Grinding

Abrasive wear is an important component in failure analyses in mining equipment. This work relates to a wear test for mill components after the occurrence of a failure in an iron ore pelletizing plant at Vale’s Tubarao Complex, Vitoria, Brazil. The equipment involved is a ball mill, which is used to grind the pellet feed into extremely fine powder for use in pelletizing process. Metallurgical components of this mill, such as screws, shell and mill head, are analyzed in a milling system simulation using iron ore slurry in order to correlate the components loss weight with running time. The analysis results and the tribology involved in this iron ore grinding process are presented in this paper. Finally, the value of the inspection process is evidenced as a key factor at the prevention of failures, at the prediction of the life cycle of the mill's components and at the reliability of the production assets.
Keywords: :Abrasive Wear; Iron Ore; Pelletizing; Grinding.

Vertical stirred mills are being widely used for the regrinding application. Although it is being used since late 1979, some aspects of its operation are still challenging. In this context, stands out the screw liner wear. Such the screw is in direct contact with grinding media and slurry, there is an intensive wear in this area. Carefully evaluation of screw liner conditions can lead to an increase in reliability and to an effective maintenance plan, also reducing operational costs. Based on this, the aim of this paper is to present an innovative and practical method for precise monitoring of liner wear. The method is based on electrical measurements, vibration signature and spectral analysis. It is simple, low intrusiveness and low cost. Experimental results were obtained at Minas-Rio Project, an Anglo American plant, located in Brazil. The results indicate a great potential to provide an accurate measurement of screw liner wear conditions.

Research results on 3D modeling of the diamond grain and its bearing layer when sintering diamond grinding wheels are provided in this paper. The influence of the main characteristics of the wheel materials and the wheel production process, namely the quantity of metallic phase within diamond grain, coefficient of thermal expansion of the metallic phase, the modulus of elasticity of bond material and sintering temperature, on the internal stresses arising in grains is investigated. The results indicate that the stresses in the grains are higher in the areas around the metallic phase. Additionally, sintering temperature has the greatest impact on the stresses of

Energy efficiency is extremely important in secondary grinding (regrinding) as specific consumption are greater than obtained in primary grinding. Moreover, finer grinding sizes are a trend in new grinding circuits therefore increasing the energy consumption, as well as respective capital and operating costs. In Brazil regrinding sizes between 40 a 20 m are common in greenfield projects. As horizontal ball mills show decreasing efficiency as grinding sizes are finer than 50 m, this work shows regrinding equipment alternatives to ball mills focusing on vertical mills. A number of survey campaigns were carried out on four industrial operations in which vertical mills were installed in the respective regrind circuit. A new batch test was developed and
validated to predict the energy consumption and product size distribution associated to vertical mills.

Life is Strange, INSIDE, Oxenfree—all these video games represent a seemingly entirely new genre. Young Adult videogames diverge from the male, gloomy grown-up stereotypes and replace them with adolescent protagonists in their coming of age stories. Their commercial success seem to validate their endeavors. However, YA narratives are hidden in plain sights for many years within JRPGs. Shin Megami Tensei – Persona 4 (short Persona 4 or P4) is a cultural ambassador. This paper examines how the game’s procedural rhetoric in combination with its Young Adult story advocate in favor of specific Japanese values. The time structure of P4 reinforces a longterm orientation and requires strategic planning as well as tactical flexibility. So-called “Social Links” represents Japan unique take on collectivism. Each link encapsulates a small YA narrative and offers different benefits to social-active protagonist. Finally, grinding mechanics reflect the notion of
repetition-based learning. Japanese schools teach through engaging with developing several solutions to a singular problem. The same holds true for the grinding process. All these elements combined create a game rhetoric promoting these aspects of Japanese culture.

Die Zementmahlung ist in besonderem Maße für die Qualität des Zements und für den Energieverbrauch gesamter Zementwerke verantwortlich. Die Zementmahlung muss eine bestimmte Materialfeinheit erreichen, nach der die Mühle jedoch nicht geregelt und betrieben werden kann, da diese aufwändig im Labor gemessen werden muss. In dieser Arbeit wird ein Softsensor entwickelt, der auf Basis von Prozessdaten wie Aufgabematerialmassenstrom, Sichterdrehzahl und Materialtemperatur die Feinheit vorhersagt. Für den Softsensor werden u.a. Ridge Regression, Support Vector Regression und Neuronale Netze mit Trainingsdaten aus halbjährigem Anlagenbetrieb trainiert. Der Support Vector Regression Softsensor erreicht einen mittleren Prognosefehler von 0,332μm bzw. 1,67%. Es wurde ein einfach bedienbares Exceltool implementiert, mit dem der Softsensor im Anlagenbetrieb eingesetzt werden kann.

Comparison between anticipated and measured mean residence time (MRT) along with analysis of the shape of residence time distribution (RTD) curves provides the most useful and valid information about mixing properties within a ball mill operating at industrial scale. In this work, the RTD measurements were carried out for a primary ball mill in closed circuit with hydrocyclones at two feed rates (i.e., 280 and 230 tons per hour (t/h)) by means of tracer technique. Also, perfect mixer, N-Mixer, and Weller models were studied to describe the RTD curves. It was found that the mixing condition inside the ball mill was very far from the perfect mixing circumstance. While, N-perfect mixer in series (N-Mixer model) showed better results compared to the large and small tanks in series (Weller model). According to the obtained results of the N-Mixer RTD model, when the ball mill throughput was enhanced from 230 t/h to 280 t/h, the MRT was decreased from 9.92 to 7.39 min, respectively. Moreover, relative variance of N-Mixer model diminished approximately 18% and particle cumulative passing from 75 μm of ball mill discharge increased 9%. Finally, it was concluded that operating in over-filled condition and poor mixing circumstance of slurry were the main reasons of low grinding efficiency.

Special Purpose machine are designed to perform some specific applications which cannot be carried out using conventional machines. Conceptualization of the system design understanding the need of the system with a collaborative approach and develop the machine. Existing now pipe notching is done on manual hand grinder where people stick Notch profile print from CATIA file on pipe and manually grind it to perfect shape on hand grinder and then the joint is done with the help of welding process. The main focus of project is to study different parameter of SPM and solving the problem related to production rate and design machine to overcome odds of the conventional process. The different software's such as ANSYS, CATIA etc. will be used for analysis and designing purpose. To study about various parameters such as the Material selection for the machine, parts required for manufacturing of machine, Machine feasibility for manufacturing depending on final cost of machine & various design parameter of the SPM. Main aim of the project is to improve accuracy and production rate of the pipe notch.

The Bond work index, W i , is defined in a Bond ball mill on the samples of standard size −3.327 + 0 mm. In practice, it is possible to find materials of non-standard size that are finer than 3.327 mm. In this work, a procedure for the calculation of the Bond work index is suggested for cases when the Bond grindability test is conducted on samples of non-standard size.

The study is focussed on a (then) innovative intercultural and interdisciplinary comparison between sword-culture in Europe and Japan. It contains the first published  results of a direct comparison between blade surfaces on medieval Japanese and Merovingian Period European sword-blades polished in the traditional Japanese manner. In this context the crucial role of surface-technology by grinding and polishing for functional sword-blades is highlighted in detail for the first time. There is an English and a Japanese summary contained.

Plant species, age, plant part and the time of sampling can affect the values of mineral nutrients present in a given sample. Besides this, the option used for the digestion of plant sample is also very important. So, for taking up the analysis of mineral nutrients in plant samples and getting the accurate and realistic results, proper and careful sampling and selection of digestion method are some of the very important considerations. Most of the essential elements are not equally distributed in the plant or within the plant parts. Although, it is possible to assay any plant part or even the whole plant but the biological significance of such an analysis always depends on the availability of interpretative data from the plant part(s) collected and used for the analysis. While conducting a plant analysis, primary objective should be to obtain the plant part for which assay results in actual comparison of plant samples coming from different types or stress treatments. Prior to elemental analysis, possible errors can occur at various stages such as; sample collection, initial handling, transportation, decontamination, drying, particle size reduction etc. Thus, possible sources of error must be known to the investigator for the accuracy of the whole procedure and the analysis. The sampling procedures and precautions required at various stages of sample preparation for the analysis of mineral nutrients are described here in this article.

Özet Madencilik sektöründe, yüksek tenörlü cevher yataklarının tükenmesi ile birlikte tane serbestleşme boyutu çok küçük olan ve çok düşük tenörlü maden yataklarının işletilmesi artık bir zorunluluk haline gelmiştir. Bu cevherlerin zenginleştirilmesi aşamasında ise gerekli olan enerjinin büyük bir kısmı öğütmeye harcanmaktadır. Mikronize öğütmelerde ise konvansiyonel (çubuklu ve bilyalı gibi) değirmenler verimini kaybetmekte ve ekonomik olmaktan çıkmaktadırlar. Bilindiği gibi, konvansiyonel değirmenlerde harcanan enerjinin büyük bir kısmı doğrudan boyut küçültmede kullanılmakta, önemli bir bölümü ise faydalı bir iş yapmadan (boyut küçültme) ısı ve ses olarak kaybedilmektedir. Ayrıca, 75 mikronun altındaki öğütmelerde konvansiyonel değirmenlerin verimi çok azalmakta (enerji tüketimi aşırı artmakta) ve öğütme ekonomik olmaktan çıkmaktadır. Bu çalışmada, kömür ve cevher hazırlama tesisleri için alternatif ince ve çok ince öğütme için kullanılan değirmenler tanıtılmış ve çalışma prensipleri ayrıntılı olarak anlatılmıştır.

The study explores the operation sequences of the production, processing and storage of cereal crops in inland Thrace during the second half of the first millennium BC. Using archaeological, archaeobotanical and ethnographic data, the research addresses questions regarding access and ownership of arable land, the intended purpose of agricultural produce as well as tradition and novelty in the agricultural methods and tools.

(versione IT in arrivo)    Sont d'abord présentés les principaux types de Moulins et de Meules, l'origine du Moulin rotatif et le phénomène de son expansion de l'Ebre vers le Rhin au cours de l'Age du Fer. On aborde ensuite le Gabarit des Meules, notamment les 2 standards principaux que sont le "petit Moulin" de 1 pied 1/4 et le "gros" de 1 pied 1/2. On définit ensuite la Hauteur Utile des meules (i.e. l'épaisseur de pierre consommable), l'Indice de Rectangularité du profil de la meule (IREC) qui permet d'apprécier son modèle à Neuf et son degré d'usure. On présente alors les Modèles des Meules de l'Antiquité (standard D = 2 H ou modèle aminci sur 3,5 H). Les 2 méthodes d'âgeage des meules (calcul de la Hauteur Utile restante ou appréciation par l'IREC) permettent de définir le degré d'usure d'une meule mais aussi d'établir le profil d'usure des meules d'un assemblage, certains sites montrant alors des meules neuves ou peu usées tandis que d'autres se caractérisent par des meules très voire archi-usées.
  Dans une avant-dernière partie sont présentées (sur la base du site laténien de Blois La Croupe -PEYNE 2019) des simulations visant à apprécier le degré d'Equipement en Meules des unités d'habitat, 6 scénarios plausibles ou probables étant retenus sur 33. Le taux d'équipement est supérieur ou égal à 1 moulin par habitat au LT-D. Une lecture égalitaire ou inégalitaire introduit la possibilité d'un Taux d'Equipement Meulier différencié socialement ou bien l'éventualité que certaines unités, concentrant plusieurs moulins, aient pu développer une activité productive spécialisée.
  On dresse pour finir un rapide bilan molinologique de l'Antiquité qui montre, en domaine rotatif, la part du lion revenant à l'Age du Fer (cultures ibérique et laténienne), l'inexistence del'Orient et les spécificités de la période Romaine (développement de la motion hydraulique, de l'anille, augmentation des gabarits sur la zone de 1,5 à 2,75 pieds d'envergure). Mais la période Romaine buttera toutefois sur "le pafond de verre" du gabarit de 3 pieds que seul saura franchir le Haut-Moyen Age grâce à l'abandon de la conicité si chère à l'Antiquité et à l'adoption du MoulinPlat, une invention laténienne de la zone Eure/Somme longtemps cantonnée par la culture des meules coniques méditerranéennes.

The present work initially studies the impact of a laboratory microwave
(MW)’s location (before and after a jaw crusher) on grindability of a copper
ore. Additionally, the role of MW’s radiation time (15–150 sec) and grinding
time (13, 15 and 17 min) on the produced particle size distribution (PSD),
mineral liberation degree (LD) and energy consumption are investigated.
relative work index (RWI), standard Bond work index (Wi), and grindability
index (GI) together with the breakage and selection functions were utilized
to assess the grinding efficiency and its kinetics of the untreated and MWpretreated (at a constant power of 0.9 kW) samples. Bond work indices were
obtained 13.70, 13.04 and 10.86 kWh/t for the untreated, MW-treated
uncrushed and MW-treated crushed samples, respectively. Besides, the
results confirmed that the microwave pretreatment was comparatively
effective at the shortest grinding time (13 min). Furthermore, locating the
microwave after the crushing stage indicated substantial improvements in
the sample’s grindability and its kinetics rate. The product size (P80) of the
MW-treated crushed sample (13 min, 0.9 kW, 150 sec) showed enhancements of 27% and 17% in comparison with the un-microwaved and MWtreated uncrushed samples. Finally, the comparative GIs acquired in the
entire spectrum of the particle range were reasonably higher if the microwave was located after the jaw crusher, particularly for the coarse fraction
sizes

At the regrind or secondary grinding stages of metal ores, usually the concern about the energy efficiency is extremely important. In general, the specific energy consumption at this stage is higher than in the primary stages of grinding. In addition, it has been observed a tendency of finer grinding in the new projects of metallic minerals, due to the finer mineral liberation, which leads to an increasing capital and operational costs. In Brazil, during the last 10 years, regrind sizes with a P80 of approximately 0,040 to 0,020 mm has been necessary in all new Iron and Copper plants. Conventional ball mills, adequate for primary grinding, usually results in low energy efficiency with products bellow 0,050 mm.
This paper presents and overview of the regrind circuits in Brazil that operates with Vertical Mills and the results of  industrial surveys at selected Vertical mill circuits, and compares these results with the design criteria and laboratory regrind tests used for the mill sizing.

This work reports aspect related to nano-sized particles of tetragonal anatase phase Titania. This approach is simple, faster, Eco-friendly, cost effective and suitable for large scale production. X-Ray Diffraction studies analyze particles size. It is found to be 74 nm and specific surface area is 19.16m2g-1. Morphology index (MI) derived from FWHM of XRD data explains the interrelationship of particle size and specific surface area. It is observed that MI has direct relationship with particle size and an inverse relationship with specific surface area. This work throws some light on and helps in the production line of Titania nano-particles.

This paper is a report of the last excavation campaign of the nuragic settlement of Brunku S’Omu, located in the territory of Villa Verde in central western Sardinia. The site, formed of a nuraghe and a large village of dry-stone huts, has been investigated several times during the period 1982 – 2004. In 2013, a new excavation campaign was carried out inside of the circular dry-stone structure named hut 16. The first results seem to suggest that such structure was used for both food preparation and metal-working activities. Pottery chrono-typological analysis dates the use of the structure to the Final Bronze Age, in accordance with the general dating of the settlement.

One of the most important machining process, drilling is done on two different samples-Aluminum and Mild Steel. Both of these aluminum and mild steel have totally different properties. Study of specimen preparation techniques and microstructure is done for both aluminum and mild steel. The purpose is to understand the difference in the properties of these two and various important points to be kept in mind while going for drilling of aluminum or any other soft metals or alloys.

The hard-turning process is steadily finding its place in modern manufacturing technology and with advance cutting tool materials it can be applied as alternative machining process to grinding providing a more economical way to finish hard surfaces. The main concerns of hard turning are tooling cost and the effect of process on machinability characteristics. The poor selection of process parameters may cause excessive tool wear and increased surface roughness. Hence there is a need to find the right parameters to achieve the right dimensional accuracy, good surface and maximum material removal rate. This paper reviews the effects of various process parameters such as cutting speed, depth of cut and feed rate on the response parameters such as surface roughness, material removal rate and chip reduction coefficient. Through this study main cutting parameters which affect the turning operation are discussed.

The present paper analyses the possible provenience, the morphological and technological aspects of the Roman
rotary querns’ lithic raw material discovered at the military site of Călugăreni / Mikháza located on the eastern
limes of Roman Dacia. Even though the querns provide only a glance on aspects of Roman everyday life, the
daily subsistence of the military and civilian population can be grasped through the process of grinding.

Technological development in Europe around the end of the Middle and beginning of the Upper Palaeolithic was expressed not only in the new methods for working flint, bone, antler, etc., but also by appearance of processing food and raw materials by grinding, crushing and abrasion. Ground plant resources can be dried and stored for longer periods and are more digestible when cooked and eaten, while crushed mineral substances can be used to create mixtures with new physical qualities. These are obvious observations to make, and findings of Palaeolithic grinding stones are known, but at the same time, we have a poor idea of the distribution of artefacts used for grinding. There is still no general understanding of where, from which periods, and in which forms they are found. This article reviews the corpus of Upper Palaeolithic grinding stones from the East European Plain, including 76 directly studied finds from 15 sites. Macroscopic and, where possible, microscopic traceological analysis has been used for their analysis. From this review we observe that grinding stone tools in the region under study include the following types: grinding slabs or lower grindstones (most often found as fragments from the late Middle Palaeolithic and later; in the Upper Palaeolithic they were used for grinding pigments, plant resources and for polishing stone); two types of grinders or upper grindstones (active tools) – elongated for repetitive, continuous movements and short for circular or irregular movements (used for grinding pigments and the working of plant resources; in the Late Upper Palaeolithic at Eastern Epigravettian sites trapezoidal grinders, similar to those from later periods, appear); pestles-grinders (found on sites related to the Eastern Gravettian); and finally, pestles (which appeared as specialised artefacts in the Late Upper Palaeolithic). Most sources refer to the sites of Gravettian circle and Epigravettian. One-third of them are securely associated with pigment and the remaining two-thirds have indications of use for grinding soft fibrous material. Based on these data, the study of paleo-economics and other aspects of the prehistory can be developed.

Grinding aids (GAs) have been an important advent in the comminution circuits. Over the last few decades, in order to address the high energy consumption and scarcity of potable water for mineral processing, chemical additives have become a promising alternative. Using GAs can have some advantages such as enhancing grinding efficiency, reducing water usage, improving material flowability, and narrowing the particle size distribution of the grinding products. A study on the effect of GAs on size reduction units is crucial for the beneficiation value chain of minerals and the impact on downstream processes. However, our understanding of the effects of these materials on the particle size reduction is quite limited. This article analyses the literature, which used GAs and provides a comprehensive review of their applications in the ore beneficiation processes. The outcomes of this investigation indicated that the current understanding on the mechanism of GA effects focuses only on their impacts on the product fineness and size distribution, and neglecting the aspect of energy expended and physicochemical environment. The application of GAs is mainly for rationalisation of energy where the type of reagent, pH, and ionic strength of the grinding environment is important. Gaps in knowledge of GAs are discussed in the context of addressing their use in the mineral industry, considering the mechanism of their effect, effect on grinding efficiency, and effect on the downstream processes. Addressing these gaps will pave the way for the application of GAs in improving size reduction efficiencies, which ultimately reduces environmental impacts.

In the present paper, the use of high performance grinding for the description of the twist topography on ground surfaces is investigated. More specifically, the periodic surface structure after finishing with peel grinding and quick-point grinding is considered. Theoretical investigations of the parameters of these grinding processes demonstrate that the twist pattern can be controlled. Furthermore, by considering single-grain material removal, shape and dimensions of the produced chip can be calculated. The single-grain model is also implemented in a CAD based model. The actual trajectory of the grinding grain is graphically represented on the workpiece surface. The chip produced by the grain in each rotation is removed from the surface, indicating the trend of the twist produced via various process parameters.

The oil press of the temenos, in Dharih, used between the 6th and the 9th cent. AD, is divided into two parts: in the southern part, with a clay floor, olives were crushed through a rotary movement of a stone roller into a round bassin; in the northern part, on a raised and paved floor, a lever system was used to put pressure on the olive paste acquired from olive crushed. This press does not have any refining device, unlike the other two oil presses belonging to the Nabataean and Roman eras discovered on the same site. The small size of the installation and the low capacity of the tanks suggest that the production of oil and residue production (lees-amurca and pomace) was low used for food, heating and lighting of the residents of the small community village installed during the Byzantine and Umayyad eras, in the last temenos of the ancient Nabataean and Roman sanctuary.

L’huilerie du temenos de Dharih, utilisée entre le VIe et le IXe s. apr. J.-C., est divisée en deux parties : dans la moitié sud en terre battue, le broyage des olives se faisait au moyen d’une meule circulaire dormante et d’un broyeur rayonnant ; dans la moitié nord surélevée et dallée, un système de levier exerçait une pression sur la pâte obtenue par le broyage et en extrayait l’huile. Cette huilerie, contrairement aux deux huileries d’époques nabatéenne et romaine découvertes sur le site, ne présente pas de dispositif de raffinage. Les petites dimensions de l’installation et la faible contenance des cuves laissent penser que la production de l’huile et des résidus de sa production (amurca et grignons) était modeste. Sans doute était-elle exclusivement destinée à nourrir, à chauffer et à éclairer les habitants de la petite agglomération villageoise installée à l’époque byzantine à l’intérieur du dernier temenos de l’ancien sanctuaire nabatéen et romain.

Grinding and polishing has always been the finishing process of all kinds of crafted goods. By burnishing, a surface becomes smoothed and an edge sharpened. Polishing gives an object a nicer look and only then the right finish. In certain cases good polishing can also prevent rapid corrosion, as can be observed on the surfaces of finds of Roman metal mirrors.
The grinding and polishing abrasives presented in this book were more-or-less easily available to prehistoric and antique man. If he really actually did work with them can only be proved without doubt in a few cases. This study demonstrates how efficient the different abrasives are and therefore how probable their use in ancient times was. Synthetically made polishing agents, such as corundum, were not yet in use, unlike some side products of early indus¬trial production like tile powder from burnt clay. I confine myself here to grinding and polishing agents which could be useful in the manufacturing of all metals known in an¬tiquity. Most of the abrasives could of course also be useful in the processing of stone (from marble to precious stones), bone, antler and wood, but our experiments and experience in the field and in the laboratory focussed on metals.
When thinking of “natural” grinding and polishing agents, mainly sandstone, quartz sand and maybe natural emery spring to mind. Old handbooks for craftsmen and workshop equipment – plus a very few sources of inform¬ation from antique authors – deal with many other substances which could either be used for sanding or for polishing. These I obtained from natural deposits and from collections, processed them for grinding or polishing and tested them on copper, bronze and brass in line with “Experimental Archaeology”. Originally the aim was to define differences in the microscopic traces which the various abrasives leave as characteristic marks on the small metal sheets, and so to obtain information as to the abrasives used on antique finds. This proved to be impossible mainly because the marks left behind by grinding are primarily affected by the particle size of the abrasives and not by the materials themselves.
Apart from grinding blocs and pulverized polishing agents, grinding and polishing tools such as files, scrapers and burnishers are also examined. Files and hones have already been dealt with in length in many specialist monographs and therefore do not need to be extensively discussed here. On the other hand, the frequently used scrapers, which played such a dominant role in antique metalworking, correspondingly merit a far more in depth examination.
In the archaeological context we rarely find evidence of sanding or polishing materials, because only in excep¬tional cases can they be identified and specified. The num¬berless hones are the exceptions. It cannot usually be determined whether they indicate ancient metalworking or whether they were used for working other raw material. This is only possible when hones are found within a specific metalworking context. However, evidence of traces of metals on brick disks from Augusta Raurica (figs. 46,1–3; 47) shows that by implementing systematic surface analysis on hones, metals also in use in metalworking may in the fu¬ture also be identified. Even with the help of modern analytics, grinding and polishing powders will still be hardly identifiable (examples figs. 102 and 107). Further archaeological research must produce well documented evidence to prove as to whether the abrasives tested and discussed here were all used in times of antiquity or not.
In this spirit, it is to be hoped that archaeologists will examine even the most vague traces of these unimposing raw materials of many craftsmen, because such evidence will help us to a better understanding of past production technologies and of the workflow leading to the finished object.
(Translation Julie Cordell)