Method for extracting and separating rubidium and cesium from lepidolite ore by chlorination roasting

Abstract

The present invention discloses a method for extracting and separating rubidium and cesium from lepidolite ore by chlorination roasting. By using a specially added auxiliary agent and a composite chlorinating agent for roasting, and leaching the roasted ore with dilute sulfuric acid, there is no need for the process of removing calcium to purify the solution. A composite extraction system is utilized to simultaneously extract rubidium and cesium and then back-extract to separate rubidium and cesium. By adopting the method of the present invention, the technological process is simple and concise, the cost is low, the leaching recovery rates of rubidium and cesium are high, and large-scale industrial production can be realized.

Description

Technical Field

[0001] The present invention relates to a metallurgical method for rubidium mica concentrate, and particularly to a method for extracting and separating rubidium and cesium from rubidium mica ore by chlorination roasting. Background Art

[0002] Rubidium and cesium are associated homologous similar elements. Due to their extremely excellent photoelectric effect and special properties, they are widely used in modern high-tech fields such as phototubes, new energy, military industry, and medicine and health, and are important strategic metals. Because the chemical properties of rubidium and cesium elements are very active, they form few ores in nature and are called "typical rock-loving dispersed dilute alkali elements" due to the difficulty of extraction.

[0003] Rubidium mica ore contains muscovite, sericite, phlogopite, etc. It is the main carrier mineral of rubidium and cesium and is a key strategic mineral resource of great economic significance. Rubidium mica ore is a layered aluminosilicate mineral with a firm and stable mineral phase, belonging to the pegmatite mineral of the monoclinic system. Its crystal form is hexagonal, and intact crystals are relatively rare. It often forms flakes and fine scaly aggregates.

[0004] The initial extraction and utilization of rubidium mica ore was to heat and leach the calcined and pulverized concentrate with industrial hydrochloric acid, precipitate with stannous double salt, remove tin by hydrolysis, precipitate with acid oxalate, and recrystallize to obtain rubidium chloride.

[0005] The current methods for treating rubidium mica resources include calcium chloride chlorination roasting, removing calcium from the water-leached calcine and leachate with soda ash, and using the BAMBP extraction system to extract cesium first and then rubidium. Its main defects are: the process is complex and the process flow is long, the recovery rates of rubidium and cesium are low, the consumption of chemical auxiliary materials is large, the cost is high, and the emissions of tailings, calcium-removing slag, waste water, etc. are large.

[0006] CN202011120620.0 provides a method for short-process extraction of rubidium chloride from rubidium-rich brine. After adding alkali to precipitate copper, lead, zinc, and magnesium metal ion impurities, the pH value is controlled to be 13-14, and the t-BAMBP system is used to extract and separate rubidium. Then, rubidium is precipitated with stannous chloride and purified by recrystallization. This method does not mention the separation of rubidium and cesium and the recovery of cesium resources, and its extraction system does not include co-extractants, diluents, and key parameters of extraction and stripping. It cannot achieve high-purity rubidium chloride obtained by stripping, and further precipitation, recrystallization and other complex processes are required to process it into high-purity rubidium chloride.

[0007] CN110293002A discloses a precipitation flotation separation system for cesium and rubidium in an aqueous solution and its application. The precipitation flotation process is to add a precipitant, a collector and a foaming agent into an aqueous solution containing cesium ions and / or rubidium ions to react and precipitate the cesium ions and / or rubidium ions. The precipitant at least includes Prussian blue, and the collector and the foaming agent at least include cationic surfactants. The precipitated solid obtained from the reaction is collected through flotation separation treatment. This invention belongs to the flotation separation process, which is a physical separation process and cannot directly separate rubidium from cesium, nor can it directly obtain high-purity compound products.

[0008] CN106435180B discloses an extraction method for rubidium ions and cesium ions. A composite extractant composed of an acidic extractant and a phenol extractant is used to perform a first extraction treatment on a mixed solution containing rubidium ions and cesium ions to obtain a first organic phase and a first raffinate. Then, the first raffinate is subjected to a second extraction treatment to obtain a second organic phase and a second raffinate. An anti-extraction agent is used to perform an anti-extraction treatment on the first organic phase to obtain an anti-extraction solution containing cesium salt; and an anti-extraction agent is used to perform an anti-extraction treatment on the second organic phase to obtain an anti-extraction solution containing rubidium salt. This method is a step-by-step single-stage extraction of rubidium and cesium, and the pH value of the solution needs to be adjusted twice. In a conventional solution where the rubidium content is much higher than that of cesium, a large amount of rubidium will be simultaneously extracted during the extraction of cesium, and complete separation of cesium and rubidium cannot be achieved by single-stage extraction.

[0009] CN107475513B invented a method for leaching rubidium, potassium and aluminum from rubidium-containing mica ore. The rubidium-containing mica ore is mixed with concentrated sulfuric acid and then subjected to a ripening reaction to obtain a ripened material. The ripened material is subjected to reduction roasting to obtain roasted ore and flue gas. The roasted ore is leached with water to obtain a leaching solution containing rubidium and potassium and leaching residues. The leaching residues are leached with an alkaline aqueous solution to obtain a leaching solution containing rubidium, potassium and aluminum. The reaction activity of the sulfuric acid system in this invention method is poor and the water solubility is poor, which will lead to a low total recovery rate of rubidium, potassium and aluminum.

[0010] CN111996392A invented a method for extracting cesium and rubidium from lithium mica. The steps include leaching after roasting the concentrate with concentrated sulfuric acid and crystallization to obtain rubidium and cesium mixed alum, secondary leaching after calcination, and then obtaining cesium sulfate through primary extraction separation and rubidium sulfate through secondary extraction separation. This method requires multiple leaching and multiple extractions, with a complex process and difficult control.

[0011] How to find a relatively perfect method for extracting and separating rubidium and cesium from rubidium-containing mica ore, with a simple process flow, low cost, high leaching recovery rates of rubidium and cesium, and the ability to achieve large-scale industrial production, is a technical problem that those skilled in the art urgently need to solve. Summary of the Invention

[0012] The technical problem to be solved by the present invention is to provide a method for extracting and separating rubidium and cesium from lepidolite ore by chlorination roasting, which makes the process flow simple, the cost low, the leaching recovery rates of rubidium and cesium high, and large-scale industrial production can be realized.

[0013] To solve the above technical problem, the method for extracting and separating rubidium and cesium from lepidolite ore by chlorination roasting according to the present invention uses special additives and composite chlorinating agents for roasting, leaches the roasted ore with dilute sulfuric acid, does not require the process of removing calcium to purify the solution, and uses a composite extraction system to simultaneously extract rubidium and cesium and then back-extract to separate rubidium and cesium.

[0014] The method of the present invention comprises the following steps:

[0015] a. Using lepidolite concentrate as raw material, adding a composite chlorinating agent and a roasting additive, controlling the weight ratio of lepidolite concentrate∶composite chlorinating agent∶roasting additive to be 1∶0.1 - 0.5∶0.05 - 0.2, mixing evenly and loading into a rotary kiln for chlorination roasting, controlling the roasting temperature at 650 - 950 °C and the roasting time at 30 - 150 min to obtain a clinker roasted ore;

[0016] b. After cooling the obtained clinker roasted ore, performing 3 - 6 - stage countercurrent leaching with an acid leaching agent, controlling the leaching liquid - solid ratio at 1 - 4:1, the leaching time at 30 - 150 min, and the leaching temperature at room temperature or heated to obtain an acidic leaching solution containing rubidium and cesium;

[0017] c. Adjusting the pH value of the obtained acidic leaching solution containing rubidium and cesium to the range of 11 - 13 to obtain an alkaline leaching solution containing rubidium and cesium;

[0018] d. For the obtained alkaline leaching solution containing rubidium and cesium, simultaneously extracting rubidium and cesium, after washing the loaded organic phase, first back - extracting to obtain a rubidium chloride solution, and then back - extracting to obtain a cesium chloride solution.

[0019] The extraction of rubidium and cesium is a 3-6 stage countercurrent extraction. t-BAMBP is used as the extractant, alkoxy [calix4, calix6] crown ether or n-octanol is used as the co-extractant, and the diluent is one of xylene, sulfonated kerosene, and cyclohexane. The extraction system is configured according to the volume ratio of t-BAMBP∶co-extractant∶diluent of 10-30:0.1-10∶60-90, the phase ratio O / A = 1-3:1, the extraction time is 3 min, and the clarification time is 5 min; after the two phases are separated, the raffinate is recovered, and the rubidium-loaded organic phase is washed with deionized water, the phase ratio O / A = 5:1, the washing time is 5 min, and the washing stage is 3; the washed loaded organic phase is countercurrently stripped with 0.2M hydrochloric acid in 3-5 stages, the phase ratio O / A = 1-3:1, the stripping time is 5 min, and the clarification time is 5 min. After the two phases are separated, the stripping solution is evaporated and crystallized to obtain rubidium chloride; the residual organic phase after extracting rubidium is countercurrently stripped with 1.5-2.5M hydrochloric acid in 2 stages, the phase ratio O / A = 5:1, the stripping time is 4 min, and the clarification time is 4 min. After the two phases are separated, the stripping solution is evaporated and crystallized to obtain cesium chloride.

[0020] The composite chlorinating agent in the roasting process is a mixture of calcium chloride, sodium chloride, and potassium chloride. The conventional mass ratio of calcium chloride, sodium chloride, and potassium chloride is 3∶1∶1, and the roasting aid is carbon powder.

[0021] The leaching agent in the roasting sand leaching process is dilute sulfuric acid with a concentration of 0.1-2M.

[0022] Use one or more of sodium hydroxide, calcium hydroxide, and potassium hydroxide to adjust the pH value range of the acidic leaching solution containing rubidium and cesium to 11-13 to obtain an alkaline leaching solution containing rubidium and cesium.

[0023] Using the method of the present invention, at a certain temperature condition, the rubidium and cesium in the lattice of the rubidium mica concentrate are converted into corresponding chlorides by the chlorination interaction reaction of the chlorinating agent, and the separation and extraction are realized by a dissolution method. The present invention adopts a composite chlorinating agent roasting process with a specially added aid, leaches the roasting sand with dilute sulfuric acid, and does not need to go through the complex process of traditional calcium removal and solution purification. By using a new composite extraction system, rubidium and cesium are synchronously extracted and then selectively separated by controlling the stripping parameters, which can greatly reduce the manufacturing cost.

[0024] In step a of the present invention, a mixed chlorinating agent composed of calcium chloride, sodium chloride, and potassium chloride is used, which can improve the defects of poor lattice matching degree and weak reaction activity brought by a single chlorinating agent. Carbon powder is used as the roasting aid, which can form a reducing atmosphere in the roasting process to promote the bonding reaction of rubidium and cesium. The local combustion reaction participated by the aid can not only reduce the roasting temperature and save energy, but also improve the leaching recovery rate of rubidium and cesium.

[0025] In step b of the present invention, the obtained clinker calcine is leached with dilute sulfuric acid. Different from the traditional water leaching method, the dilute sulfuric acid leaching process utilizes the principle of insolubility of calcium sulfate, which can inhibit a large amount of calcium ions from entering the solution, eliminating the step of adding soda ash to remove calcium and purify the solution, saving a large amount of auxiliary material consumption, avoiding the production of a large amount of difficult-to-treat calcium removal slag, and effectively improving the leaching efficiency of the calcine, which is beneficial to rubidium and cesium concentration.

[0026] In step d of the present invention, t-BAMBP with good selectivity for rubidium and cesium and a large separation coefficient is used as the extractant. To improve the extraction rate and reduce the ineffective extraction cycle, a small-ring mixed calixarene crown ether and n-octanol are selected as the co-extractants. t-BAMBP, that is, 4-tert-butyl-2-(α-methylbenzyl)phenol, is a phenolic alcohol extractant, which can undergo substitution displacement with rubidium and cesium ions in the solution. The small-ring mixed calixarene crown ether forms a cavity chelation effect with rubidium and cesium ions. N-octanol is a good organic dispersant that is insoluble in water, which can reduce the polymerization behavior of high-molecular extractants and significantly improve their extraction performance. The different working principles of the extractant and the co-extractant in the process of extracting rubidium and cesium can form a special synergistic effect.

[0027] The present invention synchronously extracts rubidium and cesium and controls the stripping parameters to separate rubidium and cesium step by step, which can effectively simplify the extraction process, reduce the amount of ineffective extraction cycle, save chemical auxiliary materials, and reduce waste discharge.

[0028] Compared with the prior art, the present invention takes rubidium mica concentrate as the object, undergoes chemical reactions under the action of additives through composite chloride roasting, and then leaches with dilute sulfuric acid. It does not need to go through the complex process of adding soda ash to remove calcium and purify the solution in the traditional way. The solvent extraction method synchronously extracts rubidium and cesium, and high-purity rubidium and cesium products can be directly obtained by stripping separation. This method has a simple process flow, low cost, and can realize large-scale industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 is a schematic process flow diagram of the present invention. EMBODIMENTS

[0030] The present invention will be described in detail below in conjunction with the drawings and specific embodiments: EXAMPLE

[0031] Take the lepidolite concentrate, screen and classify it, and take the fraction passing through a 120-mesh sieve. Add a mixed chlorinating agent and a roasting assistant carbon powder. Control the mass ratio of lepidolite concentrate: mixed chlorinating agent: roasting assistant as 1:0.4:0.1. After mixing evenly, load it into a rotary kiln for chlorination roasting. Control the roasting temperature at 850 °C and the roasting time at 90 min. After the obtained clinker calcine is cooled, leach it with 0.2 M dilute sulfuric acid by 5-stage countercurrent leaching. Control the leaching liquid-solid ratio at 3:1, the leaching time at 60 min, and the leaching temperature at 50 °C to obtain an acidic leaching solution containing rubidium and cesium. Adjust the alkalinity, that is, the pH value, to 12.5 by using sodium hydroxide for neutralization. The composite chlorinating agent is a mixture of calcium chloride, sodium chloride, and potassium chloride, and the conventional mass ratio of calcium chloride, sodium chloride, and potassium chloride is 3:1:1.

[0032] Use t-BAMBP as the extractant, alkoxy [calix4, calix6] crown ether as the co-extractant, and xylene as the diluent. Configure the extraction system according to the volume ratio of t-BAMBP: co-extractant: diluent as 20:5:75. Extract the rubidium and cesium solution with a pH value of 12.5 by 5-stage countercurrent extraction. Control the phase ratio O / A = 2:1, the extraction time at 3 min, and the clarification time at 5 min. After the two phases are separated, the raffinate is recovered. Wash the rubidium-loaded organic phase with deionized water, with a phase ratio O / A = 5:1, a washing time of 5 min, and a washing stage of 3 stages. Back-extract the washed loaded organic phase with 0.2 M hydrochloric acid by 3-stage countercurrent extraction, with a phase ratio O / A = 1:1, a back-extraction time of 5 min, and a clarification time of 5 min. After the two phases are separated, the back-extract solution is evaporated and crystallized to obtain rubidium chloride with a purity of ≥99.5%. Back-extract the residual organic phase after extracting rubidium with 2.0 M hydrochloric acid by 2-stage countercurrent extraction, with a phase ratio O / A = 5:1, a back-extraction time of 4 min, and a clarification time of 4 min. After the two phases are separated, the back-extract solution is evaporated and crystallized to obtain cesium chloride with a purity of ≥98.5%. Example

[0033] Take the lepidolite concentrate, screen and classify it, and take the fraction passing through a 120-mesh sieve. Add a mixed chlorinating agent and a roasting assistant carbon powder. Control the mass ratio of lepidolite concentrate: mixed chlorinating agent: roasting assistant as 1:0.3:0.2. After mixing evenly, load it into a rotary kiln for chlorination roasting. Control the roasting temperature at 800 °C and the roasting time at 120 min. After the obtained clinker calcine is cooled, leach it with 0.15 M dilute sulfuric acid by 4-stage countercurrent leaching. Control the leaching liquid-solid ratio at 4:1, the leaching time at 90 min, and the leaching temperature at room temperature to obtain an acidic leaching solution containing rubidium and cesium. Adjust the alkalinity, that is, the pH value, to 11.5 by using potassium hydroxide for neutralization.

[0034] Using t-BAMBP as the extractant, alkoxy [calix4, calix6] crown ether as the co-extractant, and cyclohexane as the diluent, an extraction system was configured according to the volume ratio of t-BAMBP∶co-extractant∶diluent of 25∶5∶70. A rubidium and cesium solution with a pH of 11.5 was subjected to 4-stage countercurrent extraction, with the phase ratio O / A controlled at 3:1, an extraction time of 3 min, and a clarification time of 5 min. After phase separation, the rubidium-loaded organic phase was washed with deionized water, with the phase ratio O / A at 5:1, a washing time of 5 min, and 3 washing stages. The washed loaded organic phase was subjected to 4-stage countercurrent stripping with 0.2 M hydrochloric acid, with the phase ratio O / A at 2:1, a stripping time of 5 min, and a clarification time of 5 min. After phase separation, the stripping solution was evaporated and crystallized to obtain rubidium chloride with a purity of ≥99.2%. The residual organic phase after rubidium extraction was subjected to 2-stage countercurrent stripping with 1.5 M hydrochloric acid, with the phase ratio O / A at 5:1, a stripping time of 4 min, and a clarification time of 4 min. After phase separation, the stripping solution was evaporated and crystallized to obtain cesium chloride with a purity of ≥99.0%. Example

[0035] The undersize fraction passing through a 120-mesh sieve was taken from the rubidium mica concentrate after screening and classification. Mixed chlorinating agent and roasting aid carbon powder were added, and the mass ratio of rubidium concentrate∶mixed chlorinating agent∶roasting aid was controlled at 1∶0.4∶0.05. After mixing evenly, it was charged into a rotary kiln for chlorination roasting. The roasting temperature was controlled at 900 °C and the roasting time was 120 min. After the obtained clinker calcine was cooled, it was leached by 6-stage countercurrent with 1.0 M dilute sulfuric acid. The leaching liquid-solid ratio was controlled at 2:1, the leaching time was 40 min, and the leaching temperature was room temperature, obtaining an acidic leaching solution containing rubidium and cesium, and the alkalinity was adjusted to pH 12.0 with potassium hydroxide.

[0036] Using t-BAMBP as the extractant, n-octanol as the co-extractant, and sulfonated kerosene as the diluent, an extraction system was configured according to the volume ratio of t-BAMBP∶co-extractant∶diluent of 20∶10∶70. A rubidium and cesium solution with a pH of 12.0 was subjected to 6-stage countercurrent extraction, with the phase ratio O / A controlled at 1:1, an extraction time of 3 min, and a clarification time of 5 min. After phase separation, the rubidium-loaded organic phase was washed with deionized water, with the phase ratio O / A at 5:1, a washing time of 5 min, and 3 washing stages. The washed loaded organic phase was subjected to 5-stage countercurrent stripping with

Claims

1. A method for extracting and separating rubidium and cesium from chlorinated roasted rubidium mica ore, characterized in that: The process involves roasting with specially added additives and composite chlorinating agents, leaching the roasted sand with dilute sulfuric acid, and using a composite extraction system to simultaneously extract rubidium and cesium, followed by stripping and separation of rubidium and cesium. The steps include: a. Rubidium mica concentrate as raw material, adding a composite chlorinating agent and a roasting aid, controlling the rubidium mica concentrate: composite chlorinating agent: roasting aid weight ratio of 1: 0.1-0.5: 0.05-0.2, mixed uniformly and loaded into a rotary kiln for chlorination roasting, controlling the roasting temperature 650-950 ℃, the roasting time is 30-150min, to obtain clinker calcine; b After the obtained clinker calcined was cooled, leached with an acid leaching agent for 3-6 countercurrent leaching, controlling the leachate-solid ratio of 1-4: 1, the leaching time was 30-150min, the leaching temperature was room temperature or heated to obtain an acidic leachate containing rubidium and cesium; c The obtained acidic leaching solution containing rubidium and cesium was adjusted to a pH range of 11-13 to obtain an alkaline leaching solution containing rubidium and cesium; d. The obtained alkaline leaching solution containing rubidium and cesium is simultaneously extracted by extracting rubidium and cesium, washing the loaded organic phase, first stripping to obtain a rubidium chloride solution, and then stripping to obtain a cesium chloride solution; The extraction of rubidium and cesium is a 3-6 stage countercurrent extraction, with t-BAMBP as an extractant, alkoxy [cup 4, cup 6] crown ether or n-octanol as a co-extractant, and a diluent selected from xylene, sulfonated kerosene, and cyclohexane. The extraction system is configured according to a volume ratio of t-BAMBP: co-extractant: diluent of 10-30:0.1-10:60-90, compared with O / A=1-3:1, the extraction time is 3 minutes, and the clarification time is 5 minutes. After the two phases are separated, the raffinate is recovered, and the rubidium-loaded organic phase is washed with deionized water. O / A=5:1, washing time 5min, washing stage 3; using 0.2M hydrochloric acid 3-5 levels of countercurrent stripping after washing, compared with O / A=1-3:1, stripping time 5min, clarification time 5min, after the two phases are separated, the stripping solution is evaporated and crystallized to obtain rubidium chloride; using 1.5-2.5M hydrochloric acid 2 levels of countercurrent stripping after rubidium is extracted, compared with O / A=5:1, stripping time 4min, clarification time 4min, after the two phases are separated, the stripping solution is evaporated and crystallized to obtain cesium chloride; The composite chlorinating agent in the roasting process is a mixture of calcium chloride, sodium chloride and potassium chloride, the conventional mass ratio of calcium chloride, sodium chloride and potassium chloride is 3:1:1, and the roasting aid is carbon powder; The leaching agent in the roasted sand leaching process is dilute sulfuric acid with a concentration of 0.1-2M.

2. The method according to claim 1, wherein: The pH value of the acidic leaching solution containing rubidium and cesium is adjusted to a range of 11-13 using one or more of sodium hydroxide, calcium hydroxide and potassium hydroxide to obtain an alkaline leaching solution containing rubidium and cesium.

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