Low-background radiation, high radiation shielding clinker powder and preparation method thereof

Abstract

The present application relates to the technical field of concrete clinker powder, and discloses a low-background radiation, high-radiation shielding clinker powder. A preparation method is also disclosed, comprising the following preparation steps: S1. Using iron ore, limestone and bauxite as raw materials, and using clean energy as fuel, high-iron phase clinker is prepared by calcining and heat preservation at 1100-1300 DEG C; S2. Using cement raw material as raw material and adding barite, low-calcium high-iron clinker rich in barium phase is prepared by calcining at 1420-1500 DEG C; S3. Preparing clinker powder finished product: the high-iron phase clinker in S1 and the low-calcium high-iron clinker rich in barium phase in S2 are mixed in proportion and then ball milled to obtain the clinker powder finished product. Through the sintering process control, the two kinds of clinker minerals prepared are mainly belite and iron phase solid solution, compared with the conventional Portland cement system, the mixing water amount required for complete hydration is greatly reduced, the concrete pore can be reduced, the overall density of the hardened concrete is greatly improved, and the radiation shielding effect is improved.

Description

Technical Field

[0001] This invention belongs to the field of concrete clinker powder technology, specifically, it relates to a low background radiation, high radiation shielding clinker powder and its preparation method. Background Technology

[0002] In the field of building materials, concrete, as an important structural material, is widely used in construction, infrastructure, and engineering projects. However, traditional concrete has some problems in certain applications, one of which is its high content of radioactive nuclides. These radioactive nuclides may come from naturally occurring radioactive elements in the concrete raw materials, or from the fuels used in the production process, especially when coal is used as fuel, which introduces a large amount of radioactive nuclides. Therefore, the presence of these radioactive nuclides can have a certain impact on the performance and safety of building materials.

[0003] Traditional concrete preparation processes have not been optimized for the issue of radioactive nuclides, making it difficult to control the content of radioactive nuclides in concrete and thus limiting the scope of use of concrete materials. In existing technologies, in order to improve the radiation shielding effect of concrete, barite or barite sand is usually added directly to the concrete to achieve protection against various types of radiation such as X-rays, gamma rays, and neutron rays, such as the radiation-shielding concrete based on barite disclosed in patent publication number CN112979247A.

[0004] However, while adding heavy crystals directly to concrete can improve its radiation shielding performance, it can also affect the concrete's brittleness, workability, and thickness, thereby impacting the flexibility of the building structure and the efficiency of construction.

[0005] In light of the above situation, how to ensure that concrete materials possess certain mechanical properties while significantly reducing the content of radioactive nuclides in them and improving the radiation shielding effect of concrete materials is an urgent problem to be solved. Summary of the Invention

[0006] This application aims to address the technical problems existing in the prior art, such as the presence of radioactive nuclides in concrete materials and the reduction in the mechanical properties of radiation-proof concrete.

[0007] Therefore, the first objective of this invention is to provide a method for preparing clinker powder with low background radiation and high radiation shielding properties.

[0008] Specifically, a method for preparing a clinker powder with low background radiation and high radiation shielding properties includes the following preparation steps:

[0009] S1 uses iron ore, limestone and bauxite as raw materials, clean energy as fuel, and calcination and heat preservation at 1100-1300℃ to produce high-iron phase clinker.

[0010] S2 uses cement raw materials as raw materials and adds barite, and calcines at 1420-1500℃ to produce barium-rich, low-calcium, high-iron clinker.

[0011] S3 Preparation of finished clinker powder: The high-iron phase clinker in S1 and the barium-rich low-calcium high-iron phase clinker in S2 are mixed in proportion and then ball-milled to obtain the finished clinker powder.

[0012] The technical mechanism is:

[0013] (1) By controlling the firing process, the two clinker minerals produced are mainly belite and iron phase solid solution. Compared with the conventional silicate cement system, the amount of mixing water required for complete hydration is greatly reduced, which can reduce concrete porosity and greatly improve the overall density of hardened concrete, thereby improving the radiation shielding effect. At the same time, under the same shielding effect, the concrete thickness is reduced but the mechanical properties of concrete can still be guaranteed, thereby improving the flexibility and efficiency of building structure.

[0014] (2) Among them, the calcination process control is mainly achieved by controlling the calcination temperature, thereby controlling the type of mineral crystal form, so as to produce clinker minerals mainly composed of belite and iron phase solid solution.

[0015] (3) The iron content is significantly increased while introducing barium into the clinker powder system, which further enhances the shielding effect against radiation compared with the calcium and silicon elements in the existing technology.

[0016] (4) By using clean energy fuels to replace traditional coal fuels, the enrichment of radionuclides in clinker can be effectively reduced, thereby reducing the radioactivity of the final product.

[0017] The second objective of this invention is to provide a clinker powder with low background radiation and high radiation shielding properties prepared by the aforementioned preparation method.

[0018] The beneficial effects of this application are as follows:

[0019] (1) By controlling the firing process, the two clinker minerals produced are mainly belite and iron phase solid solution. Compared with the conventional silicate cement system, the amount of mixing water required for complete hydration is greatly reduced, which can reduce concrete porosity and greatly improve the overall density of hardened concrete, thereby improving the radiation shielding effect. At the same time, under the same shielding effect, the concrete thickness is reduced but the mechanical properties of concrete can still be guaranteed, thereby improving the flexibility and efficiency of building structure.

[0020] (2) By introducing barium and significantly increasing the iron content, the shielding effect against radiation is further enhanced; at the same time, clean energy fuel is used in the calcination process to replace traditional coal fuel, which effectively reduces the enrichment of radioactive nuclides in clinker, thereby reducing the radioactivity of the final product. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0022] First, the present invention provides a method for preparing clinker powder with low background radiation and high radiation shielding properties, comprising the following preparation steps:

[0023] S1 uses iron ore, limestone and bauxite as raw materials, clean energy as fuel, and calcination and heat preservation at 1100-1300℃ to produce high-iron phase clinker.

[0024] S2 uses cement raw materials as raw materials and adds barite, and calcines at 1420-1500℃ to produce barium-rich, low-calcium, high-iron clinker.

[0025] S3 Preparation of finished clinker powder: The high-iron phase clinker in S1 and the barium-rich low-calcium high-iron phase clinker in S2 are mixed in proportion and then ball-milled to obtain the finished clinker powder.

[0026] In this invention, the calcination time of the high-iron phase clinker is 70-180 min, of which the heat preservation time is 20-60 min.

[0027] By maintaining the temperature for 20–60 minutes, the reaction is ensured to proceed fully, thereby reducing the content of free oxides such as free calcium oxide. This ensures the content of iron phase solid solution and dicalcium silicate mineral components in the clinker and the mechanical properties of the clinker powder after it is applied to concrete.

[0028] In this invention, the calcination time of the barium-rich, low-calcium, high-iron clinker is 60–120 min.

[0029] In this invention, the ratio of cement raw meal to barite by mass is 90-95:4-5.

[0030] In this invention, the mixing ratio of high-iron phase clinker and barium-rich low-calcium high-iron phase clinker by mass is 50-70:30-50.

[0031] In this invention, the clean energy source is at least one of hydrogen and natural gas.

[0032] In this invention, the Fe2O3 content in the high-ferrous phase clinker is 20-25% by mass percentage.

[0033] In this invention, the high-iron phase clinker contains the following mineral components by mass ratio: iron phase solid solution: dicalcium silicate in a ratio of 8-10: 0-2.

[0034] In this invention, the barium-rich, low-calcium, high-iron clinker comprises the following components by mass percentage: 0.5% ≤ BaO ≤ 3.0%, 5.0% ≤ Fe2O3 ≤ 7.0%, and 50% ≤ CaO ≤ 60%.

[0035] In this invention, the barium-rich, low-calcium, high-iron clinker contains the following mineral components by mass percentage: belite minerals ≥ 40%, iron phase solid solution ≥ 16%.

[0036] Second, the present invention provides a clinker powder with low background radiation and high radiation shielding properties prepared by the above preparation method.

[0037] <Example>

[0038] Example 1

[0039] (1) Preparation of high-iron phase clinker

[0040] Using iron ore (Fe2O3 content of 70%), limestone and bauxite as the main raw materials, and hydrogen as the clean energy fuel, the raw materials were calcined at 1250℃ for 2 hours and held at that temperature for 20 minutes to obtain high ferric clinker with Fe2O3 content of 25%.

[0041] Among them, the mineral components and their mass percentages in the high-iron phase clinker are: C4AF (tetracalcium aluminoferrite) 85%, C6A2F (hexacalcium ferroaluminate) 15%, and C2S (dicalcium silicate) 5%.

[0042] (2) Preparation of barium-rich, low-calcium, high-iron clinker

[0043] By mass percentage, 95% of cement raw materials are used as the main raw material, and 5% barite is added as an auxiliary component; natural gas is used as a clean energy fuel, and the mixture is calcined at 1450℃ for 1.5 hours to obtain barium-rich, low-calcium, high-iron clinker with BaO content of 2.2%, Fe2O3 content of 6.5%, and CaO content of 58%.

[0044] The mineral components and their mass percentages of the barium-rich, low-calcium, high-iron clinker are as follows: 44% berite, 20% C4AF, 18% C6A2F, and no C3A (tricalcium aluminate).

[0045] (3) Mixing and grinding

[0046] The high-iron phase clinker obtained in step (1) and the barium-rich low-calcium high-iron phase clinker obtained in step (2) are mixed at a mass ratio of 60:40. The two clinkers are fully mixed by ball milling to obtain clinker powder with low background radiation and high shielding.

[0047] Example 2

[0048] The difference between this embodiment and embodiment 1 is that in step (1), iron ore with an Fe2O3 content of 80% is used as raw material, and the raw material is calcined at 1300℃ for 1.5 hours and kept warm for 20 minutes to obtain high ferrous clinker with an Fe2O3 content of 22%.

[0049] In step (2), 3% barite is added as an auxiliary component and calcined at 1500℃ for 1 hour to obtain a barium-rich, low-calcium, high-iron clinker with BaO content of 1.5%, Fe2O3 content of 5.5%, and CaO content of 53%.

[0050] In step (3), the high-iron phase clinker and the barium-rich low-calcium high-iron phase clinker are mixed at a mass ratio of 70:30;

[0051] Among them, the mineral components and their mass percentages in the high-iron phase clinker are: C4AF (tetracalcium aluminoferrite) 95%, C6A2F (hexacalcium ferroaluminate) 5%, and no C2S (dicalcium silicate).

[0052] The mineral components and their mass percentages of the barium-rich, low-calcium, high-iron clinker are as follows: 40% berite minerals, 18% C4AF, 20% C6A2F, and no C3A.

[0053] Example 3

[0054] The difference between this embodiment and embodiment 1 is that in step (1), iron ore with a Fe2O3 content of 75% is used as raw material, and the raw material is calcined at 1280℃ for 1.8 hours and kept warm for 30 minutes to obtain high iron phase clinker with a Fe2O3 content of 20%.

[0055] In step (2), 4% barite was added as an auxiliary component and calcined at 1420℃ for 1.2 hours to obtain a barium-rich, low-calcium, high-iron clinker with BaO content of 0.5%, Fe2O3 content of 6.2%, and CaO content of 56%.

[0056] In step (3), the high-iron phase clinker and the barium-rich low-calcium high-iron phase clinker are mixed at a mass ratio of 65:35.

[0057] Among them, the mineral components and their mass percentages in the high-iron phase clinker are: C4AF (tetracalcium aluminoferrite) 88%, C6A2F (hexacalcium ferroaluminate) 12%, and C2S (dicalcium silicate) 2%.

[0058] The mineral components and their mass percentages of the barium-rich, low-calcium, high-iron clinker are as follows: 42% berite minerals, 19% C4AF, 17% C6A2F, and no C3A.

[0059] Example 4

[0060] The difference between this embodiment and embodiment 1 is that in step (1), iron ore with a Fe2O3 content of 85% is used as raw material, calcined at 1320℃ for 1.2 hours and kept warm for 40 minutes to obtain high iron phase clinker with a Fe2O3 content of 23%.

[0061] In step (2), 2% barite was added as an auxiliary component and calcined at 1480℃ for 1.8 hours to obtain a barium-rich, low-calcium, high-iron clinker with BaO content of 2.5%, Fe2O3 content of 5.8%, and CaO content of 54%.

[0062] In step (3), the high-iron phase clinker and the barium-rich low-calcium high-iron phase clinker are mixed at a mass ratio of 75:25.

[0063] Among them, the mineral components and their mass percentages in the high-iron phase clinker are: C4AF (tetracalcium aluminoferrite) 92%, C6A2F (hexacalcium ferroaluminate) 8%, and C2S (dicalcium silicate) 3%.

[0064] The mineral components and their mass percentages of the barium-rich, low-calcium, high-iron clinker are as follows: 45% berite minerals, 17% C4AF, 19% C6A2F, and no C3A.

[0065] <Comparative Example>

[0066] Comparative Example 1

[0067] The difference between this comparative example and Example 1 is that coal is used instead of hydrogen or natural gas as fuel.

[0068] Comparative Example 2

[0069] The difference between this comparative example and Example 1 is that barite is not used in step (2).

[0070] Comparative Example 3

[0071] The difference between this comparative example and Example 1 is that high-temperature insulation was not performed in step (1).

[0072] Comparative Example 4

[0073] The difference between this comparative example and Example 1 is that the cement raw materials in step (2) are prepared according to a high Al2O3 / FeO3 ratio.

[0074] <Experimental Example>

[0075] Experimental Example 1

[0076] Using Examples 1-4 and Comparative Examples 1-3 as samples, the radioactivity ratio (bq / kg) of the samples was determined according to GB / T 11713-2015 "General Method for γ-ray Spectroscopy Analysis of High Purity Germanium". The experimental results are shown in Table 1.

[0077] Table 1

[0078]

[0079] Experimental Example 2

[0080] The clinker powder provided in Examples 1-4 and Comparative Examples 1-3 was applied to concrete, and concrete test samples were prepared. Under the premise that each concrete test sample maintained the same radiation shielding effect, the thickness of the concrete layer was tested. Finally, it was compared with concrete prepared by conventional P·O42.5 cement. The comparison results are shown in the table below.

[0081] Table 2

[0082]

[0083] As shown in Tables 1 and 2, the clinker powder prepared in Examples 1-4 has a low radioactivity ratio and high shielding performance, thereby reducing the radioactivity of concrete and improving its shielding performance from a material perspective. Among these factors, the selection of raw materials, high-temperature insulation, fuel selection, and the amount of barite all have a significant impact on the radioactivity, shielding performance, and mechanical properties of the clinker powder. Meanwhile, under the premise that all concrete test samples maintain the same radiation shielding effect, the thickness of the concrete layer was tested. The present invention has a lower thickness while ensuring the same mechanical properties.

[0084] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing clinker powder with low background radiation and high radiation shielding properties, characterized in that, The preparation steps include the following: S1 uses iron ore, limestone and bauxite as raw materials, clean energy as fuel, and calcination and heat preservation at 1100~1300℃ to produce high-iron phase clinker. S2 uses cement raw materials as raw materials and adds barite, and calcines at 1420~1500℃ to produce barium-rich, low-calcium, high-iron clinker. S3 Preparation of finished clinker powder: The high-iron phase clinker in S1 and the barium-rich low-calcium high-iron phase clinker in S2 are mixed in proportion and then ball-milled to obtain finished clinker powder. In step S1, the calcination time of the high-iron phase clinker is 70~180min, of which the heat preservation time is 20~60min; In step S2, the calcination time of the barium-rich, low-calcium, high-iron clinker is 60-120 minutes.

2. The method for preparing low background radiation and high radiation shielding clinker powder according to claim 1, characterized in that, In step S2, the ratio of cement raw material to barite by mass is 90~95:4~5.

3. The method for preparing low background radiation and high radiation shielding clinker powder according to claim 1, characterized in that, In step S3, the mixing ratio of high-iron phase clinker and barium-rich low-calcium high-iron clinker by mass is 50~70:30~50.

4. The method for preparing low background radiation and high radiation shielding clinker powder according to claim 1, characterized in that, The Fe2O3 content in the high-ferrous phase clinker is 20-25% by mass percentage.

5. The method for preparing low background radiation and high radiation shielding clinker powder according to claim 1, characterized in that, By mass percentage, the high-iron phase clinker contains the following mineral components: 8-10% iron phase solid solution and 0-2% dicalcium silicate.

6. The method for preparing low background radiation and high radiation shielding clinker powder according to claim 1, characterized in that, By mass percentage, the barium-rich low-calcium high-iron clinker contains the following components: 0.5%≤BaO≤3.0%, 5.0%≤Fe2O3≤7.0%, and 50%≤CaO≤60%.

7. The method for preparing low-background-radiation, high-radiation-shielding clinker powder according to claim 1, characterized in that, By mass percentage, the barium-rich, low-calcium, high-iron clinker contains the following mineral components: belite minerals ≥ 40%, iron phase solid solution ≥ 16%.

8. A clinker powder prepared by any one of claims 1 to 7.

Images