GB2491762A - Selective reduction of Ni, Co and Cu from a mixed metal oxide and production of activated nickel - Google Patents

Abstract

A method of reducing a mixture of nickel, cobalt, copper and iron oxides using an atmosphere comprising hydrogen and water vapour to selectively reduce the nickel cobalt and copper oxides relative to the iron oxide. A metallic mixture having a reduced ratio of metallic iron relative to metallic nickel, cobalt and copper is produced. The method is performed at 350-550 0C in an atmosphere which may also comprise an inert gas, CO and CO2. The oxide may comprise no more than 4 % w/w of iron and may be a nickel smelter product or nickel-cobalt leach product. Also a method of producing activated nickel by treating metallic nickel with H2S at a pressure of 100-300 kPa and at a temperature of 20-150 0C.

Description

ATUS AND PRO CESS FOR MA

EBDOFIIIJNVENTLQN

This invention relates to processes for the production of high purity nickel via carbonylation of impure nickel with carbon monoxid9 and subsequent decomposition to said high purity nIckel; to processes of making said impure nickel, particularly, from compositions comprising mixed metal oxides and to apparatus of use in said processes-

BACKGROUND OF5HIiINVFNTK?N

Nickel carbonyl, Ni(CO)4, was first produced by the reaction of metallic nickel with carbon monoxide by Mond in the early part of the 1 90 century-Today, one of the major industrial processes for making metallic nickel is based on the production of Ni(CO)4 and subequent therntal decomposition thereof to Ni and CO. One kno commercial process operates at about 180°C and a CO pressure of about 70 atm-It is known that the CO pressure may be reduced when the reactant nickel is catalytically activated-Activation of the metal has been observed in the presence of mercury (1,2), sulphur in the form of H23 (3,4), hydrogen (5,6) or carbon (7)-Jt has been suggested that the high initial rate of founatiort of Ni(CO)4 and the subsequent decline to a steady state value is the result of a rapid decrease in the number of activated reaction sites which are produced upon heat treatment of the sample (6,8,9)-A study of surface changes during carbonyl synthesis suggests that the maximum rate is associated with fundamental changes in the defect structure-All of the above methods use catalytic activation of nickel in the presence of CO.

Canadian Patent No. 822)0 16 -The International Nickel Company of Canada, published September 2, 1969, discloses a high pressure carhonylatiort process for particular use with smelter nickel Intermediates high in copper and irorn Methods of reducing mixed metal oxide compositions comprising oxides of nickel, cobalt, copper and iron with hydrogen to produce the respective metals for subsequent ntckel carbonylation in the presence of H2S and subsequent decomposition of the nickel carbonyl to metallic nickel in powder or substrate form are known-However, there remains a need for an improved process of preparing high purity nickel, particularly; nickel powder having acceptable levels of sulphur and metallic impurites e.g. Co, Cu and Fe.

PUBLJC4TIQN 1. Morton J.R., Preston K. F. J (]hern. Pfiys., 81, 56, (1984).

2. Morton J.R., Preston K. F. Inorg. diem., 24, 3317, (1 985).

3. Mercer D. L.; Inca Ltd. (Cam 1038169 [1975/78]).

4. Schafer H. Z. Anorg. AUg. Client 493, 17 (1982).

5. Job K. J diem. Ethic. 56, 556 (1979).

6. Mazurek H., Mehta R. S., Dresseihaus M S., Dresselhaus 0., Zeiger H. J. Surf Sd 118, 530 (1982).

7. Korcnev A. V., Shvartsman R. A., Mnukhin A. S., Tyvein. MeL 1979 Nol 1, pp. 37.

8. Mehta R. S., Dresselhaus M. S., Dresseihaus 0., Zeiger H. J. Surf Sd. 78, L681 (1978).

9. Greiner 0., Manzel P. J. Catat 77 382 (1982).

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a method for producing an improved quality nickel, particularly, itt the form of a powder.

It is a further object to provide a method of selectively reducing the ratio of metallic iron relative to metallic Ni, Cu and Co from the ratio of said metals in the form of their respective OxIdes in a starting composition comprising said oxides.

* It is a further object to provide an improved method of producing activated nickel for subsequent carbonylation from a metallic admixture comprising metallic nickel, cobalt; * copper and iron.

It is a further object to provide metallic nickel when made by said processes.

it is a further object to provide nickel carbonyl from the reaction of said metallic nickel with carbon monoxide and subsequent decomposition of said nickel carbonyl to metallic nickel, particularly, in the form of nickel powder.

It is a further object to provide apparatus of use in the aforesaid processes Accordingly, in one aspect, the invention provides an improved method of reducing a mixed metal oxide composition comprising oxides of nickel, cobalt, copper and iron in a hydrogen atmosphere to produce a mixture of the respective metals, the improvement wherein said atmosphere further comprises water vapour at a concentration, temperature and time to effect selective reduction of said oxides of nickel cobalt and copper relative to said iron oxide to produce said metallic mixture having a reduced ratio of metallic iron relative to* metallic nickel, cobalt and copperS The process is of value where the mixed metal oxide composition has an iron oxide content preferably of less than 4% wlw, more preferably less than 2% w/w, as found for example, in the mixed oxide composition obtained by the roasting of nickel matte smelter product) generally known as oxide calcine The hydrogen reduction process is, preferably, carried out at a temperature selected from about 350°C to about 550°C, preferably, about 500°C iS The water vapour content in the hydrogen gas rcductant atmosphere is, preferably, but not limited to, ranges from 10% to 50% by volume, and more preferably 30% v/v H20 The reductant atmosphere may further comprise carbon monoxide and carbon dioxide, particularly, carbon monoxide and hydrogen contained in so-called Acproducer gas".

The atmosphere preferably comprises the hydrogen and water in a ratio of 10:1 to 1:1 hydrogen to water, preferably, 3:1 112:1120, more preferably 10-50% v/v 1120, and still more preferably 25-35% v/v 1120.

The carbon dioxide content in a carbon monoxide containing reducing gas should preferably be, but not limited to, CO2ICO ratios by volume ranging between 112 and 5/1 and more preferably 2/1.

The resultant metallic mixture product according to the invention, when made by a process as hereinabove defined, is of particular value when used in a pre-sulphiding process as hereinafter defined.

Tn a further aspect, the invention provides a method of producing an. activated metallic nickel from a metallic nickel for subsequent reaction with carbon monoxide, said method comprising pre-sulphiding said metallic nickel with hydrogen sufphide at a pressure selected frdm I to 3 atmospheres (100 to 300 kPa) and a temperature selected from 20 -150° for an effective activation period of time.

In this specification and claims pressures may be considered to be partial pressures when an inert gas is also present.

In a preferred aspect, the metallic nickel is in admixture with one or more metals selected from cobalt, copper and iron wherein admixture is Ireated with said hydrogen suiphide to effect production of one or more suiphides, selected from copper sulphide, cobalt sulphide and iron sulphide.

In one embodiment, the aforesaid admixture is a metallic mixture product obtained by the reduction with gaseous 112/H20 as hereinabove defined.

Preferably) the pre-suiphiding temperature is selected from 100-120°C and the pressure is selected from 1 to 2 atmospheres (100 to 200 kPa).

Thus, in a further aspect the invention provides an activated nickel when made by a pre-suiphiding method as hereinabove defifled.

In a further aspect, the invention provides producing said purified nickel in the form of a powder.

In a further aspect, the invention provides apparatus for the production of high quality nickel from an impure nickel source composition comprising oxides of metals selected from the group consisting of nickel, iron, cobalt and copper, said apparatus comprising (i) a reducing chamber for containing said composition; (ii) means for heating said composition to a temperature selected from 350°C-650°C; (iii) means for providing said reducing chamber with a reducing gaseous atmosphere comprising hydrogen and water to operably produce a first admixture comprising metals selected from the group consisting of nickel, cobalt and copper; (iv) nowcarbonylation pre-sulphidmg means for treating said first admixture with hydrogen suiphide at a temperature selected from 20°150°c to produce a second admixture comprising metallic nickei. and metallic sulphides selected from copper and cobalt; (r) carbonylation means for effecting carbonylation of said second admixture to produce nickel carbonyl; and (vi) decompositIon means for effecting decomposition of said nickel carbonyl to said high purity nickel.

Thus, the present invention provides, principally, the production of refined nickel powders, while utilizing a most effective way of achieving sulphide activation of a wide 4.

variety of metallic nickel starting materials, particularly, impure metallic nickel feed materials containing substantial quantities of copper, iron and cobalt, prior to charging a carbonylation reactor at essentially atmospheric pressure, for the production of nickel carbonyl gas of desired strength, without the production of any liquid carbonyls, and subsequent decomposition of the carbonyl gas to yield nickel powders with predetemiined, specific physical and chemical properties.

The present invention provides for the carbonylation reaction to be carried out at essentially atmospheric (lOOkPa) pressure, and, accordingly, large scale commercial operations can readily be engineered for continuous operation.

The nickel activation step using J-12S, herein termed "pre-sulphiding" as hereinabove defined at relatively low temperatures, is effected most preferably in an oxygenfree, preferably, nitrogen atmosphere, preferably at a slightly-above atmosphere pressure (1 00kPa) at room temperature or preferably at slightly above room temperature, depicted as T2 in Figure 1 and data presented in Table 2. Such pre-suiphiding can be accomplished in the feed bins, or in the transfer conveyor usually located between the reduction reactor and the feed bins. Alternatively, a portion of the sulphiding can be effectively accomplished in the carbonylation reactor pç, for example, by a continuous controlled addition of H23 to the incoming CO gas.

The apparatus further comprises apparatus for the production of high purity nickel from a metallic nickel source, comprising (a) noncarbonylation pre-suiphiding means for treating said nickel source with hydrogen suiphide at a temperature selected from 20°C to 150°C to produce activated nickel; (b) carbonylation means for effecting carbonylation of said activated nickel to produce nickel carbonyl; and (c) decomposition means for effecting decomposition of said nickel carbonyl to said high purity nickel.

Yet further, thc apparatus further comprises apparatus for the production of high quality nickel from an impure nickel source composition comprising oxides of metals and selected from the group consisting of nickel, iron, cobalt and copper, said apparatus comprising (i) a reducing chamber for containing said composition; (ii) means for heating said composition to a temperature selected from 350°C-650°C; (iii) means for providing said reducing chamber with a reducing gaseous atmosphere comprising hydrogen and water to operably produce a first admixture comprising metals selected from the group consisting of nickel, cobalt and copper; (iv) non-carbonylation pre-suiphiding means for treating said first admixture with hydrogen sulphide at a temperature selected from 20°-I 50°c to produce a second admixture comprising metallic nickel surE metallic suiphides selected from copper and cobalt; (v) carbonylation means for effecting carbonylation of said second admixture to produce nickel carbonyl; and (vi) decomposition means for effecting decomposition of said nickel carbonyl to said high purity nickel.

By the term activation" as used in this specification, is meant the process of producing activated nickel which has the form to react expeditiously with CO at about 25 50°C and 1-2 atmospheres (100 to 200kPa) pressure, to produce nickel carbonyl.

BRIEF DES CEtJPTION OF THE DRAWINGS in order that the invention may be better understood, preferred embodiments will now be described by way of example only, with reference to the accompanying drawings, wherein Fig-1 is a diagrammatic representation of apparatus and process for the production of high purity nickel from impure nickel, according to the invention; Fig. 2 is a graph of TGA Tests that show the effect of reduction temperature on suiphiding, at I O0kPa, 50°C of FBR Calcine (Sample B); Fig. 3 is a graph of TGA Tests that show the carbonylation of impure nickel matte calcine, material CC) at atmospheric (1 O0kPa) pressure and 5 0°C, after reduction in hydrogen and subsequent pre-suiphiding to various activation levels; Fig. 4 is a graph of TGA Tests that show the carbonylation of impure nickel matte calcine, Material T" at atmospheric (lOOkPa) pressure and 50°C, after reduction in hydrogen and subsequent pre-sulphiding to various sulphur activation levels; Fig. S is a graph of TGA Tests that show the carboriylation of impute nickel matte calcine, Material "F" at atmospheric (lOOkPa) pressure and 50°C, after reduction in 30% v/v 1-120-70% v/v 112 at 500°C; and after pre-sulphidirtg at various temperatures to various sulphur activation levels; Fig. 6 is a graph of carbonylation of uickeIcoba1t hydroxide material under various reduction and carbonylation conditions, but without sulphiding; and Fig. 7 is a graph of carbonylation of nickel-cobalt hydroxide material under various reduction and carbonylation conditions, under varying degrees of pre-sulphiding activation.

DETAILED LWCRIPTI0N OFT PREFERRED EMBODIMENTS Fig-I shows apparatus and process constituents for making nickel powder from an impure nickel feed, which apparatus and process involve known steps of nickel feed preparation, carbonylation of nickel with carbon monoxide and subsequent decomposition of resultant nickel carbonyl to metallic nickel.

In the apparatus and process of the present invention, a nickel Iced comprising oxides of Ni, Fe, Cu and Co are reduced in an atmosphere of 30% v/v 1120-70% v/v 1-12 at a temperature of about 500°C to produce a composition of metals of Ni, Cu and Co, in chamber 10 This composition, cooled to room temperature, is fed to a pre-suiphiding chamber 12 by feed conduit 14 and treated with FI2S at a temperature of 206O°C and slightly above atmospheric pressure, to effect selective sulphidization of Co and Cu over Ni, while activating the nickel to an appreciable degree. This resultant activated nickel is fed to carbonylation reactor 16 via feed conduit 18. Subsequent carbonylation to nickel carbonyl and decomposition thereof in chamber 20 results in nickel powder being collected in box 22.

Preferred temperatures and gas and water circulation steps are shown in Fig. 1.

With reference to the Figures, the notations shown therein denote the following:-In Figure 2 * Reduction time in hydrogen? Hours Suiphiding Time for 6% w gain, Hours aftsr reduction in pure hydrogen Reduction time in 3O%H2QJO%H2 gas mixture, Hours o Suiphiding Time for.% wt gain, Hnurs after reduction in 30% H20-70% H2ga mixture in Figure 3 -EZI -sample weight E3g, reduction at 425 oC, 1% sulphu-w, (30 oC Carbonylation) [IS -sample weight SJIg, reduction at 425 oC, 2% sulphur -Sample weight 55g, reduction at 425 oC, 4% sulphur EM -Sample weight 5$g,reduction at 425 oC, 6% sulphur -sample weight 6Mg, reduction at 425 cC, 6% sulphur.

:E1T -sample weight LGg, reduction at 425 cC, 6% sulphur -sample weight = 2Mg, reduction at 425 cC, 6% sulphur -[22 -sample weight S$g,reduclion at 500 cC, 2% sulphur -sample weight 5Mg. reduction at 500 cC, 6% sulphur -sample weight = 2,0g. reduction at 500 oC, 6% sulphur In Figure 4 redUction at 425 oC, 2% sulphur -reduction at 425 oC, 45% sulphur reducfton at 425 oC, 6%sulphur reduction at 500 oC, 4% sulphur --FIG reduction at5000C, 45% sulphur -reduction at 600 oC, 4.5% suLphur F8 reduction at 600 oC, 6% sulphur In Figure 5 -MI 2 j % S g eio oC atmospheric _F124..5wt%Sat500C lOOkF'a -F133wt%Satl000Catm05PherPC FtI4 -3 wt % S at 120 oC atmospheric MS -3 wt Yu S at 135 oC atmospheric -FIG -3wt% Sat 150 oC atmospheric JnFigureô -Gi-Reduction in 112 at 300 oC, Carbonylation 30 oC l000kFa 02-Reduction in H2 at 350 oC, Carbonylation 30 oC I 000RPa --G3-Reduction in H2 at 400 oC, Carbonylation 50 oC OkPa -------G4-Reduction in H2 at 400 oC, Czirbonylation 30 oC lOOkPa -G5-Reduction in H2 at 400 oC, Carbonylation 30 oC lOOkPa -136-Reduction in H2 at 400 oC, Carbonylation 50 00 700kPa 137-Reduction in 92 at 400 oC, Carbonylation 30 oC 1 OiJOkPa -138-Reduction in 92 at 400 oC, CarbonylatiOn 50 oC l000kPa 139-Reduction in 92 at 400 oC, Carbonylation 85 oC 1 000kPa -----G13-Reduction in 92 at 500 oC, Carbonylation 30 oC OFcPa 1318-Reduction in 92 at 500 cC, Carbonylation 50 cC OkPa -1319-Reduction in 92 at 500cC, Carbonylation 30 oC l000kPa -----G20-Reduction in 9.2 at 500 oC, Carbonylation 85 oC l000kPa inFigure7 20..-614-Recluctron in F12 at 450 oC, 0% wt S, Carboriylation 50 oc Okra ---C15-Reduction in 1-12 at 450 oC, 111% wt 5, CarbonyPation 50 oC OkPa -G16-Reduction in H2 at 450 oC, 2.6% wIt 8, Cathonylation 50 oC OPcPa G17-Recluction in Ff2 at 450 oC, 5% wt. 5, Carbonylation 50 oC OFPa 010-Reduction in 1-12 at 400 oC, 0.60% wIt 3, Carbonylation 50 cC TOOIcPa --GI 1-Reduction in Ff2 at 400 oC, 2.00% wt. 8, Carbonylation 50 oC 100}cPa --=--=----G12-Reduction in Ff2 at 400 oC, L00% wt. 5, Carbonylation 50 oC 1 ODIsPa 025-Reduction in H2 at 400 cC, 0% wt. 5, Carbonylation 50 oC 1 OOkPa -026-Reduction in 1-12 at 400 cC, 200% wI. 5, Carbonyfation 60cC lOOIcPa ----027-Reduction in 1-12 at 400 cC, 2.00% wL. 8, Carbonylation 50 cC lOOIcPa 1328-Reduction in 1-12 at 400 cC, , Carbonylation 50 cC I OOkPa CO-8% H2S -G29-Reduction in Ff2 at 400 cC, ,Carbonylation 50 cC lOORPa CO-0.02% H2S -030-Reduction in 92 at 400 cC, 3 % wt S. Carbonylanon 50 oC lOUIcPa Various nickel containing materials, their sources and compositions are shown in Table 1, by way of example only-The present invention is applicable to a wide variety of similar compositions or the treatment of relatIvely pure metallic nickel.

Nickel-containing feed can be provided -from various sources and in several different chemical and physical forms, having the nickel as metal, suiphide, oxide, hydroxide, or cat-bonate. Thus, the feed preparation step is tailored to the nature of the source nickel. For example, in the case of nickel matte emanating from smelters, the nickel usually contains 20 or more percent wiw of sulphur, and usually contain other metals, such as copper, cobalt, iron and impurities, such as silicate materials) and, often, will also contain minor, but valuable quantities of precious metals In preparing such matte in the practise of the present invention, it is preferable that the matte be in granular form before being passed on to a roasting step at elevated temperatures that could be as high as 1150°C. This eiiminates sulphur and converts all of the base metals to oxides. The resulting oxide granules are passed to a reduction step, normally at io temperatures between 350°C -650°C to provide the nickel in granular metallic form. if the nickel source is a hydroxide or carbonate, a single heating-reductLOn step is adequate to provide the nickel as metallic fines. These metallic nickel forms are acceptable for carbonylation in the practise of the present invention.

Table 2 is

yrcSu1phiding of High Grade Nickel Granules (TGA Tests) 82w pIe Mesh Suiphidhig Pressure of Sifiphidiug S4hurpkk-up ID Nickel Size Temperature ji,s, lime, Hours by tUe nickel, psi wt. % 50 _ 05_ -._ I A3 991-I -TOO 25 30 7.5 025 Bi I 99 [ 4pQJ_ 25 pJ_7.5 0.19 B2 I 99-'-1 -100 J-25 45 t 75 020

Table 1

Materials Identification A NIckel Granules) Australian Commercial 99%Ni,0A 1% Cc, 0:03% F; Source: final product from a leaching Balance oxygen operation B Nickel Granules, Canadian Commercial 99%Ni, 0.15% Co, 0i334 F; Source: final product from a leaching Balance oxygen operation C Nickel Granules, Japanese Commercial 95-5% Ni, 0.20% Cu) 1.4% Co, Source: Nickel matte granules fluid bed OAIO% Fe? Balance oxygen roasted and subsequently fluid bed reduced U' Sinter 75 mekel oxide, Japanese 77%Ni, 0-65% Cu, 1.11% Co, Commercial Source: nickel matte granules 03% Fe, Balance oxygen fluid bed roasted to oxide B Calcine Granules: produced by fluid bed 59%INi, 16% Cu, 0.92% Co, roasting in a pilot plant operation, of impure 4M7% Fe, 0.05% S, Balance matte granules, high in copper and iron oxygen coming from a Chinese commercial smelting operation F laboratory Ni 12% Cu, 094% ëo, roasting, of impure matte granules, high in 2-1% Fe, OXJ1% 3, Balance copper but lower in iron than "B", from the oxygen same Chinese commercial smelting operation G Nickel hydroxide intermediate material: 32%Ni, 4.46%Co, 0.08%Fe, recovered by lime precipitation of liquor 5.55%Mn, ft53%Cr, 070%Zn obtained by acid leaching of nickel laterite ______ __________ ore (b) 13.4%Ni, 0.58%Co, 035%Fe, 0.78%Mn, 0.06%Zn RY1 I I5%Ni, 0.94%Co, 0.55%Fe 036%Mn 0.l0%Zn The nickel granular or fine feed, that may already be activated by reaction with H23, is fed to a carbonylation reactor chamber wherein the exothermic carbonylation reaction of nickel with carbon monoxide is carried out The reactor, for example, may be either a packed bed or a moving bed type, wherein moving bed type is either a rotary bed or a fluid bed The reactor is provided with cooling means whereby the excess heat generated by the reaction is effectively removed.

Carbonylation was found to proceed at reasonable/practical rates at temperatures as low as 38°C and as high as 80°C when operating at essentially atmospheric pressure, or just modestly above atmospheric pressure, with temperatures in the narrow range of 50°C tu 60°C proving to be optimum in many cases, as seen in Table 3, hereinafter.

Nickel carbonyl-laden carbon monoxide leaving the reactor chamber, after passing through a filter, held essentially at reactor temperature (35-60°C), is fed to a decomposer chamber through a cooled feed nozzle to prevent decomposition occuring in the nozzle as gas is introduced into the decomposer chamber in which the temperature, Tg, (250-450°C) is normally set at temperatures above 250°C. At the same time, the feed nozzle is not below about 45°C to avoid production of undesirable liquid nickel carbonyL Accordingly, water cooling of the feed nozzle is closely controlled to yield a cooling outlet temperature, T7, between 40° -60°C.

Figure 1 illustrates a preferred process and apparatus of use in the practise of the invention wherein temperatures and material flows arc shown.

In the aforesaid process, over 99% of the nickel carhonyl is decomposed and collected in the collection box.

EXAMPLES

Example I: Sulpbiding and Carbonylation of Nickel Metallic GrannIes Metallic nickel granules containing 99-i-% Ni essentially free of any sulphur, and of minus 100 mesh size, Test "AS", were charged to an oxygen-free reactor chamber that had been purged with nitrogen gas, and a first quantity of hydrogen sulphicle was introduced into the chamber at a pressure of 200kPa. The chamber was sealed off and the nickel was held at this slightly elevated pressure for 8 hours at room temperature of around 25°C. The resulting nickel granules analyzed for 0.11 w/w %3 Some 2.8 kilograms of these suiphided granules were charged to a rotary kiln-type oxygen-free moving bed mini-pilot plant reactor which had been purged with nitrogen gas. A continuous stream of carbon monoxide of about 8 times in excess of stochiometric requirements and a second small quantity of hydrogen suiphide was introduced to the chamber, at essentially atmospheric pressure, while the temperature in the reactor was held at about 40°C-The gases exiting the reactor chamber contained over 10% by volume of nickel carbonyl during the first 6 hours which gradually dropped to around 8% V/v after 24 hours.

The exit gas contains about 2% when the reaction was stopped before the reaction had reached completion. The carbon monoxide plus nickel carbonyl product gases were passed directly to a mini-pilot plant powder decomposer (described in Example 2 hereinafter), that was controlled at a decomposition temperature of around 400°C. The nickel powder collection box was maintained at a temperature above 170°C-After stopping the flow of carbon monoxide to the carbonylation reactor, the system was allowed to cool down while being purged with nitrogen gas, and the powder was cooled to room temperature of around 25°C. Some 72% of the nickel in the metallic granules had been converted to nickel powder of 0.06 w/w 1⁄4 S with a density of 1.12 g/cc.

In a related series of tests in a Thermo Gravimetric Analyzer (TGA), suiphiding of metallic nickel granules demonstrated sulphur pick-up efficiency at low temperatures. As seen in Table 2, the CB5) sourced nickel granules were less active, i.e., they sulphided at considerably slower rates than either the "A" or "C" nickel granules.

Subsequently, in each case the three sources of nickel granules after sulphiding, were carbonylated in mini-pilot plant reactors, either in a packed bed reactor or in a rotary kiln reactor. The results are summarized in Table 3. Again, the "B" sourced nickel granules reacted more slowly with the carbon monoxide to fonn nickel carbonyl than the other two sourced nickel materials.

In test CS, impure 95.S%Ni granules produced from granulated nickel matte that had been roasted in a commercial fluid bed reactor at 1100" C and then reduced in a commercial fluid bed reducer with hydrogen at around 800° C, was first sulphided at 60° C for 6 hours in a nitrogen atmosphere with a HzS gauge pressure of 300kPa. This product was subsequently charged in a packed bed and subjected to reaction with carbon monoxide at essentially atmospheric pressure. Additional H2S had been added to the carbon monoxide inlet gas to the reactor representing, in total, a pickup of sulphur of 1-7 wfw % of the nIckel charge, and the nickel carbonyl gas strength, as measured by a UV analyzer, averaged around 6 v/v % for most of the reaction period-The product gases from the reactor were passed through the decornposer described in Example 2. The nickel powder product had a bulk density of 055g/ce, but an elevated, undesirable sulphur content of 1.29 w/w %. The residue analyzed 338% S. ENample 2: Pecompositiun of Nickel Carbonyl and Collection of the Nickel Powders In a series of tests, a carbon monoxide gas stream containing varying concentrations of nickel carbonyl gas, was passed through a minipilot plant decomposer reactor chamber, 12 cm in diameter and 75 cm long held at various temperatures and fed at vadous flow rates to produce nickel powders, and the nickel powders were collected in a collection box 30 cm in diameter and 30 cm long held at various temperatures.

Table 3

Mini-Pilot Plant Tests; Sniphiding and Carbonyla don of lilgh grade Metallic Nickel GrarniLes; Materials "A', "B" and "C" Snlphiding Carbonylation Sample Sample H2S Temp. Time, wiw % Tem Time, Extrac-4w %S Density Average wtw YeS ID sIze, g Pres-°C Hours S DC Hours lion % in product size of in stre added Nickel product g/ee product Residue PSI microns ________ 2800 30 20 8 Oil 40 48 72 0.06 112 2.40 025 * Ar 2800 30 -20 8 0.08 55 48 70 0.02 0.72 1750 0.22 A9 2800 30 20 8 0.11 50 0.06 035 0.95 0.25 A] 0" 600 45 60 4 OAO -25 48 0.06 1.99 3,60 1.63 Ai1' 2800 -30 50 8 0.16 50 -48 0.05 0.67 2MB 0.54 ____ ____ -. ___ ___ ___ ___ ___ SI ____ ____ ____ ____ B4' 3800 21 65 8 0.10 55 48 0.04 0.70 2MB 0.17 35* 3800 21 50 8 0.12 50 2 0.06 0.65 1.80 019 _____ ____ _____ ____ ____ ____ 85 _____ 7 cs' oC 45 60 6 1.68 60 45 ______ 129 0.55 1.50 3.38 Rotary kiln reactor Packed bed reactor + Continuous high strength 1128 (in CC) was introduced from the start of carbonylation (5 0cc/mm of 8% 1123 in CD) ++ Continuous low strength lI2S (in CO) was introduced after 10 hours of cariDonylation (1.9cc/mm of 8°/c U2S in CC)

Table 4

Decomposition of Nickel Carbonyl awl Collection of the Nickel Powder ipuseTThñcke1 Nickel Collection flog Density of Temperature Carbonyl Carbonyl Temperature Powder Remarks Feed Rate Strength, °C g/cc guam %Ni (CO)4 be 399* 8.5 16-5 WI' (--25°) N/A Liquid carbonyl collected in the box and agglomerate ci much of _pder.

355 10.8 21.2 170 kS Noliquicl

_ _

360 osJ1ffII carbonyl * A smaller mini-pilot plant decomposer was employed in this first test: 5 cm in diameter and 60 cm long.

The results of these tests, summarized in Table 4, clearly demonstrated the importance of controlling the temperature in the powder collection box in order to prevent re-carbonylation of the product nickel powder. By holding the temperature above 120°C the production of liquid nickel carbonyl in the collection box was avoided, while 99+% of the gaseous nickel carbonyl was decomposed yielding nickel powders and a carbon monoxide suitable for recycle to the reactor chamber Example 3: Treatment of an impure Nickel Matte Feed material A laboratory-sized sample of nickel matte analyzing 59.8% Ni, 10.5% Cu, 0.9% Co, 3.2% Fe and 21-0% S by weight, was roasted at temperatures starting at around 650°C and gradually increased to 1050°C for essentially complete elimination of the suiphide sulphur. The resulting oxide calcine was subsequently reduced with hydrogen at a temperature of 4 50°C. A 250 gram sample of the reduced material was charged to a packed bed reactor and reacted with carbon monoxide gas at 60°C, without arty sulphiding pre-activation, at 50°C, but with excess activating hydrogen sulphide amounting to a total of some 6.5% by weight of the metallic charge added to the carbon monoxide. The reactor product gases were fed directly to a heated tube decomposer which recovered the nickel in solid plated form. Without the pre-activation of the metallic charge, the gas strength in the reactor product gases was very low at about 2. v/V % nickel carbonyl, while the nickel product plate was high in sulphur at 2.2 wfw % as a result of excessiye H23 presence in the Co. This test shows that while a measure of pie-activation of the metallic charge is useful, the amount of activating H23 gas added to the carbon monoxide during carbonylation should be very much reduced.

Example 4: Treatment of an impure high-nickel Nickel Oxide Feed material 500 kilograms, of granular nickel oxide containing 77 w/w % Ni, containing minor quantities of cobalt, iron and sulphur was fed to a pilot plant rotary kiln reactor of about 46 cm in diameter, a heating zone 200 cm long, and a cooling zone, at a feed rate of about 1 kilogram per hour. The feed was reduced with hydrogen gas at a temperature of 425°C in a continuous manner with retention in the hot reducing zone of about 2 hours. The nickel, oxide was 90% reduced. 300 grams of this 90% reduced material, was thither reduced to completion in a small laboratory packed bed reactor at 425°C, some pre-sulphidrng with H2S. at 50°C was carried out, and the sample was then subjected to atmospheric carbonylation at 50°C. Continuous activation of the nickel was effected by continuous addition of hydrogen sulphide with the carbon monoxide. After 30 hours, some 90% of the nickei was extracted. However, as an excessive amount of activation sulphur had been added totalling some 0.73% of the metallized feed; the product nickel powder had an undesirable elevated content of sulphur of 0.52%.

In a second test, more sulphur was added during pre-sulphiding and less hydrogen suiphide was added to the carbon monoxide incoming gas, but also only after some 10 hours of initial carbonylation. The metal product powder had an acceptable low-sulphur content of 0.08 w/w %, as seen in Table 5. However, the degree of nickel extraction after 28 hours had dropped to 60%.

Table 5

Mini-Pilot Plant Tests; Reduction, Sulphithng and Carbonylation of high grade Nickel Oxide Granules; Material "B" SilpIiiding Carbonylation Sample Sample Reduc'. -1125 flTemp Time, % wlw Temp. Time, Extraction % wlwS Density Average Ye w/w ID size, g Temp. Pressure °C Hours S °C Hours fl in product product size of S in C PSI added g/ee product Residue microns D1+r 300 425 30 50 6 0.73 50 30 0.52 DC DC 2,10 D2÷÷ 00 425 30 -50, 16 0.85 50 28 60 0.08 DC DC 1.90 4'* Packed bed reactor + Continuous high strength H2S (in CU) was introduced from the start of carbonylafion (50cc/nib of 8% }12S in CU) Continuous low strength 1-125 (in CU) was introduced after 10 hours of carbonylation (1.9cc/nun of 8% 1-125 in CU) cc ExampleS: Processing of impure Nickel Matte for the production of refined carbunyl Nickel Powder, in mini-pilot plant reactor in a series of tests, a granular nickel matte containing substantial quantities of copper and iron impurities, obtained from a commercial nickel smelter was roasted in a pilot plant fluid bed roaster of 20cm diameter, at temperatures between 1070° C and 1100° C The resulting caleine, material "F", in Table 1, contained 59%Ni, 16%Cu, 09%Co, 4%Fe and less than 0.1%S. This calcine was subsequently reduced with hydrogen at temperatures between 400°C and 500°C, subsequently sulphided with H2S under varying conditions, and reacted with carbon monoxide at 50° C to 55° C and at essentially atmospheric pressure, i.e., below I OOkPa, and in most cases below about 35kPa in a mini-pilot plant carhoiiylation reactors. The gases exiting the reactors containing nickel carbonyl were directed to the mini-pilot plant powder decomposer held at 400° C (except in Test ES). The nickel and iron extractions, sulphur analyses of feed, product and residue, and density of product powders are summarized in Table 6? In all cases, carbonylationlexttactions were still proceeding when the tests were stopped.

In test ES, all of the activation sulphur was added continuously as 1123 to the incoming CO gas stream, which resulted in high pick-up of sulphur and high nickel extraction-However? a considerable proportion of the added sulphur ended up in the product nickel plate (22% w/w 3).

In test E6, activation sulphur was added to the reduced metal by reacting a gaseous mixture of 9Ovfv% H2 /lOvtv% SOB, with the metal prior to carbonylation; and further addItion of HS gas was added during carbonylation. It is seen in Table 6 that nickel extractions improved with the higher level of sulphur additions, and that presulphiding with no subsequent addition of 1123 to the CO stream yielded nickel powder low in sulphur content. It is believed that the higher sulphur levels tie up more of the copper impurity thereby "freeing" more of the nickel for reaction with the carbon monoxide. Furthermore, it is also believed that reduction at the higher temperature of 500°C suppresses, to some degree, subsequent extraction of the iron impurity.

Table 6

_______ -Mini-Pilot Plant Tests: Reduction, Sulpj4thng and Carbonylation of Jmpure Matte Calcine Granules Material "E" Suiphiding Carbonylation ample Sample educ 1125 Temp. Time, % wtw Time, Extraction %vv/wS Wensity Average wlw%S ID size, g Temp. Pressure °C Brs S added t Hrs. wlw h product size of in PSI to metal product glec product Residue Ca]c&d Nickel iron microns 250 425 15 50 0 50 48 90 70 220 DC DC 838 E6 2000 450 5 350 8 0.82 50 48 47 58 020 0.80. 0.85 1.20 B?' 3000 425105 50 8 2.19 If 44 67 66 0.05 1.26 1.10 47 3000 --450 105 50 8L26 55 35 60 50 0,03 0.40 2.10 237 B9 3000 425 1O5 50 8 1.71 55 4 -70 61 03 0:50 1.40 3.81 BID' 1500 425-500 55 50 1 8 1.00 50 4s 47 10 0.10 1.73 150 1 ElY 1500 500 55 50 8 0:86 50 70 53 10 0.20 1.38 1.20 1.30 _____ -3000 425 105 50 8 1.66 50 1 31 0.20 0.21 0.90 260 _____ 406 500 100 8.5 5.52 S048 j 53 11 0.03 2.02 OSj -9.20 Rotaiy kiln reactor Packed bed reactor Coutbuons high strength H28 @n CD) was introduced from the atast of carbonyiadon (5Ccc/miri of 8% 1-J2S th CD) Continuous low strength 1-128 (in CD) was introduced after 10 hours of carbonylation (1 9cc/mm of 8% H2S in 00) psi pressure of hydrogen sulphide repeated 17 times DC-Deposit plated onto a copper ttthe Example 6: TGA Tests related to the processing of impure Nickel Matte products Comprehensive series of TGA (Thermo Gravimetric Analyzer) tests were carried out on impure nickel oxide/calcine granules to study the effects of reduction temperature, and of varying the degree of low4emperatUre pre-sulphiding on subsequent nickel and iron carbonylation extractions Material tth", similar to that of Example 5, was the source of feed for these tests. Another series of tests was carried out on material CCF) as the feed Reduction temperatures were varied, pure hydrogen was employed for reduction, in one series on Material "F" while addition of H20 to the hydrogen gas in another test series on material "F" was carried out.

Fre-sulphiding was effected in all cases at 50° C, and carbonylation was carried out at atmospheric (lOOkPa) pressure and 50° C, except in tests E16 arid 1321 where carbonylation was carried out at 30° C-The results with material "B" are summarized in Tables 7 arid 8, and in Figures 2 and 3-It can be seen that nickel carbonyl extraetion were higher with the nickel oxide/caleine IS reduced at the lower temperature of 425° C as compared to 500° C-Also, nickel extractions were higher at the higher sulphur levels, for example, with the 2%w/wS yielding a 74% extraction and &5%wIwS yielding 88% for material "F" in the same time period) (Test F4 versus F5). Tests E17, 1120 and 1123, which yielded nickel extractions as high as 91%, are characterized by smaller test samples On the other hand, higher reduction temperature coupled with the higher sulphur addition, E23, suppressed iron extraction while yielding a high nickel extraction. In comparing iron extractions, there is a notable drop to about one-half, between the higher-iron feed material "F" and the lower-iron feed material "F".

The most surprising results with beneficial implications for commercial applications, are evident in tests Fl 1 to Fl6, in which iron extraction is virtually completely suppressed by carrying out the preparatory reduction step in a hydrogen gas containing H2O vapour.

Also some surprising results with important processing implications are depicted in Figure 2. When the reduction of the nickel oxide/calcine was carried out in pure hydrogen, the prc-sulphiding operation was distinctly slowed down as the reduction temperature was increased. However, when the reduction was carried out with hydrogen gas containing H20, subsequent suiphiding was extremely rapid.

It should be noted that the TGA Tests provide "relative" results as distinct from "absolute" results, particularly with regard to rates of reaction (Le. reaction times) which rates depend to a large extent on the equipment configuration, on the selection of solid sample sizes and on gas flow rates.

Example 7: TGA Tests related to the processing of impure Nickel Matte of the lower iron content, Material "F" Another comprehensive series of TGA tests was carried out on the impute nickel oxide/calcine granules Material ccF in which a range of weaker hydrogen gases diluted with H70, were employed for reduction, and in which the low-4emperature activation sulphur levels were varied.

Material "F", Table 1, an impure matte calcine analyzing 62%Ni, l2%Cu, 2%Fe and 001%S, was produced in the laboratory by tray roasting of granulated matte feed at temperature up to 10500 C While reduction temperatures gas strengths and sulphiding additions with f1S were varied, except in one test wherein suiphiding with elemental sulphur was attempted, the conditions for carbonylation at atmospheric (lOOkPa) pressure and 50° C, were maintained constant. The results are swmnarized in Tables 9 and 10 and depicted in Figures4and5.

It is seen that the lower reduction temperature of 42541 C yielded higher nickel and iron extractions than at the higher reduction temperatures, in the same period of carbonylation, as was already demonstrated in earlier examples. Optimum level of activation sulphur is around 45w/w% S for material "F". Lowering the gas strength of reduction by the presence of 1120 slowed the nickel reaction rate modestly. Most significantly, iron extraction was drastically lowered by the employment of the humid gaseous mixture of 30% v/v 1120 / 70% v/v HzO during reduction. Furthermore, results summarized in Table 10 show that increasing sulphur above the 2% level helped suppress iron extraction, and that pre-sulphiding with H23 gas at temperatures between 70° C and 135° C, and, preferably, between 100° C and 120° C, yielded the best nickel extractions.

The tests carried out in Example 7, demonstrated that nickel products low in iron can be produced from impure matte calcine containing some 2 w/w % iron as compared with the impure matte calcine treated in Example 6, which contained the higher levels of iron.

Comparative results are summarized in Table 10 of treating 2w/w%Fe materials with those of Table 8, of treating 4w/w%Fe material, wherein the reduction were carried out with gases 0% v/v H2O/ 70% v/v 112. Fable 9 also demonstrated that pre-sulphiding by addition of elemental sulphur was not satisfactory

Table 7

TGA Test3*i Reduction, Pre-Sul hidin and Carbon lation of Impure Matte Calcine Granules; Materials "E" Sample Sample Reduc Pressure Temp Time, wlw Temp. Time, Extraction %S in ID size, g Temp. PSI °C Bonn D/ 5 °C Hours % {* Residue DC added Nickel Iron E14 5,5 425 30 50 1.5 -6.00 50 44 87 35 fli2.20 5.6 500 30 50 11.0 6.00 50 42 79 29 13.00 E16 5.6 425 30 50 2.0 6.00 30 24 73 22 14.00 E17 L6 425 30 50 1.5 00 50 16 91 31 15.40 E18 5.5 425 30 50 0.5 200 50 44 -7449 7.10 E19 5.5 425 30 50 1.0 4.00 50 60 79 38 14.4 E20 2.0 425 30 50 1.2 6.00 50 44 87 35 15.1 E21 53 425 30 1 0.2 1.00 30 8067 54 2.50 L E22 5.5 500 30 5Q 3.5 2.00 50 24 42 31 3.90 E23 10 J 500 30 50 9 6M0 50 23 91 7 14.90

Table I Continued

TGA Tests: Reduction, Pre-Suiphiding and Carbonylation of impure Matte Calcine Granules; Materials "F" ______ _______ _______ Suiphiding ____ ____________ ---Sample Sample Rethc. Pressure Temp. Time, why Temp. Time, Extraction w/w %S ID size, g Temp. PS! °C Hours % S °C Hours % In ________ °C -. _______ added _______________ Nickel Iron --Residue F4 5.5 425 30 50 OA 2.00 50 44 7421 4.47 F5 55 425 30 50 1.0 4.50 50 44 88 22 6.20 F6 5.5 425 30 flso 1.3 6.00 50 68 77 8 7.24 P7 5.5 500 50 10.0 4.50 50 44 88 15 7.70 PS 5.5 500 30 50 16.0 6.00 50 44 74 12 730 P9 5.5 500 30 50 8.10 4.00 50 44 82 14 5.65 P10 5.5 500. 30 50 905 4.50 50 44 84 5 -6.10 P11t 5.5 500 15 50 1.50 2.00 50 44 69 13 NA ir 5.5 500 29 50 LOG 4.50 5044 75 ND NA P13t 5.5 500 29 100 033 3.00 50 44 79 ND NA F14 5.5 500 29 120 0.23 3.00 50 79 ND NA V15 5.5 500 29 135 0.20 3.00 50 44 70 ND NA 5.5 500 29 150 0.12 3.00 50 L44 51 ND NA

ND Not deec table

-H Reduction whh 70% v/v -30% v/v 1120

TableS

TGA Tests Carbonylation (Atm, 50°C) of Reduced Matte Icine - (Sample "E" with 4% Fe), Effect of varrylng reducing gas strength, oxidation Potential and reduction temperature, and of varrying suiphide activation IeveI $uiphidin level - &s% j 60% 6M% Feduction Reduction atm Temperature Reduction atm 50% H20150% Reduction ttm 100% H2 30% H20170% H2 ______ _____ __ _ -. iilili pe size -P9 IL fl fl __ Extraction time, i-tours 90 ______ 44Q 605] 444 ________ _____ -- * Ni extraction (%) -6Th10 ___ 74% 79% 86% _____ ___ Fe extraction 425 ___ ___ Sn 35% ______ ___ Extraction time_I-louis 140 60.0 24.0 41.0 425] 41.0 44.0 440 _____ Ni extraction * (%) 31% 45% 42% 65% 79% 61% 71% 61% _____ -Fe exinction 500 29% _% 31% 36% 29% 30% 23% -18% ____ Extraction lime. Hours. _____ _____ ______ 44.0 _____ _____ Ni extraction I H ___. --__ __ __ Fe extraction _.19% _ * Suiphiding at 100°C and atmospheric pressure -AlL other suiphiding at 50°C and 15!SI pressure -- -------r -1_ ---

Table 9

TGA Tests: Carbonylation (Atm., 50°C) of Reduced Matte Calcine (Sample "F" with 2%Fe); Effect of varying reducing atmosphere and reduction temperature, and of varying sniphide activation levels (1%S to 6%S) at 50°C ulhljyel --- 4.5 at % elemental Sulfur level 1.0% 2.0% 4.0% 4.6% 6,0% 3.0%wl. S 3.O%wt. S 3.0%wt. S 46%wt. S sulFur --Reduction tern peratufe Reduction attn Reduction atm Reduction elm Reduction aim Reduction atm C Reduction atm 100% li 10%H50-90% H2 70%J-120-B0'/u Ft 30%U20.70% 11a 30%l-120.7O% l 100% 112 _plee TI SJ. J. Th Extraction lime, Hours 44 44 aa __________ __________ 44 24' Ni extraction I __fl5L..__ 6% _____ 85% -______ Fe extraction - ____ "4 Extraction limeHoors -1- 44 44 44 44 -44 ___________ 141 extraction I (N 68% 63% ______ 75% ______ Fe extraction 500 JJ_ 5% 12% 26% oe% -NO -1W ______ -Reaction was "dead" after 24 hours.

ND -Not detectable

Table 10

TGA Tests: Carhonylation (Atm., 50°C) of Reduced Matte Calcine (Sample "Ft' with 2%Fe; Reduction effected with higher oxygen potential gas (30% H20 in hydrogen) at 500°C7 Effect of varying sulphide activation levels (2%S to 4.5%S) and temperatures (30°C to 150°C) Sulfifl ___ ___ ____ L_L witN HaS gas JfL_ rnt -iorc i2ot,c not çyr so-w ___!L_.

SuIlicling P aauxçtmc a3tottPt atmstat u4msfdc a3nathet evroetc nsçecft 15 -iernp C Sulfur level 2-0% _Q7, 317% 50% 3.0% -3.0% 50% ati Etiraction (inie, _ __: ______ I FeextraclioIt(%) _!&- _-- ±fL_.... 11% + Reactor was heated up betwaen 30-70°C and sulfiding was done during the temperature rise

ND -Not detectable

Example 8: Tests related to the processing of an intermediate Niclce1CobaJt Hydroxide material pro dueS by acid leaching of a liinouitic laterkte ore A series of TGA tests was carried out to establish optimum processing conditions for the extraction and recovery of refined nickel from an intermediate nickehcobalt material, "0" in Table I. Reduction temperature, degree of suiphiding with H23 gas, pressures and times employed for carbonylation were varied while pure hydrogen was employed for reduction and temperature for carbonylatioii was maintained at 30-85°C. The results are summarized in Table 11 and depicted in Figures 6 and 7. Jt is demonstrated that nickel hydroxide intermediate with 32 w/w % of nickel and 4.5 w/w % of cobalt yields some 50% or less of its nickel to the formation of nickel carbonyl at atmospheric reaction pressure and with no sulphur activation, even alter extended carbonylation reaction times. However, increasing the reaction pressure moderately to 700kPa, even with no sulphur activation, results in nickel extraction of some 90% in as little as 8 hours.

Pre-suiphiding with H2S at the lower temperature of 50°C, provided a high nickel extraction of 78% in 7 hours at a pressure of only lOOkPa, in Test 011, described in Table 11, and depicted in Figure 7 In other tests, G26 and 030, the nickel extractions at 100 kPa reached as high as 74% in 42 hours.

Additional tests were carried out on larger laboratory samples of 20grams, employing a packed bed reactor for the reduction, for the low temperature sulphiding with H23 and for the carbonylation, wherein the carbonylation temperature was either 50°C or 30°C and carbonylation pressure was at 100 kPa or under As seen in test OT-3, a high extraction of nickel was achieved at a carbonylation pressure of 100 kPa and nickel was preferentially carbonylated in comparison with the cobalt, thereby raising the Ni:Co ratio from 7.2:1 in the feed to over 700:1 in the nickel product plated after decomposition. Carbonylation at 70 kPa in test GT-4 yielded nickel extraction of 59 % in 40 hours, and the nickel to cobalt ratio was increased to 1700:1 in the product These extraction results are decidedly better than those achieved in the TGA tests, no dOubt due to the heifer gas-solids contact Although this disclosure has described and illustrated certain preferred embodiments of the invention, it is to be understood that the invention is not restricted to those particular embodiments. Rather, the invention includes all embodiments which are functional or mechanical equivalence of the specific embodiments and features that have been described and illustrated.

Table 11

ICA Tes ts Reduction, Suiphiding and Carbozylation of Nickel-Cobalt Hydroi d e; Material "G" Sulphidin Carbonylation Sample Sample Reduc. IReduc, H2S Over Temp. Time, % S Pressure Temp. Time, Extraction ID size, g Temp. Time, Pressure t}Trs. added PSI °C firs. do }Tours PSI to metal Nickel 31 3,30 300 40 --0.00 iSO 30 22 84 10 32 3.30 350 5 --0,00 150 30 18 8234 33 3,30 400 2 ---0.00 0 50 63 50 23 34 330 400 2 _____ ___ -0.00 15 30 15 54 2 3.30 400 2 --o.ooj 100 30 12 84 49 0 ____ ____ ____ ____ --___ ___ --_____ ___ ___ ___ _____ 36 330 400 2 ---0.00 100 50 50 87 35 37 3.30 400 2 --ftOO 150. 30 8 88 24 38 3.30 400 2 --0,00 150 50 8 84 24 39 3.30 400 2 --0,00 150 85 18 82 34 * 310 330 400 2 15 50 020 0.60 hbOc 50 20 84 23 -311 3.30 400 2 15 50 0.55 20 iS 50 7 79 18 012 3.30 400 2 15 50 1.05 TOO 15 50 7 41 20

_____________________ I

Table H ContcL

TGA Tests; Reduction., Suiphiding and Carbonylation of Nickel-Cobalt Hydroxide; Material C" SuIphijg, ________ __________ Carbtion Sampi Sample Reduc. Reduc, H2S Over Temp. Time, % S Pressure Temp. Time, Extraction e ID.sirze, g Temp. Time, Pressure °C Rn, added ESI °C Rn. % -% Co DC flours Psi to metal Nickel 325 330 400 2.00 ---0,00 15 50 22 23 7 326 3.30 400 2.00 15 5D0Q 2.00 15 50 42 74 21 327 3.30 400 2.00 15 50 0.55 2.00 15 50 22 64 16 G2844 3.30 400 2.00 --15 50 0.30 --1.50 ± 15 50 22 50 13 329' 3.30 400 2.00 15 500.20 1.00+ 15 50 22 39 7 -p 330 3.30 400 2.00. 15 50 1.40 300 --15 50 22 -61 9 Sulphur level increased by addition of 1128 gas in GO, 0.02% 1123 -Balance GO, during carbonylation Sulphur level increased by addition of 1-125 gas in GO, 8% 1123 -Balance GO, dining carbonylation

Table 11 eontd

Mini-Pilot Plant Teat: Reduction, Suiphiding and Carbonylation of Nickel-Cobalt Hydroxide; Material "C" Suiphiding Carbonylation Sample ID Sample Reduc. Reduc. 1125 Temp. Time, % S Pressure Tern1 Time, Extraction Product analysis size, g Temp. Time, Over °C Hi-s. added PSI p C Tim'. _____ --________ °C Hours Pressu to % 04 % % %S re PSI metal, Nickel Co Nickel Co CaIc1' GT-1 20.00 450 5 ----O.öIP 150 50 48 sU"J 72.0 9.1 -

C -___ ___ ___ _______ -____ __ ___ ___ ___

GT-2 20.90 450 5 --0.00 100 30 8 90 -70.0 0.1 -GT-34 19.80 400 6 15 50 7 15 50 26 82 7 74.50.1 GT-C 400 -6 15 50 7 10 50 26 + Carbonylation for first 2 hours with 100% CO, then switch to 99%CO -P41128 for another 20 hours because of slow reaction.

Claims (10)

1. Claims 1. An improved method of reducing a mixed oxide composition comprising oxides of nickel, cobalt, copper and iron in a hydrogen atmosphere to produce a mixture of the respective metals, the improvement wherein said atmosphere further comprises water vapour at a concentration, temperature and time to effect selective reduction of said oxides of nickel cobalt and copper relative to said iron oxide to produce said metallic mixture having a reduced ratio of metallic iron relative to metallic, nickel, cobalt and copper.
2. 2. A method as claimed in claim 1 wherein said mixed oxide composition has an iron oxide content of no more than 4% w/w Fe.
3. 3. A method as claimed in claim 1 wherein said mixed metal oxide composition has an oxide content of no more than 2% w/w/ Fe.
4. 4. A method as claimed in any one of the claims I to 3 wherein said mixed oxide composition is a nickel smelter product.
5. 5. A method as claimed in any one of claim I to 3 wherein said mixed oxide composition is a nickel-cobalt leach product.
6. 6. A method as claimed in any one of the claims I to 5 wherein said temperature is selected from 350°C to 550°C.
7. 7. A method as claimed in claim 6 wherein said temperature is about 500°C.
8. 8. A method as claimed in any one of claims I to 7 wherein said atmosphere further comprises an inert gas.
9. 9. A method as claimed in any one of claims I to 8 wherein said atmosphere further comprises a gas selected from carbon monoxide and carbon dioxide.
10. 10. A method as claimed in any one of claims I to 9 wherein said atmosphere comprises a hydrogen: water ratio selected from 10:1 to 1:1.ii A method as claimed in claim 10 wherein said hydrogen: water ratio is selected from 3:1 to 2:1.12.A process as claimed in any one of claims I to 11 wherein said hydrogen atmosphere 10-50% v/v water.13.A process as claimed in claim 12, wherein said hydrogen atmosphere comprises 25-35% v/v water.14 A method as claimed in any one of claims I to 13, wherein the mixed metal oxide composition is a solid material.