CN113104888B

CN113104888B - Full recycling method of red mud

Info

Publication number: CN113104888B
Application number: CN202110349376.3A
Authority: CN
Inventors: 建方方; 刘娥
Original assignee: Henan University of Science and Technology
Current assignee: Henan University of Science and Technology
Priority date: 2021-03-31
Filing date: 2021-03-31
Publication date: 2023-06-06
Anticipated expiration: 2041-03-31
Also published as: CN113104888A

Abstract

A full recovery and utilization method of red mud features that the red mud which is the industrial solid waste with high reserve and difficult treatment and utilization is processed sequentially and in multiple steps to realize rare-earth minerals and TiCl containing rare-earth metals lanthanum, cerium and yttrium ₄ 、ZrCl ₄ And preparing five high-value and strong environment-friendly products from the iron ore concentrate and the roadbed stone raw materials. The method has the advantages of high available value of various products, wide application range and remarkable economic benefit. The full recycling method not only realizes the maximum consumption of the conventional industrial waste pollutant red mud, solves the technical problems of large yield, difficult treatment and serious environmental pollution, but also realizes the excellent effects of rich product types, wide industrial application range and high additional value, and raw materials can be fully recycled. Therefore, the resource utilization rate is high, the economic benefit and the social benefit are obvious, and the method has wide market application prospect.

Description

Full recycling method of red mud

Technical Field

The invention belongs to the technical field of recycling treatment of solid wastes, and particularly relates to a full recycling method of red mud.

Background

In the production process of alumina, 1 to 1.5 tons of red mud is produced per 1 ton of alumina produced, so the comprehensive utilization of the red mud discharged in the production process of alumina is a worldwide difficult problem. The annual red mud discharge of China serving as a large country for alumina production is close to 1.5 hundred million tons, the accumulated discharge exceeds 13 hundred million tons, and the red mud becomes the largest pollutant of an alumina plant. At present, the global red mud reserve estimation is over 30 hundred million tons, the average world red mud utilization rate is 15%, and the Chinese red mud utilization rate is only 4%. Environmental pollution caused by red mud stockpiling is a bottleneck for alumina development, and harmless and recycling of red mud is not satisfactory. At present, the comprehensive treatment of red mud is very important in China, and related planning for encouraging the large-scale and high-quality utilization of metallurgical slag (red mud) is also provided.

The red mud is an overbased industrial solid waste, namely the red mud produced by a Bayer process, a sintering process or a series-parallel process, wherein the titanium oxide TiO ₂ Content of rare earth metalsAre higher, which is related to the symbiotic presence of elements that are the elements of the earth group, accompanied by similar properties. Tables 1 and 2 below are data reported in the literature of red mud from domestic alumina factories, and table 3 is sample detection data from the red mud library of small Yang He of Oriental hope aluminum industry Co., ltd.

TABLE 1 chemical composition/%

Table 2 rare earth metal element chemical composition/%

Element(s)	La	Ce	Pr	Nd	Sm	Eu	Ga	Tb
									Mass percent (%)	308.3-309.3	604.6-626.8	40.3-56.8	203.6-216.6	29.9-40.6	4.55-5.74	21.5-32.6	3.3-4.4
Element(s)	Ho	Er	Tm	Yb	Lu	Y	Sc	Dy
									Mass percent (%)	3.93-4.82	11.2-13.8	1.44-1.74	8.7-10.3	1.35-1.54	80.5-99.6	64.3-69.3	17.8-21.5

Table 3 red mud ICP detection results of small Yang He red mud library of Oriental hope aluminum industry Co., ltd in three-channel city in Henan

From the above table data, it can be seen that: the elements with high added value and potential recovery value in the red mud are mainly lanthanum, cerium, yttrium of the third subgroup and titanium and zirconium of the fourth subgroup. Although the content of silicon, aluminum, iron, calcium and sodium is high, the silicon, aluminum, iron, calcium and sodium have no practical value as metal mineral sources and can only be used as nonmetallic mineral sources for producing building materials. In particular, the red mud has low content of toxic elements such as heavy metals chromium, lead and the like, and is a relatively suitable raw material for producing building materials. However, the red mud has strong alkalinity and high salt content, and does not meet the material standard of building materials.

Therefore, how to reasonably process and pretreat the existing alumina red mud with large reserves to realize high-value recycling of the alumina red mud is necessary for the treatment of the alumina red mud.

Disclosure of Invention

The technical purpose of the invention is as follows: the full recovery treatment process of the alumina red mud is simple in process flow, low in raw material cost, various in product types, high in added value and sufficient in resource utilization, and can realize full recovery of materials, so that the technical problems of large storage amount, difficult treatment and serious environmental pollution of the alumina red mud are solved.

In order to achieve the above purpose, the invention adopts the following technical scheme: the full recycling method of the red mud comprises the following steps:

firstly, adding water into a red mud raw material to prepare ore pulp, then dropwise adding a concentrated sulfuric acid solution into the ore pulp under the condition of continuous stirring until no foam is generated in the obtained reaction system a, continuously stirring and reacting for 10-15min, and then carrying out solid-liquid separation on the obtained reaction product to obtain filtrate A and filter cake B for later use;

step two, adjusting the pH value of the filtrate A prepared in the step one by adopting a carbonate saturated solution until the pH value of the obtained compound is 4.7-5.2, and then filtering the obtained compound to prepare filtrate C and solid precipitate D for later use;

performing reverse osmosis filtration on the filtrate C prepared in the step II by adopting a reverse osmosis membrane to prepare desalted water and concentrated salt solution E which can be industrially recycled for later use;

step four, evaporating and crystallizing the concentrated salt solution E prepared in the step three to prepare rare earth mineral products containing rare earth metals lanthanum, cerium and yttrium, and the rare earth mineral products can be directly sold;

step five, adding the solid precipitate D prepared in the step two into a reaction furnace which is pre-filled with carbon powder according to the mass ratio of the solid precipitate D to the carbon powder of (3-5): 1, fully and uniformly mixing, heating a reaction system b in the reaction furnace under the condition of continuously introducing chlorine, collecting a gas product at 150-200 ℃, and cooling to obtain TiCl ₄ A product; collecting sublimates at 350-400 ℃ to obtain ZrCl ₄ A product; continuously heating the reaction system b to 830-870 ℃, naturally cooling to room temperature, and magnetically separating the obtained reaction product by a magnetic separator to obtain an iron concentrate product and solid residues for later use;

and step six, mixing the solid residues obtained in the step five with the filter cake B obtained in the step one, and then, transferring the mixture into a dryer for drying until the water content is not more than 3%, so as to obtain a powder product for producing the roadbed stone or the roadbed brick, and directly selling the powder product.

Further, in the first step, the volume percentage of the solid material in the ore pulp is 40-45%, and the adopted water is any one of tap water, well water or other industrial water.

Further, in the first step, the mass concentration of the concentrated sulfuric acid solution is 96-98%.

In the first step, the equipment used in the solid-liquid separation is any one of a filter press, a screw centrifuge and a belt vacuum filter.

Further, in the second step, the carbonate saturated solution is a sodium carbonate saturated solution or a sodium bicarbonate saturated solution.

Further, in the sixth step, the dryer used is a drum dryer.

Further, in the sixth step, the production formula of the road foundation stone is prepared from the following raw materials in parts by weight: 60-70 parts of powder product, 22-25 parts of 42.5# silicate cement, 3-8 parts of calcium oxide, 1-1.5 parts of glass fiber, 0.3-0.6 part of cement reinforcing agent, 0.05-0.1 part of additive and 6-8 parts of water.

Further, in the sixth step, the production formula of the roadbed brick is prepared from the following raw materials in parts by weight: 40-60 parts of powder products, 12-16 parts of 42.5# silicate cement, 6-10 parts of calcium oxide, 15-22 parts of coarse aggregate, 0.3-0.6 part of cement reinforcing agent, 0.05-0.1 part of additive and 8-10 parts of water.

Furthermore, the production formula of the roadbed stone or the roadbed brick is prepared by adopting a firing-free ceramic production process after being fully and uniformly mixed and pressing the roadbed stone or the roadbed brick at a low temperature under the pressure condition of 1800 t.

The invention has the beneficial effects that:

1. the full recycling method of the alumina red mud has simple process flow and convenient operation, and the process can simultaneously realize rare earth mineral products and TiCl containing rare earth metal lanthanum cerium yttrium by carrying out multi-step and orderly processing treatment on the red mud which is high in reserve and is difficult to treat and utilize industrial solid waste ₄ 、ZrCl ₄ And preparing five high-value and strong environment-friendly products from the iron ore concentrate and the roadbed stone raw materials. The method has the advantages of high available value of various products, wide application range and remarkable economic benefit. The full recycling method not only realizes the maximum consumption of the conventional industrial waste pollutant red mud, solves the technical problems of large yield, difficult treatment and serious environmental pollution, but also realizes the excellent effects of rich product types, wide industrial application range and high additional value, and raw materials can be fully recycled. Therefore, the resource utilization rate is high, the economic benefit and the social benefit are obvious, and the method has wide market application prospect.

2. According to the full recycling method of the alumina red mud, the red mud is subjected to preliminary pretreatment by adopting water and concentrated sulfuric acid, and the most valuable titanium, zirconium and rare earth metals in the red mud can be effectively extracted and enriched in the pretreatment operation for subsequent recycling and utilization. The process only uses cheap concentrated sulfuric acid as a pretreatment agent in the pretreatment step without adding any other chemical agent. Therefore, the cost of the treatment process is lower, and the economic benefit is better. Meanwhile, the whole process has no three-waste discharge, 100% total recovery of red mud, no secondary pollution in the whole process, meets the environmental protection requirement, has obvious recycling effect and is easy to be disposed on a large scale. And the equipment investment required in the treatment process is small, the cost is low, the industrial application is easy, and the harmless, reduction and recycling treatment of the alumina red mud are fully realized.

3. According to the full recycling method of the alumina red mud, the defects of strong alkalinity and salt enrichment of the red mud raw material are eliminated after the red mud raw material is pretreated. The remaining solid slag, although somewhat acidic, is already substantially neutral by neutralization with basic oxide calcium oxide. The pretreated red mud has no radioactive element, the total content of toxic elements such as lead, mercury, arsenic, cadmium and the like is not more than 0.05 percent, and the pretreated red mud can be used as a qualified building material raw material and has good economic benefit.

Detailed Description

The following are specific examples of the present invention, which are provided to facilitate a better understanding of the present invention, but are not intended to limit the present invention. The experimental operation process is carried out at normal temperature and normal pressure under the condition of no indication.

The full recycling method of the red mud comprises the following specific process steps:

firstly, adding water into a red mud raw material to prepare pulp with the volume percentage of solid materials of 40-45%, then dropwise adding a concentrated sulfuric acid solution with the mass concentration of 96-98% into the pulp under the condition of continuous stirring until foam is not generated in an obtained reaction system a, continuing stirring and reacting for 10-15min, and then carrying out solid-liquid separation on the obtained reaction product to obtain filtrate A and a filter cake B for later use;

in the step, the water is any one of tap water, well water or other industrial water; the equipment used in the solid-liquid separation is any one of a filter press, a spiral centrifuge or a belt vacuum filter.

Step two, adjusting the pH value of the filtrate A prepared in the step one by adopting a carbonate saturated solution until the pH value of the obtained mixture is 4.7-5.2, starting to generate precipitation when the solution becomes turbid, and then filtering the obtained mixture to prepare filtrate C and solid precipitate D for later use;

in this step, the saturated carbonate solution used is a saturated sodium carbonate solution or a saturated sodium bicarbonate solution.

Step three, because the filtrate C is rich in sulfate and other soluble salts, reverse osmosis filtration is carried out on the filtrate C prepared in the step two by adopting a reverse osmosis membrane to remove salt, so as to prepare desalted water and concentrated salt solution E which can be industrially recycled, and the desalted water is industrially recycled;

step four, evaporating and crystallizing the concentrated salt solution E prepared in the step three to prepare rare earth mineral products containing rare earth metals lanthanum, cerium and yttrium, wherein the total mass percent of the rare earth metals in the rare earth mineral products exceeds 1.5%, and the rare earth mineral products are high-quality rare earth mineral sources and can be directly sold;

step five, adding the solid precipitate D prepared in the step two into a reaction furnace which is pre-filled with carbon powder according to the mass ratio of the solid precipitate D to the carbon powder of (3-5): 1, fully and uniformly mixing, heating a reaction system b in the reaction furnace under the condition of continuously introducing chlorine, collecting a gas product at 150-200 ℃, and cooling to obtain TiCl ₄ A product; collecting sublimates at 350-400 ℃ to obtain ZrCl ₄ A product; continuously heating the reaction system b to 830-870 ℃, naturally cooling to room temperature, discharging, and magnetically separating the obtained reaction product by using a magnetic separator to obtain an iron concentrate product and solid residues for later use;

in the step, the reaction furnace can be completed by a single furnace one-pot method, or can be subjected to multiple heating reaction treatment by adopting a triple furnace mode.

And step six, mixing the solid residues obtained in the step five with the filter cake B obtained in the step one, and then, transferring the mixture into a roller dryer for drying until the water content is not more than 3%, thereby obtaining a powder product for producing the roadbed stone or the roadbed brick, and directly selling the powder product.

The production formula of the road foundation stone is prepared from the following raw materials in parts by weight: 60-70 parts of powder product, 22-25 parts of 42.5# silicate cement, 3-8 parts of calcium oxide, 1-1.5 parts of glass fiber, 0.3-0.6 part of cement reinforcing agent, 0.05-0.1 part of additive and 6-8 parts of water.

The production formula of the roadbed brick is prepared from the following raw materials in parts by weight: 40-60 parts of powder products, 12-16 parts of 42.5# silicate cement, 6-10 parts of calcium oxide, 15-22 parts of coarse aggregate, 0.3-0.6 part of cement reinforcing agent, 0.05-0.1 part of additive and 8-10 parts of water.

After the production formula of the roadbed stone or the roadbed brick is fully and uniformly mixed, the roadbed stone or the roadbed brick is prepared by adopting a full-automatic brick stone integrated machine of the SiAN silver horse group, matching with a firing-free ceramic production process and pressing at a low temperature under the pressure condition of 1800 t.

Therefore, the red mud treated by the process method can realize full recycling, does not generate secondary pollution, has obvious economic benefit and has good social benefit and environmental benefit.

Example 1

In the embodiment, the alumina red mud provided by the small Yang He red mud library of the eastern hope aluminum industry limited company of three gorges, henan province is used as the processing raw material, and the specific treatment process of the alumina red mud is as follows:

(1) Taking 1 kg of alumina red mud (from a small Yang He red mud warehouse of Sanjia eastern Oriental hope aluminum industry Co., ltd.), adding 400mL of tap water into the red mud, fully stirring the mixture to prepare ore pulp, then, under the condition of continuous stirring, beginning to dropwise add concentrated sulfuric acid solution, generating a large amount of foam at the beginning and rising the temperature, gradually disappearing the foam along with continuous addition and rapid stirring of the concentrated sulfuric acid, stopping adding acid when the foam is not generated any more, wherein the addition amount of the concentrated sulfuric acid is 108mL (about 200 g), continuing stirring and reacting for 10-15min, filtering by a belt type vacuum filter, and flushing a filter cake three times with 50 mL tap water each time in the process to obtain 506mL of filtrate A and 962 g of filter cake B;

(2) The PH value of the prepared 506mL filtrate A is regulated to 5.0 by adopting saturated solution of sodium carbonate, precipitation is generated, the obtained mixture containing the precipitation is filtered to prepare filtrate C and solid precipitation D, and the filtrate C contains 2.02 g/L of rare earth lanthanum, 3.96 g/L of cerium and 0.24 g/L of yttrium through detection; the mass percentage of the metal titanium in the solid precipitate D is 26.10 percent, the zirconium is 2.54 percent, and the iron is 35.23 percent, so that the solid precipitate D can be used for extracting metal;

(3) Reverse osmosis filtering the obtained filtrate C by adopting a reverse osmosis membrane to remove salt to obtain concentrated salt solution E and desalted water, wherein the desalted water is industrially recycled, and the concentrated salt solution E is subjected to evaporation crystallization treatment to obtain a rare earth mineral product containing rare earth metal lanthanum cerium yttrium, which can be directly sold;

(4) Fully mixing the solid precipitate D prepared in the step (2) with carbon powder, adding the mixture into a closed reaction furnace, heating the reaction furnace at a temperature of between 150 and 200 ℃ under the condition of continuously introducing chlorine, collecting a gas product at the temperature of between 150 and 200 ℃, and cooling the gas product to obtain TiCl ₄ A product; collecting sublimates at 350-400 ℃ to obtain ZrCl ₄ A product; then, continuously heating to 850 ℃, naturally cooling to room temperature, and carrying out magnetic separation on the obtained reaction product by a magnetic separator after discharging to obtain an iron concentrate product and solid residues for later use;

(5) Mixing the solid residue obtained in the step (4) with the filter cake B obtained in the step (1), and then, transferring the mixture into a roller dryer for drying until the water content is not more than 3%, thus obtaining 780g of powder product for producing the roadbed stone or the roadbed brick.

(6) And (3) adding 190 g of 42.5# silicate cement, 45 g of calcium oxide, 10 g of glass fiber, 3 g of cement reinforcing agent and 0.2 g of additive into 780g of powder product prepared in the step (5), uniformly mixing, adding 65 ml of water, stirring and molding, and pressing under 1800 tons of pressure to obtain the roadbed stone product, wherein the roadbed stone product can be directly sold and used.

Claims

1. The full recycling method of the red mud is characterized by comprising the following steps of:

firstly, adding water into a red mud raw material to prepare ore pulp, then dropwise adding a concentrated sulfuric acid solution with the mass concentration of 96-98% into the ore pulp under the condition of continuous stirring until no foam is generated in an obtained reaction system a, continuously stirring and reacting for 10-15min, and then carrying out solid-liquid separation on the obtained reaction product to obtain a filtrate A and a filter cake B for later use;

step six, mixing the solid residues obtained in the step five with the filter cake B obtained in the step one, and then, transferring the mixture into a dryer for drying until the water content is not more than 3%, so as to obtain a powder product for producing the roadbed stone or the roadbed brick, wherein the powder product can be directly sold;

the production formula of the road foundation stone is prepared from the following raw materials in parts by weight: 60-70 parts of powder product, 22-25 parts of 42.5# silicate cement, 3-8 parts of calcium oxide, 1-1.5 parts of glass fiber, 0.3-0.6 part of cement reinforcing agent, 0.05-0.1 part of additive and 6-8 parts of water;

2. The method for fully recycling red mud according to claim 1, which is characterized by comprising the following steps: in the first step, the volume percentage of solid materials in the ore pulp is 40-45%, and the adopted water is any one of tap water, well water or other industrial water.

3. The method for fully recycling red mud according to claim 1, which is characterized by comprising the following steps: in the first step, the equipment used in the solid-liquid separation is any one of a filter press, a spiral centrifuge and a belt vacuum filter.

4. The method for fully recycling red mud according to claim 1, which is characterized by comprising the following steps: in the second step, the carbonate saturated solution is sodium carbonate saturated solution or sodium bicarbonate saturated solution.

5. The method for fully recycling red mud according to claim 1, which is characterized by comprising the following steps: in step six, the dryer used is a drum dryer.

6. The method for fully recycling red mud according to claim 1, which is characterized by comprising the following steps: in the sixth step, the production formula of the roadbed stone or the roadbed brick is prepared by adopting a firing-free ceramic production process after being fully and uniformly mixed and pressing at a low temperature under the pressure condition of 1800 t.