From the new Canadian mines increased it again. In situ leach ISL, also called in situ recovery, ISR mining has been steadily increasing its share of the total, mainly due to Kazakhstan, and in accounted for over half of production:. The company continues to explore re-start options.
Deposit occurs as five discrete mineralised sand packages, located near the confluence of a major tributary entering the Yarramba paleochannel. More information regarding the mining operation, compliance reporting and approvals Back to top. Geological environments South Australia remains one of the most prospective regions in the world for uranium discovery.
Magmatic-related uranium mineral system - eg Crocker Well. Hybrid-uranium mineral system It is clear from the giant Olympic Dam deposit that the ca. Basin and surface-related uranium mineral system Sandstone-hosted The Gawler Craton and central Curnamona Province were eroded by widespread major river systems during the Cenozoic. Uranium has been deposited in reduced lithologies within these channel systems. At the Honeymoon deposit, the damming of the river systems and subsequent precipitation of uranium appears to be controlled by minor movements along small-scale faults within underlying basement.
Cenozoic paleochannnels have been explored and remain targets for uranium exploration - eg Kingoonya, Wynbring, Narlaby, Wanilla, Garford etc. Potential targets are at the base adjacent to graphitic schists within Paleoproterozoic metasediments or within this extensive, poorly explored basin adjacent to reduced lithologies. Ongoing investigations into the uranium potential of the Cariewerloo Basin are being undertaken by the Geological Survey of South Australia.
In the Crocker Well area, uranium primarily occurs as thorian-brannerite mineralisation as a disseminated accessory mineral or in fractures, breccias or quartz veins in sodic, plagioclase-rich granitoids and gneisses. Vast amounts of uranium also occur in the world's oceans, but in very low concentrations. Most of the uranium ore deposits at present supporting these mines have average grades in excess of 0. Other mines however can operate successfully with very low grade ores, down to about 0.
Some uranium is also recovered as a by-product with copper, as at Olympic Dam mine in Australia, or as by-product from the treatment of other ores, such as the gold-bearing ores of South Africa, or from phosphate deposits such as Morocco and Florida. In these cases the concentration of uranium may be as low as a tenth of that in orebodies mined primarily for their uranium content. An orebody is defined as a mineral deposit from which the mineral may be recovered at a cost that is economically viable given the current market conditions.
Where a deposit holds a significant concentration of two or more valuable minerals then the cost of recovering each individual mineral is reduced as certain mining and treatment requirements can be shared.
In this case, lower concentrations of uranium than usual can be recovered at a competitive cost. Generally speaking, uranium mining is no different from other kinds of mining unless the ore is very high grade. In this case special mining techniques such as dust suppression, and in extreme cases remote handling techniques, are employed to limit worker radiation exposure and to ensure the safety of the environment and general public.
Searching for uranium is in some ways easier than for other mineral resources because the radiation signature of uranium's decay products allows deposits to be identified and mapped from the air. Where orebodies lie close to the surface, they are usually accessed by open cut mining, involving a large pit and the removal of much overburden overlying rock as well as a lot of waste rock.
Where orebodies are deeper, underground mining is usually employed, involving construction of access shafts and tunnels but with less waste rock removed and less environmental impact. In either case, grade control is usually achieved by measuring radioactivity as a surrogate for uranium concentration. When the ore is processed, the U and the very much smaller masses of U and U are removed.
The controlling long-lived isotope then becomes Th which decays with a half-life of 77, years to radium followed by radon Supervising Scientist Group, Australia.
At McClean Lake and Ranger, mining will be completed underground. Some orebodies lie in groundwater in porous unconsolidated material such as gravel or sand and may be accessed simply by dissolving the uranium and pumping it out — this is in situ leach ISL mining also known in North America as in situ recovery - ISR. It can be applied where the orebody's aquifer is confined vertically and ideally horizontally.
Certainly it is not licensed where potable water supplies may be threatened. Where appropriate it is certainly the mining method with least environmental impact. ISL mining means that removal of the uranium minerals is accomplished without any major ground disturbance. Weakly acidified groundwater or alkaline groundwater where the ground contains a lot of limestone such as in the USA with a lot of oxygen in it is circulated through an enclosed underground aquifer which holds the uranium ore in loose sands.
The leaching solution dissolves the uranium before being pumped to the surface treatment plant where the uranium is recovered as a precipitate. Most US and Kazakh uranium production is by this method. In Australian ISL mines the oxidant used is hydrogen peroxide and the complexing agent sulfuric acid to give a uranyl sulphate.
Kazakh ISL mines generally do not employ an oxidant but use much higher acid concentrations in the circulating solutions. ISL mines in the USA use an alkali leach to give a uranyl carbonate due to the presence of significant quantities of acid-consuming minerals such as gypsum and limestone in the host aquifers.
Any more than a few percent carbonate minerals means that alkali leach must be used in preference to the more efficient acid leach, though the cost is often double. 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.
For very small orebodies which are amenable to ISL mining, a central process plant may be distant from them so a satellite plant will be set up. Hence very small deposits can become viable, since apart from the wellfield, little capital expenditure is required at the mine and remote IX site. Some ore, usually very low-grade below 0. Here the broken ore is stacked about 5 to 30 metres high on an impermeable pad and irrigated with acid or sometimes alkaline solution over many weeks.
The pregnant liquor from this is collected and treated to recover the uranium, as with ISL, usually using ion exchange. After the material ceases to yield significant further uranium, it is removed and replaced with fresh ore.
The depleted material has the potential to cause pollution so must be emplaced securely so as not to affect surface water or groundwater. Usually this will be in mined-out pits. Conventional mines have a mill where the ore is crushed and ground to liberate the mineral particles, then leached in tanks with sulfuric acid to dissolve the uranium oxides. The solution is then processed to recover the uranium.
With some South African uranium recovery from gold tailings, a pressure leach is necessary. Sometimes a physical beneficiation process is used to concentrate the ore and increase the head grade before chemical treatment.
Most of the ore is barren rock or other minerals which remain undissolved in the leaching process. These solids or 'tailings' are separated from the uranium-rich solution, usually by allowing them to settle out.
The remaining solution is filtered and the uranium is recovered in some form of ion exchange IX or solvent extraction SX system. The pregnant liquor from ISL or heap leaching is treated similarly. The mining method employed at Budenovskoye 2 is in-situ leaching ISL. The extracted uranium is treated at a processing facility on the site with the use of ion exchange technology.
Commercial production from the Karatau uranium mine started in January The proven and probable reserves at the mine as of December were estimated at It is also the eighth largest in the world, having produced 2,t of uranium in Uranium production at Kraznokamensk started in The ore body at Kraznokamensk is volcanic. Ore extracted from underground is processed at a hydrometallurgy plant and a heap leaching unit.
Langer Heinrich, Namibia Langer Heinrich uranium mine, located in the Namib Desert 40km south-east of the Rio Tinto-operated Rossing uranium mine, is the ninth largest uranium producing mine in the world.
The open-pit mine produced 1,t of uranium in The mine, owned and operated by Paladin Energy, started commercial production in March Annual uranium production of the mine was increased from 1,t to 1,t with completion of the stage-2 expansion project of the Langer Heinrich processing plant in The stage-3 expansion project, completed in , further raised the uranium production capacity to more than 2,t.
A Stage-4 expansion project has also been planned to increase uranium production capacity up to 3,t per year. The expansion, however, will not be implemented until the uranium price increases significantly.
The proven and probable reserves of Langer Heinrich including its stock piles were estimated at The minimum mine life at current rate of production is 20 years. South Inkai, Kazakhstan South Inkai uranium mine located about km north-west of Shymkent in the Chu-Sarysu basin in the Suzak region of South Kazakhstan province, Kazakhstan, is the tenth largest uranium producing mine in the world.
It produced 1,t of uranium in
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