|With a cutting width of 3.8 m and a cutting depth of up to 350 mm, the 2200 SM 3.8 surface miner deposits the coal it cuts in three windrows behind it.|
The first Wirtgen 2200 SM 3.8 surface miner is being used in the Chinese province of Xinjiang. This new, advanced surface miner is replacing the conventional mining equipment used locally. Wirtgen experts are providing support for the project.
The Yihua Xinjiang Wucaiwan coal mine is situated in the north-west of China near the borders with Russia, Kazakhstan and Mongolia. Contractor Xinjiang Jianyun Engineering Co. Ltd. has been mining coal here for about 18 months. Previously, coal was mined using conventional methods, i.e., drilling and blasting. The blasts, however, were damaging the coal and in some cases igniting it. To increase safety at the mine, the mine operator decided to introduce surface mining as the new mining method. The move improved safety and boosted the cost effectiveness and quality of mining.
“The Wirtgen specialists provided us with in-depth advice right from the start and assisted us in developing the ideal solution,” said Chen Jianyun, the owner of Xinjiang Jianyun Engineering Co. Ltd.
He and Wirtgen first set out the requirements in preliminary talks. The area being mined is 2 x 300 x 35 m so maneuverability was the key factor for the machine in question. Also, the operator wanted to increase production from 3,000 metric tons per day (mtpd) to 7,000 mtpd.
Moreover, the coal is extremely fragile and fine-grained. Consequently, it produces a great deal of dust. Various requirements on the gradation of the cut material and the coal seam (with a thickness ranging from 1.3 to 10.6 m) had to be taken into consideration during the planning stage.
“Once we’d been apprised of the underlying conditions, we advised our customer to use the new 2200 SM 3.8 surface miner. Though based on the same machine concept as the 2200 SM/3800, its production capacity is approximately 25% higher and the specific fuel consumption approximately 15% lower,” said Bernhard Schimm, manager of the mining division for Wirtgen GmbH. The newly advanced machine selectively mines soft rock.
“We scrutinized the results of tests with the prototype of the new 3.8 generation in an Indian coal mine and concluded that the 2200 SM 3.8 ideally fulfils our requirements,” Jianyun said.
The centerpiece of the 2200 SM 3.8 is the 3.8-m-wide cutting drum. It cuts coal or salt with unconfined compressive strengths of up to 35 MPa and deposits the material in three windrows behind the machine. Other benefits are its low fuel consumption, the optimized use of cutting tools and minimized content of fines due to the gentle material transport system. The modified drum speed combined with a reduced cutting depth and travel speed enabled the grain size distribution to be additionally optimized on site and the fines content to be reduced by a further 10%.
Two side plates, which can be raised and lowered hydraulically, reliably seal the cutting drum. With the drum effectively sealed, the formation of dust during milling is reduced considerably. Furthermore, the miner is also equipped with an additional dust protection plate for this application.
The effectiveness of these measures to reduce the formation of dust was already evident during the six-day practical test. The mechanical cutting drum drive system with its three power belts also proved highly efficient on the test site. The virtually loss-free transfer of power ensures maximum efficiency and tremendous daily output rates combined with simple maintenance. Maximum output during selective mining of the coal seam is ensured by three material discharge openings in the scraper plate that allow large quantities of cut rock to be deposited as a windrow. Wheeled loaders subsequently load the material onto trucks independently of the cutting process.
The large steering angle of the smooth hydraulically adjustable all-track steering results in a turning radius of just 2.5 m. The crab steering mode allows rapid maneuvring and the large ground clearance with individually height-adjustable crawler tracks allows operation on uneven terrain and reversing. The selectable hydraulic differential lock ensures optimum traction on any surface. The gradability and longitudinal slope of the surface miner allow it to operate in difficult peripheral areas and to produce separate access roads and ramps, so the 2200 SM 3.8 is also a valuable asset for job site routing.
In Zhundong coal field, the 2200 SM 3.8 works 24 hours a day 330 days a year. “Every minute that the surface miner is not working costs money and minimizes our profit,” Jianyun said. “The knowledge that we could always rely on support from Wirtgen was a key factor in our choice of partner.”