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Synthesis of nano-structured duplex and ferritic stainless steel powders by dry milling and its comparison with wet milling

Shashanka R., Uzun Orhan, Chaira D.

Archives of Metallurgy and Materials

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2020

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Vol. 65, iss. 1

5--14

EN

In the present paper, elemental Fe, Cr and Ni powders were used to fabricate nano-structured duplex and ferritic stainless steel powders by using high energy planetary ball milling. We have studied the effect of milling atmosphere like wet (toluene) and dry (argon) milling of elemental Fe-18Cr-13Ni (duplex) and Fe-17Cr-1Ni (ferritic) powders for 10 h in a dual drive planetary mill. Stearic acid of 1wt.% was added during milling to avoid agglomeration. The dry and wet milled duplex and ferritic stainless steel powders were characterized by XRD, SEM and particle size analysis techniques. We have found that both the milling atmospheres have great influence in controlling the final particle morphology, size and phase evolution during milling. It was reported that dry milling is more effective in reducing particle size than the wet milling. The Nelson-Riley method of extrapolation was used to calculate the precise lattice parameter and Williamson-Hall method was used to calculate the crystallite size and lattice strain of both the stainless steel milled in argon atmosphere. Dry milled duplex and ferritic stainless steel were then consolidated by conventional sintering method at 1100, 1200 and 1300°C temperatures under argon atmosphere for 1 hour.

2

Mechano-chemical conversion of celestite in highly concentrated sodium carbonate media

Sezer Raşit, Arslan Cüneyt

Physicochemical Problems of Mineral Processing

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2019

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Vol. 55, iss. 2

324--335

EN

An effect of high-energy ball milling on the mechano-chemical conversion of celestite to strontium carbonate (SrCO3) was studied. A celestite ore was ground by a planetary ball mill in a highly concentrated sodium carbonate (Na2CO3) solution. The experimental study was carried out to determine the effects of milling time (15, 30, and 45 min) and Na2CO3 concentration (1, 1.25, and 1.5 M) on the particle size and SrCO3 percentage of the product. A celestite/ball weight ratio was selected as 1/10 and the volume of carbonate solution was calculated for the stoichiometric amount of sulfate in celestite, as constant. After filtering, washing and drying the precipitated SrCO3 sludge was analyzed by XRD, SEM-EDS. Powders were leached in HCl solution and analyzed by AAS in order to determine the SrCO3 amount in the product. A response surface methodology was applied via the Box-Behnken method for the results of particle size and SrCO3 percentage. Regression model coefficients were 98.61 and 98.14%, which were the results of compatibility as experimentally obtained and predicted by the model, respectively. The maximum amount of SrCO3, 96.84% and the minimum particle size, 10.297 μm were obtained with the maximum values of the parameters, 45 min, 1.5 M Na2CO3, and 450 rpm.

3

The effect of mechanical disintegration on whe straw biodegradability of wheat straw

Krátký L., Jirout T.

Inżynieria i Aparatura Chemiczna

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2013

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Nr 3

202--203

EN

Present-day operating biogas plants are based on the treatment of lignocellulosic biomass presented in such materials as agriculture and forestry wastes, municipal solid waste, waste paper, wood and herbaceous energy crops. The biodegradability of untreated substrates is generally very low because of physical and chemical barriers caused by structure of lignocelulosic biomass. Therefore, pretreatment of biomass is an essential step in order to increase biomass digestibility. This paper is devoted to the mechanical disintegration of straw by the newly developed prototype of mill named MACERATOR. Its effectiveness is evaluated by the energy requirement for disintegration of wheat straw, by changes in particle sizes and also by biogj tests.

PL

Obecnie, czynne biogazownie opierają się na obróbce masy lignocelulozowej, która zawarta jest w takich materiałach jak: rolnicze i leśne odpady, stałe odpady komunalne, zużyty papier, drewno i rośliny energetyczne. Biodegradowalność nieprzerobionych substratów ogólnie jest bardzo niska ze względu na ﬁzyczne i chemiczne bariery, spowodowane przez strukturę masy lignocelulozowej. Dlatego też obróbka biomasy jest istotnym etapem podniesienia jej fermentowalności. Artykuł ten poświęcony jest mechanicznej dezintegracji słomy pszennej za pomocą nowo utworzonego prototypu młyna o nazwie MACERATOR. Jego efektywność jest oceniana na podstawie zapotrzebowania energetycznego na dezintegrację słomy pszennej poprzez zmiany wymiaru cząstek i testów na wydajność biogazu.