Method for in-situ collaborative development of coal rock-sandstone type uranium ore

Abstract

The invention discloses a method for in-situ collaborative development of coal rock-sandstone type uranium ore, which is characterized in that uranium resources in coal rock type and sandstone type uranium ore are mined through a method of combining coal underground gasification and in-situ neutral (CO2 + O2) in-situ leaching, and gasification clean utilization of coal resources and collaborative development of sandstone type and coal rock type uranium ore resources can be realized. The method has the advantages of low energy consumption, high resource recovery rate, simple process, low environmental influence and the like, conforms to the concept of green mines, and has important significance for meeting the requirements of strategic key metal uranium resources in China and protecting the environment.

Description

Technical Field

[0001] The invention relates to the field of coal rock-sandstone type uranium mine development, and in particular to a method for in-situ collaborative development of coal rock-sandstone type uranium mines. Background Art

[0002] Strategic key uranium metal is an important raw material for the nuclear industry and has irreplaceable uses in important fields such as national defense and military industry. The main uranium mines with industrial significance in my country are volcanic rock, granite, coal rock and sandstone uranium mines. Hard rock uranium mines (volcanic rock type, granite type) must be mined to the surface before further beneficiation and processing, which causes great damage to the surface and serious harm to the environment. Most hard rock uranium mines have been closed and turned to sandstone and coal rock uranium mining. Coal rock uranium ore is a uranium-rich coal seam formed by the adsorption and strong reduction of coal. Sandstone uranium ore is a uranium deposit produced in sandstone (including gravel sandstone, siltstone, mudstone). However, the existing mining method is single uranium mining, which has problems such as low uranium recovery rate, high cost and great impact on the environment. Coal rock uranium ore mainly obtains uranium by combustion and sulfuric acid leaching after underground mining, but the uranium recovery rate of this process is low, and the volatilization of uranium during combustion has serious harm to the environment and human health. The uranium deposits in sandstone-type uranium deposits have low consolidation degree and rich groundwater in the ore layers, which cannot be mined from underground to the surface, limiting the development of sandstone-type uranium deposits. The Ili Basin in Xinjiang is rich in coal-rock-type uranium and sandstone-type uranium resources, and there are strata where sandstone-type uranium deposits and coal-rock-type uranium deposits are in contact, which provides the possibility for the coordinated mining of uranium in coal and sandstone. Summary of the invention

[0003] In view of the above technical deficiencies, the purpose of the present invention is to provide a method for in-situ coordinated development of coal-rock-sandstone type uranium deposits, which is achieved by underground coal gasification, in-situ neutral (CO 2 +O 2 ) The method of combining in-situ leaching with in-situ leaching can be used to mine uranium resources in coal-rock and sandstone uranium deposits, which can achieve the clean utilization of coal resources through gasification and the coordinated development of sandstone and coal-rock uranium resources.

[0004] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0005] The present invention provides a method for in-situ collaborative development of coal rock-sandstone type uranium ore, comprising the following method:

[0006] Step 1: Digest the sampled sandstone and coal, and use inductively coupled plasma mass spectrometry to test the content of strategic key metal uranium;

[0007] Step 2: Select coal-rock and sandstone-type uranium deposits with a thickness of coal seams and sandstone layers greater than a, with impermeable roof and floor, and uranium content in coal ash and sandstone higher than the set value as research objects, conduct subsequent underground gasification of coal samples and in-situ neutral leaching of sandstone-coal-rock uranium deposits, and jointly mine uranium resources;

[0008] Step 3: Detect the mineral composition of coal and sandstone and the uranium-containing carrier minerals to obtain their composition;

[0009] Step 4: Use step-by-step chemical extraction experiments to determine the occurrence state of uranium in sandstone and simulated gasification coal ash;

[0010] Step 5: Field drilling is carried out in the study area, including several groups of gas holes, coal seam gasification channels and sandstone blasting channels are opened in the lower part of the coal seam and sandstone layer, and then the coal is gasified;

[0011] Step 6: After coal gasification, the sandstone uranium ore above the coal seam is initially broken; the sandstone layer is broken through the sandstone blasting channel, so that the sandstone block is further broken, which is conducive to the subsequent uranium leaching;

[0012] Step 7: Use the pores to introduce CO 2 and O 2 , O 2 Oxidize tetravalent uranium to hexavalent uranium; because the sandstone layer is rich in groundwater, the CO 2 Dissolves in groundwater to form HCO 3 - , which then reacts with the oxidized hexavalent uranium to leach out the strategic key metal uranium;

[0013] Step 8: Use the low-level pores to send the extraction device into the underground leaching location, extract the uranium-rich leaching solution through the pores to the ground leaching solution storage device, and transport it to the leaching solution processing plant to recover and purify the strategic key uranium metal.

[0014] Preferably, in step one, the sandstone and coal obtained by drilling sampling are digested according to the national standard GB / T 14506.30-2010 "Chemical analysis methods of silicate rocks - Part 30: Determination of 44 elements".

[0015] Preferably, in step 2, the thickness a of the coal seam and sandstone layer is 2 m, and the coal rock type and sandstone type uranium deposits with uranium contents in the coal ash and sandstone respectively higher than 1000 μg / g and 0.01% are the research objects.

[0016] Preferably, in step three, an X-ray diffractometer and a scanning electron microscope energy dispersive spectrometer are used to detect the mineral composition in the coal and sandstone.

[0017] Preferably, the specific method in step 4 includes:

[0018] 4.1. Weigh 2g of 200-mesh gasified coal ash or sandstone sample into a 100mL centrifuge tube, add 60mL of 1mol / L magnesium chloride solution, and place in an oscillating box at 200r / min and 25°C for reaction for 1h; the supernatant in the centrifuge tube is separated by centrifugation at 4000r / min for 5-10min, and the supernatant is in an exchangeable state. The residue at the bottom, i.e., residue I, is dried at 90°C to constant weight;

[0019] 4.2. Add 60 mL of 1 mol / L sodium acetate solution to the residue I, adjust the pH to 5 with acetic acid, place in an oscillating box at 200 r / min and 25°C for 8 hours, and the supernatant after centrifugation is in a carbonate state. The bottom residue, i.e., residue II, is dried at 90°C to constant weight;

[0020] 4.3. Add 60 mL of 0.04 mol / L hydroxylamine hydrochloride solution prepared with 25% acetic acid to the residue II, place in an oscillating box at 200 r / min and 95° C. for 4 h, and after centrifugation, the supernatant is in the state of iron and manganese oxides, and the residue at the bottom, i.e., the residue III, is dried at 90° C. to constant weight;

[0021] 4.4. Add 10 mL of 0.02 mol / L nitric acid and 30 mL of 30% hydrogen peroxide solution to the residue III, adjust the pH to 2 with nitric acid, and place in an oscillating box at 200 r / min and 85°C for reaction for 5 hours;

[0022] After cooling, add 20 mL of 1 mol / L ammonium acetate solution prepared with 20% nitric acid solution, place in an oscillating box at 200 r / min and 25°C to react for 0.5 h, centrifuge, and the supernatant is organic, and the bottom residue, i.e., residue IV, is dried at 90°C to constant weight;

[0023] 4.5. Since the gasified coal ash has an amorphous glass phase after high-temperature combustion, in order to more accurately determine the occurrence state of uranium in the gasified coal ash, the gasified coal ash sample needs to be further dissolved into a glass phase and a residue state after step 4.4;

[0024] By adding 40 mL of concentrated hydrofluoric acid, placing it in an oscillating box at 200 r / min and 85°C for 2 hours, the supernatant after centrifugation is in a glass phase, and its components include aluminosilicates. The bottom residue, namely residue IV, is dried at 90°C to constant weight. This step is not required for sandstone;

[0025] 4.6. According to the national standard GB / T 14506.30-2010 "Chemical analysis methods of silicate rocks - Part 30: Determination of 44 elements", the residue IV is digested and the obtained digestion solution is in the residue state;

[0026] 4.7. The content of strategic key metal uranium in exchangeable, carbonate, iron-manganese oxide, organic and residual states is tested by inductively coupled plasma mass spectrometry.

[0027] Preferably, the specific reaction mechanism in step 7 is as follows:

[0028] CO 2 +H 2 O=H 2 CO 3

[0029]

[0030] 2UO 2 +O 2 =2UO 3

[0031] UO 3 +2HCO 3 - =[UO 2 (CO 3 ) 2 ] 2- +H 2 O

[0032] [UO 2 (CO 3 ) 2 ] 2- +HCO 3 - =[UO 2 (CO 3 ) 3 ] 4- +H + .

[0033] The beneficial effects of the present invention are as follows: the method uses underground coal gasification, in-situ neutral (CO 2 +O 2 ) The method of combining in-situ leaching with in-situ leaching to mine uranium resources in coal-rock and sandstone uranium deposits can realize the clean utilization of coal resources by gasification and the coordinated development of sandstone and coal-rock uranium resources. It has the advantages of low energy consumption, high resource recovery rate, simple process and low environmental impact. It is in line with the concept of green mines and is of great significance to solving my country's demand for strategic key metallic uranium resources and environmental protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0035] Figure 1 A schematic flow chart of a method for in-situ collaborative development of coal-rock-sandstone type uranium deposits provided by an embodiment of the present invention;

[0036] Figure 2 This is a schematic diagram of the underground gasification and in-situ neutral leaching structure of coal rock and sandstone type uranium mines.

[0037] Figure numerals: 1-gas hole, 2-gasification ignition device, 3-gas recovery and separation device, 4-coal bed gasification channel, 5-sandstone blasting channel, 6-extraction device, 7-leachate storage device. DETAILED DESCRIPTION

[0038] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0039] like Figure 1 to Figure 2 As shown, a method for in-situ collaborative development of coal-rock-sandstone type uranium ore comprises the following steps:

[0040] Step 1: According to the national standard GB / T 14506.30-2010 "Chemical analysis methods of silicate rocks - Part 30: Determination of 44 elements", the sandstone and coal obtained from the drilling samples are digested and the content of strategic key metal uranium is tested using inductively coupled plasma mass spectrometry (ICP-MS).

[0041] Step 2: Select coal-rock and sandstone-type uranium deposits with a thickness of more than 2 m, impermeable roof and floor, and uranium contents in coal ash and sandstone higher than 1000 μg / g and 0.01% respectively as research objects, conduct subsequent underground gasification of coal samples and in-situ neutral leaching of sandstone-coal-rock uranium deposits to jointly mine uranium resources.

[0042] Step 3: Mineral composition and uranium-containing carrier minerals in coal and sandstone.

[0043] The mineral composition of coal and sandstone was detected by X-ray diffractometer (XRD) and scanning electron microscope energy dispersive spectrometer (SEM-EDS). The results showed that the minerals in coal are mainly quartz, kaolinite, pyrite, accompanied by a small amount of calcite, illite, gypsum, sphalerite, rutile, uranite, pitchblende and titanium-containing uranium minerals; the minerals in sandstone are mainly quartz, accompanied by a small amount of kaolinite, illite, pyrite, calcite, orthoclase, pitchblende, uranite, calcium-uranium mica, calcium-uranite and titanium-containing uranium minerals. Among them, the uranium carrier minerals in coal-rock type uranium deposits are mainly uranite, pitchblende, and a small amount of titanium-containing uranium minerals; the uranium carrier minerals in sandstone type uranium deposits are mainly pitchblende, and a small amount of uranite, titanium-containing uranium minerals, calcium-uranium mica, and calcium-uranite.

[0044] Step 4: Occurrence state of strategic critical metallic uranium in gasification coal ash and sandstone.

[0045] The occurrence state of uranium in sandstone and gasified coal ash is determined by step-by-step chemical extraction experiments. The specific operations are as follows:

[0046] 4.1. Weigh 2g of 200-mesh coal or sandstone sample into a 100mL centrifuge tube and add 1mol / L magnesium chloride (MgCl 2 ) solution 60mL, placed in an oscillating box at 200r / min and 25°C for reaction for 1h; the supernatant in the centrifuge tube was separated after centrifugation at 4000r / min for 5-10min. The supernatant was in an exchangeable state, and the bottom residue (residue I) was dried at 90°C to constant weight.

[0047] 4.2. Add 1 mol / L sodium acetate (CH 3 COONa) solution 60 mL, using acetic acid (CH 3 COOH) to adjust the pH to 5, place it in an oscillating box at 200 r / min and 25°C to react for 8 hours, and the supernatant after centrifugation is in a carbonate state, and the bottom residue (residue II) is dried at 90°C to constant weight.

[0048] 4.3. Add 25% acetic acid (CH 3 COOH) prepared with 0.04 mol / L hydroxylamine hydrochloride (NH 2 The mixture was added with 60 mL of 2-H-OH·HCl solution and placed in an oscillating box at 200 r / min and 95°C for 4 h. The supernatant after centrifugation was in the state of iron and manganese oxides, and the residue at the bottom (residue III) was dried at 90°C to constant weight.

[0049] 4.4. Add 10 mL of 0.02 mol / L nitric acid (HNO 3 ) and 30 mL 30% hydrogen peroxide solution, using nitric acid (HNO 3) to adjust pH to 2, place in an oscillating box at 200 r / min and 85°C for 5 h. After cooling, add 20 mL of 20% nitric acid (HNO 3 ) solution prepared with 1 mol / L ammonium acetate (CH 3 COONH 4 ) solution, placed in an oscillating box at 200 r / min and 25°C for reaction for 0.5 h, the supernatant after centrifugation was organic, and the bottom residue (residue IV) was dried at 90°C to constant weight.

[0050] 4.5. Since the gasified coal ash has an amorphous glass phase after high-temperature combustion, in order to more accurately determine the occurrence state of uranium in the gasified coal ash, the gasified coal ash sample needs to be further dissolved into a glass phase and a residue state after step 4.4. By adding 40 mL of concentrated hydrofluoric acid (HF), placing it in an oscillating box at 200 r / min and 85°C for 2 hours, the supernatant after centrifugation is a glass phase, the main component of which is aluminosilicate, and the bottom residue (residue IV) is dried at 90°C to constant weight. Sandstone does not need this step.

[0051] 4.6. According to the national standard GB / T 14506.30-2010 "Chemical analysis methods of silicate rocks - Part 30: Determination of 44 elements", the residue IV is digested and the digestion solution obtained is in the residue state.

[0052] 4.7. The content of strategic key metal uranium in exchangeable, carbonate, iron-manganese oxide, organic and residual states was tested by inductively coupled plasma mass spectrometry (ICP-MS). The results show that uranium in sandstone mainly exists in the form of carbonate, followed by iron-manganese oxide, organic, and a small amount of exchangeable and residual states; uranium in gasified coal ash is mainly in the glass phase and residual state, followed by iron-manganese oxide and organic states, and a small amount of exchangeable and carbonate states. The proportion of uranium in carbonate, glass phase, iron-manganese oxide and organic states is relatively large, indicating that uranium is easier to leach.

[0053] Step 5: Field drilling is carried out in the study area, including three groups of 6 gas holes 1, 2 gas holes in each group, and also including coal seam gasification channel 4 and sandstone blasting channel 5. First, the ignition rod is sent into the coal seam gasification channel, and the gasification ignition device 2 enters the coal seam through the gas hole, and 50% oxygen-enriched air gasification agent is injected through the gas hole and ignited to gasify the coal. The combustible gases (CO, H 2 , CH 4 etc.) and non-combustible gases (CO 2 etc.) are discharged through the pores and separated by the ground gas recovery and separation device 3, wherein CO 2 It can be used for subsequent in-situ neutral leaching, and the combustible gas can be used as clean gas fuel for power plants, etc.

[0054] Step 6: Due to the low consolidation degree of the sandstone layer, the sandstone-type uranium ore above the coal seam is initially crushed after coal gasification. The blasting material is sent to the sandstone layer through the sandstone crushing channel and crushed by the ground detonator, so that the sandstone block is further crushed, which is conducive to the subsequent uranium leaching. The amount of blasting material used does not damage the top plate of the sandstone layer, making the top plate structure stable.

[0055] Step 7: In-situ neutral leaching of uranium.

[0056] Carbon dioxide (CO) is introduced through the stomata 2 ) and oxygen (O 2 ), where O 2 It is an oxidant that oxidizes tetravalent uranium to hexavalent uranium. Since the sandstone layer is rich in groundwater, the CO 2 Dissolves in groundwater to form HCO 3 - , and then react with the oxidized hexavalent uranium to leach out the strategic key metal uranium. The reaction mechanism is as follows:

[0057] CO 2 +H 2 O=H 2 CO 3

[0058]

[0059] 2UO 2 +O 2 =2UO 3

[0060] UO 3 +2HCO 3 - =[UO 2 (CO 3 ) 2 ] 2- +H 2 O

[0061] [UO 2 (CO 3 ) 2 ] 2- +HCO 3 - =[UO 2 (CO 3 ) 3 ] 4- +H +

[0062] Compared with the great impact of acid (sulfuric acid) and alkaline (ammonium bicarbonate, sodium bicarbonate, sodium carbonate) leaching on the groundwater environment, and the fact that acid and alkaline leaching are prone to produce precipitation and blockage of channels, which is not conducive to the mining of uranium in coal rock and sandstone uranium deposits, neutral leaching of uranium with CO 2 Prepare leaching agent with groundwater, O 2 As an oxidant, it has the advantages of mild leaching environment, high resource recovery rate, and little impact on the groundwater environment. 2 , which is of great significance to the protection of ecosystems.

[0063] Step 8: Send the extraction device 6 to the underground leaching position through the two low-position air holes, extract the uranium-rich leaching solution through the air holes to the ground leaching solution storage device 7, and transport it to the leaching solution treatment plant to recover and purify the strategic key uranium metal.

[0064] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A method for in-situ collaborative development of coal-rock-sandstone type uranium deposits, characterized in that: The following methods are included: Step 1: Digest the sampled sandstone and coal, and use inductively coupled plasma mass spectrometry to test the content of strategic key metal uranium; Step 2: Select coal-rock and sandstone-type uranium deposits with a thickness of coal seams and sandstone layers greater than a, with impermeable roof and floor, and uranium content in coal ash and sandstone higher than the set value as research objects, conduct subsequent underground gasification of coal samples and in-situ neutral leaching of sandstone-coal-rock uranium deposits, and jointly mine uranium resources; Step 3: Detect the mineral composition of coal and sandstone and the uranium-containing carrier minerals to obtain their composition; Step 4: Use step-by-step chemical extraction experiments to determine the occurrence state of uranium in sandstone and simulated gasification coal ash; Step 5: Field drilling is carried out in the study area, including several groups of gas holes, coal seam gasification channels and sandstone blasting channels are opened in the lower part of the coal seam and sandstone layer, and then the coal is gasified; Step 6: After coal gasification, the sandstone uranium ore above the coal seam is initially broken; the sandstone layer is broken through the sandstone blasting channel, so that the sandstone block is further broken, which is conducive to the subsequent uranium leaching; Step 7: Use the pores to introduce CO2 and O2, O2 oxidizes tetravalent uranium to hexavalent uranium; because the sandstone layer is rich in groundwater, the introduced CO2 dissolves in the groundwater to form HCO3 - , which then reacts with the oxidized hexavalent uranium to leach out the strategic key metal uranium; Step 8: Use the low-level pores to send the extraction device into the underground leaching location, extract the uranium-rich leaching solution through the pores to the ground leaching solution storage device, and transport it to the leaching solution processing plant to recover and purify the strategic key uranium metal.

2. The method for in-situ collaborative development of coal-rock-sandstone type uranium ore according to claim 1, characterized in that: In step 1, the sandstone and coal obtained by pore sampling are digested according to the national standard GB / T 14506.30-2010 "Chemical analysis methods of silicate rocks - Part 30: Determination of 44 elements".

3. The method for in-situ collaborative development of coal-rock-sandstone type uranium ore according to claim 1, characterized in that: In step 2, the thickness a of the coal seam and sandstone layer is taken as 2 m, and the coal rock type and sandstone type uranium deposits with uranium contents in the coal ash and sandstone higher than 1000 μg / g and 0.01% respectively are the research objects.

4. The method for in-situ collaborative development of coal-rock-sandstone type uranium ore according to claim 1, characterized in that: In step three, the mineral composition of coal and sandstone is detected using an X-ray diffractometer and a scanning electron microscope energy dispersive spectrometer.

5. The method for in-situ collaborative development of coal-rock-sandstone type uranium ore according to claim 1, characterized in that: The specific methods in step 4 include: 4.

1. Weigh 2g of 200-mesh gasified coal ash or sandstone sample into a 100mL centrifuge tube, add 60mL of 1mol / L magnesium chloride solution, and place in an oscillating box at 200r / min and 25°C for reaction for 1h; the supernatant in the centrifuge tube is separated by centrifugation at 4000r / min for 5-10min, and the supernatant is in an exchangeable state. The residue at the bottom, i.e., residue I, is dried at 90°C to constant weight; 4.

2. Add 60 mL of 1 mol / L sodium acetate solution to the residue I, adjust the pH to 5 with acetic acid, place in an oscillating box at 200 r / min and 25°C for 8 hours, and the supernatant after centrifugation is in a carbonate state. The bottom residue, i.e., residue II, is dried at 90°C to constant weight; 4.

3. Add 60 mL of 0.04 mol / L hydroxylamine hydrochloride solution prepared with 25% acetic acid to the residue II, place in an oscillating box at 200 r / min and 95° C. for 4 h, and after centrifugation, the supernatant is in the state of iron and manganese oxides, and the residue at the bottom, i.e., the residue III, is dried at 90° C. to constant weight; 4.

4. Add 10 mL of 0.02 mol / L nitric acid and 30 mL of 30% hydrogen peroxide solution to the residue III, adjust the pH to 2 with nitric acid, and place in an oscillating box at 200 r / min and 85°C for reaction for 5 hours; After cooling, add 20 mL of 1 mol / L ammonium acetate solution prepared with 20% nitric acid solution, place in an oscillating box at 200 r / min and 25°C to react for 0.5 h, centrifuge, and the supernatant is organic, and the bottom residue, i.e., residue IV, is dried at 90°C to constant weight; 4.

5. Since the gasified coal ash has an amorphous glass phase after high-temperature combustion, in order to more accurately determine the occurrence state of uranium in the gasified coal ash, the gasified coal ash sample needs to be further dissolved into a glass phase and a residue state after step 4.4; By adding 40 mL of concentrated hydrofluoric acid, placing it in an oscillating box at 200 r / min and 85°C for 2 hours, the supernatant after centrifugation is in a glass phase, and its components include aluminosilicates. The bottom residue, namely residue IV, is dried at 90°C to constant weight. This step is not required for sandstone; 4.

6. According to the national standard GB / T 14506.30-2010 "Chemical analysis methods of silicate rocks - Part 30: Determination of 44 elements", the residue IV is digested and the obtained digestion solution is in the residue state; 4.

7. The content of strategic key metal uranium in exchangeable, carbonate, iron-manganese oxide, organic and residual states is tested by inductively coupled plasma mass spectrometry.

6. The method for in-situ collaborative development of coal-rock-sandstone type uranium ore according to claim 1, characterized in that: The specific reaction mechanism in step 7 is as follows: CO2+H2O=H2CO3 2UO2+O2=2UO3 <h2 style=";text-align:left;direction:ltr">UO3+2HCO3<h2 style=";text-align:left;direction:ltr"> - <h2 style=";text-align:left;direction:ltr"> (UO2(CO3)2)<h2 style=";text-align:left;direction:ltr"> 2- <h2 style=";text-align:left;direction:ltr"> +H2O [UO2(CO3)2] 2- +HCO3 - =[UO2(CO3)3] 4- +H + 。

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