Calcium removal method for bastnaesite flotation concentrate

Abstract

The invention belongs to the field of rare earth metallurgy, and discloses a method for removing calcium from bastnaesite flotation concentrate, which comprises the following steps: (1) inspecting and analyzing the bastnaesite flotation concentrate; (2) preparing a calcium removal agent solution according to the analysis result of the flotation concentrate; (3) heating the calcium removal agent solution to a set temperature, and adding the calcium removal agent solution into an open storage tank; (4) the bastnaesite flotation concentrate is added into a liftable reaction kettle, the reaction kettle sinks into an open storage tank filled with a calcium removal agent solution, and stirring is performed for a calcium removal reaction; (5) after the reaction is completed, the reaction kettle is lifted to be separated from the open storage tank, standing is conducted, after solid-liquid separation is conducted in the kettle, calcium removal reaction is conducted on the calcium removal agent which is moved to the position under the reaction kettle through the next stage of conveying equipment, and the countercurrent reaction process of bastnaesite flotation concentrate in the reaction kettle and the calcium removal agent in the open storage tank is formed; and (6) after the calcium removal reaction is completed, the reaction kettle sinks into an open storage tank filled with water, the carried calcium removal agent is stirred and washed away, and bastnaesite flotation concentrate subjected to calcium removal is obtained.

Description

Technical Field

[0001] The invention belongs to the field of rare earth metallurgy and relates to a method for removing calcium from bastnaesite flotation concentrate. Background Art

[0002] Fluorocarbon cerium ore (RECO3F) is the world's largest rare earth mineral resource in terms of reserves and mining volume. In Inner Mongolia, Sichuan and Shandong, China, there are large rare earth deposits dominated by fluorocarbon cerium ore, which provide about 70% of the world's rare earth raw materials. Flotation is the main method for recovering fluorocarbon cerium ore. Due to factors such as similar floatability and calcium ion adsorption, flotation often faces the problem of difficulty in separating fluorocarbon cerium ore from calcium-containing minerals. This results in 5-10% calcium in the flotation concentrate of fluorocarbon cerium ore after flotation.

[0003] The calcium in the bastnaesite flotation concentrate mainly exists in the form of acid-soluble calcium and insoluble calcium fluoride. If it is not removed, not only will a large amount of decomposition reagents be consumed in the subsequent decomposition and utilization process, but the calcium content in the rare earth liquid obtained by decomposition will also exceed the standard, affecting the extraction and separation of rare earths and the quality of subsequent products. However, the current relevant research is still mainly focused on the flotation separation reagents of bastnaesite and calcium-containing minerals in the flotation process, and there has been no report on the calcium removal process in the bastnaesite flotation ore. Summary of the invention

[0004] The purpose of the present invention is to develop a rapid, effective and low-cost preparation and decalcification method for removing calcium from bastnaesite flotation concentrate, so as to solve the problem of removing calcium from bastnaesite flotation concentrate under the premise of low rare earth dissolution.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] A method for decalcifying bastnaesite flotation concentrate comprises the following steps:

[0007] (1) sending the bastnaesite flotation concentrate to be processed for inspection and analysis;

[0008] (2) preparing a decalcification agent solution according to the analysis results of the bastnaesite flotation concentrate;

[0009] (3) After the decalcification agent solution is heated to the set temperature, it is added into the open storage tank;

[0010] (4) The fluorocarbon cerium ore flotation concentrate is added to a liftable reactor, and the reactor is sunk into an open storage tank filled with a decalcification agent solution and stirred to perform a decalcification reaction, wherein the reactor comprises a support plate, a stirring motor, a traction rope, a stirring paddle, a filter cloth and a filter frame with holes; the filter cloth is wrapped around the outside of the filter frame with holes; the filter frame with holes is connected to the support plate through the traction rope; the stirring motor is arranged on the support plate; one end of the stirring paddle is connected to the stirring motor, and the other end is inserted into the internal space of the filter frame with holes; the fluorocarbon cerium ore flotation concentrate is added to the internal space of the filter frame with holes; the support plate is connected to a lifting device, so that the reactor can be lifted and lowered;

[0011] (5) After the reaction is completed, the reactor is lifted out of the open storage tank, and after the solid and liquid in the reactor are left to stand for separation, the reactor is subjected to a decalcification reaction with the decalcification agent that is moved to the bottom of the reactor by the conveying equipment at the next stage, thereby forming a countercurrent reaction process between the bastnaesite flotation concentrate in the reactor and the decalcification agent in the open storage tank;

[0012] (6) After the decalcification reaction is completed, the reactor is sunk into an open storage tank filled with water, and the entrained decalcification agent is washed away by stirring to obtain a decalcified bastnaesite flotation concentrate.

[0013] Preferably, the total calcium content and acid-soluble calcium content of the fluorocarbon cerium ore flotation concentrate are first determined, and the estimated calcium fluoride content is obtained by subtracting the acid-soluble calcium content from the total calcium content, wherein the total calcium content is determined by atomic absorption spectroscopy; the acid-soluble calcium content is determined by dilute hydrochloric acid acid dissolution estimation method.

[0014] Preferably, the dilute hydrochloric acid acid dissolution estimation method is: take 10g of flotation concentrate and add 20ml of water to prepare the slurry, slowly add 1mol / L dilute hydrochloric acid while stirring, the molar amount of dilute hydrochloric acid added is estimated as twice the total molar amount of calcium, continue stirring for 30min after adding the acid, filter, rinse the filter residue until the pH value of the washing water is greater than 6, dry and measure the dry residue weight and calcium content, and convert the acid-soluble calcium amount.

[0015] Preferably, the decalcification agent solution is a mixed solution prepared by hydrochloric acid, aluminum chloride hexahydrate and water in a certain ratio, the molar concentration of hydrochloric acid in the prepared decalcification agent solution is 1-6 mol / L, preferably 3-4 mol / L, the mass concentration of aluminum chloride hexahydrate is 10-60%, preferably 25-45%, and the amount of decalcification agent solution added in a single tank is 0.5-3 ml / g flotation concentrate, preferably 1-2 ml / g flotation concentrate.

[0016] Preferably, the temperature of the decalcification agent solution is 40-100°C, preferably 60-90°C. The number of countercurrent decalcification reactions in step (5) is set according to the temperature of the decalcification agent solution. For specific settings, please refer to Table 1; wherein, the countercurrent decalcification reaction is a reaction between the decalcification agent of the previous stage and the fluorocarbon cerium ore flotation concentrate in the next stage reactor, and new decalcification agent and fluorocarbon cerium ore flotation concentrate are respectively added at both ends of the reaction. After reaching the set number of reactions, the decalcification agent is emptied from the open storage tank into the wastewater treatment link, and the flotation concentrate after decalcification enters the washing link of step (6).

[0017] Table 1 Correspondence between decalcification agent temperature and the number of countercurrent decalcification reactions

[0018]

[0019] Preferably, the number of countercurrent decalcification reactions is 1-6 times, preferably 2-4 times.

[0020] Preferably, the bastnaesite flotation concentrate is sunk into the decalcification agent solution and stirred for a reaction time of 0.5-2 h, preferably 1-1.5 h.

[0021] Preferably, step (6) is countercurrent washing, and the number of countercurrent washing is 1-4 times, preferably 2-3 times.

[0022] Preferably, the stirring and washing time in step (6) is 0.5-2 h, preferably 1-1.5 h.

[0023] The present invention adopts the prepared decalcification agent, and can simultaneously remove calcium in various occurrence states in the fluorocarbon cerium ore flotation concentrate through a simple solid-liquid stirring reaction. The agent is simple to prepare, and the rare earth dissolution rate in the decalcification process is low. The use of countercurrent reaction can significantly reduce the amount of decalcification agent and washing water, the equipment investment is small, and the operation is simple. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 Schematic diagram of the decalcification device in the present invention, wherein the reference numerals are as follows: 1-support plate, 2-stirring motor, 3-traction rope, 4-stirring paddle, 5-filter cloth, 6-filter frame with holes, 7-open storage tank;

[0025] Figure 2 It is a schematic diagram of a continuous countercurrent decalcification device;

[0026] Figure 3 This is the reaction flow chart of two-stage countercurrent decalcification of bastnaesite flotation concentrate. DETAILED DESCRIPTION

[0027] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further explained below in conjunction with specific implementation methods.

[0028] A method for decalcifying bastnaesite flotation concentrate comprises the following steps:

[0029] (1) sending the bastnaesite flotation concentrate to be processed for inspection and analysis;

[0030] (2) preparing a decalcification agent solution according to the analysis results of the bastnaesite flotation concentrate;

[0031] (3) After the decalcification agent solution is heated to the set temperature, it is added to the open storage tank 7;

[0032] (4) The fluorocarbon cerium ore flotation concentrate is added to a liftable reactor, and the reactor is sunk into an open storage tank 7 filled with a decalcification agent solution and stirred to perform a decalcification reaction, wherein the reactor comprises a support plate 1, a stirring motor 2, a traction rope 3, a stirring paddle 4, a filter cloth 5 and a filter frame with holes 6; the filter cloth 5 is wrapped around the outside of the filter frame with holes 6; the filter frame with holes 6 is connected to the support plate 1 through the traction rope 3; the stirring motor 2 is arranged on the support plate 1; one end of the stirring paddle 4 is connected to the stirring motor 2, and the other end is inserted into the internal space of the filter frame with holes 6; the fluorocarbon cerium ore flotation concentrate is added to the internal space of the filter frame with holes 6; the support plate 1 is connected to a lifting device, so that the reactor can be lifted and lowered;

[0033] (5) After the reaction is completed, the reactor is lifted out of the open storage tank 7, and after the solid and liquid in the reactor are left to stand, a decalcification reaction is carried out with the decalcification agent moved to the bottom of the reactor by the conveying equipment of the next stage, forming a countercurrent reaction process between the bastnaesite flotation concentrate in the reactor and the decalcification agent in the open storage tank 7;

[0034] (6) After the decalcification reaction is completed, the reactor is sunk into an open storage tank 7 filled with water, and the entrained decalcification agent is washed away by stirring to obtain a decalcified bastnaesite flotation concentrate.

[0035] The following is a detailed description of the decalcification method for bastnaesite flotation concentrate provided by the present invention in conjunction with the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0036] Embodiment 1:

[0037] The total calcium content of the fluorocarbon cerium ore flotation concentrate from a mine in Sichuan was 6.5%. 10g of the flotation concentrate was added with 20ml of water to prepare the slurry. 32.5ml of 1mol / L dilute hydrochloric acid was slowly added while stirring to dissolve the slurry. After adding the acid, stirring was continued for 30min before filtering. The residue was washed until the pH value of the washing water was greater than 6. The dry residue was dried and sent for measurement. The weight was 8.52g and the calcium content was 5.12%. The acid-soluble calcium content was converted to 0.21g. The total calcium content minus the acid-soluble calcium content was estimated to be 0.44g according to the difference subtraction method.

[0038] According to the analysis results of acid-soluble calcium and calcium fluoride content, 50 ml of decalcification agent with a hydrochloric acid content of 3 mol / L and a mass concentration of aluminum chloride hexahydrate of 42% was added to 100 g of fluorocarbon cerium ore flotation concentrate at a single time, and countercurrent decalcification reaction was carried out twice in a water bath at 90°C, with a single reaction time of 0.5 h. After the decalcification reaction, the decalcified residue was washed with water countercurrently for 3 times, with a single water volume of 100 ml, and the decalcified dry residue was obtained after filtration and drying.

[0039] According to the above reaction, the decalcification effect of bastnaesite flotation concentrate in three reactors was tested. Figure 3 It is a reaction flow chart of two-stage countercurrent decalcification of fluorocarbon cerium ore flotation concentrate, which shows three reactors filled with fluorocarbon cerium ore flotation concentrate, each reactor passes through two open storage tanks filled with decalcification agent solution, and the decalcification agent solution in each storage tank is 50ml. The decalcification agent solutions in the tanks a and b that the first reactor passes through are all newly prepared agents. After the reaction, the decalcification agent solution in the tank a is emptied into the wastewater treatment link. The decalcification agent solution in the tank b passes through the second reactor and reacts with the flotation concentrate in the second reactor. After the reaction, the decalcification agent solution in the tank b is emptied into the wastewater treatment link. The second reactor then sinks into the tank c with 50 ml of the newly prepared decalcification agent solution added for reaction. After the reaction, the decalcification agent solution in the tank c passes through the third reactor and reacts with the flotation concentrate in the third reactor. After the reaction, the decalcification agent solution in the tank c is emptied into the wastewater treatment link. The third reactor then sinks into the tank d with 50 ml of the newly prepared decalcification agent solution added for reaction. It should be noted that the tanks ad are only used to distinguish different tanks and do not represent the number of tanks.

[0040] The decalcified dry residue obtained after washing and drying in the three reaction kettles was tested, and the obtained component analysis table is shown in Table 2.

[0041] Table 2 Composition analysis of decalcified dry slag in three reactors

[0042]

[0043] It can be found that, except for the first reaction, after the countercurrent decalcification reaction is balanced, only 50 ml of decalcification agent is needed for every 100 g of fluorocarbon cerium ore flotation concentrate to achieve a good decalcification effect, with an average calcium removal rate of 96.17% and an average rare earth loss of 0.21% during the decalcification process.

[0044] Comparative Example 1:

[0045] First, add 50 ml of 3 mol / L hydrochloric acid to 100 g of fluorocarbon cerium ore flotation concentrate, react in a water bath at 90 ° C for 0.5 h, filter, add 50 ml of aluminum chloride hexahydrate solution with a mass concentration of 42% to the filter residue, react in a water bath at 90 ° C for 0.5 h, filter, and wash the decalcified residue with water for 3 times with a single water volume of 100 ml. Filter and dry, and the weight of the dried residue is measured to be 85.23 g, the calcium content is 1.23%, the calcium removal rate is 83.87%, and the rare earth loss during the decalcification process is 0.97%.

[0046] Comparative Example 2:

[0047] 50 ml of decalcification agent with a hydrochloric acid content of 3 mol / L and a mass concentration of 42% of aluminum chloride hexahydrate was added to 100 g of fluorocarbon cerium ore flotation concentrate at a single time, and the decalcification reaction was carried out once in a water bath at 90°C for 0.5 h. After the decalcification reaction, the decalcification residue was washed with water for 3 times with a single water volume of 100 ml, filtered and dried, and the weight of the dried residue was measured to be 85.45 g, the calcium content was 0.97%, the calcium removal rate was 87.25%, and the rare earth loss in the decalcification process was 0.24%.

[0048] In Comparative Example 1, the fluorocarbon cerium ore flotation concentrate is subjected to acid dissolution and calcium removal by aluminum chloride hexahydrate transformation. The calcium removal rate is 12.3% lower than that of the invention process, and the rare earth loss is increased by 0.76%. This is mainly because the rare earth dissolved by the invented decalcification agent during the decalcification process will combine with the fluorine dissolved by aluminum ion transformation to form rare earth fluoride precipitation, which reduces the rare earth loss. At the same time, the decrease in fluorine ion concentration promotes the transformation and dissolution of calcium fluoride, and the calcium removal rate is increased. In Comparative Example 2, the calcium removal rate of single calcium removal is 8.92% lower than that of countercurrent calcium removal after equilibrium in Example 1. Countercurrent calcium removal uses a new balance with the previous level of decalcification agent to remove part of the calcium before adding the new decalcification agent. Therefore, the calcium removal rate is higher at the same dosage of the agent.

[0049] Embodiment 2:

[0050] The total calcium content of the fluorocarbon cerium ore flotation concentrate from a mine in Sichuan was 6.5%. 10g of the flotation concentrate was added with 20ml of water to prepare the slurry. 32.5ml of 1mol / L dilute hydrochloric acid was slowly added while stirring to dissolve the slurry. After adding the acid, stirring was continued for 30min before filtering. The residue was washed until the pH value of the washing water was greater than 6. The dry residue was dried and sent for measurement. The weight was 8.52g and the calcium content was 5.12%. The acid-soluble calcium content was converted to 0.21g. The total calcium content minus the acid-soluble calcium content was estimated to be 0.44g according to the difference subtraction method.

[0051] According to the analysis results of acid-soluble calcium and calcium fluoride content, 50 ml of decalcification agent with a hydrochloric acid content of 3 mol / L and a mass concentration of 42% of aluminum chloride hexahydrate was added to 100 g of fluorocarbon cerium ore flotation ore at a single time, and a countercurrent decalcification reaction was carried out 5 times in a water bath at 40°C, with a single reaction time of 1 hour. After the decalcification reaction, the decalcified slag was stirred and washed with water 3 times, filtered and dried, and the calcium content in the dried slag was measured. After the countercurrent decalcification reaction was balanced, the average weight of the dried slag after decalcification of the newly added 3 groups of fluorocarbon cerium ore flotation ores was measured to be 85.17 g, the average calcium content was 0.55%, the average calcium removal rate was 92.78%, and the average rare earth loss during the decalcification process was 0.33%.

[0052] Embodiment 3:

[0053] The total calcium content of the fluorocarbon cerium ore flotation concentrate from a mine in Sichuan was 7.2%. 10g of the flotation concentrate was added with 20ml of water to prepare the slurry. 36ml of 1mol / L dilute hydrochloric acid was slowly added while stirring to dissolve the slurry. After adding the acid, stirring was continued for 30min before filtering. The residue was washed until the pH value of the washing water was greater than 6. The dry residue was dried and sent for measurement. The weight was 8.12g and the calcium content was 5.08%. The acid-soluble calcium content was converted to 0.31g. The total calcium content minus the acid-soluble calcium content was estimated to be 0.41g according to the difference subtraction method.

[0054] According to the analysis results of acid-soluble calcium and calcium fluoride content, 70 ml of decalcification agent with a hydrochloric acid content of 6 mol / L and a mass concentration of 50% aluminum chloride hexahydrate was added to 100 g of fluorocarbon cerium ore flotation ore at a single time, and the decalcification reaction was carried out once in a water bath at 100°C. The single reaction time was 1 hour. After the decalcification reaction, the decalcification residue was stirred and washed with water for 3 times, filtered and dried. The weight of the dried residue was measured to be 85.55 g, the calcium content was 0.32%, the calcium removal rate was 96.20%, and the rare earth loss during the decalcification process was 0.17%.

Claims

1. A method for decalcifying bastnaesite flotation concentrate, characterized in that: The following steps are involved: (1) sending the bastnaesite flotation concentrate to be processed for inspection and analysis; (2) preparing a decalcification agent solution according to the analysis results of the bastnaesite flotation concentrate; (3) After the decalcification agent solution is heated to the set temperature, it is added into the open storage tank; (4) The fluorocarbon cerium ore flotation concentrate is added to a liftable reactor, and the reactor is sunk into an open storage tank filled with a decalcification agent solution and stirred to perform a decalcification reaction, wherein the reactor comprises a support plate, a stirring motor, a traction rope, a stirring paddle, a filter cloth and a filter frame with holes; the filter cloth is wrapped around the outside of the filter frame with holes; the filter frame with holes is connected to the support plate through the traction rope; the stirring motor is arranged on the support plate; one end of the stirring paddle is connected to the stirring motor, and the other end is inserted into the internal space of the filter frame with holes; the fluorocarbon cerium ore flotation concentrate is added to the internal space of the filter frame with holes; the support plate is connected to a lifting device, so that the reactor can be lifted and lowered; (5) After the reaction is completed, the reactor is lifted out of the open storage tank, and after the solid and liquid in the reactor are left to stand for separation, the reactor is subjected to a decalcification reaction with the decalcification agent that is moved to the bottom of the reactor by the conveying equipment at the next stage, thereby forming a countercurrent reaction process between the bastnaesite flotation concentrate in the reactor and the decalcification agent in the open storage tank; (6) After the decalcification reaction is completed, the reactor is sunk into an open storage tank filled with water, and the entrained decalcification agent is washed away by stirring to obtain a decalcified bastnaesite flotation concentrate.

2. The method according to claim 1, characterized in that The total calcium content and the acid-soluble calcium content of the fluorocarbon cerium ore flotation concentrate are first determined, and the estimated calcium fluoride content is obtained by subtracting the acid-soluble calcium content from the total calcium content, wherein the total calcium content is determined by atomic absorption spectroscopy; the acid-soluble calcium content is determined by dilute hydrochloric acid acid dissolution estimation method.

3. The method according to claim 1, characterized in that The dilute hydrochloric acid acid dissolution estimation method is as follows: take 10g of flotation concentrate and add 20ml of water to prepare the slurry, slowly add 1mol / L dilute hydrochloric acid while stirring, the molar amount of dilute hydrochloric acid added is estimated as twice the total molar amount of calcium, continue stirring for 30min after adding the acid, filter, rinse the filter residue until the pH value of the washing water is greater than 6, dry and measure the dry residue weight and calcium content, and convert the acid-soluble calcium amount.

4. The method according to claim 1, characterized in that: The decalcification agent solution is a mixed solution prepared by mixing hydrochloric acid, aluminum chloride hexahydrate and water in a certain ratio. The molar concentration of hydrochloric acid in the prepared decalcification agent solution is 1-6 mol / L, the mass concentration of aluminum chloride hexahydrate is 10-60%, and the addition amount of the decalcification agent solution per tank is 0.5-3 ml / g of flotation concentrate.

5. The method according to claim 1, characterized in that: The temperature of the decalcification agent solution is 40-100°C. The number of countercurrent decalcification reactions in step (5) is set according to the temperature of the decalcification agent solution. The countercurrent decalcification reaction is a reaction between the decalcification agent of the previous stage and the fluorocarbon cerium ore flotation concentrate in the next stage reactor. New decalcification agents and fluorocarbon cerium ore flotation concentrate are added to both ends of the reaction. After reaching the set number of reactions, the decalcification agent is discharged from the open storage tank into the wastewater treatment link, and the flotation concentrate after decalcification enters the washing link of step (6).

6. The method according to claim 1, characterized in that The number of countercurrent decalcification reactions is 1-6 times.

7. The method according to claim 1, characterized in that The bastnaesite flotation concentrate is sunk into the decalcification agent solution and stirred for a reaction time of 0.5-2 hours.

8. The method according to claim 1, characterized in that The step (6) is countercurrent washing, and the number of countercurrent washings is 1-4 times.

9. The method according to claim 1, characterized in that: The stirring and washing time of step (6) is 0.5-2h.

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