CN111847916B - Mixed material suitable for white portland cement and preparation method thereof - Google Patents

Abstract

The invention belongs to the technical field of new materials, and particularly relates to a mixed material suitable for white portland cement and a preparation method thereof, wherein the mixed material suitable for the white portland cement comprises 90% -95% of ceramic micro powder, 2% -4% of silica sol powder and 3% -6% of calcium hydroxide. The invention provides a mixed material which can effectively reduce the production cost of products, improve the whiteness of the products, and improve the strength and the workability of the products and is suitable for white portland cement and a preparation method thereof.

Description

Mixed material suitable for white portland cement and preparation method thereof

Technical Field

The invention belongs to the technical field of new materials, and particularly relates to a mixed material suitable for white portland cement and a preparation method thereof.

Background

The prior art and the defects are as follows:

the white Portland cement is a hydraulic cementing material prepared by finely grinding Portland cement clinker with low content of ferric oxide, a proper amount of gypsum and a mixed material meeting the specification of GB/T2015-2005 white Portland cement. The white Portland cement is characterized by having higher whiteness, and is generally used as various building decoration materials, so compared with the common Portland cement, the whiteness is an important index for evaluating the quality of the white Portland cement besides conventional detection items (such as strength, stability, harmful components and the like) for product performance.

The white portland cement industry in China is developed later, compared with foreign products, the white portland cement has overall quality deviation, and in recent years, the white portland cement market has two vigorous trends of low-quality product surplus and high-quality product production and sale. Therefore, how to improve the whiteness of the product becomes a hot spot in the development of the industry. The factors influencing the whiteness of the white portland cement mainly comprise: the content of non-ferrous metal oxide in the raw materials, the selection and dosage of mineralizer, the KH value of raw material ingredients, the cooling system of clinker, the selection of mixed materials and the influence of grinding fineness, etc. Generally speaking, the quality of raw materials, raw ingredients and clinker cooling directly affect the whiteness of white portland cement clinker. But the raw materials are limited by objective natural conditions and are difficult to improve; the high KH of the raw material ingredients can improve the whiteness, but can cause high coal consumption of raw material firing, thereby obviously improving the production cost; the clinker quenching process results in low heat recovery efficiency, and indirectly causes the increase of production cost. In conclusion, the method for improving the whiteness of the white portland cement clinker has great difficulty in improving the whiteness of the cement product.

The cement product is composed of cement clinker and mixed materials, the main mixed material used in the white portland cement production industry at the present stage is finely ground limestone powder, and the finely ground limestone powder is generally obtained by purchasing a finished limestone powder product or automatically grinding limestone. The purchased limestone powder has high cost and easily causes large water demand and poor workability of cement products; the self-grinding limestone powder is difficult to ensure whiteness due to the quality and grinding fineness of limestone on one hand, and needs to bear equipment cost and power consumption cost on the other hand.

In summary, the problems of the prior art are as follows:

firstly, the method comprises the following steps: the white portland cement product has low whiteness, and does not meet the market demand;

secondly, the method comprises the following steps: the difficulty and the cost for improving the whiteness of the clinker by raw material proportioning or a burning cooling technology are high;

thirdly, the method comprises the following steps: at the present stage, limestone powder is used as a mixed material, so that the quality of the mixed material is defective, and the purchase cost and the equipment cost are high.

The difficulty and significance for solving the technical problems are as follows:

therefore, based on the problems, the mixed material suitable for the white Portland cement and the preparation method thereof, which can effectively reduce the production cost of the product, improve the whiteness of the product and improve the strength and the workability of the product, have important practical significance.

Disclosure of Invention

The invention aims to solve the technical problems in the prior art and provide a mixed material which can effectively reduce the production cost of products, improve the whiteness of the products and improve the strength and the workability of the products and is suitable for white portland cement and a preparation method thereof.

The technical scheme adopted by the invention for solving the technical problems in the prior art is as follows:

the mixed material suitable for the white portland cement comprises 90-95% of ceramic micro powder, 2-4% of silica sol powder and 3-6% of calcium hydroxide in percentage by mass.

The invention can also adopt the following technical scheme:

in the above-mentioned applicationsThe ceramic micro powder is used in the mixed material of white Portland cement, and further comprises the main components of silicon oxide and aluminum oxide, the particle size is 1-5 mu m, and the specific surface area exceeds 6000cm²(g), the particle size distribution is uniform.

The raw materials are processed by an iron removal process in the preparation process, and the whiteness is superior to that of the fine millstone limestone powder produced by a cement plant. Although the fineness is extremely fine, the surface is vitrified through high-temperature sintering in the production process, the water demand is low, the agglomeration effect is weak, the alkali excitation activity is high, the gel is formed by the reaction of the alkali generated by hydration of cement, the strength of the product is improved, and the ceramic micro powder particles which are not excited play a gap filling role and are also helpful for the strength.

A preparation process of a mixed material suitable for white portland cement comprises the following steps of: mixing 90-95% of ceramic micropowder, 2-4% of silica sol powder and 3-6% of calcium hydroxide.

The silica sol powder and the calcium hydroxide are both powder with extremely high whiteness, and on the premise of not influencing the whiteness of the product, the silica sol can react with the cement hydrate C-S-H gel to generate new gel to bond a small amount of unexcited ceramic micro powder, and the calcium hydroxide supplements alkali in a system, thereby being beneficial to exciting a mixed material.

A process for the preparation of a white portland cement product, comprising the steps of:

the method comprises the following steps: mixing 90-95% of ceramic micro powder, 2-4% of silica sol powder and 3-6% of calcium hydroxide;

step two: directly adding the mixture into a finished product of the cement mill through a conveying chute without a grinding process.

In conclusion, the invention has the following advantages and positive effects:

1. the characteristic of low water demand of vitrified surface of ceramic micropowder improves the defect of large water demand and poor workability of the product using limestone powder as a mixed material. Meanwhile, the characteristics of strong alkali excitability and strong particle gap filling effect can obviously improve the strength of the product.

2. The whiteness of the ceramic micro powder is superior to that of the ground limestone powder produced by cement plants, and the whiteness of the product is improved.

3. For the production line of purchased fine ground limestone powder, the cost of the ceramic micro powder is lower than that of the fine ground limestone powder, and the strength and the workability of the prepared product are superior to those of the fine ground limestone powder; for a production line for preparing limestone powder by self-grinding, the cost difference between the ceramic micro powder and limestone powder materials is not large, but the comprehensive cost of the ceramic micro powder is better in consideration of the power consumption and equipment cost of limestone grinding, and the ceramic micro powder is far better than self-grinding limestone powder in the aspects of whiteness and other properties.

4. The ceramic micro powder is used as a white silicate cement mixed material, so that the production process flow can be simplified: the pre-homogenizing equipment for the raw limestone powder and the conveyer belt before grinding can be omitted, and the ceramic micro powder can be directly mixed with the cement grinding material through the conveyer chute to form a product.

5. The mixed material of the invention can replace limestone powder and other common mixed materials of white portland cement, and the quality performance, the production cost and the simplified flow of the cement product are improved at three angles (the cost reduction means that the power consumption in the grinding process of high-price fine grinding limestone can be reduced, the simplified flow means that the grinding and blending process of the original limestone powder or other mixed materials is saved, but the clinker grinding process is still remained). The mixed material improves the effects of whiteness and process performance (including strength, workability and the like) of the white portland cement product, improves the effects of strength and workability of the product, and improves the value of the product; meanwhile, the power consumption of grinding is reduced, the process flow is simplified, and the production cost is reduced. For a production line for automatically grinding limestone powder as a mixed material, the ceramic micro powder is used as the mixed material, so that the production process flow can be simplified, and the equipment cost can be reduced.

Drawings

The technical solutions of the present invention will be described in further detail below with reference to the accompanying drawings and examples, but it should be understood that these drawings are designed for illustrative purposes only and thus do not limit the scope of the present invention. Furthermore, unless otherwise indicated, the drawings are intended to be illustrative of the structural configurations described herein and are not necessarily drawn to scale.

FIG. 1, FIG. 2 and FIG. 3 are scanning electron micrographs of ceramic micropowder provided in an embodiment of the present invention;

FIG. 4 shows the analysis of the components of the ceramic fine powder according to the embodiment of the present invention.

Detailed Description

Under the national environment promoting energy conservation and emission reduction sustainable development, the white portland cement industry is in the development period of pursuing high quality, and the original production process and flow need to be upgraded in all directions and in multiple angles. The method is a new direction for industry development by optimally preparing high-performance and high-whiteness products through the mixed materials and considering energy conservation and consumption reduction.

The main component of the mixed material is ceramic micro powder, a small amount of silica sol powder and calcium hydroxide are used for ensuring the working performance, the ceramic micro powder, the silica sol powder and the calcium hydroxide are prepared into a high-fineness high-whiteness mixed material according to a certain proportion, and the high-fineness high-whiteness mixed material is added into ground white portland cement clinker in a complex doping mode to prepare a high-quality white portland cement product.

The specific working principle is as follows: the prepared ceramic micro powder mixed material is used for replacing the conventional limestone powder mixed material, so that the product performance of the white Portland cement is improved. Compared with common limestone powder, the ceramic micro powder has the characteristics of higher whiteness, small particle size gap filling effect and high alkali excitation activity, can improve the strength of a cement product, and ensures the workability of the cement product due to low water demand. The auxiliary material silica sol is easy to dissolve in water, the reaction with hydration products C-S-H gel in the cement hydration process is beneficial to cementing ceramic micro powder particles which are not excited by alkali, and calcium hydroxide is used as an alkali supplement component in a system to promote the activation of the activity of the ceramic micro powder particles. The original grinding process can be omitted due to the high fineness of the ceramic micro powder mixed material, and the cement product is prepared by directly utilizing the white portland cement clinker which is transported and finely ground by the conveying chute and by a complex mixing method.

In order to further understand the contents, features and effects of the present invention, the following embodiments are illustrated and described in detail with reference to the accompanying drawings:

the attached fig. 1-3 in the specification are electron micrographs and composition analysis of ceramic fine powder, which is applied to all the examples.

Example 1: a preparation method of a mixed material suitable for white portland cement comprises the following steps:

the method comprises the following steps: selecting ceramic micro powder, silica sol powder and calcium hydroxide as a mixed material, and weighing 90% of the ceramic micro powder, 4% of the silica sol powder and 6% of the calcium hydroxide according to the weight ratio;

step two: uniformly mixing the materials of the components in the step one by using a mixer to obtain a mixed material;

step three: taking white Portland cement clinker and desulfurized gypsum as clinker components, and weighing the white Portland cement clinker and the desulfurized gypsum according to the weight ratio of 95% to 5%;

step four: grinding the clinker components in the third step for 30min by using an experimental mill, and sieving by using a 200-mesh sieve to obtain a finished clinker product;

step five: and weighing the mixed material obtained in the step two and the clinker finished product obtained in the step four according to the weight ratio of 1:9, and uniformly mixing by using a mixer to obtain a white portland cement finished product.

Example 2: a method for preparing a mixed material suitable for white portland cement, which is the same as example 1 except that: the mixture ratio is: the ceramic powder was weighed in a weight ratio of 93% ceramic powder, 3% silica sol powder and 4% calcium hydroxide.

Example 3: a method for preparing a mixed material suitable for white portland cement, which is the same as example 1 except that: the mixture ratio is: the ceramic powder is weighed according to the weight ratio of 95 percent of ceramic powder, 2 percent of silica sol powder and 3 percent of calcium hydroxide.

Comparative example 1: the preparation method of the white Portland cement (without the admixture) comprises the following steps:

the method comprises the following steps: weighing white Portland cement clinker and desulfurized gypsum according to the weight ratio of 95 percent of white Portland cement clinker to 5 percent of desulfurized gypsum;

step two: grinding the clinker components in the step one for 30min by using an experimental mill, and sieving by using a 200-mesh sieve to obtain a white portland cement (without a mixed material) finished product;

comparative example 2: the preparation method of white portland cement (limestone powder as mixed material) comprises the following steps:

the method comprises the following steps: weighing white portland cement clinker, desulfurized gypsum and limestone powder according to the weight ratio of 95% of the white portland cement clinker and 5% of the desulfurized gypsum to serve as the white portland cement clinker, and weighing the limestone powder and the white portland cement clinker according to the weight ratio of 1: 9;

step two: and (3) grinding the limestone powder and white portland cement clinker ingredients in the step one for 30min by using an experimental mill, and sieving by using a 200-mesh sieve to obtain a white portland cement (the mixed material is the limestone powder) finished product.

The white Portland cement finished products obtained in the examples 1-3 and the comparative examples 1 and 2 are subjected to sealing and drying treatment to obtain experimental samples, wherein the whiteness of the samples is determined according to the determination method specified in GB/T5950-. The measurement results are shown in table 1:

table 1 comparison of whiteness to strength data for each group

It can be seen that the whiteness of the examples 1-3 is better than that of the comparative examples 1 and 2, and the national standard requirements are met, which shows that the ceramic micro powder mixed material can effectively improve the whiteness of the white portland cement. Comparing the strength data of the examples shows that the comparative example 1 is superior to other examples in strength because of high clinker content (no mixed material), compared with the comparative example 2, the compressive strength of 3d and 28d curing ages is higher than that of the comparative example 2 in the examples 1-3, which shows that compared with limestone powder, the ceramic micro powder mixed material has a greater contribution to the strength of cement products, and the compressive strength of the examples 1-3 is not much different from that of the comparative example 1 when reaching 28d along with the extension of the curing ages, because a large amount of alkali is generated along with the progress of cement hydration, the alkali excitation activity of the ceramic micro powder is high, new gel formed after excitation improves the compactness of the system, and macroscopically reflects the strength as the strength is improved. The 28d flexural strength data of examples 1-3 are even better than comparative example 1 for the reason that it can be understood that: for the flexural strength, in addition to the gel generation amount of the system, the stacking compactness degree of the particles of the system also obviously influences the flexural strength, and the ceramic micro powder mixed material has the advantages of small particle size and strong gap filling effect, can optimize the stacking compactness of the particles of the system, and is macroscopically embodied as high flexural strength. According to theoretical analysis, more ceramic micro powder mixed material and alkali reaction activity is activated along with further increase of curing time, and the compressive and flexural strength of examples 1-3 can continue to increase and possibly even exceed that of comparative example 1 of the full clinker.

The mixed material suitable for the white portland cement can obviously improve the whiteness and the technological performance of the white portland cement.

In conclusion, the invention can provide the mixed material which can effectively reduce the production cost of the product, improve the whiteness of the product, and improve the strength and the workability of the product and is suitable for the white Portland cement and the preparation method thereof.

The present invention has been described in detail with reference to the above examples, but the description is only for the preferred examples of the present invention and should not be construed as limiting the scope of the present invention. All equivalent changes and modifications made within the scope of the present invention shall fall within the scope of the present invention.

Claims (3)

1. The admixture suitable for white portland cement is characterized in that: the mixed material suitable for the white portland cement comprises 90-95% of ceramic micro powder, 2-4% of silica sol powder and 3-6% of calcium hydroxide in mass ratio, wherein the ceramic micro powder mainly comprises silicon oxide and aluminum oxide, the granularity is 1-5 mu m, and the specific surface area exceeds 6000cm²And the particle size distribution is uniform, and the iron removal process flow is adopted in the raw material preparation process.

2. A preparation process of a mixed material suitable for white portland cement is characterized by comprising the following steps of: the process for producing a mixed material for white portland cement according to claim 1, which comprises the steps of: mixing 90-95% of ceramic micropowder, 2-4% of silica sol powder and 3-6% of calcium hydroxide.

3. A preparation process of a white portland cement product is characterized by comprising the following steps: the preparation process of the white portland cement product adopts the mixed material suitable for the white portland cement as described in claim 1, and comprises the following steps:

the method comprises the following steps: mixing 90-95% of ceramic micro powder, 2-4% of silica sol powder and 3-6% of calcium hydroxide;

step two: directly adding the mixture into a finished product of the cement mill through a conveying chute without a grinding process.

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