Cement Production Process Research Articles

Integrating Process Re-Engineering Models in Cement Production to Improve Energy Efficiency

The demand for cement has significantly increased, growing by 8% in the year 2022 and by a further 12% in 2023. It is highly anticipated that this trend will continue, and it will result in significant growth by 2030. However, cement production is highly energy-intensive, with 70 to 80% of the total energy consumed during the clinker formation, which is the main cement production process. Minimising energy losses requires a radical approach that includes optimising the performance of the kilns and significantly improving their energy efficiency. One of the most efficient approaches to optimise the performance of the kilns and reduce energy losses is by integrating process re-engineering models, which leverage process data analytics, machine learning, and computational methods. This study employed a model-based integration approach to improve energy efficiency during clinker formation. Energy consumption data were collected from two semi-automated cement production plants. The data were analysed using a regression model in Minitab (Minitab 21.1.0) statistical software. The analysis resulted in a linear energy consumption equation that links energy consumption to both production and energy loss. Dynamic simulations and modelling using Simulink in MATLAB were performed based on a proportional–integral–derivative (PID)-controlled system. The dynamic behaviour of the model was evaluated using data from Plant A and validated with data from Plant B. The energy efficiency equation was established as a mathematical model that explains energy improvements based on incorporating parameters for the cement kiln system and disturbances from the environment.

Recycling of waste glass powder: Effects on microstructure, mechanical properties and sustainability of seashell powder calcined sludge cement

The massive accumulation of waste seashells, waste sludge and waste glass not only occupies a large amount of land resources, leading to a shortage of land resources, but also causes serious soil-water-air composite pollution over a long period of time with the role of the surrounding environment, which poses a serious hazard to the ecological environment and public health. In this study, the effect patterns of waste glass powder (WGP) on the workability, mechanical properties, microstructure and carbon emission of seashell powder calcined sludge cement (SCSC) slurries prepared using waste sludge and waste seashells as supplementary cementitious materials in place of part of the cement clinker were investigated. The hydration process and microstructure of the materials were characterized by heat of hydration tests, thermogravimetry (TG-DTG), infrared Fourier transform (FTIR), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results showed that the addition of WGP improved the fluidity of SCSC slurries and reduced the shear stress of SCSC slurries without changing the flow pattern of SCSC slurries, and all the slurries conformed to the power law model. The compressive strength of SCSC slurries increased by 25.26 % with 5 % WGP addition. The CO2 emissions per cubic meter of SCSC slurries were reduced by 4.43 %, 8.81 %, 13.5 % and 18.23 % for WGP additions of 5 %, 10 %, 15 % and 20 %, respectively. These results can provide a new way for the efficient resource utilization of waste seashells, waste sludge and waste glass, and reduce the CO2 emission during the cement production process, promoting the clean production of cement.

Rotary kiln simulation for energy recovery: The precalciner cement kiln case

Cement production process is energy intensive both in terms of the thermal and electrical energy. In fact, energy demand accounts for about 40 % of operational costs. Significant heat losses are present even in modern plants, affecting negatively both on production costs and emissions. These losses are mainly due to the sensible heat in the hot flue gases and exhaust air streams used for cooling down the clinker (35 % of the process heat losses). Given the good quality of the available sensible heat in these streams (temperatures above 280 °C), a heat recovery system can be considered to increase the overall efficiency of the cement plant. The aim of this work is to create a simplified model of a cement rotary kiln to study the heat recovery optimization. Results were consistent with the temperature, pressure and flowrates ranges indicated in the literature. The model here proposed can be adapted to simulate other processes involving a rotary kiln. As a result of the study of the proposed case scenario, the plant was found to potentially generate 3.2 kWh/ton of clinker of electricity, equivalent to approximately 20 % of the total plant electrical consumption.

Optimization Scheduling Strategy for Energy Storage and Cement Load Aggregation Considering Production Constraints

Abstract For energy-intensive cement enterprises closely related to adjustable potential and production processes, an optimization scheduling model is proposed based on the coupling relationship between tasks and materials, taking into account the production constraints of cement users. In addition, energy storage-side pumped storage is aggregated to regulate resources, further enhancing the flexibility of regulation. For pumped storage devices, the constraints include power constraints during the charging and discharging process, power equality constraints, state constraints during charging and discharging, energy state constraints, and final energy constraints. For cement enterprises, taking the example of the new dry cement production process, the generation/consumption of materials and the occupation/release of equipment in each process are analyzed. The state-task network method is used to abstract materials and processes into states and tasks respectively, establishing process constraints for cement load production. Case simulation verifies that the proposed method can effectively reduce the comprehensive electricity cost of pumped storage and cement enterprises while ensuring the normal operation of pumped storage and cement enterprises, providing data guidance and support for cement enterprises to participate in grid interaction.

A Method for Calculating the Environmental Protection Cost of Cement Plants Taking into Account the Diffusion Characteristics of Air Pollutants

Abstract In recent years, China’s installed capacity of new energy has been continuously improved, and the problem of new energy consumption has become increasingly prominent. The cement load has considerable demand response potential and can effectively help absorb new energy sources, but its high emission characteristics limit the development of the cement industry. In this context, the establishment of a systematic and refined cement load emission cost model will be of great significance to improve the wind power absorption capacity and promote the low-carbon and environmentally friendly operation of the power system. In this paper, the emission characteristics of SO2, NOx, particulate matter and CO2 from the cement load are analyzed. according to the cement production process. Then, the air pollutant emission cost of the cement plant is described from the aspects of environmental protection tax and environmental protection supplementary cost, and the carbon emission cost of the cement plant is calculated by using the laddered carbon transaction cost model, and finally the emission cost model of the cement plant is constructed.

Work Posture Analysis using the RULA and OWAS Methods in the Cement Packing Section at the Packing Plant Indarung Unit of PT. Semen Padang

PT Semen Padang is a cement manufacturer. According to preliminary observations, the cement packing process, which is done at the Packing Plant Indarung unit, is the last step of the cement production process. Due to the sideways and bowed body positions, cement bagging is performed manually with a less ergonomic working position. This is performed continuously, causing workers complaints of musculoskeletal disorders. The results of distributing the Nordic Body Map questionnaire to employees indicate that many operators experience pain due to their work positions. Based on these findings, the RULA method was used to analyze work posture, yielding a group A posture score of 7, a group B posture score of 4, and a final RULA assessment score of 7. The OWAS method assessment, meanwhile, earned a score code of 2141 and was categorized as a level 3 risk. The results of the risk assessment using the RULA method yield a score of 7, indicating that the operator's work attitude needs to change immediately, whereas the results of the assessment using the OWAS method yield a score of 3, indicating that work posture has a very significant impact on tension and needs to be corrected as soon as possible. On the basis of the results of these assessments, a recommendation was made to design a trolley work facility that can be utilized to reduce the risk of MSDs for cement packaging operators

Assessing the climate effects of clinker production: A statistical analysis to reduce its environmental impacts

Building materials and components account for about 10% of the world's anthropogenic greenhouse gas emissions. Carbonate decomposition and fuel combustion from the cement production process are responsible for almost 7% of carbon dioxide emissions. Since clinker is the most impacting component of ordinary Portland cement, this paper presents a statistical analysis of the life cycle impacts of 41 recipes of grey clinker produced in Europe from 2015 to 2023 to identify the consumption impact categories (e.g., fossil fuels, renewable and non-renewable secondary fuels) which better explain the assessment of the Global Warming Potential (GWP), typically exploited to quantify the environmental impact of clinker production. More in detail, several regression methods are applied to the available dataset to build predictive models for GWP and to determine the most relevant impact categories. The regression models are then compared with respect to their statistical accuracy and goodness of fit. The results provide information that can support cement producers in developing low-impacting cement recipes.

Evaluation and Analysis of Cement Raw Meal Homogenization Characteristics Based on Simulated Equipment Models.

In recent years, the variability in the composition of cement raw materials has increasingly impacted the quality of cement products. However, there has been relatively little research on the homogenization effects of equipment in the cement production process. Existing studies mainly focus on the primary functions of equipment, such as the grinding efficiency of ball mills, the thermal decomposition in cyclone preheaters, and the thermal decomposition in rotary kilns. This study selected four typical pieces of equipment with significant homogenization functions for an in-depth investigation: ball mills, pneumatic homogenizing silos, cyclone preheaters, and rotary kilns. To assess the homogenization efficacy of each apparatus, scaled-down models of these devices were constructed and subjected to simulated experiments. To improve experimental efficiency and realistically simulate actual production conditions in a laboratory setting, this study used the uniformity of the electrical capacitance of mixed powders instead of compositional uniformity to analyze homogenization effects. The test material in the experiment consisted of a mixture of raw meal from a cement factory with a high dielectric constant and Fe3O4 powder. The parallel plate capacitance method was employed to ascertain the capacitance value of the mixed powder prior to and subsequent to treatment by each equipment model. The fluctuation of the input and output curves was analyzed, and the standard deviation (S), coefficient of variation (R), and homogenization multiplier (H) were calculated in order to evaluate the homogenization effect of each equipment model on the raw meal. The findings of the study indicated that the pneumatic homogenizer exhibited an exemplary homogenization effect, followed by the ball mill. For the ball mill, a higher proportion of small balls in the gradation can significantly enhance the homogenization effect without considering the grinding efficiency. The five-stage cyclone preheater also has a better homogenization effect, while the rotary kiln has a less significant homogenization effect on raw meal. Finally, the raw meal processed by each equipment model was used for clinker calcination and the preparation of cement mortar samples. After curing for three days, the compressive and flexural strengths of the samples were tested, thereby indirectly verifying the homogenization effect of each equipment model on the raw meal. This study helps to understand the homogenization process of raw materials by equipment in cement production and provides certain reference and data support for equipment selection, operation optimization, and quality control in the cement production process.

Roadmap of Graphite Moderator and Graphite-Matrix TRISO Fuel Management Options

Most high-temperature reactors use graphite as a moderator and structural material. This includes high-temperature gas-cooled reactors with helium cooling and TRi-structural ISOtropic (TRISO) fuel particles embedded in graphite, as well as fluoride salt–cooled high-temperature reactors with clean salt coolant and TRISO fuel particles embedded in graphite and thermal spectrum molten salt reactors with a graphite moderator and fuel dissolved in the salt. The largest volume radioactive waste stream from these reactors is the irradiated graphite. We describe herein a roadmap for management of these graphite wastes that contain radioactive 14C, tritium, and other radionuclides. There may be some graphite wastes with sufficiently low radioactivity levels that can be treated as nonradioactive waste and managed like other graphite waste. Management options for the graphite include (1) direct disposal, (2) recycled back to the reactor or other nuclear applications, and (3) oxidizing the graphite with release as an effluent or underground sequestration of the carbon dioxide. Cosequestration of this carbon dioxide with carbon dioxide from industrial, biological, and cement production processes can isotopically dilute the 14C before sequestration to eliminate the possibility of exceeding individual radiation exposure limits. We also describe options for processing graphite-matrix TRISO fuel, including separating the bulk graphite to reduce the volumes of used fuel for disposal or processing to recover fissile materials. The inventories of radioactive isotopes in different carbon wastes vary by many orders of magnitude; thus, there is no single economic option for the management of all graphite waste.

MAXIMUM EXPONENTIALLY WEIGHTED MOVING AVERAGE WITH MEASUREMENT ERROR (USING COVARIATE METHOD) USING AUXILIARY INFORMATION FOR CEMENT QUALITY CONTROL

The main quality characteristic at XYZ Inc. that should be observed is Compressive Strength. Cement production quality control is carried out on the average and process variability jointly with the Max-EWMA control chart. Measurement error can be found in the Compressive Strength. It can affect the sensitivity of the control chart, so quality control will be carried out by considering the presence of measurement error. Handling measurement errors can be done through three approaches (covariate method, multiple measurements, and linearly increasing variance). This research only focuses on the covariate method. Auxiliary variables also explain variance in the production process, so they are also considered in this research, with Blaine used as an auxiliary variable. Therefore, the control chart that will be formed is the Max-EWMA ME (Covariate) AI. The Max-EWMA and Max-EWMA ME (Covariate) AI control charts show that the XYZ Inc. cement production process based on variability and process averages is simultaneously statistically controlled. The controlled Max-EWMA control chart has an upper control limit of UCL=1.503018, and parameters dan . Max-EWMA ME (Covariate) AI has in-control parameters . The Max-EWMA ME (Covariate) AI control chart is more sensitive than the Max-EWMA control chart. Cement production capabilities based on Compressive Strength have a Cpl and Cpk capability index of 1.54, which means that the cement production process is capable, consistent, and has high accuracy so that the quality has reached the target.

Novel f-CaO soft sensor for cement clinker based on integrated model of dual-parallel structure.

Aiming at the problem that the cement production process is inherently affected by uncertainty, time delay, and strong coupling among variables, this paper proposed a novel soft sensor of free calcium oxide in a cement clinker. The model utilizes a dual-parallel integrated structure with an optimized integration of one-dimensional convolutional neural networks, long and short-term memory networks, graphical neural networks, and extreme gradient boosting. The proposed model can mitigate the risks associated with overfitting while incorporating the strengths of each individual model and excels in extracting both local and global features as well as temporal and spatial characteristics from the original time series data, ensuring its stability. The experimental results demonstrate that this dual-parallel integrated model exhibits superior robustness, predictive accuracy, and generalization capabilities when compared to single models or enhancements made to other deep learning algorithms.

A Study on Application of Desulfurization Technology in Cement Production Process

A Study on Application of Desulfurization Technology in Cement Production Process

Factors influencing the hydration kinetics of ye'elimite; effect of free lime

This study investigates factors influencing the hydration of ye'elimite, comparing stoichiometric ye'elimite-rich clinkers with and without free lime (Y-C and Y, respectively). Although the hydration sequences and products were similar, there were notable differences in their kinetics. Y-C exhibited rapid hydration upon contact with water, followed by a significant slowdown within minutes. Contrary, Y demonstrates a slower early hydration, but reached the main hydration period earlier and proceeded more rapidly thereafter. Solution analyses revealed higher initial calcium and aluminium concentrations for Y-C, while the sulfur concentration was reduced. This was attributed to the rapid dissolution of free lime, along with some ye'elimite, resulting in the instantaneous formation of ettringite and aluminium hydroxide. Consequently, the solution composition was altered, causing delayed onset of monosulfate formation and main hydration period. These findings contribute to understanding the hydraulic reactivity of ye'elimite and its potential implications for cement production processes.

Co-processing of end-of-life wind turbine blades in portland cement production

The objective of this paper is to evaluate the feasibility of co-processing wind turbine blade (WTB) material in cement manufacturing to provide an end-of-life means to divert the solid waste of decommissioned WTBs from landfills. Many WTBs consist primarily of glass fiber reinforced thermoset polymers that are difficult to recover or recycle. Portland cement is produced world-wide in large quantities, requiring immense quantities of raw materials (mostly calcium oxide and silicon oxide) and kiln temperatures approaching 1,450 °C. This work contributes analyses of WTB material composition, and predicts the energy provided through the combustible components of the WTBs and raw material contributions provided by incorporating the incombustible components of the WTBs to produce cement. Approximately 40 to 50 % of the WTB material will contribute as fuel to cement production, and approximately 50 to 60 % of the WTB material is expected to be incombustible. One tonne of WTB material can displace approximately 0.4 to 0.5 tonne of coal, while also contributing approximately 0.1 tonne of calcium oxide and 0.3 tonne of silicon oxide as raw material to the cement production process. The glass fiber WTB tested had an average boron content of 4.5 % in the ash. The effects of this high boron content on the cement and its production process should be evaluated. Co-processing WTBs in cement plants will slightly reduce combustion-related CO2 emissions due to avoided calcination. It seems feasible to co-process glass-fiber reinforced WTBs in cement production as WTBs provide suitable raw materials and compatible fuel for this process.

COMPRESSIVE STRENGTH, FLOWABILITY, AND ULTRASONIC PULSE VELOCITY TESTS OF PORTLAND CEMENT-FLY ASH-CALCINED CLAY MORTARS

The cement production process significantly affects the environment and contributes to air pollution. Consequently, there is a growing emphasis on employing alternative materials or minimizing cement usage as a solution to address environmental issues and reduce air pollution. In this investigation, an examination was conducted by substituting Portland cement with a weight of 50% with both fly ash and calcined clay. The findings revealed that replacing Portland cement with fly ash resulted in a decrease in compression strength. However, concurrently incorporating calcined clay increased compressive strength. Higher compressive strength compared to the 50% Fly ash mix was achieved by adding 20 wt.% Metakaolin and 20 wt.% Calcined clay Lopburi due to their finer particle size. As a result, the pozzolanic reaction is better than Lampang calcine clay (30FA20CClam). Additionally, ultrasonic pulse velocity testing indicated that higher values in the specimen correlated with increased compressive strength.

Characteristics of Low-Temperature Gasification Products from Wheat Straw in a Fluidized Bed Based on Cement Production Process

Characteristics of Low-Temperature Gasification Products from Wheat Straw in a Fluidized Bed Based on Cement Production Process

Multi-index control strategy from cement calcination denitration system: a model predictive control method for combined control of nitrogen oxide and ammonia escape.

The cement industry is one of the main sources of NOx emissions, and automated denitration systems enable precise control of NOx emission concentration. With non-linearity, time delay and strong coupling data in cement production process, making it difficult to maintain stable control of the denitration system. However, excessive pursuit of denitration efficiency is often prone to large ammonia escape, causing environmental pollution. A multi-objective prediction model combining time series and a bi-directional long short-term memory network (MT-BiLSTM) is proposed to solve the data problem of the denitration system and achieve simultaneous prediction of NOx emission concentration and ammonia escape value. Based on this model, a model predictive control framework is proposed and a control strategy of denitration system with multi-index model predictive control (MI-MPC) is built based on neural networks. In addition, the differential evolution (DE) algorithm is used for rolling optimization to find the optimal solution and to obtain the best control variable parameters. The control method proposed has significant advantages over the traditional PID (proportional integral derivative) controller, with a 3.84% reduction in overshoot and a 3.04% reduction in regulation time. Experiments prove that the predictive control framework proposed in this paper has better stability and higher accuracy, with practical research significance.

Application Strategy of Industrial Waste Gypsum in Cement Production

The paper primarily analyzes the application strategy of industrial waste gypsum in the cement production process, encompassing an introduction to industrial waste gypsum and its principal application strategies in cement production. According to the research, in modern cement production processes, industrial waste gypsum serves not only as a retarder and mineralizer but also for cement co-production. It is hoped that this analysis can offer valuable insights into the utilization of industrial waste gypsum and the enhancement of cement production process quality.

Study on structure-performance relationship and action mechanism of organic chemicals in cement grinding aids

Grinding aids (GAs) are an important addtive in the cement production process. However, the relationship between the molecular structure of GAs and its grinding efficiency has not been clearly revealed. In this study, the influence of GAs with different structures, including glycols and alkanolamines, on the grinding efficiency of pure clinker was systematically investigated. The working mechanism from their adsorption and dispersion configurations on tricalcium silicate (C3S) surface was investigated by first-principles method. As the structural parameters of GAs, number of polar groups is found to affect the grinding efficiency of cement clinker. The grinding performance of alkanolamines is better than that of glycols at the same dosage, when the number of hydroxyl groups is the same. The tertiary alkanolamines are adsorbed through the double-ended hydroxyl group to form larger molecular projection areas than the glycols with single-ended hydroxyl group, thus resulting in higher dispersion efficiency. Further, with the growth of the number of methyl groups in the molecular structure of the tertiary alkanolamines, the thickness of the adsorbed molecular layer grows from 9.25 Å to 9.87 Å, and the ability to shield the electrostatic forces between cement particles is enhanced and result in a better grinding aid performance.

Coupled Oxygen-Enriched Combustion in Cement Industry CO2 Capture System: Process Modeling and Exergy Analysis

The cement industry is regarded as one of the primary producers of world carbon emissions; hence, lowering its carbon emissions is vital for fostering the development of a low-carbon economy. Carbon capture, utilization, and storage (CCUS) technologies play significant roles in sectors dominated by fossil energy. This study aimed to address issues such as high exhaust gas volume, low CO2 concentration, high pollutant content, and difficulty in carbon capture during cement production by combining traditional cement production processes with cryogenic air separation technology and CO2 purification and compression technology. Aspen Plus® was used to create the production model in its entirety, and a sensitivity analysis was conducted on pertinent production parameters. The findings demonstrate that linking the oxygen-enriched combustion process with the cement manufacturing process may decrease the exhaust gas flow by 54.62%, raise the CO2 mass fraction to 94.83%, cut coal usage by 30%, and considerably enhance energy utilization efficiency. An exergy analysis showed that the exergy efficiency of the complete kiln system was risen by 17.56% compared to typical manufacturing procedures. However, the cryogenic air separation system had a relatively low exergy efficiency in the subsidiary subsystems, while the clinker cooling system and flue gas circulation system suffered significant exergy efficiency losses. The rotary kiln system, which is the main source of the exergy losses, also had low exergy efficiency in the traditional production process.