CN103043759A - Method for preparing polyaluminium ferric chloride flocculating agent by pickling waste liquid and waste aluminium material - Google Patents

Abstract

The invention discloses a method for preparing a polyaluminium ferric chloride flocculating agent by pickling waste liquids and waste aluminium materials. The method for preparing a polyaluminium ferric chloride flocculating agent, comprises: mixing waste aluminium materials after acid dissolution and pickling waste liquids, regulating a pH value by sodium hydroxide, and oxidizing and polymerizing the mixture by a strong oxide to obtain the polyaluminium ferric chloride flocculating agent. Compared with the prior art, the method uses the raw materials which are cheap and wide in source, and has advantages of simple process and easy operation. The addition of waste aluminium materials is controlled to regulate the pH valve, thereby effectively reducing the cost. The proportion of aluminium to iron in the raw materials is flexibly controlled, and the application range is winder.

Description

Method for preparing polyaluminum ferric chloride flocculant by using pickling waste liquid and waste aluminum material

technical field

The invention relates to a method for preparing a polyaluminum chloride ferric flocculant by using pickling waste liquid and waste aluminum material and its application, which belongs to the technical fields of environmental chemical industry, waste water treatment and the like.

Background technique

In order to improve the surface structure of steel or process the surface, the corrosion of strong acid is often used to clean the steel surface. When the cleaning is carried out to a certain extent, the acid concentration in the washing solution decreases, and new acid needs to be replaced to maintain proper pickling. Speed, the residual liquid is discharged to form a waste liquid with high concentration of metal ions and residual acid, and its main component is ferrous chloride solution. According to incomplete statistics, the pickling waste discharged nationwide is greater than 1×10 ⁶ m ³ /a. Pickling waste liquid has strong acidity, high concentration, large amount of waste liquid, and is easy to form acid mist. If it is discharged directly, it will cause serious environmental pollution, and also cause waste of useful resources such as Fe ²⁺ and waste acid in the waste liquid. How to realize the recycling of pickling waste liquid has become a hot spot of research at home and abroad. Various comprehensive utilization technologies include neutralization of alkaline wastewater, recycling technology, etc., among which the preparation of inorganic polymer flocculants is a main direction.

The output of aluminum profiles in my country is increasing at a rate of 40% every year. In 2007, the output of aluminum profiles in my country reached more than 6 million tons. In the process of producing aluminum profiles, there will be aluminum waste, such as aluminum slag, aluminum chips, and aluminum scraps. The recycling and reuse of aluminum waste is of great significance in terms of saving resources on the earth, saving costs, environmental protection, and improving the human ecological environment.

In the 1970s, the successful development of polyaluminum chloride provided broad prospects for the development of inorganic polymer flocculants. After the publication of the first European patent on polyaluminum chloride in the 1980s, people turned to research on polyaluminum chloride. Aluminum iron. Polyaluminum ferric chloride is an inorganic polymer flocculant with excellent performance. It combines the advantages of polyaluminum chloride and polyferric chloride. It not only has good electrical neutralization, adsorption, Bridging and sweeping flocculation, good turbidity removal effect, less corrosive to equipment pipelines, etc.; also has the advantages of fast iron salt flocculant settlement, good low temperature treatment performance, wide range of adaptable pH value, easy separation, etc.

At present, there are many patents and documents on the preparation of polyferric chloride by using pickling waste liquid, such as Chinese patent application publication numbers CN1266819A, CN1789147A, CN101780986A, CN102502747A, CN102603015A. However, there are few reports on the preparation of polyaluminum ferric chloride by oxidative polymerization using aluminum raw materials and pickling waste liquor as raw materials, adjusting a suitable pH environment, and supplemented with oxidants. Patent CN101074128A uses calcium aluminate powder and pickling waste liquid to produce polyferric aluminum chloride coagulant product with too low base, and needs to add stabilizer. Patent CN102372308A uses aluminum raw materials (bauxite or aluminum hydroxide powder) and pickling waste liquid to prepare polyaluminum ferric chloride, and the mother liquor preparation process has strict requirements on pressure. Huang Yongqiang (Research on the preparation of flocculant polyaluminum ferric chloride by electroplating waste acid and its application, Water Treatment Technology, 2010, 36 (12), 113~116) Using calcium aluminate powder and electroplating waste acid as raw materials, the method of catalytic oxidation Although the process for preparing polyaluminum chloride is simple, the oxidizing agent used is sodium nitrite, and the oxidation efficiency is not high. The introduction of nitrite ions in the preparation process has side effects on the environment and human health.

Contents of the invention

The purpose of the present invention is to provide a method for preparing polyaluminum ferric chloride flocculant by using pickling waste liquid and waste aluminum material and its application, so as to solve the pollution problem of pickling waste liquid and make full use of waste at the same time, turning waste into treasure.

The invention provides a method for preparing polyaluminum chloride ferric flocculant by using pickling waste liquid and waste aluminum material, which has the following steps:

(1) Use aluminum scrap and industrial hydrochloric acid to react in an acid-resistant container under normal pressure. When the pH rises to 0.8~1.3, filter to generate an aluminum-containing solution;

(2) After adding waste aluminum material to the pickling waste liquid to completely dissolve it, the pH of the solution rises to 1.6~2.0, forming an iron-containing solution;

(3) Put the aluminum-containing solution in step (1) and the iron-containing solution in step (2) into the anti-corrosion reaction container in proportion, and add alkali to adjust the pH value of the mixed solution to 1.9~3.0;

(4) Control the temperature of the mixed solution in the reaction vessel at 65-85°C, stir slowly, add an oxidant, react for 30-60 minutes, stop heating, and age for 2-3 hours to prepare polyaluminum ferric chloride flocculant.

In the above step (1), the waste aluminum material is aluminum leftovers, aluminum scraps and aluminum slag generated during the processing of aluminum materials; wherein the aluminum content is 70-80%.

In the above step (1), the concentration of Al(III) in the aluminum-containing solution is 70-100 g/L.

In the above step (2), the pickling waste liquid is iron and steel pickling waste liquid, and the contained free acid is hydrochloric acid, wherein the concentration of Fe(II) is 160~175g/L, and the concentration of Fe(Ⅲ) is 15~20g/L .

In the above step (3), the molar ratio of aluminum to iron is 6-9:4-1.

In the above step (4), the oxidizing agent is sodium chlorate, which is added in the form of solid or solution.

The present invention also provides the above polyaluminum ferric chloride flocculant used for turbidity removal, decolorization, oil removal and other solid-liquid separation processes in the waste water treatment process.

Compared with the prior art, the present invention has the following beneficial effects:

1. Use iron and steel pickling waste liquid and waste aluminum as raw materials for preparation, both of which are waste materials produced in industrial production, which reduces the cost of preparing polyaluminum ferric chloride, and also realizes pickling waste liquid and waste aluminum The comprehensive utilization of raw materials reduces the pollution of pickling waste liquid to the environment.

2. Using highly oxidizing sodium chlorate as an oxidizing agent, the oxidation speed is fast and the efficiency is high, and all Fe ²⁺ in the pickling waste liquid can be oxidized into Fe ³⁺ . The prepared polyaluminium chloride ferric chloride flocculant is stable powerful.

3. Using the method of first adjusting the basicity and then oxidative polymerization, the pH is controlled during the process of dissolving the waste aluminum, so that the pH of the solution rises spontaneously, so that only a small amount of alkali can be added to increase the pH of the solution and reduce the preparation time. The cost of polyaluminum ferric chloride.

4. The whole preparation process is carried out under normal pressure, which requires less equipment, and the whole process is simple to operate, and can flexibly control the ratio of aluminum and iron in the preparation raw materials, so that the application range of the flocculant is wider.

Detailed ways

The present invention will be further described below in conjunction with examples, but the present invention is not limited.

Example 1

(1) Take 50g of waste aluminum with an aluminum content of 70%, and 740g of industrial hydrochloric acid (HCl is 23%), and put them into an acid-resistant reaction vessel. When the solution pH=1.0, filter, and the filtrate is the aluminum-containing solution;

(2) Take 55g of iron and steel pickling waste liquid and 0.22g of waste aluminum material, put them into the acid-resistant reaction container, and wait for complete dissolution, the solution is an iron-containing solution with pH=1.8;

(3) Put the aluminum-containing solution in step (1) and the iron-containing solution in step (2) into the anti-corrosion reaction container, and add 2mol/L sodium hydroxide solution dropwise while stirring. When the pH=1.91, Heat, control the temperature at 75°C, stir slowly, add 2.4g of sodium chlorate, react for 40 minutes, stop heating, and age for 3 hours, the content of Al ₂ O ₃ is 10.2%, the content of Fe ₂ O ₃ is 1.8%, salt Polyaluminum ferric chloride finished product with a basis of 40.6%.

Example 2

(1) Take 43g of scrap aluminum with an aluminum content of 75%, and 620g of industrial hydrochloric acid (HCl is 25%), and put them into an acid-resistant reaction vessel. When the solution pH=1.1, filter, and the filtrate is the aluminum-containing solution;

(2) Take 105g of iron and steel pickling waste liquid and 0.45g of waste aluminum material, put them into an acid-resistant reaction container, and wait until completely dissolved, the solution is an iron-containing solution with pH=1.9;

(3) Put the aluminum-containing solution in step (1) and the iron-containing solution in step (2) into the anti-corrosion reaction container, and add 2mol/L sodium hydroxide solution dropwise while stirring. When the pH=1.98, Heat, control the temperature at 70°C, stir slowly, add 4.5g of sodium chlorate, react for 50 minutes, stop heating, and age for 2 hours, the content of Al ₂ O ₃ is 8.6%, the content of Fe ₂ O ₃ is 3.4%, salt The finished product of polyaluminum ferric chloride with a basis of 39.8%.

Example 3

(1) Take 35g of scrap aluminum with an aluminum content of 80%, and 520g of industrial hydrochloric acid (HCl is 26%), and put them into an acid-resistant reaction vessel. When the solution pH=0.9, filter, and the filtrate is the aluminum-containing solution;

(2) Take 150g of iron and steel pickling waste liquid and 0.6g of waste aluminum material, put them into the acid-resistant reaction container, and wait for complete dissolution, the solution is an iron-containing solution with pH=1.7;

(3) Put the aluminum-containing solution in step (1) and the iron-containing solution in step (2) into the anti-corrosion reaction container, and add 2mol/L sodium hydroxide solution dropwise while stirring. When the pH=2.35, Heat, control the temperature at 75°C, stir slowly, add 6.5g of sodium chlorate, react for 40 minutes, stop heating, and age for 3 hours, the content of Al ₂ O ₃ is 7.1%, the content of Fe ₂ O ₃ is 4.8%, salt The finished product of polyaluminum ferric chloride with a basis of 47.1%.

Example 4

(1) Take 30g of scrap aluminum with an aluminum content of 78%, and 440g of industrial hydrochloric acid (HCl is 25%), and put them into an acid-resistant reaction vessel. When the solution pH=1.1, filter, and the filtrate is the aluminum-containing solution;

(2) Take 190g of iron and steel pickling waste liquid and 0.82g of waste aluminum material, put them into an acid-resistant reaction container, and wait until completely dissolved, the solution is an iron-containing solution with pH=1.9;

(3) Put the aluminum-containing solution in step (1) and the iron-containing solution in step (2) into the anti-corrosion reaction container, and add 2mol/L sodium hydroxide solution dropwise while stirring. When the pH=2.97, Heat, control the temperature at 70°C, stir slowly, add 8.2g of sodium chlorate, react for 40 minutes, stop heating, and age for 3 hours, the content of Al ₂ O ₃ is 5.8%, the content of Fe ₂ O ₃ is 6.1%, salt The finished product of polyaluminum ferric chloride with a basis of 54.6%.

Claims (6)

1. method of utilizing spent pickle liquor and aluminium scrap material to prepare aluminium iron polychloride floculant is characterized in that having following steps:

(1) with aluminium scrap material and technical hydrochloric acid under atmospheric pressure state, put into the acid-resistant container internal reaction, when pH rises to 0.8 ~ 1.3, filter, generate and contain aluminum solutions;

(2) after adding aluminium scrap material dissolved it fully in spent pickle liquor, the pH of its solution rose to 1.6 ~ 2.0, generates iron-containing liquor;

(3) iron-containing liquor that contains in aluminum solutions and the step (2) in the step (1) is dropped in the anticorrosive reaction vessel in proportion, the pH value that adds alkali adjusting mixed solution is 1.9 ~ 3.0;

(4) temperature with the reaction vessel mixed solution is controlled at 65 ~ 85 ℃, and low rate mixing adds oxygenant, reacted 30 ~ 60 minutes, and stopped heating, ageing 2 ~ 3 hours makes aluminium iron polychloride floculant.

2. the method for preparing aluminium iron polychloride floculant according to claim 1 is characterized in that: in the above-mentioned steps (1), the aluminium scrap material is aluminium scrap stock, aluminium bits and the aluminium slag that aluminium produces in the course of processing; Wherein aluminium content is 70 ~ 80%.

3. the method for preparing aluminium iron polychloride floculant according to claim 1 is characterized in that: in the above-mentioned steps (1), contain Al(III in the aluminum solutions) concentration is 70 ~ 100g/L.

4. the method for preparing aluminium iron polychloride floculant according to claim 1, it is characterized in that: in the above-mentioned steps (2), spent pickle liquor is iron and steel pickling waste liquid, and contained free acid is hydrochloric acid, wherein Fe (II) concentration is 160 ~ 175g/L, and Fe (III) concentration is 15 ~ 20g/L.

5. the method for preparing aluminium iron polychloride floculant according to claim 1, it is characterized in that: in the above-mentioned steps (3), the mol ratio of aluminium and iron is 6 ~ 9:4～1.

6. the method for preparing aluminium iron polychloride floculant according to claim 1, it is characterized in that: in the above-mentioned steps (4), oxygenant is sodium chlorate, adds with solid form or solution form.