CN101337727A - Preparation method of inorganic composite polysilicate aluminum iron chloride flocculant - Google Patents

Abstract

The invention relates to a preparation method of an inorganic composite polysilicate aluminum iron chloride flocculant, which is used in the field of water treatment. The characteristics are as follows: the process is as follows: 1) polysilicic acid activation: adding 5.0-6.0% of inorganic acid by weight to the sodium silicate solution of 11-12% by weight to control the sodium silicate solution The pH of the compound is equal to 7-9, stirring continuously when adding dropwise, and then standing for aging, time: 2-6 hours, to obtain polysilicate; 2) Synthesis: Add inorganic aluminum salt and inorganic iron salt to polysilicate at the same time, Stir constantly when adding, until it is completely dissolved, let stand and mature for 10-15 hours to get polysilicate aluminum iron chloride flocculant. The flocs formed by the invention are large, have good decolorization effect, and the formed flocs are denser and the sedimentation speed is fast.

Description

Preparation method of inorganic composite polysilicate aluminum iron chloride flocculant

1. Technical field

The invention relates to a preparation method of an inorganic composite polysilicate aluminum iron chloride flocculant, which is used in the field of water treatment.

2. Background technology

In the field of water treatment, water purification by flocculation is one of the oldest solid-liquid separation methods. Due to its wide applicability, simple process, and low treatment cost, flocculation is still widely used in drinking water, domestic sewage and industrial Wastewater treatment. According to the composition of flocculant, it can be divided into inorganic flocculant, organic flocculant and microbial flocculant. Aluminum salts and iron salts are commonly used in inorganic flocculants, and the flocculation effect is better. Among them, polyaluminum chloride (PAC) is an excellent inorganic polymer flocculant, and it is the flocculant with the most mature technology and the largest market sales. When PAC is used, it has the advantages of fast floc formation, good sedimentation performance, less alkalinity consumption in water, especially strong adaptability to changes in water temperature, pH value, turbidity and organic matter content. Generally, the dosage is large, which may cause secondary pollution to the environment. In the production, there are problems of product purity, insoluble matter, basicity, and removal of harmful ions such as heavy metals; it will bring a large amount of inorganic ions into the treated liquid, It is necessary to increase the desalination and deionization process. The aluminum salt coagulant used in the water treatment process will increase the residual aluminum in the water, causing harm to the human body, animals, plants, and aquatic organisms, and affecting the water treatment effect and the operation of the treatment process. Iron salt is used to purify drinking water and treat industrial sewage with the characteristics of high efficiency, high quality, low price, safety and non-toxicity. Compared with other flocculants, alum flowers are larger, sedimentation is faster, sediments are denser, and the pH value of the treated water is suitable for a wide range. , but it is highly corrosive, easy to bring color to the treated water, and has a pungent odor, and the operating conditions are poor. The residues of organic polymer flocculants such as PAM are not easy to be degraded by microorganisms, and its monomers have strong neurotoxicity and "three-induced" effects. Microbial flocculant is a new type of water treatment agent that is obtained through microbial fermentation and separation and extraction using biotechnology, is highly efficient, non-toxic, and can eliminate secondary pollution. etc. require in-depth research.

Looking at the current situation of flocculants, it can be seen that the pursuit of high efficiency, low cost, and environmental protection is the goal of flocculant developers, actively promote green chemical technology, and develop and promote the application of new flocculants with low environmental impact and high safety. For the purpose of this invention, the inorganic composite polysilicate aluminum chloride iron flocculant is prepared through corresponding chemical analysis and synthesis techniques.

Coking wastewater is a typical refractory organic wastewater with complex components, and it is also a key control target for the country and enterprises to implement energy conservation and emission reduction. At present, coking wastewater is still polluted after treatment, which is not only difficult to reuse, but also does not conform to the principle of total amount control by the State Environmental Protection Administration. There are the following problems: the medicament is more expensive, the dosage of the medicament added after the advanced treatment is large, and the water quality cannot be guaranteed to meet the effluent index controlled by the state, which makes the operating cost of the enterprise high and it is difficult to operate continuously for a long time; the medicament is solid Sometimes, there is incomplete dissolution, which causes waste to a certain extent, and produces secondary pollution, and the enterprise has new problems that need to be solved. The patent is a liquid, which is compounded by conventional medicaments, has low cost, and does not have environmental problems such as corrosion and pollution, and belongs to an environment-friendly green preparation.

CN1594082 relates to a special synthesis process of polyaluminum iron, including raw material selection, roasting of fly ash, treatment of roasted fly ash, treatment of filter residue, preparation of acid leaching solution for ironmaking waste residue, preparation of polyaluminum iron, Preparation of polymeric silicic acid and preparation of polyaluminum ferric silicate. Because the present invention has selected ironmaking waste slag and fly ash as raw materials, the synthetic process adopted has the particularity that conventional synthetic processes do not have. Although the comprehensive utilization rate of material resources has been improved, the process has increased several The first step is to prepare polysilicic acid with a concentration of silicon dioxide as high as 8%-10%, pH=2-3.5, and a large amount of polysilicic acid required, which also needs to be adjusted by adding acid.

The preparation method of CN1478806 polysilicate flocculant comprises: (1) adding the solution containing sodium silicate into the acid, making the pH value of the mixed solution 0.5-4, stirring, static aging, and generating a polymerized silicic acid solution; (2) Mix the metal salt solution with the polymeric silicic acid solution in (1), stir, keep the pH value of the solution at 0.5-4, and wait for static aging to obtain the polysilicate flocculant. However, it is necessary to add acid to adjust the pH=0.5-4, and it takes a long time to stand and mature.

CN200610156328.8 The method for preparing polyaluminum silicate hot metal treatment agent from bauxite tailings, relates to a preparation method of bauxite tailings treatment and polysilicate aluminum hot metal treatment agent, which is characterized in that bauxite is used The tailings are used as raw materials, and after high-temperature roasting, acid leaching, alkali dissolution, and polysilicic acid polymerization, the aluminum salt solution obtained in the acid dissolution process is added to polysilicate to prepare aluminum polysilicate iron water treatment agent. However, the polymerization process is relatively complicated and requires high temperature conditions.

The preparation of the present invention does not require a lower pH range, which saves the dosage of acid during preparation; when preparing polysilicic acid, the required activation is short; the temperature required for preparation is low; the raw materials required for preparation are simple, and the preparation The procedure is the simplest conventional process, and the preparation process is simple.

3. Contents of the invention:

The object of the present invention is to provide a kind of inorganic composite polysilicate aluminum iron chloride flocculation with high stability, strong electric neutralization ability, dense floc formed, large floc, good decolorization effect and fast settling speed. The preparation method of the agent.

Technical solution: the process steps of the present invention are as follows:

1) Polysilicic acid activation: 40% by mass of inorganic acid, accounting for 5.0-6.0% by weight, is added dropwise to sodium silicate solution, accounting for 11-12% by weight, sodium silicate solution The concentration of silicon dioxide is represented by the mass percentage of silicon dioxide. The concentration of silicon dioxide in the sodium silicate solution is 2% to 5%. Stir continuously during the addition process, then let it stand for aging, time: 2-6 hours, to obtain polysilicic acid;

2) synthesis: the relationship between the addition of inorganic aluminum salt, inorganic iron salt and sodium silicate solution is represented by molar ratio, the ratio of iron and aluminum is 1: 2, and the mol ratio of iron and aluminum to sodium silicate is (1+ 2): 2, directly add to the polysilicate that has been prepared, stir continuously during the adding process until it is completely dissolved, and leave it to mature for 10-15 hours to obtain the polysilicate aluminum iron chloride flocculant.

In the synthesis steps of the present invention: the order of adding the inorganic aluminum salt and the inorganic iron salt is: first add the inorganic aluminum salt, wait until the aluminum salt is completely dissolved, then add the iron salt, and continuously stir during the preparation process.

During the synthesis process, the temperature is 30-60 degrees.

The inorganic acid is sulfuric acid or hydrochloric acid.

Comparative flocculation evaluation experiment.

1) In this experiment, coking waste water (COD=108.6) after biochemical treatment was selected, and quantitative flocculant was added for evaluation. Take 50ml of biochemically treated coking wastewater in a 100ml beaker, add 1ml of flocculant, stir on the mixer for 15min, let it stand for 10min, take the supernatant and measure the COD concentration according to the "Water and Wastewater Monitoring and Analysis Method", the results are shown in Table 1 .

Table 1

serial number product Amount of flocculant (ppm) Water temperature, ℃ COD(ppm) 1 product 500 25 46.7 2 Polyaluminum 500 25 57.8 3 poly iron 500 25 62.5 4 activated carbon 500 25 20.6

It can be seen from the results in the table that the COD of water after using the flocculant synthesized by the present invention is obviously reduced.

2) In this experiment, coking waste water (NTU=40) after biochemical treatment was selected, and quantitative flocculant was added for evaluation. Take 50ml of biochemically treated wastewater from coking and weigh it in a 100ml beaker, add 1ml of flocculant, stir on the mixer for 15min, let it stand for 10min, take the supernatant and measure the COD concentration according to the "Water and Wastewater Monitoring and Analysis Method", the results are shown in the table 2.

Table 2

serial number product Amount of flocculant, ppm Water temperature, ℃ Turbidity 1 product 500 25 16 2 Polyaluminum 500 25 19 3 poly iron 500 25 20

4 activated carbon 500 25 10

As can be seen from the results in the table, the turbidity of the water after using the flocculant synthesized by the present invention is obviously reduced.

3) This example is a comparative experiment of different water treatment products.

In this experiment, coking waste water (chroma=55) after biochemical treatment was selected, and quantitative flocculant was added for evaluation. Take 50ml of biochemically treated wastewater from coking and weigh it in a 100ml beaker, add 1ml of flocculant, stir on the mixer for 15min, let it stand for 10min, take the supernatant and measure the COD concentration according to the "Water and Wastewater Monitoring and Analysis Method", the results are shown in the table 3.

table 3

serial number product Amount of flocculant, ppm Water temperature, ℃ Chroma 1 product 500 25 10 2 Polyaluminum 500 25 15 3 poly iron 500 25 30 4 activated carbon 500 25 6

As can be seen from the results in the table, the chromaticity of the water after using the flocculant synthesized by the present invention is obviously reduced.

4) This example is a comparison of the flocculation effect of the polysilicate aluminum iron chloride flocculant prepared by the present invention and commercially available polyaluminum and polyiron. The commercially available polyaluminium, polyiron and the product of the present invention were subjected to flocculation evaluation experiments according to the experimental conditions, and the comparison results are shown in Table 4.

Table 4

Experimental flocculant Floc formation speed Floc size sinking speed Product A quick big quick Polyaluminum slow Small slow poly iron slow bigger slow

As can be seen from the above comparative experimental results: the polysilicate aluminum ferric chloride flocculant prepared by the method of the present invention is widely used, and the use conditions are mild, and the coking waste water containing organic matter, oil, etc. Adding the flocculant of the present invention can achieve good flocculation effect.

Polysilicate aluminum chloride iron salt is a new type of inorganic polymer flocculant, which is developed on the basis of polysilicic acid (activated silicic acid) and traditional aluminum salts, iron salts and other flocculants. Complex products with metal salts. Because this type of flocculant has the functions of electrical neutralization and adsorption bridging, the flocculation effect is good, the preparation is easy, and the price is cheap. Polysilicic acid is made by the activation process of water glass and is essentially an anionic inorganic polymer flocculant. Aluminum-iron polysilicate flocculant is made by introducing aluminum salt and iron salt into polysilicate. In terms of application, it can be pre-hydroxylated and polymerized before mixing, or mixed first and then polymerized. This kind of flocculant can combine the advantages of polysilicic acid, polyaluminum and polyiron, and give full play to the strengths of the three. Their flocculation and destabilization performance far exceeds that of polysilicic acid or polymetallic ions alone. Compared with polysilicic acid, it not only improves the stability, but also increases the electric neutralization ability. Compared with metal ions, it enhances the bonding and bridging performance.

The polysilicate aluminum iron chloride flocculant has the following characteristics: the formed flocs are large, have good decolorization effect, the formed flocs are relatively dense, and the sedimentation speed is fast, which can give full play to the advantages of aluminum and iron flocculants.

4. Specific implementation

Example 1

At room temperature, 56 kilograms of 40% sulfuric acid solution (accounting for 5.6% by weight) was gradually added dropwise to 795 kilograms of 3% sodium silicate solution (accounting for 11.3% by weight) of silicon dioxide concentration, Mix well, at this time the pH of the solution is 8, stir at a speed of 60r/min for 2 hours, let stand and mature for 4 hours, and generate polysilicic acid. At a temperature of 40 degrees, the inorganic aluminum salt solid (9.6% by weight) was first added to the polysilicic acid and stirred for 1 hour; then the inorganic iron salt (5.3% by weight) was added to the Put it in the polymeric silicic acid solution with inorganic aluminum salt, stir for 1 hour, let it stand and mature for 12 hours, and you can get polysilicate aluminum ferric chloride flocculation product. After the coking wastewater is treated, the dosage of 0.5 grams of chemical is added to 1 liter of treated water, and the COD removal rate can reach more than 55%.

Meet the first-level standard of national pollutant discharge (COD<100mg/L).

serial number Treated water volume dosage CODmg/L before treatment CODmg/L after treatment Chroma before processing Chromaticity after processing 1 1 Litre 0.5 grams 108.6 46.7 55 15 2 1 Litre 0.5 grams 101.9 43.9 50 20 3 1 Litre 0.5 grams 99.8 40.2 55 18 4 1 Litre 0.5 grams 105.4 48.6 50 18 5 1 Litre 0.5 grams 102.7 45.5 50 18

Example 2

In the polysilicic acid obtained in Example 1, 96 kilograms of inorganic aluminum salt solid aluminum chloride hexahydrate (9.6% by weight) and 53 kilograms of inorganic iron salt ferric chloride hexahydrate (9.6% by weight) 5.3%) into polysilicic acid, stirred for 1 hour, and left to mature for 12 hours to obtain polysilicate aluminum ferric chloride flocculation product. The relationship between the amount of aluminum chloride or crystalline aluminum chloride solid, ferric chloride or crystalline ferric chloride solid and the sodium silicate solution is represented by molar ratio, the ratio of iron and aluminum is preferably 1:2, iron and aluminum and silicic acid The molar ratio of sodium is preferably (1+2):2. After the coking wastewater is treated, the dosage of 0.5 grams is added to 1 liter of treated water, and the COD removal rate can reach more than 47%.

Meet the first-level standard of national pollutant discharge (COD<100mg/L).

serial number Treated water volume dosage CODmg/L before treatment CODmg/L after treatment Chroma before processing Chromaticity after treatment 1 1 Litre 0.5 grams 114.5 52.9 58 25 2 1 Litre 0.5 grams 119.1 60.1 55 twenty two 3 1 Litre 0.5 grams 117.8 62.3 55 20 4 1 Litre 0.5 grams 110.7 56.4 50 18 5 1 Litre 0.5 grams 109.4 55.5 58 25

Claims (4)

1, the preparation method of inorganic composite polysilicate aluminum ferric chloride flocculant, it is characterized in that: step of preparation process is as follows:

1) poly-silicic acid activation: with mass percent is that 40% mineral acid is added drop-wise in the sodium silicate solution, by weight mineral acid: sodium silicate solution=5.0 ~ 6.0%: 11 ~ 12%, constantly stir in the dropping process, pH=7 ~ 9 of control sodium silicate solution, leave standstill slaking then, the time: 2-6 hour, obtain poly-silicate solution, the concentration of sodium silicate solution uses the mass percent of silicon-dioxide to represent that silica concentration is 2% ~ 5%;

2) synthetic: with inorganic aluminate, inorganic molysite with advancing to join in the poly-silicate solution that step 1) prepares, constantly stir in the adition process, until whole dissolvings, leave standstill the curing time: after 10-15 hour, obtain inorganic composite polysilicate aluminum ferric chloride flocculant, the add-on of inorganic aluminate, inorganic molysite and the relation of sodium silicate solution use mol ratio to represent that iron, aluminum ratio are 1: 2, and the mol ratio of iron and aluminium and water glass is (1+2): 2.

2, the preparation method of inorganic composite polysilicate aluminum ferric chloride flocculant according to claim 1 is characterized in that: when synthetic: at first add inorganic aluminate, after aluminium salt all dissolves by the time, and then add molysite.

3, the preparation method of a kind of inorganic composite polysilicate aluminum ferric chloride flocculant according to claim 1 and 2, temperature is 30 ~ 60 degree in the building-up process.

4, the preparation method of inorganic composite polysilicate aluminum ferric chloride flocculant according to claim 1 is characterized in that: mineral acid is sulfuric acid or hydrochloric acid.