The 280 SMi delivers full performance | Magazine

Wirtgen 280 SMi delivers full performance in the selective mining of different materials.

At the end of 2021, a Wirtgen Surface Miner 280 SMi commenced operation in Kiviõli, an industrial town in northern Estonia. The machine is used for the selective mining of oil shale and limestone. The big advantage? The material is broken down to the required size during cutting, so that it can be used directly for further processing, without additional crushing and screening.

Wirtgen Surface Miner impresses the professionals

The company Kiviõli Keemiatööstus (KKT) has been using a Wirtgen Surface Miner to extract limestone and oil shale since 2006. ‘The selective mining process allows for loss-free oil shale extraction. With the Wirtgen Surface Miner, we can cleanly separate the oil shale from the limestone layers and extract pure, high-quality material. Drilling and blasting do not produce the same quality because the materials get mixed together in the explosion,’ says Mine Captain Dmitrij Nikolaev. The oil shale is used to produce energy, and this requires it to be broken down to a specific size. A Wirtgen Surface Miner can produce the exact grain size distribution right from the beginning of the process, thereby eliminating the time-consuming preparation steps of crushing and classifying that would follow drilling and blasting in conventional raw material extraction methods.

Efficient mining – even when the going gets tough

The 280 SMi extracts limestone and oil shale with compressive strengths of between 30 MPa and 120 MPa. With a milling drum width of 2,750 mm and a maximum cutting depth of 650 mm, the 280 SMi is an efficient rock mining tool. Its central drum design is especially well-suited for the efficient extraction of harder deposit layers. Wear-resistant picks and toolholder systems mean fewer idle times, and the hard-rock cutting drum unit provides maximum durability in hard rock layers. Plus, a variety of automatic functions contribute to operator comfort, reducing the risk of fatigue and assisting in the achievement of high production outputs.

Achieving a top result layer by layer with the 280 SMi

KKT uses the Surface Miner to remove the overburden and selectively extract oil shale. Several metres of overburden must be removed before the oil shale layer is accessible. For this, KKT uses a side casting process; the 280 SMi removes the cut material using a powerful rear-loading slewing conveyor that can be raised and lowered. The material from several lined-up cutting conveyors are deposited onto a windrow. The advantage of side casting is that extraction is separate from loading and transport, simplifying the loading process for excavators and wheel loaders and making the whole process more economical than other methods such as cut-to-ground. This keeps the Surface Miner running at optimal efficiency and eliminates the idle times that come from having to wait for dump trucks.

Here, the oil shale and limestone ratio is 1:3. It is therefore critical to have a machine that can handle materials at different hardness levels. In oil shale layers with a compressive strength of up to 60 MPa, the 280 SMi reaches feed rates of up to 15 m/min at nearly full cutting depth, putting it in the absolute top league in terms of production output.

The limestone in Kiviõli has a UCS of between 60 MPa and 120 MPa and can be very difficult to cut. Nevertheless, the 280 SMi works its way reliably, layer by layer, cutting the limestone at the required production output. The pre-broken limestone is easier to manage during recultivation. Rather than having to carry out the time-consuming process of post-crushing large chunks of rock, as is necessary after drilling or blasting, the cut material can be easily placed into the desired landscape.

Keeping a close eye on sustainability

The Wirtgen Surface Miner’s levelling technology makes it possible to cleanly separate limestone and oil shale layers, ensuring a high-quality product. Additional processing is no longer necessary, thereby reducing carbon emissions. In addition to selectively extracting materials, the precise levelling system also enables effective water balance management in the mine. The 280 SMi Surface Miner creates surfaces with predefined latitudinal and longitudinal tilt to optimize water runoff from the work area. By not using drilling and blasting methods, it is possible to reduce the amount of water that runs down into deeper layers, something that can cause problems in later mining and processing stages. The clean and level work surface also means that trucks approved for road use can be brought in, resulting in significant cost reductions for transportation compared to classic dump trucks.

The Wirtgen 280 SMi defies all challenges

With temperatures plummeting into the double digits below zero and around 100 days of snow per year, this cold region creates special challenges for the Surface Miner and its operators. All the necessary operating agents have to be heated for the machine to operate productively 24/7in the cold over the long term. The large LED light package with its 6-partcamera/monitor system and the rotating (and air-conditioned) panoramic glass cabin provide the operator with a comfortable view in all directions, both day and night.

KKT is impressed by quality from Wirtgen

KKT chose to purchase a new Wirtgen280 SMi because they found the Surface Miner to be the absolute best and most efficient side casting extraction technology available to them. The Wirtgen 2500 SM, which they have been using since 2012 and which has logged over30,000 hours of operation, has gone into well-earned retirement.