Seyed Hadi Hoseinie

Reliability analysis of drum shearer machine at mechanized longwall mines

Purpose – Longwall mining is a special mining method with high productivity and smooth operation and the drum shearer is known as the most important component in longwall mines due to its direct role in the coal cutting and production process. Therefore, its reliability is important in keeping the mine production at a desired level. Hence, reliability analysis is essential in identifying and removing existing problems of this machine in order to achieve a better production condition. This paper seeks to learn about the reliability of the shearer machine in order to locate critical subsystems. The improvement of the reliability of the critical subsystems, to enhance the optimum operation of the shearer machine, is the main objective of this research.Design/methodology/approach – A basic methodology was used in this paper for the reliability modeling of the shearer machine. First, failure and performance data from a two‐year period at the Tabas Coal Mine‐Iran was classified and sorted. The tests for validat...

Reliability analysis of the cable system of drum shearer using the power law process model

In this article, the reliability of the cable system of a drum shearer machine was studied and analysed using operation and maintenance data from an Iranian mine for a period of two years. The tests for trend and serial correlation show that the times between successive failures for the cable system are not independent and identically distributed. A goodness-of-fit test shows that the power law process model provides a good fit to the failure data of this system. After parameter estimation for the power law model, reliability and failure rate plots were obtained. Based on analysis and results, a period of 125 h was defined as the reliability-based maintenance interval for the cable system of the shearer. The analysis shows that, by using this strategy, the reliability of the system will improve by at least 50%.

Reliability-based maintenance scheduling of haulage system of drum shearer

Drum shearer is the most important component of production chain in longwall mining. This machine is driven along the face by a powerful haulage system. In this paper, the reliability of haulage system of shearer has been analysed. The result showed that Time Between Failures (TBF) data of this system obeys the three-parameter Weibull distribution. On the basis of the achieved reliability model, the Preventive Maintenance (PM) scheduling has been suggested for different reliability levels. The reliability-based maintenance intervals for 90, 80, 70 and 50% reliability are 19.4, 35, 49 and 96.8 h, respectively. If 35 h are considered as the PM intervals, mean TBF will be increased by 16.2%.

Prediction of rock fracture toughness modes I and II utilising brittleness indexes

Fracture toughness and brittleness are of the most crucial rock features for underground excavation and drilling in rock mass. Developed standard tests to determine rock fracture toughness are very difficult as well as time consuming; furthermore, they require high-level accuracy during sample preparation and testing. An attempt has been made to propose simple relations to determine fracture toughness modes I and II based on brittleness indexes B1, B2 and B3 in this paper. The data for regression were gathered from the literature, including modes I and II fracture toughness, uniaxial compressive strength and tensile strength. It was obtained that both fracture toughness modes I and II of different rock types give reasonable correlations with brittleness index B1. No correlation was observed between fracture toughness modes and other brittleness indexes.

RELIABILITY-CENTERED MAINTENANCE FOR SPRAY JETS OF COAL SHEARER MACHINE

Spray jets constitute one of the most important parts of each type of rock cutting machine, especially the drum shearer. This system cools the cutting picks and controls the dust emission. The blockage of spray jets causes the coal shearer machine to stop automatically. Therefore, the reliable performance of this system assists the achievement of a smooth coal cutting operation. Fields data shows that the maintenance of this system is time-consuming and causes major downtimes in the production process. Therefore, it is essential to find an optimum preventive maintenance task and intervals, to reduce the downtime and minimize the associated costs of the machine. The aim of this paper is to identify an applicable and effective maintenance task, with its associated interval, for management of the failure modes of the spray jets of coal shearers. A case study has been conducted on spray jets of double-drum shearer machine in Tabas Coal Mine in Iran. In the study, the RCM approach is used to select an applicable and effective maintenance task. The failure data were analyzed using a parametric approach to evaluate the reliability of the spray jets, and to estimate the reliability parameters. A reliability-based cost modeling has been implemented to identify the optimum maintenance interval and frequencies of restoration for the spray jets. In the study, a cost rate function (CRF) has been introduced in which an as-good-as-new (AGAN) effectiveness for restoration actions is considered. The CRF also considers restoration and repair times, and takes into account the costs associated with repair and restoration, and the opportunity cost of the equipments lost production due to maintenance downtime, to arrive at the most cost-effective maintenance intervals. The results of the analysis have shown that the minimum cost per unit of time,

A fuzzy logic based classification for assessing of rock mass drillability

46.5/h, will be achieved within a range of intervals i.e., T = 210 h to T = 260 h.

Comparison and analysis of burden design methods in blasting: a case study on Sungun copper mine in Iran

This paper describes a fuzzy classification system for evaluating of rock mass drillability. Six parameters; Uniaxial Compressive Strength (UCS), joints dipping, Mohs hardness, joints aperture, joints spacing and grain size have been used. In this fuzzy system, each rock mass is classified into five modes from very poor to excellent condition. As a case study, 15 rock masses in two mines in Iran have been studied and classified using fuzzy system and classic classification. The comparison of the results shows that the fuzzy classification produces clearer results than classic system especially in rock masses with boundary condition.

A new classification system for evaluating rock penetrability

In this study, 19 burden designing methods have been analysed for burden design in the Sungun Copper Mine in Iran. Also, economical Optimum Burdens (OBs) have been calculated using the results of actual blastings. The results of mentioned methods and optimum burden have been compared with each other. The comparison shows that the Anderson, Pears, Allsman, Langefors and Energy Transition (ET) methods have very close results to the OB. Also, the results of Fraenkel, Ash, Foldesi and Prillet methods are very different from the OB. Therefore, earlier methods could not be used in burden designing for open pit mines.