Lime Kiln Research Articles

Group of tetradrachmas from the reign of Diocletian discovered at Kom el-Dikka in Alexandria

A set of more than 30 tetradrachmas from the second half of the 3rd century AD was discovered in Alexandria in Egypt, at the Kom el-Dikka site excavated by a Polish mission, in a zone of public buildings constructed in the 4th century AD. A row of lime kilns from the construction site of this complex stood on top of the ruins of an early Roman domestic quarter and, after they ceased to be used, were covered with earth and rubble, the latter partly from the destruction layer of these houses. Excavation of the kilns in 2008 and 2009 produced large quantities of 4th and 5th century pottery as well as pieces of marble revetment that had been fed to the kilns, and isolated late Roman coins. The tetradrachmas from two of the kilns (Fc and Fd), which were hoarded apparently in AD 293–295, seems to have preceded the destruction of the early Roman houses and may have been hidden in one of them.

Influence of electric arc furnace dust and lime kiln waste in Portland cement hydration

Abstract Studies have indicated that the use of electric arc furnace dust (EAFD) results in a delay in the hydration time of Portland cement. Calcium-rich waste such as lime kiln waste (LKW) is one of the techniques used to offset this delay as it accounts for the lack of this element in calcium silicate hydrate (C-S-H) production in the mixture. The objective of this study was to evaluate the influence of electric arc furnace dust (EAFD) and lime kiln waste (LKW) in the hydration process of Portland cement pastes and their influence in setting time and hydration heat. The methodology used required several steps: physiochemical and micro-structural characterization of waste samples; definition and production cement pastes with different levels of waste substitution and a reference paste and evaluation of the cement pastes with respect to setting time and hydration heat. Results showed that the substitution of 1% EAFD with or without LKW presented similar hydration heats as the reference paste. This indicated that EAFD+LKW substitution would not affect substantially the hydration reactions of cement and could allow waste recycling in construction materials.

SOME CHARACTERISTICS OF BUILDING MATERIALS OF ANCIENT KYYIVAN MONUMENTS OF THE X-TH - THE XIІ-TH CENTURIES

The development of brickwork technique in ancient Kyyiv dates back to the X- th century. Old Rus` monuments’ masonry was made of large thin bricks called “plynfa” and lime-and-ceramic mortar. The size of the X-th – the XII-th brick sides varies from 27 to 36 cm, its thickness – from 2.5 to 4.5 cm.
 Different kinds of clay and loess extracted from the territory of Kyyiv and its vicinities were used as a raw material for brick and ceramic addition to mortar. That is why bricks in Kyyivan monuments differ in colour from light yellow to orange and dark red. Some gruss or cut straw were used as addition to fat clay.
 Limestone was brought to Kyyiv from Chernihiv area and lime mortar was produced in lime kilns situated near building sites. Ceramic addition to mortar called “tsemianka” was of refined clay, and crushed brick waste was used as well.
 Bricks were burnt under the temperature of 1000 – 1200 degrees C. That’s why bricks were very firm regardless of chink-like pores appeared as a result of hand-moulding of brick.
 The author took some investigation for the purpose to determine physical and mechanical properties of ancient bricks of Kyyivan monuments. Bricks were picked out of excavations or waste after building repairs. Small cubes were cut out of bricks with the height equal to brick thickness. Those samples were examined concerning their strength by compressing them perpendicularly to the sides the bricks were bedded in mortar.
 The strength of samples varied from 100 to 200-300 kg per sq.cm, water absorption was 10 % to 20 %. Some bricks taken from the Cathedral of the Assumption of Kyyiv-Pechersk monastery were the most firm. The strength of those samples was about 400-500 kg per sq. cm, their water absorption was the smallest, about 5.6 %.
 Because of high porosity and water absorption of building materials the surface of ancient masonry was exposed to destruction under the influence of temperature overfalls and precipitation, as it can be seen on the open parts of walls of the Old Rus` monuments. To prevent destruction of masonry, the walls of ancient monuments were covered with fine lime-and-ceramic mortar. Fragments of original plaster can be found on the walls of the XI-th century monuments St.Sophia Cathedral and St.Michael Church of Vydubychy monastery in Kyyiv.
 High level of well-developed building technique and high quality of building materials caused durability of ancient masonry and constructions in Kyyivan monuments, which preserved until nowadays.

Treatment of Exhaust Pollutants from a Lime Kiln of Paper-mill with Micro-bubble System

Treatment of Exhaust Pollutants from a Lime Kiln of Paper-mill with Micro-bubble System

Sulfur Recovery from Syngas in Pulp Mills with Integrated Black Liquor Gasification

Research Highlights: As to fill the current knowledge gap and to deliver important findings to the scientific community, efficient sulfur recovery from black liquor gasifier syngas, comprising both gas cleaning and returning sulfur to the pulping process, was modeled and assessed from a techno-economic viewpoint. This manuscript proves that the associated investment and operational costs cannot be neglected and that they impact the black liquor gasification feasibility significantly. To prove its gasification as a sustainable and more efficient processing route over its combustion in recovery boilers, a substantial process efficiency improvement and operating costs reduction must be targeted in future research. Background and Objectives: Sulfur compounds found in black liquor partly turn into hydrogen sulfide during gasification and exit the gasifier in the syngas. Their efficient recovery in their sulfidic form to the pulping process is of utmost importance. Current studies focus on black liquor gasifier syngas desulfurization only. Materials and Methods: A mathematical model of two H2S absorption units from a 66.7 tDS/h (1600 tons dry solids per day) black liquor gasification process to 20 ppm H2S content in cleaned syngas using either white liquor plus NaOH or N-methyldiethanolamine (MDEA) was created using the Aspen Plus simulation software. Results: The results show that CO2 co-absorption significantly increases the lime kiln load: +20% in the MDEA alternative and +100% in the other one. The MDEA alternative requires almost the same investment costs but by around USD 9.7 million (>50%) lower annual operating costs compared to the other one. Economic evaluation was based on the assumed discount rate of 5% and on the expected plant operation time of 25 years. The estimated total investment cost of the whole plant is around USD 170 million for both alternatives. The whole plant including this alternative exhibits a positive net present value (over USD 19 million), an internal rate of return of 5% and a profitability index of 1.12, whereas that with the other alternative is economically infeasible. Conclusions: The MDEA-based syngas cleaning technology represents a more efficient and economically feasible option of sulfur recovery. A major drawback of both modeled syngas cleaning technologies is that their estimated annual operating costs significantly reduce the expected profit margin of gasification over the traditional black liquor combustion in a recovery boiler. Syngas cleaning and sulfur recovery have to be further optimized to reach a significant cut down in operational costs to improve the economic feasibility of black liquor gasification.

Investigation of hard-burn and soft-burn lime kiln dust as alternative materials for alkali-activated binder cured at ambient temperature

As climate change becomes a severe concern, the development of green technology becomes a goal for many sectors, including the construction material sector. Ordinary Portland cement (OPC), the main constituent of concrete production, is a primary contributor to releasing carbon dioxide (CO2) into the atmosphere. Some alternative cementitious materials have been studied to reduce the massive amount of OPC consumption. Lime kiln dust (LKD), a by-product of quicklime production, is produced in abundance worldwide and mostly disposed of in landfills. The two types of LKD, soft-burn and hard-burn, are high-potential wastes that can be developed as alternative cementitious binders using the alkali-activated binder (AAB) technology. This study investigates the mixture designation and properties of LKD-based AAB when cured at ambient temperature. The results show that an ambient-cured soft-burn LKD-AAB achieved practical workability with an 8 M NaOH solution, 1.50 of sodium silicate-to-sodium hydroxide ratio (SS/SH), and 0.60 of liquid alkaline-to-binder ratio (L/B). A rapid setting behavior and an excellent compressive strength of 10.89 MPa at 28 days were revealed at room temperature curing. The ambient-cured hard-burn LKD-AAB could not provide the appropriate properties. However, the mixture of 20% hard-burn LKD and 80% soft-burn LKD resulted in an LKD-AAB mixture that meets the minimum requirement for low-strength cement applications. The positive outcome of this study may be the solution for of LKD wastes utilization in Thailand that addresses the challenge of developing ambient-cured AAB for in-field applications.

Developing one-part alkali-activated metakaolin/natural pozzolan binders using lime waste

Among the several schemes that have been reported to be a satisfactory alternative to Portland cement is alkali-activated cement, which has recently started to receive greater consideration in construction sectors. Conventional two-part alkali activation has many drawbacks, including that the activating solution is viscous, problematic and is not user friendly to handle. Thus, the aim of this research is to produce a one-part alkali-activated metakaolin/natural pozzolan, by using an earth alkaline source (rich in calcium oxide) from waste material (lime kiln dust), as an activating precursor to break the alumina-silicate crystalline phases. Thermal treatment of materials at two levels of treatment (450°C and 950°C) was used as an assisted activation approach. Analytical techniques, including X-ray powder diffraction, thermogravimetric analysis, Fourier transform infrared spectroscopy and scanning electron microscopy, were utilised to investigate the performance of the developed materials at a molecular level. Reduction of crystalline peaks, as well as the appearance of new wollastonite minerals within the calcined lime kiln dust, contributed to the development of 27 MPa compressive strength after 28 days. The dissolution that occurred through the pozzolanic reaction as well as thermal treatment evidently contributed to transform crystalline to amorphous phases.

Upcycling Potential of Industrial Waste in Soil Stabilization: Use of Kiln Dust and Fly Ash to Improve Weak Pavement Subgrades Encountered in Michigan, USA

The State of Michigan in the United States often encounters weak soil subgrades during its road construction and maintenance activities. Undercutting has been the usual solution, while a very few attempts of in-situ soil stabilization with cement or lime have been made. Compared to the large volume of weak soils that require improvement and the cost incurred on an annual basis, some locally available industrial byproducts present the potential to become effective soil subgrade stabilizers and a better solution from the sustainability perspective as well. The candidate industrial byproducts are Cement Kiln Dust (CKD), Lime Kiln Dust (LKD), and Fly Ash (FA), out of which only a fraction is currently used for any other secondary purposes while the rest is disposed of in Michigan landfills. This manuscript describes a laboratory investigation conducted on above industrial byproducts and/or their combinations to assess their suitability to be used as soil subgrade stabilizers in three selected weak soil types often found in Michigan. Results reveal that CKD or a combination of FA/LKD can be recommended for the long-term soil subgrade stabilization of all three soil types tested, while FA and LKD can be used in some soil types as a short-term soil stabilizer (for construction facilitation). A brief discussion is also presented at the end on the potential positive impact that can be made by the upcycling of CKD/LKD/FA on sustainability.

Granulated biofuel ash as a sustainable source of plant nutrients.

Recovery of nutrients from biomass combustion ash is of great importance for sustainable bioenergy waste use. In this work, granulated fertilizer materials were engineered from biofuel bottom ash, lime kiln dust and water, analysed for their chemical complexity and tested in pot experiments (2017-2018) for their propensity to release nutrients. The results obtained in this work showed that spring barley yield was observed to be the highest for granulated biomass ash with 30% of ash in the granule. The yield increased 3.99 t ha-1 per 100 kg ha-1 potassium oxide (K2O) in 2017 and 1.23 t ha-1 per 100 kg ha-1 K2O in 2018. Straw yield varied between 1.39-5.08 t ha-1/100 kg ha-1 in 2017 and 0.36-1.23 t ha-1/100 kg ha-1 in 2018. Calcium concentration significantly increased in soil. No significant changes in soil mobile phosphorus (P) were obtained as well as for the heavy metal concentrations in soil. This suggests that biofuel ash can be a significant source of certain major nutrients for crops that can also beneficially affect soil pH. The results of this work can provide policy-makers with the information needed to diversify existing and enable new biomass bottom ash utilization routes which currently vary significantly between the countries.

Long-term performance of novel high-calcium one-part alkali-activated cement developed from thermally activated lime kiln dust

The traditional activation approach for alkali-activated cement AAC has several problems resulting mainly from the hazardous and corrosiveness of the alkaline chemicals, such as (NaOH, Na2SiO3), which in turn impede the utilisation of AAC in the construction fields. In this study, A second generation of alkali activated binder was developed using Metakaolin (MK) and natural pozzolan material (NP) (as a source of alumina-silicate), these materials were activated using high-calcium lime kiln dust as solid activator to transform the alumina-silicate crystalline phases to cementitious hydrated products. This was achieved with the aid of heat treatment of materials at different temperatures. Raw materials and final AAC samples were characterised using analytical methods, such X-Ray powder diffraction (XRD), Thermogravimetric Analysis (TG-DTA), Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscope (SEM). Additionally, long-term compressive strength, chemical and microstructural performance were investigated. The transformation of raw materials from crystalline to amorphous phases happened due to the effect of the heat treatment and the formation of stratlingite products in the final AAC paste, which were evidenced using the mentioned characterisation methods. The findings of the present study proved that the compressive strength of the new binder reached 27 MPa and 51 MPa after 28 and 180 days of curing, respectively, ensuring a progressive as well as a higher degree of alkali-activation and disappearance of unreacted alkaline substances in the final AAC products.

Lime kiln conversion from coke to natural gas operation – an option in direction of sustainable energy

This paper deals with the conversion of coke fired lime kilns to gas and the conclusions drawn from the completed projects. The paper presents (1) the decision process associated with the adoption of the new technology, (2) the necessary steps of the conversion, (3) the experiences and issues which occurred during the first campaign, (4) the impacts on the beet sugar factory (i.e. on the CO2 balance and exhaust gas temperature), (5) the long term impressions and capabilities of several campaigns of operation, (6) the details of available technologies and (7) additional benefits that would justify a conversion from coke to natural gas operation on existing lime kilns. (8) Forecast view to develop systems usable for alternative gaseous fuels (e.g. biogas).

Physicochemical Characterization of Pelletized Lime Kiln Dust as Potential Liming Material for Acidic Soils

Lime kiln dust (LKD) is a fine particulate material by-product produced during the lime burning processes. Current reuse options are chiefly focused on reuse in the cement industry which are limited by the inherent porosity of this by-product. Due to the presence of calcium (Ca), magnesium (Mg) and other elements which can serve as micronutrients to the plants, LKD has the potential to be used as a replacement for conventional liming materials for both soil pHKCl increase and plant supplement with secondary major- (Ca and Mg) and micronutrients (Mn, Cu, Zn and Ni). The work described here outlines the investigation of physicochemical properties of pelletized LKD materials and their effect on soil pHKCl, available Ca and Mg content in the soil as well as straw and grain yields of spring barley. LKD were analyzed using X-ray diffraction, scanning electron microscopy with energy dispersive analysis, while detailed chemical analysis of both pelletized LKD and soil was performed using Atomic Absorption Spectroscopy. Pellet size and major element composition were used as chief indicators for the liming capacity of LKD. It was shown that low acidic soil (pHKCl 5.4) can be conditioned using fine (0.1–2 mm) pelletized LKD due to the high release rates while coarse pellets (5–8 mm) did not significantly increase available Ca and Mg content in soil and did not reach optimum pHKCl range even after 48 weeks. The highest application rate of LKD at 4 t/ha increased spring barley grain yield compared to control but the increase was not statistically significant. Thus, pelletized lime kiln dust could be a potential alternative to natural limestone or dolomite minerals as liming material for acid soils with the pellet size determining the liming kinetics.

Alternative “green” lime kiln fuels: Part II—Woody biomass, bio-oils, gasification, and hydrogen

This paper is the second of a two-part series on “green” lime kiln fuels. The first part of this work reviews the use of pulp mill and recovery byproducts as either full or partial replacement of oil or natural gas in the kiln. The second part reviews the use of various forms of woody biomass, bio-oils, gasification and hydrogen as potential carbon neutral or carbon-free lime kiln fuels. Several of these options require specialized burners to supply the fuel to the kiln and high-quality metallurgy to withstand the acidic conditions of the fuel.

Alternative “green” lime kiln fuels: Part I—Pulping/recovery byproducts

This paper is the first of a two-part series on “green” lime kiln fuels. The first part of this work reviews the use of pulp mill and recovery byproducts as either full or partial replacement of oil or natural gas in the kiln. The second part reviews the use of various forms of woody biomass, bio-oils, gasification, and hydrogen as potential carbon neutral or carbon-free lime kiln fuels.

Estimation of energy efficiency of kraft pulp production with the exergy increment method

This article contains results of exergic analysis of kraft pulping flow chart. The results of exergic balances of main kraft pulping processes such as alkali recovery at recovery boilers, black liquor evaporation, chips cooking, lime decarbonation are considered in details in the article. The analysis of the process flow chart makes it possible to determine the bottlenecks in the use of heat energy and to substantiate principal lines for increasing energy efficiency of the processes under study. A main share of the exergy expended in the existing pulping process is due to alkali recovery in the recovery boiler and comprises 70% of the total exergy available in the system. A procedure of hydrothermal production of chemicals in the process of kraft pulping is studied. A schematic diagram and analysis of heat technique of the kraft pulping process which in fact consists of organic component removal from black liquor through its autoclave carbonation with flue gases releasing from lime kiln at the temperature 80-90 oC are given in the article. The removal of organic components under these conditions can reach 70 %. In the studied version the exergic efficiency ηe = 80 % is considerably higher than that of the flow chart existing for chemicals recovery which is equal to ηe = 48 %. This is the evidence of high energy efficiency of the method developed.

Geoenvironmental behavior of lime-treated marine sediments

Several hundred million cubic meters of sediment are dredged from various U.S. ports, harbors, and waterways annually to maintain and improve the nation’s navigation system for commercial, national defense, and recreational purposes. The United States Environmental Protection Agency mandated containment of dredged sediments in designated containment facilities. The current study aims to explore the use of sediments dredged from Baltimore Harbor as a potential highway embankment material. Lime-based additives have been added to the dredged material and geotechnical analysis is coupled with environmental assessment in this study. Long-term sequential column leaching test results showed that aluminum, arsenic, nickel, cobalt, and zinc leached from the dredged sediments, but the metal concentrations quickly decreased to EPA water quality limits for protection of aquatic life and human health in freshwaters. Addition of lime kiln dust and quick lime lowered the amount of metals leaching from the material. Contaminant concentrations originating from the dredged sediment in an embankment are reduced up to 80 times in surface waters and decreased to negligible levels upon reaching groundwater.

Fate of phosphorus in the recovery cycle of the kraft pulping process

The accumulation of nonprocess elements in the recovery cycle is a common problem for kraft pulp mills trying to reduce their water closure or to utilize biofuels in their lime kiln. Nonprocess elements such as magne-sium (Mg), manganese (Mn), silicon (Si), aluminum (Al), and phosphorus (P) enter the recovery cycle via wood, make-up chemicals, lime rock, biofuels, and process water. The main purge point for these elements is green liquor dregs and lime mud. If not purged, these elements can cause operational problems for the mill. Phosphorus reacts with calcium oxide (CaO) in the lime during slaking; as a result, part of the lime is unavailable for slaking reactions. The first part of this project, through laboratory work, identified rhenanite (NaCa(PO4)) as the form of P in the lime cycle and showed the negative effect of P on the availability of the lime. The second part of this project involved field studies and performing a mass balance for P at a Canadian kraft pulp mill.

Geochemical behavior and stabilization of spent sulfate-reducing biofilter mixtures for treatment of acid mine drainage

Sulfate-reducing biofilters operated in semi-passive or passive modes constitute an approach of choice for treatment of acidic mining effluents. The aim of the present study involved examining the behavior of biofilters after use based on two modes of management, namely in unsaturated and saturated media. Two acidophilic biofilters were investigated following their mixing with different alkaline industrial residues (i.e., 25% fly ash biomass or 30% aluminum red mud, or 10% kiln dust). Percolation column tests for a 330-d period indicated that aluminum red mud and lime kiln dust (to a lesser extent) are efficient materials for maintaining the pH neutrality of biofilter leachate and to reduce release of metals (i.e., Al, Cd, Cr, Cu, Fe, Mn, Ni, Pb, Zn) in spent biofilters. The storage of biofilters in saturated mode also makes it possible to preserve the reducing conditions of the environment and neutrality of the pH and to limit the dissolution of the solution of cadmium, nickel and zinc. Conversely, increased iron release is noted under saturated conditions. Finally, the results indicated that a mixture of biofilters and lime kiln dust is preferable to surface addition of these to reduce the loss of metals in leachates.

Effect of Lime Kiln Dust on Kaolin-Slag Mixture

Soil stabilsation is one of the area which needs further research due to its importance both geotechnical and environmentally. Application of landfill materials and turn them into something worthwhile has been in attention of researchers. Lime Kiln Dust (LKD) is one of the materials which shows a potential of usage into soils. On other hand, Unconfined Compressive Strength (UCS) is also one of important tests in soil mechanics to represent characteristic of soil. Surely, in order to run UCS testing, compaction tests was conducted. The compaction values then utilized in the preparation of UCS samples. This study considers the effect of lime kiln dust on the UCS behavior of kaolinite-slag mixture. Compaction and UCS testing were conducted. The results showed that OMC was increased with increasing LKD in kaolinite-slag mixture and MDD was decreased with increasing in kiln dust. UCS also found to be with increasing in kiln dust. The results was support with different curing time (i.e. 7, 28, 90).

Glass finds and other artifacts from excavations of Area FW at the Kom el-Dikka site in Alexandria in 2018

Excavations in 2018 of the central part of the Kom el‑Dikka site in Alexandria (Area FW) produced a collection of glass finds representing two broadly defined chronological horizons. The set from an early Roman house in the lower layers of the sector is representative of the early and mid‑Roman period (1st–3rd centuries AD) and is significant in that it broadens the known repertoire of vessels forms from the site in general. Examination of the context has also provided further firm archaeological evidence of gold-in-glass bead manufacture at the site. The upper layers, associated with an extensive dumping of ashes from the nearby late antique bath and waste from the working of a complex of lime kilns situated in this area, yielded material typical of late Roman/early Byzantine glasses (4th–6th century AD) already known from the site and comprising mainly simple free-blown utilitarian wares with limited ornamentation.