CN113354309A

CN113354309A - Modified red mud powder and preparation method thereof

Info

Publication number: CN113354309A
Application number: CN202110386058.4A
Authority: CN
Inventors: 高建阳; 刘世杰; 郭淑敏; 张晓阳; 李克甫; 陈玉海; 袁崇良; 李颍; 纪蒙; 赵冠南; 刁克建; 刘建峰; 郑霞; 刘翔宇; 李吉义; 张秀平; 牟涛
Original assignee: Chalco Shandong Co ltd; Chinalco Shandong Environmental Protection Technology Co ltd
Current assignee: Chalco Shandong Co ltd; Chinalco Shandong Environmental Protection Technology Co ltd
Priority date: 2021-04-09
Filing date: 2021-04-09
Publication date: 2021-09-07
Anticipated expiration: 2041-04-09
Also published as: CN113354309B

Abstract

The invention provides modified red mud powder, which belongs to the technical field of light metal metallurgy, and is prepared from raw materials of the modified red mud powder, wherein the raw materials of the modified red mud powder comprise a composite modification auxiliary agent and red mud, the composite modification auxiliary agent comprises a dispersing auxiliary agent, a stabilizing auxiliary agent and a water reducing auxiliary agent, the mass ratio of the composite modification auxiliary agent to the solid mass of the red mud is (6-30) to (70-94), and the mass ratio of the dispersing auxiliary agent to the stabilizing auxiliary agent to the water reducing auxiliary agent is 1 to (0-0.15) to (0-0.05). The modified red mud powder can replace clay, is used as a raw material in the fields of building materials, cement and the like, solves the problem of red mud stacking, reduces the consumption of the clay in the manufacturing industries of building materials, cement and the like, and protects clay resources from being over developed. The invention also provides a preparation method of the modified red mud powder.

Description

Modified red mud powder and preparation method thereof

Technical Field

The invention belongs to the technical field of light metal metallurgy, and particularly relates to modified red mud powder and a preparation method thereof.

Background

Red mud, a waste produced in the process of refining alumina from bauxite, is known as red-red mud slurry.With the continuous development of the bauxite industry, the red mud discharge amount of China is more than 1500 million tons every year, and the total mass of the red mud tends to increase with the new production and the yield increase transformation of old equipment. Most alumina factories around the world pile or dump red mud into deep sea, the storage of the red mud not only occupies a large amount of land and farmland and consumes more construction and maintenance cost of a storage yard, but also residual alkaline liquor in the red mud can permeate underground to cause groundwater pollution. In addition, dust formed by red mud in a yard flies everywhere, so that the ecological environment is damaged, and serious pollution is caused. In the current society where land resources are increasingly tense and environmental protection is increasingly important, comprehensive treatment of red mud has become one of the focuses of people. The red mud is the largest waste generated in the production process of the alumina and also the largest pollution source in the production of the alumina. Due to the difference between the production method and the bauxite grade, about 0.5 to 2.5 tons of red mud are generated for each ton of alumina, and 3 to 4m is additionally added for each ton of red mud³The alkali-containing waste liquid.

The red mud can be divided into three types of red mud, namely sintering process, Bayer process and combination process, according to different alumina production methods, and the alumina production methods adopted at home and abroad are different due to different bauxite content abundance. Except China, other countries mostly adopt Bayer process production, and the yield of the Bayer process accounts for more than 90% of the total world yield. The Bayer process adopts strong base NaOH to dissolve out high-alumina and high-iron bauxite, and the red mud produced has high alumina, iron oxide and alkali content; the bauxite of boehmite type and gibbsite type are treated. The sintering method and the combined method are used for treating indissolvable bauxite with high silicon content, low iron content, diaspore type bauxite and kaolinite type bauxite, and the red mud Ca0 generated by the method is high in content and low in alkali and iron content. The red mud is mainly produced by Bayer process and the red mud is mainly produced by hematite, sodium aluminosilicate hydrate, cancrinite and the like.

In the aspect of recovering metallic iron in red mud, a great deal of research is carried out in various countries, and although the time of foreign research is relatively early and is mostly 60-80 years, a great deal of practical application is still not available at present. In China, the plane bauxite contains various valuable metals, the plane bauxite industry company and Guangxi metallurgical research institute jointly make a test research of direct reduction ironmaking by taking the Bayer process red mud of plane bauxite as a raw material and coal as a reducing agent, and the process flow comprises the steps of mixing the red mud and the coal, briquetting, drying, then carrying out reduction roasting, and finally carrying out magnetic separation to prepare sponge iron.

At present, Ganxzhou color research institute and other companies adopt a high-gradient and high-strength magnetic separator to recover iron in red mud, quartz is not obtained, and meanwhile, the investment and operation cost is high and the recovery rate is low.

The development of the red mud application technology is greatly limited by the problems of red mud alkali and water content, and cannot be well utilized all the time.

The red mud has high viscosity, high water content, thixotropic property, difficult drying, long time and great utilization difficulty.

In the aspect of red mud resource utilization, the alumina industry in China successively develops technical research works in the aspects of producing cement from red mud, producing novel wall materials such as baking-free bricks and sintered bricks from red mud, producing silicon-calcium board thermal insulation materials from red mud, using red mud plastic fillers, using red mud silicon-calcium fertilizers and extracting valuable metals such as scandium, titanium and iron from red mud, and the like, and some progress is made, but the large-scale utilization of the red mud is not realized by other technologies except the production of cement from red mud ingredients.

The red mud produced by sintering process contains SiO necessary for silicate cement₂、Fe₂O₃、Al₂O₃CaO, and the like, the content of the useful components accounts for more than 75 percent of the total amount, and the components are selected from SiO₂-Al₂O₃the-CaO ternary system phase diagram is close to the composition range of cement clinker. In China, the original Shandong aluminum industry company always goes ahead of the nation in the aspect of popularization and application of cement produced by sintering red mud, the last 60 th century begins, common portland cement is produced by using the sub-clay characteristic of the red mud and replacing industrial raw materials such as clay by the red mud by adopting a wet process, more than 800 million tons of red mud is consumed in an accumulated way, and the produced common portland cement is used for wharfs, ports, docks, naval vessel shelters and yellow river railway highwaysRoad bridges, large coal mines, Antarctic survey stations, civil buildings of factory buildings and the like, but as the last 90 century, the requirement on the alkali content of cement is increased because the state implements a new cement standard, so that the mixing amount of cement produced by red mud ingredients is greatly reduced.

At present, a large amount of clay is used in domestic and foreign building materials, brick and tile plants and cement plants, and the clay is used as a resource and occupies a very important position in national economy. The development and utilization of clay minerals has become a popular industry in the world today. The clay is not available in the industries of building materials, papermaking, rubber, enamel, refractory materials, environmental protection, chemical engineering, textile, petroleum, agriculture and the like. The clay rock resources are distributed in various places in China. China has ascertained that the basal reserves: the ingredients are 10 hundred million tons of clay which is mainly distributed in provinces (regions) such as Henan, Jiangsu, Guangxi, Anhui, inner Mongolia, Heilongjiang, Guizhou, Jilin, Shanxi, Fujian, Shandong, Hebei, Hubei, Guangdong, Qinghai and the like.

Disclosure of Invention

In order to solve the technical problems of red mud stacking and difficult reasonable utilization, the invention provides modified red mud powder which can replace clay and be used as a raw material in the fields of building materials, cement and the like, solves the red mud stacking problem, reduces the consumption of the clay in the manufacturing industries of building materials, cement and the like, and protects the clay resource from being over developed.

The invention also provides a preparation method of the modified red mud powder.

The invention is realized by the following technical scheme:

the invention provides modified red mud powder, which is prepared from raw materials comprising a composite modification auxiliary agent and red mud, wherein the composite modification auxiliary agent comprises a dispersing auxiliary agent, a stabilizing auxiliary agent and a water reducing auxiliary agent, the mass ratio of the composite modification auxiliary agent to the solid mass of the red mud is (6-30) to (70-94), and the mass ratio of the dispersing auxiliary agent to the stabilizing auxiliary agent to the water reducing auxiliary agent is 1 (0-0.15) to (0-0.05).

Optionally, the dispersing aid comprises at least one of sintering red mud, calcium hydroxide, carbide slag, magnesium carbonate, fly ash, furnace slag, quicklime and slag powder.

Optionally, the stabilizing additive includes at least one of quartz powder, kaolin, shale, bentonite, montmorillonite and silica fume.

Optionally, the water-reducing additive comprises at least one of sodium tripolyphosphate, sodium silicate, sodium hexametaphosphate and lignosulfonate.

Based on the same invention concept, the invention also provides a preparation method of the modified red mud powder, which comprises the following steps:

mixing a dispersing auxiliary agent, a stabilizing auxiliary agent and a water-reducing auxiliary agent to obtain a composite modified auxiliary agent;

mixing the composite modifying additive with the red mud to obtain modified red mud;

aging the modified red mud, and then crushing to obtain modified red mud powder;

wherein the mass ratio of the dispersing auxiliary agent to the stabilizing auxiliary agent to the water-reducing auxiliary agent is 1 (0-0.15) to 0-0.05;

the ratio of the mass of the composite modification auxiliary agent to the solid mass of the red mud is (6-30) to (70-94).

Optionally, the dispersing aid, the stabilizing aid and the water-reducing aid are mixed to obtain a composite modified aid, which specifically comprises:

uniformly mixing and stirring a dispersing auxiliary agent, a stabilizing auxiliary agent and a water-reducing auxiliary agent to obtain a composite modification auxiliary agent, wherein in the composite modification auxiliary agent, [ Si ]: [ Al ] (0.5-6): 1, [ Si ]: and (0.1-5) 1, wherein the water content is 1-30%, wherein [ Si ] represents the mass fraction of Si element in the composite modification auxiliary agent, [ Al ] represents the mass fraction of Al element in the composite modification auxiliary agent, and [ Ca ] represents the mass fraction of Ca element in the composite modification auxiliary agent.

Optionally, in the composite modification auxiliary agent, [ Si ]: [ Al ] - (1-5): 1, [ Si ]: and [ Ca ] (0.1-4): 1, water content of 1-20%, and particle size d50 of 1-150 um, wherein [ Si ] represents the mass fraction of Si element in the composite modification aid, [ Al ] represents the mass fraction of Al element in the composite modification aid, and [ Ca ] represents the mass fraction of Ca element in the composite modification aid.

Optionally, the composite modifying additive is mixed with red mud to obtain modified red mud, and the method specifically comprises the following steps:

and mixing and stirring the composite modification auxiliary agent and the red mud with the water content of 22-41% uniformly to obtain the modified red mud with the water content of 5-30%.

Optionally, the red mud is Bayer process filter-pressed red mud, the water content is 32-38%, and the ratio of the mass of the composite modification auxiliary agent to the solid mass of the red mud is (10-25) to (75-90).

Optionally, the modified red mud is aged and then crushed to obtain modified red mud powder, and the method specifically comprises the following steps:

aging the modified red mud for 0.1-10 h, and then crushing to obtain modified red mud powder with the particle size d50 of 10-3000 mu m, wherein the water content of the modified red mud powder is 5-28%.

One or more technical schemes in the invention at least have the following technical effects or advantages:

1. the modified red mud powder takes the dispersing assistant, the stabilizing assistant, the water reducing assistant and the red mud as raw materials, compared with the red mud on the dam, the red mud reduces the red mud transportation cost, the damming cost, the maintenance cost and the exploitation cost, the demand for composite modification auxiliary agent is smaller, the cost of raw materials is reduced, the red mud contains a large amount of Si, Al, Fe and Na elements and is an ideal raw material used as a clay substitute, the viscosity of the red mud can be reduced by the dispersing auxiliary agent, the stability of the physical characteristics of the modified red mud can be ensured by the stabilizing auxiliary agent, the water content of the modified red mud powder can be controlled by the water reducing auxiliary agent, the pulverization of the red mud is facilitated, the modified red mud powder can replace the clay and be used as a raw material in the fields of building materials, cement and the like, the problem of red mud stockpiling is solved, and the consumption of clay in the manufacturing industries of building materials, cement and the like is reduced, and the clay resource is protected from being over developed.

2. The invention relates to a preparation method of modified red mud powder, which is characterized in that a dispersing auxiliary agent, a stabilizing auxiliary agent and a water reducing auxiliary agent are mixed to prepare a composite modified auxiliary agent, and then the composite modified auxiliary agent is mixed with red mud, so that the red mud can be more fully mixed with the dispersing auxiliary agent, the stabilizing auxiliary agent and the water reducing auxiliary agent, the modified red mud is aged, the physical and chemical properties of the red mud are stabilized and uniform, and then the red mud is crushed to obtain the modified red mud powder.

The foregoing description is only an overview of the technical solutions of the present invention, and the embodiments of the present invention are described below in order to make the technical means of the present invention more clearly understood and to make the above and other objects, features, and advantages of the present invention more clearly understandable.

Drawings

In order to more clearly illustrate the technical solution of the present invention, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on the drawings without creative efforts.

FIG. 1 is a flow chart of a preparation method of modified red mud powder according to the invention.

Detailed Description

The present invention will be described in detail below with reference to specific embodiments and examples, and the advantages and various effects of the present invention will be more clearly apparent therefrom. It will be understood by those skilled in the art that these specific embodiments and examples are for the purpose of illustrating the invention and are not to be construed as limiting the invention.

Throughout the specification, unless otherwise specifically noted, terms used herein should be understood as having meanings as commonly used in the art. Accordingly, 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. If there is a conflict, the present specification will control.

Unless otherwise specifically stated, various raw materials, reagents, instruments, equipment and the like used in the present invention are commercially available or can be prepared by existing methods.

It should be further noted that the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.

It is noted that, in this document, relational terms such as "first" and "second," and the like, may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions.

In order to solve the technical problems, the general idea of the invention is as follows:

according to a typical embodiment of the invention, modified red mud powder is provided, wherein the modified red mud powder comprises a composite modification auxiliary agent and red mud, the composite modification auxiliary agent comprises a dispersing auxiliary agent, a stabilizing auxiliary agent and a water reducing auxiliary agent, the mass ratio of the composite modification auxiliary agent to the solid mass of the red mud is (6-30) to (70-94), and the mass ratio of the dispersing auxiliary agent to the stabilizing auxiliary agent to the water reducing auxiliary agent is 1 (0-0.15) to (0-0.05).

According to the invention, the modified red mud powder takes the dispersing auxiliary agent, the stabilizing auxiliary agent, the water reducing auxiliary agent and the red mud as raw materials, the red mud reduces the transportation cost, the damming cost, the maintenance cost and the exploitation cost of the red mud compared with the red mud on the dam, the demand for the composite modifying auxiliary agent is smaller, the raw material cost is reduced, the red mud contains a large amount of Si, Al, Fe and Na elements and is an ideal raw material used as a clay substitute, the dispersing auxiliary agent can reduce the viscosity of the red mud, the stabilizing auxiliary agent can ensure the stability of the physical characteristics of the modified red mud, and the water reducing auxiliary agent can control the water content of the modified red mud powder and is beneficial to realizing the pulverization of the red mud.

According to the invention, the ratio of the quality of the composite modification auxiliary agent to the solid matter quality of the red mud is (6-30) to (70-94), which has the advantages of ensuring the viscosity reduction and effective dispersion of the red mud, the use amount of the composite modification auxiliary agent is less than the range, which causes poor viscosity reduction effect, and the use amount of the composite modification auxiliary agent is higher than the range, which causes high raw material cost, the mass ratio of the dispersion auxiliary agent, the stabilization auxiliary agent and the water reducing auxiliary agent is 1 (0-0.15) to (0-0.05), which has the advantages of making the physicochemical properties of the red mud uniform and stable, the use amount of the stabilization auxiliary agent and the water reducing auxiliary agent is too low, which causes poor physicochemical property uniformity, and the use amount of the stabilization auxiliary agent and the water reducing auxiliary agent is higher than the range, which causes high raw material cost.

According to the invention, the red mud is subjected to filter pressing by using a Bayer process, the Bayer process filter-pressed red mud is the Bayer process red mud which is directly pressed into the red mud filter cake with the target water content by using the filter press, and compared with the dam red mud, the Bayer process filter-pressed red mud reduces the red mud transportation cost, the dam building cost, the maintenance cost and the exploitation cost, has smaller demand on the composite modification auxiliary agent, and reduces the raw material cost.

In the present invention, the mass of the solid matter refers to the mass of the solid matter remaining after the moisture of the red mud is removed.

As an optional embodiment, the dispersing aid includes at least one of sintering red mud, calcium hydroxide, carbide slag, magnesium carbonate, fly ash, slag, quicklime, and slag powder.

In the invention, the dispersing auxiliary agent adopts at least one of sintering process red mud, calcium hydroxide, carbide slag, magnesium carbonate, fly ash, furnace slag, quicklime and slag powder, which brings the advantages of fully reducing the viscosity of the Bayer process red mud and improving the dispersion degree.

As an alternative embodiment, the stabilizing aid includes at least one of quartz powder, kaolin, shale, bentonite, montmorillonite and silica fume.

According to the invention, the stabilizing additive comprises at least one of quartz powder, kaolin, shale, bentonite, montmorillonite and silica residue, and has the advantage that the physicochemical property of the modified red mud can be further stabilized according to the change of the chemical components of the red mud.

As an alternative embodiment, the water reducing additive comprises at least one of sodium tripolyphosphate, sodium silicate, sodium hexametaphosphate, and lignosulfonate.

According to the invention, the water reducing additive comprises at least one of sodium tripolyphosphate, sodium silicate, sodium hexametaphosphate and lignosulfonate, and the water reducing additive has the advantages that the physical state of the red mud can be further stabilized and modified according to the moisture change of the red mud, so that a good foundation is laid for the next aging and crushing.

According to another exemplary embodiment of the present invention, there is provided a method of preparing modified red mud powder, as shown in fig. 1, the method comprising:

s1, mixing a dispersing auxiliary agent, a stabilizing auxiliary agent and a water reducing auxiliary agent to obtain a composite modified auxiliary agent.

As an optional embodiment, the mixing of the dispersing aid, the stabilizing aid and the water-reducing aid to obtain the composite modifying aid specifically includes:

In the invention, the dispersing auxiliary agent, the stabilizing auxiliary agent and the water-reducing auxiliary agent are mixed and stirred uniformly, and in the prepared composite modifier, [ Si ]: [ Al ] is controlled to be (0.5-6) 1, [ Si ]: and (0.1-5) the 1 has the advantages that on one hand, the viscosity of the formed mixed high-silicon material can be reduced, the dispersity is improved, on the other hand, a foundation is laid for later-stage red mud crushing, red mud powder cannot be obtained if the ratio is too low, the cost is too high if the ratio is over the range, the water content is controlled to be 1-30%, the foundation is laid for later-stage red mud powder obtaining, the treatment cost is high if the ratio is below the range, and the red mud powder is not easy to crush if the ratio is over the range.

As a preferred embodiment, in the composite modification aid, [ Si ]: [ Al ] - (1-5): 1, [ Si ]: and [ Ca ] (0.1-4): 1, water content of 1-20%, and particle size d50 of 1-150 um, wherein [ Si ] represents the mass fraction of Si element in the composite modification aid, [ Al ] represents the mass fraction of Al element in the composite modification aid, and [ Ca ] represents the mass fraction of Ca element in the composite modification aid.

In the invention, the particle size d50 in the composite modification auxiliary agent is 1-150 um, which has the advantages of being capable of matching with the particle size of red mud, and being difficult to mix with the red mud when the particle size is too low or too high.

S2, mixing the composite modification auxiliary agent with the red mud to obtain modified red mud;

as an optional embodiment, the mixing of the composite modifying additive and the red mud to obtain the modified red mud specifically comprises:

As an optional embodiment, the red mud is Bayer process filter-pressed red mud, the water content is 32-38%, and the ratio of the mass of the composite modification auxiliary agent to the solid mass of the red mud is (10-25): 75-90).

S3, aging the modified red mud, and then crushing to obtain modified red mud powder;

According to the invention, the dispersing auxiliary, the stabilizing auxiliary and the water reducing auxiliary are mixed to prepare the composite modifying auxiliary, and then the composite modifying auxiliary is mixed with the red mud, so that the red mud can be more fully mixed with the dispersing auxiliary, the stabilizing auxiliary and the water reducing auxiliary, and the modified red mud is aged, so that the aging aims to make the moisture and the physicochemical properties of the red mud more stable, and then the red mud is crushed to obtain the modified red mud powder, thereby overcoming the problems of large viscosity and large moisture of the traditional red mud, recovering the original particle size distribution in a short process, and preparing the clay red mud powder with different silicon-aluminum ratios, and being suitable for different types of building material raw materials.

As an optional implementation manner, the modified red mud is aged and then crushed to obtain modified red mud powder, which specifically comprises:

aging the modified red mud for 0.1-10 h, and then crushing, specifically: controlling the rotating speed of the crusher to be 20-2000 r/min, preferably 100-400 r/min, and controlling the time to be 0.01-2h to obtain the modified red mud powder with the granularity d50 of 10-3000 mu m, wherein the water content of the modified red mud powder is 5-28%.

In the invention, the aging time is 0.1-10 h, which has the advantages of making the physical and chemical properties of the red mud stable and uniform, easily causing non-uniform components below the range, and affecting the production efficiency above the range.

The modified red mud powder and the preparation method thereof according to the present invention will be described in detail below with reference to examples, comparative examples and experimental data.

Example 1

The preparation method of the modified red mud powder comprises the following steps:

(1) mixing and stirring red mud, quartz powder and sodium tripolyphosphate according to the mass ratio of 1:0.02:0.01 to obtain a composite modification auxiliary agent [ Si ]: [ Al ] ═ 1.2, [ Si ]: [ Ca ] ═ 1: 1; the water content is 10 percent;

(2) taking red mud with the solid weight of 100g, adding 10g of modified composite auxiliary agent into the red mud with the water content of 38%, and uniformly mixing to obtain modified red mud with the water content of 26%; d50:10 um.

(3) And (3) aging the modified red mud for 0.1h, and then crushing, wherein the rotating speed of a crusher is controlled to be 100 revolutions per minute, and the crushing time is controlled to be 1h, so that 108g of modified red mud powder is obtained.

In this example, the modified red mud powder obtained had a water content of 15% and a particle size D50 of 25 um.

Example 2

(1) mixing and stirring calcium hydroxide, montmorillonite and sodium silicate according to the mass ratio of 1:0.15:0.04 to obtain a composite modification auxiliary agent, wherein the composite modification auxiliary agent [ Si ]: [ Al ] ═ 2.1; [ Si ]/[ Ca ] ═ 0.8:1, d50:90um, water content 1%;

(2) taking red mud with the solid weight of 100g, adding 25g of modified composite auxiliary agent into the red mud with the water content of 32%, and uniformly mixing to obtain modified red mud with the water content of 15%;

(3) and aging the modified red mud for 1h, and then crushing, wherein the rotating speed of a crusher is controlled at 400 rpm, and the crushing time is controlled at 0.06h, so as to obtain 120g of modified red mud powder.

In this example, the modified red mud powder obtained had a water content of 23% and a particle size D50 of 1000. mu.m.

Example 3

(1) mixing and stirring the carbide slag, the silicon slag and the sodium hexametaphosphate according to the mass ratio of 1:0.1:0.02 to obtain a composite modification auxiliary agent, wherein the composite modification auxiliary agent [ Si ]: 1.8, [ Si ]/[ Ca ] - [ 4: 1; the water content is 8 percent;

(2) taking red mud with the solid weight of 100g, adding 18g of modified composite auxiliary agent into the red mud with the water content of 36%, and uniformly mixing to obtain modified red mud with the water content of 10%;

(3) and ageing the modified red mud for 0.5h, and then crushing, wherein the rotating speed of a crusher is controlled to 300 revolutions per minute, and the crushing time is controlled to 0.5h, so that 115g of modified red mud powder is obtained.

In this example, the modified red mud powder obtained had a water content of 19% and a particle size D50 of 390 μm.

Comparative example 1

This comparative example differs from example 1 only in that: the composite modification auxiliary agent does not contain sintering process red mud.

Comparative example 2

This comparative example differs from example 1 only in that: the composite modification auxiliary agent does not contain quartz powder.

Comparative example 3

This comparative example differs from example 1 only in that: the composite modifying additive does not contain sodium tripolyphosphate.

Comparative example 4

This comparative example differs from example 1 only in that: in the composite modified additive, the mass ratio of the sintering red mud, the quartz powder and the sodium tripolyphosphate is 1:0.2: 0.01.

The test method related to each embodiment of the application is as follows:

the method for testing the water content comprises the following steps: GB/T14685-2011;

the test method for the particle size D50 is as follows: GB/T10322.7-2004;

[ Si ]: [ Al ] test method: YS/T575.1-2007, YS/T575.2-2007;

the test method for [ Si ]/[ Ca ] is as follows: YS/T575.1-2007, YS/T575.7-2007.

Related experiments:

the modified red mud powders obtained in examples 1 to 3 and comparative examples 1 to 4 were subjected to performance tests, and the test results are shown in Table 1.

TABLE 1 data on the properties of modified red mud powders obtained in examples 1-3 and comparative examples 1-4

	Water content (%)	Particle size D50(μm)
			Example 1	15	25
Example 2	23	1000
			Example 3	19	390
Comparative example 1	28	2800
			Comparative example 2	5	1600
Comparative example 3	18	260
			Comparative example 4	22	180

As can be seen from Table 1, the water content and particle size of the modified red mud powders prepared in examples 1-3 are closer to the clay property than those of comparative examples 1-4, the problems of large viscosity and large water content of red mud are overcome, the original particle size distribution is recovered, and the clay red mud powders with different silica-alumina ratios are prepared and are suitable for different types of building materials.

One or more technical solutions in the present invention at least have the following technical effects or advantages:

(1) the modified red mud powder takes the dispersing assistant, the stabilizing assistant, the water reducing assistant and the red mud as raw materials, compared with the red mud on the dam, the red mud reduces the red mud transportation cost, the damming cost, the maintenance cost and the exploitation cost, the demand for composite modification auxiliary agent is smaller, the cost of raw materials is reduced, the red mud contains a large amount of Si, Al, Fe and Na elements and is an ideal raw material used as a clay substitute, the viscosity of the red mud can be reduced by the dispersing auxiliary agent, the stability of the physical characteristics of the modified red mud can be ensured by the stabilizing auxiliary agent, the water content of the modified red mud powder can be controlled by the water reducing auxiliary agent, the pulverization of the red mud is facilitated, the modified red mud powder can replace the clay and be used as a raw material in the fields of building materials, cement and the like, the problem of red mud stockpiling is solved, and the consumption of clay in the manufacturing industries of building materials, cement and the like is reduced, and the clay resource is protected from being over developed.

(2) The modified red mud powder has the advantages that the ratio of the quality of the composite modification auxiliary agent to the solid matter quality of the red mud is (6-30): (70-94), the viscosity reduction effect is poor when the dosage of the composite modification auxiliary agent is less than the range, the raw material cost is high when the dosage of the composite modification auxiliary agent is higher than the range, the physicochemical properties of the red mud are uniform and stable when the dosage of the dispersion auxiliary agent, the stabilization auxiliary agent and the water reducing auxiliary agent is 1: (0-0.15): (0-0.05), the physicochemical properties are poor when the dosage of the stabilization auxiliary agent and the water reducing auxiliary agent is too low, and the raw material cost is high when the dosage of the stabilization auxiliary agent and the water reducing auxiliary agent is higher than the range.

(3) The invention relates to a preparation method of modified red mud powder, which is characterized in that a dispersing auxiliary agent, a stabilizing auxiliary agent and a water reducing auxiliary agent are mixed to prepare a composite modified auxiliary agent, and then the composite modified auxiliary agent is mixed with red mud, so that the red mud can be more fully mixed with the dispersing auxiliary agent, the stabilizing auxiliary agent and the water reducing auxiliary agent, the modified red mud is aged, the red mud has thixotropy, the aging aims to make the moisture and the physical and chemical properties of the red mud more stable, and then the red mud is crushed to obtain the modified red mud powder.

Finally, it should also be noted that the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.

While preferred embodiments of the present invention have been described, additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. Therefore, it is intended that the appended claims be interpreted as including preferred embodiments and all such alterations and modifications as fall within the scope of the invention.

It will be apparent to those skilled in the art that various changes and modifications may be made in the present invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.

Claims

1. The modified red mud powder is characterized in that the modified red mud powder is prepared from composite modification aids and red mud, the composite modification aids comprise dispersing aids, stabilizing aids and water-reducing aids, the mass ratio of the composite modification aids to the solid mass of the red mud is (6-30) to (70-94), and the mass ratio of the dispersing aids, the stabilizing aids and the water-reducing aids is 1 to (0-0.15) to (0-0.05).

2. The modified red mud powder as claimed in claim 1, wherein the dispersing aid comprises at least one of sintered red mud, calcium hydroxide, carbide slag, magnesium carbonate, fly ash, slag, quicklime and slag powder.

3. The modified red mud powder of claim 1, wherein the stabilizing additive comprises at least one of quartz powder, kaolin, shale, bentonite, montmorillonite and silica fume.

4. The modified red mud powder of claim 1, wherein the water-reducing additive comprises at least one of sodium tripolyphosphate, sodium silicate, sodium hexametaphosphate and lignosulfonate.

5. A method for preparing modified red mud powder according to any one of claims 1 to 4, wherein the method comprises:

wherein the mass ratio of the dispersing auxiliary agent to the stabilizing auxiliary agent to the water-reducing auxiliary agent is 1 to (0-0.15) to (0-0.05);

the mass ratio of the composite modification auxiliary agent to the solid mass of the red mud is (6-30) to (70-94).

6. The preparation method of the modified red mud powder as claimed in claim 5, wherein the mixing of the dispersing aid, the stabilizing aid and the water-reducing aid to obtain the composite modifying aid specifically comprises:

and uniformly mixing and stirring a dispersing aid, a stabilizing aid and a water-reducing aid to obtain a composite modification aid, wherein in the composite modification aid, [ Si ]: Al ] - (0.5-6) to 1, [ Si ]: Ca ] - (0.1-5) to 1, and the water content is 1-30%, wherein [ Si ] represents the mass fraction of Si element in the composite modification aid, [ Al ] represents the mass fraction of Al element in the composite modification aid, and [ Ca ] represents the mass fraction of Ca element in the composite modification aid.

7. The method of claim 6, wherein [ Si ]: [ Al ]: 1, (0.1-4): 1, water content is 1-20%, and particle size d50 is 1-150 um, wherein [ Si ] represents the mass fraction of Si element in the composite modifying aid, [ Al ] represents the mass fraction of Al element in the composite modifying aid, and [ Ca ] represents the mass fraction of Ca element in the composite modifying aid.

8. The preparation method of the modified red mud powder according to claim 5, wherein the modified red mud is obtained by mixing the composite modification auxiliary agent with red mud, and specifically comprises the following steps:

9. The preparation method of the modified red mud powder as claimed in claim 8, wherein the red mud is Bayer process press-filtered red mud, the water content is 32-38%, and the mass ratio of the composite modification auxiliary agent to the solid matter of the red mud is (10-25) to (75-90).

10. The preparation method of the modified red mud powder as claimed in claim 1, wherein the modified red mud is aged and then crushed to obtain the modified red mud powder, and the method specifically comprises the following steps: