TRENDS IN THE DEVELOPMENT AND APPLICATION OF HEAVY-DUTY DUMP TRUCKS FOR THE TRANSPORTATION OF ROCK MASS IN DEEP QUARRIES

ABSTRACT

In the world, when developing mineral deposits in an open-pit manner, heavy-duty dump trucks are increasingly being used, which have the ability to move on the lower horizons of a deep quarry, perform steep maneuvering operations in cramped conditions, on extreme and protracted slopes, significantly reducing the distance of transportation. Currently, special attention is being paid to the process of transporting rock mass using heavy-duty quarry dump trucks with their operational indicators, which provide a significant reduction in the cost of road transportation and increase labor productivity. When analyzing the conduct of open-pit mining, it was found that with an increase in the depth of quarries, the mining conditions for the development of deposits change: cramped conditions for mining, reducing the angles of repayment of the sides according to structural parameters, the parameters of the width of the transport berm, the guiding slope of the route change, which predetermines the use of road transport.

АННОТАЦИЯ

В мире при разработке месторождений полезных ископаемых открытым способом все более широкое использование находит применение большегрузных карьерных автосамосвалов, имеющих способность перемещаться на нижних горизонтах глубокого карьера, выполнять крутые маневровые операции в стесненных условиях, на предельных и затяжных уклонах, существенно сокращая расстояние транспортирования. В настоящее время уделяется особое внимание процессу транспортирования горной массы с использованием большегрузных карьерных автосамосвалов с их эксплуатационными показателями, обеспечивающих существенное снижение себестоимости автоперевозок и повышения производительности труда. При анализе ведения открытых горных работ установлено, что с увеличением глубины карьеров изменяются горнотехнические условия разработки месторождений: стеснённые условия ведения горных работ, уменьшения углов погашения бортов по конструктивным параметрам, изменяются параметры ширины транспортной бермы, руководящий уклон трассы, что предопределяет применения автомобильного транспорта.

Keywords: technological vehicles, quarry dump truck, rock, transportation, minerals, mining, deep quarry, operational indicators.

Ключевые слова: технологический автотранспорт, карьерный автосамосвал, горное порода, транспортировка, полезные ископаемые, добыча, глубокий карьер, эксплуатационные показатели. 

Introduction

In the world, when developing mineral deposits in an open-pit manner, heavy-duty dump trucks are increasingly being used, which have the ability to move on the lower horizons of a deep quarry, perform steep maneuvering operations in cramped conditions, on extreme and protracted slopes, significantly reducing the distance of transportation. Currently, special attention is being paid to the process of transporting rock mass using heavy-duty quarry dump trucks with their operational indicators, which provide a significant reduction in the cost of road transportation and increase labor productivity. The analysis of the extraction of minerals by the open method in the world shows that when developing quarries to a depth, the cost of transporting rock mass reaches over 60%. In this regard, the problems that inevitably arise during the operation of heavy-duty quarry dump trucks are one of the main ones. Automobile cargo flows in deep quarries are characterized by a high concentration of traffic, heterogeneity of the transported rock mass, instability of the main parameters.

Recently, the use of quarry dump trucks in the development of mineral deposits by the open method has become widespread. In many countries (Russia, USA, Canada, South America, etc.), its use, unlike other types of quarry transport, in the near future will be over 75%. For example, in Australia it is almost equal to 100% [1]. This circumstance is due to the fact that the largest modernization is taking place with the technical improvement of quarry dump trucks, determined mainly by natural and technological characteristics [4].

Research methods

These technical indicators of deep pits (Table 1) show that in most of the deep pits of various mining companies in the world, the peculiarity of the operating conditions of modern technological vehicles is determined by the ever-increasing depth of mining operations and in the future it will remain one of the main types of quarry transport. This trend leads to the predominant use of road transport (over 60%) as an assembly link, the concentration of road freight traffic in a working area with cramped spatial conditions. As the analysis of the complexity of the operating conditions shows, it is aggravated by a high concentration of mining equipment, a minimal front of excavation, cramped working and maneuvering platforms.

Table 1.

Technical parameters of deep pits of the largest ore deposits

Currently, in 63 countries, more than 16 thousand units of transport equipment are used at more than 760 mining enterprises for quarrying minerals. 12 thousand are heavy—duty dump trucks. The share of quarry vehicles in technological transportation of mining enterprises is 75%.  The world's leading manufacturers of dump trucks are Caterpillar (USA), Liebherr (Germany), Komatsu (Japan), Euclid-Hitachi (Japan), Terex-Unit Rig (UK), BELAZ Software (Republic of Belarus). A standard-sized range of modern quarry dump trucks is formed taking into account global trends in the formation of mechanization in open-pit mining and the mining equipment used. Relatively quarry dump trucks can be classified by load capacity into 6 main groups (Fig.1).

Figure 1. Distribution of heavy-duty dump trucks used in deep quarries of the world

The standard-sized range and its demand in the market of heavy-duty dump trucks are primarily characterized by the release of excavation and loading equipment. To date, more than 69 models of dump trucks with a rigid frame are produced in the world by 29 different manufacturers in classes of more than 30 tons and 33 models of dump trucks with a lifting capacity of 90-363 tons – by seven main manufacturers [2].

The main reason for the decrease in the productivity of quarry vehicles with an increase in the distance of transportation determines the need for periodic technical re-equipment of the motor transport link of the quarry with new brands of dump trucks.

For many quarries, the features of the dynamics of the main values of the productivity of quarry transport of quarry systems identified at that time are temporary and not permanent. The author analyzes the modern career transport, the ways of its development and improvement. At the same time, this paper does not consider the use of heavy-duty dump trucks in quarries with a depth of over 600 meters on long steep slopes. [3]

In order to maintain the planned transportation of the volume of rock mass, it becomes necessary to choose a quarry dump truck with a load capacity of more than 200 tons at the low horizons of a deep quarry. In [5], based on the analysis of heavy-duty dump trucks produced by the largest companies Caterpillar, Liebherr, Komatsu, Euclid-Hitachi, Terex-Unit Rig, BelAZ, several of the largest and largest dump trucks were identified. The paper indicates that one of the main parameters is the dump truck's load capacity, and the method of choosing the dump truck's load capacity is determined depending on the volume of the excavator bucket. However, this paper does not consider the issue of moving rock mass from the lower horizons of a deep quarry and does not substantiate the relationship between the performance indicators of heavy dump trucks.

When researching the use of heavy-duty dump trucks, a literary review of their use in deep quarries was carried out. Bingham Canyon is the largest quarry and mining point in the Western United States. A copper porphyry quarry is being developed at the deposit. The ore body has dimensions of 1200-1500 x 1800-2100 m. The reserves of the Bingham Canyon deposit amount to 637 million tons of ore with average copper. The parameters of the quarry are: depth 1200 meters, width 4000m with an area of 7.7 km². Transportation of rock mass is carried out using heavy-duty quarry dump trucks (64 units), which allows transporting 231 tons of rock mass in one flight [6].

Open-pit mining [7-10] at the deep quarries of Muruntau, Kalmakyr, where mining technology and equipment are being improved, dump trucks, a steep-slope conveyor, a complex of cyclic flow technology (CPT) and railway transport are used on deep horizons. The experience of using CPT in a deep Muruntau quarry has shown a reduction in the cost of transporting rock mass by an average of 15-20%, and an increase in labor productivity, while the amount of harmful impurities released into the atmosphere has noticeably decreased. The used steep-slope conveyor (CNC), which has been in operation since 2009, is part of the mining and transport complex TST-ore. It should be noted that with an increase in the depth of work, there is a noticeable deterioration in ore extraction indicators, accompanied by an increase in the stripping coefficient and the cost of moving the rock mass. Improvements in this case are possible by reducing the volume of stripping operations, improving the technology of open-pit mining, introducing newer models of heavy-duty dump trucks.

At the same time, the production capacity of quarries by rock mass, as a rule, increases. Compensation for such deterioration is achieved by reducing the volume of stripping operations, as well as improving the technology of field development, the acquisition of newer brands of heavy-duty dump trucks, which determines the main trends in the development of deep pits.

Results and conclusion. The depth of the Muruntau and Kalmakyr quarries has approached and today exceeds the corresponding mark of 600 and 550 m. [11]. On the lower ledges of the Kalmakir quarry, the rock mass is shipped by excavators to BelAZ-7530 dump trucks with a load capacity of 220 tons, followed by its delivery to transshipment points and shipment by excavators to railway transport. An increase in the volume of overburden will require an increase in unloading fronts, which will require the construction of additional railway dead ends. In addition, the reconstruction of the internal communications of the Kalmakir quarry will increase the volume of storage of waste rock in the automobile dump to 6 million tons. m³.

In the conditions of the deep Muruntau quarry, an increase in the efficiency of the transport system can be ensured by further improvement of the CPT scheme, in particular, the introduction of steep-slope conveyor transport and road transport. An increase in the efficiency of transport can be achieved with the use of specialized vehicles.

Due to the low reliability of the machines, the re-equipment of the technological fleet of dump trucks did not give the expected effect. The excess of the heat transfer of the engine over the power of the standard cooling system led to the fact that in the summer, when moving up with a load, the dump truck was forced to stop 2-3 times for cooling. Working in this mode disabled the engine in 6 thousand hours. In the current situation, the measures taken to improve the reliability of the machine as a whole did not give positive results, and the improvement of its individual components and systems was not of significant importance. The production program for the rock mass was not carried out by the quarry.

The transition to imported CAT-785B dump trucks with a lifting capacity of 136 tons from Caterpillar became inevitable in this situation. A significant factor determining the level of technical operation of dump trucks was the ability to monitor the condition of the units, quickly and accurately determine the malfunction. From this point of view, the CAT-785V dump truck has more advanced diagnostic capabilities, since it is equipped with three on-board computers for control, monitoring, registration and long-term storage of the parameters of its systems and units.

According to the test results, the dependences of the operational speed and the number of flights on the given transportation distance were established. Using these dependencies, the reference performance of dump trucks in various conditions was formed, which then served as the basis for determining their shift, monthly and annual productivity, taking into account emergency downtime and the adopted maintenance system.

The deterioration of the performance of road transport in deep quarries makes it necessary to find ways to intensify it, replace it with other more advanced or in combination with other types of career transport suitable for work in certain areas of the quarry.

In the future, with the development of the quarry in the V-th stage, additional movement in the amount of 102 million m³ of rock mass is planned. The intensive increase in the depth of the Muruntau quarry as it develops, including the transport route, determines the need to purchase new, more advanced models of heavy-duty dump trucks for their operation on the lower horizons in cramped conditions (Fig. 2).

Figure 2. Development of mining operations of the Muruntau quarry on the borders of the ivth stage

At the moment, the fleet of rolling stock of the Muruntau quarry Motor Transport Management is 114 units of heavy-duty dump trucks of the BelAZ, Caterpillar, Komatsu brands (Fig. 3).

Figure 3. Distribution of heavy-duty dump trucks in the conditions of the Muruntau quarry

In the near future, it is planned to purchase Komatsu dump trucks with a capacity of 220 tons. It is established that when using four-wheel drive dump trucks, it is possible to achieve higher indicators. The use of such dump trucks leads to an increase in specific energy consumption when lifting rock mass (by 15 -20%).

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