Method for preparing white carbon black and separating metal hydroxide by using yellow phosphorus solid waste and titanium dioxide waste acid

Abstract

This invention provides a method for preparing precipitated silica and co-producing calcium sulfate using yellow phosphorus solid waste calcium silicate and titanium dioxide waste acid, and for separating metal hydroxides. The method includes the following steps: 1. Passing the titanium dioxide waste acid through an ion exchange membrane to obtain clean acid, which is then collected for later use; 2. Reacting the yellow phosphorus solid waste calcium silicate with titanium dioxide waste liquid and then separating the liquid, which is the mother liquor; 3. Slurrying the separated solid and reacting it with liquid alkali to obtain a suspension, and then drying the separated solid to obtain calcium sulfate; 4. Passing clean acid into the mother liquor to generate a precipitate, which is then separated, with the solid being precipitated silica and the liquid being a sodium sulfate solution; 5. Allowing the mother liquor to mature through reaction before entering the separation system for further separation, and further recovering the metal hydroxide precipitates of the separated single metal elements. This method achieves efficient separation and harmless treatment of multiple metal elements in the mother liquor, and simultaneously utilizes yellow phosphorus solid waste calcium silicate and titanium dioxide waste acid to prepare precipitated silica and calcium sulfate, realizing comprehensive resource utilization and environmental protection.

Description

Technical Field

[0001] This invention belongs to the field of comprehensive utilization of waste residue from yellow phosphorus smelting and waste liquid from titanium dioxide, specifically involving a method for preparing white carbon black and co-producing calcium sulfate and separating metal hydroxides using solid waste calcium silicate slag from yellow phosphorus and waste acid from titanium dioxide. Background Technology

[0002] More and more titanium dioxide manufacturers are joining hands with the phosphorus chemical industry to create a circular economy of sulfur, phosphorus, iron, and titanium. However, the liquid waste dilute sulfuric acid produced by the titanium dioxide industry contains a variety of complex metal impurity ions, including Fe, Ti, Al, Mn, and Mg. For every ton of titanium dioxide produced, 5-6 tons of waste acid with a concentration of 23% are generated simultaneously. The treatment of this waste acid restricts the development of the sulfuric acid process for producing titanium dioxide. Similarly, for every ton of yellow phosphorus produced, approximately 9.5 tons of yellow phosphorus slag and calcium silicate slag are generated simultaneously. The treatment of this calcium silicate slag also restricts the development of the yellow phosphorus industry. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a method for preparing silica and co-producing calcium sulfate using yellow phosphorus solid waste calcium silicate slag and titanium dioxide waste acid, and separating metal hydroxides.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is: a method for preparing silica and separating metal hydroxides from yellow phosphorus solid waste and titanium dioxide waste acid, characterized by comprising the following steps: Step 1: Pass the waste acid from titanium dioxide through an ion exchange membrane to obtain clean acid, and collect it for later use; Step 2: Add the yellow phosphorus solid waste calcium silicate slag to the titanium dioxide liquid waste in a certain proportion, control the reaction temperature to avoid the formation of silica gel, and separate after the reaction. The separated solid is solid B1 and the liquid is mother liquor C1. Step 3: Wash solid B1 and grind it into a slurry. Add liquid alkali to react and obtain a suspension. Separate the suspension. The separated solid is solid B2 and the liquid is liquid C2. Wash and dry solid B2 to obtain calcium sulfate. Step 4: Pass clean acid into liquid C2, controlling the flow rate at 4-6 L / min. After precipitate is formed, let it mature for 0.5-3 hours before solid-liquid separation. Wash the separated solid and then dry it to obtain precipitated silica. The separated liquid is sodium sulfate solution, which is sent to the collection tank. Step 5: Pump the mother liquor C1 into the reaction tank for reaction maturation, and then enter the separation system for separation. Further recovery is carried out on the metal hydroxide precipitate of the separated single metal element.

[0005] Furthermore, in step two, the mass ratio of titanium dioxide waste to calcium silicate slag is 5-7; the reaction temperature is controlled at 80-100℃.

[0006] Furthermore, in step three, the amount of liquid alkali added is based on a mass ratio M. 30%氢氧化钠 M 钙硅渣酸解后粉体 The value ranges from 2.33 to 5.67; the wash water from washing solid B1 enters the mother liquor C1.

[0007] Furthermore, in step four, the wash water used to wash the solid separated from the solid-liquid mixture is introduced into the mother liquor C1.

[0008] The method for preparing silica and separating metal hydroxides from yellow phosphorus solid waste and titanium dioxide waste acid is characterized in that the separation system includes a primary separator, a secondary separator, a tertiary separator, a quaternary separator, and a quinary separator connected in series and having the same structure; the separation system is controlled by a PLC.

[0009] Step five specifically includes: (a) Pump the mother liquor C1 into the primary reaction tank and introduce liquid alkali into it, control the pH to 2-3, heat to boiling, and after aging for 0.5-1 hour, enter the primary separator; (ii) The solid slurry separated by the primary separator is metatitanic acid. The metatitanic acid is sent to the first collection tank, and the filtrate enters the secondary reaction tank. Liquid alkali and hydrogen peroxide are added to the reaction tank at the same time, and the pH is controlled at 3.8-4.1. After the reaction is complete, it is aged for 0.5-1 hours and then enters the secondary separator for solid-liquid separation. The separated solid is a precipitated slurry of basic ferric hydroxide. The precipitated slurry is sent to the second collection tank, and the separated filtrate is sent to the tertiary reaction tank. (iii) Liquid alkali is introduced into the three-stage reaction tank to adjust the pH value to 4.5-6. After the reaction is complete, it is allowed to mature for 0.5-1 hour before entering the three-stage separator for solid-liquid separation. The separated solid slurry is Al(OH). 3， The filtrate is sent to the third collection tank, and the separated filtrate is sent to the fourth reaction tank. (iv) Pour liquid alkali into the fourth-stage reaction tank, adjust the pH to 9.8-10.5, and purge with a large amount of compressed air to ensure complete reaction. After maturing for 1-1.5 hours, it enters the fourth-stage separator for solid-liquid separation. The separated solid slurry is a precipitate of Mn(OH)2. Send the solid slurry to the fourth collection tank and the separated filtrate to the fifth-stage reaction tank. (v) Add liquid alkali to the fifth-stage reaction vessel, adjust the pH to not less than 12.5, stir thoroughly, and let it mature for 0.5-1h after the reaction is complete. Then enter the fifth-stage separator. The separated Mg(OH)2 precipitate is sent to the fifth collection tank, and the separated sodium sulfate solution is sent to the sixth collection tank. (vi) Evaporate and crystallize the sodium sulfate solution in the sixth collection tank to obtain the finished sodium sulfate powder.

[0010] Furthermore, the first-stage separator, second-stage separator, third-stage separator, fourth-stage separator, and fifth-stage separator each include three identical tubes, with two tubes working alternately and one tube as a backup. One end of the pipe is an inlet connected to the slurry pipe, and the other end is an outlet connected to the filtrate pipe. The inlet end of the pipe is equipped with a valve No. 1, and the pipe is connected to a washing water pipe above and a sedimentation slurry pipe below. The outlet end is equipped with a valve No. 2, and the pipe is connected to a compressed air pipe above and a washing water collection pipe below.

[0011] The pipe body is equipped with a filter screen and a flow rate sensor in the middle; the washing water pipe is equipped with a washing water valve, the sedimentation slurry pipe is equipped with a slurry valve, the compressed air pipe is equipped with a compressed air valve, and the washing water collection pipe is equipped with a washing valve. When the flow rate sensor detects that the linear velocity of the filtrate flow rate decreases to 0-0.5 cm / s, it indicates that a certain thickness of sediment cake has adhered to the filter screen, affecting the flow rate. The PLC control automatically closes valves one and two to clean the pipe body and switches to another pipe body for operation.

[0012] The cleaning process is as follows: the PLC controls the simultaneous opening of the washing water valve and the washing valve, and the washing water with a pressure of 0.1-0.3 MPa is used to rinse the filter screen for 3-5 seconds through the washing water pipe. The washing water is then discharged into the washing water collection tank through the washing water collection pipe. After the slurry filter cake adhering to the feed inlet side of the filter screen is washed clean, open the slurry valve and the compressed air valve, blow air into the filter screen for 0.2-0.5 seconds to make the slurry filter cake fall off the filter screen, close the compressed air valve, open the washing water valve to flush water for 0.2 seconds, close the washing water valve, and the slurry filter cake that has fallen off by backflushing is flushed into the collection tank, and the self-cleaning of the pipeline is completed.

[0013] The beneficial effects of this invention are as follows: In the entire process system, the reaction tanks and separation systems at each level work closely together. By precisely controlling the reaction conditions (such as pH value, reaction time, amount of added reagents, etc.) and separation parameters (such as sieve mesh size, flow rate, etc.), the efficient separation and harmless treatment of multiple metal elements in the mother liquor are achieved. At the same time, white carbon black and calcium sulfate are prepared by using yellow phosphorus solid waste calcium silicon slag and titanium dioxide waste acid, thus achieving the dual purpose of comprehensive resource utilization and environmental protection. Attached Figure Description

[0014] Figure 1 This is a process flow diagram of the present invention; Figure 2 This is a schematic diagram of the separator involved in the present invention; Wherein: H1 - primary separator, H2 - secondary separator, H3 - tertiary separator, H4 - quaternary separator, H5 - quinary separator; G1 - primary reaction vessel, G2 - secondary reaction vessel, G3 - tertiary reaction vessel, G4 - quaternary reaction vessel, G5 - quinary reaction vessel; M1 - first collection vessel, M2 - second collection vessel, M3 - third collection vessel, M4 - fourth collection vessel, M5 - fifth collection vessel, M6 - sixth collection vessel; 1-Wash water pipe, 2-Sedimentation slurry pipe, 3-Compressed air pipe, 4-Wash water collection pipe, S-Filter screen, Q-Flow rate sensor, A-Pipe body, A1-Inlet, A2-Outlet, F1-Valve No. 1, F2-Valve No. 2, F11-Wash water valve, F12-Slurry valve, F13-Compressed air valve, F14-Washing valve. Detailed Implementation

[0015] The principles and features of the present invention are described below with reference to the accompanying drawings. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention. Example

[0016] Raw material source: Titanium dioxide waste acid—the hydrolysis of titanium oxysulfate to produce hydrated titanium dioxide (i.e., metatitanic acid) and approximately 23% dilute sulfuric acid. This dilute sulfuric acid contains incompletely hydrolyzed Ti, as well as Fe, Al, Mn, and other metallic elements brought in from the ilmenite source, with the following concentrations: Fe 35 g / L, Ti 2462 ppm, Al 1785 ppm, Mn 2257 ppm, Mg 3186 ppm. These impurity metallic elements exist in the waste acid in the form of ferrous sulfate, aluminum sulfate, manganese sulfate, and magnesium sulfate.

[0017] See Figure 1-2 A method for preparing silica and separating metal hydroxides from yellow phosphorus solid waste and titanium dioxide waste acid, characterized by comprising the following steps: Step 1: Take 10 m³ of waste acid from the titanium dioxide waste acid source and pass it through an ion exchange membrane. Collect the clean acid after passing through the membrane for later use. Step 2: Add 2t of yellow phosphorus solid waste calcium silicon slag to 10t of titanium dioxide waste acid for reaction, then add 1t of water, control the reaction temperature at 85℃, and after the reaction is completed, perform solid-liquid separation. The separated solid is solid B1, and the liquid is mother liquor C1. Step 3: Wash solid B1 and add the washing water into mother liquor C1. Pulverize the washed solid B1 into a slurry and add 0.8t of NaOH and 0.8t of water to react and obtain a suspension. Separate the suspension. The separated solid is solid B2 and the liquid is liquid C2. Wash and dry solid B2 to obtain calcium sulfate. Step 4: Add clean acid to liquid C2 at a flow rate of 5L / min. When the pH reaches 7, let it mature for 30 minutes before solid-liquid separation. Wash the separated solid and let the wash water enter the mother liquor C1. Dry the washed solid to obtain precipitated silica. The separated liquid is sodium sulfate solution and is sent to the sixth collection tank M6. Step 5: Pump the mother liquor C1 into the reaction tank for reaction maturation, and then enter the separation system for separation. Further recovery is carried out on the metal hydroxide precipitate of the separated single metal element.

[0018] The working steps of the separation system are: (a) Pump the mother liquor C1 into the primary reaction tank G1, and introduce 30% NaOH solution into it to control the pH to 2.5. Heat to boiling and let the reaction mature for 0.5 hours before entering the primary separator H1. (ii) The solid slurry separated by the primary separator H1 is metatitanic acid. The metatitanic acid is sent to the first collection tank M1, and the filtrate enters the secondary reaction tank G2. 30% NaOH solution and 500 kg of hydrogen peroxide are added to the reaction tank G2 simultaneously, and the pH is controlled at 3.8. After the reaction is complete, it is allowed to mature for 0.5 h, and then enters the secondary separator H2 for solid-liquid separation. The separated solid is a precipitated slurry of basic ferric hydroxide. The precipitated slurry is sent to the second collection tank M2, and the separated filtrate is sent to the tertiary reaction tank G3. (iii) Liquid alkali is introduced into the three-stage reaction tank G3 to adjust the pH value to 4.5. After the reaction is complete, it is matured for 0.5 hours and then enters the three-stage separator H3 for solid-liquid separation. The separated solid slurry is Al(OH). 3， The filtrate is sent to the third collection tank M3, and the separated filtrate is sent to the fourth reaction tank G4. (iv) Liquid alkali is introduced into the fourth-stage reaction tank G4 to adjust the pH to 9.8, and a large amount of compressed air is introduced to ensure complete reaction. After maturation for 1 hour, it enters the fourth-stage separator H4 for solid-liquid separation. The separated solid slurry is a precipitate of Mn(OH)2. The solid slurry is sent to the fourth collection tank M4, and the separated filtrate is sent to the fifth-stage reaction tank G5; (v) Add liquid alkali to the fifth-stage reaction tank G5, adjust the pH to 12.5, stir thoroughly, and let it mature for 0.5 hours after the reaction is complete. Then it enters the fifth-stage separator H5. The separated Mg(OH)2 precipitate is sent to the fifth collection tank M5, and the separated sodium sulfate solution is sent to the sixth collection tank M6. (vi) Evaporate and crystallize the sodium sulfate solution in the sixth collection tank M6 to obtain the finished sodium sulfate powder.

[0019] The cleaning process of the separation system is as follows: 1. During normal operation, open valve F1 and valve F2, and close the washing water valve F11, slurry valve F12, compressed air valve F13 and washing valve F14. 2. When the flow rate sensor Q detects that the linear velocity of the filtrate flow rate has decreased to 0-0.5 cm / s, it indicates that a certain thickness of sediment filter cake has adhered to the filter screen S, affecting the flow rate. The PLC control automatically closes valves F1 and F2 to clean pipe A, and at the same time switches to another pipe A for operation.

[0020] 3. For the pipe body A that needs to be cleaned, the PLC controls the simultaneous opening of the washing water valve F11 and the washing valve F14. The washing water with a pressure of 0.1-0.3Mpa is used to rinse the filter screen S for 3-5 seconds through the washing water pipe 1. The washing water is then discharged into the washing water collection tank through the washing water collection pipe 4. 4. After the slurry filter cake attached to the feed inlet side of the filter screen S is washed clean, open the slurry valve F12 and the compressed air valve F13, blow air into the filter screen S for 0.2-0.5 seconds to make the slurry filter cake fall off the filter screen S. Close the compressed air valve F13, open the washing water valve F11 to flush with water for 0.2 seconds, close the washing water valve F11, and the slurry filter cake that has fallen off by backflushing is flushed into the collection tank. The self-cleaning of pipeline A is completed.

Claims

1. A method for preparing silica and separating metal hydroxides from yellow phosphorus solid waste and titanium dioxide waste acid, characterized in that, Includes the following steps: Step 1: Pass the waste acid from titanium dioxide through an ion exchange membrane to obtain clean acid, and collect it for later use; Step 2: Add the yellow phosphorus solid waste calcium silicate slag to the titanium dioxide waste acid in a certain proportion, control the reaction temperature to avoid the formation of silica gel, and separate after the reaction. The separated solid is solid B1 and the liquid is mother liquor C1. Step 3: Wash solid B1 and grind it into a slurry. Add liquid alkali to react and obtain a suspension. Separate the suspension. The separated solid is solid B2 and the liquid is liquid C2. Wash and dry solid B2 to obtain calcium sulfate. Step 4: Pass clean acid into liquid C2, controlling the flow rate at 4-6 L / min. After precipitate is formed, let it mature for 0.5-3 hours before solid-liquid separation. Wash the separated solid and then dry it to obtain precipitated silica. The separated liquid is sodium sulfate solution, which is sent to the collection tank. Step 5: The mother liquor C1 is pumped into a reaction tank for reaction maturation, and then enters the separation system for separation. The metal hydroxide precipitates of the separated single metal elements are further recovered; specifically: (a) Pump the mother liquor C1 into the primary reaction tank (G1) and introduce liquid alkali into it, control the pH to 2-3, heat to boiling, and after aging for 0.5-1 hours, enter the primary separator (H1). (ii) The solid slurry separated by the primary separator (H1) is metatitanic acid. The metatitanic acid is sent to the first collection tank (M1), and the filtrate enters the secondary reaction tank (G2). Liquid alkali and hydrogen peroxide are added to the secondary reaction tank (G2) at the same time, and the pH is controlled at 3.8-4.

1. After the reaction is complete, it is aged for 0.5-1 hours and then enters the secondary separator (H2) for solid-liquid separation. The separated solid is a precipitated slurry of basic ferric hydroxide. The precipitated slurry is sent to the second collection tank (M2), and the separated filtrate is sent to the tertiary reaction tank (G3). (iii) Liquid alkali is introduced into the three-stage reaction tank (G3) to adjust the pH value to 4.5-6. After the reaction is complete, it is allowed to mature for 0.5-1 hour, and then enters the three-stage separator (H3) for solid-liquid separation. The separated solid slurry is Al(OH). 3， The filtrate is sent to the third collection tank (M3), and the separated filtrate is sent to the fourth reaction tank (G4). (iv) Pour liquid alkali into the fourth-stage reaction tank (G4) to adjust the pH to 9.8-10.5, and purge with a large amount of compressed air to ensure complete reaction. After maturation for 1-1.5 hours, it enters the fourth-stage separator (H4) for solid-liquid separation. The separated solid slurry is a precipitate of Mn(OH)2. The solid slurry is sent to the fourth collection tank (M4), and the separated filtrate is sent to the fifth-stage reaction tank (G5). (v) Add liquid alkali to the fifth-stage reaction vessel (G5), adjust the pH to not less than 12.5, stir thoroughly, and let it mature for 0.5-1h after the reaction is complete, and then enter the fifth-stage separator (H5). The separated Mg(OH)2 precipitate is sent to the fifth collection tank (M5), and the separated sodium sulfate solution is sent to the sixth collection tank (M6). (vi) Evaporate and crystallize the sodium sulfate solution in the sixth collection tank (M6) to obtain the finished sodium sulfate powder.

2. The method for preparing silica and separating metal hydroxides from yellow phosphorus solid waste and titanium dioxide waste acid according to claim 1, characterized in that, In step two, the mass ratio of titanium dioxide waste acid to calcium silicate slag is 5-7; the reaction temperature is controlled at 80-100℃.

3. The method for preparing silica and separating metal hydroxides from yellow phosphorus solid waste and titanium dioxide waste acid according to claim 1, characterized in that, In step three, the amount of liquid alkali added is based on the mass ratio M. 30%氢氧化钠 M 钙硅渣酸解后粉体 The value ranges from 2.33 to 5.67; the wash water from washing solid B1 enters the mother liquor C1.

4. The method for preparing silica and separating metal hydroxides from yellow phosphorus solid waste and titanium dioxide waste acid according to claim 1, characterized in that, In step four, the wash water used to wash the solid separated from the solid-liquid mixture is introduced into the mother liquor C1.

5. The method for preparing silica and separating metal hydroxides from yellow phosphorus solid waste and titanium dioxide waste acid according to any one of claims 1-4, characterized in that, The separation system includes a first-stage separator (H1), a second-stage separator (H2), a third-stage separator (H3), a fourth-stage separator (H4), and a fifth-stage separator (H5) connected in series and having the same structure; the separation system is controlled by a PLC.

6. The method for preparing silica and separating metal hydroxides from yellow phosphorus solid waste and titanium dioxide waste acid according to claim 5, characterized in that, The first-stage separator (H1), second-stage separator (H2), third-stage separator (H3), fourth-stage separator (H4), and fifth-stage separator (H5) each include three identical tubes (A), with two tubes (A) working alternately and one tube (A) as an emergency backup. One end of the pipe body (A) is the inlet (A1) connected to the slurry pipe, and the other end is the outlet (A2) connected to the filtrate pipe. The inlet (A1) end of the pipe body (A) is equipped with valve No. 1 (F1). At the same time, the upper part of the pipe body (A) is connected to the washing water pipe (1) and the lower part is connected to the sedimentation slurry pipe (2). The outlet (A2) end is equipped with valve No. 2 (F2). At the same time, the upper part of the pipe body (A) is connected to the compressed air pipe (3) and the lower part is connected to the washing water collection pipe (4).

7. The method for preparing silica and separating metal hydroxides from yellow phosphorus solid waste and titanium dioxide waste acid according to claim 6, characterized in that, The pipe body (A) is equipped with a filter screen (S) and a flow rate sensor (Q) in the middle; the washing water pipe (1) is equipped with a washing water valve (F11), the sedimentation slurry pipe (2) is equipped with a slurry valve (F12), the compressed air pipe (3) is equipped with a compressed air valve (F13), and the washing water collection pipe (4) is equipped with a washing valve (F14). When the flow rate sensor (Q) detects that the linear velocity of the filtrate flow rate has decreased to 0-0.5 cm / s, it indicates that a certain thickness of sediment cake has adhered to the filter screen (S), affecting the flow rate. The PLC control automatically closes valves 1 (F1) and 2 (F2) to clean the tube (A) and simultaneously switches to another tube (A) for operation.

8. The method for preparing silica and separating metal hydroxides from yellow phosphorus solid waste and titanium dioxide waste acid according to claim 7, characterized in that, The cleaning process is as follows: the PLC controls the simultaneous opening of the washing water valve (F11) and the washing valve (F14), and the washing water with a pressure of 0.1-0.3Mpa is used to rinse the filter screen (S) for 3-5 seconds through the washing water pipe (1). The washing water is then discharged into the washing water collection tank through the washing water collection pipe (4). After the slurry filter cake attached to the feed inlet side of the filter screen (S) is washed clean, open the slurry valve (F12) and the compressed air valve (F13), blow air onto the filter screen (S) for 0.2-0.5 seconds to make the slurry filter cake fall off the filter screen (S), close the compressed air valve (F13), open the washing water valve (F11) to flush with water for 0.2 seconds, close the washing water valve (F11), and the slurry filter cake that has been backflushed off is flushed into the collection tank, and the self-cleaning of the pipeline (A) is completed.

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