Process and system for treating waste salt slurry produced in production of sodium chlorate

[0026] Example 1:

[0027] Such as figure 1 As shown, the treatment system for waste salt sludge in the production of sodium chlorate includes a grinder 1, an oxidation dissolution system, a washing system, a reduction system, and a waste water regulating tank 17, the discharge port of the grinder 1 and the oxidation dissolution of the oxidation dissolution system The feed inlet of the reaction tank 2 is connected, the outlet of the water collection tank 7 of the oxidation dissolution system is connected with the inlet of the reduction reaction tank 13 of the reduction system, and the outlet of the reduction centrifuge 15 of the reduction system is connected with the water inlet of the wastewater regulating tank 17 , The outlet of the waste water regulating tank 17 is connected with the incoming water line 18 of the wastewater plant, the slag outlet of the oxidizing dissolution centrifuge 6 of the oxidation dissolution system is connected with the inlet of the slag collecting tank 8 of the washing system, and the outlet of the slag collecting tank 8 is connected with The inlet of the washing centrifuge 10 is connected, and the water outlet of the washing centrifuge 10 is respectively connected with the water inlet of the oxidation dissolution reaction tank 2 and the inlet of the water collection tank 7 through a three-way valve.

[0028] The oxidation dissolution system includes oxidation dissolution reaction tank 2, oxidant storage tank 3, dissolution agent storage tank 4, water supply pipeline 5, oxidation dissolution centrifuge 6 and water collection tank 7, oxidation dissolution reaction tank 2 is a pressurized stirred tank, oxidation dissolution reaction tank The water inlet of 2 is connected with the water supply pipeline 5. The oxidation dissolution reaction tank 2 is respectively connected with the oxidant storage tank 3 and the dissolution agent storage tank 4 through pipelines. The pipeline between the oxidation dissolution reaction tank 2 and the oxidant storage tank 3 is equipped with oxidation control The pipeline between the oxidation dissolution reaction tank 2 and the dissolution agent storage tank 4 is provided with a dissolution control valve. The outlet of the oxidation dissolution reaction tank 2 is connected with the inlet of the oxidation dissolution centrifuge 6, and the outlet of the oxidation dissolution centrifuge 6 is connected with The inlet of the water collection tank 7 is connected.

[0029] The washing system includes a slag collecting tank 8, a washing centrifuge 10, and a dechromating filter residue storage tank 12. The water inlet of the slag collecting tank 8 is connected with the hot water outlet of the electrolytic heat exchanger 9 of the sodium chlorate production system, and the slag collecting tank 8 The outlet is in communication with the inlet of the washing centrifuge 10, the flushing water inlet of the washing centrifuge 10 is in communication with the flushing water pipeline 11, and the residue outlet of the washing centrifuge 10 is in communication with the inlet of the dechromating filter residue storage tank 12.

[0030] The reduction system includes a reduction reaction tank 13, a reducing agent storage tank 14, a reduction centrifuge 15 and a chromium hydroxide storage tank 16. The reduction reaction tank 13 and the reducing agent storage tank 14 are connected through a pipeline, and the reduction reaction tank 13 and the reducing agent storage tank 14 A reduction control valve is provided on the pipeline between, the outlet of the reduction reaction tank 13 is connected with the inlet of the reduction centrifuge 15, and the slag outlet of the reduction centrifuge 15 is connected with the inlet of the chromium hydroxide storage tank 16.

[0031] work process:

[0032] (1) Waste salt sludge grinding: transport the waste salt sludge to the grinder 1 to grind to obtain the grinding material; the purpose of grinding is to fully release the chromium ions wrapped in the waste salt sludge to improve the efficiency of subsequent oxidation, dissolution and reduction .

[0033] (2) Oxidation: (1) After the waste salt sludge grinding is completed, the ground material is transported to the oxidation dissolution reaction tank 2, and water is added to the oxidation dissolution reaction tank 2 through the water supply line 5, and after the mixing is uniform, it is oxidized through the oxidant storage tank 3 Oxidant is added to the dissolution reaction tank 2, and the oxidation reaction is carried out at a temperature of 20°C and a pressure of 0.5MPa. The oxidation reaction time is 2h. After the oxidation reaction is completed, an oxidation slurry is obtained; the function of oxidation is to pass trivalent chromium ions through The oxidant is oxidized to hexavalent chromium ions, and the oxidation reaction is carried out under pressurized conditions, which can promote the oxidation reaction, so that the oxidation reaction proceeds more thoroughly and the oxidation reaction efficiency is higher.

[0034] (3) Chromium ion dissolution: (2) After the oxidation is completed, add the hexavalent chromium ion dissolution agent to the oxidation slurry through the dissolution agent storage tank 4, and stir uniformly under the conditions of a temperature of 50°C and a pressure of 0.5 MPa to make The hexavalent chromium ions are dissolved, and the stirring time is 0.5h. After the stirring, the materials are transported to the oxidation dissolution centrifuge 6 for solid-liquid separation to obtain filter residue and filtrate; the purpose of dissolution is to remove the hexavalent chromium ions in the oxidation slurry The dissolution can improve the dissolution under pressure, which can increase the dissolution rate of hexavalent chromium ions, thereby increasing the recovery rate of chromium ions and the dechromization rate of waste salt mud.

[0035] (4) Washing: (3) After the dissolution of chromium ions is completed, the filter residue is transported to the residue collecting tank 8, and washing water is added to the residue collecting tank 8 through the electrolytic heat exchanger 9 of the sodium chlorate production system. Washing is carried out at a temperature of 20℃, and the number of washings is 2 times. After washing, the material is transported to the washing centrifuge 10 for solid-liquid separation to obtain washing filtrate and dechromium filter residue; the purpose of washing is to remove hexavalent chromium ions from The filter residue after the dissolution treatment is fully removed for the next reduction treatment; the washing water used for washing comes from the hot water produced by the electrolytic heat exchanger 9 of the sodium chlorate production system, and there is no need to heat the washing water during washing. , It reduces the energy and water consumption of the system, and the processing cost is lower; in (4) washing, the dechromated filter residue obtained after solid-liquid separation is tested in the environmental protection comprehensive utilization standard (HJ/T301-2007). The test result of the standard (HJ/T301-2007) is unqualified, and flushing water is passed into the washing centrifuge 10 through the flushing water pipeline 11, and the flushing water washes the dechromium filter residue until the dechromium filter residue is tested for environmental protection comprehensive utilization standards After the result is qualified, the dechromium filter residue is transported to the dechromium filter residue storage tank 12 for storage; the purpose of testing the dechromium filter residue is to ensure that the content of hexavalent chromium ion in the dechromium filter residue does not exceed the requirements of the national standard. According to the requirements of utilization, it can be used in the production of coatings, refractories, etc., without causing secondary pollution; the flushing water after washing is returned to the oxidation dissolution reaction tank 2 to prepare oxidation slurry, reducing the water consumption of the oxidation reaction, and saving Up water resources.

[0036] (5) Reduction: (4) After the washing is completed, the filtrate obtained in (3) the chromium ion dissolution and the washing filtrate obtained in (4) the washing are transported to the water collection tank 7 to be mixed to obtain a mixed liquid, and the mixed liquid is transported to reduction In the reaction tank 13, the reducing agent is added to the reduction reaction tank 13 through the reducing agent storage tank 14. After mixing uniformly, the reduction reaction is carried out at a temperature of 20°C, and the reduction reaction time is 1 h. After the reduction reaction is completed, the reduction is carried out by centrifugation. The machine 15 performs solid-liquid separation to obtain chromium hydroxide precipitation and waste water to be discharged. The chromium hydroxide is transported to the chromium hydroxide storage for storage, and the waste water to be discharged is transported to the wastewater conditioning tank 17; the purpose of reduction is to remove (3) chromium ion The hexavalent chromium ion in the filtrate obtained in the dissolution and the washing filtrate obtained in (4) washing is reduced to chromium hydroxide by a reducing agent. The chromium hydroxide can be recovered and sold outside, which makes the operation of the production enterprise more diversified and increases The income of production enterprises. (5) During reduction, adjust the pH value of the wastewater to be discharged to 6, and test the wastewater to be discharged after the pH value is adjusted according to CJ3082-1999, and send it to the wastewater pipeline 18 after passing the test. The waste water to be discharged is directly transported to the waste water plant for treatment through the inflow line 18 of the waste water plant, instead of being returned to the sodium chlorate production system. On the one hand, waste water treatment procedures can be omitted and waste water treatment costs can be saved; on the other hand, perchlorate is avoided The ions and metal ions then return to the sodium chlorate production system, causing system equipment damage and reducing safety accidents.

[0037] Example 2:

[0038] The treatment process of waste salt sludge in the production of sodium chlorate in Example 1 includes the following steps: (1) grinding of waste salt sludge, (2) oxidation, (3) chromium ion extraction, (4) washing, (5) ) Reduction; where,

[0039] (1) Grinding of waste salt sludge: Grind waste salt sludge to 50 meshes to obtain grinding material; the purpose of grinding is to fully release the chromium ions wrapped in waste salt sludge to improve the efficiency of subsequent oxidation, dissolution and reduction.

[0040] (2) Oxidation: (1) After the waste salt sludge is ground, the ground material and water are mixed in a mass ratio of 1:0.5. After the mixing is uniform, the oxidant is added and the temperature is 20°C and the pressure is 0.5MPa. The oxidation reaction is carried out under conditions, the oxidant is permanganate, the mass ratio of oxidant to abrasive is 1:15, and the oxidation reaction time is 2h. After the oxidation reaction is completed, an oxidation slurry is obtained; the role of oxidation is to remove trivalent chromium ions By oxidizing the oxidant to hexavalent chromium ions, the oxidation reaction is carried out under pressurized conditions, which can promote the oxidation reaction, so that the oxidation reaction proceeds more thoroughly and the oxidation reaction efficiency is higher.

[0041] (3) Chromium ion dissolution: (2) After the oxidation is completed, add hexavalent chromium ion dissolution agent to the oxidation slurry. The hexavalent chromium ion dissolution agent is sodium bicarbonate, and the mass ratio of the hexavalent chromium ion dissolution agent to the abrasive It is 1:1. Stir uniformly at a temperature of 50°C and a pressure of 0.5MPa to dissolve hexavalent chromium ions. The stirring time is 0.5h. After the stirring is completed, solid-liquid separation is performed to obtain filter residue and filtrate; The purpose is to dissolve the hexavalent chromium ions in the oxidized slurry, and improve the dissolution under pressure, which can increase the dissolution rate of hexavalent chromium ions, thereby increasing the recovery rate of chromium ions and the dechromization rate of waste salt mud.

[0042] (4) Washing: (3) After the dissolution of chromium ions is completed, the filter residue and the washing water are mixed in a mass ratio of 1:1. After the mixing is uniform, the washing is carried out at a temperature of 20°C, and the number of washings is 2 After washing, solid-liquid separation is carried out to obtain washing filtrate and dechromium filter residue; the purpose of washing is to fully remove hexavalent chromium ions from the filter residue after dissolution treatment for the next reduction treatment; washing used for washing The water comes from the hot water produced by the electrolytic heat exchanger 9 of the sodium chlorate production system. There is no need to heat the washing water during washing, which reduces the energy consumption of the system; in (4) washing, the solid-liquid separation is obtained. The dechromium filter residue is tested in the environmental protection comprehensive utilization standard (HJ/T301-2007). If the test result of the environmental protection comprehensive utilization standard (HJ/T301-2007) is unqualified, the dechromium filter residue is rinsed with flushing water until the dechromium filter residue is tested The test result of the environmental protection comprehensive utilization standard is qualified, and its purpose is to ensure that the content of hexavalent chromium ion in the dechrome filter residue does not exceed the national standard. Only such dechrome filter residue meets the requirements for reuse and can be used in the production of coatings, refractories, etc. , Will not cause secondary pollution; the washing water after washing is returned to (2) oxidation, used to prepare oxidation slurry, reducing the water consumption of oxidation reaction and saving water resources.

[0043] (5) Reduction: (4) After washing is completed, mix the filtrate obtained in (3) chromium ion dissolution with the washing filtrate obtained in (4) washing to obtain a mixed solution, add reducing agent and follow the grinding material and reducing agent The mass ratio is 1:15. The reducing agent is ferrous sulfate. After the mixing is uniform, the reduction reaction is carried out at a temperature of 20°C. The reduction reaction time is 1h. After the reduction reaction is completed, solid-liquid separation is carried out. Obtain chromium hydroxide precipitation and waste water to be discharged; the purpose of reduction is to reduce hexavalent chromium ions in the filtrate obtained in (3) chromium ion dissolution and (4) washing filtrate obtained in washing to chromium hydroxide through a reducing agent, Chromium hydroxide can be recycled and sold outside, which makes the operation of production enterprises diversified and increases the income of production enterprises. (5) During the reduction, adjust the pH value of the wastewater to be discharged to 7, and test the wastewater to be discharged after the pH value is adjusted according to CJ3082-1999, and send it to the wastewater pipeline 18 after passing the test. The waste water to be discharged is directly transported to the waste water plant for treatment through the inflow line 18 of the waste water plant, instead of being returned to the sodium chlorate production system. On the one hand, waste water treatment procedures can be omitted and waste water treatment costs can be saved; on the other hand, perchlorate is avoided The ions and metal ions then return to the sodium chlorate production system, causing system equipment damage and reducing safety accidents.

[0044] The total chromium content in the waste salt sludge used in this example is 9400mg/kg. After the treatment, the chromium content of the dechromium filter residue is tested according to the national standard (HJ/T299-2007). The chromium content in the leaching solution 6+ The content is 0mg/L, the total chromium content of the leachate is 2.4mg/L, which meets the environmental protection comprehensive utilization standard (HJ/T301-2007), the reduction and detoxification rate is 99.97%, and the chromium content of the treated waste salt mud is lower than the national standard National environmental protection emission standards.

[0045] Example 3:

[0046] The treatment process of waste salt sludge in the production of sodium chlorate in Example 1 includes the following steps: (1) grinding of waste salt sludge, (2) oxidation, (3) chromium ion extraction, (4) washing, (5) ) Reduction; where,

[0047] (1) Grinding of waste salt sludge: Grind waste salt sludge to 100 meshes to obtain grinding material; the purpose of grinding is to fully release the chromium ions wrapped in waste salt sludge to improve the efficiency of subsequent oxidation, dissolution and reduction.

[0048] (2) Oxidation: (1) After the waste salt sludge is ground, the ground material and water are mixed in a mass ratio of 1:1. After the mixing is uniform, the oxidant is added and the temperature is 30℃ and the pressure is 0.4MPa. The oxidation reaction is carried out under the conditions, the mass ratio of the oxidant to the abrasive is 1:25, the oxidation reaction time is 0.5h, and the oxidant is sodium peroxide. After the oxidation reaction, the oxidation slurry is obtained; the function of oxidation is to pass trivalent chromium ions through The oxidant is oxidized to hexavalent chromium ions, and the oxidation reaction is carried out under pressurized conditions, which can promote the oxidation reaction, so that the oxidation reaction proceeds more thoroughly and the oxidation reaction efficiency is higher.

[0049] (3) Chromium ion dissolution: (2) After the oxidation is completed, add hexavalent chromium ion dissolving agent to the oxidation slurry, the hexavalent chromium ion dissolving agent is ammonium bicarbonate, and the mass ratio of the hexavalent chromium ion dissolution agent to the abrasive 1:1.5. Stir uniformly at a temperature of 90°C and a pressure of 0.4MPa to dissolve hexavalent chromium ions. The stirring time is 0.5h. After the stirring, solid-liquid separation is performed to obtain the filter residue and the filtrate; The purpose is to dissolve the hexavalent chromium ions in the oxidized slurry, and improve the dissolution under pressure, which can increase the dissolution rate of hexavalent chromium ions, thereby increasing the recovery rate of chromium ions and the dechromization rate of waste salt mud.

[0050] (4) Washing: (3) After the dissolution of chromium ions is completed, the filter residue and washing water are mixed in a mass ratio of 1:5. After the mixing is uniform, wash at a temperature of 55°C, and the number of washings is 2 After washing, solid-liquid separation is carried out to obtain washing filtrate and dechromium filter residue; the purpose of washing is to fully remove hexavalent chromium ions from the filter residue after dissolution treatment for the next reduction treatment; washing used for washing The water comes from the hot water produced by the electrolytic heat exchanger 9 of the sodium chlorate production system. There is no need to heat the washing water during washing, which reduces the energy consumption of the system; in (4) washing, the solid-liquid separation is obtained. The dechromation filter residue is tested for the environmental protection comprehensive utilization standard. If the test result of the environmental protection comprehensive utilization standard (HJ/T301-2007) is unqualified, rinse the dechromization filter residue with flushing water until the dechromization filter residue is subject to the environmental protection comprehensive utilization standard (HJ/T301-2007). The test result of T301-2007) is qualified. Its purpose is to ensure that the content of hexavalent chromium ion in the dechromium filter residue does not exceed the requirements of the national standard. Only such dechromium filter residue can meet the requirements for reuse. It can be used to produce coatings, refractories, etc. , Will not cause secondary pollution; the washing water after washing is returned to (2) oxidation, used to prepare oxidation slurry, reducing the water consumption of oxidation reaction and saving water resources.

[0051] (5) Reduction: (4) After washing is completed, mix the filtrate obtained in (3) chromium ion dissolution with the washing filtrate obtained in (4) washing to obtain a mixed solution, add reducing agent and follow the grinding material and reducing agent The mass ratio is 1:20. The reducing agent is sodium sulfide. After the mixing is uniform, the reduction reaction is carried out at a temperature of 60°C. The reduction reaction time is 0.5h. After the reduction reaction is completed, solid-liquid separation is carried out. Obtain chromium hydroxide precipitation and waste water to be discharged. The purpose of reduction is to reduce the hexavalent chromium ions in the filtrate obtained in (3) the chromium ion dissolution and the washing filtrate obtained in (4) washing to chromium hydroxide through a reducing agent. The chromium hydroxide can be recovered and sold. Make the operation of the production enterprise diversified and increase the income of the production enterprise. (5) During the reduction, adjust the pH value of the wastewater to be discharged to 8, and test the wastewater to be discharged after the pH value is adjusted according to CJ3082-1999, and send it to the wastewater pipeline 18 after passing the test. The waste water to be discharged is directly transported to the waste water plant for treatment through the inflow line 18 of the waste water plant, instead of being returned to the sodium chlorate production system. On the one hand, waste water treatment procedures can be omitted and waste water treatment costs can be saved; on the other hand, perchlorate is avoided The ions and metal ions then return to the sodium chlorate production system, causing system equipment damage and reducing safety accidents.

[0052] The total chromium content in the waste salt sludge used in this example is 9400mg/kg. After the treatment, the chromium content of the dechromium filter residue is tested according to the national standard (HJ/T299-2007). The chromium content in the leaching solution 6+ The content is 0mg/L, the total chromium content of the leachate is 1.9mg/L, which meets the environmental protection comprehensive utilization standard (HJ/T301-2007), the reduction and detoxification rate is 99.98%, and the chromium content of the treated waste salt mud is lower than the national standard. National environmental protection emission standards.