WO2007140554A1 - An ore heap leaching process for metal production with the aid of solar energy - Google Patents

An ore heap leaching process for metal production with the aid of solar energy Download PDF

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Publication number
WO2007140554A1
WO2007140554A1 PCT/BR2007/000136 BR2007000136W WO2007140554A1 WO 2007140554 A1 WO2007140554 A1 WO 2007140554A1 BR 2007000136 W BR2007000136 W BR 2007000136W WO 2007140554 A1 WO2007140554 A1 WO 2007140554A1
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WO
WIPO (PCT)
Prior art keywords
metal
solar energy
solution
aid
leaching process
Prior art date
Application number
PCT/BR2007/000136
Other languages
French (fr)
Inventor
Flávia Dutra MENDES
Renato De Souza Costa
Original Assignee
Companhia Vale Do Rio Doce
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Companhia Vale Do Rio Doce filed Critical Companhia Vale Do Rio Doce
Publication of WO2007140554A1 publication Critical patent/WO2007140554A1/en

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B1/00—Preliminary treatment of ores or scrap
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B1/00—Preliminary treatment of ores or scrap
    • C22B1/14—Agglomerating; Briquetting; Binding; Granulating
    • C22B1/24—Binding; Briquetting ; Granulating
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B3/00—Extraction of metal compounds from ores or concentrates by wet processes
    • C22B3/02—Apparatus therefor
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B3/00—Extraction of metal compounds from ores or concentrates by wet processes
    • C22B3/04—Extraction of metal compounds from ores or concentrates by wet processes by leaching
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00—Technologies related to metal processing
    • Y02P10/20—Recycling

Definitions

  • the present report relates to a heap leaching process in which the use of solar energy, particularly the use of solar collectors to heat the pile, makes it possible to improve process economics as well as to reduce both environmental impact and leach cycle time.
  • the heap leaching process is used worldwide for the extraction of metals - namely, but not limited to, copper, gold, and uranium - from ores.
  • the leaching process is simple and involves the following conventional unit operations: crushing, agglomeration, stacking, spraying of the leaching solution, and collection of the percolated liquor.
  • the heap leaching technique begins with ore preparation, which involves crushing the raw ore down to the process grain size as defined from laboratory tests.
  • maximum ore size varies from 12 mm to 75 mm depending on the type of metal to be extracted, the mineralogy, dissolution kinetics, etc. Fines are generated during crushing in an amount, which depends on how small the maximum ore size is.
  • the crushed material is subjected to a second stage consisting in agglomerating the produced fines, with ancillary agglutinating agents being added to the material.
  • ancillary agglutinating agents must be compatible with the heap leaching process condition. Should the leaching process be performed within the alkaline pH range, basic agglutinating agents shall be used. Otherwise, i.e. within the acidic pH range, either acid or neutral reagents shall be used.
  • the agglomerated material is conveyed to a pile 2 to 10 meters in height, which is determined according to what has been defined from previous tests on the mechanical strength of the ore.
  • the leaching solution containing the specific reagent is then sprayed onto the pile to dissolve the target metal. This solution percolates through the agglomerated ore down to the base of the pile, where it is collected for further processing for recovery of the target metals.
  • the recovery process varies with respect to the unit operations to be used for the type of metal to be recovered, and may comprise, but is not limited to, chemical purification, selective solvent extraction, adsorption in organic compounds, and releaching. Finally, the desired end products can be obtained by electrowinning and/or reduction to the metallic state.
  • the heap leaching process may become unfeasible for ores requiring long cycles (i.e. generally more than 360 days), because, in addition to causing much greater environmental impact, preparation of the heap leach pile is an onerous stage in that it requires large areas for pile buildup.
  • One of the objectives of the present invention is therefore to provide an ore heap leaching process for metal production with the aid of solar energy, which makes it possible to increase the temperature inside the pile, thereby substantially increasing the dissolution kinetics of target elements. This makes for reduction of both the industrial process operation cycle time and the pile unit area for the same production capacity, consequently reducing environ- mental impact as well.
  • Another objective of the present invention is to provide an ore heap leaching process for metal production with the aid of solar energy, which makes it possible to reduce investments and consequently, to improve process economics.
  • Another objective of the present invention is to provide an ore heap leaching process for metal production with the aid of solar energy, to be implemented in tropical regions with plenty of sunshine and long periods of dry weather.
  • Another objective of the present invention is to provide an ore heap leaching process for metal production with the aid of solar energy, to be implemented in regions with positive water balance, where the increase in solution temperature causes evaporation of excess water, thereby increasing the concentration of target elements in the solution and facilitating the operation of the industrial unit.
  • Figure 1 is a schematic exploded view in perspective of the collectors
  • Figure 2 is a flow chart of the heap leaching process without using the collectors shown in figure 1 ;
  • Figure 3 is a flow chart of the heap leaching process using the collectors as shown in figure 2.
  • the solar collectors (10) are made of spaced glass plates (V), pipes (T) for transporting the solution (S) to be heated, blackened aluminum plate (CE), copper serpentine coil (SC), thermal insulation material (I), plate (C) and frame (M) for accommodating all the components of the solar collector.
  • the heap leaching proc- ess begins with ore crushing (1), followed by fines agglomeration (2), and then addition of sulfuric acid and/or additives (3) to produce the heap leach pile (4).
  • said heap leach pile (4) receives the leaching solution (5), thereby originating a target metal-pregnant solution, which is stored in a reservoir (6) and then subjected to a metal recovery stage (7), originating a target metal-poor solution (8).
  • the stored metal-poor solution (8) is reconcentrated with the leaching solution (5) and then returned to the heap leach pile (4). It should be pointed out that a portion of the metal-pregnant solution (6) can be conveyed directly to the metal recovery stage (7) and then be returned to the leaching solution reservoir (5).
  • the novelty of the present invention is that the reservoir of the metal-poor solution (8) is heated by the solar energy collected by solar collectors (10), thereby providing the heating of the leaching solution (5) that is kept in a thermally insulated vessel to maintain the temperature and better utilize the collected energy.
  • Process water (9) is added for the preparation of the leaching solution (5), as well as for maintaining the industrial conditions, as significant evaporation occurs in the area of both the pile and the reservoir of the metal-pregnant solution (6). In this way, the dissolution kinetics of the target elements increases significantly, reducing both the unit area and the piles for the same production capacity and reducing the operation cycle time of the pile.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Manufacturing & Machinery (AREA)
  • Geochemistry & Mineralogy (AREA)
  • Geology (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Environmental & Geological Engineering (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Manufacture And Refinement Of Metals (AREA)

Abstract

'AN ORE HEAP LEACHING PROCESS FOR METAL PRODUCTION WITH THE AID OF SOLAR ENERGY', involving ore crushing (1 ), followed by fines agglomeration (2), and then addition of sulfuric acid and/or additives (3) to produce the heap leach pile (4); next, said heap leach pile (4) receives the leaching solution (5), thereby originating a target metal-pregnant solution, which is stored in a reservoir (6) and then is subjected to a metal recovery stage (7), originating a target metal-poor solution (8), at which point a process stage is included, in which both the metal-poor solution reservoir (8) and the water (9) are heated by the solar energy collected by solar collectors (10), thereby providing the heating of the leaching solution (5) that is kept in a thermally insulated vessel to maintain the temperature and better utilize the collected energy.

Description

"AN ORE HEAP LEACHING PROCESS FOR METAL PRODUCTION WITH THE AID OF SOLAR ENERGY".
The present report relates to a heap leaching process in which the use of solar energy, particularly the use of solar collectors to heat the pile, makes it possible to improve process economics as well as to reduce both environmental impact and leach cycle time.
As is known by those skilled in the art, the heap leaching process is used worldwide for the extraction of metals - namely, but not limited to, copper, gold, and uranium - from ores. The leaching process is simple and involves the following conventional unit operations: crushing, agglomeration, stacking, spraying of the leaching solution, and collection of the percolated liquor.
The heap leaching technique begins with ore preparation, which involves crushing the raw ore down to the process grain size as defined from laboratory tests. In general, maximum ore size varies from 12 mm to 75 mm depending on the type of metal to be extracted, the mineralogy, dissolution kinetics, etc. Fines are generated during crushing in an amount, which depends on how small the maximum ore size is.
The crushed material is subjected to a second stage consisting in agglomerating the produced fines, with ancillary agglutinating agents being added to the material. Such agents must be compatible with the heap leaching process condition. Should the leaching process be performed within the alkaline pH range, basic agglutinating agents shall be used. Otherwise, i.e. within the acidic pH range, either acid or neutral reagents shall be used. The agglomerated material is conveyed to a pile 2 to 10 meters in height, which is determined according to what has been defined from previous tests on the mechanical strength of the ore. The leaching solution containing the specific reagent is then sprayed onto the pile to dissolve the target metal. This solution percolates through the agglomerated ore down to the base of the pile, where it is collected for further processing for recovery of the target metals.
The recovery process varies with respect to the unit operations to be used for the type of metal to be recovered, and may comprise, but is not limited to, chemical purification, selective solvent extraction, adsorption in organic compounds, and releaching. Finally, the desired end products can be obtained by electrowinning and/or reduction to the metallic state.
Although widely used, the heap leaching process may become unfeasible for ores requiring long cycles (i.e. generally more than 360 days), because, in addition to causing much greater environmental impact, preparation of the heap leach pile is an onerous stage in that it requires large areas for pile buildup.
Another drawback of the heap leaching process is that it generally occurs in a large uncovered open-air area and therefore rainwater infiltration into the pile renders the operation difficult, particularly during periods of high rainfall, due to both the diluting effect of water and operational problems in handling excess water.
Another drawback of the heap leaching process is that the temperature of the process is maintained at ambient temperature, which renders the process slow and requires a vast area per unit of produced metal (in general, for a leach cycle of 360 days, the required area is approximately 50 sq m per ton of metal per annum), resulting in high investment cost.
Techniques aimed at solving these problems are currently being implemented, such as reducing ore grain size, which significantly reduces both the percolation rate and the operation cycle time, but also reduces productiv- ity. Ancillary leaching agents are also being used with the main objective of increasing reaction kinetics, but, although this is a good method, it has not been found to be efficient in certain cases
One of the objectives of the present invention is therefore to provide an ore heap leaching process for metal production with the aid of solar energy, which makes it possible to increase the temperature inside the pile, thereby substantially increasing the dissolution kinetics of target elements. This makes for reduction of both the industrial process operation cycle time and the pile unit area for the same production capacity, consequently reducing environ- mental impact as well.
Another objective of the present invention is to provide an ore heap leaching process for metal production with the aid of solar energy, which makes it possible to reduce investments and consequently, to improve process economics. Another objective of the present invention is to provide an ore heap leaching process for metal production with the aid of solar energy, to be implemented in tropical regions with plenty of sunshine and long periods of dry weather.
Another objective of the present invention is to provide an ore heap leaching process for metal production with the aid of solar energy, to be implemented in regions with positive water balance, where the increase in solution temperature causes evaporation of excess water, thereby increasing the concentration of target elements in the solution and facilitating the operation of the industrial unit. The foregoing and other objectives and advantages of the present invention are attained by an ore heap leaching process for metal production with the aid of solar energy, involving the use of solar collectors to heat the leaching solution, and keeping said leaching solution inside a thermally insulated vessel so as to maintain the temperature and thus better utilize the collected energy. The present invention will be described with reference to the drawings attached hereto, in which:
Figure 1 is a schematic exploded view in perspective of the collectors;
Figure 2 is a flow chart of the heap leaching process without using the collectors shown in figure 1 ; and
Figure 3 is a flow chart of the heap leaching process using the collectors as shown in figure 2.
It is pertinent to point out that the only known use of collected solar energy to assist the leaching process is via solution recirculation pipes placed on top of the ore pile, whereas the concept as described herein, of combining the conventional solar heating technology, renders the technique much more efficient.
As can be seen in figure 1 , the solar collectors (10) are made of spaced glass plates (V), pipes (T) for transporting the solution (S) to be heated, blackened aluminum plate (CE), copper serpentine coil (SC), thermal insulation material (I), plate (C) and frame (M) for accommodating all the components of the solar collector.
As shown in the flow chart in figure 2, the heap leaching proc- ess begins with ore crushing (1), followed by fines agglomeration (2), and then addition of sulfuric acid and/or additives (3) to produce the heap leach pile (4). Next, said heap leach pile (4) receives the leaching solution (5), thereby originating a target metal-pregnant solution, which is stored in a reservoir (6) and then subjected to a metal recovery stage (7), originating a target metal-poor solution (8).
In traditional leaching, the stored metal-poor solution (8) is reconcentrated with the leaching solution (5) and then returned to the heap leach pile (4). It should be pointed out that a portion of the metal-pregnant solution (6) can be conveyed directly to the metal recovery stage (7) and then be returned to the leaching solution reservoir (5).
According to the flow chart shown in figure 3, the novelty of the present invention is that the reservoir of the metal-poor solution (8) is heated by the solar energy collected by solar collectors (10), thereby providing the heating of the leaching solution (5) that is kept in a thermally insulated vessel to maintain the temperature and better utilize the collected energy. Process water (9) is added for the preparation of the leaching solution (5), as well as for maintaining the industrial conditions, as significant evaporation occurs in the area of both the pile and the reservoir of the metal-pregnant solution (6). In this way, the dissolution kinetics of the target elements increases significantly, reducing both the unit area and the piles for the same production capacity and reducing the operation cycle time of the pile.
Although a preferred embodiment of this solution has been described and illustrated, it bears pointing out that other solutions can be accom- pushed without departing from the scope of the present invention.

Claims

Claims
1- "AN ORE HEAP LEACHING PROCESS FOR METAL PRODUCTION WITH THE AID OF SOLAR ENERGY", involving ore crushing (1), followed by fines agglomeration (2), and then addition of sulfuric acid and/or addi- tives (3) to produce the heap leach pile (4); next, said heap leach pile (4) receives the leaching solution (5), thereby originating a target metal-pregnant solution, which is stored in a reservoir (6) and then is subjected to a metal recovery stage (7), originating a target metal-poor solution (8), the process being characterized by the fact that both the metal-poor solution reservoir (8) and the water (9) are heated by the solar energy collected by solar collectors (10), thereby providing the heating of the leaching solution (5) that is kept in a thermally insulated vessel to maintain the temperature and better utilize the collected energy.
2- "AN ORE HEAP LEACHING PROCESS FOR METAL PRODUCTION WITH THE AID OF SOLAR ENERGY", according to claim 1 , charac- terized by the fact that the solar collectors (10) are made of spaced glass plates (V), pipes (T) for transporting the solution (S) to be heated, blackened aluminum plate (CE), copper serpentine coil (SC), thermal insulation material (I), plate (C) and frame (M) for accommodating all the components of the solar collector.
3- "AN ORE HEAP LEACHING PROCESS FOR METAL PRO- DUCTION WITH THE AID OF SOLAR ENERGY", according to claim 1 , characterized by the fact that it makes possible to increase the temperature inside the pile, thereby substantially increasing the dissolution kinetics of target elements and, thus, making for the reduction of both the industrial process operation cycle time and the pile unit area for the same production capacity, consequently reduc- ing environmental impact as well.
4- "AN ORE HEAP LEACHING PROCESS FOR METAL PRODUCTION WITH THE AID OF SOLAR ENERGY", according to claim 1 , characterized by the fact that it makes possible to reduce investments and consequently, to improve process economics. 5- "AN ORE HEAP LEACHING PROCESS FOR METAL PRODUCTION WITH THE AID OF SOLAR ENERGY", according to claim 1 , characterized by the fact that it is implemented in tropical regions with plenty of sunshine and long periods of dry weather. 6- "AN ORE HEAP LEACHING PROCESS FOR METAL PRO¬
DUCTION WITH THE AID OF SOLAR ENERGY", according to claim 1 or 5, characterized by the fact that it is implemented in regions with positive water balance, where the increase in solution temperature causes evaporation of excess water, thereby increasing the concentration of target elements in the solu- tion and facilitating the operation of the industrial unit.
PCT/BR2007/000136 2006-06-02 2007-05-30 An ore heap leaching process for metal production with the aid of solar energy WO2007140554A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
BRPI0602731-8 2006-06-02
BRPI0602731-8A BRPI0602731A (en) 2006-06-02 2006-06-02 ore heap leaching process for metal production assisted by solar energy

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2012106831A2 (en) * 2011-02-08 2012-08-16 Hernandez Pavez Jose Octavio Method and system for the solar heap leaching of minerals, using solar concentrating collectors, based on fresnel lenses with solar tracking
WO2014075148A1 (en) * 2012-11-15 2014-05-22 Technological Resources Pty. Limited Heap leaching

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4739973A (en) * 1986-08-13 1988-04-26 Herndon J Marvin Chemical extraction of metals from ores
US6149711A (en) * 1999-03-18 2000-11-21 Lane; Richard P. Method and apparatus for solar heating and distributing a mining leach solution
US6743276B1 (en) * 2001-08-17 2004-06-01 Richard P. Lane Method and apparatus for solar heating a mining leach solution

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4739973A (en) * 1986-08-13 1988-04-26 Herndon J Marvin Chemical extraction of metals from ores
US6149711A (en) * 1999-03-18 2000-11-21 Lane; Richard P. Method and apparatus for solar heating and distributing a mining leach solution
US6743276B1 (en) * 2001-08-17 2004-06-01 Richard P. Lane Method and apparatus for solar heating a mining leach solution

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2012106831A2 (en) * 2011-02-08 2012-08-16 Hernandez Pavez Jose Octavio Method and system for the solar heap leaching of minerals, using solar concentrating collectors, based on fresnel lenses with solar tracking
WO2012106831A3 (en) * 2011-02-08 2012-11-15 Hernandez Pavez Jose Octavio Method and system for the solar heap leaching of minerals, using solar concentrating collectors, based on fresnel lenses with solar tracking
WO2014075148A1 (en) * 2012-11-15 2014-05-22 Technological Resources Pty. Limited Heap leaching
US10060008B2 (en) 2012-11-15 2018-08-28 Technological Resources Pty. Limited Heap leaching
US10815550B2 (en) 2012-11-15 2020-10-27 Technological Resources Pty. Limited Heap leaching

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