Method for improving resource utilization of bauxite wet extraction tailings by using acid wastewater

Abstract

The invention belongs to the technical field of resource recovery, and provides a method for improving bauxite wet extraction tailing resource utilization by using acid wastewater, which comprises the following steps: mixing bauxite wet extraction tailings and acid wastewater, and precipitating to obtain filtrate and filter residue; and adjusting the pH of the filtrate, and adding sodium carbonate to finish the treatment. According to the method, through well-designed chemical and physical processes, bauxite wet extraction tailings rich in metal elements such as aluminum, sodium and calcium serve as a treating agent and are introduced into acid wastewater. Alkaline components in the tailings extracted by the bauxite wet method are neutralized with acidic substances in the wastewater, so that the acidity of the wastewater is remarkably reduced, the precipitation of heavy metal ions is promoted, harmful substances in the wastewater are effectively removed, and the dual targets of wastewater treatment and resource utilization are achieved.

Description

Technical Field

[0001] The invention relates to the technical field of resource recovery, and in particular to a method for improving the utilization of bauxite wet extraction tailings resources by utilizing acidic wastewater. Background Art

[0002] With the development of science and technology, the consumption of mineral resources is huge, and the amount of industrial waste acid water generated is also amazing. If these waste acid water cannot be effectively solved, it will not only waste water resources, but also affect the human living environment. At present, the treatment and utilization of waste acid water mainly focus on the traditional addition of acid and alkali substances to make the pH value of waste water close to neutral, and at the same time make the heavy metal ions in the waste water form hydroxide precipitation and precipitate for utilization.

[0003] Bauxite extraction tailings are materials produced during the processing of bauxite, usually containing a certain amount of aluminum, silicon and other elements and their composite compounds, with a high silicon and aluminum content and good looseness. As a composite resource, bauxite extraction tailings have a high research enthusiasm and rich research results, such as Chinese patent applications (publication numbers CN102910923A, CN106431443A), but the resource utilization of bauxite extraction tailings is simple, mainly focusing on the preparation of ceramsite, concrete and steam-cured bricks, etc., such as Chinese patent applications (publication numbers CN112062598A, CN116835926A, CN108530015A), which reduces the utilization rate of bauxite extraction tailings and has a low added value. The existing technology mainly uses wet method (publication number CN103882888A) and dry method (publication number CN109107752A) to treat bauxite tailings. The final tailings obtained have different contents. The SiO content in the tailings treated by dry method is 2 The total proportion is nearly 50%, and the aluminum-silicon ratio is 0.9. Therefore, the bauxite tailings obtained by wet treatment can make full use of resources.

[0004] In summary, there is currently no way to treat the two together, so a feasible process is designed to not only reduce the acidity of the wastewater, but also promote the precipitation of heavy metal ions to achieve the dual goals of wastewater treatment and bauxite wet extraction tailings resource utilization. Summary of the invention

[0005] The purpose of the present invention is to overcome the defects in the prior art and provide a method for improving the utilization of bauxite wet extraction tailings resources by utilizing acidic wastewater.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0007] The present invention provides a method for improving the utilization of bauxite wet extraction tailings resources by using acidic wastewater, comprising the following steps:

[0008] (1) mixing and precipitating bauxite wet extraction tailings and acidic wastewater to obtain a filtrate and a filter residue;

[0009] (2) After adjusting the pH of the filtrate, sodium carbonate is added to complete the treatment.

[0010] Preferably, the mesh size of the bauxite wet extraction tailings in step (1) is 100 to 300 meshes.

[0011] Preferably, in step (1), the mass ratio of the bauxite wet extraction tailings to the acidic wastewater is 5-15:80-100.

[0012] Preferably, the hydrogen ion concentration of the acidic wastewater in step (1) is 2.5 to 3.5 mol / L.

[0013] Preferably, the mixing time in step (1) is 1 to 2 hours.

[0014] Preferably, the precipitation time in step (1) is 1 to 2 hours.

[0015] Preferably, the reagent used to adjust the pH of the filtrate in step (2) is sodium hydroxide;

[0016] The mass ratio of sodium hydroxide to bauxite wet extraction tailings is 14-28:6-12.

[0017] Preferably, the mass volume ratio of the sodium carbonate and the filtrate is 4-5g:80-90mL.

[0018] The present invention provides a method for improving the resource utilization of bauxite wet extraction tailings by using acidic wastewater, comprising the following steps: mixing bauxite wet extraction tailings and acidic wastewater, and obtaining filtrate and filter residue after precipitation; and adding sodium carbonate after adjusting the pH of the filtrate to complete the treatment. The method uses a well-designed chemical and physical process to introduce bauxite wet extraction tailings rich in metal elements such as aluminum, sodium, and calcium as a treatment agent into the acidic wastewater. The alkaline components in the bauxite wet extraction tailings react with the acidic substances in the wastewater to neutralize, which not only significantly reduces the acidity of the wastewater, but also promotes the precipitation of heavy metal ions, effectively removing harmful substances in the wastewater, so as to achieve the dual goals of wastewater treatment and resource utilization.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0020] (1) The resource utilization of bauxite tailings is simple, mainly focusing on the preparation of ceramsite, concrete and steam-cured bricks, etc., which reduces the utilization rate of bauxite tailings and has low added value. This application uses acidic wastewater to improve the resource utilization rate of bauxite wet extraction tailings.

[0021] (2) The alkaline components in the bauxite tailings are neutralized by the acidic substances in the wastewater through wet extraction, which not only reduces the acidity of the wastewater, but also promotes the precipitation of heavy metal ions and effectively removes harmful substances in the wastewater, thereby achieving the dual goals of wastewater treatment and resource utilization.

[0022] (3) The aluminum-silicon ratio of the treated bauxite wet extraction tailings can be greatly improved and further applied in industry, such as the preparation of geopolymer grouting materials, dissolution of alumina, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 The present invention is a flow chart of a method for improving the utilization of tailings resources by wet extraction of bauxite using acidic wastewater. DETAILED DESCRIPTION

[0024] The present invention provides a method for improving the utilization of bauxite wet extraction tailings resources by using acidic wastewater, comprising the following steps:

[0025] (1) mixing and precipitating bauxite wet extraction tailings and acidic wastewater to obtain a filtrate and a filter residue;

[0026] (2) After adjusting the pH of the filtrate, sodium carbonate is added to complete the treatment.

[0027] In the present invention, the bauxite wet extraction tailings obtained are dried and then ground.

[0028] In the present invention, the mesh size of the bauxite wet extraction tailings in step (1) is preferably 100 to 300 meshes, more preferably 150 to 250 meshes, and more preferably 180 to 220 meshes.

[0029] In the present invention, the mass ratio of the bauxite wet extraction tailings and the acidic wastewater in step (1) is preferably 5-15:80-100, more preferably 6-14:85-95, and more preferably 8-12:88-92.

[0030] In the present invention, the hydrogen ion concentration of the acidic wastewater in step (1) is preferably 2.5 to 3.5 mol / L, more preferably 2.6 to 3.4 mol / L, and more preferably 2.8 to 3.2 mol / L.

[0031] In the present invention, the mixing time in step (1) is preferably 1 to 2 hours, more preferably 1.2 to 1.8 hours, and more preferably 1.4 to 1.6 hours.

[0032] In the present invention, the precipitation time in step (1) is preferably 1 to 2 hours, more preferably 1.2 to 1.8 hours, and more preferably 1.4 to 1.6 hours.

[0033] In the present invention, the aluminum-silicon ratio of the filter residue is 1.8 to 3.06.

[0034] In the present invention, the reagent used to adjust the pH of the filtrate in step (2) is sodium hydroxide.

[0035] In the present invention, the mass ratio of the sodium hydroxide to the bauxite wet extraction tailings is preferably 14-28:6-12, more preferably 16-26:8-10, and more preferably 18-24:8.5-9.5.

[0036] In the present invention, sodium hydroxide is added to adjust the pH value, and then sodium carbonate is added after filtering.

[0037] In the present invention, the mass volume ratio of the sodium carbonate and the filtrate is preferably 4-5 g:80-90 mL, more preferably 4.2-4.8 g:82-88 mL, and more preferably 4.4-4.6 g:84-86 mL.

[0038] In the present invention, the pH of the filtrate is adjusted and sodium carbonate is added before filtering to obtain Fe(OH) 3 、Al(OH) 3 Mg(OH) 2 、CaCO 3 .

[0039] The schematic diagram of the process of the present invention for improving the utilization of bauxite tailings resources by using acidic wastewater is as follows: Figure 1 shown.

[0040] The technical solutions provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0041] The bauxite wet extraction tailings used in the embodiment of the present invention were taken from an aluminum company in Henan Province, and the mineral composition is shown in Table 1.

[0042] Table 1 Mineral composition of bauxite wet extraction tailings

[0043] Element Calcite Diaspore Montmorillonite Sodium feldspar Andalusite Hematite content(%) 10.91 13.64 8.15 6.76 9.78 1.64

[0044] Example 1

[0045] The bauxite wet extraction tailings were dried and ground to a particle size of 200 mesh; the ground bauxite wet extraction tailings and acidic wastewater (2.5 mol / L) were mixed and stirred for 1 h at a mass ratio of 10:90, then precipitated for 2 h, and filtered to obtain a filtrate and a filter residue; the Na in the bauxite was tested. + All dissolved in the waste liquid, Fe 3+ 、Al 3+ Mg 2+ , Ca2+ The precipitation rates are 10.44%, 0.11%, 27.22% and 83.34% respectively.

[0046] Sodium hydroxide (the mass ratio of sodium hydroxide to bauxite wet tailings is 20:9) is added to the filtrate to obtain Fe(OH) 3 、Al(OH) 3 Mg(OH) 2 Then, sodium carbonate was added to the filtered filtrate (the mass volume ratio of sodium carbonate to filtrate was 4.5 g: 85 mL) until the Ca 2+ The precipitation was complete and the solid was filtered to complete the treatment.

[0047] The chemical composition and proportion of the filter residue after the acidic wastewater treatment are shown in Table 2. The aluminum-silicon ratio (molar ratio of aluminum / molar ratio of silicon) is 1.81.

[0048] Table 2 Chemical composition of the filter residue in Example 1

[0049] chemical composition <![CDATA[SiO 2 ]]> <![CDATA[Al 2 THE 3 ]]> <![CDATA[Fe 2 THE 3 ]]> CaO <![CDATA[K 2 The]]> MgO Ingredient content / % 29.38 45.11 4.46 4.20 2.48 1.23

[0050] Example 2

[0051] The bauxite wet extraction tailings were dried and ground to a particle size of 150 mesh; the ground bauxite wet extraction tailings and acidic wastewater (2.8 mol / L) were mixed and stirred for 2 h at a mass ratio of 8:95, then precipitated for 1 h, and filtered to obtain a filtrate and a filter residue; the Na in the bauxite was tested. + All dissolved in the waste liquid, Fe 3+ 、Al 3+ Mg 2+ , Ca 2+ The precipitation rates are 8.32%, 0.12%, 45.56% and 91.97% respectively.

[0052] Sodium hydroxide (the mass ratio of sodium hydroxide to bauxite wet extraction tailings is 15:23) is added to the filtrate to obtain Fe(OH) 3 、Al(OH) 3 Mg(OH) 2 Then, sodium carbonate was added to the filtered filtrate (the mass volume ratio of sodium carbonate to filtrate was 5 g: 82 mL) until the Ca 2+ The precipitation was complete and the solid was filtered to complete the treatment.

[0053] The chemical composition and proportion of the filter residue after acidic wastewater treatment are shown in Table 3. The aluminum-silicon ratio is 1.92.

[0054] Table 3 Chemical composition of the filter residue in Example 2

[0055] chemical composition <![CDATA[SiO 2 ]]> <![CDATA[Al 2 THE 3 ]]> <![CDATA[Fe 2 THE 3 ]]> CaO <![CDATA[K 2 The]]> MgO Ingredient content / % 28.22 46.13 4.58 2.03 2.72 0.92

[0056] Example 3

[0057] The bauxite wet extraction tailings were dried and ground to a particle size of 260 mesh; the ground bauxite wet extraction tailings and acidic wastewater (3.1 mol / L) were mixed and stirred for 2 h at a mass ratio of 14:91, then precipitated for 1 h, and filtered to obtain a filtrate and a filter residue; the Na in the bauxite was tested. + All dissolved in the waste liquid, Fe 3+ 、Al 3+ Mg 2+ , Ca 2+ The precipitation rates are 34.94%, 0.16%, 62.72% and 93.59% respectively.

[0058] Sodium hydroxide (the mass ratio of sodium hydroxide to bauxite wet extraction tailings is 14:20) is added to the filtrate to obtain Fe(OH) 3 、Al(OH) 3 Mg(OH) 2 Then, sodium carbonate was added to the filtered filtrate (the mass volume ratio of sodium carbonate to filtrate was 4.6 g: 81 mL) until the Ca 2+ The precipitation was complete and the solid was filtered to complete the treatment.

[0059] The chemical composition and proportion of the filter residue after acidic wastewater treatment are shown in Table 4. The aluminum-silicon ratio is 2.49.

[0060] Table 4 Chemical composition of the filter residue in Example 3

[0061] chemical composition <![CDATA[SiO 2 ]]> <![CDATA[Al 2 THE 3 ]]> <![CDATA[Fe 2 THE 3 ]]> CaO <![CDATA[K 2 The]]> MgO Ingredient content / % 25.46 53.86 3.24 1.62 3.25 0.63

[0062] Example 4

[0063] The bauxite wet extraction tailings were dried and ground to a particle size of 240 mesh; the ground bauxite wet extraction tailings and acidic wastewater (2.8 mol / L) were mixed and stirred for 2 h at a mass ratio of 13:82, then precipitated for 1 h, and filtered to obtain a filtrate and a filter residue; the Na in the bauxite was tested. + All dissolved in the waste liquid, Fe 3+ 、Al 3+ Mg 2+ , Ca 2+ The precipitation rates are 71.48%, 1.13%, 84.61% and 98.10% respectively.

[0064] Sodium hydroxide was added to the filtrate (the mass ratio of sodium hydroxide to bauxite wet extraction tailings was 25:7) to obtain Fe(OH) 3 、Al(OH) 3 Mg(OH)2 Then, sodium carbonate was added to the filtered filtrate (the mass volume ratio of sodium carbonate to filtrate was 5 g: 88 mL) until the Ca 2+ The precipitation was complete and the solid was filtered to complete the treatment.

[0065] The chemical composition and proportion of the filter residue after acidic wastewater treatment are shown in Table 5. The aluminum-silicon ratio is 3.06.

[0066] Table 5 Chemical composition of the filter residue in Example 4

[0067] chemical composition <![CDATA[SiO 2 ]]> <![CDATA[Al 2 THE 3 ]]> <![CDATA[Fe 2 THE 3 ]]> CaO <![CDATA[K 2 The]]> MgO Ingredient content / % 23.27 60.49 1.42 0.48 3.62 0.26

[0068] Comparative Example 1

[0069] The difference from Example 1 is that the acidic wastewater is replaced with pure water.

[0070] When sodium hydroxide and sodium carbonate were subsequently added, no precipitation was produced.

[0071] The chemical composition and proportion of the filter residue are shown in Table 6. The aluminum-silicon ratio is 1.03.

[0072] Table 6 Chemical composition of the residue in Comparative Example 1

[0073] chemical composition <![CDATA[SiO 2 ]]> <![CDATA[Al 2 THE 3 ]]> <![CDATA[Fe 2 THE 3 ]]> CaO <![CDATA[K 2 The]]> MgO NaO Ingredient content / % 29.61 25.81 4.98 25.28 0.97 1.69 11.2

[0074] As can be seen from the above embodiments, the present invention provides a method for treating acidic wastewater using bauxite wet extraction tailings, comprising the following steps: mixing bauxite wet extraction tailings and acidic wastewater, and obtaining a filtrate and a filter residue after precipitation; and adding sodium carbonate after adjusting the pH of the filtrate to complete the treatment. This method uses a carefully designed chemical and physical process to introduce bauxite wet extraction tailings rich in metal elements such as aluminum, sodium, and calcium as a treatment agent into the acidic wastewater. The alkaline components in the bauxite wet extraction tailings react with the acidic substances in the wastewater to neutralize, which not only significantly reduces the acidity of the wastewater, but also promotes the precipitation of heavy metal ions, effectively removing harmful substances in the wastewater, so as to achieve the dual goals of wastewater treatment and resource utilization.

[0075] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for improving the utilization of bauxite wet extraction tailings resources using acidic wastewater, characterized in that: It includes the following steps: (1) mixing and precipitating bauxite wet extraction tailings and acidic wastewater to obtain a filtrate and a filter residue; (2) After adjusting the pH of the filtrate, sodium carbonate is added to complete the treatment.

2. The method for improving the utilization of bauxite tailings by wet extraction using acidic wastewater according to claim 1, characterized in that: The mesh size of the bauxite wet extraction tailings in step (1) is 100 to 300 meshes.

3. The method for improving the utilization of bauxite tailings by wet extraction using acidic wastewater as claimed in claim 1 or 2, characterized in that: The mass ratio of the bauxite wet extraction tailings to the acidic wastewater in step (1) is 5-15:80-100.

4. The method for improving the utilization of bauxite tailings resources by using acidic wastewater as claimed in claim 3, characterized in that: The hydrogen ion concentration of the acidic wastewater in step (1) is 2.5 to 3.5 mol / L.

5. The method for improving the utilization of bauxite tailings resources by using acidic wastewater as claimed in claim 1 or 4, characterized in that: The mixing time in step (1) is 1 to 2 hours.

6. The method for improving the utilization of bauxite tailings resources by using acidic wastewater as claimed in claim 5, characterized in that: The precipitation time in step (1) is 1 to 2 hours.

7. The method for improving the utilization of bauxite tailings resources by using acidic wastewater as claimed in claim 6, characterized in that: The reagent used to adjust the pH of the filtrate in step (2) is sodium hydroxide; The mass ratio of sodium hydroxide to bauxite wet extraction tailings is 14-28:6-12.

8. The method for improving the utilization of bauxite tailings by wet extraction using acidic wastewater as claimed in claim 7, characterized in that: The mass volume ratio of the sodium carbonate and the filtrate is 4-5 g:80-90 mL.

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