US3876415A

US3876415A - Concentration of nickel values in oxidized ores

Info

Publication number: US3876415A
Authority: US
Inventors: Malcolm Charles Evert Bell; James Alexander Evert Bell; Ramamritham Sridhar; Herman Frederik Bakker
Original assignee: International Nickel Co Inc
Current assignee: Huntington Alloys Corp
Priority date: 1972-02-09
Filing date: 1973-01-12
Publication date: 1975-04-08
Anticipated expiration: 1992-04-08
Also published as: ZA73533B; GB1401718A; AU5151773A; FR2171380A1; FR2171380B1; CA965961A; DE2306475A1; DE2306475C3; DE2306475B2; BR7300943D0; AU447098B2; JPS4889121A

Abstract

Concentrates of nickel and/or cobalt are continuously recovered from oxide ores containing same by preheating the ore to at least about 850.degree.C., then mixing the ore with at least one chloride selected from the group consisting of alkali metal chlorides, alkaline earth metal chlorides and iron chlorides and holding the mixture at a temperature between about 900.degree.C. and 1100.degree.C. in a hydrogen-containing atmosphere having a reducing potential equivalent to a CO:CO.sub.2 ratio between about 1:2 and 4:1 to convert and concentrate a preponderant part of the nickel and/or cobalt to the metallic state and recovering the metallic concentrate.

Description

United States Patent [191 Bell et a1.

1 1 Apr. 8, 1975 1 1 CONCENTRATION OF NICKEL VALUES IN OXIDIZED ORES [22] Filed: Jan. 12, 1973 121] Appl. No.: 323,091

[30] Foreign Application Priority Data Feb. 9. 1972 Canada 134358 {52] US. Cl. 75/2; 75/82; 75/113 [51] Int. Cl. C22b 1/08; C22b 23/02 [58] Field of Search 75/82, 1. .5 BA, 2

[561 References Cited UNITED STATES PATENTS 1.480.212 1/1924 Lamothe et a1 75/82 1.487.145 3/1924 Caron et a1. 75/82 X 2.473.795 6/1949 Hills et a1 1. 75/82 2.733.983 2/1956 Daubenspeck..... 75/82 X 2.850.376 9/1958 Queneau et al.... 75/82 2.998.311 8/1961 Hills et a1 75/82 3.272.616 9/1966 Queneau et a1 75/82 X 3.311.466 3/1967 Curlook 75/82 X 3.453.101 7/1969 Takahashi et a1 75/82 X 3.656.934 4/1972 Curlook et a1 75/82 3.658.508 4/1972 Weir et a1. 75/82 X 3.667.933 6/1972 Heitmann 75/82 X 3.701.647 10/1972 Yasui et a1 75/3 3.725.039 4/1973 Jepsen 75/82 X FOREIGN PATENTS OR APPLICATIONS 848,377 8/1970 Canada 2.042.076 5/1971 France Primary E.\'aminerRobert V. Hines Assistant Examinen-Thomas A. Waltz [57] ABSTRACT Concentrates of nickel and/or cobalt are continuously recovered from oxide ores containing same by preheating the ore to at least about 850C. then mixing the ore with at least one chloride selected from the group consisting of alkali metal chlorides. alkaline earth metal chlorides and iron chlorides and holding the mixture at a temperature between about 900C. and 1100C. in a hydrogen-containing atmosphere having a reducing potential equivalent to a COzCO ratio between about 1:2 and 4:1 to convert and concentrate a preponderant part of the nickel and/or cobalt to the metallic state and recovering the metallic concentrate.

23 Claims, 1 Drawing Figure CONCENTRATION OF NICKEL VALUES IN OXIDIZED ORES The present invention pertains to the treatment of nickeliferous oxide ores, and more particularly to the beneficiation of nickel-containing oxide ores.

Nickel-containing oxide ores form the largest known reserve of nickel values. However, these ores are not amenable to conventional beneficiation techniques. as are sulfide ores; and, in most instances, the entire mass of the ore must be hydrometallurgically, pyrometallurgically or vapometallurgically treated to recover the nickel values. Treatment of the entire ore mass is expensive in terms of both capital and operating costs.

Nickeliferous oxide ores are not amenable to conventional beneficiation techniques since nickel is present in the ore merely as a dilute substitutional constituent and not as a separate and distinct mineral. Most frequently, oxide ores are a mixture of a highly weathered (or laterized) portion and a less weathered portion. The more weathered portion of oxide ores'can contain up to about 50 percent iron, or even more, and nickel is associated with phases rich in iron or magnesium. In less weathered ore, nickel is contained in silicate minerals. The very nature of these ores is such that they do not respond to physical separation techniques such as flotation or magnetic separation and must be chemically and/or pyrometallurgically treated to concentrate the nickel values.

Nickel has been recovered from nickeliferous lateritic ores by smelting the entire mass of the ore in the presence of controlled amounts of reductant to pro duce a ferronickel product. ln a very similar process. nickeliferous lateritic ores are smelted in the presence of a controlled amount of reductant and in the presence of calcium sulfate to produce a ferronickel matte from which nickel can be subsequently recovered. Nickel-containing limonite has been hydrometallurgically treated by leaching with sulfuric acid at elevated temperatures and pressures to selectively dissolve the nickel values, and the resulting pregnant leach solution is treated for nickel and cobalt recovery. Nickel has also been recovered from nickel-bearing lateritic ores by selective reduction followed by leaching with an ammoniacal ammonium carbonate solution from which nickel and cobalt values were recovered. All these processes have in common the same shortcoming, i.e., the entire mass of the ore must be treated to recover the nickel values.

Recently, it has been suggested in Canadian Pat. No. 786,269 to mix nickeliferous lateritic ores with controlled amounts of carbon and a halide of alkali or alkaline earth metals and to heat the mixture to tempera tures between about 750C. and l,OOOC. to segregate the nickel values in a metallized phase. By this treatment, nickel values along with iron values are deposited on the solid carbonaceous reductant and the deposited nickel values are recovered by magnetic sepa ration or by flotation after the surface of the deposited nickel values has been activated for flotation. As practiced, this process has been quite erratic in that nickel recoveries and the grade of the concentrate have varied quite widely. Another problem with the process described in Canadian Pat. No. 786,269 is that it is designed to be conducted on a batch basis with indirect heating which severely limits production rates and results in increased capital and operating costs.

It has now been discovered that nickeliferous oxide ores can be treated in a special manner to place the ore in a condition where nickel values contained therein can be concentrated by physical means to provide a high-grade concentrate which contains at least about percent of the nickel values.

It is an object of the present invention to provide a process for concentrating nickel values contained in nickeliferous lateritic ores.

Another object of the present invention is to provide a process for continuously concentrating nickel values contained in nickel-bearing lateritic ores.

The invention also contemplates providing a process for treating nickel-containing oxide ores on a continuous basis to provide a high-grade nickel concentrate.

It is a further object of the invention to provide a process for the continuous treatment of nickel-containing lateritic ores by segregation roasting to provide high nickel recoveries.

Other objects and advantages will become apparent from the following description taken in conjunction with the Figure which is a front elevation, partly in section, of an arrangement of rotary furnaces that can be employed in the practice of the process in accordance with the present invention.

Generally speaking, the present invention contemplates a continuous process for beneficiating nickeliferous oxide ores to produce high-grade nickel concentrates. The nickeliferous oxide ore is preheated to a temperature above about 850C. The preheated ore is mixed with at least one chloride selected from the group consisting of alkali metal chlorides, alkaline earth metal chlorides and iron chlorides, and the mixture is held at a temperature between about 900C. and l,l0OC. in a hydrogen-containing atmosphere having a reducing potential equivalent to a carbon monoxide to carbon dioxide ratio (CO:CO between about 1:2 and 4:1 to produce metallized particles with a preponderant part of the nickel and/or cobalt values being concentrated therein. The metallized particles are recovered by physical means, e.g., flotation or magnetic separation, to provide nickel and/or cobalt concentrates.

All nickeliferous oxide ores, and even roasted nickeliferous sulfide ores, can be treated by the process in accordance with the present invention. However, if the nickeliferous oxide material contains large amounts of iron, large amounts of chlorides as consumed and lower grade concentrates are realized. Best results, in terms of reagent cost, nickel recoveries and concentrate grades, are obtained by treating nickeliferous oxide ores that contain, by weight, at least about 1.5 percent nickel, less than about 30 percent iron, and the balance essentially magnesia, alumina, silica, and moisture. Cobalt in the ore is generally recovered to almost the same extent as nickel, and it is understood in the following that reference to nickel also includes cobalt.

A salient feature of the process in accordance with the present invention is that the process is conducted on a continuous basis. Although the process can be conducted in other apparatus, such as in a multi-hearth furnace having rotating rabble arms for conveying ore from one hearth to another, it is advantageous in terms of capacity, process control and mechanical simplicity, to employ a rotary furnace. A single rotating furnace in which preheating and segregating zones are established can be employed but it is advantageous, for reasons described herein, to employ two rotating furnaces in tandem with one serving as a preheating and/or partial pre-reduction furnace while the other functions as a segregation furnace. One advantage of carrying out the process in two or more stages is to minimize the gas flow through the segregation vessel or the segregation portion of a vessel so that any chloride unavoidably lost from the process is concentrated in a small amount of off gas. This gas can be more economically treated to recover its chloride content thereby eliminating environmental pollution and to provide chloride for recycle thereby lowering the costs of the process.

The introduction of large quantities of gases, in addition to those generated in the segregation process, is deleterious to the recovery of nickel by the segregation process. The reduction reactions occurring during the segregation process are endothermic and require heat to maintain the proper operating temperature. The use of indirect heating to supply the required heat at the process temperature of about l,00OC. is costly and at present impractical on a large tonnage basis. The use of direct combustion heating introduces a large volume of gas into the reaction vessel thereby diluting the internally generated chloride gases and decreasing the efficiency of the process. Furthermore, the water vapor resulting from combustion makes it more difficult to carry out the chloridizing reactions. The process in accordance with the present invention minimizes the amount of diluting combustion gases entering the reaction vessel or zone of the reaction vessel in which the segregation process is being carried out. This objective can be achieved in part by minimizing the heat require ments during the segregation part of the process, by using a two-stage process in which dehydration, calcining and heating of the ore to the process temperature is carried out in one reactor or portion of a reactor. The chloride and a reductant, such as particulate carbon, are then added to a second vessel or distinct portion of the first vessel, to initiate the segregation part of the process.

It is possible to partially reduce the ore during the first or preheating period without adversely affecting the results obtained during the second or segregation period. This partial reduction further decreases the heat requirements in the segregation period by reducing the Fe O in the ore to Fe O, and FeO, and reducing part of the M to Ni, all of which are endothermic reactions that would otherwise have to be carried out during the segregation period. A still further method of decreasing the gas flow during the segregation reaction period is to preheat the combustion air to this reaction vessel or zone thereof, or to utilize oxygenfor the combustion of the fuel. Another further method of decreasing the heat requirements and concomitant flow of combustion products during the segregation stage is to preheat and dehydrate the chloridizing agent and preheat the reductant before their introduction to the segregation stage.

Turning to the FIGURE, there is depicted rotating furnaces A and B with the discharging end of furnace A and charging end of furnace B communicating with housing C. Heating furnace A is operated to preheat the nickeliferous oxide ore to predetermined tempera tures while rotary furnace B functions as a segregating furnace. Since the construction of rotary furnaces A and B are similar in most respects, like parts will be given like reference numerals except where there is a substantial difference in construction or function.

Rotary furnaces A and B comprise cylindrical steel shells l1 lined with a suitable refractory 12. Rotary furnaces A and B are elevated at a slight angle from the horizontal to facilitate the flow of particulate material from one end to the other. Rotary furnace A which functions as a preheating furnace, can be equipped with internal lifters to further facilitate the flow of particulate material through the furnace and to improve gas-solid contact between the particulate material and the furnace atmosphere. Motors 13 operate via pinion gears 14 which mesh with ring gears 15 to rotate furnaces A and B about their longitudinal axis. Steel tires 16, that are mounted on shells 11 and that ride on thrust bearings 17, stabilize rotary furnaces A and B.

The charging end of furnace A communicates with flue system 18 for discharging flue gases. The flow of such gases can be controlled by damper 19. Fresh ore is fed to furnace A from hopper 20 via conveyer 21. The discharge end of furnace A communicates with housing C, and an arrangement of baffles or slides 22 and 23 function to transfer preheated particulate material from furnace A to furnace B. The discharge end of furnace A is equipped with burner 24 which combusts fuel and air to generate heat for preheating particulate ore in furnace A. It will be noted that the products of combustion from burner 24 flow countercurrent to the flow of ore through furnace A to thereby provide more efficient heat exchange. Burner 24 can be operated either with theoretical air or an excess of a free-oxygencontaining gas or with a deficiency of oxygen, producin g a gas of controlled reduction potential. If the burner is operated under reducing conditions, air is admitted by side pipes at points downstream of the burner to combust the remaining combustibles in the gas and thereby obtain maximum fuel efficiency.

The charging end of furnace B communicates with housing C, and preheated material from furnace A is charged to furnace B via slides 22 and 23. Controlled amounts of chlorides, which can be preheated and dehydrated, from hopper 25 are admixed with preheated ore via screw conveyer 26 and slide 23. In a like manner, particulate carbonaceous reductant is admixed with the ore and the chloride from 27 via screw conveyer 28 and slide 23. The mixture of preheated ore, chloride and particulate carbonaceous reductant are maintained at reducing temperatures in furnace B by combusting fuel and free-oxygen-containing gas in burner 29. Burner 29 is operated so that the atmosphere within furnace B is reducing to nickel chloride and essentially non-reducing to ferrous chloride. The products of combustion from burner 29 flow concurrently with the mixture of preheated ore, chloride and particulate reductant. Concurrent flow of the products of combustion from burner 29 is an advantageous feature of the present invention since any chlorine or hydrogen chloride generated by the decomposition of the alkali metal chloride, alkaline earth metal chloride, or iron chloride is not immediately swept from the furnace but is allowed to reside in furnace B sufficiently long to promote segregation reactions. The discharge end of furnace B communicates with housing 30 that functions as a flue system with damper 31 and as a discharge hopper via valve 32.

In operation, fresh nickel-containing lateritic ore from hopper 20 is fed to furnace A via screw conveyer 21 and is preheated to a temperature of at least about 850C. as it is conveyed through furnace A countercurrent to the products of combustion generated by burner 24. Preheated ore is discharged on slide 22 to slide 23 while controlled amounts of chloride and particulate carbonaceous reductant advantageously preheated to a temperature up to l,lO0C. are added to slide 23 or directly to the rotating furnace. The mixture of preheated ore, chloride and particulate carbonaceous reductant is introduced into furnace B where a slightly to strongly reducing atmosphere and a temperature between about 900C. and 1,050C., e.g., between 920C. and 1,020C., is maintained. Burner 29 is operated from neutral to strongly reducing depending on the amount of solid carbonaceous reductant that is most advantageously employed for the particular ore being treated. Fuel, free-oxygen-containing gases and chlorides can be injected at a plurality of points along the segregation furnace to provide smooth temperature, reducing potential and chloridizing potential profiles within the segregating furnace. The products of combustion of burner 29 pass concurrently with the ore, chloride and particulate carbonaceous reductant through furnace B and are led to housing 30 to be discharged through flue 31. The mixture of ore, chloride and solid carbonaceous material travels through furnace B to housing 30 where it is fed via feeder 32 to means for cooling the mixture of ore, chloride and solid carbonaceous reductant under non-oxidizing conditions.

An important feature of the present invention is the preheating of nickeliferous oxide ores to a temperature of at least about 850C. in an atmosphere non-reducing to partially reducing to nickel oxide before adding chlorides and reductants to the ore. Advantageously, the ore is preheated to a temperature between about 920C. and l,O0OC. The process in accordance with the present invention can be conducted by preheating to lower or higher temperatures before additions of chlorides and solid carbonaceous reductants are made, but either lower nickel recoveries, and/or lower grade concentrates (i.e., less than about 6 percent nickel), and/or greater reagent losses and greater fuel consumption are encountered. If the ore is preheated to a lower temperature, more fuel must be burned to achieve the required temperature, and material amounts of the chloride decompose and the gaseous products of decomposition are swept from the furnace before entering into the segregation reactions whereby lowering both nickel recovery and the grade of the concentrate and increasing chloride losses. Higher preheat temperatures can be objectionable in that the ore can sinter rendering solid-solid and gas-solid contact less effective and increasing the risks of encountering reactions that place the nickel values in a highly refractory state. Preheating to temperatures within the foregoing ranges optimizes fuel consumption, particularly when countercurrent gas flow is employed in furnace A. It is advantageous, particularly with the higher iron ores, (25-35 percent Fe), to carry out partial reduction of the iron oxide to Fe O or FeO in furnace A in order to reduce the endothermic reduction heat that would otherwise have to be supplied in Kiln B. As discussed above, higher heat requirements and subsequent greater gas flows in Kiln B result in poorer results. The reduction potential in Kiln A should not be high enough to reduce over about 50 percent of the nickel, or poorer nickel recovery is obtained after treatment in furnace B.

After preheating the nickeliferous oxide ore, at least one chloride ofa group lAor group 2A element or iron chloride and aparticulate solid carbonaceous reductant are thoroughly mixed with the preheated ore, and the mixture is maintained at a temperature between about 920C. and l,O50.C. in an atmosphere that is substantially reducing to nickel chloride and substantially non-reducing to ferrous chloride. The chloride reagent is added to the ore in amounts, on a weight basis, between about 3 and 12 percent, advantageously in amounts between about 4 and 8 percent. Smaller amounts of the chloride can be added but nickel recoveries suffer. The chloride can be added in amounts exceeding about 12 percent, but any advantages gained by way of increased nickel recoveries are offset by the production of lower grade concentrates and by increased reagent costs. The best results in terms of nickel recovery and grade of concentrates are obtained when chlorides in amounts between about 4 and 8 percent are added to the preheated nickeliferous oxide ore. For similar reasons, solid carbonaceous reductant, such as coke, coal, charcoal, fuel oil, wood, and lignite, are added to and admixed with the preheated nickeliferous oxide ore. Again for best results in terms of nickel recoveries and concentrate grade, the carbonaceous reductant is advantageously added to the preheated ore in amounts between about 0.5 and 12 percent by weight of the dried, preheated ore.

As noted hereinbefore, the mixture of preheated ore, chloride and solid carbonaceous reductant is held at a temperature between about 950C. and 1,050C. in an atmosphere that is reducing to nickel chloride and essentially non-reducing to ferrous chloride. Advantageously, the mixture is held at a temperature between about 970C. and 1,020C. in order to insure high nickel recoveries and high grade concentrates while minimizing mechanical problems associated with sticking and minimizing fuel consumption. Under these conditions at least about percent, and in most instances about percent or more, of the nickel in the ore is reduced from the gaseous state to the metallic state and canbe easily separated from the ore by magnetic separation techniques or, after suitably activating the precipitated metal values, by flotation techniques. Although the length of time the mixture is held at these temperatures will vary from ore to ore, it has been found that, in most instances, residence times between about 0.5 hour and 2 hours are usually sufficient to insure nickel recoveries of at least about 75 percent.

The gaseous effluent from the second stage reactor can be cleaned in conventional wet scrubber to remove HC], FeCl and any traces of nickel chloride from the gas. The solution may be neutralized with a base such as limestone, and the calcium chloride-iron chloride solution dried and recycled for use. Alternatively, the solution could be neutralized with reduced ore.

In order to give those skilled in the art a better appreciation of the process in accordance with the present invention, the following illustrative examples are given:

EXAMPLE I A mixture of Indonesian ore from the island of Sulawesi was calcined at 1,000 C. in air for 6 hours to expel all structurally bound water. The calcined ore was subsequently mixed at room temperature with 6 weight per cent (granular) CaCl and 12% coke (82% C) ground to minus 48 mesh. This mixture was then fed at 1.2

7 kg/hr to an externally heated rotary kiln. In passing through the kiln the ore mixture was heated to 980C. to 1,000C. allowing a residence time above 940C. of one hour.

In test C, the hot partially reduced ore was fed to a segregating zone where 3% coke and calcium chloride, both based on the weight of the reduced ore, were added to the ore and the mixture was maintained at The kiln was continuously purged concurrently with 5 1,000C. for 1 hour. Test D was conducted under i ia gaseous mixture of 2 2 and 2- 'fl runs lar conditions except 5% coke along with 5% calcium were Carried out at different gas flowrates- The Product chloride was added to the hot calcined ore. The cooled was allowed to Cool to room temperature and ore from both tests was ground to pass through 325 ground through 200 mesh and magnetically Separated mesh and magnetic concentrates were recovered by at 4800 gauss in a Davis tube. The adverse effects of wet magnetic Separation in a Davis tube at 4800 gauss. high gas flowrates are confirmed by the results reported Th results f t st C and D are summarized in Table in Table l. I]

The flowrates and compositions of simulated com- TABLE II bustion gases were different to simulate single stage test A and two-sta e se re ation conditions test B l5 g g g Assay of Magnetic Concentrate N| Recovery Gas flowrate. lnlet Gas Composition. Wt. "/1 Ni '7: Fe /l Test moles/kg ore CO H O N Test C 22.8 7.75 58.1 89.3 A 29 l2 13 75 Test D 22 2 8 64.4 90.1 B 10 19 46 20 Based on weight of the reduced or calcined ore.

TABLE 1 Weight Assay of Materials. 71 Distribution. 9& '14 Ni Co Fe M gO Si()- C C1 Ni Co Fe Indonesian Ore 1.72 0.05 20.4 14.6 37.7 Calcined (1000C.1 1110 1.85 22.0 100 100 10a CaCl- 6 61.8 Coke 12 81.7 Product of Test B Segregated Ore 97.2 1.88 20.4 5.1 1.8 98.8 92.4 Magnetic Fraction 16.0 9.6 54.8 83.0 41.1 Non-Mag. Fraction 81.2 0.36 14.4 15.8 51.. Product of Test A Segregated Ore 102.0 1.78 21.0 .4 1 2 98.0 97 Magnetic Fraction 14.0 9.9 47.0 74.9 29.9 Non-Mag. Fraction 88.0 0.48 16.9 23.1 67.6

Based on the weight olthc calcined ore.

'l'hc proportion o1- the Ni. Co and Fe in the calcined ore that reports in the named fractions.

By comparing the distribution of nickel in the magnetic fractions in Tests A and B, it is evident that greater nickel recoveries are realized by minimizing gas flowrates without materially lowering the grade of the concentrate, as shown by the nickel assays of the magnetic fraction in Tests A and B.

EXAMPLE 11 This example confirms that a portion of the nickel values contained in oxide ores can be prereduced without materially altering nickel recoveries. An oxide ore containing 1.65% nickel, 0.3% cobalt, 29.7% iron, 10.9% magnesia, 24.4% silica and 1.68% chromium was employed in this example. In test C, the ore was prereduced at 1,000C. in an atmosphere having a reducing potential equivalent to a CO:CO ratio of 1:4 to reduce about 17% of the nickel values while maintaining 99% of the iron in the oxide state and to expel all structurally bound water. The ore for test D was calcined at 1,000C. to expel all structurally bound water.

EXAMPLE 111 This example confirms that higher grade nickel concentrates are recovered from ores having lower iron contents, even though nickel recoveries remain substantially constant.

ON gas mixture over the ore. After allowing for a reaction time of 0.5 hour at 980C. to 1,020C., the segregated ore was cooled to room temperature,

ground through 325 mesh and wet magnetically separated at 4800 gauss. Test conditions, grades and recoveries are tabulated in Table 111.

TABLE I11 Weight Analysis, Weight 7: Distribution, 7:

% Ni Co Fe MgO SiO C Cl Ni Co Fe Test E Gas Flow: 3 moles Co /kg, 2 moles H O/kg, 7 moles N lkg Australian Ore 1.65 0.15 14.5 4.6 54.4 Calcined Ore P 1.72 15.1 CaC1 5.7 61.8 Coke 5.7 81.7 Segregated Ore (1020C.) 100.1 1.68 13.6 3.7 O 7 98.4 90.2 Magnetics 6.5 21.8 40.1 82.3 17.3

TABLE III Weight Analvsis. Weight "/1 Distribution. "/f" "/1 Ni Co Fe M g SiO C C 1 Ni C 6 Fe Non-Magnetics 93.6 0.29 11.8 16.1 72.9 Test F Gas Flow": 4 moles CO. ./kg. 2 moles H O/kg. 5 moles N. ./kg Indonesian Ore 1.72 0.05 20.4- 14.6 37.7 Calcined Ore 100 1.85 22.0 CaCl 2 6 6.8 Coke 12 81.7 Segregated Ore (970C) 97.2 1.88 20.4 5.1 1.8 98.8 92.4 Magnetics 16.0 9.6 54.8 83.0 42.1 Non-Magnetics 81.2 0.36 14.4 15.8 51.3 Test G Gas Flow: 2 moles Co /kg. 3 moles H O/kg. 4 moles N. ,/kg Indonesian Ore (980C) 1.77 33.1 calcined Ore 100 1.90 35.5 100 100 100 CaCl: 7.4 61.8 Coke 7.4 81.7 Segregated Ore (980C) 98.] 1.92 35.7 0.4 0.3 99.1 98.6 Magnetics 26.0 6.0 58.4 82.1 42.8 Non-Magnetics 72.1 0.45 25.0 17.0 50.8

Based on weight of the calcined ore. d on the weight 61' Ni. Co and Fe contained in the calcined ore. (ins flows based on weight of ore.

EXAMPLE IV TABLE IV 850 to about 1,1000C; mixing the hot preheated ore which is at a temperature of above about 850C. with at least one chloride selected from the group consisting of alkali metal chlorides, alkaline earth metal chlorides, and iron chloride; maintaining the mixture of ore and chloride at a temperature between about 900C. and 1,100C. in a hot gaseous hydrogen-containing atmosphere having a reducing potential equivalent to a carbon monoxide to carbon dioxide ratio between about 1:2 and 4:1, at least a part of the heat to maintain the temperature of the mixture of ore and chloride being produced by combusting a fuel with a gas containing 7: Reductant' "/1 Chloridizer Magnetic Concentrate Non Magnetics Coke Coal CaCl NaCl FeCl Wt. 7H 7: Ni "/1 Fe 71 Nickel 71 Ni Recovery Ore Assay: 1.727! Ni. 16.471 Fe. 4.4671 MgO. 50.2% Sin 3.9% A1 0 5.0 5.3 9.6 15.2 59.4 83.9 0.31 5.0 4.0 13.1 13.2 61.9 91.3 0.19 4.0 4.8 5.1 27.5 56.5 79.5 0.38 5.0 5.8 6.6 20.8 49.8 76.3 0.46 5.0 2.0 2.0 7.7 18.4 52.7 76.1 0.48 5.0 2.9 2.9 6.6 20.8 49.8 76.3 0.46 4.0 1.85 1.85 6.4 17.0 48.8 75.3 0.38 Ore Assay: 1.72% Ni. 29.2% Fe, 11.4% MgO. 26.271 SiO- 5.0 5.0 21.6 8.9 60.6 91.1 0.24 5.0 5.0 20.5 8.5 54.1 89.1 0.27 5.0 2.5 2.5 11.0 15.8 69.4 88.7 0.25 5.0 2.5 2.5 12.1 14.8 66.3 88.7 0.26 4.0 4.0 10.5 14.9 49.3 79.3 0.46

Based on the weight o1- ore. Selectively reduced high iron ore puggetl with HCI.

Although the present invention has been described in free oxygen; and minimizing the combustion gas flow rate to less than about 30 moles of gas/kg. of ore to produce metallized particles with greater nickel values concentrated therein than obtained at higher flow rates; and recovering the metallized particles.

2. The process as described in claim 1 wherein controlled amounts of a particulate carbonaceous material are added to the preheated ore.

3. The process as described in claim 2 wherein the chloride is added to the ore in amounts, on a weight basis, between about 3 and 12 percent and the particulate carbonaceous material is added in amounts, on a weight basis, between about 0.5 and 12 percent.

4. The process as described in claim 3 wherein the chloride is added in amounts between about 4 and 8 percent.

5. The process as described in claim 3 wherein the mixture of ore and chloride is maintained at temperature by combusting fuel and preheated free-oxygencontaining gas.

6. The process as described in claim 3 wherein the mixture of ore and chloride is maintained at temperature by combusting fuel and oxygen-enriched air.

7. The process as described in claim 3 wherein the chloride additive is dehydrated.

8. The process as described in claim 7 wherein the chloride additive and the particulate carbonaceous material are preheated.

9. The process as described in claim 3 wherein off gases from the segregating stage are treated to recover contained chlorides and the recovered chlorides are used as the chloride additive. t

10. The process as described in claim 3 wherein the metallized particles are recovered by magnetic separation.

11. The process as described in claim 3 wherein the ore contains cobalt and the cobalt is recovered with the nickel.

12. The process as described in claim 3 wherein the ore contains at least about 1.5 percent nickel and less than about 30% iron.

13. The process as described in claim 3 wherein the mixture of ore and chloride is maintained at a temperature between about 920C. and 1,020C.

14. A continuous process for beneficiating nickeliferous oxide ores, having an iron content of up to about 50% which comprises establishing within at least one rotary furnace a preheating zone and a segregating zone; continuously feeding nickeliferous oxide ores to the preheating zone; preheating the nickeliferous oxide ore to a temperature above 850C. to about 1,100C. in the preheating zone; continuously conveying the preheated nickeliferous oxide ore while hot to the segregating zone; introducing and intimately mixing controlled amounts of a particulate solid carbonaceous reductant and of at least one chloride selected from the group consisting of alkali metal chlorides, alkaline earth metal chlorides, and iron chloride to the preheated ore which is at a temperature above about 850C; maintaining the mixture of preheated ore, chloride and carbonaceous reductant at a temperature between about 900C. and 1,100C. in a hydrogencontaining atmosphere having a reducing potential equivalent to a carbon monoxide to carbon dioxide ratio between about 1:2 and 4:], at least a part of heat required to maintain said temperature being provided by contacting the ore-containing mixtures with a hot gaseous atmosphere produced by combusting a fuel with a gas containing free oxygen, minimizing the combustion gas flow rate to less than about 30 moles of gas/kg. ofore conveyed to the segregating zone to produce metallized particles with greater nickel values being concentrated therein than obtained at higher flow rates; continuously discharging treated ore containing the metallized particles from the segregating zone; and recovering the metallizedparticles from the discharged ore.

15. The process as described in claim 14 wherein the nickeliferous oxide ore contains cobalt and the cobalt is recovered with the nickel.

16. The process as described in claim 15 wherein the nickeliferous ore contains at least about 1.5% nickel and less than about 30% iron.

17. The process as described in claim 1 wherein said nickeliferous ore has an iron content of up to about 35%.

18. The process as described in claim 17 wherein the gas flow rate in the second stage is about 9 to 12 moles of gas/kg of ore.

19. The process as described in claim 1 wherein the first stage is heated directly by a gas flow which is counter-current to the flow of ore and the second stage is heated directly by a gas flow which is concurrent with the flow of ore.

20. The process as described in claim 1 wherein the temperature in the first stage is maintained between about 920C to about 1,000C.

21. The process as described in claim 3 wherein the mixture of ore and chloride is maintained at temperature by combusting fuel and oxygen.

22. In a two-stage process for beneficating nickeliferous oxide ores having an iron content of up to about 35 percent which comprises a preheating stage and a segregating stage, said ore being subjected in the segregating stage to an elevated temperature in the presence of a reducing agent and a chloride, the steps comprising preheating the ore containing oxide nickel values to a temperature above about 850C to about 1,100C in a reducing atmosphere to dehydrate, calcine, heat and partially reduce the ore, the reduction potential of said reducing atmosphere being such that not greater than about 50 percent of the nickel values in said ore are reduced, the heat to said preheating-partial reduction stage being provided by a direct heating means; continuously conveying the hot partially reduced nickeliferous oxide ore to the segregating stage, introducing and intimately mixing controlled amounts of a particulate solid carbonaceous reductant and at least one chloride selected from the group consisting of alkali metal chlorides, alkaline earth metal chlorides, and iron chloride to the hot partially reduced ore which is at a temperature above about 850C; maintaining the mixture of ore, chloride and carbonaceous reductant at a temperature between about 900C and 1,100C in a hot gaseous hydrogen-containin g atmosphere having a reducing potential equivalent to a carbon monoxide to carbon dioxide ratio between 1:2 to 4:1, at least a part of said hot gaseous atmosphere being produced by combusting fuel and a free-oxygen-containing gas, and minimizing the combustion gas flow rate to less than about 30 moles of gas/kg. of ore, to produce metallized particles with greater nickel values being concentrated therein than obtained at higher flow rates; continuously discharging treated ore containing the metallized particles from the segregating stage, and recovering the metallized particles from the discharged ore.

23. The process as described in claim 22 wherein the mixture of ore, reductant and chloride is maintained at temperature by combusting the fuel with preheated free-oxygen-containing gas.

Claims

1. A CONTINUOUS PROCESS FOOR BENEFICIATING NIKELITERIOUS OXIDE ORES INCLUDING A PREHEATING STAGE AND A SEGREGATING STAGE WHICH COMPRISES PREHEATING AN ORE CONTAINING NICKEL VALUES TO A TEMPERATURE ABOVE ABOUT 850*C TO ABOUT 1,1000*C; MIXING THE HOT PREHEATED ORE WHICH IS AT A TEMPERATURE OF ABOVE ABOUT 850*C. WITH AT LEAST ONE CHLORIDE SELECTED FROM THE GROUP CONSISTING OF ALKALI METAL CHLORIDES, ALKALINE EARTH METAL CHLORIDES, AND IRON CHLORIDE; MAINTAINING THE MIXTURE OF ORE AND CHLORIDE AT A TEMPERATURE BETWEEN ABOUT 900*C. AND 1,100*C. IN A HOT GASEOUS HYDROGEN-CONTAINING ATMOSPHERE HAVING A REDUCING POTENTIAL EQUIVALENT TO A CARBON MONOXIDE TO CARBON DIOXIDE RATIO BETWEEN ABOUT 1:2 AND 4:1, AT LEAST A PART OF THE HEAT TO MAINTAIN THE TEMPERATURE OF THE MIXTURE OF ORE AND CHLORIDE BEING PRODUCED BY COMBUSTING A FUEL WITH A GAS CONTAINING FREE OXYGEN; AND MINIMIZING THE COMBUSTION GAS FLOW RATE TO LESS THAN ABOUT 30 MOLES OF GAS/KG. OF ORE TO PRODUCE METALLIZED PARTICLES WITH GREATER NICKEL VALUES CONCENTRATED THEREIN THAN OBTAINED AT HIGHER FLOW RATES; AND RECOVERING THE METALLIZED PARTICLES.

5. The process as described in claim 3 wherein the mixture of ore and chloride is maintained at temperature by combusting fuel and preheated free-oxygen-containing gas.

9. The process as described in claim 3 wherein off gases from the segregating stage are treated to recover contained chlorides and the recovered chlorides are used as the chloride additive.

13. The process as described in claim 3 wherein the mixture of ore and chloride is maintained at a temperature between about 920.degree.C. and 1,020.degree.C.

14. A continuous process for beneficiating nickeliferous oxide ores, having an iron content of up to about 50% which comprises establishing within at least one rotary furnace a preheating zone and a segregating zone; continuously feeding nickeliferous oxide ores to the preheating zone; preheating the nickeliferous oxide ore to a temperature above 850.degree.C. to about 1,100.degree.C. in the preheating zone; continuously conveying the preheated nickeliferous oxide ore while hot to the segregating zone; introducing and intimately mixing controlled amounts of a particulate solid carbonaceous reductant and of at least one chloride selected from the group consisting of alkali metal chlorides, alkaline earth metal chlorides, and iron chloride to the preheated ore which is at a temperature above about 850.degree.C.; maintaining the mixture of preheated ore, chloride and carbonaceous reductant at a temperature between about 900.degree.C. and 1,100.degree.C. in a hydrogen-containing atmosphere having a reducing potential equivalent to a carbon monoxide to carbon dioxide ratio between about 1:2 and 4:1, at least a part of heat required to maintain said temperature being provided by contacting the ore-containing mixtures with a hot gaseous atmosphere produced by combusting a fuel with a gas containing free oxygen, minimizing the combustion gas flow rate to less than about 30 moles of gas/kg. of ore conveyed to the segregating zone to produce metallized particles with greater nickel values being concentrated therein than obtained at higher flow rates; continuously discharging treated ore containing the metallized particles from the segregating zone; and recovering the metallized particles from the discharged ore.

20. The process as described in claim 1 wherein the temperature in the first stage is maintained between about 920.degree.C to about 1,000.degree.C.

22. In a two-stage process for beneficating nickeliferous oxide ores having an iron content of up to about 35 percent which comprises a preheating stage and a segregating stage, said ore being subjected in the segregating stage to an elevated temperature in the presence of a reducing agent and a chloride, the steps comprising preheating the ore containing oxide nickel values to a temperature above about 850.degree.C to about 1,100.degree.C in a reducing atmosphere to dehydrate, calcine, heat and partially reduce the ore, the reduction potential of said reducing atmosphere being such that not greater than about 50 percent of the nickel values in said ore are reduced, the heat to said preheating-partial reduction stage being provided by a direct heating means; continuously conveying the hot partially reduced nickeliferous oxide ore to the segregating stage, introducing and intimately mixing controlled amounts of a particulate solid carbonaceous reductant and at least one chloride selected from the group consisting of alkali metal chlorides, alkaline earth metal chlorides, and iron chloride to the hot partially reduced ore which is at a temperature above about 850.degree.C; maintaining the mixture of ore, chloride and carbonaceous reductant at a temperature between about 900.degree.C and 1,100.degree.C in a hot gaseous hydrogen-containing atmosphere having a reducing potential equivalent to a carbon monoxide to carbon dioxide ratio between 1:2 to 4:1, at least a part of said hot gaseous atmosphere being produced by combusting fuel and a free-oxygen-containing gas, and minimizing the combustion gas flow rate to less than about 30 moles of gas/kg. of ore, to produce metallized particles with greater nickel values being concentrated therein than obtained at higher flow rates; continuously discharging treated ore containing the metallized particles from the segregating stage, and recovering the metallized particles from the discharged ore.