Heap leaching is a process through which metals are extracted from the ore in which they are found. Heap leaching targets nickel from laterite by paul grad march 1, 2017 the niwest nickel laterite project located at murrin murrin in the north eastern goldfields of western australia, has the potential to become a significant longterm, lowcost nickel producer through the development of heap leaching. Comparison of conventional mill, heap leach, and in. 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. Radioactive waste from uranium mining and milling us epa. The agglomeration process represents a way used by nickel, copper and uranium industries to enhance acid heap leaching of low grade ores containing large amount of fines and clays dhawan et al.
A brief note on the heap leaching technologies for the recovery of. Feeco is a preferred partner for the heap leaching process because of our vast experience in the agglomeration field for over 65 years. The following table compares the features of the three main types of facilities, which include conventional. However, uranium leaching from ore on a large scale is widely practiced in the usa. Feeco can supply a complete package consisting of a rotary ore agglomerator, and the necessary material handling equipment to feed the agglomerator, as well as carry material to the heap leach pads feeco is a preferred partner for the heap leaching process because of our vast experience in the agglomeration field for over 65 years. In 2012, the percentage of the mined uranium produced by heap leaching. Not unlike insitu leach mining, heap leach mining is a process whereby uranium, copper and other precious metals are extracted from ore with a chemical solution. In order to better understand the heap leaching process of uranium ore agglomerates, a multiscale approach, based on 10cm and meterscale columns, was.
Heap leaching mining techniques, metals mining, copper. The remaining solution is filtered and the uranium is recovered in some form of ion exchange ix or solvent extraction sx system. Leaching parameters are taken from the standard protocol designed by areva and values are representative of actual process conditions for acid heap leaching petersen, 2016. Heap leaching is an industrial process for extracting precious metals and minerals by dissolving them from ore with liquids known as leaching solutions. Apr 25, 2018 heap leaching is used to extract gold, copper, silver, uranium, and iodine. Generally heap leaching process is employed in copper leaching process but sometimes a combination of heap leaching and in situ leaching processes are used. Copper heap leaching solvent extractionelectrowinning sxew in 2014, more than 50 major hlsxew operations worldwide recovered approx. Similar to in situ mining, heap leach mining differs in that it.
It is controlled by surface etching, diffusion, and mass transfer within the ore. Uranium mining, processing, and reclamation uranium mining. The use of ion exchange recovery in the copper industry is not widesprea d. A study of uraniumore agglomeration parameters and their. Similar to the way pouring hot water over crushed coffee beans leaves coffee grounds waste and liquid coffee, spraying chemicals over piles of uranium containing crushed rock leaves the leftover rock and a liquid containing uranium. Cyanide solutions are a solvent for the precious metals, while a sodium chloride solution dissolves some chlorides. In either the acid or alkali leaching method the fortified groundwater is pumped into the aquifer via a series of injection wells where it slowly migrates through the aquifer leaching the uranium bearing host sand on its way to strategically placed extraction wells where submersible pumps pump the liquid to the surface for processing. The process is commonly used to extract metals such as gold, copper, and uranium yellowcake in addition to several other minerals.
In situ uranium leaching is gaining vast acceptance. Uram conference, vienna 2014 uranium heap leaching. As the precursor to the nuclear fuel cycle, uranium recovery focuses on extracting or mining natural uranium ore from the earth and concentrating or milling that ore. The leaching liquid often sulfuric acid is introduced on the top of the pile and percolates down until it reaches a liner below the pile, where it is caught.
The crushed ore is placed on a leaching pad with a liner. Comparative cost and energy analyses for each of four methods for leaching uranium ore are described. The uranium is then stripped from this and precipitated see box. The report describes information obtained from a literature search and site visits related to heapleaching practices for lowgrade uranium ore. Due to the scale effect between the columns and a 6 m high heap, 10 days of leaching under laboratory conditions correspond to a leaching liquidsolid ratio of 11 equates. The solution sulphatefe 3 solution is sprinkled over the heap which percolates through the ore and collects at the bottom pit. Etango uranium project heap leach demonstration program. Uranium leaching uranium leaching is more important than copper, although less amount of uranium is obtained than copper. Testing confirms the simple chemistry and efficient leaching nature of the granite host rock and uranium mineralisation.
The choice between an acid leaching process or alkaline leaching process is dependent on the ore and gangue and the uranium mineralogy. In situ leaching isl, solution mining, or in situ recovery isr involves dissolving uranium in the ground and pumping the solution to the surface where the minerals can be recovered. After completion of the leaching process, a longterm problem may result from naturally induced leaching, if the ore contains the mineral pyrite fes 2, as with the uranium deposits in thuringia, germany, for example. Prior to the leaching process, the ore is often given preliminary treatments that can include roasting and grinding. The process has been performed successfully to obtain gold, copper and uranium.
During leaching, the piles present a hazard because of release of dust, radon gas and leaching liquid. Heap leach is limited to ores with low clay content, and the process requires. Introduction, methods, application, copper, microorganisms, and processes. 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. Similar to the way pouring hot water over crushed coffee beans leaves coffee grounds waste and liquid coffee, spraying chemicals over piles of uraniumcontaining crushed rock leaves the leftover rock and a liquid containing uranium. Heap leaching is used to extract gold, copper, silver, uranium, and iodine.
This phase is generally controlled by the chemical reactions involving the ore minerals and sulphuric acid. In some cases uranium has been removed from lowgrade ore by heap leaching. After completion of the leaching process, a longterm problem may result from naturally induced leaching, if the ore contains the mineral pyrite fes 2, as with the uranium deposits in. Heap leaching mining techniques, metals mining, copper mining. In situ leach mining of uranium world nuclear association. Mar 31, 2015 comparison of conventional mill, heap leach, and in situ recovery facilities through the years, the u. During the first phase of leaching first 5 to 10 days, the accessible, soluble uranium minerals are solubilized by dilute sulphuric acid. Our rotary agglomeration drums are durable, built for longevity, and trusted by companies around the globe. Figure 8 is a schematic plan of the operating procedure. For getting one tonne of uranium, a thousand tonne of uranium ore must be handled. Uranium leaching with sulphuric acid is a complex process governed by chemical dissolution, and the oxidation of uranium. Heap leaching is usually carried out in the open and on slightly sloping ground covered with a watertight. This process was later on employed for recovering metals from ores containing low quantity of the metal. The leaching process may be conceptually divided into four basic phases.
The process is particularly effective for ores that have a tangible clay component i. This method was first employed to extract copper at the bluebird mine in the us in the early 1960s, and then by several gold mines in the western parts of the us a few years later. Heap leaching provides mining operators with a benign. The final chemical precipitate is filtered and dried. Similar to in situ mining, heap leach mining differs in that it places ore on a liner, then adds the. The milling process commonly yields dry powderform material consisting of natural uranium, yellowcake, which is sold on the uranium market as u 3 o 8. Aug 20, 2015 copper heap leaching solvent extractionelectrowinning sxew in 2014, more than 50 major hlsxew operations worldwide recovered approx. All of the materials used in heap leaching process and industry specifications of materials are. Another process in which copper and uranium are recovered is via a process called insitu leaching. Upon completion of the 200gallonsperton 840 lt leach and the 100gallonperton.
For uranium ore deposits, the choice of mining methods and processing options is very depositspecific and dependent on many variables such as the quality and quantity of the ore, the shape and depth of the ore deposit, site. Oct 02, 2017 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 absorb specific minerals and then re. As the need for resources increase, the heap leaching industry has risen to the occasion with advancements creating an even more efficient leach. Heap leaching is often chosen for its efficiency and costeffectiveness. Ammonium hydroxide is used for native ores, carbonates, and sulfides, and sodium hydroxide is used for oxides. Information from the world nuclear association, the global privatesector organization that provides information on nuclear power, nuclear energy, and the role of nuclear in sustainable development. Pdf heap leaching technologycurrent state, innovations. May 06, 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 hl is a process to extract lowgrade minerals from ore, including copper, precious metals, nickel and uranium. 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. Heap leaching is bat for suitable ores because it allows the economical processing of ore that would otherwise be uneconomic under con ditions that can technically achieve regulatory acceptable levels of environmental risk mitigation.
This may be done if the uranium contents is too low for the ore to be economically processed in a uranium mill. Recovery of uranium by heap leaching is less common, with acid heap leaching used in hungary neaiaea, 2000 and and alkaline heap leaching process used in namibia schnell, 2010. Another method of uranium extraction is heap leaching. Hydrodynamic performance critical for heap leach to. Since then, heap leaching has been adopted successfully by many mines across the world. Heap leaching, a process used to extract copper, uranium, and some precious metals from their ores. Comparison of conventional mill, heap leach, and in situ. Modern heap leaching started with uranium as the target metal, and made its way eventually to copper, but it was with gold extraction that the. An integrated multiscale approach to heap leaching of uraniumore. In effect, 23 of the heap production was to be processed for uranium recovery with the lowgrade wash liquor on recycle. Us6312500b1 heap leaching of nickel containing ore. Heap leaching is an industrial mining method to dig out precious metals and copper compounds from ore. Heap leaching is generally economically feasible only for oxide ore deposits.
Heap leaching today is applied to crushed ores, and modern heaps are designed to prevent ground contamination using a minimum of double containment, groundwater. Similar to in situ mining, heap leach mining differs in that it places ore on a. This is an early turning point in the microbiological leaching of uranium ores. Further enhancing project knowledge designed, permitted, constructed and successfully commissioned large scale demonstration plant. May 29, 2011 bioheap leaching is used commercially and is based on natural bacterias ability to leach metals from sulphide minerals. Comparison of conventional mill, heap leach, and in situ recovery facilities through the years, the u. These general terms incorporate a large variety of design possibilitiesthere are as many methods of mining uranium as there are orebody sizes, shapes, and mineral constituents. After completion of the leaching process within months to years, the leached ore is either.
Heap leaching is an extraction process by which chemicals usually sulfuric acid are used to extract the economic element from ore which has been mined and placed in piles on the surface. The use of an agitated leaching process is the most common type of uranium processing, and is the one most likely to be applied to deposits in virginia. Pdf conventional heap leaching of uranium ore is neither a new concept historically in the united states, nor is the idea unfamiliar on a. Pdf conventional heap leaching of uranium ore in the western. In some cases, uranium is extracted from lowgrade ore by heap leaching. Uranium leaching is the process by which the uranium is extracted from the raw ore by reacting the material with acid or base. Bioheap leaching is used commercially and is based on natural bacterias ability to leach metals from sulphide minerals.
A short description of the in situ leachingin situ recovery islisr uranium. The solution collecting in the bottom pit will include. The uranium ore was st acked in heaps, similar to dump leaching of. T his chapter outlines the basic steps involved in mining, processing, and reclamation that might be suitable for uranium ore deposits in the commonwealth of virginia. These recovery operations produce a product, called yellowcake, which is then transported to a fuel cycle facility. The present invention relates to a new process of heap leaching and comprises the following steps. Uranium ores are normally processed by grinding the ore materials to a uniform particle size and then treating the ore to extract the uranium by chemical leaching. Heap leaching is an industrial mining process used to extract precious metals, copper, uranium, and other compounds from ore using.
Table of contentspilot test programfullscale pilot heap operationmaybell heap leach experience union carbide began looking seriously at heap leaching in 1971 at that time some 1. Heap leaching is an industrial mining process to extract precious metals, copper, uranium, and other compounds from ore via a series of chemical. Heap leaching is the most common method used in the u. Based on the current understanding of uranium deposits in the commonwealth of virginia, extraction of uranium ore would use openpit mining, or underground mining, or a combination of both. An integrated multiscale approach to heap leaching of uranium. Ore is mined, crushed and dumped onto a leaching pad made from impermeable membrane with a minimum thickness of 1. Microbial leaching bioleaching, biomining environmental. Heap leaching is an extraction process from ore which has been mined and placed in piles on the surface. The process includes sizing the ore where necessary, forming pellets by contacting ore with a lixiviant and agglomerating. For uranium ore deposits, the choice of mining methods and processing options is. This industrial technology consists in increasing ore particle size distribution by gathering fines to improve the heap permeability and stability and also prevent fine particle. A process is provided for heap leaching ore to recover nickel. In order to better understand the heap leaching process of uranium ore agglomerates, a multiscale approach, based on 10cm and meterscale columns, was used to achieve a representative elementary. For many decades, there has been a growing demand for heap leaching due to its environmental benefits.
The pregnant liquor from isl or heap leaching is treated similarly. Heap leaching is a lowcost technology used in industrial mining to recover precious metals such as gold and uranium, along with several other highly sought after metals like copper, from their primary resources ores and minerals. Heap leaching is based on the use of a series of chemical reactions that absorb specific minerals and reseparate them after their division from other earth materials. As the need for resources increase, the heap leaching industry has risen to the occasion with advancements creating an. Leaching process was first observed in pumps and pipelines installed in mine pits containing acid water. Uram conference, vienna 2014 uranium heap leaching 22 the plan 1. Heap leaching last updated december 23, 2019 gold heap leaching. Uranium mining, processing, and reclamation uranium mining in. Uranium mining, processing, and reclamation uranium. When processing copper through heap leaching, vast quantities of ore and overburden overburdensoil and rocks that have been moved out of the way to get to ore are called overburden. Nuclear regulatory commission nrc has licensed numerous uranium recovery facilities in the united states, which used a variety of extraction methods to glean uranium from ore.