CN113151700B - High-heap leaching method for uranium ore - Google Patents
High-heap leaching method for uranium ore Download PDFInfo
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B60/00—Obtaining metals of atomic number 87 or higher, i.e. radioactive metals
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- C22B60/0217—Obtaining thorium, uranium, or other actinides obtaining uranium by wet processes
- C22B60/0221—Obtaining thorium, uranium, or other actinides obtaining uranium by wet processes by leaching
- C22B60/0226—Obtaining thorium, uranium, or other actinides obtaining uranium by wet processes by leaching using acidic solutions or liquors
- C22B60/0234—Obtaining thorium, uranium, or other actinides obtaining uranium by wet processes by leaching using acidic solutions or liquors sulfurated ion as active agent
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- C22B3/00—Extraction of metal compounds from ores or concentrates by wet processes
- C22B3/04—Extraction of metal compounds from ores or concentrates by wet processes by leaching
- C22B3/06—Extraction of metal compounds from ores or concentrates by wet processes by leaching in inorganic acid solutions, e.g. with acids generated in situ; in inorganic salt solutions other than ammonium salt solutions
- C22B3/08—Sulfuric acid, other sulfurated acids or salts thereof
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- C22B60/00—Obtaining metals of atomic number 87 or higher, i.e. radioactive metals
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Abstract
The invention is suitable for the technical field of uranium ore metallurgy, and provides a high-heap leaching method for uranium ore, which comprises the following steps: carrying out high-pressure roller milling treatment on the uranium ore until the particle size is not larger thanGreater than 8 mm; adding concentrated sulfuric acid and a water solution containing a cementing agent into crushed uranium ore, mixing, stacking, performing series-stacking spray leaching on cured cemented ore particles by using a spray liquid, wherein the spray liquid is prepared by adding ferrous sulfate into a sulfuric acid solution, returning residual liquid obtained by performing ion exchange treatment on a leaching solution into the spray liquid, and the spray strength is 10-20l/h/m2And when the detected uranium concentration of the leachate is lower than 50mg/L, adding an oxidant into the spraying liquid. According to the invention, a cementation granulation method is combined with acid mixing curing and high-acid spraying to improve the leaching rate, adverse factors such as poor permeability caused by pile height and poor ore mineralization and permeability are overcome, and the leaching rate of uranium in lake and mountain uranium ores reaches more than 80% under the condition of pile height of 9m, so that the method is obviously superior to the existing heap leaching technology.
Description
Technical Field
The invention belongs to the technical field of uranium ore metallurgy, and particularly relates to a high-heap leaching method for uranium ore.
Background
The uranium ore hydrometallurgy technology mainly comprises conventional stirring leaching, underground leaching and heap leaching (referred to as "heap leaching"). Compared with the conventional agitation leaching, the heap leaching has the defects of low resource recovery rate and poor adaptability, but also has the advantages of low capital investment, low production cost, low energy consumption and the like. The uranium ore resource deposit in China has the characteristics of small scale, dispersed ore body, low grade and the like, and is very suitable for the development of heap leaching technology, so most uranium ore enterprises adopt the heap leaching hydrometallurgy process to recover low-grade uranium ore, and the mature development of the heap leaching technology in China is further promoted. According to different uranium deposit conditions and ore properties, the hydrometallurgy technology of dump leaching uranium ores begins to be researched in China since the 80 th century. Through the development of the last forty years, various heap leaching technologies in China realize the industrial application. The method comprises a fine-grained heap leaching technology, a concentrated acid curing-high-speed rail leaching heap leaching technology, a bacterial oxidation leaching heap leaching technology, a percolation heap leaching technology and the like, and the resource recovery rate is only 2% -6% lower than that of conventional agitation leaching, so that the maximum utilization of uranium resources is realized.
Lake mountain uranium ore is one of the few large uranium ores found in the world, the total resource amount is nearly 30 ten thousand tons, and the low-grade uranium ore accounts for about 1/3 and is the second uranium ore in the world. In order to realize the maximum utilization of resources, a heap leaching practicability exploration test is carried out on low-grade ores of lake and mountain uranium ores in the early stage, and the result shows that the leaching rate of uranium is only about 65%, and is far lower than that of a conventional stirring leaching technology by about 90%. Meanwhile, due to the large heap leaching scale of lake mountain uranium ores, the problem of ore segregation, channeling, surface structure and the like during leaching is caused by the high heap body, and the heap leaching efficiency is further reduced.
Therefore, the problems that the leaching rate of uranium is low, the heap leaching efficiency is low, and the uranium resource of lake mountain uranium ore cannot be fully recovered exist in the existing heap leaching technology.
Disclosure of Invention
The embodiment of the invention aims to provide a high heap leaching method for uranium ore, and aims to solve the problems that the leaching rate and the heap leaching efficiency of uranium are low, and uranium resources of lake mountain uranium ore cannot be fully recovered in the existing heap leaching technology.
The embodiment of the invention is realized in such a way that a high-heap leaching method for uranium ores comprises the following steps:
carrying out high-pressure roller grinding treatment on the uranium ore to obtain uranium ore crushed stone with the granularity not greater than 8 mm;
adding concentrated sulfuric acid and a water solution containing a cementing agent into the uranium ore crushed stones, uniformly mixing, and then performing stacking treatment to obtain a cemented ore particle stacking pile with the stacking height of 4-12 m;
performing series-pile spraying leaching on the cured cemented ore particle piles by using a spraying liquid, wherein the spraying liquid is prepared by adding ferrous sulfate into a sulfuric acid solution, a residual liquid obtained after ion exchange treatment of the obtained leaching liquid is returned to the spraying liquid, and the spraying strength is 10-20l/h/m2And when the uranium concentration of the leachate is detected to be lower than 50mg/L, adding an oxidant into the spraying liquid.
According to the uranium ore high-heap leaching method provided by the embodiment of the invention, high-pressure roller milling is carried out on uranium ore to a certain particle size, then acid-mixing cementing granulation treatment is carried out on the uranium ore to obtain a cemented ore particle heap with the heap height of 4-9 m, and high-acid serial heap spray leaching is carried out under a certain spray strength after curing treatment; the method overcomes the problem of poor permeability caused by stack height by using a cementing granulation method, improves the leaching rate by combining acid mixing curing and high acid spraying, overcomes the disadvantages of poor ore mineralization and permeability and the like, inhibits the generation of leaching solution precipitate, successfully realizes that the leaching rate of uranium from lake and mountain reaches more than 80 percent under the condition of stack height of 9m, and is obviously superior to the prior stack leaching technology.
Drawings
FIG. 1 is a flow chart of a uranium ore high heap leaching process provided by an embodiment of the invention;
FIG. 2 is a graph showing the variation of the leaching solution concentration with the extension of the leaching time for each column in different spraying strength influence tests provided by the embodiment of the present invention;
FIG. 3 is a liquid meter leaching rate change curve diagram of uranium corresponding to each column along with the extension of leaching time in different spraying strength influence tests provided by the embodiment of the invention;
FIG. 4 is a graph showing the variation of leachate concentration with increasing leaching time for each column in different heap height effect tests provided by embodiments of the present invention;
FIG. 5 is a liquid meter leaching rate change curve diagram of uranium corresponding to each column along with the extension of leaching time in different stack height influence tests provided by the embodiment of the invention;
FIG. 6 is a graph showing the variation of the leaching solution concentration with the extension of the leaching time for each column in the test of the influence of different acid-mixing granulation conditions provided by the embodiment of the present invention;
FIG. 7 is a graph showing the change of the leaching rate of uranium by liquid meter according to the increase of leaching time of each column in the experiment for influencing the conditions of preparing grains with different mixed acids according to the embodiment of the invention;
FIG. 8 is a graph showing the variation of the leaching solution concentration with the extension of the leaching time for each column in different initial spraying acidity influence tests provided by the embodiment of the present invention;
fig. 9 is a graph showing the variation of leaching rate of liquid meter of uranium according to the prolongation of leaching time of each column in different initial spray acidity influence tests provided by the embodiment of the invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
The ores of lake mountain uranium ores are mainly alaskite type uranium ores, the embedding granularity of the uranium ores is small, the uranium ores need to be crushed to be smaller in granularity for heap leaching, and high-heap leaching is not beneficial. Due to the particularity of uranium ore leaching, a high heap leach level will result in a leach solution with reduced acidity, resulting in-heap precipitation and plugging. However, in view of the scale of lake mountain uranium ores, the design height of a heap leaching bench test reaches more than 6m, it is imperative to adopt a higher heap height for heap leaching, and no precedent exists in the world uranium ore hydrometallurgy history, and how to solve the influence of the heap height is the key for the successful application of the heap leaching technology in the lake mountain uranium ores.
The embodiment of the invention provides a high-heap leaching method for uranium ore, aiming at solving the problems that the leaching rate of uranium is low, the heap leaching efficiency is low, and the uranium resource of lake-mountain uranium ore cannot be fully recovered in the existing heap leaching technology, the uranium ore is subjected to high-pressure roller milling treatment to a certain particle size, then is subjected to acid-mixing cementing granulation treatment, so that a cemented ore particle building pile with the building pile height of 4-9 m can be obtained, and is subjected to high-acid serial-pile spray leaching under certain spray strength after curing treatment; the problem of poor permeability caused by pile height is solved by utilizing a cementing granulation method, the leaching rate is improved by combining acid mixing curing and high-acid spraying, the unfavorable factors such as poor mineralization and permeability of the ore are overcome, the generation of leaching solution precipitate is inhibited, the leaching rate of uranium in lake and mountain uranium ore reaches more than 80% under the condition of pile height of 9m, and the method is obviously superior to the existing heap leaching technology.
As shown in fig. 1, a high heap leaching method for uranium ore according to an embodiment of the present invention includes the following steps:
step S1: and carrying out high-pressure roller grinding treatment on the uranium ore to obtain uranium ore crushed stone with the granularity not greater than 8 mm.
In the embodiment of the invention, through research on a high-pressure roller milling treatment process, a common ore grinding process and the particle size of crushed uranium ore in the early test process, the leaching rate of uranium corresponding to the crushed uranium ore obtained through the high-pressure roller milling treatment is higher than that of the crushed uranium ore obtained through the common ore grinding treatment under the same crushed uranium ore particle size condition, and when the particle size of the crushed uranium ore is larger than 8mm, the leaching rate of uranium is obviously reduced, and the leaching rate of the uranium is higher as the particle size of the crushed uranium ore is smaller.
Step S2: adding concentrated sulfuric acid and a water solution containing a cementing agent into the uranium ore crushed stones, uniformly mixing, and then performing stacking treatment to obtain a cemented ore particle stack with the stacking height of 4-12 m.
In the embodiment of the invention, concentrated sulfuric acid and a water solution containing a binding agent are added into uranium ore crushed stones to carry out acid-mixing cementing granulation, the mass percent of water after granulation molding is required to be about 10%, and the water used in the embodiment of the invention is distilled water.
In the embodiment of the invention, the mass ratio of the uranium ore crushed stone, the concentrated sulfuric acid and the cementing agent is 1000 (15-34) to 0.075-0.15. The invention adopts concentrated acid to mix and cure and then dilute acid to leach out through an acid mixing curing technology, but the reaction of acid is incomplete due to too high acid mixing amount; too low a pH causes precipitation at too high a pH of the leachate. Proper amount of mixed acid and high acid are adopted for spraying to decompose the acid dosage of sulfuric acid in the processes of mixing acid and spraying, and granulation is matched to increase the permeability of ore heap, thereby achieving the purpose of improving leaching effect.
In the present example, the bond is polyacrylamide, it should be noted that other bonds having properties comparable to polyacrylamide may be used.
In the embodiment of the present invention, the mass fraction of the concentrated sulfuric acid is not less than 90%.
In the embodiment of the present invention, the pile height is preferably 9 m. The uranium ore heap leaching is easy to cause liquid accumulation due to small particle size and high spraying strength. In order to ensure that the solution flowing through the ore heap keeps a certain residual acid, the heap leaching height is limited, which greatly increases the area of the heap and the project investment for large-scale heap leaching. From the current world heap leaching production, the height of refined heap leaching is generally controlled below 6 m. In domestic uranium ore dump leaching production enterprises, the stack height is controlled to be 4-5 m. The research of the invention determines that the optimal heap height is 9m, the first application of large-scale heap leaching high-heap technology in the uranium ore industry is realized, and the heap height breakthrough of fine heap leaching of the uranium ore is innovatively realized.
In the embodiment of the present invention, the aging process is a natural infiltration process of acid to the ore, and the aging process is generally performed according to the convention, for example, the aging process may be performed for 1-8 days.
Step S3: performing series-pile spraying leaching on the cured cemented ore particle piles by using a spraying liquid, wherein the spraying liquid is prepared by adding ferrous sulfate into a sulfuric acid solution, a residual liquid obtained after ion exchange treatment of the obtained leaching liquid is returned to the spraying liquid, and the spraying strength is 10-20L/h/m2And when the uranium concentration of the leachate is detected to be lower than 50mg/L, adding an oxidant into the spraying liquid.
In the embodiment of the invention, the oxidant is one of hydrogen peroxide and sodium perchlorate. The invention discovers that different oxidants are obtained through earlier testsThe leaching rate of uranium is less influenced by type selection, the leaching effect is ideal, and H is preferably selected by comparison according to the influence of economy and chloride ions on the post-process of heap leaching2O2. Wherein H2O2The concentration of the uranium ore is 1-3 g/L, and the addition amount of the uranium ore is 0.5-3 kg/t. In addition, it should be noted that the oxidant cannot be added too early, otherwise, the reducing substances (such as sulfides and the like) in the ore consume a large amount of the oxidant, and experiments show that when the uranium concentration of the leaching solution is detected to be lower than 50mg/L, the oxidant is added into the spraying solution, so that the leaching rate of the uranium can be ensured, and meanwhile, the consumption of the oxidant can be greatly reduced.
In the embodiment of the invention, the concentration of the sulfuric acid solution is 15-100g/L and is used as the initial spraying acidity. Early tests show that the leaching rate of corresponding uranium is reduced along with the reduction of the initial spraying acidity.
In the embodiment of the invention, early tests show that the spraying strength is 20l/h/m2When the leaching rate of uranium is within the range, the leaching rate of uranium is increased along with the increase of the spraying strength, and when the spraying strength is more than 20l/h/m2In time, liquid accumulation is generated, and spraying needs to be stopped.
In the embodiment of the invention, the spraying time mainly depends on the leaching rate, and generally, the longer the spraying time is, the higher the leaching rate is; however, the spraying period is too long and is not suitable for rapidly recycling resources, so that the spraying period is generally 30-50 days, preferably 40 days, and the time is too long and is not economical. The spraying can be finished when the uranium concentration of the tail liquid is detected to be lower than 10 mg/L.
In the embodiment of the invention, the initially prepared spray liquid is prepared by adding ferrous sulfate into a sulfuric acid solution, the concentration of iron ions is kept to be not less than 3g/L, and Fe is introduced in the primary spraying process2+Acting as a catalyst, Fe2+Reacting with oxidant to produce Fe3+And further Fe3+Reacting with uranium to produce easily soluble hexavalent uranium and Fe2+The leaching rate of uranium can be improved by circulating the steps; generally, only when the concentration of iron ions in the spray liquid is lower than 3g/L, ferrous sulfate is added into the spray liquid; in addition, the uranium ore containsIron ions, therefore, only a proper amount of iron ions are usually introduced into the initial spraying liquid, and after the leachate returns to the spraying liquid, the concentration of the iron ions in the subsequent spraying liquid can be generally kept to be not less than 3g/L, so that additional iron ions do not need to be supplemented.
In the embodiment of the present invention, the ion exchange treatment means can be implemented by referring to the prior art.
It is worth noting that the method combines the characteristics of the lake-mountain uranium ore and the technologies of acid mixing curing, granulation, high-acid spraying and the like on the basis of the acid mixing curing technology, is one-time extension and improvement of the acid mixing curing technology, and has very important significance for promoting the application of low-grade heap leaching industrial production. In addition, the breakthrough of heap leaching height is beneficial to greatly reducing the area of a storage yard, which has a very positive effect on large-scale heap leaching.
Examples of certain embodiments of the invention are given below, which are not intended to limit the scope of the invention. Unless otherwise indicated, the starting materials used in the examples of the present invention are either commercially available or prepared by conventional methods.
Examples
In this embodiment, the high heap leaching method for uranium ore includes:
carrying out high-pressure roller milling treatment on low-grade ores of lake mountain uranium ores until the granularity is less than or equal to 8 mm; adding 90% by mass of concentrated sulfuric acid and a polyacrylamide-containing aqueous solution into the uranium ore crushed stone, and uniformly mixing to obtain cementing ore particles for heaping, wherein the mass ratio of the uranium ore crushed stone to the concentrated sulfuric acid to the cementing agent is 799-837: 20:0.125, and the mass percentage of water after pelletizing and forming is controlled to be 8.75% -9.76%; stacking the cemented ore particles to obtain 6-column cemented ore particle stacks with stacking height of 9m (corresponding to 1-6 in table 1-2); performing series-pile spraying leaching on each column cemented ore particle pile after curing treatment for 1-8 days by using a spraying liquid, wherein the initial spraying liquid is prepared by adding ferrous sulfate into a sulfuric acid solution, the concentration of the sulfuric acid solution is kept at 100g/L, the concentration of iron ions is kept at 3g/L, and a residual liquid obtained after ion exchange treatment of the obtained leaching liquid is returned to the spraying leaching liquidIn the liquid, the spraying strength is 20l/h/m2And when the uranium concentration of the leachate is detected to be lower than 50mg/L, adding hydrogen peroxide with the concentration of 3g/L into the spraying liquid, wherein the adding amount of each column is 0.87-2.76 kg/t uranium ore, and the spraying leaching time of each column in series is 22-46 days.
The acid-mixing granulation conditions and test results for each column of cemented ore granulate pile are reported in tables 1-2:
TABLE 1 granulation conditions of the acid mixture
| Column number | 1-1 | 1-2 | 1-3 | 1-4 | 1-5 | 1-6 |
| Dry weight of ore (kg) | 837 | 836 | 824 | 799 | 826 | 825 |
| Wet weight (kg) after acid mixing | 927 | 926 | 903 | 881 | 913 | 812 |
| Moisture (%) | 9.76 | 8.81 | 8.75 | 9.27 | 9.60 | 9.48 |
| Acid mixing amount (kg/t) | 20.00 | 20.00 | 20.00 | 20.00 | 20.00 | 20.00 |
| Cementing dose (g/t) | 125 | 125 | 125 | 125 | 125 | 125 |
| Raw ore grade (ppm) | 220 | 186 | 227 | 220 | 223 | 215 |
| U3O8(g) | 184.125 | 155.406 | 186.986 | 175.761 | 174.151 | 177.448 |
| Pile height (m) | 9 | 9 | 9 | 9 | 9 | 9 |
| Bulk specific gravity (t/m)3) | 1.52 | 1.51 | 1.49 | 1.45 | 1.50 | 1.50 |
| Maturation time (d) | 3 | 6 | 8 | 6 | 2 | 1 |
TABLE 2
In summary, as can be seen from table 1, the uranium ore high heap leaching method provided in the embodiment of the present invention overcomes the problem of poor permeability caused by heap height by using a cementation granulation method, improves the leaching rate by combining acid mixing and curing and high acid spraying, overcomes adverse factors such as poor mineralization and permeability of the ore itself, and inhibits the generation of leachate precipitates, and a column circulation test determines that the leaching rate of uranium in lake and mountain uranium ore can reach more than 80% under the condition of heap height of 9m, which is significantly superior to the existing heap leaching technology.
The method comprises the following steps of strengthening and optimizing heap leaching process conditions aiming at the properties of lake mountain uranium ore ores in the early stage small batch test process so as to determine relevant researches on a high heap leaching process and process parameters for treating the lake mountain low-grade ores, specifically, an oxidant selection test and a high pressure roller grinding and common ore grinding comparison test are respectively carried out by adopting an indoor column leaching test, and different spraying strength influence tests, different heap height influence tests, different acid mixing granulation condition influence tests and different initial spraying acidity influence tests are respectively carried out by adopting a column string test.
(1) Oxidant selection test
Weighing a certain amount of lake mountain low-grade ore, grinding the lake mountain low-grade ore to 355 mu m, adding the lake mountain low-grade ore into a beaker, and controlling the solid-to-liquid ratio to be 1: 1. adding sulfuric acid into a beaker to maintain the pH at about 1.5, adding ferrous sulfate to maintain the concentration of ferric ions at 3g/L, and adding certain amount of H2O2、MnO2And NaClO3And keeping the oxidation-reduction potential at about 500mV, and inspecting the leaching rate of uranium after leaching for 24 hours at normal temperature. Specific test conditions and test results are shown in table 3.
TABLE 3
In conclusion, as can be seen from table 3, the leaching rates of different oxidant selections are less affected, the average leaching rate of the sample in the zone 1 is more than 81%, the average leaching rate of the sample in the zone 2 is more than 85%, the grade of the leaching residue is lower than 50ppm, and the leaching effect is ideal. H is selected by comparison and considering the influence of economy and chloride ions on the post-heap leaching process2O2And MnO2The next stage experiment was performed as an alternative oxidant. However, MnO2Comparative tests were only performed at the time of agitation leaching, which was found later to be unsuitable for heap leaching.
It should be noted that in this test, the amount of the oxidant added, especially pyrolusite, is significantly increased compared with the test of the research stage of the lake and mountain project. Analysis of the experimental procedure suggests that the oxidant cannot be added too early, otherwise the reducing species (such as sulfides, etc.) in the ore would consume the oxidant in large quantities. After analysis, the oxidizing agent was added after 2 hours after the addition of sulfuric acid in the subsequent test, in order to optimize the amount of the oxidizing agent added.
(2) High pressure roller mill and ordinary ore grinding contrast test
Weighing a certain amount of lake and mountain low-grade ore, grinding the lake and mountain low-grade ore to different granularities respectively, adding the lake and mountain low-grade ore into a beaker, and controlling the solid-to-liquid ratio to be 1: 1. adding sulfuric acid into a beaker to maintain the pH at about 1.5, adding ferrous sulfate to maintain the iron ion concentration at 3g/L, and then adding H2O2The oxidation-reduction potential is kept at about 500 mV. And (4) inspecting the leaching rate of uranium after 7 days of leaching at normal temperature. Specific test conditions and test results are shown in tables 4 to 6.
TABLE 4
TABLE 5
TABLE 6
In summary, as can be seen from tables 4 to 6, under the same uranium ore crushed stone particle size condition, the leaching rate of uranium corresponding to the uranium ore crushed stone obtained through high-pressure roller milling treatment is higher than that of the uranium ore crushed stone obtained through ordinary ore milling treatment, and when the particle size of the uranium ore crushed stone is larger than 8mm, the leaching rate of uranium corresponding to the uranium ore crushed stone is obviously reduced, and as the particle size of the uranium ore crushed stone becomes smaller, the leaching rate of uranium is higher.
(3) Different spray intensity impact test
Carrying out high-pressure roller milling treatment on low-grade ores of lake mountain uranium ores until the granularity is 8 mm; adding 20kg of 90 mass percent concentrated sulfuric acid and a water solution containing 125g of polyacrylamide into the obtained 1t uranium ore crushed stone, uniformly mixing to obtain cemented ore particles for building piles, and controlling the mass percent of water after granulation and forming to be about 10%; the cemented ore grains are piled up for 9m and then leached by sulfuric acid solution, and the spraying strength is respectively 10, 17, 20, 40, 60 and 80l/h/m2. Ferrous sulfate was added to maintain the iron ion concentration at 3g/L, and then H was added2O2The oxidation-reduction potential is kept at about 500 mV. And stopping spraying when the uranium concentration of the leachate is lower than 10mg/L, and testing the concentration of the leachate and the leaching rate of uranium corresponding to each column along with the prolonging of the leaching time, as shown in figures 2-3. Specific test conditions and test results are shown in table 7.
TABLE 7
In summary, it can be seen from Table 7 that the spray intensity was 20l/h/m2When the leaching rate of uranium is within the range, the leaching rate of uranium is increased along with the increase of the spraying strength, and when the spraying strength is more than 20l/h/m2In time, liquid accumulation is generated, and spraying needs to be stopped. In addition, as can be seen from the combination of FIGS. 2 to 3, the spraying strength is 10 to 20l/h/m2The corresponding column reactor is corresponding to the leaching liquid with the regular decline of the concentration along with the prolonging of the time, and the leaching rate of the uranium reaches 20l/h/m when the spraying intensity reaches2And the leaching time can reach more than 80 percent in a shorter leaching time.
(4) Different stack height impact test
Carrying out high-pressure roller milling treatment on low-grade ores of lake mountain uranium ores until the granularity is 8 mm; adding 20kg of 90 mass percent concentrated sulfuric acid and 75g of polyacrylamide-containing aqueous solution into the obtained 1t uranium ore crushed stone, uniformly mixing to obtain cemented ore particles for building piles, and controlling the mass percent of water after granulation and forming to be about 10%; the cemented ore grains are respectively piled up for 4m, 5m and 9m and then leached out by sulfuric acid solution with the spraying strength of 20l/h/m2. Ferrous sulfate was added to maintain the iron ion concentration at 3g/L, and then H was added2O2The oxidation-reduction potential is kept at about 500 mV. And stopping spraying when the uranium concentration of the leachate is lower than 10mg/L, and testing the concentration of the leachate and the leaching rate of uranium corresponding to each column along with the prolonging of the leaching time, as shown in fig. 4-5. Specific test conditions and test results are shown in table 8.
TABLE 8
In summary, as can be seen from table 8, when the stacking height is within 9m, the leaching rates of uranium are equivalent to each other with the increase of the stacking height, and all of the leaching rates are more than 80%; in particular, as can be seen from fig. 4 to 5, the leaching solution concentration of the corresponding column pile is regularly decreased with the time increase when the pile height is within 9m, and the leaching rate of uranium on a liquid basis can be 80% or more at a leaching time of 25 days when the pile height reaches 4.13m, and can be 80% or more at a leaching time of 34 days when the pile height reaches 9 m.
(5) Test for influence of different acid-mixed granulation conditions
Carrying out high-pressure roller milling treatment on low-grade ores of lake mountain uranium ores until the granularity is 8 mm; respectively adding a certain amount of concentrated sulfuric acid with the mass fraction of 90% and a certain amount of aqueous solution containing polyacrylamide into the obtained 1t uranium ore crushed stone, uniformly mixing to obtain cemented ore granules for building piles, and controlling the mass percentage of water after granulation and forming to be about 10%; the cemented ore grains are piled up for 9m and then leached by sulfuric acid solution, and the spraying strength is 20l/h/m2. Ferrous sulfate was added to maintain the iron ion concentration at 3g/L, and then H was added2O2The oxidation-reduction potential is kept at about 500 mV. And stopping spraying when the uranium concentration of the leachate is lower than 10 mg/L.
Specifically, preliminary tests on the acid-mixing granulation conditions were performed in the early stage of the present invention, and the specific test conditions and test results are shown in table 9. The results show that: the leaching test is carried out by adopting the acid mixing amount of 30.7kg/t, and the leaching rate is only more than 50 percent in the time of about 20 days. And when the spraying strength is increased, the leaching rate tends to be obviously increased. Therefore, tests of the influence of different acid mixing amounts on the leaching rate are further increased, and the test results show that when the acid mixing amount is 13-28kg/t, the leaching rate tends to increase along with the reduction of the acid mixing amount, but when the acid mixing amount is lower than 16kg/t, the leaching rate gradually decreases. Therefore, by combining the test results and the actual situation that the average acid consumption of the ore is 25.8kg/t, 15kg/t and 20kg/t are selected as the optimal acid mixing amount to carry out further tests, and the specific test conditions and the test results are shown in Table 10; and the leaching concentration of the leaching solution and the leaching rate of uranium corresponding to the extension of the leaching time of each column were tested, and the results are shown in fig. 6 to 7.
TABLE 9
In conclusion, as can be seen from Table 10, when the acid content is 15kg/t, the leaching rate reaches 81.51% after 49 days of leaching; when the acid mixing amount is 20kg/t, the leaching rate reaches 82.08 percent after 34 days of leaching; therefore, 20kg/t is selected as the optimal acid mixing amount of the heap leaching ore.
(6) Test of influence of different initial spray acidity
Carrying out high-pressure roller milling treatment on low-grade ores of lake mountain uranium ores until the granularity is 8 mm; respectively adding 20kg of 90 mass percent concentrated sulfuric acid and 125g of polyacrylamide-containing aqueous solution into the obtained 1t uranium ore crushed stone, uniformly mixing to obtain cemented ore granules for building piles, and controlling the mass percent of water after granulation and forming to be about 10%; the cemented ore grains are piled up for 9m and then leached by sulfuric acid solution, and the spraying strength is 20l/h/m2. Ferrous sulfate was added to maintain the iron ion concentration at 3g/L, and then H was added2O2The oxidation-reduction potential is kept at about 500 mV. And stopping spraying when the uranium concentration of the leaching solution is lower than 10mg/L, and testing the leaching solution concentration and the leaching rate of uranium corresponding to each column along with the extension of the leaching time, as shown in figures 8-9. Specific test conditions and test results are shown in table 11.
TABLE 11
In summary, as can be seen from Table 11 and FIGS. 8 to 9, when the initial spray acidity is 15 to 100g/L, the leaching rate tends to gradually increase with the increase in the storage time spray acidity, and particularly, 82.08% is reached when the initial spray acidity is 100 g/L. In addition, considering that the ore heap permeability is poor due to the fact that the tail liquid residual acid is too low, 100g/L is selected as the initial spraying acidity.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the present invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.
Claims (8)
1. A high heap leaching method for uranium ore is characterized by comprising the following steps:
carrying out high-pressure roller grinding treatment on the uranium ore to obtain uranium ore crushed stone with the granularity not greater than 8 mm;
adding concentrated sulfuric acid and a water solution containing a cementing agent into the uranium ore crushed stones, uniformly mixing, and then performing stacking treatment to obtain a cemented ore particle stacking pile with the stacking height of 4-12 m; the mass ratio of the uranium ore crushed stone to the concentrated sulfuric acid to the cementing agent is 1000 (15-34) to 0.075-0.15;
performing series-pile spraying leaching on the cured cemented ore particle piles by using a spraying liquid, wherein the spraying liquid is prepared by adding ferrous sulfate into a sulfuric acid solution, a residual liquid obtained after ion exchange treatment of the obtained leaching liquid is returned to the spraying liquid, and the spraying strength is 10-20l/h/m2When the detected uranium concentration of the leaching solution is lowAdding an oxidant into the spray liquid at 50 mg/L; the oxidant is one of hydrogen peroxide and sodium perchlorate.
2. The uranium ore high heap leaching method according to claim 1, wherein the heap height is 9 m.
3. The uranium ore high heap leaching method according to claim 1, wherein the oxidant is hydrogen peroxide; the concentration of the hydrogen peroxide is 1-3 g/L, and the addition amount of the hydrogen peroxide is 0.5-3 kg/t uranium ore.
4. The high heap leaching process of uranium ore according to claim 1, wherein the consolidating agent is polyacrylamide.
5. The uranium ore high heap leaching method according to claim 1, wherein the mass fraction of the concentrated sulfuric acid is not less than 90%.
6. The high heap leaching method for uranium ores according to claim 1, wherein the concentration of sulfuric acid solution in the spray liquid is 15-100g/L, and the concentration of iron ions is not less than 3 g/L.
7. The uranium ore high heap leaching process according to claim 1, wherein the ripening process is for a period of 1 to 8 days.
8. The high heap leaching method for uranium ores according to claim 1, wherein the time for the series heap spray leaching is 30-50 days.
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