Limestone Extraction Without Drilling and Blasting

10 December, 2018

First published in the December 2018 issue of Quarry Management as Surface Mining

Limestone extraction without drilling and blasting – Wirtgen surface miners play a key role in increasing production and reducing costs for a large cement plant in western Ukraine

PJSC Ivano-Frankivskcement (IFCEM), based in Yamnytsya, in western Ukraine, produce cement clinker and around 300 other cement and gypsum products for use in construction. The raw material for the company’s cement plant comes from a limestone deposit located some 15km north of Yamnytsya – in a part of the Carpathian mining area that is rich in sedimentary rocks such as limestone, marl and gypsum.

For years, the limestone was extracted by drilling and blasting and then wet processed into clinker in the cement plant. In a move to increase productivity and reduce costs, IFCEM became the first cement plant in the Ukraine to initiate the transition from the wet process to a dry process, a measure that optimized the mining method for material supply.

The dry process is now considered the preferred method for clinker production as it reduces fuel consumption per tonne of material. This, in turn, has a positive effect on production costs and the environment. For an optimal dry process, the material from the quarry should have a low moisture content so that it can be crushed in a dry crusher, ground to powder in the raw mill and burnt in the rotary kiln without further pre-treatment.

To ensure that the material extracted from the quarry is as dry as possible, a radical change in the mining method was necessary. At the same time, the use of explosives for limestone extraction was having a detrimental effect on neighbouring residential areas due to the noise and ground vibrations it generated. IFCEM found the solution in Wirtgen surface miner technology. In 2012, the company purchased a 2200 SM machine, followed by a second, identical model in 2015 and then, last year, a 2500 SM.

By gradually phasing out the drilling and blasting operations, the surface miners progressively reduced the time and cost involved in pre- and post-crushing the material, and also made it possible to redesign the limestone deposit working area. By ensuring a defined surface slope, with the aid of the Level Pro automatic levelling system, the surface miners created the conditions for efficient dewatering.

Compared with drilling and blasting, this allows much drier raw material to be mined and the material can enter the plant’s drying process without any further treatment. Thanks to the redesign of the mining area, exploitation of the deposits has also been increased, as previously unused areas can now be worked and additional material extracted.

This increase in mining volume had a major influence on the selection of the third surface niner machine. After impressive results with the smaller Wirtgen 2200 SM with its 2.2m cutting drum and maximum cutting depth of 300mm, the technical management of Ivano-Frankivskcement opted for the more powerful 2500 SM model.

Together, the three Wirtgen surface miners generate a daily output of 7,000 tonnes, which results in optimum utilization of the cement plant. The 2500 SM has made an important contribution to this, as well as to increasing production in the quarry, where the limestone has a uniaxial compressive strength of between 20MPa and 70MPa depending on its depth. The 2500 SM, which has already clocked more than 4,500h, is equipped with a 2.5m-wide cutting drum fitted with cutting tools on an HT 15 quick-change tool-holder system. The HT 15 reduces the time required to replace the tool-holder from 90min to 15min, compared with conventional welded tool-holder systems.

The 2500 SM, which is capable of removing material to a maximum depth of 650mm, extracts the limestone to a depth of 400–450mm. Depending on the rock’s hardness, the surface miner achieves a feed rate of 5m per minute at a grain size of 0–100mm, with the entire tooling arrangement being replaced at varying intervals between 200h and 500h, depending on the application.

Since its market launch, the 2500 SM has proven its performance and flexibility worldwide, as it can be used for the selective mining of raw materials with uniaxial compressive strengths up to 80MPa – and in special cases even higher. The surface miner cuts, crushes and loads the rock in a single operation. Depending on the application, the material can either be loaded directly into trucks via the the machine’s 11.3m long slewing discharge conveyor, discharged laterally or deposited as a windrow between the machine’s crawler tracks. The 2500 SM is powered by a 783kW (1,065hp) engine and delivers precise mining of the mineral thanks to the Level Pro levelling system integrated into the machine’s control system.

The operator sits in a spacious soundproof and dustproof air-conditioned cabin. A video system with several cameras provides a complete overview during the extraction process, ensuring maximum safety. Summing up the advantages, machine operator Svyatoslav Podolyak, who has been driving the 2500 SM since last year, said: ‘This surface miner has an excellent production rate that is even higher than that of the 2200 SM, and that is already very good. Thanks to the clearly arranged instruments, I can see all the important information at a glance. The soundproofed and air-conditioned cabin also gives me an optimal view of the cutting edge and allows me to concentrate on my work in the cold winters and hot summers typical of this region.’

According to Yaroslav Nesterovych Voznyak, technical manager at IFCEM, the surface miners, especially the 2500 SM, have had a positive influence on the production cycle in the quarry and in the cement plant. ‘The purchase of the Wirtgen surface miners made the transition from drilling and blasting to a safe mining process easy to implement,’ he said. ‘In addition to the environmental and production benefits, the surface miners have proven to be the best solution, especially in terms of cost-efficiency and economical operation. The grain size of the material produced is ideal for the cement plant, which is why our fleet of surface miners will grow. We are already preparing a further mining area with a volume of around 180 million tonnes of material, which we want to mine with our Wirtgen machines.’