1. A method for granulating, curing and dealkalizing red mud is characterized by comprising the following steps: the red mud is consolidated into balls through a hydraulic cementing material to prepare spherical particles, and then the spherical particles are soaked for dealkalization, wherein the powder raw materials in the spherical particles comprise the following components in parts by weight: 80-90 parts of red mud and 10-20 parts of hydraulic cementing material.

2. The red mud granulation, solidification and dealkalization method according to claim 1, which is characterized in that: the hydraulic cementing material is one or a mixture of more of Portland series cement, alkali-activated slag, geopolymer, sulphoaluminate cement and magnesium phosphate cement.

3. The red mud granulation, solidification and dealkalization method according to claim 1, which is characterized in that: the red mud is sintering process red mud, Bayer process red mud or combination process red mud.

4. The red mud granulation, solidification and dealkalization method according to claim 1, which is characterized in that: the method specifically comprises the following steps:

1) adding water and a water reducing agent into a powder raw material at normal temperature according to a ratio, and mixing to obtain a dry and thick paste, wherein the water adding amount accounts for 15-20% of the mass of the powder raw material, the mixing amount of the water reducing agent accounts for 0.5-1% of the mass of the powder raw material, and the precise dosage of the water and the water reducing agent is based on convenient granulation;

2) pouring the dry and thick paste into a granulator for granulation and balling;

3) when the surfaces of the granular balls are round and smooth and have no cracks and the granular balls are not mutually adhered, the preparation of the spherical granules to be dealkalized is completed;

4) standing the spherical particles to be dealkalized until the spherical particles are fully solidified, and taking the spherical particles as the standard of being soaked in water without collapse and mud;

5) pouring fully cured spherical particles to be dealkalized into a clean water tank for soaking for 0.5-1 hour, wherein the solid-to-liquid ratio of soaking is controlled to be 1: 4-7;

6) and pouring out the leaching solution to finish the dealkalization treatment of the spherical particles to be dealkalized.

5. The red mud granulation, solidification and dealkalization method according to claim 4, which is characterized in that: the water reducing agent is naphthalene series, aliphatic series or polycarboxylic acid.

Background

The red mud is strong-alkaline solid waste discharged in the production process of alumina. The discharge amount of red mud is nearly 1 hundred million tons every year in China, the total stacking amount of the red mud exceeds 6 hundred million tons, and the stacking of a large amount of red mud can bring harm to the health of people and the natural environment due to the characteristics of strong alkalinity, high water content and the like. At present, red mud is treated by a common damming stacking and seawater dumping mode at home and abroad, the damming stacking treatment not only occupies a large amount of land resources, but also causes the problems of water body pollution, soil salinization and the like because heavy metals in the red mud can permeate into soil and surface water in the stacking process. Besides the direct pollution of the substances in the red mud, the dust generated after the red mud is dehydrated can also pollute the atmosphere. Meanwhile, alkaline substances in the red mud corrode a dam body and easily cause dam break danger, so that the research on the reduction, harmlessness and reclamation of the red mud can fundamentally solve the problems that the red mud is accumulated to occupy a large amount of land and has large potential hazard.

The existing dealkalization method of red mud comprises a calcium ion replacement method, a wet carbonization method and a water washing method. The calcium ion replacement method needs to consume a large amount of reagents and is high in cost. The wet-method carbonization treatment of the red mud needs high pressure, has strict requirements on leaching equipment, and has the disadvantages of difficult control of required conditions and complicated operation. The water washing dealkalization process is simple, does not consume reagents, has low cost and is a main method commonly adopted by the dealkalization of the red mud at present. The washing process comprises two procedures of washing and filter pressing dehydration, and because the red mud has strong water absorption, the water content of the red mud cake after filter pressing is still high, the dealkalization efficiency is low, only part of free alkali in the red mud can be removed, and the washing and the filter pressing are required to be repeated for many times. Even so, the leaching rate of soluble alkali is only 50-70% after four times of water washing. And the wastewater generated by multiple times of washing is large in amount and turbid in water quality, and the subsequent purification treatment cost is high.

Disclosure of Invention

Aiming at the defects in the prior art, the invention provides a method for granulating, curing and dealkalizing red mud, which has simple process and high dealkalizing efficiency, fundamentally solves the problem of piling up a large amount of red mud, can extract valuable metals such as sodium from the filtered red mud and realizes the recycling of secondary resources.

In order to achieve the purpose, the invention adopts the following technical scheme:

a red mud granulation, solidification and dealkalization method is characterized in that red mud is consolidated into balls through a hydraulic cementing material to prepare spherical particles, then the spherical particles are soaked for dealkalization, and powder raw materials in the spherical particles comprise the following components in parts by weight: 80-90 parts of red mud and 10-20 parts of hydraulic cementing material.

The improvement is that the hydraulic cementing material is one or more of silicate series cement, alkali-activated slag, geopolymer, sulphoaluminate cement and magnesium phosphate cement.

The red mud is sintered red mud, Bayer red mud or combined red mud.

As an improvement, the method specifically comprises the following steps:

1) adding water and a water reducing agent into a powder raw material at normal temperature according to a ratio, and mixing to obtain a dry and thick paste, wherein the water adding amount accounts for 15-20% of the mass of the powder raw material, the mixing amount of the water reducing agent accounts for 0.5-1% of the mass of the powder raw material, and the precise dosage of the water and the water reducing agent is based on convenient granulation;

2) pouring the dry and thick paste into a granulator for granulation and balling;

3) when the surfaces of the granular balls are round and smooth and have no cracks and the granular balls are not mutually adhered, the preparation of the spherical granules to be dealkalized is completed;

4) standing the spherical particles to be dealkalized until the spherical particles are fully solidified, and taking the spherical particles as the standard of being soaked in water without collapse and mud;

5) pouring fully cured spherical particles to be dealkalized into a clean water tank for soaking for 0.5-1 hour, wherein the solid-to-liquid ratio of soaking is controlled to be 1: 4-7;

6) and pouring out the leaching solution to finish the dealkalization treatment of the spherical particles to be dealkalized.

The improvement is that the water reducing agent is naphthalene series, aliphatic series or polycarboxylic acid.

Has the advantages that:

compared with the prior art, the method for granulating, curing and dealkalizing the red mud has the following advantages:

(1) thoroughly solves the problem of difficult dehydration of the water-washed dealkalized red mud

Although practice has proved that the red mud washing can achieve the aim of dealkalization, the red mud has great water absorption because the red mud belongs to superfine powder, so the washed red mud still has more than 40 percent of water after filter pressing and dehydration, soluble alkali is dissolved in the pore water of the red mud and can not be completely removed, repeated washing and filter pressing are needed, the process is complicated, the efficiency is low, the amount of waste water generated by repeated washing is large, the water quality is turbid, and the subsequent purification treatment cost is high.

According to the invention, the red mud is consolidated into clusters through the hydraulic cementing material, the red mud powder is consolidated into the red mud aggregate by utilizing the mechanical strength established by the red mud and the cementing material, the red mud aggregate is soaked in clear water after being fully solidified, the salt in the red mud aggregate is fully leached, and finally the particles are taken out of the soaking solution, so that the solid-liquid separation is realized, namely the purpose of washing and dealkalizing is achieved.

(2) Realizes the recycling of the dissolved alkali

The red mud has high soluble alkali content and high utilization value, and can generate very high economic benefit if being extracted effectively. The traditional calcium ion replacement method, wet carbonization method, acid dissolution method and the like digest the soluble alkali in the calcium ion replacement method to achieve the aim of dealkalization, thereby causing great resource waste. The washing method has the disadvantages of large amount of waste water, turbid water quality, incapability of recovering soluble alkali and high cost of subsequent sewage purification treatment.

The invention solidifies the red mud into hard aggregate particles through the hydraulic cementing material, and the soaking solution is clear in water quality, and the soluble alkali in the soaking solution can be directly recycled.

(3) Develops a path for resource utilization of the red mud

The building material application of the red mud is the most effective way for red mud digestion, but because the content of soluble alkali in the red mud is higher, building material products developed by the red mud are seriously efflorescent, and the resource development of the red mud is greatly restricted.

According to the invention, the red mud is consolidated into clusters through the hydraulic cementing material, the dealkalization is sufficient, the problem of the saltpetering of the red mud building material product is thoroughly solved, and meanwhile, the granulated red mud and the cementing material establish higher mechanical strength, so that the red mud can be used as lightweight aggregate to be doped into concrete, and the red mud resource utilization way is widened.

Detailed Description

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention.

Example 1

Selecting Bayer process red mud of Xinghua county of Shandong province as treatment object, and determiningIts alkali content is 6.87% (by Na)₂And O is calculated). Uniformly dry-mixing 80 parts of Bayer process red mud and 20 parts of P.O 42.5.5 ordinary portland cement in parts by mass, adding water accounting for 15% of the mass of the powder raw materials and 0.5% of a water reducing agent, mixing the materials into a dry and thick paste, pouring the paste into a granulator to prepare spherical particles with the particle size of 3-20mm, and standing the spherical particles to be desalted for 7 days to fully solidify the spherical particles until the spherical particles are not disintegrated and muddy when meeting water; and pouring the fully solidified particles into a clean water tank to be soaked for 1 hour, wherein the solid-to-liquid ratio of soaking is 1:5, so that alkali in the particles is fully leached, and the dealkalization of the red mud is realized. Measuring the content of residual alkali (Na) in the dealkalized red mud particle ball by using a fluorescence analyzer₂Calculated as O) was 0.11%, the removal of alkali was sufficient.

Example 2

The red mud is treated with Bayer process red mud of Xinghua county of Shandong province, and its alkali content is 6.87% (using Na)₂And O is calculated). Uniformly dry-mixing 90 parts of Bayer process red mud and 10 parts of P.O 42.5.5 ordinary portland cement in parts by mass, adding water accounting for 15% of the mass of the powder material and 0.5% of a water reducing agent, mixing the materials into a dry and thick paste, pouring the paste into a granulator to prepare spherical particles with the particle size of 3-20mm, and standing the spherical particles to be desalted for 7 days to fully solidify the spherical particles until the spherical particles are not disintegrated and not argillized when meeting water; and pouring the fully solidified particles into a clean water tank to be soaked for 0.5 hour, wherein the solid-to-liquid ratio of soaking is 1:6, so that alkali in the particles is fully leached, and the dealkalization of the red mud is realized. Measuring the content of residual alkali (Na) in the dealkalized red mud particle ball by using a fluorescence analyzer₂Calculated as O) is 0.16 percent, and the alkali is sufficiently removed.

Example 3

The red mud is treated with Bayer process red mud of Xinghua county of Shandong province, and its alkali content is 6.87% (using Na)₂And O is calculated). Uniformly dry-mixing 85 parts of Bayer process red mud and 15 parts of P.O 42.5.5 ordinary portland cement in parts by mass, adding water accounting for 15% of the mass of the powder raw materials and 0.5% of a water reducing agent, mixing the materials into a dry and thick paste, pouring the paste into a granulator to prepare spherical particles with the particle size of 3-20mm, and standing the spherical particles to be desalted for 7 days to fully solidify the spherical particles until the spherical particles are not disintegrated and muddy when meeting water; pouring the fully solidified particles into a clean water pool to be soaked for 0.8 hour, wherein the solid-liquid ratio of the soaking is 1:7,so that the alkali in the red mud is fully leached, and the dealkalization of the red mud is realized. Measuring the content of residual alkali (Na) in the dealkalized red mud particle ball by using a fluorescence analyzer₂Calculated as O) is 0.09 percent, and the alkali is sufficiently removed.

The above description is only a preferred embodiment of the red mud powder dealkalization technology of the present invention, and is not intended to limit the present invention, and the dealkalization of the powder material by the solidification granulation method within the spirit and principle of the present invention shall be included in the protection scope of the present invention.