Apparatus and Process for the Improved Economic Extraction of Metal from a Metal-Bearing Material

Abstract

The present invention relates to an improved apparatus for economically extracting metal from a metal-bearing material. In particular, the present invention relates to an improved apparatus for extracting metal, including inter alia base metal (i.e. copper) and gold, from a metal-bearing ore, concentrate or other metal-bearing material. The present invention further extends to a process for the extraction of such metal which is carried out in accordance with the aforementioned apparatus. According to a first aspect thereof, the present invention provides an apparatus for extracting metal from a metal-bearing material, said apparatus, including a feed receptacle for receiving a metal-bearing feed stream; a reaction vessel; at least one pump means for delivering the metal-bearing feed stream to the reaction vessel; a means for introducing leaching agents, in the form of a leaching agent solution, to the reaction vessel; a means of agitation by circulating the metal-bearing feed stream and leaching agent solution in the reaction vessel so as to allow for a combination of agitation (tank) leaching and vat leaching to take place; a means for achieving liquid/solid separation; and a means for extracting a metal containing product; wherein said apparatus is re-locatable and transportable in order to allow the apparatus to be assembled easily on site without being geographically bound to one specific site.

Claims

1. An apparatus for extracting metal from a metal-bearing material, the apparatus comprising: a feed receptacle for receiving a metal-bearing feed stream; a reaction vessel; at least one pumping means for delivery of the metal bearing feed stream to the reaction vessel; a means for introducing leaching agents, in the form of a leaching agent solution, to the reaction vessel; a means for agitation and/or stirring and/or circulating the metal-bearing feed stream in the reaction vessel; a means for achieving liquid/solid separation; and a means for extracting a metal-containing product, wherein said apparatus is re-locatable and transportable in order to allow the apparatus to be assembled easily on site without being geographically bound to one specific site.

2-6. (canceled)

7. The apparatus according to claim 1, wherein the pumping means is a jet pump.

8. The apparatus of claim 7, wherein a centrifugal pump is used as a drive pump for the jet pump.

9. (canceled)

10. The apparatus of claim 7, wherein the jet pump is configured to achieve mixing of the metal-bearing feed stream and a leaching agent by circulation of these components through the jet pump.

11-16. (canceled)

17. The apparatus according to claim 1, wherein the reaction vessel is configured to receive and process at least 40 tons of dry feed material at a density of 50% solid material.

18-22. (canceled)

23. The apparatus according to claim 1, wherein the pumping means is configured to achieve separation of the reaction vessel constituents into contiguous upper and lower phases.

24. (canceled)

25. The apparatus of claim 23, wherein a down corner pipe is used to enhance the differential between the two phases.

26. The apparatus of claim 23, comprising a means for achieving liquid/solid separation.

27-28. (canceled)

29. The apparatus of claim 26, wherein an aspect ratio is such that it enhances liquid-solid separation.

30. The apparatus of claim 29, wherein the aspect ratio is between 3.93 to 4.66 H:W.

31-33. (canceled)

34. The apparatus according to claim 1, wherein the apparatus is modular.

35. The apparatus of claim 34, wherein upper and lower sections of the reaction vessel are modular, thereby allowing the reaction vessel to be dismantled and assembled easily on site or at further sites.

36. The apparatus of claim 35, wherein the reaction vessel is skid mounted.

37. The apparatus according to claim 1, wherein the dimensions and configuration of the apparatus are such that they substantially compliment dimensions of a containerized truck.

38. The apparatus of claim 37, wherein the dimensions accord to specific containerized truck dimensions and allow for pre-construction and/or assembly in workshops and/or factories.

39-41. (canceled)

42. A method for extracting metal from a metal-bearing material wherein said method comprises providing an apparatus of claim 1, introducing the metal-bearing material into the apparatus, and extracting the metal from the metal-bearing material.

43. The method, according to claim 42, wherein the metal-bearing material is a metal-bearing ore, metal concentrate, spiral concentrate or tailing that comprises copper, gold, silver, platinum group metals or mixtures thereof.

44. The method, according to claim 42, wherein process water is introduced for start-up conditions.

45. The method, according to claim 42, wherein one or more leaching agents are utilized during the circulation process.

46. The method, according to claim 48, wherein the leaching agent(s) are selected from hydrochloric acid (HCl), sulphuric acid (H.sub.2SO.sub.4), raffinate and iron sulphate (Fe.sub.2(SO.sub.4)).

47. The method, according to claim 42, wherein ferric sulphate and oxygen are introduced to accomplish leaching of the metal-bearing material.

48. The method, according to claim 42, wherein a portion of a circulated leaching agent solution is used as a sparging liquid to create a fluidized bed system.

49. The method, according to claim 42, comprising the transfer of washed leaching agent solution to a subsequent process or storage, while remaining solid solution is pumped out to tailings.

50. The method, according to claim 42, wherein reaction of leaching agents and metal-bearing material is carried out under ambient conditions.

51. The method, according to claim 42, wherein the apparatus is assembled at the site where the extraction is performed and/or wherein, upon completion of the extraction, the apparatus is disassembled and transported to a new location where it is re-assembled.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0089] FIG. 1 is a perspective view of the apparatus according to the present invention, showing inter alia, the feed receptacle and the reaction vessel;

[0090] FIG. 2 is a side view of the apparatus as depicted in FIG. 1;

[0091] FIG. 3 is a further side view of the apparatus as depicted in FIG. 1;

[0092] FIG. 4 is a top view of the apparatus as depicted in FIG. 1;

[0093] FIG. 5 is an isoview of the piping configuration of the apparatus as depicted in FIG. 1;

[0094] FIG. 6 is a top view of the apparatus as depicted in FIG. 1;

[0095] FIG. 7 is a bottom view of the apparatus as depicted in FIG. 1;

[0096] FIG. 8 depicts a diagram showing the leaching efficiency results from a prototype plant (commercial scale) in the DRC; and

[0097] FIG. 9 depicts a diagram showing the leaching kinetic results for a 20t leach test in the prototype plant located in the DRC.

DESCRIPTION OF THE INVENTION

[0098] FIGS. 1 to 7 represent the apparatus of the present invention, designed to scale for commercial purposes, showing inter alia, the feed receptacle and reaction vessel.

Example 1: Improved Economic Extraction of Copper from a Copper-Bearing Feed Material

[0099] Solids or copper-rich feed material (not shown) is fed dry into a feed receptacle, in the form of a feed bin 2 of the apparatus 1. The bottom of the feed bin is equipped with a jet pump 4 which transfers the solids from the feed bin 2 to the reaction vessel, in the form of a reactor 3. The jet pump 4 produces a vacuum by means of the venturi effect. A centrifugal drive pump 5 is used as the drive pump for generating the flow through the jet pump 4. The reactor 3 is equipped with an additional jet pump 6 similar to the jet pump 4 located in feed bin 2. The jet pump 6 is capable of pumping up to 55% solids and uses either process water for start-up conditions or leach solution during the circulation process.

[0100] The reactor 3 is designed to treat a batch of 40 tons of dry feed (up to 5 mm) at a density of 50% solids. The 40 tons of feed material is loaded into the reactor 3 through the feed bin 2 and jet pump 4 once the reactor 3 is filled with either process water (not shown) or leach solution (not shown) to the required volume. The filling process is achieved via the centrifugal drive pump 5. Leach reagents (not shown) are introduced through the feed system 7 until the required free acid levels are obtained.

[0101] The combination of agitation (tank) leaching and vat leaching commences by circulating the solids and leach solution through the reactor 3. The centrifugal drive pump 5 draws leach solution from the top of the reactor 3 and then circulates the solution through the jet pump 6 and back into the reactor 3.

[0102] The venturi created by the jet pump 6 draws solids from the bottom of the reactor 3 and circulates with the leach solution back to the reactor 3. The circulated slurry is introduced to the reactor 3 through a down pipe 8 developing a liquid-solid interface. The top part of the reactor 3 mainly comprises liquid phase and the bottom section mainly slurry phase. A portion of the circulated leach solution is used as sparging liquid in the cone section of the reactor 3 in order to create a fluidized bed system. The cone fluidization aids as agitation and prevents the solids from settling and improves leaching kinetics.

[0103] Once the leaching process is complete and equilibrium is reached, the circulation and fluidization process is stopped. The solids are allowed to settle and liquid/solid separation takes place. The bulk of the pregnant leach solution (PLS) is now drawn from the top of the reactor 3 and pumped to the next process or PLS storage.

[0104] The PLS left behind in the slurry phase at the bottom of the reactor 3 is washed with process water via the centrifugal drive pump 5 and jet pump 6 combination. Once the slurry is sufficiently washed from all the remaining copper in solution, it is allowed to settle and the final liquid/solid separation step will commence. The final washed leach solution is then transferred from the top of the reactor 3 to the next process or PLS storage whilst the remaining solids in the bottom compartment of the reactor 3 are pumped out to tailings.

[0105] The reactor 3 is now ready for the next batch. A series of batch reactors 3 can be used in order to produce a continuous flow of PLS, simulating a semi-batch operation.

[0106] Having described the invention in detail and by reference to the aspects and embodiments thereof, the scope of the present invention is not limited only to those described characteristics, aspects or embodiments. As will be apparent to persons skilled in the art, modifications, analogies, variations, derivatives and adaptations to the above-described invention can be made on the base of art-known knowledge and/or on the base of the disclosure (e.g. the explicit, implicit or inherent disclosure) of the present invention without departing from the spirit and scope of this invention.

[0107] A prototype unit was constructed on commercial scale and tested in the DRC on copper concentrate from an existing mining operation. The copper material tested was a spiral concentrate. The material composition and test results are indicated in table 1 & 2 below. The Cu extraction achieved was above 90% similar to other conventional methods.

TABLE-US-00001 TABLE 1 Results from 20t leach Mass balance (20t leach) Mass Volume Cu H2SO4 Co Fe Cu H2SO4 Co Fe t m3 w/w or g/l g/L w/w w/w kg kg kg kg IN Solids-feed 18.8 6.7 11.5% 0 0.05% 9.34% 2 160 0 9.4 1 758 Acid 4.0 2.2 0 102.6 0.00 0.00 0 4 048 0.0 0 Process water 39.5 39.5 0 0 0 0 0 0 0.0 0 into system Total 62.3 48.4 2 160 4 048 9.4 1 758 OUT Solids-residue 13.2 4.7 1.0% 0 0.11% 15.08% 129 0 14.5 1 987 Solution to CCD0 23.0 23.0 48.6 3.3 0.07 0.12 1 117 77 1.6 2.8 Residual solution 20.7 20.7 48.6 3.3 0.07 0.12 1 004 69 1.4 2.5 Total 56.9 48.4 2251 145 17.6 1992

TABLE-US-00002 TABLE 2 Results from 40t leach Mass balance (40t leach) Cu H2SO4 Co Fe Mass Volume w/w or w/w or w/w or w/w or Cu H2SO4 Co Fe t m3 g/L g/L g/L g/L kg kg kg kg IN Solids-feed 40.6 14.5 10.9% 0 0.07% 6.34% 4 430 0 28.4 2574.5 Acid-Leach 1 4.4 2.4 0 145.8 0 0 0 4 416 0 0 Acid-Leach 2 2.2 1.2 0 78.4 0 0 0 2 208 0 0 Acid-Leach 3 1.7 0.9 0 64.4 0 0 0 1 656 0 0 Process water into system- 30.3 30.3 0 0 0 0 0 0 0 0 Process water into system- 28.2 28.2 0 0 0 0 0 0 0 0 Process water into system- 25.7 25.7 0 0 0 0 0 0 0 0 Process water into system- 32.2 32.2 0 0 0 0 0 0 0 0 Total 165.2 135.4 4 430 8 280 28.4 2574.5 OUT Solids-residue 28.4 10.2 5.2% 0 0.09% 9.56% 1481 0 25.6 2717.5 Solution to CCD0-Leach 1 19.5 16.0 67.5 14.5 0.03 2.65 1 079 232 0.5 42.4 Solution to CCD0-Leach 2 20.8 18.0 58.7 28.9 0.02 2.69 1 056 520 0.4 48.3 Solution to CCD0-Leach 3 18.0 15.7 50.9 68.3 0.00 3.34 801 1074 0.0 52.5 Solution to CCD0-Wash 26.3 23.0 30.3 35.6 0.00 2.05 696 818 0.0 47.2 Residual solution 24.4 21.3 30.3 35.6 0.00 2.05 645 758 0.0 43.7 Total 142.0 108.2 5 901 3 767 26.5 2962.5