CN115180702A - Long-acting passive treatment method for acid uranium tailing seepage water - Google Patents
Long-acting passive treatment method for acid uranium tailing seepage water Download PDFInfo
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- CN115180702A CN115180702A CN202210816369.4A CN202210816369A CN115180702A CN 115180702 A CN115180702 A CN 115180702A CN 202210816369 A CN202210816369 A CN 202210816369A CN 115180702 A CN115180702 A CN 115180702A
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- 239000004576 sand Substances 0.000 claims description 3
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- JFALSRSLKYAFGM-UHFFFAOYSA-N uranium(0) Chemical compound [U] JFALSRSLKYAFGM-UHFFFAOYSA-N 0.000 abstract description 17
- 230000000694 effects Effects 0.000 abstract description 9
- 230000003472 neutralizing effect Effects 0.000 abstract description 9
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- 229910001385 heavy metal Inorganic materials 0.000 abstract description 7
- 230000007774 longterm Effects 0.000 abstract description 7
- 238000001556 precipitation Methods 0.000 abstract description 5
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- 238000002386 leaching Methods 0.000 abstract description 3
- 238000004065 wastewater treatment Methods 0.000 abstract description 2
- 238000006386 neutralization reaction Methods 0.000 description 11
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- 239000003344 environmental pollutant Substances 0.000 description 3
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- 238000012360 testing method Methods 0.000 description 3
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 description 2
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- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 description 2
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 2
- 229910052776 Thorium Inorganic materials 0.000 description 2
- 238000009825 accumulation Methods 0.000 description 2
- 230000033228 biological regulation Effects 0.000 description 2
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- 230000007935 neutral effect Effects 0.000 description 2
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- ZSLUVFAKFWKJRC-IGMARMGPSA-N 232Th Chemical compound [232Th] ZSLUVFAKFWKJRC-IGMARMGPSA-N 0.000 description 1
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 1
- UCKMPCXJQFINFW-UHFFFAOYSA-N Sulphide Chemical compound [S-2] UCKMPCXJQFINFW-UHFFFAOYSA-N 0.000 description 1
- 230000002378 acidificating effect Effects 0.000 description 1
- 239000011149 active material Substances 0.000 description 1
- 239000001099 ammonium carbonate Substances 0.000 description 1
- 229910052793 cadmium Inorganic materials 0.000 description 1
- BDOSMKKIYDKNTQ-UHFFFAOYSA-N cadmium atom Chemical compound [Cd] BDOSMKKIYDKNTQ-UHFFFAOYSA-N 0.000 description 1
- 229910000019 calcium carbonate Inorganic materials 0.000 description 1
- 239000000292 calcium oxide Substances 0.000 description 1
- 235000012255 calcium oxide Nutrition 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 229910052804 chromium Inorganic materials 0.000 description 1
- 239000011651 chromium Substances 0.000 description 1
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- UQSXHKLRYXJYBZ-UHFFFAOYSA-N iron oxide Inorganic materials [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 description 1
- 235000013980 iron oxide Nutrition 0.000 description 1
- VBMVTYDPPZVILR-UHFFFAOYSA-N iron(2+);oxygen(2-) Chemical class [O-2].[Fe+2] VBMVTYDPPZVILR-UHFFFAOYSA-N 0.000 description 1
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- 238000012795 verification Methods 0.000 description 1
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Images
Classifications
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/66—Treatment of water, waste water, or sewage by neutralisation; pH adjustment
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2101/00—Nature of the contaminant
- C02F2101/006—Radioactive compounds
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2101/00—Nature of the contaminant
- C02F2101/10—Inorganic compounds
- C02F2101/20—Heavy metals or heavy metal compounds
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2103/00—Nature of the water, waste water, sewage or sludge to be treated
- C02F2103/10—Nature of the water, waste water, sewage or sludge to be treated from quarries or from mining activities
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2209/00—Controlling or monitoring parameters in water treatment
- C02F2209/06—Controlling or monitoring parameters in water treatment pH
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- Life Sciences & Earth Sciences (AREA)
- Hydrology & Water Resources (AREA)
- Engineering & Computer Science (AREA)
- Environmental & Geological Engineering (AREA)
- Water Supply & Treatment (AREA)
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Processing Of Solid Wastes (AREA)
Abstract
The invention provides a long-acting passive treatment method for acid uranium tailing leachate, belonging to the technical field of uranium-containing wastewater treatment. In the retired treatment stage of the uranium tailings, the surface layer part of the uranium tailings slag is mixed with lime, so that the long-term alkaline environment of a retired tailing pond can be maintained, and leaching of radioactive nuclides and heavy metals is reduced; according to the invention, soil-stone materials are covered above the mixed lime layer, so that the precipitation rate of radioactive gas radon on the surface of a tailing pond can be reduced, and the effect of isolating air is also achieved. Meanwhile, a lime wall is arranged between the tailing dam and uranium tailing slag to further neutralize the acid tailing seepage water. In the retirement treatment stage of the tailing pond, the uranium tailing seepage water can stably reach the standard by neutralizing the uranium tailing with lime and arranging a lime wall, and the retirement treatment effect of the tailing pond is stable for a long time. Compared with the method for directly neutralizing the tailing leachate by lime, the method has the advantages that the lime consumption for treating the unit leachate is less, the method is more economical, and the secondary pollution can be avoided.
Description
Technical Field
The invention relates to the technical field of uranium-containing wastewater treatment, in particular to a long-acting passive treatment method for acid uranium tailing leachate.
Background
The exploitation of uranium resources meets the utilization of nuclear energy and nuclear technology, and simultaneously generates a large amount of uranium tailings, and according to the statistics of world energy information service (world information service energy), the total amount of the uranium tailings accumulated in the world reaches 24 hundred million tons by 9 months in 2021. The uranium tailings are weathered or leached by rainwater to form composite wastewater containing radionuclides such as uranium, thorium and radium and toxic heavy metals such as cadmium and chromium. Once the wastewater enters soil and underground water, the wastewater pollutes a tailing pond and surrounding soil, water resources and ecological environment, and further harms human health.
Permeable Reactive Barrier (PRB) is a method for removing heavy components of polluted groundwater in situ in developed countries such as europe and america in the 90 s of the 20 th century, and is a method for disposing an active material wall underground to intercept a polluted plume so that pollutants can be converted into another form acceptable to the environment after the polluted plume passes through a reaction medium, thereby achieving the purpose of enabling the concentration of the pollutants to reach the environmental pollution. The existing experimental research shows that radioactive substances, heavy metals and the like dissolved in underground water can be effectively controlled and treated by using the permeable reactive barrier technology. Morrison S J et al (Morrison S J, mushovic P S, niesen P L. Early break of molybdenum and uranium in a permanent reactive barrier [ J ]. E20viron Sci Technol,2006,40 (6): 2018-202) use FeO-PRB to treat uranium and molybdenum in contaminated groundwater, and after 8 months, the uranium concentration in the groundwater is reduced from 1.0mg/L to 0.02mg/L or less, but investigations have shown that iron oxides, calcium carbonate and sulfides are precipitated inside the reaction wall and on the surface of zero-valent iron, and the production of precipitates reduces the permeability of the reaction wall and even causes clogging, and reduces the effectiveness and activity of zero-valent iron.
The acid tailings are generally neutralized by lime before being stacked or entering a tailing dam, so that most radium, other radionuclides, salt and heavy metals are precipitated, but the method is a short-term measure, and when sulfides exist in tailings, the sulfides are oxidized to cause a low-pH environment, so that the metals and the radionuclides are leached again and migrate to the environment along with seepage water.
Disclosure of Invention
In view of this, the invention aims to provide a long-term-effectiveness passive treatment method for acid uranium tailing leachate, and the treatment method provided by the invention can realize long-term failure treatment of acid uranium tailings.
In order to achieve the above object, the present invention provides the following technical solutions:
the invention provides a long-acting passive treatment method for acid uranium tailing leachate, which comprises the following steps:
in the retirement treatment stage of uranium tailings, mixing the surface layer part of uranium tailings slag in a uranium tailings pond with lime to obtain a mixed lime layer, and covering an earth-rock material on the mixed lime layer; and a tailing dam is arranged at the downstream tail end of the uranium tailing pond, and a lime wall with a certain thickness is filled between the tailing dam and uranium tailing slag.
Preferably, the thickness of the surface layer part of the uranium tail slag is 20-50 cm.
Preferably, the mass ratio of the surface layer part of the uranium tailing slag to the lime is 100:0.5 to 5.
Preferably, the earth and stone material is one or more of waste stone, loess, medium sand and kaolin.
Preferably, the thickness of the earth and stone material is more than or equal to 50cm.
Preferably, the thickness of a lime wall between the tailing dam and the uranium tailing slag is 1-3 m, the height of the lime wall is the same as the total height of the uranium tailing slag, the mixed lime layer and the earth-rock material, and the length of the lime wall is the same as the length of the tailing dam.
Preferably, the bottom of the uranium tailing pond is provided with a clay water barrier layer.
Preferably, the pH value of the uranium tailing leachate is less than 6.
The invention provides a long-acting passive treatment method for acid uranium tailing leachate, which comprises the following steps: in the retirement treatment stage of uranium tailings, mixing the surface layer part of uranium tailings slag in a uranium tailings pond with lime to obtain a mixed lime layer, and covering an earth-rock material on the mixed lime layer. In the retired treatment stage of the uranium tailings, the surface layer part of the uranium tailings slag is mixed with lime, so that the long-term alkaline environment of a retired tailing pond can be maintained, and leaching of radioactive nuclides and heavy metals is reduced; according to the invention, soil and stone materials are covered above the mixed lime layer, so that the precipitation rate of radon on the surface of the tailing pond can be reduced, and the effect of isolating air is also achieved. Meanwhile, a lime wall is arranged between the tailing dam and uranium tailing slag to further neutralize the acid tailing seepage water. The treatment method provided by the invention can prevent sulfide in the uranium tail slag from oxidizing and acid-reversing, avoids the situation that the radionuclide and heavy metal in the uranium tail slag are leached again to pollute the environment, and finally realizes the long-term stable retirement treatment effect of the tailing pond. Meanwhile, in the retirement treatment stage of the tailing pond, the uranium tailing seepage water can stably reach the standard by neutralizing the uranium tailing with lime and arranging a lime wall, and compared with a method for directly neutralizing the uranium tailing seepage water with lime, the method for treating the uranium tailing seepage water has the advantages that the lime consumption for treating the unit seepage water is less, the method is more economic, and the generation of secondary pollution can be avoided.
Drawings
FIG. 1 is a schematic diagram of a simulated lime neutralization reaction of example 1;
FIG. 2 is a schematic diagram of example 1 simulating lime neutralization of tailing leachate;
FIG. 3 is a schematic illustration of example 1 simulating neutralization of tailings of the present invention;
fig. 4 is a schematic view of the treatment of the tailings seepage water 765 in example 2.
Detailed Description
The invention provides a long-acting passive treatment method for acid uranium tailing leachate, which comprises the following steps:
in the retirement treatment stage of uranium tailings, mixing the surface layer part of uranium tailings slag in a uranium tailings pond with lime to obtain a mixed lime layer, and covering an earth-rock material on the mixed lime layer.
In the invention, the uranium tailings are preferably acid-leached uranium tailings.
In the invention, the content of uranium in the uranium tailings is preferably 4.0 x 10 2 ～5.0×10 4 Bq/kg， 226 The Ra content is preferably 5.00X 10 3 ～7.50×10 4 Bq/kg。
In the invention, the pH value of the uranium tailing seepage water is preferably less than or equal to 6, and more preferably 4-5.
In the present invention, the particle size of the uranium tailings is preferably a natural particle size.
In the retirement treatment stage of uranium tailings, the surface layer part of uranium tailings slag in a uranium tailing pond is mixed with lime to obtain a mixed lime layer. In the present invention, the thickness of the surface layer portion of the uranium tail slag is preferably 20 to 50cm, and more preferably 30 to 40cm.
In the invention, the mass ratio of the surface layer part of the uranium tail slag to lime is preferably 100:0.5 to 5, more preferably 100:1 to 2.
The invention does not require any particular mixing means, as is known to those skilled in the art, such as stirring.
According to the invention, the surface layer part of the uranium tailing slag is mixed with lime, so that a long-term alkaline environment of a retired tailing pond can be maintained, and the oxidation and acid reversion of sulfides in the uranium tailing slag are prevented, thereby reducing the leaching of radioactive nuclides and heavy metals.
After the mixed lime layer is obtained, earth and stone materials are covered above the mixed lime layer. In the invention, the earth-rock material is preferably one or more of waste stone, loess, medium sand and kaolin.
In the present invention, the particle size of the earth and stone material is a natural particle size.
In the invention, the thickness of the earth and stone material is preferably more than or equal to 50cm; wherein, the thickness of the waste stone is preferably 0.5 to 3.0m, and the thickness of the loess is preferably 0.3 to 1.0m; the thickness of the gravelly soil is preferably 0.3 to 0.5m.
In the invention, the soil-stone material can reduce the precipitation rate of radioactive gas radon on the surface of the tailing pond and also has the function of isolating air. According to the invention, through the accumulation of the covering soil-stone material on the surface of the tailing yard, the diffusion coefficient of radon can be reduced, the diffusion retention time of free radon in the covering material is increased, and the decay of radon in the covering layer before the radon enters the atmosphere is ensured through the hysteresis effect, so that the precipitation and release of radon are reduced.
In the invention, a tailing dam is preferably arranged on the side surface of the uranium tailing pond, and a lime wall with a certain thickness is filled between the tailing dam and uranium tailing slag. The method has no special requirements on the height and specification of the tailing dam, and the tailing dam can be designed correspondingly according to natural conditions and specific conditions.
In the present invention, the thickness of the lime is preferably 1 to 3m, more preferably 1.5 to 2.5m; the height of the dam is the same as the total height of the uranium tailings, the mixed lime layer and the earth-rock materials, and the length of the dam is the same as the length of the tailings dam.
According to the invention, the lime wall with a certain thickness is filled between the tailing dam and the uranium tailing slag, so that the acid uranium tailing seepage water can be neutralized, and the precipitation of the acid uranium tailing seepage water is reduced.
In the invention, the bottom of the uranium tailing pond is preferably provided with a clay water-resisting layer. According to the invention, the clay water-resisting layer can prevent the acid tailings from seeping water to pollute the underground water.
The method for long-term passive treatment of acid uranium tailing leachate provided by the present invention is described in detail with reference to the following examples, but they should not be construed as limiting the scope of the present invention.
Example 1
Two organic glass reaction columns are designed, the diameter is 160mm, the height is 40mm, and the two organic glass reaction columns are respectively marked as a column 1 and a column 2. Feed liquid is continuously sprayed into the reaction column body from the column top through the constant flow pump according to 24h/d, and percolate is collected from the column bottom through the water outlet and is used for simulating lime neutralization reaction, as shown in figure 1.
The column 1 is filled with 1.5kg of lime, uranium tailing leachate is continuously poured from the top of the column through a constant flow pump, the flow rate is controlled to be 0.15L/h-0.3L/h, and the process of neutralizing the tailing leachate with the lime is simulated, as shown in figure 2.
Continuously running for 143 days, regularly recording the flow and pH value of the seepage liquid seeped from the water outlet at the bottom of the column every day, and sampling and analyzing other items at regular intervals according to the quality of the seepage water, wherein the obtained results are shown in Table 1.
TABLE 1 lime neutralization tailings leachate test results
| Run time (d) | 0 | 2 | 5 | 9 | 15 |
| Cumulative flow (L) | - | 8.52 | 27.68 | 53.13 | 90.12 |
| pH | 2.6 | ＞13.0 | ＞13.0 | ＞13.0 | ＞13.0 |
| U(mg/L) | 8.4 | 0.00 | 0.01 | 0.00 | 0.00 |
| 226 Ra(Bq/L) | 0.36 | 0.07 | - | 0.14 | 0.1 |
| Run time (d) | 22 | 34 | 41 | 48 | 55 |
| Cumulative flow (L) | 122.02 | 168.15 | 191.19 | 226.89 | 254.74 |
| pH | ＞13.0 | ＞13.0 | ＞13.0 | 11.5 | 10.3 |
| U(mg/L) | 0.01 | 0.04 | 0.23 | 0.14 | 0.07 |
| 226 Ra(Bq/L) | 0.09 | 0.2 | 0.31 | 0.32 | 0.29 |
| Run time (d) | 62 | 69 | 76 | 86 | 94 |
| Cumulative flow (L) | 285.44 | 309.51 | 337.21 | 363.15 | 397.98 |
| pH | 8.7 | 8.1 | 4.6 | 4.4 | 4.3 |
| U(mg/L) | 0.91 | 2.08 | 2.24 | 4.96 | 5.8 |
| 226 Ra(Bq/L) | 0.32 | 0.38 | - | - | 0.33 |
| Run time (d) | 101 | 108 | 115 | 122 | 143 |
| Cumulative flow (L) | 432.32 | 465.97 | 510.12 | 548.05 | 661.46 |
| pH | 4.3 | 4.3 | 4.3 | 3.6 | 3.1 |
| U(mg/L) | 5.6 | 5.1 | 4.1 | 4.3 | 5.9 |
| 226 Ra(Bq/L) | 0.36 | 0.43 | - | - | 0.25 |
As can be seen from Table 1, in the early period of operation (within 55 d), the pH value of the neutralization tail solution is alkaline, the U concentration of the neutralization tail solution is less than 0.3mg/L, 226 ra concentration is less than 1.1Bq/L, and the discharge outlets U and U meet the regulation of radiation protection and radiation environment protection for uranium mining and metallurgy (GB 23727-2020) 226 Emission limits of Ra requirements. However, as the operation time increases (when the operation time reaches 62 d), the lime can not neutralize the tailing seepage water basically, namely the water quality can not reach the discharge standard, and at the moment, 1kg of lime can neutralize the tailing seepage water by about 285.44/1.5=190.29L.
The column 2 was filled with 2kg of tailings, 1kg of 1 wt% lime-doped tailings and 1kg of waste rock from bottom to top, and tap water was continuously poured from the top of the column by a constant flow pump at a flow rate of 0.15L/h to 0.3L/h, simulating the tailing neutralization process of the present invention, as shown in fig. 3. The flow rate and pH value of the exudate from the water outlet at the bottom of the column were recorded every day at regular intervals, and the other items were sampled and analyzed at regular intervals depending on the quality of the exudate, and the obtained results are shown in Table 2.
TABLE 2 neutralization test results of tailings
| Run time (d) | 0 | 7 | 14 | 21 | 28 |
| Cumulative flow (L) | - | 45.47 | 83.03 | 155.16 | 207.51 |
| pH | 6.9 | ＞10.0 | ＞10.0 | 9.1 | 8.65 |
| U(mg/L) | 0.003 | 0.014 | 0.02 | 0.02 | 0.014 |
| 226 Ra(Bq/L) | 0.05 | 1.59 | 1.25 | 1.73 | 0.43 |
| Run time (d) | 35 | 42 | 49 | 56 | 68 |
| Accumulation ofFlow (L) | 240.33 | 262.03 | 287.13 | 311.75 | 350.38 |
| pH | 9.3 | 8.7 | 8.9 | 8.9 | 8.7 |
| U(mg/L) | 0.01 | 0.03 | 0.03 | 0.03 | 0.03 |
| 226 Ra(Bq/L) | 0.33 | - | 0.27 | 0.3 | 0.25 |
| Run time (d) | 75 | 82 | 90 | 97 | 104 |
| Cumulative flow (L) | 378.39 | 410.58 | 451.33 | 490.15 | 530.33 |
| pH | 8.3 | 7.6 | 7.8 | 7.5 | 7.2 |
| U(mg/L) | 0.04 | 0.03 | 0.02 | 0.02 | 0.02 |
| 226 Ra(Bq/L) | 0.37 | 0.44 | 0.4 | 0.54 | 0.33 |
| Run time (d) | 117 | 124 | 140 | - | - |
| Cumulative flow (L) | 546.99 | 585.44 | 681.72 | - | - |
| pH | 7.3 | 7.8 | 7.2 | - | - |
| U(mg/L) | 0.01 | 0.02 | 0.01 | - | - |
| 226 Ra(Bq/L) | - | - | 0.67 | - | - |
As can be seen from Table 2, after the tailings are neutralized by lime, the pH value of the tailing seepage water is basically maintained to be alkalescent and neutral, the U concentration in the tailing seepage water can be stably less than 0.3mg/L, 226 ra concentration is less than 1.1Bq/L after 28 days of operation, and wastewater discharge outlets U and U meet the uranium mining and metallurgy radiation protection and radiation environment protection regulations (GB 23727-2020) 226 Emission limits of Ra requirements. Compared with the method for neutralizing the tailing leachate by using lime, the method for neutralizing the tailing leachate by using lime has more stable treatment effect on the tailing leachate under the condition of continuous operation for the same time. When the water seeps and accumulatesWhen the amount reaches 530.33L, the pH of the seeping water is close to neutral, and the water amount treated by 1kg of lime is 530.33/0.01=5.3 × 10 4 (L) the amount of tailings that passed through was 3/0.01=300kg.
The test results in tables 1 and 2 show that: according to the invention, the tailings are neutralized by lime, so that the tailing seepage water can reach the standard more stably, the lime consumed by treating unit seepage water is less, certain economic feasibility is realized, and meanwhile, in the retirement treatment stage of a tailing pond, the generation of secondary pollution can be avoided by adding lime into the tailings.
Example 2
(1) Case background
765 the ore is located in Bo Shang Zhen in Lincang city of Yunnan province, the primary product is uranium ore, the hydrometallurgy process adopts the flow of sulfuric acid percolation leaching-clear liquid extraction-ammonium carbonate back extraction-filtration-uranyl ammonium tricarbonate, and the final product is uranyl tricarbonate. 1994, 765 mine production stoppage instruction, and tailing stacking is about 9.22 ten thousand meters 3 The acid uranium-bearing tailings seeping water is generated, the pH value is between 2.5 and 2.9, and the residual U in the uranium tailings is natural, 226 Ra and Th are natural, 210 Po、 210 The Pb is continuously leached under the acidic condition, thereby causing certain pollution to the environment.
Seventy-six-five mine retired environment treatment engineering is officially completed in 11 months in 2001 and is completely completed at the end of 5 months in 2007 for 5 and half years.
(2) Case implementation
765 the retirement treatment scheme of lime neutralizing tailings is adopted in the retirement treatment process of the mine tailing yard, which comprises the following steps:
waste (ore) stones, coal slag, dirty soil and the like which need to be cleared and dug to a tailing yard are covered on the tailing yard with the thickness of 2.30m, and then 0.9m of loess is covered on the upper part, so that the loess is prevented from being lost due to change of dry cracking in rainy and dry seasons and rain wash, and 0.3m thick gravelly soil is covered on the loess. The main ditch is treated in a step mode, the width of the platform is equal to that of the slope, and 2-3% of inner slope is formed on the platform to prevent surface water from converging to wash the steps. Concrete drainage ditches are cast in situ at the slope toe, and infiltration of surface water is reduced. In addition, a rubble intercepting ditch is built at the junction of the tailing yard and the upper side slope, and surface water in a catchment area outside the yard is intercepted. When a tailing yard is regulated, surface tailings (40 cm thick) are doped with a proper amount of quicklime for neutralization (tailing neutralization), in order to ensure that the seepage water of a tailing pond stably reaches the standard for a long time, a lime wall with the thickness of 2m and the depth of 3m is added between a tailing dam and uranium tailings for neutralizing acid water, so that the seepage of the acid water is reduced, and the structural schematic diagram is shown in fig. 4.
In 2014, the tailing pond seepage water is verified and monitored, and the result is shown in table 3.
TABLE 3 765 tailing seepage water treatment effect
As can be seen from Table 3, from 765 mine retired treatment completion in 2007 to 2014, verification and monitoring show that the pH of the tailing seepage water after retired treatment is obviously increased, the concentrations of other pollutants are reduced in different degrees, the effect is still obvious after seven years of tailings retired treatment, and the emission standard is met.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.
Claims (9)
1. A long-acting passive treatment method for acid uranium tailing leachate comprises the following steps:
in the retirement treatment stage of uranium tailings, mixing the surface layer part of uranium tailings slag in a uranium tailings pond with lime to obtain a mixed lime layer, and covering an earth-rock material on the mixed lime layer.
2. The processing method according to claim 1, wherein the thickness of the surface layer portion of the uranium tailing slag is 20 to 50cm.
3. The processing method according to claim 1 or 2, wherein the mass ratio of the surface layer part of the uranium tailings slag to lime is 100:0.5 to 5.
4. The treatment method according to claim 1, wherein the earth-rock material is one or more of waste stone, loess, medium sand and kaolin.
5. The process according to claim 1 or 4, wherein the thickness of said earth-rock material is greater than or equal to 50cm.
6. The treatment method of claim 1, wherein a tailing dam is arranged at the downstream end of the uranium tailing pond, and a lime wall with a certain thickness is filled between the tailing dam and the uranium tailing slag.
7. The treatment method according to claim 6, wherein the thickness of the lime wall is 1-3 m, the height of the lime wall is the same as the total height of the uranium tailings slag, the mixed lime layer and the earth-rock material, and the length of the lime wall is the same as the length of the tailings dam.
8. The treatment method according to claim 1, wherein a clay water barrier is arranged at the bottom of the uranium tailings pond.
9. The treatment method according to claim 1, wherein the pH value of the uranium tailings leachate is less than or equal to 6.
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