Abstract
dc:descriptionThis doctoral thesis deals with the recent development of a longwall simulation tool for analyzing shearer operations and estimating hourly and annual production output. In most cases longwall mining refers to underground coal extraction processes. Coal is mainly used for electricity and steel production. Therefore, the coal resource made a major contribution to the Total Primary Energy Supply - having an approximately one quarter share right after the oil, which provided nearly one third of the consumed energy in 2005. Compared to other fossil fuels, coal has the largest amount of proven mineral resources, which makes the average global coal production last for at least 137 years as estimated in 2006. Coal consumption is predicted to increase from 5.3 Gt by approx. 1.8% per year on an average within the next 24 years. As parts of the expected amounts of mineral resources will be proven global coal mining is predicted to continue even for the next 160-190 years. Coal mining is divided into surface mining (approx. 40%) and underground operations (approx. 60%) which are drilling and blasting, room and pillar with continuous miners as well as shearer and plow longwall systems. Almost one third of the coal coming from deep mines is extracted by longwalls. Their main advantage is high productivity combined with low fatality numbers. Longwalls’ share is expected to increase as safety and productivity is getting more and more important. Shearer longwall systems consist of the Shearer to extract and load the coal onto the Armored Face Conveyor (AFC), the AFC for conveying the coal to the main gate and the roof supports to protect miners and machinery from falling rock. Currently, there are five common shearer cutting methods which differ in cutting height and cutting web per shearer’s pass. This results in different capacities and mass flows on the conveyor belts. According to those cutting methods, the Excel based algorithm divides the shearer movement into single steps along the coal face by calculating extracted masses and consumed time whilst taking possible bottle-necks into account like e.g. the cutting motor power. Finally the ratio of extracted coal and cycle time represents the capacity of the longwall system on an hourly basis. Considering the longwall crews’ schedule as well as machine availability, an annual output is estimated. This simulation tool is able to uncover system bottle-necks and it provides the user with expected production increase if one bottle-neck is removed. Additionally, it visualizes coal load on the belts which enables users to analyze their conveying systems. A second implemented shearer simulates two parallel running longwalls conveying coal on one common belt. The second machine can be operated in an automatic mode that corresponds to the first longwall’s coal load reaching optimized belt utilization. The software was calibrated and verified in a coal mine of the Appalachian-Region. The following figures were calibrated: specific required energy for cutting and loading the coal, required pulling forces at the face and friction factors of upper and lower AFC races. The verification procedure contained a comparison of real and virtual shearer movements as well as a comparison of the real and calculated amount of coal coming from one shearer’s pass. As a result of this study, a negligible difference of less than 6 % was detected in calculated and real mine data over an almost six week period. With regards to most of the evaluation criteria, the software performance is either good or excellent, particularly the distinguished precision. Only disadvantages are a less flexible algorithm and some unfavourable settings regarding maintenance and software extension while working with Excel. Fields of further software development are the shearer drum design, the roof support, the ventilation system and the longwall development which can be limiting factors to the shearer speed. The algorithm should also be updated for the latest inventions of cutting very large seams by utilizing Longwall Top Coal Caving methods and mining very low seams with longwall plow systems. Object oriented programming is regarded as the new software basis which tends to match better than Excel does regarding flexibility and user-friendly interfaces. To summarize: the described simulation tool is unique and can save a lot of time and money. It has outstanding capabilities in uncovering improvement potentials of shearer longwall systems that can be achieved only by changing cutting methods instead of installing bigger motor power.
Degree
thesis:*- Grantor dc:publisher
- Publikationsserver der RWTH Aachen University
- Year dc:date
- 2009
Author and committee
dc:creator, dc:contributor.*- Author dc:creator
-
- Lange, Ulrich
- Contributors dc:contributor
-
- Nienhaus, Karl
Subjects
dc:subject × 13Rights
dc:rights- Statement dc:rights
-
- info:eu-repo/semantics/openAccess
- Language dc:language
- ger