Influence of the main operational factors on the working capacity of a mining hydraulic excavator

The analysis of factors influencing the failures of a mining excavator is substantiated. The classification of factors and methods of dealing with them will have a great importance in mining engineering. The article considers an example of the influence of various factors on the lifting mechanism of a hydraulic mining excavator. Thanks to the early identification of the most influencing factors on a mining excavator, it will be possible to manage the equipment maintenance and repair under actual conditions and operating conditions.

Influence of power fluid temperature in hydraulics on operating efficiency of hydraulic mining excavators

The Republic of Vietnam has great mineral resources. Open pit mines use hydraulic excavators. In hot climate, the excavators lose capacity, and the number of the hydraulics failures grows. To identify the causes of unstable operation of the hydraulics, the authors analyze the capacity reduction factors, namely, hydraulic pump leaks. The test subject is pump HPV95 for Komatsu hydraulic excavators. The axial-piston pump leaks take place in clearances of control and injection gears, and only have mutable and cyclic behavior in the piston and cylinder clearances. This has an adverse effect on uniformity of the pump flow and on stability of the injection pressure. Generally, leaks can be evaluated from the Reynolds equation of fluid flow rate in the ring clearance. The input data are the design variables of axial-piston pump HPV95 and power fluid temperature range of Komatsu hydraulic mining excavators operated in open pit mining in the south in the Republic of Vietnam. Matlab-based Simulink modeling shows that with increasing temperature of power fluid, leaks in the injection gear grow nonlinearly in the absolute value and so does the surging amplitude in the pump flow. As a consequence, the pressure fluctuations and vibrations in the hydraulic gear elevate. The modeling also exhibits higher surge and reduced net capacity of the hydraulics with rising temperature of power fluid. These changes are caused by reduction in the flow friction in the ring channel between the piston and block of cylinders. Thus, the power fluid cooling system engineering subject to hydraulics capacity, operating conditions and cooling methods is highly critical for the efficient operation of hydraulic mining excavators.

THE RESEARCH OF "HYDROBANK-COOLER" SYSTEMS OF HYDRAULIC POWER UNITS OF HYDRAULIC MINING MACHINES

Today, powerful expensive equipment is used in mining enterprises. Downtime, breakdowns and repairs of hydraulic mining machines lead to large financial losses of mining enterprises. Mechanical particles, microdroplets of water and air bubbles that fall into hydraulic fluids during operation, significantly affect the properties of the working fluid. In this regard, maintaining the quality of the working fluid used in expensive hydraulic mining machines is one of the most important tasks of modern hydraulics.

Substantiation of rational relationships of main parameters of the rock washing-out process when applying GD-300 hydraulic monitors at Kuzbass open pits

The need to use hydraulic technology for washing out quaternary bedrock, as well as heterogeneous rocks previously piled in hydraulic-mine dumps located above commercial coal reserves, requires the use of modern high-performance equipment. As such equipment, it is advisable to use the new GD-300 hydraulic mining giants – monitors, which are designed, manufactured and tested at Kuzbass open pits. In order to increase the performance of hydraulic monitors at Kuzbass open pits, the following dependencies are determined in the article: changes in the amount of water flow through the hydraulic monitors on the nozzle diameter and the pressure in front of it; changes in the amount of solid rock washed out by the hydraulic monitor ‒ solid flow on the nozzle diameter at various values of the pressure in front of it; changes in the solid flow on the pressure in front of the nozzle.

Investigation of the influence of flooded bench hydraulic mining parameters on sludge pond formation in the pit residual space

The research aim is establishment of effective parameters for mining of flooded bench by a hydro-mechanized complex with dumping of enclosing rocks in a sludge pond of pit residual space. The established research results make it possible to choose the effective width of the dredger mining cut at the hydromechanical method, taking into account the volume of the excavation and dump pipeline movements. Two technological schemes for the formation of a sludge pond in the pit residual space are proposed, they differ in the direction of the sludge pond movement relatively to the pit front. The established dependence of the number of movements of the sludge pond pipeline on the width of the dump pass allows to choose its effective value, taking into account the number of discharge pipes. Based on the dependence of the average monthly excavation volume and the number of movements of sludge pond pipeline on the width of cut face, the optimal number of discharge pipes is established. The research results allow establishing the effective dredger width of the sludge pond and the number of discharge pipes provided that a transverse or longitudinal pass at the internal sludge pond formation is applied during the mining.

Consideration for declaring a Mineral Reserve for TSF mining projects

SYNOPSIS The mining of old tailings storage facilities (TSFs) or dams/dumps has become a common operation in South Africa. This practice has several interesting aspects that are different to normal surface mining operations. When considering the estimation of Mineral Reserves, the Competent Person must take into account the conditions of mining historical TSFs that are often situated in close proximity to communities. This paper discusses the Modifying Factors required to convert a Mineral Resource to a Mineral Reserve, such as mining sequence, dilution, mining losses, and environmental, social/community, and government factors. The paper also investigates the role that Inferred Mineral Resources may play in the life-of-mine plans for tailings dam projects. Keywords: TSF, tailings, hydraulic mining, Mineral Reserve estimation.

Modelling hydraulic mixture movement along the extraction chamber bottom in case of hydraulic washout of the tuff-stone

This paper presents the research results of the pulp movement process along the extraction chamber bottom to the suction pipe of the pulp lifting device in case of downhole hydraulic mining the volcanic tuff-stone. The washout process and hydraulically operated transportation of the tuff-stone hydraulic mixture, when forming the extraction chamber, have been studied under various conditions and methods of exposure. As a result, the dominant parameters have been determined influencing the hydrodynamic washout technology as well as tuff-stone hydraulic mixture lifting to the alluviation map. The dependences have been substantiated of the washout process performance and transportation capacity of the hydraulic mixture flow on the determined parameters. To calculate the process of pulp flow-over along the extraction chamber bottom to the intaking hydraulic elevator headwall, the systems of equations have been determined based on the modelling the movement of tuff-stone hydraulic mixture along the extraction chamber bottom during hydraulic washout. The dependences of the contact strength of the tuff-stone samples mined by downhole method on the time spent in water are presented, resulting in determination of the tuff-stone weakening coefficient and the degree of its saturation with water.