Cement combination grinding system and grinding process

Abstract

The application discloses a cement combination grinding system and grinding process. The application produces uniform standard clinker powder through the combination grinding production mode, controls the fineness of the clinker powder according to the exertion degree of the clinker strength, and efficiently utilizes the clinker resources. On the other hand, the application produces various kinds of mixed material (low-activity mixed material) powder, controls the particle composition of the mixed material powder according to the characteristics of the mixed material, and stores the mixed material powder respectively. According to the individualized requirements of the cement varieties, performance and the like, the clinker powder and the various kinds of mixed material powder are metered and proportioned at the bottom of a semi-finished product warehouse, and are sent into a cement terminal grinding mechanism to perform particle shaping, so as to ensure the circularity, adjust the width and narrowness of the particle distribution, and produce different varieties of high-quality cement with good homogeneity and small standard deviation.

Description

Technical Field

[0001] This invention relates to the field of cement production technology, specifically a cement combined grinding system and grinding process. Background Technology

[0002] Traditional cement production methods typically employ a mixed grinding approach, where all raw materials are pre-mixed and fed together into a grinding system (roller press pre-grinding system + ball mill system). The grinding system achieves the required fineness after one or more cycles. This method has the following problems: materials that are easier to grind are ground finer, while materials that require fine grinding but are difficult to grind, such as clinker and slag, are not easily ground. Industry reports have clearly proposed a scientific cement composition, which involves grinding materials with cementing properties, such as clinker and slag, to a sufficiently fineness to reduce resource waste. In particular, the clinker preparation process not only consumes energy but also generates significant carbon emissions; approximately 850 kg of CO2 is emitted for every ton of clinker produced. Saving 1% of clinker per ton of cement can reduce CO2 emissions by 8.50 kg and save 3-4 yuan in costs. Therefore, the efficient utilization of clinker has significant social and economic benefits in reducing CO2 emissions and conserving resources. Summary of the Invention

[0003] The purpose of this invention is to provide a cement combined grinding system and grinding process to solve the problems mentioned in the background art. It controls the particle size distribution of clinker and admixtures according to the characteristics of the raw materials, fully grinding active materials such as clinker to the required particle size range. Difficult-to-grind admixtures act as coarse aggregates in the cement, while easily ground admixtures act as fine aggregates, resulting in a more rational particle size distribution in the finished cement, efficient utilization of valuable clinker resources, improved cement workability and quality stability, reduced clinker waste, and lower carbon emissions and production costs per ton of cement.

[0004] To achieve the above objectives, the present invention provides the following technical solution:

[0005] This invention discloses a cement combined grinding system, comprising a blending material grinding mechanism, a clinker grinding mechanism, a batching mechanism, and a cement final grinding mechanism; wherein:

[0006] The batching mechanism includes a coarse mixed material powder silo, a fine mixed material powder silo, and a clinker powder silo. The feed ends of the coarse mixed material powder silo and the fine mixed material powder silo are connected to the mixed material grinding mechanism, and the discharge ends are connected to the cement final grinding mechanism. The feed end of the clinker powder silo is connected to the clinker grinding mechanism, and the discharge end is connected to the cement final grinding mechanism.

[0007] As a further aspect of the present invention: the mixed material grinding mechanism includes a first roller pressing unit, a first powder classifier, and a first dust collection unit connected in sequence; the first powder classifier includes a first airflow separator, a first high-efficiency powder classifier, and a first cyclone dust collector connected in sequence; wherein, the return port of the first airflow separator is connected to the first roller pressing unit, and the discharge port of the first high-efficiency powder classifier is connected to the inlet of the coarse mixed material powder silo; the discharge port of the first cyclone dust collector is connected to the inlet of the fine mixed material powder silo; the first dust collection unit includes a first fan and a first bag filter connected to the dust emission port of the first cyclone dust collector; the discharge end of the first bag filter is connected to the inlet of the fine mixed material powder silo.

[0008] As a further aspect of the present invention: the clinker grinding mechanism includes a second roller pressing unit, a second powder classifier, a ball milling unit, and a third powder classifier connected in sequence; wherein, the second powder classifier includes a second air classifier, a second high-efficiency powder classifier, and a second cyclone dust collector connected in sequence; the return ports of the second air classifier and the second high-efficiency powder classifier are both connected to the second roller pressing unit; the discharge end of the second cyclone dust collector is connected to the ball milling unit.

[0009] As a further aspect of the present invention: the third powder classifier unit includes an O-sepa powder classifier, a third bag filter, and a third fan connected in sequence; the discharge end of the third bag filter is connected to the clinker powder silo; it also includes a fourth bag filter and a third fan connected to the ball mill unit.

[0010] As a further aspect of the present invention: the clinker grinding mechanism further includes a second dust collection unit; the second dust collection unit includes a second fan and a second bag dust collector connected to the dust outlet of the second cyclone dust collector; the discharge end of the second bag dust collector is connected to the ball milling unit.

[0011] As a further aspect of the present invention, the batching mechanism further includes a first weighing scale located below the coarse mixed material powder silo, a second weighing scale located below the fine mixed material powder silo, and a third weighing scale located below the clinker powder silo.

[0012] As a further aspect of the present invention: the cement final grinding mechanism includes a finished product ball mill, a fourth bag dust collector, and a fourth fan.

[0013] Another aspect of the present invention discloses a grinding process for a cement combined grinding system as described in any of the preceding claims, comprising the following steps:

[0014] S1. Preparation of mixed materials with different fineness: Based on the grindability of various mixed materials, coarse powder, fine powder and ultrafine powder are prepared respectively and sent to the coarse mixed material powder silo and the fine mixed material powder silo for later use.

[0015] S2. Clinker powder is prepared by a combined grinding system of roller press pre-grinding and ball mill grinding. The particle size control of clinker powder is adjusted according to the degree of clinker strength. When the cost reduction of saving clinker amount is greater than the cost increase of power consumption, the particle size of clinker powder can be controlled as fine as possible.

[0016] S3. The mixed material powders of different particle sizes prepared in step S1 and the clinker powder prepared in step S2 are respectively sent to the clinker powder silo for later use. According to the different types of cement produced, the amount of clinker powder and mixed material powder is controlled by a metering scale in the batching mechanism and sent together to the cement final grinding mechanism.

[0017] S4. In the cement final grinding unit, mixed material powder and clinker powder of different particle sizes are fed together into the ball mill for particle shaping, and the particle distribution width is adjusted to produce different varieties of high-quality cement, which are then sent to different cement silos for storage.

[0018] Compared with the prior art, the beneficial effects of the present invention are:

[0019] This invention produces standardized clinker powder through a combined grinding process, rationally controlling the fineness of the clinker powder according to cement quality requirements, thus efficiently utilizing clinker resources. Simultaneously, it produces various types of blended material powder (low-activity blended materials), controlling the particle composition of each blended material powder based on its characteristics, and storing them separately. According to the individualized requirements of cement type and performance, clinker powder and various blended material powders are metered and batched at the bottom of the semi-finished product silo, then fed into the cement terminal grinding unit for particle shaping, ensuring roundness, adjusting particle size distribution, resulting in cement with good homogeneity and small standard deviation, producing high-quality cement of different varieties. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure of the present invention;

[0021] Figure 2 This is a process flow diagram of the present invention;

[0022] In the diagram: 1-First steady-flow weighing bin, 2-First roller press, 3-First cake elevator, 4-First air classifier, 5-First high-efficiency classifier, 6-First cyclone dust collector, 7-First circulating fan, 8-First bag dust collector, 9-First fan, 10-First inclined chute, 11-Second inclined chute, 12-Second steady-flow weighing bin, 13-Second roller press, 14-Second cake elevator, 15-Second air classifier, 16-Second high-efficiency classifier, 17-Second cyclone dust collector, 18-Second circulating fan, 19-Second bag dust collector, 20-Second fan, 21-Third inclined chute, 22-Clinker ball mill. 23-Fourth Inclined Sluice, 24-Grinding Tail Elevator, 25-Fifth Inclined Sluice, 26-O-Sepa Air Classifier, 27-Third Bag Filter, 28-Third Fan, 29-Sixth Inclined Sluice, 30-Fourth Bag Filter, 31-Third Fan, 32-Coarse Mixed Material Powder Silo, 33-Fine Mixed Material Powder Silo, 35-Clinker Powder Silo, 35-First Measuring Scale, 36-Second Measuring Scale, 37-Third Measuring Scale, 38-Seventh Inclined Sluice, 39-Third Cake Elevator, 40-Cement Ball Mill, 41-Eighth Inclined Sluice, 42-Fourth Cake Elevator, 43-Ninth Inclined Sluice, 44-Fourth Bag Filter, 45-Fourth Fan. Detailed Implementation

[0023] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] In the description of this invention, it should be noted that the terms "upper," "lower," "left," "right," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of the invention is in use. They are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. In addition, the terms "first," "second," and "third," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0025] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or a communication connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0026] Please see Figure 1-2 In an embodiment of the present invention, a cement grinding system includes a blending material grinding mechanism, a clinker grinding mechanism, a batching mechanism, and a cement final grinding mechanism, wherein:

[0027] The mixed material grinding mechanism includes a first steady flow weighing bin 1, a first roller press 2, a first cake elevator 3, a first air classifier 4, a first high-efficiency powder classifier 5, a first cyclone dust collector 6, a first circulating fan 7, a first bag dust collector 8, a first fan 9, a first inclined chute 10, and a second inclined chute 11. The mixed material raw material is fed into the first steady flow weighing bin 1 by a belt conveyor, and then enters the first roller press 2 for crushing. The crushed material is lifted by the first cake elevator 3 and then sent to the first air classifier 4 for primary sorting. The coarse powder is returned to the first steady flow weighing bin 1 for cyclic crushing, and the fine powder enters the first high-efficiency powder classifier 5 with the airflow for secondary sorting. The sorted coarse mixed material powder enters the coarse mixed material powder silo 32 through the first inclined chute 10 for storage. The fine mixed material powder enters the cyclone dust collector 6 with the airflow for collection and then enters the fine mixed material powder silo 33 through the second inclined chute 11 for storage. The powder collected by the first bag dust collector 8 of the system venting also enters the fine mixed material powder silo 33 through the second inclined chute 11 for storage. The clean air is discharged into the atmosphere by the first fan 9. The particle size of the mixed material powder is adjusted and controlled by adjusting the rotation speed of the first high-efficiency air classifier 5 and the rotation speed of the first blower 9. The particle size control requirement for fine mixed material powder is ≤5% residue on an 80μm sieve, and the particle size control requirement for coarse mixed material powder is 25% to 35% residue on an 80μm sieve.

[0028] The clinker grinding mechanism includes a second steady-flow weighing bin 12, a second roller press 13, a second cake elevator 14, a second air classifier 15, a second high-efficiency classifier 16, a second cyclone dust collector 17, a second circulating fan 18, a second bag dust collector 19, a second fan 20, a third inclined chute 21, a clinker ball mill 22, a fourth inclined chute 23, a mill tail elevator 24, a fifth inclined chute 25, an O-sepa classifier 26, a third bag dust collector 27, a third fan 28, a sixth inclined chute 29, a fourth bag dust collector 30, and a third fan 31. Clinker is conveyed by a belt conveyor into the second steady-flow weighing bin 12, and then into the second roller press 13 for crushing. The crushed material is lifted by the second cake elevator 14 and then sent to the second air classifier 15 for primary sorting. The coarse powder is returned to the second steady-flow weighing bin 12 for cyclic crushing, while the fine powder is carried by the airflow into the second high-efficiency air classifier 16 for secondary sorting. The coarse powder after secondary sorting is also returned to the second steady-flow weighing bin 12 for cyclic crushing. The clinker fine powder is carried by the airflow into the second cyclone dust collector 17 for collection, and then conveyed through the third inclined chute 21 into the clinker ball mill 22 for further grinding. The clinker fine powder carried out of the outlet of the cyclone dust collector 17 is collected by the second bag dust collector 19. The clinker powder is fed into the clinker ball mill 22 via the third inclined chute 21 for further grinding. The discharged clinker powder is then conveyed to the O-sepa classifier 26 via the fourth inclined chute 23, the mill tail elevator 24, and the fifth inclined chute 25. Clinker powder of the selected fineness is collected by the airflow into the third bag filter 27 and then sent to the clinker powder storage silo via the sixth inclined chute 29 for later use. Clean air is discharged into the atmosphere via the third fan 28. Internal ventilation of the clinker ball mill 22 is achieved through the fourth bag filter 30 and the third fan 31. The clinker powder collected by the fourth bag filter 30 is also sent to the clinker powder storage silo 34 via the sixth inclined chute 29 for later use, and clean air is discharged into the atmosphere via the third fan 31. The particle size control requirement for the clinker powder is ≤6% residue on a 45μm sieve.

[0029] The batching mechanism includes a coarse blended material powder silo 32, a fine blended material powder silo 33, a clinker powder silo 34, a first weighing scale 35, a second weighing scale 36, a third weighing scale 37, and a seventh inclined chute 38. Depending on the type of cement being produced, clinker powder and blended material powders of different fineness are weighed and batched proportionally at the bottom of the silos. The coarse blended material powder is weighed by the first weighing scale 35, the fine blended material powder by the second weighing scale 36, and the clinker powder by the third weighing scale 37. The batched mixture is then conveyed together through the seventh inclined chute 38 into the cement final grinding mechanism.

[0030] The cement final grinding mechanism includes a third cake elevator 39, a cement ball mill 40, an eighth inclined chute 41, a fourth cake elevator 42, a ninth inclined chute 43, a fourth bag filter 44, and a fourth fan 45. The batch material from the semi-finished product storage system is fed into the third cake elevator 39 via the seventh inclined chute 38, and then lifted by the third cake elevator 39 before being fed into the cement ball mill 40 for further grinding. The finished cement exiting the mill is sequentially fed into the finished cement storage system via the eighth inclined chute 41, the fourth cake elevator 42, and the ninth inclined chute 43. Internal ventilation of the cement ball mill 40 is achieved through the fourth bag filter 44 and the fourth fan 45. The finished cement collected by the fourth bag filter 44 is fed into the finished cement storage system via the ninth inclined chute 43.

[0031] The process of this system during operation is as follows:

[0032] Different particle sizes of blended material powder are prepared through a blended material grinding mechanism. Based on the grindability of various blended materials, coarse and fine blended material powders are obtained and sent to the corresponding powder silos in the batching mechanism for later use. Clinker powder is prepared using a combined grinding system of roller pressing unit pre-grinding + ball mill grinding. The particle size of the clinker powder is adjusted according to the degree of efficient clinker utilization. When the cost reduction due to clinker saving is greater than the cost increase due to power consumption, the clinker powder particle size can be controlled as fine as possible. The clinker powder is sent to the clinker powder silo in the batching mechanism. Depending on the type of cement produced, the amount of clinker powder and blended material powder is controlled by the metering scale at the bottom of different powder silos and sent together into the cement grinding system. Blended material powder and clinker powder of different particle sizes are fed together into the cement ball mill 40 for particle shaping to ensure roundness and adjust particle distribution width, producing different types of high-quality cement, which are then sent to different cement silos for storage.

[0033] At the Huangma Cement Plant in Meizhou, Guangdong, the advantages of the combined grinding production method over the traditional combined grinding production method before the transformation in terms of clinker utilization are summarized as follows:

[0034] 1. Comparison of strength of M32.5 masonry cement with different grinding methods

[0035]

[0036]

[0037] With the use of low-activity blended materials, the clinker consumption was significantly reduced after the modified combined grinding process, saving 7 percentage points. This is a clear advantage compared to the conventional combined grinding process before the modification. At the same time, the workability of the cement produced by the modified combined grinding process is improved (the consistency remains unchanged after 30 minutes, and the water slurry does not separate), resulting in higher market acceptance.

[0038] 2. Comparison of strength of Real Madrid P.042.5 iron standard cement by different grinding methods

[0039]

[0040] The comparison in the table above reveals that, for the production of P.O42.5 iron standard cement using combined grinding, the customer requires a specific heat control of ≤350m³ to control the heat of hydration. 2 / kg, in practice it is generally controlled at 330-340m 2 / kg, using combined grinding, the clinker consumption is reduced by about 8%, which is also the lowest in the local industry, showing obvious advantages.

[0041] 3. Strength Comparison of Real Madrid P.042.5R Cement with Different Grinding Methods

[0042]

[0043] The comparison in the table above reveals that for P.O42.5R bulk cement produced by combined grinding, the Guangdong market has relatively high requirements for early strength, with customers requiring a concrete strength of ≥350m. 2 / kg, in practice generally controlled at 370-380m 2 / kg, without adding any highly active admixtures, combined grinding saves 5 percentage points of clinker consumption compared to traditional combined grinding, and market feedback indicates that the admixtures have good compatibility and high stability.

[0044] The three varieties listed above demonstrate the significant advantages of the new combined grinding technology. It reduces clinker consumption by 5-8 percentage points, efficiently utilizes valuable clinker resources, and improves cement workability and quality stability. After adopting combined grinding technology, Huangma Company's annual cement production reached 3 million tons, saving approximately 180,000 tons of clinker annually, resulting in an average cost saving of 25 yuan per ton of cement and an increase in annual profit of 75 million yuan. Based on a CO2 emission of 850 kg per ton of clinker, combined grinding reduces CO2 emissions by approximately 50 kg per ton of cement.

[0045] Although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

[0046] Therefore, the above description is only a preferred embodiment of this application and is not intended to limit the scope of this application; that is, all equivalent modifications made in accordance with the scope of the claims of this application shall be within the protection scope of the claims of this application.

Claims

1. A cement combined grinding system, comprising a mixed material grinding mechanism, a clinker grinding mechanism, a batching mechanism and a cement final grinding mechanism; characterized in that: the batching mechanism comprises a coarse mixed material powder bin (32), a fine mixed material powder bin (33) and a clinker powder bin (34), wherein the feeding end of the coarse mixed material powder bin (32) and the fine mixed material powder bin (33) is connected with the mixed material grinding mechanism, and the discharging end is connected with the cement final grinding mechanism; the feeding end of the clinker powder bin (34) is connected with the clinker grinding mechanism, and the discharging end is connected with the cement final grinding mechanism; the mixed material grinding mechanism comprises a first roller pressing unit, a first powder selecting unit and a first dust collecting unit connected in sequence; the first powder selecting unit comprises a first air flow classifier (4), a first high-efficiency powder classifier (5) and a first cyclone dust collector (6) connected in sequence; wherein the return port of the first air flow classifier (4) is connected with the first roller pressing unit, the discharging port of the first high-efficiency powder classifier (5) is connected with the feeding port of the coarse mixed material powder bin (32); the discharging port of the first cyclone dust collector (6) is connected with the feeding port of the fine mixed material powder bin (33); the first dust collecting unit comprises a first fan (9) and a first bag dust collector (8) connected with the dust raising port of the first cyclone dust collector (6); the discharging end of the first bag dust collector (8) is connected with the feeding end of the fine mixed material powder bin (33); the grinding process of the cement combined grinding system comprises the following steps: S1, preparing mixed materials with different finenesses; S2, preparing clinker powder by using a combined grinding system of a roller press pre-grinding and a ball mill grinding, so that the particle size of the clinker powder is controlled within a preset range; S3, the mixed materials with different particle sizes prepared in step S1 and the clinker powder prepared in step S2 are respectively sent into the coarse mixed material powder bin (32), the fine mixed material powder bin (33) and the clinker powder bin (34) for standby use; according to different cement varieties, the batching amount of the clinker powder and the mixed material powder is controlled by a batching scale in the batching mechanism, and then they are sent into the cement final grinding mechanism together; S4, in the cement final grinding mechanism, the mixed material powder and the clinker powder with different particle sizes are sent into a finished ball mill together, the particle size distribution is adjusted, different varieties of high-quality cement are produced, and then they are respectively sent into different cement storage bins for storage. The clinker grinding mechanism comprises a second roller pressing unit, a second powder selecting unit, a ball mill unit and a third powder selecting unit connected in sequence; wherein the second powder selecting unit comprises a second air flow classifier (15), a second high-efficiency powder classifier (16) and a second cyclone dust collector (17) connected in sequence; the return ports of the second air flow classifier (15) and the second high-efficiency powder classifier (16) are connected with the second roller pressing unit; the discharging end of the second cyclone dust collector (17) is connected with the ball mill unit. The third powder selecting unit comprises an O-sepa powder classifier (26), a third bag dust collector (27) and a third fan (28) connected in sequence; the discharging end of the third bag dust collector (27) is connected with the clinker powder bin (34); further comprising a fourth bag dust collector (30) and a fourth fan (31) connected with the ball mill unit. ​ ​ ​ ​ ​ 2. The cementitious composite grinding system of claim 1, wherein, ​ 3. The cementitious composite grinding system of claim 2, wherein, ​ 4. The cementitious composite grinding system of claim 2, wherein, The clinker grinding mechanism further comprises a second dust collection unit; the second dust collection unit comprises a second fan (18) and a second bag-type dust collector (19) connected with a dust emission port of a second cyclone dust collector (17); a discharge end of the second bag-type dust collector (19) is connected with the ball mill unit.

5. The cementitious composite grinding system of claim 1, wherein, The batching mechanism further comprises a first metering scale (35) arranged below the coarse mixed material powder bin (32), a second metering scale (36) arranged below the fine mixed material powder bin (33), and a third metering scale (37) arranged below the clinker powder bin (34).

6. The cementitious composite grinding system of claim 1, wherein, The cement final grinding mechanism comprises a finished product ball mill (40), a fifth bag-type dust collector (44), and a fifth fan (45).

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