Improvement of the Occupational Safety by Radical Isolation of Pollution Sources during Underground Ore Mining

One of the ways to protect the health of the employees in the mining enterprises is the improvement of the mine atmosphere by strengthening safety measures in the underground mining of minerals, especially those that pose a particular hazard. The aim of the study is to develop a technology for the radical protection of the employees from specific pollution. To achieve this goal, a set of tasks is being solved, one of which is the use of technogenic waste as materials for the preparation of hardening filling mixtures. It is experimentally established that the process of increasing the strength of the tailings of various concentration plants is adequate, the structures of which can be used to control the geomechanics of the ore-bearing massif. Classification of the strengthening mixtures that allow to increase strength can occur when unloading from the crushing and grinding mills. Use of tailings for the manufacture of insulating massifs is possible after extracting the remaining metals from them, for example, using one of the leaching methods. Air pollution with specific substances during underground mining of ore deposits can be radically reduced by isolating workings with artificial insulating massifs. Possibility of using tailings for the manufacture of insulating artificial massifs is substantiated experimentally by comparing the capabilities of mills of various types. The issues of atmospheric air pollution during underground mining, mainly of ore deposits, are considered. Quantitative values of hazard for development systems are given. The results of experiments confirming the possibility of using tailings for the manufacture of concrete insulating artificial massifs are presented. Quantitative values are obtained related to the capabilities of mills for obtaining a product of the same size with different granulometric composition of the starting material when used in industry.

ACCURACY OF HOLE PROCESSING WITH A COMBINED TOOL

Cement, powder metallurgy and various large-sized equipment are used in the industry of building materials for grinding raw materials. During operation, such equipment is exposed to external influences, especially at the joints, which reduce the reliability of the units. This leads to the early replacement of wearing parts. Large components of grinding mills are connected by flanges. The flanges are fastened with bolts, some of which must be precision, since they take the load of the equipment and ensure the tightness of the connection. The holes for precision bolts, respectively, must be accurate and of high quality. A study of the processing of holes with a reamer is given. The cutting elements of the tool, in the form of multifaceted plates, are mechanically attached to the body, which makes it possible to quickly replace the plate in case of wear or breakage. Such an assembled combined cutting tool allows to perform countersinking and reaming in one operation and thereby reduce the processing time of one hole and, in general, all precision holes in the flanges of the mill being repaired. The dependence of the precision hole accuracy on the shape and spatial deviation from the cutting modes of processing when using a combined tool is derived. The dependence is established for processing using a portable device with a rising spindle, as the most used equipment for repairs. The presented dependence makes it possible to predict the accuracy of machining holes with a combined tool, taking into account the rigidity of the technological system and calculate the required reamer accuracy.

Manufacture features of grinding elements for coal mills made of high-tech wear-resistant chromium-nickel cast iron

New high-tech spheroidal graphite chromium-nickel cast iron with improved as-cast properties is developed. The technological advantages of the new alloy are shown in comparison with foreign cast iron of the type Nihard-4. High-quality castings of grinding elements made of new domestic wear -resistant cast iron are made in the conditions of Russian plants using the developed technology. Medium-speed coal grinding mills equipped with these grinding elements have successfully passed the operational test at domestic and foreign thermal power plants. The technical and economic advantages of the new technology in comparison with foreign ones are shown, which made it possible to guarantee the stable production of high-quality wear-resistant massive castings of complex c onfi guration using domestic materials under the conditions of Russian plan.

Grinding Mills in the Life of the Russian Peasantry of the Post-Reform Period

Grinding mills were a routine attribute of the economic life of the peasantry, being an indispensable stage in the process of making bread. Yet these structures are hardly ever specifically researched by historians and anthropologists. This paper examines the socio-economic role of mills in the life of peasants of the early 20th century in Karelia. The study is based on the analysis of archival statistical data from the agricultural census of 1916 as well as on ethnographical and toponymical materials, which allows for a comprehensive examination of the object. The study has identified the number of mills in Karelia at the beginning of the 20th century. It also analyses the conditions that contributed to the effectiveness of functioning of these peasant farm buildings. It has been found that the mill craft in Karelia was the second (after blacksmithing) small-scale peasant production in terms of its economic benefit. At the same time, this type of economic activity was not the main source of income in those farms where they existed. The miller remained primarily a peasant farmer, but the level of prosperity of his economy was higher than that of other peasants. The sources used for the research have also enabled to trace the negative effects of crises in agriculture in Karelia during World War I on the flour milling business. A special attention in the paper is devoted to the mythological worldview of peasants. The analysis of the corpus of Karelian- and Russian-language toponymic data has confirmed the important role of grinding mills in the setup of the region’s peasant economy.

Acoustic signals of rotating drums generated based on DEM simulations

Acoustic emission (AE) or vibration signal has been applied in detecting operations of grinding mills in many industries. This paper proposes an approach to generate AE signals based on the particle-wall impacts. Through a combination of multi-mode vibrations and the calibration of the key parameters, the model was able to reproduce experimental data. The AE model was then implemented into a discrete element method (DEM) modelling of particle flow in a rotating mill. The AE signals of the mill under different filling levels and rotation speeds were generated and analysed, mainly focusing on the frequency and magnitude of each vibration mode. The link between the AE signals and the particle-wall impact energy was explored.

COMPARISON OF PARTICLE SHAPES OF CONVENTIONALLY GROUND BARITE, CALCITE AND TALC MINERALS BY DYNAMIC IMAGING TECHNIQUE: A REVIEW

Shape of particles made by grinding is one of the important measures for determining the utilizations of industrial minerals namely barite, calcite, and talc particles, particularly at production (like coating pigments, paints, rubber and paper) and processing stages (beneficiation by flotation). Therefore, measurement of particle characteristics is a critical issue in the development and control of industrial mineral products in most of the industries for some demanding applications. Ball and rod mills are commonly used as conventional grinding mills to produce a controlled grind size for the flotation circuit in the beneficiation of industrial minerals. Dynamic Image Analysis (DIA) offers reproducible results of a huge number of particles for some industrial minerals namely, barite [1], calcite [2] and talc [3] particles, whose shapes are crucial for some industries utilized as fillers. Thus, this review is about the comparison of shape values in terms of circularity (C) and bounding rectangle aspect ratio (BRAR) determined by the real time DIA. It was found that the shape results of the previous studies for the same samples by SEM measurement [4] were in good agreement with DIA results. It was concluded that the more rounded particles were encountered in the rod milled products for calcite and barite minerals. On the other hand, the more elongated particles were found in the ball milled products for talc mineral. It was attributed to the material type since the same mills were used for all tests. Hence, DIA can be used as a useful tool, which is easy, fast and highly accurate to control the particle shape distributions whether the required powder is fit for use

Measurements of Vibration and Noise Level at Different Cement Companies

The aim of this article is to compare Vibration and Noise measurements caused by different types of Machines at cement factories with the standard evaluation criteria of Vibration ISO 2631 – 4 EVS – EN 5349 – 2 and Noise following the standard ISO 9612 – 2009. Two cement companies were chosen, the first is located at Baddish district, 30km west of Mosul city (Iraq), which is called Baddish general cement company, while the other is located south of Mosul, and is called Hammam Al-Alil general cement company. Three stations were chosen for each company (raw materials grinding mills, cement grinding mills, and exhaust fan stations) having different electrical motor capacities. Noise level meter and vibration level meter manufactured by B & K (DENEMARK) were used for measurement. The location of bearing was chosen for vibration measurement, while the location of the operator’s ears for noise measurement, where chosen. It was found that most of the readings in vibration levels were unacceptable according to the evaluation criterion of vibration magnitude and noise level higher than 85dBA due to rotating unbalance misalignment and faulty gear matching (ISO 1940/1, 1990).

Roman Gold from Tresminas (Portugal)

The reconstruction of Roman mining activities in a primary deposit during the 1st and 2nd centuries AD has been made possible thanks to the excellent preservation of ancient mining and the prerequisite accompanying industries in the territorium metallorum Tresminas / Jales. Decades of on-site research and careful documentation of the monuments and traces of mining have faciliated the understanding of the work processes presented in this volume: prospection, excavation and processing. Within this framework, prospecting not only served the discovery of deposits as reported by ancient sources, but it accompanied the miners’ daily work and was an essential element of the mining process. The mining itself has left traces that enable us to both follow and understand the progress of mining over time. The planning and execution that become visible as a result of this allow us to infer a central organisation. The fantastic extensive high galleries of Tresminas, whose dimensions and state of preservation still impress visitors and researchers today are a further example of this. Finds that were abandoned, never completed or destroyed in ancient times are particularly helpful in understanding the mining process. The complex processing of the gold-bearing ores has left behind in Tresminas around 1 000 stamp mills, countless rock-grinding mills and enormous ore washing structures. In addition, the water management system associated with mining and settlement is discussed. An important part of the industrial complex was also the local stone quarrying for the production of stamp mills, rock-grinding and grain mills. A summary of the historical context of the territorium metallorum Tresminas / Jales is presented in the introduction.