Vol 63 Iss. 1

In the second half of the 18th century, the rapid development of iron and copper works, as well as gold and salt mining in Russia, created the necessary prerequisites for the organization of a domestic school to train mining and technical personnel, which was urgently needed by industry. The Mining Cadet Corps, now the Leningrad Mining Institute, established in St. Petersburg in 1773, became such a school - the oldest technical educational institution of our country. Over its 200-year history, the Mining Institute has educated a large army of talented scientists, production organizers, engineers, whose work contributed to progress in various branches of science and technology. A significant contribution was made by the Institute's students to the development and improvement of the open-pit mining method - a method that has always been of great importance, and in our time has become the most widespread in the mining industry of the country.

One of the most important decisions in the design of open pits is the choice of direction and intensity of movement of mining operations in the horizontal direction and in depth. These issues are usually solved when establishing the method of opening the open pit field and the calendar plan of mining operations. Implemented opening at the deposit for a long time, and sometimes forever, predetermines the order and efficiency of the open pit.

Periodically, dust and gas impurities accumulate in the atmosphere of the quarry space, the concentration of which in some cases is so high that the production process in the quarry stops for a long time and the company suffers huge losses. Significant expenses are needed to normalize the purity of the atmosphere at the moments of its stable conditions.

Uniform operation allows to eliminate equipment downtime, eliminate violations of technological discipline and eliminate unproductive costs associated with deviations from the normal course of production. Unevenness of the production process of ore extraction may not create negative consequences for other related technological processes, if this unevenness is foreseen. But disproportions arising in the technological process can not always be foreseen in advance by the plan, and to prevent them, appropriate reserves should be created (damping devices, accumulating capacity).

In the practice of designing mining enterprises, one often has to compare options with different intensity of construction and development of the design capacity of the open pit for ore. These variants may differ from each other in terms of construction time, duration of the period of development of the design capacity, the amount and time of investment, as well as the amount of commercial ore extracted in the period up to the design year. When comparing variants with different volumes of marketable products, projects usually do not comply with the requirement of identity of effect, i.e. comparability of variants in terms of volume and quality of ore. Approved in 1969 Model Methodology for determining the effectiveness of capital investment proceeds from compliance with this requirement, but does not indicate ways and means of its satisfaction.

Two methods of development of mineral deposits - underground and open (surface) - are constantly improving and competing with each other. Recently, there is a tendency to isolate the third method of development - underwater. Since the beginning of the 20th century, the most developed is the open pit method of development, and in the following decades, the area of its application will continuously expand. In this connection both theory and practice of open pit operations have been improved and the most complete and accurate classifications of those methods, which are created for surface development of deposits, are more and more urgently required. This article attempts to improve the classifications of stripping methods and development systems by utilizing all, in our opinion, the most valuable information given by other researchers, and some of the author's suggestions.

In the existing classifications there is a large number of categories of mineral reserves by preparedness (opened, prepared, ready for extraction, in clean-up, in pillars, flooded, etc.) and absolutely no division into categories by preparedness for excavation of waste rocks. To eliminate uncertainty in the interpretation of the role of reserves in the operation of the quarry and to justify the number and nomenclature of categories of reserves, let us consider the quarry as a system with all its interacting links. ...

Determination of quarry boundaries is one of the main tasks of designing the field development. Its solution is usually carried out in three stages. The boundary cutoff stripping ratio is calculated, then the method of delineation is selected, and, finally, according to the selected method, the quarry is outlined.

One of the well-known methods of determining the limiting stripping ratio in open pit mining is the method of comparing the allowable cost of the mineral, calculated taking into account all capital costs of mining and processing of raw materials and recoverable value, with the actual cost of ore extraction and removed overburden, taken by analogues. ...

Correctly chosen productivity of the open pit in terms of mineral resources has always been the key to stable and economical operation of the mining enterprise. And the more complex the geological structure of the deposit, the more difficult the task of determining the productivity. The Koashvinskoye apatite-nepheline deposit of the Apatit combine is one of the very complex ones. It is represented by four ore bodies with a configuration characterized in plan view and at depth by frequent bulges and pinch-outs.

Possible options for the development of mining operations in open pits are not sufficiently taken into account in planning, and sometimes good solutions for a given period do not contribute to success in the future. When opening the open pit field, it is necessary to focus not only on the rapid commissioning of the mine, but also on laying the cut trench in stable rocks, especially in deposits with complex engineering and geological conditions, i.e., when taking the final decision on the option, it is necessary, along with the indicators of the mode of stripping, the productivity of the mine, the development of mine transportation communications, to take into account also the factor of stability of slopes and sides.

Movements of mining operations in the development of the open pit are characterized by two directions: horizontal – as the working benches are worked out – and downward – in the process of deepening the open pit. Let us assume that the quarry has the form of a regular cone and we know the coordinates of points O₁, O₂, O₃, ..., Oₙ, determining the direction of deepening. ...

Under a circular quarry we will understand a quarry, the contour of which by the end of mining is close to an elliptical cone. The research will be carried out in the natural Cartesian coordinate system, i.e. the plane хоу is parallel to the plane of the horizon, axes ох and оу are parallel to the axes of the quarry. ...

The direction of deepening of the quarry is characterized by the path of movement in the quarry space, as the works are lowered, the place of the initial preparatory excavation at each of the horizons. The graph-analytical method proposed by A. I. Arsentiev and G. A. Sovetov was used to determine the rational direction of deepening. The minimum of the average overburden ratio since the beginning of development is taken as the criterion of optimality, at which the minimum of the present costs of construction and operation of the open pit is achieved. The purpose of the study is to verify the applicability of the methodology in determining the direction of deepening for quarries with complex geological and topographical conditions of development, as well as to identify the features of deepening of such quarries.

The use of mechanical shovels for preparation of new horizons in weak water-saturated rocks (sands, loams) with reduced bearing capacity is associated with great difficulties and requires good preliminary dewatering of the rocks. Practice of designing and construction of quarries has shown expediency and efficiency of application of advance drainage trenches. Digging is carried out by draglines in loose covering rocks, filtration properties of which provide drainage of rocks in trench sides on the width of excavator's run for the period of excavator's working out of its block. Thanks to this method at the open pits of Sokolovsko-Sarbaisky combine it was possible to reduce the construction time, as the stripping and dewatering works were carried out simultaneously.

The need to determine the width of working benches arises constantly in short‑term and long‑term planning, as well as in the process of open‑pit operation. …

Continuous improvement of technology and mechanization of open-pit mining operations has made it possible to develop mineral deposits represented by thin layers of complex structural structure. From the point of view of economic efficiency the most interesting is the selective development of the formation, which has a number of advantages over partially selective and gross excavation: preparatory works are developed independently of excavation and loading; losses of oil shale are minimal; qualitative averaging of organic mass in the face is achieved; excavation and loading machines and technological transport do not dwell on the movement of rock layers; there is no need for mechanical method of enrichment of oil shale; drilling-and-blasting method is replaced by mechanical ripping.

At many operating quarries non-metallic minerals are extracted only up to the level of groundwater, and large reserves of raw materials lying below the water-bearing horizon are considered off-balance sheet and are not developed. The depth of deposit development can be increased at the expense of watered reserves by using draglines, which provide excavation of blasted rock mass from under water from a great depth.

Analysis of the Kovdorsky open pit operation over the last 5 years has shown that the volume of the blasted block varied widely (from 30 to 130 thousand m³), with its average value for rock decreasing by 22.4 thousand m³ (from 55.6 to 33.2 thousand m³) and for ore by 28 thousand m³ (from 51.5 to 23.5 thousand m³). Carry over reserves of blasted rock mass also fluctuated significantly; its maximum reserve in 1967 1968 reached 780 800 thousand m³, and in 1969 amounted to 840 thousand m³, while the minimum reserve in 1965 was 270 thousand m³, and in 1967 and 1968 it was 520 and 500 thousand m³, respectively.

Thermal drilling of blast holes in granite quarries, despite certain advantages over mechanical methods, has not become widespread mainly because of a sharp decrease in drilling efficiency in fractured zones.

From the organization and state of drilling and blasting operations largely depends the management of blasted rock mass reserves and the rhythmicity of open pit operations. As reported data show, the cost of rock preparation for excavation at open pits in the Arctic is 1.5 2 times higher than at open pits in the central regions of the country with similar mining conditions. Improvement of technology and organization of drilling and blasting operations at Arctic open pits has made it possible to significantly increase the supply of blasted rock mass to excavators.

Climatic conditions have a serious impact on the productivity of open‑pit equipment and attempts have long been made to account for this influence by various correction coefficients.

In open pits where weak unstable rocks are mined, landslides are very common and result in reduced productivity of mining and transport equipment. …

The rhythmicity of work of open pits in the Arctic depends on numerous factors and, first of all, on severe climatic conditions, the influence of which leads to a decrease in the productivity of open pits and disruption of the rhythm of their work. To take into account the severity of the climate, correction coefficients are introduced to the production norms in different periods of the year. However, seasonal fluctuations have been insufficiently studied overall, although the patterns of seasonality are very important to take into account when planning and organizing production processes. On the other hand, at open pits in the Arctic it is very important to use favorable periods of the year for intensification of mining operations.

One of the common types of blending facilities is the blending stockpile. The qualitative composition of the ore stream arriving for processing varies randomly in time. Therefore, for the study of blending processes, in particular in blending stockpiles, the most promising is the apparatus of the theory of random functions, which allows us to directly take into account the internal relations of the processes of changing the qualitative composition of the blended mineral raw material flows. However, there are no methods in the specialized literature that allow calculating blending processes in stockpiles with the help of the theory of random functions. Usually, the efficiency of blending stockpiles is estimated by the ratio of variances (or standard deviations) of the controlled components of the qualitative composition at the input and output of the stockpile. In the present work, similar estimates are adopted. Without loss of generality, we consider random fluctuations X(t) of some component X of the qualitative composition.