US3630721A

US3630721A - Recovery of copper

Info

Publication number: US3630721A
Application number: US828801A
Authority: US
Inventors: Terence P Mcnulty
Original assignee: Anaconda Co
Current assignee: Anaconda Co; Atlantic Richfield Co
Priority date: 1969-05-26
Filing date: 1969-05-26
Publication date: 1971-12-28
Anticipated expiration: 1988-12-28

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 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

Unite States Patent [72] lnventor Terence P. McNulty Tucson, Ariz. [21] Appl. No. 828,801 [22] Filed May 26, 1969 [45] Patented Dec. 28, 1971 [73] Assignee The Anaconda Company 4] RECOVERY OF COPPER Claims, 1 Drawing Fig.

[52] 11.5. (I 75/72, 75/76, 75/113 [51] Int. C22b /00 Field of Search /72-76, 101, l 1 1-1 17 [5 6] References Cited UNITED STATES PATENTS 7 1,487,145 3/1924 Caron 75182 X 1,958,754 5/1934 Holley 75/76 X 2,025,068 12/1935 Mitchell 75/111 6/1951 Pratt 75/11 Attorney-Pennie, Edmonds, Morton, Taylor and Adams 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 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.

PA'IENIEBIIERNM r 3530.721

INVENTOR TERENCE P. MC NULTY ATTORNEYS RECOVERY OF COPPER This invention relates to a method of beneficiating or upgrading copper oxide ores to enhance the winning of metallic copper therefrom, as manifested by increased yields and/or improvements in efficiency and economy thereby achieved over heretofore known methods, and to an apparatus for carrying out said method.

Low-grade, finely disseminated copper oxide ores are 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 disseminated in igneous or hydrous silicate gangue. Such ores frequently contain too high a proportion of acid consuming constituents for economical 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.

l-leretofore, 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 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 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 of the foregoing problems and is based upon the discovery that the copper content of suitably sized particles of such ores 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 concentration in yields corresponding to remarkably high proportions of the total copper content of the ore. These 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 sustain the 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 further gains 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 involves the steps of crushing, grinding or similarly reducing a copper oxide ore 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 flotation-concentration. The process may be carried out also with optional steps of preheating the ore particles 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 ores in an oxidizing atmosphere before chlorination, and then perform the gaseous reduction step after chlorination without an intervening oxidizing treatment.

The accompanying drawing illustrates a novel apparatus which is particularly useful for carrying 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 in Africa. Typically, such ores contain from about 0.5 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.

ln 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 facilitates its 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 vessel 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.

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 not 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 one-half 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 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 one-fourth to about one-half 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 one-half 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 fiotationconcentration, 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 flotation-concentration in known manner.

The final concentrate comprises a copper enriched product which may contain an amount of copper corresponding to 70 percent to 80 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 a 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 l,800 F. Furthermore, the full sequence of steps is operable at temperatures just above the melting temperature of cuprous chloride (79l 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, formation 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 offset 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 l0 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, 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 168, respectively, and provide for transfer of ore from compartments 10A to 108 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 chlorine-donating 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 A, 10B and WC. 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

multiposition valves

28A, 23B and 28C, respectively. As illustrated, the gases withdrawn from compartments 10B and 110C may be recycled into plenum chamber A 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 108 to compartment 10A. Temperaturesensing probes 32A, 32B and 32C, e.g., thermocouples, are mounted into the compartments 110A, K018 and 10C to measure temperatures therein.

The ore feed opening 12 communicates with the discharge end of the 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 oredi scharge 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 offgases may be discharged via conduit 50.

The ore discharge opening 14 of chamber 10 communicates with one end of a variable-speed rotating-screw 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 mesh is fed into preheater 36 via feed hopper 48 and conveyor 46. The ore particles are heated to a temperature of about 850 F. in preheater 36 by countercurrent contact with a hot mixture of air and natural gas injected via conduit 42 and plenum 40. The composition of this mixture is controlled preferably to provide about 2 percent 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 20A 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 103. 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 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 WA 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 283.

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 byproduct which is withdrawn through conduit 26C and either recycled through valve 23C 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 a 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 1 hour at the specified temperature. Then the ore particles were chlorinated in chlorine gas at the same temperature over a period of 1 hour. Next the chlorinated ore particles were oxidized with air at the same temperature for about 1 hour. Finally the ore particles were reduced with a reducing gas containing a mixture of hydrogen and methane at the same temperature for about 1 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 theg aseous reactants. The results of these analyses are also given in the table below.

917 Total Cu Product '16 Total Cu Distribution Raw Ore, control sample Rougher tail 1.34 96.6 lst Cleaner tail 1.50 2.7 lst Cleaner conct. 4.10 0.7 Prehcuted. chlorinated,

oxidized, reduced Rougher tail 0.29 23.5 lst Cleaner tail 2.48 1.9 is! Cleaner conct. 60.00 74.6

As will be 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 8 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.

ln 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 1 hour at 800 F. and then subjected to flotation-concentration 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 IOO-mesh screen. The ore was reduced for about 1 hour with methane, then chlorinated for about 1 hour with chlorine gas, and then reduced with methane for about 1 hour, all of these treatments being carried out at a temperature between 900-950 F. The treated ore was then subjected to flotation-concentration in only the rougher tank and the first cleaner tank.

The tailing 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 1.

In cleaner tail lst cleaner conct.

EXAMPLE 3 Three different mixed oxide/sulfide copper ores from the Twin Buttes, Arizona vicinity, designated as Limestone 68-436, 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 flotation-concentration 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 base 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):

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 detennined by reference to the appended claims.

The following is claimed:

1. 1n the beneficiation of a copper oxide ore to enhance the winning of metallic copper therefrom, the improvement which comprises:

a. reacting a chlorine-donating gas with particles of said ore particles to form copper chloride therein, said reaction being carried out at a temperature above ambient which maintains said copper chloride substantially in molten liquid form, and

b. passing a reducing gas through said ore particles to reduce said molten liquid copper chloride therein to metallic copper.

2. The improvement according to claim 1 which further comprises maintaining said ore particles during step (b) at a temperature substantially the same as during step (a).

3. The improvement according to claim 2 which further comprises subsequent to step (b):

c. quenching said ore particles in a cooling liquid.

d. reducing said quenched ore particles to particles of which at least about percent by weight passes a l00-mesh screen, and

e. flotating said reduced ore particles to separate a copper enriched fraction from the remainder thereof.

4. The improvement according to claim I in which said temhydrogen or a mixture thereof through said ore particles perature during step (a) is within the range from about 800 to at a temperature from about 800 to about 900 F. about 975 F. c. reacting a chlorine-donating gas with said ore particles to 5. The improvement according to claim 1 whi h further form cuprous chloride therein, said reaction being carried comprises passing a gas containing methane, ca mOnOX- 5 out at a temperature within the range set forth in step (b) ide, y g a mixture thereof through said Ore Particles to maintain said cuprous chloride substantially in molten at a temperature from about 850 to about 950 F. before step id f m d. passing a gas containing oxygen through said ore particles 6. The improvement according to claim 1 which further comprises passing a gas containing oxygen through said ore particles at a temperature from about 800 to about 975 F. after step (a) and before step (b).

7. The improvement according to claim 1 in which said reducing gas contains methane, hydrogen or a mixture thereof.

8. The improvement according to claim 1 in which said copper oxide ore also contains sulfidic copper compounds and which further comprises passing a gas containing oxygen through said ore particles at a temperature from about 900 to about i,000 F. before step (a). 2

9. In the beneficiation of copper oxide ore to enhance the winding of metallic copper therefrom, the improvement which at a temperature within the range set forth in step (b) to liberate chlorine gas from metal chlorides therein other than said cuprous chloride, so that said liberated chlorine gas may react with and form additional molten liquid cuprous chloride from copper compounds not converted thereto during step (c), and

e. passing a reducing gas through said ore particles at a temperature within the range set forth in step (b) to reduce said molten liquid cuprous chloride to metallic copper.

10. The improvement according to claim 9 which further comprises subsequent to step (e):

f. quenching said ore particles in an aqueous cooling liquid.

g. reducing said quenched ore particles to particles of which at least about 80 by weight passes a IOO-mesh screen,

comprises:

a. reducing said ore to particles of which at least about 80 flotatmg reduced Ore "9 to Separate a copperpercem by weight passes an 8 meSh screen enriched fraction from the remainder thereof.

7 b. passing a gas containing methane, carbon monoxide,

Claims

2. The improvement according to claim 1 which further comprises maintaining said ore particles during step (b) at a temperature substantially the same as during step (a).
3. The improvement according to claim 2 which further comprises subsequent to step (b): c. quenching said ore particles in a cooling liquid, d. reducing said quenched ore particles to particles of which at least about 80 percent by weight passes a 100-mesh screen, and e. flotating said reduced ore particles to separate a copper enriched fraction from the remainder thereof.
4. The improvement according to claim 1 in which said temperature during step (a) is within the range from about 800* to about 975* F.
5. The improvement according to claim 1 which further comprises passing a gas containing methane, carbon monoxide, hydrogen or a mixture thereof through said ore particles at a temperature from about 850* to about 950* F. before step (a).
6. The improvement according to claim 1 which further comprises passing a gas containing oxygen through said ore particles at a temperature from about 800* to about 975* F. after step (a) and before step (b).
7. The improvement according to claim 1 in which said reducing gas contains methane, hydrogen or a mixture thereof.
8. The improvement according to claim 1 in which said copper oxide ore also contains sulfidic copper compounds and which further comprises passing a gas containing oxygen through said ore particles at a temperature from about 900* to about 1,000* F. before step (A).
9. In the beneficiation of copper oxide ore to enhance the winding of metallic copper therefrom, the improvement which comprises: a. reducing said ore to particles of which at least about 80 percent by weight passes an 8-mesh screen, b. passing a gas containing methane, carbon monoxide, hydrogen or a mixture thereof through said ore particles at a temperature from about 800* to about 900* F. c. reacting a chlorine-donating gas with said ore particles to form cuprous chloride therein, said reaction being carried out at a temperature within the range set forth in step (b) to maintain said cuprous chloride substantially in molten liquid form, d. passing a gas containing oxygen through said ore particles at a temperature within the range set forth in step (b) to liberate chlorine gas from metal chlorides therein other than said cuprous chloride, so that said liberated chlorine gas may react with and form additional molten liquid cuprous chloride from copper compounds not converted thereto during step (c), and e. passing a reducing gas through said ore particles at a temperature within the range set forth in step (b) to reduce said molten liquid cuprous chloride to metallic copper.
10. The improvement according to claim 9 which further comprises subsequent to step (e): f. quenching said ore particles in an aqueous cooling liquid, g. reducing said quenched ore particles to particles of which at least about 80 percent by weight passes a 100-mesh screen, h. flotating said reduced ore particles to separate a copper enriched fraction from the remainder thereof.