Carbon Dioxide Reaction Hardening Cement Clinker Using Paper Sludge And Sewage Waste And Carbon Dioxide Reaction Hardening Cement Manufactured Using The Same

Abstract

The present invention relates to a carbon dioxide reaction-hardened cement clinker using paper mill sludge and sewage waste, and a carbon dioxide reaction-hardened cement produced using the same. The present invention has the effect of providing a clinker capable of manufacturing carbon dioxide reaction hardening cement by mixing discarded paper mill sludge and sewage waste in an optimal ratio and calcining it, thereby efficiently synthesizing Pseudo-Wollastonite and Rankinite, which are the major mineral phases of carbon dioxide reaction hardening cement, without causing limestone fragmentation or melting.

Description

Technology Field

[0001] The present invention relates to a carbon dioxide reaction-hardened cement clinker using paper mill sludge and sewage waste, and a carbon dioxide reaction-hardened cement produced using the same. Background Technology

[0003] As interest in carbon-neutral technologies increases to address climate change, countries around the world are establishing roadmaps by officially declaring annual carbon emission targets or through documentation and legislation. The cement industry is the third largest emitter of carbon dioxide, after the steel and petrochemical industries. Carbon capture, utilization, and storage (CCS) technologies are being developed as an efficient carbon neutrality measure for the cement industry. Among these technologies, mineral carbonation is a representative example. Carbon dioxide reaction-hardened cement produced through this technology fixes carbon dioxide in a stable inorganic mineral phase, allowing for effective capture and stable storage without the risk of leakage. Furthermore, since cement produced through this mineral carbonation process can be manufactured into blocks, tiles, panels, or off-set construction (OSC) products, it offers the advantage of being usable as a construction material that replaces conventional cement. The main mineral phases of this carbon dioxide reaction-hardened cement are Pseudo-Wollastonite and Rankinite, and their primary raw materials are calcium carbonate and silicon oxide. The synthesis of the aforementioned major mineral phases can be degraded by impurities such as metal oxides and alkali components, and if limestone fragmentation or melting occurs during the calcination process of the clinker, there is a problem in that the quality of the cement produced by grinding the clinker deteriorates.

[0004] Paper sludge is a byproduct generated during the paper manufacturing process that is difficult to recycle due to its high calcium content as well as high levels of alkaline components. Similarly, sewage waste contains high silicon oxide content and large amounts of metal oxides and alkaline components, so there is currently no suitable recycling method other than discharging it into rivers after purification.

[0005] The patent documents and references mentioned in this specification are incorporated by reference into this specification to the same extent that each document is individually and clearly identified by reference. Prior art literature

[0007] Korean Patent Application 10-2020-0187959 The problem to be solved

[0008] The present invention relates to a carbon dioxide reaction-hardened cement clinker using paper mill sludge and sewage waste, and a carbon dioxide reaction-hardened cement produced using the same.

[0009] The objective of the present invention is to provide a clinker suitable for the manufacture of carbon dioxide reaction hardening cement by mixing discarded paper mill sludge and sewage waste in an optimal ratio and calcining it, thereby efficiently generating Pseudo-Wollastonite and Rankinite, which are the major mineral phases of carbon dioxide reaction hardening cement, without causing limestone fragmentation or melting.

[0010] Another objective of the present invention is to provide a carbon dioxide reaction hardening cement with excellent workability and excellent reactivity, which facilitates the penetration of carbon dioxide, by grinding the carbon dioxide reaction hardening cement clinker prepared above to an optimal fineness.

[0011] Other objects and technical features of the present invention are more specifically presented by the following detailed description of the invention, claims, and drawings. means of solving the problem

[0013] The present invention provides a carbon dioxide reaction-hardened cement clinker comprising paper sludge and sewage waste.

[0014] The above paper sludge is characterized by having a calcium oxide (CaO) content of 82 to 90 Mass %, a silicon oxide (SiO2) content of 1.5 to 3 Mass %, and a sodium oxide (Na2O) content of 5 to 6 Mass %; the above sewage waste is characterized by having a silicon oxide (SiO2) content of 89 to 94 Mass %, an aluminum oxide (Al2O3) content of 1.5 to 2.5 Mass %, and a calcium oxide (CaO) content of 0.5 to 1.5 Mass %.

[0015] The carbon dioxide reaction-hardened cement clinker containing the above paper sludge and sewage waste is characterized by having a calcium (Ca) and silicon (Si) content ratio (S / (C+S, where C represents the calcium content and S represents the silicon content) of 0.355 to 0.38.

[0016] The carbon dioxide reaction-hardened cement clinker containing the paper sludge and sewage waste is characterized by being manufactured by a method comprising: a first step of manufacturing a molded body using a composition for manufacturing carbon dioxide reaction-hardened cement clinker containing the paper sludge and sewage waste; a second step of first heating the molded body from room temperature to 280 to 320°C for 50 to 70 minutes at a heating rate of 5°C / min; a third step of secondarily heating the first heated molded body from 280 to 320°C to 1150 to 1350°C for 95 to 100 minutes at a heating rate of 10°C / min; and a fourth step of maintaining the secondarily heated molded body at 1150 to 1350°C for 100 to 140 minutes to manufacture the carbon dioxide reaction-hardened cement clinker.

[0017] The present invention provides a carbon dioxide reaction hardening cement containing paper sludge and sewage waste, manufactured using a carbon dioxide reaction hardening cement clinker containing paper sludge and sewage waste.

[0018] The carbon dioxide reaction-hardened cement containing the above paper mill sludge and sewage waste comprises a carbon dioxide reaction-hardened cement clinker containing the above paper mill sludge and sewage waste with a fineness of 4300 to 4700 cm 2 It is characterized by being manufactured by grinding into / g. Effects of the invention

[0020] The present invention relates to a carbon dioxide reaction-hardened cement clinker using paper mill sludge and sewage waste, and a carbon dioxide reaction-hardened cement produced using the same.

[0021] The present invention has the effect of providing a clinker capable of manufacturing carbon dioxide reaction hardening cement by mixing discarded paper mill sludge and sewage waste in an optimal ratio and calcining it, thereby efficiently synthesizing Pseudo-Wollastonite and Rankinite, which are the major mineral phases of carbon dioxide reaction hardening cement, without causing limestone fragmentation or melting. Specific details for implementing the invention

[0023] The present invention relates to a carbon dioxide reaction-hardened cement clinker containing paper mill sludge and sewage waste, and cement produced using the same. The present invention will be described in detail below through examples.

[0025] Examples

[0027] 1. Analysis of Raw Materials for Manufacturing Carbon Dioxide Reaction-Hardened Cement Clinker

[0028] The present invention relates to a carbon dioxide reaction-hardened cement clinker using waste limestone, paper industry byproducts, and sewage waste. The main minerals of the carbon dioxide reaction-hardened cement clinker of the present invention are wollastonite (CaSiO3) and rankinite (Ca3Si2O7). In the present invention, waste limestone and sludge generated from the paper industry (paper sludge) were used as raw materials for calcium oxide (CaO), and sewage waste (sewage waste 1 and 2) was used as raw materials for SiO2.

[0029] Generally, waste limestone refers to limestone with a calcium carbonate (CaCO3) content of 75% or less and a silicon oxide (SiO2) content of 10% or more, and the calcium carbonate can be verified by taking the value of calcium oxide (CaO) * 1.784. Paper sludge is sludge generated during the papermaking process and is characterized by containing a large amount of moisture, as well as having a calcium oxide (CaO) content of 80% or more after drying. Sewage waste is waste generated in water supply and sewage systems and is characterized by containing a large amount of moisture, and upon drying, having a silicon oxide (SiO2) content of 90% or a metal oxide such as aluminum oxide (Al2O3) of 10%.

[0030] When the above waste limestone, paper sludge, and sewage waste are used as raw materials for cement, there was a problem in that the quality of the cement deteriorated because major minerals of cement clinker, such as wollastonite (CaSiO3) and rankinite (Ca3Si2O7), were not synthesized due to silicon oxide present in high amounts; alkali components including Na2O and K2O; or metal oxides including Al2O3 and MgO.

[0031] Accordingly, in this invention, through various embodiments, it was confirmed whether it is possible to manufacture a carbon dioxide reaction-cured cement clinker with excellent performance by reducing impurities during the process of applying heat when manufacturing cement clinker, thereby ensuring that target minerals are well formed in the cement clinker produced through carbon dioxide reaction-curing, and the optimal conditions for this were identified.

[0032] Table 1 below shows the results of analyzing the raw material for manufacturing carbon dioxide reaction-hardened cement clinker of the present invention using XRF. The above analysis results were obtained by measuring 1 g of the sample after heating it at 950°C until a constant weight was achieved.

[0033] XRF(Mass %) CaO raw materials SiO2 raw material waste limestone Paper sludge Sewage waste 1 Sewage waste 2 Na2O 0.2 3.52 0.40 5.02 MgO 2.1 0.84 0.58 0.82 Al2O3 2.39 0.47 1.93 10.80 SiO2 22.83 1.23 84.60 75.51 P2O5 - 0.25 0.36 0.19 SO3 0.21 1.22 0.21 0.43 Cl - 0.03 0.02 0.10 K2O 1.01 0.19 0.67 1.74 CaO 38.66 53.7 1.09 0.95 TiO2 - 0.04 0.40 0.20 V2O5 - - 0.04 - Cr2O3 - - 0.12 0.45 MnO - 0.03 0.03 0.09 Fe2O3 0.64 0.73 1.59 2.15 LOI, % 34.60 37.60 7.53 0.9

[0035] Table 2 below shows the results of calculating the amount of elements included in the raw materials for manufacturing carbon dioxide reaction-hardened cement clinker of the present invention.

[0036] Amount of element in sample before loss on ignition (Mass %) CaO raw materials SiO2 raw material waste limestone Paper sludge Sewage waste 1 Sewage waste 2 Na2O 0.31 5.64 0.43 5.07 MgO 3.21 1.34 0.62 0.83 Al2O3 3.65 0.75 2.09 10.90 SiO2 34.91 1.97 91.49 76.20 P2O5 - 0.40 0.39 0.19 SO3 0.32 1.96 0.23 0.43 Cl - 0.04 0.02 0.10 K2O 1.54 0.30 0.73 1.76 CaO 59.11 86.10 1.18 0.96 TiO2 - 0.07 0.43 0.20 V2O5 - - 0.04 - Cr2O3 - - 0.13 0.45 MnO - 0.04 0.04 0.09 Fe2O3 0.98 1.17 1.72 2.17

[0038] In the present invention, the amount of elements present in the raw material before loss on ignition (Mass %) was calculated by converting the XRF analysis results of the raw material for manufacturing carbon dioxide reaction-hardened cement clinker into a loss on ignition (LOI, %) value. The amount of the element was calculated using the following mathematical formula 1.

[0039]

[0041] As a result of the analysis, the waste limestone of the present invention was found to be unsuitable as a cement raw material, as it contained 59.11% calcium oxide (CaO), which is less than 70%, 34.91% silicon oxide (SiO2), and 3.65% and 3.21% metal oxides, aluminum oxide (Al2O3) and magnesium oxide (MgO). Additionally, the paper mill sludge of the present invention had a calcium oxide (CaO) content of 86.10%, but it was determined that calcination of the target mineral would not be easy due to the high content of sodium oxide (Na2O), an alkaline component. The sewage waste of the present invention was found to be unsuitable as a cement raw material, as it contained a significant amount of the metal oxides magnesium oxide (MgO) and aluminum oxide (Al2O3), even though it contained 75% or more silicon oxide (SiO2).

[0043] 2. Composition for manufacturing carbon dioxide reaction-hardened cement clinker

[0044] 1) Composition for manufacturing carbon dioxide reaction-hardened cement clinker containing waste limestone and sewage waste

[0045] In the present invention, a composition for manufacturing carbon dioxide reaction-hardened cement clinker was prepared by optimally mixing waste limestone and sewage waste. The composition for manufacturing carbon dioxide reaction-hardened cement clinker of the present invention used waste limestone as a calcium oxide (CaO) raw material and sewage waste 1 and sewage waste 2 as silicon oxide (SiO2) raw materials.

[0046] Table 3 below shows the composition of the carbon dioxide reaction-hardened cement clinker composition of the present invention, comprising waste limestone and sewage waste.

[0047] Raw Material (Mass %) composition Waste limestone (C) Sewage Waste 1(S) Sewage Waste 2(S) S / (C+S) CaO SiO2 SiO2 Example 1 51.58 42.26 - 0.45 Example 2 50.42 43.40 - 0.46 Example 3 49.26 44.53 - 0.47 Example 4 47.53 46.22 - 0.49 Example 5 50.97 - 40.69 0.44 Example 6 49.23 - 41.93 0.46 Example 7 47.48 - 43.16 0.48 Example 8 45.74 - 44.40 0.49

[0049] The composition for manufacturing carbon dioxide reaction-hardened cement clinker according to the present invention derives an optimal ratio based on the raw material composition ratio of calcium oxide (CaO) contained in waste limestone after loss on ignition and silicon oxide (SiO2) contained in sewage waste after loss on ignition. The above raw material composition ratio is explained by the following Equation 2.

[0050]

[0051] In the above mathematical formula 2, S represents the Mass % of SiO2 contained in the raw material, and C represents the Mass % of CaO contained in the raw material.

[0053] The composition for manufacturing carbon dioxide reaction-hardened cement clinker was mixed and molded according to the criteria in Table 3, and then carbon dioxide reaction-hardened cement clinker was manufactured according to the following steps. The major mineral phases (Pseudo-Wollastonite and Rankinite) related to carbon dioxide reaction hardening were analyzed from the manufactured carbon dioxide reaction-hardened cement clinker, and it was confirmed whether limestone dusting and melting occurred during the manufacturing process of the carbon dioxide reaction-hardened cement clinker.

[0054] The manufacture of the above carbon dioxide reaction-hardened cement clinker was carried out by a manufacturing method comprising the following steps: a first step of manufacturing a molded body using a composition for manufacturing carbon dioxide reaction-hardened cement clinker; a second step of first heating the molded body from room temperature to 300°C for 60 minutes at a heating rate of 5°C / min; a third step of secondarily heating the firstly heated molded body from 300°C to 850°C for 55 minutes at a heating rate of 10°C / min; a fourth step of maintaining the secondarily heated molded body at 850°C for 30 minutes to decarbonize it and prevent limestone dusting; a fifth step of thirdly heating the decarbonized molded body from 850°C to 1270°C for 42 minutes at a heating rate of 10°C / min; and a sixth step of manufacturing the carbon dioxide reaction-hardened cement clinker by maintaining the thirdly heated molded body at 1270°C for 2 hours. and the seventh step of cooling the carbon dioxide reaction-hardened cement clinker produced above under slow cooling conditions. For reference, it was confirmed that in all examples, when the third step of decarbonization was not performed, differentiation occurred.

[0055] Table 4 below shows the results of confirming the major mineral phases related to carbon dioxide reaction hardening of the carbon dioxide reaction hardening cement clinker of the present invention, whether limestone dusting occurs, and whether melting occurs.

[0056] S / (C+S) Major mineral phases (%) related to carbon dioxide reaction hardening Whether limestone has differentiated Whether it melts Pseudo Wollastonite Rankinite bout(%) Example 1 0.45 37.67 35.18 72.9 O X Example 2 0.46 43.39 29.16 72.6 O X Example 3 0.47 48.86 22.92 71.6 X X Example 4 0.49 53.02 17.43 70.5 X X Example 5 0.44 42.26 27.37 69.6 X X Example 6 0.46 48.43 18.54 67.0 X O Example 7 0.48 55.21 10.24 65.5 X O Example 8 0.49 60.61 4.07 64.7 X O

[0058] As a result of the analysis, in the case of carbon dioxide reaction-hardened cement clinker (Examples 1 to 4) manufactured using waste limestone and sewage waste 1, it was confirmed that the major mineral phases related to carbon dioxide reaction-hardening were synthesized most in Example 1, where the raw material composition ratio (S / (C+S)) value was 0.45. However, in Examples 1 and 2, where the raw material composition ratio (S / (C+S)) values ​​were 0.45 and 0.46, respectively, it was confirmed that limestone differentiation occurred. The above limestone differentiation is the fine pulverization of the carbon dioxide reaction-hardened cement clinker, which contains the same mineral phase as the clinker but has an average fineness of 1000 cm² / g. Therefore, when the clinker is ground to manufacture cement, it is difficult to control the particle size, making it difficult to maintain the quality of the cement. Furthermore, when manufactured and used as cement, the imbalance in fineness and particle size may affect the reaction. It was confirmed that melting did not occur in any of the carbon dioxide reaction-hardened cement clinkers manufactured using waste limestone and sewage waste 1 according to the present invention. The aforementioned melting refers to the liquefaction of the raw materials during clinker production; since liquefied clinker cannot be granulated during clinker grinding, cement production becomes difficult.

[0059] Therefore, it is determined that the carbon dioxide reaction-hardened cement clinker produced using waste limestone and sewage waste 1 of the present invention is preferably the composition of Example 3, in which major mineral phases related to carbon dioxide reaction-hardening are synthesized in large quantities without limestone differentiation or melting.

[0060] As a result of the analysis, for carbon dioxide reaction-hardened cement clinkers (Examples 5 to 8) prepared using waste limestone and sewage waste 2, it was confirmed that the major mineral phases related to carbon dioxide reaction-hardening were synthesized most abundantly in Example 5, where the raw material composition ratio (S / (C+S)) value was 0.44. It was confirmed that as the raw material composition ratio (S / (C+S)) value decreased, the synthesis of the major mineral phases related to carbon dioxide reaction-hardening decreased, and the clinker melted. It was confirmed that no limestone differentiation occurred in any of the carbon dioxide reaction-hardened cement clinkers prepared using waste limestone and sewage waste 2 according to the present invention. Therefore, regarding the carbon dioxide reaction-hardened cement clinker prepared using waste limestone and sewage waste 2 according to the present invention, the composition of Example 5, which synthesizes a large amount of major mineral phases related to carbon dioxide reaction-hardening without limestone differentiation or melting, is considered preferable.

[0061] The carbon dioxide reaction-hardened cement clinker of the present invention undergoes loss on ignition during the heating process. Table 2 above shows the results of converting the elements contained in the sample of the present invention to the values ​​prior to loss on ignition. Based on the above experimental results, the optimal composition of the carbon dioxide reaction-hardened cement clinker of the present invention is summarized as follows.

[0062] The optimal composition of the carbon dioxide reaction-hardened cement clinker of the present invention is a composition in which, when manufacturing the carbon dioxide reaction-hardened cement clinker using waste limestone having a calcium oxide (CaO) content of 57 to 63 Mass %, a silicon oxide (SiO2) content of 32 to 38 Mass %, and an aluminum oxide (Al2O3) content of 3 to 4 Mass %; and sewage waste having a silicon oxide (SiO2) content of 89 to 94 Mass %, an aluminum oxide (Al2O3) content of 1.5 to 2.5 Mass %, and a calcium oxide (CaO) content of 0.5 to 1.5 Mass %, the ratio of calcium (Ca) to silicon (Si) content (S / (C+S), where C represents the calcium content and S represents the silicon content) is 0.465 to 0.48. If the ratio of calcium (Ca) to silicon (Si) content is less than 0.465, there is too much limestone content, causing limestone fragmentation. Consequently, when clinker is ground to manufacture carbon dioxide reaction hardened cement, it is difficult to control the particle size, which leads to a problem of reduced quality. Additionally, even if the ratio of calcium (Ca) to silicon (Si) content exceeds 0.48, the major mineral phases related to carbon dioxide reaction hardening do not increase, so the quality does not improve when clinker is ground to manufacture carbon dioxide reaction hardened cement.

[0063] Another optimal composition of the carbon dioxide reaction-hardened cement clinker of the present invention is a composition in which the ratio of calcium (Ca) to silicon (Si) content (S / (C+S), where C represents the calcium content and S represents the silicon content) is 0.43 to 0.45 when manufacturing the carbon dioxide reaction-hardened cement clinker using waste limestone having a calcium oxide (CaO) content of 57 to 63 Mass %, silicon oxide (SiO2) content of 32 to 38 Mass %, and aluminum oxide (Al2O3) content of 3 to 4 Mass %; and sewage waste having a silicon oxide (SiO2) content of 73 to 80 Mass %, aluminum oxide (Al2O3) content of 8 to 14 Mass %, and calcium oxide (CaO) content of 0.5 to 1.5 Mass %. If the ratio of calcium (Ca) to silicon (Si) content is less than 0.43, the content of major mineral phases related to carbon dioxide reaction hardening is low, and the quality deteriorates when carbon dioxide reaction hardening cement is manufactured by grinding the clinker. In addition, if the ratio of calcium (Ca) to silicon (Si) content exceeds 0.45, the content of metal oxides is high, which lowers the melting point of the clinker. This causes damage to the inner wall of the kiln, accelerates erosion of refractory materials, uneven clinker coating, suppression of clinker discharge, and non-uniformity of clinker size and shape, which leads to problems such as increased manufacturing costs or deterioration of cement quality.

[0065] 2) Composition for manufacturing carbon dioxide reaction-hardened cement clinker containing paper mill sludge and sewage waste

[0066] In the present invention, a composition for manufacturing carbon dioxide reaction-hardened cement clinker was prepared by optimally mixing paper mill sludge and sewage waste.

[0067] The composition for manufacturing carbon dioxide reaction-hardened cement clinker of the present invention used paper mill sludge as a calcium oxide (CaO) raw material and sewage waste 1 as a silicon oxide (SiO2) raw material.

[0068] Table 5 below shows the composition of the carbon dioxide reaction-hardened cement clinker composition of the present invention, comprising paper mill sludge and sewage waste 1.

[0069] Raw Material (Mass %) composition Paper mill sludge (C) Sewage Waste 1(S) S / (C+S) CaO SiO2 Example 9 53.40 37.66 0.41 Example 10 55.11 35.89 0.39 Example 11 57.20 32.41 0.36 Example 12 59.39 31.48 0.35 Example 13 61.10 29.72 0.33 Example 14 62.82 27.95 0.31 Example 15 64.53 26.19 0.29 Example 16 66.24 24.42 0.27

[0071] The composition for manufacturing carbon dioxide reaction-hardened cement clinker according to the present invention derives an optimal ratio based on the raw material composition ratio of calcium oxide (CaO) contained in paper sludge after loss on ignition and silicon oxide (SiO2) contained in sewage waste after loss on ignition. The above raw material composition ratio is explained by the following Equation 2.

[0072] The composition for manufacturing carbon dioxide reaction-hardened cement clinker was mixed and molded according to the criteria in Table 5, and then carbon dioxide reaction-hardened cement clinker was manufactured according to the following steps. The major mineral phases (Pseudo-Wollastonite and Rankinite) related to carbon dioxide reaction hardening were analyzed from the manufactured carbon dioxide reaction-hardened cement clinker, and it was confirmed whether limestone dusting and melting occurred during the manufacturing process of the carbon dioxide reaction-hardened cement clinker.

[0073] The manufacture of the carbon dioxide reaction-hardened cement clinker was carried out by a manufacturing method comprising the following steps: a first step of manufacturing a molded body using a composition for manufacturing carbon dioxide reaction-hardened cement clinker; a second step of first heating the molded body from room temperature to 300°C for 60 minutes at a heating rate of 5°C / min; a third step of secondarily heating the firstly heated molded body from 300°C to 1250°C for 97 minutes at a heating rate of 10°C / min; and a fourth step of manufacturing the carbon dioxide reaction-hardened cement clinker by maintaining the secondarily heated molded body at 1250°C for 120 minutes.

[0074] Table 6 below shows the results of confirming the major mineral phases related to carbon dioxide reaction hardening of the carbon dioxide reaction hardening cement clinker of the present invention, whether limestone dusting occurs, and whether melting occurs.

[0075] S / (C+S) Major mineral phases (%) related to carbon dioxide reaction hardening Whether limestone has differentiated Whether it melts Pseudo Wollastonite Rankinite bout(%) Example 9 0.41 64.5 24.2 88.7 X X Example 10 0.39 51.8 34.7 86.4 X X Example 11 0.36 37.9 52.7 90.7 X X Example 12 0.35 29.8 54.4 84.2 X X Example 13 0.33 10.6 52.4 63.0 X X Example 14 0.31 10.8 52.9 63.7 X X Example 15 0.29 8.4 34.0 42.4 X X Example 16 0.27 5.9 4.1 10.0 X X

[0077] As a result of the analysis, in the case of carbon dioxide reaction-hardened cement clinker prepared using paper sludge and sewage waste 1, it was confirmed that the major mineral phases related to carbon dioxide reaction-hardening were synthesized most in Example 11, where the raw material composition ratio (S / (C+S)) value was 0.36, and it was confirmed that the synthesis of the major mineral phases related to carbon dioxide reaction-hardening decreased when the raw material composition ratio (S / (C+S)) value was 0.39 or higher or 0.35 or lower. In addition, it was confirmed that limestone differentiation and melting did not occur in all examples of the carbon dioxide reaction-hardened cement clinker prepared using paper sludge and sewage waste 1 according to the present invention.

[0078] The above results differ from the results of Examples 1 to 4 using waste limestone and sewage waste 1, and it is determined that this is because, due to the characteristics of paper mill sludge, it has a higher calcium oxide (CaO) content and a lower content of metal oxides (Al2O3, MgO, etc.), while having a higher content of alkali components (Na2O, etc.). In particular, since the alkali components interfere with the synthesis of the target synthetic mineral during calcination, it is important to derive the optimal combination ratio of the raw materials.

[0079] The carbon dioxide reaction-hardened cement clinker of the present invention undergoes loss on ignition during the heating process. Table 2 above shows the results of converting the elements contained in the sample of the present invention to the values ​​prior to loss on ignition. Based on the above experimental results, the optimal composition of the carbon dioxide reaction-hardened cement clinker of the present invention is summarized as follows.

[0080] The optimal composition of the carbon dioxide reaction-hardened cement clinker of the present invention is a composition in which the ratio of calcium (Ca) to silicon (Si) content (S / (C+S), where C represents the calcium content and S represents the silicon content) is 0.355 to 0.38 when manufacturing the carbon dioxide reaction-hardened cement clinker using paper mill sludge having a calcium oxide (CaO) content of 82 to 90 Mass %, a silicon oxide (SiO2) content of 1.5 to 3 Mass %, and a sodium oxide (Na2O) content of 5 to 6 Mass %; and sewage waste having a silicon oxide (SiO2) content of 89 to 94 Mass %, a calcium oxide (CaO) content of 0.5 to 1.5 Mass %, and a sodium oxide (Na2O) content of 0.3 to 0.6 Mass %. If the ratio of calcium (Ca) to silicon (Si) content is less than 0.355 or greater than 0.38, the synthesis of major mineral phases related to carbon dioxide reaction hardening decreases, and the performance may be degraded when the clinker is ground and used as carbon dioxide reaction hardening cement.

[0082] 3. Cement manufactured using carbon dioxide reaction-hardened cement clinker

[0083] Carbon dioxide reaction-hardened cement clinker (Examples 5 and 11) prepared with the optimal composition ratio confirmed through the above examples was prepared with a fineness of 4000, 4500, or 5000 cm 2 Carbon dioxide reaction hardening cement was prepared by grinding to a ratio of 1 / g, and mortar was prepared by mixing under conditions of water / cement = 0.5 and cement / standard sand = 1 / 3, after which molded bodies were manufactured. The flow test of the above mortar was measured using a vernier caliper after 15 compactions of two layers in accordance with KS L 5111. Immediately after manufacturing, the molded bodies were placed in a curing chamber at 20°C, 60% relative humidity, and a 20% CO2 atmosphere, demolded, and cured for 1, 3, and 7 days, after which the compressive strength was evaluated. The manufacturing and strength measurement of the above molded bodies were carried out in accordance with KS L ISO 679.

[0084] Table 7 shows the results of analyzing the performance of the carbon dioxide reaction hardening cement of the present invention.

[0085] clinker Powder Flow Compressive strength 1 day 3 days 7 days Example 17 Example 5 4000㎝ 2 / g 233㎜ 1.1MPa 20.7MPa 24.2MPa Example 18 Example 5 4500㎝ 2 / g 227㎜ 1.0MPa 17.6MPa 19.0MPa Example 19 Example 5 5000㎝ 2 / g 222㎜ 1.6MPa 19.9MPa 21.1 MPa Example 20 Example 11 4000㎝ 2 / g 215㎜ 2.5MPa 13.3MPa 20.8MPa Example 21 Example 11 4500㎝ 2 / g 210㎜ 1.1MPa 18.1 MPa 34.5MPa Example 22 Example 11 5000㎝ 2 / g 201㎜ 1.8MPa 13.4 MPa 18.2 MPa

[0087] Analysis results show that when cement is manufactured using the carbon dioxide reaction-hardened cement clinker containing waste limestone and sewage waste of the present invention (Example 5), the fineness is 4000 cm 2 It was confirmed that cement produced by grinding to a compressive strength of 1 / g exhibited the best workability and compressive strength. In particular, given that the aforementioned compressive strength represents the efficiency of carbon dioxide penetration into the molded body for hardening due to the characteristics of cement hardened using carbon dioxide, it is determined that the higher the compressive strength, the more efficiently the hardening process by carbon dioxide proceeds.

[0088] Analysis results show that when cement is manufactured using the carbon dioxide reaction-hardened cement clinker containing paper mill sludge and sewage waste of the present invention (Example 11), the fineness is 4500 cm 2 It was confirmed that cement produced by grinding to 1 / g exhibits excellent workability and the highest compressive strength.

[0089] The specific embodiments described herein represent preferred embodiments or examples of the invention and do not limit the scope of the invention. It is evident to those skilled in the art that variations and other uses of the invention do not deviate from the scope of the invention as described in the claims of this specification.

Claims

Claim 1 A carbon dioxide reaction-hardened cement clinker comprising paper sludge and sewage waste, characterized by being manufactured by a method comprising: a first step of manufacturing a molded body using a composition for manufacturing a carbon dioxide reaction-hardened cement clinker comprising paper sludge and sewage waste; a second step of first heating the molded body from room temperature to 280 to 320°C for 50 to 70 minutes at a heating rate of 5°C / min; a third step of secondarily heating the firstly heated molded body from 280 to 320°C to 1150 to 1350°C for 95 to 100 minutes at a heating rate of 10°C / min; and a fourth step of maintaining the secondarily heated molded body at 1150 to 1350°C for 100 to 140 minutes to manufacture the carbon dioxide reaction-hardened cement clinker comprising paper sludge and sewage waste. Claim 2 A carbon dioxide reaction-hardened cement clinker comprising paper sludge and sewage waste, wherein, in claim 1, the paper sludge is characterized by having a calcium oxide (CaO) content of 82 to 90 Mass %, a silicon oxide (SiO2) content of 1.5 to 3 Mass %, and a sodium oxide (Na2O) content of 5 to 6 Mass %; and the sewage waste is characterized by having a silicon oxide (SiO2) content of 89 to 94 Mass %, an aluminum oxide (Al2O3) content of 1.5 to 2.5 Mass %, and a calcium oxide (CaO) content of 0.5 to 1.5 Mass %. Claim 3 In claim 1, the carbon dioxide reaction-hardened cement clinker comprising paper sludge and sewage waste is characterized by having a calcium (Ca) to silicon (Si) content ratio (S / (C+S, where C represents the calcium content and S represents the silicon content) of 0.355 to 0.

38. Claim 4 delete Claim 5 A carbon dioxide reaction hardened cement comprising paper sludge and sewage waste, manufactured using a carbon dioxide reaction hardened cement clinker comprising paper sludge and sewage waste according to any one of claims 1 to 3. Claim 6 In claim 5, the carbon dioxide reaction-hardened cement containing the paper mill sludge and sewage waste comprises a carbon dioxide reaction-hardened cement clinker containing the paper mill sludge and sewage waste with a fineness of 4300 to 4700 cm 2 Carbon dioxide reaction hardening cement containing paper sludge and sewage waste, characterized by being manufactured by grinding to a weight of 1 / g.

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