System, apparatus, and process for leaching metal and storing thermal energy during metal extraction

Patent metadata

Field	Value
Publication number	US-11390933-B2
Application number	US-202017023111-A
Country	US
Kind code	B2
Filing date	Sep 16, 2020
Priority date	Sep 9, 2014
Publication date	Jul 19, 2022
Grant date	Jul 19, 2022

Abstract

An environmentally friendly (e.g. no acid, base, or cyanide) system and process for large scale extraction of metal ion into aerobic molten salt (or ionic liquid) and the electrodeposition of metal (e.g. copper, gold, silver, etc.) from the metal ion dissolved in the molten salt. The non-volatile low vapor pressure liquid salt is reusable, and heat from the molten slag can heat the molten salts or ionic liquids. Another embodiment comprises a one-pot apparatus for the extraction of metal (e.g. copper) from metal earths and electrodepositing the metal using a low melting (209° C.) aerated Na—K—Zn chloride salt in which copper metal oxidizes and is converted to soluble copper chloride. When an electrical power supply is connected to the graphite vessel (cathode) and to copper rods in the melt (anodes), then the copper chloride is deposited as copper metal by electroreduction on the bottom of the graphite reaction vessel.

First claim

The invention claimed is:

1. An environmentally friendly leaching process for extracting and depositing metals from ore and slag, the process comprising:
(a) passing a molten ore or slag through a heat exchanger to transmit heat from the molten ore or slag to the heat exchanger;
(b) heating a non-volatile low vapor pressure liquid with the heat exchanger;
(c) transmitting the heated non-volatile low vapor pressure liquid to an open air crucible;
(d) dissolving ore or slag into the non-volatile low vapor pressure liquid in the open air crucible until the mixture is a liquid solution with metal ions and undissolved ore or slag;
(e) separating, using a filtration or decanting mechanism, said liquid solution from said undissolved ore or slag;
(f) transferring said liquid solution from the open air-crucible into an electrochemical reactor via the filtration or decanting mechanism, said electrochemical reactor comprising:
i. a high temperature resistant housing;
ii. a cathode electrode and an anode electrode connected to a direct current power supply on an upper end, and immersed in said liquid solution on a bottom end; and,
iii. one or more valves to drain said electrochemical reactor;

(g) applying a current between the cathode and anode electrode to electrify said liquid solution; and
(h) electro-depositing metal onto the cathode electrode from the metal ions in the electrified liquid solution,
wherein the electro-deposited metal is retrievable via the one or more valves of the electrochemical reactor.

2. The environmentally friendly leaching process of claim 1 , wherein the low vapor pressure liquid is a molten salt comprising a eutectic NaCl—KCl—ZnCl 2 composition.

3. The environmentally friendly leaching process of claim 1 , wherein the metal is selected from the group consisting of copper, silver, and gold, and any combination thereof.

4. The environmentally friendly leaching process of claim 1 , further comprising recycling the electrified liquid solution by passing the electrified liquid solution through the heat exchanger comprising melted slag that re-heats the electrified liquid solution.

5. The environmentally friendly leaching process of claim 4 , further comprising recycling the heated electrified liquid solution by transporting it back to the open air crucible.

6. The environmentally friendly leaching process of claim 1 , wherein dissolving the ore or slag into the low vapor pressure liquid in the open air container further comprises digesting and extracting metals from the ore or slag via oxidization of metal and metal sulphide to metal oxide, and converting the metal oxide into metal chloride.

7. The process of claim 1 , wherein the ore or slag being heated, mixed and dissolved into the low vapor pressure liquid is granulated ore or granulated slag.

8. The process of claim 1 , wherein the heated low vapor pressure liquid is transmitted to the open air crucible by way of a storage tank.

9. The process of claim 1 , further comprising,
(i) after passing the molten ore or slag through the heat exchanger, transmitting the molten ore or slag to a granulator;
(j) converting the molten ore or slag to a granulated ore or a granulated slag; and
(k) transmitting the granulated ore or the granulated slag to the open air crucible;
wherein (i)-(k) occur after (c) and prior to (d).

10. The process of claim 1 , wherein the electrochemical reactor further comprises a heating unit to heat the liquid solution.

11. The process of claim 1 , wherein the electrochemical reactor further comprises a pressure release mechanism.

12. A leaching system for extracting and depositing metals from ore and slag, comprising:
a. a mixing crucible configured to contain a first mixture of slag or ore with an aerobic low vapor pressure liquid;
b. a heat source;
c. a means for stirring;
d. a filtration or decanting mechanism positioned beneath said mixing crucible and able to remove undissolved slag or ore from the mixing crucible;
e. an electrochemical reactor configured to receive a metal ion-containing liquid from the mixing crucible via the filtration or decanting mechanism comprising:
i. a high temperature resistant, corrosion resistant crucible;
ii. a cathode electrode and an anode electrode connected to a power supply; and
iii. one or more valves to drain a metal-ion depleted liquid from the electrochemical reactor;

f. a movable re-cycle tank able to receive the metal-ion depleted liquid from the electrochemical reactor; and,
g. a heat exchanger device configured to receive the metal-ion depleted liquid from the re-cycle tank and able to transfer heat from a melted slag to the metal-ion depleted liquid.

13. The leaching system of claim 12 , wherein the aerobic low vapor pressure liquid comprises a molten salt or an ionic liquid.

14. The leaching system of claim 13 , wherein the molten salt is a eutectic composition of NaCl—KCl—ZnCl 2 .

15. The leaching system of claim 12 , wherein the electrochemical reactor is configured to maintain the metal ion-containing liquid at about four hundred to five hundred degrees Celsius.

16. The leaching system of claim 12 , further comprising a granulation tank for storing melted slag from the heat exchanger device, wherein the granulation tank is connected to the mixing crucible to mix the melted slag with the re-cycled molten salt or ionic liquid.

17. The leaching system of claim 12 , wherein the metal is selected from the group consisting of copper, silver, and gold, and any combinations thereof.

18. The leaching system of claim 12 , wherein the mixing crucible is able to mix the aerated molten salt until the metal within the slag or ore is extracted via oxidization of metal and low-valency metal cations and metal sulphide to metal oxide and the exchange of the sulfide and oxide in metal sulphide to metal oxide by chloride, thereby converting into metal chloride.

19. The leaching system of claim 12 , wherein the heat source is a melted slag or a heat-generating electromechanical device.

20. The leaching system of claim 12 , wherein the filtration or decanting mechanism further comprises a vacuum pump.

Assignees

• Clean Resources Pte Ltd
• Univ Arizona
• The Arizona Board Of Regent On Behalf Of The Univ Of Arizona

Inventors

• Jalbout Abraham Fouad
• Godinez Andres
• Gervasio Dominic Francis
• Elsentriecy Hassan H

Classifications

• Y02P10/20

  Recycling · CPC title

• C22B3/02

  Apparatus therefor · CPC title

• C22B7/04

  Working-up slag · CPC title

• C25C3/34

  of metals not provided for in groups C25C3/02 - C25C3/32 · CPC title

• C22B11/044 Primary

  from pyrometallurgical residues, e.g. from ashes, dross, flue dust, mud, skim, slag, sludge · CPC title