The Study of the Melting of Waelz Oxide with an Increase in the Temperature of the Calcination Process

2021 ◽  
Vol 316 ◽  
pp. 705-710
Author(s):  
A.G. Ryazanov ◽  
A.V. Senin ◽  
V.D. Nasonov
Keyword(s):  
Partial Melting ◽  
Gas Phase ◽  
Lead Oxide ◽  
Elevated Temperatures ◽  
Lead Sulfate ◽  
Raw Material ◽  
Chemical Transformations ◽  
Calcination Process ◽  
Waelz Oxide ◽  
Negative Effect

Waelz-oxide is a raw material for the production of metallic zinc. Waelz-oxide contains impurities of zinc and lead chlorides and fluorides. Halides have a negative effect on the process of zinc electrolysis. Halides have a relatively low boiling point; therefore, they are removed into the gas phase by calcining Waelz-oxide at 800–850 °С. To intensify the process, calcination is sometimes carried out at elevated temperatures of 1100–1250 °С. However, an increase in temperature leads to partial melting and granulation of the calcined product. In the present work, the chemical and phase composition of the initial and calcined Waelz-oxide was studied. Thermodynamic modeling of phase and chemical transformations of Waelz-oxide components during heating has been performed. Experiments on calcination of Waelz-oxide in laboratory conditions at temperatures of 600–1250 °C were carried out. It was found that partial melting and granulation of Waelz-oxide is the result of the formation of fusible eutectics containing lead oxide. Lead oxide is formed as a result of decomposition of lead sulfate when heated above 1100 °C. A similar effect is not observed at a standard calcination temperature of 850 °C.

Mechanisms of Partial Melting of Metasomatized Mantle Ultramafic Rocks beneath Avacha Volcano, Kamchatka, and the Growth of Minerals from a Gas Phase in Fractures

Petrology ◽  
2020 ◽  
Vol 28 (6) ◽  
pp. 569-590
Author(s):  
V. N. Sharapov ◽  
A. A. Tomilenko ◽  
G. V. Kuznetsov ◽  
Yu. V. Perepechko ◽  
K. E. Sorokin ◽  
...  
Keyword(s):  
Partial Melting ◽  
Gas Phase ◽  
Ultramafic Rocks ◽  
Metasomatized Mantle

scholarly journals Clinoptilolite as a natural, active zeolite catalyst for the chemical transformations of geraniol

2021 ◽  
Author(s):  
Anna Fajdek-Bieda ◽  
Agnieszka Wróblewska ◽  
Piotr Miądlicki ◽  
Jadwiga Tołpa ◽  
Beata Michalkiewicz
Keyword(s):  
Reaction Time ◽  
Nitrogen Adsorption ◽  
Carbon Chain ◽  
Raw Material ◽  
Chemical Transformations ◽  
Renewable Biomass ◽  
Ft Ir ◽  
Catalyst Content ◽  
Favorable Conditions ◽  
Instrumental Methods

AbstractThis work presented the studies with the natural zeolite—clinoptilolite as the catalyst for the isomerization of geraniol. During the research, it turned out that the studied process is much more complicated, and not only isomerization takes place in it, but also dehydration, oxidation, dimerization, cyclization and fragmentation of the carbon chain. Geraniol is an organic raw material which can be obtained not only by a chemical synthesis but also from plants (renewable biomass) by distillation or extraction method, for example a source of geraniol can be a plant—geranium. Before catalytic tests clinoptilolite was characterized by the instrumental methods, such as: XRD, porosity studies—nitrogen adsorption at 77 K, SEM, EDXRF, and FT-IR. Gas chromatography analyses showed that the main products of geraniol isomerization process were 6,11-dimethyl-2,6,10-dodecatrien-1-ol and thumbergol. The selectivity of 6,11-dimethyl-2,6,10-dodecatrien-1-ol and thumbergol depended on the temperature, catalyst content and reaction time. These parameters were changed in the following ranges: 80–150 °C (temperature), 5–15 wt% (catalyst content) and 15–1440 min. (reaction time). The most favorable conditions for 6,11-dimethyl-2,6,10-dodecatrien-1-ol and thumbergol obtaining were: temperature 140 ºC, catalyst content 12.5 wt% and reaction time 180 min. At these conditions, the conversion of geraniol amounted to 98 mol%, and the selectivities of 6,11-dimethyl-2,6,10-dodecatrien-1-ol and thumbergol amounted to 14 and 47 mol%, respectively.

High Temperature Corrosion Behavior of Si-Containing Alloys in the Gas Phase of Air-(Na2SO4+25.7mass%NaCl)

2011 ◽  
Vol 696 ◽  
pp. 272-277 ◽  
Author(s):  
Toto Sudiro ◽  
Tomonori Sano ◽  
Akira Yamauchi ◽  
Shoji Kyo ◽  
Osamu Ishibashi ◽  
...  
Keyword(s):  
High Temperature ◽  
Gas Phase ◽  
Corrosion Behavior ◽  
Elevated Temperatures ◽  
High Temperature Corrosion ◽  
Ni Content ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
Corrosion Resistant Alloy ◽  
Si Content

The objective of this study is to develop an excellent corrosion resistant alloy for high temperature coating applications. The Si-containing alloys consisting of CoNiCrAlY and CrSi2 alloys with varying Si and Ni content respectively were prepared by spark plasma sintering (SPS) technique. The corrosion behavior of these alloys was investigated in the gas phase of air-(Na2SO4+25.7mass%NaCl) at elevated temperatures of 923, 1073 and 1273K. The results showed that CoNiCrAlY alloy with 30mass% Si content and CrSi2 alloy with 10mass% Ni content were the most effective materials for application in the gas phase of air-(Na2SO4+25.7mass%NaCl) due to the formation of protective Al2O3/SiO2 and SiO2 scale, respectively. Therefore, it is realized that CoNiCrAlY-30mass% Si and CrSi2-10mass% Si coating are very effective for improving of high temperature corrosion resistance of STBA21 steel.

scholarly journals A Robust Two-Step Process for the Efficient Conversion of Acidic Soybean Oil for Biodiesel Production

Catalysts ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 527 ◽  
Author(s):  
Gaojian Ma ◽  
Lingmei Dai ◽  
Dehua Liu ◽  
Wei Du
Keyword(s):  
Fatty Acid ◽  
Soybean Oil ◽  
Lower Cost ◽  
Immobilized Lipase ◽  
Acid Methyl Ester ◽  
Acid Value ◽  
Catalytic Performance ◽  
Raw Material ◽  
Biodiesel Production ◽  
Negative Effect

Acidic oil, which is easily obtained and with lower cost, is a potential raw material for biodiesel production. Apart from containing large quantity of FFAs (free fatty acids), acidic oil usually contains some amount of inorganic acid, glycerides and some other complex components, leading to complicated effect on lipase’s catalytic performance. Exploring the efficient process of converting acidic oil for biodiesel production is of great significance to promote the use of acidic oil. A two-step conversion process for acidic soybean oil was proposed in this paper, where sulfuric acid-mediated hydrolysis was adopted first, then the hydrolyzed free fatty acid, collected from the upper oil layer was further subject to the second-step esterification catalyzed by immobilized lipase Novozym435. Through this novel process, the negative effect caused by harmful impurities and by-product glycerol on lipase was eliminated. A fatty acid methyl ester (FAME) yield of 95% could be obtained with the acid value decreased to 4 mgKOH/g from 188 mgKOH/g. There was no obvious loss in lipase’s activity and a FAME yield of 90% could be maintained with the lipase being repeatedly used for 10 batches. This process was found to have a good applicability to different acidic oils, indicating it has great prospect for converting low quality oil sources for biodiesel preparation.

scholarly journals Particleboards from Recycled Thermally Modified Wood

Forests ◽  
2021 ◽  
Vol 12 (11) ◽  
pp. 1462
Author(s):  
Ján Iždinský ◽  
Zuzana Vidholdová ◽  
Ladislav Reinprecht
Keyword(s):  
Mechanical Properties ◽  
Urea Formaldehyde ◽  
Brown Rot ◽  
Decay Resistance ◽  
Raw Material ◽  
Modulus Of Rupture ◽  
Negative Effect ◽  
Serpula Lacrymans ◽  
Thermally Modified Wood ◽  
Modified Wood

In recent years, the production and consumption of thermally modified wood (TMW) has been increasing. Offcuts and other waste generated during TMWs processing into products, as well as already disposed products based on TMWs can be an input recycled raw material for production of particleboards (PBs). In a laboratory, 16 mm thick 3-layer PBs bonded with urea-formaldehyde (UF) resin were produced at 5.8 MPa, 240 °C and 8 s pressing factor. In PBs, the particles from fresh spruce wood and mixed particles from offcuts of pine, beech, and ash TMWs were combined in weight ratios of 100:0, 80:20, 50:50 and 0:100. Thickness swelling (TS) and water absorption (WA) of PBs decreased with increased portion of TMW particles, i.e., TS after 24 h maximally about 72.3% and WA after 24 h maximally about 64%. However, mechanical properties of PBs worsened proportionally with a higher content of recycled TMW—apparently, the modulus of rupture (MOR) up to 55.5% and internal bond (IB) up to 46.2%, while negative effect of TMW particles on the modulus of elasticity (MOE) was milder. Decay resistance of PBs to the brown-rot fungus Serpula lacrymans (Schumacher ex Fries) S.F.Gray increased if they contained TMW particles, maximally about 45%, while the mould resistance of PBs containing TMW particles improved only in the first days of test. In summary, the recycled TMW particles can improve the decay and water resistance of PBs exposed to higher humidity environment. However, worsening of their mechanical properties could appear, as well.

scholarly journals WOOD COMPONENTS AS SOURCES OF PENTO-CONTAINING RAW MATERIALS FOR SYNTHESIS OF USEFUL COMPOUNDS, PRODUCTS AND REAGENTS

2021 ◽  
Vol 64 (3) ◽  
pp. 107-115
Author(s):  
Irina A. Chetvertneva ◽  
Oleg Kh. Karimov ◽  
Galina A. Teptereva ◽  
Natalia S. Tivas ◽  
Eldar M. Movsumzade ◽  
...  
Keyword(s):  
Raw Materials ◽  
Condensation Reaction ◽  
Agricultural Waste ◽  
Monomer Unit ◽  
Paper Industry ◽  
Raw Material ◽  
Chemical Transformations ◽  
Covalent Bonds ◽  
Industry Waste ◽  
Wood Processing

The paper considers the main components and products of wood processing, agricultural waste, pulp and paper industry waste and qualifies them as sources of pentose-containing resource-renewable domestic raw materials. The article describes in detail the structural components of wood as a natural polymer, which contains aromatic and carbohydrate parts. It is noted that these poly-mers are promising as raw materials for the production of useful chemical products. The role of lignin, cellolose and hemicellulose in the design of mechanical and structural properties of wood is considered. The article considers the features of the sulfonation reactions of the lignin monomer unit depending on the pH of the medium: acidic, neutral and alkaline. There are three main reac-tions that occur simultaneously with lignin in the process of wood delignification during sulfite cooking, such as the sulfonation reaction, the hydrolytic destruction reaction, and the condensation reaction. It is shown that the lignin-hemicellulose matrix contains three types of interconnected mesh structures: the lignin itself; a network of covalent bonds of lignin with hemicelluloses, and a network whose structure is obtained due to the hydrogen bond and the forces of the physical inter-action of lignin and hemicelluloses. The features of chemical transformations of the monomeric aromatic link of lignosulfonate – phenylpropane unit in the processes of wood delignification, the main chemical reactions of wood raw material delignification under the conditions of sulfite and neutral-sulfite brews are shown. The method of quantitative determination of monosaccharides in the composition of the carbohydrate part is proposed.

scholarly journals Resilience to temperature and pH changes in a future climate change scenario in six strains of the polar diatom <i>Fragilariopsis cylindrus</i>

2015 ◽  
Vol 12 (14) ◽  
pp. 4235-4244 ◽  
Author(s):  
M. Pančić ◽  
P. J. Hansen ◽  
A. Tammilehto ◽  
N. Lundholm
Keyword(s):  
Climate Change ◽  
Growth Rates ◽  
Significant Interaction ◽  
Elevated Temperatures ◽  
Future Climate Change ◽  
Change Scenario ◽  
Ph Tolerance ◽  
Increased Temperature ◽  
Fragilariopsis Cylindrus ◽  
Negative Effect

Abstract. The effects of ocean acidification and increased temperature on physiology of six strains of the polar diatom Fragilariopsis cylindrus from Greenland were investigated. Experiments were performed under manipulated pH levels (8.0, 7.7, 7.4, and 7.1) and different temperatures (1, 5, and 8 °C) to simulate changes from present to plausible future levels. Each of the 12 scenarios was run for 7 days, and a significant interaction between temperature and pH on growth was detected. By combining increased temperature and acidification, the two factors counterbalanced each other, and therefore no effect on the growth rates was found. However, the growth rates increased with elevated temperatures by ~ 20–50 % depending on the strain. In addition, a general negative effect of increasing acidification on growth was observed. At pH 7.7 and 7.4, the growth response varied considerably among strains. However, a more uniform response was detected at pH 7.1 with most of the strains exhibiting reduced growth rates by 20–37 % compared to pH 8.0. It should be emphasized that a significant interaction between temperature and pH was found, meaning that the combination of the two parameters affected growth differently than when considering one at a time. Based on these results, we anticipate that the polar diatom F. cylindrus will be unaffected by changes in temperature and pH within the range expected by the end of the century. In each simulated scenario, the variation in growth rates among the strains was larger than the variation observed due to the whole range of changes in either pH or temperature. Climate change may therefore not affect the species as such, but may lead to changes in the population structure of the species, with the strains exhibiting high phenotypic plasticity, in terms of temperature and pH tolerance towards future conditions, dominating the population.

scholarly journals Effect of Temperature and Sisal Fiber Content on the Properties of Plaster of Paris

2018 ◽  
Vol 7 (4.20) ◽  
pp. 205 ◽  
Author(s):  
Aqil M. ALmusawi ◽  
Thulfiqar S. Hussein ◽  
Muhaned A. Shallal
Keyword(s):  
Mechanical Properties ◽  
Elevated Temperatures ◽  
Physical And Mechanical Properties ◽  
Fiber Content ◽  
Sisal Fiber ◽  
Effect Of Temperature ◽  
Plaster Of Paris ◽  
Micro Cracks ◽  
Recent Developments ◽  
Negative Effect

Recent developments in the production of ecologically friendly building composites have led to a renewed interest in the use of vegetable fibers as a reinforcement element. Traditional pure Plaster of Paris (POP) can suffer from the development of micro-cracks due to thermal expansion. Therefore, sisal fiber was studied for its potential as an ecological element to restrict and delay the development of micro-cracks in POP. Different sisal proportions of 0, 2, 4, 6, 8 and 10 wt. % of POP were used to characterize the physical and mechanical properties of POP at the ambient temperature. Then, the effects of temperatures of 25, 100, 200, 300, 400 and 500  were investigated. Results proved that the composite of 10% sisal fiber had the best mechanical properties. Also, when the fiber content was increased, the composite’s performance was enhanced, becoming better able to resist elevated temperatures. However, raising the temperature to 300 or above had a negative effect on the mechanical properties, which were significantly decreased due to the degradation of the sisal fiber. 

scholarly journals The Fabrication of Geopolymer Foam Composites Incorporating Coke Dust Waste

Processes ◽  
2020 ◽  
Vol 8 (9) ◽  
pp. 1052
Author(s):  
Buczkowska Katarzyna ◽  
Chi Hiep Le ◽  
Petr Louda ◽  
Szczypiński Michał ◽  
Totka Bakalova ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Experimental Investigation ◽  
Residual Strength ◽  
Elevated Temperatures ◽  
Composite Foam ◽  
Coke Dust ◽  
Composite Foams ◽  
Negative Effect ◽  
Geopolymer Binder

This paper reports the results of an experimental investigation on the mechanical properties of geopolymer foams incorporating filler from the coke dust waste (CDW). In this work, CDW was used to replace a part of geopolymer paste at 5%, 10%, 20%, and 30% by geopolymer binder mass. The physico-mechanical properties and thermal resistance against high temperatures of CDW/geopolymer foams are presented. The primary results obtained show that the use of CDW in the production of geopolymer foam composites made it possible for them to achieve relatively good mechanical properties. However, the incorporation of the CDW into the geopolymer had a slightly negative effect on thermal conductivity, but significantly improved the mechanical strength of the final product. Moreover, this waste also helped the composite foam to achieve a structure with more uniform open pores distribution, compared to the pure foam. After exposure to elevated temperatures, the residual strength of the composite foams maintained well compared to the pure foams.

Investigation of Flotation Separation of Elemental Sulfur and Sulfides from Lead Sulfate from Low-Temperature Leaching of Lead Concentrates

2020 ◽  
Vol 989 ◽  
pp. 537-542
Author(s):  
Kirill A. Karimov ◽  
Aleksei V. Kritskii ◽  
Sergey E. Polygalov
Keyword(s):  
Low Temperature ◽  
Filter Cake ◽  
Elemental Sulfur ◽  
Lead Sulfate ◽  
Raw Material ◽  
Granulation Process ◽  
Flotation Concentrate ◽  
Autoclave Leaching ◽  
Sulfate Lead ◽  
Concentrate Yield

Monometallic ore that is mostly lead found in nature is extremely rare. The main natural raw material for the lead production is sulfide polymetallic ores. In this study the filter cake processing after the low-temperature autoclave leaching of the lead concentrate to produce a sulphide concentrate and lead tailings was investigated The study of component separation was carried out using the methods of mathematical planning of the second order experiment. The following optimal costs of reagents, g/t: 140-200 potassium xanthate, 70-100 foaming agent, 100 copper sulfate; the concentrate yield is 41-43 %; it is extracted to, %: 95 Fe, 49 Cu, 96 Zn, 98 S0, 18-19 Pb. At flotation 18,7% of lead goes into flotation concentrate and 80.5% is lead sulfate. The rectification of the obtained concentrate by flotation did not give acceptable results, since the yield of the foam product in all experiments was 93-96%. For the separation of lead sulphate from sulphur-sulfide concentrate was used in the granulation of sulfur in the following conditions: t = 145 °C, Po2 = 0,0-0,5 MPa, τ = 60 to 120 min. In the granulation process of the flotation concentrate is a division of lead sulfate and elemental sulfur, the sulfate lead content in sulphur-sulfide phase is decreased from 28.44 % to 3.5 %, its recovery in a sulfate filter cake has reached 90.6 %

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