This white paper summarizes the state of art of insitu leaching of metals and minerals, and describes a new technology concept employing improved fragmentation of ores underground in order to prepare the ore for more efficient insitu leaching, combined with technology to continuously improve solution flow patterns through the ore during the leaching process. Heap and in situ leaching the minerals business unit has extensive expertise and experience in the field of uranium heap and in situ leaching isl. The uranium recovery using this technology is claimed to be as high as in acid. This in situ leaching project operated for 7 years and closed down in 1982 ogorman et al. In situ recovery, an alternative to conventional methods of. Insitu leaching gains importance for the exploitation of low grade ore deposits, for. The leaching liquid used for in situ leaching contains the leaching agent ammonium carbonate for example, or particularly in europe sulfuric acid. The process requires that holes be drilled into the site where the deposit is located with the aim of creating portals through which certain liquid can be poured down to the deposit by the created portal. While some units are being leached, others are being prepared for production. In situ, or inplace leaching is concerned with the extraction of metals from natural mineral disseminations without removal from their geologic location which, in many cases, amounts to the reversal of the deposition process accompanied by a presumed increase in velocity of the processes, if the project is to be profitable. Ground water modeling studies at in situ leaching facilities and evaluation of doses and risks to offsite receptors from contaminated ground water revision 2 contract number epd10042 work assignment 206, task 2 prepared by. Copper leaching throughout the world copper leaching plants have been widely used for many years. Sulfide leaching is a more complex process because of the refractory nature of the sulphide minerals. Uranium ore is extracted from opencast mines, underground mines and by in situ leaching.
Ammonium carbonate can also be used to yield uranium trioxide, uo 3, or uranyl tricarbonate, u o 2 c o 3 3 4 in situ leaching also known as in situ recovery involves dissolving the ore with an oxidant such as hydrogen peroxide while it is still in the ground and fixing the uraniumcontaining minerals with a complexing agent either acidic or alkaline depending on the mineral content of. The disadvantages of leaching are lower recovery and greater difficulty in controlling the cyanidation process. We designed a series of laboratory experiments, monitored the temporal evolution of solution compositions, and analyzed the experimental results through process based numerical modeling. Pdf modeling process of insitu leaching of various.
In situ recovery isr, also known as in situ leaching isl, use solu tions that are pumped through the mineralized body in situ under ground to recover metals by leaching. A process is described for maintaining a relatively high and constant concentration in the leachate of an in situ leaching operation as the mineral value in the formation is depleted, and without reducing the daily production, by adjusting the pumping rate of lixiviant proportionally to the depletion of the mineral value. Its application to amenable uranium deposits in certain sedimentary formations has been growing in view of its competitive production costs and low surface impacts. First used in wyoming in the 1950s, insitu leaching isl mining accounts for most uranium production in the united states. In situ leach or leaching isl or in situ recovery isr mining has become one of the standard uranium production methods. Leaching is the process of a solute becoming detached or extracted from its carrier substance by way of a solvent leaching is a naturally occurring process which scientists have adapted for a variety of applications with a variety of methods. Leaching is the loss or extraction of certain materials from a carrier into a liquid usually, but not always a solvent. Leachate solutions vary according to the ore deposit, from freshwater for salt deposits to acid solutions for copper and acid or sodium bicarbonate leachates. It is operated as simple heap leaching process or combination of both heap leaching and in situ leaching process. In response to claims that acid insitu leaching isl mining of uranium in south. The lixiviant is then pumped into the deposit, making contact with the ore, and the resulting solution is then collected and processed. However the flow capacity of injection wells is generally. Isr trials were carried out at several sites near mount isa, queensland in the1970sogormanet al. In situ leach works by artificially dissolving minerals occurring naturally in a solid state.
Dakota is in situ leach mining of uranium, the process has been used elsewhere to mine other. Adsorption is a term used to describe the attraction of a mineral. Manual of acid in situ leach uranium mining technology. In situ leach isl mining is defined as, the extraction of uranium from the host. Heap leaching is an industrial mining process to extract precious metals, copper, uranium, and other compounds from ore via a series of chemical. Leaching solution is pumped into the deposit where it makes contact with the ore.
Flow sheet for in situ leaching of uranium from water saturated, permeable sandstone deposits. It involves pumping chemicals into the ground to dissolve the uranium mineral in situ and then pumping these uraniumladen solutions back to the surface for extraction and processing of. Pdf in present work modeling of mineral extraction by the insitu leaching isl method is considered. To provide a stable rate of uranium production, the isl wellfield units should be placed in production in a systematic order.
This is usually done near the mines at facilities referred to as uranium mills prior to transport to fuel manufacturing. Stationary solid beds leaching equipments movingbed leaching dispersedsolid. Simulating in situ leaching process using comsol multiphysics. Shanks process other tanks in the battery are kept in. The method of recovery of gold from the process slurry is by carbon adsorption. Although this definition can include the use of explosives or hydraulic. Process for the insitu leaching of uranium from a subterranean ore deposit employing a lixiviant containing a carbonate leaching agent and an oxidizing agent. Holes are drilled into the deposit, in order to make pathways for the solution to penetrate. The optimized leaching conditions are usually a concentration of lixiviant of 0. Insitu leaching is a process that is utilized in mining for the recovery of certain stated types of minerals that include uranium, gold and copper. Medcram medical lectures explained clearly recommended for you. This process initially involves drilling of holes into the ore deposit.
The soluble u complexes are transported by groundwater flow to the extraction wells where they are pumped to the surface and are recovered in. Dilute sulphuric acid ph 2 is percolated down through the pile. We designed a series of laboratory experiments, monitored the temporal evolution of solution compositions, and analyzed the experimental results through processbased numerical modeling. Microbial leaching bioleaching, biomining environmental. Feasibility of electrokinetic in situ leaching of gold. This article provides a numerical simulation of the insitu leaching isl uranium. Gold and silver leaching practices in the united states. In addition, in situ leaching of uranium is more sensitive to good engineering management and attention to detail. In situ leaching isl, also called in situ 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. Solidliquid extraction leaching course outcomes co apply principles of leaching. In situ leaching isl involves the application of a specific lixiviant to dissolve en. Pdf study of uranium extraction process by the insitu leaching. All of the materials used in heap leaching process and industry specifications of materials are.
Dilute acidic solutions are introduced to the copperbearing ores, causing dissolution of soluble copper minerals table 1 remaining in the leached cap and underlying enrichment blanket. The ore from mining is processed into a refined form of u 3 o 8 known as yellowcake or uoc uranium ore concentrate. The lixiviant is heated to a temperature of at least 110 f. Specific extraction methods depend on the soluble characteristics relative to the sorbent material such as concentration, distribution, nature, and size. Pdf simulating insitu leaching process using comsol. Heap and insitu leaching the minerals business unit has extensive expertise and experience in the field of uranium heap and insitu leaching isl. Isl involves injecting chemicals, called lixivants into an aquifer that contains a uranium ore body i. In the case of insitu leaching isl also called insitu recovery isr, or solution mining the uraniumbearing ore is not removed from its geological deposit, but a leaching liquid is injected through wells into the ore deposit, and the uraniumbearing liquid is pumped to the surface from other wells. In situ recovery, an alternative to conventional methods. It involves pumping chemicals into the ground to dissolve the uranium mineral in situ and then pumping these uraniumladen solutions back to the surface for extraction and processing of the uranium into yellowcake for export.
In situ leaching is a more environmentally friendly method than traditional methods of mining gold. In situ leach mining rules question and answer sheet. However, only the cyanidation process is used industrially in hydrometallurgical processes. The leaching of precious metals like gold and silver can be done very easily with cyanide or ozone under ambient conditions. Pdf study of insitu leaching of metals by numerical simulation. 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. Review of environmental impacts of the acid insitu leach. The insitu leaching project at san manuel was initially designed to utilize gravity flow leaching to recover oxidised copper from partially rubblized and supergene mineralized rock that was spatially situated adjacent to an abandoned portion of the block cave underground mine. Investigation of in situ leach isl mining of uranium in new mexico. This method can only be applied if the uranium deposit is located in porous rock, confined in impermeable rock layers. The application of air flow provides the required oxygen to increase sulphide copper oxidation and to improve the activity of leaching microorganisms lorca, 2004.
The main objective of this study was to clarify the inprinciple feasibility of electrokinetic in situ leaching of gold from finegrained porous media. Again a very ore body specific issue, this has been one of the big issue in enhanced oil recovery processes which some have complained are doing significant environmental damage. It is recognized as having economic and environmental advantages when properly employed by knowledgeable specialists to extract uranium from suitable sandstone type deposits. After the leaching process is complete, the soluble gold must be concentrated and separated from the process slurry.
In situ leaching or solution mining is a process of recovering minerals such as copper and uranium through boreholes drilled into the formation, without the need for conventional mining. Although some species may be more of an environmental concern than others, the leaching process is indiscriminant such that all constituents e. This in situ leaching project operated for 7 years and. Pdf modeling process of insitu leaching of various regimes. In this process carbon is added directly to the leach circuit so that the leaching and adsorption processes proceed simultaneously.
The present invention provides an improved process for the insitu recovery of mineral values, particularly uranium, from subterranean deposits that exhibit heterogeneous permeabilities in the formation zones. Aqueous solutions of thickening agents or viscosity building agents are utilized to control the mobility of the leaching solutions as they traverse the subterranean formation to. A suitable deposit is one where the commodity is located in saturated permeable horizons or distinctive geological areas that are bounded above and below by impermeable strata. The recovery of mineral and metal values by solution mining has been practiced for. In situ leaching is a process that is utilized in mining for the recovery of certain stated types of minerals that include uranium, gold and copper. In the 1970s and early 1980s an in situ leaching project was carried out to extract copper from oxide ores at miami, arizona. To prepare for the possibility of in situ leach mining operations moving into the. In situ leach uranium mining iaea scientific and technical. In situ leaching isl, also known as in situ recovery, is a low capitalcost method of extracting uranium, copper or potash from suitable deposits. The cil process the carboninleach cil process, illustrated in figure 3 is a variation of the cip process. Pdf the article is devoted to numerical modeling of uranium insitu leaching process, which enables to assess the dynamics of the technological. Sep 22, 2004 this white paper summarizes the state of art of in situ leaching of metals and minerals, and describes a new technology concept employing improved fragmentation of ores underground in order to prepare the ore for more efficient in situ leaching, combined with technology to continuously improve solution flow patterns through the ore during the leaching process. Insitu leaching is a process in which there is a dissolution of the useful component by the chemical reagent in the place of ore body stratification followed by the removal of the formed compounds from the reaction zone by the moving stream of solvent. This publication describes how experience with isl can be used.
In situ leach mining rules question and answer sheet why are the new in situ leach mining rules drafted. The facilities within the minerals business unit include over 30 temperature controlled 2 m vertical columns, each capable of holding 35 kg of ore and 8 temperature controlled 4 m vertical columns. The main objective of this study was to clarify the in principle feasibility of electrokinetic in situ leaching of gold from finegrained porous media. Sep 21, 1982 a process is described for maintaining a relatively high and constant concentration in the leachate of an in situ leaching operation as the mineral value in the formation is depleted, and without reducing the daily production, by adjusting the pumping rate of lixiviant proportionally to the depletion of the mineral value. Leaching is the process by which constituents of a solid material are released into a contacting water phase. Pdf study of uranium extraction process by the insitu. Capital cost is reduced, as only one set of agitators for both leaching and. To prepare for the possibility of in situ leach mining operations moving into the state, the 2006 legislature passed senate bill 62. In clause the technological model insitu leaching uranium deposits are stated, settlement data for forecasting and are obtained managements of process leaching. The use of a heated lixiviant provides for a substantially greater ultimate uranium recovery than that attained through.
The process design of gold leaching and carboninpulp. There are three types of leaching systemsheap, dump, and in situ. Explosives or hydraulic fracturing are used to create open pathways within the deposit for solution to penetrate into. In situ leaching isl, also known as solution mining, or in situ recovery isr in north america. Its application to amenable uranium deposits in certain sedimentary formations has been growing in view of its competitive production costs. During the construction of this insitu leaching system, an. Manual of acid in situ leach uranium mining technology publications.
If ore is mined or if it is gathered from old nine wasterock piles and hauled to specially prepared pads lined with clay, tar, or alon for. Modeling process of insitu leaching of various regimes. In situ leaching is a process in which there is a dissolution of the useful component by the chemical reagent in the place of ore body stratification followed by the removal of the formed compounds from the reaction zone by the moving stream of solvent. Leaching agriculture, the loss of watersoluble plant nutrients from the soil. Leaching in metallurgy and metal recovery emew blog. In situ leach wikipedia 2019928 in situ leaching isl, also called in situ recovery isr or solution mining, is a mining process used to recover minerals tel. However, it does provide insights into many of the considerations. 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. 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. Enough naoh must be present as neutralizer to maintain alkaline conditions at a constant ph of 11. A method for leaching or dissolving gold from ores or.
1149 35 1292 167 171 1370 827 1422 445 580 1102 588 1120 952 905 341 168 1368 927 1315 1341 816 266 168 553 621 90 152 968 172 1379 658 565 778 1489 76 618 648