CN103031443A - Method of dealkalizing red mud and recovering aluminum and iron - Google Patents

Abstract

The invention discloses a method of dealkalizing red mud and recovering aluminum and iron. The method comprises the steps of mixing the red mud and sulfuric acid, roasting, or stirring and leaching, conducting water-leaching, washing and filtering on roasted or leached products, reducing the content of Na2O in solid slag to below 1%, and recovering the aluminum and the iron in a solution by methods such as neutralization sedimentation and resin adsorption. The method has the characteristic that the method is simple in treatment process, low in cost, easy to automatize and large in scale.

Description

A method for dealkalizing red mud and recovering aluminum and iron

technical field

The present invention relates to the fields of metallurgy, chemical industry and building materials, especially in the fields of metallurgy and building materials preparation. After desodiumizing the waste residue red mud discarded by alumina plants, cement, sintered bricks, non-steamed bricks, etc. are prepared, and can be recycled at the same time. Among them aluminum and iron.

Background technique

Red mud is a polluting waste residue removed from the alumina industry. On average, 1 to 2 tons of red mud is produced for every 1 ton of alumina produced. my country, as the world's fourth largest producer of alumina, discharges more than 5.5 million tons of red mud every year. At present, the wet storage or dehydration and drying treatment of red mud reservoirs (dams) are often adopted, which not only invades farmland, pollutes the environment, and has hidden dangers of dam collapse, but also causes secondary waste of resources. Therefore, it is very important to comprehensively utilize and harmlessly treat it. necessary.

For the development and utilization of red mud, researchers have carried out research on building materials, adsorption materials, filling materials, agricultural fertilizers, and recovery of valuable metals, but most of them are in the theoretical research stage, so the overall comprehensive utilization rate is only 15%. about.

If red mud is to be well applied in the field of building materials, it must be desodiumized, because the presence of sodium will bring harm to the later application process of the material, and one of the more serious forms is "frosting". Therefore, red mud is carried out The research on mud desalination has potential industrial value. 

Aiming at this problem, domestic and foreign researchers have done a lot of research. The patent (CN1141264A) proposed "sintering red mud dealkalization and its surface modification process", using activated calcium oxide as dealkalization agent and calcium lignin sulfite as surface modifier, the dealkalization rate is 60~70%; the patent (CN1594093A) proposed "a Bayer process red mud dealkalization method at atmospheric pressure", and the dealkalization reaction is carried out after mixing red mud and milk of lime, and the N/S of red mud can be reduced to below 0.10; The patent (CN101468866A) proposes "a method for dealkalization of red mud under normal pressure by sintering method". The red mud produced in the sintering process is roasted and pulverized, and then mixed with water and put into a gas-liquid- In the solid three-phase reactor, CO ₂ gas is introduced into the red mud slurry for dealkalization reaction, which can reduce the Na ₂ O content in the red mud to below 1%; the patent (CN101423318A) proposes "a kind of red mud The method of de-alkalization" first grinds the red mud and sulfuric acid, then adds lime to the autoclave for heating reaction to de-sodium, which can make the sodium content in the red mud lower than 0.3%; the patent (CN102190322A) proposes "removal The method of sodium in the red mud produced by the alumina industry", using ammonium chloride to remove the alkali in the red mud; other methods of using phosphogypsum to quickly dealkalize the red mud.

These methods above either have relatively high processing costs, or are difficult to realize industrialization.

Contents of the invention

The purpose of the present invention is to provide a desodination method with low treatment cost, good desodination effect, and easy industrialization, which reduces or removes the sodium in red mud, and recovers part of aluminum and iron, so that the red mud with reduced sodium content is convenient Used in the production of construction materials such as cement and brick making.

The technical scheme of the present invention: a method for removing sodium from red mud and recovering aluminum and iron, comprising the following steps:

(1) Leaching process: first mix red mud with sulfuric acid; then put the mixed solution into a heated and stirred container for stirring, then wash and filter the solution, and the obtained filter residue is the treated red mud;

(2) The washing solution after the leaching process or roasting process, after precipitation and resin adsorption, extracts aluminum and iron, and the remaining sodium sulfate solution crystallizes as a by-product.

A method for removing sodium from red mud and recovering aluminum and iron, comprising the following steps:

(1) Roasting process: firstly mix red mud with sulfuric acid; then put the mixed liquid into a high-temperature furnace for roasting, then cool naturally, take samples, wash and filter, and the obtained filter residue is the processed red mud;

(2) The washing solution after the leaching process or roasting process, after precipitation and resin adsorption, extracts aluminum and iron, and the remaining sodium sulfate solution crystallizes as a by-product.

In the leaching process, the concentration of sulfuric acid is 30~200g/l, the liquid-solid ratio of the mixed solution of red mud and sulfuric acid is 3~6; the temperature is 30~110°C, the stirring speed is 200~500r/min, and the leaching time is 20~ 80min, washing frequency is 3~8 times.

In the roasting process, the liquid-solid ratio of the mixed solution of red mud and sulfuric acid is 0.5-2, the amount of sulfuric acid per ton of red mud is 50-500kg, the roasting temperature is 100-800°C, the roasting time is 20-80min, and the washing times 3~8 times.

The red mud is Bayer red mud, sintering red mud or mixed red mud.

Beneficial effects of the present invention: (1) The red mud treated by the present invention has high activity, and the Na ₂ O content is lower than 1%, which can be used in the application of building materials such as cement, sintered bricks, non-steamed bricks, etc.; (2) The red mud treated by the present invention The technological process adopted is simple, and at the same time, it can process the waste acid of some enterprises, and can realize closed-circuit circulation without secondary pollution; (3) The present invention has low treatment cost, good sodium removal effect, and easy industrialization.

Detailed ways

Example 1:

The liquid-solid ratio of a mixed solution of Bayer red mud and sulfuric acid is 3; the concentration of sulfuric acid is 30g/l; then the mixed solution is put into a heated and stirred container for stirring, the temperature is 110°C, and the stirring speed is 200r/l min, the leaching time is 20min, and then the solution is washed and filtered for 3 times, and the obtained filter residue is the treated red mud; the Na ₂ O content in the treated red mud is 0.85%, after neutralization precipitation and resin After adsorption treatment, the recovery rates of aluminum and iron entering the solution are 82% and 90% respectively, and the purity of sodium sulfate after crystallization is greater than 92%.

Example 2:

The liquid-solid ratio of a mixed solution of Bayer red mud and sulfuric acid is 5; the concentration of sulfuric acid is 150 g/l; min, the leaching time is 70min, and then the solution is washed and filtered, the number of washings is 8 times, and the obtained filter residue is the treated red mud; the Na ₂ O content in the treated red mud is 0.21%, after neutralization precipitation and resin After adsorption treatment, the recovery rates of aluminum and iron entering the solution are 75% and 88% respectively, and the purity of sodium sulfate after crystallization is greater than 93%.

Example 3:

The liquid-solid ratio of the mixed solution of red mud and sulfuric acid is 6; the concentration of sulfuric acid is 50g/l; then the mixed solution is put into a heated and stirred container for stirring, the temperature is 60°C, and the stirring speed is 500r /min, the leaching time is 70min, and then the solution is washed and filtered, the number of washings is 5 times, and the obtained filter residue is the treated red mud; the Na ₂ O content in the treated red mud is 0.41%, after neutralization, precipitation and After resin adsorption treatment, the recovery rates of aluminum and iron entering the solution are 70% and 94% respectively, and the purity of sodium sulfate after crystallization is greater than 85%. .

Example 4:

The liquid-solid ratio of the mixed solution of red mud and sulfuric acid is 4; the concentration of sulfuric acid is 200g/l; then the mixed solution is put into a heated and stirred container for stirring, the temperature is 30°C, and the stirring speed is 500r /min, the leaching time is 80min, and then the solution is washed and filtered, the number of washings is 4 times, and the obtained filter residue is the treated red mud; the Na ₂ O content in the treated red mud is 0.76%, after neutralization, precipitation and After resin adsorption treatment, the recovery rates of aluminum and iron entering the solution are 79% and 89% respectively, and the purity of sodium sulfate after crystallization is greater than 92%.

Example 5:

The liquid-solid ratio of a mixed solution of Bayer red mud and sulfuric acid is 0.5; the amount of sulfuric acid per ton of red mud is 500kg; Then cool naturally; wash and filter the samples for 3 times, and the resulting filter residue is the treated red mud; the Na ₂ O content in the treated red mud is 0.98%, and after neutralization precipitation and resin adsorption treatment, it enters the solution The recoveries of aluminum and iron in the process are 74% and 89% respectively, and the purity of sodium sulfate after crystallization is greater than 90%.

Embodiment 6:

The liquid-solid ratio of the mixed solution of red mud and sulfuric acid is 1.5; the amount of sulfuric acid per ton of red mud is 250kg; then the mixed solution is put into a high-temperature furnace for roasting, the roasting temperature is 400°C, and the roasting time is 60min , and then cooled naturally; the sample was washed and filtered for 5 times, and the resulting filter residue was the treated red mud; the Na ₂ O content in the treated red mud was 0.22%, and after neutralization, precipitation and resin adsorption treatment, it entered The recoveries of aluminum and iron in the solution are 89% and 88% respectively, and the purity of sodium sulfate after crystallization is greater than 90%.

Embodiment 7:

The liquid-solid ratio of the mixed solution of red mud and sulfuric acid is 2 by a mixed method; the amount of sulfuric acid per ton of red mud is 50kg; then the mixed solution is put into a high-temperature furnace for roasting, the roasting temperature is 100°C, and the roasting time is 80min , and then cooled naturally; the sample was washed and filtered for 8 times, and the resulting filter residue was the treated red mud; the Na ₂ O content in the treated red mud was 1.67%, and after neutralization, precipitation and resin adsorption treatment, it entered The recoveries of aluminum and iron in the solution are 83% and 82% respectively, and the purity of sodium sulfate after crystallization is greater than 95%.

Claims (5)

1. a red mud takes off sodium and reclaims the method for aluminium and iron, it is characterized in that: comprise following steps:

(1) extract technology: at first red mud is mixed with sulfuric acid; Then the container that mixed solution is put into the band heating, stirs stirs, and then solution is carried out washing and filtering, and the gained filter residue is the red mud after the processing;

(2) washing soln behind extract technology or the sinter process, through precipitation and resin absorption extraction aluminium and iron, after the remaining metabisulfite solution crystallization as byproduct.

2. a red mud takes off sodium and reclaims the method for aluminium and iron, it is characterized in that: comprise following steps:

(1) sinter process: at first red mud is mixed with sulfuric acid; Then mixed solution is put into High Temperature Furnaces Heating Apparatus and carry out roasting, then naturally cooling is taken a sample and is washed, filters, and the gained filter residue is the red mud after the processing;

(2) washing soln behind extract technology or the sinter process, through precipitation and resin absorption extraction aluminium and iron, after the remaining metabisulfite solution crystallization as byproduct.

3. a kind of red mud according to claim 1 takes off the method for sodium and recovery aluminium and iron, and it is characterized in that: sulfuric acid concentration is 30 ~ 200g/l, and the mixing solutions liquid-solid ratio of red mud and sulfuric acid is 3 ~ 6; Temperature is 30 ~ 110 ℃, and stirring velocity 200 ~ 500r/min, extraction time are 20 ~ 80min, and washing times is 3 ~ 8 times.

4. a kind of red mud according to claim 2 takes off the method for sodium and recovery aluminium and iron, it is characterized in that: the mixing solutions liquid-solid ratio of red mud and sulfuric acid is 0.5 ~ 2, the sulfuric acid consumption of red mud per ton is 50 ~ 500kg, maturing temperature is 100 ~ 800 ℃, roasting time is 20 ~ 80min, and washing times is 3 ~ 8 times.

5. take off according to claim 1 the method for sodium and recovery aluminium and iron with 2 described a kind of red muds, it is characterized in that: red mud is Bayer red mud, red mud from sintering process or mixed combining method red mud.