CN110980903A - Preparation method of poly-aluminum ferric silicate flocculant for pretreatment of coking wastewater - Google Patents
Preparation method of poly-aluminum ferric silicate flocculant for pretreatment of coking wastewater Download PDFInfo
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- CN110980903A CN110980903A CN201911313188.4A CN201911313188A CN110980903A CN 110980903 A CN110980903 A CN 110980903A CN 201911313188 A CN201911313188 A CN 201911313188A CN 110980903 A CN110980903 A CN 110980903A
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- aluminum
- flocculant
- coking wastewater
- iron
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/52—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities
- C02F1/5236—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities using inorganic agents
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B33/00—Silicon; Compounds thereof
- C01B33/20—Silicates
- C01B33/26—Aluminium-containing silicates, i.e. silico-aluminates
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2103/00—Nature of the water, waste water, sewage or sludge to be treated
- C02F2103/34—Nature of the water, waste water, sewage or sludge to be treated from industrial activities not provided for in groups C02F2103/12 - C02F2103/32
Abstract
In the preparation method of the polyaluminum ferric silicate flocculant for pretreatment of coking wastewater, the polyaluminum ferric silicate flocculant is prepared by performing acid leaching and alkali leaching on coal gangue powder and polymerizing acid leaching solution and alkali leaching solution254The removal rate of COD and DOC can achieve better effect, the usage amount is small, and the coagulated water can reach the standard discharge and meet the requirement of subsequent treatment.
Description
Technical Field
The invention relates to the field of environmental protection, in particular to a preparation method of a polysilicate aluminum ferric flocculant for pretreatment of coking wastewater.
Background
The coal gangue is one of the solid wastes with the largest yield in China, the comprehensive utilization degree of the coal gangue is lower at present, and a large amount of piled gangue not only occupies the land, but also causes great harm to the ecological environment. However, the main component of the coal gangue is SiO2，Al2O3，Fe2O3And the like, and meets the raw material requirement of preparing the polysilicate flocculant.
The coking wastewater is high-concentration organic wastewater generated in the coking or gas making process of a coking plant, a certain concentration of refractory organic pollutants is still remained after biochemical treatment, and the coking wastewater mainly contains soluble organic matters and has higher polarity. The traditional flocculating agent has low removal efficiency on the organic matters, so that the consumption of the flocculating agent is large, the effluent quality is poor, and the standard discharge or the follow-up treatment requirement is difficult to meet in the flocculation treatment process of the coking wastewater. The polysilicate flocculant serving as a novel inorganic polymeric flocculant has good charge neutralization, adsorption bridging and net capturing capabilities, and has good potential on removing organic matters; meanwhile, the raw material source is wide, and the solid silicate wastes such as fly ash, coal gangue, metal tailings and the like can meet the requirements, so that the method has important significance for improving the comprehensive utilization rate of the solid silicate wastes.
However, the current research on the flocculation performance of polysilicate flocculants mainly focuses on indexes such as turbidity removal, color removal and COD removal, and the deep research on the removal characteristics of the flocculants on various organic matter components in wastewater is reported; and due to the difference of raw materials and water quality, the optimal proportion of the flocculant synthesized by various researchers is not consistent. Common flocculating agents (such as polyaluminium chloride, polyferric chloride and the like) have the defects of large usage amount, poor removal effect on difficultly-degraded organisms and difficulty in standard discharge of coagulated effluent or meeting the requirement of subsequent treatment, so that the development of novel flocculating agents is an urgent need for pretreatment of coking wastewater.
Disclosure of Invention
The invention provides a novel high-efficiency flocculant preparation method suitable for coking wastewater, aiming at the current situations that the traditional coagulant is large in dosage, poor in effect of removing difficultly-biodegradable organic matters, and difficult to discharge the coagulated effluent up to the standard or meet the subsequent treatment requirement.
The invention provides a preparation method of a polysilicate aluminum ferric flocculant for pretreatment of coking wastewater, which comprises the following steps:
(1) crushing and grinding a certain amount of coal gangue, and then sieving to obtain coal gangue powder with a particle size of less than 80 meshes for later use;
(2) placing the screened coal gangue powder into a muffle furnace, calcining and activating for a certain time at a certain calcining temperature, cooling to room temperature, adding 20 wt% hydrochloric acid for acid leaching, and filtering to separate solid from liquid after the acid leaching is finished, wherein the filtrate is an acid leaching solution, and filter residues are washed to be neutral by deionized water;
(3) drying the washed filter residue at the temperature of 100-120 ℃ for 2h, and then carrying out alkali leaching on silicon by using a sodium hydroxide solution, wherein the filtrate is an alkali leaching solution;
(4) slowly adding 2mol/L hydrochloric acid into the alkali immersion liquid under magnetic stirring at 25 ℃ until the pH is 4-5, and activating silicic acid;
(5) when the solution begins to turn light blue, adding pickle liquor containing aluminum and iron ions, adding a small amount of ferric chloride and aluminum chloride to adjust the molar ratio of aluminum/iron/silicon, and finally placing the solution in a constant-temperature water bath kettle at the temperature of 30 ℃ for curing for 10 hours to obtain the polysilicate aluminum ferric flocculant.
Compared with the prior art, the polyaluminum ferric silicate flocculant is prepared by performing acid leaching and alkali leaching on coal gangue powder and polymerizing acid leaching solution and alkali leaching solution, and the preparation method has the advantages of simple preparation process and convenience in operation, and the polyaluminum ferric silicate flocculant can be used for treating chroma, turbidity and UV (ultraviolet) of coking wastewater254The removal rate of COD and DOC can achieve better effect, the usage amount is small, and the coagulated water can reach the standard discharge and meet the requirement of subsequent treatment.
Further, the aluminum/iron molar ratio is 1-9, the (aluminum + iron)/silicon molar ratio is 5-17, and the polyaluminum ferric silicate flocculants with different aluminum/iron molar ratios and (aluminum + iron)/silicon molar ratios can be used for preparing the polyaluminum ferric silicate flocculants with different flocculation effects, so that the polyaluminum ferric silicate flocculants are suitable for pretreatment of coking wastewater with different flocculation requirements.
Further, the calcination temperature of the muffle furnace is 750-850 ℃.
Further, the calcination activation time of the muffle furnace is 2-4 h.
Furthermore, when the polyaluminum ferric silicate flocculant is used for treating the coking wastewater, the adding amount of the polyaluminum ferric silicate flocculant is 25-200mg/L, the flocculation performances of the coking wastewater are different due to the adding amount of different polyaluminum ferric silicate flocculants, and the optimal adding amount of the polyaluminum ferric silicate flocculant can be selected under a certain cost condition in the actual application.
Detailed Description
For a further understanding of the invention, reference will now be made to the preferred embodiments of the invention by way of example, and it is to be understood that the description is intended to further illustrate features and advantages of the invention, and not to limit the scope of the claims.
Example one
The preparation method of the polysilicate aluminum ferric flocculant for pretreatment of the coking wastewater comprises the following steps:
(1) crushing and grinding 100g of coal gangue, and then screening to obtain coal gangue powder with the granularity of less than 80 meshes for later use;
(2) putting 50g of screened coal gangue powder into a muffle furnace, calcining and activating for 2h at the calcining temperature of 800 ℃, then cooling to room temperature, adding 20 wt% hydrochloric acid for acid leaching, and filtering to separate solid and liquid after the acid leaching is finished, wherein the filtrate is acid leaching solution, and filter residue is washed to be neutral by deionized water;
(3) drying the washed filter residue at 110 ℃ for 2h, and then carrying out alkali leaching on silicon by using a sodium hydroxide solution, wherein the filtrate is an alkali leaching solution;
(4) slowly adding 2mol/L hydrochloric acid into the alkali immersion liquid until the pH is 4.5 under magnetic stirring at 25 ℃ to activate silicic acid;
(5) when the solution starts to turn light blue, adding pickle liquor containing aluminum and iron ions, adding ferric chloride and aluminum chloride to adjust the molar ratio of aluminum to iron to be 3: 1 and 5: and 1, finally, placing the solution in a constant-temperature water bath kettle at the temperature of 30 ℃ for curing for 10 hours to obtain the polysilicate aluminum ferric flocculant.
The flocculation effect of the obtained polysilicate aluminum ferric flocculant on coking wastewater is tested, and the test results are as follows: the aluminum/iron molar ratio is 3: 1 hour, color, COD, UV254The removal rates are 67.8%, 45.1% and 41.3% respectively; the aluminum/iron molar ratio is 5: 1 hour, color, COD, UV254The removal rates were 71.6%, 48.2%, and 42.5%, respectively. This may be related to the properties of the aluminium salt, iron salt flocculants themselves. The aluminum salt has good decoloring effect and poor settleability, and the iron salt is opposite; meanwhile, the flocculant has more advantages in removing iron salt flocculant with a conjugated structure and unsaturated organic matters. Thereby causing the color removal and the removal of COD and UV254The optimal mixture ratio is not consistent. However, too high or too low molar ratio of aluminum to iron is not good in flocculation effect because of the synergistic effect of aluminum and iron in the flocculation process, and the proper ratio is favorable for achieving the best effect.
Example two
The preparation method of the polysilicate aluminum ferric flocculant for pretreatment of the coking wastewater comprises the following steps:
(1) crushing and grinding 100g of coal gangue, and then screening to obtain coal gangue powder with the granularity of less than 80 meshes for later use;
(2) putting 50g of screened coal gangue powder into a muffle furnace, calcining and activating for 2h at the calcining temperature of 800 ℃, then cooling to room temperature, adding 20 wt% hydrochloric acid for acid leaching, and filtering to separate solid and liquid after the acid leaching is finished, wherein the filtrate is acid leaching solution, and filter residue is washed to be neutral by deionized water;
(3) drying the washed filter residue at 110 ℃ for 2h, and then carrying out alkali leaching on silicon by using a sodium hydroxide solution, wherein the filtrate is an alkali leaching solution;
(4) slowly adding 2mol/L hydrochloric acid into the alkali immersion liquid until the pH is 4.5 under magnetic stirring at 25 ℃ to activate silicic acid;
(5) when the solution started to turn light blue, the pickle liquor containing aluminium and iron ions was added and ferric chloride and aluminium chloride were added to adjust the (aluminium + iron)/silicon molar ratio to 7: 1 and 13: and 1, finally, placing the solution in a constant-temperature water bath kettle at the temperature of 30 ℃ for curing for 10 hours to obtain the polysilicate aluminum ferric flocculant.
The flocculation effect of the obtained polysilicate aluminum ferric flocculant on coking wastewater is tested, and the test results are as follows: (aluminum + iron)/silicon molar ratio of 7: 1 hour, color, COD, UV254The removal rates are 66.7%, 52.3% and 41.7% respectively; (aluminum + iron)/silicon molar ratio 13: 1 hour, color, COD, UV254The removal rates were 72.1%, 51.9%, and 41.2%, respectively.
Combining the first and second examples, the optimum aluminum/iron molar ratio of the polyaluminum ferric silicate flocculant can be determined to be 3: 1, the optimum (aluminum + iron)/silicon molar ratio is 13: 1.
EXAMPLE III
The preparation method of the polysilicate aluminum ferric flocculant for pretreatment of the coking wastewater comprises the following steps:
(1) crushing and grinding 100g of coal gangue, and then screening to obtain coal gangue powder with the granularity of less than 80 meshes for later use;
(2) putting 50g of screened coal gangue powder into a muffle furnace, calcining and activating for 2h at the calcining temperature of 800 ℃, then cooling to room temperature, adding 20 wt% hydrochloric acid for acid leaching, and filtering to separate solid and liquid after the acid leaching is finished, wherein the filtrate is acid leaching solution, and filter residue is washed to be neutral by deionized water;
(3) drying the washed filter residue at 110 ℃ for 2h, and then carrying out alkali leaching on silicon by using a sodium hydroxide solution, wherein the filtrate is an alkali leaching solution;
(4) slowly adding 2mol/L hydrochloric acid into the alkali immersion liquid until the pH is 4.5 under magnetic stirring at 25 ℃ to activate silicic acid;
(5) when the solution starts to turn light blue, adding pickle liquor containing aluminum and iron ions, adding ferric chloride and aluminum chloride to adjust the molar ratio of aluminum to iron to be 3: 1, (aluminum + iron)/silicon molar ratio 13: and 1, finally, placing the solution in a constant-temperature water bath kettle at the temperature of 30 ℃ for curing for 10 hours to obtain the polysilicate aluminum ferric flocculant.
The obtained polysilicate aluminum ferric flocculant is added into the coking wastewater in the adding amount of 25mg/L, 50mg/L and 125mg/L, the flocculation effect test is respectively carried out, and the results are as follows: the turbidity removal is the best when the adding amount is 25mg/L, the removal rate can reach 94 percent, and the removal rate is 89 percent when the adding amount is 150 mg/L; the removal rate of COD is increased firstly and reaches a maximum value of 54.3 percent at 125 mg/L; DOC and UV254The removal rate of (D) is increased along with the increase of the adding amount, and reaches 34.5 percent and 50.1 percent respectively at the adding amount of 125 mg/L. Comprehensively considering, the optimal adding amount of the polysilicate aluminum ferric flocculant is determined to be 125 mg/L.
Claims (5)
1. The preparation method of the polysilicate aluminum ferric flocculant for pretreatment of the coking wastewater comprises the following steps:
(1) crushing and grinding a certain amount of coal gangue, and then sieving to obtain coal gangue powder with a particle size of less than 80 meshes for later use;
(2) placing the screened coal gangue powder into a muffle furnace, calcining and activating for a certain time at a certain calcining temperature, cooling to room temperature, adding 20 wt% hydrochloric acid for acid leaching, and filtering to separate solid from liquid after the acid leaching is finished, wherein the filtrate is an acid leaching solution, and filter residues are washed to be neutral by deionized water;
(3) drying the washed filter residue at the temperature of 100-120 ℃ for 2h, and then carrying out alkali leaching on silicon by using a sodium hydroxide solution, wherein the filtrate is an alkali leaching solution;
(4) slowly adding 2mol/L hydrochloric acid into the alkali immersion liquid under magnetic stirring at 25 ℃ until the pH is 4-5, and activating silicic acid;
(5) when the solution begins to turn light blue, adding pickle liquor containing aluminum and iron ions, adding a small amount of ferric chloride and aluminum chloride to adjust the molar ratio of aluminum/iron/silicon, and finally placing the solution in a constant-temperature water bath kettle at the temperature of 30 ℃ for curing for 10 hours to obtain the polysilicate aluminum ferric flocculant.
2. The method for preparing the polyaluminum ferric silicate flocculant for coking wastewater according to claim 1, wherein the aluminum/iron molar ratio is 1 to 9, and the (aluminum + iron)/silicon molar ratio is 5 to 17.
3. The preparation method of the polyaluminum ferric silicate flocculant for coking wastewater as claimed in claim 1, wherein the muffle furnace has a calcination temperature of 750-850 ℃.
4. The method for preparing the polyaluminum ferric silicate flocculant for coking wastewater according to claim 1, wherein the calcination activation time of the muffle furnace is 2-4 h.
5. The method for preparing the polyaluminum ferric silicate flocculant for coking wastewater according to claim 1, wherein the dosage of the polyaluminum ferric silicate flocculant used for treating coking wastewater is 25-200 mg/L.
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| CN115465869A (en) * | 2022-10-31 | 2022-12-13 | 陕西科技大学 | Method for preparing calcium iron polysilicate from gasified slag |
| CN115504555A (en) * | 2022-09-27 | 2022-12-23 | 齐鲁工业大学 | Coal gasification slag-based composite ferric aluminum silicate flocculant and preparation method and application thereof |
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| CN115465869A (en) * | 2022-10-31 | 2022-12-13 | 陕西科技大学 | Method for preparing calcium iron polysilicate from gasified slag |
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