Method for using cement raw material

Abstract

To provide a method for using cement raw materials that can control the amount of air pollutants contained in the exhaust gas produced when the cement raw materials are heated.SOLUTION: A method for using cement raw materials according to the present invention includes: a step (a) of preparing information on a first organic matter amount, which is the amount of organic matter contained in a first cement raw material, and information on a second organic matter amount, which is the amount of organic matter contained in a second cement raw material; a step (b) of estimating a third organic matter amount, which is the amount of organic matter contained in a third cement raw material obtained by mixing the first cement raw material and the second cement raw material, by calculation based on the mixing ratio of the first cement raw material and the second cement raw material, the first organic matter amount and the second organic matter amount; and a step (c) of charging the third cement raw material from an upper part of a preheater attached to a cement kiln when an evaluation value based on the third organic matter amount is equal to or less than a predetermined threshold value.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a method for using a cement raw material. [Background technology]

[0002] Currently, efforts are being made to use waste materials as part of the raw materials for cement in order to realize a sustainable society. A specific example is a method in which raw materials containing limestone and clay, which are obtained by crushing in a raw material mill at a cement factory (hereinafter referred to as "main cement raw materials"), are mixed with raw materials made from waste materials (hereinafter referred to as "recycled raw materials"), and then the mixture is put into a cement kiln and fired.

[0003] However, there is concern that the amount of air pollutants contained in cement kiln exhaust gas will increase due to the diversification and increase in the amount of waste, as well as the diversification and increase in the amount of by-products produced by burning waste. In particular, persistent organic pollutants (POPs), which are air pollutants, are difficult to decompose naturally and may affect ecosystems and humans through bioaccumulation through the food chain, etc., so it is important to reduce their emissions. Dioxins (DXNs) are known as an example of POPs.

[0004] In response to the above problems, the applicant has proposed in Patent Document 1 listed below a method in which cement kiln exhaust gas is collected by a dust collector to capture kiln dust with an increased concentration of dioxins. The kiln dust is then poured into the bottom of the kiln or below the preheater, and the dioxins are decomposed by heating using the heat generated during cement burning. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 4948446 Summary of the Invention [Problem to be solved by the invention]

[0006] However, with the recent diversification of recycled raw materials, there are cases where it is difficult to reduce the risk of emitting air pollutants using only the above techniques, and further measures are required. In view of the above circumstances, the present invention has an object to provide a method for using cement raw materials that can reduce the amount of air pollutants contained in exhaust gas generated when the cement raw materials are heated. [Means for solving the problem]

[0007] The method for using the cement raw material according to the present invention includes the steps of: A step (a) of preparing information on a first organic matter amount, which is an amount of organic matter contained in a first cement raw material, and information on a second organic matter amount, which is an amount of organic matter contained in a second cement raw material made of a material different from the first cement raw material; a step (b) of estimating a third organic matter amount, which is an organic matter amount contained in a third cement raw material obtained by mixing the first cement raw material and the second cement raw material, by calculation based on a mixing ratio of the first cement raw material and the second cement raw material, the first organic matter amount, and the second organic matter amount; and (c) comparing an evaluation value based on the third organic matter amount with a predetermined threshold value, and if the evaluation value is equal to or less than the predetermined threshold value, adding the third cement raw material from above a preheater attached to a cement kiln.

[0008] The information on the first organic matter amount can be obtained in advance, for example, by conducting an organic matter amount measurement test on the first cement raw material. Similarly, the information on the second organic matter amount can be obtained in advance, for example, by conducting an organic matter amount measurement test on the second cement raw material.

[0009] To produce cement clinker, cement raw materials are fed into a cement kiln via a preheater or other device and heated. When the cement raw materials are heated, the organic components contained in the cement raw materials undergo complex reactions such as combustion, pyrolysis, and synthesis, generating air pollutants. In other words, it is believed that there is a close relationship between the amount of organic matter contained in the cement raw materials and the amount of air pollutants generated.

[0010] Here, most of the organic matter is heated at high temperature and is oxidatively decomposed, thermally decomposed, etc., and converted into gases such as CO2. Therefore, the amount of organic matter contained can be grasped by checking the degree of weight loss before and after heating. That is, an ignition loss test can be used as the organic matter amount measurement test. More specifically, an ignition loss test is performed on the first cement raw material at a predetermined first temperature to measure the ignition loss (IL), and the organic matter amount of the first cement raw material (first organic matter amount) can be derived based on this measurement value. Similarly, an ignition loss test is performed on the second cement raw material at a predetermined first temperature to measure the ignition loss, and the organic matter amount of the second cement raw material (second organic matter amount) can be derived based on this measurement value.

[0011] That is, the step (a) is (a1) measuring the ignition loss of the first cement raw material and the second cement raw material at a first temperature corresponding to a heating environment in an upper portion of a preheater attached to a cement kiln; The method may include a step (a2) of deriving the first organic matter amount based on an ignition loss of the first cement raw material at the first temperature, and deriving the second organic matter amount based on an ignition loss of the second cement raw material at the first temperature.

[0012] Information relating to the obtained organic substance amounts (first organic substance amount, second organic substance amount) may be recorded in a storage medium (flash memory, cloud server, etc.).

[0013] For example, when the second cement raw material is waste α, an ignition loss test is performed on the waste α in advance to measure the ignition loss, and the second organic amount can be derived based on this measured value. Also, when the second cement raw material is waste β different from the waste α, an ignition loss test is performed on the waste β in advance to measure the ignition loss, and the second organic amount can be derived based on this measured value. In other words, even when a wide variety of recycled raw materials are used as the second cement raw material, by deriving in advance the amount of organic matter contained in the recycled raw materials used, it is possible to predict the amount of air pollutants contained in the exhaust gas generated during heating according to the recycled raw material used.

[0014] Then, when the first cement raw material and the second cement raw material, which are made of different materials, are mixed to produce cement, it is possible to estimate the amount of air pollutants contained in the exhaust gas generated when the mixed cement raw material (third cement raw material) is heated, based on the respective organic matter amounts (first organic matter amount, second organic matter amount) and the mixing ratio.

[0015] In other words, according to the above method, in step (b), before the third cement raw material is actually charged from above the preheater into the cement kiln, it is possible to estimate the amount of organic matter contained in the third cement raw material (third organic matter amount) by a calculation including the previously prepared first organic matter amount and second organic matter amount, and the mixing ratio of the first cement raw material and the second cement raw material.

[0016] The "first cement raw material" is not limited to a raw material made of a single material, and may be a raw material made of a mixture of multiple materials. Similarly, the "second cement raw material" is not limited to a raw material made of a single material, and may be a raw material made of a mixture of multiple materials.

[0017] As described above, in step (c), an evaluation value based on the third organic matter amount is compared with a predetermined threshold value. Here, the "evaluation value" may be a value of the third organic matter amount, or may be a value resulting from a calculation using the value of the third organic matter amount. As an example of the latter, the ratio of the third organic matter amount to the smaller value of the first organic matter amount and the second organic matter amount (here, the first organic matter amount) may be adopted. As another example, the difference value between the third organic matter amount and the first organic matter amount may be adopted. The "evaluation value" adopted here is a value that shows a positive correlation with the third organic matter amount.

[0018] When burning cement raw materials, the cement raw materials are generally charged from the top of a preheater. As the cement raw materials pass through the preheater, they gradually increase in temperature while exchanging heat with the combustion exhaust gas from the cement kiln, and are eventually charged into the cement kiln. Typically, the cement raw materials are in a temperature environment of 500°C to 600°C when they pass through the top of the preheater, and in a temperature environment of 800°C to 1,000°C when they reach the bottom of the preheater. When they are charged into the cement kiln, they are in a temperature environment of 1,000°C or more, more typically about 1,300°C to 1,500°C.

[0019] Air pollutants generated when cement raw materials are heated are believed to originate from organic matter contained in the cement raw materials, and more specifically, from precursor substances generated by conversion of the organic matter during incomplete combustion in the preheater, particularly in the upper part of the preheater. Meanwhile, near the exhaust gas inlet of the preheater, the temperature of the exhaust gas is high, and the time required for the exhaust gas to pass through the preheater before reaching the preheater outlet is also long, so that most of the organic matter contained in the cement raw materials is oxidized and decomposed into CO2. In other words, near the exhaust gas inlet of the preheater, it is believed that the amount of air pollutants generated is extremely low or almost not generated.

[0020] The preheater is installed to preheat the cement raw materials using the heat of the high-temperature exhaust gas discharged from the cement kiln. In other words, the flow of the cement raw materials fed into the top of the preheater and the flow of the exhaust gas discharged from the cement kiln are in the opposite direction. The exhaust gas discharged from the cement kiln moves upward through the preheater, then passes through a cooling and recovery system and is discharged into the atmosphere from the chimney.

[0021] The gas (cement kiln exhaust gas) after heat exchange with the cement raw materials at the top of the preheater is then sent to the cooling and recovery system. In other words, the exhaust gas that has passed through the top of the preheater is not subsequently placed in a higher temperature environment than the top of the preheater. Therefore, if air pollutants are contained in the exhaust gas as a result of heat exchange with the cement raw materials at the top of the preheater, there is a low possibility that these air pollutants will be subsequently thermally decomposed.

[0022] In other words, placing the cement raw materials in the temperature environment above the preheater generates air pollutants derived from the organic matter contained in the cement raw materials, and the amount of these generated is a determining factor in the amount of air pollutants contained in the exhaust gas. The amount of air pollutants generated by placing the cement raw materials in the temperature environment above the preheater is thought to show a high correlation with the amount of organic matter in the cement raw materials calculated based on the ignition loss of the cement raw materials in a temperature environment similar to that of the upper part of the preheater.

[0023] From this viewpoint, the first temperature in the step (a1) is set to a temperature corresponding to the heating environment in the upper part of a preheater attached to the cement kiln. In detail, the first temperature is preferably set to a temperature in the range of 400°C to 700°C, more preferably to a temperature in the range of 400°C to 650°C, and particularly preferably to a temperature in the range of 450°C to 600°C.

[0024] When the first cement raw material is a blended raw material (main cement raw material) blended in the raw material process, it contains clay and limestone. Calcium carbonate in limestone undergoes a decarbonation reaction and generates CO2 at a temperature range exceeding 600°C, more precisely at a temperature of about 650°C to 900°C. Therefore, when the ignition loss of the first cement raw material is measured at a temperature significantly higher than 600°C, the weight loss caused by the generation of CO2 is accompanied, and the correlation between the measured ignition loss value and the amount of organic matter (first organic matter amount) contained in the first cement raw material decreases. From this viewpoint, the first temperature is more preferably a temperature in the range of 400°C to 650°C, and particularly preferably a temperature in the range of 450°C to 600°C.

[0025] The value of the amount of organic matter contained in the second cement raw material (second organic matter amount) is used in a calculation together with the first organic matter amount in step (b) and is used to estimate the amount of organic matter contained in the third cement raw material. From this viewpoint, when the first organic matter amount is set based on the ignition loss of the first cement raw material measured at the first temperature, it is preferable that the second organic matter amount is also set based on the ignition loss of the second cement raw material measured at the first temperature.

[0026] In this manner, when the ignition losses of the first cement raw material and the second cement raw material are measured at the first temperature in step (a1), the amount of organic matter in the first cement raw material (first organic matter amount) and the amount of organic matter in the second cement raw material (second organic matter amount) are derived in step (a2) based on the measured values.

[0027] As a specific example, in step (a2), the ignition loss of the first cement raw material at the first temperature may be regarded as the first organic matter amount, and the ignition loss of the second cement raw material at the first temperature may be regarded as the second organic matter amount.

[0028] As another specific example, The step (a) further includes a step (a3) ​​of measuring the loss on ignition of the first cement raw material and the second cement raw material at a second temperature higher than 100° C. and lower than the first temperature; In the step (a2), the first organic matter amount may be determined based on a difference between an ignition loss at the first temperature and an ignition loss at the second temperature of the first cement raw material, and the second organic matter amount may be determined based on a difference between an ignition loss at the first temperature and an ignition loss at the second temperature of the second cement raw material.

[0029] When the first cement raw material is a blended raw material (main cement raw material) blended in the raw material process, the first cement raw material contains substances having water of crystallization, such as gypsum dihydrate. This water of crystallization undergoes a desorption reaction in a temperature environment higher than 100° C., more specifically, in a temperature environment of 150° C. or higher. In other words, when the ignition loss of the first cement raw material is measured at the first temperature, the measurement result reflects the weight loss due to the desorption of substances having water of crystallization contained in the first cement raw material.

[0030] However, the gas generated by the desorption of the substance having water of crystallization is composed of HO, and is therefore not an air pollutant. Therefore, strictly speaking, the value of the loss on ignition measured for the first cement raw material at the first temperature reflects the amount of organic matter contained in the first cement raw material (first organic matter amount) and the amount of water of crystallization contained in the first cement raw material.

[0031] In contrast, in the above method, in step (a3), the ignition loss is measured under temperature conditions (second temperature) at which the water of crystallization contained in the first cement raw material is desorbed while the organic matter contained in the first cement raw material is not easily volatilized.

[0032] As described above, the value of the ignition loss of the first cement raw material at the first temperature obtained in step (a1) reflects the amount of organic matter contained in the first cement raw material (first organic matter amount) and the amount of water of crystallization contained in the first cement raw material. On the other hand, the value of the ignition loss of the first cement raw material at the second temperature obtained in step (a3) ​​reflects the amount of water of crystallization contained in the first cement raw material, but hardly reflects the amount of organic matter contained in the first cement raw material (first organic matter amount).

[0033] Therefore, the difference between the ignition loss of the first cement raw material at the first temperature and the ignition loss of the first cement raw material at the second temperature, which is derived in step (a2), is significantly affected by the presence of water of crystallization contained in the first cement raw material, and therefore shows a higher correlation between this difference value and the first organic matter amount.

[0034] The second organic matter amount is preferably calculated in the same manner as the first organic matter amount, and is derived based on the difference between the ignition loss at the first temperature and the ignition loss at the second temperature of the second cement raw material.

[0035] The second temperature is preferably a temperature at which organic matter contained in the first cement raw material is less likely to volatilize and at which crystallization water contained in the first cement raw material is desorbed. From this viewpoint, the second temperature is preferably a temperature within the range of 100°C to 350°C, more preferably a temperature within the range of 150°C to 350°C, and more preferably a temperature within the range of 150°C to 300°C.

[0036] In step (c), if it is confirmed that the evaluation value is equal to or less than a predetermined threshold value corresponding to the allowable standard for the amount of air pollutants generated, it is expected that the amount of air pollutants contained in the exhaust gas can be suppressed to or less than the allowable standard value even if the third cement raw material is actually fed from the top of the preheater toward the cement kiln. Therefore, according to the above method, it is possible to feed a cement raw material (third cement raw material) made of a mixture of multiple cement raw materials from the top of the preheater in the same way as a normal cement raw material (main cement raw material), while suppressing the amount of air pollutants generated.

[0037] In the step (c), if the evaluation value exceeds the predetermined threshold, the mixing ratio may be changed so that the evaluation value becomes equal to or less than the predetermined threshold, and the third cement raw material may be charged from an upper portion of the preheater.

[0038] According to the above method, even if the third cement raw material after the mixing ratio has been changed is actually charged into the cement kiln from above the preheater, the amount of air pollutants contained in the exhaust gas can be suppressed to or below the allowable standard value.

[0039] In the above-mentioned method for using a cement raw material, the second organic amount is higher than the first organic amount; In the step (c), when the evaluation value exceeds the predetermined threshold, the mixing ratio is changed by decreasing a relative ratio of the second cement raw material to the first cement raw material so that the evaluation value is equal to or less than the predetermined threshold, and then the third cement raw material is charged from an upper portion of the preheater; The method may further include a step (d) of feeding the second cement raw material from a lower portion of the preheater.

[0040] When the amount of the second organic matter is higher than the amount of the first organic matter, it is expected that the amount of air pollutants contained in the exhaust gas generated when the third cement raw material is heated increases as the ratio (mixing ratio) of the second cement raw material contained in the mixed cement raw material (third cement raw material) increases. Here, in the step (c), when the evaluation value exceeds a predetermined threshold value that is an allowable standard for the amount of air pollutants generated, it is preferable, from the viewpoint of reducing the amount of air pollutants generated, to reduce the ratio of the second cement raw material contained in the third cement raw material to reduce the amount of the third organic matter and make the evaluation value equal to or lower than the predetermined threshold value. However, in this case, it is expected that the consumption rate of the second cement raw material received at the cement plant will be slowed down.

[0041] As described above, the lower part of the preheater is in a higher temperature environment than the upper part of the preheater. Therefore, when the second cement raw material is added from this point, it is expected that most of the organic matter contained in the second cement raw material will be completely oxidized to CO2, and the amount of air pollutants generated will be low or almost zero.

[0042] Therefore, by reducing the ratio of the second cement raw material to make the evaluation value equal to or less than a predetermined threshold value, and further feeding the second cement raw material from the bottom of the preheater as in process (d), it is possible to suppress the amount of air pollutants contained in the exhaust gas while increasing the consumption of the second cement raw material which has a relatively high organic matter content.

[0043] Here, "adding from the bottom of the preheater" refers to the preheater inlet for exhaust gas, which includes the case of adding from the bottom of the cement kiln, as well as the case of adding from the cyclone closest to the cement kiln (hereinafter referred to as the "lowest cyclone") when the preheater is composed of multiple stages of cyclones, the case of adding from the cyclone located just before the lowest cyclone, and the case of adding from piping connecting these cyclones.

[0044] The first cement raw material is a blended raw material blended in a raw material step, The second cement raw material may be a waste material.

[0045] The waste that can be used includes general waste and industrial waste that are mainly composed of organic matter and have combustibility, such as waste plastics, wood chips, sludge, construction soil, ASR, waste tires, carbon fiber, carbon fiber reinforced plastics (CFRP), meat and bone meal, and biomass. Effect of the Invention

[0046] According to the present invention, it is possible to reduce the amount of air pollutants contained in the exhaust gas generated when the cement raw materials are heated, while utilizing a variety of cement raw materials. [Brief description of the drawings]

[0047] [Figure 1] 1 is a flowchart showing an example of a procedure for carrying out a method for using a cement raw material according to the present invention. [Diagram 2] 2 is a flowchart showing an example of a detailed procedure of step #1 in FIG. 1. [Diagram 3] 1 is a schematic diagram of a cement manufacturing apparatus including a cement kiln and a preheater attached to the cement kiln. [Figure 4] FIG. 1 is a block diagram showing a schematic configuration of an evaluation combustion system including a test kiln. [Diagram 5] This is a graph plotting the relationship between the actual measured values ​​of the toxic equivalents of dioxins (DXNs) contained in the sampled exhaust gas and the estimated (relative) values ​​of the organic matter amounts in the raw materials obtained by calculation. [Figure 6] This is a graph plotting the relationship between the actual measured values ​​of the toxic equivalents of dioxins (DXNs) contained in the sampled exhaust gas and the estimated (relative) values ​​of the ignition loss of the raw material at 600°C calculated. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0048] An embodiment of the method for using a cement raw material according to the present invention will be described with reference to the drawings as appropriate. Note that the drawings are schematic, and the dimensional ratios in the drawings do not necessarily match the actual dimensional ratios, and the dimensional ratios between the drawings do not necessarily match.

[0049] In the method of using a cement raw material according to the present invention, a cement raw material is used that is a mixture of cement raw materials made of different materials. Hereinafter, these cement raw materials made of different materials are referred to as a "first cement raw material C1" and a "second cement raw material C2", respectively. Moreover, a cement raw material that is a mixture of the first cement raw material C1 and the second cement raw material C2 is referred to as a "third cement raw material C0".

[0050] In the following, a case where the third cement raw material C0 is obtained by mixing two types of cement raw materials (C1, C2) will be described. However, a similar explanation can be applied to a case where the third cement raw material C0 is obtained by mixing three or more types of cement raw materials (C1, C2, C3, ...).

[0051] 1 and 2 are flow charts showing an example of a procedure for carrying out a method for using a cement raw material according to the present invention. In the following description, the step numbers shown in Figs. 1 and 2 will be referred to as appropriate.

[0052] (Preparation of information on organic matter content) First, a preparation step is performed (Step #1). Fig. 2 is a flow chart showing an example of a detailed procedure of Step #1. As shown in Fig. 2, by performing Step #1, the amount of organic matter corresponding to each of the first cement raw material C1 and the second cement raw material C2 is recorded.

[0053] Specifically, an organic matter amount measurement test is performed on each of the first cement raw material C1 and the second cement raw material C2 (step #11, step #21). In the following, an organic matter amount measurement test on the first cement raw material C1 will be described as an example.

[0054] The organic matter amount measurement test can be performed using an ignition loss test. For example, the ignition loss test can be performed using a method conforming to JIS A 1226:2020 "Ignition loss test method for soil."

[0055] More specifically, the ignition loss test is performed at a first temperature T1 close to the temperature of the exhaust gas passing through the upper part of the preheater. This first temperature T1 is preferably set to a temperature in the range of 400°C to 700°C, more preferably in the range of 400°C to 650°C, and particularly preferably in the range of 450°C to 600°C.

[0056] As a specific example, the weight W of the first cement raw material C1 1a After measuring the temperature T1, the first cement raw material C1 is held in the electric furnace set at the first temperature T1 for a predetermined time (for example, about 10 minutes). Then, the first cement raw material C1 is taken out of the electric furnace and its weight W 1b is measured. And the weight before heating W 1a The weight difference before and after heating (W 1a -W 1b This ratio is the ignition loss I of the first cement raw material C1 at the first temperature T1. 1a Corresponds to.

[0057] When the first cement raw material C1 is placed in an environment of the first temperature T1, at least a part of the organic matter contained in the first cement raw material C1 is volatilized. It is considered that the substances derived from the volatilized organic matter form air pollutants.

[0058] In reality, the first cement raw material C1 fed from the top of the preheater passes through successively high temperature environments by passing through multiple cyclones, and eventually reaches the cement kiln, which has the highest temperature. When the first cement raw material C1 reaches the bottom of the preheater, it is in a temperature environment of 800°C to 1,000°C, and when it is fed into the cement kiln, it is in a temperature environment of 1,000°C or more, more typically about 1,300°C to 1,500°C. In such an extremely high temperature environment, most of the organic matter contained in the cement raw material is oxidized and decomposed to CO2. In addition, the first cement raw material C1 passes through a high temperature environment for a certain period of time before passing through the top of the preheater and reaching the bottom of the preheater.

[0059] In other words, after the first cement raw material C1 passes through the upper part of the preheater, most of the organic matter contained in the first cement raw material C1 is oxidatively decomposed and converted into CO2, making it difficult for air pollutants derived from the organic matter to be generated.

[0060] According to the above, the ignition loss I derived by performing an ignition loss test on the first cement raw material C1 at the first temperature T1, which is close to the temperature of the exhaust gas passing through the upper part of the preheater, is 1a The value of corresponds to the amount of organic matter contained in the first cement raw material C1 that is volatilized due to incomplete combustion caused by heating the first cement raw material C1 at the first temperature T1. In this case, the amount of organic matter in the first cement raw material C1 (first organic matter amount O1) is calculated by dividing the ignition loss I 1a (Step #12).

[0061] Incidentally, when the first cement raw material C1 is a blended raw material (main cement raw material) blended in the raw material process, the first cement raw material C1 contains a substance having crystal water, such as gypsum dihydrate. This crystal water undergoes a desorption reaction in a temperature environment higher than 100° C., more specifically, in a temperature environment of 150° C. or higher. In other words, strictly speaking, the ignition loss I 1areflects the amount of organic matter contained in the first cement raw material C1 (first organic matter amount) and the amount of water of crystallization contained in the first cement raw material C1.

[0062] Therefore, the ignition loss due to the presence of water of crystallization I 1a From the viewpoint of reducing the discrepancy between the amount of organic matter actually contained in the first cement raw material C1 (first organic matter amount O1) and the first cement raw material C1, the ignition loss I 1b may be measured.

[0063] The second temperature T2 is preferably a temperature at which the organic matter contained in the first cement raw material C1 is less likely to volatilize and at which the crystallization water contained in the first cement raw material C1 is desorbed. From this viewpoint, the second temperature T2 is preferably a temperature within the range of 100°C to 350°C, more preferably a temperature within the range of 150°C to 350°C, and more preferably a temperature within the range of 150°C to 300°C.

[0064] Ignition loss I derived by performing an ignition loss test on the first cement raw material C1 at the second temperature T2 1b It is considered that the value of T2 substantially corresponds to the amount of crystallization water released from the first cement raw material C1, because at this second temperature T2, almost no organic matter contained in the first cement raw material C1 is volatilized.

[0065] Therefore, from the viewpoint of considering the amount of desorption of the water of crystallization contained in the first cement raw material C1, the amount of organic matter in the first cement raw material C1 (first organic matter amount O1) is calculated by multiplying the ignition loss I of the first cement raw material C1 at the first temperature T1 by the following formula: 1a and the ignition loss I of the first cement raw material C1 at the second temperature T2. 1b The difference value δI1 (δI1 = I 1a -I 1b ) (Step #12).

[0066] In the above description, the ignition loss test is performed as a test for measuring the amount of organic matter contained in the first cement raw material C1. However, the present invention is not limited to the ignition loss test, as long as the test can measure the amount of organic matter contained in the first cement raw material C1. For example, a total organic carbon (TOC) measurement test or a calorific value (higher, lower) measurement test can also be used. In the former case, for example, a method using a known TOC measurement device or a method conforming to ISO 10694:1995 "Soil quality - Determination of organic carbon and total carbon after dry combustion (elemental analysis)" can be used. In the latter case, for example, a method conforming to JIS Z 7302-2:1999 "Refuse-derived fuel - Part 2: Calorific value test method" can be used.

[0067] The information on the first organic substance amount O1 derived in this manner is recorded in a storage medium (step #13).

[0068] As with the first cement raw material C1, the second cement raw material C2 is also subjected to an organic matter amount measurement test, and the organic matter amount O2 is derived and recorded (steps #21 to #23). The organic matter amount O2 corresponding to the second cement raw material C2 corresponds to the "second organic matter amount."

[0069] The preparation step #1 is carried out by the above steps #11 to #13 and #21 to #23.

[0070] In the above method, the first organic matter amount O1 is determined by the ignition loss I of the first cement raw material C1 at the first temperature T1. 1a The value of the first cement raw material C1 at the first temperature T1 or the ignition loss I 1a and the ignition loss I of the first cement raw material C1 at the second temperature T2. 1b However, in the former case, the first organic matter amount O1 is calculated by multiplying the ignition loss I 1aIt is not excluded that the first organic amount O1 is a value obtained by performing a predetermined arithmetic operation on the difference value ΔI1. Similarly, in the latter case, it is not excluded that the first organic amount O1 is a value obtained by performing a predetermined arithmetic operation on the difference value ΔI1. The same is true for the second organic amount O2.

[0071] Next, the mixing ratio of the first cement raw material C1 and the second cement raw material C2 to realize the third cement raw material C0 is set (step #2). For example, if 60% of the third cement raw material C0 is composed of the first cement raw material C1 and 40% of the second cement raw material C2, the mixing ratio U1 of the first cement raw material C1 is 0.6, the mixing ratio U2 of the second cement raw material C2 is 0.4, and the mixing ratio of the two is 3:2. In other words, the mixing ratios U1 and U2 here are expressed as internal ratios.

[0072] Next, the amount of organic matter (third organic matter amount O0) contained in the third cement raw material C0 obtained by mixing the first cement raw material C1 and the second cement raw material C2 at the mixing ratio set in step #2 is derived by calculation based on the result obtained in step #1 (step #3).

[0073] It is expected that the higher the proportion of cement raw materials containing a higher amount of organic matter, the higher the amount of organic matter contained in the third cement raw material C0. More specifically, the amount of organic matter contained in the third cement raw material C0 (third organic matter amount O0) can be estimated by the following formula (1) using the first organic matter amount O1 of the first cement raw material C1, the blending ratio U1 of the first cement raw material C1, the second organic matter amount O2 of the second cement raw material C2, and the blending ratio U2 of the second cement raw material C2.

[0074]

number

[0075] Next, based on the third organic substance amount O0 derived in step #3, an evaluation value Y for evaluating the amount of air pollutants generated when the third cement raw material C0 is heated is calculated (step #4). As this evaluation value Y, the value of the third organic substance amount O0 itself can be used, or a value obtained by performing a predetermined calculation on the third organic substance amount O0 can be used. Here, for simplicity of explanation, the explanation will be continued by taking as an example a case where the evaluation value Y is the value of the third organic substance amount O0 itself.

[0076] Next, the evaluation value Y derived in step #4 and a preset reference threshold Y r (Step #5) Compare with the reference threshold Y r is preferably set to a reference value corresponding to the allowable limit of the amount of air pollutants contained in the exhaust gas. r If the evaluation value Y exceeds the standard threshold Y, the exhaust gas generated when the third cement raw material C0 is heated contains air pollutants in an amount that exceeds the permissible limit. r If it is below this level, it can be determined that the amount of air pollutants contained in the exhaust gas generated when the third cement raw material C0 is heated is suppressed to below the permissible limit.

[0077] Evaluation value Y is the standard threshold Y r If it is equal to or lower (Yes in step #5), the third cement raw material C0 is fed from the top of the preheater toward the cement kiln and used in cement production (step #6).

[0078] FIG. 3 is a schematic diagram of a cement manufacturing apparatus including a cement kiln and a preheater attached to the cement kiln. The cement manufacturing apparatus 1 shown in FIG. 3 includes a cement kiln 6 provided with a burner 7 and a preheater 5 connected above the cement kiln 6. In the example of FIG. 3, the preheater 5 includes five stages of cyclones, and the raw materials fed from the raw material feed port 21 are preheated by passing through the cyclones 5a, 5b, 5c, 5d, and 5e in this order and then fed into the cement kiln 6. In each cyclone (5a, 5b, 5c, 5d, 5e), the high-temperature gas discharged from the cement kiln 6 flows in, and heat exchange is performed between the raw materials and the cyclones. In other words, the gas discharged from the cement kiln 6 flows in the opposite direction to the flow of the raw materials, so that the environmental temperature becomes lower the further above the preheater 5 it is. In other words, cyclone 5a has the lowest temperature, and the environmental temperature becomes higher in the order of cyclone 5b, cyclone 5c, cyclone 5d, and cyclone 5e.

[0079] As described above, the first organic matter amount O1 and the second organic matter amount O2 prepared in step #1 correspond to the amounts of organic matter contained in the cement raw materials (C1, C2), respectively, and show a high correlation with the amount of air pollutants generated when the cement raw materials (C1, C2) are heated in a preheater, particularly in a heating environment equivalent to that when passing through the upper side of the preheater. Therefore, the third organic matter amount O0 calculated based on the first organic matter amount O1 and the second organic matter amount O2, and the evaluation value Y based thereon show a high correlation with the amount of air pollutants generated when the third cement raw material C0 is heated in a heating environment equivalent to that when passing through the preheater, particularly in a heating environment equivalent to that when passing through the upper side of the preheater.

[0080] Therefore, in step #5, the evaluation value Y is equal to the reference threshold Y rThe case where the amount of air pollutants contained in the exhaust gas generated when the third cement raw material C0 obtained by mixing the first cement raw material C1 and the second cement raw material C2 at the mixing ratio set in step #2 is introduced from above the preheater 5 through the raw material inlet 21 shown in FIG. 3 is equal to or less than the allowable limit value. Therefore, the evaluation value Y is equal to or less than the standard threshold value Y r If it is below the allowable limit (Yes in step #5), even if the third cement raw material C0 is fed from above the preheater 5 toward the cement kiln 6 (step #6), the amount of air pollutants contained in the generated exhaust gas is suppressed to be below the allowable limit.

[0081] On the other hand, the evaluation value Y is the standard threshold Y r If the amount exceeds the allowable limit (No in step #5), there is a concern that when the third cement raw material C0 is fed from the top of the preheater toward the cement kiln, the amount of air pollutants contained in the exhaust gas may exceed the allowable limit.

[0082] In this case, the mixing ratio of the first cement raw material C1 and the second cement raw material C2 is changed (step #7), and the third organic matter amount O0 and evaluation value Y are calculated again (steps #3 and #4). Note that, when the first cement raw material C1 is a mixed raw material (main cement raw material) mixed in the raw material process, and the second cement raw material C2 is a waste material, step #7 is actually a process of lowering the mixing ratio of the second cement raw material C2 in the third cement raw material C0, i.e., the value of the mix ratio U2.

[0083] For the third cement raw material C0 adjusted by changing the mixing ratio of the first cement raw material C1 and the second cement raw material C2, the evaluation value Y is r If it is equal to or lower than the reference threshold value Y (Yes in step #5), the third cement raw material C0 obtained under this adjusted mixing ratio is fed from the top of the preheater 5 toward the cement kiln 6 (step #6). In this case, the amount of air pollutants contained in the exhaust gas can be suppressed. Note that even after the mixing ratio is adjusted, the evaluation value Y continues to be equal to or lower than the reference threshold value Yr If it exceeds this value (No in step #5), the mixing ratio is adjusted again, and steps #3 to #5 are then repeated.

[0084] According to the above method, the evaluation value Y is set to a reference threshold Y r In step #7, the proportion of the second cement raw material C2 is reduced, which means that the consumption rate of the second cement raw material C2 is reduced, in order to: If the second cement raw material C2 is a waste product, there may be limitations on the amount of waste that can be accepted at the cement plant.

[0085] Therefore, when it is necessary to ensure a certain degree of consumption rate of the second cement raw material C2 (Yes in step #8), at least a part of the remaining second cement raw material C2 not used in producing the third cement raw material C0 may be fed from the bottom of the preheater 5 toward the cement kiln 6 (step #9). In the cement manufacturing apparatus shown in Fig. 3 as an example, the second cement raw material C2 may be fed toward the cement kiln 6 from the raw material feeding port 22.

[0086] Unlike the upper part of the preheater 5, the bottom part of the cement kiln 6 is subjected to an extremely high temperature environment. Therefore, even if the second cement raw material C2 is made of a material with a relatively high organic content, such as waste, when heated in such a high-temperature environment, most of the organic matter contained in the second cement raw material C2 is oxidized and decomposed into CO2, and the amount of substances that cause air pollution is low or almost not generated. Therefore, by feeding a part of the second cement raw material C2 from the lower part of the preheater 5 toward the cement kiln 6, it is possible to increase the consumption rate of the second cement raw material C2 while suppressing the generation of air pollutants derived from the second cement raw material C2.

[0087] From the viewpoint of thermal efficiency, it is not preferable to feed all of the raw materials from the lower part of the preheater 5. According to the above method, the cement raw material (third cement raw material C0) is fed from the upper part of the preheater 5 within a range in which the problem of the amount of generated air pollutants contained in the exhaust gas does not become apparent, so that cement clinker can be produced without a significant decrease in thermal efficiency. Furthermore, when there is a reason to increase the consumption rate of the second cement raw material C2, at least a portion of the remaining second cement raw material C2 that was not used in producing the third cement raw material C0 can be fed from the lower part of the preheater 5, thereby increasing the consumption rate of the second cement raw material C2 while suppressing the amount of generated air pollutants. EXAMPLES

[0088] The method according to the present invention will be described in detail below with reference to examples. However, the following examples are merely illustrative and the present invention is not limited to the following examples.

[0089] (Verification 1: Measurement of organic matter amount) Seven different types of raw materials (hereinafter referred to as "Raw Material R1" to "Raw Material R7") were subjected to ignition loss tests using an electric furnace under the temperature conditions of 600°C as the first temperature T1 and 250°C as the second temperature T2 in accordance with JIS A 1226:2020. The equipment used in the tests is as follows:

[0090] Electric furnace: Motoyama tabletop high-speed heating electric furnace, S7-2035-OP Crucible: Alumina, capacity 30mL Crucible tongs: Total length 210mm, width 95mm Electronic balance: A&D, GR-202

[0091] (i) The weight of the crucible was measured to the nearest 0.001 g. (ii) Raw material R1, whose particle size had been adjusted to 150 μm or less and dried at 105° C., was measured to the nearest 2 g and 0.001 g. (iii) The electric furnace was turned on and heated to a predetermined temperature (here, the first temperature T1 = 600°C). (iv) The crucible containing the raw material R1 was placed in an electric furnace using crucible tongs and ignited for 1 hour. (v) After the ignition was stopped, the electric furnace was left open for about 10 minutes. Then, the crucible was removed from the electric furnace using crucible tongs and left at room temperature for several minutes. (vi) The crucible was transferred to a desiccator and left to stand until it reached approximately room temperature. After that, the total weight of the crucible containing the raw material R1 was measured to the nearest 0.001 g. (vii) The above steps (i) to (vi) were repeated until the measured value in (vi) reached a constant weight. (viii) Based on the difference between the measurement value of (vi) above at which the weight has reached a constant weight and the sum of the measurement values ​​of (i) and (ii) above, the ignition loss I of the raw material R1 at the first temperature T1 is calculated. 1a was calculated.

[0092] Ignition loss I of raw material R1 at second temperature T2 1b The organic content O1 of the raw material R1 was calculated by the same procedure as that for calculating the ignition loss at the first temperature T1. 1a Loss on ignition I at the second temperature T2 1b It was calculated by subtracting (O1 = I 1a -I 1b ).

[0093] The ignition losses of the other raw materials R2 to R7 were calculated in the same manner as for raw material R1. The results are shown in Table 1. In Table 1, the relative ratio of ignition loss and the relative ratio of organic content of each raw material Ri (i = 1 to 7) calculated by the following formula are shown as the measurement results. Relative ratio of ignition loss of each raw material Ri = ignition loss of each raw material Ri / organic matter amount of raw material R1 Relative ratio of organic content of each raw material Ri = Organic content of each raw material Ri / Organic content of raw material R1

[0094] [Table 1]

[0095] (Verification 2: Estimation of organic matter amount and loss on ignition) Next, the amount of organic matter in each of the raw materials S1 to S19 obtained by mixing the other raw materials (raw materials R2 to R7) with the raw material R1 in a specified ratio was estimated based on the calculation of the above formula (1). The mixing conditions and the estimation results are shown in Table 2. However, since raw material S1 is raw material R1 with no other raw materials mixed therein, it is substantially the same as raw material R1.

[0096] In Table 2, the "mixing ratio" is a value expressed as a percentage. The estimated values ​​of the organic matter amount of raw materials S1 to S19 are expressed as relative values ​​based on the organic matter amount of raw material R1 shown in Table 1 (the organic matter amount of raw material S1). The numerical values ​​in parentheses next to each of raw materials R1 to R7 are the organic matter amounts shown in Table 1.

[0097] [Table 2]

[0098] In addition, for each of the raw materials S1 to S19, an estimated value of the ignition loss at the first temperature T1 (=600°C) was calculated based on the above formula (1). That is, the ignition loss I 0a is the ignition loss I of the first cement raw material C1 at the first temperature T1. 1a , the blending ratio U1 of the first cement raw material C1, and the ignition loss I of the second cement raw material C2 at the first temperature T1 2a The results are shown in Table 3.

[0099]

number

[0100] [Table 3]

[0101] In Table 3, "blending ratio" is a value expressed as a percentage. The estimated ignition loss at 600°C for raw materials S1 to S19 is expressed as a relative value based on the organic matter amount of raw material R1 shown in Table 1. The numerical value in parentheses for each raw material R1 to R7 is the ignition loss at 600°C value shown in Table 1.

[0102] In addition, the estimated values ​​of ignition losses at 600°C for raw materials S1 to S19 shown in Table 3 correspond to the estimated values ​​of the organic matter amounts of raw materials S1 to S19 when the estimated values ​​of ignition losses at 600°C are used as the estimated values ​​of the organic matter amounts of raw materials S1 to S19.

[0103] (Verification 3: Evaluation of the concentration of air pollutants contained in the exhaust gas from heated mixed raw materials) Next, raw materials S1 to S19 shown in Tables 2 and 3 were heated in a test kiln simulating an actual cement kiln, the resulting exhaust gas was collected, and the concentrations of air pollutants contained in the exhaust gas were measured.

[0104] Fig. 4 is a block diagram showing a schematic configuration of an evaluation combustion system including a test kiln. In Fig. 4, the flow of solids such as raw materials is shown by a dashed line, and the flow of gases such as exhaust gas is shown by a dashed line.

[0105] The evaluation combustion system 30 includes a test kiln 31, an exhaust duct 32, and a cyclone 36. The internal space of the test kiln 31 is heated by a burner 33. A cyclone 36 simulating a preheater and an exhaust duct 32 are attached to the upstream side (bottom side) of the test kiln 31. A conveyor 34 is installed above the exhaust duct 32, and raw materials supplied from a raw material storage section 35 can be fed from the top of the preheater through the conveyor 34 toward the test kiln 31. A conveyor 47 is installed on the bottom side of the test kiln 31, and raw materials supplied from a raw material storage section 48 can be fed from the bottom side of the test kiln 31, in other words, from the bottom of the preheater, toward the test kiln 31 through the conveyor 47.

[0106] The evaluation combustion system 30 includes a treatment system for treating the exhaust gas discharged from the cyclone 36. This treatment system includes a cooling tower 37, a bag filter 38, a bag filter 39, a suction fan 42, and a chimney 43. The exhaust gas discharged from the cyclone 36 passes through the cooling tower 37 to be cooled, and then passes through the bag filter 38 to remove dust contained in the exhaust gas.

[0107] Activated carbon from an activated carbon feeder 41 is supplied to the exhaust gas that has passed through the bag filter 38, and some of the components contained in the exhaust gas are adsorbed and removed. The exhaust gas then passes through a bag filter 39, whereupon dust containing activated carbon is removed, after which the exhaust gas is sent to a chimney 43 via a suction fan 42 and released from the chimney 43 into the outside air.

[0108] Test kiln 31 was used with the following specifications: Kiln length: 8,340mm Aspect ratio(L / D): 18.5 ·Fuel used: JIS Class 1 A heavy oil Tilt: 5.0% (2.86°)

[0109] A test was conducted in which each of the raw materials S1 to S19 was supplied from the raw material storage section 35, and was charged into the test kiln 31 from above the preheater through the conveyor 34, and was fired in the test kiln 31. The test conditions were as follows.

[0110] Raw material input: 100kg / h ·Filling rate: 10% ·Heavy oil burning amount: 35L / h~40L / h Firing temperature in test kiln 31: 1,450℃~1,500℃

[0111] The exhaust gas generated when each of the raw materials S1 to S19 was heated under the above conditions was collected in the collection section 52 through the extraction pipe 51 arranged after the bag filter 38. The toxic equivalent of dioxins (DXNs) contained in the collected exhaust gas was measured using a method in accordance with the "Manual for Simple Measurement of Dioxins in Exhaust Gas, Soot and Cinders (Instrumental Analysis Method)" (Dioxin Countermeasures Office, General Affairs Division, Water and Air Environment Bureau, Ministry of the Environment, March 2010). The results are shown in Table 4.

[0112] The estimated organic matter amounts of raw materials S1 to S19 in Table 4 are the same as those shown in Table 2, and the estimated ignition losses at 600°C for raw materials S1 to S19 are the same as those shown in Table 3. The measured toxic equivalents of DXNs in raw materials S1 to S19 in Table 4 are the measured toxic equivalents of DXNs in the exhaust gas obtained by heating each of the raw materials S1 to S19 [ng-TEQ / Nm 3 ] is calculated by dividing the measured value of the toxic equivalent of DXNs in the exhaust gas obtained by heating the raw material S1 [ng-TEQ / Nm 3 ] is expressed as a relative value based on the standard.

[0113] [Table 4]

[0114] 5 to 6 are graphs plotting the correspondence between the estimated values ​​shown in Table 4 and the actual measured values ​​of the toxic equivalent of DXNs in the exhaust gas. FIG. 5 is a graph plotting the correspondence between the estimated value of the organic matter amount of each raw material and the actual measured value of the toxic equivalent of DXNs in the exhaust gas. FIG. 6 is a graph plotting the correspondence between the estimated value of the ignition loss of each raw material at 600 ° C. and the actual measured value of the toxic equivalent of DXNs in the exhaust gas. In other words, FIG. 6 corresponds to a graph plotting the correspondence between the estimated value of the organic matter amount of each raw material and the actual measured value of the toxic equivalent of DXNs in the exhaust gas when the estimated value of the ignition loss of each raw material at 600 ° C. is used as the estimated value of the organic matter amount of each raw material.

[0115] According to Table 4 and Figure 5, it was confirmed that when the estimated amount of organic matter in the raw material exceeds a certain value (here, 1.1), the DXNs concentration in the exhaust gas generated when the raw material is heated rises sharply. The reason for this is presumably that there is a limit to the total amount of organic matter in the raw material that can be oxidized and decomposed under the atmosphere above the preheater (the atmosphere in the cyclone 36 in Figure 4), and when an amount of organic matter exceeding this limit is fed, the incomplete combustion of the organic matter accelerates, causing an explosive increase in the amount of precursor substances of DXNs generated.

[0116] The results in Table 4 and Figure 5 suggest that the concentration of air pollutants in the exhaust gas can be controlled by controlling the amount of organic matter in the raw material to a specified value or less.

[0117] Also, according to Table 4 and Figure 6, it was confirmed that when the estimated ignition loss of the raw material at 600°C exceeds a predetermined value (here, 1.4), the DXNs concentration in the exhaust gas generated when the raw material is heated rises sharply. The reason is presumed to be the same as above. This result suggests that the concentration of air pollutants in the exhaust gas can be controlled by controlling the ignition loss of the raw material at 600°C to a predetermined value or less, in other words, by controlling the amount of organic matter in the raw material estimated by the ignition loss of the raw material at 600°C to a predetermined value or less.

[0118] Here, the value of 600°C is a value simulating a first temperature T1 close to the temperature of the exhaust gas passing through the upper part of the preheater. In other words, the temperature at which the ignition loss is measured is not limited to 600°C, and may be any temperature within the range of 400°C to 700°C, more preferably within the range of 400°C to 650°C, and particularly preferably within the range of 450°C to 600°C.

[0119] However, when the raw materials contain a substance containing water of crystallization, the ignition loss of the raw materials at 600°C reflects the amount of the water of crystallization in addition to the amount of organic matter contained in the raw materials. According to the results of Figures 5 to 6, it can be said that the concentration of air pollutants in the exhaust gas can be controlled by the value of the amount of organic matter in the raw materials estimated from the value of the ignition loss of the raw materials at a first temperature T1 close to the temperature of the exhaust gas passing through the upper part of the preheater. However, from the viewpoint of improving accuracy, it is preferable to control the concentration of air pollutants in the exhaust gas by the value of the amount of organic matter in the raw materials estimated based on the ignition loss of the raw materials at the first temperature T1 and the ignition loss of the raw materials at a second temperature T2, which is a temperature at which the organic matter contained in the first cement raw material C1 is unlikely to volatilize and at which the water of crystallization contained in the first cement raw material C1 is desorbed.

[0120] (Verification 4: Evaluation of the effect of feeding the blended raw materials from the bottom of the preheater on the concentration of air pollutants in the exhaust gas) Next, for six types of mixed raw materials (S13, S15, S16, S17, S18, S19) whose estimated organic matter amount (relative value) was 1.1 or more in Tables 2 and 4, tests were conducted in which the mixed raw materials were burned in the test kiln 31 in the same manner as above, while maintaining the mixing ratio of each mixed raw material and varying the feeding points of the base raw material and the blended raw materials. According to Verification 3, these mixed raw materials have a high amount of organic matter and generate a relatively large amount of air pollutants when heated.

[0121] In detail, of the mixed raw materials (S13, S15, S16, S17, S18, S19), the base raw material R1 was fed from the raw material storage section 35 through the conveyor 34 to the test kiln 31 from the top of the preheater, and the mixed raw materials (R5, R6, R7) were fed from the raw material storage section 48 through the conveyor 47 to the test kiln 31 from the bottom of the preheater. In other words, in this verification 4, the mixed raw materials were not fed from the same place, but each raw material was fed from a different place, and the raw materials were heated in a mixed state in the test kiln 31. The conditions are as shown in Table 5 below. In Table 5, the numerical values ​​in parentheses along with each raw material (R1, R5, R6, R7) are the organic matter amounts shown in Table 1.

[0122] [Table 5]

[0123] For example, level K13 is similar to raw material S13 in Table 3 in the sense that it is raw material fed to the test kiln 31, and 85% of base raw material R1 and 15% of blended raw material R5 are mixed. However, in this level K13, the base raw material R1 is fed to the test kiln 31 from the top of the preheater, and the blended raw material R5 is fed to the test kiln 31 from the bottom of the preheater, which is different from the verification using raw material S13 shown in Table 3. The same is true for the other levels K15 to K19.

[0124] For these levels K13 and K15 to K19, exhaust gas was extracted in the same manner as in Verification 3, which obtained the results in Table 4, and the toxic equivalent of DXNs contained in the exhaust gas was measured. The results are shown in Table 6. For comparison, Table 6 also shows the measurement results (see Table 4) when mixed raw materials corresponding to each level (S13, S15, S16, S17, S18, S19) were fed into the test kiln 31 from above the preheater.

[0125] [Table 6]

[0126] From Table 6, it was confirmed that when the base raw material R1 and the mixed raw materials (R5, R6, R7) containing a higher organic matter content than the base raw material R1 are heated in the test kiln 31, the DXNs concentration in the exhaust gas is significantly lower when the mixed raw materials (R5, R6, R7) are charged from the bottom of the preheater (b) than when the mixed raw materials of the base raw material and the mixed raw materials are charged from the top of the preheater all at once (a), regardless of the raw material composition and the mixing ratio. This shows that by charging the second cement raw material C2, which contains a higher organic matter content such as waste, from the bottom of the preheater in step #9, the generation of air pollutants can be suppressed while the consumption rate of the second cement raw material C2 can be increased. [Explanation of symbols]

[0127] 1: Cement manufacturing equipment 5: Preheater 5a, 5b, 5c, 5d, 5e: Cyclone 6: Cement kiln 7: Burner 21: Raw material input port 22: Raw material input port 30: Evaluation combustion system 31: Test kiln 32: Exhaust duct 33: Burna 34: Conveyor 35: Raw material storage section 36: Cyclone 37: Cooling tower 38: Bag filter 39: Bag filter 41:Activated carbon charging device 42: Suction fan 43: Chimney 47: Conveyor 48: Raw material storage section 51: Air extraction pipe 52: Collection Department

Claims

1. A step (a) of preparing information on a first organic matter amount, which is an amount of organic matter contained in a first cement raw material, and information on a second organic matter amount, which is an amount of organic matter contained in a second cement raw material made of a material different from the first cement raw material; a step (b) of estimating a third organic matter amount, which is an organic matter amount contained in a third cement raw material obtained by mixing the first cement raw material and the second cement raw material, by calculation based on a mixing ratio of the first cement raw material and the second cement raw material, the first organic matter amount, and the second organic matter amount; and (c) comparing an evaluation value based on the third organic matter amount with a predetermined threshold value, and if the evaluation value is equal to or less than the predetermined threshold value, adding the third cement raw material from an upper part of a preheater attached to a cement kiln.

2. 2. The method of claim 1, wherein in the step (c), when the evaluation value exceeds the predetermined threshold value, the mixing ratio is changed so that the evaluation value becomes equal to or less than the predetermined threshold value, and then the third cement raw material is charged from an upper part of the preheater.

3. the second organic amount is higher than the first organic amount; In the step (c), when the evaluation value exceeds the predetermined threshold value, the mixing ratio is changed by decreasing a relative ratio of the second cement raw material to the first cement raw material so that the evaluation value is equal to or less than the predetermined threshold value, and then the third cement raw material is charged from an upper portion of the preheater; 3. The method of claim 2, further comprising the step (d) of feeding the second cement raw material from a lower portion of the preheater.

4. The first cement raw material is a blended raw material blended in a raw material step, 4. The method of claim 3, wherein the second cement raw material is a waste material.

5. The step (a) (a1) measuring ignition losses of the first cement raw material and the second cement raw material at a first temperature corresponding to a heating environment in an upper portion of a preheater attached to a cement kiln; and (a2) deriving the first organic matter amount based on an ignition loss of the first cement raw material at the first temperature, and deriving the second organic matter amount based on an ignition loss of the second cement raw material at the first temperature.

6. 6. The method of using a cement raw material according to claim 5, wherein in the step (a2), an ignition loss of the first cement raw material at the first temperature is set as the first organic matter amount, and an ignition loss of the second cement raw material at the first temperature is set as the second organic matter amount.

7. The step (a) further includes a step (a3) ​​of measuring the ignition loss of the first cement raw material and the second cement raw material at a second temperature higher than 100° C. and lower than the first temperature; 6. The method of using a cement raw material according to claim 5, wherein the step (a2) determines the first organic matter amount based on a difference between an ignition loss at the first temperature and an ignition loss at the second temperature of the first cement raw material, and determines the second organic matter amount based on a difference between an ignition loss at the first temperature and an ignition loss at the second temperature of the second cement raw material.

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