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1

The relationships between the kinetic grinding parameters with interstitial fillings and the liberation degree of a chromite ore

Umucu Yakup, Deniz Vedat, Gursoy Hakan Y., Tokcan Isıl, Arsoy Zeyni

Physicochemical Problems of Mineral Processing

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2023

|

Vol. 59, iss. 5

art. no. 168254

EN

In this study, the relationships between the liberation degree and the kinetic breakage parameters of a chromite ore obtained from the Burdur (Türkiye) were examined under the laboratory conditions. Firstly, liberation degrees for chromite particles were determined by the particle counting method in a metal microscope for 4 different size groups. Secondly, the breakage parameter of chromite ore which was dry ground with a ball mill was obtained using standard test methods. Additionally, the model parameters were also determined for the fractional interstitial fillings (U) of the chromite sample. Thirdly, the kinetic grinding parameters were compared with the liberation degree of the chromite sample. As a result of the tests, a very good correlation was obtained with R2=0.998, and regression analysis in the grinding processing of the chromite ore was used to verify the validity of the relationship parameter of Si that was produced. To these, it was found that interstitial fillings (U=0.6, 0.8, 1.0, and 1.2) have an effect on the grinding.

2

Optimizing the removal of iron oxide from Egyptian feldspar ore

Yassin E. Khaled, Elbendari A.M., Hassan El-Sayed R. E.

Physicochemical Problems of Mineral Processing

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2023

|

Vol. 59, iss. 6

art. no. 176420

EN

The demand for feldspar as a raw material for various industrial applications continuously increases. Feldspar is a primary raw material in manufacturing ceramics, glass, fillers, welding electrodes, and enamel. Feldspar is often associated with iron oxide, which decreases its economic value and hinders its industrial application. The present work aimed at reducing iron oxide content in Egyptian feldspar ore from the Wadi Zerabi locality. Ball milling was used for preparing feldspar feed of size -250+45μm. Carpco dry high-intensity magnetic separation followed by acid leaching processes were carried out in order to decrease the iron contamination and increase the feldspar content. A Box-Behnken statistical design was used to optimize the magnetic separation results. From a feldspar feed containing 1.40% Fe2O3, a non-magnetic concentrate of 0.25% Fe2O3 was obtained. The Fe2O3 removal reached up to 82% with a high yield as the % weight of non-magnetic feldspar reached up to 97.5%. The leaching process further reduced the iron oxide content down to 0.19 %. Also, the feldspar whiteness was improved from 65.17% in the original ore to 85.60% in the leached product.

3

Eti Copper Siirt flotation plant revision studies

Kara Yaşar, Tatar Ali, Hasyamanlar Ahmet

Physicochemical Problems of Mineral Processing

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2023

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Vol. 59, iss. 5

art. no. 166260

EN

Several optimization studies were made to increase metal recovery and reduce operational costs of the concentrator in Siirt Madenköy copper mine. In consequence of these studies, effects of the changes in operating parameters, cost and plant recovery will be examined at this article. In this article, we will discuss two important revision studies, which are (i) replacement of 500 mm hydrocyclone set used in ball mills with 350 mm of hydrocyclone set, (ii) replacing the present Ball Mill with a SAG mill. Correspondingly elimination of the crushing and screening plant, (iii) increasing the scavenger cells from 4 to 6 by the addition of 2 more cells. In consequence with this feeding the middling tail to the increased scavenger cells which was treated as a part of final tail before this change. We will examine the effect of all these changes to the final recovery, concentrate grade and final cost.

4

Wykorzystanie sieci neuronowych do modelowania pracy młyna kulowego w Cementowni WARTA S.A.

Śnieżyński Bartłomiej, Gajewski Paweł, Stępień Piotr, Roszczynialski Wojciech K., Golonka Paulina, Wolski Grzegorz

Materiały Budowlane

|

2023

|

nr 8

12--17

PL

Zastosowanie Sztucznych Sieci Neuronowych (SSN) do sterowania procesem przemiału cementu jest w pełni uzasadnione ze względu na złożoność procesu mielenia oraz nieliniowość charakteryzujących go parametrów. Stabilna praca młyna uzyskana przy wsparciu samouczących się SSN może przełożyć się na minimalizację jednostkowego zużycia energii przy utrzymaniu właściwego stopnia rozdrobnienia. Jako dane wejściowe zasilające algorytm SSN wykorzystano wybrane parametry technologiczne monitorowane podczas pracy młyna kulowego pracującego w warunkach przemysłowych. Eksperymenty wykazały, że mały błąd predykcji dają modele uwzględniające małą liczbę parametrów, biorące pod uwagę dane wejściowe z krótszego okna czasowego i 30-minutowym oknem wygładzania danych wejściowych. Najlepsze konfiguracje sieci neuronowej pozwalają na predykcję parametrów pracy młyna ze średnim bezwzględnym błędem procentowym poniżej 5% dla horyzontu czasowego 10 min oraz poniżej 7% dla horyzontu czasowego 15 min.

EN

The use of Artificial Neural Networks (ANNs) to control the cement grinding process is fully justified, taking into account the complexity of the grinding process and the non-linearity of its parameters. Stable operation of the mill, obtained with the support of self-learning ANNs, may translate into minimization of unit energy consumption while maintaining the desired degree of fragmentation. As input data powering the ANN algorithm, selected technological parameters monitored during the operation of the ball mill in an industrial setting were used. Experiments have shown that models with a smaller number of parameters, taking into account input data from a shorter time window and a 30-minute input smoothing window, yield a smaller prediction error. The best configurations of the neural network allow for the prediction of the mill operation parameters with an average absolute percentage error of less than 5% for the time horizon of 10 minutes and less than 7% for the time horizon of 15 minutes.

5

Geopolymer Concrete Production by Using Nano-Bauxite Binder

Salman Sadeq Dawood, Jubier Najwa J., Al-Zubaidi Aseel B.

Journal of Ecological Engineering

|

2023

|

Vol. 24, nr 10

305--314

EN

Iraqi bauxite ore was used in the manufacturing of geopolymer mortar and concrete. To de-hydroxylate and turn bauxite into an amorphous phase, it was heated to 650 degrees Celsius. Mixing bauxite nanoparticles with an active alkaline solution produces a geopolymer of high grade due to their high efficiency. The nano-bauxite geopolymer mortar is produced following ASTM C109 with various quantities of alkaline solution with molarity (8, 10, 12, and 14). At 3, 7, and 28 days, the maximum compressive strength of mortar with a molarity of 12 was 20.2, 49.7, and 65.3 MPa, respectively. The same quantity of molarity for the mortar was utilized for the production of geopolymer concrete using an alkaline solution. The weight of nano bauxite was substituted for the percentage of nano-glass and carbon nano-tubes that were included in the geopolymer concrete. This resulted in the utilization of nano-glass and carbon nano-tubes, the best ratios are 8% silica merge with 0.01% of carbon nano-tubes. At the age of 28 days, the water absorbency value was found to be 1.78%, and it was noted that the increased compressive strength reached 81.4 MPa. For the polymerization and performance hardening of samples at low temperatures (20±3 °C), geopolymers with nano-bauxite binders were manufactured without heat treatment. The increased compressive strength as well as resistance to freezing and thawing tests are a result of the superior performance and high requirements of nano-materials. XRD examination was performed, many geopolymer phases were generated, and the bond structures between alumina and silica were observed; these results confirm the development of geopolymer.

6

The numerical techniques application in the ball mill comminution process modelling

Pawlos Witold, Dominiczak Przemysław

Cuprum : czasopismo naukowo-techniczne górnictwa rud

|

2023

|

nr 1-2

47--53

EN

The preliminary results of comminution process numerical simulations have been presented in this paper. The numerical prediction has been based on discrete elements method (DEM) for solid modelling and smoothed particles hydrodynamics method (SPH) for modelling a continuous medium – liquid. The one way numerical coupling between solid and liquid has been applied. The ball mill working in production line in O/ZWR has been modelled. The considered ball mill is used to copper ore comminution process. The numerical calculations have been carried out for different mill rotation speed.

PL

W artykule przedstawiono wstępne wyniki numerycznych symulacji procesu rozdrabniania. Prognozowanie numeryczne zostało oparte na metodzie elementów dyskretnych (DEM), wykorzystanej dla modelowania cząstek stałych, oraz na metodzie symulacji hydrodynamicznej (SPH) dla modelowania w ośrodku ciągłym – ciecz. Zastosowano jednokierunkowe sprzężenie numeryczne pomiędzy fazą stałą a ciekłą. Młyn kulowy, zainstalowany w ciągu technologicznym ZWR, został wytypowany jako obiekt modelowania. Rozpatrywany młyn pracuje jako urządzenie rozdrabniające rudę miedzi. Obliczenia numeryczne przeprowadzono dla różnych prędkości obrotowych młyna.

7

Selective comminution and grinding mechanisms of spent carbon anode from aluminum electrolysis using ball and rod mills

Ni Chao, Zhou Shaoqi, Gao Jixuan, Bu Xiangning, Chen Yuran, Alheshibri Muidh, Xie Guangyuan, Li Biao

Physicochemical Problems of Mineral Processing

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2022

|

Vol. 58, iss. 3

art. no. 145667

EN

The recovery of spent carbon anode (SCA) materials plays important roles in environment protection and resources recycling, while this cannot be efficiently achieved without liberation. In this study, grinding characteristics of spent carbon anode from aluminum electrolysis in both ball mill and rod mill were analyzed, and compared based on the utilization of the selective Fuerstenau upgrading curves. In addition, the different grinding mechanisms of ball and rod milling were evaluated by analyzing the shape factor and surface roughness of the ground samples. Results of mineralogical characterizations indicated that carbon particles (d50 = 46.86 μm) presented in the SCA were closely associated with cryolite particles. At 5 min grinding time, the maximum selective comminution factor (β) values of ball milling and rod milling were 2.00 and 1.63, respectively, indicating a higher degree of selective comminution of SCA was achieved from ball milling. Comparisons of the valuable component content (cv, cum) of -125 μm ground particles and the shape characterizations of 74–125 μm ground particles generated from ball and rod milling manifest that a direct relationship exists between the degree of selective comminution and the grinding mechanism.

8

Improvement of the accuracy of Hogg and Fuerstenau's model in predicting the power draw of ball mills based on determining the grinding media’s dynamic voidage

Golpayegani Mohammad Hasan, Rezai Bahram

Physicochemical Problems of Mineral Processing

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2022

|

Vol. 58, iss. 6

art. no. 153380

EN

In the development of tumbling mills' power models, the voidage of grinding media is assumed to be static and equal to 40%. While the grinding media’s voidage is dynamic; and hence is varied by changing the operating parameters. In this paper, to improve the Hogg and Fuerstenau model's accuracy in predicting the ball mills' power draw, the grinding media's static and dynamic voidage was studied for Bond's proposed ball size distributions (BSD) for the ball mills' first filling. To this end, by scaling down balls to one-tenth of actual size, developing a novel method to measure the dynamic voidage, and employing the three-level factorial method, a separate empirical model was developed for determining the dynamic voidage of each Bond's BSD with respect to mill's fractional filling and rotating speed. Moreover, using the multiple regression method, a general empirical model was derived to determine the dynamic voidage of each supposed BSD based on calculating the mean absolute deviation of balls diameter (MAD). Results indicated that grinding media's dynamic voidage increases with an increase in rotating speed and a decrease in fractional filling and balls diameter's MAD. The maximum and minimum static and dynamic voidage occurred for the seventh and first Bond's BSDs. By employing an industrial database and analyzing the mean absolute percentage error (MAPE) of predicted ball mills' power draw, it was found that the Hogg and Fuerstenau model's accuracy enhances by calculating the load's bulk density based on the grinding media's dynamic voidage.

9

Proces rozdrabniania w młynie kulowym opisany teorią momentów statystycznych

Olejnik Tomasz P.

Technologia i Jakość Wyrobów

|

2021

|

R. 66

148--158

PL

W artykule przedstawiono wyniki badań mających na celu eksperymentalną weryfikację modelu rozdrabniania w młynie kulowym w oparciu o teorię momentów statystycznych. Badania kruszenia materiałów skalnych o różnej twardości przeprowadzono w młynie laboratoryjnym o objętości 6 dm3 . Dla określonych odstępów czasu pobierano próbki surowca z młyna i wykonano analizy granulometryczne, określając udziały procentowe produktu. Mielono cztery rodzaje materiału skalnego: gabro, kwarcyt, sjenit i piaskowiec żelazisty. Obliczono wartości momentów zerowych, momentów centralnych oraz współczynniki spłaszczenia i asymetrii. Zbadano zależności między tymi wartościami w funkcji czasu mielenia.

EN

Results of investigations which aimed at experimental verification of the model of grinding in a ball mill based on the theory of moments are presented in the paper. Grinding tests for rock materials with different hardness were carried out in a laboratory mill 6 dm3 in volume. Particle size distribution of the material was determined in specified time intervals. Four types of rock material were milled: gabro, quartzite, syenite and ferruginous sandstone. The values of zero moments, central moments and coefficients of flattening and asymmetry were calculated. Relationships between these values as a function of milling time were examined.

10

Dobór urządzenia łagodnego rozruchu na przykładzie młyna kulowego

Bortnowski Piotr, Gładysiewicz Lech

Transport Przemysłowy i Maszyny Robocze

|

2019

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Nr 1

56--63

PL

Przeprowadzono analizę możliwości zastosowania sprzęgła hydrokinetycznego oraz inteligentnej przekładni CST w układzie napędowym młyna kulowego służącego do mielenia rudy miedzi. Głównym celem rozważań nad możliwością instalacji tego typu urządzeń było zapewnienie łagodnego rozruchu młyna pod pełnym obciążeniem. Zakres pracy obejmował wykonanie modelu bryłowego, rozpatrywanego młyna w celu wyznaczenia momentów bezwładności obiektu, oraz przeprowadzenie obliczeń dynamicznych. Wyznaczono parametry, pozwalające na optymalny dobór sprzęgła hydrokinetycznego.

EN

The article describes the use of a fluid coupling and CST drive in the ball mill drive system. The ball mill is used for grinding copper ore. The selected devices ensure soft start the loaded mill. It was necessary to make a 3D model of a ball mill to determine its moment of inertia. The results of dynamic calculations allowed the selection of the suitable fluid coupling and CST drive system.

11

The effect of ball size distribution on power draw, charge motion and breakage mechanism of tumbling ball mill by discrete element method (DEM) simulation

Panjipour R., Barani K.

Physicochemical Problems of Mineral Processing

|

2018

|

Vol. 54, iss. 2

258--269

EN

In this research, the effect of ball size distribution on the mill power draw, charge motion regime and breakage mechanism in a laboratory ball mill was studied using the discrete element method (DEM) simulation. The mill shell and crushing balls were made of Plexiglas® and compressed glass, respectively. Modeling was performed using Particle Flow Code 3D (PFC3D). Model parameters were back-calculated by comparing the power draws and images obtained from simulation and laboratory test works. After determining the model parameters, the mill was simulated in mill fillings of 15, 20, 25, 30, 35 and 40% with ball media of 2 and 2.5 cm in diameter. For every mill filling, the numbers of big and small balls were changed and 11 scenarios were chosen. The results showed that at a constant mill filling, the power draw was changed with changing the ball size distribution and for all mill fillings the maximum power draw occurred when the fraction of small balls was between 30-40%. The effect of ball size distribution increased with increasing mill filling and for the mill filling of 35%, the ball size distribution had the maximum effect on the power draw. When the mill charge contained mono-sized balls, the ball flow regime inside the mill transited to the cataracting and impact breakage was the main breakage mechanism. Increasing the fraction of big balls from 0 to 70% led the flow of balls into the cascading regime and breakage mechanism to attrition.

12

Testy mielenia koksiku z wykorzystaniem młyna kulowego

Micorek T., Robak J., Rejdak M., Różycki G., Jakubina G.

Piece Przemysłowe & Kotły

|

2017

|

Nr 1

1--5

PL

W pracy przedstawiono wyniki testów mielenia koksiku do uziarnienia poniżej 0,2 mm w młynie bębnowym kulowym. Jako mielniki zastosowano polidyspersyjne złoże kul ceramicznych. Mielenie prowadzono w sposób periodyczny w czasie 15 godzin, pobierając w określonych odcinkach czasowych próbkę produktu mielenia. Surowiec wyjściowy i próbki produktu poddano analizie rozkładu ziarnowego. Stwierdzono, że możliwe jest zmielenie koksiku w stopniu zapewniającym uzyskanie ponad 90 % m/m w produkcie ziaren o rozmiarze poniżej 0,2 mm. Proces mielenia przebiegał najefektywniej w cią-gu pierwszych pięciu godzin procesu, wydłużenie czasu trwania procesu znacznie zmniejszyło efektywność procesu. Optymalnym rozwiązaniem w skali przemysłowej może być wykorzystanie młynów bębnowych w systemie mielenia wielozabiegowym, zamkniętym.

EN

The paper presents the results of coke breeze grinding tests for particle sizes below 0.2 mm in a ball drum mill. A polydispersed ceramic balls were used as a grinding aid. Grinding was carried out in a batch manner during 15 hours, collecting a sample of the grinding product at specified time intervals. The starting raw material and product samples were analyzed for grain size distribution. It was found that it is possible to grind the coke breeze to a degree that provides more than 90% m / m in grains with a size below 0.2 mm. The milling process was the most effective during the first five hours of the process, the longer process duration significantly reduced the efficiency of the process. An optimal solution on an industrial scale can be the use of drum mills in a multi-gear and closed grinding system.

13

Investigation on the particle size and shape of iron ore pellet feed using ball mill and HPGR grinding methods

Abazarpoor A., Halali M.

Physicochemical Problems of Mineral Processing

|

2017

|

Vol. 53, iss. 2

908--919

EN

An effect of a grinding method, that is ball mill and high pressure grinding rolls (HPGR), on the particle size, specific surface area and particle shape of an iron ore concentrate was studied. The particle size distribution was meticulously examined by sieve, laser and image analyses. To measure the specific surface area of particles, Brunauer-Emmett-Teller (BET) and Blaine methods were used. It was found that for samples having equal Blaine specific surface areas numbers, the amount of fine particles produced in HPGR was higher than that produced in a ball mill. A higher surface area was observed from HPGR treatment in comparison to ball mill grinding, provided by a higher porosity, cracks, roughness and new surfaces. A shape factor of particles was determined using the circularity, roughness, and aspect ratio. It was also observed that HPGR produced particles that were more elongated, less circular and rougher than those processed by the ball mill.

14

Porównanie właściwości cementów portlandzkich produkowanych w różnych układach przemiałowych

Baran T., Pichniarczyk P.

Cement Wapno Beton

|

2017

|

R. 21/83, nr 6

477--488

PL

W przemyśle cementowym najbardziej rozpowszechnionymi do mielenia cementu są młyny kulowe, pracujące w obiegu zamkniętym. W Polsce, w ostatnich latach, uruchomiono dwie instalacje młynów pionowych do przemiału cementu. W pracy przedstawiono wyniki badań właściwości cementów wyprodukowanych w młynie misowo rolkowym i kulowym, w jednej cementowni i z tego samego klinkieru. Młyn kulowy pracował w obiegu zamkniętym z nowoczesnym separatorem „Sepax”. Stwierdzono, że w porównaniu do młyna misowo rolkowego cementy z młyna kulowego zawierają znacznie więcej gipsu półwodnego, co świadczy o większym stopniu odwodnienia gipsu. Niezależnie od układu przemiałowego, cementy tej samej klasy mają bardzo zbliżony skład ziarnowy. Wytrzymałość cementów z młyna pionowego jest większa od cementów z młyna kulowego. Zgodność cementów z młyna misowo rolkowego z domieszkami: melaminowo-formaldehydową i polikarboksylaną jest nieznacznie korzystniejsza, natomiast w przypadku lignosulfonianu zależność jest odwrotna. Natomiast zmniejszenie konsystencji w czasie jest zbliżone w przypadku cementów 32,5, a dla klasy 42,5 jest szybsze w przypadku cementu z młyna misowo rolkowego.

EN

In cement industry the most popular for cement grinding are the ball mills, working in closed circuit. In Poland in last years two roller mills for cement grinding were installed. In the paper the results of cements properties examination which were produced in roller mill and ball mill in one cement plant and of one clinker. The ball mill worked in closed circuit with Sepax separator. It was found that in comparison to roller mill cements from ball mills have higher content of semihydrate gypsum which confirm the higher gypsum dehydroxylation. Independently of mill system used the cements of the same grade have very similar grains size distributions. However, the strength of cement ground in roller mill has higher strength. Compatibility of cement from roller mill with two admixtures: melamine-formaldehyde and polycarboxylate is higher than from ball mill, but for the lignosulfonate the situation is opposite. However, the decrease of consistency with time is similar in the case of cements 32,5 and for 42.5 is quicker for cement from roller mill.

15

Operating conditions of slide bearings of mills used in KGHM Polska Miedź S.A.

Olszewski A., Łubiński J. I., Pawlos W., Kuźba B.

Tribologia

|

2016

|

nr 4

177--189

EN

The paper contains the results from a technical analysis of the conditions of the operation of hydrodynamic bearings supporting the drums of ore processing mills at KGHM Polska Miedź S.A. A theoretical analysis was performed on the grounds of onsite examination and measurements of principal dimensions of the bearings of interest. The computer simulation covered the characteristics of the oil film in the bearings as a function of bearing clearance, load, lubricant viscosity, and journal tilting in relation to two planes (horizontal and vertical). The results of the analysis indicate that the bearings currently operate close to maximum capacity and that there is a significant deflection of the Bering journals under the applied joint load of the drum’s own weight and the process load of grinders and slurry. The current extent of tilting can cause oil film breakage at the bearing’s edge. The result of calculations amended by bearings’ examination and measurements allowed the formulations of conclusions regarding the current state of the bearings and evaluated load conditions. Guidelines were established for later developments in the capacity and reliability of the bearings.

PL

W artykule przedstawiono analizę warunków pracy łożysk hydrodynamicznych młynów rudy zainstalowanych w KGHM Polska Miedź S.A. Analiza teoretyczna została poprzedzona wizją lokalną oraz wykonaniem stosownych pomiarów geometrii czopów i łożysk. Symulacja komputerowa charakterystyk filmu olejowego łożysk obejmowała zbadanie wpływu wartości luzu łożyskowego, obciążenia, lepkości oleju smarującego oraz ukosowania czopa w dwóch płaszczyznach (poziomej i pionowej). Analiza wskazuje, że zainstalowane łożyska pracują na granicy swojej nośności, a ugięcie osi czopów spowodowane ugięciem walczaka pod działaniem ciężaru własnego i nadawy wywołuje znaczne ukosowanie czopa w panwi mogące prowadzić do przerywania filmu olejowego na krawędziach zewnętrznych. Przeprowadzone obliczenie uzupełnione o oględziny pomiary łożysk wykonane w KGHM Polska Miedź S.A. pozwoliły na sformułowanie wniosków odnośnie do stanu istniejących łożysk, ich obciążenia oraz możliwości zwiększenia nośności i niezawodności.

16

Kinetic grinding test approach to estimate the ball mill work index

Gharehgheshlagh H. H.

Physicochemical Problems of Mineral Processing

|

2016

|

Vol. 52, iss. 1

342--352

EN

The standard Bond method is the most acceptable method for designing and selecting ball/rod mills described by their basic parameter called work index (Wi). The standard Bond method is a tedious time consuming procedure requiring at least 7 – 10 grinding cycles, so that many researchers have tried to simplify this method to be able to perform a rapid calculation of a work index. This study aims to develop a new approach toward estimating the Bond ball mill work index (BBWI) by applying a series of kinetic grinding tests with Bond standard mill. Establishing a series of relationships between grinding parameters and Bond equation parameters, this approach is fast and practical due to eliminating laboratory control steps while reducing the number of milling steps. In this scope, thirteen ore samples were used to compare Wi values obtained by standard Bond method with those of the proposed kinetic approach. The kinetic periods were determined as 0.33, 1, 2, 4 and 8 minutes. The results of kinetic tests were found to be logical and acceptable as they were so close to the values obtained by Bond standard method, for all samples error was ≤ 2.60%. It was therefore concluded that the proposed approach could be considered as a simple yet practical alternative for the standard Bond method.

17

First-order and second-order breakage rate of coarse particles in ball mill grinding

Barani K., Balochi H.

Physicochemical Problems of Mineral Processing

|

2016

|

Vol. 52, iss. 1

268--278

EN

It has been observed by many authors that the breakage rates of coarse particles in a ball mill slow down with increasing grinding time and deviate from the first order. In this paper it is intended to find out whether the breakage rates of coarse particles obey second-order kinetics or not. For this purpose, quartz, limestone, iron ore and a mixture of quartz/limestone (weight ratio of 1:1) were selected as a ball mill feed. The first-order breakage rate was determined for the four particle sizes of quartz, limestone, iron ore and the mixture of quartz/limestone. Results indicating good first-order kinetics were obtained with the fine-sized particles (-1.2+1 mm, -0.6+0.42 mm). However, the coarse-sized particles (-5+4 mm, -3.15+2.5 mm) showed deviations from the first order. These coarse particles were in the abnormal breakage region. The second-order breakage rate was determined for the coarse particles (-5+4 mm, -3.15+2.5 mm). It can be seen that, for both sizes and all the materials, the second-order plot had better fit than the first-order plot. Also, it can be concluded that the second-order kinetics could model the breakage of coarse particles better than the first-order kinetics, and the validity of the second-order breakage rate was increased with increasing particle size. However, it is suggested to examine the validity of the second-order breakage rate kinetics for other materials and particle sizes.

18

Wpływ kąta pochylenia na chropowatość powierzchni złożonych po obróbce frezem kulistym

Burek J., Żurek P., Żurawski K.

Mechanik

|

2016

|

R. 89, nr 10

1478--1479

PL

W artykule przedstawiono wpływ kąta pochylenia frezu kulistego na chropowatość powierzchni po obróbce wykończeniowej elementów o złożonych kształtach.

EN

The article presents the influence of ball mill inclination angle on complex surfaces roughness at the finishing phase.

19

Kierunki rozwoju młynów do mielenia surowców i spoiw mineralnych

Sidor J.

Materiały Ceramiczne

|

2016

|

T. 68, nr 1

61--69

PL

Praca zawiera opisy budowy i działania najnowszych młynów stosowanych w procesach mielenia surowców mineralnych do produkcji cementu i klinkieru cementowego, a także wapna, gipsu i węgla. Są to nowe konstrukcje młynów grawitacyjnych rurowo-kulowych, młynów wysokoenergetycznych wibracyjnych i planetarnych oraz wysokociśnieniowych młynów walcowych, zwanych prasami. Młyny te użytkowane są jako młyny wstępne lub młyny finalne. Młyny wysokoenergetyczne cechuje ponad dwukrotnie większa moc jednostkowa przypadająca na jednostkę objętości komory młyna. W młynach wibracyjnych moc ta jest 3-5 razy większa od mocy jednostkowej młyna kulowego, a w młynach planetarnych Hicom 100-150 razy. Duże moce umożliwiły budowę młynów o dużych wydajnościach, mniejszych wymiarach i masie oraz mniejszym jednostkowym poborze energii. Inny kierunek rozwoju młynów dotyczy wysokociśnieniowych młynów walcowych, do których należą młyny Beta Mill, Horo Mill i Premill. W pracy zamieszczono główne kierunki rozwoju konstrukcji tych młynów obejmujące wzrost wymiarów komór mielących i mocy układów napędowych, nowe rozwiązania głównych zespołów roboczych oraz niektóre parametry młynów.

EN

The paper presents main directions in development of mills used in milling processes of mineral raw materials for cement production and cement clinker, lime, gypsum, and coal. These are new constructions of gravity (ball-pipe) mills and high energy mills, including vibratory, planetary and high pressure roll mills also called presses. These mills are used as preliminary or final mills. The high-energy mills have more than twice output power per volume unit of the mill chamber, when compared to the gravity mills. The vibratory mills are characterized by 3-5 times bigger output power, whereas the Hicom planetary mills have 100-150 bigger output power. The bigger power made possible the construction of mills with larger capacities, smaller sizes and weight, and lower power consumption. The other direction concerns the development of high pressure grinding rolls (HPGR) that include Beta Mill, Horo Mill and Premill. The paper reports some parameters of the mentioned mills and the main directions in development of their construction, that is, an increase in dimensions of grinding chambers and power of drive systems, and new solutions of main working units.

20

Effect of graphene as anti-settling agent for magnetorheological fluid

Thanikachalam J., Nagaraj P., Hikku G. S.

Journal of Achievements in Materials and Manufacturing Engineering

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2016

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Vol. 77, nr 2

49--56

EN

Purpose: Magnetorheological fluids are field-responsive fluids containing magnetic particles suspended in a suitable medium. In this proposed work, the iron powder was dispersed in silicone oil to obtain magnetorheological fluid. These fluids can be transformed from liquid-like state to solid-like state within milliseconds by applying magnetic field and vice versa. The particles arrange as chain like pattern with the application of magnetic field, increasing the yield strength of the fluid. However, when the shear stress reaches the critical value, the chain like pattern breaks causing reduction in yield strength. One of the major limitations of these fluids is that the suspended particles settle down quickly forming cake like structure at the bottom, which is very difficult to re-disperse. Design/methodology/approach: The present study focuses on increasing the Sedimentation time of the fluid by adding suitable Nano additives. For this purpose graphene nanoparticles with atomic thickness were introduced as an additive to decrease the sedimentation of the fluid. The added graphene sheets (gap-fillers) filled the interspaces of Iron particles and improved the sedimentation resistance. Different quantities of graphene were added (0.5 g, 1.5 g, 2.5 g and 3.5 g) and their normalized height was calculated with time. Interpolation method was also done to find the sedimentation values with Graphene addition which were not done experimentally. Findings: The prepared samples were characterized using Fourier Transform Infrared Spectroscopy, Scanning Electron Microscope, Optical Microscopy, Viscometer etc. Contour plot was interpreted to understand the effect of graphene addition towards the normalized height and viscosity of the fluid.