Lime Sources Research Articles

Effects of Mg compounds in hydroxylated calcined dolomite as an effective and sustainable substitute of lime to precipitate as ettringite for treatment of selenite/selenate in aqueous solution

The elevated level of selenium (Se) in the aqueous system presents long-term ecological risks. Hydroxylated calcined dolomites (HCDs) are considered as potentially sustainable lime sources due to their lower production temperatures and resourceful than lime. In this study, HCDs were developed for the removal of Se contaminated water. The HCDs exhibited a better performance to co-precipitate with Se oxyanions than pure Ca(OH)2. Considering that HCDs consisted of Ca(OH)2 with MgO and Mg(OH)2, the function of Mg compounds was also elaborated by various characterization techniques. Mg compounds were proved to enhance the precipitation process and Se removal. STEM-EDX observation revealed that SeO32– was incorporated into the ettringite structure with Mg compounds, whereas SeO42– exhibited a affinity to Mg compounds. Extended X-ray absorption fine structure (EXAFS) results for the MgO/Mg(OH)2 after the reaction proved that both SeO32– interacted with Mg(OH)2 and MgO via inner-sphere complexes whereas SeO42– formed outer-sphere complexes with these Mg compounds. Besides, Mg compounds also influenced the surface charge of solid residues and thus enhanced SeO32– removal. This study provides a fundamental understanding of the roles of Mg compounds in the removal of Se oxyanions during environmental remediation. Besides, the HCDs were proved to be sustainable Ca sources for waste/wastewater remediation.

Microstructure Analysis and Chemical and Mechanical Characterization of the Shells of Three Freshwater Snails.

The shells of freshwater snails are discarded as waste, which qualify as biological materials with prospective multiple uses. To substantiate this proposition, an attempt was made to elucidate the physical and chemical properties of the shells of three freshwater snails, namely, Bellamya bengalensis, Pila globosa, and Brotia costula. The shells were prepared for electron microscopy and assessment of the calcium carbonate content, apart from the Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS), and nanoindentation studies. The results indicated that the calcium carbonate content (y) of the shells ranged between 87 and 96% of the total weight (x) and complied with a power regression equation: y = 0.801x1.016; R2 = 0.994; r = +0.998; P < 0.001. Observations through SEM depicted different snail species-specific arrangement patterns of calcium carbonate crystals in the diverse layers of shells. The XRD, FTIR, and EDS observations revealed the dominance of the aragonite form of the calcium carbonate crystal in the microstructures of each snail shell with the occurrence of different shell surface functional groups. The Brunauer–Emmett–Teller analysis elucidated the surface textures of shell dust taken from each snail species; in addition, the nanohardness properties indicate the shells as a tough biocomposite exoskeleton. Species-specific variations in the shell morphology, microstructure, and calcium carbonate content were prominent for the three freshwater snails considered for the study. Nonetheless, the physical and chemical properties substantiate that the shells of B. bengalensis, P. globosa, and B. costula qualify as biological materials for sustainable use in various fields including bioremediation, biocatalyst, biomedical applications, and a source of lime. Since the shells of the freshwater snails are discarded as aquaculture waste, subsequent use as a biological material will support the “waste made useful” paradigm in sustainability, both from ecological and economic perspectives.

Investigation of Azospirillum brasilense Inoculation and Silicon Application on Corn Yield Responses

New management practices are needed to help improve the inoculation efficiency of plant growth-promoting bacteria (PGPB). The use of silicon (Si) combined with PGPB can be a useful and sustainable strategy to enhance cereal development under tropical conditions. This research was developed to investigate inoculation methods with Azospirillum brasilense combined with Si application as a soil amendment in corn. The effects of Si application and A. brasilense inoculation on plant development and yield were tested on corn for two consecutive years. The study was set up in a Rhodic Hapludox under a no-till system in a completely randomized block design with four replicates. Treatments were tested in a full factorial design (triple factorial 4 × 2 × 2) and included (i) 4 inoculation methods (control, seed, in-furrow, and leaf), (ii) two lime sources (calcium and magnesium silicate and dolomitic limestone), and (iii) two study years (2015/2016 and 2016/2017). Our results showed that seed and in-furrow inoculation were more effective in promoting corn development and greater yield, with an increase of 10.6 and 7.3% in corn grain yield, respectively. Silicate application combined with seed inoculation increased shoot N uptake and root biomass. Also, Si application increased leaf chlorophyll index, stem diameter, and had similar effects on soil properties compared with limestone. Our results showed positive effects on corn growth and productivity as a result of inoculation, while the potential benefits of Si use were less evident.

Comparative study on utilization of different types of municipal solid waste incineration bottom ash for clinker sintering

In this study, two types of municipal solid waste incineration (MSWI) bottom ash (BA) (MSWI-BA-A, water quenched, MSWI-BA-B, natural cooling), are utilized as alternative materials for clinker sintering. Fixed clinker modulus (lime saturation ratio = 0.90 ± 0.01, silica modulus = 2.6 ± 0.1 and alumina modulus = 1.5 ± 0.1), designed gradient addition ratio of MSWIBA (0, 3%, 6%, 9% and 12%) and same sintering temperature (1723.15 K) are adopted to conduct the experiments. Raw materials are characterized by XRF, X-ray diffraction and differential thermal analysis. Clinkers are analyzed and evaluated by XRF, X-ray diffraction, petrographic analysis, compressive and flexural strength tests and toxicity characteristic leaching procedure. The major difference of the two types of MSWIBA is LOI value which is supposed to be the most probable reason for huge difference between liquid phase formation temperature variation and incremental introduction of MSWI. MSWI-BA-A increases liquid phase formation temperature. Liquid phase formation temperatures and MSWI-BA-B samples addition ratios nearly present negative linear correlation. All clinkers sintered with addition of MSWIBA slightly reduce water demand for normal consistency. MSWIBA addition poses relatively obvious influence on initial setting time and little effect on final setting time. There is an increase in initial strength and a decrease in 28-day strength of clinkers sintered with MSWIBA, 28-day compressive strength decreases with the incremental introduction of MSWIBA. Distinct characteristics, such as free lime, periclase, orthorhombic tricalcium aluminate (C3A) crystal and secondary Belite crystal, are observed by petrographic analysis. MSWIBA is significant source of free lime and periclase in clinkers. Incremental input of alkali introduced by MSWIBA influences clinker sintering and mineral crystallinzation, further results in orthorhombic C3A crystal and indistinct Alite edge caused by corrosion. Leaching concentration of heavy metals from mortars prepared with the sintering clinkers is lower than corresponding concentration of the Chinese National Standard GB 30760-2014.

Inoculation of Azospirillum brasilense associated with silicon as a liming source to improve nitrogen fertilization in wheat crops

This research was developed to investigate whether inoculation with Azospirillum brasilense in combination with silicon (Si) can enhance N use efficiency (NUE) in wheat and to evaluate and correlate nutritional and productive components and wheat grain yield. The study was carried out on a Rhodic Hapludox under a no-till system with a completely randomized block design with four replications in a 2 × 2 × 5 factorial scheme: two liming sources (with Ca and Mg silicate as the Si source and limestone); two inoculations (control - without inoculation and seed inoculation with A. brasilense) and five side-dress N rates (0, 50, 100, 150 and 200 kg ha−1). The results of this study showed positive improvements in wheat growth production parameters, NUE and grain yield as a function of inoculation associated with N rates. Inoculation can complement and optimize N fertilization, even with high N application rates. The potential benefits of Si use were less evident; however, the use of Si can favour N absorption, even when associated with A. brasilense. Therefore, studies conducted under tropical conditions with Ca and Mg silicate are necessary to better understand the role of Si applied alone or in combination with growth-promoting bacteria such as A. brasilense.

Can silicon applied to correct soil acidity in combination with Azospirillum brasilense inoculation improve nitrogen use efficiency in maize?

Alternative management practices are needed to minimize the need for chemical fertilizer use in non-leguminous cropping systems. The use of biological agents that can fix atmospheric N has shown potential to improve nutrient availability in grass crops. This research was developed to investigate if inoculation with Azospirillum brasilense in combination with silicon (Si) can enhance N use efficiency (NUE) in maize. The study was set up in a Rhodic Hapludox under a no-till system, in a completely randomized block design with four replicates. Treatments were tested in a full factorial design and included: i) five side dress N rates (0 to 200 kg ha-1); ii) two liming sources (Ca and Mg silicate and dolomitic limestone); and iii) with and without seed inoculation with A. brasilense. Inoculation with A. brasilense was found to increase grain yield by 15% when N was omitted and up to 10% when N was applied. Inoculation also increased N accumulation in plant tissue. Inoculation and limestone application were found to increase leaf chlorophyll index, number of grains per ear, harvest index, and NUE. Inoculation increased harvest index and NUE by 9.5 and 19.3%, respectively, compared with non-inoculated plots. Silicon application increased leaf chlorophyll index and N-leaf concentration. The combination of Si and inoculation provided greater Si-shoot accumulation. This study showed positive improvements in maize growth production parameters as a result of inoculation, but the potential benefits of Si use were less evident. Further research should be conducted under growing conditions that provide some level of biotic or abiotic stress to study the true potential of Si application.

Sixth-century AD glassware from Jelica, Serbia—an increasingly complex picture of late antiquity glass composition

In this paper, the chemical analyses of forty-two samples of glassware from the sixth to early seventh century AD Byzantine settlement of Gradina on Jelica, Serbia are reported, completing the previous study of forty windowpane samples from the same site. Apart from a single plant ash glass, all other glasses are natron-based, classified as Foy 2.1 (thirty-four), Foy 3.2 (six), and Roman (two). The ten colourless glasses from the assemblage are decolourised with manganese. Five glasses are intentionally coloured blue with cobalt and copper, one black with iron. Four blue glasses are opacified, one with antimony, one perhaps with tin. Some Jelica glass finds classified as Foy 3.2 are specific for having magnesium levels above those characteristic for serie 3.2. Jelica glasses assigned to Foy 2.1 group were further divided into low iron (twenty), high iron (four), and very high iron (six) subgroups. The overall compositional pattern of Jelica samples identified as Foy 2.1 suggest that different sands with different heavy mineral suites and sources of lime were used in their making, as well as different levels of recycling. Our findings indicate that the reasons for the compositional blurring of Foy 3.2 and Foy 2.1 are not limited to technological reasons such as recycling, but also include variations in the sand minerals. The results support the picture of the dominance of Foy 2.1 and Foy 3.2 types of glass in central and eastern Balkans and on the Macedonian-Thracian coast during the sixth century AD. Our findings, together with the apparent absence of Levantine glass from this region reported until now, suggest that different trade routes were supplying these regions with Eastern Mediterranean raw glass from those supplying Adriatic Sea coasts.

Wood Bottom Ash and GeoSilex: A By-Product of the Acetylene Industry as Alternative Raw Materials in Calcium Silicate Units.

The main objective of this research was to obtain calcium silicate units from alternative raw materials, such as the bottom ashes from the combustion of wooden boards (WBA), as a source of silica, and GeoSilex (G), a by-product with low energy and environmental costs generated in the manufacture of acetylene, as a source of lime. Once the raw materials were physically, mineralogically and chemically characterized, calcium silicate units were obtained by mixing different amounts of WBA residue (90–20 wt%) and G by-product (10–80 wt%). The mixtures were compressed at 10 MPa and cured in water for 28 days. The calcium silicate units were subjected to a wide experimental program that included the determination of physical properties (bulk density, apparent porosity and water absorption), mechanical properties (compressive strength), and thermal properties (thermal conductivity). Optimum values are obtained for calcium silicate units that contain a 1/1 WBA/G weight ratio, which have an optimal amount of SiO2 and CaO for the cementation reaction. The 50WBA-50g units have compressive strength values of 46.9 MPa and a thermal conductivity value of 0.40 W/mK. However, all calcium silicate units obtained comply with the European Standard EN 771-2: 2011 to be used as structural building materials.

SOME PHYSICAL AND CHEMICAL PROPERTIES OF SOIL AFFECTED BY THE APPLICATION OF DIFFERENT SOURCES OF LIME IN ABUJA, NIGERIA

A field experiment was conducted at University of Abuja Teaching and Research farm, F.C.T-Abuja, Nigeria to determine the effects of different sources of lime on soil properties. The experiment was laid out in a Randomized Complete Block Design (RCBD) in factorial fashion comprising six treatments replicated three times. The treatment includes two types of industrial lime (ultrasol - V1 and agricultural lime – V2) applied at three different levels. Data collected from the study were analyzed using Analysis of Variance (ANOVA) and means were separated with Duncan’s New Multiple Range Test (DNMRT). The result obtained showed a high significant effects of treatments on soil chemical properties. The soil chemical properties were calcium (Ca), with the application of V2L1 (1000kg/ha) giving the highest value relative to other treatments and control. Soil exchangeable magnesium showed a significant effect in the control plot (V2Lo). Percent organic carbon and percent organic matter content in the soil were highly significant in plots treated with V1L2 (ultrasol lime at 2000kg/ha). Exchangeable potassium (k) and sodium (Na) produced the highest values in plots amended with V1L1 (ultrasol lime at 1000kg/ha) though not significant. Base saturation was increased though not significant in V2L1 (agricultural lime at 1000kg/ha) treated plot. CEC (Cation Exchange Capacity) increased in the V2L0 (agricultural lime at 0kg/ha) but was not significant. Exchangeable acidity reduced greatly in V1L2 and V2L1 treated plots. Electrical conductivity in the soil and percent total nitrogen showed no significant difference but produced the highest values in plots amended with V1L1. Manganese (Mn) and copper (Cu) in the soil were influenced by treatments with the lowest values in plots treated with V2L2 (agricultural lime at 2000kg/ha) though not significant. Iron (Fe) was reduced in plot treated with V1L0 (ultrasol lime at 0kg/ha) but was not significantly different. Zinc (Zn) was completely eliminated on the application of both agricultural and ultrasol limes. Available phosphorus had no significant influence on the amended plots and control. Soil pH (in water (H2O), potassium chloride (KCl) and in calcium chloride (CaCl2) showed no significant effect on treatments and control. Based on the following results, the use of agricultural lime (V2­­) and ultrasol lime (V1)­ both at 1000kg/ha and 2000kg/ha could be recommended for improving soil properties.

EFFECTS OF DIFFERENT SOURCES OF LIMING MATERIALS ON GROWTH AND DEVELOPMENT OF AMARANTHUS (Amaranthus hybridus) IN ABUJA, NIGERIA

A field experiment was conducted at University of Abuja Teaching and Research farm, F.C.T-Abuja, Nigeria to determine the effects of different sources of lime on growth of maranthus (Amaranthus hybridus). The experiment was laid out in a Randomized Complete Block Design (RCBD) in factorial fashion comprising six treatments replicated three times. The treatment includes two types of industrial lime (ultrasol - V1 and agricultural lime – V2) applied at three different levels. Data collected from the study were analyzed using Analysis of Variance (ANOVA) and means were separated with Duncan’s New Multiple Range Test (DNMRT). The result obtained showed a high significant effects of treatments on growth of Amaranthus (Amaranthus hybridus). Growth parameters such as plant height at 5 Weeks after Transplanting (WAT) had significantly higher value with the application of V1L2 (2000kg/ha) compared to other treatments and control. There was no significant effect on treatments and control at 2, 3 and 4WAT. Leaf count showed significant influence at 5WAT with the application of V1L1 (1000kg/ha), at 2 and 3WAT, there was no significant effect on treated plots and control. At 4WAT treatments had no significant effect on number of leaves. Plot treated with limes had no significant effect on Shoot Fresh Weight (SFW) at 4 and 5WAT. There was no significant effect on SFW at 2 and 3WAT. Shoot Dry Weight (SDW) showed a significantly higher value at 5WAT with V1L1 (1000kg/ha) compared to other treatments and control. At 4WAT control plot had a significant higher value on SDW. There was no significant effect on SDW at 4WAT with treatments. At 2 and 3WAT, SDW showed no significance difference on amended plots and control. Based on the following results, the use of ultrasol lime (V1)­ both at 1000kg/ha and 2000kg/ha could be recommended for improving growth of Amaranthus (Amaranthus hybridus).

Examination of nanoparticulate phosphate rock as both a liming agent and phosphorus source to enhance the growth of spinach in acid soil

ABSTRACT To examine the effect of nanoparticulate phosphate rock (NPR) as both a liming agent and phosphorus source in a tropical acid soil. The study examined five rates of NPR (0, 250, 500, 1000, or 2000 kg ha−1), which supplies 30, 60, 120 or 240 kg P ha−1, in a randomized complete pot experiment design with 3 replications. The pots of soil were incubated in a climate-controlled greenhouse for 21 days and then spinach was grown for 49 days. Soil parameters (pH, available P and exchangeable acidity), spinach parameters (leaf area, root hair surface area, root length and dry matter yield) and the effectiveness of NPR dissolution were estimated. The soil and plant parameters and the effective NPR dissolution all increased to the same degree at 1000 and 2000 kg NPR ha−1. Therefore, the use of 1000 kg ha−1 was most economically justified. Although, NPR has been appeared as an effective liming agent and phosphorus source in tropical acid soil. However, a regular application of NPR and further research for economic comparison between NPR and both of lime and superphosphate, as well as the original PR, will be needed.

Addition of lignin to lime materials for expedited pH increase and improved vertical mobility of lime in no‐till soils

AbstractSoil acidification caused by long‐term nitrogen (N) fertilizer applications has been a growing concern for dryland crop production in both tilled and no‐till soils in the Pacific Northwest (PNW). Many no‐till soils have stratified soil pH in the 5–10 cm depth due to repeated N fertilizer applications at this depth. In the PNW, the practice of liming to correct low soil pH is complicated due to lack of affordable lime sources and because the inherent difficulty in ameliorating stratified soil acidity in no‐till systems. An intact soil‐column incubation study was conducted to investigate whether mixing lime materials with lignin‐containing black liquor—a by‐product from the pulp industry—could elevate soil pH change in both conventional and no‐till systems and expedite vertical downward movement of lime in no‐till system. Results indicate that mixing lime with black liquor has the potential to not only elevate the increase in soil pH in both conventional till and no‐till systems, but also accelerate downward movement of lime to correct soil pH below the soil surface. Mixing agricultural lime or super fine micro lime with black liquor increased soil pH to a depth of 25–30 cm within 147 days after surface application to a no‐till soil.

Effect of difference sources and levels of lime application on yield, nutrient availability and uptake of rice in acidic soils

Soil acidity is an important agricultural problem while evaluating the production potential of most of the crops. A field experiment was conducted in farmers field at Gananadhasapuram village of Thovalaitaluk (strongly acidic soil) and Andarkulam village of Agastheswaramtaluk (moderately acidic soil) during Pishanam (Oct-Feb) and late Pishanam (Nov–Mar) season of 2017-2018 respectively, in the high rainfall zone to study the effect of different source and levels of lime on yield of rice and soil properties. Liming materials viz., dolomite and calcite were tried at different levels along with recommended fertilizers + ZnSO4. The experiment was conducted in RBD. The results of the experiment revealed that significantly higher grain (7.09 and 7.40 t ha-1) and straw (10.3 and 10.5 t ha-1) yield of rice were recorded with the application of dolomite @ 0.75 LR (6.36 t ha-1) (T7) and @ 0.50 LR (1.6 t ha-1) (T5) respectively in the strongly and moderately acidic soils along with recommended dose of fertilizers during pishanam and late pishanam seasons. Similarly, higher nutrient uptake was recorded in treatment T7 and T5 respectively both seasons as compared to other treatments. The soil pH, EC, available NPK, exchangeable Ca, Mg and DTPA extractable Zn, Cu were increased and the DTPA extractable Fe and Mn were decreased upon lime application irrespective of the sources. The economics of various treatments revealed that, the highest B:C ratio (1.86 and 2.56) was recorded with the application of dolomite @ 0.75 LR (6.36 t ha1) (T7) and @ 0.50 LR (1.6 t ha-1) (T5) along with recommended dose of fertilizers in the strongly and moderately acidic soils respectively during pishanam and late pishanam seasons. The study clearly indicated that in strongly acidic soils, the application of dolomite @ 0.75 LR (6.36 t ha-1) (T7) and in moderately acidic soils, dolomite @ 0.50 LR (1.6 t ha-1) (T5) along with recommended dose of fertilizers and ZnSO4 is found to be the best for getting higher yield and higher returns per rupee invested under rice cultivation.

Elemental analysis of limestone by laser-induced breakdown spectroscopy, scanning electron microscopy coupled with energy dispersive x-ray spectroscopy and electron probe microanalysis

Limestone, a sedimentary rock-forming mineral is a source of lime and is important industrially as it usually contains +95% calcium carbonate and <5% impurities. The presence of these impurities can cause problems while accessing the different applications of limestone requiring high chemical purity. Due to its great significance and multiple applications, the qualitative and quantitative analysis of limestone is highly desirable. The analysis of the emission spectrum obtained at the fundamental harmonic (1064 nm) of Q-switched Nd:YAG laser revealed the presence of Ca, Si, Al, Mg, Na, Fe, Ti, K, Sr and S with varying intensities. The Boltzmann plot method used to deduce the excitation temperature, and the electron number density value measured by the Stark broadening method resulted in the ranges from 4091–4231 K and (1.2–6.4) × 1016 cm−3, respectively. The quantitative analysis has been performed using the calibration-free laser-induced breakdown spectroscopy (CF-LIBS) technique based on the assumption of local thermodynamic equilibrium and optically thin plasma. The results of the CF-LIBS technique were compared to the measurements of other more standard analytical methods such as scanning electron microscopy coupled with energy dispersive x-ray spectroscopy and electron probe microanalysis with good agreement.

Characterisation of Byzantine and early Islamic primary tank furnace glass

In order to improve the understanding of glass production and provenance, we present trace element and Sr, Nd and B isotope ratio data for 15 samples of raw natron glass from a single tank furnace in Apollonia (6th–7th century CE) and eight glass samples from two tank furnaces in Bet Eli'ezer (8th century CE) in Israel. This data provides information about the geochemical homogeneity within a single batch of raw glass and about the differences and/or similarities between different tank furnaces on a single site. Four glasses from a secondary workshop at Tell el-Ashmunein, Egypt (8th–9th century CE) are analysed for comparative purposes.All raw glass samples have uniform trace element patterns and ratios. Because of poor mixing of the glass batch before and during firing, absolute concentrations however can vary significantly within a single tank furnace. The concentrations of trace elements commonly associated with (de)colouring are very low and can be attributed to background concentrations in the sand raw materials. This indicates that there was no obvious recycling of glass cullet at this stage of the production process and that the tank furnace glass is primary glass in the true sense of the word. The isotopic compositions of Sr, Nd and B in the tank furnace glasses are relatively homogeneous. This confirms their potential as provenance indicators. The isotopic composition of Sr in tank furnace glass from Apollonia and Bet Eli'ezer indicates that the lime was derived from seashell, suggesting the glass was produced from beach sand. Glass from Tell el-Ashmunein contains Sr with lower 87Sr/86Sr ratios, pointing to the use of limestone as the source of lime. All primary glasses from Israel analysed have Nd isotopic compositions typical for an Eastern Mediterranean origin. δ11B indicates that natron used in the tank furnaces in Apollonia and Bet Eli'ezer was most likely imported from Egypt.

Influence of Source and Particle Size on Agricultural Limestone Efficiency at Increasing Soil pH

Core Ideas Liming materials' fineness affected the effectiveness and economics of lime use. There is little information about pelleted lime's efficiency at increasing soil pH. This study assessed the effectiveness of calcitic and dolomitic agricultural limestone (aglime) particle sizes. Calcitic aglime was more efficient than dolomitic aglime at similar particle sizes. Pelleted lime was more effective than calcitic and dolomitic aglime. The chemico‐physical characteristics of liming materials determine their capacity to neutralize soil acidity. This study evaluated how calcitic and dolomitic agricultural limestone (aglime), pelleted calcitic lime, and different particle sizes of both aglime sources increased soil pH. Both aglime sources were fractionated to pass different Tyler mesh sizes (4–8, 8–20, 20–60, 60–100, or 100+). The equivalent of 8.97 Mg CaCO3 ha–1 of each material or powdered CaCO3 was mixed with three acidic soils and incubated for 7, 21, 35, 70, 105, 140, 175, and 210 d. All sources increased soil pH. Differences among soils were minor compared with source differences. The efficiency of lime sources at raising pH relative to CaCO3 increased with incubation time and fineness, and was lower for dolomitic than for calcitic aglime. Pelleted lime, calcitic aglime, and dolomitic aglime efficiencies across all incubation periods were 60 to 90, 47 to 65, and 12 to 47% respectively. Calcitic aglime's efficiency across the incubation periods was –1 to 29, 17 to 39, 24 to 61, 47 to 81, and 70 to 97% for material passing mesh sizes 4 to 8, 8 to 20, 20 to 60, 60 to 100, and 100+, respectively; whereas dolomitic aglime's efficiency was 2 to 12, 4 to 21, 12 to 43, 50 to 66, and 60 to 86%, respectively. The study demonstrated the value of distinguishing between particle sizes passing mesh sizes 60 to 100 and finer, and between calcitic and dolomitic aglime in aglime assessments and agricultural recommendations.

Natural Lime Treated as Partial Cement Replacement to Produce Concrete

In this study, eggshell powder was used as partial replacement of Ordinary Portland cement replacement at 5%, 10%, 15% and 20% in concrete production. Since the chemical composition of eggshell contain mainly of calcium oxide which is mostly similar to the natural lime sources. Thus the use of waste-products in cement industries is an environmental friendly while able to increase the industrialization instead of disposal of large numbers of waste materials that would pollute the land, water and air. The specimens were casted into concrete cube (100mm x 100mm x100mm) and beam (100mm x100mm x 500mm). The investigations focused on compressive, flexural strength and water absorption at different percentages of replacement and tested at 1, 7, 28, 56 and 90 days. From the investigation, it is found that the compressive strength and flexural strength increases up to 45% as compared to the control specimens when cement replacement by 15% of air-dry eggshell powder. Moreover, the rate of water absorption greatly reduces 55% when cement replacement by 15% of air-dry eggshell powder. Scanning electron microscope showed clear picture of the eggshell concrete contain less voids than normal plain concrete.

Utilization efficiency of lime consumption during magnesium sulfate precipitation

In this study, the utilization efficiency of two quicklimes and their respective slaked lime slurry (milk of lime) products were evaluated using the precipitation of magnesium sulfate as a model system. Magnesium was selected because of its abundant presence in hydrometallurgical processing solutions and mineral processing slurries, where it is often the main buffering and lime consuming element at pH levels above 9. Lime, also called quicklime, purity is often measured in terms of available CaO percentage, CaO(avail%), the active component. The purpose of this investigation was to evaluate the validity and suitability of this commonly used industrial metric for the target application reaction. Two samples with CaO(avail%) of 93 and 80% w/w were used, in dry quicklime and slaked formats, as magnesium precipitation reagents. Utilization efficiencies were compared and found to differ significantly, depending on the original quicklime reagent and format of their respective slaked lime products. Utilization efficiency was defined as the mass portion of the quicklime that participates in the target application and was calculated for both slaked lime and quicklime reagent formats to facilitate comparisons. The main conclusion was that the CaO(avail%) metric was a very poor predictor of reagent utilization efficiency of slaked lime. Although the CaO(avail%) of quicklime, provides the theoretical amount of potential active reagent, slaked lime Ca(OH)2 particle size was found to have a greater influence on utilization efficiency. Utilization efficiencies were found to range from 34 to 89% for slaked limes with median Ca(OH)2 particle sizes of 67 and 5μm respectively. Precipitate coating effects on larger Ca(OH)2 particles were observed, leading to the occlusion of unreacted Ca(OH)2 particles. This coating mechanism is proposed as a potential reason for reduced utilization efficiency of poor quality slaked lime with a significant portion of large Ca(OH)2 particles. The findings demonstrate the potential error of assessing industrial slaked lime performance, based on lime CaO(avail%) alone. It is argued that industrial selection and assessment of lime sources, should instead be assessed by determining utilization efficiency in laboratory approximation tests of the target reactions or, at least, by industrial evaluation of slaked lime particle size distribution.

Marília Oliveira Calazans, Bonding together the pasts: the mining of lime in Brazilian shell mounds

This article seeks to understand the links between mining and archaeology in shell mounds of coastal Brazil, vastly used as lime sources since the early colonization. The shell mounds are the most ancient traces of the occupation of the Brazilian coast and many of them are extinct, because of the mining, which converted their shells into the cement of colonial buildings. Between devastation and cooperation, there are connected activities that were revealed by the scientific papers, published in the nineteenth century, and by the history of the public management of those sites through the twentieth century.

Low-CO2 Cements from Fluidized Bed Process Wastes and Other Industrial By-Products

ABSTRACTAccording to the findings of X-ray diffraction analysis, calcium looping (CaL) spent sorbent (as a main source of CaO), anodization mud (as a source of Al2O3 and additional sulfate), and fluidized bed combustion (FBC) fly and bottom ashes, separately or in mixture (as main sources of CaSO4 plus alumina and uncarbonated lime) can replace limestone, bauxite, and gypsum as components of calcium sulfoaluminate (CSA) clinker-generating raw mixes. All of the hydrated CSA cements obtained from the corresponding clinkers and investigated by means of differential thermal-thermogravimetric analysis displayed a similar behavior. It has been demonstrated that the well-recognized environmentally friendly character of CSA cement manufacture can be further improved not only by using industrial wastes instead of natural materials, but also by virtue of the reduced CO2 emission and increased energy saving associated with the limestone substitution with poorly carbonated sources of lime, such as CaL spent sorbent and FBC ashes.