DE1192633B - Process for leaching ores containing uranium - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY GERMAN WIW PATENT OFFICE

EDITORIAL

Int. CL:

COIg

German class: 12 η - 43/00

Number:
File number:
Registration date:
Display day:

1192633
C 20093IV a / 12 η
October 31, 1959
May 13, 1965

The invention relates to a method for leaching uranium-containing ores, namely such ores, their Uranium content is less than 1000 ppm, with the broken, coarsely crushed, arranged in a layer Starting material about 1 month to several years the attack of a diluted aqueous solution of an alkali carbonate or alkali bicarbonate is exposed.

In the known processes for leaching uranium-containing ores, in which alkaline leaching solutions are used, the ore is only relatively exposed to the leaching solution exposed to short periods of time.

If such a leach is carried out in a batch process, the inevitable result is, * 5 that the ratio of the amount of leaching reagent to the amount of ore is generally relatively large is; if the leaching is carried out as a continuous process, the exposure time is proportionate should be short and the leaching reagent is only passed through the bulk of the ore, one also chooses one for the - based on the unit of time - flow rate of the leaching agent relatively high value. In these procedures, which are different in themselves, the ore completely surrounded by the leaching agent, or the leaching agent flows or trickles through the Ore through.

In particular, they are generally used to extract uranium from uranium-containing slates Depending on the type of ore, acidic or alkaline solutions for leaching the finely crushed ore; for the z. B. uranium-containing shale existing in France, only alkaline leaching is economical, where alkali carbonate or bicarbonate solutions are used.

For the leaching, the ore or the shale mineral must be finely crushed; it's a special one To provide a system for leaching and the separation of the solid from the leaching liquid, in which one can separate the uranium-containing leach solutions from the leached rock; there must still be a dump to accommodate the unproductive or depleted material.

In addition, for reasons of economy, this known process can only be used to treat slate or ores whose uranium content is in the order of 1000 ppm. Under the most favorable conditions, the yields of such a leaching are hardly greater than 80%, even if very highly concentrated solutions, e.g. B. Na ₂ CO ₃ , can be used.

Process for leaching ores containing uranium

Applicant:

Commissariat a l'Energie Atomique, Paris

Representative:

Dipl.-Ing. R. Beetz, patent attorney,

Munich 22, Steinsdorfstr. 10

Named as inventor:

Pierre Mouret, Bourg-la-Reine, Seine;

Paul Pottier, Chatillon-sous-Bagneux, Seine;

Jean Le Bris, Montrouge, Seine;

Alban Villa, Paris (France)

Claimed priority:
France of November 5, 1958 (778 390),
dated June 29, 1959 (798 809)

It has now been found that by changing the contact conditions between the solid mineral on the one hand and the alkaline leaching agent used in solution on the other hand, as well as by choosing one low concentration of the leaching solution is possible, with little financial outlay, even with obtain relatively poor ores leaching efficiencies or yields that are relatively high and quite are comparable to those yields obtained by the previously known processes of acidic or alkaline leaching can be obtained, and that a uranium-containing solution is obtained which is sufficiently rich and is also sufficiently pure to extract the uranium from it in an economical manner.

It was found that one can improve the efficiency of the leaching by increasing the contact time of the ore increased with the leaching agent flowing through this ore and a uranium-containing solution with a sufficiently high concentration of uranium, given the time for the leaching agent to pull through extends through the ore long enough.

For such leaching over a relatively long period of time, the known frequent leaching is generally suitable, how they z. B. is used for copper ores in warm zones, whereby the leaching time is several Can be months to several years and

509 569/224

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relatively highly diluted leaching solutions - in these leach ores with a uranium content smaller than

Cases usually acidic solutions - used 1000 ppm; this salary may only be

will. be a few hundred ppm.

The invention, which is based on the exploitation of the above.

Knowledge is based, allows it, in particular 5 solution without the formation of an actual flow economically a relatively high leaching favored the aeration of the ore. The procedures at

To achieve yield and a uranium-containing leaching which the ore is completely in the leaching liquid

to win solution, the uranium content of which is large enough, floats or is covered by it or with which

to process this solution in the usual way. a leaching liquid flowed through the ore

The new process for leaching uranium-containing ores, io, which the ore with a relatively strong flow through the name of those ores whose uranium content flows less, cannot have a simultaneous intimate effect of more than 1000 ppm, whereby the broken, coarse air and the leaching agent result,
The aeration of the mass of the ore can be a material about 1 month to several years Alkali bicarbonates exposed to liquid according to the invention is possible; if that is, is essentially characterized in that the layer of ore through which the air is supposed to sweep the leaching solution evenly onto the surface is too thick Ventilation, e.g. B. 0.5 and 51 per hour and square meter of the ore surface by placing chimneys made of porous surface in the ore mass with the proviso that the clay begins.

Amount of the leaching solution is such that after it has passed through the mass of the

The uranium-containing solution is collected and this without any substantial flow and without trickling ore

pulls through the ore. a known extraction process for recovery

The alkaline lukewarm to be added according to the invention is subjected to uranium; you can use the uranium either It is particularly advantageous to use it with ores, or to extract it with an organic solvent which in an acidic leaching process, because of their chemical composition, ion exchange resins for the same purpose or their acid-binding content.

The components have a high acid consumption. After the uranium has been extracted, the

condition. 30 uranium freed leaching solution for the purpose of renewed

To carry out the process, it is sufficient to use an atomizer or distribution device

general, when the ore is fed relatively coarsely crushed.

and there is no particular separation according to grain size according to this method according to the invention

he follows; the flow of the leach reagent through which the concentration of the alkaline leach solution in

Ore is said to be very slow and without substantial amounts of the order of a few grams of Na ₂ CO ₃ each

Flow, the following effects being liters, and those obtained by the slow leaching

enter: uranium leaching fluids have a very

a) The leaching liquid does not result in a different uranium content. You can do some fine particles entrained, which clog up milligrams of uranium per liter up to several hundred or contain 40 milligrams per liter to separate impermeable layers. The respective uranium lead can; So it is not necessary, the content changes according to the content of the ore, fine particles from the crushed ore to the possibilities of the leaching attack and the divorce; The ore can be used as the layer height of the ore that the leachant is used to it has penetrated from the crushing and crushing plant.

comes. 45 In contrast to the classic procedures,

b) By slow permeation or seepage where alkaline leaching liquids are used If one reaches one of the leaching liquid, the uranium becomes with a much larger one sufficiently long contact time between the solution selectivity pulled out, and the uranium-containing alkaline and the ore to facilitate the leaching out of the leaching liquid involved in this slow leaching process Obtaining uranium and a leaching liquid 50 is obtained is much purer, so that the bemit to obtain a sufficiently high uranium content. knew about further processing using

Each grain of the ore gradually gives its ion exchange resin to a draining alkali

Uranium to the leaching solution wetting it, and lischen solution leads easily for a new one

the alkaline solution accumulates on its way to leaching the ore which is reusable. The uranium

between the point of application and the point where it is discharged

step increasingly from the mass of the ore with the elution of the ion exchange resins

Uranium. can be on the order of 5 g each

By analyzing samples that you get from time to liter up to about 20 g per liter.

Time at different points of the mass of the ore. With this type of leaching it happens that at

can be seen, the efficiency of the 60 certain ores during a certain time, z. B.

Leaching or extraction in the individual areas for a few 10 hours, no uranium from the ore

track the ore mass. is dissolved and that the uranium then more or

The contact between the ore and the leach goes into solution less quickly, whereby the speed

liquid takes place according to the above-mentioned conditions of the solution of the uranium after a certain one has expired

slow leaching; the leaching agent 65 assumes an average value over time,

pulls or seeps through the mass of the ores that simply disintegrate

small ore without significant flow through it. when the leachant passes through, a good one

In this way one can observe in an economical way the dissolution of the uranium, whereby the leaching

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medium after its passage through the mass part of the crushing plant, saving one of the ore first, e.g. B. during a period of example container leaching plant, elimination of a facility wise 100 hours, one essentially constant for the separation of more or less deaf shows permanent uranium content and only then ores, elimination of the heaps on which otherwise mountains this uranium content decreases. 5 or poor ores are stored, as the ore deposit

You have to carry out the invention, which is subjected to the leaching, in the course of In accordance with the leaching process, the fact that the leaching process is gradually discharged to a dump, that a certain amount of the leaching liquid leached ores, still the other advantages that the The filter for the clarification of the leaching liquid was initially retained by the bulk of the ore (250 kg of crushed ore can initially save a few io and the dimensions of the plant, Contain percent moisture; they then hold 401 in which the ion exchange takes place, are reduced from the first 1001 of the abandoned leaching can, since the throughput of the uranium-containing liquid back) and accordingly the Zer liquid is only very low. dusting or the task of the leaching agent to the method according to the invention is as a result

Choose a start larger than for the subsequent 15 economically on the one hand because of the above Leaching process. The height of the ore layer, due to reasons, on the other hand, because one is following this procedure ores which the leaching liquid has to pass through will still be able to use ores which have hitherto been discarded Chosen sufficiently large, namely in the size had to be. For example, an ore deposit can be Order of several meters up to a height from which one used only the richest ore veins Too far more than 10 m for a uranium-containing 20 to be sent for processing, now in its entirety Process leaching liquid with the greatest possible content; the very high cost of separation of uranium received; if one can be known as the leaching or separation of the rich and poor ores Heap leaching directly on one lying in the open - saved.

carries out the ore embankment, one avoids all. The method according to the invention is in two cases

Borrowed difficulties that can be used with the production of a 25 with particular advantage: special leaching apparatus or installation. 1. To exploit deposits or deposits, are bound; after their leaching, the ore forms the total ore quantities of which are relatively small and

on the embankment a dump on which there is only leached material where the ores only have a content of. approximately

Material is located. . Have 1000 ppm uranium;

In the laboratory and in the smaller industrial 3 <> 2. in deposits with very large amounts of ore, but the uranium content can be lower than that of very different scale

Containers to hold the crushed ore work- 1000 ppm.

th; For example, the whole or at least a substantial part can be placed vertically

Using wooden barrels, one can cylindrical vertical part of the deposit can then be in place Use glass tubes in which the layer heights 35 are processed using the new method, of the ore through which the leaching liquid passes - The leaching of uranium-containing ores as they are just entering should, between a few centimeters up to 1 or was written, can basically be used for uranium ores 2 m. Finally, all kinds of metal can also be used; you can make them yourself at Erzen Use towers when the layer heights are turning where the uranium is leached out exceed several meters; with such 4 ° known methods with short or medium Lau experiments also up to layer heights of several periods and solvents or leaching agents 10 m walk. medium concentration has been very difficult so far.

The method according to the invention allows ins- The method according to the invention is above all off

special, economically poor ores interesting for economic reasons, because in his process, even those ores, the uranium content of which is 45 in the simplest form of application is below 1000 ppm and, for example, only drive in far away from traffic is a few 100 ppm. The uranium will carry out with effective deposits at which it is difficult degrees or leached yields that would make the ores a special consideration the very low uranium content of the ores used in the processing plant, are relatively cheap. The application of the invention 5 ° The comminution of the ores does not require adequate Leaching process is just for the special measures, the sifting of the crushed Processing of poor ores particularly economical; Ore on grain size does not need to be very precise, this shows a particular advantage of this new and the facilities for the leaching and the Procedure. Cleaning have small dimensions, also the consumption

It is absolutely desirable that the ore should only be roughly crushed in proportion to the energy required to carry out the process; the proportion of small compared to the consumption in the previously known fine particles (the diameter of which, for example, in conventional systems. You only need the energy, less than 1 mm) should remain very low so that these fine particles are not necessary for ore extraction in the mine there is little with the leaching agent and, moreover, only the low power that is dragged ^along and the gaps between 6o which clog with their larger ore grains for the operation of a small pump system, whereby the additional devices are required. The circulation of the leaching agent is disturbed or even documentation costs are relatively low if one could be broken by it. The effort involved in setting up the mine itself

If you disregard the leach immediately as a heap.

leaching is carried out on ore embankments to which the ⁶ 5 The plant for the extraction of the uranium has only one brings the ore extracted from the mine, achieves very small dimensions, it can moreover in one one besides the known advantages of the more or less easily movable and transport heap leaching, such as the elimination of a very considerable form, can be carried out so that

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if necessary, can be easily chopped up and down if she is attached to an arrangement of the ore refiner just described is to be used by another operating location. pouring allows a very good and even

After the extraction work is completed, the leaching liquid will be distributed over the entire Extraction plant dismantled or dismantled, one ore.

neutralizes the embankment of the leached ores, 5 in the ore embankment 11 inserted chimney poisoning or undesirable interference pipes 20 made of porous clay are for ventilation in the

to prevent the growth of plants in the area. Provided inside the embankment.

After a final inspection of the heaps, the leaching of the heaped up begins those channels are blocked from which the ores, as soon as a larger quantity of ore is extracted, contain ceranic deposits Leaching liquid flowed, then neutralized ίο smaller and roughly on the lower part of Aufman the alkalinity that is still contained in the fill area. Let it be exemplary is. first have 50,0001 ore in an appropriate manner

For a more detailed explanation of the invention, the bottom surface of the embankment can be arranged. Procedures will now be a few different through- Now the diluted ore will now be applied to this ore embankment This process is carried out using the scheme 15 sprayed leaching liquid. The ore mining can tables F i g. 1 to 4 of the drawing are described in more detail - the newly mined ore will be continued ben. These embodiments are intended only as further up the sloping surface of the Erzauf examples of the method according to the invention and the bed poured.

To carry out the method to be used in this way, gradually the entire floor devices get ranked. It shows 20 area covered and the ore embankment each up to

F i g. 1 a system in which the procedure is carried out according to the level as shown in FIG. 1 in

of the present invention is shown immediately at the final ore stage.

pit on an embankment of 500,000 tons of uranium-containing If you increase the height of the ore embankment,

Minerals can be carried out, one must also improve ventilation and one

F i g. 2 a column carrying the 25 greater number of chimneys 20 which use this

Ensure ventilation of the procedure on a laboratory scale.

equips and in which an alkaline leaching of under- At the foot of the lock 18 flows through the

different uranium ores is feasible, aerated ore slowly migrating leaching

F i g. 3 a leaching tower, the application liquid via a manifold 21, through the

of the process on a semi-industrial scale allows 30 the entire uranium-containing alkaline solution through

F i g. 4 shows a device that does not run in the open air, which is not detailed in the drawings preventive effects of rainfall on the drainage pipes shown. This uranium-alkaline Leaching of uranium ores, ζ. B. in a containing liquid is in the equalization tank 22 Appendix according to FIG. 2, compensated. initiated. The pump layer 23 then pumps the solution

There are only those parts 35 in a relatively small treatment plant 12, where the shown, the understanding of the present uranium-containing solution an extraction process under invention seem necessary. is thrown, in which either an organic solution

The representation of the F i g. 1 shows an ore mine 8, solvents or ion exchange resins are used, a crushing plant 9, a storage container 10 for the. The leaching-concentrated leaching liquid then freed from the uranium, an ore pouring liquid, is poured through line 24 by means of pump 26, device 11, on which the crushed ore is drawn off at regular intervals, and through line 25 again layered in the manner and the leaching through container 13 introduced, from which the pump 15 is performed. The ore is pushed back into the distribution system until it is still relatively liquid, and it is crushed in a coarse grain size. Furthermore, the FIG. 2 is a cylindrical column 27 FIG. 1 shows a small, following the overall system 45 made of glass, in which a leaching in the system 12 created, in which the uranium-containing leaching laboratory scale can be carried out. The height solution is dealt with. There is no special installation of this column is 60 cm, its internal diameter 14 cm. intended for further chemical treatment. Dilute alkaline leaching liquid, which contains 5 g of the concentrated leaching agent solution, which contains the Na ₂ CO ₃ per liter, is withdrawn via line 28, supply 10, is supplied to container 13 50 and drips in individual drops at the diluted with; 14 is a feed line for the point designated for this 29 on the distribution layer 30. The dilution required water. The diluted solution of the alkaline liquid then slowly pulls through the ore mass 31 with the aid of a pump 15 into the storage container 16, which ore mass 31 is firmly conveyed by the grid 32 and then held above in the form of a spray. The uranium-containing liquid is collected in the half of the ore embankment 11 from the distribution pipes 17 55 container 33, the volume of which is larger than fine sprayed over the entire ore. 51 is. The solution is made in proportions of 51

The base on which the ore embankment 11 is taken. If you analyze it for its uranium content, it has a sloping slope. You can do this and then run this solution through a series of, for example, a small valley and select the columns that contain the ion exchanger of a strongly basic ore heaped up with the help of a retaining wall or 60 type. The uranium-free liquid will hold dam 18 in place. If the soil is _{not already naturally impervious to liquids (5 g per liter) by adding Na 2} CO ₃ to the initial valley and is again permissible for leaching, it can be used, for example, from the ore.

dense that one injected calcium silicate into the soil. There were three different ones in this column

The subsequent action of an acid forms 65 ores leached.

silica gel, which makes the soil dense enough. In the first of these attempts a uranium shale was used

On the floor surface there is a drainage system 19 in front of Saint-Hippolyte with a uranium content of

seen, which consists of clay pipes laid in sand. 2015 ppm treated. The column 27 contained 10,681 g

this ore (dry weight), the largest grains of which were less than 6 mm in diameter. Half of the mass consisted of grains, the diameter of which was between 3 and 6 mm. The throughput the alkaline solution through the ore averaged 21 hours every 24 hours. The ones obtained in this experiment The results are summarized in the following table:

IO

uranium Liquid Sum of Attempt concentration lot yield duration the liquid Days milligram liter ° / o per liter 4th 1 238 5 13.3 2 384 5 4th 376 5 28.6 10 280 5 13th 173 5 14th 56 5 35.4 16 46 5 19th 49 5 21 35 5 22nd 27 5 39.0 25th 38 5 28 62 5 32 65 5 35 38 5 45.3 36 105 5 42 51 5 46 67.5 5 49 61.5 5 50.0 50 25.0 5 51 24.0 5 53 22.0 5 55 30.0 5 56 25.5 5 53.2 58 37 5 61 20th 5 63 68.5 5 65 19.2 5 69 38.5 5 74 33 5 85 91.5 5 112 57 5 65.85 126 160.0

uranium Liquid Sum of Attempt concentration lot yield duration the liquid milligram liter ° / o Days per liter 2 5 1 8th 2 8.4 3 5.4 2 10.6 4th 3.5 2 11.3 5 1.2 2 12.8 6th 2.4 2 14.0 9 2 2 16.9 13th 4.5 2 18.7 17th 2.4 5 21.8 18th 2.0 5 29.0 31 5

The consumption of Na ₂ CO ₃ is of the same order of magnitude as that of the ore of the previous one

ao attempt; the uranium concentration of the eluate was naturally much smaller, it was in the range of magnitude from 8 to 10 g per liter.

In the next experiment, an ore was treated that is not a slate ore and comes from Saint-Symphorien des

as Ruaux came; this ore contained calcium carbonate; a comparatively carried out acidic leaching showed a relatively high consumption of the leaching agent. A quantity of 10 kg of crushed ore was therefore treated as in the previous example with a dilute alkaline leaching solution containing 5 g of Na ₂ CO ₃ per liter. The mean amount of leach liquid throughput was about 11 per 24 hours. The dimensions of the column were again somewhat different than before: height 80 cm, diameter 100 mm; the rate at which the uranium is leached is shown in the following table:

uranium Fluid
quantity total
the
yield PH value
the uranium
hold Attempt
duration concentration
the liquid
speed solution milligram liter % Days per liter 5 26.6 8.39 ⁴⁵ ι 554 5 37.1 10.22 7th 240 5 42.30 10.35 10 126 5 48.4 10.1 14th 152 5 56 10.25 so 20 180

The amount of Na ₂ CO ₃ required is 5 kg per ton of ore, and the liquids that are obtained during the elution of the ion exchangers reach a uranium concentration of 15 g per liter. It was found that the low concentration of Na ₂ CO _{3 in} the leaching liquids is very advantageous for binding the uranium in the ion exchangers.

In the second attempt, a uranium slate from So Saint-Hippolyte with a uranium content of only 320 ppm treated. The dimensions of the column 27 were slightly different than in the first attempt (height 65 cm, Diameter 4.5 cm). The content of this column was 1 kg of ore (dry weight); the grain of the Ore was roughly the same as in the previous experiment. The results were as follows achieved.

Fig. 3 shows a tower with a clear square cross-section (total cross-sectional area 1.66 m ² ) and 9 m height. This tower held an amount of 22 tons of uranium shale, which contained 1200 ppm uranium and was coarsely crushed in the usual way. An alkaline leaching solution containing 5 g of Na ₂ CO ₃ per liter and the pH of which was about 10 was sprayed with the aid of distribution lines 29. The throughput of this liquid was 41 per hour. The alcalic liquid was distributed in the distribution layer 30 over the entire cross section of the tower. The moisture of the ore used was around 8%.

The total yield at the end of the 38th day was about 2.5%; the uranium concentration in the leaching fluid was about 300 to 350 mg per liter on the 38th day.

The uranium-containing liquid was collected at 33 a, via a pump 34 in two columns 35

509 569 / 224-

and 36 filled with anion exchange resins (organic resins of a strongly basic type). The liquid freed from uranium was conveyed further by the pump 37 and - after setting to a concentration of 5 g Na ₂ CO ₃ per liter - used again for leaching the ore. A third column 38 was eluted during the time that columns 35 and 36 were in use.

The F i g. 4 shows an arrangement with which one can control or regulate the amount of water flow through the line 39 used for the dissolution of the carbonate in a container 40, specifically as a function of the amount of rain 41 which immediately falls on an embankment of the which is indicated schematically in FIG Ore falls. 51 with the return line of lauryl is designated ¹ S-cleaning fluid, from which the uranium has been extracted. When it rains, the concentration of the conductive saline solution in the pipe 42, into which the rainwater collected by the funnel 43 runs, changes. The pipe 42 is fed in a constant stream ^ao via the feed line 44 with a saline solution, which is a 0.1 η solution and is supplied in a constantly constant amount. The concentration at the outlet 45 of the pipe 42 is variable, depending on the amount of rainwater flowing into the pipe, and the resulting changes in the electrical resistance of this salt solution make it possible to actuate the valve 47 via an intermediate auxiliary element 46 which also acts as a relay , which in turn controls the water supply via the line 39 into the vessel 40. The circuit of this arrangement works on a differential principle; two line probes 48 and 49 serve to measure the differences between the variable resistance of the saline solution flowing out of the tube 42 and a standard resistance of a 0.1 N NaCl solution which is located in the vessel 50. The actuation of the valve 47 now takes place in such a way as a function of the resistances that the water flow is set to a variable value which, taking into account the falling amount of rain, leads to a constant concentration of the salt in the leaching liquid; Rainfalls can therefore not affect the leaching process carried out outdoors.

Claims (2)

Patent claims: 1. Process for leaching ores containing uranium, namely those ores with less uranium content is than 1000 ppm, the crushed, coarsely comminuted starting material arranged in a layer about 1 month to several years the attack of a dilute aqueous solution of a Exposed to alkali carbonates or alkali bicarbonates, characterized in that that the leach solution is evenly applied to the surface of the stratified ore in an amount between about 0.5 and 51 per hour and square meter of the ore surface is applied with the Provided that the amount of leaching solution is such that it is without substantial Current and without trickling through the ore. 2. The method according to claim 1, characterized in that in the leaching one outdoors lying ore fill the amount of water used to dissolve the leaching reagent adjusted taking into account the amount of rainwater. Considered publications: U.S. Patent No. 2,841,468; V. Tafel, textbook for metallurgy, 2nd edition, Vol. 1, p. 509; U11 m a η η, Encyclopedia of Technical Chemistry, 3rd edition, Vol. 8, p. 275. 1 sheet of drawings 509 569/224 5. 65 © Bundesdruckerei Berlin