JAN-FEB 2018

Best of Germany 2014 - Mining Equipment and Mining Technology

Issue link: https://vdma.epubxp.com/i/951969

Contents of this Issue


Page 23 of 51

VDMA 22 VDMA MINING SUPPLEMENT • 2018 holders are mounted onto the drum in a job-specific layout. Number of picks, pick spacing, and pick design are a few of the parameters that are designed to the conditions on the mine site and desired project deliveries, e.g., particle size distribution or cutting rates. In the development of the cutting drum for the New Acland proj- ect, the engineers had to design the Surface Miner to cut both coal and rock partings. On the direct-loading machine, the tool holders are mounted in a helix layout to pull the material toward the mid- dle of the drum. The cutting depth can be adjusted to follow the coal-rock interface, down to 830 mm. A scraper is located behind the cutting drum and from there the material is transported onto a primary conveyor, which transfers the material onto the discharge conveyor that slews 180° with an adjustable height. It can load haul truck easily and efficiently while minimizing dust emissions. The conventional mining system consisted of dozers and a wheel loader for loading rock and coal into the 130-mt to 190-mt haul trucks. This dozer-assisted, truck-and-shovel operation has been well developed over the years at New Acland. The dozer oper- ators have extensive experience and achieve good loss and dilution figures. New Acland, however, wanted to improve recovery and fur- thered reduce coal loss and dilution. A change in the mining process can be risky and uncertain so New Acland opted for a four-month trial. For the successful imple- mentation of new technology, it is important to take a whole-of- process view, which requires cooperation between the divisions. KPIs of the Surface Miner trial were not only limited to productivity and mechanical availability, but also addressed impacts across the whole process chain. An example is the particle size distribution (PSD), particularly fines generation. During the commissioning of the surface miner, New Acland and Wirtgen jointly conducted an extensive comparison of the gradation of the specified coal. To this end, Wirtgen supplied a tracked MS 19 triple-deck screening plant from Kleemann to analyze the grain sizes of the 5-mm to 150-mm fractions and a laboratory screening plant to analyze the grain sizes of the fractions between 0.5 mm and 5 mm. A total of 100 individual 30-ton samples were analyzed. The samples for the conventional mining equipment and the 4200 SM were taken from identical mining fields, which were divided into two for this purpose. The Wirtgen Surface Miner was tailored to mine-site specifica- tions and arrived at the mine site in May 2014 and was commis- sioned within two weeks of arrival. The implementation of the new mining system required some adjustments to the traditional block mining system. The Surface Miner cuts lanes alongside each other. At the end of each cutting lane, it cuts its own ramp and turns around 180° to start the next lane. The cutting lane length is a major parameter influencing productivity. With increasing cutting lane lengths, the fraction of operating time spent turning around decreases while actual cutting time increases. To enable an efficient surface mining operation, it is recommended to operate the 4200 SM in blocks of more than 300 m. New Acland's conventional mining method oper- ated in 150-m x 150-m blocks. So multiple traditional mining blocks were added together to create a mining area of up to 600 m, allow- ing the Surface Miner to operate efficiently. An in-depth trial program, designed around the KPIs, formed an essential part of the implementation process. They were categorized as performance; health, safety and environment (HSE); financial and downstream impact. Most of the KPIs refer to the continuous mining system employed. The KPI for fines generation was defined as "fine coal generation less than 2 mm not to exceed limitation of dozer/loader system." Operators with no previous experience were trained to operate the 4200 SM. A ramp up was applied to some KPIs to account for that training. During a period of four months, performance of both mining systems was measured and compared against each other. The assessment revealed that about 70% less machines would be required for the Surface Mining system compared to the conven- tional ripping, stacking and loading system. The 4200 SM has less impact on the environment, less equipment resulted in less emis- sion of noise, vibration and dust. The fuel usage per volume mined material was around 65% lower with than the traditional method. The operators experienced a number of ergonomic benefits as well. Optimized Methods for Moving Ore After successfully installing two gearless conveyor projects in Peru (Antapaccay and Las Bambas), Siemens completed the world's big- gest installation of a direct conveyor drive system. In this modern- ization project, the belt conveyor replaced the railway system that was previously used to transport ore from the mine to the processing plant. The conveyor consisted of three individual sections equipped with a total of five integrated drive systems. For the largest of the belt sections, Siemens supplied two gearless drive systems with an output of 6,000 kilowatts each. Siemens is also supplying a new conveyor system with gearless and conventional drives to thyssenkrupp Industrial Solutions for the Oyo Tolgoi underground copper mine in Mongolia. The new system New Acland participated in a four-month trial that compared the use of a Wirtgen Surface Miner against its traditional mining techniques and realized several benefits with the new system.

Articles in this issue

view archives of VDMA - JAN-FEB 2018