Hasil untuk "Cement industries"

H. Tan, Zhang Xun, Xingyang He et al.

Abstract Lithium slag is a by-product of lithium carbonate industry; in the past decades, due to ascending demand of lithium salts, emission of this kind of solid waste is dramatically increased and results in serious environmental problem. Utilization of lithium slag is of great importance to the sustainable development of lithium carbonate industry. In this study, one new way to utilize lithium slag in sulphoaluminate cement system was attempted. Lithium slag was processed with wet grinding, in order to obtain fine particles and facilitate the ions dissolution. Addition of wet-grinded lithium slag was expected to improve the early strength of sulphoaluminate cement. The hydration mechanism was investigated in terms of setting time, hydration process, hydrates, and pore structure. The results show that lithium slag with D(0.5) of 3.04 μm, which is extremely difficult to be prepared in dry-grinding system, can be easily obtained with wet-grinding process; the ions dissolution of lithium, aluminum, and silicon phase can also be significantly facilitated in wet-grinding process. With the dosage less than 10%, wet-grinded lithium slag can notably promote the early strength of the sulphoaluminate cement paste, and the main reason for the promotion is not only because of the filling effect of fine particles and nucleation seed induction of nano particles formed in wet-grinding process, but also due to the fact that the dissolved lithium can noticeably facilitate the precipitation of hydrates to induce the cement hydration. The findings suggest that lithium slag has great potential to be utilized in sulphoaluminate cement system, and also provide one new way to utilize solid waste in cement-based materials.

Sarah Danieli, José S. Andrade Neto, Erick Grünhäuser Soares et al.

Portland cement is one of the most used materials in the world. Despite the environmental harm its production causes, it will most likely continue dominating the market, given its remarkable characteristics and widespread use worldwide with high consumer acceptance. Improvements in the energy demand, equipment efficiency, and intensification of alternative materials have been proposed to mitigate the large amount of CO2 emissions during the clinker process. However, even if applied, only some extent of the CO2 emitted could be avoided since the most significant portion comes from the limestone decomposition, which cannot be avoided, fitting the cement industry into the list of hard-to-abate industries. In this scenario, new companies are developing and improving indispensable carbon capture technologies and CO2 reapplication in new processes. With the advance of carbon market regulation, the technologies that prove to be the most efficient will have a competitive advantage in this new economy. This study reviews the current carbon capture scenario in cement and concrete production and highlights the leading companies emerging in this sector, exploring the main aspects of their processes, technology readiness levels (TRL), real-world achievements, scalability, suitability for achieving net-zero emissions, credibility, feasibility, opportunities, and limitations.

F. U. Nwogu, E. A. Ubuoh, C. Kanu et al.

Abstract Cement industries contribute significantly to poor air quality globally. As cement production expands in Nigeria, so too does its environmental footprint. Despite the well-documented dangers of cement-related air pollution, there is a lack of comprehensive scientific evidence-based studies on monthly variations of air quality around cement plants in Southern Nigeria. There is a pertinent need for a systematic investigation into how cement production affects dry atmospheric chemistry and contributes to environmental degradation in the region; hence, the study evaluated the effect of cement production processes on ambient atmospheric chemistry at the Lafarge Holcim cement processing plant in Cross River, Southern Nigeria. Using mobile real-time air quality monitors (MX IBRID) , levels of carbon monoxide (CO), carbon dioxide (CO2), sulphur dioxide (SO2), nitrogen dioxide (NO2), volatile organic compound (VOC), hydrogen sulphide (H2S) and particulate matter (PM2.5, PM10) were taken from cement production sites: milling site, quarrying site and loading bay for a 12-month period (January to December, 2023). The results revealed that the milling site had the highest relative levels of dry atmospheric chemistry (NO2; 0.15 ± 0.01 ppm, SO2; 5.78 ± 0.008 ppm, VOCs; 8.41 ± 0.13 ppm, CO; 575.5 ± 722.5 ppm, PM10; 346.2 ± 128.4 μg/m3), and the quarrying site had the highest PM2.5 (31.6 ± 0.04 μg/m3). Comparison with different global standards showed significant exceedances in CO, SO2 and NO2, PM10 across the three sites with more than 35% increase relatively. The correlation matrix revealed a significant relationship among and between pollutants and meteorological parameters. Principal component analysis showed high positive and negative loadings of CO, CO2, SO2, NO2, VOC, H2S, PM2.5 and PM10 existing in clusters from different sources. The monthly air quality index report implicated PM10 and SO2 as major constituents of hazardous and very unhealthy air quality around the area. Key recommendations were made, among others, that the company must regularly conduct an environmental audit of all their processes so as to improve their environmental performance, adopt pollution reduction technologies such as the use of water spray, gas scrubbers, filters and alternative sources of fuel such as solar power. Environmental regulators must also brace up and issue sanctions, set restrictions and issue heavy fines when there is a breach of environmental responsibilities on the part of the company.

Cassandra Trottier, Laurent Ramos Cheret, Haoye Lu et al.

The damage rating index (DRI) is a valuable microscopy tool for collecting and counting data on different types of concrete cracks, such as those associated with alkali-silica reaction (ASR) induced deterioration. Yet, the procedure presents drawbacks such as time consumption and variability linked to operator experience, which has sparked debates about the subjectivity of its outcomes. Embracing the forefront of technological advancements, this study explores the practicality of automating the DRI's data collection through artificial intelligence (AI) and machine learning. Like many image processing and analysis applications that use AI, the DRI is an object classification and segmentation task. This study represents a step forward in leveraging automation to enhance the objectivity and efficiency of ASR damage characterization in concrete through point-count microscopy, along with proposing a set of tools to evaluate the outcomes from the application’s perspective for more efficient training data selection. Results show that despite obtaining acceptable performance individually, where the detector-classifier performance was found to have an accuracy of 0.744, and the crack counter accuracy was 0.988, the current version of the proposed machine still displays high variability in detecting, classifying, and counting distinct crack types. Overall, the machine overestimates ASR-induced damage, which was further verified through the Chi-square goodness of fit test, indicating that further training and enhancement of the proposed machine are required.

Y. C. Díaz, S. S. Berriel, U. Heierli et al.

Abstract This paper aims at assessing the return on investment and carbon mitigation potentials of five investment alternatives for the Cuban cement industry in a long-term horizon appraisal (15 years). Anticipated growing demand for cement, constrained supply and an urgent need for optimisation of limited capital while preserving the environment, are background facts leading to the present study. This research explores the beneficial contribution of a new available technology, LC 3 cement, resulting from the combination of clinker, calcined clay and limestone, with a capacity of replacing up to 50% of clinker in cement. Global Warming Potential (GWP) is calculated with Life Cycle Assessment method and the economic investment's payback is assessed through Return on Capital Employed (ROCE) approach. Main outcomes show that projected demand could be satisfied either by adding new cement plants—at a high environmental impact and unprofitable performance— or by introducing LC 3 strategy. The latter choice allows boosting both the return on investment and the production capacity while reducing greenhouse gas (GHG) emissions up to 20–23% compared to business-as-usual practice. Overall profitability for the industry is estimated to overcome BAU scenario by 8–10% points by 2025, if LC 3 were adopted. Increasing the production of conventional blended cements instead brings only marginal economic benefits without supporting the needed increase in production capacity. The conducted study also shows that, in spite of the extra capital cost required for the calcination of kaolinite clay, LC 3 drops production costs in the range of 15–25% compared to conventional solutions.

Sangit Saha, Hena Ray, Alokesh Ghosh et al.

Anuoluwapo S. Taiwo, David S. Ayre, Morteza Khorami et al.

This study investigates the influence of limestone powder and metakaolin as sustainable eco-friendly additives on the properties and behavior of cementitious composite boards, with a focus on mechanical strength, physical properties, and microstructural characteristics. The experimental investigation begins with the characterization of the raw materials, including limestone powder, and metakaolin, to assess their particle sizes, elemental composition, and microstructural features. Cement composite boards were fabricated using an innovatively developed lab-simulated vacuum dewatering process, by varying the proportions of limestone powder and metakaolin as partial replacements for cement, along with waste kraft fibres as reinforcement. Mechanical testing was conducted to evaluate the flexural strength and behaviour of the composite boards according to standardized procedures. A microstructural analysis was performed using scanning electron microscopy (SEM) to examine the effect of additives on the cementitious matrix, fibrematrix interaction, and hydration products. The findings from the experimental study reveal insights into the influence of limestone powder and metakaolin on the mechanical properties and microstructure of waste kraft fibre-reinforced cement composite boards. Our analysis of the results shows that adding 9% limestone powder as partial cement replacement produces a 24% and 50% enhancement in flexural strength at 7 and 28 days of hydration, while that of metakaolin as partial cement replacement was optimum at 6% with an enhancement of 4% and 36%, respectively, at 7 and 28 days of hydration. The implications of these findings for the development of sustainable cementitious composite are discussed, including the potential benefits of using limestone powder and metakaolin as supplementary cementitious materials in waste kraft fibre-reinforced cement composite boards. Finally, recommendations for optimizing additive proportions are also provided to enhance the understanding and application of these materials in the construction and building industries.

Hossein Asgharian, Ali Yahyaee, Chungen Yin et al.

Many governments around the world have taken action to utilise carbon capture (CC) technologies to reduce CO₂ emissions. This technology is particularly important to reduce unavoidable emissions from industries like cement plants, oil refineries, etc. The available literature in the public domain explores this theme from two distinct perspectives. The first category of papers focuses only on modelling the CC plants by investigating the details of the processes to separate CO₂ from other gas components without considering the industrial applications and synergies between sectors. On the other hand, the second category investigates the required infrastructure that must be put in place to allow a suitable integration without considering the specific particularities of each carbon capture technology. This review gives a comprehensive guideline for the implementation of CC technologies for any given application while also considering the coupling between different energy sectors such as heating, power generation, etc. It also identifies the research gaps within this field, based on the existing literature. Moreover, it delves into various aspects and characteristics of these technologies, while comparing their energy penalties with the minimum work required for CO₂ separation. Additionally, this review investigates the main industrial sectors with CC potential, the necessary transportation infrastructure from the point sources to the end users, and the needs and characteristics of storage facilities, as well as the utilisation of CO₂ as a feedstock. Finally, an overview of the computation tools for CC processes and guidelines for their utilisation is given. The guidelines presented in this paper are the first attempt to provide a comprehensive overview of the technologies, and their requirements, needed to achieve the cross-sector coupling of CC plants for a wide range of applications. It is strongly believed that these guidelines will benefit all stakeholders in the value chain while enabling an accelerated deployment of these technologies.

SD Ndlovu, E Prabakaran, K. Pillay

Heavy metals are posing problems in the environment and one of them is lead. The disposal of lead in our water systems comes from industries such as the paint, mining, and electroplating industries. In this study, Carbon nanoparticles (CNPs) were synthesized from carbon soot by using a refluxed method. The CNPs were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction pattern (XRD) Brunauer–Emmett–Teller (BET), Thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and Transmission Electron Microscope (TEM). Batch adsorption studies were carried out for lead adsorption. Pb2+ uptake fitted well with the pseudo-second-order kinetics model, while the adsorption isotherm fitted best to the Langmuir model, with a maximum adsorption capacity of 67.98 mg/g at 25 °C. The obtained thermodynamic parameters demonstrated that the adsorption of Pb2+ ions by carbon nanoparticles was exothermic and spontaneous. The spent adsorbent was then used in cement production, demonstrating that Pb2+-CNPs can be a promising material for cement production when its quantity exceeds 1.2 %.

M. Hossain, C. Poon, Irene M. C. Lo et al.

Deepankar Kumar Ashish

Hamdy El-Diadamony, A. Amer, T. E. Sokkary et al.

Abstract The industrial area produces lots of solid waste materials with CO2 emission. One of the most effective ways to solve these problems is the utilization of these waste materials. The production process of cements from its raw materials produces a lot of CO2. The most effective way to decrease CO2 emission of cement industry is the substitution of a proportion of cement with supplementary cementing materials. Cement blended with metakaolin (MK) is also required as a countermeasure to reduce the amount of CO2 generation. Metakaolin (MK), Al2Si2O7, is a highly amorphous dehydration product of kaolinite, Al2(OH)4Si2O5. The aim of our research was to investigate the effect of up to 20 wt% substitutions of OPC by MK on the hydration characteristics of MK-blended cement pastes. The physico-chemical properties of the hardened cement pastes were studied up to 90 days of hydration. The hydration products of some selected samples were investigated using XRD, DTA and DTG techniques. The results indicated that substitution of up to 20 wt% OPC by MK as pozzolanic materials resulted in an increase in the standard water of consistency, acceleration of the initial setting times, high compressive strength values at earlier ages and improvement of the mechanical and durability properties.

Takuma Watari, André Cabrera Serrenho, Lukas Gast et al.

Abstract The current decarbonization strategy for the steel and cement industries is inherently dependent on the build-out of infrastructure, including for CO2 transport and storage, renewable electricity, and green hydrogen. However, the deployment of this infrastructure entails considerable uncertainty. Here we explore the global feasible supply of steel and cement within Paris-compliant carbon budgets, explicitly considering uncertainties in the deployment of infrastructure. Our scenario analysis reveals that despite substantial growth in recycling- and hydrogen-based production, the feasible steel supply will only meet 58–65% (interquartile range) of the expected baseline demand in 2050. Cement supply is even more uncertain due to limited mitigation options, meeting only 22–56% (interquartile range) of the expected baseline demand in 2050. These findings pose a two-fold challenge for decarbonizing the steel and cement industries: on the one hand, governments need to expand essential infrastructure rapidly; on the other hand, industries need to prepare for the risk of deployment failures, rather than solely waiting for large-scale infrastructure to emerge. Our feasible supply scenarios provide compelling evidence of the urgency of demand-side actions and establish benchmarks for the required level of resource efficiency.

Chunzhi Cai, Reny P. Devassy, Mohsen M. El-Sherbiny et al.

Chaoyue Zheng, Haoran Zhang, Xingrui Cai et al.

Abstract To estimate the air pollution emissions from China’s cement industry and quantify the impacts of various influencing factors, we estimated the direct emissions and indirect electricity emissions of greenhouse gases and atmospheric pollutants from China’s cement industry over 2005–2012 at the provincial level from the perspective of the cement life-cycle. Carbon dioxide (CO2), sulfur dioxide (SO2), nitrogen oxides (NOX), and particulate matter (PM) were considered in this study. Using the Logarithmic Mean Divisia Index (LMDI) method and the multi-regional decomposition analysis (M-R) model, we quantified the impacts of the emission factor, energy intensity, output structure, clinker share, and production scale on the tempo-spatial variations in pollutant emissions. Our results show that, from 2005 to 2012, the emissions of CO2, SO2, NOx, and total suspended particulate (TSP) changed by 62%, 65%, −13%, and −46%, respectively. The major driving forces of these changes were production scale, output structure, production scale and output structure, and emission factor, respectively. In 2012, the proportions of indirect electricity emissions of CO2, SO2, NOx, and TSP corresponded to 10%, 33%, 20%, and 12% of the total, respectively. The emission intensities in the developed eastern provinces were much lower than the national average, due to their technological advantages. Through the interprovincial clinker trade, most of the pollution derived from the cement life-cycle in the eastern provinces was transferred to the central and western provinces, further increasing the pollution in these latter regions. This study may provide a reference for the comprehensive accounting of pollutant emission characteristics in a specific industry. The findings of this study suggest that China’s cement industry should adopt deNOx devices and use alternative raw materials and fuels to further reduce environmental burden.

Nora Cadavid-Giraldo, Mario C. Vélez–Gallego, Alexandre Restrepo-Boland

Abstract While the cement industry is perceived as one of the major contributors to climate change, with a 7 % share of total C O 2 emissions, direct taxes on emissions of these gases have been little applied to this productive sector. The present study addresses the issue of assessing the effectiveness of carbon taxation methods in encouraging sustainable cement production processes. In particular, the effect of different carbon emission prices on decisions that lead to a reduction of C O 2 emissions in a representative cement supply chain, was studied. A mixed-integer linear formulation is used to describe a non-taxed base case against a case that explicitly includes carbon taxes. Computational experiments conducted on a realistic-sized instance built based on publicly available data from the cement sector, showed that environmental benefits can be attained after implementing a carbon taxation mechanism. The results indicate that with a rate between 15 US $ and 150 US $ by C O 2 emitted ton over a predefined cap, will drive cleaner cement production scenarios with a reduction of emissions up to 24 % , respect to a non-taxed scenario used as the base line. The proposed decision-making tool can be effectively used by any cement company that needs to better assess the trade-off between its financial objectives and the sustainability goal of carbon emissions reduction.

S. R. Pinto, C. Angulski da Luz, G. S. Munhoz et al.

Abstract The search for cements with lower CO2 emissions and lower consumption of non-renewable materials has been a challenge for the cement industry. The aim of this study was to investigate the resistance of SSC concrete to carbonation and chloride ingress. Portland cements (CEM I and CEM III/B) were used as a comparison. The results showed that the carbonation was very advanced in the SSC concretes. This is related to the exclusive formation of C-S-H and ettringite as hydration products, which present a higher rate of carbonation than portlandite. The SSC concrete has a good performance in terms of chloride penetration, mainly due to the increased ability to combine chloride ions both physically and chemically. The service life estimation showed that SSC concretes could be suitable for rural and urban environments when low w/c ratios (0.40) are used. All SSC mixtures studied were suitable for chloride environments.

Junjie Wang, Engui Liu

Abstract To reduce solid waste discharges into environment and virgin resource consumptions in construction, waste seashells from seafood and aquaculture industry were recycled into powder form and reused in cementitious construction materials. This work aimed to use this biologically renewable waste material as a possible alternative to the nonrenewable limestone mineral used conventionally with Portland cement. The study explored roles of seashell powder as both a partial replacement and an additional additive to cement through evaluating the rheological and physico-mechanical properties of early-age cement paste. The cyclic rheological measurement including model analysis (Bingham, Casson, and Herschel-Bulkley models) was conducted to reveal the time- and shear-dependent workability of fresh cement paste during the first 2 h. Connecting to rheology, physico-mechanical measurements were carried out to understand hydration mechanisms of cement paste with seashell powder. Seashell powder was found to improve the rheological and early hydration behaviors of Portland cement paste. A parallel comparison between limestone and seashell powders was conducted to understand different roles of the two calcium carbonate minerals in cement system. Results from this study indicated the unique physical features and chemical reactivities of seashell powder in cement system, and thus suggested a promising feasibility to recycle waste seashells with cementitious construction materials.

Alaa H. Salum, Ban H. Ismail, Samer H. Sadik

This study investigates the feasibility of installing a waste heat recovery system (WHR) in a cement factory in Iraq using the organic thermal Rankine cycle (ORC). Heat losses in the cement industries represent high energy consumption percentages of the total energy inputs. The production of clinker is a sub-process in the cement manufacturing plant and consumes three quarters of the total energy used as heat from combustion. The main sources of waste heat in the cement plant are identified, from these sources of waste heat from the kiln surface to the air, hot air coming out of the clinker cooler, and preheating exhaust gases. It is possible to obtain the total waste heat from these sources in the range of 35-40% of the total heat input. This waste heat energy can be exploited by installing a waste heat recovery system in these plants to generate electricity. It is possible to generate electrical energy by 5.9 MW. When using an organic system to recycle hot gases in plants whose daily production is up to 6000 tons, the installation of such a system could lead to saving 82.5 tons of fuel oil consumption per day, and reducing carbon dioxide emissions by 99.12 tons per day.