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Number of results: 10
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Abstract

Deposits used as fertilizer bring to soil both biogens necessary for plant growth and other ingredients such as metals. including heavy metals. Knowledge of quantities and rate in which heavy metals are to be released to soil from granulates is important because of their toxic influence on plants (in the case of high metals concentration). This paper presents results of investigation of elution of Cu. Zn, Ni, Cd, Pb. and Cr from granulates prepared from municipal sewage sludge, hard coal ash and brown coal ash. Elution to water solution was carried out in static conditions with single-stage and tree-stage extraction. Heavy metal a component of sludge-ash granulates eluted in various quantities, i.e. from trace for cadmium to 9.26-9.53 mg/kg of d.m. for zinc. Among the soluble forms of metals the most mobile are (in decreasing sequence): Cu > Pb> Zn> Ni in granulates containing brown coal ash and Cu> Pb> Ni> Zn in granulates contain hard coal ash.
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Authors and Affiliations

Czesława Rosik-Dulewska
ORCID: ORCID
Katarzyna Głowala
Urszula Karwaczyńska
Jolanta Robak
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Abstract

This study explores the influence of alkali activators on the initiation of polymerization reaction of alumino-silicate minerals present in class-F fly ash material. Different types of fly ash aggregates were produced with silicate rich binders (bentonite and metakaolin) and the effect of alkali activators on the strength gain properties were analyzed. A comprehensive examination on its physical and mechanical properties of the various artificial fly ash aggregates has been carried out systematically. A pelletizer machine was fabricated in this study to produce aggregate pellets from fly ash. The efficiency and strength of pellets was improved by mixing fly ash with different binder materials such as ground granulated blast furnace slag (GGBS), metakaolin and bentonite. Further, the activation of fly ash binders was done using sodium hydroxide for improving its binding properties. Concrete mixes were designed and prepared with the different fly ash based aggregates containing different ingredients. Hardened concrete specimens after sufficient curing was tested for assessing the mechanical properties of different types concrete mixes. Test results indicated that fly ash -GGBS aggregates (30S2‒100) with alkali activator at 10M exhibited highest crushing strength containing of 22.81 MPa. Similarly, the concrete mix with 20% fly ash-GGBS based aggregate reported a highest compressive strength of 31.98 MPa. The fly ash based aggregates containing different binders was found to possess adequate engineering properties which can be suggested for moderate construction works.

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Authors and Affiliations

P. Gomathi
A. Sivakumar
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Abstract

The application of fluidized fly ash in underground mining excavations is limited due to its significant content of free calcium and calcium sulfate. In order to increase the amount of utilized fly ash from fluidized beds, it should be converted to a product with properties that meet the requirements for mining applications. This research presents the results of an attempt to adapt fluidized fly ashes for use in underground mining techniques, by means of carbonation and granulation. Carbonation was performed with the use of technical carbon dioxide and resulted in the reduction of free calcium content to a value below 1%. Granulation on the other hand, resulted in obtaining a product with good physical and mechanical parameters. The performed mineralogical and chemical studies indicate that trace amounts of “binding” phases, such as basanite and/or gypsum are present in the carbonized ash. The addition of water, during the granulation of carbonized fluidized fly ash, resulted in changes in the mineral phases leading to the formation of ettringite and gypsum as well as the recrystallization of the amorphous substance. It was confirmed that the carbonization and granulation of flying fluidized ashes positively affects the possibility of using these ashes in underground mining excavations.

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Authors and Affiliations

Jadwiga Proksa
Marian Jacek Łączny
Zbigniew Bzowski
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Abstract

This paper elucidated the potential of electron backscatter diffraction analysis for ground granulated blast furnace slag geopolymers at 1000°C heating temperature. The specimen was prepared through the mechanical ground with sandpaper and diamond pad before polished with diamond suspension. By using advanced technique electron backscatter diffraction, the microstructure analysis and elemental distribution were mapped. The details on the crystalline minerals, including gehlenite, mayenite, tobermorite and calcite were easily traced. Moreover, the experimental Kikuchi diffraction patterns were utilized to generate a self-consistent reference for the electron backscatter diffraction pattern matching. From the electron backscatter diffraction, the locally varying crystal orientation in slag geopolymers sample of monoclinic crystal observed in hedenbergite, orthorhombic crystal in tobermorite and hexagonal crystal in calcite at 1000°C heating temperature.
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Authors and Affiliations

Ikmal Hakem Aziz
1
ORCID: ORCID
Mohd Mustafa Al Bakri Abdullah
2
ORCID: ORCID
Mohd Arif Anuar Mohd Salleh
2
ORCID: ORCID
Sorachon Yoriya
3
ORCID: ORCID
Rafiza Abd Razak
4
ORCID: ORCID
Rosnita Mohamed
1
ORCID: ORCID
Madalina Simona Baltatu
5
ORCID: ORCID

  1. Universiti Malaysia Perlis (UniMAP), Geopolymer & Green Technology, Centre of Excellence (CEGeoGTech), Perlis, Malaysia
  2. Universiti Malaysia Perlis (UniMAP), Faculty of Chemical Engineering Technology, Perlis, Malaysia
  3. National Metal and Material Technology Center (MTEC), National Science and Technology Development Agency (NSTDA), 114, Thailand Science Park, Pahonyothin Rd., Khlong 1, Khlong Luang, Pathum Thani 12120, Thailand
  4. Department of Civil Engineering Technology, Faculty of Engineering Technology, Universiti Malaysia Perlis (UniMAP), 02100 Padang Besar, Perlis, Malaysia
  5. Gheorghe Asachi Technical University of Iasi, Faculty of Materials Science and Engineering, 700050, Iasi, Romania
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Abstract

Significant quantities of coal sludge are created during the coal enrichment processes in the mechanical processing plants of hard coal mines (waste group 01). These are the smallest grain classes with a grain size below 1 mm, in which the classes below 0.035 mm constitute up to 60% of their composition and the heat of combustion is at the level of 10 MJ/kg. The high moisture of coal sludge is characteristic, which after dewatering on filter presses reaches the value of 16–28% (Wtot r) (archival paper PG SILESIA). The fine-grained nature and high moisture of the material cause great difficulties at the stage of transport, loading and unloading of the material. The paper presents the results of pelletizing (granulating) grinding of coal sludge by itself and the piling of coal sludge with additional material, which is to improve the sludge energy properties. The piling process itself is primarily intended to improve transport possibilities. Initial tests have been undertaken to show changes in parameters by preparing coal sludge mixtures (PG SILESIA) with lignite coal dusts (LEAG). The process of piling sludge and their mixtures on an AGH laboratory vibratory grinder construction was carried out. As a result of the tests, it can be concluded that all mixtures are susceptible to granulation. This process undoubtedly broadens the transport possibilities of the material. The grain composition of the obtained material after granulation is satisfactory. Up to 2 to 20 mm granules make up 90–95% of the product weight. The strength of the fresh pellets is satisfactory and comparable for all mixtures. Fresh lumps subjected to a test for discharges from a height of 700 mm can withstand from 7 to 14 discharges. The strength of the pellets after longer seasoning, from the height of 500 mm, shows different values for the analyzed samples. The values obtained for hard coal sludge and their blends with brown coal dust are at the level from 4 to 5 discharges. The strength obtained is sufficient to determine the possibility of their transport. At this stage of the work it can be stated that the addition of coal dust from lignite does not cause the deterioration of the material’s strength with respect to clean coal sludge. Therefore, there is no negative impact on the transportability of the granulated material. As a result of mixing with coal dusts, it is possible to increase their energy value (Klojzy-Karczmarczyk at al. 2018). The cost analysis of the analyzed project was not carried out.

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Authors and Affiliations

Jacek Feliks
Beata Klojzy-Karczmarczyk
Marek Wiencek
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Abstract

Hard coal sludge is classified as group 01 waste or it is a by-product in the production of a hard coal with variable energy importance. Pulverized lignite is not waste but a final product of drying and the very fine pulverization of lignite with a high calorific value. The study comprised the basic material before granulation such as coal sludge (PG SILESIA) and pulverized lignite (LEAG) as well as their prepared blends after the granulation on a pipe vibration granulator designed at AGH. The pulverized lignite of the LEAG company shows a low sulfur contents. In the analyzed samples its average content (Stot d) is 0.61%. An average value of this parameter in the analyzed coal sludge samples is 0.55%. The addition of pulverized lignite does not have a significant impact on the total content of sulfur and of analyzed toxic elements (Hg, As, Cd, Cr, Co, Cu, Mn, Ni, Pb, Sb, Tl, and W) in the samples. The calorific value of coal sludge falls within the range of 11.0−12.4 MJ/kg (on a dry basis). For the coal sludge and pulverized lignite blends the calorific value clearly increases to values of 14.8−17.7 MJ/kg (on dry basis). The calorific value slightly decreases in the

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Authors and Affiliations

Beata Klojzy-Karczmarczyk
ORCID: ORCID
Janusz Mazurek
ORCID: ORCID
Marek Wiencek
Jacek Feliks
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Abstract

The article analyzes the influence of selected factors on the activity rate of cement binder containing 50% of ground granulated blast furnace slag in its composition. These factors are the chemical and mineral composition of Portland cement CEM I, the degree of grinding of granulated blast furnace slag and Portland cement, and the water/binder ratio. This slag content is characteristic for blast furnace cement CEM III/A. In addition to the application effects, this type of cement is a low-carbon binder (there is a reduction of CO 2 emissions by about 45% compared to Portland cement CEM I). The use of this type of cement in the composition of concrete enables the obtaining of concrete with a very small carbon footprint. Based on the results of our own research, it was found that such a high proportion of ground granulated blast furnace slag in the binder composition leads to a significant reduction in the early compressive strength of standard mortars (after two and seven days of setting). This results in a significant reduction in the use of these types of binders (cements) in selected areas of construction, e.g. prefabrication and high-strength concrete. Analyzing the obtained results of their own research, the authors concluded that the early strength of these types of binders can be significantly improved by increasing the specific surface area (degree of grinding) of Portland cement CEM I and lowering the water/slag ratio (w/s, where: s = cement + slag). The proposed material and technological modifications also enable the obtaining of higher compressive strength at all tested dates. The strength of the standard (after twenty-eight days and over longer periods) is comparable to or higher than that of Portland cement CEM I.
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Authors and Affiliations

Arkadiusz Janic
1
ORCID: ORCID
Zbigniew Giergiczny
2
ORCID: ORCID

  1. Technology Centrum Betotech sp. z o.o., Dąbrowa Górnicza, Poland;
  2. Faculty of Civil Engineering Silesian University of Technology, Gliwice, Poland
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Abstract

The effects of supplementary cementitious materials (SCM) on the characteristics and internal structure of synthetic aggregate made from ground granulated blast furnace slag are investigated in this study (GGBS). Due to its high pozzolanic activity, GGBS was shown to be superior to other SCM materials, enhancing both the strength and durability of synthetic aggregate. Because sintering uses a lot of energy and generates a lot of pollutants, using a cold-bonded approach to make low density lightweight aggregates is particularly significant from an economic and environmental standpoint. Thus, the utilisation of ground granulated blast furnace slag (GGBS) as a substitute material in the production of green artificial lightweight aggregate (GLA) using the cold bonding method was discussed in this work. Admixtures of ADVA Cast 203 and Hydrogen Peroxide were utilised to improve the quality of GLA at various molar ratios. The freshly extracted GLA was then evaluated for specific gravity, water absorption, aggregate impact, and aggregate crushing in order to determine the optimal proportion blend. As a result, the overall findings offer great application potential in the development of concrete (GCLA). It has been determined that aggregates with a toughness of 14.6% and a hardness of 15.9% are robust. The compressive strength test found that the GCLA has a high strength lightweight concrete of 37.19 MPa and a density of 1845.74 kg/m3. The porous features developed inside the internal structure of GLA have led to GCLA’s less weight compared to conventional concrete.
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Authors and Affiliations

R.A. Razak
1 2
ORCID: ORCID
M.A. Hassan
1
ORCID: ORCID
M.M.A.B. Abdullah
2
ORCID: ORCID
Z. Yahya
1 2
ORCID: ORCID
M.A.M. Ariffin
3
ORCID: ORCID
A.F.B. Mansor
1
ORCID: ORCID
D.L.C. Hao
1 2
ORCID: ORCID

  1. Universiti Malaysia Perlis (UniMAP), Faculty of Civil Engineering Technology, Perlis, Malaysia
  2. Universiti Malaysia Perlis (UniMAP), Geopolymer & Green Technology, Centre of Excellence (CEGeoGTech), Perlis, Malaysia
  3. Universiti Teknologi Malaysia, School of Civil Engineering, Faculty of Engineering, Skudai, Johor Bahru, Malaysia
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Abstract

In this study, the effects of replacing fine aggregate by granulated lead/zinc slag waste (GLZSW) on the thickness of concrete shields against X-ray radiation and on the compressive strength of concrete have been investigated. The fine aggregate was substituted by GLZSW in four percentages: 25%, 50%, 75%, and 100% (by weight). The first aim of the present study was to compare the thicknesses of concretes with GLZSW and control concrete using Lead Equivalent (LE). The second aim was to assess the effects of replacing fine aggregate by GLZSW on the compressive strength of concrete. Results of this study indicated that the compressive strength of mixed concretes increased significantly compared to the control upon replacing fine aggregate by GLZSW; the mixture containing 100% GLZSW had the greatest compressive strength. Further, the inclusion of GLZSW as a substitute for fine aggregate increased the radiation attenuation properties and consequently decreased the thickness of concrete shields in direct proportion to the mixing ratio of GLZSW. The results revealed that concrete mixes containing 100% GLZSW offered the greatest reduction in shield thickness. The study shows that there is a promising future for the use of GLZSW as substitute for fine aggregate in concrete used to shield against X-ray radiation.
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Authors and Affiliations

Mohamed Alwaeli
1

  1. Assoc. Prof., DSc., PhD., Eng., Mohamed Alwaeli, Silesian University of Technology, Faculty of Energy and Environmental Engineering, Konarskiego 18A, 44-100 Gliwice

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