Peak Performance in Estonia – Selective Mining with the 280 SMi | Magazine

The Wirtgen 280 SMi Delivers Peak Performance in the Selective Mining of Different Materials

At the end of 2021, the first Wirtgen Surface Miner 280 SMi commenced operation in Kiviõli, an industrial town in northern Estonia. The machine is being 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 without the need for additional crushing and screening.

Wirtgen Surface Miners Impress Industry Experts

The Estonian company Kiviõli Keemiatööstus (KKT) has been using Wirtgen Surface Miners for the extraction of 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 exceptionally pure materials of the highest quality. Such high quality cannot be achieved with drilling and blasting, 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 elaborate processing steps of crushing and classifying that would follow conventional extraction of primary resources by drilling and blasting.

Efficient Mining – Even When the Going Is Tough

The 280 SMi extracts limestone and oil shale with compressive strengths of between 30 and 120 MPa UCS. The 280 SMi is an efficient mining tool with a milling drum width of 2,750 mm and a maximum cutting depth of 650 mm. Its central drum concept is especially well-suited for the economical extraction of harder deposits. 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.

Top Quality, Mined Layer-by-Layer with the 280 SMi

KKT uses the Surface Miner to strip off the overburden and selectively extract the oil shale. Several meters of overburden must first be stripped off to expose the oil shale horizon. For this, KKT uses the side casting method; the 280 SMi removes the cut material and deposits it precisely by means of a high-performance, height-adjustable rear discharge conveyor that can be slewed to either side. The material cut from several adjacent strips is deposited in a windrow. The advantage of side casting is that extraction is separate from loading and transport, which simplifies material loading for wheel loaders and excavators and makes the whole process considerably 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 otherwise result from having to wait for dump trucks.

Here, the ratio of oil shale to limestone deposits is 1:3. It is therefore critical to have a machine that can handle materials of different hardnesses. In oil shale layers with a hardness of up to 60 MPa the 280 SMi achieves feed rates of up to 15 m/min at close to full cutting depth, which makes it a major league player when it comes to production performance.

The limestone in Kiviõli has a hardness of between 60 MPa UCS and 120 MPa UCS and can be very difficult to cut. Despite this, the 280 SMi continues to work reliably layer-by-layer, cutting away the limestone at the required production rate. The pre-broken limestone is easier to handle during recultivation measures. Rather than having to carry out the laborious process of post-crushing large chunks of rock, as is necessary after drilling or blasting, the cut material can be very easily processed to achieve a form suitable for further use.

Sustainability Is Always an Important Issue

The WirtgenSurface Miner’s leveling technology makes it possible to cleanly separate limestone and oil shale layers and ensure high product quality. Additional processing is no longer necessary, thereby reducing CO₂ emissions. In addition to the selective extraction of materials, precise leveling also enables optimum regulation of the water balance at the mine. The Surface Miner 280 SMi creates surfaces with predefined cross slope and longitudinal slope to optimize the drainage of water from the working area. Eliminating the need for drilling and blasting also reduces the seepage of water into deeper layers, which can cause problems in later mining and processing stages. The clean and level working area also allows transportation with trucks approved for use on public roads, resulting in significantly lower transport costs as compared to classic dump trucks.

The Wirtgen 280 SMi Masters All Challenges

With temperatures reaching into the double digits below zero and around 100 days of snow per year, this cold region presents special challenges for the Surface Miner and its operators. All the necessary fuels and lubricants have to be heated for the machine to operate productively 24/7 in the long and cold winter season. The large LED lighting package with its 6-part camera/monitor system and the rotatable, air-conditioned cabin with all-round glazing ensure that the operator has an ideal overview of the machine and the working environment when working during the day and at night.

KKT Is Impressed by the Quality of the Wirtgen Surface Miner

KKT chose to buy a new Wirtgen 280 SMi because they found that a Surface Miner using the side-casting method to be the absolute best and most efficient extraction technology, and also because the time had come to send the Wirtgen 2500 SM that had served them so well since 2012 into a well-earned retirement after logging over 30,000 operating hours.