CN114409374B

CN114409374B - Preparation method of red mud for ceramic preparation and firing method of red mud product

Info

Publication number: CN114409374B
Application number: CN202210168780.5A
Authority: CN
Inventors: 布德
Original assignee: Inner Mongolia Bude Ethnic Culture Development Co ltd
Current assignee: Inner Mongolia Bude Ethnic Culture Development Co ltd
Priority date: 2022-02-23
Filing date: 2022-02-23
Publication date: 2023-05-02
Anticipated expiration: 2042-02-23
Also published as: CN114409374A

Abstract

The invention provides a preparation method of red mud for ceramic manufacture and a firing method of a red mud product, belonging to the technical field of red mud preparation and firing, wherein the preparation method of the red mud comprises the following steps: respectively selecting clean natural red soil and sand; mixing natural red soil and sand to obtain a mixture, and grinding and crushing to obtain slurry; airing the slurry to obtain clay; and (3) putting the clay into a pugging machine for pugging to obtain the red mud for ceramic manufacture. The firing method of the red mud product comprises the following steps: selecting red mud for ceramic making, putting the red mud into a model, and then pressing the red mud by a skin pressing machine to obtain a wet blank; airing the wet blank until the wet blank is thoroughly dried and no moisture on the surface oozes out, so as to obtain a dry blank; and (3) sending the dried blank into an electric kiln for high-temperature firing, and then cooling to room temperature to obtain the red mud product. The preparation method of the red mud and the firing method of the red mud product are used for solving the problems of reduced natural red mud resources, large natural red mud firing shrinkage and easy deformation.

Description

Preparation method of red mud for ceramic preparation and firing method of red mud product

Technical Field

The invention relates to the technical field of red mud preparation and firing, in particular to a preparation method of red mud for ceramic manufacture and a firing method of red mud products.

Background

The pottery is a ceramic product with Chinese traditional characteristics, integrates practicality, functionality, ornamental, artistic quality and collection, and is popular with people. The ceramic product mainly has two main purposes in production and life: firstly, the artistic work is used as an artwork for appreciation and collection; secondly, the product is used as a household utensil, such as tea set, tableware, wine set, rice set and the like. Firewood firing is the oldest firing technology of pottery, but because of the reasons of difficult control of temperature, high firing cost, difficult control of product quality and the like, a large number of factories currently adopt gas furnace firing and electric furnace firing technologies with easy control of firing temperature and product quality and relatively low rejection rate.

The traditional ceramic mud material mainly comprises red mud and white mud, the content of iron oxide in red mud ore is high, a superior person is bright and clean, red light is slightly seen in orange, and inferior persons are disordered and haze and are not commonly tolerant. Because the red mud contains abundant iron elements, and iron is an important colorant in the glaze, the sintered red mud product mainly takes the colors of vermilion, crab apple, vermilion and the like according to different iron content, and can meet different demands of consumers. However, natural red mud is becoming increasingly scarce in resources and, therefore, alternative materials are being sought to meet the ever-increasing demands for long-term scale exploitation of mineral resources and products. The existing red mud is a product formed by strong weathering in a humid and hot climatic environment, has obvious red color due to the fact that the red mud contains more ferric oxide, and is soil with the characteristics of high water content, low density, high strength and low compressibility, good plasticity and easy molding. The laterite is rich in resources in China and is widely distributed, and the laterite is also a raw material for producing various jars such as wine jars, pickle jars and the like. Although laterite also has its prominent disadvantages: the firing shrinkage is large and the material is easy to deform, but the laterite with more abundant resources is adopted as the raw material to process and manufacture the novel pug, which has important significance for the sustainable development of the related industry of the red mud product. However, so far, few reports are published in China about the technical results of processing and manufacturing red mud products and mud materials thereof. Therefore, the invention aims to research and prepare a red mud pug which takes red mud as a raw material, does not add any artificial pigment, can be used for preparing ceramics, and burns red mud products according to the performance and characteristics of the pug.

Disclosure of Invention

The invention provides a preparation method of red mud for ceramic manufacture and a firing method of a red mud product, which are used for solving the problems of reduced natural red mud resources, large natural red mud firing shrinkage and easy deformation. The invention takes natural red soil and sand as raw materials, provides a novel preparation method of red mud, enriches the variety of red mud products, and can obtain red mud products with excellent quality by adopting an optimized firing process.

In a first aspect, the invention provides a method for preparing red mud for ceramic manufacture, comprising:

respectively selecting clean natural red soil and sand for later use;

mixing natural red soil and sand to obtain a mixture, and grinding and crushing to obtain slurry;

airing the slurry to obtain clay; and, a step of, in the first embodiment,

putting clay into a pugging machine for pugging, and repeating pugging for 2-4 times to obtain red mud for ceramic preparation;

the chemical composition and the content of the natural laterite are as follows: siO (SiO) ₂ 55-60% of Al ₂ O ₃ 15-18% of Fe ₂ O ₃ 6-8% of TiO ₂ 0.5-1.0%, caO 2-3%, mgO 1.0-2.5%, K ₂ O is 2-3%, na ₂ O is 1-1.5%, and ignition decrement is 8-9%.

According to the invention, natural red soil and sand are reasonably proportioned, ball milling refinement and extrusion pugging are carried out by combining mechanical force, and the internal structure of the red mud pug for ceramic manufacture is optimized, so that the appearance of the red mud is dark red, the shrinkage rate is less than 20%, and the ceramic composite material has the characteristics of good plasticity, excellent compressibility, lower sintering temperature and the like.

The natural laterite is taken from Gobi desert of a Marat's back flag in an inner Mongolian autonomous region; the sand is at least one of river sand, sea sand and mountain sand which are naturally formed.

The natural laterite adopted in the invention has good cohesiveness, low melting point and high content of iron element, and the binding force among the natural laterite particles is high, so that the deformation rate and shrinkage rate of pugs and red mud blanks can be reduced during firing, and the rejection rate is reduced.

Further arranged that the weight ratio of the natural red soil to the sand is 1:0.8-1.1.

Further, the specific operation of the grinding and crushing treatment is as follows: mixing natural red soil and sand to obtain a mixture, then sending the mixture into a ball mill, adding water into the ball mill, and carrying out grinding and crushing treatment to obtain slurry.

In the invention, the mixture is ground and crushed by ball milling, the raw materials are thinned by mechanical force, and the structure, the structure and the performance of the raw materials can be possibly induced to change in the process. After ball milling, the grains of the raw materials are refined, the specific surface area is increased, the distribution uniformity of particles and the binding force among particles can be effectively improved, and the compactness and the mechanical property of mud materials and red mud products are improved in the pugging step and the firing process.

Further, the operation conditions of the grinding and crushing treatment are as follows: the rotating speed of the ball mill is 60-80r/min, and the grinding balls are high-aluminum balls with 92 percent of content.

The weight ratio of the materials in the ball mill is as follows: grinding ball, mixing material and water=1:1.0-1.3:0.8-1.1.

The slurry can be ground into different mesh sizes according to the production requirements, including but not limited to 20 mesh, 40 mesh, 60 mesh, 80 mesh, 120 mesh, … …, 300 mesh, etc. The red mud for ceramics preparation with different granularity can be obtained from mud with different meshes, and then the red mud for ceramics preparation with corresponding granularity is selected to be produced and fired into red mud products according to the requirements of specific products.

And further setting that in the step of pugging, when the pugging is repeated, after the first pugging is finished, the obtained pugging is kept stand for 10-24 hours, then the subsequent pugging is carried out, and the pugging does not need to be kept stand in the gap of the subsequent pugging. Preferably, the pugging repetition number is 3.

In the invention, after the first pugging is finished, the obtained pug is kept stand, so that the interior of the pug can be fused better. During the standing period, oxidation and other reactions can occur in the pug, so that the chemical state of the internal components of the pug after standing is more stable, the deformation rate and the shrinkage rate are reduced in the firing process, and the process performance of the red mud product is improved.

In a second aspect, the present invention provides a firing method for a red mud product, comprising:

1) According to production requirements, red mud for ceramic manufacture, which is prepared by the method, is selected, put into a model, and then pressed by a leather pressing machine to obtain a wet blank;

2) Airing the pressed wet blank in an airing room until the wet blank is thoroughly dried and no moisture on the surface is exuded, so as to obtain a dry blank;

3) And (3) sending the dried blank into an electric kiln, firing at a high temperature of 1100-1160 ℃, and cooling to room temperature to obtain the red mud product.

The firing method provided by the invention optimizes the technical performances of shrinkage, water absorption, color and the like of the red mud product to the greatest extent, so that the red mud product has high hardness, good strength, excellent fire resistance and heat insulation performance, higher thermal stability, easy cleaning when knocking metal impact sound, low heavy metal leaching amount, and high safety and reliability.

The high-temperature firing is further controlled by adopting a gradient heating control mode, and the specific operation is as follows: heating from normal temperature to 400 ℃, wherein the heating rate is 3-3.5 ℃/min; continuously heating to 750-780 ℃ at a heating rate of 3-3.5 ℃/min; continuously heating to 890-920 ℃ with the heating rate of 1.5-2 ℃/min; continuously heating to the firing temperature, wherein the heating rate is 2.5-3 ℃/min, and preserving heat for 30-60min.

According to the invention, the firing temperature is controlled by adopting a gradient heating mode, so that the shrinkage of the green body of the dry blank can be controlled more effectively, the fire-resistant temperature of the green body is improved, and the yield is improved, so that the red mud product with ideal size and high yield is obtained.

In the invention, the electric kiln is adopted for firing, which is different from the traditional firewood firing technology, and can solve the problems of difficult control of firewood firing temperature, high firing cost, difficult control of product quality, large pollution in the production process and the like, the temperature and the product quality of the electric kiln for firing are convenient for accurate control, the product is not influenced by flue gas, ash slag and the like, the rejection rate is relatively low, and the improvement of the yield and the production efficiency is facilitated.

The model is further provided with a model of daily ceramics and industrial ceramics, including tableware, drinking tools, face bricks, ceramic pots and flowerpots. In particular, the above-mentioned models include, but are not limited to, tableware or drinking vessel such as bowl, plate, dish, pot, cup, handleless cup, etc., face brick, pottery pot, flowerpot, etc.

Compared with the prior art, the preparation method of the red mud for preparing ceramics and the firing method of the red mud product provided by the invention have the following beneficial effects:

1) The invention has rich yield of raw natural red soil and sand, contains color-developing substances, and can lead the obtained red mud pug and red mud products to have stable color; the heavy metal content in the raw materials is little, the leaching amount is low, and the safety and the reliability are realized.

2) After the red mud product is fired, the inside and the outside do not need glazing and coloring, chemical pigment is not added, the red mud product is glazed, the harm to human bodies caused by harmful substances in the glaze is avoided, the problem of color spots caused by uneven pigment is also avoided, the inside and the outside of the red mud product are uniform in color, the appearance is smooth and bright, the texture is fine and smooth and warm, the surface is in a semi-vitrified state, and the red mud product is easy to clean after being used.

3) According to the invention, natural red soil and sand are used as raw materials, a novel preparation method of red mud is provided, the variety of red mud products is enriched, and the red mud products with excellent quality can be obtained by adopting an optimized firing process; the preparation method of the red mud is simple, the firing method of the red mud product is simple, convenient and feasible, the yield is high, the energy consumption is low, the environment is not polluted, the popularization is easy, the economic benefit and the social benefit are obvious, and the method has wide market prospect.

4) The preparation method and the firing method provided by the invention solve the problems of reduced natural red mud resources, large shrinkage and easy deformation of the natural red mud during firing, can expand the application range and the utilization value of the natural red mud, promote the sustainable development of the related industry of red mud products, and have wide application and popularization prospects and remarkable economic and social benefits.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions of the prior art, the following description will briefly explain the drawings used in the embodiments or the description of the prior art, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained according to these drawings without inventive effort for a person skilled in the art.

FIG. 1 is a schematic diagram showing the control mode of the gradient temperature rise when firing the red mud product at high temperature in example 5;

FIG. 2 shows the shrinkage measurement results of the test group samples in test example 1;

FIG. 3 shows the results of measuring flexural strength and retention of strength of each test group specimen before and after the thermal shock test in test example 2.

Detailed Description

For the purpose of making the objects, technical solutions and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below, and it is apparent that the described embodiments are some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are also within the scope of the invention.

In one embodiment of the invention, a method for preparing red mud for ceramics comprises the steps of:

1) Selecting raw materials: clean natural red soil and sand are respectively selected for standby, and the weight ratio of the natural red soil to the sand is 1:0.8-1.1.

The natural laterite is taken from Gobi desert of Marate's back flag in the inner Mongolian autonomous region. The sand is at least one of river sand, sea sand and mountain sand.

2) Grinding and crushing: mixing natural red soil and sand to obtain a mixture, then sending the mixture into a ball mill, adding water into the ball mill, and carrying out grinding and crushing treatment to obtain slurry.

The operating conditions of the above grinding and crushing treatment are as follows: the rotating speed of the ball mill is 60-80r/min, and the grinding balls are high-aluminum balls with 92 percent of content. The weight ratio of the materials in the ball mill is as follows: grinding ball, mixing material and water=1:1.0-1.3:0.8-1.1.

The slurry can be ground to various mesh sizes, including but not limited to 20 mesh, 40 mesh, 60 mesh, 80 mesh, 120 mesh, … …, 300 mesh, etc., depending on the production needs.

3) And (3) airing: and pouring the ground slurry on a drying rack for drying, and naturally drying until the obtained clay is not sticky.

4) Pugging: and (3) putting the clay obtained by airing into a pugging machine for pugging, and repeating pugging for 2-4 times to obtain the red mud for ceramic manufacture.

According to the invention, a pugging machine is used for pugging, and mechanical force is used for extrusion, so that air in pugs is thoroughly discharged, the pugs are more uniform in structure, and better in plasticity and compactness, the green body is convenient to form, the drying strength and the mechanical strength of the green body are improved, the labor cost is saved, and the production efficiency is improved.

In the step of pugging, when the repeated pugging is carried out, after the first pugging is finished, the obtained pugging is kept stand for 10-24 hours, then the subsequent pugging is carried out, and the pugging does not need to be kept stand in the gap of the subsequent pugging. Preferably, the pugging repetition number is 3.

According to the invention, after the green body prepared from the red mud pug obtained by mechanical pugging is fired, the porosity and the water absorption rate are lower than those of the green body prepared by manual pugging, the mechanical strength is higher, and the problem that the green body is unevenly contracted at each part due to uneven particles when the mud pug obtained by manual pugging is fired can be avoided, so that the forming rate of the red mud product is higher.

In order to optimize the performance of the red mud material and the red mud product, the further improved technical scheme improves the preparation method of the red mud for preparing ceramics, and the specific measures are as follows: in the grinding and crushing step, natural laterite and sand are mixed to obtain a mixture, the mixture is sent into a ball mill, 0.5-2wt% of sodium polyacrylate and 1-3wt% of polydimethylsiloxane are added into the mixture, and after uniform mixing, water is added into the ball mill for grinding and crushing treatment, so that slurry is obtained.

According to the improved technical scheme, sodium polyacrylate and polydimethylsiloxane are added into the mixture to serve as a gain agent, the sodium polyacrylate and the polydimethylsiloxane play a synergistic role, the sodium polyacrylate and the polydimethylsiloxane can be uniformly distributed in the red mud material under the action of mechanical force, the red mud material possibly has fluxing and reinforcing effects in the drying and high-temperature firing processes, the internal structure of a blank body is enabled to be more compact, the flexural strength of an obtained red mud product is also higher, the thermal shock stability and the thermal shock resistance of the red mud product can be improved, the cold and hot shock resistance of the red mud product is good, and the explosion condition is not easy to occur under the thermal shock effect. In addition, the connection and arrangement modes of particles in the red mud material are possibly influenced, and the stress effect in the red mud blank is reduced, so that the shrinkage and deformation rate of the red mud product in the drying and firing processes are reduced, and the yield and production efficiency of the red mud product are improved.

The present invention will be described in further detail with reference to examples.

Example 1:

the preparation method of the red mud for ceramic manufacture comprises the following steps:

1) Selecting raw materials: clean natural red soil and sand are respectively selected for standby, and the weight ratio of the natural red soil to the sand is 1:0.8. The natural laterite is taken from Gobi desert of Marate's back flag in the inner Mongolian autonomous region. The sand is natural sea sand and river sand, and the weight ratio is 1:1.

In this example, based on GB/T4734-1996, the chemical composition and content of the natural red soil are detected as follows: siO (SiO) ₂ 59.49, al ₂ O ₃ 16.05%, fe ₂ O ₃ 6.39% of TiO ₂ 0.88%, caO 2.87%, mgO 1.9%, K ₂ O is 2.3%, na ₂ O is 1.08 percent, and the ignition decrement is 8.67 percent.

2) Grinding and crushing: mixing natural red soil and sand to obtain a mixture, then sending the mixture into a ball mill, adding water into the ball mill, and then grinding and crushing at a rotating speed of 60r/min to obtain slurry. The grinding balls of the ball mill are high-alumina balls with 92 percent of content. The weight ratio of the materials in the ball mill is as follows: grinding ball, mixing material and water=1:1.0:0.8. The slurry was ground to 60 mesh.

4) Pugging: and (3) putting the clay obtained by airing into a pugging machine for pugging, and repeating pugging for 2 times to obtain the red mud for ceramic preparation. In the pugging step, when repeated pugging is carried out, after the first pugging is finished, the obtained pug is kept stand for 10 hours, and then secondary pugging is carried out.

Example 2:

a method for preparing red mud for ceramics, which differs from example 1 only in that:

step 1) selecting raw materials: the weight ratio of the natural red soil to the sand is 1:1.1. The sand is natural sea sand and mountain sand, and the weight ratio is 1:1.

Step 2) grinding and crushing: the rotating speed of the ball mill is 80r/min, and the weight ratio of materials in the ball mill is as follows: grinding ball, mixture and water=1:1.3:1.1.

Step 4) pugging: and (3) putting the clay obtained by airing into a pugging machine for pugging, and repeating for 4 times to obtain the red mud for ceramic manufacture. In the step of pugging, when the repeated pugging is carried out, after the first pugging is finished, the obtained pugging is kept stand for 24 hours, then the subsequent pugging is carried out for 3 times, and the pugging is not required to be kept stand in the gap between the subsequent pugging for 3 times.

Example 3:

step 1) selecting raw materials: the weight ratio of natural red soil to sand is 1:1. The sand is natural river sand and mountain sand, and the weight ratio is 1:1.

Step 2) grinding and crushing: the rotating speed of the ball mill is 70r/min, and the weight ratio of materials in the ball mill is as follows: grinding ball, mixing material and water=1:1:1.

Step 4) pugging: and (3) putting the clay obtained by airing into a pugging machine for pugging, and repeating for 3 times to obtain the red mud for ceramic manufacture. In the step of pugging, when the repeated pugging is carried out, after the first pugging is finished, the obtained pugging is kept stand for 16 hours, then the subsequent pugging is carried out for 2 times, the gap between the subsequent pugging for 2 times is reserved, and the pugging does not need to be kept stand.

Example 4:

a method for preparing red mud for ceramics, which differs from example 3 only in that:

step 2) grinding and crushing: mixing natural laterite and sand to obtain a mixture, then sending the mixture into a ball mill, adding 1wt% of sodium polyacrylate and 1.5wt% of polydimethylsiloxane into the mixture, uniformly mixing, adding water into the ball mill, and grinding and crushing at a rotating speed of 70r/min to obtain slurry. The weight ratio of the materials in the ball mill is as follows: grinding ball, mixing material and water=1:1:1. The slurry was ground to 60 mesh.

Example 5:

a method of firing a red mud product comprising the steps of:

1) Selecting red mud for ceramic manufacture, which is prepared in the embodiment 3, according to production requirements, putting the red mud into a model, and then pressing the red mud by a leather pressing machine to obtain a wet blank;

3) And (3) sending the dried blank into an electric kiln, firing at a high temperature of 1130 ℃, and cooling to room temperature to obtain the red mud product.

As shown in fig. 1, the high-temperature firing adopts a control mode of gradient heating, and the specific operation is as follows: heating from normal temperature to 400 ℃ at a heating rate of 3 ℃/min; continuously heating to 770 ℃, wherein the heating rate is 3.5 ℃/min; continuously heating to 900 ℃ with the heating rate of 1.5 ℃/min; continuously heating to the firing temperature, wherein the heating rate is 3 ℃/min, and preserving heat for 60min.

Example 6:

the firing method of red mud products differs from example 5 only in that:

in the step 1), red mud for ceramic manufacture prepared in the example 2 is selected;

in the step 3), the dried blank is sent into an electric kiln for high-temperature firing, the firing temperature is 1145 ℃, and then the red mud product is obtained after cooling to room temperature.

The high-temperature firing adopts a control mode of gradient temperature rise, and the specific operation is as follows: heating from normal temperature to 400 ℃ at a heating rate of 3.5 ℃/min; continuously heating to 780 ℃ at a heating rate of 3 ℃/min; continuously heating to 920 ℃, wherein the heating rate is 2 ℃/min; continuously heating to the firing temperature, wherein the heating rate is 2.5 ℃/min, and preserving the heat for 30min.

Example 7:

the firing method of red mud products differs from example 5 only in that:

in step 1), the red mud for ceramic manufacture prepared in example 4 was selected.

Comparative example 1:

step 2) grinding and crushing: mixing natural laterite and sand to obtain a mixture, then sending the mixture into a ball mill, adding 1wt% of sodium polyacrylate into the mixture, uniformly mixing, adding water into the ball mill, and grinding and crushing at a rotating speed of 70r/min to obtain slurry. The weight ratio of the materials in the ball mill is as follows: grinding ball, mixing material and water=1:1:1. The slurry was ground to 60 mesh.

Comparative example 2:

step 2) grinding and crushing: mixing natural laterite and sand to obtain a mixture, then sending the mixture into a ball mill, adding 1.5wt% of polydimethylsiloxane into the mixture, uniformly mixing, adding water into the ball mill, and grinding and crushing at a rotating speed of 70r/min to obtain slurry. The weight ratio of the materials in the ball mill is as follows: grinding ball, mixing material and water=1:1:1. The slurry was ground to 60 mesh.

Comparative example 3:

the firing method of red mud products differs from example 5 only in that:

in step 1), red mud for ceramic manufacture prepared in comparative example 1 is selected.

Comparative example 4:

the firing method of red mud products differs from example 5 only in that:

in step 1), red mud for ceramic manufacture prepared in comparative example 2 is selected.

Test example 1:

determination of physical Properties of Red mud and Red mud products

The experimental method comprises the following steps: firing of the pressed samples was performed according to the methods in example 5-example 7, comparative example 3 and comparative example 4, in which the pressed samples of each test group were each made into a sample of Φ50.00mm×4.00mm by the same mold. Each test group was set with 3 replicates and averaged. The results are shown in FIG. 2 and Table 1.

(1) Shrinkage test: drawing a 45mm straight line on the formed wet blank of the sample through the center of a circle, measuring the length of the straight line by a vernier caliper, and marking as L ₀ The method comprises the steps of carrying out a first treatment on the surface of the Drying the marked sample wet blank until the sample wet blank is dried thoroughly and the surface is free from moisture exudation to obtain a dry blank, measuring the linear length on the dry blank, and marking as L _Dry The method comprises the steps of carrying out a first treatment on the surface of the Then the dried blank is put into an electric kiln, high-temperature firing is carried out according to the gradient heating mode of each example and comparative example, after cooling, the straight line length is measured on a fired sample and is marked as L _{Burning out} . The shrinkage is calculated as follows: shrinkage on drying D _Dry ＝(L ₀ -L _Dry )/L ₀ 100% x, firing shrinkage D _{Burning out} ＝(L _Dry -L _{Burning out} )/L _Dry X 100%, total shrinkage D _{Total (S)} ＝(L ₀ -L _{Burning out} )/L ₀ ×100％。

The shrinkage measurements for each test group sample are shown in FIG. 2, where the shrinkage differences for example 5 and example 6 are not significant, where D for example 5 _Dry 5.56%, D _{Burning out} 7.53%, D _{Total (S)} 12.67%. Example 7D _Dry 4.44%, D _{Burning out} 6.04%, D _{Total (S)} The shrinkage was 10.22% and was significantly lower than in example 5. Comparative example 3D _Dry 5.44%, D _{Burning out} 7.05%, D _{Total (S)} 12.11%; d of comparative example 4 _Dry 5.33%, D _{Burning out} 6.50%, D _{Total (S)} 11.49%; the shrinkage of comparative example 3 and comparative example 4 varied to different extents than that of example 5, but the difference was not significant.

As can be seen from the shrinkage rates of comparative examples 5, 7, 3 and 4, the shrinkage rate of the pressed sample of example 7 is significantly reduced during the drying and firing processes, mainly because the red mud used in example 7 is prepared by the preparation method of example 4, and the gain agent added in the preparation method of example 4 plays a synergistic role, affects the connection and arrangement of particles in the red mud material, and reduces the stress effect inside the red mud blank, thereby reducing the shrinkage rate and deformation rate of the red mud product during the drying and firing processes and improving the yield and production efficiency of the red mud product.

(2) Water absorption test: taking the fired samples of each test group, cleaning the samples by an ultrasonic cleaner, drying the samples to constant weight at 110 ℃, then placing the samples in a dryer for cooling to room temperature, weighing the mass of the samples, and marking the mass as M ₁ The method comprises the steps of carrying out a first treatment on the surface of the Placing the sample into a container, placing the container in a vacuum drying oven, pumping vacuum for 5min, slowly injecting distilled water into the container until the sample is completely submerged, maintaining the vacuum pumping state for 15min, stopping vacuumizing, taking out the container, standing in air for 30min, taking out the sample, carefully wiping off sagging droplets on the surface of the sample by using a towel saturated with distilled water, and rapidly weighing the mass of the saturated sample in the air, wherein the mass is recorded as M ₂ . The water absorption is calculated by the following formula: w= (M ₂ -M ₁ )/M ₁ ×100％。

Table 1 results of measurement of water absorption of test group samples

	Example 5	Example 6	Example 7	Comparative example 3	Comparative example 4
						Water absorption percentage%	1.86	1.83	1.71	1.80	1.82

From the results, it is clear that the water absorption of the sample of example 7 is slightly lower than that of other samples, probably because the red mud of example 4 used in example 7 is added with the gain agent to exert a synergistic effect during preparation, and can be uniformly distributed in the red mud material under the action of mechanical force, and the red mud material may have fluxing and reinforcing effects during the drying and high-temperature firing processes, so that the internal structure of the green body is more compact, and the water absorption of the red mud product is reduced to some extent.

Test example 2:

determination of thermal shock resistance of red mud and red mud products

The experimental method comprises the following steps: firing of the samples was performed according to the methods in example 5, example 7, comparative example 3 and comparative example 4, in which the samples of each test group were each fabricated into 15mm×15mm×110mm samples by the same mold. After the firing of the sample, the flexural strength sigma of the sample was measured by a three-point load method according to GB/T4741-1999 ₁ . The thermal shock resistance of the sample is measured by adopting a quenching strength method, and the method specifically comprises the following steps: placing the sample into a resistance furnace with the temperature of 300 ℃ for 30min, rapidly taking out the sample, placing the sample into water with the temperature of 25 ℃ for quenching, taking out the sample, drying the sample at 100 ℃, placing the sample into the resistance furnace with the temperature of 300 ℃ for 30min, rapidly taking out the sample, placing the sample into water with the temperature of 25 ℃ for quenching, and then drying, preserving the heat and quenching the sample; after the sample is circulated for three times in this way, the flexural strength sigma of the sample after thermal shock is measured ₂ And calculating the intensity retention rate p of the sample, wherein the calculation formula is as follows: p=σ ₂ /σ ₁ X 100%. Each test group was set with 3 replicates and averaged. The results are shown in FIG. 3.

FIG. 3 shows the results of the flexural strength and strength retention measurements of the test group samples before and after the thermal shock test, the flexural strength differences between the samples of example 5, comparative example 3 and comparative example 4 before the thermal shock test were not significant, 62.4MPa, 63.2MPa and 62.6MPa, respectively, but were significantly lower than the flexural strength of 69.7MPa of example 7. After the thermal shock test, the flexural strength of each sample is reduced to different degrees, and the flexural strength and the strength retention rate of each sample are respectively as follows: 29.3MPa and 46.96% of example 5, 40.6MPa and 58.25% of example 7, 31.7MPa and 50.16% of comparative example 3 and 30.8MPa and 49.20% of comparative example 4.

Compared with the test sample of the embodiment 7, the breaking strength after firing is obviously higher than that of the embodiment 5, the strength retention rate after a thermal shock test is obviously higher than that of other test groups, the red mud used in the embodiment 7 is prepared by the preparation method of the embodiment 4, and the gain agent added in the preparation method of the embodiment 4 plays a synergistic role, can be uniformly distributed in the red mud material under the action of mechanical force, possibly has fluxing and reinforcing effects in the drying and high-temperature firing processes, can enable the internal structure of a green body to be more compact, can also enable the breaking strength of the obtained red mud product to be higher, can also improve the thermal shock stability and the thermal shock resistance of the red mud product, enable the cold and hot shock property of the red mud product to be good, is not easy to generate burst condition under the thermal shock effect, and prolongs the service life of the red mud product.

Finally, it should be noted that the above embodiments are merely illustrative of the technical solution of the present invention, and not limiting thereof; although the invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art will appreciate that; the technical scheme described in the foregoing embodiments can be modified or some or all of the technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit of the invention.

Claims

1. A method for preparing red mud for ceramic manufacture, comprising:

respectively selecting clean natural red soil and sand for later use;

mixing natural red soil and sand to obtain a mixture, then sending the mixture into a ball mill, adding water into the ball mill, and carrying out grinding and crushing treatment to obtain slurry;

airing the slurry to obtain clay; and, a step of, in the first embodiment,

putting the clay into a pugging machine for pugging, and repeating pugging for 3 times to obtain red mud for ceramic preparation;

the chemical composition and the content of the natural laterite are as follows: siO (SiO) ₂ 55-60% of Al ₂ O ₃ 15-18% of Fe ₂ O ₃ 6-8% of TiO ₂ 0.5-1.0%, caO 2-3%, mgO 1.0-2.5%, K ₂ O is 2-3%, na ₂ O is 1-1.5%, and ignition decrement is 8-9%;

the natural laterite is taken from Gobi desert of a Marat back flag of an inner Mongolian autonomous region; the sand is naturally formed river sand and mountain sand, and the weight ratio is 1:1;

the weight ratio of the natural red soil to the sand is 1:1;

in the step of pugging, when the repeated pugging is carried out, after the first pugging is finished, standing the obtained pugging for 10-24 hours, then carrying out subsequent pugging, and leaving the pugging in a gap without standing;

the operating conditions of the grinding and crushing treatment are as follows: the rotating speed of the ball mill is 70r/min, and the grinding balls are high-aluminum balls with 92 percent of content; the weight ratio of the materials in the ball mill is as follows: grinding ball, mixing material, water=1:1:1;

in the grinding and crushing treatment, 0.5-2wt% of sodium polyacrylate and 1-3wt% of polydimethylsiloxane are also added to the mixture.

2. The method of manufacturing according to claim 1, characterized in that: in the grinding and crushing treatment, 1wt% of sodium polyacrylate and 1.5wt% of polydimethylsiloxane were also added to the mixture.

3. A method of firing a red mud product, comprising:

1) Selecting red mud for ceramic manufacture, which is prepared by the method of claim 1 or 2, according to production requirements, putting the red mud into a model, and then pressing the red mud by a leather pressing machine to obtain a wet blank;

3) Sending the dried blank into an electric kiln, firing at a high temperature of 1100-1160 ℃, and cooling to room temperature to obtain a red mud product;

the high-temperature firing adopts a control mode of gradient heating, and the specific operation is as follows: heating from normal temperature to 400 ℃, wherein the heating rate is 3-3.5 ℃/min; continuously heating to 750-780 ℃ at a heating rate of 3-3.5 ℃/min; continuously heating to 890-920 ℃ with the heating rate of 1.5-2 ℃/min; continuously heating to the sintering temperature, wherein the heating rate is 2.5-3 ℃/min, and preserving heat for 30-60min.

4. A firing method according to claim 3, characterized in that: the model comprises a daily ceramic model and an industrial ceramic model, and comprises tableware, drinking tools, face bricks, ceramic pots and flowerpots.