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Tytuł:
Dolomite and calcite enhancement of whey protein isolate hydrogels
Autorzy:
Norris, K.
Tsang, S. C.
Kerns, J. G.
Kłosek-Wawrzyn, E.
Jaegermann, Z.
Douglas, T. E. L.
Powiązania:
https://bibliotekanauki.pl/articles/285345.pdf
Data publikacji:
2018
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Polskie Towarzystwo Biominerałów
Tematy:
hydrogels
dolomite
calcite
Źródło:
Engineering of Biomaterials; 2018, 21, 148; 98
1429-7248
Pojawia się w:
Engineering of Biomaterials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Changes of surface properties of calcite particles with calcium stearate using conventional experimental design and properties of coated calcite
Autorzy:
Ucurum, M.
Bayram, O.
Toraman, O. Y,
Kılıc, H.
Yalcın, S.
Powiązania:
https://bibliotekanauki.pl/articles/109347.pdf
Data publikacji:
2018
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
calcite
surface modification
mechano-chemical
calcium stearate
properties of modified calcite
Opis:
Calcite is utilized as a filler mineral in the industries such as plastics, rubber, and paint, to gain products with a variety of features. In order to use a calcite ore as a filler, some specific physical and physico-chemical properties are required such as ultra-fine sizes and conversion of hydrophilic to hydrophobic structure. In the present study, for these purposes, surfaces of the ultra-fine calcite powder (d50=2.94 μm) were coated by a mechano-chemical process with calcium stearate [Ca(C17H35COO)2] in a stirred ball mill. The influence of operating parameters such as calcite filling-ratio, ball-filling ratio, operation speed, grinding time and chemical dosage on the active ratio (%) was systematically examined. Then, the properties of modified calcite product were measured and evaluated by contact angle, TGA, DTA, FTIR, and SEM. The results showed that the mechano-chemical technology is very effective for modifying the surface of micronized calcite products using calcium stearate chemical.
Źródło:
Physicochemical Problems of Mineral Processing; 2018, 54, 3; 688-700
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Separation of magnesite and calcite based on flotation solution chemistry
Autorzy:
Yao, Jin
Gong, Xiufeng
Sun, Haoran
He, Ruofan
Yin, Wanzhong
Powiązania:
https://bibliotekanauki.pl/articles/2146910.pdf
Data publikacji:
2022
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
magnesite
calcite
reverse flotation
Opis:
The dissolution characteristics of minerals, dissolution of flotation agents in solutions, and equilibrium of dissociations and associations serve as the basis for determining the optimal conditions for the effective components of flotation agents and for evaluating the interaction between flotation agents and minerals. This basis provided the theoretical support for the flotation separation of minerals. Based on this, the flotation separation of magnesite and calcite was realized using sodium dihydrogen phosphate, also known as monosodium phosphate (MSP), as a regulator and dodecylamine (DDA) as a collector. When MSP was used in the DDA system, single-mineral and binary mixed-ore flotation tests revealed that the floatability of calcite was significantly greater than that of magnesite and the separation of magnesite and calcite was more effective, respectively. Zeta potential measurements showed that MSP-containing negative groups could selectively reduce the zeta potential of calcite and promote the adsorption of DDA-containing positive groups on the surface of the calcite. However, this effect was negligible on the zeta potential of magnesite. Due to the stronger affinity of MSP to Ca2+ than that to Mg2+, as demonstrated by Fourier transform infrared and X-ray photoelectron spectroscopy analyses, the MSP was adsorbed onto the surface of calcite primarily by hydrogen bonds rather than magnesite, which promoted the stronger adsorption of DDA-containing positive groups on the surface of the calcite. As a result, the differences in the floatability of magnesite and calcite were enlarged by MSP. Thus, MSP can be utilized an effective regulator for the efficient separation of magnesite from calcite via reverse flotation.
Źródło:
Physicochemical Problems of Mineral Processing; 2022, 58, 4; art. no. 149398
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Applicability of statistical process control for surface modification plant and properties of coated calcite
Autorzy:
Ucurum, M.
Malgir, E.
Deligezen, H.
Karaer, N.
Avsar, M.
Powiązania:
https://bibliotekanauki.pl/articles/110501.pdf
Data publikacji:
2016
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
calcite
surface modification
pin mill plant
statistical process control
coated calcite properties
Opis:
Due to its low surface energy, easy dispersion, high homogeneity and whiteness, coated (modified) calcite has increasingly been used in many industries, particularly in the plastics. The demand for this product will most likely increase in the years to come. Surface modification of calcite with a fatty acid would lead to a great expansion of industrial applications. The color values of coated calcite products are the first quality parameter. Therefore, it is very important to monitor the variations in the color characteristics of the coated calcite products. It is well known that statistical process control (SPC) techniques have been widely used in the many industries. In the present study, the surface of micronized calcite was coated with stearic acid by a pin mill. X-R control graphics and process capability index were applied for monitoring variations in quality control based on color parameters (L*, a* and b*) for the pin mill plant. In addition, active ratio, particle size distribution, whiteness parameters, BET, FTIR, TGA-DTA and SEM were then determined on a coated calcite sample. The results show that the pin mill plant seems under control and the coating technology is very effective in modifying the surface of micronized calcite products.
Źródło:
Physicochemical Problems of Mineral Processing; 2016, 52, 2; 803-820
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Evaluation Potential as Micronized Calcite of White Marble Waste
Ocena potencjału pozyskania zmikronizowanego kalcytu z odpadów z białego marmuru
Autorzy:
Deniz, Vedat
Polat, Ercan
Powiązania:
https://bibliotekanauki.pl/articles/318935.pdf
Data publikacji:
2020
Wydawca:
Polskie Towarzystwo Przeróbki Kopalin
Tematy:
calcite
marble wastes
micronized calcite
physical properties of micronized calcite
chemical properties of micronized calcite
physicochemical properties of micronized calcite
mineralogical properties of micronized calcite
kalcyt
odpady marmuru
kalcyt mikronizowany
właściwości fizyczne mikronizowanego kalcytu
właściwości chemiczne mikronizowanego kalcytu
właściwości fizykochemiczne mikronizowanego kalcytu
właściwości mineralogiczne mikronizowanego kalcytu
Opis:
Natural calcium carbonates have a great importance in the world’s economy due to their numerous applications areas such as calcium carbonate in the paper and paint industries. The final calcite products have rigorous quality specifications which are currently difficult to meet for local producers in Turkey. Therefore, large quantities of high white marble wastes have been transported long distances inside the country to supply the different industrial plants for using calcite. Marble wastes, located in Afyon and Kutahya regions, Turkey’s mid-west, are used generally for concrete and highway purposes. Evaluations of marble wastes are very important for the economic development of any country or region. This study aims at developing new perspective for evaluation of marble wastes as domestic calcite resources and serves as a guide for investment and decision making for the Turkey calcite industry. This paper presents applied research work to determining the product quality for evaluation as micronized calcite of marble wastes and gives an overview of the market situation for the regional producers. The aim of the work is to characterize four different marble wastes and to determine the potential for production of the required quality for the Turkey calcite market;- to control the quality of the products by application tests, including the measurement some tests.
Naturalne węglany wapnia mają ogromne znaczenie w światowej gospodarce ze względu na ich liczne zastosowania, takie jak węglan wapnia w przemyśle papierniczym i malarskim. Produkty handlowe kalcytu muszą spełniać rygorystyczne wymagania jakościowe, które obecnie są trudne do osiągnięcia przez lokalnych producentów w Turcji. Dlatego duże ilości odpadów z przeróbki białego marmuru zostały przetransportowane do zakładów przemysłowych które wykorzystują kalcyt. Odpady marmurowe, znajdujące się w regionach Afyon i Kutahya, w środkowo-zachodniej Turcji, są ogólnie wykorzystywane do betonu i budowy autostrad. Możliwość wykorzystania odpadów marmurowych jest bardzo ważna dla rozwoju gospodarczego każdego kraju lub regionu. W artykule przedstawiono nową metodę oceny odpadów marmurowych jako krajowych zasobów kalcytu. Metoda służy jako przewodnik dla inwestorów i do podejmowania decyzji w branży kalcytu w Turcji. W artykule przedstawiono prace badawcze prowadzone w celu określenia jakości produktu - zmikronizowanego kalcytu z odpadów marmurowych oraz przegląd sytuacji rynkowej producentów regionalnych. Celem artykułu jest scharakteryzowanie czterech różnych odpadów marmurowych i określenie potencjału produkcji kalcytu o wymaganej jakości w Turcji. Zaproponowano kontrolę jakości produktów poprzez testy aplikacyjne, w tym pomiary niektórych parametrów.
Źródło:
Inżynieria Mineralna; 2020, 2, 1; 21-28
1640-4920
Pojawia się w:
Inżynieria Mineralna
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Żyłowe złoża kalcytów
Vein calcite deposits
Autorzy:
Bąk, B.
Kuć, P.
Nieć, M.
Powiązania:
https://bibliotekanauki.pl/articles/170852.pdf
Data publikacji:
2016
Wydawca:
Poltegor-Instytut Instytut Górnictwa Odkrywkowego
Tematy:
kalcyt
żyły kalcytowe
różanka
wapienie
dolomity
calcite
vein of calcite
limestone
dolomite
Opis:
Żyły kalcytów cechujące się znaczną grubością, od kilku do kilkunastu, rzadziej kilkudziesięciu metrów, występują w obszarze kielecko-chęcińskim oraz w rejonie Krzeszowic koło Krakowa. Niektóre z nich są udokumentowane i wykazywane w krajowym bilansie zasobów. Obecnie nie mają znaczenia gospodarczego i nie są eksploatowane. Miały one znaczenie w przeszłości. Wydobywano z nich kalcyt żyłowy, zwany „różanką”, ceniony z uwagi na jego walory dekoracyjne. Wykorzystywane były głównie w budownictwie sakralnym. Żyły kalcytu występujące w strefie zaburzeń tektonicznych, przez co cechuje je złożona budowa o zróżnicowanych teksturach. Poszczególne generacje kalcytu różnią się barwą i strukturą skupień kalcytu. Kalcyt zazwyczaj jest grubokrystaliczny, często jego agregaty mają budowę pręcikową. Żyły mają budowę złożoną, krystyfikacyjną i brekcjową. W drugiej połowie XX w. żyły kalcytowe, z przyczyn ekonomicznych i względów ochrony środowiska, straciły znaczenie gospodarcze. Ich eksploatacja na niewielką, rzemieślniczą skalę, powinna być nadal możliwa jako źródło kamienia do rekonstrukcji starych zabytków architektonicznych.
Pure calcite veins of considerable thickness up to teens of meters, that occurs in the western part of Holy Cross Mts., and to the West of Kraków, were economically important in the past. Their coarse crystalline varied: banded, cockade or breccia structure and varied rose coloration, make theme unique decorative, ornamental stone. Recently, they lost importance due to small size and environment protection exigencies, however they are listed in governmental mineral resources inventory. Their small scale, artisanal quarrying is still possible, as a source of ornamental stone for reconstruction of old architectural monuments.
Źródło:
Górnictwo Odkrywkowe; 2016, 57, 5; 34-41
0043-2075
Pojawia się w:
Górnictwo Odkrywkowe
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Calcium carbonate mineralization. Part II: effect of poly(ethylene glycol) and block copolymers molecular weight on formation of precipitate
Autorzy:
Polowczyk, I.
Bastrzyk, A.
Kozlecki, T.
Grzadka, E.
Sadowski, Z.
Powiązania:
https://bibliotekanauki.pl/articles/110696.pdf
Data publikacji:
2015
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
mineralization
block copolymers
PEG
calcite
Opis:
In this study the role of PEG and PEO-PPO-PEO block copolymers molecular weight in precipitation of calcium carbonate was examined. The CaCO3 particles were characterized by FTIR spectroscopy, X-ray, SEM and particle size distribution analysis. In absence and presence of modifiers, mixing of the reagents led to the formation of calcite crystals. The calcium carbonate obtained with poly(ethylene glycol) and block copolymers was characterized by smaller diameter in comparison with the one without modifiers. It was observed that using compounds with different molecular weights has no obvious effect on the form and properties of precipitated calcium carbonate particles.
Źródło:
Physicochemical Problems of Mineral Processing; 2015, 51, 2; 587-600
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of depressants in the selective flotation of smithsonite and calcite using potassium lauryl phosphate as collector
Autorzy:
Sun, Qing
Feng, Qiming
Shi, Qing
Powiązania:
https://bibliotekanauki.pl/articles/110635.pdf
Data publikacji:
2019
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
smithsonite
calcite
flotation
depressant
separation
Opis:
In order to selectively separate smithsonite and calcite using potassium lauryl phosphate as collector and reveal the depression mechanism, the approaches of micro-flotation and zeta potential measurements were adopted. The effects of sodium hexametaphosphate (SHMP), water glass (WG), carboxymethyl cellulose (CMC) and lignosulfonate calcium (LSC) as depressants on smithsonite and calcite have been studied through micro-flotation. The single mineral flotation tests show that LSC can depress calcite, but it has little effect on smithsonite flotation. Flotation separation of a mixture of smithsonite and calcite can be completed to obtain a zinc concentrate grade up to 33.85% Zn with a recovery of 70.06%. The zeta potential results illustrate that LSC has higher tendency to be adsorbed on the surface of calcite. However, there is little adsorption of LSC on smithsonite.
Źródło:
Physicochemical Problems of Mineral Processing; 2019, 55, 1; 89-96
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of depressants in the selective flotation of smithsonite and calcite using cationic collector
Autorzy:
Liu, Hongjiang
Zhang, Guofan
Luo, Yuanjia
Powiązania:
https://bibliotekanauki.pl/articles/1449481.pdf
Data publikacji:
2020
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
smithsonite
calcite
selective separation
depressant
Opis:
This work studied the effects of sodium hexametaphosphate (SHMP), tanning extract, water glass (WG) and calcium lignosulfonate (CLS) as depressants for the separation of smithsonite from calcite by using a cationic collector called octadecylamine acetate (ODA). Micro-flotation experimental tests showed that CLS can greatly and selectively depress calcite. When the dosages of CLS used were 20 and 40 mg/L, a concentrate with Zn grades of 42.54% and 49.32% and Zn recoveries of 81.66% and 68.00% was achieved in the flotation separation of mixed mineral (1:1 smithsonite:calcite). Zeta potential and adsorption measurements revealed that the adsorption of CLS on calcite’s surface was greater than that on smithsonite’s surface. When CLS was added, the adsorption of ODA was hindered greatly on the calcite’s surface but slightly on the smithsonite’s surface.
Źródło:
Physicochemical Problems of Mineral Processing; 2020, 56, 1; 1-10
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
High Porous Ceramic for Oil/Water Separation: Calcite as a Sintering Aid
Autorzy:
Abdulhameed, Mohammed Abdulmunem
Rahman, Mokdad Hayawi
Azziz, Haider Nadhom
Powiązania:
https://bibliotekanauki.pl/articles/27323841.pdf
Data publikacji:
2023
Wydawca:
Polskie Towarzystwo Inżynierii Ekologicznej
Tematy:
porous ceramic membrane
sintering aid
calcite
Opis:
The effects of calcite (CaCO3) as sintering aid on the preparation of local aluminum silicate microfiltration membranes were characterized in terms of morphology, thermal shrinkage behavior, porosity, permeation performance, and pure water permeate flux for the membrane. Material selection is based on availability and formability. In order to create a suspension, an organic solvent (N-methyl-2-pyrrolidone) and a polymer binder were added to a mixture of aluminum silicate and calcium carbonate. The coagulant bath consisted of water, and the suspension was extruded into a hollow fiber using a spinneret. The membrane precursor is subjected to high temperatures up to 1250 °C and this process called the sintering process gets strong hollow fiber with high mechanical stability. The addition of the CaCO3 to the dispersion altered the structure of the resulting sintered membranes. The obtained finding demonstrates that carbon calcium addition to aluminum silicate has an affirmative on overall porosity in contrast to those made from purely natural aluminum silicate, as a result the aluminum silicate calcite ceramic microfiltration membrane, which had a high porosity of above 50%, shows the highest permeability of 35.8 ml m-2•s-1 and above 97% oil rejection when operating at 0.15 MPa trans-membrane pressure in oil-in-water separation experiments. The results show that low-cost aluminum silicate-calcite component of ceramic membranes and the manufactured ceramic microfiltration membrane can handle emulsified oily wastewater.
Źródło:
Journal of Ecological Engineering; 2023, 24, 7; 88--95
2299-8993
Pojawia się w:
Journal of Ecological Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The effect of the main component ratios in the joint filling on the product quality
Autorzy:
Rizaoğlu, Tamer
Karataş, Muhammed Ziya
Çoşkun, Canberk
Powiązania:
https://bibliotekanauki.pl/articles/27324350.pdf
Data publikacji:
2022
Wydawca:
Instytut Techniki Górniczej KOMAG
Tematy:
cement
joint filling
calcite
building materials
Opis:
When building materials are exposed to environmental and natural factors such as temperature differences, humidity, strong wind and earthquake in the areas where they are applied, irreversible damages such as separation, cracking and level difference occur in structures and building materials. In order to prevent these damages, the joints are left between the building materials and the gaps are filled with filling materials. The composition of the materials filling the joint gaps is also very important. The most important problems encountered in joint fillings are rupture, cracking and therefore permeability. In this study, it is aimed to compare the joint filling materials produced from different proportions of aggregate and white cement against rupture and cracking, and to determine the mixture ratio that exhibits the best performance. Five different recipes were prepared by using calcite powder as aggregate, white Portland cement as binder and water-repellent, volumizing and thickening chemical additives as auxiliary materials. On the prepared test samples; Capillary water absorption, water absorption by weight and volume, unit volume weight, saturated unit volume weight, porosity, compressive strength, bending strength, surface hardness and abrasion resistance tests were carried out. Considering the cost and environmental damage of cement, which is one of the main components in joint filler material, DD2 [Calcite (71.50%)] + White Cement (26.50%) + [Polymer + Cellulose + Plasticizer + Silicone] 2% has been detected as the most appropriate recipe.
Źródło:
Mining Machines; 2022, 40, 4; 180--190
2719-3306
Pojawia się w:
Mining Machines
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effective flotation separation of scheelite and calcite by applying methylene phosphonic acid sodium as a novel and green depressant
Autorzy:
Zhou, Hepeng
Wu, Handan
Guo, Jiangfeng
Tang, Xuekun
Huang, Wen
Luo, Xianping
Powiązania:
https://bibliotekanauki.pl/articles/24086193.pdf
Data publikacji:
2023
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
scheelite
calcite
inhibition mechanism
flotation separation
Opis:
It is known that the flotation separation of scheelite and calcite is quite difficult due to their similar surface properites. To slove the problem, ethylenediaminetetra (methylene phosphonic acid) sodium (EDTMPS), an environmentally friendly reagent, was employed as an efficient depressant for flotation separation of calcite for the first time. In flotation experiments, it demonstrates that EDTMPS could strongly inhibit the flotation of calcite but barely affect the flotaiton behavior of scheelite, showing excellent dpress ability and selectivity. Based on a series of measurements including contact angle analysis, zeta potential, and XPS analysis, it was found that large amout of EDTMPS could be absorbed on the surface of calcite through strong chemical chelation reaction and thus inhibiting the further adsorption of NaOL. On the contrary, little EDTMPS was absorbed on that of scheelite owing to the negatively charged tungstate ions on the surface in relative terms. All in all, these results exhibit EDTMPS has excellent selective inhibition ability on calcite, which can be potentially applied in actual scheelite and calcite flotation separation process.
Źródło:
Physicochemical Problems of Mineral Processing; 2023, 59, 3; art. no. 168517
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The effect of polyacrylic acid on the surface properties of calcite and fluorite aiming at their selective flotation
Autorzy:
Zhang, C.
Gao, Z.
Hu, Y.
Sun, W.
Tang, H.
Yin, Z.
He, J.
Guan, Q.
Zhu, Y.
Powiązania:
https://bibliotekanauki.pl/articles/110577.pdf
Data publikacji:
2018
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
calcite
fluorite
selective flotation
polyacrylic acid
Opis:
In this study, the polyacrylic acid (PAA) was studied as a selective depressant for calcite in the selective flotation of fluorite and calcite, and the implications of this process for the separation of fluorite ore were studied using micro-flotation tests, and the results were analyzed with Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS) analyses. The flotation tests indicated that the preferential adsorption of PAA onto calcite rather than sodium oleate (NaOl) could selectively depress the flotation of calcite, allowing its separation from fluorite at pH 7. The zeta potential of calcite became more negative with the addition of PAA rather than with NaOl. However, the characteristic features of PAA adsorption were not observed for fluorite, suggesting that NaOl preferentially adsorbed on the surface of fluorite, or that PAA could be replaced by NaOl on the fluorite surface. FT-IR and XPS analysis were utilized to obtain a better understanding of the mechanism by which PAA was more strongly adsorbed on the calcite surface than NaOl. This was revealed to occur through chemical bonding between the carboxyl group of PAA and the hydroxyl groups of the Ca species on the calcite surface, modifying the structure of the adsorbed layer. A possible adsorption mechanism, along with a postulated adsorption mode for the surface interaction between PAA and calcite, is proposed.
Źródło:
Physicochemical Problems of Mineral Processing; 2018, 54, 3; 868-877
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Diagenetic alteration in low-Mg calcite from macrofossils : a review
Autorzy:
Ullmann, C. V.
Korte, C.
Powiązania:
https://bibliotekanauki.pl/articles/2059799.pdf
Data publikacji:
2015
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
diagenetic alteration
macrofossil calcite
isotopes
palaeoenvironment
Opis:
The quality of palaeoenvironmental reconstructions based on macrofossil carbonate critically depends on preservation of the shell material because post-depositional processes can modify its structural, chemical and isotopic composition, potentially overprinting or completely erasing palaeoenvironmental information. A suite of methods can be employed to evaluate the impact of diagenetic processes on the primary geochemical signatures of samples. Here we review the benefits and shortcomings of the most commonly employed optical (optical microscopy, cathodoluminescence microscopy, scanning electron microscopy) and chemical (trace element abundances, isotopic ratios) screening techniques used to assess the alteration degree of low-Mg calcite macrofossils and summarize the findings on diagenetic trends observed for elemental and isotopic systems in such materials. For a robust evaluation of the preservation state of biogenic calcite, it is advisable to combine a set of complementary techniques. Absolute limiting values of element and isotope ratios for discarding diagenetically altered materials cannot be universally applied, but should rather be evaluated on a case to case basis. The evaluation can be improved by analyses of diagenetic carbonate and altered fossil materials, which help constraining the diagenetic trajectories in the sampled specimens. Quantification of post-depositional alteration is possible, but in most cases the complexity of diagenetic systems hampers the possibility of retrieving original proxy values for palaeoenvironmental reconstructions from partially altered materials.
Źródło:
Geological Quarterly; 2015, 59, 1; 3--20
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Calcium carbonate mineralization. Part 1, The effect of poly(ethylene glycol) concentration on the formation of precipitate
Autorzy:
Polowczyk, I.
Bastrzyk, A.
Kozlecki, T.
Sadowski, Z.
Powiązania:
https://bibliotekanauki.pl/articles/110925.pdf
Data publikacji:
2013
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
calcium carbonate
calcite
vaterite
mineralization
PEG
Opis:
In this study, the role of polymer in precipitation has been examined by studying the effect of poly(ethylene glycol) (PEG) on the formation of calcium carbonate particles. The CaCO3 particles were characterized by several techniques, such as FTIR, XRD, SEM, and particle size distribution analysis. In the absence of polymer, the mixing of reagents in an aqueous solution led to the formation of calcite crystals. Introduction of poly(ethylene glycol) molecules reduced the rate of crystallization process, and the effect was concentration dependent. In the presence of 0.05, 0.1, and 0.5 % of PEG, after 5 minutes of precipitation initiation, vaterite microspheres appeared in the system and which were transformed into calcite crystals after 24 hours. The calcium carbonate obtained with PEG was characterized by smaller sized particles in comparison with the ones without polymer.
Źródło:
Physicochemical Problems of Mineral Processing; 2013, 49, 2; 631-639
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 62

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