38 percent, sulfur 31 percent and rock 14 percent by leaching such a solid pentlandite flotation concentrate with aerated ammonia and then treating the concentrate with synthesis gas under conditions as set forth in the preceding example.

Similarly, the procedure of the above example can be employed using a temperature of from 100 to 250C., a H pressure of from zero to 1,200 psig., a carbon monoxide pressure of from 200 to 1,200 psig., a time of from 1 to 4 hours, an amount of organic solvent (per unit volume of aqueous solution) of from 0.1 to 2.0, said solvent being selected from ligroin, n-octane, kerosene, n-nonane, and cyclohexane.

The procedure of the above examples can be extended to recovery of Ni, Cu, Co, Fe and precious metals. Thus, a sulfide concentrate containing these metals is smelted in air in a smelting furnace. lron values can be recovered as known in the art and separated from a matte containing (some iron), nickel, copper, cobalt, and precious metals.

The matte is subjected to a pressure oxidation to yield soluble ammine sulfates of nickel, cobalt, and copper.

Iron values and precious metals are in the residue. The precious metals are recovered as known in the art. The ammine sulfates are treated as in the previous examples to recover and separate copper, nickel, and cohalt.

The use of a catalyst for the formation of nickel carbonyl is a preferred embodiment of the invention and is illustrated by the following examples.

EXAMPLES To a reaction vessel equipped with a stirrer was added 327 millimoles ammonium hydroxide (13.6 molar solution), 54.5 millimoles NiSO enough water to make a total volume of 100 ml. and then 10 ml. of heptane. The reaction vessel was closed and sealed, pressure lines were connected and the vessel flushed with nitrogen. After pressuring with nitrogen to 60 psig., the autoclave was heated to C. On reaching temperature equilibrium, the reaction vessel was pres- 4 Mmoles product found over mmoles of starting metal sulfate.

sured further to about 600 psig. with carbon monoxide. The reaction was continued for 3 hours. The total pressure drop in the reaction was 235 psi. After rapid cooling, the autoclave was vented.

The organic layer was separated. The amount of nickel carbonyl was determined by decomposition with bromine. The yield of nickel carbonyl was 30 percent. The aqueous phase contained unreacted nickel sulfate corresponding to 51 percent of the amount charged.

The following table shows effect of the addition of cyanide ion in the form of potassium cyanide, KCN. The reaction procedure is substantially the same as in Example 3 above. The various Examples 4-9 illustrate the effectiveness of the addition of a small amount of cyanide ion to the reaction mixture. Further, the catalysis by cyanide ion is not affected to any substantial extent by the presence of other metal ions.

TABLE I [Cyanide-Catalyzed Reduction of Nickel, Cobalt, and Copper sulfates] Example No.

Reaction variables:

Initial molar ratios:

NiS04 9 110 110 110 101 110 C0804 12 12 CuSO4. 27 27 KC 1 1 1 1 1 1 Total pressure drop, p.s.i 395 410 410 425 400 315 Reaction time, hrs. 1. 5 2. 2 2. 2 2. 5 3. 0 3. 0 Duration of gas uptake, hrs 0.75 1 8 1. 8 1 2.5 9 3. 0 1 3. 0 Results percent:

Recovered:

NiSO4 4. 8 1.9 1 9 2.4 8 8 30.8 C0804 3 .3 74.7 011804- 7. 6 47. 2 Conversion 4 to Ni(CO)4 90 98 98 94; 92 72 Conversion 4 to Cu metal. 63 53 1 54.5 moles of NiSO; used in each run. The metal sulfate-ammonia ratio was 1:6 in each run. Total volume of each run was 100 ml. of aqueous phase and ml. of heptane. All runs were carried out at 150 C. and 600 p.s.i. initial carbon monoxide pressure. Examples 4-9 were repressured three times back to 600 psi.

1 Gas was still being taken up very slowly when reaction was stopped.

3 The amount of cobalt found in aqueous solution.

EXAMPLE 10 The procedure of Example 9 is repeated exceptthat the molar ratio of cyanide ion to metal is 1:1. The results obtained from such a reaction are similar to those of Example 9.

Similar results are obtained when the reaction is run under a carbon monoxide pressure of 400 psi. The re- 1 action vessel may be repressured at regular intervals to maintain the carbon monoxide at about this level. Also, petroleum ether can be used for the solvent to extract the nickel carbonyl.

EXAMPLE 1 1 The reaction vessel of Example 3 is filled according to the procedure of Example 1 with 327 mmoles of ammonium hydroxide, 54,5 mmoles of nickel sulfate, 13.6

mmoles of copper sulfate, enough water to make 100 the products analyzed. The yield of neckel carbonyl is about 75 percent and about a 50 percent yield of copper metal is obtained.

Similar results are also obtained when the catalyst concentration of cyanide ion is about 0.1 mole percent based on the amount of nickel present.

EXAMPLE 12 The process of Example 3 is repeated except that cyanide ion catalyst at a concentration of about 10 mole percent based on nickel is added. The rate of nickel carbonyl formation is increased by a factor of 10, and high yield of nickel carbonyl is obtained.

Similar results are obtained in this process using nonane as the hydrocarbon solvent. Also, the addition of cyanide ion in-the form of NaCN brings similar results.

Similar results to those above are obtained when a nickel sulfide-containing ore concentrate is mixed with aqueous ammonia, aerated, and then contacted with carbon monoxide at a pressure of 600 psig. and a tempcrture of C. in the presence of cyanide ion catalyst.

EXAMPLE 13 Using the procedure of Example 3, a typical sulfide ore from Maine is concentrated by known methods to give a nickel-containing sulfide ore concentrate having the following analysis: Ni 8.75%, Fe 44.15%, Co 0.85%, Cu 0.73%, S 34.24%, insol. 5.64%, trace metal 3.36%.

This concentrate is mixed with aqueous ammonia, NH OH, and aerated according to known procedures. The aeration of the ammoniacal solution precipitates out iron as hydrated ferric oxide. Many other trace metal values are insoluble in Nl-1 OH and, after these areremoved, the Ni, Co, and Cu values are left in the ammonia leach solution as the ammonium sulfate complexes. The ammonium concentration is this solution is adjusted to give a Nl-LOH to nickel ratio of about 4:1 or 6:1 as desired.

To the solution is now added molar ratio of I I 1 10:1 NiSO :KCN, heptane to form an organic layer on top. The vessel is sealed and pressured with carbon monoxide to 1,600 psig. and the temperature is maintained at C. for three hours. When the vessel is vented, the organic layer is drawn off and the ammoniacal solution is removed. Metallic copper left in the bottom of the reaction vessel is removed from the reaction vessel. I i I I Recovery of metal values is as follows: Cu 53%; Ni 72%, (as Ni(CO) Co 74.7%,(as C080 Another embodiment of this invention comprises the discovery that nickel carbonyl catalyzes the formation of copper from ammoniacal solutions of copper ammines. THus, when treated with carbon monoxide, ammoniacal solutions of copper salts will give copper metal. When the same reaction conditions are em ployed together with nickel carbonyl present in the system the yield of copper metal is increased. This is demonstrated by the following example.

EXAMPLE 14 A glass liner of a rocking autoclave was charged with 9.99 g. of CuSO -5H O, 16 ml. of concentrated ammonium hydroxide, and 35 ml. of water. The autoclave was pressured with 600 psig. of carbon monoxide and 600 psig. of hydrogen. The resultant mixture was heated for 2 hours at 150C. Y

The resultant reaction mixture consisted of a colorless aqueous phase (which turned deep blue on exposure to air) and copper metal. The metal was filtered off, washed with aqueous ammonia, water and methanol. After drying in vacuo, the product copper weighed 0.56 g. (a 22 percent yield).

In another run, the glass liner was charged with 5.0 g. (20 mmoles) of CuSO '5H O, 5.25 g. (20 mmoles) NiSO,-6H 16 ml. of concentrated ammonium hydroxide, 35 ml. of water and 10 ml. of heptane. The autoclave was pressured with 600 psig. each of hydrogen {and carbon monoxide and heated 2.5 hours at 150C. The resultant reaction mixture consisted of an aqueous layer, copper metal, and a colorless organic layer.

The copper metal was removed by filtration, washed and dried in vacuo. The amount of copper was 0.74 grams, a 58 percent yield.

The nickel yield determined by treatment of the heptane layer with bromine in CCl was 52 percent. Similar results are obtained when the heptane is omitted.

A copper sample obtained by the procedure above wherein neckel was present in the reaction mixture contained 0.01 to 0.1 percent nickel.

EXAMPLE 15 A glass liner was charged with 5.0 g., 20.0 mmoles CuSO -5H O, 5.25 g., 20.0 mmoles NiSO -6H O, 21 ml. 320 mmoles concentrated NH OH, 25 ml. water, and 10 ml. heptane. The autoclave was pressured with 640 psi. hydrogen and 1,200 psi. carbon monoxide, then heated 2.0 hours at 150C. The reaction mixture consisted of a colorless upper phase, metallic copper, and a light blue aqueous solution. The heptane phase was siphoned off and combined with subsequent heptane extracts of the aqueous phase. The organic solution was treated with excess bromine in carbon tetrachloride.

The resulting mixture was filtered, washed with carbon tetrachloride, and dried. This gave 2.55 g. of light yellow-brown powder, identified as nickel bromide. The amount isolated corresponded to 1 1.7 mmoles Ni(- CO).,, 58 percent yield based on starting NiSO Copper metal was isolated as above. The yield was 0.90 g. 14.2 mmoles (71 percent based on starting CuSO The above example can be repeated by using: copper concentrations of from 0.001 grams per liter to saturated solution, nickel concentrations of from 0.001 grams per liter to satruated solution, ammonia concentrations of from 1 to 10 moles per mole of metal, v hydrogen pressures of from zero to 1,200 psig, temperatures of from 100 to 250C. However, it should be pointed out that the copper concentration is not critical. In addition, preferred copper concentrations are from 1 to 100 grams per liter. Preferred nickel concentrations are from 1 to 150 grams per liter. PrefeiTed ammonia concentrations are within the range of from 1 to 10 moles per mole of metal. Preferred carbon monoxide pressures are from 200 to 400 psig. A preferred temperature range is from 100 to 200C. Reaction times are not critical, times of 1 to 4 hours are usually sufficient. The presence of an immiscible organic solvent is not essential. However, because this embodiment lends itself to be an integral feature of a method for separation of copper metal from nickel carbonyl, it is usually preferred to carry out this embodiment in the presence of a solvent for nickel carbonyl. Solvents for this purpose and amounts thereof have been set forth above.

The nickel carbonyl need not be formed in situ. Rathre, preformed nickel carbonyl .can be added to the reaction mixture.

Another embodiment ofthis invention is the catalytig effect of manganese carbonyl in the production of copper metal from carbon monoxide reduction of ammoniacal copper ammine solutions.

This is illustrated by the following example.

EXAMPLE 16 A glass liner of a rocking autoclave of roughly 300 ml. capacity was charged with Mn (CO) 0.80 g.

Conc. NH.,OH 16 ml.

Water 35 ml.

n-Heptane 10 ml.

The autoclave was pressured with 600 psi of hydrogen and 600 psi of carbon monoxide, then heated 2.5 hours at 150. The reaction mixture consisted of a colorless aqueous phase, metallic copper, solid Mn (C )w. and a yellow organic phase. The heptane layer was siphoned off, and the remaining catalyst was extracted with heptane and ether. Work up of the organic extracts gave 0.59 g. Mn (CO) (74 percent recovery). Metallic copper was filtered off, washed with aqueous ammonia, water, and methanol. After drying in vacuo, 1.03 g. of copper (16.2 mmoles, 40.5 percent yield) was obtained.

The preceding experiment was repeated using the same reaction conditions and the same quantity of reagents, but leaving out Mn (CO), and heptane. There was obtained 0.56 g. 8.9 mmoles of copper metal, representing 22 percent yield. The aqueous phase of the reaction was colorless, but turned to deep blue color when exposed to air.

Because Mn (CO) is a solid, it is preferred that the process be conducted in the presence of an organic solvent. In contrast, Ni(CO) is a liquid and no solvent is required for it to render catalysis of copper metal preparation.

The above example can be repeated and increased yields of copper obtained by using:

copper concentrations of from 0.001 grams per liter to saturated solution,

manganese carbonyl copper ratios of from 0.001 to ammonia concentrations of from 1 to 10 moles per mole of metal,

hydrogen pressures of from to 1,200 psig.,

carbon monoxide pressures of from 200 to 1,200

psig., I

temperatures of from 100 to 250C.

However, it should be pointed out that the copper concentration is not critical. In addition, preferred copper concentrations are from 1 to 30 grams per liter. Preferredmanganese carbonyl to copper ratio is from 0.01 to 0.4. Preferred ammonia concentrations are within the range of from 2 to 4. Preferred carbon monoxide pressures are from 200 to 400 psig. A preferred temperature range is from to 200C. Reaction times are not critical; times of 1 to 4 hours are usually suffcient.

Another embodiment is the catalytic effect of cobalt carbonyl in the production of copper metal from carbon monoxide reduction of ammoniacal copper ammine solutions. For example, similar results to those obtained by manganese carbonyl catalysis in Example 16 are obtained when cobalt carbonyl is substituted for the manganese carbonyl.

The following experiments are an indication that manganese carbonyl also catalyzes the formation of nickel carbonyl.

EXAMPLE 17 The glass liner was charged with 10.5 g. 40 mmoles NiSO -6H O, 0.80 g., 2.05 mmoles Mn (CO) 21 ml. conc. NI-I OI-I (c.a. 320 mmoles), 25 ml. water, and 10 ml. heptane. The autoclave was pressured with 820 psi H and 1,300 psi CO, then heated 2.5 hours at 150, cooled, and vented through a dry ice trap. The reaction mixture consisted of a blue aqueous phase and a yellow organic phase. The heptane layer was siphoned off and the aqueous phase was extracted with about 30 ml. of heptane-hexane solution. The combined organic solution was distilled in vacuo into a dry icecooled receiver. Work-up of the distillation residue gave 0.53 g., 1.36 mmole Mn (CO) representing 67 percent recovery. The distillate, containing Ni(CO) was treated at 76C. with bromine-carbon tetrachloride solution until no more gas was evolved and the mixture contained excess of bromine. The suspension was filtered and washed with carbon tetrachloride. After drying in vacuo, 5.93 g. of nickel dibromide was obtained. Thus, the yield of nickel carbonyl was 27.1 mmoles, or 68 percent.

The amounts of starting materials used were the same as in the preceding experiment, except that no Mn (CO) was added in this case. The autocalve was pressured with 800 psi H and 1,200 psi CO and heated 2.5 hours at 150C. Following the same work-up procedure, 4.86 g. of NiBr was obtained. This corresponded to 22.2 mmoles of Ni(CO),,, 56 percent yield.

As with all processes of this invention described and illustrated by the above description and examples the processes of the aforesaid examples are not criti cally dependent on use of n-heptane. When an essentially water-immiscible solvent is used, it may be any solvent for nickel carbonyl. For economic reasons, aliphatic hydrocarbon materials are preferred solvents. To facilitate Ni(CO) stripping the solvent preferably has a boiling point of at least about 36C. There is no critical upper limit in boiling point of solvent.

From the foregoing description, it can be readily seen that the process of this invention is highly flexible. Thus, any method for obtaining nickel and its associated metals in the desired form for carbonylation may be used. A feature of this invention is,therefore, the combination of various pyrometallurgical, hydrometallurgical, vapometallurgical, and physical separation processes with carbonylation to obtain and separate nickel and its associated metals. Indeed, such combination results in improved processes for winning nickel by advantageously using proven front-end processes in handling various types of ores most economically, dissolving or partially dissolving the nickel values in an aqueous ammonium salt or ammonium hydroxide solution and contacting the solution with a carbon monoxide-containing gas under conditions whereby the nickel values are reduced to form nickel carbonyl, copper values are precipitated as metallic copper, and cobalt values remain in aqueous solution as a cobalt carbonyl anion from which it is readily recovered by oxidation to hydrated cobalt oxide. Thus, the overall process effects removal of nickel and those associated metals from the material provided by the front-end process.

The wide applicability of such improved processes is illustrated by combining the above-described reductive carbonylation process with a sulfide or oxide ore leaching process, a ferronickel process, a blast furnace or converter matte process using either sulfide or oxide ores or even a scrap metal recovery process. As a result of such improved processes, substantial savings in operational steps, processing costs, and capital investment are realized. 7

One currently employed process as schematically diagrarnmed in FIG. 2A shows a process employing crushing and grinding, drying the ore to prepare a material of suitable size, partially reducing the ore to the metals, cooling the reduced ore under non-oxidizing conditions, oxidatively leaching the reduced ore with aqueous ammonia and carbon dioxide to dissolve nickel and cobalt as their carbonates. The leach solution is then boiled to concentrate the solution, recover ammonia values, and precipitate basic nickel carbonate. The basic nickel carbonate is then sintered to produce a nickel oxide product.

FIG. 2B shows the improved-process combining carbonylation after the oxidative leach. Such an improved process allows recovery of nickel metal and, in addition, cobalt by a simpler process requiring fewer operations and less processing equipment. According to FIG. 2B, the steps of ore preparation (which include crushing, grinding and drying), reducing and cooling under non-oxidizing conditions are the same as the process of FIG. 2A. However, the oxidative leach may be carried out under more strenuous conditions and significant amounts of cobalt, suppressed in the previous process, are now leached from the ore. The previous process having no easy method for separating cobalt finds leaching of the cobalt a liabilityto the process. However, the process of this invention easily separates cobalt and, thus, it becomes an asset to the process. After leaching, the leach solution is subjected to carbonylation under conditions whereby nickel and cobalt tetracarbonyl compounds are produced. The nickel carbonyl is separated from the solution and the metal recovered from the carbonyl compounds. The cobalt is separated in a different manner. Thus, a preferred embodiment of this invention is a process for recovering nickel values from lateritic nickel ores predominantly of the silicate type ore containing them, said process comprising:

a. subjecting said ore to a reducing roast to convert asubstantial amount of said nickel to nickel metal;

b. cooling the reduced ore under non-oxidizing conditions;

c. oxidatively leaching said reduced ore with an aqueous ammoniacal ammonium carbonate solution by injecting an oxygen-containing gas into a slurry of said reduced ore in said ammoniacal ammonium carbonate solution;

d. contacting the resultant leach solution containing nickel ammonium salt complexes with a carbon monoxide-containing gas under conditions whereby the nickel values are reduced to nickel carbonyl;

e. separating said nickel carbonyl from said leach solution; and

f. decomposing said nickel carbonyl to metallic nickel.

The lateritic nickel ore is prepared for reduction by crushing and drying. A first crushing, for example, in toothed roll crushers, breads up larger lumps of ore for convenient drying in a concurrently oil-fired rotary drying kiln. Temperatures in the kiln range from about 1,900F. at the entrance to about 250F. at the exit. The dry ore averages about 1.4 wt.% nickel and 0.1

wt.% cobalt. The dried ore is then finely ground in hammer and ball mills and charged to the reduction furnace.

Reduction is carried out in a multiple hearth furnace using a producer gas and additional heat from combustion of fuel oil. A sufficiently low heating rate permits substantially complete reduction of nickel oxide to metal at less than 1,400F. Reduction is carried out at this temperature to obtain the maximum amount of nickel as the metal and yet limit the amount of iron and other impurities such as magnesia in the product. The reduced ore is cooled under non-oxidizing conditions by discharging the furnace into cooling tubes rotating in a water bath. The temperature of the ore on exiting from the coolers is about 300F. The ore is then placed in quench tanks containing an ammoniacal ammonium carbonate leach solution. The leach solution is made by injecting ammonia and carbon dioxide into water. High temperatures in the quench tank are prevented by precooling the ammoniacal leach liquor in water-cooled heat exchangers. Such low temperatures minimize ammonia vaporization and deposition of scale.

From the quench tank, the ore is leached in aerating tanks by injecting an oxygen-containing gas, for example air, into the solution. The oxidation of nickel dissolves the nickel into the ammonia ammonium carbonate solution as a stable hexammine nickel carbonate complex. Also, the recovery process of this invention permits a deep leach which also dissolves the cobalt values in the ore. Iron deposits out as hydrated ferric oxide and can be removed as such from the leach tank.

The dilute leach solution discharges into a series of thickeners which serve to settle and remove the gangue. The supematent washed leach liquor can then be passed into an autoclave for carbonylation. The essentially iron-free solution containing nickel and cobalt values is contacted with a carbon monoxide-containing gas. This operation is carried out as described above to produce nickel carbonyl and cobalt tetracarbonyl anion. Separating of nickel carbonyl from the leach solution can be carried out by extracting the nickel carbonyl into an essentially water-immiscible, substantially inert solvent for nickel carbonyl, thus concentrating the nickel carbonyl produced in the solvent, or when the reaction is essentially complete, additional amounts of carbon monoxide-containing gas may be passed through the carbonylated leach solution to vaporize the nickel carbonyl. The nickel carbonyl is then passed into a decomposition zone to obtain metallic nickel. Decomposition is readily accomplished thermally by known methods.

This embodiment of the invention can be illustrated in the following examples. Unless otherwise stated, all parts are by weight.

EXAMPLE 1 8 A solution of basic nickel and cobalt carbonates such as result from the oxidative leach step of the above process, was prepared by dissolving 51 parts of NiCl -6H O and 10 parts of CoCl -6l-I O in 100 parts of water. To this solution was added sufficient aqueous sodium hydroxide to precipitate the metals as Ni(Ol-l and Co- (OH) After filtration, washing, and resuspension in water, 90-400 parts of ammonium carbonate and 27 parts of concentrated ammonium' hydroxide were added. The solution was stirred and warmed slightly to yield a blue solution of nickel and cobalt salts.

The blue solution was then vaporized under vacuum at 35-40C. to decrease the volume of solution. Any precipitated solids were re-dissolved using enough aqueous ammonia so that the final solution analyzed as follows:

2 parts Ni 0.2 parts Co parts H 0 2 parts .Nl-l (as concentrated ammonium hydroxide) This solution, corresponding to an oxidative leach solution according to the above process, was placed in a reaction vessel equipped with a stirrer, a thermocouple, a pressure gauge, a gas inlet tube, and a vent gas discharge tube. To the solution was added 7 parts of heptane. The autoclave was sealed and pressured to 300 psi. with carbon monoxide. The stirrer was started and the temperature in the reaction vessel brought up to C. The reaction was continued for 40 minutes with carbon monoxide pressure decreasing to 220 psi. indicating the carbon monoxide was absorbed in the reaction vessel contents. The stirrer was stopped and the reaction vessel cooled. The remaining carbon monoxide was vented and the reaction vessel was opened.

The contents of the reaction vessel has separated into two layers. The heptane layer was drawn off and the remaining aqueous layer was observed to have the blue color characteristic of nickel and cobalt salt solutions. Therefore, the reaction, was of low yield. The organic layer was, therefore, not analyzed for nickel carbonyl. Several runs were carried out using the procedure of Example 18 except for the addition of catalyst and the reaction time. The results are shown in Table ll below.

It will be appreciated by skilled practitioners that the invention does not require a solvent for separation of nickel carbonyl. However, it is a preferred embodiment of the invention that the contacting with the carbon monoxide-containing gas is carried out in the presence of an essentially water-immiscible, substantially inert solvent for nickel carbonyl whereby said nickel carbonyl formed is concentrated in said solvent. As stated previously, the solvent can be any solvent meeting the above criteria. A preferred solvent is an aliphatic hydrocarbon.

Example 19 in Table II above shows that a catalyst is not necessary for converting nickel to nickel carbonyl with carbon monoxide. However, it is clear from Examples 20 and 21 that the presence of a catalyst is extremely beneficial. Therefore, it is a preferred embodiment of the invention that the contacting with the carbon monoxide-containing gas is carried out in the presence of a catalyst for the formation of nickel carbonyl. A preferred catalyst is cyanide ion. A most preferred catalyst concentration is from about 0.01 to about I mole of cyanide ion per mole of nickel present.

While the nickel carbonyl may be separated from the aqueous reaction phase, by carrying out the reaction in the presence of a solvent, the nickel carbonyl may also be separated from the leach solution by passing additional carbon monoxide-containing gas through the

Claims (23)

1. 2. A process of claim 1 wherein said solution or slurry is an ammonium salt solution or slurry.
2. 3. A process of claim 2 wherein said ammonium salt solution or slurry is an ammoniacal ammonium salt solution or slurry.
3. 4. A process of claim 3 wherein said ammoniacal ammonium salt solution is selected from the group consisting of ammoniacal ammonium chloride, carbonate, sulfate, and mixtures thereof.
4. 5. A process of claim 4 wherein said ammoniacal ammonium salt solution or slurry is an ammoniacal ammonium carbonate solution or slurry.
5. 6. A process of claim 5 wherein the molar ratio of ammonia to metal in said ammoniacal ammonium carbonate solution is from 0:1 to about 100:1.
6. 7. A process of claim 6 wherein the molar ratio of ammonia to metal in said ammoniacal ammonium carbonate solution is from 0:1 to 10:1.
7. 8. A process of claim 6 wherein said reaction is carried out at a pressure of from 50 to about 3,000 psig. and a temperature of from about 50* to about 250C.
8. 9. A process of claim 8 wherein said temperature is from 100* to about 175C.
9. 10. A process of claim 1 wherein said reaction is carried out in the presence of a catalytic amount of a ligand selected from the group consisting of cyanide, sulfide, cysteine, and tartrate.
10. 11. A process of claim 10 wherein said reaction is carried out at a temperature of from 50* to about 250C. and a pressure of from 50 to about 1,800 psig.
11. 12. A process of claim 10 wherein said ligand is present at a ratio of from 0.01 to 1 mole of said ligand per mole of said nickel.
12. 13. A process of claim 12 wherein said ligand is present at a ratio of from 0.01 to 0.5 mole of said ligand per mole of said nickel.
13. 14. A process of claim 12 wherein said ligand is cyanide ion.
14. 15. A process of claim 1 wherein said carbon monoxide-containing gas is selected from the group consisting of carbon monoxide and synthesis gas.
15. 16. A process of claim 15 wherein said carbon monoxide-containing gas is carbon monoxide.
16. 17. A process of claim 1 wherein said contacting is carried out in the presence of an essentially water-immiscible, substantially inert solvent for nickel carbonyl whereby said nickel carbonyl is concentrated in said solvent.
17. 18. A process of claim 17 wherein said solvent is a saturated aliphatic hydrocarbon.
18. 19. A process of claim 4 further characterizeD by carrying out said contacting in the presence of an amount of cyanide ion sufficient to catalyze the formation of said nickel carbonyl.
19. 20. A process of claim 19 wherein said contacting is carried out in the presence of an essentially water-immiscible, substantially inert solvent for nickel carbonyl wherein said nickel carbonyl formed is concentrated is said solvent.
20. 21. A process of claim 1 wherein said nickel carbonyl is separated from said solution by passing a carbon monoxide-containing gas through said solution, allowing said nickel carbonyl to vaporize into said carbon monoxide-containing gas and subsequently passing said carbon monoxide-containing gas into a thermal decomposition zone wherein said nickel carbonyl in said carbon monoxide-containing gas is decomposed to metallic nickel.
21. 22. A process of claim 1 wherein said solution or slurry is aqueous ammonium hydroxide.
22. 23. A process for the manufacture of nickel said process comprising a. establishing an aqueous solution or slurry containing nickel derived from a source of nickel ore, b. contacting said solution or slurry with a carbon monoxide-containing gas under conditions of temperature and pressure sufficient to form nickel carbonyl, c. separating said nickel carbonyl from said solution or slurry, and d. decomposing said nickel carbonyl to obtain metallic nickel.
23. 24. A process of claim 1 wherein said aqueous solution or slurry contains an ammonium salt or ammonium hydroxide and a catayltic amount of cyanide ion and the reaction is carried out at a temperature of from about 50* to about 250 C and a pressure of from about 50 to about 3,000 psig.

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