To address the degradation of mechanical and durability properties of microcapsule-based self-healing cementitious materials caused by interfacial defects, this study focused on cement mortars containing dual microcapsules of epoxy resin (EP) and tetraethylenepentamine (TEPA) as the study subject. We systematically compared and analyzed the effects of three mineral admixtures — nano-SiO2, silica fume (SF), and ground granulated blast furnace slag (GGBFS) — on the material’s mechanical properties, resistance to chloride ion penetration, resistance to sulfate attack, resistance to carbonation, and freeze-thaw durability, and further elucidated their mechanisms of action. The results indicate that all three mineral admixtures can synergistically optimize the pore structure of the paste through a combination of micro-filling and pozzolanic effects, thereby enhancing the interfacial bonding between the microcapsules and the cement matrix, which effectively improves the mechanical and durability properties of the microcapsule-modified cement mortar. Among them, nano-SiO₂ and SF demonstrated superior performance in enhancing resistance to chloride ion penetration, sulfate attack, and freeze-thaw cycles, while GGBFS showed the most significant improvement in flexural and compressive strengths. Overall, mineral admixtures can effectively compensate for the loss of intrinsic properties in the cement matrix caused by the introduction of microcapsules, providing a theoretical basis and technical support for the engineering application of self-healing cement-based materials.

Aiming at the engineering bottleneck that it is difficult to balance strength and water permeability of pervious concrete, this paper investigates the effects of single and compound incorporation of triethanolamine and magnesium fluorosilicate on mechanical properties, pore structure and permeability coefficient of cement binder paste and porous pervious concrete. The experimental results indicate that triethanolamine presents an obvious characteristic of remarkable early-strength improvement but insufficient later strength gain, while magnesium fluorosilicate can steadily and continuously enhance the strength. The combined admixture system exhibits excellent synergistic effect. The retarding regulation of MF effectively mitigates the deficiency in later-age strength development of TEA-amended systems caused by excessively rapid early hydration, and significantly optimizes the homogeneity of microstructure at later ages. The 28d compressive strength of paste in group T5M6 （0.5wt%TEA、0.6wt%MF） reaches as high as 114.5MPa. When applied in pervious concrete, the modified paste acts as a high-performance "bonding bridge" to strengthens the bond at aggregate contact points. For groups M9 (0.9wt%MF) and T5M6, the 28d compressive strength reaches 26.8MPa and approximately 29.0MPa respectively while maintaining a high permeability coefficient, which effectively breaks the trade-off between strength and water permeability. The research results can provide theoretical support for the preparation of high-performance pervious pavement materials for sponge cities.

The determination of water-soluble chromium (Ⅵ) content in cement is mainly carried out in accordance with GB 31893—2015， Limit and determination of the water-soluble chromium (Ⅵ) content for cement. However, this standard test method is time-consuming and labor-intensive, and the required testing instruments are susceptible to environmental constraints, making on-site rapid screening impractical. Against thisbackground, this paper develops a rapid detection method for water-soluble chromium (Ⅵ) in cement and its practical application. By optimizing and simplifying the experimental procedures, the filtrate containing water-soluble chromium (Ⅵ) is rapidly obtained through direct dispersion of cement samples, and the absorbance is measured with a portable visible spectrophotometer to obtain test results efficiently. Based on comparative analysis of test data from 54 groups of samples measured by the proposed rapid method and the national standard method, segmented correction formulas of the rapid detection method and its uncertainty interval for practical application are established. The results indicate that the developed method can serve as an effective technical tool for on-site rapid screening of cement  samples.

As the Ministry of Ecology and Environment promotes ultra-low emission retrofitting in the cement industry, higher requirements are placed on flue gas treatment and online monitoring systems. This paper systematically compares the detection method standards and technical principles of SO2, NOX, and NH3 for stationary pollution sources at home and abroad, focusing on the analysis of eight analytical techniques, including differential optical absorption spectroscopy (UV-DOAS), ultraviolet fluorescence (UVF), chemiluminescence detection (CLD), and tunable diode laser absorption spectroscopy (TDLAS). Combined with sampling systems such as cold-dry extraction, hot-wet extraction, dilution extraction, and in-situ direct measurement, this paper evaluates the applicability of these techniques under complex operating conditions in cement production. The research shows that the in-situ hot-wet system based on UV-DOAS offers advantages such as fast response, high accuracy, low power consumption, and low maintenance, making it particularly suitable for SCR denitrification process control and ultra-low emission monitoring. Verified by typical application cases, the UV-DOAS combined with in-situ hot-wet extraction monitoring system demonstrates stable performance and accurate data in SCR denitrification process and kiln tail flue gas outlet monitoring, meeting national technical specification requirements. In the future, with increasing demand for ultra-low emissions and multi-component monitoring, domestically produced Fourier transform infrared (FTIR) analysis systems are expected to become a better solution.

Cement has poor fluidity during the unloading process, so central inverted cone bottom silos are often used in engineering to improve unloading fluidity. However, this type of silo changes the cross-sectional shape within the height range of the inverted cone bottom and is prone to dead material zones. To investigate the variation of lateral pressure on the silo wall of a central inverted cone bottom silo, a plexiglass cement silo model with central inverted cone bottom, with a diameter of 500mm and a height of 1 600mm was designed. Three groups of cement loading and unloading tests were conducted, and three columns of pressure sensors were arranged along the silo wall to obtain the lateral pressure-time curves under full-load static condition and unloading condition. The test results were compared with the calculated values specified in Chinese, American and European codes. The results show that the test values of static lateral pressure along the depth are generally consistent with the uncorrected values of the three codes. The fluidity of cement in the upper part above the inverted cone bottom is weaker than that at the bottom, causing the maximum dynamic lateral pressure at the upper measuring points to appear later. The inverted cone bottom has pressure-reducing and flow-promoting effects: it reduces the static lateral pressure but increases the dynamic lateral pressure. The maximum dynamic lateral pressure at each depth is higher than the corrected values of the three codes. Based on this, a modified formula for lateral pressure under the Chinese code is proposed. Both the maximum static and dynamic lateral pressures occur in the middle-lower part of the vertical wall section.

Ultra-low emission control of nitrogen oxides (NOX) in the cement industry has been continuously tightened, and selective catalytic reduction (SCR) has become the mainstream treatment technology. After the medium-temperature and medium-dust SCR denitrification system of a 5 000t/d cement clinker production line was put into operation, problems such as catalyst clogging, sharp drop in denitrification efficiency and excessive NO_X emission occurred due to the incineration of alternative fuels and co-processing of industrial sludge. In this paper, the technical characteristics of medium-temperature medium-dust and high-temperature hige-dust SCR processes are compared, and the core inducements of catalyst deactivation caused by ammonium bisulfate formation and total organic carbon condensation in the medium-temperature SCR system are analyzed. Aiming at the key technical difficulties of high-temperature high-dust SCR in the renovation, solutions including adjusting the flue gas path, replacing high temperature specialty catalysts, and optimizing the ash cleaning and valve systems are proposed. After renovation, the NO_X emission concentration of the system is stabilized at 36~48mg/Nm³, the denitrification efficiency reaches 88%~92%, the system resistance and energy consumption meet the standards, and the long-term operation stability is significantly improved.

In view of the difficulty in stably meeting the ultra-low flue gas emission requirements of the wet flue gas desulfurization system of a 5000t/d cement clinker production line, this paper carries out a technical renovation study on the capacity expansion and upgrading of the wet flue gas desulfurization (WFGD) system. By comparing three renovation schemes, namely single-tower double circulation, double-tower series connection, and in-situ single-tower capacity expansion, the in-situ single-tower capacity expansion scheme is selected. The main renovation measures include elevating the desulfurization tower body, adding new spray layers and circulating pumps, optimizing the oxidation air pipe network, replacing the high-efficiency three-stage ridge-type demister, and raising the operating liquid level in the tower.After the renovation, the system runs stably. Under the working condition with the inlet SO₂ concentration no more than 2500mg/Nm³, the outlet SO₂ concentration is steadily lower than 35mg/Nm³, the dust concentration is less than 10mg/Nm³ and the desulfurization efficiency reaches 98.97%. All indexes fully comply with the ultra-low emission standards for the cement industry. Featuring a high equipment reuse rate, small floor area and convenient construction, the proposed renovation scheme can provide an engineering reference for the desulfurization system upgrading of cement clinker production lines with site space constraints.

The co-processing of solid and hazardous waste in cement kilns raises the concentration of harmful substances in flue gas, posing challenges to the stable and efficient operation of wet flue gas desulfurization systems. This paper analyzes the main operational problems of wet desulfurization systems during co-processing, including slurry poisoning, intensified equipment corrosion, and decreased desulfurization efficiency. The sources of harmful elements such as chlorine, fluorine, and heavy metals are clarified, and their multi-level enrichment pathways and action mechanisms are expounded from three aspects: the low-temperature area of the raw mill, slurry circulation in the desulfurization tower, and reuse of desulfurization wastewater. Combined with engineering practice, comprehensive optimization and renovation schemes are proposed from three perspectives of equipment anti-corrosion, wastewater zero discharge, and automatic control. The operation results show that the desulfurization efficiency exceeds 98% and full wastewater zero discharge is realized, with a significant reduction in annual operating cost. The research conclusions can provide a technical reference for the design, operation and maintenance of desulfurization systems in similar engineering projects.

To meet the increasingly stringent air pollutant emission standards for the cement industry, our company adopted a series denitrification technology route consisting of "duct furnace staged combustion denitrification + iSNCR + SCR" to upgrade the denitrification system of a 5000t/d cement clinker production line. This retrofit achieved full-process denitrification control covering the source, process, and end-of-pipe stages. Before the retrofit, the production line was only equipped with an intelligent selective non-catalytic reduction (iSNCR) denitrification system. Although NO_X emissions below 100mg/m³ could be achieved, further tightening of emission limits would lead to a substantial increase in ammonia consumption and ammonia slip. After the retrofit, the NO_X concentration at the stack outlet was stably kept below 50mg/m³, the measured ammonia slip was below 8mg/m³, and the ammonia consumption per ton of clinker decreased by about 1.8kg/t.cl. Meanwhile, the firing system operated stably, and the clinker output and quality were not affected. This combined process effectively reduces denitrification costs, achieves low-cost ultra-low emissions, and provides a feasible technical pathway for deep NO_X abatement in the cement industry.

To address the disposal challenge of arsenic-containing desulfurization gypsum（a hazardous waste）, industrial co-processing experiments were carried out based on a 4 500t/d new dry-process cement kiln. Three feeding rates of 5t/d, 7t/d and 9t/d were set up to systematically explore the influence of arsenic-containing desulfurization gypsum on clinker quality, heavy metal solidification, kiln tail flue gas emission and cement performance. The results indicate that when the daily feeding rate is controlled within 9t/d, the arsenic content in clinker does not exceed the national standard limit, and the leachable arsenic content is lower than the detection limit, which meets environmental protection specifications. The sulfur trioxide content of clinker increases slightly with a slight extension of setting time, while the 3d and 28d compressive strengths are improved steadily. The emission concentrations of sulfur dioxide and arsenic in kiln tail flue gas are stable and up to standard. Calculated at 9t/d, the effective raw material replacement rate reaches 0.39%, reducing 3.37kg of carbon dioxide emission per ton of clinker. This technology can realize the harmless disposal and resource utilization of arsenic-containing hazardous waste while ensuring stable kiln operation and product quality , and effectively broaden the application scope of co-processing hazardous wastes in cement kilns.

With the rapid advancement of digital and intelligent construction technologies, high-precision measurement and positioning techniques have become essential for the installation of large-scale cement industrial equipment. Taking the installation of a rotary kiln in a cement production line EPC project as a case study, this paper analyzes the limitations of traditional alignment methods, including their heavy reliance on operator experience, the use of multiple measuring instruments, and deficiencies in positioning accuracy and efficiency. The feasibility and effectiveness of a high-precision total station-based measurement and positioning method are then investigated. The results show that, through the integration of digital surveying instruments and a spatial coordinate system, the proposed method enables precise three-dimensional positioning of cement equipment during installation, significantly reducing installation errors, improving construction efficiency, and optimizing installation procedures. In addition, the method reduces dependence on manual experience and provides strong technical support for the digital and intelligent transformation of heavy cement equipment installation.

As a key conveying equipment in cement production processes, the reliability of the tail wheel assembly of a bucket elevator directly impacts system operational efficiency and environmental performance indicators. Conventional rolling bearings used in tail wheels are highly susceptible to failure due to dust ingress and lubrication deterioration, resulting in frequent unplanned shutdowns and elevated maintenance costs. This paper addresses the technical limitations of domestic bucket elevator tail wheel bearings, proposes a retrofit solution that incorporates a self-lubricating wear-resistant bushings and a fully sealed built-in counter weight, and systematically solves problems such as dust leakage, bearing wear, and environmental pollution by integrating an optimized built-in counterweight sealing structure. The solution has been validated through material selection, structural design, and engineering practice.Results show a significant reduction in equipment failure rates and maintenance expenses, along with marked improvement in the operating environment. This approach offers a practical and replicable solution for the modernization and reliability enhancement of bucket elevators in the cement industry.

The shaft-adit system offers significant energy savings and cost reductions, making it widely adopted in cement material open-pit mines. However, its application effectiveness is greatly influenced by the topographic and geological conditions of the mine site, as well as the physical properties of the ore and rock. This paper systematically introduces two mainstream design configurations of the shaft-adit system and their technical characteristics. Based on five typical mining engineering cases, it analyzes the application schemes and operational performance of these two configurations in actual projects. The study shows that the key to successful application of the shaft-adit system lies in: during the design phase, fully investigating the engineering geological conditions, reasonably determining the shaft diameter and the structural design at diameter transition points, and implementing targeted treatments for unfavorable geological sections; during the production phase, strictly controlling the moisture content of materials entering the shaft and the proportion of oversized blocks, avoiding prolonged storage of ore, and maintaining a full-shaft production condition. The two design configurations each have their own applicable scenarios, and the appropriate configuration should be selected based on the specific conditions of the mine, rather than simply copying the management model of the truck haulage system.