Method for treating stainless steel pickling wastewater

Abstract

The invention provides a method for treating stainless steel pickling wastewater and relates to the field of environmental protection. The method comprises the following steps: adjusting the pH of the flushing water to 1-2, adding the first defluorination agent and the second defluorination agent, then standing and filtering to obtain a filter cake and filtrate; adjusting the pH of the filtrate to 2-3 , add iron-removing flocculant, then stand still and filter to obtain filter cake and filtrate; adjust the pH of the filtrate to 4-5, add chromium-removing flocculant, then stand still and filter to obtain filter cake and filtrate; adjust the pH of the filtrate to 6-7, add nickel-removing flocculant, then stand still and filter to obtain filter cake and filtrate; adjust the pH of the filtrate to 7-8, then undergo membrane treatment, concentrated water is treated by three-effect evaporation, and the concentrated liquid is cooled and crystallized. Carry out harmless treatment. Please provide the method to separate and extract each element in the flushing water one by one, so as to achieve the purpose of comprehensive utilization of resources and environmental protection.

Description

technical field

[0001] The invention relates to the field of environmental protection, in particular to a method for treating stainless steel pickling wastewater. Background technique

[0002] The fluorine-containing pickling solution and fluorine-containing acid washing water produced by pickling of stainless steel materials contain elements such as fluorine, iron, chromium, nickel, manganese, etc. After treating fluorine with calcium oxide or calcium chloride, oxidize, add flocculant to precipitate metal ions at one time, filter out, and then process sludge and filtrate.

[0003] The existing technology can treat the wastewater to meet the discharge standard, but all the metal ions are precipitated at one time, which will complicate the subsequent resource recovery and utilization, and the cost is high, and the cost is even higher than the value of the recycled material, which leads to the market. The degree of intention to carry out in-depth resource recovery is not high...

Examples

Embodiment 1

[0036] Take 600g of pickling and flushing water from A stainless steel company, and it contains fluorine after testing: 2.1×10 3 mg / L, containing iron: 5.83×10 3 mg / L, containing chromium: 1.094×10 3 mg / L, containing nickel: 6.344×10 2 mg / L; adjust the pH of the flushing water to 1, add 8 g of calcium chloride and 4 g of potassium aluminum sulfate successively under stirring, continue stirring for 25 minutes after the addition is complete, then let stand for 70 minutes, and filter to obtain the first filtrate, filter The cake was dried at 110°C for 1 hour to obtain 2.4 g of calcium fluoride;

[0037] Adjust the pH of the first filtrate to 2 with a 25% aqueous sodium hydroxide solution, add 0.2 g of polyacrylamide, continue stirring for 15 minutes, then let stand for 15 minutes, and filter to obtain the second filtrate; the filter cake is hydrogen Iron oxide was dried at 110°C and crystallized to obtain 5.1 g of ferric oxide;

[0038] Adjust the pH of the second filtrate to...

Embodiment 2

[0044] Take 600g of pickling and flushing water from B stainless steel company, and it contains fluorine after testing: 1.15×10 3 mg / L, containing iron: 5.483×10 4 mg / L, containing chromium: 1.515×10 3 mg / L, containing nickel: 6.979×10 3 mg / L, containing manganese 4.119×10 2 mg / L; adjust the pH of the flushing water to 2, add 4 g of calcium chloride and 2 g of potassium aluminum sulfate successively under stirring, continue stirring for 30 minutes after the addition is complete, then let stand for 60 minutes, and filter to obtain the first filtrate, filter The cake was dried at 110°C for 1 hour to obtain 1.3 g of calcium fluoride;

[0045] Adjust the pH of the first filtrate to 3 with a 30% potassium hydroxide aqueous solution, add 0.3 g of polyacrylamide, continue to stir for 10 minutes, then let it stand for 50 minutes, and filter to obtain the second filtrate; the filter cake is hydrogen Iron oxide was dried at 110°C and crystallized to obtain 47g of ferric oxide;

[0...

Embodiment 3

[0053] Take 600g of pickling and flushing water from B stainless steel company, and it contains fluorine after testing: 1.15×10 3 mg / L, containing iron: 5.483×10 4 mg / L, containing chromium: 1.515×10 3 mg / L, containing nickel: 6.979×10 3 mg / L, containing manganese 4.119×10 2 mg / L; adjust the pH of the rinse water to 2, add 3.8g of calcium chloride and 2.1g of potassium aluminum sulfate in turn under stirring, continue stirring for 35 minutes after the addition, then stand still for 50 minutes, and filter to obtain the first filtrate , the filter cake was dried at 110°C for 1 hour to obtain 1.25 g of calcium fluoride;

[0054] Adjust the pH of the first filtrate to 3 with a 35% aqueous potassium hydroxide solution, add 0.3 g of polyacrylamide, continue to stir for 5 minutes, then let stand for 60 minutes and filter to obtain the second filtrate; the filter cake is hydrogen Iron oxide was dried at 110°C and crystallized to obtain 46.8g of ferric oxide;

[0055] The pH of th...

technical field

[0001] The invention relates to the field of environmental protection, in particular to a method for treating stainless steel pickling wastewater. Background technique

[0002] The fluorine-containing pickling solution and fluorine-containing acid washing water produced by pickling of stainless steel materials contain elements such as fluorine, iron, chromium, nickel, manganese, etc. After treating fluorine with calcium oxide or calcium chloride, oxidize, add flocculant to precipitate metal ions at one time, filter out, and then process sludge and filtrate.

[0003] The existing technology can treat the wastewater to meet the discharge standard, but all the metal ions are precipitated at one time, which will complicate the subsequent resource recovery and utilization, and the cost is high, and the cost is even higher than the value of the recycled material, which leads to the market. The degree of intention to carry out in-depth resource recovery is not high...

Examples

Embodiment 1

[0036] Take 600g of pickling and flushing water from A stainless steel company, and it contains fluorine after testing: 2.1×10 3 mg / L, containing iron: 5.83×10 3 mg / L, containing chromium: 1.094×10 3 mg / L, containing nickel: 6.344×10 2 mg / L; adjust the pH of the flushing water to 1, add 8 g of calcium chloride and 4 g of potassium aluminum sulfate successively under stirring, continue stirring for 25 minutes after the addition is complete, then let stand for 70 minutes, and filter to obtain the first filtrate, filter The cake was dried at 110°C for 1 hour to obtain 2.4 g of calcium fluoride;

[0037] Adjust the pH of the first filtrate to 2 with a 25% aqueous sodium hydroxide solution, add 0.2 g of polyacrylamide, continue stirring for 15 minutes, then let stand for 15 minutes, and filter to obtain the second filtrate; the filter cake is hydrogen Iron oxide was dried at 110°C and crystallized to obtain 5.1 g of ferric oxide;

[0038] Adjust the pH of the second filtrate to...

Embodiment 2

[0044] Take 600g of pickling and flushing water from B stainless steel company, and it contains fluorine after testing: 1.15×10 3 mg / L, containing iron: 5.483×10 4 mg / L, containing chromium: 1.515×10 3 mg / L, containing nickel: 6.979×10 3 mg / L, containing manganese 4.119×10 2 mg / L; adjust the pH of the flushing water to 2, add 4 g of calcium chloride and 2 g of potassium aluminum sulfate successively under stirring, continue stirring for 30 minutes after the addition is complete, then let stand for 60 minutes, and filter to obtain the first filtrate, filter The cake was dried at 110°C for 1 hour to obtain 1.3 g of calcium fluoride;

[0045] Adjust the pH of the first filtrate to 3 with a 30% potassium hydroxide aqueous solution, add 0.3 g of polyacrylamide, continue to stir for 10 minutes, then let it stand for 50 minutes, and filter to obtain the second filtrate; the filter cake is hydrogen Iron oxide was dried at 110°C and crystallized to obtain 47g of ferric oxide;

[0...

Embodiment 3

[0053] Take 600g of pickling and flushing water from B stainless steel company, and it contains fluorine after testing: 1.15×10 3 mg / L, containing iron: 5.483×10 4 mg / L, containing chromium: 1.515×10 3 mg / L, containing nickel: 6.979×10 3 mg / L, containing manganese 4.119×10 2 mg / L; adjust the pH of the rinse water to 2, add 3.8g of calcium chloride and 2.1g of potassium aluminum sulfate in turn under stirring, continue stirring for 35 minutes after the addition, then stand still for 50 minutes, and filter to obtain the first filtrate , the filter cake was dried at 110°C for 1 hour to obtain 1.25 g of calcium fluoride;

[0054] Adjust the pH of the first filtrate to 3 with a 35% aqueous potassium hydroxide solution, add 0.3 g of polyacrylamide, continue to stir for 5 minutes, then let stand for 60 minutes and filter to obtain the second filtrate; the filter cake is hydrogen Iron oxide was dried at 110°C and crystallized to obtain 46.8g of ferric oxide;

[0055] The pH of th...