Uranium mining is the process of extraction of uranium ore from the ground. Pdf extraction of uranium from heap leaching solutions. Pdf heap leaching technologycurrent state, innovations. 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. Similarly, leaching is also a major natural process that occurs at depths. Uranium ore leaching pregnant leach liquor ion exchange solvent extraction precipitation. Acid leaching has been used in the uranium milling industry since the midforties and has accounted for a majority of the production since that time. An integrated multiscale approach to heap leaching of. Wmc copper uranium division copper ore heap leaching. The leaching kinetics were determined for various leaching conditions and the activation energy was found to be 45. The goal of the present study was to compare uranium recovery by bioleaching and acid leaching in identical columns under similar process conditions for the same material. 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. Leaching behaviour and the solution consumption of uranium. Heap leaching is an industrial mining process to extract precious metals, copper, uranium, and other compounds from ore via a series of chemical.
Pdf conventional heap leaching of uranium ore is neither a new concept historically in the united states, nor is the idea unfamiliar on a. The recovery of metals and other processes are conducted just like in slope leaching fig. This phase is generally controlled by the chemical reactions involving the ore minerals and sulphuric acid. Etango uranium project heap leach demonstration program. Although usually acidic mine waters were used for ore processing,4 billion liters of freshwater. Heap leaching and its application to copper, uranium. Heap leaching of gold ore started to gain promenence in the late 1960s when it was. It is preferred over carbonate leaching because of its greater efficiency in recovering uranium. Prior to the injection of the lixiviant, an aqueous solution of sulfuric acid and oxidizing agent is injected into the deposit in an amount of at least 1 pore volume. Leaching is a process of extracting a substance from a solid material that is dissolved in a liquid. The major uranium mineral is pitchblende which can be easily leached by acid with o 2. Application of united nations framework classification 2009 unfc2009 for uranium resources uranium ore processing i. The initially injected acid solution is substantially free of. Depending on the presence of pyrite fes and acidicalkaline conditions, biological process of sulphur oxidation.
A pilot scale liquid surfactant membrane process, designed to purify and concentrate uranium from heap leaching solutions, has been developed. Kazakhstan, canada, and australia are the top three producers and together account for 70% of world uranium production. The bacterial strain that was used in the leaching experiments was isolated from the jaduguda mine water sample. 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 volume rev of packed agglomerates. Dilute sulphuric acid ph 2 is percolated down through the pile. The order of reaction with respect to uranium concentration was found to be unity. Testing confirms the simple chemistry and efficient leaching nature of the granite host rock and uranium mineralisation. The process includes sizing the ore where necessary, forming pellets by contacting ore with a lixiviant and agglomerating. Another critical factor was the supply of water for the leaching heaps. Radioactive metals, such as uranium are extracted by the process of acid leaching. All of the materials used in heap leaching process and industry specifications of materials are.
The uranium ore was st acked in heaps, similar to dump leaching of. Gavin mudd about the proposed heap leaching expansion of ranger uranium mine in kakadu national park. In addition, the whole leaching process of uranium sandstone can be divided into two phases taking the 60th hour as the demarcation point ie, about the 2. Etango uranium project heap leach demonstration program phase. Precious metals such as gold are extracted from their ores by a cyanide or ozone leaching process. Presentation by uranium energy corp on uranium recovery by heap leaching methods.
Microbial leaching bioleaching, biomining microbial leaching is the process by which metals are dissolved from ore bearing rocks using microorganisms. The uranium recovery is highly leached for introduction of bacterial leaching process at uranium leaching can enhance the kinetics of leaching and strengthen its process, bioleaching has been paid great attention in uranium industry in recent years. The worldwide production of uranium in 2015 amounted to 60,496 tonnes. Uranium deposit mineralogy and associated chemistry there are numerous types of uranium minerals in existence, the simplest form being uraninite. Biological and chemical leaching together biooxidation of pyrite for the production of ferric sulphuric acid generated in process split feed system bioleaching system pyrite leached in autoclave and uranium subjected to bacterial leach. During the first phase of leaching first 5 to 10 days, the accessible, soluble uranium minerals are solubilized by dilute sulphuric acid. 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. Bioleaching of lowgrade uranium ore using acidithiobacillus. A brief note on the heap leaching technologies for the recovery of. 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. The pellets are formed into a heap and leached with sulfuric acid to extract the.
Pdf heap leaching is a wellestablished extractive metallurgical technology enabling the economical. Process for the insitu leaching of uranium from a subterranean ore deposit employing a lixiviant containing an oxidizing agent, sulfuric acid, and carbon dioxide. The solution collecting in the bottom pit will include. Heap leaching is generally economically feasible only for oxide ore deposits. A comparison of the uranium recovery from lowgrade ore by.
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. Further enhancing project knowledge designed, permitted, constructed and successfully commissioned large scale demonstration plant. It is suggested that then heapleaching of ores, the. 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. Insitu leaching isl, also called insitu recovery isr or solution mining, is a mining process used to recover minerals such as copper and uranium through boreholes drilled into a deposit, in situ. Arizona volcanics carbonateacid process new mexico todilto formation carbonate process wyoming wind river formation acid process. Pdf conventional heap leaching of uranium ore in the western.
It is operated as simple heap leaching process or combination of both heap leaching and in situ leaching process. Heap leaching provides mining operators with a benign. The leaching process in mining is carried out either as heap leaching or insitu leaching. 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. Pdf heap leaching technologycurrent state, innovations, and. All of these disciplines have made steps forward in modeling the diffusion process and all have pertinent data for the mineral processing of copper heap leaching.
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. Mar 09, 2010 bioleaching of uranium was carried out with turamdih ore sample procured from uranium corporation of india limited, jaduguda. Microbial leaching bioleaching, biomining environmental. For many decades, there has been a growing demand for heap leaching due to its environmental benefits. 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. Agglomeration is generally carried out in a rotating drum. Therefore, high eh value is good benefit for oxidizing fourth valence uranium 15. This process is carried with an ore which remains in its original location in the earth. Pdf extraction of uranium from heap leaching solutions by. 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 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. Besides the technical feasibility of the heap leaching process in a particular context. This technique is used to process several ores such as uranium, copper or nickel laterites and is based on fluidrocks interactions at the heap scale and on the percolation of. Us4337979a process for the insitu leaching of uranium. The liquid coming out of the bottom of pile reach in. A process is provided for heap leaching ore to recover nickel.
The leaching agent not ailings, or waste generated from the milling process, are stored in specially designed waste losing ounts azards and characteristics of mill tailings c dissolve the only extracts uranium from the ore, but also several other constituents including molybdenum. The ore is arranged in a big heap, which is treated with water as in slope leaching. An integrated multiscale approach to heap leaching of uranium. The process is particularly effective for ores that have a tangible clay component i. Consequently much research has been done on the factors which influence the kinetics of the oxidation of uranium, as well as those which influence. 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. The leaching process may be conceptually divided into four basic phases. Pictorial representation of the isl process 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. In china, hardrocktype uranium such as granitetype deposits are using heap leaching widely in industry. Us6312500b1 heap leaching of nickel containing ore. During leaching, the piles present a hazard because of release of dust, radon gas and leaching liquid. Heap leaching is an industrial method to process low grade ores, consisting of percolating an acid or alkaline leaching solution through a 4 to 10 meter high heap of crushed ore ghorbani et al.
In india, uranium occurrences of almost all the above types are reported in different parts of the country. Copper heap leaching solvent extractionelectrowinning sxew in 2014, more than 50 major hlsxew operations worldwide recovered approx. Uranium leaching is the process by which the uranium is extracted from the raw ore by reacting the material with acid or base. In situ leach isl mining of uranium june 2009 z most uranium mining in the usa and kazakhstan is now by in situ leach methods, also known as in situ recovery isr. Currently several new projects are progressing to recover uranium from carbonate deposits sole et al. Is a technique used in the recovery of copper, salttrona and uranium ores in. 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. 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. Other important uranium producing countries in excess of 1,000 tons per year are niger, russia, namibia, uzbekistan, china, the. Prior to the leaching process, the ore is often given preliminary treatments that can include roasting and grinding. Uram conference, vienna 2014 uranium heap leaching 22 the plan 1. In situ leach works by artificially dissolving minerals occurring naturally in a solid state.
This is an early turning point in the microbiological leaching of uranium ores. 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. A study of uraniumore agglomeration parameters and their. Flow diagrams of heap leaching processes of gold, copper, and uranium adopted. For the last 10 centuries, microorganisms have assisted in the recovery of copper dissolved in drainage from water. Uranium recovery by heap leaching methods in arizona new mexico wyoming uranium energy corp 6100 indian school rd ne, suite 225 albuquerque, nm 87110. This process is commonly referred to as extraction, particularly in the chemical industry. Future uranium heap leach projects will benefit from the experience gained from copper and gold heap leaching, including strong acid cures, heap building techniques and operating strategies. For recovery of material occurring naturally in solution, see. The solution sulphatefe 3 solution is sprinkled over the heap which percolates through the ore and collects at the bottom pit. The influence of uranium mineralogy and the lithology and behaviour of the host rocks means of effecting capital and operating cost reductions, particularly for lower grade deposits flowsheet options for acid leaching and purification.
Overall, the process can be described as percolation. Aug 02, 2011 a video interview with monash universitys dr. It would also prevent a uniform flow of the solution through. Bioleaching of uranium was carried out with turamdih ore sample procured from uranium corporation of india limited, jaduguda. Flow rate and agglomerate size distribution were found to have no impact on the ore leaching kinetics. Heap leachionexchange operations involve the following process. Application of united nations framework classification. For oxide ores, recovery only slightly reduced with. A brief note on the heap leaching technologies for the.
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