COMPARATIVE ANALYSIS OF THE USE OF A HYDRAULIC EXCAVATOR AND A MECHANICALLY DRIVEN EXCAVATOR IN DEEP QUARRIES

ABSTRACT

The main problem in deep quarries is the increase in the cost of mining operations. This article discusses the possibilities of using a hydraulic excavator to solve this problem. A comparative analysis of the efficiency of hydraulic excavators with mechanical excavators of the ECG type has been carried out, which allows an objective assessment of their potential in deep quarries. The article examines the positive and negative aspects of using a hydraulic excavator, including its performance, economic efficiency, as well as the impact on the environment and the safety of work processes. The identified advantages include high maneuverability, greater accuracy in the execution of work and reduced operating costs, while the disadvantages relate to the high cost of equipment and maintenance. Conclusions are drawn about the expediency of using hydraulic excavators, depending on the specifics of mining operations and the depth of the quarry.

АННОТАЦИЯ

Основной проблемой в глубоких карьерах является увеличение стоимости горных работ. В этой статье рассматриваются возможности использования гидравлического экскаватора для решения этой проблемы. Проведен сравнительный анализ эффективности гидравлических экскаваторов и экскаватора с механическим приводом типа ЭКГ, что позволяет объективно оценить их потенциал в глубоких карьерах. В статье рассматриваются положительные и отрицательные аспекты использования гидравлического экскаватора, включая его производительность, экономическую эффективность, а также воздействие на окружающую среду и безопасность рабочих процессов. К выявленным преимуществам относятся высокая маневренность, большая точность при выполнении работ и снижение эксплуатационных расходов, в то время как недостатки связаны с высокой стоимостью оборудования и технического обслуживания. Сделаны выводы о целесообразности использования гидравлических экскаваторов в зависимости от специфики горных работ и глубины карьера.

Keywords: deep quarry, productivity, width of the work site, hydraulic excavator, ledge, speed of movement of the excavator.

Ключевые слова: глубокий карьер, производительность, ширина рабочей площадки, гидравлический экскаватор, уступ, скорость перемещения экскаватора.

Introduction

Modern quarries are characterized by a significant increase in the depth of mining operations and the height of the working area. The average depth of deep quarries has already exceeded 500 m. The height of the working area of large deep quarries is 120-150 m on average for ore. overburden - 170-200 m.

With an increase in the depth of mining operations, the physical and mechanical properties of rocks change, the front of mining operations decreases, the width of work sites decreases, and the provision of excavators with vehicles becomes more complicated, which creates additional difficulties for the organization of the workflow.

In addition, high-tech equipment is emerging, the use of which in one way or another changes the parameters of the working area of the quarry. For example, the use of a hydraulic excavator allows you to reduce the width of the working area of the ledge. At the same time, the stability of the ledge on which the excavator is located requires a complete stability analysis [1].

It is particularly necessary to emphasize the continuing decline in the quality of minerals in the fields being developed and most of the newly put into operation, the significant complication of mining, geological, climatic and economic and geographical conditions for the development of deposits, especially new ones, with increasing requirements for environmental protection, which leads to a steady trend of significant growth in operational and capital expenditures costs in the mining industry. [2]

Thus, two problems are relevant for deep quarries: the choice of rational models of excavators when replenishing the fleet instead of retired ones and reducing the cost of mining operations.

The research method

The performance of excavator-dump complexes is one of the main factors that make it possible to assess the effectiveness of mining operations. It is well known that the main factors affecting the performance of an excavator include the following: the difficulty of mining the rock mass, which is assessed by the category of rock and its condition; technical data, condition and reliability of the excavator; the qualification of the driver; the quality of the face, the conditions of approach of transport to the loading site, illumination.

But their organization has no less influence on the efficiency of the work, which depends on the parameters of the ledge, the sequence of blocks working on the ledge, types of work and processes, the number of dump trucks, road conditions, timely supply of fuel, energy, spare parts, etc. [3]

We will conduct a comparative analysis of ECG 15 and Cat 6040 in the conditions of the Kalmakyr quarry

Determination of the working site during rock mining using ECG-15 [4]

where, T – the width of the transport lane m;

C – the distance from the lower edge of the camber to the transport lane C = 2.0-3.0 m;

B – camber width;

S – the width of the safety lane S=1.5-2.0 m;

Z – the width of the prism of a possible collapse (we assume Z=3.5 m);

 The width of the carriageway of a permanent highway in two-lane traffic is determined by the expression:

where, a – the width of the dump truck, m;

y – the distance from the wheel to the end of the roadway (y = 0.5 m);

x – the gap between the bodies of oncoming cars:

where, V – the speed of cars, km/h V = 20 km/h;

Camber width:

Where,  – is the radius of unloading of the excavator

 = (0,8-0,9) *    m

 – the radius of scooping at the excavator's standing level

Technical performance of ECG-15 (by loosened mass) it is determined by the formula:

where E – the bucket capacity, m³

К_f – bucket filling ratio (К_f=0,6);

К_u – excavator utilization rate (К_u =0,8);

t_c – cycle time, (t_c =28), сек;

К_l – the coefficient of loosening of rocks in the bucket (К_l =1,2);

The results of calculations of the parameters of the ECG 15 work site are translated in Table 1.

Table 1

Parameters of the working area for ECG 15

Figure 1. ECG working area 15

Using the same methodology, we calculate the working area for the development of rocks using Cat 6040

Figure 2. Cat 6040 Hydraulic Excavator

Table 2

Parameters of the working area for Cat 6040

As a result of the reduction of the working area, the volume of overburden in each block decreases and the general angle of the side of the Kalmakyr quarry increases.

S= 74,26 м² L= 300 m

The maximum movement speed of the UGE-300 is 2.7 km/h

The maximum travel speed of the CAT 6040 is 2.7 km/h

The maximum movement speed of the EKG-15 is 0.75 km/h

The maximum movement speed of the ECG-10 is 0.7 km/h

It will take more than 55 minutes to move the ECG to a safe distance of 150 m and deliver it to the site. And EG takes 25 minutes, according to the above indicators, we can increase ore productivity by 630 m3

The main factors characteristic of the operation of quarry hydraulic excavators are:

- high annual working time (7000 hours);

- high forces and dynamics (up to 70 kN per 1 m3 bucket capacity) in the mode of digging working equipment in the bottom;

- high specific power (up to 3.7 kW/t per 1 ton of working weight);

- distance from external infrastructures for the repair of hydraulic components.

Remoteness from service infrastructures makes it more difficult to overcome these factors and makes it necessary to organize services on site.

In addition, there are a number of additional factors that reduce the reliability of the hydraulic drive on quarry excavators in mining enterprises:

- high level of air pollution in the work area (up to 1.2 g/l);

- extremely low or high ambient temperatures, which determines significant changes in the viscosity of the hydrofluid: 10-15 times during operation, and 250 times during startup;

- high loads that occur during the excavation of very hard or poorly blasted rocks, which determines the need for artificial pressure limitation in the system to increase the service life of hydraulic components;

- an insufficiently high level of maintenance due to the low qualification of the service personnel, as well as due to insufficient technical equipment with measuring instruments and special tools. [5]

Studies have shown that the main causes of hydraulic excavator failures are contamination of the hydraulic fluid and the start of the hydraulic system of excavators at extremely low temperatures.

In [6] it was noted that with an increase in the depth of the quarry, the purification of the atmosphere from pollution becomes more complicated. From the experience of operating at the Kalmakyr quarry, where the depth is already above 500 m. pollution is below 300 m. they will be critical for a hydraulic excavator.

Conclusion and results

After conducting a comparative analysis of ECG 15 and Cat 6040, positive and negative aspects were established.

Of course, the use of a hydraulic excavator is more rational than a mechanically driven excavator. By reducing the working area due to the more compact dimensions of the hydraulic excavator, theoretically an increase in the general side to 1 degree is achieved, which reduces the number of stripping operations. In addition, greater productivity allows you to increase the productivity of the career as a whole.

However, the use of a hydraulic excavator in deep quarries has its negative aspects:

- High maintenance cost.

- Rapid failure of the hydraulic drive due to contamination.

- High cost of hydraulic excavator spare parts.

Based on the above aspects, the use of hydraulic excavators in deep quarries below 200-250 m. it is not rational.

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