Etango uranium project heap leach demonstration program phase 1 july 2015. Heap leaching as a hydrometallurgical process is one of the cheapest methods and particularly useful in the case of. This process was later on employed for recovering metals from ores containing low quantity of the metal. Similar to in situ mining, heap leach mining differs in that it places ore on a liner, then adds the chemicals via drip systems to the. Lessons learnt from heap leaching operations in south america. Pdf heap leaching is a lowcost technology used in industrial mining to recover precious metals such as gold and uranium, along with several other. The leaching process in mining is carried out either as heap leaching or insitu leaching. Treatment of cyanide heap leaches and tailings 2 since the 1970s and early 1980s, heap leaching has developed into an efficient way to beneficiate a variety of lowgrade, oxidized gold ores. The acceptance of binder is limited due to the lack of acidtolerant binders. Heap leaching is an industrial process for extracting precious metals and minerals by dissolving them from ore with liquids known as leaching solutions. Heap leaching of gold ore started to gain promenence in the late 1960s when it was applied on a large scale to low grade ores that were uneconomic to procees by conventional tank leach methods.
Improvements in copper heap leaching by use of wetting agents proceedings of emc 2009 3 a sprinkler system is installed on top of each heap allowing the diluted sulfuric acid to be fed uniformly over the ore. Hpgr grindingagglomeration may have some advantages. In addition to conventional uranium milling and in situ recovery isr, which are currently used to extract uranium from ore, some nrclicensed facilities used extraction methods. The problem of copper leaching is compounded when multiple lifts are placed on the heap as is usually the. Heap leaching as a hydrometallurgical process is one of the cheapest methods and particularly useful in. A brief note on the heap leaching technologies for the. Gardner synopsis the basis of this paper is a compilation of work in the design and construction of copper heap leach facilities, and interviews with various heap leach operations personnel in chile and peru. Heap leach stacks can near 200m as operations look to more quickly prove and sustain site yield. As the leaching agent filters through the heap, the uranium will break its bonds with the.
The flowsheet resembles the front end of the processing plant up to the heap leaching stage. The cyanide percolates down through the heap for several weeks, leaching out the gold. Process of heap leaching the mined ore is crushed into tiny chunks and heaped on an impermeable plastic andor clay lined leach pad where it may be irrigated with a. It is less well known that heap leaching operations are carried out successfully in cold. Leaching also takes place in nature, where the rocks are dissolved by water. What links here related changes upload file special pages permanent link. In the case of heap leaching, the uranium ore is mined, placed on a pad in heaps 530 metres high and irrigated with acid or alkaline solution over many weeks, leaching uranium into the resulting pregnant liquor, which is then collected and treated to extract the uoc. Comparable to in situ mining, heap leach mining differs in that it uses a liner to place amounts of ore on, then adds the chemicals via. Leaching of uranium and vanadium from korean domestic ore. The extraction of precious metals from ore using heap leaching is a common method of production. Mining of the ore is conventional either underground or surface and the ore is placed on surface pads where extractive liquors acid or alkaline are pumped over and through the material.
Modern day heap leaching, which has a relatively low level of energy consumption, is for example. After completion of the leaching process within months to years, the leached ore is either left in place, or removed to a disposal site, and new ore is placed on the leach pad socalled onoff scheme, or dynamic heap leaching. Heap leaching and the water environment does low cost. Heap leaching technology moving the frontier for treatment. Estimated water requirements for gold heapleach operations. At infinite separation ie very dilute slurry leaching the leach particle dimension is the actual crushed particle size. Presently certain metals from sulfide ores and other ores are.
Dynamic simulation of heap leach flowsheets brett muller and tim newton simulus. Pdf heap leaching technologycurrent state, innovations, and. Heap leaching mining techniques, metals mining, copper mining. Lessons learnt from heap leaching operations in south america an update by b. Etango uranium project heap leach demonstration program. Introduction, methods, application, copper, microorganisms, and processes. Uranium mining is the process of extraction of uranium ore from the ground. Pdf conventional heap leaching of uranium ore is neither a new concept historically in the united states, nor is the idea unfamiliar on a. Concise overviews of quality control and characterization tools are provided. Heap leaching of lowgrade uranium ore was attempted at the nabarlek. Heap leaching is an industrial mining method to dig out precious metals and copper compounds from ore. The leaching process has literally made many mines by taking low grade geological resources and. Compared to tank leaching, heap leaching has several advantages, including simplicity of design, lower capital and operating costs, and shorter startup. Heap leaching is an industrial mining process of separating precious metals, copper, and other minerals, from ores.
In a research paper, researcher mark smith suggests the first use of heap leaching occurred at the bluebird copper oxide mine during in the late 1960s, with other western united states gold mines following suit in the 1970s. First, bottleroll tests of finely ground material are run. Heap leaching is an industrial mining process to extract precious metals, copper, uranium, and other compounds from ore via a series of chemical reactions that absorbs specific minerals and then reseparate them after their division from other earth materials. In an operating cyanide heap leach, copper will begin to leach from fresh ore on the heap, and if unchecked can build up in solution to levels that begin to affect gold recovery and cyanide consumption, in turn affecting project economics. Typical operations take place for about one to three months per heap and the recovery achieved is at least 60% and may be as high as 85% in some cases. Understanding the timerateofrecovery dynamics in heapleach operations is mandatory for analyzing the financial performance of any mining operation. Heap leaching is, in contrast to many dump leaching operations, a preplanned process where arrangements are made to optimize conditions for leaching. Water is required for drilling and dust suppression during mining, for. Heap leaching of richclay copper ores is becoming ordinary practice at many sites. A very broad range of processes are used for the recovery of valuable metals. Different agglomerationheap leaching systems are summarized. Although heap leaching has become established as the technology for treatment of some copper, gold, and zinc minerals, as well as its extension to the treatment of other types of minerals such as saltpeter and mine tailings, little study has been made on the optimization of this technology. At the same time, theyre constantly on the lookout for suitable and costeffective equipment and systems for every heapleaching project.
Understanding the timerateofrecovery dynamics in heap leach operations is mandatory for analyzing the financial performance of any mining operation. The combination of such understanding with advanced flow and. Bleiwas introduction this report provides a perspective on the amount of water necessary for conventional gold heap leach operations. Heap leaching is a relatively simple process with 3 components. The growth of heap leaching is heavily tied to the massive scale on which mines are being built, with some sites requiring huge investments. Cement, limestone or fly ash are used for heap leaching gold ores with cyanide, and could be considered for alkaline heap leaching of uranium ores or ammonia leaching of copper oxide ores. While the solution percolates through the heap, copper is leached out of the ore. Pdf heap leaching is a wellestablished extractive metallurgical technology. Post leaching, the rocks are left with a smaller proportion of minerals than they originally contained. Then, agglomerates have been leached during 10 days with sulfuric acid at 10gl. Mar 28, 2020 heap leaching is an industrial process for extracting precious metals and minerals by dissolving them from ore with liquids known as leaching solutions. Heap leaching is a tried and tested mining technique enabling the processing of different kinds of ores which could not otherwise be exploited under viable economic conditions. Sustainable issues related to heap leaching operations. Bench scale metallurgical testing of ores for their amenability to vat leaching is similar to that for heap leaching.
Its also a must for the successful execution of a project. The first use of cyanide for leaching of gold and silver ores was in england in 1887 by j. Heap leachionexchange operations involve the following process. Heap leaching hl is a flexible and economic mineral processing method, commonly used to extract gold from lowgrade gold ores. Today heap leaching is used in several hundred mining operations in countries across the world including the united states of america, canada, australia, argentina, chile, etc. Heap leach and ionexchange facilities through the years, the u. Archived from the original pdf on november 22, 2008. Agglomeration is generally carried out in a rotating drum.
Of note is the potential dual use of the crushing circuit for both the main cilp plant and the heap leach. Process of heap leaching the mined ore is crushed into tiny chunks and heaped on an impermeable plastic andor clay lined leach pad where it may be irrigated with a leach solution to melt the valuable metals. The etango project is one of the worlds largest undeveloped uranium deposits, located in the erongo uranium mining. Heap leaching is a tried and tested mining technique enabling the processing of. Smith, rrd lnternotionol corp, usa abstrqct heap leaching is no stranger to extreme climates. Nuclear regulatory commission nrc has licensed numerous uranium recovery facilities in the united states, which used a variety of extraction methods. Heap leaching heap leaching is being done these days on relatively lowgrade ores for gold, copper and uranium recovery. Dynamic simulation of heap leach flowsheets brett muller and tim newton simulus presented by brett muller brett.
The huge heaps described above are sprayed with a dilute solution of sodium cyanide, and this percolates down through the piled ore, dissolving the gold. Uranium is the main source to generate the nuclear power as cheap and more. Heap leaching is an industrial mining process used to extract precious metals, copper, uranium, and other compounds from ore using a series of chemical reactions that absorb specific minerals and reseparate them after their division from other earth materials. Cyanide heap leaching university of colorado boulder. Treatment of ore is sitespecific as determined by metallurgical tests. Pdf structural and physical properties of uraniumore. Recovery of copper from oxide copper ore by flotation and leaching kiraz, emirhan m. This could be extended to some degree to assess the leaching of agglomerates in a heap, as rigid spheres of the agglomerate size distribution. Pdf a brief note on the heap leaching technologies for the. Jun 28, 2016 this feature is not available right now. On the optimization of heap leaching sciencedirect. Attendees included project managers, operators and environmental professionals. Heap leaching is usually carried out in the open and on. Heap leaching, heap leaching consulting, heap leaching of.
Nov 26, 2004 a very broad range of processes are used for the recovery of valuable metals. Lessons learnt from heap leaching operations in south. Sustainable issues related to heap leaching operations stability of the ore heap. During leaching, the piles present a hazard because of release of dust, radon gas and leaching liquid. Hpgr has been shown to influence the extraction and kinetics of leaching low grade gold ores. Bleiwas introduction this report provides a perspective on the amount of water necessary for conventional gold heapleach operations. Heap recovery heal leaching, uranium production heap leaching is an alternative method of extracting uranium rich liquor from extracted ore.
In this process, ore is firstly crushed to fine particles. In brief, the mineral ore or concentrate is piled in a heap and lixiviant fluid is distributed over the surface to leach metal from the heap. Cyanidation extracting gold from lowgrade ores, heap leaching is practiced. Instability of the ore either static, seismic, or during extreme rainfall can lead to loss of the facility, failure of the liner system, and loss of environmental containment maximum overall slope for the ore heap lifts heights and setbacks. The ore is placed on geomembranelined heap leach pads and the oreladen solution is drained through lined ditches into impoundments for holding prior to extraction. By spraying leaching solution to the large piles, the goldcontaining solution is leached.
Heap leaching technologycurrent state, innovations, and future directions. Lessons learnt from heap leaching operations in south americaan update onoff heap leach padthese facilities use similar pads and collection systems as the permanent pad but each lift is removed after it has been leached. Pdf heap leaching technologycurrent state, innovations. Nonetheless, heap leaching has also been used to extract uranium from ore at conventional mills, and ionexchange procedures have been used to separate uranium from the liquid extract at both conventional mills and isr facilities. At the same time, theyre constantly on the lookout for suitable and costeffective equipment and systems for every heap leaching project. The vat leaching process vat leaching can be described as leaching in a bathtub inside a building.
The process is commonly used to extract metals such as gold, copper, and uranium yellowcake in addition to several other minerals. Heap leaching and its application to copper, uranium. It involves a series of chemical processes, through which the mineral ores are piled into the form of a heap, and a leach solution is spread over the ore surface to leach metal from the heap. Estimated water requirements for gold heap leach operations by donald i. Its seven representatives included three staff members from. Catherine reichardt school of mining engineering, university of the witwatersrand, private bag 3, wits 2050. Heap leaching and the water environment does low cost recovery come at a high environmental cost. Leaching process was first observed in pumps and pipelines installed in mine pits containing acid water. In response to claims that acid insitu leaching isl mining of uranium in south australia and. Heap leaching is often carried out at high altitudes, or at extremely arid or wet sites. Heap leaching mining techniques, metals mining, copper. Uram conference, vienna 2014 uranium heap leaching. Phosphate fertilizers as a proliferationrelevant source. Crushed ore agglomeration and its control for heap leach.
Improvements in copper heap leaching by use of wetting agents. Heap leaching accomplishes thisbut only with the containment support of geosynthetics. The formation of an ore heap, the heap leach ore and obtention of the product this process uses a membrane to place upon it certain amounts of mineral, in order to add chemical solutions. Heap leaching is a process whereby precious metals such as gold and silver are extracted from rock by placing mineralized material on a lined pad a base in a heap and irrigating with a leaching solvent, such. This solution, now enriched with gold, drains off the bottom of the pad into what is known as the pregnant pond, from which it is pumped to the recovery plant. Estimated water requirements for gold heapleach operations by donald i. Applications shlomo orr and velimir vesselinov abstract in our 1st article orr, 2000, we investigated different flow and transport phenomena that could significantly reduce leaching recovery. Dump leaching is an industrial process to extract precious metals and copper from ores dump leaching is similar to heap leaching, however in the case of dump leaching ore is taken directly from the mine and stacked on the leach pad without crushing where, in the case of gold and silver, the dump is irrigated with a dilute cyanide solution that percolates through the ore to dissolve gold and. Instability of the ore either static, seismic, or during extreme rainfall can lead to loss of the facility, failure of the liner system, and loss of environmental containment maximum overall slope for. Evolution of structural and physical properties of uranium ore agglomerates during heap leaching has been. Catherine reichardt school of mining engineering, university of.
920 783 145 1647 1588 717 1266 1286 1174 987 82 1129 1278 599 717 552 73 294 643 1203 1240 38 1493 469 1320 1447 1453 770 237 1251 83 486 1366 527 327 16 356 303 300 994