Vol 36 Iss. 1

In 1957, the Institute lost an outstanding teacher and researcher, a major specialist in the development of ore deposits, associate professor, candidate of technical sciences Nikolai N. Polyakov.

In 1957, Alexander M. Alamsky, a prominent specialist in the field of mining, an indefatigable researcher and a talented teacher, associate professor of the Drilling and Blasting Department of the Leningrad Mining Institute, candidate of technical sciences, passed away. He was born in 1900 in the town of Atkarsk, Saratov province. He was educated in a real school, Saratov University (two courses), Saratov Polytechnic Institute and, finally, in 1928 Alexander Mikhailovich graduated from the Leningrad Mining Institute, specializing in the development of ore deposits.

Rock fracturing is a general property of a rock massif characterized by ubiquitous distribution and irregularity of development, as well as a pronounced average orientation of fracture systems within geological structures. The intensity of fracturing is determined, as observations show, by the composition of rocks and conditions of their occurrence. The aggregate of fracturing of individual layers, strata and stratigraphic horizons gives the fracturing of the rock massif. Being an important structural element of the rock massif, rock fracturing, especially in the conditions of folded coal deposits, is a constantly acting factor on the development conditions.

Modern systems of development of thin and medium thickness steeply falling coal seams, despite continuous improvement, have major drawbacks. They do not guarantee complete safety of labor, do not achieve the flow of coal excavation, labor productivity continues to be insufficient. This is due to the fact that when working along the strike and the applied methods of roof management require significant exposures of the host rocks, and therefore, create conditions leading to face blockages and high labor intensity of the main production processes.

One of the most important places in the complex of production processes of coal mining are occupied by roofing and roof management in longwall faces. The works on fixing and roof management are associated with high labor and timber costs. The main means of reducing the cost of fixing and roof management is the wide introduction of mechanized fasteners and metal organ walls. As industrial tests have shown, the best technical and economic indicators are obtained with organ walls OK and OKU-150. This kind of casing was the most widespread. As of July 1956, 182 faces in the Ukrainian Donbass and about 50 faces in the Rostovugol Combine were secured with the OK and OKU-150 organ walls. By the end of 1957 it is planned to introduce this fastener in 600 faces in a number of basins of the Soviet Union.

At the end of 1955, the Leningrad Mining Institute was involved in the work of the Unipromed Institute to improve the development systems at copper mines in the Urals. The proposed article deals with one of the issues studied by the Institute. The work was carried out by Associate Professor N. N. Polyakov. N. N. Polyakov, Associate Professor E. Y. Makhno and the author of the article under the guidance of Prof. P. I. Gorodetsky. The design of the mobile support and flexible slab was developed jointly by Associate Professor E. Y. Makhno and the author, all laboratory experiments, observations at the mines and calculations were performed by the author of the article.

Layer caving is in many cases the only acceptable mining system, so the issues of improving its efficiency are of great practical importance for the ore industry. However, this system is characterized by low productivity of the faces and high labor intensity of works, in particular, fixing of cleaning faces. Therefore, it is very tempting and promising to study the possibility of layer mining with the use of only one flexible slab. In this case, the working space of the face will be between the sagging part of the flexible slab ab and the face wall av. Successful solution of the problem would make it possible to work the layers in a very simple and cheap way and thus significantly increase the efficiency of the layer caving system.

The economic significance of qualitative and quantitative mineral losses during mining is well known, and therefore the importance of their regulation is obvious. Although mineral losses and dilution during mining are inevitable, their size can be different, and the possibility (and the degree of technical complexity) of reduction depends, on the one hand, on natural conditions, and on the other hand - on the development system, the quality of mining operations and the quality of their control and accounting.

The increase in coal production by open-pit mining envisaged by the Five-Year Plan (122 million tonnes in 1960 against 66 million tonnes in 1955) by rates far exceeds the general growth of coal production in the Soviet Union, and especially from underground work: open-pit coal production increases by 88%, total production by 52%, underground production by about 40%. Such increased rate of development of open-pit works is connected with their well-known advantages, consisting, besides increase of labor productivity and reduction of production costs, in considerable improvement of labor conditions, increase of safety of works and sharp reduction of losses in the subsoil, especially at development of powerful steeply falling seams and veins. Injuries at coal pits are about five times less than in underground mines (reduction of severe and fatal cases is even greater).

Establishing the cost of repair of drifts in mining engineering literature has always been and is paid much attention, as the maintenance of drifts is one of the main items of expenditure of coal mines both in terms of cost and labor intensity. Some establish a mathematical dependence of the cost of repair of drifts, passed (or extinguished) in parallel to the cleaning works, as a function of their length, and others - as a function of conditions, maintenance: the cross-section of the excavation, the characteristic of rocks, proximity-cleaning works, etc. Some of them establish a mathematical dependence of the cost of repair of drifts, passed (or extinguished) in parallel to the cleaning works, as a function of their length.

The importance of preparatory workings in increasing labor productivity in the coal industry is great. Being ahead of cleaning works, preparatory workings create coal reserves, ready for excavation, than provide normal and uninterrupted operation of the field, rational use of mechanisms and high labor productivity in cleaning works.

In order to provide cleaning and preparation faces with sufficient amount of air it is necessary to correctly determine air losses both at operating mines and at their design. In many mines of Donbass, as well as in other coal basins of the country, a significant specific weight (often reaching 50-70%) in the general mine underground leakages falls on air losses in parallel workings.

At present, there is an urgent need to create roadheaders for mining in medium and strong rocks. One of the possible solutions to this issue is the creation of a combine harvester that destroys rock by percussive method. Development of the design of the working body of such a machine is complicated by the insufficient study of rock destruction under impact load application and the lack of parameters necessary for design. For this reason there are still no satisfactory designs of impact mining machines, despite the fact that the first inventions in this field appeared more than a hundred years ago (for example, Penrice tunneling machine in 1856).

Further realization of grandiose tasks of peaceful development of the USSR national economy requires even wider use of explosives energy in the development of mineral deposits in the field of industrial, railway and hydraulic engineering construction and in other sectors of the economy. Meanwhile, the issue of determining the size of explosive charges is still not developed sufficiently, and existing methods of calculation often give incorrect results.

Of all the currently known methods of mine shafts only the drilling method mechanizes all the main links of the tunneling cycle and allows automation of production.Drilling method, as well as other special methods of excavation, is applicable in difficult gropogeological conditions (for example, large inflows of water into the excavation). However, in comparison with the methods of freezing and cementation, it has a number of advantages. By this method, rock destruction, its removal and temporary fixing are carried out in parallel and with the help of mechanisms controlled from the ground surface, i.e. the most labor-intensive and dangerous profession of a sinker of vertical excavations is eliminated.

Cleaning the bottom hole from the drilled rock and bringing it to the surface when drilling shafts and boreholes is one of the main functions performed by the flushing fluid. In the process of drilling the flushing fluid is contaminated with drilled rock and its percentage in the fluid increases. The high content of drilled rock in the flushing fluid deteriorates its quality, causes collapse of the borehole walls (due to deterioration of claying of its walls) and poses a risk of seizing the drilling tool during the termination of flushing. Besides, the increase in the percentage of rock content in the flushing solution requires more energy for flushing, increases the wear of drilling equipment parts, and significantly reduces the drilling speed.

In 1955, the VNIMI team, in the work of which the author was directly involved, surveyed 70 of the most disturbed mine shafts in Donbass. For the remaining shafts, questionnaires on the condition of the shafts were collected with the corresponding graphic materials attached. The survey covered almost all natural conditions in which there are mine shafts of Donbass with the depth of more than 300 m.

In the practice of mine shaft reinforcement design up to the present time the calculation of reinforcement elements is made according to the norms based on the “Prussian rules for lifting and lowering people” from 6/IV 1925, Thus, in 1934 S. L. Lazovsky drew attention to the fact that due to the elasticity of conductors the load is distributed unevenly between the shoots and gave a solution to the problem of load distribution between the shoots taking into account the elasticity of conductors.

Core drilling has found wide application in geological exploration and mining industry. The park of core drilling machines is replenished with new brands. There are units for drilling in the most different geological conditions and the most different depths of wells (from 50—100 to 1000—1500 m and higher). However, despite the large volume of drilling operations and their long application, very little attention has been paid to the issues of drilling rigs drive. The proposed paper addresses part of the general issue of power required to drive the well drilling process.

The present work is based on the timing materials carried out by the staff of the All-Union Research Institute of Methods and Techniques of Exploration (VITRa) in the Karaganda coal basin and the Kustanay iron ore deposit. The structure of the deposit of the Dolinsk section of the Karaganda basin involves Quaternary, Tertiary and Paleozoic sediments. Quaternary sediments are represented by modern continental facies - mainly alluvium, deluvium and proluvium. The upper part of the Quaternary sediments consists of sandy loam, loam and multigrained sands with inclusion of pebbles. The thickness of sediments is from 7 to 15 l.

So far, the main means of drilling holes for blasting operations at open-pit mines are percussion rods. At mines and quarries work more than 1500 machines, the total volume of drilling by which exceeds 3 mln. pog. m of wells per year. Increase of productivity of machines and improvement of drilling works in recent years has been paid much attention, but drilling productivity grows still very slowly. At mines with a good organization of drilling operations, where machine downtime is minimized, drilling productivity in recent years has not practically increased, i.e. the reserves of productivity increase due to organizational measures have been used to a large extent. For further increase of productivity it is necessary to modernize the machines.

The solution of the problem of transportation of large volumes of rock mass at open-pit mining operations depends to a great extent on increasing productivity and cheapening the operation of rail transport. An important role should be given to the improvement of wagon designs, which account for 65% of metal consumption and up to 40% of maintenance, repair and depreciation costs in relation to the total costs of rolling stock.As the analysis of transportation equipment operation at open pits shows, the current situation with the equipment of open-pit mining operations with dumpcars cannot be considered satisfactory: a) the nomenclature of manufactured dumpcars is small; b) the strength of the main components of the wagon in general and especially when used for loading of excavators is low. Therefore, it is necessary to design and manufacture new types of dumpcars for open-pit mining operations.