Additive-free defluorination treatment method for bastnaesite

Abstract

The invention provides a bastnaesite additive-free defluorination treatment method, which belongs to the technical field of mineral treatment, and comprises the following steps: grinding bastnaesite, and sieving to obtain bastnaesite powder; roasting the bastnaesite powder in a rotary kiln at constant temperature; introducing saturated steam into bastnaesite powder roasted in the rotary kiln for high-temperature reaction; and guiding the gas generated by the reaction in the rotary kiln into adsorption equipment containing deionized water to recover HF. The bastnaesite additive-free defluorination treatment method provided by the invention is simple, efficient, environment-friendly and good in defluorination effect.

Description

Technical Field

[0001] The present invention relates to the technical field of mineral processing, and in particular to an additive-free defluorination treatment method for bastnaesite. Background Art

[0002] Rare earth elements have excellent properties in optics, electromagnetism, chemistry, etc., and their applications in materials, electronics, energy, medical and other fields are constantly expanding and developing rapidly.

[0003] Environmental protection issues in rare earth metallurgy are still one of the key issues that need to be solved urgently. Among them, the treatment methods of fluorocarbon cerium ore and Baotou mixed rare earth concentrate, which dominate the production of rare earths, are currently mainly based on oxidation roasting-hydrochloric acid leaching and concentrated sulfuric acid roasting. These methods not only have long process flows and large amounts of waste, resulting in serious waste of rare earth and fluorine resources, but also fail to effectively control fluorine, which is distributed in gas, solid metallurgical waste slag and metallurgical wastewater. In addition, because fluorine easily reacts with Ce under strong acid and high temperature conditions, it is easy for fluorine to react with fluorine. 4+ The occurrence of complexation reaction will also cause a decrease in rare earth leaching rate, further resulting in waste of resources.

[0004] Therefore, there is an urgent need for a simple, efficient and environmentally friendly defluorination method for bastnaesite to solve the current environmental problems existing in the production of rare earths from bastnaesite. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a simple, efficient, environmentally friendly and effective defluorination treatment method for bastnaesite without additives.

[0006] In order to solve the above technical problems, the present invention provides a method for defluorination of bastnaesite without additives, comprising the following steps:

[0007] Grinding the bastnaesite and sieving it to obtain bastnaesite powder;

[0008] The bastnaesite powder is calcined at a constant temperature in a rotary kiln;

[0009] Saturated steam is introduced into the bastnaesite powder calcined in the rotary kiln to carry out a high-temperature reaction;

[0010] The gas generated by the reaction in the rotary kiln is led to an adsorption device filled with deionized water to recover HF.

[0011] Furthermore, the grinding of the bastnaesite is performed in a planetary ball mill, and the particle size of the bastnaesite powder obtained by sieving is between -50 mesh and -150 mesh.

[0012] Furthermore, during the ball milling process of the bastnaesite, the ball milling is stopped after every 2-3 minutes, and the ball milling is cooled for 1-2 minutes before continuing the ball milling.

[0013] Furthermore, the calcination temperature of the bastnaesite powder in the rotary kiln is set to 650° C.-1050° C., the calcination time is set to 30-240 min, and the rotation speed of the rotary kiln is set to 1-6 r / min.

[0014] Furthermore, the flow rate of the saturated steam into the rotary kiln is 0.6-1.5m 3 / kg·h.

[0015] Furthermore, when the bastnaesite powder is introduced into saturated water vapor for high-temperature reaction, the temperature is controlled to be 950° C.-1050° C., and the reaction time is controlled to be 60-150 minutes.

[0016] Furthermore, the adsorption device is a horizontal fixed window adsorption device containing deionized water.

[0017] The present invention provides an additive-free defluorination method for bastnaesite. The method involves grinding and sieving bastnaesite to obtain powder, then calcining it at high temperature in a rotary kiln. The calcined powder then reacts with saturated water vapor at high temperature to convert the fluorine in the bastnaesite into HF gas. The resulting gas is then passed through an adsorption device containing deionized water to recover the HF. This method not only has strong raw material adaptability, a simple and easy-to-operate process, and a short treatment flow, but also enables efficient and full recovery of the F element in the bastnaesite, is environmentally friendly, and offers low processing costs and high economic benefits. It is worthy of widespread use and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a flow chart of a method for defluorination of bastnaesite without additives provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0019] See also Figure 1 The embodiment of the present invention provides a method for defluorination of bastnaesite without additives, comprising the following steps:

[0020] Step 1) grinding bastnaesite and sieving to obtain bastnaesite powder.

[0021] To effectively refine the bastnaesite particles so they can better react with water vapor, the bastnaesite is milled in a planetary ball mill. After grinding and crushing, the bastnaesite is sieved to produce a bastnaesite powder with a particle size of -50 to -150 mesh.

[0022] In order to prevent the fluorocarbon cerium ore powder from being decomposed due to excessive temperature during the ball milling process, the ball milling of the fluorocarbon cerium ore is stopped every 2-3 minutes, and then cooled for 1-2 minutes, and then the ball milling is continued, and this process is repeated until the particle size of the ball-milled fluorocarbon cerium ore after screening is between -50 mesh and -150 mesh.

[0023] Step 2) calcining the fluorocarbon cerium ore powder in a rotary kiln at a constant temperature.

[0024] In order to fully defluorinate the bastnaesite powder during the roasting reaction with saturated water vapor, the bastnaesite needs to be roasted. During the roasting process, the RE(CO3)F structure in the bastnaesite decomposes to form the REOF structure (where RE represents rare earth metals such as lanthanum, cerium, praseodymium, and neodymium), and then the next step of water vapor defluorination is carried out. The chemical reactions that occur in this process are as follows:

[0025] REF3·RE2(CO3)3=REF3+RE2O3+CO2(g) (1)

[0026] Ce2O3+1 / 2O2=2CeO2 (2)

[0027] REF3+RE2O3=3REOF (3)

[0028] As a specific embodiment of the present invention, during the roasting process of fluorocarbon cerium ore, in order to facilitate the full decomposition of the RE(CO3)F structure in the fluorocarbon cerium ore to form a REOF structure, the roasting temperature of the fluorocarbon cerium ore powder in the rotary kiln is set to 650°C-1050°C through the controller of the rotary kiln, the roasting time is set to 30-240min, and the speed of the rotary kiln is set to 1-6r / min.

[0029] Step 3) Saturated water vapor is introduced into the calcined bastnaesite powder in the rotary kiln to carry out a high-temperature reaction. The following reactions occur during the reaction:

[0030] REF3+3H2O(g)=RE2O3+6HF(g) (4)

[0031] 2REOF+H2O(g)=RE2O3+2HF(g) (5)

[0032] As a specific embodiment of the present invention, in order to allow the saturated water vapor to completely react with the fluorine-containing compound in the calcined bastnaesite powder, the flow rate of the saturated water vapor into the rotary kiln is controlled to be 0.6-1.5m 3 / kg·h.

[0033] At the same time, as a specific embodiment of the present invention, in order to enable saturated water vapor to effectively and fully react with the fluorine-containing compound in the calcined fluorocarbon cerium ore powder, the temperature of the fluorocarbon cerium ore powder when passing saturated water vapor for high-temperature reaction is controlled to be 950°C-1050°C, and the reaction time is controlled to be 60-150 minutes.

[0034] Step 4) The gas generated by the reaction in the rotary kiln is led to an adsorption device filled with deionized water to recover HF.

[0035] Among them, the adsorption equipment is a horizontal fixed window adsorption equipment containing deionized water.

[0036] The HF in the gas generated by the reaction in the rotary kiln is absorbed by the deionized water in the adsorption equipment to obtain an acid solution containing hydrofluoric acid.

[0037] Through the above treatment process, the fluorine removal rate in fluorocarbon cerium ore can reach up to 99.8%, and the obtained hydrofluoric acid solution can be directly used in industrial production, thereby enabling the fluorine element in fluorocarbon cerium ore to be efficiently recovered and utilized.

[0038] At the same time, the F-free tail gas remaining after the HF in the gas generated by the reaction in the rotary kiln is recovered can be discharged directly, thereby reducing the impact on the environment and being environmentally friendly.

[0039] Furthermore, after the bastnaesite powder is calcined in the rotary kiln and saturated steam is introduced to complete the calcination reaction, the remaining product can be directly used for subsequent rare earth element recovery. Since the fluorine element in the remaining product is essentially completely removed, the environmental pollution caused by fluorine during the rare earth element recovery process is significantly reduced, resulting in an environmentally friendly process.

[0040] The following examples and comparative examples illustrate the additive-free defluorination method for bastnaesite provided by the present invention.

[0041] Example 1

[0042] (1) Take an appropriate amount of fluorocarbon cerium ore and put it into a grinding jar for ball milling (in the process of grinding, to prevent the sample from being decomposed by excessive temperature, grind for two minutes and then stop to cool for one minute). Weigh the fluorocarbon cerium ore powder with a particle size of -150 mesh after ball milling.

[0043] (2) Set the temperature to 950°C in the controller, slowly pour the fluorocarbon cerium ore powder into the rotary kiln, control the rotary kiln speed to 3 r / min, and roast for 120 min.

[0044] (3) Keep the rotary kiln speed unchanged, adjust the rotary kiln temperature to 1050℃, and saturated steam prepared in advance at 1.2m 3The fixed flow rate of 100 g / kg·h was introduced into the rotary kiln to allow the saturated water vapor to react with the calcined bastnaesite powder in the rotary kiln at high temperature for 150 min.

[0045] (4) The gas in the rotary kiln is directed through a pipeline to a horizontal fixed window adsorption device containing H2O to recover the escaped HF.

[0046] The experimental data were recorded and the F removal rate of bastnaesite was calculated.

[0047] After the above process, the F removal rate was 99.8%.

[0048] Example 2

[0049] (1) Take an appropriate amount of fluorocarbon cerium ore and put it into a grinding jar for ball milling (in the process of grinding, to prevent the sample from being decomposed by excessive temperature, grind for two minutes and then stop to cool for one minute). Weigh the fluorocarbon cerium ore powder with a particle size of -150 mesh after ball milling.

[0050] (2) The temperature was set at 850°C in the controller, and the fluorocarbon cerium ore powder was slowly poured into the rotary kiln. The speed of the rotary kiln was controlled to 3 r / min, and the calcination was carried out for 120 min.

[0051] (3) Keep the rotary kiln speed unchanged, adjust the rotary kiln temperature to 1000℃, and saturated steam prepared in advance at 0.6m 3 The fixed flow rate of 100 g / kg·h was introduced into the rotary kiln to allow the saturated water vapor to react with the calcined bastnaesite powder in the rotary kiln at high temperature for 150 min.

[0052] (4) The gas in the rotary kiln is directed through a pipeline to a horizontal fixed window adsorption device containing H2O to recover the escaped HF.

[0053] The experimental data were recorded and the F removal rate of bastnaesite was calculated.

[0054] After the above process, the F removal rate was 82.72%.

[0055] Example 3

[0056] (1) Take an appropriate amount of fluorocarbon cerium ore and put it into a grinding jar for ball milling (in the process of grinding, to prevent the sample from being decomposed by excessive temperature, grind for two minutes and then stop to cool for one minute). Weigh the fluorocarbon cerium ore powder with a particle size of -150 mesh after ball milling.

[0057] (2) Set the temperature to 750°C in the controller, slowly pour the fluorocarbon cerium ore powder into the rotary kiln, control the rotary kiln speed to 3 r / min, and roast for 120 min.

[0058] (3) Keep the rotary kiln speed unchanged, adjust the rotary kiln temperature to 950℃, and saturated steam prepared in advance at 0.8m 3 The fixed flow rate of 100 g / kg·h was introduced into the rotary kiln, so that the saturated water vapor reacted with the calcined bastnaesite powder in the rotary kiln at high temperature for 90 min.

[0059] (4) The gas in the rotary kiln is directed through a pipeline to a horizontal fixed window adsorption device containing H2O to recover the escaped HF.

[0060] The experimental data were recorded and the F removal rate of bastnaesite was calculated.

[0061] After the above process, the F removal rate was 76.07%.

[0062] Example 4

[0063] (1) Take an appropriate amount of fluorocarbon cerium ore and put it into a grinding jar for ball milling (in the process of grinding, to prevent the sample from being decomposed by excessive temperature, grind for two minutes and then stop to cool for one minute). Weigh the fluorocarbon cerium ore powder with a particle size of -150 mesh after ball milling.

[0064] (2) Set the temperature to 650°C in the controller, slowly pour the fluorocarbon cerium ore powder into the rotary kiln, control the rotary kiln speed to 3 r / min, and roast for 120 min.

[0065] (3) Keep the rotary kiln speed unchanged, adjust the rotary kiln temperature to 950℃, and saturated steam prepared in advance at 0.8m 3 The fixed flow rate of 100 g / kg·h was introduced into the rotary kiln to allow the saturated water vapor to react with the calcined bastnaesite powder in the rotary kiln at high temperature for 100 min.

[0066] (4) The gas in the rotary kiln is directed through a pipeline to a horizontal fixed window adsorption device containing H2O to recover the escaped HF.

[0067] The experimental data were recorded and the F removal rate of bastnaesite was calculated.

[0068] After the above process, the F removal rate was 82.59%.

[0069] Example 5

[0070] (1) Take an appropriate amount of fluorocarbon cerium ore and put it into a grinding jar for ball milling (in the process of grinding, to prevent the sample from being decomposed by excessive temperature, grind for two minutes and then stop to cool for one minute). Weigh the fluorocarbon cerium ore powder with a particle size of -150 mesh after ball milling.

[0071] (2) The temperature was set at 950°C in the controller, and the fluorocarbon cerium ore powder was slowly poured into the rotary kiln. The speed of the rotary kiln was controlled to 4 rpm, and the calcination was carried out for 90 min.

[0072] (3) Keep the rotary kiln speed unchanged, adjust the rotary kiln temperature to 1050℃, and saturated steam prepared in advance at 0.8m 3 The fixed flow rate of 100 g / kg·h was introduced into the rotary kiln to allow the saturated water vapor to react with the calcined bastnaesite powder in the rotary kiln at high temperature for 150 min.

[0073] (4) The gas in the rotary kiln is directed through a pipeline to a horizontal fixed window adsorption device containing H2O to recover the escaped HF.

[0074] The experimental data were recorded and the F removal rate of bastnaesite was calculated.

[0075] After the above process, the F removal rate was 96.72%.

[0076] Example 6

[0077] (1) Take an appropriate amount of fluorocarbon cerium ore and put it into a grinding jar for ball milling (in the process of grinding, to prevent the sample from being decomposed by excessive temperature, grind for two minutes and then stop to cool for one minute). Weigh the fluorocarbon cerium ore powder with a particle size of -150 mesh after ball milling.

[0078] (2) Set the temperature to 1050°C in the controller, slowly pour the fluorocarbon cerium ore powder into the rotary kiln, control the rotary kiln speed to 5 r / min, and roast for 60 minutes.

[0079] (3) Keep the rotary kiln speed unchanged, adjust the rotary kiln temperature to 1050℃, and saturated steam prepared in advance at 1.2m 3 / kg·h fixed flow rate into the rotary kiln, keeping the temperature and speed of the rotary kiln unchanged, and the saturated water vapor reacts with the fluorocarbon cerium ore powder roasted in the rotary kiln at high temperature for 120 minutes.

[0080] (4) The gas in the rotary kiln is directed through a pipeline to a horizontal fixed window adsorption device containing H2O to recover the escaped HF.

[0081] The experimental data were recorded and the F removal rate of bastnaesite was calculated.

[0082] After the above process, the F removal rate was 96.52%.

[0083] Example 7

[0084] (1) Take an appropriate amount of fluorocarbon cerium ore and put it into a grinding jar for ball milling (in the process of grinding, to prevent the sample from being decomposed by excessive temperature, grind for two minutes and then stop to cool for one minute). Weigh the fluorocarbon cerium ore powder with a particle size of -150 mesh after ball milling.

[0085] (2) Set the temperature to 950°C in the controller, slowly pour the fluorocarbon cerium ore powder into the rotary kiln, control the rotary kiln speed to 6 r / min, and roast for 30 minutes.

[0086] (3) Keep the rotary kiln speed unchanged, adjust the rotary kiln temperature to 1000℃, and saturated steam prepared in advance at 1.5m 3 The fixed flow rate of 100 g / kg·h was introduced into the rotary kiln to allow the saturated water vapor to react with the calcined bastnaesite powder in the rotary kiln at high temperature for 60 min.

[0087] (4) The gas in the rotary kiln is directed through a pipeline to a horizontal fixed window adsorption device containing H2O to recover the escaped HF.

[0088] The experimental data were recorded and the F removal rate of bastnaesite was calculated.

[0089] After the above process, the F removal rate was 88.84%.

[0090] Example 8

[0091] (1) Take an appropriate amount of fluorocarbon cerium ore and put it into a grinding jar for ball milling (in the process of grinding, to prevent the sample from being decomposed by excessive temperature, grind for two minutes and then stop to cool for one minute). Weigh the fluorocarbon cerium ore powder with a particle size of -50 mesh after ball milling.

[0092] (2) Set the temperature to 950°C in the controller, slowly pour the fluorocarbon cerium ore powder into the rotary kiln, control the rotary kiln speed to 3 r / min, and roast for 120 min.

[0093] (3) Keep the rotary kiln speed unchanged, adjust the rotary kiln temperature to 950℃, and saturated steam prepared in advance at 0.6m 3 The fixed flow rate of 100 g / kg·h was introduced into the rotary kiln to allow the saturated water vapor to react with the calcined bastnaesite powder in the rotary kiln at high temperature for 110 min.

[0094] (4) The gas in the rotary kiln is directed through a pipeline to a horizontal fixed window adsorption device containing H2O to recover the escaped HF.

[0095] The experimental data were recorded and the F removal rate of bastnaesite was calculated.

[0096] After the above process, the F removal rate was 84.83%.

[0097] Example 9

[0098] (1) Take an appropriate amount of fluorocarbon cerium ore and put it into a grinding jar for ball milling (in the process of grinding, to prevent the sample from decomposing due to excessive temperature, grind for two minutes and stop to cool for one minute), and weigh the fluorocarbon cerium ore powder with a particle size of -100 mesh after ball milling.

[0099] (2) Set the temperature to 950°C in the controller, slowly pour the fluorocarbon cerium ore powder into the rotary kiln, control the rotary kiln speed to 3 r / min, and roast for 120 min.

[0100] (3) Keep the rotary kiln speed unchanged, adjust the rotary kiln temperature to 1000℃, and saturated steam prepared in advance at 0.7m 3 The fixed flow rate of 100 g / kg·h was introduced into the rotary kiln, so that the saturated water vapor reacted with the calcined bastnaesite powder in the rotary kiln at high temperature for 120 min.

[0101] (4) The gas in the rotary kiln is directed through a pipeline to a horizontal fixed window adsorption device containing H2O to recover the escaped HF.

[0102] The experimental data were recorded and the F removal rate of bastnaesite was calculated.

[0103] After the above process, the F removal rate was 88.46%.

[0104] Comparative Example

[0105] (1) Take an appropriate amount of fluorocarbon cerium ore and put it into a grinding jar for ball milling (in the process of grinding, to prevent the sample from being decomposed by excessive temperature, grind for two minutes and then stop to cool for one minute). Weigh the fluorocarbon cerium ore powder with a particle size of -150 mesh after ball milling.

[0106] (2) Set the temperature to 950°C in the controller, slowly pour the fluorocarbon cerium ore powder into the rotary kiln, control the rotary kiln speed to 3 r / min, and roast for 120 min.

[0107] (3) The air is heated at 1.2m 3 / kg·h fixed flow rate into the rotary kiln.

[0108] (4) The gas in the rotary kiln is directed through a pipeline to a horizontal fixed window adsorption device containing H2O to recover the escaped HF.

[0109] The experimental data were recorded and the F removal rate of bastnaesite was calculated.

[0110] After the above process, the F removal rate was 41.31%.

[0111] According to Examples 1-9, it can be seen that after fluorocarbon cerium ore is calcined at high temperature under a saturated water vapor atmosphere, the HF gas emitted during the calcination process is recovered with deionized water, which is indeed feasible and effective. Calcination experiments at different temperatures, different times and different particle sizes obtain different experimental results, thereby screening out the best calcination conditions. By comparing Examples 1-9 and the comparative example, it can be seen that the treatment effect of fluorocarbon cerium ore by a saturated water vapor atmosphere has a significant effect. Moreover, from the comparison of the process parameters of Examples 1-9, it can be seen that in the defluorination process of fluorocarbon cerium ore, the roasting time and roasting temperature also have a certain influence on the defluorination rate of fluorocarbon cerium ore.

[0112] Therefore, the additive-free defluorination treatment method of fluorocarbon cerium ore provided by the present invention can achieve a good defluorination effect by high-temperature roasting of fluorocarbon cerium ore in a saturated water vapor atmosphere, and controlling the roasting time and roasting temperature within a certain range. In addition, the present invention defluorinates water as a single substance, and no other substances are added during the treatment process. Not only can the F element be fully recovered, but the water vapor is also environmentally friendly. During the roasting process, no HF gas is generated, which can be absorbed in time by an absorption device filled with deionized water and will not be discharged into the air to affect the environment and harm human health. At the same time, less wastewater is generated, which is beneficial to the environment. Therefore, it has broad application prospects.

[0113] Finally, it should be noted that the above specific implementation methods are only used to illustrate the technical solutions of the present invention and are not limiting. Although the present invention has been described in detail with reference to examples, those skilled in the art should understand that the technical solutions of the present invention can be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A method for defluorination of bastnaesite without additives, characterized in that: The steps include: Grinding the bastnaesite and sieving to obtain bastnaesite powder; The bastnaesite powder is calcined at a constant temperature in a rotary kiln; Saturated steam is introduced into the bastnaesite powder calcined in the rotary kiln to carry out a high-temperature reaction; The gas generated by the reaction in the rotary kiln is led to an adsorption device filled with deionized water to recover HF.

2. The additive-free defluorination method for bastnaesite according to claim 1, characterized in that: The grinding of the bastnaesite is carried out in a planetary ball mill, and the particle size of the bastnaesite powder obtained by sieving is between -50 mesh and -150 mesh.

3. The additive-free defluorination method of bastnaesite according to claim 2, characterized in that: During the ball milling process of the fluorocarbon naesite, the ball milling is stopped after every 2-3 minutes, and the ball milling is cooled for 1-2 minutes, and then the ball milling is continued.

4. The additive-free defluorination method for bastnaesite according to claim 1, characterized in that: The calcination temperature of the fluorocarbon cerium ore powder in the rotary kiln is set to 650° C.-1050° C., the calcination time is set to 30-240 min, and the rotation speed of the rotary kiln is set to 1-6 r / min.

5. The additive-free defluorination method of bastnaesite according to claim 1, characterized in that: The flow rate of the saturated steam into the rotary kiln is 0.6-1.5m 3 / kg·h.

6. The additive-free defluorination method of bastnaesite according to claim 5, characterized in that: The temperature of the bastnaesite powder when passing saturated water vapor to perform a high-temperature reaction is controlled to be 950° C.-1050° C., and the reaction time is controlled to be 60-150 minutes.

7. The additive-free defluorination method for bastnaesite according to claim 1, characterized in that: The adsorption device is a horizontal fixed window adsorption device containing deionized water.

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