Method for separating valuable metals in acid leaching solution

Abstract

The invention belongs to the technical field of waste resource utilization, and provides a separation method for valuable metals in an acid leaching solution. After the pH value of the acid leaching solution is adjusted to be alkaline, the obtained alkaline solution is mixed with gas containing carbon dioxide in a spraying or aeration mode for reaction. According to the method, magnesium ions and aluminum ions in the acid leaching solution are converted into basic carbonate and calcium ions are converted into carbonate by utilizing carbon dioxide and liquid caustic soda; compared with hydroxide, basic carbonate and carbonate cannot adsorb lithium ions and rare earth ions in an acid leaching solution, ferric hydroxide formed by a small amount of iron ions has limited adsorption on the lithium ions, and efficient separation and recovery of the lithium ions can be achieved. Furthermore, the carbon dioxide-containing gas is carbon dioxide-containing tail gas, and the separation method can utilize the carbon dioxide gas in the tail gas, so that the carbon emission is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of valuable metal recovery, and particularly relates to a method for separating valuable metals in an acid leaching solution. BACKGROUND

[0002] In the process of extracting valuable elements from ores or solid waste by wet treatment, the acid leaching solution obtained contains a large amount of lithium ions, rare earth ions, aluminum ions, calcium ions, magnesium ions and iron ions, and these ions generally need to be separated to obtain the required valuable elements. In the prior art, when valuable metals are recovered from the acid leaching solution, sodium hydroxide or lime is generally used to precipitate and remove aluminum ions, calcium ions, magnesium ions and iron ions in the form of hydroxides; and then lithium ions and rare earth ions in the filtrate are recovered respectively. However, the hydroxides formed by aluminum ions, calcium ions and magnesium ions can adsorb lithium ions in the acid leaching solution, and the hydroxide precipitate formed directly in the acid solution containing lithium ions may contain about 0.3% lithium oxide and the like, resulting in a low recovery rate of lithium ions. SUMMARY

[0003] Therefore, the present application provides a method for separating valuable metals in an acid leaching solution. The separation method provided by the present application can realize efficient recovery of lithium ions in the acid leaching solution.

[0004] In order to achieve the above-mentioned application purposes, the present application provides the following technical solutions:

[0005] The present application provides a method for separating valuable metals in an acid leaching solution, comprising the following steps:

[0006] After adjusting the pH value of the acid leaching solution to be alkaline, the obtained alkaline solution is mixed with carbon dioxide gas by spraying or aeration to react;

[0007] The acid leaching solution comprises the following components at the following concentrations:

[0008] Lithium ions 0-25 g / L, rare earth ions 0-30 g / L, iron ions 0-0.1 g / L, calcium ions 0-1 g / L, magnesium ions 0-2 g / L, aluminum ions 0.1-50 g / L, the concentrations of the iron ions, calcium ions and magnesium ions are not simultaneously 0, and the concentrations of the lithium ions and rare earth ions are not simultaneously 0.

[0009] Preferably, the pH value of the alkaline solution is 8-11.

[0010] Preferably, the reagent for adjusting the pH value of the acid leaching solution to be alkaline is liquid alkali.

[0011] Preferably, the volume content of carbon dioxide in the carbon dioxide gas is 8-100%.

[0012] Preferably, the carbon dioxide-containing gas is a carbon dioxide-containing tail gas.

[0013] Preferably, the spraying is performed in a spray tower.

[0014] Preferably, the aeration is performed in an aeration tank.

[0015] Preferably, after the reaction, the method further comprises: solid-liquid separation of the obtained mixed system to obtain filter residue and filtrate; and rinsing and drying of the filtrate to obtain the carbon fixation material.

[0016] The application provides a method for separating valuable metals in an acid leaching solution, comprising the following steps: after adjusting the pH value of the acid leaching solution to be alkaline, the obtained alkaline solution is mixed with a carbon dioxide-containing gas by spraying or aeration to perform a reaction; the acid leaching solution comprises the following components: lithium ions 0-25 g / L, rare earth ions 0-30 g / L, iron ions 0-0.1 g / L, calcium ions 0-1 g / L, magnesium ions 0-2 g / L, and aluminum ions 0.1-50 g / L, and the concentrations of the iron ions, calcium ions and magnesium ions are not all 0, and the concentrations of the lithium ions and rare earth ions are not all 0.

[0017] The application converts the magnesium ions and aluminum ions in the acid leaching solution into basic carbonates and the calcium ions into carbonates by using carbon dioxide and liquid alkali; compared with hydroxides, the basic carbonates do not adsorb lithium ions and rare earth ions in the acid leaching solution, and the small amount of iron hydroxide formed by the iron ions in the acid leaching solution has limited adsorption on the lithium ions and rare earth ions, so that efficient separation and recovery of the lithium ions can be realized.

[0018] Further, the carbon dioxide-containing gas is a carbon dioxide-containing tail gas, and the separation method of the application can utilize the carbon dioxide gas in the tail gas, thereby reducing carbon emissions. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 The flowchart of the method for separating valuable metals in an acid leaching solution provided by the application is shown. DETAILED DESCRIPTION

[0020] Figure 1 The flowchart of the method for separating valuable metals in an acid leaching solution provided by the application is shown, and the method will be described in detail below Figure 1 The separation method provided by the application is described in detail.

[0021] The application provides a method for separating valuable metals in an acid leaching solution, comprising the following steps:

[0022] After adjusting the pH value of the acid leaching solution to be alkaline, the obtained alkaline solution is mixed with a carbon dioxide-containing gas by spraying or aeration to perform a reaction;

[0023] The acid leaching solution comprises the following components at the following concentrations:

[0024] Lithium ions 0-25 g / L, rare earth ions 0-30 g / L, iron ions 0-0.1 g / L, calcium ions 0-1 g / L, magnesium ions 0-2 g / L, aluminum ions 0.1-50 g / L, the concentrations of the iron ions, calcium ions and magnesium ions are not simultaneously 0, and the concentrations of the lithium ions and rare earth ions are not simultaneously 0.

[0025] In the present application, the raw materials used in the present application are preferably commercially available products.

[0026] After the pH value of the acid leaching solution is adjusted to be alkaline, an alkaline solution is obtained.

[0027] In the present application, the acid leaching solution preferably comprises the following components at the following concentrations:

[0028] Lithium ions 0-25 g / L, rare earth ions 0-30 g / L, iron ions 0-0.1 g / L, calcium ions 0-1 g / L, magnesium ions 0-2 g / L, aluminum ions 0.1-50 g / L, the concentrations of the iron ions, calcium ions and magnesium ions are not simultaneously 0, and the concentrations of the lithium ions and rare earth ions are not simultaneously 0.

[0029] In the present application, the pH value of the alkaline solution is preferably 8-11, and more preferably 9-10; and the reagent for adjusting the pH value of the acid leaching solution to be alkaline is preferably liquid alkali.

[0030] After the alkaline solution is obtained, the alkaline solution is mixed with carbon dioxide-containing gas by spraying or aeration to realize carbon sequestration.

[0031] In the present application, the volume content of carbon dioxide in the carbon dioxide-containing gas is preferably 8-100%, and more preferably 8-15%. In the present application, the carbon dioxide-containing gas is preferably carbon dioxide-containing tail gas.

[0032] In the present application, the spraying is preferably carried out in a spraying tower; and the spraying preferably comprises the following steps: the acid leaching solution is pumped into the spraying tower, the liquid alkali is used to adjust the acid leaching solution to be alkaline, and an alkaline solution is obtained; the alkaline solution is sent to the top of the spraying tower for atomization, and is mixed with the carbon dioxide-containing gas entering the spraying tower.

[0033] In the present application, the aeration is preferably carried out in an aeration tank; and the aeration preferably comprises the following steps: the acid leaching solution is pumped into the aeration tank, the liquid alkali is used to adjust the acid leaching solution to be alkaline, and an alkaline solution is obtained; and the alkaline solution is mixed with the carbon dioxide-containing gas entering the aeration pipe.

[0034] In the present application, the reaction occurring in the process of the reaction includes:

[0035] Al 3+ +6NaOH+3CO2=NaAl(OH)2CO3↓+3Na + +2NaHCO3+H2O;

[0036] Ca 2+ +2NaOH+CO2=CaCO3↓+2Na + +H2O;

[0037] 2Mg 2+ +4NaOH+CO2=Mg2(OH)2CO3↓+2Na + +H2O;

[0038] 2Fe 3+ +6NaOH→2Fe(OH)3↓+6Na + ;

[0039] After the reaction, the present application preferably further includes: solid-liquid separation of the obtained mixed system to obtain filter residue and filtrate; the filtrate is rinsed and dried to obtain a carbon fixation material.

[0040] In the present application, the solid-liquid separation method is preferably pressure filtration. In the present application, the filtrate preferably includes valuable metal ions and sodium ions; the valuable metal ions preferably include one or more of rare earth ions and lithium ions; the filtrate preferably further includes other metal ions; the other metal ions preferably include one or more of magnesium ions, calcium ions, aluminum ions and iron ions, the concentration of the magnesium ions is preferably ≤10 mg / L, the concentration of the calcium ions is preferably ≤50 mg / L, the concentration of the aluminum ions is preferably ≤5 mg / L, and the concentration of the iron ions is preferably ≤0.0001 mg / L.

[0041] The present application does not make specific limitations on the recovery method of the filtrate, and the recovery can be performed by methods well known to those skilled in the art.

[0042] In the present application, the drying method is preferably spray drying.

[0043] The present application preferably further includes heating the carbon fixation material; the heating preferably includes a first heating method, a second heating method or a third heating method.

[0044] In the present application, the first heating mode preferably comprises sequentially performing first stage heating, second stage heating, third stage heating, fourth stage heating, fifth stage heating and sixth stage heating; the temperature of the first stage heating is preferably 120 DEG C, and the holding time is preferably 4 hours; the temperature of the second stage heating is preferably 220 DEG C, and the holding time is preferably 2 hours; the temperature of the third stage heating is preferably 320 DEG C, and the holding time is preferably 2 hours; the temperature of the fourth stage heating is preferably 360 DEG C, and the holding time is preferably 2 hours; the temperature of the fifth stage heating is preferably 850 DEG C, and the holding time is preferably 2 hours; the temperature of the sixth stage heating is preferably 1200 DEG C, and the holding time is preferably 2 hours.

[0045] In the present application, the second heating mode preferably comprises sequentially performing first stage heating and second stage heating, the temperature of the first stage heating is preferably 120 DEG C, and the holding time is preferably 4 hours; the temperature of the second stage heating is preferably 1000 DEG C, and the holding time is preferably 2 hours.

[0046] In the present application, the third heating mode preferably comprises sequentially performing first stage heating, second stage heating and third stage heating, the temperature of the first stage heating is preferably 120 DEG C, and the holding time is preferably 4 hours; the temperature of the second stage heating is preferably 350 DEG C, and the holding time is preferably 4 hours; the temperature of the third stage heating is preferably 1000 DEG C, and the holding time is preferably 2 hours.

[0047] In the present application, the main reactions occurring in the process of heating are as follows:

[0048] 2NaAl(OH)2CO3=Al2O3+Na2O+2H2O↑+2CO2↑;

[0049] Mg2(OH)2CO3=2MgO+H2O↑+CO2↑;

[0050] CaCO3=CaO+CO2↑;

[0051] 2Fe(OH)3=Fe2O3+3H2O↑.

[0052] The method for separating valuable metals in acid leaching solution provided by the present application will be described in detail below in combination with examples, but they should not be understood as limiting the protection scope of the present application.

[0053] Example 1

[0054] The acid leaching solution containing aluminum chloride 16.94 g / L, lithium chloride 28.94 g / L, iron chloride 0.05 g / L, calcium chloride 2.82 g / L, magnesium chloride 2.61 g / L is pumped into a spray tower with a diameter of 2.5 meters and a height of 8 meters, the liquid caustic is sent into the spray tower by a pump to mix with the acid leaching solution, the pH is controlled at 9-10, at the same time, the carbon dioxide-containing waste gas from a gas boiler is introduced into the spray tower by a pipeline (the volume content of carbon dioxide is 10%), the basic solution at the bottom of the spray tower is sent to the top of the spray tower by a pump to be atomized and mixed with the gas boiler tail gas entering the spray tower to react, the mixed solution with precipitate at the bottom of the spray tower is pumped out and filtered, the filtrate is mainly lithium chloride and sodium chloride solution, due to the introduction of liquid caustic and water in the tail gas, the solution is diluted, the concentration of lithium chloride is 20.86 g / L, the concentration of sodium chloride is 57.83 g / L, the concentrations of iron and aluminum ions are 0; the concentrations of calcium and magnesium ions are reduced to 44 mg / L and 8 mg / L respectively.

[0055] The filter mud is rinsed and pressure filtered to obtain a semi-product with a water content of 85%, the filter mud is sampled, detected after being kept in a thermostat at 120°C for 4 hours, and the lithium oxide content is 0.07%. The filter mud is spray dried to obtain a yellowish powder solid carbon material, the water content of the solid carbon material is 5%, the solid carbon material contains Mg 5.10%, Na 11.19%, Al 13.14%, Fe 0.07%, Ca 3.90%, trace amount of Li, and the rest of the elements are carbon, hydrogen and oxygen.

[0056] The solid carbon material is kept in a thermostat at 120°C for 4 hours, weighed 1000 g, heated to 220°C and kept for 2 hours, weighed again, and the weight is reduced by 1.2 g; the powder is continuously heated, kept at 320°C for 2 hours, and the powder is reduced by 317.5 g; the powder is continuously heated, kept at 360°C for 2 hours, and the powder is reduced by 68.5 g; the powder is continuously heated, kept at 850°C for 2 hours, and the powder is reduced by 45 g; the weight of the remaining powder is 567.8 g, the powder is continuously heated to 1200°C, and kept for 2 hours, and the weight of the powder is not reduced any more, and the final weight is 567.5 g.

[0057] The residual solid carbon powder is continuously chemically analyzed, and the composition of the residual solid carbon powder is Al2O3 46.0%, Na2O 27.97%, MgO 15.70%, CaO 10.13%, Fe2O3 0.18%, trace amount of Li2O, and the rest is water.

[0058] Example 2

[0059] The acid leaching solution containing aluminum chloride 35.94 g / L, lithium chloride 25.5 g / L, calcium chloride 0.32 g / L, magnesium chloride 0.61 g / L is pumped into a 300 m 3The liquid caustic is pumped into the aeration tank to mix with the acid leaching solution, the pH is controlled at 9-10, and the exhaust gas boiler tail gas containing CO2 (the volume content of CO2 is 12%) is introduced into the aeration tank by a pipeline, and the aeration tank is continuously stirred. The mixture liquid with precipitate at the bottom of the tower is pumped out and filtered. The filtrate is mainly lithium chloride and sodium chloride solution. Due to the introduction of liquid caustic and water in the tail gas, the solution is diluted, the concentration of aluminum ions is 0, and the concentration of calcium and magnesium ions is reduced to about 5 mg / L.

[0060] The filter mud is rinsed and pressure filtered to obtain a semi-product with a moisture content of 85%. A filter mud sample is detected in a thermostat at 120°C for 4 hours, and the lithium oxide content is 0.03%. The filter mud is spray dried to obtain a light yellow powder solid carbon material. The moisture content of the solid carbon material is 5%, and the solid carbon material contains Mg 0.43%, Na 17.13%, Al 20.11%, Ca 0.32%, C 9.62%, trace Li, and the remaining elements are hydrogen and oxygen.

[0061] 1000 g of the above solid carbon material is heated to 120°C and kept for 4 hours, and then weighed as 951 g. The powder is continuously heated, and there is no irritating odor in the heating process. After being kept at 1000°C for 2 hours and cooled, the final weight of the powder is 541.5 g.

[0062] The residual solid carbon powder is continuously chemically analyzed, and the composition is Al2O3 61.0%, Na2O 37.1%, MgO 1.15%, CaO 0.72%, trace Li2O, and the balance is water.

[0063] Example 3

[0064] The acid leaching solution containing aluminum sulfate 152.15 g / L, lithium sulfate 6.65 g / L, and magnesium sulfate 0.22 g / L is pumped into the aeration tank of 300 m 3 The liquid caustic is pumped into the aeration tank to mix with the acid leaching solution, the pH is controlled at 9-10, and the exhaust gas boiler tail gas containing CO2 (the volume content of CO2 is 10-15) is introduced into the aeration tank by a pipeline. When the exhaust gas boiler tail gas is insufficient, liquid CO2 is gasified in a tank to supplement. The aeration tank is continuously stirred. The mixture liquid with precipitate at the bottom of the tower is pumped out and filtered. The filtrate is mainly lithium sulfate and sodium sulfate solution. Due to the introduction of liquid caustic and water in the tail gas, the solution is diluted, the concentration of aluminum ions is 0, and the concentration of magnesium ions is reduced to 5 mg / L.

[0065] The filter mud was washed and filtered to obtain a semi-product with a moisture content of 70%. Samples were taken and incubated at 120℃ for 4 hours in a constant temperature chamber for analysis; the Li₂O content was 0.02%. The filter mud was then spray-dried to obtain a white powdery carbon-fixing material. Analysis showed that the carbon-fixing material contained 5% moisture, 0.064% Mg, 15.14% Na, 17.78% Al, 7.917% C, trace amounts of Li, and the remaining elements were hydrogen and oxygen.

[0066] After removing moisture by keeping the above-mentioned carbon-fixing material at 120℃ for 4 hours in a constant temperature chamber, weigh 1000g, heat it to 350℃ and keep it at that temperature for 4 hours, then weigh it again. The weight is 569.4g. Continue heating the powder to 1000℃. There is no irritating odor during the heating process. Keep it at that temperature for 2 hours. The powder hardly loses any weight. The final weight is 569.3g.

[0067] Further chemical analysis of the residual carbon powder revealed that its main components were 62.29% Al2O3, 7.86% Na2O3, 0.20% MgO, trace amounts of Li2O, and the remainder was water.

[0068] Comparative Example 1

[0069] The acid leaching solution from Example 1 was pumped into a spray tower with a diameter of 2.5 meters and a height of 8 meters. Liquid alkali was pumped into the spray tower and mixed with the acid leaching solution, controlling the pH to 9-10. The mixture with precipitate at the bottom of the spray tower was pumped out and filtered. The filtrate mainly consisted of lithium chloride and sodium chloride solutions. Due to the introduction of water into the liquid alkali, the solution was diluted. The concentration of lithium chloride was 14.6 g / L, the concentration of sodium chloride was 59.3 g / L, and the concentrations of iron and aluminum ions were 0. The concentrations of calcium and magnesium ions were reduced to 45 mg / L and 10 mg / L, respectively.

[0070] The filter mud was rinsed and filtered to obtain a semi-product with a moisture content of 85%. Samples of the filter mud were then incubated at 120℃ for 4 hours in a constant temperature chamber, and the lithium oxide content was found to be 0.29%.

[0071] Comparative Example 2

[0072] The acid leaching solution from Example 2 was pumped into a 300m... 3 In the aeration tank, liquid alkali is pumped into the aeration tank and mixed with the acid leaching solution. Air is introduced into the aeration tank for stirring, and the pH is controlled at 9-10. The mixture with precipitate at the bottom of the tower is pumped out and filtered. The filtrate is mainly lithium chloride and sodium chloride solution. Due to the introduction of liquid alkali and water in the tail gas, the solution is diluted, and the aluminum ion concentration is 0, while the calcium and magnesium ions are reduced to about 8 mg / L.

[0073] The filter mud was rinsed and filtered to obtain a semi-product with a moisture content of 85%. The filter mud was sampled and kept at 120℃ for 4 hours in a constant temperature chamber for testing. It was found to contain 0.35% lithium oxide.

[0074] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for separating valuable metals from an acid leaching solution, characterized in that, Includes the following steps: After adjusting the pH of the acid leaching solution to alkaline, the resulting alkaline solution is mixed with carbon dioxide gas by spraying or aeration to carry out the reaction. The acid leaching solution comprises components of the following concentrations: The concentrations of lithium ions are 0–25 g / L, rare earth ions are 0–30 g / L, iron ions are 0–0.1 g / L, calcium ions are 0–1 g / L, magnesium ions are 0–2 g / L, and aluminum ions are 0.1–50 g / L. The concentrations of iron ions, calcium ions, and magnesium ions are not all 0 at the same time, and the concentrations of lithium ions and rare earth ions are not all 0 at the same time.

2. The separation method according to claim 1, characterized in that, The alkaline pH value is 8 to 11.

3. The separation method according to claim 1 or 2, characterized in that, The reagent used to adjust the pH of the acid leaching solution to be alkaline is liquid alkali.

4. The separation method according to claim 1, characterized in that, The volume content of carbon dioxide in the carbon dioxide-containing gas is 8% to 100%.

5. The separation method according to claim 4, characterized in that, The carbon dioxide-containing gas is carbon dioxide-containing exhaust gas.

6. The separation method according to claim 1, characterized in that, The spraying is carried out in a spray tower.

7. The separation method according to claim 1, characterized in that, The aeration takes place in an aeration tank.

8. The separation method according to claim 1, characterized in that, The reaction process further includes: separating the solid and liquid components of the resulting mixture to obtain filter residue and filtrate; and rinsing and drying the filtrate to obtain a carbon-fixing material.

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