US3687432A

US3687432A - Recovery of copper

Info

Publication number: US3687432A
Application number: US133956A
Authority: US
Inventors: Terence Mcnulty
Original assignee: Individual
Current assignee: Atlantic Richfield Co
Priority date: 1971-04-14
Filing date: 1971-04-14
Publication date: 1972-08-29
Anticipated expiration: 1989-08-29

Abstract

Low grade, finely disseminated copper oxide ores are beneficiated to enhance the winning of metallic copper therefrom by crushing and sieving the ore to particles of suitable size, preheating the ore particles, reacting a chlorine-donating gas with the ore particles at a controlled elevated temperature to form copper chloride (preferably cuprous chloride) therein and maintain it substantially in molten liquid form, and then reducing the molten liquid form, and then reducing the molten liquid copper chloride at the elevated temperature to metallic copper with a reducing gas. Further benefits are derived by carrying out the preheating step in a reducing or oxidizing atmosphere, and by passing an oxidizing gas through the ore particles after chlorination and before reduction to metallic copper. Apparatus is also described for carrying out the foregoing processes continuously.

Description

United States Patent McNulty [451 Aug. 29, 1972 [54] RECOVERY OF COPPER [72] Inventor: Terence McNulty, '8000 S. Kolb Road, Tucson, Ariz. 85706 [22] Filed: April 14, 1971 [21] Appl. No.: 133,956

Related US. Application Data [62] Division of Ser. No. 828,801, May 26, 1969,

Pat. No. 3,630,721.

[52] US. Cl ..266/9 [51] Int. Cl. ..C22b 15/00 [58] Field of Search ..266/9, 24

[56] References Cited UNITED STATES PATENTS 3,020,149 2/1962 Old et al. ..266/9 X Primary Examiner-Gerald A. Dost Attorney-Dean S. Edmonds et al.

[ ABSTRACT Low grade, finely disseminated copper oxide ores are beneficiated to enhance the winning of metallic copper therefrom by crushing and sieving the ore to particles of suitable size, preheating the ore particles, reacting a chlorine-donating gas with the ore particles at a controlled elevated temperature to form copper chloride (preferably cuprous chloride) therein and maintain it substantially in molten liquid form, and then reducing the molten liquid form, and then reducing the molten liquid copper chloride at the elevated temperature to metallic copper with a reducing gas. Further benefits are derived by carrying out the preheating step in a reducing or oxidizing atmosphere, and by passing an oxidizing gas through the ore particles after chlorination and before reduction to metallic copper. Apparatus is also described for carrying out the foregoing processes continuously.

10 Claims, 1 Drawing Figure Patented Aug. 29, 1972 I. 3,687,432

IINVENTOR TERENCE P. Mc NULTY BY 2 6%6 /f2%&

RECOVERY OF COPPER CROSS REFERENCE TO RELATED APPLICATION This application is a division of my application Ser. 5

Low grade, finely disseminated copper oxide ores are l 5 characterized by minimal total copper contents, typically a maximum of about 1 percent by weight and as little as 0.5 percent, and a copper oxide mineral such as chrysocolla, azurite, malachite or brochantite as the predominant mineralization, which is finely disseminatedin igneous or hydrous silicate gangue. Such ores frequently contain too high a proportion of acid consuming constituents for economic recovery of copper by conventional acid leaching. Also, the copper mineralization is so finely disseminated that these ores do not respond adequately to treatments such as sulfidization for recovery of copper by the conventional flotation-concentration method used with copper sulfide ores.

Heretofore, certain so-called segregation or migration processes have been developed for treatment of copper oxide ores of the type described above. These processes involve converting the copper content of the ore at elevated temperatures to copper chloride vapor,

migration of the copper chloride vapor out of the ore particles and subsequent condensation of it upon an added material such as carbon or coke or upon the exterior of the host ore particles, in order to render the copper values more readily amenable to separation from the gangue by conventional techniques such as leaching. However, the commercial practice of such processes is technically difficult and costly, due to the fact that temperatures above l,450 F. must be maintained to achieve vaporization and migration of the copper chloride. At these temperatures, serious corrosion problems from chloride vapors are encountered, which can be only partially alleviated by costly anticorrosion measures. Also, a considerable amount of fuel energy is required to maintain the high operating temperatures, resulting in further increases in the cost 5 of production. Furthermore, difficulty is usually had with ores bearing substantial quantities of calcium carbonate.

The present invention provides a process for beneficiation of low grade, finely disseminated copper oxide ores which avoids many of the foregoing problems and is based upon the discovery that the copper content of suitably-sized particles of such ores novel, enabling features of the invention permit recovery of copper from low grade, finely disseminated ores without having to produce and handle vaporized metal chlorides or to generate and sustainthe temperatures required for that purpose, as in conventional segregation or migration processes. As a result, significant savings in cost of equipment, fuel .energy and maintenance may be realized in the commercial practice of the invention in comparison to such conventional processes, and in many cases furthergains are achieved due to the recovery of higher amounts of copper from the total amount available in the ore when processed in accordance with the invention. All of these advantages have both technical and economic value and especially so in the context of processing of ores which, at best, rate poor on the scale of quality.

Briefly summarized, the invention involvesthe steps of crushing, grinding or similarly reducing a copper oxide or to particles of suitable size, reacting .a chlorine-donating gas with the ore particles at a controlled temperature above ambient to form molten liquid copper chloride (preferably cuprous chloride) therein and to maintain the molten liquid form without substantial vaporization or vapor phase migration thereof, and then reducing the molten liquid copper chloride to metallic copper with a reducing gas. The ore particles are then cooled by quenching and the copper therein separated and recovered in conventional manner, preferably by first grinding the particles to a finer size and then subjecting them to flotationconcentration. The process may be carried out also with optional steps of preheating the ore particle in. a reducing atmosphere prior to chlorination and treating the ore particles with an oxidizing gas after chlorination and before reduction to metallic copper, for purposes which will be explained hereafter. Less desirable alternatives also are to preheat mixed oxide/sulfide oresin an oxidizing atmosphere before chlorination, and then perform the gaseous reduction step after chlorination without an intervening oxidizingtreatment.

The accompanying drawing illustrates a novel apparatus which is particularly useful forcarrying out the process of the invention.

The invention is useful to maximum advantage in processing of low grade, finely disseminated copper oxide ore as found, for example, in the southwest United States, South America and Northern Rhodesia 0 in Africia. Typically, such ores contain from about 05 can, at proper temperatures, be converted to and maintained substantially as molten liquid cuprous chloride, that the molten salt, with little or no prior vaporization, can be coalesced or concentrated within the ore particles and then reduced to metallic copper by gaseous reduction, and that as a result the reduced copper can be readily recovered by conventional flotation-concentration in yields corresponding to remarkably high proportions of the total copper content of the ore. These to about 1 percent total copper of which 'percent or more assays as copper oxide mineralization. The invention may also be applied, however, to copper oxide ores having higher copper contents or to mixed copper oxide-sulfide ores to recover copper with substantially the same efficiencies and yields as with the low grade copper oxide ores.

In practicing the invention, it is desirable initially to crush, grind or similarly reduce the copper oxide ore to particles of which at least about 80 percent by weight passes an 8 mesh screen. To some degree, this step enhances the subsequent coalescence or concentration of molten liquid copper chloride in the 'particles'and thus promotes recovery of a maximum proportion of the total copper content of the ore. In addition, reduction of the ore to specified size provides greater uniformity in the ore material and facilitatesits handling during subsequent phases of the process. The ore may be reduced to the required size by conventional means such as gyratory or cone crushers.

After the foregoing'step, the ore particles are placed in any suitable vesselv to which heat and gases may be supplied such as a smelting furnace or the like. At this point, the ore particles may be exposed at elevated temperature to a reducing gas such as gases containing methane, carbon monoxide or mixtures thereof. Generally, this step helps to open up the mineralization of the ore, that is, it liberates the copper oxide minerals from silicates and similar gangue constituents and thus promotes subsequent formation of copper chloride, especially cuprous chloride. Such preheating in a reducing gas is very important in the case of chrysocolla and similar hydrous silicate ores for ensuring ultimate recovery of the maximum amount of copper from the ore. The preheating-reducing treatment may be carried out at temperatures from about 850 to about 950 F. and generally will be completed in about 1 to about 1% hours. i

In the next step of the process, which may be performed directly after the ore particles have been reduced to size or after the preheating-reducing treatment described above, the ore particles are exposed to chlorine gas, or hydrogen chloride or any other gas which donates chlorine, at a controlled temperature above ambient in order to convert the copper oxide minerals therein to molten liquid copper chloride. Generally, this may be done at a temperature within the range from about 800 to about 975 F., and preferably from about 840 to about 900 F. At such controlled temperatures, the copper chloride formed in the ore particles remains substantially in molten liquid form with little or no vaporization or vapor phase migration thereof. As the chlorination proceeds, the molten liquid coalesces or concentrates within the host ore particles and generally this step of the process will be completed in about k to about 1 hour.

Thereafter, the ore particles may be exposed to an oxidizing gas at substantially the same temperatures as sustained during chlorination. This is an optional step which converts chlorides of other metals in the ore particles, primarily iron chloride, to the corresponding metal oxides and thus liberates chlorine which is available within the ore particles for chlorinating any residual copper oxide minerals not converted to the chloride during the preceding chlorination step. Accordingly the oxidizing treatment is another measure which can be used to ensure the maximum ultimate yield of copper and whether or not it is used will be determined largely by balancing the improvement in yield from any particular ore against the cost of operation. The oxidizing treatment may be accomplished with the use of air, pure oxygen or any gas containing oxygen mixed with components which are not detrimentally reactive to the ore particles, and generally will be completed in about V4 to about 1% hour.

In the next step, the ore particles containing concentrated molten liquid copper chloride are exposed to a reducing gas, at substantially the same temperatures as sustained during chlorination, in order to reduce the chloride to metallic copper. This may be done with gases containing hydrogen, methane, or any other hydrocarbon or mixtures thereof, and generally reduction will be completed in about A to about 1 hour. The reduced metallic copper will be concentrated or distributed within the ore particles in substantially the same portions formerly containing the molten liquid copper chloride.

Following the reduction to metallic copper, the ore particles are discharged from the furnace or reaction vessel and quenched in water or any other aqueous coolant. Then, in preparation for flotation-concentration, the particles preferably are ground to a finer size, typically about 80 percent minus 100 mesh, in a ball mill or any other suitable grinding apparatus. Finally, the copper content of the ore particles is separated from the gangue in conventional flotation tanks, preferably in a series of at least two tanks with the concentrate from the first being further concentrated in the second, etc. Collector chemicals such as xanthates, dithiophosates or xanthate derivatives and frothers such as pine oil may be used in carrying out flotationconcentration in known manner.

The final concentrate comprises a copper enriched product which may contain an amount of copper corresponding to to percent by weight of the total copper content of the original ore.

ln carrying out the process of the invention as described above, the best results generally are achieved by using the full sequence of the described steps including those which are critical and essential, as well as those which are optional. More specifically, the ore particles should be preheated in a neutral or reducing atmosphere (optional), chlorinated (essential), oxidized (optional) and finally reduced to metallic copper (essential). By this sequence, the copper oxide mineralization is opened up during preheating in a reducing atmosphere, so that more of it can be converted to the chloride during the chlorination step. For mixed oxide/sulfide ores, of which the sulfide portion is invariably mainly iron sulfide, the iron sulfide is converted to ferrous chloride at the same time that copper chloride is formed during the chlorination step. During the subsequent oxidation step, the copper chloride remains unaffected whereas the ferrous chloride is converted to ferric oxide, chlorine being liberated simultaneously and saved for further use in chlorination of any residual copper oxide not chloridated during the previous chlorination step, or for recycling and chlorination of additional amounts of ore. In the final reduction step, hydrogen chloride evolves as the molten coalesced copper chloride is reduced to copper metal and this off-gas may be recycled for chlorination of further amounts of ores. Thus, the full sequence of steps provides for maximum recovery of chlorine when processing either straight copper oxide ores or mixed oxide/sulfide ores, without problems of chlorine loss due to formation of ferrous chloride which cannot be reduced with hydrogen or methane below 1,800 F. Furthermore, the full sequence of steps is operable at temperatures just above the melting temperature of cuprous chloride (791 F.), i.e. at about 800 to 900 F and thus also provides for maximum economy in the cost of fuels since only the lowest operating temperatures need be generated and sustained during the process.

A less advantageous alternative to the foregoing full sequence of steps for avoiding chlorine loss due to formation of ferrous chloride is to preheat mixed oxide/sulfide ores in an oxidizing atmosphere prior to chlorination. In this way the iron sulfide content of the ore may be converted to iron oxides which are more stable than the sulfide and will not be converted to chlorides during the subsequent chlorination step. As a result, the chlorinated ore with molten coalesced copper chloride therein may thereafter be reduced directly to copper metal without an intervening oxidation step and without problems of chlorine loss as irreducible iron chlorides, fonnation of which has been avoided. However, the disadvantageous feature of this alternative sequence is that the higher temperatures required for the initial oxidizing preheat (e.g. 900 to 1,000 F.) maintain the copper content of the ore in cupric form, with the result that the remaining chlorination and reduction steps must be carried out above the melting temperature of cupric chloride, i.e. above 928 F., as contrasted from the lower operating temperatures which may be used in the preferred sequence of steps described previously. Thus, while one less step is required in the alternative sequence, the resulting increase in cost of fuels for maintaining higher operating temperatures will often off-set the advantages of a simpler and shorter processing schedule. However, where in specific instances the economic factors are not prohibitive or intolerable, the alternative sequence may be used to treat mixed oxide/sulfide ores in accordance with the invention.

Referring now to the accompanying drawing, an apparatus for carrying out the process of the invention continuously is there illustrated, and includes a reactor in the form of an elongated chamber standing in upright, vertical position.

The chamber 10 is provided with an ore feed opening 12 at the top and an ore discharge opening 14 at the bottom. The internal space of the chamber 10 situated between the ore feed and

discharge openings

12 and 14 is divided into three separate compartments 10A, 10B and 10C, which succeed each other along the length axis of the chamber. Each compartment 10A, 10B and 10C has a

base comprising walls

16A, and 16B and 16C, respectively, which angle downwardly and inwardly toward the length axis of chamber 10.

Transfer openings

17A and 17B are centered on the length axis of chamber 10 at the bottoms of

angled walls

16A and 16B, respectively, and provide for transfer of ore from compartments 10A to 10B to 10C by downward movement through the openings.

The tops of the walls 10A, 10B and 10C are sealed to the interior wall of chamber 10 and the bottoms of the walls are similarly sealed by means of the

horizontal walls

18A, 18B and 18C extending across the radial distance between said bottoms and the interior wall of chamber 10. Thus, isolated plenum chambers 20A, 20B and 20C are formed containing the spaces enclosed by the interior wall of chamber 10, angled

walls

16A, 16B and 16C, and connecting

walls

18A, 18B and 18C at the bases of compartments 10A, 10B and 10C respectively.

The plenum chamber 20A of top compartment 10A is provided with an injection conduit 22A through which chlorine, hydrogen chloride or other chlorinedonating gas may be injected into the plenum chamber. Similarly, the plenum chambers 20B and 20C of the middle and bottom compartments 10B and 10C are provided with

conduits

22B and 22C through the former of which air, oxygen or other oxygen-donating gas may be injected and through the latter of which methane, hydrogen or other hydrocarbon gas capable of reducing copper chloride may be injected into the respective plenum chambers.

The

angled walls

16A, 16B and 16C are provided with a plurality of upright

hollow nozzle members

24A, 24B and 24C, respectively, through which gas injected into the associated plenum chambers 20A, 20B and 20C may pass and be distributed into the compartments 10A, 10B and 10C. At the tops of compartments 10A, 10B and 10C,

conduits

26A, 26B and 26C are provided through which off-gases resulting from the treatment of ore in the compartments may be withdrawn. The flow of gas in the

withdrawal conduits

26A, 26B and 26C is controlled by

multi-position valves

28A, 28B and 28C, respectively. As illustrated, the gases withdrawn from compartments 10B and 10C may be recycled into plenum chamber 20A and thereby into compartment 10A, or conducted away from chamber 10 like the gas withdrawn from compartment 10A for other suitable disposition. In addition, a plurality of upright hollow conduits 30 vertically traversing plenum chamber 20A provide for direct passage of off-gases from compartment 10B to compartment 10A. Temperature sensing probes 32A, 32B and 32C, e.g. thermocouples, are mounted into the compartments 10A, 10B and 10C to measure temperatures therein.

The ore feed opening 12 communicates with the discharge end of a conventional, variable-speed, rotating-screw conveyor 34, the opposite end of which communicates with a rotary drum preheater 36. As illustrated, the conveyor 34 is inclined upwardly from its opposite to discharge ends in order to provide a gas seal as will be more fully explained hereafter. The preheater 36 is equipped at one end with a gas-inflow oredischarge plenum 40 into which hot air or air-natural gas mixtures may be injected via conduit 42. The opposite end of preheater 36 is provided with a gas-exhaust ore-feed plenum 44 into which ore may be fed via variable-speed, rotating-screw conveyor 46 supplied by feed hopper 48 and out of which off-gases may be discharged via conduit 50.

The ore discharge opening 14 of chamber 10 communicates with one end of a variable-speed rotatingscrew conveyor 52 which is similar to conveyor 34 but maintained in horizontal rather than inclined position and which conveys ore to a dump opening 54 near its opposite end.

In the preferred operation of the apparatus described above, copper oxide or mixed copper oxide/sulfide ore crushed to particles of approximately minus 6 meshis cent by volume of carbon monoxide to effect preheating in a reducing atmosphere in order to help open up the mineralization as previously explained.

After traversing the length of preheater 36, the ore particles are dropped into inclined conveyor 34 which conveys the particles to its discharge end and into the ore feed opening 12. Chlorine-containing off gases from chamber 10 are prevented from passing back through opening 12 into preheater 36 by the inclination of conveyor 34 and the ore contained therein, thereby avoiding intermixing of chlorine and carbon monoxide which would raise the hazard of formation of toxic phosgene.

The ore particles enter compartment 10A and are there chlorinated at a temperature of about 850 F. by hot chlorine gas injected via conduit 22A, plenum chamber A and nozzles 24A. Such temperatures, being a little above the melting temperature of cuprous chloride (791 F.), result in conversion of the copper content of the ore particles to cuprous chloride in molten state, little or none of which vaporizes. The molten cuprous chloride coalesces and thereby becomes concentrated within the ore particles. Simultaneously, the iron sulfide content of the ore, if any, is converted to iron chloride, chiefly ferrous chloride.

The ore particles next pass through transfer opening 17A and enter compartment 10B. Here the particles are treated with hot air or any other oxygen-donating gas, the temperature of the particles again being maintained at about 850 F. Under these conditions, ferrous chloride in the ore particles is readily oxidized to liberate its chlorine content while the molten or coalesced cuprous chloride remains unaffected. The liberated chlorine will react with any residues of copper oxide or copper oxide minerals in the ore particles which were not converted to the chloride in compartment 10A to form additional molten cuprous chloride. A portion of the liberated chlorine is also passed directly back through conduits 30 into compartment 10A to assist in chlorination of further quantities of ore entering that compartment. The same effect may be achieved indirectly by the recycle path provided by withdrawal conduit 26B and valve 288.

The ore particles next pass through transfer opening 178 and enter compartment 10C. Here, the molten or coalesced cuprous chloride in the ore particles is reduced to metallic copper, again at temperatures of about 850 F., by hydrogen, natural gas or any other gaseous hydrocarbon introduced via conduit 22C, plenum chamber 20C and nozzles 24C. The reduction reaction evolves hydrogen chloride as by-product which is withdrawn through conduit 26C and either recycled through valve 28C to compartment 10A for chlorination of further quantities of ore or conveyed to a treating station where its chlorine content is regenerated in conventional manner. The regenerated chlorine in turn is recycled to injection conduit 22A.

Finally, the ore particles containing concentrated metallic copper pass through discharge opening 14 into conveyor 52 for dumping through opening 54 into a quenching bath and then recovery of the copper by conventional flotation-concentration as previously explained. By varying and correlating the operational rates of

conveyors

34 and 52, the height and residence time of ore particles in chamber 10 can be readily controlled.

Further details of the invention will be apparent from the following examples which constitute several embodiments thereof and in which all proportions are expressed by weight unless otherwise indicated.

EXAMPLE 1 In this example a copper oxide ore, designated Pit Limestone 68-2-1 and having head assay of 1.28 percent total copper and 1.15 percent oxide copper, was processed. The ore was first crushed in a cone crusher until 100 percent thereof passed a 6 mesh screen. The crushed ore particles were then transferred to a smelting furnace and the temperature of the furnace raised to 860 F. A mixture of methane and hydrogen gases was passed through the ore particles for about one hour at the specified temperature. Then the ore particles were chlorinated in chlorine gas at the same temperature over a period of one hour. Next the chlorinated ore particles were oxidized with air at the same temperature for about one hour. Finally the ore particles were reduced with a reducing gas containing a mixture of hydrogen and methane at the same temperature for about one hour.

The reduced ore particles were removed from the furnace and quenched in water. Then the particles were reduced in a ball mill to minus mesh size. The ground ore particles were subjected to flotation-concentration in a rougher tank using pine oil as the frothing agent and a xanthate as the collector chemical, with air bubbled up through the liquid content of the tank. The concentrate from the rougher tank was then transferred to a second cleaner flotation tank and further refined by flotation-concentration using the same conditions. The tailings from the rougher and cleaner tanks as well as the concentrate from the cleaner tank were collected and analyzed for copper content. The results of these analyses are given in the table below, the amount of copper in each fraction being expressed, first, as the percentage of that fraction (percent total Cu) and, secondly, as the percentage of total copper content of the original ore (percent total Cu distribution). The same analyses were made upon a control sample of the original ore which was crushed to the same size and subjected to flotation-concentration as the chlorinated sample, but not treated by any of the gaseous reactants. The results of these analyses are also given in the table below.

k Total Cu Product Total Cu Distribution Raw Ore, control sample As will e evident from the foregoing results, the process of the invention was effective for recovering three-quarters of the total original copper content of the ore.

EXAMPLE 2 In this example low grade southern Arizona ore, designated Arkose K-6, was used. The ore had a head assay of 0.5 percent total copper and 0.4 percent oxide copper. The oxide copper mineralization was primarily dilute copper silicate in various silicate matrices.

This ore was treated in five different ways all of which were preceded by crushing the ore so that the particle size was minus eight mesh, with the exception of test number five. In all cases, the feed to flotation was obtained by ball milling to approximately 80 percent minus 100 mesh.

In test number one the raw ore was merely subjected to flotation-concentration in a rougher tank followed by a first cleaner tank and then a second cleaner tank.

In test number two the ore was first preheated for about one hour at 800 F. and then subjected to flotation-concentration in the manner described for test number one.

In test number three the ore was again preheated as in test number two, then sulfidized with sodium sulfide at 68 F. and then subjected to flotation-concentration in the manner described in test number one.

In test number four the ore was preheated as in test number two, then sulfidized with elemental sulfur at 625 F. and then subjected to flotation-concentration in the manner described in test number one.

In test number five the ore was crushed to a size such that about 80 percent thereof passed 100 mesh screen. The ore was reduced for about one hour with methane, then chlorinated for about one hour with chlorine gas, and then reduced with methane for about one hour, all of these treatments being carried out at a temperature between 900950 F. The treated ore was then subjected to flotation-concentration in only the rougher tank and the first cleaner tank.

The tailings and concentrates from the respective five tests were collected and analyzed for copper content and the results of these analyses are given in the table below on the same two bases as described in Example l.

Total Test No. Product Total Cu Cu Distr.

1 rougher tail 0.45 60.2 1st cleaner tail 0.56 29.3

2nd cleaner tail 0.93 3.2

2nd cleaner conct. 4.72 7.3

2 rougher tail 0.40 78.3 1st cleaner tail 0.61 1 1.9

2nd cleaner tail 1.48 2.4

2nd cleaner conct. 6.19 7.4

3 rougher tail 0.41 74.8 1st cleaner tail 0.65 15.9

2nd cleaner tail 1.79 2.2

2nd cleaner conct. 8.03 8.1

4 rougher tail 0.20 32.7 1st cleaner tail 0.98 15.3

2nd cleaner tail 1.81 8.4

2nd cleaner conct. 5.83 43.6

5 rougher tail 0.14 22.5 1st cleaner tail 0.91 3.9

I 1st cleaner conct. 30.70 73.6

As will be noted 73.6 percent of the total copper content of the original ore was recovered in the first cleaner concentrate derived from the ore that was chlorinated and reduced in accordance with the invention. None of the other treatments could approach this yield even through one less flotation-concentration treatment was used with the ore sample processed in accordance with the invention.

EXAMPLE 3 Three different mixed oxide/sulfide copper ores from the Twin Buttes, Arizona vicinity, designated as Limestone 68-136, Shaft Spill 67-63 and Arkose 67-64, were treated by the preferred process of the invention as previously described in connection with the accompanying drawing and then subjected to flotationconcentration in accordance with the procedures described in Examples 1 and 2.

The results of these tests are set forth in the following table on the same bases as in Examples 1 and 2, with the ore designations above being denoted as A, B and C, respectively, and the head assays of each reported as percent total copper (T Cu) and percent oxide copper (0 Cu): Ore and Again, it will be seen from the foregoing that the process of the invention was effective for recovering substantial proportions of the total copper contents of the treated ores.

The invention has been described in terms of its operative principles and several illustrative embodiments thereof. Many variations in the illustrative embodiments will be obvious to those skilled in the art without departing from essence or scope of the invention. Accordingly the scope of the invention is to be determined by reference to the appended claims.

The following is claimed:

1. Apparatus for the beneficiation of copper oxide ores which comprises:

a. an elongated chamber standing with its length axis in substantially vertical position and having an ore feed opening at an upper portion thereof and an ore discharge opening at a lower portion thereof,

b. means for dividing that portion of the internal space of said chamber situated between said ore feed and discharge openings into a plurality of separate compartments positioned successively along said length axis,

1. each said compartment having a transfer opening at its base in communication with the top of the next succeeding compartment to provide for transfer of ore from one compartment to the next succeeding compartment by movementof the ore down through said transfer opening,

c. means for injecting a gas of selected composition into the base portion of each said compartment, and

(1. means for withdrawing from an upper portion of each said compartment off-gases resulting from the treatment of ore therein with said injected gas.

2. Apparatus according to claim 1 wherein each said injection means is arranged to inject gas at a level elevated above the transfer opening of its respective compartment.

3. Apparatus according to claim 1 wherein each said withdrawal means (d) is arranged to withdraw gas from a level approximately the same as that of the transfer open-ing of the next higher compartment.

4. Apparatus according to claim 1 wherein the base of each, said compartment comprises walls angled downwardly and inwardly toward the length axis of said chamber, and the transfer opening of said compartment is substantially centered on said length axis at the bottom of said angled walls.

5. Apparatus according to claim 4 wherein the tops of said angled walls of each base are sealed to the interior wall of said chamber and the bottoms of said angled walls are also sealed to the interior wall of said chamber via connecting walls extending across the radial distance between said bottoms and said interior wall, thereby forming an isolated plenum chamber containing the space enclosed by said angled walls, connecting walls and interior wall, each said injection means (0) being arranged to inject gas directly into one of said plenum chambers, and said angled walls of each plenum chamber having a plurality of upright hollow nozzle members through which gas injected into said plenum chamber may pass for injection and distribution into the respective compartment thereof.

6. Apparatus according to claim 1 wherein said dividing means (b) divides said internal space into three successive compartments, and wherein said injection means (c) for the top one of said three compartments injects a chlorine-donating gas therein and said injection means (0) for the middle one of said three compartments injects an oxygen-donating gas therein and said injection means (c) for the bottom one of said three compartments injects a gas capable of reducing copper chloride therein.

7. Apparatus according to claim 6 which further comprises a plurality of hollow conduits communicating between the upper portion of the middle one of said three compartments and the lower portion of the top one of said three compartments to provide for passage of off-gases from said middle compartment to said top compartment.

8. Apparatus according to claim 1 which further comprises:

e. variable-speed rotating-screw conveyor means for transporting ore from a source thereof and dropping it into said ore feed opening at a selected rate,

f. variable-speed rotating-screw conveyor means for receiving ore exiting through said ore discharge opening and transporting it elsewhere at a selected rate, whereby the height of ore in said chamber may be controlled and varied by correlation of said rates. 9. Apparatus according to claim 8 which further comprises means for preheating said ore and for providing said preheated ore as the source of ore for said variable speed rotating-screw conveyor means (c).

10. Apparatus according to claim 9 wherein said variable speed rotating-screw conveyor means (c) is positioned at an incline from said source of preheated ore to said ore feed opening to prevent off-gases from said compartments from passing therethrough into said preheating means.

Claims

2. Apparatus according to claim 1 wherein each said injection means (c) is arranged to inject gas at a level elevated above the transfer opening of its respective compartment.
3. Apparatus according to claim 1 wherein each said withdrawal means (d) is arranged to withdraw gas from a level approximately the same as that of the transfer opening of the next higher compartment.
4. Apparatus according to claim 1 wherein the base of each said compartment comprises walls angled downwardly and inwardly toward the length axis of said chamber, and the transfer opening of said compartment is substantially centered on said length axis at the bottom of said angled walls.
5. Apparatus according to claim 4 wherein the tops of said angled walls of each base are sealed to the interior wall of said chamber and the bottoms of said angled walls are also sealed to the interior wall of said chamber via connecting walls extending across the radial distance between said bottoms and said interior wall, thereby forming an isolated plenum chamber containing the space enclosed by Said angled walls, connecting walls and interior wall, each said injection means (c) being arranged to inject gas directly into one of said plenum chambers, and said angled walls of each plenum chamber having a plurality of upright hollow nozzle members through which gas injected into said plenum chamber may pass for injection and distribution into the respective compartment thereof.
6. Apparatus according to claim 1 wherein said dividing means (b) divides said internal space into three successive compartments, and wherein said injection means (c) for the top one of said three compartments injects a chlorine-donating gas therein and said injection means (c) for the middle one of said three compartments injects an oxygen-donating gas therein and said injection means (c) for the bottom one of said three compartments injects a gas capable of reducing copper chloride therein.
7. Apparatus according to claim 6 which further comprises a plurality of hollow conduits communicating between the upper portion of the middle one of said three compartments and the lower portion of the top one of said three compartments to provide for passage of off-gases from said middle compartment to said top compartment.
8. Apparatus according to claim 1 which further comprises: e. variable-speed rotating-screw conveyor means for transporting ore from a source thereof and dropping it into said ore feed opening at a selected rate, f. variable-speed rotating-screw conveyor means for receiving ore exiting through said ore discharge opening and transporting it elsewhere at a selected rate, whereby the height of ore in said chamber may be controlled and varied by correlation of said rates.
9. Apparatus according to claim 8 which further comprises means for preheating said ore and for providing said preheated ore as the source of ore for said variable speed rotating-screw conveyor means (c).
10. Apparatus according to claim 9 wherein said variable speed rotating-screw conveyor means (c) is positioned at an incline from said source of preheated ore to said ore feed opening to prevent off-gases from said compartments from passing therethrough into said preheating means.