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In this study, this process has been modeled and optimized using the design of experiment technique and response surface methodology (RSM). The RSM was employed to optimize the combustion process in the cement kiln. Kiln feed (X1 = 160–190 t h−1), fan speed (X2 = 840–870 rpm), kiln rotational speed (X3 = 2.8–3.4 rpm), kiln fuel rate (X4 = 3800–4150 L h−1), calciner fuel rate (X5 = 5700–6200 L h−1), pressure of kiln inlet (X6 = 98–102 Pa), and limestone saturation factor (LSF) (X7 = 94–95.8 %) as independent variables were investigated. The carbon monoxide and the kiln body temperature in RSM were considered as response variables. The absolute average error in the model predictions for the combustion process in the cement kiln, for the kiln body's temperature, is about 1.6 % and for carbon monoxide is about 15.5 %. [ABSTRACT FROM AUTHOR]

This research paper gives the development data obtained for modern modified periclase‐spinel materials that have an increased adaptive ability to preserve the material integrity and the operational reliability of the refractories exposed to the effect of the sign‐alternating high‐gradient and thermal loads. Based on the research done, a concept was developed to improve the heat resistance of the periclase‐spinel materials and it includes both the known mechanisms of absorbing excess energy by cracks that are developed under the action of thermal shocks (in particular, the effect of heterophasicity and creation of a microcracked structure due to the difference in thermal efficiency coefficients (TEC) for different phases) and new mechanisms of the structure‐&‐phase adaptations preserving simultaneously the integrity of modified periclase‐spinel refractories. The use of the developed modified periclase‐spinel refractories results in the energy saving of up to 15 %, reduction of material costs due to the extension of the service life of the lining elements of rotary kilns; reduction of the resources required for the maintenance and an increase in the amount of overhaul sessions. [ABSTRACT FROM AUTHOR]

The disposal of solid waste in dumpsites is getting increased in developing countries due to rapid urbanization. Biomining is an innovative idea to recover valuable resources from legacy waste and usable land from old dumpsites. Various mechanical equipments are employed in the biomining process, out of which the trommel screen plays a major role in sieving the legacy waste into different fractions. Optimization of trommel screen performance in the biomining process is carried out in this project. Feasible operating parameters such as the feed rate of the trommel screen 1 (100 mm) and trommel screen 2 (4 mm) and moisture content of legacy waste were optimized in the Rajapalayam biomining site, Tamil Nadu, India. The characteristics of legacy waste in three different biomining sites, namely, Rajapalayam, Srivilliputhur, and Sivakasi, were analyzed. Results indicate that 9 and 2 m3 h–1 feed rates show more separation efficiency for trommel 1 and 2, respectively. Changing the feed rates to the optimized values is also suggested to get better separating efficiency without compromising the purity and recovery of fractions. The recovery of the underflow fraction is maximum at a moisture content of 1.5% and 5.3% for trommel 1 and trommel 2, respectively. The trommel screen gets clogged for higher and lower values of moisture content so that the recovery of the underflow fraction gets affected. The refuse‐derived fuel (RDF) characteristics meet the standard for reuse in cement kilns, and the bioearth characteristics are not suitable to be used as a soil amendment in its original form due to the unavailability of nutrients such as NPK and elevated C/N ratio. [ABSTRACT FROM AUTHOR]

Cement manufacturing is energy‐intensive (5Gj/t) and comprises a significant portion of the energy footprint of concrete systems. Incorporating modern monitoring, simulation and control systems will allow lower energy use, lower environmental impact, and lower costs of this widely used construction material. One of the goals of the CESMII roadmap project on the Smart Manufacturing of Cement included developing an analytical process model for clinker quality that includes the chemistry of the kiln feed and accounts for critical process variables. This predictive model will be used in nonlinear model predictive control system designed to significantly reduce process energy use while maintaining or improving product quality. In the cement manufacturing plant used in this study, the kiln feed (meal) is tested every 12 h and used to estimate the mineral composition of the cement kiln output (clinker) using the stoichiometry‐based Bogue's model and the expertise of the plant operators. During kiln operation, kiln output (clinker) is sampled and tested every 2 h to measure its chemical and mineral composition. The predicted and measured values of the clinker composition are used by the plant operators to adjust the kiln input stream and the production process characteristics to maintain stable operation and uniform product quality. However, the time delay between prediction and testing, along with inaccuracies inherent in the Bogue's model have made any process changes designed to minimize energy use problematic, especially in‐light of potential clinker quality issues that process changes often pose. A new analytical model that integrates quality information and process operation information has been developed from data collected from 2 years of production from an operating cement facility. To make the model fuel‐type‐independent, consumed heat energy was computed in the model instead of fuel type and amount. A Feedforward Network was trained and tailored from collected data. Many data‐based simulations were conducted to quantitatively evaluate the proposed model and the 5‐fold cross‐validation procedure was used to test the models. The resulting predictive model was shown to have a low root mean square error (MSE) with respect to the estimated clinker mineral composition compared to that using the industry standard "Bogue' model". The end goal of this work was to develop a single machine learning tool that allows the use of quality control data and process control variables to improve energy efficiency of the process in a continuous fashion. The proposed nonlinear model predictive control system (NMPC) can generate predicted kiln production characteristics based on manipulated variables in manner that accurately follows the target product quality values. Simulation results also show that the proposed model produced accurate predictions of kiln outputs that fell within the required constraints, while manipulating control variables within typical operational ranges. [ABSTRACT FROM AUTHOR]

This study investigated the geochemical and mineralogical characteristics combined with heavy elements concentrations of Cement kiln dust (CKD) in Ain Sukhna industrial area, North‐western part of the Gulf of Suez, Egypt and the influence of flash floods in its stability. Flooding severity is moderate with several water erosional processes. The CKD characterized by very poorly sorted/very fine‐sands to silt. CaO and SiO2 are major components with enrichment of chloride/sulfate ions. High enrichment of Sr, Zn, Pb, Cd, Sb, and Se are related to variations in shale/limestone feeds during cement formation. The threshold effect level exceeds the standard value for Cd, Pb, and Zn at S3 that indicates adverse biological effects. Sylvite, calcite, and halite minerals were dominated. Three main principal components recognized the shale, calcium/magnesium carbonate dissolution, and the scavenging effect of sulfate for heavy elements. Monitoring the CKD leachability and proper management plans are prerequisite for environmental protection in the future. [ABSTRACT FROM AUTHOR]

This paper draws on evidence from debt bonded brick workers in Cambodia to explore how animism and formal religion are articulated to retain workers in dangerous and difficult conditions. The paper shows first how factory labourers, owners, and local religious figures actively articulate spiritual beliefs by legitimising workers' confinement to the kiln through moral recourse to Buddhist notions of merit, character, and destiny. Secondly, it shows how informal animist beliefs play a key role in shaping interpretations of, and responses to, the extreme physical conditions of the kilns. Thus, by exploring how superstition and religious beliefs work to co‐constitute labour (im)mobility in the country's brick kilns, it makes a case for linking the geographies of labour, mobilities, and spirituality. More broadly, by highlighting the role of locally articulated spirituality in immobilising workers, our paper provides a counterpoint to predominant narratives of spiritual and animist agency as resistance, demonstrating instead how such agency may serve in the workplace as a means of coercion, restriction and control. [ABSTRACT FROM AUTHOR]

We examine the adoption of fuel‐efficient precalciner kilns in the cement industry using the universe of adoption decisions in the United States over 1973–2013. We find that cement plants are more likely to adopt the technology if fuel costs are high, nearby competitors are few, and local demand conditions are favorable. We relate the findings to the Schumpeterian and induced innovation hypotheses regarding the effects of competition and factor prices. Our results suggest firms may be most responsive to factor prices under advantageous competitive and demand conditions. [ABSTRACT FROM AUTHOR]

The cement industry is one of the largest pollutant emitters. One way to cope with high pollutant emissions is to co‐combust biomass with pulverized coal. A mathematical model was developed, which is detailed enough to consider the complex physical and chemical behavior of the co‐combustion process but simple enough to perform simulations with a real geometry of cement rotary kiln within reasonable time. Numerical simulation with a 20‐% share of pulverized biomass of total fuel heating value was performed. An industrial rotary kiln geometry was simulated; temperature and velocity fields along with mass fractions of released volatiles and combustion products were analyzed. The model allows better insights in the co‐firing process with the main goal to reduce CO2 emissions by optimizing the combustion process inside the rotary kiln. [ABSTRACT FROM AUTHOR]

The Xing kiln, which is located in Xingtai, Hebei Province, is famous for white porcelain production, especially translucent white porcelain. However, the translucency, as the most important characteristic of translucent white porcelain, is rarely mentioned. In this study, eight samples including translucent white porcelain and non‐translucent white porcelain excavated from the Xing kiln are quantitatively analysed by a transmittance tester. The study points out the defects of the previous concept of translucent white porcelain based on light transmittance and proposes a new definition based on translucency. Translucent white porcelain is not deliberately thinned fine white porcelain, but a special kind of fine white porcelain with a body of excellent translucency. Further analysis reveals that all transmittance values of translucent white porcelain are more than 0.01% with a body thickness less than 6 cm, which is higher than that of non‐translucent white porcelain by about one or two orders of magnitude. The absorption coefficient for translucent white porcelain is close to −0.82, while that for non‐translucent white porcelain is much closer to −1.87. This research will serve to further studies on subjects such as the classification, colouring mechanism and firing technology of the translucent white porcelain of the Xing kiln. Moreover, it is expected to set a new stage for discussing the translucency of ancient porcelain. [ABSTRACT FROM AUTHOR]

Cement kiln dust accelerated carbonation in aqueous slurries at 25°C and 3 bar PCO2 was investigated by X-ray diffraction analysis, solution chemistry, scanning electron microscopy, and energy dispersive spectroscopy to better understand chemical and mineralogical processes governing CO2 uptake. Dissolution of lime, portlandite, and ettringite occurs primarily in the carbonation process. These provide Ca2+ ions to react with CO32− ions leading to calcite bulk precipitation from solution. Concomitantly, the dissolution of Ca-(Al)-silicate grains takes place but it is limited by the formation of a Si-rich and Ca-depleted rim which appears onto the grain surfaces due to an initial hydration step. The Si-rich decalcified rim hinders the diffusion of Ca2+ ions from the core of silicate grains to the bulk solution. The diffusion of Ca ions through the rim is then the rate limiting step for the carbonation of Ca-(Al)-silicate, that accounts for up to 4% of the carbonation potential. Achieved results elucidate the processes governing CO2 uptake by cement kiln dust, and are fundamental in the perspective of enhanced CO2 sequestration by cement kiln dust. © 2017 Society of Chemical Industry and John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The cement production process is energy intensive both in terms of the thermal energy (firing the kiln, drying and De carbonation) and electrical energy for driving the numerous drives within the process line. The average specific power consumption of the case study plant was 111 kWh/ton of cement with an average peak demand of 9.7 MW. The high cost of electric power at 0.14 USD/ kWh results in very high cost of production that significantly lowers the company's profit margin and limits its competitive advantage. The generation of electrical power from waste heat recovery would reduce the electricity power bill through partially substituting the power procured from the national grid. This research evaluated the potential that the plant has for generating electrical power from the hot waste gases vented into the atmosphere and it was found that the plant has the potential to generate 3.4 MWh of electrical power. This results to a net potential to generate 2.89 MWh of electrical power after factoring in the auxiliary power consumption by Waste heat recovery plant system at 15%. This ultimately gave a reduction of 33% in the electricity power bill of the case study plant. The paper recommends the installation of a steam rankine cycle for the power generating plant. In this work the authors designed the steam boilers for the waste heat recovery plant for conversion of thermal energy to electrical energy, selected a commercial steam turbine and evaluated its economic feasibility and established that the designed plant would have a simple payback period of 2.7 years. [ABSTRACT FROM AUTHOR]

This study assessed the efficiency of activated carbon, cement kiln dust (CKD), and sawdust for the removal of cadmium (Cd), copper (Cu), lead (Pb), and zinc (Zn) from aqueous solutions under mono-metal and competitive sorption systems and the removal of Cd, Cu, and Zn from different industrial wastewaters. Batch equilibrium experiments were conducted in a mono-metal and competitive sorption system. The efficiency of the sorbents in the removal of Cd, Cu, and Zn from industrial wastewaters was also investigated. Cement kiln dust expressed the highest affinity for the metals followed by activated carbon and sawdust. Competition among the metals changed their distribution coefficient (Kd) with the sorbents. Sorption of Pb and Cu was higher than Cd and Zn. The average metal removal from the wastewaters varied from 74, 61, and 60% for Cd, Cu, and Zn, respectively, to nearly 100%. The efficiencies of CKD and activated carbon in removing metals were higher than sawdust, suggesting their potential as low-cost sorbents for the removal of toxic metals from wastewaters. [ABSTRACT FROM AUTHOR]

Immobilization techniques were adopted for the treatment of palm oil mill effluent (POME) and biogas production using immobilized anaerobic sludge as the seed. The performance of an upflow anaerobic sludge blanket reactor (UASBR) was monitored using cement kiln dust (CKD) at various hydraulic retention time (HRT). POME was used as the substrate carbon source. UASBR with POME concentration of 20 g-COD/L in the feed was able to produce methane at an optimal rate of 0.689 L CH4/(L POME h) and HRT of 50 h. The reactor pH was improved and maintained above 7.5 steadily by increasing CKD dose from 1.5 to 10 gCKD/L. In UASBR containing immobilized-granule, the methane production rate was 0.600-0.699 L CH4/(L POME h) at HRT of 75 h. The biogas production rate of 1.37 L/g-CODremoved.h and COD removal of 93% were found at POME concentration of 20 g COD/L ( r = 0.95) and HRT of 75 h. The suspended solids removal of 82% was found at 6.5 gCKD/L dose ( r = 0.99). © 2014 American Institute of Chemical Engineers Environ Prog, 2014 34: 736-743, 2015 [ABSTRACT FROM AUTHOR]

A mixture of different types of clay was blended with rice straw (RS) and microcrystalline cellulose (MCC) in the presence or absence of cement kiln dust (CKD) to produce new types of brick. The ratios of RS and MCC were 0, 5, and 10% w/w in the absence of CKD while they were kept at 5% w/w in its presence. The samples produced were compared to 'blended' bricks prepared using 10% w/w CKD. Samples were fired at temperatures up to 1000°C and their surface and composition studied using SEM and XRD. Moreover, the chemical and physical properties of prepared bricks were determined. Introducing RS reduced both strength and bulk density but increased porosity of prepared samples. The presence of MCC alone increased the compressive strength, while combining RS with CKD overcame the decrease in strength resulting from the presence of RS alone. This has enabled the production of light-weight low-cost bricks with a compressive strength close to nonblended bricks, especially at high firing temperature. POLYM. COMPOS., 35:174-179, 2014. © 2013 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

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A comparison of various waste-solvent treatment technologies, such as distillation (rectification) and incineration in hazardous-waste-solvent incinerators and cement kilns, is presented for 45 solvents with respect to the environmental life-cycle impact. The environmental impact was calculated with the ecosolvent tool that was previously described in Part I of this work. A comprehensive sensitivity analysis was performed, and uncertainties were quantified by stochastic modeling in which various scenarios were considered. The results show that no single treatment technology is generally environmentally superior to any other but that, depending on the solvent mixture and the process conditions, each option may be optimal in certain cases. Nevertheless, various rules of thumb could be derived, and a results table is presented for the 45 solvents showing under which process conditions and amount of solvent recovery distillation is environmentally superior to incineration. On the basis of these results and the ecosolvent tool, an easily usable framework was developed that helps decision makers in chemical industries reduce environmental burdens throughout the solvent life cycle. With clear recommendations on the environmentally optimized waste-solvent treatment technology, the use of this framework contributes to more environmentally sustainable solvent management and thus represents a practical application of industrial ecology. [ABSTRACT FROM AUTHOR]

The software tool ecosolvent is presented that allows for comparative environmental assessment of treatment technologies for specific, user-defined, waste-solvent mixtures. The tool is composed of models for waste-solvent distillation as well as for thermal treatment in hazardous waste-solvent incinerators and cement kilns. It was designed with a tiered structure in order to allow for a high flexibility regarding informational needs. The life-cycle assessment method was used to assess the environmental impact. The applicability of the tool is shown with two case studies from industry. In these case studies, various waste-solvent treatment technologies are compared for two specific waste-solvent mixtures. Potential use of the ecosolvent tool for its role in practical decision making in chemicals industries is illustrated by two case studies of waste-solvent systems. In the ethyl acetate case study, the tool indicates that solvent recovery by distillation is clearly better than incineration of the waste solvent. The results from the methanol case study are less clear-cut. In the subsequent article (part II), the ecosolvent tool will be used to derive general rules of thumb and specific recommendations for 45 important solvents used in chemical industries. Additionally, a framework will be presented that provides quick and easy decision support regarding environmentally optimized waste-solvent management. [ABSTRACT FROM AUTHOR]

Discusses the combination of fuzzy control and optimal control to control the cement kiln. Application of modern control theory to power system stabilization; Process of determining the optimal control; Difficulty of determining the switching-over point.