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.