Alkaline argillaceous sandstone type uranium ore heap leaching treatment method

Abstract

The invention belongs to the field of uranium ore treatment, and particularly relates to an alkaline argillaceous sandstone type uranium ore dump leaching treatment method which comprises the following steps: crushing alkaline argillaceous sandstone type uranium ore to obtain fine ore; mixing the fine crushed ore with an alkaline component and a curing aid, and curing; then carrying out roasting treatment at the temperature of 250 to 400 DEG C; an alkaline aqueous solution is adopted as a cooling medium to conduct spraying cold quenching on the roasted product, and pretreated ore is obtained; the curing auxiliary agent is a component with oxidability; and heaping the pretreated ore, and then carrying out alkaline leaching treatment by adopting an alkaline leaching agent. Through combination of curing-roasting and cold quenching, the physical and chemical structure can be optimized, the problems of poor permeability, liquid accumulation and the like of fine-grained alkaline argillaceous sandstone type uranium ore can be solved, and the leaching effect of uranium can be improved.

Description

Technical Field

[0001] The invention belongs to the technical field of hydrometallurgy, and in particular relates to the field of uranium recovery in uranium mines. Background Art

[0002] Uranium production methods can be divided into stirring leaching, in-situ leaching and heap leaching, etc. These methods can be divided into acid method and alkaline method. Among them, for alkaline uranium ore, high-pressure alkaline leaching and heated alkaline leaching processes are generally used for treatment. For example, a certain uranium mine is an alkaline mud sandstone type uranium ore with a high carbonate content. The carbonate components are mainly calcite and dolomite. Its calcium content is 3-12%, an average of 7-8%, and its carbon dioxide content is 6-12%, with a maximum of 15.5%. If the acid method is used for leaching, the sulfuric acid consumption is high and it cannot be used in production; using the heated stirring alkaline leaching process, the leached pulp is separated by a plate and frame filter press for solid-liquid separation. This process has a large uranium leaching return difference and high production cost; using the conventional alkaline heap leaching process, due to the high mud content in the ore, the poor permeability of the ore pile, and the slow leaching reaction rate of the conventional alkaline heap leaching, the uranium leaching rate is low.

[0003] For similar alkaline uranium ores, Chang Xixin et al. published "A Study on an Enhanced Alkali Heap Leaching Process for Uranium Extraction", which adopts an alkali-mixed high-temperature maturation heap leaching process. Although the uranium leaching rate can reach more than 90%, the leaching tailings need to be mixed with alkali again and subjected to high-temperature maturation again, which makes it difficult to achieve industrialization. In addition, this method is affected by the permeability of the ore pile, the spraying intensity is low, and high heap leaching cannot be achieved; Zhang Xiaowen et al. published "A Study on a New Process for Uranium Extraction by Alkali Heap Leaching", which adopts an ore crushing-burning-pretreatment-heating-leaching process. Although the ore is roasted, the uranium leaching rate is only 82%, and the resource utilization rate is low; CN 115679134 A discloses a method for treating carbonaceous siliceous mudstone-type uranium ore, which is a uranium ore containing sulfur, organic matter and carbonate. The mineral type and physicochemical characteristics are quite different from those of alkaline mudstone-type uranium ore, and the technical solution is difficult to simply transfer. In addition, the mineral crushing particle size of its technical solution is large, which is difficult to further refine, and it is difficult to solve the problems of heap leaching osmotic pressure difference and easy liquid accumulation caused by mineral refinement. Moreover, its heap leaching height is low, and it is difficult to solve the problem of high heap leaching height further aggravating osmotic pressure degradation and liquid accumulation.

[0004] In summary, the existing uranium ore recovery scheme is difficult to adapt to the physical and chemical characteristics of alkaline mudstone sandstone uranium ore, and it is difficult to achieve efficient leaching of fine particles and high heap leaching height.

[0005] Purpose of the Invention

[0006] In view of the problem of lack of suitable processes for uranium recovery from alkaline argillaceous sandstone type uranium ore, the present invention aims to provide a heap leaching method for alkaline argillaceous sandstone type uranium ore, aiming to provide a method adapted to the physicochemical characteristics of alkaline argillaceous sandstone type uranium ore and improving the uranium leaching efficiency and effect therein.

[0007] The main characteristic of alkaline mudstone-type uranium ore is that the mineralization and alteration has the characteristics of a paragenetic mineral combination of albite-carbonation-hematite-chlorite, among which chlorite mainly exists in radial and foliated chlorite, and carbonation mainly exists in vein-like siderite and calcite filling the cracks. Therefore, the ore has high clay mineral content and high carbonate content, and solid-liquid separation is difficult during stirring leaching. During heap leaching, clay minerals absorb water and swell, and the permeability of the ore pile cannot meet the requirements.

[0008] In addition, theoretically, refining ore particles can improve the leaching effect, but practice shows that fine particles will greatly affect permeability during heap leaching, which can easily lead to liquid accumulation; in addition, high heap height will further affect osmotic pressure and liquid accumulation. Aiming at the leaching difficulties caused by the special physical and chemical characteristics of alkaline muddy sandstone uranium ore and the difficulty in achieving fine-grained high heap height leaching, the present invention provides the following solutions after in-depth research:

[0009] A heap leaching method for alkaline argillaceous sandstone type uranium ore, wherein the alkaline argillaceous sandstone type uranium ore is crushed to obtain finely crushed ore;

[0010] The finely crushed ore is mixed with an alkaline component and a aging aid and then slaked; then the ore is roasted at a temperature of 250 to 400°C; and an alkaline aqueous solution is used as a cooling medium to spray and quench the roasted product to obtain a pretreated ore;

[0011] The pretreated ore is piled up and then subjected to alkali leaching treatment using an alkali leaching agent.

[0012] In view of the problem that uranium is difficult to be efficiently recovered by alkaline leaching due to the physicochemical characteristics of alkaline mudstone-type uranium ore, and the problem that it is difficult to achieve leaching at a fine-grained high pile height, the present invention innovatively matures the mineral to be treated, the alkaline component, and the maturation aid in advance, and then directly performs insulation modification at the temperature, and further cooperates with the subsequent cold quenching of the alkaline aqueous solution, so that the physicochemical transformation in the mineral can be optimized, its microstructure can be optimized, and its microscopic active pathways can be exposed, so that the uranium recovery problem caused by the physicochemical characteristics of alkaline mudstone-type uranium ore can be effectively solved, and efficient leaching at a fine-grained and high pile height can be achieved.

[0013] In the present invention, the alkaline mudstone-type uranium ore is a uranium ore containing high concentrations of clay and carbonate, and the uranium therein exists in the form of independent primary uranium minerals. The clay includes chlorite, kaolin and other clays. The carbonate components are mainly calcite, dolomite and the like.

[0014] The scheme of the present invention is applicable to the efficient treatment of the alkaline argillaceous sandstone type uranium ore with any content characteristics. For example, in the alkaline argillaceous sandstone type uranium ore, the clay content can be 1-10wt%, the calcium content can be 3-12wt%, the carbon dioxide content can be 6-16wt%; and the uranium content can be 0.1-0.5wt%.

[0015] In the present invention, the mineral to be processed can be crushed based on known processes.

[0016] In the present invention, the particle size of the finely crushed ore is below 1 mm, and the mass proportion of the ore below -0.15 mm is not less than 70wt%.

[0017] In the present invention, finer particle size theoretically increases the leaching effect, but practical studies have shown that finer particle size alkaline argillaceous sandstone uranium ore has poor permeability during the heap leaching stage and is prone to liquid accumulation on the surface of the ore heap, especially in the case of a precursor with a high heap height, where the poor permeability and liquid accumulation problems are more prominent. However, the combination of aging-roasting and cold quenching described in the present invention can optimize the physical and chemical structure, solve the problems of poor permeability and liquid accumulation in fine-grained alkaline argillaceous sandstone uranium ore, and improve the uranium leaching effect.

[0018] In the present invention, the alkali-maturing aid assisted maturation, roasting modification and alkaline system spraying and cold quenching treatment processes are combined for the mineral, and further coordinated with the joint control of parameters such as the maturation composition and the roasting temperature, so that the physicochemical structure of the alkaline argillaceous sandstone type uranium ore can be optimized, thereby helping to improve its alkaline leaching effect.

[0019] In the present invention, the alkaline component includes at least one of alkali metal carbonate and bicarbonate; preferably includes sodium carbonate and sodium bicarbonate, and more preferably includes sodium carbonate and sodium bicarbonate in a weight ratio of 3 to 5:1 to 2.

[0020] In the present invention, the aging aid includes at least one of permanganate, manganese dioxide, hypochlorite, and hydrogen peroxide; and may further include at least one of potassium permanganate, manganese dioxide, and sodium chlorate.

[0021] In the present invention, the alkaline component is 3-10wt% of the weight of the finely crushed ore; the aging aid is 0.05-0.2% of the weight of the finely crushed ore; and the mixing water added in the mixing stage is 15-20% of the weight of the finely crushed ore.

[0022] In the present invention, the temperature in the mixing and aging stages is 15 to 45°C.

[0023] In the present invention, the aging time is 10 hours or longer, and further 24 to 48 hours.

[0024] In the present invention, the roasting stage is carried out in a rotary kiln.

[0025] Preferably, the inlet temperature is controlled at 150-200°C, the temperature inside the kiln is 280-400°C, and the outlet temperature is 250-330°C.

[0026] Preferably, the calcination time is 10 to 50 minutes, and further can be 20 to 30 minutes.

[0027] In the present invention, after the roasted material is discharged, the alkaline aqueous solution is sprayed into the roasted material while it is still hot to perform cold quenching modification treatment.

[0028] In the present invention, the alkaline aqueous solution is an aqueous solution in which an alkaline solute is dissolved; wherein the alkaline solute includes at least one of sodium carbonate, sodium hydroxide and sodium bicarbonate.

[0029] Preferably, the concentration of the alkaline solute in the alkaline aqueous solution is 0.5-10 g / L.

[0030] Preferably, the initial temperature of the alkaline aqueous solution is below 50°C.

[0031] Preferably, the alkaline aqueous solution is 7-10% of the mineral content.

[0032] Preferably, the temperature of the ore after quenching is controlled at 30-50°C.

[0033] In the present invention, the physicochemical characteristics of the mineral can be optimized through the combined process of aging-roasting-quenching and the combined control of conditions, so that the physicochemical characteristics of the modified pretreated ore can be improved, and the alkaline leaching effect can be improved, for example, the leaching problem of fine particles and high pile height can be solved.

[0034] In the present invention, the pretreated ore can be subjected to heap alkali leaching treatment based on conventional means.

[0035] In the present invention, the pile height can reach 6 to 8 meters. The process described in the present invention can achieve efficient leaching under high pile conditions, so that on the premise of obtaining excellent leaching effect, the processing cost can be significantly reduced.

[0036] The alkaline leaching agent selected in the alkaline leaching stage is an aqueous solution in which at least one alkaline solute selected from sodium carbonate and sodium bicarbonate is dissolved; preferably, it is an aqueous solution in which sodium carbonate and sodium bicarbonate are dissolved; further preferably, the weight ratio of sodium carbonate to sodium bicarbonate is 3-5:0.5-1.

[0037] Preferably, the concentration of the solute in the alkaline leaching agent is 3 to 10 g / L; further preferably, 3.5 to 6 g / L.

[0038] In the present invention, the ore heap after the heap is built is sprayed with an alkali leaching agent to carry out leaching, the leaching liquid is sent to an adsorption system, and the adsorption tail liquid is returned to prepare an alkali leaching agent to circulate and participate in the alkali leaching process;

[0039] When the uranium concentration in the leaching solution is lower than 100 mg / L, spraying is stopped and the heap leaching quasi-tailings are matured again with concentrated alkali; the matured quasi-tailings are sprayed with clean water or adsorbed tailings, and when the uranium concentration in the leaching solution is lower than 20 mg / L, spraying is stopped and the leaching solution obtained by spraying is returned to the next heap to prepare the alkaline leaching agent.

[0040] In the present invention, the spray intensity is 50 to 200 L / (m 2 ·h), preferably 100 to 200 L / (m 2 h), continuous spraying;

[0041] When the uranium concentration of the leaching solution is lower than 100 mg / L, spraying is stopped and the heap leaching tailings are matured again with concentrated alkali after the heap is left empty for 3 to 5 days.

[0042] In the present invention, the concentrated alkali is a mixed solution of 100-200 g / L sodium carbonate and 30-50 g / L sodium bicarbonate; the spraying amount is 5-10% of the mass of the ore, and after the spraying is completed, the ore pile is matured for 5-7 days.

[0043] Beneficial Effects

[0044] The present invention innovatively matures the to-be-treated mineral, alkaline components and a maturing aid in advance, and then directly performs heat preservation modification at the temperature, and further cooperates with subsequent cold quenching of an alkaline aqueous solution, so that the physicochemical transformation in the mineral can be optimized, its microstructure can be optimized, and its microscopic active pathways can be exposed. In this way, the uranium recovery problem caused by the physicochemical characteristics of alkaline mudstone sandstone type uranium ore can be unexpectedly solved, and the uranium recovery efficiency and effect can be significantly improved, especially the leaching effect under fine particles and high pile height can be improved.

[0045] The present invention achieves a technical breakthrough in heap leaching of alkaline mudstone-type uranium ore, which is mainly reflected in the improvement of the ore pile height, the enhancement of the ore pile permeability, the lower leaching slag grade and the improvement of the leaching rate, which is of great significance for promoting the industrial production and application of heap leaching of uranium ore. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 Example 1: Process flow chart of heap leaching of alkaline mudstone-type uranium ore. DETAILED DESCRIPTION

[0047] According to the operation steps and related parameters disclosed in the present invention, those skilled in the art can achieve the purpose of the present invention according to the operation principle of the present method, without being limited to the use of the equipment itself and its use method used in the specific embodiment.

[0048] The present invention discloses an industrial production method for high recovery rate heap leaching of alkaline muddy sandstone type uranium ore, which comprises the following steps:

[0049] (1) crushing alkaline argillaceous sandstone-type uranium ore to -1 mm, of which the mass of ore below -0.15 mm accounts for no less than 70%;

[0050] (2) adding sodium carbonate, sodium bicarbonate, a aging aid and water to the finely crushed ore obtained in step (1) and mixing them uniformly, wherein the amount of sodium carbonate added is 3-5%, the amount of sodium bicarbonate is 1-2%, the amount of potassium permanganate, a aging aid, is 0.05-0.2%, and the amount of water is 15-20% based on the mass of the ore, and then aging is performed after mixing them uniformly;

[0051] (3) calcining the material after aging in step (2) at a high temperature of 250-400° C., wherein the inlet temperature is controlled to be 150-200° C., the temperature in the kiln is 280-400° C., and the outlet temperature is 250-330° C.;

[0052] (4) transferring the ore roasted in step (3) into a rotary cooler and spraying a dilute alkali solution for cooling;

[0053] (5) transferring the ore after cooling in step (4) to a stockpile for heaping;

[0054] (6) spray leaching the ore pile in step (5), send the leaching solution to the adsorption system, return the adsorbed tailings to prepare the leaching agent, and stop spraying when the uranium concentration in the leaching solution is lower than 100 mg / L, and perform aging treatment on the heap leaching tailings again with concentrated alkali;

[0055] (7) The quasi-tailings after the re-ripening in step (6) are sprayed with clean water or tailings liquid. When the uranium concentration in the leaching solution is lower than 20 mg / L, the spraying is stopped and the leaching solution obtained by the spraying is returned to the next pile for preparing the leaching agent.

[0056] The step (1) is specifically as follows: the raw ore is crushed by a three-stage two-closed-circuit crushing system consisting of a gyratory crusher or a jaw crusher, a cone crusher, a high-pressure roller mill, a vibrating screen and a belt conveyor. In order to prevent the material from clogging the screen and improve the screening efficiency of fine-grained ore, both vibrating screens of the two-stage screening system use a relaxation screen, and the screen material is a high-elastic polyurethane. In order to prevent sticky materials such as fine mud from adhering to the inner wall of the feeder and the cone crusher, a bar feeder is used. The material under the sieve of the bar feeder is combined with the discharge of the jaw crusher and enters the first screening system for pre-screening. The first relaxation screen consists of two layers of screens, the aperture of the upper screen is 30 mm, and the aperture of the lower screen is 1 mm. The underscreen material is combined with the underscreen material of the second stage and sent to the fine crushing bin. The material on the first screen enters the cone crusher, and the material after cone crushing is combined with the material after fine crushing by the high-pressure roller mill and enters the second screening system. The material on the second screen enters the high-pressure roller mill. The aperture of the upper screen of the second relaxation screen is -1mm, and the aperture of the lower screen is 1mm. After fine crushing, the particle size of the ore is not more than 1mm, of which the proportion below -0.15 is not less than 70%.

[0057] The invention provides industrial control equipment and method for ultra-fine crushing of this type of uranium ore, which can crush the ore to a particle size not greater than 1 mm, of which the particle size below -0.15 accounts for not less than 70%, again breaking the minimum value of the existing uranium ore particle size in the leaching pile, and achieving the purpose of fully dissociating the target mineral.

[0058] The step (2) is specifically as follows: using a drum granulator to evenly mix the finely crushed ore with sodium carbonate, sodium bicarbonate, a maturation aid and water, the material stays in the drum granulator for 3 to 5 minutes, and the evenly mixed ore is matured at room temperature for 24 to 48 hours.

[0059] The step (3) is specifically as follows: sending the matured material to a rotary kiln for roasting, using coal gas or natural gas as the fuel for roasting, the fuel is directly injected and burned in the furnace, the rotary kiln inlet temperature is controlled to be 150-180°C, the roasting temperature in the kiln is 250-400°C, the outlet temperature is 250-350°C, and the material is roasted in the rotary kiln for 20-30 minutes.

[0060] In the present invention, the alkali-ripening aid is used for high-temperature roasting after assisted aging, which can promote the cracking of minerals. In addition, it can also optimize the physical and chemical properties of minerals, improve the permeability of subsequent ore pile spraying, and prevent the problem of liquid accumulation on the surface of the ore pile caused by the decrease in permeability of the ore pile directly.

[0061] The step (4) is specifically as follows: the roasted ore is sent to a rotary cooler and sprayed with dilute alkali solution for cooling, wherein the amount of alkali solution used is 7-10% of the mass of the ore, and the dilute alkali solution is an adsorption tail liquid or is composed of a solution with a sodium carbonate concentration of 3-5 g / L and a sodium bicarbonate concentration of 0.5-1 g / L. After cooling, the temperature of the ore is 30-50°C.

[0062] The calcined material is sprayed with dilute alkali solution in a rotary drum cooler for rapid cooling, which can further optimize the physical and chemical characteristics of the mineral, facilitate the dissolution of the target mineral, and further accelerate the subsequent leaching speed and efficiency.

[0063] The step (5) is specifically as follows: the cooled material is piled up. Since the ore is treated with alkali mixing and high temperature roasting, the physical properties of the ore itself are changed, and it is not easy to become muddy during the heap leaching process. Compared with the conventional treatment method of heaping 2 to 3 meters, the pile height can reach 6 to 8 meters.

[0064] The step (6) is specifically as follows: spraying with a solution having a sodium carbonate concentration of 3 to 5 g / L and a sodium bicarbonate concentration of 0.5 to 1 g / L, with a spraying intensity of 50 to 200 L / (m 2 ·h), preferably 100 to 200 L / (m 2 h), continuous spraying. When the uranium concentration of the leaching solution is lower than 100 mg / L, stop spraying, leave the pile empty for 3 to 5 days, and then spray a solution with a sodium carbonate concentration of 100 to 200 g / L and a sodium bicarbonate concentration of 30 to 50 g / L for maturation. The spraying amount is 5 to 10% of the ore mass. After the spraying is completed, the ore pile is matured for 5 to 7 days.

[0065] The step (7) is specifically as follows: spray leaching the matured quasi-tailings, wherein the leaching agent preferably adsorbs the tailings, and when the uranium concentration in the leaching solution is lower than 20 mg / L, the spraying is stopped.

[0066] In the present invention, the alkaline mudstone-type uranium ore is a uranium ore containing high concentrations of clay and carbonates, and the uranium therein exists in the form of independent primary uranium minerals. The clay includes chlorite, kaolin and other clays. The carbonate components are mainly calcite, dolomite and the like. In the following case, the alkaline mudstone-type uranium ore has a clay content of 4-7wt%, a calcium content of 6-7wt%, a carbon dioxide content of 8-10wt%; and a uranium content of 0.1-0.3wt%.

[0067] Example 1

[0068] The uranium grade of an alkaline mudstone uranium mine is 0.2%. The operation is carried out according to the following steps:

[0069] (1) After coarse crushing by jaw crusher, medium crushing by cone crusher and fine crushing by high pressure roller mill, the particle size of ore is less than -1mm, of which the particle size below -0.15mm accounts for 75.3%.

[0070] (2) Using a cylindrical granulator, the finely crushed ore is evenly mixed with sodium carbonate, sodium bicarbonate, potassium permanganate and water. The amount of sodium carbonate added is 4%, sodium bicarbonate is 1.5%, potassium permanganate is 0.1%, and water is 15% based on the mass of the ore. The material stays in the granulator for 4 minutes. The evenly mixed material is matured at room temperature for 36 hours.

[0071] (3) The matured material is sent to a rotary kiln for roasting, wherein the inlet temperature is 180°C, the roasting temperature is 300°C, the outlet temperature is 270°C, and the material is roasted in the rotary kiln for 25 minutes.

[0072] (4) The roasted material is sent to a rotary cooler and sprayed with a dilute alkali solution for cooling (the temperature of the roasted material in the initial stage of spraying is above 200°C). The dilute alkali solution is an adsorption tail liquid with an alkali concentration of 5 to 10 g / L. The spraying amount is 8% of the ore mass. The ore temperature after cooling is 35°C.

[0073] (5) The calcined and cooled materials are piled up to a height of 7m.

[0074] (6) Spray leaching of the piled ore using a solution of 5 g / L sodium carbonate and 1 g / L sodium bicarbonate at a spray intensity of 150 L / (m 2 h), continuous spraying. When the uranium concentration of the leaching solution is lower than 100 mg / L, the spraying is stopped. The spraying is carried out for 4 days in total. Then, after 5 days of empty pile, a solution with a sodium carbonate concentration of 200 g / L and a sodium bicarbonate concentration of 50 g / L is sprayed for maturation. The spraying amount is 10% of the mass of the ore. After the spraying is completed, the ore pile is matured for 7 days, and the matured quasi-tailings are sprayed and leached. The leaching agent absorbs the tailings. When the uranium concentration in the leaching solution is lower than 20 mg / L, the spraying is stopped. The spraying time is 3 days.

[0075] The total spraying time was 19 days, the uranium grade in the leached residue was 0.008%, and the uranium leaching rate was 96.0%.

[0076] The uranium in Example 1 was recovered by various methods of the prior art, and the comparison with Example 1 is shown in the following table:

[0077] Comparative Example 1

[0078] The uranium ore in Example 1 was finely ground to -100 mesh (accounting for more than 90%), and 4% sodium carbonate, 1.5% sodium bicarbonate, and 0.1% potassium permanganate were added based on the mass of the ore. The liquid-to-solid volume mass ratio was 2L / kg, the leaching temperature was 90°C, the leaching time was 18h, and the leached pulp was washed by plate and frame filter press.

[0079] Comparative Example 2

[0080] The uranium ore in Example 1 was crushed to -5 mm (if it was crushed to -1 mm and directly heap leached, the permeability would be extremely poor), and a solution with a sodium carbonate concentration of 5 g / L and a sodium bicarbonate concentration of 1 g / L was used for spraying, and the spraying intensity was 20 to 50 L / (m 2 h), continuous spraying, turning the pile twice during the process, and stopping spraying when the uranium concentration of the leaching solution is <20 mg / L for 3 consecutive days.

[0081] Comparative Example 3

[0082] Compared with Example 1, the only difference is that the crushed minerals in step 1 are pre-processed in step 3, the product is then processed in step 2, and the processed product is then processed in step 4 and subsequent processes. Other operations and parameters are the same as in Example 1.

[0083] Comparative Example 4

[0084] Compared with Example 1, the only difference is that, in step 2, potassium permanganate is lacking, and other operations and parameters are the same as in Example 1.

[0085] Comparative Example 5

[0086] Compared with Example 1, the only difference is that the roasting conditions in step 3 are changed, specifically, the roasting temperature is controlled to 200° C., and the material is roasted in the rotary kiln for 25 minutes. Other operations and parameters are the same as in Example 1.

[0087] Comparative Example 6

[0088] Compared with Example 1, the only difference is that the roasting conditions in step 3 are changed, specifically, the inlet temperature is 380°C, the roasting temperature is 500°C, the outlet temperature is 470°C, the material is roasted in the rotary kiln for 25 minutes, and the other operations and parameters are the same as in Example 1.

[0089] Comparative Example 7

[0090] Compared with Example 1, the only difference is that in step 4, no cold quenching treatment is performed, but the product of step 3 is cooled to room temperature in the furnace after being roasted and then transported to step 4 to participate in the treatment of step 4. Other operations and parameters are the same as in Example 1.

[0091] The results of Example 1 and Comparison 1 to 7 are shown in Table 1 below;

[0092] Table 1

[0093]

[0094]

[0095] Example 2

[0096] The uranium grade of an alkaline mudstone uranium mine is 0.15%. The operation is carried out according to the following steps:

[0097] (1) After coarse crushing by jaw crusher, medium crushing by cone crusher and fine crushing by high pressure roller mill, the particle size of ore is less than -1mm, of which the particle size below -0.15mm accounts for 78.1%.

[0098] (2) Using a cylindrical granulator, the finely crushed ore is evenly mixed with sodium carbonate, sodium bicarbonate, potassium permanganate and water. The amount of sodium carbonate added is 3.5%, sodium bicarbonate is 1%, potassium permanganate is 0.1%, and water is 16% based on the mass of the ore. The material stays in the granulator for 5 minutes. The evenly mixed material is matured at room temperature for 36 hours.

[0099] (3) The aging material is sent to a rotary kiln for roasting, wherein the roasting temperature (furnace temperature) is 280° C. and the material is roasted in the rotary kiln for 30 minutes.

[0100] (4) The roasted material is sent to a rotary cooler and sprayed with a dilute alkali solution for cooling. The dilute alkali solution is the adsorption tail liquid, and the spraying amount is 8% of the ore mass. The ore temperature after cooling is 35°C.

[0101] (5) The calcined and cooled materials are piled up to a height of 6.5 m.

[0102] (6) Spray leaching of the ore after heaping, using a solution of 5 g / L sodium carbonate and 1 g / L sodium bicarbonate, with a spray intensity of 120 L / (m 2 h), continuous spraying. When the uranium concentration of the leaching solution is lower than 100 mg / L, stop spraying. Spraying for 5 days in total, then after 5 days of empty pile, spray 150 g / L sodium carbonate and 50 g / L sodium bicarbonate solution for maturation. The spraying amount is 10% of the ore mass. After the spraying is completed, the ore pile is matured for 7 days, and the matured quasi-tailings are sprayed and leached. The leaching agent absorbs the tailings. When the uranium concentration in the leaching solution is lower than 20 mg / L, stop spraying. The spraying time is 3 days.

[0103] The total spraying time was 20 days, the uranium grade in the leached residue was 0.007%, and the uranium leaching rate was 95.3%.

[0104] Example 3

[0105] The uranium grade of an alkaline mudstone uranium mine is 0.25%. The operation is carried out according to the following steps:

[0106] (1) After coarse crushing by jaw crusher, medium crushing by cone crusher and fine crushing by high pressure roller mill, the particle size of the ore is less than -1 mm, of which the particle size below -0.15 mm accounts for 74.9%.

[0107] (2) Using a cylindrical granulator, the finely crushed ore is evenly mixed with sodium carbonate, sodium bicarbonate, potassium permanganate and water. The amount of sodium carbonate added is 3.5%, sodium bicarbonate is 1%, potassium permanganate is 0.1%, and water is 16% based on the mass of the ore. The material stays in the granulator for 5 minutes. The evenly mixed material is matured at room temperature for 36 hours.

[0108] (3) The matured material is sent to a rotary kiln for roasting, wherein the roasting temperature is 350° C. and the material is roasted in the rotary kiln for 20 minutes.

[0109] (4) The roasted material is sent to a rotary cooler and sprayed with a dilute alkali solution for cooling. The dilute alkali solution is the adsorption tail liquid, and the spraying amount is 8% of the ore mass. The ore temperature after cooling is 35°C.

[0110] (5) The calcined and cooled materials are piled up to a height of 8m.

[0111] (6) Spray leaching of the piled ore using a solution of 5 g / L sodium carbonate and 1 g / L sodium bicarbonate at a spray intensity of 150 L / (m 2 h), continuous spraying. When the uranium concentration of the leaching solution is lower than 100 mg / L, stop spraying. Spraying for 5 days in total, then after 5 days of empty pile, spray 150 g / L sodium carbonate and 50 g / L sodium bicarbonate solution for maturation. The spraying amount is 10% of the ore mass. After the spraying is completed, the ore pile is matured for 7 days, and the matured quasi-tailings are sprayed and leached. The leaching agent absorbs the tailings. When the uranium concentration in the leaching solution is lower than 20 mg / L, stop spraying. The spraying time is 3 days.

[0112] The total spraying time was 20 days, the uranium grade in the leached residue was 0.009%, and the uranium leaching rate was 96.4%.

Claims

1. A heap leaching method for alkaline argillaceous sandstone type uranium ore, characterized in that: The alkaline muddy sandstone type uranium ore is crushed to obtain finely crushed ore; The finely crushed ore is mixed with alkaline components and a slaking aid and then slaking is performed; then the slaking is performed at a temperature of 250 to 400°C; Then, an alkaline aqueous solution is used as a cooling medium to spray and quench the roasted product to obtain a pretreated ore; the aging aid is an oxidizing component; The pretreated ore is piled up and then subjected to alkali leaching treatment using an alkali leaching agent.

2. The heap leaching method for alkaline argillaceous sandstone type uranium ore according to claim 1, characterized in that: Alkaline argillaceous sandstone-type uranium ores are uranium ores containing clay and carbonate, and the uranium in them exists in the form of independent primary uranium minerals; Preferably, the particle size of the finely crushed ore is below -1 mm, and the mass proportion of the ore below -0.15 mm is not less than 70wt%.

3. The heap leaching method for alkaline argillaceous sandstone type uranium ore according to claim 1, characterized in that: The alkaline component includes at least one of alkali metal carbonate and bicarbonate; preferably includes sodium carbonate and sodium bicarbonate, and more preferably includes sodium carbonate and sodium bicarbonate in a weight ratio of 3 to 5:1 to 2; Preferably, the aging aid comprises at least one of permanganate, manganese dioxide, hypochlorite and hydrogen peroxide; Preferably, the alkaline component is 3-10wt.% of the weight of the finely crushed ore; the slaking aid is 0.05-0.2% of the weight of the finely crushed ore; the mixing water added in the mixing stage is 15-20% of the weight of the finely crushed ore; Preferably, the temperature during the mixing and aging stages is 15 to 45°C; Preferably, the aging time is 10 hours or longer, and further 24 to 48 hours.

4. The heap leaching method for alkaline argillaceous sandstone type uranium ore according to claim 1, characterized in that: The roasting stage is carried out in a rotary kiln; Preferably, the inlet temperature is controlled to be 150-200°C, the temperature in the kiln is 280-400°C, and the outlet temperature is 250-330°C; Preferably, the calcination time is 10 to 50 minutes, and further can be 20 to 30 minutes.

5. The heap leaching method for alkaline argillaceous sandstone type uranium ore according to claim 1, characterized in that: The alkaline aqueous solution is an aqueous solution in which an alkaline solute is dissolved; wherein the alkaline solute includes at least one of sodium carbonate, sodium hydroxide, and sodium bicarbonate; Preferably, the concentration of the alkaline solute in the alkaline aqueous solution is 0.5 to 10 g / L; Preferably, the starting temperature of the alkaline aqueous solution is below 50°C; Preferably, the alkaline aqueous solution is 7-10% of the mineral content; Preferably, the temperature of the ore after quenching is controlled at 30-50°C.

6. The heap leaching method for alkaline argillaceous sandstone type uranium ore according to claim 1, characterized in that: The pile height is 6 to 8 meters.

7. The heap leaching method for alkaline argillaceous sandstone type uranium ore according to claim 1, characterized in that: The alkaline leaching agent selected in the alkaline leaching stage is an aqueous solution containing at least one alkaline solute selected from sodium carbonate and sodium bicarbonate; preferably, an aqueous solution containing sodium carbonate and sodium bicarbonate; more preferably, the weight ratio of sodium carbonate to sodium bicarbonate is 3-5:0.5-1; Preferably, the concentration of the solute in the alkaline leaching agent is 3 to 10 g / L; further preferably, 3.5 to 6 g / L.

8. The heap leaching method for alkaline argillaceous sandstone type uranium ore according to claim 1, 6 or 7, characterized in that: The ore heap is sprayed with an alkali leaching agent to carry out leaching, and the leaching liquid is sent to the adsorption system. The adsorption tail liquid is returned to the preparation of the alkali leaching agent to participate in the alkali leaching process; When the uranium concentration in the leaching solution is lower than 100 mg / L, spraying is stopped and the heap leaching quasi-tailings are matured again with concentrated alkali; the matured quasi-tailings are sprayed with clean water or adsorbed tailings, and when the uranium concentration in the leaching solution is lower than 20 mg / L, spraying is stopped and the leaching solution obtained by spraying is returned to the next heap to prepare the alkaline leaching agent.

9. The heap leaching method for alkaline argillaceous sandstone type uranium ore according to claim 8, characterized in that: The spray intensity is 50~200L / (m 2 ·h), preferably 100 to 200 L / (m 2 h), continuous spraying; When the uranium concentration of the leaching solution is lower than 100 mg / L, spraying is stopped and the heap leaching tailings are matured again with concentrated alkali after the heap is left empty for 3 to 5 days.

10. The heap leaching method for alkaline argillaceous sandstone type uranium ore according to claim 9, characterized in that: The concentrated alkali is a mixed solution of sodium carbonate with a concentration of 100-200 g / L and sodium bicarbonate with a concentration of 30-50 g / L; the spraying amount is 5-10% of the mass of the ore. After the spraying is completed, the ore pile is matured for 5-7 days.

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