Quicklime Research Articles

Identifying construction technologies and environmental connections at the Iron Age IIA settlement of Kh. es-Suwweida, Israel: A microarchaeological study

The first season of excavations at Kh. es-Suwweida in northern Israel revealed strata from the late Iron Age IIA consisting of a series of massive fortification walls, rooms and internal compartments with potential floors. A microarchaeological investigation was undertaken to add high-resolution contextual and compositional data to the field evidence and characterize site formation processes, construction materials and technologies, and use of environmental resources. We applied a micro-archaeological approach to study sediments and archaeological materials via micromorphology, Fourier-transform infrared (FTIR) spectroscopy and micro-spectroscopy, and phytolith and pollen analysis. Two main construction technologies were identified: lime plasters produced from mixtures of pyrogenic lime and non-pyrogenic crushed chalk, and mudbricks prepared from sedimentary materials. An in situ lime constructed floor with multiple re-plastering and activity zones associated with the remains of a degraded mudbrick structure was reconstructed in one locality, and a collapsed burnt lime and mudbrick building with a wooden superstructure was reconstructed in another locality. The micro-archaeobotanical analyses identify domesticated barley, the cultural utilisation of grasses on-site, and a hinterland vegetation of open fields. The combined microarchaeological evidence enables a more detailed reconstruction of the variability in construction technologies and the sequence of collapse and degradation processes in an Iron Age settlement.

Strength and leaching behavior of CaO- and MgO-treated Cd-contaminated soils subjected to partial and full carbonation

Cadmium (Cd)-contaminated soils may pose a significant threat on human health. They are often treated with quick lime (CaO) and reactive magnesia (MgO), but these treatments often result in low strength. Hence, in this study, partial and full carbonation are used to enhance the stabilization/solidification of CaO- and MgO-treated Cd-contaminated soils, aiming to achieve CO2 sequestration, strength improvement, and Cd immobilization. Performance of treated contaminated soils is evaluated through unconfined compressive strength (UCS), leaching, X-ray diffraction (XRD), and thermogravimetric analysis (TGA) tests. The results indicate that carbonation significantly enhances the UCS of both CaO- and MgO-treated Cd-contaminated soils. After carbonation, MgO-treated soils exhibit higher UCS than CaO-treated soils. Partial and full carbonation yield similar UCS in CaO-treated soils, while full carbonation results in higher UCS in MgO-treated soils. For CaO-treated soils, partial carbonation keeps Cd leachability below the 1 mg/kg limit, but full carbonation increases it beyond this limit. In contrast, fully carbonated MgO-treated soils maintain Cd leachability below the limit, though partial carbonation leads to higher leachability. Formation of Ca and Mg carbonates contributes to the strength improvement of soils. Cd(OH)2 and its complex, as well as CdCO3 exist in partially and fully carbonated soils, lowering leached Cd concentration. Overall, partial carbonation is better for CaO-treated soils, while full carbonation is preferable for MgO-treated soils.

DEVELOPMENT OF DRY BUILDING MIXTURES BASED ON REDISPERSIBLE POWDER FOR REGULATING THE PROPERTIES OF PLASTER MIXTURES

The relevance of the work. The results is theoretically substantiated and experimentally confirmed the possibility of obtaining a dry additive-retarder of gypsum setting based on lime and polyvinyl acetate dispersions due to the formation of polyvinyl alcohol and salts of calcium acetate in the result of alkaline hydrolysis of polyvinyl acetate dispersion (PVAD) with the slaked lime in hydrated lime. The results of the work implemented in the production of dry gypsum mixes. Purpose. The development of dry building mixes based on gypsum and time increase of time of their conformance through adding of complex additives on the basis of burnt lime and polyvinyl acetate dispersions [PVAD]. Methodology. The study used standard research techniques to determine physical and mechanical properties of gypsum binders and quality of complex additives according to ДСТУ Б В.2.7-82:2010, ДСТУ Б В.2.7-23-95, ДСТУ Б В.2.7-171:2008. Study of phase composition of materials, micro – and macrostructure was carried out by x-ray diffraction, electron and light microscopy. The results. The influence of the main components of the additive (polyvinyl acetate dispersion and lime) on the properties of hemihydrate gypsum is investigated. The chemistry of the interaction of components of the complex additive, according to which the result of alkaline hydrolysis of polyvinyl acetate is formed: polyvinyl alcohol, a feature of its molecules structure is the presence of hydrophilic OH−groups and the hydrophobic component − a hydrocarbon radical. The hydrophilic part of the molecule being ion adsorbed on the surface of the particles of the binder, forms a monomolecular layer that is oriented with the hydrophobic part of the gypsum particles. It is also possible the formation of calcium acetate Ca(СН3СОО)2, which increases the concentration of calcium ions in solution. The combined effect of hydrolysis products significantly reduce the solubility of hemihydrate, the rate of formation of crystallization centers, due to the slowing effect of these supplements.

Stabilization strategies for granite waste powder applied in sustainable pavement subgrade: Mechanical and durability performance

The sustainable and efficient treatment of massive granite waste powder (GWP) has received increasing attention. This study proposes a novel method for recycling GWP cemented by inorganic binder-stabilized materials (IBSM) for sustainable pavement subgrade filler, i.e., IBSM-stabilized GWP (ISG). IBSM consists of Portland cement (PC), quicklime (QL), ground granulated blast furnace slag (GGBS), and sodium dodecyl benzene sulfonate (SDBS). Response surface methodology (RSM) and microstructure analysis were employed to analyze the effects of IBSM components on ISG mechanical properties and durability. The 56d compressive strength of ISG is above 2.62 MPa, meeting the minimum criterion of 1 MPa. The residual strength coefficient after 5 freezing-drawing cycles is generally greater than 65 %, except for the groups with high QL content. Both PC and GGBS are positively correlated with the performance of ISG. Moreover, multi-objective optimization identifies the optimal mix ratio: 3.03 % PC, 0.83 % QL, 3.47 % GGBS, and 0.18 % SDBS. The optimal ISG presents excellent strength and durability performance, with S7d of 1.61 MPa, S56d of 3.88 MPa, Sw of 3.35 MPa, Rftc of 90 %, Rwdc of 92.01 %. These findings provide insight into the stabilization strategies of GWP using in highway subgrade filler, which can alleviate the environmental pollution induced by GWP waste.

Experimentation of Heat-Insulating Materials for Surrounding Rocks in Deep Mines and Simulation Study of Temperature Reduction

With the increasing depletion of shallow resources, mining has gradually shifted to deeper levels, and the high-temperature problem of deep mining has restricted the efficient and safe development of mining. In this study, five types of thermal insulation materials for surrounding rocks with different ratios were produced using tailings, P.O.32.5 clinker, aluminum powder, glass beads, quick lime, and slaked lime as test materials. Based on the uniaxial compression test, the thermal constant analysis test, and numerical simulation analysis technology, the change rule of mortar compressive strength and thermal conductivity was analyzed, and the cooling effect of surrounding-rock thermal insulation materials with different ratios was discussed. The results showed that the compressive strength of the surrounding-rock thermal insulation materials ranged from 0.39 to 0.53 MPa, and the thermal conductivity ranged from 0.261 to 0.387 W/(K·m), with the compressive strength of ratio E being the largest and the thermal conductivity of ratio A being the lowest. In the numerical simulation analysis results, the thermal insulation layer thickness was taken as a value of 10 cm when, at this time, the best thermal insulation effect and economic benefits involved a temperature reduction of 0.9 K. In the case of changing the thermal conductivity and inlet wind speed, the original temperature of the rock temperature reduction was also very clear, with maximum reductions of 0.92 K, 0.92 K, and 1.42 K.

Low-density granite-based geopolymer for well cementing: The role of burnt lime in enhancing early strength

In the pursuit of sustainable solutions within the oil and gas industry, the environmental and mechanical limitations of Ordinary Portland Cement (OPC) have led to the evaluation of more sustainable alternative materials for oilwell cementing applications. Particularly in shallow-depth cementing operations, where low-density slurries are essential to prevent formation breakdown, current solutions fall short in balancing environmental impact with the industry's performance requirements. Geopolymers, known for their reduced carbon footprint and comparable mechanical properties, have been seen as a promising alternative. However, increasing water content to lower the slurry density remains a challenge for geopolymers due to the weakening effect and prolonged reaction. The specific role of burnt lime (CaO) has the potential to enhance the early strength of low-density geopolymers yet remains under-explored for this particular case. This study aims to fill this gap by examining the effects of two different reactivities of CaO on a low-density granite-based geopolymer at low temperatures and investigate the potential of CaO to enhance the early strength of low-density geopolymers, aiming to provide a sustainable alternative to traditional cementing materials in oil well operation. The investigation consists of viscosity measurements, pumpability tests, and compressive strength evaluations. Additionally, isothermal calorimetry, TGA, XRD, and SEM were conducted to gain a deeper understanding of the behavior of each sample. Supplementary tests were conducted to evaluate the effect of varying CaO concentrations and the impact of mud contamination on the performance of low-density geopolymers. The investigation revealed that calcium oxide did not significantly impact the initial viscosity of the slurry however, it affects gelation and rate of the reaction. Short-term strength was shown to be affected by CaO at two different temperatures, yet negligible effects were seen in the long-term period for geopolymers with a high water-to-solid ratio. The findings suggest that CaO can significantly enhance the early strength of geopolymers, which are crucial properties for cementing operations in oil and gas wells. This could contribute to accelerate the possibility of geopolymers as a viable sustainable replacement for Portland cement especially in shallow and low-temperature well-cementing applications.

Stabilization of river dredged sediments by means of alkali activation technology

PurposeAlkali activation process has been applied to fresh river clay-rich sediments in order to increase their mechanical properties and make them suitable for soil stabilization.Materials and methodsDredged sediments were mixed with up to 30 mass percent (ma%) of fly ash (FA) or ladle slag (LS) and after curing for 3 days at 60 °C, the bending and compressive strength have been determined. The mixtures which exhibited the highest strengths were further optimized for being used in soil stabilization. For this purpose, the sediment was stabilized with 4 ma% of quicklime (QL) and after 1 h 30 ma% of FA with alkali activator was added and cured for 1, 7 and 28 days.ResultsThe stabilized sediment has a significantely better geomechanical performance in comparison with the sediment alone. Stabilizing the dredged sediment using alkali activation technology provides high enough strengths to eventually make it suitable for anti-flood embankments.ConclusionsThe results confirmed the suitability of the investigated technology for soil stabilization.

Penggunaan Kapur Tohor dan Abu Vulkanik pada Bata Ringan Terhadap Berat Jenis, Daya Serap Air, dan Kuat Tekan

Light brick is a material commonly used in building walls besides red brick. Quick lime and volcanic ash were used in this research as substitute materials for making CLC lightweight bricks. This research aims to analyze using quicklime as a cement substitute and volcanic ash as a sand substitute to test density, water absorption capacity, and compressive strength. Light brick testing refers to the SNI standards for wall masonry. This research also compares the production costs of substitute lightweight bricks with conventional ones. The method used is quantitative experimentation and data analysis techniques using regression analysis. The influencing variable in this research is the independent variable, namely the use of volcanic ash: quicklime in variation A 0%: 0%, variation B 9%: 15%, variation C 9%: 30%, and variation D 9%: 45%. Based on the test results, it can be concluded that using volcanic ash affects increasing density and compressive strength and reduces the value of water absorption capacity. The optimum test results were in Variation D with an average density value of 956 kg/m3, water absorption value of 17%, and compressive strength value of 2.08 MPa.

Insights for Soil Improvements: Unraveling Distinct Mechanisms of Microbial Residue Carbon Accumulation under Chemical and Anaerobic Soil Disinfestation

Soil disinfestation has been widely used as an effective strategy to improve soil health and crop yield by suppression of soil-borne plant pathogens, but its effect on soil organic carbon (SOC), a crucial factor linked to climate change, remains unknown. A microcosm trial was conducted to evaluate microbial residue carbon (MRC) and its contribution to SOC under chemical soil disinfestation (CSD) with quicklime (QL) and chloropicrin (CP), as well as anaerobic soil disinfestation (ASD) with maize straw (MASD) and soybean straw (SASD). The SOC concentrations were increased by both CSD and ASD. Also, total SOC-normalized MRC concentration was enhanced, with a considerable increase in soil bacterial and fungal MRC, particularly evident under CP and SASD treatment. Due to broad-spectrum biocidal activities, decreased SOC-normalized microbial biomass carbon (MBC) was consistent with the reductions in bacterial and fungal phospholipid fatty acids (PLFAs), consequently increasing MRC accumulation under CSD. Similarly, ASD decreased fungal PLFAs while shifting bacterial PLFAs from aerobic to anaerobic taxa or from gram-negative to -positive taxa, both of which contributed to both MBC and MRC buildup. Collectively, the findings demonstrate that ASD can efficiently increase SOC concentration, with distinct mechanisms underlying MRC generation when compared to traditional CSD.

Characterization and utilization capabilities of industrial wastes for green bricks production

BackgroundThe goal of this study is to develop a feasible and sustainable solution to manage the use of industrial wastes of ground granulated blast-furnace steel slag (GGBS) activated by cement kiln dust (CKD) and quicklime (QL). Using activated GGBS in the manufacture of stabilized green bricks is still uncommon in Egypt in such applications. Five clay-based mixtures, each with varying replacement ratios (5–10, wt.%) of CKD and QL, were studied. Laboratory tests were conducted on cylindrical specimens made from these mixtures, which were left to cure for periods of up to 60 days. The raw materials and lab-made specimens were analyzed using particle size analysis, differential thermal analysis, X-ray fluorescence, and X-ray diffraction techniques. The physical and mechanical properties of the cured specimens were also determined and evaluated according to standard specifications. Furthermore, the durability of the cured specimens was evaluated against collapsibility in water.ResuItsIt has been observed that adding QL and CKD to the stabilized green specimens of different mixes can enhance their engineering properties with curing age increasing. This is due to the pozzolanic reaction, which fills the pore structure with calcium silicate hydrates and calcium aluminate hydrates gel. The ratio of QL and CKD used significantly affected the engineering properties of the specimens. The study found that using 20% GGBS and 5% QL led to an increase in compressive strength (266 kg/cm2) at the density of (2.15 g/cm3), while also water absorption was reduced (8%) to give superior results. When GGBS and CKD were combined, a higher content of CKD (10 wt.%) gave better results compared to (5 wt.%) CKD. Furthermore, the physical and mechanical properties of the tested specimens (MD 1, MD II, MD III and MD IV) met the acceptable limits of dry compressive strength (30–70 kg/cm2), water absorption (8–15%), and density (1.7–2 gm/cm3), as specified by the Egyptian standard specifications for buildings used compressed earth blocks.ConclusionThe CKD and QL act as alkali activators for GGBS and can be utilized in masonry construction.

Effectiveness of lime kiln dust on swelling of subgrade expansive soil

BackgroundThe structure of flexible or rigid pavement built on expansive subgrade soil that has a volumetric change is vulnerable to many problems that might cause failure. Pavement and construction became more durable and economical by enhancing the quality of subgrade expansive soil. Solid waste recycling has become very popular recently as a means of attaining sustainable waste management, so using lime kiln dust (LKD), which is a by-product of quick lime production, to treat expansive soil in pavement subgrades. This research describes the effect of LKD on the chemical composition, strength, and swelling of high and low-plastic clay that were extracted from two sites. The minimum LKD required for treating expansive soils was determined by using the Eades and Grim pH test. From tests, it was found that the addition of LKD increased the shrinkage limit by a range (250–500)% and decreased the plasticity and swelling potential by between (50 and 100)% of expansive subgrade soils. The strength according to CBR, increased approximately by 150% for CL soil and 800% for CH soil.ResultsThe optimal percentage of LKD for CH soil is 6%, and for CL soil, it is 2%. The plastic limit increased by 50% for CH soil at 6% LKD. On the other hand, CL soil became non-plastic at 4% LKD. With an increase in the percentage of LKD, it led an the increase in the shrinkage limit by 500% in CH soil and 250% in CL soil. The free swell decreased by 50% in CH soil and 100% in CL soil. The swelling pressure decreased by 50% for two expansive soils. CBR increased by 800% in CH soil and by 150% in CL soil.ConclusionThis work found that the addition of LKD improves the physical, chemical, and mechanical properties of expansive subgrade soil.

Quicklime-stabilized Tuff and Clayey Soils for Highway A3 Construction in Northern Tunisia

This study presents a comprehensive examination of the effects of quicklime (QL) addition on the stabilization of two distinct clayey soils with high (CH) and low plasticity (CL-tuff). The results showed that incorporating QL into the soils substantially improves their stabilization characteristics. Specifically, the addition of QL results in a notable decrease in the final water content of both soils, as shown by a reduction from 23.04 to 19.06% in CH and from 18.07 to 17.1% in CL-tuff at 4% QL addition. Furthermore, this study reveals a transformation in the plasticity properties of soils. Liquid Limit (LL) and Plasticity Index (PI) were reduced, with CH-tuff exhibiting a significant decrease in PI from 48 to 12 and an increase in Plastic Limit (PL) from 21.8 to 55 at 4% QL. CL-tuff also showed reduced plasticity, with PI decreasing to 8.33 at 4% QL. Additionally, the Immediate Bearing Index (IBI) was improved for both soil samples, indicating improved load-bearing capacities. For CH samples, IBI improved from 6.37 to 11.99 at 4% QL addition, while for CL-tuff, it increased dramatically from 4.5 to 23.6 for the same QL percentage. The findings underscore the effectiveness of QL in improving soil properties crucial for chemical stabilization, providing evidence that QL addition can be a key technique in soil stabilization, especially for soils with high plasticity or those requiring increased bearing strength.

Burnt lime: effectively and safely

Burnt lime: effectively and safely

Environmental impact of concrete containing high volume fly ash and ground granulated blast furnace slag

Concrete production is energy-intensive and has an adverse impact on the environment due to the raw materials involved. Currently, India has abundant reserves of fly ash and ground granulated blast furnace slag (GGBS). Despite various applications, fly ash often ends up in landfills. Given its abundance, there is a growing interest in utilising substantial quantities of fly ash in concrete production. In the current study, M30-grade concrete is designed with very high levels of fly ash and GGBS. Additionally, quick lime (QL) is incorporated as a supplementary agent to augment lime content. A total of twenty concrete mixes have been developed with different combinations of fly ash, GGBS, and QL. Results illustrate that the addition of QL does not show overall strength improvement to the GGBS-based mixes, but it impacts on fly ash-based mixes. The targeted design strength is achieved with 70% cement replacement with fly ash and QL. The strength development depends on the pozzolanic reaction initiated and the formation of hydration products in the system. The environmental impact of concrete is assessed by analysing its life cycle assessment using a cradle-to-gate approach. The energy requirement and kg-CO2 eq. emissions depend on the level of cement replacement. The fly ash-based concrete emits less kg-CO2 eq. and requires less energy than the GGBS-based mixes. Overall, the designed strength is achieved with 65% fly ash, requiring 59% less energy, reducing 54% CO2 footprint, 56% GWP100, 80% HTPinf, 46% ODPinf, and cost by 34% compared to OPC-based concrete.

Application of ANN in Construction: Comprehensive Study on Identifying Optimal Modifier and Dosage for Stabilizing Marine Clay of Qingdao Coastal Region of China

Nowadays, the use of new compound chemical stabilizers to treat marine clay has gained significant attention. However, the complex non-linear relationship between the influencing factors and the unconfined compressive strength of chemically treated marine clay is not clear. In order to study the influence of various factors (dosage, type of stabilizer, curing age) on the unconfined compressive strength of solidified soil during chemical treatment, experiments were performed to determine the unconfined compressive strength of soft marine clay modified with various types of stabilizers. Further, an artificial neural network (ANN) model was used to establish a prediction model based on the unconfined compressive strength test data and to verify the performance. Sensitivity and optimization analyses were further conducted to explore the relative significance of parameters as well as the optimal dosage amount. Research has found that when the content of aluminate cement is 89.5% and the content of curing agent is 30%, the unconfined compressive strength significantly increases after 28 days of solidification, and the change in quicklime content has the greatest effect on the improvement in the unconfined compressive strength. The influence of modifiers on the unconfined compressive strength is in the order: potassium hydroxide > kingsilica > quick lime > bassanite. The values of each factor were obtained when the unconfined compressive strength was the maximum, which provided support for the optimization of the treatment scheme. The analysis of chemical treatment is no longer limited to the linear relationship according to the test results, which proves the feasibility of non-linear relationship analysis based on the artificial neural network.

Evaluation of Different Agricultural Limes for Bread Wheat and Fababean Production in Acid Soil of West Shewa Zone, Ethiopia

The application of lime is believed to enhance soil health status through improving soil pH, base saturation and reduces Al and Mn toxicities. Liming effects depend on the source, composition, purity and fineness of the lime. The performance of three liming materials and one control treatment was evaluated in a field trial, further evaluation and validation was done at three districts on different farmers’ sites during 2023 main cropping season. The liming materials included calcitic lime, hydrated lime, and quick lime. The treatments laid out in randomized complete block design. The results of the study showed that all tested lime materials (calcitic lime, hydrated lime, and quick lime) improved yield and agronomic performance of wheat, barley and fababean in comparably. This implies that hydrated limes can serve as an alternative agricultural lime to ameliorate soil acidity. Hence, these liming materials can be used as agricultural lime material and the result is confirmed through validation across locations on different testing crops (wheat, barley and Faba bean). So, it is recommended that liming materials which can be easily accessed for the farmers is recommended because of there is no significant difference among liming material tested.

Resisting Material Binaries: Unpacking persisting dichotomies of building materials in Central Africa

The current discourse on African architecture is strongly influenced by social design—a practice for which architecture holds an important role in addressing complex societal questions and problems. The use of “alternative” building materials, as opposed to industrial materials like concrete or steel, is very central within this discourse. However, as this article argues, this strong binary approach to building materials is heavily influenced by colonial and postcolonial logic. To understand this continuity, I will trace some path dependencies visible in the Central African region from the colonial period to the present. In the first section, the material preferences of a Belgian architecture firm working in Rwanda in 2012 are related to the binaries of the architecture firms operating in this region in the 1970s and 1980s. In the second section, I discuss how the strong distinction between so-called “local” and “modern” materials is a remnant of the colonial period. Through an in-depth analysis of the shifting valuations of cement and burnt lime in Central Africa, the article aims to make these colonial categories feel less natural. Building on post-colonial science and technology studies (STS) scholarship, the conclusion proposes an alternative to binary thinking—a conscious material choice that tries to understand building materials as situated processes, allowing to go beyond the industry-driven denominators by which we currently value our building materials.

Bricks, Mud and Lime Mortars in Heritage Restoration: A case study

This paper is based upon an extensive eight-year experience in the restoration of monuments from the World Heritage Site Patan Darbar Square to Tripureshwor Mahadev Temple, Sattals, and Garden Area and the Sama Center, representing historically significant Malla, Shah and Rana period architectures respectively, after the Gorkha earthquake of 2015. These monuments date back from 6th to the 20th century. All structures employ a masonry system as the structural system. The main materials observed in these heritages were burnt clay bricks, stones, mud mortars, and lime mortars. This study examines the technical aspects such as material properties (compressive strength, bending strength, mechanical properties), and composition of mortars according to their use in different locations and types of structures, even within the same building. The study acknowledges the Department of Archaeology’s preservation and monument act, highlighting the potential for material reuse in heritage restoration. The primary aim of this study is to comprehensively understand and analyze the strength of antiquated materials and traditional mortars used in historical construction and restoration. It provides practical recommendations for future preservation efforts.

Impact evaluation of amount of burnt lime, moisture and pellet feed on the sinter fines fraction by utilizing a sintering pilot plant

Impact evaluation of amount of burnt lime, moisture and pellet feed on the sinter fines fraction by utilizing a sintering pilot plant

Production of refining alumina-containing fluxes by sintering from technogenic raw materials

Modern Russian steelmaking plants use predominantly alumina-containing materials for liquefying lime in a ladle-furnace unit, which replaced fluorspar. Alumina-containing materials currently available on the market cannot be used directly in steelmaking without preliminary preparation (refining, heat treatment or briquetting), or are simply unsuitable for ladle processing of steel. This work describes laboratory studies on the production of refining alumina-containing fluxes by sintering in units such as machines for pellets firing or producing agglomerate (in the temperature range of 1200 – 1500 °C) from clean metallurgical waste (fine dust from the production of alumina and burnt lime), meeting the requirements of steelmaking plants by chemical composition and mechanical properties. A comparison was made of sintering technological schemes with the introduction of hydra­ted lime and a mixture of hydrated lime and calcium carbonate in a 1:1 ratio as a source of CaO. We determined that the maximum permissible CaO content in sintered briquettes when using a mixture of hydrated lime and calcium carbonate in the charge, which does not lead to hydration destruction in air, is in the range of 2.3 - 3.6 %, depending on the holding temperature. The maximum permissible content of Al2O3 in sintered briquettes when using hydrated lime in the charge, which does not lead to hydration destruction in air, is in the range of 9.5 – 31.7 %, depending on the holding temperature. In existing fuel units it is possible to obtain fluxes by sintering only when using hydrated lime as a source of CaO, because adding calcium carbonate to the charge (9 – 22 %) requires an increase in holding temperature (above 1500 °C) or holding time (more than 25 min).